Head to head narcolepsy/hypersomnia study

At the sleep research meeting in San Antonio this year, there were signs of an impending pharmaceutical arms race in the realm of narcolepsy. The big fish in a small pond, Jazz Pharmaceuticals, was preparing to market its recently FDA-approved medication: Sunosi/solriamfetol. Startup Harmony Biosciences was close behind with pitolisant, already approved in Europe. On the horizon are experimental drugs designed to more precisely target the neuropeptide deficiency in people with classic narcolepsy type 1 Read more

Anti-inflammatory approach suppresses cancer metastasis in animal models

An anti-inflammatory drug called ketorolac, given before surgery, can promote long-term survival in animal models of cancer metastasis, a team of scientists has found. The research suggests that flanking chemotherapy with ketorolac or similar drugs -- an approach that is distinct from previous anti-inflammatory cancer prevention efforts -- can unleash anti-tumor immunity. The findings, published in Journal of Clinical Investigation, also provide a mechanistic explanation for the anti-metastatic effects of ketorolac, previously observed in human Read more

I3 Venture awards info

Emory is full of fledgling biomedical proto-companies. Some of them are actual corporations with employees, while others are ideas that need a push to get them to that point. Along with the companies highlighted by the Emory Biotech Consulting Club, Dean Sukhatme’s recent announcement of five I3 Venture research awards gives more examples of early stage research projects with commercial potential. This is the third round of the I3 awards; the first two were Wow! Read more

pediatrics

Mother’s milk is OK, even for the in-between babies

“Stop feeding him milk right away – just to be safe” was not what a new mother wanted to hear. The call came several days after Tamara Caspary gave birth to fraternal twins, a boy and a girl. She and husband David Katz were in the period of wonder and panic, both recovering and figuring out how to care for them.

“A nurse called to ask how my son was doing,” says Caspary, a developmental biologist in Emory’s Department of Human Genetics. “She started asking about vomiting and other specific symptoms.”

Her son had tested positive by newborn screening for a rare disorder called galactosemia. Galactosemia is an inherited disease that results from inability to metabolize galactose, a component of human milk and cow-milk-based formula. If a baby with “classic” galactosemia continues to drink milk, the baby may quickly develop symptoms such as jaundice, vomiting and diarrhea, progressing to liver disease and other serious complications that can lead to infant death. If a newborn has classic galactosemia, it is critical for the baby to stop drinking milk and switch to a low-galactose formula, such as soy-based formula, as soon as possible.

Caspary and Katz, a cell biologist, learned several days later that their son did not have classic galactosemia but instead had inherited Duarte galactosemia, a milder, more common form of the metabolic disorder, affecting more than 1 in 5,000 children in the United States. But there was still a looming question.

“We needed to figure out what to feed the baby!” Katz exclaimed, recalling their confusion years later.

The looming question was: what to feed the baby?

Their pediatrician didn’t know what to recommend. Galactosemia, in whatever form, is rare enough in the US that most pediatricians don’t develop experience with it. There was no uniform standard of care, and state-level guidelines for children with Duarte galactosemia varied widely, from no dietary restrictions to banning all milk products for the first year. Some of the limited research available at the time suggested that affected children might experience developmental problems as they grew up. Read more

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Genomics plus human intelligence

Emory geneticists Hong Li and Michael Gambello recently identified the first pediatric case of a rare inherited metabolic disorder: glucagon receptor deficiency. Their findings, published in Molecular Genetics and Metabolic Reports, show the power of gene sequencing to solve puzzles – when combined with human intelligence. Although the diagnosis did not resolve all the issues faced by the patient, it allowed doctors to advise the family about diet and possible pancreatic tumor risk.

The family of a now 9-year-old girl came to Li when the girl was 4 years old. Based on newborn screening, the girl had been diagnosed with a known disorder called arginase deficiency. Arginase breaks down the amino acid arginine; if it is deficient, arginine and toxic ammonia tend to accumulate. At birth, the girl had high arginine levels – hence the initial diagnosis.

