Trainees will benefit from USF Health’s increase in nationally recognized faculty with research expertise in blood vessel inflammation linked to heart, lung and other diseases

TAMPA, Fla (Feb. 3, 2022) — The University of South Florida recently received a highly competitive National Institutes of Health (NIH) Institutional Training Grant (Award Number T32HL160529), boosting the USF Health Morsani College of Medicine’s (MCOM) capacity to prepare the next generation of scientists in an emerging area of research applicable to many major diseases.

The NIH’s National, Heart, Lung, and Blood Institute awarded MCOM total expected funds of $1.35 million over the next five years to support the comprehensive training of pre- and postdoctoral scientists focused on research in vascular inflammation and injury. Trainees will be selected from PhD candidates and graduates, as well as MD graduates in residency or fellowship programs related to cardiovascular sciences. They will receive stipends and financial support for attending scientific conferences.

The USF Health Morsani College of Medicine’s new NHLBI Institutional Training Grant for research in vascular inflammation and injury is directed by Sarah Yuan, MD, PhD (center), professor and chair of Molecular Pharmacology and Physiology (MPP).  Joining Dr. Yuan are core MPP members of the T32 grant team, from left to right: Victoria Mothershed, the program’s administrative manager; Thomas Taylor-Clark, PhD, the program’s associate director; and Jerome Breslin, PhD, who designs and oversees the program’s curriculum. — Photo by Allison Long, USF Health Communications

“This is the first NIH T32 institutional training award obtained by USF’s college of medicine in the last 20 years,” said program director Sarah Yuan, MD, PhD, professor and chair of the Department of Molecular Pharmacology and Physiology. “It represents a critical step in raising our national prominence in training the next generation of translational researchers.”

Translational research is the process of efficiently moving scientific discoveries made in the laboratory into the clinic, hospital, or community to treat patients and improve health.

“Our goal is to prepare these trainees with the strong knowledge, skills and vision for leading independent research that will decipher complex cellular and molecular mechanisms and develop new diagnostic and therapeutic targets for cardiovascular disease and other conditions affected by inflammation,” said Dr. Yuan, who holds the USF Health Deriso Endowed Chair in Cardiovascular Research.

Inflammation commonly underlies the onset and progression of various diseases or injuries in multiple organs, including the heart, brain, lung, kidney, gut, and placenta. Recently, Dr. Yuan noted, this includes the discovery that vascular inflammation in response to coronavirus infection is a leading cause of severe illness and death in COVID patients.

A better understanding of the physiological processes contributing to vascular inflammation can lead to more precise and much-needed ways to diagnose, treat, and possibly prevent its harmful effects,

The new training program takes advantage of the substantial number of NIH-funded researchers recruited to MCOM under the leadership of Charles J. Lockwood, MD, senior vice president for USF Health and dean of MCOM. Many of these nationally preeminent faculty hires are experts in inflammation research and the vascular biology associated with heart, lung, neurodegenerative, or other diseases. Investment in new and renovated laboratories, and research facilities with shared, highly specialized equipment has risen along with the influx of new investigators.

Up to 25 NIH-funded faculty mentors across seven MCOM departments (Molecular Pharmacology and Physiology, Internal Medicine, Surgery, Obstetrics and Gynecology, Pediatrics, Pathology and Medical Engineering), including those affiliated with the USF Health Heart Institute, the USF Health Neuroscience Institute, and several other research centers, will mentor top students recruited to the T32 program.

“Our commitment to building the research infrastructure, expertise and curriculum needed to attract the highest caliber of faculty and academically talented students will not waver,” Dr. Lockwood said. “This new institutional training award is a tremendous addition to our growing research portfolio, one that helps feed a pipeline of diverse young scientists driven to transform meaningful discoveries into best-practice patient care. They will be well prepared to understand and help solve complex problems beyond the scope of individual disciplines or laboratories.”

The latest scientific equipment and imaging techniques will help trainees investigating the complex cellular and molecular processes contributing to inflammatory changes in and surrounding the tiniest blood vessels.  — Photo by Allison Long, USF Health Communications

The program’s curriculum is composed of rigorous courses and workshops to build competency in critical thinking and communication, an intensive hands-on research experience, and a personalized career development plan. Trainees will have access to the latest technologies, including viable human organ models to study the effects of inflammatory disease and its treatment, and high-resolution imaging techniques to see changes in blood flow, cells, proteins, and other structures within and outside the tiniest vessels.

Program director Dr. Yuan is joined by several core members of MCOM Molecular Pharmacology and Physiology, including Thomas Taylor-Clark, PhD, the program’s associate director; Jerome Breslin, PhD, who designs and oversees the program’s curriculum; and Victoria Mothershed, the program’s administrative manager.

“It took the support of leadership, dedicated teamwork, and perseverance to get here,” Dr. Yuan said. “We’re thrilled to receive this institutional award and want it to be catalyst for more such programs cultivating leaders in biomedical and translational science.”

Targeting the gene Foxo1 may offer an early treatment approach for hereditary lymphedema, USF Health preclinical study reports

Principal investigator Ying Yang, PhD, is an assistant professor of molecular pharmacology and physiology in the USF Health Morsani College of Medicine and a member of the college’s Heart Institute. | Photo by Allison Long, USF Health Communications

Tampa, FL (Aug. 9, 2021) — A University of South Florida (USF Health) preclinical study unexpectedly identified the gene Foxo1 as a potential treatment target for hereditary lymphedema. The research, published July 15 in The Journal of Clinical Investigation, was done with colleagues from Tulane University and the University of Missouri.

