Skin disease studies go deep: depression/inflammation insight

A recent paper from Miller and psychiatry chair Mark Rapaport looks at clinical trials testing an anti-inflammatory drug against psoriasis, to see whether participants’ depressive symptoms improved. Read more

New insight into how brain cells die in Alzheimer's and FTD

(Epi)genetic hallucinations induced by loss of LSD1 resemble Alzheimer's. Another surprise: LSD1 aggregates in Alzheimer's brain, looking like Tau Read more

2B4: potential immune target for sepsis survival

Emory immunologists have identified a potential target for treatments aimed at reducing mortality in sepsis, an often deadly reaction to Read more

department of pharmacology

Granulins treasure not trash – potential FTD treatment strategy

Emory University School of Medicine researchers have developed tools that enable them to detect small proteins called granulins for the first time inside cells. Granulins are of interest to neuroscientists because mutations in the granulin gene cause frontotemporal dementia (FTD). However, the functions of granulins were previously unclear.

FTD is an incurable neurodegenerative disease and the most common type of dementia in people younger than 60. Genetic variants in the granulin gene are also a risk factor for Alzheimer’s disease and Parkinson’s disease, suggesting this discovery may have therapeutic potential for a broad spectrum of age-related neurodegenerative diseases.

The results were published August 9 by the journal eNeuro (open access).

Thomas Kukar, PhD

Some neuroscientists believed that granulins were made outside cells, and even could be toxic under certain conditions. But with the newly identified tools, the Emory researchers can now see granulins inside cells within lysosomes, which are critical garbage disposal and recycling centers. The researchers now propose that granulins have important jobs in the lysosome that are necessary to maintain brain health, suppress neuroinflammation, and prevent neurodegeneration.

Problems with lysosomes appear in several neurodegenerative diseases such as Alzheimer’s and Parkinson’s.

“A lysosomal function for granulins is exciting and novel.  We believe it may provide an explanation why decreased levels of granulins are linked to multiple neurodegenerative diseases, ranging from frontotemporal dementia to Alzheimer’s,” says senior author Thomas Kukar, PhD, assistant professor of pharmacology and neurology and the Emory University Center for Neurodegenerative Disease. Read more

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Drug discovery: selective anti-inflammatory approach to AD

Anyone familiar with Alzheimer’s disease research can say what a challenge drug development has been. In Emory’s Department of Pharmacology, Thota Ganesh is focusing on an anti-inflammatory approach. Ganesh’s work has been supported by the Alzheimer’s Drug Discovery Foundation and more recently by a five-year, $3.6 million grant from the National Institute on Aging.

Medicinal chemist Thota Ganesh, PhD, is focusing on an anti-inflammatory approach to Alzheimer’s disease, targeting the prostaglandin receptor EP2.

An assistant professor at Emory since 2011, he is continuing research he undertook with Ray Dingledine on EP2 antagonists. In animals, they showed that this class of compounds could reduce injury to the brain after a prolonged seizure. Since then, they have shown that EP2 antagonists have similar effects in protecting against organophosphate pesticides/nerve agents.

EP2 is one of the four receptors for prostaglandin E2, a hormone involved in processes such as fever, childbirth, digestion and blood pressure regulation. Before Ganesh and colleagues from the Emory Chemical Biology Discovery Center started looking for them, chemicals that could block EP2 selectively were not available.

Their idea is: blocking EP2 is a better strategy than the more general approach of going after prostaglandins, the targets for non-steroid anti-inflammatory drugs (NSAIDs) such as aspirin, ibuprofen and celecoxib (Celebrex). Read more

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More on NMDA receptor variants + epilepsy/ID

NMDA receptors are complex electrochemical machines, important for signaling between brain cells. Rare mutations in the corresponding genes cause epilepsy and intellectual disability.

Pre-M1 helices in multi-subunit NMDA receptor. Adapted from Ogden et al PLOS Genetics (2017).

In Emory’s Department of Pharmacology, the Traynelis and Yuan labs have been harvesting the vast amounts of information now available from public genome databases, to better understand how changes in the NMDA receptor genes relate to function. (Take a “deeper dive” into their November 2016 publication on this topic here.)

Their recent paper in PLOS Genetics focuses on a particular region in the NMDA receptor, called the pre-M1 helix (see figure). It also includes experiments on whether drugs now used for Alzheimer’s disease, such as memantine, could be repurposed to have beneficial effects for patients with certain mutations. The in vitro data reported here could inform clinical use. Read more

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Insane in the membrane – inflamed in the brain

Inflammation in the brain is a feature of several neurological diseases, ranging from Parkinson’s and Alzheimer’s to epilepsy. Nick Varvel, a postdoc with Ray Dingledine’s lab at Emory, was recently presenting his research and showed some photos illustrating the phenomenon of brain inflammation in status epilepticus (prolonged life-threatening seizures).

The presentation was at a Center for Neurodegenerative Disease seminar; his research was also published in PNAS and at the 2016 Society for Neuroscience meeting.green-red-brain

Varvel was working with mice in which two different types of cells are marked by fluorescent proteins. Both of the cell types come originally from the blood and can be considered immune cells. However, one kind – marked with green — is in the brain all the time, and the red kind enters the brain only when there is an inflammatory breach of the blood brain barrier.

