USF Health physician-scientist Dr. Juan Carlos Cardet was co-first author for the New England Journal of Medicine article reporting results of the long-awaited PREPARE trial

TAMPA, Fla (Feb. 26, 2022) — Black and Latinx patients suffer disproportionately from asthma, a chronic inflammatory disease with symptoms including shortness of breath, tightness in the chest, coughing, and wheezing. They experience more severe asthma, higher rates of asthma-related emergency department visits and hospitalizations, and approximately double the asthma death rates compared to white patients.

A new approach for managing moderate-to-severe asthma, known as single maintenance and reliever therapy, combines two medications in one inhaler for control of underlying inflammation and quick relief of acute symptoms. While this strategy has gained interest and led to updated guidelines for patients, no studies to date have focused on Black and Latinx populations.

To help address the lack of comparable data for these underrepresented populations, the PREPARE (PeRson EmPowered Asthma RElief) trial enrolled 1,201 Black and Latinx adults (ages 18 to 75)  with moderate-to-severe asthma. The study was conducted November 2017 to April 2021 at 19 sites in the U.S., including the USF Health Morsani College of Medicine, and Puerto Rico. Participants were randomized to one of two groups. In addition to continuing their usual asthma medications, half of the participants (intervention group) received one-time instruction on how to use inhaled corticosteroids whenever they dispensed airway-opening reliever medications via a nebulizer or rescue inhaler. The other half (control group) also continued their usual care (UC) but did not dispense inhaled corticosteroids as needed to treat asthma attacks along with quick-relief medications. All patients had one instructional visit followed by 15 monthly questionnaires.

The PREPARE study demonstrated that this new intervention, called Patient-Activated Reliever-Triggered Inhaled Corticosteroids (PARTICS), substantially reduced severe asthma attacks, improved asthma control and quality of life, and decreased lost days from work or school.

The study results were presented by USF Health physician-scientist Juan Carlos Cardet, MD, MPH, Feb. 26 at the 2022 Annual Meeting of the American Academy of Allergy, Asthma & Immunology (AAAAI) and simultaneously published in The New England Journal of Medicine.

“Despite decades spent trying to find effective solutions to address the health disparities in asthma care, we haven’t made a significant dent in the problem,” said Dr. Cardet, an assistant professor in the USF Health Division of Allergy and Immunology. “The patient-centered PARTICS intervention we investigated works in underrepresented populations with poorly controlled asthma. It’s feasible, low cost, and may be easy to implement and help reduce the burden of complications from asthma if we can bring it to the clinic.”

Dr. Juan Carlos Cardet of the USF Health Morsani College of Medicine’s Allergy and Immunology Division studies better ways to treat poorly controlled asthma, including in underserved populations.

Dr. Cardet was the PREPARE study’s co-first author along with Elliot Israel, MD, the Gloria M. and Anthony C. Simboli Distinguished Chair in Asthma Research and director of Clinical Research in the Pulmonary and Critical Care Division, Brigham and Women’s Hospital. Thomas Casale, MD, a professor of medicine and pediatrics in the USF Health Division of Allergy and Immunology, helped execute the study as the USF site principal investigator.

Among PREPARE’s key findings:

• The annualized rate of severe asthma exacerbations was 0.69 per patient for participants in the PARTICS+UC group; the rate was 0.82 for the control group.
• Participants in the PARTICS+UC group also showed improved scores for asthma control and quality of life compared to patients in the control group.
• Those in the PARTICS+UC group also missed fewer days of school, work or other usual activities compared to the control group (13.4 versus 16.8 days)

A distinctive aspect of the PREPARE trial was the degree of engagement by patients to help optimize the study. Researchers collaborated with Black and Latinx adults with asthma as well as asthma caregivers — called Patient Partners — who are among the NEJM paper’s coauthors.

Dr. Cardet, working with Dr. Israel worked with other collaborators, designed a symptom-driven treatment approach consistent with what patients wanted; that is, an intervention intended to help control the chronic inflammation of asthma (with an inhaled corticosteroid) at the same time an inhaled reliever medication is delivered to ease severe flare-ups of symptoms.

Many patients are prescribed complicated regimens of controller medications to be taken daily, even on days when they experience no need for a fast-acting medication to open their constricted airways,” Dr. Cardet said. “In real life, patients may or may not adhere to that regimen when they’re feeling OK, but they will use their medications when symptoms arise.”

This work was supported by a Patient-Centered Outcomes Research Institute (PCORI) Project Program Award (PCS-1504-30283), the Gloria M. and Anthony Simboli Distinguished Chair in Asthma Research Award, grant #K23AI125785 from the National Institute of Allergy and Infectious Diseases (NIAID) and grant #AI-835475 from the American Lung Association (ALA)/American Academy of Allergy, Asthma & Immunology (AAAAI).

Dr. Cardet is a co-investigator for the Precision Interventions for Severe and/or Exacerbation-Prone Asthma Network (PrecISE) sponsored by the National Heart, Lung, and Blood Institute (NHLBI). This multisite clinical study, which aims to identify biomarkers to guide development of targeted treatments for severe asthma, is also seeking participants from underrepresented populations.

A USF Health-led team tests 40 million compounds and finds lead candidate that selectively relaxes airway smooth muscle cells with no detectable drug desensitization

TAMPA, Fla. (Dec. 2, 2021) – Beta-agonists (β-agonists) are the only drugs that directly open narrowed airways and make it easier to breathe for millions of people with asthma, a chronic respiratory disease. These inhaled medications activate the β₂-adrenergic receptors (β₂AR ) on airway smooth muscle cells and relax them, dilating airways and increasing air flow.

