Posts Tagged ‘University of Iowa’

by Jennifer Brown

The recent Ebola outbreak in West Africa has claimed more than 11,300 lives—a stark reminder of the lack of effective options for treating or preventing the disease.

Progress has been made on developing vaccines, but there is still a need for antiviral therapies to protect health care workers and local populations in the event of future outbreaks.

Now, a new study suggests that gamma interferon, an FDA-approved drug, may have potential as an antiviral therapy to prevent Ebola infection when given either before or after exposure to the virus.

The findings, published in the journal PLOS Pathogens, show that gamma interferon, given up to 24 hours after exposure, inhibits Ebola infection in mice and completely protects the animals from death.

Ebola infection appears to be a stepwise process. First, the virus targets and infects macrophages or dendritic cells, two types of immune system cells found in the liver, spleen, and lymph nodes. Ebola then replicates in those cells. Following this initial infection, which happens at day 3 or 4 in non-human primates, Ebola virus is released into the blood and infects a plethora of other different cell populations.

“It goes from an early stage with a very targeted infection of only these few cell types, to everything being infected,” says Wendy Maury, professor of microbiology at the University of Iowa.

“We think what’s happening with gamma interferon is that it’s targeting macrophages and blocking the infection of those initial cell targets so you don’t get the second round of infection.”

The University of Iowa does not have a specializing BioSafety Level 4 (BSL4) lab that is required for experiment using Ebola virus, so the researchers made their initial findings using a surrogate virus, which targets and infects the same cells as Ebola, but does not cause the disease.

This Ebola lookalike—a sheep in wolf’s clothing—consists of a less dangerous vesicular stomatitis virus (VSV) that expresses Ebola glycoproteins on its surface.

All of the results found using the surrogate virus were then repeated using mouse-adapted Ebola virus in the BSL4 lab of Maury’s longtime collaborator Robert Davey at Texas Biomedical Institute in San Antonio, Texas.

Gamma interferon inhibits the virus’s ability to infect human and mouse macrophages, in part by blocking virus replication in the cells. Pre-treating mice with interferon gamma 24 hours before exposure protects the animals from infection and death. The researchers were surprised to find that treatment up to 24 hours after what would have been a lethal exposure also completely protected the animals from death, and they could no longer detect any Ebola virus in the mouse’s cells.

The findings suggest that interferon gamma may be useful both as a prophylaxis and post-exposure treatment against Ebola. The team still has to determine how late gamma interferon can be given to the mice and still prevent infection. However, the results suggest a window of time after exposure when gamma interferon may be an effective antiviral therapy.

“My guess is that if you delay the gamma interferon too much, you miss this window of opportunity to block the infection in macrophage cells and the gamma interferon can no longer provide protection,” Maury says.

Maury and colleagues investigated how gamma interferon might be helping the cells fight off the Ebola virus. They identified that the expression of more than 160 genes in human macrophages is stimulated by gamma interferon. Introduction of some of these genes into cells was sufficient to prevent Ebola infection.

“This mechanistic information might suggest more precise drug targets rather than the broad effects, including adverse side-effects, that are produced by gamma-interferon,” she says.

Gamma interferon is already approved by the FDA to treat chronic granulomatous disease (an immune disease) and severe malignant osteopetrosis.

In addition to moving the studies into larger animal models, Maury next plans to study the ability of gamma interferon to inhibit Ebola infection in conjunction with other developing antivirals.

“Right now, there are no FDA-approved antiviral therapies for Ebola, but there are some being developed that target virus entry,” she says. “We know that gamma interferon blocks replication but not entry into cells. So combining an entry inhibitor with gamma interferon may allow us to reduce amount of gamma interferon needed and target two different steps in the virus’s life cycle, which has been shown in HIV to be critically important for controlling the virus.”

http://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1005263

http://now.uiowa.edu/2015/12/fda-approved-drug-protects-mice-ebola

With the pressure for a certain body type prevalent in the media, eating disorders are on the rise. But these diseases are not completely socially driven; researchers have uncovered important genetic and biological components as well and are now beginning to tease out the genes and pathways responsible for eating disorder predisposition and pathology.

