CURE Discovery: Researchers use “Big Data” to Identify a Protein that Protects Against Epileptogenesis

Key Points

Dr. Avtar Roopra and his team used a “big data” approach to understand how an injured brain may develop epilepsy. To do so, the team analyzed a vast amount of data to identify a protein called EZH2, which determines when thousands of genes are “turned on” or “turned off.”
The research team found that inhibiting EZH2 activity increased the frequency and severity of seizures in rodent models of acquired epilepsy, suggesting that EZH2 protects against the development of seizures and may be a potential new therapeutic target.
Because of this CURE-funded work, Dr. Roopra was able to secure a grant from the National Institutes of Health (NIH) to continue his promising study on EZH2.

Deep Dive

There are many antiepileptic drugs (AEDs) commercially available, but they only treat the seizures rather than cure or even prevent epilepsy. To develop curative or preventative AEDs, researchers must first understand the biological mechanisms underlying epileptogenesis, the process by which an initial “insult” to the brain, such as a head injury or even a period of recurrent seizures, leads to epilepsy.¹ A particularly critical stage of epileptogenesis is called the latent period, a poorly understood span of time between the initial insult and the onset of epilepsy.¹ Dr. Roopra’s CURE-funded project set out to better understand what happens in the brain during this period.²

The researchers turned to a potentially powerful method, which involves identifying possible proteins, known as transcription factors, that activate (“turn on”) or suppress (“turn off”) specific genes. Some transcription factors control thousands of genes and are therefore known as “master” regulators. Unfortunately, finding these master regulators can be a challenging task given the large quantity of genomic data to analyze.

Dr. Roopra’s work overcame these challenges through a collaboration with Dr. Raymond Dingledine’s team at Emory University. They collected data from numerous laboratories and worked together to construct a large database of detailed gene expression profiles³ of brain cells from different rat models of acquired epilepsy, collected at multiple time points during the latent period.⁴ Dr. Roopra’s team then developed a high-powered computer algorithm⁵ to identify potential master regulators from this database.

Using these tools, Dr. Roopra and his team uncovered evidence for increased levels of EZH2 in these samples.² In addition, when the team inhibited EZH2 activity in rodent models of acquired epilepsy, the frequency and severity of daily seizures increased significantly, suggesting that EZH2 serves to dampen seizure activity during the latent period. ²

This discovery could lead to the development of novel treatments that could potentially cure or even prevent epilepsy rather than offer only symptomatic treatment of the seizures.

Since completing his CURE-funded grant, Dr. Roopra and his co-investigators have parlayed their initial results to obtain a much larger grant from the NIH to further explore the role of EZH2 in the generation of epilepsy. CURE is proud to have played a part in propelling Dr. Roopra’s groundbreaking work to the next stage. Such success highlights the importance of funding innovative ideas that one day will lead to developing treatments with “no seizures, no side effects” for every person with epilepsy.

Literature Cited

¹Lukawski, K. et al. Mechanisms of epileptogenesis and preclinical approach to antiepileptogenic therapies. Pharmacol. Rep. 2018; 70(2): 284-293.
² Khan, N. et al. A systems approach identifies Enhancer of Zeste Homolog 2 (EZH2) as a protective factor in epilepsy. PLoS One 2019; 14(12): e0226733.
³ Casamassimi, A. et al. Transcriptome profiling in human diseases: new advances and perspectives. Int. J. Mol. Sci. 2017; 18(8): 1652.
⁴ Dingledine. R. et al. Transcriptional profile of hippocampal dentate granule cells in four rat epilepsy models. Sci. Data 2017; 4: 170061
⁵ Roopra, A. MAGIC: A tool for predicting transcription factors and cofactors driving gene sets using ENCODE data. PLoS Comput. Biol. 2020; 16(4): e1007800.

Your support makes this research possible. Our researchers’ important work continues through the current public health crisis and beyond, thanks to generous donors who, like us, envision a world without epilepsy.