However, for a significant proportion of asthmatics, the effectiveness of existing β-agonists is insufficient to open tightly constricted airways and the clinical benefits realized appear to wane over time, leaving them constantly struggling with the disease.

“A lack of more effective therapies to treat or prevent shortness of breath is a major issue for patients with severe-to-moderate asthma,” said Stephen Liggett, MD, vice dean for research and a professor of medicine, molecular pharmacology and physiology, and biomedical engineering at the University of South Florida Health (USF Health) Morsani College of Medicine. “As regular use of β-agonists increases, the body becomes less sensitive to these bronchodilators.”

This process, known as tachyphylaxis or drug desensitization, contributes to insufficient asthma control, which leads to increased emergency department visits and hospitalizations — impacting the quality of life and extracting an economic toll in increased medical costs and missed days of work and school. Dr. Liggett’s laboratory works with collaborators across the country to understand the mechanisms of tachyphylaxis, with the aim of improving β-agonists.

Over the last three years, a multi-institutional research team led by USF Health studied 40 million compounds to identify those that activated β₂AR (β-agonists) without causing tachyphylaxis. The investigators found one such agonist, which was structurally distinct from all known traditional β-agonists. Their preclinical research suggests that a different class of β-agonists, known as biased agonists, offers promise for selectively treating asthma and other obstructive lung diseases. Such biased agonists offer a therapeutic option without causing the rapid turndown of these receptors (β₂AR) when the drug is used on an as-needed basis, or the even greater loss of effectiveness observed with chronic use.

The drug discovery study, published online recently in the Proceedings of the National Academy of Sciences of the United States (PNAS), was conducted by scientists with expertise in biochemistry, physiology, and computational biology. The team used molecular modeling driven by high speed, high-capacity supercomputers to define how this atypical agonist, named C1-S, works at the molecular level.

“This is the first β-agonist ever known to relax airway smooth muscle and treat asthma without any detectable tachyphylaxis and represents a significant breakthrough in asthma therapy,” said principal investigator Dr. Liggett, the PNAS paper’s senior author.

USF Health’s Stephen Liggett, MD, led a multi-institutional research team that studied 40 million compounds to identify those that activated β₂AR (beta-agonists) without causing tachyphylaxis (drug desensitization). — Photo by Allison Long, USF Health Communications and Marketing

β2-adrenergic receptors are G protein-coupled receptors (GPCR), present in airway smooth muscle cells to mediate various functions. The existing β-agonists used to treat asthma are all unbiased. That means the drug equally favors activating a G-protein signaling pathway that promotes airway smooth muscle cell relaxation (thus easier breathing) as well as engaging a beta arrestin (β-arrestin) signaling pathway that leads to the unwanted outcome of tachyphylaxis.

“Beta-arrestin is a protein that upon interaction with the G protein-coupled receptor begins to uncouple (inhibit) the receptor from stimulating the clinically important signaling pathway we want to preserve,” Dr. Liggett explained. “With unbiased beta agonists you have these dueling signaling processes essentially competing with each other.”

Research is underway to design biased agonists to help alleviate pain without addiction and to better treat certain cardiovascular conditions with minimal side effects; however, no GPCR-biased agonists are yet being developed for asthma.

The researchers approached this massive study with “no preconceived notions” about what compounds might work best, Dr. Liggett said. Among their key findings:

• Of the 40 million compounds screened, 12 agonists activated the target receptor (β₂AR), stimulating cyclic AMP production that causes airway smooth muscle relaxation. But only one of these 12 (C1-S) appeared to be strongly biased away from the b-arrestin signaling that limits airway smooth muscle response (and thus drug effectiveness) due to receptor desensitization.
• Through a series of biochemical experiments, the researchers verified for the first time that it was possible for an agonist to “split the signal” mediated by a G coupled-protein receptor (β₂AR). This split preferentially activates, or switches on, a signaling pathway beneficial for treating obstructive lung disease rather than a pathway believed to be physiologically harmful, Dr. Liggett said.
• In addition to measuring signaling at the cellular level, the researchers employed the magnetic twisting cytometry, a method pioneered by co-author Steven An, PhD, at Rutgers University that measures changes in human airway smooth muscle cell relaxation and contraction. All the biochemistry results correlated with the physiological response the researchers expected — relaxation of airway smooth muscle without desensitization.
• Computer modeling and docking was performed by investigators at Caltech (William Goddard III, PhD, and now graduate student Alina Tokmakova). These studies helped identify molecular contact points between the receptor and biased agonist C1-S; some of these binding sites were not seen with any other agonist before and thus point to the basis of the properties of this unique drug. The collection of 40 million compounds was assembled and maintained by Marc Giulianotti, PhD, of Florida International University.

As regular use of β-agonists increases, the body becomes less sensitive to these inhaled bronchodilators, a process known as as tachyphylaxis (drug desensitization) that contributes to insufficient asthma control.

The researchers plan to evaluate the safety and efficacy of their lead drug candidate C1-S for potential use in humans, Dr. Liggett said.

“Every day we see breakthrough asthma symptoms in patients using albuterol, a beta-2 receptor agonist that is the cornerstone of treatment. When exacerbated, these symptoms sometimes require hospitalization, use of a ventilator, and occasionally even result in death,” said Kathryn S. Robinett, MD, assistant professor of medicine at the University of Maryland School of Medicine’s Division of Pulmonary and Critical Care Medicine, who was not involved in the research. “A new class of beta-agonists that do not cause tachyphylaxis, like the one characterized in this study, could provide rapid relief and add a powerful tool to our belt in the treatment of asthma.”