Lymphedema — a chronic condition in which lymphatic (lymph) fluid accumulates in soft tissue under the skin, usually in the arms and legs — causes minor to painfully disfiguring swelling. Primary, or hereditary, lymphedema is rare, present at birth and caused in part by genetic mutations that regulate normal lymphatic valve development. Secondary, or acquired, lymphedema is caused by damage to the lymphatic system from surgery, radiation therapy, trauma, or parasitic infection. In the U.S., lymphedema most commonly affects breast cancer patients, with prevalence ranging from 10 to 40% after lymph node removal and radiation therapy.

While lymphedema can be managed with massage and compression garments, no treatment exists to address its underlying cause: the build-up of fluid that eventually backs up in the lymph system like an overflowing sink with a blocked drain. This stagnant lymph triggers an inflammatory response that can induce connective and fatty tissue to form and harden the skin, restricting movement and increasing the risk of recurrent infections.

Green immunostained image of a lymphatic vessel with one valve in the center and another in the top left corner. To the upper right of the lymph vessel is a large vein. | Photo courtesy of Joshua Scallan, PhD.

“The later fibrosis stage of lymphedema cannot be massaged away,” said study principal investigator Ying Yang, PhD, assistant professor of molecular pharmacology and physiology at the USF Health Morsani College of Medicine. “Targeting lymph valves early in the disease is one critical aspect in identifying an effective treatment for lymphedema. If the disease progresses too far, it’s difficult to reverse.”

Valve loss or dysfunction that disrupts the flow of lymph fluid is strongly associated with lymphedema in patients. But no one has discovered whether new valves can be grown or if defective ones can be fixed.

The USF Health-led study shows that both are possible.

Dr. Yang’s group hypothesized that the protein encoded by the gene Foxo1 plays a key role in lymph valve formation based on an earlier USF Health discovery of cell signaling processes controlling formation of lymph valves. The researchers showed that deleting a single gene — lymphatic vessel-specific Foxo1 — promoted the growth of markedly more valves in both young postnatal mice and adult mice than in control littermates without Foxo1 deletion. Furthermore, deleting Foxo1 in a mouse model mimicking human lymphedema-distichiasis syndrome fully restored the both the number of valves and valve function.

Dr. Yang (left) and with biologist Luz Knauer | Photo by Allison Long, USF Health Communications

“It was exciting to see that Foxo1 is the only gene so far reported that, when deleted, induces more lymphatic valves to form, instead of inhibiting valve growth,” said Dr. Yang, a member of the USF Health Heart Institute. “We actually reversed valve loss and repaired the structure and function of defective valves in a genetic mutation model of lymphedema…That type of discovery makes a study clinically relevant.”

The lymphatic circulatory system – a parallel of the blood vessel circulatory system – helps maintain healthy fluid balance in the body by collecting and controlling the flow of extra lymph fluid that leaks from tissue. This complex network propels watery lymph fluid carrying proteins, nutrients and toxin-destroying immune cells through the body in one direction before returning the fluid to circulating blood. Small valves inside lymph vessels open and close in response to force exerted by the lymph fluid, moving it forward and preventing backward flow into tissues.

Dr. Yang in her lab where she researches lymphedema, which in the U.S. most commonly occurs in some breast cancer patients after lymph node removal and radiation therapy. Some of the research is light sensitive and must be conducted in near darkness. | Photo by Allison Long, USF Health Communications

Among the key study findings:

• The protein FOXO1 (encoded by gene Foxo1) inhibits lymph valves from developing by suppressing many genes, which collectively contribute to the multi-step process of making a mature valve. FOXO1 behaves like a brake on a set of valve-forming genes, Dr. Yang said. “Once the brake is removed, all those genes can now be expressed so that new valves can successfully grow.”

• Inactivation (knockout) of Foxo1 in lymphatic endothelial cells (LEC) of young postnatal mice promoted valve formation at multiple stages. Likewise, deleting LEC-specific Foxo1 in adult mice also increased valve formation, compared to control mice without the gene knockout.

• A mouse model of lymphedema-distichiasis syndrome had 50% fewer lymphatic valves and the remaining valves closed abnormally and exhibited fluid backflow. But when Foxo1 was deleted, the number of valves increased to the same levels as those in healthy control mice and the structure of defective valves was restored to normal. Further analysis showed that the loss of Foxo1 also significantly improved valve function in this mouse model of human primary lymphedema disease.

Photo by Allison Long | USF Health Communications

This study was supported by grants from the National Heart, Lung, and Blood Institute, a part of the National Institutes of Health. USF Health’s Joshua Scallan, PhD, was the lead author.

The powerful genetic tool distinctly identifies P2X2-expressing cells and can selectively manipulate them to better understand sensory nerve function and find targeted treatments

tdTomato (red) expression in nodose sensory nerve cells expressing P2X2. | Image courtesy of Thomas Taylor-Clark, USF Health; published in eNeuro: https://doi.org/10.1523/ENEURO.0203-20.2020

TAMPA, Fla. (Aug. 5, 2020) — Despite frequent news announcing “medical breakthroughs,” advancements in biomedical and clinical science typically happen incrementally. Scientists refine our understanding of how the world works by harnessing new tools and data that can challenge conventional thinking – a continual process of revision that elicits new answers to old questions, and often poses different questions.

In an eNeuro paper published July 15, University of South Florida Health Morsani College of Medicine researchers describe a reporter mouse strain they created in pursuit of a new way to answer an old question: Is purinergic receptor gene P2X2 expressed in particular populations of sensory nerve cells?

“We needed a suitable mouse model to visualize where P2X2 is located so we might prove the gene is actually expressed in a very discrete group of sensory nerves. And because, moving forward, we want a reporter system that allows us to manipulate these vagal nodose nerves in precise, varied ways for therapeutic purposes,” said senior author Thomas Taylor-Clark, PhD, a professor in the  Department of Molecular Pharmacology and Physiology.