CURE Initiative: Defending Against Post-Traumatic Epilepsy

Post-traumatic epilepsy (PTE) is a seizure disorder resulting from injury to the brain. It is a devastating complication of traumatic brain injury (TBI), which can occur as a result of car accidents, sports-related injuries, or military combat. PTE can develop weeks, months, or even years after TBI, offering a window of opportunity for interventions to prevent seizures. Unfortunately, there is currently no way to predict who will develop epilepsy following TBI, and there are no therapies to prevent it.

CURE’s collaborative, multi-investigator PTE research program aims to develop better models to study PTE and discover methods to predict who is at risk as a way to intervene early and prevent PTE. With a $10 million grant from the US Department of Defense, this initiative brings together leading scientists in the field from around the world. This groundbreaking initiative, which launched in 2018, involves six primary investigators and their research teams for a total of over 60 scientists. To further encourage collaboration and scientific rigor, CURE has contracted with the Laboratory of Neuro Imaging (LONI) at the University of Southern California to create a database to house data from the teams and make it accessible for cross-comparison and analysis.

These teams are enhancing knowledge about PTE by researching what changes occur in the brain, as well as by developing robust animal models to study PTE. In addition, the researchers are investigating how different types of head injury can contribute to seizure onset and occurrence, and they are identifying potential EEG, MRI, or blood biomarkers to predict PTE in humans.

One exciting, ongoing PTE project is led by Dr. Jeffrey Loeb of the University of Illinois at Chicago. Dr. Loeb’s team project will focus on a type of bleeding commonly caused by TBI called subarachnoid hemorrhage. This kind of bleeding occurs when there is blood between the brain and the protective tissue surrounding the brain. By studying both rat models and in-patient instances of subarachnoid hemorrhage, Dr. Loeb’s data-driven approach will hopefully lead to methods or guidelines to help doctors take steps to prevent the development of epilepsy. Check out our recent interview with him to learn more.

We’ve also seen significant achievements over the course of the past two years. These includes a publication from Dr. Harald Sontheimer’s team at Virginia Tech University on a new mouse model for PTE,¹ and a manuscript in preparation by Dr. Victoria Johnson’s team at the University of Pennsylvania on neuropathology in humans after TBI. The investigators have presented abstracts of their work at scientific meetings including the 2019 National Neurotrauma Society meeting in Pittsburgh, PA and the 2019 American Epilepsy Society Meeting in Baltimore, MD.

This collaborative, team-science approach has the potential to develop innovative ways to study PTE, build understanding of the neural mechanisms behind PTE, and ultimately help us understand who is at the greatest risk. This research can pave the way for the development of therapies to prevent and/or treat PTE, having a positive impact on the lives of all affected by TBI and PTE.

¹ Shandra O., Robel S. Inducing Post-Traumatic Epilepsy in a Mouse Model of Repetitive Diffuse Traumatic Brain Injury. J Vis Exp. 2020 Feb 10;(156)

Learn More about PTE

Podcast: Former football star and broadcaster Mike Adamle discusses developing and managing PTE resulting from sports injuries.

Watch or Listen Now

Webinar: Watch a free webinar on what triggers seizures in people who sustain traumatic brain injury.

Watch Now

Podcast: Explore the relationship between TBI and PTE, particularly in Vietnam veterans, in this Seizing Life podcast episode.

Watch or Listen Now

CURE Discovery: Discover the results of an innovative CURE-funded study aiming to find a way to prevent PTE.

Learn More

CURE Discovery: Two Major SUDEP Risk Factors Identified in Nationwide Swedish Study

This grant was generously supported by the Leisher Family Award.

Key Takeaways:

Dr. Torbjörn Tomson’s study confirms previous research suggesting that generalized tonic-clonic seizures (GTCS) are a significant risk factor for Sudden Unexpected Death in Epilepsy (SUDEP)
The study found that for people with GTCS, living and sleeping alone are also significant SUDEP risk factors
The research suggests that treatments to reduce the occurrence of GTCS or to convert GTCS to non-GTCS would be useful in reducing SUDEP risk

Deep Dive:

Dr. Torbjörn Tomson at the Karolinska Institute in Sweden, whose 2010 CURE-funded study was supported generously by the Leisher Family Award, recently published his findings from a large, nationwide study on factors associated with increased risk of SUDEP.¹

