News Category: CURE Epilepsy Discovery

CURE Epilepsy Discovery: FCD Genes in Epilepsy, One Piece of the Mosaic

Key Points

  • 2017 CURE Epilepsy grantee Dr. Jack Parent and his team designed a novel system using human neurons grown in a dish to discover the genes behind focal cortical dysplasia (FCD), a common cause of intractable epilepsy.
  • The researchers systematically turned off genes in these neurons, which for some, revealed telltale molecular signs of FCD.
  • These genes included some known FCD genes, as well as six new genes that could also contribute to FCD.

 

Of Needles and Haystacks
A new approach to finding the genes behind Focal Cortical Dysplasia (FCD)

Imagine looking for a needle in a haystack — but without knowing what a needle looks like. This is the kind of diabolical challenge faced by epilepsy researchers seeking to identify the genes involved in FCD.

Marked by brain malformations and seizures, FCD is a common cause of intractable epilepsy. The devastating effects of FCD are wrought by a tiny fraction of the brain’s billions of neurons. These rare-as-needles neurons carry genetic mutations that warp their development and function, making them prone to kicking off electrical activity that creates seizures for the rest of the brain’s haystack of neurons.

Knowing which gene mutations are carried by the responsible neurons would help identify them as needles. In the past decade, studies of brain tissue that has been surgically removed to alleviate seizures in people with FCD have identified a short list of genes that cause these brain malformations. But these do not explain all cases, which suggests other genes remain to be discovered.

Research funded in part by CURE Epilepsy offers a novel strategy for FCD gene discovery that uses human neurons grown in a laboratory dish. In this study, senior author Dr. Jack Parent at the University of Michigan and colleagues designed a way to systematically turn off genes in these lab-grown neurons to see which genes contributed to a hallmark of FCD, specifically elevated levels of a protein called pS6, that distinguishes cells involved in FCD. Though not yet peer-reviewed, the study has been posted to bioRxiv, a preprint repository that enables rapid sharing of results among researchers[1] with the hope that early distribution of the results could facilitate other collaborations to find more FCD-related needles in the haystack.

Their new approach identified six novel genes, two of which have been recently associated with FCD through studies of brain tissue removed from people with FCD.  The researchers found that when these genes were inactivated, the FCD-linked protein levels increased in these cells.

 

 

Mutation Mosaics

The epilepsy research community has made great strides in identifying the genes responsible for some forms of the neurological disorder. The Epilepsy Genetics Initiative (EGI), funded by CURE Epilepsy, has also enabled reanalysis of genetic data to find causes of epilepsy in people who did not initially receive a genetic diagnosis.

But the genetic roots of FCD are harder to discern. That’s because, unlike many genetic diseases, FCD-related mutations are not found in the blood cells surveyed by standard genetic tests like those used for the EGI. Instead, these mutations are solely found in brain cells, and very few of them at that.

This scenario, in which some cells of the body carry a mutation and others do not, is referred to as a “mosaic.” These mosaic mutations are not inherited, but rather come to pass “sporadically” in a developing fetus, when cells divide furiously to produce the many, many cells of the body. Sometimes, genetic mistakes occur and go uncorrected, and these are passed onto new cells made during later cell divisions. In FCD, the cells carrying these mistakes are neurons, and they are interspersed with regular neurons that do not carry the mutation — like a mosaic made from tiles of two colors.

This means that the areas of hyperactivity that a person with FCD has on a brain scan likely harbor neurons with FCD-related gene mutations. Studies of resected brain tissue find that the center of seizure activity is marked by a higher percentage of cells carrying mutations [2].

These neurons may also be misshapen, similar to those observed in brain tissue from people with tuberous sclerosis complex (TSC), a genetic condition that results in tumor growth throughout the body, FCD, and seizures. This similarity gave the first clue that FCD could result from genetic mutations that affect the same processes implicated in TSC. TSC is caused by mutations to two genes, TSC1 and TSC2, which act as tumor suppressors. TSC1 and TSC2 also impact a crucial “housekeeping” pathway inside cells called the mTOR pathway, which controls cell growth, proliferation, and metabolism.

Indeed, other parts of the mTOR pathway have been implicated in FCD in the past decade, based on genetic studies of brain tissue from FCD patients. The associated genes in the mTOR pathway include the MTOR gene, P1K3CA, AKT3, TSC1, TSC2, RHEB, and DEPDC5.

But these genes still do not account for all cases of FCD. Because the mTOR pathway forms a complicated web of interacting components, other causes of FCD may lie within the mTOR pathway itself, or beyond, in yet undiscovered players. The new study by Tidball and Parent took both strategies, by looking in depth at genes belonging to the mTOR pathway, and broadly at the entire genome.

 

Discovery in a Dish

Drs. Andrew Tidball, Jack Parent and colleagues designed a system to explore the effects of turning off genes, one by one, to see if they resulted in a telltale sign of FCD: elevated levels of the pS6 protein, which normally helps initiate protein manufacture in a cell. In FCD, the misshapen cells that drive seizures show high levels of pS6, which is a sign of an overly active mTOR pathway.

Though this kind of experiment could take place in any kind of cell, the researchers wanted to utilize human neurons to better simulate the situation in the brain. Using stem cell techniques, the researchers grew neurons that were transformed from human skin cells in a laboratory dish, where they could be kept alive for days.

To turn genes off, the researchers introduced gene editing tools into human neurons using the Nobel prize-winning CRISPR method. This method provides a way to modify DNA in living cells. Typically, each cell took up a CRISPR molecule that switched off one gene. In all, the researchers probed the effects of over 100,000 of these molecules in over 100 million human neurons.

The researchers evaluated individual neurons for their pS6 protein outputs. Neurons with exceptionally high levels of pS6 resembled FCD cells and were therefore analyzed more carefully. This analysis confirmed some previous FCD genes, like DEPDC5, which reassured the researchers that their dish experiments could tell them something real about FCD biology.

Even more intriguing were the new genes identified. The researchers focused on six of them: HIP1, PIK3R3, LRRC4, EIF3A, TSN, URI1. Notably, two of these — HIP1 and PIK3R3 — were identified last year in studies of brain tissue from FCD patients [3], which further validates this approach.

Just as a busy intersection acts as a hub for multiple roads, the mTOR pathway gathers information from multiple cellular processes, then transforms and sends it out through other routes. Further experiments showed that the new genes influenced both the “before” and “after” of the mTOR intersection: HIP1 and PIK3R3 acted on an input to the mTOR pathway, while the other four genes seemed involved in its outputs. Thus, different disruptions to the network of interacting genes and resulting proteins surrounding mTOR may create multiple paths to FCD.

 

Maximal Impact

These findings could help define what researchers should look for once they obtain precious brain tissue from FCD patients to make a diagnosis. What’s more, this dish method could provide a way to test the effects of any genetic anomalies that turn up in FCD patient brain tissue. Many genetic anomalies are harmless, which means researchers need ways to sort the blameless ones from the FCD-related ones. For example, this method could be used to assess any genetic variants identified from the tiny number of brain cells that remain stuck to electrodes after they have been used to probe seizure sites in the brain while evaluating patients for surgery. Related work by CURE Epilepsy grantees Drs. Gemma Carvill and Elizabeth Gerard at Northwestern University and Dr. Alicia Goldman at Baylor College of Medicine is seeking to find a way to recover DNA from cells left on electrodes to identify the genetic causes of FCD.

 

 

 

Literature Cited:

  1. Tidball AM, Luo J, Walker JC, Takla TN, Carvill GL, Parent JM. Genome-wide CRISPRi Screen in Human iNeurons to Identify Novel Focal Cortical Dysplasia Genes bioRxiv 2023.12.13.571474.
  2. Lee WS, Stephenson SEM, Howell KB, Pope K, Gillies G, Wray A, et al. Second-hit DEPDC5 mutation is limited to dysmorphic neurons in cortical dysplasia type IIA Ann Clin Transl Neurol. 2019 Jul; 6:1338-1344.
  3. Chung C, Yang X, Bae T, Vong KI, Mittal S, Donkels C, et al. Comprehensive multi-omic profiling of somatic mutations in malformations of cortical development Nat Genet. 2023 Feb; 55: 209-220.

CURE Epilepsy Discovery: Researchers Funded to Investigate Cardiac Biomarkers in Epilepsy Thanks to CURE Epilepsy

Key Points

  • A biomarker is something that can be objectively measured, such as protein in blood or electrical activity in the brain and is used as an indicator of abnormal biological activity. In epilepsy, a biomarker could be used to predict individuals with epilepsy who are at a high risk of sudden death.
  • Previous studies have shown the usefulness of cardiac measures such as heart rate and heart rate variability (HRV, or the amount of time between heartbeats) as potential biomarkers for seizures. Dr. David Auerbach at the Upstate Medical University is extending this knowledge to understand if cardiac measures can distinguish between epileptic seizures and functional or dissociative seizures (FDS), also known as psychogenic non-epileptic seizures (PNES). While FDS are not categorized as epileptic seizures, understanding FDS could have an impact on treating and curing the epilepsies.
  • Dr. Auerbach was recently awarded The CURE Epilepsy Cameron Boyce SUDEP Research Award to explore the role of cardiac biomarkers for Sudden Unexpected Death in Epilepsy (SUDEP). His cross-disciplinary work applies techniques from the field of cardiology to epilepsy.

 

Deep Dive

Epileptic seizures (ES) are caused by disturbances in electrical activity in the brain. However, in 20-40% of individuals whose seizures are not controlled by antiseizure medications, seizure activity does not correlate with changes in an electroencephalogram (EEG).[1] These seizures are classified as psychogenic non-epileptic seizures (PNES), also known as functional or dissociative seizures (FDS).[2] Many people with FDS have experienced abuse, trauma, or neglect. FDS can co-occur with depressive disorders, personality disorders, and post-traumatic stress disorders. FDS are often debilitating and are associated with a decreased quality of life, substantial emotional burden, and financial and psychosocial loss.[3,4] There is value to the epilepsy field in understanding and studying FDS for several reasons: first, ES and FDS can co-exist,[5] and second, both ES and FDS can impact the cardiac system, leading to changes in heart rate, arrhythmias, and other abnormalities seen on an electrocardiogram (ECG).[6,7] Disturbances in the autonomic nervous system have been seen in individuals with ES and FDS, and this is especially true in drug-resistant epilepsy and cases of Sudden Unexpected Death in Epilepsy (SUDEP).[8,9]

It is important to be able to differentiate between ES and FDS because the characteristics and treatment options for each differ. Similar to ES, there is a high risk of sudden death in individuals with FDS. Alarmingly, those with FDS have 2.5 times the rate of sudden death compared to the general population.[10] People with suspected FDS may undergo testing in an epilepsy monitoring unit using video EEG, but tests done there can lead to inconclusive results. Not being able to properly diagnose FDS can have many detrimental impacts such as delays in getting proper treatment, and inappropriate or even inadvertently dangerous medical treatment.[11,12] Hence, there is an urgent need to develop ways to diagnose FDS and differentiate ES from FDS.

In a recently published paper funded by the University of Rochester Provost Research Award, Dr. Auerbach’s team applied their knowledge of cardiac biomarkers in the study of the autonomic nervous system and FDS.[1] An important function of the autonomic nervous system is to regulate cardiac activity.[13] One measure of autonomic system function is the heart beat-to-beat variability (also known as heart rate variability, or HRV). HRV is the time between each heartbeat. There is generally some variation in the time between heartbeats; this is considered adaptive because it means that the heart can respond to changes in situations, being ready for either increasing or decreasing the heart rate as needed. The team performed ECG to measure the heart’s electrical activity and track the evolution of HR and HRV, to understand if they could be used to distinguish between ES and FDS.[1] In this study, the authors evaluated the evolution of autonomic function for five hours surrounding seizures; they also developed HR and HRV algorithms to differentiate between ES and FDS.16 The authors found that HR and HRV measures such as the HR after the seizure (“post-ictal HR”), and change in HR before and after seizures (“pre-to-post ictal change”) did indeed distinguish between ES and FDS, and that this effect was specific to convulsive events (i.e., those with a significant physical component), and not non-convulsive, seizures (i.e., those without a significant physical component).[1] By taking inputs and knowledge from the field of cardiology, Dr. Auerbach’s team was able to develop biomarkers for FDS, signaling once again that a holistic, interdisciplinary approach to understanding epilepsy is critical.