“This paper is an example of how reexamining questions with better techniques leads to clearer understanding, and in this day and age the clarity and reproducibility of data is a paramount issue in science.”

Thomas Taylor-Clark, PhD, professor of molecular pharmacology and physiology at USF Health, studies sensory airway nerves affecting defensive behaviors, including cough.

The P2X2 receptor (P2X2 for short) belongs to a family of P2X ion channels that sit on the surface of cell membranes and are activated by the neurotransmitter adenosine triphosphate (ATP). P2X2 plays a key role in sensory processes, including taste, hearing, some aspects of blood pressure regulation, and sensing physical stimuli in visceral organs like the lungs and bladder.

Dr. Taylor-Clark studies airway sensory nerves affecting defensive behaviors, including cough, and what happens when they go wrong in disease and injury. To further their research, his team needed a more reliable approach to distinguish which subsets of cells express P2X2, especially in the brain and spinal cord (central nervous system) and the peripheral nervous system (nerves outside the brain and spinal cord). Existing pharmacological and biochemical techniques were not selective enough, yielding dramatically different gene expression patterns that hamper accurate estimates of P2X2-expressing cell types.

So, the USF Health researchers created a knockin mouse incorporating a powerful genetic approach that could be used in future experiments. They made a mouse that expresses the bacterial enzyme cre recombinase in cells expressing the P2X2 gene. The enzyme manipulates specific sites (lox sequences) in DNA. Then, they bred this P2X2-cre mouse with a second mouse having specific lox sequences that produce substantial levels of tdTomato – a bright red fluorescent protein – under the control of cre. In offspring of the P2X2-cre mice and the cre-sensitive mice, tdTomato is robustly expressed and specifically reported (visualized) in P2X2-expressing cells, even when levels of P2X2 expression are low.

“With this system, it’s easier to see any cell type you want to investigate,” Dr. Taylor-Clark said. “And, since many mouse strains have different cre-sensitive genetic expression patterns, you can manipulate virtually any gene or genetic process to test its role in tissue/organ function with a modular approach.”

tdTomato (red) expression in the vagal ganglia of reporter mouse strain for P2X2, with a dotted line separating the subsets of nodose (bottom) and jugular (top) nerve cells. | Images courtesy of Thomas Taylor-Clark, USF Health; published in eNeuro: https://doi.org/10.1523/ENEURO.0203-20.2020

The researchers detailed where they found P2X2. As they suspected, the gene was expressed predominantly in the vagal sensory nerve system, where cell clusters relay sensory information about the state of the body’s organs to the central nervous system. In particular, almost all nodose vagal neurons (more than 85%) expressed P2X2, compared to nearly none of the jugular neurons. (Nodose and jugular are the two groups of neurons in the vagal system.).

The researchers demonstrated some P2X2 expression in the tongue’s taste buds, the carotid body, trachea (windpipe) and esophagus. They observed P2X2 in hair and support cells of the cochlea (inner ear bone important in hearing), but not, as some previous studies reported, in sensory nerves innervating the hair cells.

With a few exceptions, P2X2 expression was absent in central nervous system cell types. Earlier reporter mouse studies using established biochemical techniques indicated P2X2 expression in virtually every area of the brain, so the USF Health group was surprised to find P2X2 expressed in a very limited subset of neurons, Dr. Taylor-Clark said.

“But, actually, that was encouraging because if we manipulate (gene expression) we want the effects to be very narrow and targeted, not widespread,” he added. “Selectivity is the hallmark of any therapeutic approach. Otherwise, you will not get the beneficial outcome you want, and you may get side effects you don’t want.”

Other studies have suggested that activating nodose sensory nerves diminishes cough, while activating jugular sensory nerves increases cough. Dr. Taylor-Clark hopes to test whether nodose neurons can protect against chronic cough by modifying the P2X2-cre system to selectively silence only the nodose neurons, without adversely blocking all other nerve impulses.

Image courtesy of Thomas Taylor-Clark, USF Health; published in eNeuro: https://doi.org/10.1523/ENEURO.0203-20.2020

“Our next step is to manipulate this P2X2-cre system so that, instead of expressing tdTomato, we can express a protein that upon addition of a drug then either artificially activates or inhibits P2X2-expressing cells,” he said. “Currently, little is understood about the physical interaction of the nodose nerve terminals (endings) in the trachea and other target organs, and how that changes with disease. Our goal is a detailed knowledge of all the different subtypes of sensory nerves and how they control organ function, so we can help drive targeted neuromodulaton therapies.”

The USF Health work was supported by the National Institutes of Health Common Fund’s Stimulating Peripheral Activity to Relieve Conditions (SPARC) program, the National Institute for Neurological Disorders and Stroke, and the National Institute of Diabetes and Digestive and Kidney Diseases.

Physician-scientist Dr. Sarah Yuan will expand her nationally prominent microvascular research program to include COVID-19

TAMPA, Fla. — Sarah Yuan, MD, PhD, professor and chair of the Department of Molecular Pharmacology and Physiology at the USF Health Morsani College of Medicine, has received a highly competitive National Heart, Lung, and Blood Institute (NHLBI) Outstanding Investigator Award to continue breaking new ground in microvascular and circulation research.

Dr. Yuan is the first USF faculty member to receive this particular award — $6.25 million from the National Institute of Health’s NHLBI to support her ambitious research program, instead of funding individual projects, over the next seven years.

Sarah Yuan, MD, PhD

The NHLBI Outstanding Investigator Award (OIA) recognizes scientists who have a track record of highly successful and innovative research and are considered likely to make major advances in heart, lung, blood or sleep research with the support of long-term, stable funding. Recipients of the prestigious award also demonstrate outstanding mentorship of students and junior scientists and leadership in cardiovascular research.