The study’s co-lead authors were Donghwa Kim, PhD, of the USF Health Morsani College of Medicine, and Alina Tokmakova, currently a graduate student at University of California San Francisco.

The work was supported by grants from the National Heart, Lung, and Blood Institute, part of the National Institutes of Health.

-USF Health-
USF Health’s mission is to envision and implement the future of health. It is the partnership of the USF Health Morsani College of Medicine, the College of Nursing, the College of Public Health, the Taneja College of Pharmacy, the School of Physical Therapy and Rehabilitation Sciences, the Biomedical Sciences Graduate and Postdoctoral Programs, and USF Health’s multispecialty physicians group. The University of South Florida is a high-impact global research university dedicated to student success. Over the past 10 years, no other public university in the country has risen faster in U.S. News and World Report’s national university rankings than USF. For more information, visit health.usf.edu

Experts in airway bitter taste receptors and medicinal chemistry team up to advance a potential asthma and COPD treatment that works differently than existing bronchodilators

.

TAMPA, Fla (Jan 4, 2021) — Despite the progress made in managing asthma and chronic obstructive pulmonary disease (COPD), poorly controlled symptoms for both respiratory diseases can lead to severe shortness of breath, hospitalizations or even death.

“Only about 50 percent of asthmatics, and an even lower percentage of people with COPD, achieve adequate control of lung inflammation and airway constriction with currently available medications,” said Stephen Liggett, MD, vice dean for research at the University of South Florida Morsani College of Medicine and a USF Health professor of medicine, molecular pharmacology and physiology, and biomedical engineering. “So, we’re clearly missing something from our drug armamentarium to help all these patients.”

Dr. Liggett’s laboratory has discovered several subtypes of bitter taste receptors (TAS2Rs) — G protein-coupled receptors expressed on human smooth airway muscle cells deep inside the lungs. In asthma and COPD, tightening of smooth muscles surrounding bronchial tubes narrows the airway and reduces air flow, and Dr Liggett’s lab found that these taste receptors open the airway when activated. They are now looking for new drugs to treat asthma and other obstructive lung diseases by targeting smooth muscle TAS2Rs to open constricted airways.

A promising bronchodilator agonist rises to the top

In a preclinical study published Nov. 5 in ACS Pharmacology and Translational Science, Dr. Liggett and colleagues identified and characterized 18 new compounds (agonists) that activate bitter taste receptor subtype TAS2R5 to promote relaxation (dilation) of human airway smooth muscle cells. The cross-disciplinary team found 1,10 phenanthroline-5,6-dione (T5-8 for short) to be the most promising of several lead compounds (drug candidates). T5-8 was 1,000 times more potent than some of the other compounds tested, and it demonstrated marked effectiveness in human airway smooth muscle cells grown in the laboratory.

For this drug discovery project, Dr. Liggett’s laboratory collaborated with Jim Leahy, PhD, professor and chair of chemistry at the USF College of Arts and Sciences, and Steven An, PhD, professor of pharmacology at the Rutgers Robert Wood Johnson Medical School.

In an extensive screening conducted previously, another research group identified only one compound that would bind to and specifically activate the TASR5 bitter taste receptor – although apparently with limited effectiveness. Using this particular agonist (called T5-1 in the paper) as a starting point, the team relied on their collective disciplines to devise new activators, aiming for a much better drug profile for administration to humans.

USF Health’s Stephen Liggett, MD

“The two key questions we asked were: ‘Is it possible to find a more potent agonist that activates this receptor?’ and ‘Is it feasible to deliver by inhalation given the potencies that we find?’” said Dr. Liggett, the paper’s senior author. “T5-8 was the bronchodilator agonist that worked best. There were a few others that were very good as well, so we now have multiple potential new drugs to carry out the next steps.”

The researchers developed screening techniques to determine just how potent and effective the 18 compounds were. A biochemical test assessed how well these new agonists activated TAS2R5 in airway smooth muscle cells isolated from non-asthmatic human donor lungs. Then, the researchers validated the effect on airway smooth muscle relaxation using a technique known as magnetic twisting cytometry, pioneered by Dr An.

“Team science” solves a structural problem

“The biggest challenge we faced was not having a 3-D crystal structure of TAS2R5, so we had no idea exactly how agonist T5-1 fit into this mysterious bitter taste receptor,” Dr. Liggett said. “By merging our strength in receptors, pharmacology, physiology, and drug development, our team was able to make the breakthrough.”

T5-8 was superior to all the other bronchodilator agonists screened, exhibiting a maximum relaxation response (50%) substantially greater than that of albuterol (27%). Albuterol belongs to the only class of direct bronchodilators (beta-2 agonists) available to treat wheezing and shortness of breath caused by asthma and COPD. However, this drug or its derivatives, often prescribed as a rescue inhaler, does not work for all patients and overuse has been linked to increased hospitalizations, Dr. Liggett said. “Having two distinct classes of drugs that work in different ways to open the airways would be an important step to help patients optimally control their symptoms.”

The ACS Pharmacology paper highlights the importance of translational research in bridging the gap between laboratory discoveries and new therapies to improve human health, he added. “This study yielded a drug discovery that successfully meets most of the criteria needed to advance the compound toward its first trial as a potential first-in-class bronchodilator targeting airway receptor TAS2R5.”

The study was supported by a grant from the NIH’s National Heart, Lung, and Blood Institute.

Journal cover image by Onur Kilic, Johns Hopkins University, republished by permission of Springer Nature | Nature Biomedical Engineering| July 2019

USF Health’s Stephen Liggett, MD, is a coauthor of the article highlighted on the July 2019 cover of Nature Biomedical Engineering, one of the high-impact Nature journals.