CURE Epilepsy has long been leading the charge in funding research on seizure-related biomarkers and is committed to advancing this research as it will have the potential to improve outcomes for people with epilepsy by identifying, for example, who may be at risk for epilepsy after a stroke to who may be at risk for epilepsy following a brain injury to who may not respond to antiseizure medications. By using tools that are new to the field of epilepsy and SUDEP but well-accepted in the field of cardiology, Dr. Auerbach’s team is using funding from The CURE Epilepsy Cameron Boyce SUDEP Research Award to explore potential biomarkers, including cardiac biomarkers that may help predict who is at greater risk for SUDEP. His long-term goal is to develop a risk assessment tool for SUDEP based on various biological markers, including cardiac arrhythmias. Additionally, Dr. Auerbach has recently been awarded a $1M grant by the National Institute of Neurological Disorders and Stroke (NINDS). This grant builds on his previous project looking at a cardiac abnormality known as Long QT Syndrome (LQTS), which showed a link between LQTS and an increased prevalence and risk of seizures.[14] Dr. Auerbach’s scientific work is just one example of CURE Epilepsy’s influence on the field, where supporting a promising scientist early in their career has exponential impact when they go on to gain additional government funding, train new epilepsy researchers, and advance their research which will ultimately impact the millions of people living with epilepsy.

By funding transformational research, CURE Epilepsy continues to be committed to advancing the study of biomarkers within priorities areas including SUDEP and post-traumatic epilepsy (PTE); the organization is poised to make even more progress in the area of biomarkers in 2024.

 

Literature Cited:

  1. Ryan M, Wagner K, Yerram S, Concannon C, Lin J, Rooney P, et al. Heart rate and autonomic biomarkers distinguish convulsive epileptic vs. functional or dissociative seizures Seizure: European Journal of Epilepsy. 2023 Aug; 111: 178-186.
  2. Ertan D, Aybek S, LaFrance WC, Jr., Kanemoto K, Tarrada A, Maillard L, et al. Functional (psychogenic non-epileptic/dissociative) seizures: why and how? J Neurol Neurosurg Psychiatry. 2022 Feb;93:144-157.
  3. Dworetzky B. The Impact of PNES is About More than Counting Events Epilepsy Curr. 2016 Sep-Oct;16:314-315.
  4. Rawlings GH, Reuber M. What patients say about living with psychogenic nonepileptic seizures: A systematic synthesis of qualitative studies Seizure. 2016 Oct;41:100-111.
  5. El-Naggar H, Moloney P, Widdess-Walsh P, Kilbride R, Delanty N, Mullins G. Simultaneous occurrence of nonepileptic and epileptic seizures during a single period of in-patient video-electroencephalographic monitoring Epilepsia Open. 2017 Dec;2:467-471.
  6. Romigi A, Ricciardo Rizzo G, Izzi F, Guerrisi M, Caccamo M, Testa F, et al. Heart Rate Variability Parameters During Psychogenic Non-epileptic Seizures: Comparison Between Patients With Pure PNES and Comorbid Epilepsy Front Neurol. 2020;11:713.
  7. Costagliola G, Orsini A, Coll M, Brugada R, Parisi P, Striano P. The brain-heart interaction in epilepsy: implications for diagnosis, therapy, and SUDEP prevention Ann Clin Transl Neurol. 2021 Jul;8:1557-1568.
  8. Anzellotti F, Dono F, Evangelista G, Di Pietro M, Carrarini C, Russo M, et al. Psychogenic Non-epileptic Seizures and Pseudo-Refractory Epilepsy, a Management Challenge Front Neurol. 2020;11:461.
  9. Müngen B, Berilgen MS, Arikano?lu A. Autonomic nervous system functions in interictal and postictal periods of nonepileptic psychogenic seizures and its comparison with epileptic seizures Seizure. 2010 Jun;19:269-273.
  10. Nightscales R, McCartney L, Auvrez C, Tao G, Barnard S, Malpas CB, et al. Mortality in patients with psychogenic nonepileptic seizures Neurology. 2020 Aug 11;95:e643-e652.
  11. Devinsky O, Gazzola D, LaFrance WC, Jr. Differentiating between nonepileptic and epileptic seizures Nat Rev Neurol. 2011 Apr;7:210-220.
  12. Yeom JS, Bernard H, Koh S. Myths and truths about pediatric psychogenic nonepileptic seizures Clin Exp Pediatr. 2021 Jun;64:251-259.
  13. Huikuri HV, Stein PK. Heart rate variability in risk stratification of cardiac patients Prog Cardiovasc Dis. 2013 Sep-Oct;56:153-159.
  14. Auerbach DS, McNitt S, Gross RA, Zareba W, Dirksen RT, Moss AJ. Genetic biomarkers for the risk of seizures in long QT syndrome Neurology. 2016 Oct 18;87:1660-1668.

CURE Epilepsy Discovery: Leading the Charge on Research and Awareness of Sudden Unexpected Death in Epilepsy (SUDEP)

Key Points

  • Sudden Unexpected Death in Epilepsy (SUDEP) is a tragic outcome defined by premature death in people with epilepsy that is not caused by drowning, injury, or other known causes of mortality.
  • CURE Epilepsy has been a leader in driving awareness and research on SUDEP since 2004, when it started the first private research program to investigate SUDEP and its prevention.
  • CURE Epilepsy has advanced the understanding of risk factors associated with SUDEP which   healthcare providers can use to talk to patients about epilepsy and SUDEP.
  • CURE Epilepsy also commemorates individuals who have passed away due to SUDEP. For example, CURE Epilepsy actively participates in an annual SUDEP Action Day in October, when families and organizations across the epilepsy community come together to raise awareness about SUDEP.  

 

Deep Dive

Sudden Unexpected Death in Epilepsy (SUDEP) refers to deaths in people with epilepsy not caused by drowning, injury, or other known causes of mortality. There is often evidence of an associated seizure, and the death is usually unwitnessed. Unfortunately, SUDEP is underrecognized and underestimated, as coroners and medical examiners may be unaware of the diagnostic criteria that define SUDEP.[1, 2] CURE Epilepsy has been the leading force driving research and raising awareness about SUDEP and since 2004 has funded over 40 projects totaling nearly $6 million to understand the basic biological mechanisms underlying this tragic outcome.   

Former CURE Epilepsy Board Director, Research Committee member, and SUDEP pioneer Jeanne Donalty has been a prominent voice in raising awareness of SUDEP and has worked tirelessly on grassroots approaches for awareness and prevention. Her work was motivated by the loss of her son Christopher when he was 21 years old, the recognition that healthcare providers rarely talked about SUDEP as a potential outcome of epilepsy, and the minimal research at the time in understanding SUDEP. Together with CURE Epilepsy, Jeanne worked with the National Institute of Neurological Disorders and Stroke (NINDS) to help create a “Center Without Walls” called the Center for SUDEP Research (CSR). The CSR employed a range of strategies to explore the causes of SUDEP and identify risk factors that may help prevent it. Former CURE Epilepsy Board Chair and volunteer Gardiner Lapham, who lost her son Henry to SUDEP, was instrumental in the formation of an organization called Partners Against Morality in Epilepsy (PAME). PAME continues to be a driving force in reducing epilepsy mortality by convening an annual conference of diverse stakeholders to discuss epilepsy mortality causes, share research discoveries, and identify means of prevention. CURE Epilepsy is a founding member of PAME and continues to be deeply involved by sitting on the Governance Committee, partnering on annual webinars, and financially sponsoring the annual meeting. 

In addition to advocacy and education, CURE Epilepsy funds innovative research in this field of study. Specifically, CURE Epilepsy researchers have developed SUDEP registries to get a more accurate understanding of the number of people affected, investigated risk factors for SUDEP, and studied the underlying biological mechanisms of SUDEP.   

Impact of SUDEP registries  

A registry is a database of people who have been diagnosed with a certain condition; it can be used to track the outcomes of participants and inform the care of other individuals with the same condition. Dr Elizabeth Donner at the University of Toronto was a recipient of CURE Epilepsy’s 2009 Sudden Unexpected Death in Epilepsy Award. With this funding, she developed a pediatric SUDEP registry in Canada to obtain data on every child with epilepsy who died suddenly and unexpectedly. While previous studies estimated that SUDEP affects 1 in 4,500 children with epilepsy each year,[3] Dr. Donner’s work estimated a much higher number: 1.11 cases of SUDEP per 1,000 children with epilepsy.[4] Her estimate is also in line with another study that made use of the Swedish National Death Registry.[5] Additionally, Dr. Donner and colleagues used the North American SUDEP Registry (NASR) and found that even those with well-controlled epilepsy may be at risk for sudden death.[6] Previous studies had suggested that SUDEP risk was highest in those with treatment-resistant epilepsy; however, the NASR study showed that sudden death can happen to anyone with epilepsy and that it should be discussed with everyone with epilepsy and their caregivers. Specifically, the study revealed that the risk of sudden death appeared to be higher in individuals who had not taken their most recent dose of anti–seizure medication, those who were sleep-deprived, and those with psychiatric disorders.[6]  

Understanding the risk factors for SUDEP  

Dr. Torbjörn Tomson at the Karolinska Institute in Sweden was awarded a CURE Epilepsy grant in 2010, which was supported by the Leisher Family Award. His research involved a large, nationwide study on factors associated with increased risk of SUDEP; his findings confirm previous findings that generalized tonic-clonic seizures (GTCS) are a significant risk factor for SUDEP.[7] He found that individuals with GTCS living and sleeping alone are at significant risk for SUDEP. His work supports the use of seizure-monitoring devices to alert caregivers and the recommendation that people with GTCS should share a room with someone when sleeping whenever possible. Also, any treatments to reduce the occurrence of GTCS or to convert GTCS to non-GTCS could be useful in reducing SUDEP risk.[7] 

Understanding the genetic mechanisms underlying SUDEP    

CURE Epilepsy-funded grantees have investigated a multitude of targets and biological mechanisms in people affected by SUDEP, as well as in experimental animal models. The work of Dr. Annapurna Poduri and colleagues in Robert’s Program[1] at Boston Children’s Hospital explored common, underlying, genetic mechanisms that may be associated with SUDEP and other sudden unexpected pediatric deaths. Her team employed a “trio-based” approach, meaning that the child and their parents were studied to understand genetic changes that may have contribute to sudden unexpected death in these children.[8] Using this approach, many genes that were previously not associated with sudden death were reclassified; for example, genes such as SCN1A and DEPDC5 that are implicated in sudden pediatric death have also been shown to be relevant in SUDEP. Dr. Poduri also examined ten infants who died of sudden infant death syndrome (SIDS) and found that two children had variants of the SCN1A gene, which is also implicated in SUDEP.[9] Genes associated with cardiac issues such as arrhythmia and cardiomyopathy (a condition that makes it harder for the heart to pump blood) were also implicated in SUDEP.[8] In a separate study, CURE Epilepsy Award grantee Dr. Christopher Reid at the Florey Institute of Neuroscience & Mental Health at the University of Melbourne sought to understand the risk between SUDEP and cardiac arrhythmia (abnormal or irregular heartbeat). His team studied a gene called KCNH2, as mutations in this gene are linked to cardiac arrhythmias. His work demonstrated the role of KCNH2 mutations in SUDEP and suggests that genetic screening for KCNH2 could help understand an individual’s risk for SUDEP.[10, 11]

In addition to these and dozens of other scientific studies that CURE Epilepsy has funded and is currently funding on SUDEP, CURE Epilepsy is leading a project to standardize the data collected and reported in preclinical studies to improve transparency and rigor. Epilepsy researchers have an opportunity to comment on the common data elements (CDEs) developed through this project until December 31, 2023, after which CURE Epilepsy will distill and publish these best practices. Over the past 25 years, CURE Epilepsy has funded transformative science and significantly furthered awareness of SUDEP, and the organization will continue to prioritize this important area of research going forward in hopes of eventually preventing this tragic outcome.