As we enter the holiday season, shoppers will once again rush into crowded department stores searching for the perfect gift. They will be jostled and bumped, yet for the most part, remain cheerful because of the crisp air, lights, decorations, and the sound of Karen Carpenter’s contralto voice ringing out familiar carols.

While Carpenter is mainly remembered for her musical talents, unfortunately, she is also known for introducing the world to anorexia nervosa (AN), a severe life-threatening mental illness characterized by altered body image and stringent eating patterns that claimed her life just before her 33rd birthday in 1983.

Even though eating disorders (ED) carry one of the highest mortality rates of any mental illness, many researchers and clinicians still view them as socially reinforced behaviors and diagnose them based on criteria such as “inability to maintain body weight,” “undue influence of body weight or shape on self-evaluation,” and “denial of the seriousness of low body weight” (1). This way of thinking was prevalent when Michael Lutter, then an MD/PhD student at the University of Texas Southwestern Medical Center, began his psychiatry residency in an eating disorders unit. “I just remember the intense fear of eating that many patients exhibited and thought that it had to be biologically driven,” he said.

Lutter carried this impression with him when he established his own research laboratory at the University of Iowa. Although clear evidence supports the idea that EDs are biologically driven—they predominantly affect women and significantly alter energy homeostasis—a lack of well-defined animal models combined with the view that they are mainly behavioral abnormalities have hindered studies of the neurobiology of EDs. Still, Lutter is determined to find the biological roots of the disease and tease out the relationship between the psychiatric illness and metabolic disturbance using biochemistry, neuroscience, and human genetics approaches.

We’ve Only Just Begun

Like many diseases, EDs result from complex interactions between genes and environmental risk factors. They tend to run in families, but of course, for many family members, genetics and environment are similar enough that teasing apart the influences of nature and nurture is not easy. Researchers estimate that 50-80% of the predisposition for developing an ED is genetic, but preliminary genome-wide analyses and candidate gene studies failed to identify specific genes that contribute to the risk.

According to Lutter, finding ED study participants can be difficult. “People are either reluctant to participate, or they don’t see that they have a problem,” he reported. Set on finding the genetic underpinnings of EDs, his team began recruiting volunteers and found 2 families, 1 with 20 members, 10 of whom had an ED and another with 5 out of 8 members affected. Rather than doing large-scale linkage and association studies, the team decided to characterize rare single-gene mutations in these families, which led them to identify mutations in the first two genes, estrogen-related receptor α (ESRRA) and histone deacetylase 4 (HDAC4), that clearly associated with ED predisposition in 2013 (1).

“We have larger genetic studies on-going, including the collection of more families. We just happened to publish these two families first because we were able to collect enough individuals and because there is a biological connection between the two genes that we identified,” Lutter explained.

ESRRA appears to be a transcription factor upregulated by exercise and calorie restriction that plays a role in energy balance and metabolism. HDAC4, on the other hand, is a well-described histone deacteylase that has previously been implicated in locomotor activity, body weight homeostasis, and neuronal plasticity.

Using immunoprecipitation, the researchers found that ESRRA interacts with HDAC4, in both the wild type and mutant forms, and transcription assays showed that HDAC4 represses ESRRA activity. When Lutter’s team repeated the transcription assays using mutant forms of the proteins, they found that the ESRRA mutation seen in one family significantly reduced the induction of target gene transcription compared to wild type, and that the mutation in HDAC4 found in the other family increased transcriptional repression for ESRRA target genes.

“ESRRA is a well known regulator of mitochondrial function, and there is an emerging view that mitochondria in the synapse are critical for neurotransmission,” Lutter said. “We are working on identifying target pathways now.”