“I am so excited to receive this award because it provides long-term support for my work at a high level and allows tremendous freedom and flexibility to pursue research directions in newly emerging areas,” said Dr. Yuan, who trained as a trauma surgeon early in her career and has a secondary appointment as a professor of surgery. She also holds the Deriso Endowed Chair in Cardiovascular Disease at USF Health.

“I feel honored to have been recognized at the national level, and want to thank Dr. Charles Lockwood (USF Health senior vice president and Morsani College of Medicine dean) for supporting this application as well as the development of my research program,” she added. “I hope this will help expand our grant portfolio for cardiovascular and lung research at USF Health.”

Dr. Yuan’s research encompasses investigation of the loss of small blood vessel integrity during inflammation with the aim of discovering new diagnostics and treatments targeting vascular inflammation. With the Outstanding Investigator Award, she plans to broaden her research to look for tissue-specific biomarkers that might be used to diagnose and treat COVID-19, a respiratory virus that attacks the endothelial cells lining blood vessels and causes inflammation and damage in the lungs, heart, kidneys, brain and gut.

“Blood vessels supply every organ and tissue in the body,” she said. “So I’m fortunate that my research can apply to many types of disease processes, including investigating the COVID-19 host immune response characterized by blood vessel abnormalities, clotting, and circulation problems in multiple organ systems.”

A nationally recognized leader who studies the interactions between blood cells and endothelial cells, Dr. Yuan has developed cutting-edge theories on the molecular processes controlling microvascular permeability under normal and disease conditions. Through microvascular permeability (or leakiness) – an early step in the body’s inflammatory response to injury or to invading viruses, bacteria or other pathogens – the blood vessel wall allows the flow of fluid, proteins, small molecules, or white blood cells (neutrophils) on their way to the site of inflammation.

Dr. Yuan’s discoveries have significantly advanced the understanding of the complex interplay between signaling molecules and endothelial structures that regulate vascular barrier function during trauma, infection, sepsis, ischemia/reperfusion injury, atherosclerosis, and diabetes. She identified several molecules that play key roles in mediating leakage from blood vessel walls. Her laboratory has pioneered molecular biology and imaging techniques to learn more about how the vascular barrier malfunctions, which can lead to excessive leaking of fluid and proteins from blood vessels, tissue swelling and ultimately organ failure.

Dr. Yuan’s laboratory has pioneered molecular biology and imaging techniques to learn more about the permeability of tiny blood vessels and how the vascular barrier malfunctions. She uses the state-of-the-art resources at USF Health’s Muma Advanced Microscopy and Cell Imaging Core facility.

Throughout her career Dr. Yuan has emphasized the translational value of research work that links novel molecular findings to the physiological processes underlying injury and illness through rigorous analysis of human models of disease, as well as animal models and cell cultures. Using trauma patient blood samples, Dr. Yuan is collaborating with David J. Smith, MD, professor and chair of the USF Health Department of Plastic Surgery, to identify novel diagnostic markers of inflammatory injury that might better guide the precision treatment of trauma and burns, as well as prevent secondary infection and other complications.

Dr. Yuan has been continuously funded by the NHLBI for more than 25 years. She is the author of more than 85 peer-reviewed articles in high-impact journals, including Nature Communications, Circulation, Circulation Research, Cardiovascular Research, and Arteriosclerosis, Thrombosis, and Vascular Biology (ATVB). She is a fellow of the American Association for the Advancement of Science and the 2020 recipient of the Eugene M. Landis Award from The Microcirculatory Society.

Dr. Yuan has served on numerous NIH study sections and work groups. She is currently a regular member of a standing NIH study section, Hypertension and Microcirculation, and she routinely participates in NIH grant reviews for other areas, including the Surgery, Anesthesiology and Trauma, the Vascular Biology and Hematology, and the Surgical Sciences, Biomedical Imaging and Bioengineering panels.

-Photos by Allison Long, USF Health Communications and Marketing

New USF Health research on endothelial-derived microvesicles, using models of sepsis, may be useful for better diagnosis and treatment of inflammatory or infectious diseases

A new preclinical study by the University of South Florida Health (USF Health) Morsani College of Medicine sheds light on how tiny bubble-like particles flowing in the blood can serve as diagnostic markers for certain diseases while also contributing to disease progression.

Microvesicles (green) interacting with target endothelial cells (nuclei stained blue) to increase both stress fiber formation (red) and activation of cellular contraction proteins (yellow). The interaction contributes to greater vascular wall barrier permeability (leakage). Image courtesy of Victor Chatterjee (University of South Florida), originally published by Oxford University Press, Cardiovascular Research, https://doi.org/10.1093/cvr/cvz238

Cells lining the inner surface of blood vessels, called endothelial cells, have the ability to package and release microscopic vesicles (0.1 to 1 micrometer in diameter) into the blood circulation. These microvesicles carry unique cargo of molecules under different health or disease conditions; thus, by identifying their specific cargo content or molecular signature, doctors can better diagnose the nature and extent of a medical problem.

Researchers in the laboratory of Sarah Yuan, MD, PhD, at the USF Health Department of Molecular Pharmacology and Physiology, discovered that endothelial cells produce microvesicles containing a high level of c-Src protein during sepsis, a life-threatening condition that causes systemic inflammation and multiple organ failure. Their study, conducted using cell cultures and an animal model of sepsis, was recently reported in Cardiovascular Research, a highly rated journal sponsored by the European Society of Cardiology.

Most intriguingly, the researchers found that in addition to providing a unique marker that signifies the status of inflammation in blood vessels, these c-Src enriched microvesicles play an active role in causing vascular wall injury and barrier leakage.