 

Literature Cited:

  1. Sudden Unexpected Death in Epilepsy (SUDEP). Available at: https://www.cdc.gov/epilepsy/about/sudep/index.htm. Accessed October 5.
  2. Devinsky O. Sudden, unexpected death in epilepsy N Engl J Med. 2011 Nov 10;365:1801-1811.
  3. Harden C, Tomson T, Gloss D, Buchhalter J, Cross JH, Donner E, et al. Practice guideline summary: Sudden unexpected death in epilepsy incidence rates and risk factors: Report of the Guideline Development, Dissemination, and Implementation Subcommittee of the American Academy of Neurology and the American Epilepsy Society Neurology. 2017 Apr 25;88:1674-1680.
  4. Keller AE, Whitney R, Li SA, Pollanen MS, Donner EJ. Incidence of sudden unexpected death in epilepsy in children is similar to adults Neurology. 2018 Jul 10;91:e107-e111.
  5. Sveinsson O, Andersson T, Carlsson S, Tomson T. The incidence of SUDEP: A nationwide population-based cohort study Neurology. 2017 Jul 11;89:170-177. 
  6. Chloe V, Fizza H, Elizabeth D, Brian DM, Jeffrey B, Dale H, et al. SUDEP in the North American SUDEP Registry Neurology. 2019;93:e227.
  7. Sveinsson O, Andersson T, Mattsson P, Carlsson S, Tomson T. Clinical risk factors in SUDEP: A nationwide population-based case-control study Neurology. 2020 Jan 28;94:e419-e429.
  8. Koh HY, Haghighi A, Keywan C, Alexandrescu S, Plews-Ogan E, Haas EA, et al. Genetic Determinants of Sudden Unexpected Death in Pediatrics Genet Med. 2022 Apr;24:839-850.
  9. Brownstein CA, Goldstein RD, Thompson CH, Haynes RL, Giles E, Sheidley B, et al. SCN1A variants associated with sudden infant death syndrome Epilepsia. 2018 Apr;59:e56-e62.
  10. Bleakley LE, Soh MS, Bagnall RD, Sadleir LG, Gooley S, Semsarian C, et al. Are Variants Causing Cardiac Arrhythmia Risk Factors in Sudden Unexpected Death in Epilepsy? Front Neurol. 2020;11:925.
  11. Soh MS, Bagnall RD, Bennett MF, Bleakley LE, Mohamed Syazwan ES, Phillips AM, et al. Loss-of-function variants in K(v) 11.1 cardiac channels as a biomarker for SUDEP Ann Clin Transl Neurol. 2021 Jul;8:1422-1432

CURE Epilepsy Discovery: Taking Flight Awardee Makes Strides Towards Development of a Biomarker with Implications for Acquired Epilepsies

Key Points

  • Acquired epilepsies can occur as a result of an initiating event such as a brain injury which may include hypoxia that results as a part of cardiac arrest and coma. Currently, it is not possible to predict who will develop seizures after an initial brain injury.
  • Studying brain activity to identify biological signals (biomarkers) may help predict who will develop epilepsy following a brain injury. Yet, deciphering changes in brain activity following an injury remains a significant challenge in the field and thus is a critical area of focus for CURE Epilepsy.
  • Dr. Edilberto Amorim at the University of California San Francisco received a Taking Flight Award in 2020; his research focuses on patients who experienced a coma after cardiac arrest, a population in which brain activity is routinely monitored via electroencephalography (EEG) immediately after the cardiac event.
  • Dr. Amorim’s team identified specific brain activity patterns based on EEG that correlate with good recovery of patients after coma.
  • The work of Dr. Amorim and his team has helped to demonstrate the utility of specific brain activity biomarkers in predicting patient outcomes following cardiac arrest. This work provides insights into changes in brain activity that may be extended to people at risk of developing epilepsy after a brain injury.

 

Deep Dive  

 Acquired epilepsies can result from brain injury such as head trauma or a lack of oxygen (hypoxia) which can occur following a heart attack or cardiac arrest.[1] Often, there is a period of time between the initial injury and the onset of seizures referred to as the “latent” period. During this time, individuals do not experience seizure activity, but a process called epileptogenesis may be at play to change brain activity, making it more hyperexcitable and prone to seizures. This subset of individuals begins to experience spontaneous seizures and develop epilepsy. Knowledge about changes in the brain after the initial injury may provide clues about ways to prevent seizures. A biomarker is a biological factor such as a protein in the blood or brain electrical activity that can be objectively measured and can act as an indicator or even predictor of a normal or an abnormal condition. In epilepsy, a biomarker could provide information on who is at the highest risk of developing seizures following a brain injury.

Research on biomarkers of acquired epilepsies is challenging, however, due to the inherent complexity of different types of epilepsy, the variability that exists between people at risk for epilepsy, and the challenges of monitoring people acutely after an injury that puts them at risk for epilepsy.[2] Knowing the impact that finding biomarkers for the epilepsies could have on patients and families, CURE Epilepsy funds research in this area. Dr. Edilberto Amorim at the University of California, San Francisco practices at the Zuckerberg San Francisco General Hospital, and received a Taking Flight Award in 2020. Taking Flight Awards fund investigators in the field of the epilepsies relatively early in their careers to enable them to develop a research focus and team independent of their mentor(s). Dr. Amorim’s research involves studying brain activity using electroencephalography (EEG) to predict health outcomes in patients who are critically ill. The goal of his research is to develop data-driven approaches to develop personalized therapies. His work builds on previous studies that have identified several EEG patterns that may serve as biomarkers for the epilepsies.[3]

Dr. Amorim’s approach, however, is unique as he studies individuals who are comatose after a cardiac arrest. Since brain activity in these individuals is monitored with EEG soon after the injury, this is an opportune time to study EEG patterns to better understand the evolution of brain activity after an initial injury.[4, 5] It is known that brain activity rapidly change in the first few hours and days following injury [6]; however, while some individuals with abnormal brain activity do not recover from a coma, others do. Dr. Amorim hypothesized that there are clues in the EEG that will correspond to how well a patient recovers after a coma following cardiac arrest. In earlier, smaller studies, his team used machine learning algorithms and found that EEG patterns change over time after a cardiac arrest and that they may be reflective of the functional status of the patient. Hence, they may be used to accurately predict recovery after a cardiac arrest.[7, 8]

Dr. Amorim’s team conducted a multi-center, international study of 1,038 patients who experienced cardiac arrest and coma and collected more than 50,000 hours of EEG data.[9] By developing machine learning algorithms that can identify patterns from a large amount of data, he focused on three domains of EEG activity:

  1. Burst suppression ratio, or a pattern of EEG where extremely high-voltage electrical activity is followed by periods of no activity
  2. Spike frequency, with spikes being discrete events in the EEG signal
  3. Shannon entropy, which is a measure of uncertainty of a certain event or pattern used to characterize complex processes

To correlate EEG patterns to functional recovery, the team looked at cerebral performance category (CPC), a validated way of categorizing the neurological state of an individual after a cardiac arrest.[10] Analysis of the data showed that certain patterns of EEG (namely lower burst suppression ratio, lower spike frequency, and higher levels of entropy) were associated with better functional outcomes, e.g., independence for activities of daily living. Out of these, high entropy states were most informative, as they were associated with better outcomes even in the presence of less-than-ideal spike frequency and burst suppression rates. This suggests that high entropy states may reflect resilience against brain injury and may herald good recovery following coma. The timing of the appearance of certain patterns in EEG was also informative. People with good recovery from coma had earlier and larger improvements in burst suppression ratio and entropy as compared to those with poor recovery. Hence, the different types of EEG patterns that occur early after a cardiac arrest and coma carry important information about the potential to recover from these health crises.[9]

Dr. Amorim’s team has also launched a data challenge competition called the PhysioNet Challenge 2023 to further the field of prediction of outcomes in cardiac arrest, which given the connection to brain function has implications for epilepsy.[11] It is one of the largest disease-specific EEG databases, with more than 50,000 hours of continuous EEG data and is open-access to anyone interested in using the data. Almost 100 teams from all over the world are participating in the competition; more details about this competition can be found here.

By looking at EEG patterns to predict recovery, Dr. Amorim’s work adds to the existing knowledge about what happens in the brain following an injury. His work provides insights on important parameters of brain function to assess immediately following an injury that may be extended to the study of epileptogenesis, the processes that contribute to the generation of seizures.[9] Dr. Amorim’s work gives us clues as to how detailed and precise EEG analysis after cardiac arrest can provide insights into the mechanisms that make a brain susceptible to seizures and acquired epilepsies. A better understanding of what happens in the brain during the latent period after a brain injury brings us closer to developing preventative strategies and personalized treatments for those at risk of developing an acquired epilepsy.[11]

 

 

Literature Cited:

  1. Shorvon SD. The etiologic classification of epilepsy Epilepsia. 2011 Jun;52:1052-1057.
  2. Simonato M, Agoston DV, Brooks-Kayal A, Dulla C, Fureman B, Henshall DC, et al. Identification of clinically relevant biomarkers of epileptogenesis – a strategic roadmap. Nat Rev Neurol. 2021;17:231-242.
  3. Gallotto S, Seeck M. EEG biomarker candidates for the identification of epilepsy Clin Neurophysiol Pract. 2023;8:32-41.
  4. Amorim E, Rittenberger JC, Zheng JJ, Westover MB, Baldwin ME, Callaway CW, et al. Continuous EEG monitoring enhances multimodal outcome prediction in hypoxic-ischemic brain injury Resuscitation. 2016 Dec;109:121-126.
  5. Khazanova D, Douglas VC, Amorim E. A matter of timing: EEG monitoring for neurological prognostication after cardiac arrest in the era of targeted temperature management Minerva Anestesiol. 2021 Jun;87:704-713.
  6. Hofmeijer J, Beernink TM, Bosch FH, Beishuizen A, Tjepkema-Cloostermans MC, van Putten MJ. Early EEG contributes to multimodal outcome prediction of postanoxic coma Neurology. 2015 Jul 14;85:137-143.
  7. Ghassemi MM, Amorim E, Alhanai T, Lee JW, Herman ST, Sivaraju A, et al. Quantitative Electroencephalogram Trends Predict Recovery in Hypoxic-Ischemic Encephalopathy Crit Care Med. 2019 Oct;47:1416-1423.
  8. Amorim E, van der Stoel M, Nagaraj SB, Ghassemi MM, Jing J, O’Reilly UM, et al. Quantitative EEG reactivity and machine learning for prognostication in hypoxic-ischemic brain injury Clin Neurophysiol. 2019 Oct;130:1908-1916.
  9. Amorim E, Zheng WL, Jing J, Ghassemi MM, Lee JW, Wu O, et al. Neurophysiology State Dynamics Underlying Acute Neurologic Recovery After Cardiac Arrest Neurology. 2023 Aug 29;101:e940-e952.
  10. Hsu CH, Li J, Cinousis MJ, Sheak KR, Gaieski DF, Abella BS, et al. Cerebral performance category at hospital discharge predicts long-term survival of cardiac arrest survivors receiving targeted temperature management* Crit Care Med. 2014 Dec;42:2575-2581.
  11. 11. Amorim E, Zheng, W., Lee, J. W., Herman, S., Ghassemi, M., Sivaraju, A., Gaspard, N., Hofmeijer, J., van Putten, M. J. A. M., Reyna, M., Clifford, G., & Westover, B. I-CARE: International Cardiac Arrest REsearch consortium Database (version 2.0). PhysioNet. 2023.