For this study, Dr. Tomson and his team analyzed medical records for 255 people who passed away due to SUDEP between July 1, 2006 and December 31, 2011. These SUDEP cases were classified as either “definite SUDEP” or “probable SUDEP”² based on available information. To build a strong understanding of SUDEP risk factors, the investigators compared each case of SUDEP to the medical records for 5 people with epilepsy of the same sex who were alive at the case’s time of death. These individuals served as controls against which to compare factors that might contribute to SUDEP risk. For SUDEP cases and controls, the team used medical records to collect information on age, sex, epilepsy type, and occurrence of seizures, as well as lifestyle information on whether the individuals lived alone or with someone and if they shared a bedroom. The team performed analyses to understand how each of these factors contributed to SUDEP risk.

The analyses of these data found that the presence and frequency of GTCS was the most important risk factor for SUDEP. A history of GTCS was associated with a ten-fold greater risk of SUDEP. Of those with this increased risk, patients who had 4-10 GTCS in the year preceding SUDEP had a 32-fold increase in SUDEP risk. Dr. Tomson’s team also found that the presence of nocturnal GTCS in the year preceding SUDEP was associated with a 15-fold increased risk of SUDEP. Further, this study found that there was no increased risk of SUDEP in people with only non-GTCS, suggesting that treatments to convert GTCS to non-GTCS could reduce SUDEP risk.

Importantly, the team observed a substantial increase in SUDEP risk for individuals with GTCS who lived alone and those who live with other people but don’t share a bedroom. The combination of sleeping alone and having at least one GTCS in the preceding year resulted in a 67-fold increased risk for SUDEP compared to not having GTCS and sharing a bedroom. This data confirms previous research suggesting that unattended GTCS are the most significant risk factor in SUDEP.³

This important study identifies GTCS and sleeping alone as significant risk factors for SUDEP. In addition, Dr. Tomson’s work makes the case for improved seizure monitoring devices to alert caregivers of night-time seizures and for people with GTCS to share a room with someone when sleeping whenever possible. The research further suggests that treatments to reduce occurrence of GTCS would be useful in reducing SUDEP risk.

¹ 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(4):e419-e429
² SUDEP was defined as “definite” or “probable” based on previously developed criteria. When these criteria were met with a sufficient description of the circumstances of death and a postmortem report was available, SUDEP was classified as “definite”. When criteria were met but a postmortem report was not available, SUDEP was classified as “probable”. A third category of “possible” SUDEP included cases where SUDEP could not be ruled out but did not have sufficient evidence or a postmortem report. Possible SUDEP was not included in this study.
³ Devinsky O, Hesdorffer DC, Thurman DJ, Lhatoo S, Richerson G Sudden unexpected death in epilepsy: epidemiology, mechanisms, and prevention, Lancet Neurol. 2016 Sep;15(10):1075-88

CURE Discovery: Predicting Focal Epilepsy’s Path through the Brain

Key Takeaways

In a study funded in part by CURE, Dr. Jennifer Gelinas aimed to understand how focal epilepsy resulting in partial seizures can progress to different parts of the brain over time.
She discovered that abnormal electrical activity between seizures can affect regions of the brain outside of a person’s epileptic network (regions of the brain involved in creating and spreading seizures).
Examining these interactions may provide opportunities to predict how focal epilepsy might progress in individuals.

Deep Dive

Focal epilepsy is often a progressive and unpredictable disease because focal seizures can evolve into new, individual-specific seizure types over time, making treatment challenging.

Some people with focal epilepsy experience seizures that get worse with time, while other individuals have a more stable course. CURE grantee, Dr. Jennifer Gelinas at Columbia University, hopes to understand how and why this variability happens. The aim of her CURE-funded work is to find ways to predict how focal epilepsy will progress to other regions of the brain so that doctors can treat patients more effectively.

Dr. Gelinas previously reported that, in a rat model of temporal lobe epilepsy, interictal epileptiform discharges (IEDs) can trigger neural activity in distant brain regions.¹ IEDs are a type of abnormal electrical activity that occurs between seizures. Now in her recently published study,² funded partly by CURE, Dr. Gelinas sought to understand how IEDs can affect the progression of focal epilepsy over time in people.