Victor Chatterjee, MD, PhD, a postdoctoral fellow in the Department of Molecular Pharmacology and Physiology, was the paper’s first author. He works in the laboratory of departmental chair Sarah Yuan, MD, PhD. | Photo by Allison Long, USF Health Communications and Marketing

“Microvesicles produced by inflamed endothelial cells circulate in the blood and target healthy barrier cells by unloading their bioactive cargo into receiving cells. They ‘tell’ the receiving cells to change behavior, leading to an increased permeability of the barrier,” said first author Victor Chatterjee, MD, PhD, a postdoctoral fellow working in Dr. Yuan’s lab.

Like the breech of a protective levy, increased permeability of the endothelial barrier allows blood fluids and proteins to leak through the blood vessel wall into surrounding tissues. Because this leak process underlies sepsis, traumatic injury, atherosclerosis, cancer, and several types of inflammatory or immunological disorders, the authors suggest that endothelial-derived microvesicles may have potential applications in developing new molecular markers or therapeutic targets for better diagnosis and treatment of these diseases.

This paper also reports an in-depth analysis of the molecular mechanisms underlying vascular leakage caused by endothelial derived microvesicles.

A key finding is that the circulating microparticles are highly interactive. They bind to the membrane of targeted endothelial cells and get inside these cells, where they unload c-Src cargo to turn on the signal for cell contraction and cell-to-cell junction opening. Since junctions are critical structures that “glue” neighboring cells together to form the vascular wall barrier, opening them results in blood leakage.

Dr. Yuan, a member of the USF Health Heart Institute, was senior author of the NIH-supported study published in Cardiovascular Research.

In an effort to translate their benchwork to bedside care, the USF Health researchers plan to use blood samples from human patients to determine if and how the molecular signature of microvesicles change over time or correlate with disease severity, Dr. Chatterjee said.  A better understanding of how these tiny cargo carriers function in the human disease process could help guide physicians in better managing infectious or inflammatory diseases, he said.

The senior author of the Cardiovascular Research paper is Dr. Yuan, professor and department chair, who holds the USF Health Deriso Endowed Chair in Cardiovascular Disease. Dr. Yuan’s research has been supported by the National Institutes of Health: National Heart, Lung, and Blood Institute, and National Institute of General Medical Sciences.

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Targeting VE- cadherin signaling pathways holds promise for treating lymphedema’s debilitative swelling, USF-led preclinical research suggests

Green immunostained image of a lymphatic vessel with one valve in the center and another in the top left corner. To the upper right of the lymph vessel is a large vein. | Photo courtesy of Joshua Scallan

TAMPA, Fla. (Aug. 27, 2019) — Lymphedema, resulting from a damaged lymphatic system, can be a debilitating disease in which excess protein-rich fluid (lymph) collects in soft tissues and causes swelling — most often in the arms or legs.  Symptom severity varies, but the chronic swelling can lead to pain, thickened skin, disfigurement, loss of mobility in affected limbs, and recurrent infections.

While lymphedema can be managed with massage and compression garments or electronic sleeve-like pumps, no treatment exists to address its underlying cause: the abnormal build-up of lymph fluid that expands tissue like a water-logged sponge.

Now, a mouse model study led by the University of South Florida (USF Health) Morsani College of Medicine has identified new cellular processes controlling development of the small valves inside lymphatic vessels, which prevent lymph fluid from flowing the wrong way back into tissues. The one-way valves work with muscles to help propel lymph fluid through the body and regulate flow. The new findings suggest that targeting signaling pathways involved in creating and maintaining lymphatic valves may one day be a viable therapy for patients coping with lymphedema.

The study was published online Aug. 27 in Cell Reports.

Joshua Scallan, PhD, assistant professor of molecular pharmacology and physiology at USF Health Morsani College of Medicine, focuses on the molecular and cellular processes of lymphatic vessels. The lymphatic system parallels the blood vessel circulatory system, but has been studied less extensively.

“We knew that lymph flow was required for the valves to form and function throughout life, but we did not know how the endothelial cells that make up the inner lining of lymphatic vessels can ‘sense’ the flow,” said senior author Joshua Scallan, PhD, assistant professor in the USF Health Department of Molecular Pharmacology and Physiology. “This study is the first to identify signaling pathways by which cells sense and respond to the mechanics of flow to keep the valves operating effectively — so that lymph fluid keeps moving forward.”

The lymphatic circulatory system – a parallel system to the blood vessels – is an extensive drainage network that acts as a conduit for immune cells (such as lymphocytes) and helps protect the body against infections. One of its primary jobs is to remove extra fluid (mostly water containing proteins, lipids, and other substances) that continuously leaks from tiny blood vessels into surrounding tissues just under the skin, Dr. Scallan said.

The lymph vessels, which carry lymph around the body, collects the leaked fluid (as much as 12 liters a day) and transports it away from the tissues. This lymph fluid is checked and filtered for bacteria, viruses and other harmful substances by lymph nodes clustered in various areas of the body, and eventually returned to the blood circulatory system through veins in the neck. If forward lymph flow is blocked or impaired, fluid does not drain from the tissues and results in the disease known as lymphedema.

Microscopic image of endothelial cells lining the lymphatic vessels. The protein VE-cadherin (stained green) is needed for lymphatic valves to form, mature and maintain the normal movement of lymph fluid. | Photo courtesy of Joshua Scallan

In a series of experiments, the researchers used a “conditional knockout” mouse model, developed in Dr. Scallan’s laboratory, in which production of the junction protein VE-cadherin was inactivated in lymphatic vessels. The gene for VE-cadherin, located where neighboring cells lining lymph vessels connect, was deleted in mice both before and after birth.