CURE Epilepsy Discovery: CURE Epilepsy’s Efforts Lead to an Increased Understanding of Epilepsy with Eyelid Myoclonia (EEM)

Key Points

  • Epilepsy with eyelid myoclonia (EEM) is a type of absence epilepsy that was formerly known as Jeavons syndrome; its main characteristic is eyelid myoclonia (a brief jerking of the eyelids that may manifest with or without absence seizures).
  • The symptoms of EEM may be confused with ocular tics and many characteristics overlap with other epilepsy syndromes, so this form of epilepsy is routinely misdiagnosed.
  • To better understand the clinical manifestations and treatment of EEM, CURE Epilepsy convened a panel of EEM expert neurologists and individuals with EEM lived experience to summarize existing knowledge, develop consensus about the diagnostic approach and clinical management of EEM and identify areas where further study is needed.
  • Several areas of consensus were identified, e.g., the use of electroencephalogram (EEG) to diagnose EEM, the recommendation for genetic testing if an individual has a family history of epilepsy, and the use of valproic acid as a first-line therapy (except in women of childbearing age) to manage EEM.

 

Deep Dive  

Epilepsy with eyelid myoclonia (EEM), formerly called Jeavons syndrome, is a generalized epilepsy syndrome (meaning that all areas of the brain are impacted by abnormal electrical activity). Onset of EEM is in childhood and affects girls more than boys. There are three main characteristics of EEM; the first and hallmark symptom of EEM is eyelid myoclonia – a brief but intense and repeated jerking of the eyelids followed by the eyeballs rolling up that may be present with or without absence seizures. The second characteristic is eye closure-induced or bright and/or flickering light-induced seizures or EEG paroxysms which are abnormal EEG patterns, and the third is photosensitivity.[1] While seizures in EEM may be as short as six seconds, they typically occur many times a day. Around one-third of people with EEM have a positive family history of epilepsy, and recently, mutations in specific genes have also been found.[1]

Although EEM was first documented in 1977,[2] the condition still is frequently underrecognized and there are delays in diagnosis.[1] EEM is a rare condition and its prevalence (the proportion of people who have EEM at a given time) in people with epilepsy is unclear but past estimates suggest it accounts for up to 2.7% of people seen at epilepsy centers.[3-5] Currently, EEM is diagnosed using routine EEG, and people with EEM have a unique EEG pattern that is characteristic of this syndrome.[6, 7] The average age of onset of EEM is 6-8 years of age [8, 9]; however, the exact time of seizure onset is difficult to establish, as eyelid jerks are routinely discounted as behavioral mannerisms.8 Indeed, the average length of time to diagnosis of EEM is reported to be delayed by as much as 9.6 years,[10] and more than 70% of patients were diagnosed with another epilepsy syndrome [10] or tics.[11] The potential for intellectual disability associated with EEM has been reported. Furthermore, issues such as irritability, anxiety, and psychosis may be seen, but knowledge about intellectual ability and psychiatric comorbidities in patients with EEM is limited.[12]

Current treatment strategies for EEM are informed by small studies; the first line of treatment consists of broad-spectrum anti-seizure medications (ASMs).[13] However, resistance to ASMs is common.[14] While for many individuals EEM persists into adulthood, it is not known whether the clinical characteristics remain the same, change, or worsen with age. 

Recently, the International League Against Epilepsy (ILAE) updated the classification of epilepsy syndromes to include EEM as a generalized epilepsy syndrome of childhood with a genetic cause.[3] This, combined with the recent advances in epilepsy genetics made it an opportune time to revisit the understanding of the syndrome and develop consensus on the approach to clinical diagnosis and treatment of EEM.[13] CURE Epilepsy convened an international steering committee of EEM experts and used a modified Delphi process to survey experts around the world to develop a better understanding of the clinical presentation of EEM and establish best practices for its management.

The committee reviewed current literature and brought together a panel of 25 physicians and five individuals with lived experiences of EEM (patients and caregivers) to participate in the modified Delphi process, which consisted of three rounds of consensus-building surveys. The Delphi method is used in the medical field as a way to gather knowledge in a field, develop consensus or solve a complex problem.[15] This initiative led to three separate publications: a literature review, a summary of the clinical presentation and approach to diagnosis EEM,[13] and consensus on the treatment and management of EEM.[16]

Clinical presentation of EEM:

There was strong consensus among experts that EEM affects predominantly females and that it is a generalized epilepsy syndrome with an onset at three to 12 years of age. There was strong agreement that eyelid myoclonia must be present to make a diagnosis of EEM. The experts reiterated that eyelid myoclonia may go unnoticed for many years before a diagnosis of epilepsy is made. Absence seizures or generalized tonic-clonic seizures are seen with EEM, and EEG is critical for diagnosis. Experts recommend genetic testing when one or more of these factors is present: 1. a family history of epilepsy, 2. intellectual disability, and 3. seizures that do not respond to ASMs (drug-resistant epilepsy).[13]

All patients and caregivers mentioned stress and sleep deprivation as triggers for their seizures; they also reported that the uncontrolled eyelid myoclonia seen in EEM affects them in social and psychological settings (e.g., bullying in school). Given this, there was a strong recommendation that physicians working with people who have EEM should inquire whether their patients are experiencing psychosocial impacts.[13] Since there is not a lot known about psychosocial issues in EEM, it was recommended as an area of further investigation and research.[13]

Medical management of EEM:

In this area, there was strong consensus that valproic acid be used as the first-line treatment and that levetiracetam or lamotrigine be used as alternatives for women of childbearing age. There was strong consensus to avoid sodium channel-blocking medications (except for lamotrigine).[16] It was recognized that seizures usually continue into adulthood and that remission occurs in less than half of patients. The panel also stated that some individuals have a milder course of EEM and that they may not require ASMs at all.[16] Two manifestations of EEM emerged: one group of individuals had seizures at an earlier age, exhibited intellectual disability, and had more frequent generalized tonic-clonic seizures and/or drug-resistant epilepsy. In contrast, individuals with seizures starting at a later age and who did not have intellectual disability were likely to respond to ASM therapy.[16] For issues such as driving there was no consensus among panelists about whether patients with uncontrolled eyelid myoclonia alone should be advised not to drive, but there was a strong consensus that EEG should be used when making determinations about driving candidacy as interictal epileptiform discharges on EEG have been shown to affect driving ability.

In conclusion, the international panel convened by CURE Epilepsy identified areas of consensus regarding the clinical presentation of EEM and ways to optimally manage seizures. Areas of minimal consensus were also revealed; these include the presence of psychosocial issues, matters related to driving, and potential dietary therapies that may be beneficial in EEM. It was also discussed that there may be variability in how EEM is diagnosed worldwide, given that features of EEM are seen in other epilepsy syndromes as well.[8] These topics of further research could inform clinical trials and the development of novel therapies. 

Click here to watch the recording or read the transcript for our webinar on EEM/Jeavons syndrome that took place on September 15, 2023.

 

Literature Cited:

  1. Smith KM, Wirrell EC, Andrade DM, Choi H, Trenité DK, Knupp KG, et al. A comprehensive narrative review of epilepsy with eyelid myoclonia Epilepsy Res. 2023 Jul;193:107147.
  2. Jeavons PM. Nosological problems of myoclonic epilepsies in childhood and adolescence Dev Med Child Neurol. 1977 Feb;19:3-8.
  3. Specchio N, Wirrell EC, Scheffer IE, Nabbout R, Riney K, Samia P, et al. International League Against Epilepsy classification and definition of epilepsy syndromes with onset in childhood: Position paper by the ILAE Task Force on Nosology and Definitions Epilepsia. 2022 Jun;63:1398-1442.
  4. Jonsson P, Eeg-Olofsson O. 10-year outcome of childhood epilepsy in well-functioning children and adolescents Eur J Paediatr Neurol. 2011 Jul;15:331-337.
  5. Asadi-Pooya AA, Homayoun M. Idiopathic (genetic) generalized epilepsies with absences: clinical and electrographic characteristics and seizure outcome Neurol Sci. 2020 Dec;41:3677-3682.
  6. Giannakodimos S, Panayiotopoulos CP. Eyelid myoclonia with absences in adults: a clinical and video-EEG study Epilepsia. 1996 Jan;37:36-44.
  7. Joshi CN, Patrick J. Eyelid myoclonia with absences: Routine EEG is sufficient to make a diagnosis Seizure. 2007 2007/04/01/;16:254-260.
  8. Striano S, Capovilla G, Sofia V, Romeo A, Rubboli G, Striano P, et al. Eyelid myoclonia with absences (Jeavons syndrome): a well-defined idiopathic generalized epilepsy syndrome or a spectrum of photosensitive conditions? Epilepsia. 2009 May;50 Suppl 5:15-19.
  9. Reyhani A, Özkara Ç. Pitfalls in the diagnosis of Jeavons syndrome: a study of 32 cases and review of the literature Epileptic Disord. 2020 Jun 1;22:281-290.
  10. Smith KM, Youssef PE, Wirrell EC, Nickels KC, Payne ET, Britton JW, et al. Jeavons Syndrome: Clinical Features and Response to Treatment Pediatr Neurol. 2018 Sep;86:46-51.
  11. Madaan P, Jauhari P, Chakrabarty B, Gulati S. Jeavons Syndrome: An Overlooked Epilepsy Syndrome Pediatric Neurology. 2019 2019/04/01/;93:63.
  12. Nilo A, Crespel A, Genton P, Macorig G, Gigli GL, Gelisse P. Epilepsy with eyelid myoclonias (Jeavons syndrome): An electro-clinical study of 40 patients from childhood to adulthood Seizure. 2021 Apr;87:30-38.
  13. Smith KM, Wirrell EC, Andrade DM, Choi H, Trenité DK, Jones H, et al. Clinical presentation and evaluation of epilepsy with eyelid myoclonia: Results of an international expert consensus panel Epilepsia. 2023 Jun 16.
  14. Zawar I, Toribio MGG, Xu X, Alnakhli RS, Benech D, Valappil AMN, et al. Epilepsy with Eyelid myoclonias ? A diagnosis concealed in other genetic generalized epilepsies with photoparoxysmal response Epilepsy Research. 2022 2022/03/01/;181:106886.
  15. Niederberger M, Spranger J. Delphi Technique in Health Sciences: A Map Front Public Health. 2020;8:457.
  16. Smith KM, Wirrell EC, Andrade DM, Choi H, Trenité DK, Jones H, et al. Management of epilepsy with eyelid myoclonia: Results of an international expert consensus panel Epilepsia. 2023 Jun

CURE Epilepsy Discovery: CURE Epilepsy Grantee Makes Strides in the Understanding of Acquired Epilepsies by Investigating Inflammation in the Brain

Key Points

  • In acquired epilepsies, seizures occur as a result of a physical injury, stroke, infection, brain tumor, and various neurological diseases.
  • One way that scientists study acquired epilepsies in the lab is by using an experimental model called the “status epilepticus” (SE) model.
  • In people, SE is a medical emergency characterized by unrelenting generalized seizures lasting more than five minutes and that can be associated with negative cognitive impacts, an eventual epilepsy diagnosis, and even death.
  • One of the hallmarks of SE is inflammation in the brain that manifests in a variety of ways. The invasion of inflammatory cells called monocytes from the blood into the brain is one facet of the inflammatory cascade.
  • Nicholas H. Varvel at the Emory University School of Medicine received a CURE Epilepsy Award in 2019 to examine whether reducing the invasion of monocytes into the brain could be a therapeutic strategy for SE and potentially other acquired epilepsies.
  • Dr. Varvel’s team found that using a drug to reduce the invasion of monocytes from the blood into the brain minimized the harmful effects of SE, such as a loss in functional impairment and inflammation.
  • Dr. Varvel’s work provides yet another clue to our understanding of acquired epilepsies; with more experiments and evidence, drugs that block monocyte invasion could become a therapy for the prevention and cure of acquired epilepsies.