For this study, Dr. Gelinas and her team analyzed intracranial EEG (iEEG) recordings from 10 people with focal epilepsy who were undergoing clinical evaluation for epilepsy surgery. For each person, the team first identified brain regions where IEDs could be detected. They then located brain regions which had abnormal neural activity in response to IEDs. Although the patterns of neural activity coupled with IEDs were specific to each person, in each case they were located in distant brain regions outside the patient’s epileptic network. Moreover, distant brain regions where neural activity coupled with IEDs was detected had different characteristics compared to regions that were not affected by IEDs. The researchers also found that affected regions could be identified even in the absence of detectable IEDs.

This important study suggests that abnormal electrical activity (such as IEDs) in one part of the brain can disrupt normal neural activity in distant parts of the brain and may be an indicator of where the epileptic network will spread. Detection and manipulation of these patterns may present opportunities for diagnosis and therapies to prevent the spread of the network to other brain regions.

Dr. Gelinas was awarded a $100,000 Taking Flight grant by CURE in 2018. This grant seeks to promote the careers of young epilepsy investigators to allow them to develop a research focus independent of their mentor.

¹ Gelinas J.N., Khodagholy D. et. al., Interictal epileptiform discharges induce hippocampal-cortical coupling in temporal lobe epilepsy. Nat Med. 2016 Jun;22(6):641-8. 2016;57:178–82
² Dahal P., Ghani N., et. al. Interictal epileptiform discharges shape large-scale intercortical communication. Brain. 2019 Nov 1;142(11):3502-3513

CURE Discovery: Novel Strategies to Understand SUDEP Risk and Ways to Prevent It

Key Takeaways

This CURE-funded study aims to develop biomarkers to assess the risk of Sudden Unexpected Death in Epilepsy (SUDEP) and therapies to prevent it.
By studying breathing and heart abnormalities in a mouse model of SUDEP, the researchers are trying to understand if there are specific patterns which can be detected early and used as a marker to predict risk of SUDEP.
Studies show that administering a drug to block a protein in the brain called orexin improved breathing and heart rate in the mouse models and potentially increased their longevity.

Deep Dive

This grant was supported generously by the Cameron Benninghoven Award.

The ability to predict and prevent SUDEP is a vital need for the epilepsy community, and a recent discovery by CURE Grantee Dr. Kristina Simeone and co-investigators Dr. Peter Abel and Dr. Timothy Simeone at Creighton University could lead to strategies that can help do so. The team is studying specific changes in cardiac and respiratory function health that can lead to SUDEP in hopes of developing biomarkers to predict SUDEP risk and treatments to prevent it.

The researchers are conducting experiments in a mouse model called Kv1.1 KO, which lacks part of the potassium channel, an important component of electrical signaling in the brain. These mice develop spontaneous seizures which progressively become more severe until the mice reach a specific age and are impacted by SUDEP.¹

A 2013 study of SUDEP in humans noted a pattern of rapid breathing followed by apnea and bradycardia (slow heart rate) which eventually led to SUDEP.² In their studies with the Kv1.1 KO mice, Dr. Simeone and her team similarly found that these mice had chronic periods of hypoxia (low oxygen), experienced apnea caused by periods of rapid breathing, and had periods of bradycardia. They found that these breathing and heart problems were more likely to occur as the mice approached SUDEP age. The researchers are interested in understanding whether this abnormal pattern of breathing and bradycardia can be detected early and used as a novel marker to predict SUDEP risk.

The researchers also gathered evidence suggesting that a protein in the brain called orexin, which is known to regulate breathing and heart rate, may be a central player in causing SUDEP. They previously found that blocking orexin’s actions can improve sleep and reduce seizures in the Kv1.1 KO mice model.³ The team treated mice with a drug which blocks orexin’s actions and found that it beneficially increased heart rate in mice with bradycardia, and improved abnormal breathing patterns. The team also found that treating mice at high risk for SUDEP daily with the drug may increase their lifespan.

Dr. Simeone and her co-investigators are interested in using these important new discoveries to develop monitoring strategies for estimating SUDEP risk and eventually developing therapies to prevent SUDEP.