Among key findings of the preclinical study detailed in Cell Reports:

• Deletion of VE-cadherin prevented lymphatic valves from forming in the embryonic mice and caused disintegration of valves already developed in the postnatal mice. This indicates that the protein is required for lymphatic valves to form, mature and maintain the normal movement of lymph fluid away from tissues.
• Stimulating two different signaling pathways dependent upon VE-cadherin activation — β-catenin and AKT – partially rescued the loss of valves.
• The AKT signaling pathway was shown to promote the growth of new valves in normal, healthy mice.

“Our data explain how fluid forces at the lymphatic endothelial cell membrane regulate genes to control valve formation and maintenance,” Dr. Scallan and his fellow study authors concluded. “Future studies are needed to investigate the AKT signaling pathway to identify therapeutic targets that may safely enhance valve formation in lymphedema patients.”

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Millions of people worldwide suffer from lymphedema, predominantly in tropical and subtropical regions where filariasis (a parasitic infection) is common.  In the U.S. and most other developed countries, acquired (secondary) lymphedema is most commonly caused by breast cancer treatment: surgical removal of lymph nodes or radiation therapy. Hereditary (primary) lymphedema, caused by defective lymph vessels at birth, is rare.

USF Health researchers worked with colleagues at the Oklahoma Medical Research Foundation.  The study was supported by grants from the National Heart, Lung and Blood Institute, National Institutes of Health.

-Photos by Allison Long, USF Health Communications and Marketing

The new study, with collaboration from USF Health, establishes potential targets for treating diabetic damage to nerves regulating heart rate

Cardiac autonomic neuropathy, a common complication of diabetes, can increase the risk of severe heart disease, and sudden cardiac death caused by abnormal heart rhythms known as arrhythmias.  Earlier research at the USF Health Morsani College of Medicine, University of South Florida, and elsewhere has helped define how diabetes affects innervation of the heart and damages nerves that control involuntary (autonomic) regulation of body functions, including heart rate.

Now a new preclinical study, including USF Health collaborator Sami Noujaim, PhD, has discovered that inhibiting the enzyme glycogen synthase kinase-3B (GSK3ß) in heart muscle cells reduces dysfunctional parasympathetic nervous system activity associated with diabetes. Recently published in PLOS ONE, the Tufts University-led study used a mouse model for type 1 diabetes (Akita mouse) in which the cardiac-specific GSK3ß gene was selectively and partially inactivated.

Sami Noujaim, PhD

In particular, the findings support a new mechanism for understanding how overstimulation of GSK3ß in type 1 diabetes affects development of an abnormal cardiac parasympathetic response in diabetes and also suggests new targets for treating or preventing damage to nerves that regulate heart rate.

The sympathetic nervous system, which mobilizes the body’s “fight-or-flight” responses to stress, accelerates heart rate.  The “rest-and-digest” parasympathetic nervous system, which helps calm the body, slows heart rate.

These two components of the involuntary nervous system are normally in constant flux.  In fact, slight variations in the time between each heartbeat, known as heart rate variability, characterizes a healthy heart in which both sympathetic and parasympathetic systems communicate effectively to maintain regulatory balance.  Conversely, in cardiovascular disease and diabetes, heart rate variability decreases.

“Reduced heart rate variability is a harbinger of bad cardiovascular outcomes in the future,” said co-investigator Dr. Noujaim, associate professor of molecular pharmacology and physiology at USF Health. “So, we want to find a signaling pathway to target that can increase heart rate variability. Our goal is to reduce the likelihood of the diabetic heart developing poor cardiovascular outcomes, including arrhythmias.”

Dr. Noujaim directs a cardiac electrophysiology research laboratory, which has the tools to translate mouse heart activity into frequencies used to analyze beat-to-beat variations in heart rate. High frequencies are predominately generated from parasympathetic regulation of heart rate, while low frequencies result largely from sympathetic regulation.

Dr. Noujaim’s laboratory uses specialized equipment to measure the electrical activity of heart muscle cells, including those affected by diabetes.

Among some key findings of the PLOS ONE study:

• Decreasing the expression of GSK3ß in the hearts of the Akita mice reversed cardiac parasympathetic dysfunction. It also increased (improved) parasympathetic response, as measured by the increased high-frequency proportion of heart rate variability.
• Reducing GSK3ß expression also increased activity of IKACH in heart muscle cells of the diabetic mice. The parasympathetic nervous system slows down heart rate through activation of the IKACH potassium current in the cardiac cells. However, Dr. Noujaim said, when GSK3ß is upregulated in response to high glucose levels in the diabetic heart, it causes the suppression of the IKACH current. When IKACH is suppressed, the parasympathetic tone does not reach the heart, thereby allowing the heart-rate accelerating sympathetic nervous system tone to dominate and heart rate variability to decline, he added.
• Collectively, the series of experiments demonstrate that increased GSK3ß activity amplifies cardiac parasympathetic malfunction in type 1 diabetes through regulation of IKACH.

“The data further establish GSK3ß and the GSK3ß signaling pathway as potential therapeutic targets in the treatment and prevention of autonomic dysfunction in diabetic patients,” the study authors conclude.

The research was supported by the Juvenile Diabetes Research Foundation and National Institutes of Health grants.

The USF Health study, using a rat model for high blood pressure, helps explain the different nerve-induced physiological response to air pollution in patients with preexisting cardiovascular disease

Numerous studies have linked air pollution with cardiovascular disease, including evidence suggesting that chronic exposure accelerates the process of atherosclerosis.