 

Deep Dive  

“Acquired” epilepsies are those where seizures occur as a result of a physical injury, infection, stroke, brain tumor and other insults to the brain.[1] In past Discovery articles, we shared the work of CURE Epilepsy grantees who are researching in the field of acquired epilepsies, specifically post-traumatic epilepsies (PTE) as part of the PTE Initiative,[2] and understanding neuroinflammation as it relates to epileptogenesis, the process by which the brain starts generating seizures after a brain injury or insult. This month’s Discovery focuses on another cause of epilepsy called “status epilepticus” (SE). Status epilepticus is a medical emergency and is characterized by unrelenting, generalized seizures lasting more than five minutes that have the potential to cause serious and lasting impacts. Indeed, more than 40% of individuals that survive SE go on to develop epilepsy within 10 years of the SE episode.[3]

Status epilepticus can have many deleterious effects on the brain. Hardening (also called “sclerosis”) of a part of the brain called the hippocampus can take place.[4, 5] Additionally, the blood-brain barrier (BBB) – a part of the vasculature of the brain that protects the brain from harmful substances – may erode, letting in molecules that cause inflammation.[6] In acquired epilepsies, certain inflammatory substances known as “cytokines” and “chemokines” may be activated. Additionally, there can be the invasion of inflammatory cells called monocytes from the blood into the brain.[7] Studies in animal models suggest that reducing inflammation can relieve the negative impacts of SE, namely neuronal damage, erosion of the BBB, and behavioral deficits.[8-10]

Dr. Nicholas H. Varvel at the Emory University School of Medicine received a CURE Epilepsy Award in 2019 to investigate if stopping the invasion of monocytes into the brain could be a therapeutic target for SE and potentially other acquired epilepsies. Researchers have shown that monocytes can invade the brain from blood in other neurological conditions, and this formed the basis of Dr. Varvel’s rationale.[11, 12]

Monocytes express a receptor known as CCR2, which mediates their migration from the blood to injured tissues. Previous studies done in Dr. Varvel’s lab showed that using a genetic technique to remove CCR2 prevented the invasion of monocytes into the brain. This technique also reduced inflammation as defined by neuronal damage and erosion of the BBB.[7]  Recent work from Dr. Varvel’s lab explored if using a drug to reduce CCR2 in the days after SE could provide benefits similar to the genetic method. Understanding the consequences of early inhibition of CCR2 immediately after SE might eventually lead to the development of a therapy that could target inflammation and the harmful effects that usually follow.[13]

In this study Dr. Varvel showed the specific involvement of monocytes in SE; blocking CCR2 (a receptor that is found on monocytes) through the use of an orally-administered drug was neuroprotective, as seen by fewer changes in inflammatory markers, the extent of erosion of the BBB, and most importantly, improved functional recovery. Hence, the CCR2 antagonist represents a strategy by which the immediate harmful effects of SE could potentially be reduced. More experiments are necessary to provide definitive answers, but one can envision a therapeutic intervention and future clinical trials, using a CCR2 antagonist that when administered to an individual after SE could reduce its harmful effects and potentially even prevent epilepsy.[13]

 

Literature Cited:

  1. Sirven JI. Epilepsy: A Spectrum Disorder Cold Spring Harb Perspect Med. 2015 Sep 1;5:a022848.
  2. Iyengar SS, Lubbers LS, Harte-Hargrove L, CURE Epilepsy Post-Traumatic Initiative Advisors, Investigators. A team science approach for the preclinical and clinical characterization and biomarker development for post-traumatic epilepsy Epilepsia Open.n/a.
  3. Hesdorffer DC, Logroscino G, Cascino G, Annegers JF, Hauser WA. Risk of unprovoked seizure after acute symptomatic seizure: effect of status epilepticus Ann Neurol. 1998 Dec;44:908-912.
  4. Lewis DV, Shinnar S, Hesdorffer DC, Bagiella E, Bello JA, Chan S, et al. Hippocampal sclerosis after febrile status epilepticus: the FEBSTAT study Ann Neurol. 2014 Feb;75:178-185.
  5. Fujikawa DG, Itabashi HH, Wu A, Shinmei SS. Status epilepticus-induced neuronal loss in humans without systemic complications or epilepsy Epilepsia. 2000 Aug;41:981-991.
  6. van Vliet EA, da Costa Araújo S, Redeker S, van Schaik R, Aronica E, Gorter JA. Blood-brain barrier leakage may lead to progression of temporal lobe epilepsy Brain. 2007 Feb;130:521-534.
  7. Varvel NH, Neher JJ, Bosch A, Wang W, Ransohoff RM, Miller RJ, et al. Infiltrating monocytes promote brain inflammation and exacerbate neuronal damage after status epilepticus Proc Natl Acad Sci U S A. 2016 Sep 20;113:E5665-5674.
  8. Broekaart DWM, Anink JJ, Baayen JC, Idema S, de Vries HE, Aronica E, et al. Activation of the innate immune system is evident throughout epileptogenesis and is associated with blood-brain barrier dysfunction and seizure progression Epilepsia. 2018 Oct;59:1931-1944.
  9. Jiang J, Quan Y, Ganesh T, Pouliot WA, Dudek FE, Dingledine R. Inhibition of the prostaglandin receptor EP2 following status epilepticus reduces delayed mortality and brain inflammation Proc Natl Acad Sci U S A. 2013 Feb 26;110:3591-3596.
  10. Rojas A, Amaradhi R, Banik A, Jiang C, Abreu-Melon J, Wang S, et al. A Novel Second-Generation EP2 Receptor Antagonist Reduces Neuroinflammation and Gliosis After Status Epilepticus in Rats Neurotherapeutics. 2021 Apr;18:1207-1225.
  11. Gyoneva S, Kim D, Katsumoto A, Kokiko-Cochran ON, Lamb BT, Ransohoff RM. Ccr2 deletion dissociates cavity size and tau pathology after mild traumatic brain injury Journal of Neuroinflammation. 2015 2015/12/03;12:228.
  12. Howe CL, LaFrance-Corey RG, Overlee BL, Johnson RK, Clarkson BDS, Goddery EN. Inflammatory monocytes and microglia play independent roles in inflammatory ictogenesis Journal of Neuroinflammation. 2022 2022/01/29;19:22.
  13. Alemán-Ruiz C, Wang W, Dingledine R, Varvel NH. Pharmacological inhibition of the inflammatory receptor CCR2 relieves the early deleterious consequences of status epilepticus Sci Rep. 2023 Apr 6;13:5651.

CURE Epilepsy Discovery: Better Understanding of Post-Traumatic Epilepsy Provides a Foundation for the Development of Novel Therapies

Key Points

  • Post-traumatic epilepsy (PTE) is an acquired epilepsy that develops as a result of a physical injury to the brain.
  • CURE Epilepsy established the PTE Initiative in 2017 and utilized a team science approach to leverage the expertise of six research teams to develop better ways to study PTE in the laboratory, identify biomarkers that may predict risk of developing PTE, and better understand the biological pathways that lead to PTE after injury.
  • The PTE Initiative has led to many scientific successes to date: PTE Initiative teams developed and characterized several different laboratory-based models of PTE, enhanced the understanding of the biological underpinnings of PTE, and identified potential risk factors and potential biomarkers for PTE.

 

Deep Dive  

Last month’s CURE Epilepsy Discovery shared that some epilepsies can be “acquired.” More specifically, in acquired epilepsy, seizures occur as a result of physical injury, infection, brain tumor, or stroke.[1] Post-traumatic epilepsy (PTE) is a type of acquired epilepsy that occurs following a traumatic injury to the brain, for example, as a result of a motor vehicle accident, a fall, a sports injury, or a combat-related injury.[2] PTE may also be accompanied by changes in learning and memory, anxiety, depression, difficulties focusing, and sleep disturbances.[3,4] The risk of PTE following a TBI depends on the type and severity of the injury. PTE caused by traumatic brain injury (TBI) comprises 5% of all epilepsies.[5] In military service members who have suffered injuries, the risk of PTE can be as high as 53%.[6] Current treatment strategies for PTE include anti-seizure medications, but these are not effective in all individuals with PTE and are associated with many side effects. At this point, it is not possible to predict who is at a higher risk for developing PTE after a TBI.

Many issues make PTE a challenging epilepsy to study in laboratories and clinical settings. One of these issues is the process of epileptogenesis, which is the time between the injury and when the brain starts generating seizures and can span days to months or years. Epileptogenesis could provide a unique window of opportunity for intervention, but at present, we do not know enough about this process to develop therapies to halt it in its tracks. Therefore, in order to develop effective treatment strategies to prevent PTE, we need to understand the changes taking place in the brain after TBI and before the development of PTE. Additionally, a PTE biomarker (a biological factor that can be measured through genomic analysis, in blood, or via brain activity that can indicate the potential of developing of PTE) would be especially helpful. Addressing these needs may be best approached in a cohesive effort within the scientific community in order to find effective preventive strategies and treatments for all individuals at risk of this type of epilepsy.

One way of bringing researchers together in an intentional way is through a “team science” approach. Team science is a collaborative effort where different researchers with a breadth of skills come together to solve a single issue, taking advantage of diversity of scientific background, knowledge and expertise.[7] CURE Epilepsy has a track record of funding team science initiatives, such as the Infantile Spasms (IS) Initiative, which brought together eight different research teams across the US  with an array of expertise to advance the understanding of IS and potential treatments. Team science initiatives provide a unique opportunity for transparent and real-time collaboration.[8]

With learnings from the IS Initiative, CURE Epilepsy developed the PTE Initiative with a $10 million grant from the Department of Defense. The main objectives of the PTE Initiative were to improve how PTE is studied in the laboratory and identify biomarkers and risk factors that could help predict who will develop PTE after TBI. The PTE Initiative consisted of six global teams examining various facets of PTE, coming together to collaborate and accelerate discoveries. CURE Epilepsy also convened an External Advisory Committee comprised of thought leaders in the field of PTE to advise the teams on scientific challenges and provide logistical oversight and guidance. CURE Epilepsy led quarterly meetings to share advancements, discuss challenges, and transfer information that helped accelerate learning, especially for early career researchers. In multiple instances, research teams using similar models were able to compare and contrast their methods and data. In another example, an outside group with expertise in machine learning and artificial intelligence joined the EEG focus group and presented ideas to refine EEG analysis. One investigator shared, “Thanks to CURE Epilepsy support we were able to speed up our studies, but especially we could join a very active consortium aimed at discussing hypotheses, sharing data and cross-validating results across preclinical models and patients.”

More information about the specific projects and their impact can be found below:

Dr. Victoria Johnson at The University of Pennsylvania: Using an animal model that mimics certain features of human TBI, Dr. Johnson’s team looked separately at changes in the blood brain barrier (a  layer of cells that protects the brain by blocking most substances from passing from the body’s circulating blood supply into the brain), changes in different brain cells including support cells called glia, and changes in brain activity following TBI. The team also conducted parallel analyses of changes in the blood brain barrier and brain cells in postmortem human tissue from people who sustained a TBI, some of whom developed PTE. Preliminary results from her work also suggest the activation of a specific pathway known as mammalian target of rapamycin (mTOR) following TBI in humans.[9] More about Dr. Johnson’s work can be found here.

 

Dr. Kevin Staley at Massachusetts General Hospital: To better understand why certain individuals develop PTE, Dr. Staley’s team focused on the ways that changes to the extracellular matrix, a network of molecules and proteins that provides support to brain cells, might contribute to the development of PTE following TBI. The team hypothesized that alterations in the extracellular matrix might cause an imbalance between excitatory and inhibitory neurotransmitters and that this imbalance may ultimately lead to seizures. The team found hallmarks of increased excitation in animal models around the time of convulsions.[10] More about Dr. Staley’s work can be found here.