¹ Simeone KA, Matthews SA, Rho JM, et al. Ketogenic Diet increases longevity in a model of Sudden Unexpected Death in Epilepsy, the Kv1.1KO mice. Epilepsia. 2016;57:178–82
² Ryvlin P, Nashef L et al. Incidence and mechanisms of cardiorespiratory arrests in epilepsy monitoring units (MORTEMUS): a retrospective study. Lancet Neurol. 2013 Oct;12(10):966-77
³ Roundtree HM, Simeone TA et al. Orexin Receptor Antagonism Improves Sleep and Reduces Seizures in Kcna1-null Mice. Sleep. 2016 Feb 1;39(2):357-68

CURE Discovery: Understanding and Treating NMDA Receptor-Associated Epilepsy

Key Takeaways:

Researchers are studying whether off-label treatment with certain FDA-approved drugs can improve seizure control for individuals whose epilepsy is caused by over-activation of NMDA-R.
The CURE-funded team is researching previously unstudied mutations in GRIN genes and using this information to determine who might benefit from off-label treatment with NMDA-R blockers.
Interested families with a genetic diagnosis of a GRIN mutation and epilepsy can enroll in this important study. Contact Jenifer Sargent at Jenifer.Sargent@childrenscolorado.org for more information.

Deep Dive:

Can off-label use of certain FDA-approved drugs which reduce NMDA-R function

improve seizure control in patients with epilepsy caused by over-activation of NMDA-R? That is the question a CURE-funded study by Dr. Stephen Traynelis at Emory University and his team aims to answer.

Dr. Traynelis and his collaborators, Drs. Sooky Koh, Ann Poduri, and Tim Benke, will assess if epilepsy caused by over-activation of a protein in the brain, called the N-methyl-D-aspartate receptor (NMDA-R), can be improved when patients with GRIN mutations are treated off-label by their clinicians with certain FDA-approved NMDA-R blockers. They also hope to determine if treatment with these drugs has any positive effects on developmental progress in addition to improved seizure control.

NMDA-R is an essential component of electrical signaling in the brain and is made from proteins encoded by the GRIN family of genes.¹ Because GRIN genes provide the blueprint for NMDA-R, mutations in these genes can impact how the NMDA-R works. Not all of these mutations cause over-activation of the NMDA-R, so in the first part of this project, the researchers are investigating each human GRIN mutation that has not been studied before by re-creating them in the laboratory and evaluating how they affect NMDA-R activity. This information will then be used to determine who might benefit from off-label treatment with drugs that reduce NMDA-R function.

People with GRIN variants that data suggest produce a strong over-activation of the NMDA-R might be candidates for treatment by their physician with NMDA-R blockers. Those with GRIN variants that reduce activity of the NMDA-R or produce complex actions which are difficult to clearly categorize would not be expected to benefit from treatment.

The investigators have created a registry where families affected by GRIN mutations can sign up to participate. The registry collects medical history data and records that are stored without any identifying information to protect the privacy of each participant. Following analysis of a patient’s mutation status, a report is shared with their clinician who will judge whether it is in the patient’s best interest to be considered for off-label treatment. Treatment could then be offered to the family and is based on treatment guidelines Dr. Traynelis and his collaborators have developed.

The team will follow up with a retrospective analysis of treatment efficacy. That is, the investigators will go back and analyze medical records, EEG data, seizure history, and other relevant data for people who received off-label treatment from their physicians to understand how well the treatment worked. This data will also allow an assessment of whether particular GRIN mutations may benefit more from the treatment than others.

This study is expected to provide data for a clinical trial that could lead to new therapies for these difficult to treat epilepsies. In a previously published study, the investigators treated a child with early-onset epileptic encephalopathy associated with a mutation in GRIN2A with the drug memantine and found a substantial reduction in his seizure burden after treatment for a year.² Additional studies provided more mixed results, creating a need to better understand the utility of this approach.

The team is looking to enroll additional families in this important study. If you or anyone you know with a genetic diagnosis of a GRIN mutation and epilepsy are interested in participating, please contact Jenifer Sargent at Jenifer.Sargent@childrenscolorado.org to learn more about the study.