Bless the Beasts and the Children

Finding genes associated with EDs provides the groundwork for molecular studies, but EDs cannot be completely explained by the actions of altered transcription factors. Individuals suffering these disorders often experience intense anxiety, intrusive thoughts, hyperactivity, and poor coping strategies that lead to rigid and ritualized behaviors and severe crippling perfectionism. They are less aware of their emotions and often try to avoid emotion altogether. To study these complex behaviors, researchers need animal models.

Until recently, scientists relied on mice with access to a running wheel and restricted access to food. Under these conditions, the animals quickly increase their locomotor activity and reduce eating, frequently resulting in death. While some characteristics of EDs—excessive exercise and avoiding food—can be studied in these mice, the model doesn’t allow researchers to explore how the disease actually develops. However, Lutter’s team has now introduced a promising new model (3).

Based on their previous success with identifying the involvement of ESRRA and HDAC4 in EDs, the researchers wondered if mice lacking ESRRA might make suitable models for studies on ED development. To find out, they first performed immunohistochemistry to understand more about the potential cognitive role of ESRRA.

“ESRRA is not expressed very abundantly in areas of the brain typically implicated in the regulation of food intake, which surprised us,” Lutter said. “It is expressed in many cortical regions that have been implicated in the etiology of EDs by brain imaging like the prefrontal cortex, orbitofrontal cortex, and insula. We think that it probably affects the activity of neurons that modulate food intake instead of directly affecting a core feeding circuit.”

With these data, the team next tried providing only 60% of the normal daily calories to their mice for 10 days and looked again at ESRRA expression. Interestingly, ESRRA levels increased significantly when the mice were insufficiently fed, indicating that the protein might be involved in the response to energy balance.

Lutter now believes that upregulation of ESRRA helps organisms adapt to calorie restriction, an effect possibly not happening in those with ESRRA or HDAC4 mutations. “This makes sense for the clinical situation where most individuals will be doing fine until they are challenged by something like a diet or heavy exercise for a sporting event. Once they start losing weight, they don’t adapt their behaviors to increase calorie intake and rapidly spiral into a cycle of greater and greater weight loss.”

When Lutter’s team obtained mice lacking ESRRA, they found that these animals were 15% smaller than their wild type littermates and put forth less effort to obtain food both when fed restricted calorie diets and when they had free access to food. These phenotypes were more pronounced in female mice than male mice, likely due to the role of estrogen signaling. Loss of ESRRA increased grooming behavior, obsessive marble burying, and made mice slower to abandon an escape hole after its relocation, indicating behavioral rigidity. And the mice demonstrated impaired social functioning and reduced locomotion.

Some people with AN exercise extensively, but this isn’t seen in all cases. “I would say it is controversial whether or not hyperactivity is due to a genetic predisposition (trait), secondary to starvations (state), or simply a ritual that develops to counter the anxiety of weight related obsessions. Our data would suggest that it is not due to genetic predisposition,” Lutter explained. “But I would caution against over-interpretation of mouse behavior. The locomotor activity of mice is very different from people and it’s not clear that you can directly translate the results.”

For All We Know

Going forward, Lutter’s group plans to drill down into the behavioral phenotypes seen in their ESRRA null mice. They are currently deleting ESRRA from different neuronal cell types to pair individual neurons with the behaviors they mediate in the hope of working out the neural circuits involved in ED development and pathology.

In addition, the team has created a mouse line carrying one of the HDAC4 mutations previously identified in their genetic study. So far, this mouse “has interesting parallels to the ESRRA-null mouse line,” Lutter reported.

The team continues to recruit volunteers for larger-scale genetic studies. Eventually, they plan to perform RNA-seq to identify the targets of ESRRA and HDAC4 and look into their roles in mitochondrial biogenesis in neurons. Lutter suspects that this process is a key target of ESRRA and could shed light on the cognitive differences, such as altered body image, seen in EDs. In the end, a better understanding of the cells and pathways involved with EDs could create new treatment options, reduce suffering, and maybe even avoid the premature loss of talented individuals to the effects of these disorders.