 

Dr. Jeffrey Loeb at The University of Illinois at Chicago: Dr. Loeb’s team studied a condition called subarachnoid hemorrhage, which occurs when there is bleeding in the space between the brain and the tissues that surround the brain and may contribute to the development of PTE.[11] Dr. Loeb’s team employed techniques such as EEG and magnetic resonance imaging to examine subarachnoid hemorrhage in a laboratory model and in humans with a goal of eventually developing therapies for PTE. More about Dr. Loeb’s work can be found here.

 

Dr. Michelle Olson and Dr. Harald Sontheimer at Virginia Polytechnic Institute and State University: This team looked closely at abnormal changes in a certain kind of glial support cell in the brain called an astrocyte. The team set out to develop a novel, more accurate animal model of PTE, and also examine various changes in astrocytes at the cellular, molecular, and functional levels in animals that develop PTE after TBI versus those that do not. More about this team’s work can be found here.

 

Dr. Kevin Wang (formerly at the University of Florida and now at Morehouse School of Medicine): Dr. Wang’s team, working with collaborators at Mario Negri Institute for Pharmacological Research, studied changes in proteins, metabolites and microRNA (a specific kind of genetic material) following TBI in preclinical and clinical samples that may contribute to the development of or predict PTE. Preliminary results from Dr. Wang’s team show changes in specific biological pathways that coincide with epileptogenesis. More about Dr. Wang’s work can be found here.

 

Dr. Pavel Klein at Mid-Atlantic Epilepsy and Sleep Center: Dr. Klein worked with ten clinical research teams in the US and Europe to characterize people who were considered “high-risk” for PTE following severe TBI. As a part of this characterization, the research teams collected blood samples with a goal of identifying biomarkers in collaboration with Dr. Wang and other researchers that may help predict risk of developing PTE. More about Dr. Klein’s work can be found here.

 

Conclusion

CURE Epilepsy’s PTE Initiative has progressed our understanding of epileptogenesis after a TBI, developed animal models to better predict who is at risk for PTE, and moved the community closer to identifying biomarkers for PTE. Research findings are now being advanced through CURE Epilepsy’s newest team science initiative, the PTE Astrocyte Biomarker Initiative. Stay tuned for more details on this exciting new project!

 

Literature Cited:

  1. Epilepsy. Available at: https://www.who.int/en/news-room/fact-sheets/detail/epilepsy. Accessed May 2.
  2. Pitkänen A BT. Head Trauma and Epilepsy. In: Noebels JL AM, Rogawski MA, et al. , editor. Jasper’s Basic Mechanisms of the Epilepsies [Internet]. 4th edition ed. Bethesda (MD): National Center for Biotechnology Information (US); 2012.
  3. Golub VM, Reddy DS. Post-Traumatic Epilepsy and Comorbidities: Advanced Models, Molecular Mechanisms, Biomarkers, and Novel Therapeutic Interventions Pharmacol Rev. 2022 Apr;74:387-438.
  4. Hammond FM, Corrigan JD, Ketchum JM, Malec JF, Dams-O?Connor K, Hart T, et al. Prevalence of Medical and Psychiatric Comorbidities Following Traumatic Brain Injury J Head Trauma Rehabil. 2019 Jul/Aug;34:E1-e10.
  5. Verellen RM, Cavazos JE. Post-traumatic epilepsy: an overview. Therapy. 2010;7:527-531.
  6. Ding K GP, Diaz-Arrastia R. . Epilepsy after Traumatic Brain Injury. In: Laskowitz D GG, editor. Translational Research in Traumatic Brain Injury. Boca Raton (FL): CRC Press/Taylor and Francis Group; 2016.
  7. What is team science? . Available at: https://cancercontrol.cancer.gov/brp/research/team-science-toolkit/what-is-team-science#:~:text=Team%20science%20is%20a%20collaborative,oftentimes%20trained%20in%20different%20fields. Accessed June 6.
  8. Lubbers L, Iyengar SS. A team science approach to discover novel targets for infantile spasms (IS) Epilepsia Open. 2021 Mar;6:49-61.
  9. Iyengar SS, Lubbers LS, Harte-Hargrove L, CURE Epilepsy Post-Traumatic Initiative Advisors, Investigators. A team science approach for the preclinical and clinical characterization and biomarker development for post-traumatic epilepsy Epilepsia Open.n/a.
  10. Lillis KP BB, Martinez-Ramirez L, Normoyle K, Staley K. Intraneuronal and extracellular chloride changes following TBI in a porcine model of post-traumatic epilepsy.  American Epilepsy Society Chicago, USA2021.
  11. Kanner AM. Subarachnoid Hemorrhage as a Cause of Epilepsy Epilepsy Curr. 2003 May;3:101-102.

CURE Epilepsy Discovery: Strides Made in the Understanding of Acquired Epilepsies by CURE Epilepsy Grantees

Key Points:

  • An acquired epilepsy can occur as a result of brain infection, tumor, or injury leading to spontaneous seizures.
  • Little is known about the mechanisms underlying epileptogenesis, the process by which the brain starts generating seizures following an insult or injury.
  • CURE Epilepsy grantee Dr. Annamaria Vezzani at the Mario Negri Institute for Pharmacological Research in Milan has made strides understanding the process of neuroinflammation as it relates to epileptogenesis in acquired epilepsy.
  • Her work on a molecule known as High Mobility Group Box 1 (HMGB1) gives clues as to a potential blood-based biomarker of epileptogenesis and pharmacoresistance (failure to respond to at least two anti-seizure medications (ASMs)).
  • Vezzani’s mentee and continued colleague, Dr. Teresa Ravizza, has also been funded by CURE Epilepsy and continues to drive research to understand the biological mechanisms of acquired epilepsy.

 

Deep Dive

Epilepsy (also referred to as a “seizure disorder”) is a group of conditions characterized by recurrent seizures. Epilepsy can be the result of many different underlying causes including through “acquired” physical injury, infection, brain tumor, or stroke.[1] In acquired epilepsy, spontaneous seizures start after the injury or insult to the brain has occurred. The process by which the brain starts generating seizures after a brain injury or insult is called epileptogenesis. Currently, there is no way to predict who will experience epileptogenesis, and there are no treatments that can prevent or halt epileptogenesis. If there was a way to know that epileptogenesis is taking place or predict who is at risk for it, it might be possible to gain valuable insights into treating and even preventing seizures.

CURE Epilepsy has awarded numerous grants to investigators examining diverse aspects of acquired epilepsies. A few examples of discoveries funded by CURE Epilepsy include Dr. Bruce Gluckman and Dr. Steven Schiff’s development of preclinical models to predict acquired epilepsy following a brain infection, Dr. Gerben van Hameren’s work looking at a particular part of the cell called the mitochondria as a target for post-traumatic epilepsy (PTE), and Dr. Asla Pitkanen’s work that aims to study changes in gene expression in brain tissue in a preclinical model of traumatic brain injury (TBI).

A subset of acquired epilepsies is called PTE, which develops in the months or years following a TBI.[2] TBI may be caused by blows to the head, blasts, penetrating head injuries, accidental falls, sports-related injuries, or motor vehicle accidents. It is currently not possible to predict who will develop PTE after a TBI.[3] Dr. Annamaria Vezzani, head of the Laboratory of Epilepsy and Therapeutic Strategies, Department of Acute Brain Injury at the Mario Negri Institute for Pharmacological Research in Milan, has been an important part of CURE Epilepsy’s efforts to understand acquired epilepsies for decades as an early (2002) and repeat (2015) grantee, and more recently, as part of the PTE Initiative. Dr. Vezzani’s work centers on the role of inflammation in epilepsy. Her work looks at neuroinflammation (i.e., the inflammatory response that is sustained by cells in the brain after insult or injury) and has shown that neuroinflammation can play an important role in the generation of seizures.[4] Through a study funded by CURE Epilepsy, Dr. Vezzani first studied a specific signaling pathway in the brain called interleukin-1 (IL-1) type 1 receptor/Toll-like receptor (IL-1R/TLR4). Her experiments in experimental animals showed that IL-1beta and an inflammatory molecule known as High Mobility Group Box 1 (HMGB1) are released from specific brain cells known as “glia” during seizures.[5] The levels of HMGB1 increased in the brain and the blood before animals developed epilepsy, and this increase in HMGB1 levels was maintained during the development of epilepsy.[6,7] These results gave her precise biological mechanisms that could be targeted to stop seizures.

In addition to showing that HMGB1 is closely involved with seizures, Dr. Vezzani’s work also showed that during an injury or seizures, HMGB1 moves from the nucleus to the cytoplasm of a cell, and this form of HMGB1 can also be measured in blood.[5,8,9,10] More specifically, Dr. Vezzani showed that there is a form of HMGB1 (the disulfide isoform of HMGB1) that contributes to seizures [11]; this finding may inform development of targeted therapeutic strategies. What makes this discovery on HMGB1 particularly exciting for the epilepsy community is its numerous applications: this work could lead to the development of novel drugs to target and halt epileptogenesis, and could also be a way to stop seizures once they have started. As a biomarker, increased levels of HMGB1 could be a sign that epilepsy is about to develop.[10,11] Dr. Vezzani’s work also found that a combination of anti-oxidant drugs that are already used in medical practice is capable of preventing the increase in HMGB1 and delaying the onset of seizures, as well as reducing seizure burden and the memory impairments that are seen in epilepsy.[7]

The role of HMGB1 has also been studied in people with epilepsy. Patients with epilepsy whose seizures were not adequately controlled by ASMs were found to have higher levels of HMGB1 when compared to those who responded to ASMs, and people who did not have epilepsy. Therefore, this work is evidence that HMGB1 can distinguish, with a high level of accuracy, those who respond to ASMs versus those who do not. This adds to the evidence that suggests that HMGB1 can be used as a biomarker for predicting how someone will respond to ASMs.[12] Dr. Vezzani’s more recent CURE Epilepsy-funded work looks at HMGB1 as a target and a mechanistic biomarker of epileptogenesis. HMGB1 is also being studied in people who have experienced TBI as a part of CURE Epilepsy’s PTE Initiative, which funded a diverse group of researchers, including Dr. Vezzani, to develop experimental models to study PTE and discover prediction methods to enable early intervention and eventual prevention.

In addition to her impact and contribution to epilepsy research, Dr. Vezzani is also passionate about mentorship and has guided many mentees who are now established epilepsy researchers in their own right. One of her mentees, Dr. Teresa Ravizza, also at the Mario Negri Institute for Pharmacological Research, received a Taking Flight Award from CURE Epilepsy in 2011. As part of her project, Dr. Ravizza focused on specific cells in the brain known as “astrocytes” and the role of these cells in acquired epilepsies.[13] She also looked at the mechanisms that may contribute to the breakdown of the blood-brain barrier, a network of cells that keep harmful substances from reaching the brain, as previous studies had shown that activation of inflammatory astrocytes along with a breakdown in the blood-brain barrier leads to the generation and sustaining of seizures.[14] Dr. Ravizza’s work hypothesized that the development of epileptogenesis followed by spontaneous seizures is dependent on the extent, duration, and location of blood-brain barrier breakdown. By using a host of techniques, including visualizing the brain by magnetic resonance imaging (MRI), studying the electrical activity of brain circuits, and looking at the behavior of animals, Dr. Ravizza examined whether blood-brain barrier breakdown and glia activation may predict the development of spontaneous seizures and cognitive deficits. Preliminary data support this hypothesis, suggesting that information obtained from these experiments may one day help predict the trajectory of seizures and serve as an effective therapeutic strategy for acquired epilepsies.

Drs. Vezzani and Ravizza continue their work to study neuroinflammation and the underlying mechanisms that may contribute to epileptogenesis. Their work is instrumental not only to understand why and how the brain generates and sustains seizures, but also to discover biomarkers that could predict if someone will have seizures, or how they may respond to a drug. The ultimate hope is that this work with CURE Epilepsy will lead to the ability to prevent or cure acquired epilepsies.