The girl had a history of low body weight, anorexia and intermittent vomiting, which led doctors to place a feeding tube through the abdominal wall into her stomach. For several years, she was given a special low-protein liquid diet and supplements, aimed at heading off nutritional imbalance and tissue breakdown. However, she did not have intellectual disability or neurological symptoms, which are often seen with arginase deficiency.

In fact, her blood amino acids, including arginine, were fully normalized, and a genetic test for arginase deficiency was normal as well.  These results were perplexing. By reviewing all the clinical, biochemical and molecular data, Li concluded the girl did not have arginase deficiency, and began looking for an alternative diagnosis. Read more

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MSCs: what’s in a name?

At a recent symposium of cellular therapies held by the Department of Pediatrics, we noticed something. Scientists do not have consistent language to talk about a type of cells called “mesenchymal stem cells” or “mesenchymal stromal cells.” Within the same symposium, some researchers used the first term, and others used the second.

Guest speaker Joanne Kurtzberg from Duke discussed the potential use of MSCs to treat autism spectrum disorder, cerebral palsy, and hypoxic-ischemic encephalopathy. Exciting stuff, although the outcomes of the clinical studies underway are still uncertain. In these studies, the mesenchymal stromal cells (the language Kurtzberg used) are derived from umbilical cord blood, not adult tissues.

Nomenclature matters, because a recent editorial in Nature calls for the term “stem cell” not to be used for mesenchymal (whatever) cells. They are often isolated from bone marrow or fat. MSCs are thought have the potential to become cells such as fibroblasts, cartilage, bone and fat. But most of their therapeutic effects appear to come from the growth factors and RNA-containing exosomes they secrete, rather than their ability to directly replace cells in damaged tissues.

The Nature editorial argues that “wildly varying reports have helped MSCs to acquire a near-magical, all-things-to-all-people quality in the media and in the public mind,” and calls for better characterization of the cells and more rigor in clinical studies.

At Emory, gastroenterologist Subra Kugathasan talked about his experience with MSCs in inflammatory bowel diseases. Hematologist Edwin Horwitz discussed his past work with MSCs on osteogenesis imperfecta. And Georgia Tech-based biomedical engineer Krishnendu Roy pointed out the need to reduce costs and scale up, especially if MSCs start to be used at a higher volume.

Several of the speakers were supported by the Marcus Foundation, which has a long-established interest in autism, stroke, cerebral palsy and other neurological conditions.

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Navigating monstrous anticancer obstacles

A new PNAS paper from geneticist Tamara Caspary’s lab identifies a possible drug target in medulloblastoma, the most common pediatric brain tumor. Come aboard to understand the obstacles this research seeks to navigate. Emory library link here.

Standard treatment for children with medulloblastoma consists of surgery in combination with radiation and chemotherapy. Alternatives are needed, because survivors can experience side effects such as neurocognitive impairment. One possibility has emerged in the last decade: inhibitors of the Hedgehog pathway, whose aberrant activation drives growth in medulloblastoma.

Medulloblastoma patients are caught “between Scylla and Charybdis”: facing a deadly disease, the side effects of radiation and/or existing Hedgehog inhibitors. From Wikimedia.

As this 2017 Oncotarget paper from St. Jude’s describes, Hedgehog inhibitors are no fun either. In adults, these agents cause muscle spasms, hair loss, distorted sense of taste, fatigue, and weight loss. In a pediatric clinical trial, the St. Jude group observed growth plate fusions, resulting in short stature. The drug described in the paper was approved in 2012 for basal cell carcinoma, a form of cancer whose growth is also driven by the Hedgehog pathway. Basal cell carcinoma is actually the most common form of human cancer, although it is often caught at an early stage that doesn’t require harsh treatment.