Both markers, CX3CR1 (green) and CCR2 (red), are chemokine receptors. Green fluorescent protein is selectively produced in microglia, which settle in the brain before birth and are thought to have important housekeeping/maintenance functions.

Monocytes, a distinct type of cell that is not usually in the brain in large numbers, are lit up red. Monocytes rush into the brain in status epilepticus, and in traumatic brain injury, hemorrhagic stroke and West Nile virus encephalitis, to name some other conditions where brain inflammation is also seen.

In the PNAS paper, Varvel and his colleagues include a cautionary note about using these mice for studying situations of more prolonged brain inflammation, such as neurodegenerative diseases: the monocytes may turn down production of the red protein over time, so it’s hard to tell if they’re still in the brain after several days.

Targeting CCR2 – good or bad? Depends on the disease model

The researchers make the case that “inhibiting brain invasion of CCR2+ monocytes could represent a viable method for alleviating several deleterious consequences of status epilepticus.” Read more

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Nerve gas, angel dust and genetic epilepsy

Last week, Lab Land noticed similarities between two independent lines of research from the Escayg and Traynelis/Yuan labs at Emory. Both were published recently and deal with rare forms of genetic epilepsy, in which molecular understanding of the cause leads to individualized treatment, albeit with limited benefit.

Both conditions are linked to an excess of neuronal excitation, and both can be addressed using medications that have also been tested for Alzheimer’s. A critical difference is that memantine is FDA-approved for Alzheimer’s, but huperzine A is not.

What condition? Dravet syndrome/GEFS+ Epilepsy-aphasia syndrome
What gene is mutated? SCN1A – sodium ion channel GRIN2A – NMDA receptor subunit
What is the beneficial drug? Huperzine A Memantine
How does the drug work? Acetylcholinesterase inhibitor NMDA receptor antagonist
Other drugs that use the same mechanism Alzheimer’s medications such as donepezil

Irreversible + stronger: insecticides, nerve gas

Ketamine, phencyclidine (aka PCP)
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Deep dive into NMDA receptor variation

The study of human genetics has often focused on mutations that cause disease. When it comes to genetic variations in healthy people, scientists knew they were out there, but didn’t have a full picture of their extent. That is changing with the emergence of resources such as the Exome Aggregation Consortium or ExAC, which combines sequences for the protein-coding parts of the genome from more than 60,000 people into a database that continues to expand.

ajhg-fig-2-092016

Rare mutations in the NMDA receptor genes cause epilepsy (GRIN2A) or intellectual disability (GRIN2B). Shown in blue are agonist binding domains of the receptors, where several disease-causing mutations can be found.

At Emory, the labs of Stephen Traynelis and Hongjie Yuan have published an analysis of ExAC data, focusing on the genes encoding two NMDA receptor subunits, GRIN2A and GRIN2B. These receptors are central to signaling between brain cells, and rare mutations in the corresponding genes cause epilepsy (GRIN2A) or intellectual disability (GRIN2B). GRIN2B mutations have also been linked with autism spectrum disorder.

steveandhongjie

Steve Traynelis and Hongjie Yuan

The new paper in the American Journal of Human Genetics makes a deep dive into ExAC data to explore the link between normal variation in the healthy population and regions of the proteins that harbor disease-causing mutations.

In addition, the paper provides a detailed look at how 25 mutations that were identified in individuals with neurologic disease actually affect the receptors. For some patients, this insight could potentially guide anticonvulsant treatment with a repurposed Alzheimer’s medication. Also included are three new mutations from patients identified by whole exome sequencing, one in GRIN2A and two in GRIN2B.

“This is one of the first analyses like this, where we’re mapping the spectrum of variation in a gene onto the structure of the corresponding protein,” says Traynelis, PhD, professor of pharmacology at Emory University School of Medicine. “We’re able to see that the disease mutations cluster where variation among the healthy population disappears.”

Heat map of agonist binding domain for GRIN2A.

Heat map of agonist binding domain for GRIN2A. From Swanger et al AJHG (2016).

Postdoctoral fellow Sharon Swanger, PhD is first author of the paper, and Yuan, MD, PhD, assistant professor of pharmacology, is co-senior author.

It’s not always obvious, looking at the sequence of a given mutation, how it’s going to affect NMDA receptor function. Only introducing the altered gene into cells and studying protein function in the lab provides that information, Traynelis says.

NMDA receptors are complicated machines: mutations can affect how well they bind their ligands (glutamate and glycine), how they open and shut, or how they are processed onto the cell surface. On top of that complexity, mutations that make the receptors either stronger or weaker can both lead the brain into difficulty; within each gene, both types of mutation are associated with similar disorders. With some GRIN2A mutations, the functional changes identified in the lab were quite strong, but the effect on the brain was less dramatic (mild intellectual disability or speech disorder), suggesting that other genetic factors contribute to outcomes.