That paper, titled “A microphysiological model of the bronchial airways reveals the interplay of mechanical and biochemical signals in bronchospasm,” was also listed among 25 Most-Viewed Articles published in Nature Biomedical Engineering. The most viewed distinction was based on articles ranked by unique page views* for June 30 through July 29, 2019.

Dr. Liggett is vice dean for research, and professor of internal medicine, molecular pharmacology and physiology, and medical engineering at USF Health Morsani College of Medicine.  He was part of a collaborative team, led by researchers at Johns Hopkins University and Yale, which created a microdevice simulating the behavior of bronchial airways to investigate why it is so difficult to successfully treat some asthma patients.

Nature Biomedical Engineering describes its July cover design, using an image by Johns Hopkins University’s Onur Kilic (lead author), as a device simulating “a microphysiological system that recapitulates the mechanochemical environment of the human bronchial airways.” To read more about the research highlighted and its clinical relevance, click here.

“A cover article in Nature Biomedical Engineering is quite hard to come by.  The acceptance rate (for articles) alone is probably less than 10%,” said Robert Frisina, PhD, chair of the USF College of Engineering’s Department of Medical Engineering, where Dr. Liggett holds a joint faculty appointment.  “Outstanding work by Steve, demonstrating we can do great things in biomedical engineering here at USF.”

*Unique page views count as one the total number of article page views by the same user within a defined session.

Studies led by USF’s Dr. Stephen Liggett shed light on genetic variability of adrenergic receptors and how they might best be used to treat disease

Dr. Stephen Liggett, who leads the research enterprise for the Morasani College of Medicine and for USF Health, also oversees a genomics laboratory working on NIH-funded studies. Behind him is a radioligand binding machine used to determine the number of receptors in each cell.

While significant progress has been made managing asthma over the last two decades, about half of all asthmatics achieve optimal control of this chronic inflammatory disease using currently available medications.  Similarly, only about 50 percent of patients with congestive heart failure, which occurs when the heart is too weak to pump enough blood to meet the body’s needs, have an average life expectancy of more than five years.

More still needs to be  known at the molecular level about these common diseases to identify potential new targets for drug therapies, said Stephen B. Liggett, MD, associate vice president for research at USF Health, vice dean for research at the Morsani College of Medicine, and professor of internal medicine and molecular pharmacology and physiology.

What ties these two diseases together are the receptors on cardiac muscle and on smooth muscle of the airways. Dr. Liggett’s laboratory helps shed light on the genetic variability of adrenergic receptors and on how these receptors can best be used for treatment. The genetic studies have been particularly useful in developing the concept of pharmacogenetics, a tailoring of therapy based on an individual’s genetic makeup, for heart failure and asthma.

“Twenty years ago we had a handful of medicines for high blood pressure, and today we don’t use any of them. Now, we have a whole new group of more effective (antihypertensive) drugs with much fewer side effects,” he said.  “And, I’m sure that one day, we’ll have more tools in our toolbox to better treat heart failure and asthma – drugs that work better for subgroups of people as defined by their genetic makeup and environmental exposures.”

 Dr. Liggett comments on some of his laboratory’s contributions to the field over his career.

The research team led by Dr. Liggett, center, includes Ashley Goss, Hiwot Zewdie, Donghwa Kim, PhD, and Maria Castano. Not pictured: Alexa Woo, PhD.

Mining a “superfamily” of receptors for better drug targets

Dr. Liggett leads a USF team that studies the genetic, molecular biology, structure and function of G-coupled protein receptors, or GPCRs, the largest family of human proteins.  More than 800 GPCRs have been discovered within cell membranes in the human body, Dr. Liggett said, and one or more of these receptors plays a role in virtually everything the body does, including controlling thoughts in the brain, sight and smell, uterine contraction and relaxation, blood pressure, cardiac, lung and kidney function, to name just a few.

Consequently, malfunctions of GPCR signaling pathways are implicated in many chronic diseases including asthma and cardiovascular diseases.  Already this “superfamily” of receptors accounts for nearly half the targets of all prescribed drugs. But, a deeper understanding of the dynamics of the GPCR signaling network and how it maintains a healthy cell or responds to pathogens could lead to the design of drugs that more precisely target diseases with greater effectiveness and fewer side effects.

Dr. Liggett began his work with GPCRs in 1988 as a Howard Hughes Institute postdoctoral research fellow in the Duke University Medical Center laboratory of mentor Robert Lefkowitz, MD. Dr. Lefkowitz was awarded the 2012 Nobel Prize in Chemistry with Brian Kobilka, MD, for groundbreaking discoveries revealing the inner workings of GPCRs.

Building upon his interest and advanced training in pulmonary and critical care medicine, Dr. Liggett began early in his career to concentrate on one of the classes of GPCRs known as adrenergic receptors, which are stimulated by the hormone epinephrine and the neurotransmitter norepinephrine. They are involved in increasing the rate and force of contraction of the heart, as well as constriction and dilation of blood vessels throughout the body and of airways in the lung. For the last 28 years, he has been continuously funded by the National Institutes of Health (NIH) to study the molecular basis of beta-adrenergic receptors in asthma.

Biological scientist Ashley Goss

Dr. Liggett is the principal investigator of a four-year, $1.12-million R01 grant from the NIH’s National Heart, Blood and Lung Institute (NHBLI) that seeks to understand how beta-adrenergic signaling is regulated to influence the development and treatment of asthma. Over his career, he has also been awarded millions of dollars in NIH funding to explore the role of genetic variations of GPCRs in heart failure, including whether those variations may alter how effectively drugs work in individual patients.