Caspary’s lab studies the Hedgehog pathway in early embryonic development. In the PNAS paper, former graduate student Sarah Bay and postdoc Alyssa Long show that targeting a downstream part of the Hedgehog pathway may be a way to avoid problems presented by both radiation/chemo and existing Hedgehog inhibitors. Read more

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Vulnerability to cocaine uncovered in adolescent mouse brains

Editor’s note: Guest post from Neuroscience graduate student Brendan O’Flaherty. Companion paper to the Gourley lab’s recently published work on fasudil, habit modification and neuronal pruning.

An Emory study has discovered why teenager’s brains may be especially vulnerable to cocaine. Exposure to small amounts of cocaine in adolescence can disrupt brain development and impair the brain’s ability to change its own habits, the study suggests.

Guest post from Brendan O’Flaherty

The results were published in the April 1, 2017 issue of Biological Psychiatry, by researchers at Yerkes National Primate Research Center.

Drug seeking habits play a major role in drug addiction, says senior author Shannon Gourley, PhD, assistant professor of pediatrics, psychiatry and behavioral sciences at Emory University School of Medicine and Yerkes National Primate Research Center. The first author of the paper is former Emory graduate student Lauren DePoy, PhD.

When it comes to habits, cocaine is especially sneaky. Bad habits like drug use are already very difficult to change, but cocaine physically changes the brain, potentially weakening its ability to “override” bad habits. Although adults are susceptible to cocaine’s effects on habits, adolescent brains are especially vulnerable.

“Generally speaking, the younger you are exposed to cocaine in life, the more likely you are to have impaired decision making,” Gourley says.

Shannon Gourley, PhD, in lab

To understand why adolescent brains are especially vulnerable to cocaine, the researchers studied the effects of cocaine exposure on how the mice make decisions about food.

“I think it’s pretty amazing that we can actually talk to mice in a way that allows them to talk back,” Gourley says. “And then we can utilize a pretty tremendous biological toolkit to understand how the brain works.”

Researchers injected adolescent mice five times with either saline or cocaine. Both groups of animals then grew up without access to cocaine. Researchers then trained the mice to press two buttons, both of which caused food to drop into the cage. Since both buttons rewarded the mice equally, the mice pushed each button half the time.

Over time, pushing the two buttons equally could become a habit. To test this, the researchers then played a trick on the mice. When one of the buttons was exposed, the researchers starting giving the mice food pellets for free, instead of rewarding them for button-pressing.

“What the mouse should be learning is: ‘Ah hah, wait a minute, when I have access to this button I shouldn’t respond, because my responding doesn’t get me anything,‘” Gourley says. Read more

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#AHA17 highlight: cardiac pacemaker cells

At the American Heart Association Scientific Sessions meeting this week, Hee Cheol Cho’s lab is presenting three abstracts on pacemaker cells. These cells make up the sinoatrial node, which generates electrical impulses driving our heart beats. Knowing how to engineer them could enhance cardiologists’ ability to treat arrhythmias, especially in pediatric patients, but that goal is still some distance away.

Just a glimpse of the challenge comes from graduate student Sandra Grijalva’s late breaking oral abstract describing “Induced Pacemaker Spheroids as a Model to Reverse-Engineer the Native Sinoatrial Node”, which was presented yesterday.

Cho has previously published how induced pacemaker cells can be created by introducing the TBX18 gene into rat cardiac muscle cells. In the new research, when a spheroid of induced pacemaker cells was surrounded by a layer of cardiac muscle cells, the IPM cells were able to drive the previously quiescent nearby cells at around 145 beats per minute. [For reference, rats’ hearts beat in living animals at around 300 beats per minute.] Read more

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Beyond CF – potential byproducts of precision medicine

Just a quick comment on the potential of research being conducted by Eric Sorscher, who came to Emory from University of Alabama, Birmingham in 2015 and is now a Georgia Research Alliance Eminent Scholar. While Sorscher’s lab is working on advancing new treatments for cystic fibrosis patients who currently do not benefit from available drugs, it was intriguing to learn of potential side benefits beyond cystic fibrosis.