¹ Hansen KB, Feng Y et. al., J Gen Physiol. 2018 Aug 6; 150(8): 1081–1105
² Pierson TM, Yuan H et. al., Ann Clin Transl Neurol. 2014 Mar 1;1(3):190-198

CURE Discovery: A New Model to Understand Focal Cortical Dysplasias

Highlights

CURE Taking Flight Grantee Dr. Yu Wang and his team created a new, better animal model of focal cortical dysplasias (FCDs) to understand how they can lead to focal epilepsy.
The team found that 100% of the animals developed spontaneous seizures, had hyperactivation of the mTOR pathway, and displayed brain malformations as seen in human FCDs.
The team treated the animals with a drug called everolimus, which reversed the abnormal increase in neuronal size seen in some types of FCDs.

Deep Dive

Dr. Yu Wang and his colleagues at the University of Michigan are one step closer to understanding the process of epileptogenesis in FCDs and developing therapies for it. FCDs (small groupings of neurons that fail to develop correctly) are a common cause of difficult-to-treat focal epilepsies. Surgery is often the only treatment option for those impacted by FCDs, and up to 50% of pediatric epilepsy surgery patients have FCDs that are detectible by MRI.¹

Dr. Wang’s team sought to generate a novel animal model of FCD with the same features as humans with mutations in a gene called DEPDC5. This gene is part of the mTOR signaling pathway and is associated with development of FCD-related. Other animal models used to study DEPDC5 are limited in usefulness as they fail to either develop spontaneous seizures or show the same electroclinical features as human FCDs.

To create their model, Dr. Wang and his team used a gene editing technique called CRISPR-IUE in rats to delete DEPDC5 only in the brain’s cortex and not the entire body, thereby more accurately replicating human FCD.² The team found that 100% of the animals developed spontaneous seizures, had hyperactivation of the mTOR pathway, and displayed brain malformations as seen in human FCDs. Importantly, these animals displayed seizure activity highly similar to those recorded in humans with FCDs.

This new model had another feature seen in some types of FCDs: enlarged cell size. Dr. Wang and his team observed that neurons with DEPDC5 deletion were almost twice the size of neurons with a normal level of DEPDC5. The team treated the animals with a drug called everolimus and reversed the increase in neuronal size in their model.

Dr. Wang’s work has led to a model that represents the genetics, pathology, and EEG features of human FCDs. Critically, their work demonstrates that a known drug may be valuable in treating these epilepsies. The team is currently using this model to understand how DEPDC5 mutations cause malformations leading to epilepsy, and to develop a novel gene therapy strategy for mTOR-related cortical malformation and epilepsies. While Dr. Wang’s career is just starting to take flight, we can’t wait to see how his insights and innovations will drive science forward!

¹ Bast T. et.al. Focal cortical dysplasia: prevalence, clinical presentation and epilepsy in children and adults. Acta Neurol Scand. 2006 Feb;113(2):72-81
² Hu S, Knowlton RC et.al. Somatic Depdc5 Deletion Recapitulates Electroclinical Features of Human Focal Cortical Dysplasia Type IIA. Ann Neurol. 2018 Jul;84(1):140-146

A Partnership to Make New Medicines: MaRS Innovation Launches New Drug Discovery Program Based on UHN Discovery

MaRS Innovation is partnering with Dr. James Eubanks at the University Health Network (UHN) to develop a new treatment for Rett syndrome, a rare developmental disorder found almost exclusively in girls and women.

Infants with Rett syndrome develop and grow normally until the age of 8 to 12 months when symptoms begin appearing. Although the symptoms vary in type and severity, most of the girls and women with the disorder cannot speak or use their hands purposefully. Many also experience seizures that are difficult to control with medications. Presently, there is no cure for Rett syndrome, and the available treatments can only help alleviate symptoms.

Researchers have known for many years that most cases of Rett syndrome are caused by mutations in the MECP2 gene; however, the mechanisms that link these genetic changes to the syndrome’s diverse symptoms are not well understood.

“We believe that we have discovered an important piece of the puzzle,” says Dr. Eubanks, a Senior Scientist at the Krembil Research Institute (UHN) who has been studying the disorder for over 20 years.