Bitter taste receptors in a new place

Dr. Liggett is also currently a project principal investigator for a five-year, $2-million NHBLI P01 grant examining how airway smooth muscle bitter taste receptors might be applied as new treatments for asthma and chronic obstructive pulmonary disease.

Using a genomics-based method that Dr. Liggett pioneered, his team had previously identified bitter taste receptors, initially thought only to exist on the tongue, deep inside the lung at the airway smooth muscle and demonstrated they act to open the airway. “When activated, they appear far superior to the beta-agonists commonly prescribed to patients to open their airways during an asthma attack,” said Dr. Liggett, who published the discovery and the need for alternatives to current bronchodilators in Nature Medicine and other journals.

Overall, discoveries emerging from Dr. Liggett’s research have yielded more than 250 peer-reviewed papers, many highly cited and appearing in top journals such as Nature Medicine, Science, Proceedings of the National Academy of Sciences, and the New England Journal of Medicine. His work has been cited by other papers more than 26,000 times. He also holds 18 patents detailing potential new targets for drug therapy or genetic variations of known drug targets and how they might be used to predict response to medications and customize treatment.

 The serendipity of finding bitter taste receptors on smooth airway muscle in the lungs

Laboratory assistant Hiwot Zewdie

Among some of his laboratory’s major findings:

– While at the University of Maryland, Dr. Liggett’s team worked with colleagues at the University of Wisconsin-Madison to sequence for the first time the entire genomes (more than 100 different strains) of all known rhinoviruses, a frequent cause of respiratory infections including the common cold. The groundbreaking work, published on the cover of Science, provided a powerful framework for large-scale, genome-based epidemiological studies and the design of antiviral agents or vaccines to combat rhinoviruses. “I originally suggested sequencing 10 strains, and then my collaborator asked why not do them all,” he said. “This made the difference between a mediocre proof-of-concept paper and a full article in Science. I learned that it is important to think big if you want to make a real difference”

–  Discovered and characterized genetic variations that may predict which patients with congestive heart failure respond best to a life-saving beta-blocker drug.  These landmark studies occurred over several years and were published in Nature Medicine twice, and the Proceedings of the National Academy of Sciences three times. “This is a good example of the progression of an idea over time, where every year or so an unexpected turn of events occurred, and new insight was gained,” he said.

– While at the University of Cincinnati, Dr. Liggett, working with colleagues at Washington University and Thomas Jefferson University, found that a genetic variation of an enzyme, which inhibits beta-adrenergic receptor signaling, confers “genetic beta-blockade” in cardiac muscle and protects against early death in African Americans with heart failure.  The findings, published in Nature Medicine, provided insight into individual variations in disease outcomes. Another key study from Cincinnati revealed that a certain combination of genetic variants within a single gene conferred low vs. excellent responses to inhaled beta-agonists in treating asthma. These combinations, called haplotypes, had never been identified in GPCRs. The work was published in Proceedings of the National Academy of Sciences.

Dr. Liggett’s groundbreaking research sequencing all known human rhinoviruses, a frequent cause of respiratory infections, was featured on the April 3, 2009 cover of the journal Science.

Advancing outside his field of study

Dr. Liggett joined USF Health in 2012 from the University of Maryland School of Medicine in Baltimore, where he was associate dean for interdisciplinary research and professor of medicine and physiology. He received his MD degree at the University of Miami and completed both a residency in internal medicine and fellowship in pulmonary diseases and critical care medicine at Washington University School of Medicine and Barnes Hospital in St. Louis, MO.

Within two years, he advanced from a postdoctoral research fellowship in Dr. Lefkowitz’s laboratory at Duke to tenured associate professor and director of pulmonary and critical care medicine at the University of Cincinnati College of Medicine.  By the time he left Cincinnati for the University of Maryland in 2005, he held an endowed chair in medicine and directed the university’s Cardiopulmonary Research Center.

Though he had no significant wet-lab experience, Dr. Liggett was fascinated by the emerging science called “molecular biology” and was undeterred from branching into a field of study in which he had no formal training.

He secured a position as assistant professor at Duke following his fellowship there, and figured out how to sequence adrenergic receptor genes from a patient’s blood. While routine now, such genetic testing had not been done previously.  He unexpectedly kept finding multiple variations (called polymorphisms or mutations) in genes coding for the same receptors, so he sought out the advice of some classic geneticists.  At the time, Dr. Liggett said, their traditional thought was modeled after diseases like cystic fibrosis — if a person had the genetic mutation they developed the disease, if the mutation was absent they did not.

“There was no consideration for common genetic variants and how they might affect disease risk, progression, or response to treatment. It simply was not in their thought process,” Dr. Liggett said. He was told “it’s probably nothing and don’t quit your day job.” He did not take their advice.

 Some advice Dr. Liggett would give to emerging young scientists

Assistant professor Donghwa Kim, PhD

Instead, he returned to the laboratory to sequence and clone receptors from many different populations with asthma and heart failure, showing that the receptor genes did indeed differ from one individual to another, generally with several common “versions.” His team also created “humanized” mice expressing the human genes for asthma and heart failure so they could begin to understand the physiology of the receptors. They began to find that some genetic alterations increased receptor function, some decreased the drug’s affinity to bind (responsiveness) to a receptor, and still others altered how the receptor was regulated.  And, through NIH-supported clinical trials, the researchers correlated outcomes observed in patients undergoing drug therapies with the genetic variations uncovered in the laboratory.