References

1. Lutter M, Croghan AE, Cui H. Escaping the Golden Cage: Animal Models of Eating Disorders in the Post-Diagnostic and Statistical Manual Era. Biol Psychiatry. 2015 Feb 12.

2. Cui H, Moore J, Ashimi SS, Mason BL, Drawbridge JN, Han S, Hing B, Matthews A, McAdams CJ, Darbro BW, Pieper AA, Waller DA, Xing C, Lutter M. Eating disorder predisposition is associated with ESRRA and HDAC4 mutations. J Clin Invest. 2013 Nov;123(11):4706-13.

3. Cui H, Lu Y, Khan MZ, Anderson RM, McDaniel L, Wilson HE, Yin TC, Radley JJ, Pieper AA, Lutter M. Behavioral disturbances in estrogen-related receptor alpha-null mice. Cell Rep. 2015 Apr 21;11(3):344-50.

http://www.biotechniques.com/news/Exploring-the-Biology-of-Eating-Disorders/biotechniques-361522.html


Dr. Justin Grobe, PhD


Dr. Michael Lutter, MD PhD

In a study that seems to defy conventional dietary wisdom, University of Iowa scientists have found that adding high salt to a high-fat diet actually prevents weight gain in mice.

As exciting as this may sound to fast food lovers, the researchers caution that very high levels of dietary salt are associated with increased risk for cardiovascular disease in humans. Rather than suggest that a high salt diet is suddenly a good thing, the researchers say these findings really point to the profound effect non-caloric dietary nutrients can have on energy balance and weight gain.

“People focus on how much fat or sugar is in the food they eat, but [in our experiments] something that has nothing to do with caloric content – sodium – has an even bigger effect on weight gain,” say Justin Grobe, PhD, assistant professor of pharmacology at the UI Carver College of Medicine and co-senior author of the study, which was published in the journal Scientific Reports on June 11.

The UI team started the study with the hypothesis that fat and salt, both being tasty to humans, would act together to increase food consumption and promote weight gain. They tested the idea by feeding groups of mice different diets: normal chow or high-fat chow with varying levels of salt (0.25 to 4 percent). To their surprise, the mice on the high-fat diet with the lowest salt gained the most weight, about 15 grams over 16 weeks, while animals on the high-fat, highest salt diet had low weight gain that was similar to the chow-fed mice, about 5 grams.

“We found out that our ‘french fry’ hypothesis was perfectly wrong,” says Grobe, who also is a member of the Fraternal Order of Eagles Diabetes Research Center at the UI and a Fellow of the American Heart Association. “The findings also suggest that public health efforts to continue lowering sodium intake may have unexpected and unintended consequences.”

To investigate why the high salt prevented weight gain, the researchers examined four key factors that influence energy balance in animals. On the energy input side, they ruled out changes in feeding behavior – all the mice ate the same amount of calories regardless of the salt content in their diet. On the energy output side, there was no difference in resting metabolism or physical activity between the mice on different diets. In contrast, varying levels of salt had a significant effect on digestive efficiency – the amount of fat from the diet that is absorbed by the body.

“Our study shows that not all calories are created equal,” says Michael Lutter, MD, PhD, co-senior study author and UI assistant professor of psychiatry. “Our findings, in conjunction with other studies, are showing that there is a wide range of dietary efficiency, or absorption of calories, in the populations, and that may contribute to resistance or sensitivity to weight gain.”

“This suppression of weight gain with increased sodium was due entirely to a reduced efficiency of the digestive tract to extract calories from the food that was consumed,” explains Grobe.

It’s possible that this finding explains the well-known digestive ill effects of certain fast foods that are high in both fat and salt, he adds.

Through his research on hypertension, Grobe knew that salt levels affect the activity of an enzyme called renin, which is a component in the renin- angiotensin system, a hormone system commonly targeted clinically to treat various cardiovascular diseases. The new study shows that angiotensin mediates the control of digestive efficiency by dietary sodium.