 

 

Literature Cited:

  1. Epilepsy. Available at: https://www.who.int/en/news-room/fact-sheets/detail/epilepsy. Accessed May 2.
  2. Verellen RM, Cavazos JE. Post-traumatic epilepsy: an overview. Therapy. 2010;7:527-531.
  3. Annegers JF, Coan SP. The risks of epilepsy after traumatic brain injury Seizure. 2000 Oct;9:453-457.
  4. Vezzani A, Aronica E, Mazarati A, Pittman QJ. Epilepsy and brain inflammation Exp Neurol. 2013 Jun;244:11-21.
  5. Maroso M, Balosso S, Ravizza T, Liu J, Bianchi ME, Vezzani A. Interleukin-1 type 1 receptor/Toll-like receptor signalling in epilepsy: the importance of IL-1beta and high-mobility group box 1 J Intern Med. 2011 Oct;270:319-326.
  6. Walker LE, Frigerio F, Ravizza T, Ricci E, Tse K, Jenkins RE, et al. Molecular isoforms of high-mobility group box 1 are mechanistic biomarkers for epilepsy J Clin Invest. 2017 Jun 1;127:2118-2132.
  7. Terrone G, Pauletti A, Pascente R, Vezzani A. Preventing epileptogenesis: A realistic goal? Pharmacol Res. 2016 Aug;110:96-100.
  8. Iori V, Maroso M, Rizzi M, Iyer AM, Vertemara R, Carli M, et al. Receptor for Advanced Glycation Endproducts is upregulated in temporal lobe epilepsy and contributes to experimental seizures Neurobiol Dis. 2013 Oct;58:102-114.
  9. Choi J, Min HJ, Shin JS. Increased levels of HMGB1 and pro-inflammatory cytokines in children with febrile seizures J Neuroinflammation. 2011 Oct 11;8:135.
  10. Pauletti A, Terrone G, Shekh-Ahmad T, Salamone A, Ravizza T, Rizzi M, et al. Targeting oxidative stress improves disease outcomes in a rat model of acquired epilepsy Brain. 2019 Jul 1;142:e39.
  11. Ravizza T, Terrone G, Salamone A, Frigerio F, Balosso S, Antoine DJ, et al. High Mobility Group Box 1 is a novel pathogenic factor and a mechanistic biomarker for epilepsy Brain Behav Immun. 2018 Aug;72:14-21.
  12. Walker LE, Sills GJ, Jorgensen A, Alapirtti T, Peltola J, Brodie MJ, et al. High-mobility group box 1 as a predictive biomarker for drug-resistant epilepsy: A proof-of-concept study Epilepsia. 2022 Jan;63:e1-e6.
  13. Vezzani A, Ravizza T, Bedner P, Aronica E, Steinhäuser C, Boison D. Astrocytes in the initiation and progression of epilepsy Nat Rev Neurol. 2022 Dec;18:707-722.
  14. Vila Verde D, de Curtis M, Librizzi L. Seizure-Induced Acute Glial Activation in the in vitro Isolated Guinea Pig Brain Front Neurol. 2021;12:607603.

CURE Epilepsy Discovery: CURE Epilepsy Funds Research to Investigate Mechanisms of Genetic Epilepsies

Key Points:

  •  As part of its quest to find a cure for the epilepsies, CURE Epilepsy has led initiatives, including one focused on genetic epilepsies.
  • The impact of CURE Epilepsy on epilepsy genetics over the years has been broad, ranging from the discovery of individual genes that are associated with epilepsy, to contributions in rare epilepsies, to the Epilepsy Genetics Initiative (EGI).
  • In this CURE Epilepsy Discovery, we highlight the efforts of EGI and the centralized database to store and analyze genetic signatures associated with epilepsy; we also summarize its impact on people living with genetic epilepsies and the epilepsy research community.
  • We then feature three recent CURE Epilepsy grants awardees who have contributed to numerous aspects of genetic epilepsies ranging from the development and application of new technology to study epilepsy genetics, to studying specific genes and their contributions to epilepsy, to exploring the epigenomic pattern associated with epilepsy.
  • The three CURE Epilepsy grants awardees are Dr. Heather Mefford at St. Jude Children’s Research Hospital, and Drs. Gemma Carvill and Jeff Calhoun, both at Northwestern University.
  • Adding to this work is a recent endeavor, the Rare Epilepsy Partnership Award to find cures for rare forms of epilepsies.

 

Deep Dive

Epilepsy occurs when the normal electrical signaling between brain cells (neurons) is disrupted; however, the exact causes of epilepsy are not fully understood. Broadly speaking, epilepsy can have several potential causes, and one of these causes is genetic. Epilepsy is said to have a genetic cause if the seizures are caused as a result of a genetic defect or mutation.[1] These epilepsies are very diverse and the underlying gene or genes involved are not always known. Having a genetic cause for the epilepsies does not necessarily mean that the gene mutation was inherited; sometimes, the genetic variant or mutation may occur spontaneously in a child without being present in either parent; these are called “de novo” mutations.[2] Some epilepsies that have a genetic cause may have additional environmental causes as well.

With the emergence of novel technologies, our knowledge about the genes impacting the epilepsies has grown substantially in the last several years. The increased availability and steadily decreasing costs of genetic technology to analyze one’s entire genetic makeup has meant that scientists can identify many more genes that may be associated with epilepsy. By identifying particular genes associated with epilepsy, we can create animal models to simulate epilepsy in the lab and answer questions regarding the mechanisms by which a particular genetic mutation gives rise to seizures. The ultimate goal of identifying genes associated with epilepsy is to develop targeted therapies for a particular gene.[3] An even more exciting prospect of understanding the genes associated with epilepsy is the prospect of targeting the genes to potentially stop the onset of seizures before it even begins! Understanding the genetic mechanisms of epilepsy is helped by continued advances in genetic technologies, sophisticated ways to store and analyze huge datasets, and the capability to perform experiments in animals and translate findings to the human condition, thus setting the scene for precision medicine in genetic epilepsy.[4]

CURE Epilepsy’s Epilepsy Genetics Initiative (EGI) was formed in 2015 and was instrumental in creating a centralized database that holds the genetic (whole exome sequence) data of people with epilepsy. Whole exome sequencing is a way to analyze a person’s unique DNA fingerprint pattern. By analyzing and re-analyzing genetic data as techniques advance, EGI aimed to advance our understanding of the genetic causes of epilepsy so that clinicians could better and more effectively diagnose, treat, and even prevent genetic epilepsies. Thanks to GI, new genes underlying epilepsy have been found; re-analysis of patient genetic materials has led to new diagnoses for those with genetic epilepsy. Additionally, there have been benefits to the epilepsy community as well. EGI is a community resource, and the whole exome data within the database is available to the research community. All the genetic data are de-identified; hence, there is no way for information to be linked back to a patient or the patient’s family.

In addition to the formation of a centralized database, CURE Epilepsy is also intently focused on identifying and funding cutting-edge research in epilepsy curing the epilepsies. This CURE Epilepsy Discovery article will also outline the work of three CURE Epilepsy grants awardees: Dr. Heather Mefford, her mentee Dr. Gemma Carvill, and Dr. Carvill’s mentee Dr. Jeff Calhoun. By funding these outstanding researchers investigating mechanisms underlying genetic epilepsies, CURE Epilepsy is actively supporting the development of the future generation of epilepsy researchers and scientists.

Dr. Heather Mefford is currently at St. Jude Children’s Hospital and received a CURE Epilepsy Award in 2019. As part of this grant, she investigated the causes of Developmental and Epileptic Encephalopathies (DEE). DEE are severe, early-onset epilepsy disorders that are associated with developmental delay and seizures that are resistant to treatment. A specific genetic cause can be correctly identified in about half of the cases of DEE, and this identification can be associated with a correct diagnosis and a favorable prognosis (course of the disease). Also, a proper diagnosis can help the clinician connect the family to appropriate support groups as well. However, about half of those with DEE are not accurately diagnosed, even with state-of-the-art genetic testing. Work done by Dr. Mefford’s team looked for a different cause in those with DEE that are not diagnosed. Her team looked at abnormal methylation – a type of chemical modification in the DNA structure – in individuals with DEE that did not have a diagnosis or cause. Methylation is considered an “epigenetic” modification – these modifications are not hardwired into one’s DNA, but turn genes “on” and “off.” [5]

Work done by Dr. Mefford’s team has led to the development of “methylation signature” analysis by which methylation patterns of individuals with DEE without a known diagnosis can be studied. Methylation patterns have been studied for other disorders, but not comprehensively for epilepsy. More work is needed to understand the precise methylation signature in DEE; however, the goal is that one day, by diagnosing methylation patterns, we will be able to improve the diagnosis of those with DEE. An accurate diagnosis could also improve the prognosis, and clinicians will be able to accurately offer genetic counseling services to patients and families. There is also the hope of being able to provide targeted precision therapies for these specific methylation patterns.

In addition to recognizing methylation patterns, Dr. Mefford’s team has also been instrumental in characterizing de novo mutations in a gene called PPP3CA and the role of these mutations in causing epilepsy. Since mutations in the PPP3CA gene are very rare, the scientists working on this gene pooled data from different sources including CURE Epilepsy’s EGI. By collecting and analyzing data in this way, Dr. Mefford and her collaborators were able to show that mutations in the PPP3CA gene were a lead factor in the development of specific childhood-onset epilepsy. Dr. Mefford and her collaborators were also able to understand how mutations in the PPP3CA gene cause epilepsy. This gene is responsible for the production of a protein in the brain known as calcineurin; this substance is responsible for key functions in the brain, including proper signaling between neurons. Mutations in PPP3CA interfere with the ability of calcineurin in electrical transmission in the brain leading to neurodevelopmental disorders and epilepsy.[6] Hence, Dr. Mefford’s work funded and supported by CURE Epilepsy is laying the foundation for the study of epigenetics, particularly methylation, in DEE.[7]

In addition to her work as a physician caring for pediatric patients living with severe epilepsy syndromes, and her work as an epilepsy genetics researcher (described above), Dr. Mefford is also passionate about supporting the next generation of epilepsy scientists. One of her trainees, Dr. Gemma Carvill is an independent epilepsy researcher and leads her research program at Northwestern University. Dr. Carvill received CURE Epilepsy’s Taking Flight Award in 2015. The Taking Flight Award was developed to foster and develop the careers of young epilepsy investigators by allowing them to develop a research focus independent of their mentor(s). The Taking Flight Award came at an opportune time in Dr. Carvill’s career and was instrumental in directing her scientific interests in the field of epilepsy genetics.

Dr. Carvill investigated the genetic causes of the most severe forms of epilepsy known as epileptic encephalopathy. Childhood epileptic encephalopathies are a group of epilepsy disorders that are profoundly treatment-resistant; children with this condition also have severe cognitive and neurological deficits.[8,9] Specifically, she was interested in exploring the epigenomic causes of epileptic encephalopathy, i.e., studying genes that turn the activity of other genes “on” or “off”. By using a new genome-editing technology called CRISPR-Cas9 to introduce mutations in a class of genes known as “chromatin remodelers”, she was able to study the mechanisms by which these genes cause seizures.