“If there’s a lesson to be learned here by young investigators, I’d say it’s that you can collect information from experts in the field, but you need to use your gut to ultimately decide on whether to pursue a line of research or not,” Dr. Liggett said.

Personalized medicine challenge: Common diseases, multiple genetic variations

Realizing personalized medicine’s full potential will require a better understanding of how environmental variables – including diet, exercise, the gastrointestinal microbiome (gut bacteria) and toxin exposure – combine with genetic variations to affect disease and its treatment, he said. “Personalized medicine faces its greatest challenges in the common diseases like asthma, atherosclerotic heart disease and heart failure, because they involve multiple variations in multiple genes that interact with the environment to give you a disease – and also provide a set-up for unique ways to treat the disease.”

Biological scientist Maria Castano

Dr. Liggett was one of the first physicians recruited for what would become the USF Health Heart Institute.  He recalls that he still had the letter of offer in his pocket when he stood before the Hillsborough County Commission in 2012 to help USF Health leadership pitch the need for a cardiovascular institute to include a focus on genomics-based personalized medicine.  The county joined the state in funding the project, and Dr. Liggett was instrumental in the early planning stages of the Heart Institute before the arrival of its founding director Dr. Samuel Wickline.  The institute is now under construction in downtown Tampa as part of the new Morsani College of Medicine facility, a key anchor of Water Street Tampa. Already, 21 of the 31 institute’s biomedical scientists who will investigate the root causes of heart and vascular diseases with the aim of finding new ways to detect, treat and prevent them, have been recruited.

“There’s an excitement here and philosophy of excellence that’s rewarding to see,” Dr. Liggett said. “We have a strategic plan in place, including moving ahead to expand research in cardiovascular disease, infectious disease and the microbiome, and the neurosciences. Our departments are recruiting at a good pace, and the faculty we’re bringing in all have NIH funding and are highly collaborative.”

Dr. Liggett is an elected fellow of the American Association for the Advancement of Science – one of only five Morsani College of Medicine faculty members to receive that prestigious honor.  He is also an elected Fellow of the National Academy of Inventors and the American College of Chest Physicians. Last year, he was one of 30 scientists nationwide selected to join The Research Exemplar Project – recognition of his outstanding reputation as a leader whose high-impact, federally-funded research yields novel and reproducible results.

Over his career, he has served on several NIH study sections and on the editorial board of high-impact journals relevant to fundamental biochemistry as well as heart and lung diseases.  He is currently editor-in-chief of the Journal of Personalized Medicine.

 The potential of new treatments for asthma and heart failure

Dr. Liggett holds 18 patents detailing potential new targets for drug therapy or genetic variations of known drug targets, which might be used to predict response to medications and customize treatment.

Some things you may not know about Dr. Liggett:

• He has asthma, which helps motivate his research toward finding better treatments for this common lung disease affecting one in 12 people in the United States.
• Restores vintage cars, primarily DeLoreans. Although he recently finished bringing a funky lime green 1974 Volkswagen Thing back to life, and over the holidays restored a 1973 VW camper. 

• Lives with wife Julie on the beach in Treasure Island, where they enjoy surfing, paddle boarding, and photography.
• Has three children – Elliott, an engineer at NASA’s Jet Propulsion Laboratory at Cal Tech in Pasadena, CA; Grace, who recently completed her master’s degree in public health at USF; and Mara, an undergraduate student studying social work at Florida Atlantic University, and two step-children — Madison, an undergraduate at the University of Florida, and Tripp, a senior at St. Petersburg Catholic High School. He also has three grandchildren, ages 2 to 9.

Photos by Sandra C. Roa, and audio clips by Eric Younghans, University Communications and Marketing

Understanding the sensory nerves involved in protective behaviors may lead to new therapies for respiratory, cardiovascular diseases

Think about the last time you stubbed a toe.

The sensory nerves activated when your toe slammed against a hard object initiated a defensive reflex leading you to withdraw your toe from the source of intense pain. Tom Taylor-Clark, PhD, associate professor in the Department of Molecular Pharmacology and Physiology, likens the pain-induced response to an early warning system that, if working properly, helps us avoid things that can cause damage.

“If you stub your toe once, sure it hurts so much,” he said, “but if you do it repeatedly, eventually you will break your toe.”

In his laboratory at the USF Health Morsani College of Medicine, Dr. Taylor-Clark studies the role of defensive, or nociceptive, sensory nerves in health and disease. Using a combination of electrophysiology, imaging and molecular biology techniques, he investigates how these peripheral nerves, which stimulate organs and penetrate nearly all the body’s tissues, sense their environment. That includes sensory nerve response to external stimuli, like extreme heat or cold, inhaled pollutants or a source of injury, and internal stimuli, such as inflammation, infection or organ damage.

Thomas Taylor-Clark, PhD, an associate professor in the Department of Molecular Pharmacology and Physiology, studies the role of defensive, sensory nerves in health and disease.

“We are interested in understanding the sensory nerves involved in protective behaviors, or defense, because they are the ones that go wrong in disease and injury,” Dr. Taylor-Clark said.

The protective role of airway sensory nerves in cough

His laboratory focuses primarily on the electrical excitability of sensory nerves of the airways. The researchers study the behavior of sensory nerves connecting the lungs with the brainstem, the primitive part of the brain that controls basic body functions such as breathing, swallowing and heart rate. In particular, Dr. Taylor-Clark works with colleagues to better understand the nerves involved in initiating the chronic cough associated with the asthma, a disease characterized by persistent airway inflammation.