The clinical usefulness of reducing digestive efficiency for treating obesity has been proven by the drug orlistat, which is sold over-the-counter as Alli. The discovery that modulating the renin-angiotensin system also reduces digestive efficiency may lead to the developments of new anti-obesity treatments.

Lutter, who also is an eating disorders specialist with UI Health Care, notes that another big implication of the findings is that we are just starting to understand complex interactions between nutrients and how they affect calorie absorption, and it is important for scientists investigating the health effects of diet to analyze diets that are more complex than those currently used in animal experiments and more accurately reflect normal eating behavior.

“Most importantly, these findings support continued and nuanced discussions of public policies regarding dietary nutrient recommendations,” Grobe adds.

http://www.eurekalert.org/pub_releases/2015-06/uoih-hsp061115.php

By Rachel Feltman

If you give a mouse an eating disorder, you might just figure out how to treat the disease in humans. In a new study published Thursday in Cell Press, researchers created mice who lacked a gene associated with disordered eating in humans. Without it, the mice showed behaviors not unlike those seen in humans with eating disorders: They tended to be obsessive compulsive and have trouble socializing, and they were less interested in eating high-fat food than the control mice. The findings could lead to novel drug treatments for some of the 24 million Americans estimated to suffer from eating disorders.

In a 2013 study, the same researchers went looking for genes that might contribute to the risk of an eating disorder. Anorexia nervosa and bulimia nervosa aren’t straightforwardly inherited — there’s definitely more to an eating disorder than your genes — but it does seem like some families might have higher risks than others. Sure enough, the study of two large families, each with several members who had eating disorders, yielded mutations in two interacting genes. In one family, the estrogen-related receptor α (ESRRA) gene was mutated. The other family had a mutation on another gene that seemed to affect how well ESRRA could do its job.

So in the latest study, they created mice that didn’t have ESRRA in the parts of the brain associated with eating disorders.

“You can’t go testing this kind of gene expression in a human,” lead author and University of Iowa neuroscientist Michael Lutter said. “But in mice, you can manipulate the expression of the gene and then look at how it changes their behavior.”

It’s not a perfect analogy to what the gene mutation might do in a human, but the similarities can allow researchers to figure out the mechanism that causes the connection between your DNA and your eating habits.

The mice without ESRRA were tested for several eating-disorder-like behaviors: The researchers tested how hard they were willing to work for high fat food when they were hungry (less, it seemed, so much so that they weighed 15 percent less than their unaltered littermates), how compulsive they were, and how they behaved socially.

In general, the ESRRA-lacking mice were twitchier: They tended to overgroom, a common sign of anxiety in mice, and they were more wary of novelty, growing anxious when researchers put marbles into their cages. They also showed an inability to adapt: When researchers taught the mice how to exit a maze and then changed where the exit was, the mice without ESRRA spent way more time checking out the area where the exit should have been before looking for where it had gone.

The social changes were even more striking: Mice will usually show more interest in a new mouse than one they’ve met before, but in tests the modified mice showed the opposite preference, socializing with a familiar mouse when a new one was also presented.

They were also universally submissive to other mice, something the researchers detected with a sort of scientific game of chicken. Two mice are placed at either end of a tube, and one always plows past the other to get to the opposite side. It’s just the way mice size each other up — someone has to be on top. But every single one of the modified mice let themselves get pushed around.

“100% of the mice lacking this gene were subordinate,” Lutter said. “I’ve never seen an experiment before that produced a 0% verses 100% result.”

The avoidance of fats has an obvious connection to human disorders. But the social anxiety and rigidity are also close analogies to disordered eating in humans.

Now that Lutter and his colleagues know that the gene does something similar in mice, they can start looking for the actual mechanism that’s tripping these switches in the brain. They know that the gene’s pathway is very important for energy metabolism, especially in the breakdown of glucose. It’s possible that mutations in the gene cause some kind of impairment in neurons’ ability to get and process energy, but they can’t be sure yet.