MaRS Innovation will initially invest up to $400,000 to help translate Dr. Eubanks’ discovery into a new treatment for Rett syndrome. The funds will support the creation and evaluation of drug-like compounds that target TRPM2, dampening its activity, in the brain of Rett patients. Dr. Mark Reed, a medicinal chemist and head of Krembil’s Centre for Medicinal Chemistry and Drug Discovery, will oversee the work, which will be split between the Centre and the Charles River Discovery site in the United Kingdom. The new partnership will also give Drs. Eubanks and Reed access to MaRS Innovation commercialization services to support further development of any promising treatments.

CURE Discovery: A Potential Link Between Gut Bacteria and Epilepsy

Key Points

Dr. Tore Eid’s CURE-funded research aims to understand how gut bacteria can impact seizure development, inflammation, and neurodegeneration.
The team found increased levels of certain amino acids, potentially made by gut bacteria, in the epileptic brain regions of individuals with focal epilepsies.
Short-term treatment with these amino acids reduced spontaneous seizures in a rat model of epilepsy, while a long-term treatment worsened seizure frequency.
Dr. Eid’s studies have the potential to develop epilepsy treatments such as dietary interventions and other safe manipulations of gut bacteria.

Deep Dive

CURE grantee, Dr. Tore Eid, and his team at Yale University, are conducting exciting research to understand how gut bacteria can influence the development and manifestation of seizures. This impactful work, funded by the Heldman-Kirshner family grant in honor of Alex Heldman, could lead to simpler and safer treatments for epilepsy.

Over 500 different types of bacteria live in our gut alone.¹ This dense collection of bacteria, called gut microbiota, helps us digest food, provides important nutrients, builds immunity, and protects us from harmful pathogens. Disruptions to the gut microbiota play a role in many diseases including irritable bowel disease, colitis, and diabetes. There is also evidence that gut microbiota problems are linked to anxiety, depression, and autism spectrum disorders.² How and whether these bacteria influence epilepsy development and progression is not very well studied. There is some evidence that the ketogenic diet, which is effective in reducing seizure frequency in a number of different epilepsies, may work by modifying the gut microbiota.³

To better understand the role gut bacteria may play in epilepsy, Dr. Eid and his team analyzed brain fluid samples from people with focal epilepsy. They found that epileptic brain regions had increased levels of certain amino acids called branched chain amino acids, which can be made by gut bacteria. Levels of some of these branched amino acids increased in the brain three hours before a spontaneous seizure occurred, while levels of other branched amino acids increased an hour before. This may indicate that there is a “fine-tuning” of these amino acids happening within the body which potentially impacts seizure occurrence.

Next, the team fed these branched chain amino acids to a rat model of epilepsy they developed. A short-term treatment decreased spontaneous seizures while a long-term treatment worsened seizure frequency and caused neuronal loss in an area of the brain called the hippocampus.⁴ These results provide evidence that molecules derived from gut bacteria can impact brain chemistry and seizure development.

The team is also interested in understanding how bacteria living in the gut can influence epilepsy development and progression in the brain, focusing on a large nerve called the vagus nerve. This nerve allows the brain and the gut to directly communicate with each other. Dr. Eid’s team has developed techniques to selectively stimulate or suppress signaling only through the afferent vagus nerve, which transmits messages from the gut to the brain, without affecting the efferent nerve, which transmits messages from the brain to the gut and other organs.

In future studies, Dr. Eid and his team will perform careful manipulations of gut bacteria in a rat model of epilepsy by feeding the animals specific types of bacteria. The types of bacteria the team plans to use make molecules which can influence brain chemistry and thus potentially affect seizures. The team will study the effect of this treatment along with afferent vagal nerve stimulation/suppression on seizure development, brain inflammation, and neuronal loss in the rats.

These studies have the potential to impact epilepsy treatment through safe manipulations of gut bacteria through, for example, dietary interventions, probiotics, or antibiotics.