Cystic fibrosis is caused by mutations in the CFTR gene, which encodes a protein with important functions in cells that produce mucus, sweat, saliva, tears and digestive enzymes. But other things can impair the functioning of the CFTR protein besides genetic mutations. Namely, smoking. Read more

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Ebola’s capriciousness in kids

Anita McElroy, a pediatric infectious disease specialist at Emory, and her colleagues at the CDC, led by Christina Spiropoulou, have been getting some attention for their biomarker research on Ebola virus infection. Sheri Fink from the New York Times highlighted their work in a Nov. 9 report on the infection’s capriciousness. Genetics may also play a role in surviving Ebola infection, as recent animal research has suggested.

McElroy’s team’s findings attracted notice because their results suggest that Ebola virus disease may affect children differently and thus, children may benefit from different treatment regimens than those for adults. The authors write that early intervention to prevent injury to the lining of blood vessels — using statins, possibly — might be a therapeutic strategy in pediatric patients. Read more

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Dissecting how chronic stress leads to depression

How can we study depression and antidepressants in animals? They can’t talk and tell us how they’re feeling. Previously, researchers have used the model of “behavioral despair,” with examples of the forced swimming test or the tail suspension test.

Shannon Gourley, PhD

Several psychiatrists have been arguing that a new framework is needed, which better simulates aspects of depression in humans, such as the variety of behavioral changes and the several week time period needed for antidepressants to function. This new framework could help illuminate how depression develops, and lead to new antidepressants that are effective for more people.

Shannon Gourley, who recently joined the Emory-Children’s Pediatric Research Center has been taking the approach of examining the lack of motivation and self-defeating behavior that are integral parts of depression.

The Pediatric Research Center is an effort led by Emory University and Children’s Healthcare of Atlanta, including partnerships with the Georgia Institute of Technology and Morehouse School of Medicine.

Note: Gretchen Neigh in psychiatry/physiology has been doing work with a similar theme, looking at the effects of adolescent social stress in animal models.

Gourley, neuroscience graduate student Andrew Swanson and their colleagues at Yale, where Gourley was a postdoc with Jane Taylor and Tony Koleske, have a new paper in PNAS on this topic. In particular, they dissect how chronic stress – or exposure to the stress hormone corticosterone – can produce loss of motivation and impaired decision making.

First, the researchers found that exposing rodents to cheap oakleys corticosterone shut off a growth factor called BDNF (brain-derived neurotrophic factor) in the frontal cortex, a region of the brain important for planning and goal-directed behavior. BDNF nourishes neurons and helps keep them alive.

To confirm that BDNF was important in this region of the brain, researchers selectively silenced the gene for BDNF only in the frontal cortex. Both mice exposed to stress hormones and the BDNF-altered mice showed reduced motivation to earn food rewards. Mice would ordinarily press a lever dozens of times to get a food pellet, but the BDNF-altered animals would stop trying earlier – the “break point” is 2/3 as high.

“Depression is a leading cause of unemployment because people are unable to break out of self-defeating behavioral patterns and to muster the motivation to engage with the world. If we can better understand how to treat these symptoms, we can effect better outcomes for individuals suffering from depression,” Gourley says. “The BDNF deficiency alone could account for the loss of motivation that individuals with depression suffer.”

However, she reports her team was surprised that the loss of BDNF could not account for another aspect of depression: cyclical self-defeating behavior. They modeled this by asking whether mice continue to press a lever for a food reward even when the reward is no longer available.

“When we made the discovery that reduced BDNF could not account for all of the depression symptoms that we study, we took a step back and looked at the stress response system,” Gourley says.

Stress hormone exposure impairs the ability of mice to switch away from fruitless behaviors, but loss of BDNF in the frontal cortex does not. Here, the stress response system itself was the culprit. When her team temporarily blocked the ability of mice to shut off their stress response systems using the drug mifepristone, mice had impaired decision-making. However, their motivation to obtain rewards was not altered. When the drug wore off, they returned to normal.