They’ll see if they can pinpoint affected neurons and fix them. They’re also going to test some drugs that are known to affect this gene and its pathways. It’s possible that they’ll land on a treatment that helps calm these negative behaviors in affected mice, leading to treatments for humans with the mutation.

http://www.washingtonpost.com/news/speaking-of-science/wp/2015/04/09/scientists-manage-to-give-mice-eating-disorders-by-knocking-out-one-gene/

Open Access Article here: http://www.cell.com/cell-reports/abstract/S2211-1247(15)00301-0

The more scientists study pigeons, the more they learn how their brains—no bigger than the tip of an index finger—operate in ways not so different from our own.

In a new study from the University of Iowa, researchers found that pigeons can categorize and name both natural and manmade objects—and not just a few objects. These birds categorized 128 photographs into 16 categories, and they did so simultaneously.

Ed Wasserman, UI professor of psychology and corresponding author of the study, says the finding suggests a similarity between how pigeons learn the equivalent of words and the way children do.

“Unlike prior attempts to teach words to primates, dogs, and parrots, we used neither elaborate shaping methods nor social cues,” Wasserman says of the study, published online in the journal Cognition. “And our pigeons were trained on all 16 categories simultaneously, a much closer analog of how children learn words and categories.”

For researchers like Wasserman, who has been studying animal intelligence for decades, this latest experiment is further proof that animals—whether primates, birds, or dogs—are smarter than once presumed and have more to teach scientists.

“It is certainly no simple task to investigate animal cognition; But, as our methods have improved, so too have our understanding and appreciation of animal intelligence,” he says. “Differences between humans and animals must indeed exist: many are already known. But, they may be outnumbered by similarities. Our research on categorization in pigeons suggests that those similarities may even extend to how children learn words.”

Wasserman says the pigeon experiment comes from a project published in 1988 and featured in The New York Times in which UI researchers discovered pigeons could distinguish among four categories of objects.

This time, the UI researchers used a computerized version of the “name game” in which three pigeons were shown 128 black-and-white photos of objects from 16 basic categories: baby, bottle, cake, car, cracker, dog, duck, fish, flower, hat, key, pen, phone, plan, shoe, tree. They then had to peck on one of two different symbols: the correct one for that photo and an incorrect one that was randomly chosen from one of the remaining 15 categories. The pigeons not only succeeded in learning the task, but they reliably transferred the learning to four new photos from each of the 16 categories.

Pigeons have long been known to be smarter than your average bird—or many other animals, for that matter. Among their many talents, pigeons have a “homing instinct” that helps them find their way home from hundreds of miles away, even when blindfolded. They have better eyesight than humans and have been trained by the U. S. Coast Guard to spot orange life jackets of people lost at sea. They carried messages for the U.S. Army during World Wars I and II, saving lives and providing vital strategic information.

UI researchers say their expanded experiment represents the first purely associative animal model that captures an essential ingredient of word learning—the many-to-many mapping between stimuli and responses.

“Ours is a computerized task that can be provided to any animal, it doesn’t have to be pigeons,” says UI psychologist Bob McMurray, another author of the study. “These methods can be used with any type of animal that can interact with a computer screen.”

McMurray says the research shows the mechanisms by which children learn words might not be unique to humans.

“Children are confronted with an immense task of learning thousands of words without a lot of background knowledge to go on,” he says. “For a long time, people thought that such learning is special to humans. What this research shows is that the mechanisms by which children solve this huge problem may be mechanisms that are shared with many species.”

Wasserman acknowledges the recent pigeon study is not a direct analogue of word learning in children and more work needs to be done. Nonetheless, the model used in the study could lead to a better understanding of the associative principles involved in children’s word learning.

“That’s the parallel that we’re pursuing,” he says, “but a single project—however innovative it may be—will not suffice to answer such a provocative question.”

http://now.uiowa.edu/2015/02/pigeon-power