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.

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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

Mark your calendar for USF Health Research Day 2022 — the largest interdisciplinary research gathering of faculty, students and staff across multiple colleges. Celebrating the best in health sciences research, Research Day will return as an in-person event on Friday, Feb. 25, 2022, at the USF Marshall Student Center.

The Roy H. Behnke Keynote Speaker will be Litsa G. Kranias, PhD, Professor and Hanna Chair of Cardiology at the University of Cincinnati College of Medicine. She was the former chair of the Department of Pharmacology and Systems Physiology at Cincinnati, and continues to play a major role in training the next generation of scientists.  Her presentation is titled “Calcium Circuits in Cardiac Function and Survival.”

“Dr, Kranias has numerous key discoveries related to the molecular basis of cardiac contractility and relaxation in normal and failing hearts, and in particular the role of myocyte ca2+ homeostasis,” said Stephen Liggett, MD, associate vice president for research at USF Health, Morsani College of Medicine vice dean for research, and professor of medicine, molecular physiology and pharmacology, and medical engineering. “Her work spans basic, translational, and clinical research and we look forward to an energizing keynote presentation.”

For more information, please visit https://health.usf.edu/research/upcoming-research-days, or email the Research Day team at healthresearchday@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

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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.

The COVID-19 pandemic is having a lasting impact on the way we live, work and interact. Watch Dr. Bryan Bognar, vice dean of the Morsani College of Medicine Department of Medical Education, discuss USF Health’s medical education successes and challenges due to the COVID-19 pandemic.

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The COVID-19 pandemic is having a lasting impact on the way we live, work and interact. Watch Dr. Terri Ashmeade, chief quality officer at USF Health, discuss patient safety in the clinics.

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The COVID-19 pandemic is having a lasting impact on the way we live, work and interact at USF Health. Watch Jacqueleen Reyes Hull, Ed.D, assistant vice president for administration at USF Health, discuss how daily life has changed for faculty and staff.

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USF Health medical student Tampa Hutchens discusses how the COVID-19 pandemic has affected medical education and what students and USF faculty have done to keep their medical training on track.

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USF Health Dean of the Taneja College of Pharmacy Dr. Kevin Sneed discusses the role pharmacists play in responding to the COVID-19 pandemic. Dr. Sneed stresses how pharmacists are helping find promising treatments, connecting with patients virtually to go over their medication regimens and further strengthening the healthcare sector’s approach to fighting the pandemic.

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USF Health Dean of Public Health, Dr. Donna Petersen, discusses the importance of public health especially during pandemics like COVID-19. Dean Petersen stresses the importance of following CDC guidelines — washing hands thoroughly, wearing a mask and maintaining social distance — to avoid contracting and spreading COVID-19. Dr. Petersen leads the COVID-19 Task Force and lays out plans to reopen USF to students, faculty and staff.

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Nurses protect the health and well-being of patients every day and play an integral role in our nation’s health care system. In the latest USF Health Brief, Dr. Usha Menon, interim dean of the USF Health College of Nursing, discusses the challenges and changes nurses and nurse training face during the COVID-19 pandemic.

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Dr. Stephen Liggett, USF Health associate vice president for research, discusses how COVID-19 has changed how research is conducted and the types of conditions researchers work.

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Dr. Deborah DeWaay, USF Health associate dean of undergraduate medical education, discusses the current and long-term changes in medical education due to the COVID-19 pandemic.

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Dr. Mark Moseley, USF Health’s Chief Clinical Officer, discusses how physicians and other health care providers are using telehealth services and technology to remotely care for patients, especially amid the COVID-19 pandemic.

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In the first USF Health Briefs, Dr. Charles Lockwood, Dean of the Morsani College of Medicine, talks about how the COVID-19 pandemic has changed our way of life and access to health care, the lessons the virus is teaching the medical community, and how long it may take before we can safely mingle in large groups again.

Multiple clinical studies related to COVID-19 are published daily, so it is important for us to carefully consider the conclusions of such studies, particularly those with an overreliance on statistical tests that ultimately provide a P value.

For many basic research experiments, as well as clinical trials, we often accept that a P value of < 0.05 means the difference between two groups is “significant.” But P = 0.048 (for example) for a typical t-test really just means there is a 4.8% chance that the outcome you observed between two groups is not actually different; that is, the two means of the two groups are identical. Statistically speaking, this indicates there is a 4.8% chance that the null hypothesis (no difference between groups or no treatment effect on some measured outcome) is true. (Or, that random sampling from otherwise identical populations would lead to a difference smaller than you observed in 95.2% of experiments and larger than you observed in 4.8% of experiments.) So, when P is even marginally greater than 0.05 the tendency is to label the results as “nonsignificant.” A corollary is the unabashed support a reader of a paper may give to an intervention deemed “significant” when the P is minimally lower than 0.05.

In the era of “big data” the simple P value has been improved as the defining statistical test. This has included correction for multiple comparisons (eventually meaning that the raw P value might need to be quite small) and even using P = 0.10 or 0.20 to make some initial lists of genes to consider for further study. We have also seen greater use of the false discovery rate as a way to slim down very large datasets. Nevertheless, an overreliance on the P value (1, 2) may exist for most papers we read.