¹ Eckburg PB et.al. Diversity of the human intestinal microbial flora, Science. 2005 Jun 10;308(5728):1635-8
² E.Y. Hsiao et.al Microbiota modulate behavioral and physiological abnormalities associated with neurodevelopmental disorders, Cell. 155 (2013) 1451-1463
³ Olson CA, Vuong HE et. al. The Gut Microbiota Mediates the Anti-Seizure Effects of the Ketogenic Diet, Cell. 2018 Jun 14;173(7):1728-1741.e13. doi: 10.1016/j.cell.2018.04.027
⁴ Gruenbaum SE, Dhaher R et. al., Effects of Branched-Chain Amino Acid Supplementation on Spontaneous Seizures and Neuronal Viability in a Model of Mesial Temporal Lobe Epilepsy, J Neurosurg Anesthesiol. 2019 Apr;31(2):247-256

CURE Discovery: New Genetic Models of Epileptic Encephalopathies Deepen Our Understanding

This research is generously supported by a grant from Jen Scott and Pierre-Gilles Henry, PhD, in honor of Felix Henry.

Key Points

CURE grantee Dr. Mingshan Xue created mice modeling the features of STXBP1-related epileptic encephalopathy (EE) to explore why not having enough STXBP1 activity can cause epilepsy.
The team found that inhibitory brain signaling was diminished in the models, causing excessive neuronal excitation, seizures, and other neurological features seen in humans with EE.
The long-term goal of the team’s project is to understand the mechanisms that cause EEs and use this knowledge to develop new therapies.

Deep Dive

Reduced activity of a gene called STXBP1 is one of the most common causes of epileptic encephalopathy (EE),¹a group of severe pediatric epilepsies which includes Ohtahara Syndrome, West Syndrome, and Dravet Syndrome. Patients with EE often have aggressive, treatment-resistant seizures, developmental delays, behavioral deficits, and intellectual disability among other clinical features. There is an urgent need to better understand these syndromes and develop new therapies for them.

CURE grantee Dr. Mingshan Xue and his colleagues at the Baylor College of Medicine created mouse models with reduced STXBP1 activity to study epilepsy associated with this genetic variant. Through extensive testing, they determined these mice accurately represented EE clinical features such as seizures, behavioral, and cognitive deficits.²

For their CURE-funded work, the team used these models to determine how not having enough STXBP1 activity could cause EE. The team previously observed high levels of neuronal excitation in the brains of mice with low STXBP1. Thus, Dr. Xue’s team hypothesized that not having enough STXBP1 must prevent inhibitory neuronal signaling, causing an imbalance between excitation and inhibition in the brain.

To test this, the team recorded the electrical activity of neurons in the model with reduced STXBP1 activity. They found that inhibitory brain signaling was indeed diminished in these mice while excitatory signaling was not affected, resulting in excessive excitation, seizures, and other neurological features of EE. Further testing revealed that mice with reduced STXBP1 activity specifically in inhibitory neurons had higher anxiety, impaired motor skills, and reduced cognitive function – all features that are seen in humans with EE.

EEs are typically hard to treat with currently available options. The team’s long-term goal is to understand the mechanisms that cause EEs and use this knowledge to develop new therapies. Since completing their CURE-funded grant, Dr. Xue and his co-investigator have received a National Institutes of Health grant, as well as an American Epilepsy Society postdoctoral fellowship to continue this important work.

Bridging the Gap Between STXBP1 Researchers and Families

We are honored to sponsor and attend the first ever STXBP1 Investigators and Family Meeting (SIFM) on June 21, 2019 and June 22, 2019 in Philadelphia. This conference is hosted by STXBP1 Foundation and the Center for Cellular and Molecular Therapeutics (CCMT).

The need for developing community and driving more research on this group of EEs is clear. The inaugural SIFM will bring together researchers and families of individuals with STXBP1 encephalopathies to foster community development and accelerate the search for a cure. This conference is designed to encourage interaction and in-depth discussions among researchers and clinicians to further research and innovation in this field.

You can find out more information about this conference here.

¹ Carvill GL et.al. Nat Genet. 2013 Jul;45(7):825-30. doi: 10.1038/ng.2646
² Wu Chen et.al., Apr 29, 2019, https://www.biorxiv.org/content/10.1101/621516v1

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