TAMPA, Fla. (June 18, 2019) — Air pollution significantly increases the risk for premature deaths, particularly in people with underlying cardiovascular disease, clinical and epidemiological studies have determined

In healthy people, inhaling ozone or particle pollution triggers a defensive lung-heart reflex (pulmonary-cardiac reflex) that automatically slows heart rate to accommodate oxygen deficiency and help slow distribution of pollutants throughout the body. Yet, when patients with cardiovascular diseases breathe pollutants that same protective mechanism does not kick in.  Instead, their heart rates intermittently speed up, known as tachycardia, and can evoke a potentially deadly irregular heart rhythm, known as premature ventricular contractions.

What accounts for the difference?  University of South Florida Health (USF Health) researchers who study the role of sensory airway nerves in protective behaviors wanted to know.

Their preclinical findings, reported May 11 in The Journal of Physiology, help explain the altered physiological response to air pollution in patients with preexisting cardiovascular disease.

Thomas Taylor-Clark, PhD, of the USF Health Department of Molecular Pharmacology and Physiology, was senior author for the study.| Photo by Eric Younghans

Using a rat model for high blood pressure (hypertension), a common chronic cardiovascular condition, the USF Health team found that preexisting hypertension altered normal reflexes in the lungs to affect autonomic regulation of the heart when an irritant mimicking air pollution was inhaled. In particular, hypertension appeared to shift the reflex response from the parasympathetic nervous system to the sympathetic nervous system.  The sympathetic nervous system mobilizes the body’s defensive “fight-or-flight” response to a threat, including releasing adrenaline that increases heart rate. In contrast, the parasympathetic nervous system controls involuntary responses, including breathing and heart rate, while the body is at rest and maintains a state of calm.

“The speeding up of heart rate and abnormal heart beats (in the hypertensive rats) were due to the switching on of this ‘flight-or-fight’ nervous system not seen in the healthy animals exposed to noxious agents,” said senior author Thomas Taylor-Clark, PhD, associate professor of molecular pharmacology and physiology in the USF Health Morsani College of Medicine. “The heart was responding to an aberrant nerve-generated reflex that may worsen preexisting cardiovascular disease.”

To simulate effects of air pollution inhaled into the lungs — difficult to recreate in a laboratory setting — the USF researchers used allyl isothiocyanate, the pungent ingredient in wasabi and horseradish.  When healthy rats with normal blood pressure inhaled this irritant, their heart rates slowed as expected.  But, in the rats with chronic hypertension, inhaling the same irritant stimulated an increased heart rate accompanied by premature ventricular contractions.

Surprisingly, a rapid heart rate and abnormal heart rhythm did not occur when allyl isothiocyanate was intravenously injected into the hypertensive rats.

USF Health postdoctoral scholar J. Shane Hooper, PhD, was the study lead author.

“It did not evoke the peculiar reflex; instead, we observed a slowing of the heart rate like that seen in the rats with normal blood pressure,” Dr. Taylor-Clark said. “This suggests that the sensory airway nerves accessible by IV are different than those accessible by inhalation… so perhaps the pathways of airway sensory nerves (connecting organs like the heart and lungs with the brainstem,) are more complex than previously understood.”

Chronic hypertension may remodel airway sensory nerves controlling the pulmonary-cardiac reflex that helps defend the body against physical damage from air pollution, the USF study suggests. This remodeling, which may happen in the developmental stages of hypertension, could turn on inappropriate sympathetic nervous system excitation of the heart, Dr. Thomas-Taylor said.

By better understanding how cardiovascular disease changes neuronal interactions between the heart and lungs, the researchers hope to help doctors with treatment choices – and eventually discover new treatments.

“Our goal is to add another piece of information that clinicians could consider when selecting a best treatment for hypertension. In addition to the patient’s age, ethnicity and race, that might include whether the person lives in an area with high pollution levels,” he said. “In the long-term, if we can identify the nervous system mechanisms involved in remodeling the pulmonary-cardiac reflex, we can target those to develop new blood pressure drugs.”

The USF Health study was supported by grants from the American Heart Association, the National Institutes of Health’s National Heart, Lung and Blood Institute, and the NIH Commonfund.

A slice of the brainstem showing central projections of defensive nerves (red) into the medulla, where the nerves transmit signals to brainstem networks to control various involuntary functions like breathing, cough, swallowing, heart rate and blood pressure.

More than four in 10 Americans are at risk of disease and premature death due to air pollution, the American Lung Association reports. And, more than one-third of the deaths from lung cancer, heart disease and stroke are associated with air pollution, according to the World Health Organization.

The program, one of five awarded nationally this year, pairs faculty mentors from USF Health’s Heart Institute with promising students interested in cardiovascular or related biomedical research

The American Heart Association has awarded the USF Health Morsani College of Medicine a three-year, $60,000 grant to establish a summer training program intended to encourage promising undergraduate college students from all disciplines to consider careers in cardiovascular research.

The AHA-sponsored Undergraduate Student Fellowship grant was one of five newly awarded in 2018 to institutions across the United States. And, the 13 total undergraduate student fellowship programs currently funded by AHA include such prestigious institutions as Stanford University, the University of California San Diego, Pennsylvania State University and Carnegie Mellon University, to name a few.

USF Health’s Heart Institute Summer Undergraduate Research Fellowships program begins May 28, providing a 10-week research experience for five highly qualified junior and senior-level undergraduate students. This summer, all five student fellows entering the rigorous program are from USF, but qualifying U.S. and international students from other institutions can apply.  The AHA grant funds $4,000 stipends to support each trainee.