Knowing more about how these airway sensory nerves work, including the interface between the conscious and unconscious in the brainstem networks that control cough, is important in understanding how they are disrupted by inflammatory disease. The information could help guide the design of new treatments for unresolved cough and associated symptoms, a major reason people visit primary care providers, Dr. Taylor-Clark said. In addition, better ways to treat cough are important, because for those with a variety of neuromuscular diseases impaired cough can cause an increase in pulmonary infections from aspiration.

Recently, Dr. Taylor-Clark’s team expanded their research to look into how pre-existing cardiovascular disease alters nerve-generated reflexes from the lungs to affect cardiovascular function.

 Dr. Taylor-Clark comments on one aspect of his laboratory’s sensory nerve research.

Stephen Hadley, a senior biological scientist in Dr. Taylor-Clark’s laboratory.

Three research awards totaling more than $2.85 million support their work. The studies are done using cell cultures as well as with the help of transgenic mice that selectively express red fluorescent protein in defensive neurons.

With a grant from the National Heart, Blood and Lung Institute, Dr. Taylor-Clark has investigated the connection between two well-known research findings to determine the downstream effects of mitochondria, the energy producers of the cell, on airway sensory nerve activation. The first finding, he said, was that airway sensory nerves respond to a type of inflammatory signaling that induces potentially damaging oxidative stress. The second was that mitochondria are located right next to signaling receptors in the sensory nerve cells.

“So, we hypothesized that perhaps mitochondria are not there just to produce energy, but to generate signaling,” Dr. Taylor-Clark said. “And we found that mitochondrial signaling activates the sensory nerves specifically by activating chili and wasabi receptors in airways.”

Hot on the trail of wasabi and chili receptors

These receptors for chili peppers (or capsaicin) and wasabi (allylisothiocyanate), officially known as TRPV1 and TRPA1 respectively, are expressed by every single defensive sensory nerve in your body, including those in your tongue, your skin – and your airways (nasal passages, bronchi, larynx). Together the TRPV1 and TRPA1 compounds contribute to involuntary cough reflex.

The USF work linking mitochondrial signaling and airway sensory nerve receptors, triggered by these TRPV1 and TRPA1 molecules that can generate pain as well as heat sensation, resulted in two major papers in the journal Molecular Pharmacology, one in 2013 and another in 2014. A supplementary biophysiological study defining how the wasabi (TRPA1) receptor works was published earlier this year in the Journal of General Physiology.

Above and below: Microscopic images from a transgenic mouse expressing the red fluorescent protein tdTomato  in defensive sensory nerve only.  This crosssection of the lung showing defensive nerve terminals (red)  innervating regions surrounding the small branches of bronchiles, or air tubes (green), within the lungs.

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.

Pollution-induced exacerbation of underlying cardiovascular disease

Another direction of scientific endeavor for Dr. Taylor-Clark is investigating how pre-existing cardiovascular disease may alter normal reflexes from the lungs to affect autonomic regulatory control of the heart. Seed funding from an earlier Morsani College of Medicine Research Office intramural BOOST grant helped his research group obtain a two-year American Heart Association award for this more recent area of research under the auspices of the USF Health Heart Institute.

In preliminary research presented last year at the Experimental Biology Conference, Dr. Taylor-Clark and colleagues reported that hypertensive rats exposed to wasabi, an irritant mimicking the effects of a pollutant like ozone when inhaled into the lungs, experience a much different cardiac response than healthy rats. The heart rate of healthy rats exposed to wasabi slows significantly as a protective mechanism to help slow the distribution of pollutants throughout the body. But given the same exposure, rats with chronic high blood pressure have periods of rapid heartbeats interspersed with a slow heart rate – which can evoke a potentially dangerous abnormal heart rhythm known as premature ventricular contractions.

“So you have a situation where you’ve gone from a healthy (cardiovascular) reflex to an aberrant reflex that may exacerbate pre-existing cardiovascular disease,” he said.

Working with researchers at the University of Florida, Dr. Taylor-Clark is a co-investigator for a recently awarded a three-year, $1.28M grant from the National Institutes of Health Common Fund’s Stimulating Peripheral Activity to Relieve Conditions (SPARC) funding program. The comprehensive project aims to improve maps of the peripheral nervous system —the electrical wiring that connects the brain and spinal cord with the rest of the body – so that more selective and minimally invasive “electroceutical” treatments might be developed for conditions such as heart disease, asthma and gastrointestinal disorders.

 USF’s involvement in NIH project charting defensive airway nerves.

Dr. Taylor-Clark and Stephen Hadley. Recently, Dr. Taylor-Clark’s laboratory expanded its research to look into how pre-existing cardiovascular disease alters nerve-generated reflexes from the lungs to affect cardiovascular function.

Mapping for the future of neuromodulation therapies

The UF-USF multidisciplinary team is focusing on functional mapping of peripheral and central neural circuits for airway protection and breathing.

Using cutting-edge genetic and neurophysiological approaches, they are characterizing the types of defensive airway nerves that control breathing, coughing and heart rate differently and finding where they connect into the brainstem network.

“We are trying to bridge the gap between what has been done (with nerve trafficking) in the lungs and what has been done in the brainstem, and then link them together,” Dr. Taylor-Clark said. “We have transgenic mice that make red fluorescent protein only in their defensive nerves, so now we can chart where targeted nerves are going with superior image quality.”

The team’s overall goal is to advance understanding of the neural pathways underlying respiratory control, laying the groundwork for future neuromodulation therapies to normalize lung function in people at risk.

“If we want to (preferentially) target these therapies for optimal effectiveness, we need to know where all these nerves go and what they do,” Dr. Taylor-Clark said.