To study the epigenomic causes of epilepsy, she studied de novo mutations in the CUX2 gene. In an international study done with Dr. Gaetan Lesca of the Lyon University Hospital, Dr. Carvill found mutations in the CUX2 gene in nine patients who started having seizures early in life, had treatment-resistant epilepsy, and severe developmental delay. Since mutations such as the one in the CUX2 gene are rare, several research teams must come together to provide statistical rigor. By identifying mutations in the CUX2 gene in epileptic encephalopathy, this gene can potentially be targeted to develop therapies.[10]

Another work done by Dr. Carvill and her team looked at another epilepsy-associated gene called SZT2. Earlier studies have shown an association between mutations in the SZT2 gene and some neurodevelopmental disorders,[11] but the full extent of the impact of mutations in this gene and its link to epilepsy was not yet known. It is also known that the SZT2 gene plays a critical role in the mammalian target of rapamycin complex 1 (mTORC1) signaling pathway which is essential in cell growth and proliferation. By using state-of-the-art genetic technologies, Dr. Carvill’s team determined that mutations in the SZT2 gene were likely pathogenic and that the mutation is more prevalent in individuals of Ashkenazi Jewish ancestry. The direct implication of these findings is the knowledge that this gene should be included in prenatal gene panels. Given that the SZT2 gene interacts with the mTORC1 pathway, and since the mTORC1 pathway is implicated in other neurodevelopmental diseases as well, there are also implications for potential treatment strategies involving the mtORC1 signaling pathway.[12]

Since receiving the Taking Flight Award, Dr. Carvill has been awarded other accolades also; notably the prestigious Innovator’s Award from the NIH. As part of this award, she will continue her work on genetic epilepsies, specifically exploring if cell-free DNA (cfDNA) could be used as a non-invasive avenue for epilepsy diagnosis and perhaps as a biomarker.[13] At Northwestern University, she too is mentoring a Taking Flight grantee, Dr. Jeffrey Calhoun.

Carrying on the tradition, Dr. Jeffrey Calhoun received the Taking Flight Award in 2022 and his research will look at genetic variants that are linked to the risk for epilepsy. He is developing methods to determine which genetic variants near SCN1A, a gene implicated in epilepsy, alter SCN1A gene expression. This technique eventually could also be used to study variants that impact other genes associated with epilepsy. By understanding the pattern of gene expression and the variants that may cause variable expression, Dr. Calhoun’s work aims to impact the diagnosis and care of those with genetic epilepsies. 

Hence, the work of Drs. Mefford, Carvill, and Calhoun together aim to develop new technologies to better understand genetic epilepsies, which many times, can be catastrophic. In addition to funding Dr. Mefford and her mentees, CURE Epilepsy is making an incredible impact on rare epilepsies, having inaugurated the Rare Epilepsy Partnership Award this year. With this partnership award providing funding for the rare and devasting epilepsies, we can not only provide hope but more understanding that will one day be translated into a cure.

 

Literature Cited:

  1. Scheffer IE, Berkovic S, Capovilla G, Connolly MB, French J, Guilhoto L, et al. ILAE classification of the epilepsies: Position paper of the ILAE Commission for Classification and Terminology Epilepsia. 2017 Apr;58:512-521.
  2. Steinlein OK. Genetics and epilepsy Dialogues Clin Neurosci. 2008;10:29-38.
  3. Szepetowski P. Genetics of human epilepsies: Continuing progress Presse Med. 2018 Mar;47:218-226.
  4. Knowles JK, Helbig I, Metcalf CS, Lubbers LS, Isom LL, Demarest S, et al. Precision medicine for genetic epilepsy on the horizon: Recent advances, present challenges, and suggestions for continued progress Epilepsia. 2022 Oct;63:2461-2475.
  5. What is Epigenetics? Available at: https://www.cdc.gov/genomics/disease/epigenetics.htm. Accessed April 9, 2023.
  6. Myers CT, Stong N, Mountier EI, Helbig KL, Freytag S, Sullivan JE, et al. De Novo Mutations in PPP3CA Cause Severe Neurodevelopmental Disease with Seizures Am J Hum Genet. 2017 Oct 5;101:516-524.
  7. Hebbar M, Mefford HC. Recent advances in epilepsy genomics and genetic testing F1000Res. 2020;9.
  8. Cross JH, Guerrini R. The epileptic encephalopathies Handb Clin Neurol. 2013;111:619-626.
  9. Jehi L, Wyllie E, Devinsky O. Epileptic encephalopathies: Optimizing seizure control and developmental outcome Epilepsia. 2015 Oct;56:1486-1489.
  10. Chatron N, Møller RS, Champaigne NL, Schneider AL, Kuechler A, Labalme A, et al. The epilepsy phenotypic spectrum associated with a recurrent CUX2 variant Ann Neurol. 2018 May;83:926-934.
  11. Kariminejad A, Yazdan H, Rahimian E, Kalhor Z, Fattahi Z, Zonooz MF, et al. SZT2 mutation in a boy with intellectual disability, seizures and autistic features European Journal of Medical Genetics. 2019 2019/09/01/;62:103556.
  12. Calhoun JD, Aziz MC, Happ HC, Gunti J, Gleason C, Mohamed N, et al. mTORC1 functional assay reveals SZT2 loss-of-function variants and a founder in-frame deletion Brain. 2022 Jun 30;145:1939-1948.
  13. Carvill GL. Cell-free DNA sequencing approaches to define the genetic etiology of unexplained epilepsy. Accessed April 9, 2023.

CURE Epilepsy Discovery: CURE Epilepsy Grantee Discovers Specific Alterations in the Inhibitory Neurotransmitter System in Infantile Spasms (IS)

Key Points:

  • Infantile spasms (IS), also called West syndrome, is a rare epilepsy syndrome associated with stereotypical spasms, developmental delay, and a telltale brainwave pattern. Medications used to treat IS are not effective in everyone with IS and are associated with side effects.
  • CURE Epilepsy launched the Infantile Spasms Initiative (IS Initiative) in 2013 with a team science approach to bring together groups of investigators working on diverse topics related to IS; this one-of-a-kind initiative in epilepsy research contributed immensely to today’s understanding of IS and its mechanisms.
  • One of the Initiative’s grantees, Dr. Chris Dulla, developed a mouse model that simulates the neuronal excitation and inhibition relevant to IS. Animal models are incredibly useful to understanding the biological mechanisms underlying IS, and by better understanding the interplay between neural excitation and inhibition in IS, there is hope that we can develop targeted therapies.

 

Deep dive

Infantile spasms (IS) is a devastating and rare epilepsy syndrome that is typically seen in the first year of a child’s life, most commonly between four and eight months of age.[1, 2] One in 2,000 children is affected by infantile spasms, and worldwide it is estimated that one baby is diagnosed with IS every 12 minutes.[3] IS consists of the following characteristics: subtle seizures consisting of repetitive, but often subtle movements—such as jerking of the mid-section, dropping of the head, raising of the arms or wide-eyed blinks; developmental delay and cognitive and physical deterioration; and a signature disorganized, atypical brainwave pattern called “hypsarrhythmia.”[4, 5] Potential causes include brain injuries or infections, issues with brain development and malformations, gene variants, or metabolic conditions. IS can sometimes have an underlying genetic cause as well.[2, 6] Often, infants appear to develop normally until spasms start, but then show signs of regression. Some infants may have hundreds of such seizures a day.

Current treatment for IS consists of hormonal therapy such as adrenocorticotropic hormone and prednisone, and antiseizure medications such as vigabatrin. These medications are effective in approximately half of the patients with IS.[7, 8] Even infants who have been diagnosed in a timely fashion may not respond to the available treatments, or they may suffer adverse side effects. There is no reliable way to predict who will respond favorably to medications.

As there was a dire need to better understand and treat IS, because there was no advocacy group or organization dedicated to IS and no organization was focusing on finding treatments or cures, CURE Epilepsy stepped in and leveraged our expertise as well as our resources to assemble the Infantile Spasms (IS) Initiative in 2013. Committing $4 million, the Initiative brought together eight research teams working on various aspects of IS. [9] Team science” is a unique way of conducting research that leverages the strengths and expertise of scientists trained in different but related fields to solve a single, complex problem. CURE Epilepsy’s IS Initiative was the first team science approach in the epilepsy research community, and teams in the Initiative benefitted from sharing knowledge and resources to expedite understanding of IS. [9] Collectively, the Initiative studied the basic biology that may explain what causes IS, searched for biomarkers and novel drug targets, and explored ideas for improved treatments for the condition. [9]

One of the eight teams involved in the Initiative was led by Dr. Chris Dulla and his laboratory at Tufts University. Dr. Dulla’s team developed an animal model for IS by targeting a gene called Adenomatous polyposis coli (APC). For the epilepsies in general, animal models are crucial to understanding the biological mechanisms that cause seizures. Dr. Dulla’s team developed an animal model for IS by targeting a gene called Adenomatous polyposis coli (APC). Mice that were genetically altered to have a decrease in the activity of APC exhibited many of the features that were reminiscent of human IS.[10] The development of this mouse model (called “APC cKO”) was an important step in IS research as it provided a way for scientists to study IS and the mechanisms that may cause it.

Broadly speaking, there are two kinds of neurons (brain cells): “excitatory” neurons that activate other neurons, and “inhibitory” neurons that restrain other neurons. A fine balance between excitation and inhibition is critical for the brain to function, and in epilepsy, this delicate balance may be disturbed. Inhibitory neurons are modulated by a neurotransmitter called gamma amino butyric acid (GABA). In the current study, Dr. Dulla’s team wanted to study GABAergic neurotransmission in the APC cKO model. Previous studies have shown a link between GABAergic neurotransmission and IS; specifically, alterations in GABAergic transmission have been found in animal models of IS [11, 12] and in human patients with IS.[13] The ultimate goal is to better understand the interplay between excitatory and inhibitory neurotransmission in IS.[14]

In a recent study that was published in February 2023, Dr. Dulla’s team studied inhibitory neurons (also called “interneurons,” abbreviated to “INs”). They looked at a certain kind of interneuron, called a parvalbumin-positive interneuron (PV+ IN) and studied the way these interneurons looked under the microscope (i.e., their anatomy) as well as the way they functioned (i.e., their physiology). In humans, IS has a time course in terms of when seizures start. To recreate this in their mouse model, the team studied APC cKO mice at multiple time points: in infancy (postnatal days 9 and 14), and then later, as adults, and compared them to mice that did not have the genetic mutation (i.e., “wild-type” mice). The goal of the study was to understand what happens to PV+ INs in the APC cKO mouse model of IS.[14]

In normal brain development, an excess of PV+ INs are made, but then they disappear over time. The first discovery Dr. Dulla’s team made was that in APC cKO mice, there is an excess of PV+ IN death. The second important finding was that in APC cKO mice, the death of these PV+ INs occurred earlier in development as compared to wild-type mice.[14] This change in the pattern of death of PV+ INs could mean that there are subtle changes taking place in the neural circuit. Since the primary role of interneurons is to keep brain activity in check, an excess of interneurons dying very quickly may mean that the excitatory neurons run amok. In contrast, other types of interneurons did not show accelerated dying, but this change was specific to PV+ INs.[14] The change in the pattern of PV+ IN cell death in APC cKO mice was also reflected in the functioning of the brain as studied by looking at the electrical activity in the brain.14 The changes seen in the interneuron death and associated function were more pronounced at postnatal day 9 (as compared to postnatal day 14), which suggests that this is the critical period in brain development in this model, when, if GABAergic inhibition is perturbed, may lead to IS and associated symptoms.

In totality, Dr. Dulla’s findings regarding GABAergic neurotransmission and PV+ INs are complicated with respect to the sequence and timing of events. However, there is a variation in the way the inhibitory GABAergic neuronal circuitry develops and matures in APC cKO mice that suggests a critical window of events that if perturbed, may lead to spasms and behavioral impacts later on. This work positions PV + INs as a potential target to treat IS, and perhaps even offers avenues for timely diagnosis.[14] This perturbation of inhibition during a critical period in development may contribute to spasms and seizures later in life. The development of the GABAergic circuitry depends on brain activity; hence, the changes in activity of the neural circuitry seen in APC cKO mice interneurons may contribute to long-term changes in the brain. The exact link between the PV+ IN death in early development and behavioral spasms needs to be investigated in more detail, but this work lays the foundation to continue studying inhibitory transmission in IS. Future studies will reveal if stopping this excess PV+ IN death may be a therapeutic target or a cure for Infantile Spasms.

 

 

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