Jerome Breslin, PhD, professor in the USF Health Department of Molecular Pharmacology and Physiology, directs the newly awarded Summer Undergraduate Research Fellowships program sponsored by the American Heart Association. Dr. Breslin is pictured here in 2016 with two USF undergraduate students who conducted NIH and American Physiological Society fellowship-supported research in his laboratory — Sara Sampinato (left), chemical engineering major, and Andrea Burgess, biomedical sciences major. |Photo by Eric Younghans

“Our main goal is to recruit, train and mentor outstanding undergraduate students so they can become the next generation of graduate students and medical students who will be future leaders and advocates for cardiovascular research,” said Jerome Breslin, PhD, professor in the Department of Molecular Pharmacology and Physiology who directs this new AHA fellowship program at USF.

Five faculty members — all members of the USF Health Heart Institute with a solid track record of producing successful scientists — will mentor the undergraduate fellows through their individualized summer research experiences. Four faculty mentors are from Molecular Pharmacology and Physiology: Dr Breslin; Ruisheng Liu, MD, PhD, professor; Sami Noujaim, PhD, assistant professor; and Sarah Yuan, MD, PhD, departmental chair and professor. The fifth, Mack Wu, MD, holds appointments as a professor in the Department of Surgery and the Department of Molecular Medicine.

Graduate and doctoral students will also help mentor, giving the undergraduates an opportunity to interact with researchers at all levels, Dr. Breslin said.

The students will train in laboratories using cutting-edge technology to better understand the underlying mechanisms of diseases and discover new therapies.  Their cardiovascular research projects will focus on basic science areas in which the Heart Institute investigators are experts, including:  endothelial function, microcirculation, hypertension and cardiac arrhythmias.

In addition to laboratory research, students will participate in weekly seminars and workshops designed to instill scientific rigor, develop professional skills, and help them begin building a network needed to pursue a career in science.

“At the USF Health Heart Institute, we want to create the most vibrant research environment possible for all levels of trainees. That means reaching out to students who are still undergraduates to nurture their interest in cardiovascular or related biomedical sciences with a meaningful summer research experience. Ultimately we want to get more young scientists into the pipeline – and it’s never too early to start that process.”

This summer, the five student fellows participating in the AHA program were selected from among 18 applicants, including several from the University of Florida and Florida State University.  For the first summer, all these undergraduate participants are from USF:

USF Juniors (all majoring in biomedical sciences)
Nouhaila Beytour, Dr. Noujaim (faculty mentor); Veneta Dinova, Dr. Liu; Rebeca Gonzalez Jauregui, Dr. Breslin; and Ethan Zheng, Dr. Yuan.

USF Senior (majoring in public health)
Forouzandeh Farsaei, Dr. Breslin

For more information, please visit: www.health.usf.edu/medicine/mpp/surp.

NASA NEEMO 22 space analog simulates mission to Mars

TAMPA, Fla. (June 9, 2017) – University of South Florida associate professor Dominic D’Agostino, PhD, is one of four crew members selected for the NASA Extreme Environment Mission Operations (NEEMO) 22 expedition. He is the only member not affiliated with National Aeronautics and Space Administration (NASA) or European Space Agency (ESA).

Members of the NEEMO 22 crew, from left:  Planetary scientist Trevor Graff, ESA astronaut Pedro Duque, NASA astronaut Commander Kjell Lindgren, and USF researcher Dominic D’Agostino of the Department of Molecular Pharmacology and Physiology.

The NEEMO 22 crew splash down to the bottom of the Atlantic Ocean June 18, where they’ll spend 10 days in the Florida Keys National Marine Sanctuary located six miles off the coast of Key Largo, simulating a deep space mission with similar objectives to exploration on Mars. Living and working at the bottom of the ocean mimics the harsh, microgravity environment they will experience in space. They’ll conduct simulated spacewalks, test time delays in communication, evaluate a variety of tools and procedures to be used in future space missions.

Dr. D’Agostino was selected for his research conducted at the USF Hyperbaric Biomedical Research Laboratory (HBRL) on how extreme environments impact the human body. One of the countermeasures developed is a method to induce and sustain nutritional ketosis with ketone supplement formulations. Nutritional ketosis shifts the body’s metabolic state to burn fat rather than glucose as its primary fuel.

The USF-patented method will play a pivotal role in advancing the objectives of the NEEMO 22 mission. Dr. D’Agostino will be in a constant state of nutritional ketosis, which is proven to preserve the genome, protecting DNA. This is beneficial to NASA as it can countermeasure neurological risks that come with space travel such as space radiation, lack of oxygen and stress of small spaces.

Dr. Dominic D’Agostino with his wife Dr. Csilla Ari D’Agostino (NEEMO support diver) at the NASA NBL training center.

No other crew members will be in this metabolic state, creating a baseline for how environmental factors impact the human body in such extreme conditions. Data will also be collected from the other crew members on gut microbiome, body composition, cognitive tasks, vision assessment, sleep quality and a variety of other physiological parameters.

Other objectives of the NEEMO 22 crew include testing counter measure equipment, technology for precisely tracking assets and assess hardware sponsored by the ESA that will help crew members evacuate someone who has been injured on a lunar spacewalk.

Dr.  D’Agostino is an associate professor in Department of Molecular Pharmacology and Physiology and a certified diver.  He studies, develops and tests metabolic-based therapies, including ketogenic diets, ketone esters and ketone supplements, at the USF Hyperbaric Biomedical Research Laboratory, the only facility of its kind in the world. He is a member of various organizations including the Aerospace Medical Association and Undersea and Hyperbaric Medicine Society. His wife, USF assistant professor Dr. Csilla Ari D’Agostino, will join the mission as a NEEMO support diver. She’s a certified dive master and cognitive neuroscientist.  

Dr. D’Agostino practices using the Mini DNA analyzer. This device will help the NEEMO 22 crew understand how the microbiome of the habitat is changing (i.e. any potential pathogenic microbes).

Dr. D’Agostino conducts his research and development of metabolic-based therapies at the USF Hyperbaric Biomedical Research Laboratory.