Dr. Taylor Clark-received his PhD degree from University College London in 2004. He completed a postdoctoral fellowship at Johns Hopkins University Division of Allergy and Clinical Immunology and served as a medical faculty member at Hopkins for a year before joining USF’s medical school in 2009 as an assistant professor.

Dr. Taylor-Clark is associate chair for research in the Department of Molecular Pharmacology and Physiology. In 2015, he received the Award for Excellence in Teaching from USF’s Graduate PhD Program in Integrated Biological Sciences.

 How mapping neural circuits for airway protection and breathing may lead to novel therapies.

A combination of electrophysiology, imaging and molecular biology techniques are used to study behavior of sensory nerves connecting the lungs with the brainstem.

Some things you might not know about Dr. Taylor-Clark:

• In the mid-1990s, for two years before entering University College London as an undergraduate, he played bass guitar in a band that recorded and performed “very loud rock and roll” as part of the London music scene. These days, with wife Luciana as the audience, Dr. Taylor-Clark jams at home in his living room with daughter Ella, 9, who plays drums.

• Taylor-Clark’s PhD thesis involved a study of how the human nose congests. He measured the internal dimensions of people’s nasal passages with a sonar device at the end of a stick, recruiting family and friends, among others, as study volunteers. He induced sneezing and other symptoms of hay fever by spraying histamine into their nostrils. The shape of the nose and the interaction between nerves and blood vessels in the nose affected air flow and severity of symptoms, he discovered. “While writing the thesis, I began to realize how little was understood about nerves in the airways.”

.

 Photos by Eric Younghans, USF Health Communications

Tampa, FL (June 8, 2016) — The American Lung Association’s Airways Clinical Research Centers (ACRC) network has expanded the national reach of its clinical trials to enhance the quality of life for patients with asthma and chronic obstructive pulmonary disease (COPD). The University of South Florida (USF) — a continuous member of the Lung Association ACRC since its inception in 1999 — is among 17 centers across the country and one of only two centers in Florida.

The non-profit national network studies patients with airways diseases, specifically asthma and COPD, the latter of which includes emphysema and chronic bronchitis.

Asthma affects a high rate of Florida’s population, 8 percent of adults and 10 percent of children, and nearly 8 percent of Floridians have COPD, said Thomas Casale, MD, who assumes the role of principal investigator for USF’s Lung Association ACRC on July 1.

“Finding how best to treat these patients is a primary goal of the American Lung Association’s ACRC,” said Dr. Casale, professor of medicine and pediatrics in the Division of Allergy and Immunology, Department of Internal Medicine, USF Health Morsani College of Medicine.

                              Dr. Thomas Casale, left, and Dr. Richard Lockey

“Participation in this network gives our patients the opportunity to enroll in clinical studies designed to study these disorders and define optimal care for patients with asthma or COPD.  They can also expect to learn a lot about their disease and how best to manage their symptoms.”

Many studies published by investigators in the highly competitive Airways Clinical Research Centers network have been published in the New England Journal of Medicine or the Journal of the American Medical Association.

Richard Lockey, MD, director of the USF Health Division of Allergy and Immunology, has been USF’s ACRC principal investigator since the group began and will continue to collaborate on studies. Under his leadership, USF has participated in a variety of ACRC network clinical trials in which outcomes are helping shape the nature of care, including the:

• Anxiety and COPD Evaluation (ACE Trial) examining the relationship between anxiety, health status and prognosis to inform appropriate treatment strategies. Open at USF through June 30, 2016.
• Resistant Airway Obstruction in Children (REACH) study, investigating whether or not anti-inflammatory medications normally prescribed for children with asthma can help in the management of children with fixed airflow obstruction. Open at USF through June 30, 2017.
• Long-acting Beta Agonist Step-Down Study (LASST), investigating the best way to reduce treatment in well-controlled asthmatic patients.

• Continuous Positive Airway Pressure (CPAP) on Reducing Airway Reactivity in Asthmatics, a trial evaluating whether CPAP, an effective treatment for sleep apnea, can improve asthma control.

“Breathing is essential to life, and it’s vital for those suffering from lung disease to have access to the best treatment options available, and we get there through research,” said Harold P. Wimmer, National President and CEO of the American Lung Association.

“The Airways Clinical Research Centers Network attracts some of the best investigators nationwide, and by adding significantly to the expertise of the ACRC network, we will advance research to improve the quality of life for those living with both COPD and asthma.”

For more information on the American Lung Association’s ACRC, visit http://www.lung.org/our-initiatives/research/airways-clinical-research-centers/

About USF Health
USF Health’s mission is to envision and implement the future of health. It is the partnership of the USF Health Morsani College of Medicine, the College of Nursing, the College of Public Health, the College of Pharmacy, the School of Physical Therapy and Rehabilitation Sciences, the Biomedical Sciences Graduate and Postdoctoral Programs, and the USF Physicians Group. The University of South Florida is a Top 50 research university in total research expenditures among both public and private institutions nationwide, according to the National Science Foundation. For more information, visit www.health.usf.edu

About the American Lung Association
The American Lung Association is the leading organization working to save lives by improving lung health and preventing lung disease, through research, education and advocacy. The work of the American Lung Association is focused on four strategic imperatives: to defeat lung cancer; to improve the air we breathe; to reduce the burden of lung disease on individuals and their families; and to eliminate tobacco use and tobacco-related diseases. For more information about the American Lung Association, a holder of the Better Business Bureau Wise Giving Guide Seal, or to support the work it does, call 1-800-LUNGUSA (1-800-586- 4872) or visit: Lung.org.

Media contact:
Anne DeLotto Baier, USF Health Communications
abaier@health.usf.edu or (813) 974-3303