Gourley says the implication is that effective antidepressants need to be able to attack not one, but two physiological systems: they need to increase levels of BDNF, and they need to help the stress system recover so that it can shut itself off better. A classic trycyclic antidepressant, amitriptyline, can do both and was effective in treating both the motivation and decision making parts of depression in animal models.

The use of tricyclic antidepressants is limited because of side effects and overdose potential. In addition, another challenge in treating depression is that current antidepressants only begin to work after several weeks or months of treatment. This is thought to be because it takes several weeks for these drugs—which act only indirectly on BDNF—to restore BDNF levels back to normal.

New compounds that act directly on BDNF’s receptor TrkB, such as those identified and tested by Emory researcher Keqiang Ye, could be promising in the development of new approaches to depression, Gourley says.

She and her team also showed that a drug called riluzole, which acts indirectly but rapidly on BDNF systems, has antidepressant effects in the animal models. Riluzole is currently in use to treat ALS, and reportedly has antidepressant effects in humans. Clinical trials with riluzole in the context of depression are underway.

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Playing tetherball with HIV

Raise your hand if you played tetherball in grade school. Paul Spearman and his colleagues have a new paper in the journal Cell Host & Microbe probing a protein called “tetherin” that keeps HIV ensnared within cells it is infecting.

The paper includes electron microscopy images that make it possible to imagine a tiny cord attached to a nascent HIV particle within the cell. In these images, we don’t see the tetherin protein directly. However, we do see gold beads, bound to antibodies against the tetherin protein, which indicate where the protein is. The microscopy was performed at Emory’s Robert P. Apkarian Integrated Electron Microscopy Core.

Tetherin is a so-called “restriction factor,” one of several proteins within the cell that interfere with parts of the viral life

The black dots are antibody-linked gold beads, which indicate where the tetherin is. The larger globules are viral capsids.

cycle. Other restriction factors include enzymes that strip the viral RNA or impede the assembly of the viral capsid. Tetherin also interferes with a variety of other viruses such as Ebola.

Some viral proteins such as HIV’s Vpu or Nef fight back against the action of tetherin. Tracking how this kind of arms race has developed can help scientists follow how HIV evolved from similar retroviruses that infect non-human primates. In addition, knowing how tetherin works could be important in efforts to eradicate potential reservoirs of HIV in infected individuals, and in understanding how the virus is transmitted from person to person.

In their paper, first author Hin Chu and Spearman wanted to determine why infection looks different in two different cell types vulnerable to HIV. In T cells, HIV assembly occurs near the membrane, but in macrophages, HIV assembly occurs in an internal compartment.

“The reason that there is a large, internal collection of HIV particles in macrophages is hotly debated,” Spearman explains. “Some see this as a reservoir of virus that is available to spread to other cells, others would say this is a dead-end compartment. We found that the compartment basically goes away when we deplete tetherin, so tetherin is essential to the existence of the virus-containing compartment.”

Chu and his co-workers examined what happened in macrophages when they used a tool called “RNA interference” to turn off the tetherin gene.

Hin Chu

“We found that cell-cell transmission was enhanced when we depleted tetherin. My interpretation is that when tetherin is upregulated in macrophages, viral particles are rapidly internalized and are not transmitted.”

“Another significant finding is that Vpu doesn’t work well in macrophages. If we can determine why it doesn’t work well in this cell type, it will help us understand how Vpu does work so efficiently in other cells such as T cells. Macrophages are one of the most important cell types infected by HIV, so these questions are likely to be very important in how virus spreads and is maintained in infected individuals.”

Spearman is chief research officer for Children’s Healthcare of Atlanta and director of the Children’s Center for Vaccines and Immunology, within the Emory-Children’s Pediatric Research Center. He is also professor and vice chair of research in pediatrics at Emory. Hin Chu is a graduate student in the Microbiology and Molecular Genetics program.

Posted on by Quinn Eastman in Immunology 1 Comment