Clinical relevance

Traynelis and Yuan previously collaborated with the NIH’s Undiagnosed Disease Program to show that the Alzheimer’s medication memantine can be repurposed as an anticonvulsant, for a child with intractable epilepsy coming from a mutation in the GRIN2A gene. (Nature Communications, Annals of Clinical and Translational Neurology)

Memantine is an NMDA receptor antagonist, aimed at counteracting the overactivation of the receptor caused by the mutation. Memantine has also been used to treat children with epilepsy associated with mutations in the related GRIN2D gene. However, memantine doesn’t work on all activating mutations, and could have effects on the unmutated NMDA receptors in the brain as well. Traynelis reports that his clinical colleagues are developing guidelines for physicians on the use of memantine for children with GRIN gene mutations.

This study and related investigations were supported by funding from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (R01HD082373), the National Institute of Neurological Disorders and Stroke (R24NS092989), the Atlanta Clinical & Translational Science Institute (UL1TR000454), and CURE Epilepsy: Citizens United for Research in Epilepsy.

 

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A sweet brain preserver: trehalose

It’s sweet, it’s safe, and it looks like it could save neurons. What is it? Trehalose.

Trehalose molecule

Trehalose is a natural sugar.

This natural sugar is used in the food industry as a preservative and flavor enhancer (it’s in Taco Bell’s meat filling). And curiously, medical researchers keep running into trehalose when they’re looking for ways to fight neurodegenerative diseases.

A recent example from Emory’s Department of Pharmacology: Chris Holler, Thomas Kukar and colleagues were looking for drugs that might boost human cells’ production of progranulin (PGRN), a growth factor that keeps neurons healthy. Mutations in the progranulin gene are a common cause of frontotemporal dementia.

The Emory scientists discovered two leads: a class of compounds called mTOR inhibitors — the transplant drug rapamycin is one — and trehalose. The team decided to concentrate on trehalose because it increased PGRN levels in neuronal and non-neuronal cell types, unlike the mTOR inhibitors. Their results were published at the end of June in Molecular Neurodegeneration.

The team confirmed their findings by examining the effects of trehalose on cells derived from patients with progranulin mutations. This paper is the first to include results from Emory’s Laboratory of Translational Cell Biology, which was established in 2012 to facilitate this type of “disease in a dish” approach. Cell biologists Charles Easley, Wilfried Rossoll and Gary Bassell from the LTCB, and neurologists Chad Hales and William Hu from the Center for Neurodegenerative Disease are co-authors.

Read more

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Flashback to LSD research from the 1950s

Accompanying Kai Kupferschmidt’s July 3 feature in Science, which discusses a current revival of clinical research on hallucinogens such as LSD and psilocybin, was a curious historical photo. The 1955 copyrighted photo depicts pharmacologist Harry Williams squirting LSD into the mouth of Carl Pfeiffer, chair of pharmacology at Emory during the 1950’s. Read more

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Hypersomnia update: beyond subject one

It’s not sleep apnea. It’s not narcolepsy. Hypersomnia is a different kind of sleep disorder. There’s even an “apples and oranges” T-shirt (see below) that makes that point.

This weekend, your correspondent attended a patient-organized Living with Hypersomnia conference. One of the main purposes of the conference was to update sufferers and supporters on the state of research at Emory and elsewhere, but there was also a lot of community building — hence the T-shirts.

The story of how sleep took over one young lawyer’s life, and how her life was then transformed by flumazenil, a scarce antidote to sleeping pills she was not taking, has received plenty of attention.

Now an increasing number of people are emerging who have a condition similar to Anna Sumner’s, and several questions need answers. Read more

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Personalized molecular medicine part 3

This is a continuation of previous posts on individualized treatment for infantile-onset epilepsy, made possible by Emory scientists Stephen Traynelis and Hongjie Yuan’s collaboration with the NIH Undiagnosed Diseases Program. A companion paper containing some clinical details was recently published in Annals of Clinical and Translational Neurology.

Memantine, which was found to be effective for this particular child, is normally used to treat symptoms of Alzheimer’s disease. He has a mutation in a gene encoding a NMDA receptor, an important signaling molecule in the brain, which hyperactivates the receptor. Treatment with memantine reduced his seizure frequency from 11 per week to three per week, and eliminated one type of seizure, myoclonic jerks. It allowed doctors to taper off conventional anticonvulsant drugs, which were having little effect anyway. His cognitive ability has remained unchanged.

The team also discovered that the compound dextromethorphan, found in many over-the-counter cough medicines, was effective in the laboratory in counteracting the effects of a GRIN2A mutation found in another patient. However, these effects were mutually exclusive, because the molecular effects of the mutations are different; memantine helps L812M, while dextromethorphan helps N615K.

Yuan and Traynelis report they have an Fake Oakleys ongoing collaboration with UDP investigators to analyze the effects of mutations in NMDA receptor genes. That means more intriguing case reports are coming, they say.

Tyler Pierson, MD, PhD, lead author of the clinical paper who is now at Cedars-Sinai Medical Center in Los Angeles, and David Adams, MD, PhD, senior staff clinician at NIH, provided some additional information on the patient in the study, shown here in a Q + A format. Read more

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