In the context of an appropriately designed and powered clinical trial, it is important to think about the arbitrary nature of “P < 0.05.” Do we really think that P = 0.049 and P = 0.051 can adequately help us decide if a treatment is effective or not? To my mind, such a heavy reliance on an arbitrary cutoff is inappropriate and can lead to poor decisions during the pandemic. It can even promote the “targeted reading” effect, in which the reader looks at the abstract for a P value. If is not < 0.05, they dismiss a therapy or intervention as insignificant and move on. I suggest that values approaching the prespecified P value should be interpreted, at a minimum, as “worthy of further studies.” And of course, P values minimally below the cutoff should be suspect, with the study needing replication.

There also appears to be publication bias against papers with P values marginally above 0.05 (or whatever value was prespecified), which may leave important papers to publication in lower-tier journals. As reported in a statement from the Statistical Association, a petition signed by 800 statisticians proposes the elimination of inferring statistical significance based on P values (3). The higher P value is frequently interpreted as “proof” that the null hypothesis is true. But it really conveys the current study provides insufficient evidence to infer, from a probabilistic standpoint, that the null hypothesis can be rejected.

The use of an adaptive clinical trial design has helped mitigate some of these concerns (4). These trials incorporate interim data analyses used to modify the ongoing trial, without undercutting its validity. The actions that might occur are typically prespecified, but they need not be when faced with a rapidly unfolding life-threatening public health crisis such as the COVID-19 pandemic. Indeed, most COVID-19 trials that we are conducting with Tampa General Hospital are adaptive trials.

When it comes to scientific literature, then, we have no choice but to read the full paper. This includes looking at how the study was designed, and other outcome indices such as confidence intervals, to understand the results. In this pandemic era in particular, an overreliance on P ≤ 0.05 could lead us away from effective solutions for COVID-19.

Stephen Liggett, MD
Associate Vice President for Research, USF Health
Vice Dean for Research, USF Health Morsani College of Medicine
Professor of Medicine, Molecular Pharmacology and Physiology

References:

1. Singh AK, Kelley K, Agarwal R. Interpreting Results of Clinical Trials: A Conceptual Framework. Clin J Am Soc Nephrol 2008;3:1246-52.
2. Ross Meisner and Bill Woywod. Are you overvaluing your clinical trial p values? Clinical Leader, (Guest column) Feb. 6, 2020.
3. Valentin Amrhein, Sander Greenland, Blake McShane. Scientists rise up against statistical significance, Nature (Comment), March 20, 2019
4. Philip Pallmann, Alun W. Bedding, Babak Choodari-Oskooei, et al. Adaptive designs in clinical trials: why use them, and how to run and report them. BMC Medicine, 28 February 2018.

From designing 3D printed test swabs, to researching antibody responses and engaging in leading clinical trials, USF Health scientists rapidly team up to help fight COVID-19

While the world waits for therapies to reduce death rates and a widely available vaccine to prevent COVID 19, team science at USF Health and other academic medical centers continues to take on an unprecedented sense of urgency.

Globally, scientists across disciplines are publicly sharing their ideas, expertise and data like never before – all singularly focused on finding solutions to a highly contagious and potentially life-threatening new virus known as severe acute respiratory syndrome coronavirus 2, or SARS-CoV-2.

Since the pandemic began, the number of studies posted by researchers worldwide to open-access repositories like bioRxiv and medRxiv has skyrocketed. These preprints – papers written after a study concludes but made available before peer review – let scientists disseminate their findings more quickly and obtain instant feedback on their work. Researchers also continue to identify and share viral genome sequences, protein structures, and COVID-19 related epidemiological and clinical data through online databases.

Meanwhile, thousands of clinical trials have been launched as academic medical centers, hospitals and laboratories join forces with government and industry in the search for optimal diagnostics and therapies. At USF Health, more than 65 COVID-19 related laboratory, clinical and epidemiological projects are underway or in final stages of the approval process. These represent unique research efforts by the faculty of all four USF Health colleges, as well as joint efforts with pharmaceutical firms and biotechnical and software companies. Many of the patient-related studies are conducted by USF Health faculty physicians at Tampa General Hospital.  USF Health is also working with Tampa General to create a biorepository that collects, processes and stores health data and residual specimens from patients who test positive or negative for COVID-19 to use in future biomedical research.

“The need for rapid and accurate basic and clinical results has never been greater. The scientific community has risen to the challenge of a lifetime and continues to push forward,” said Stephen Liggett, MD, associate vice president for USF Health Research and vice dean for research in the Morsani College of Medicine. “Without a doubt we are still in the early stages of understanding this new coronavirus – in knowing who should be tested and how often, and which tests work best; in knowing how to treat patients and how effective vaccines will be in conferring immunity.”

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View the interview with Stephen Liggett, MD, associate vice president for research at USF Health, who discusses how the COVID-19 pandemic has changed research here.

USF faculty and student researchers have been quick to mobilize their talent and resources, Dr. Liggett said. “They want to do whatever they can to find answers — both to help fight this pandemic and to prepare for future outbreaks.”

How are some key scientific areas contributing to the pandemic response?  Below are just a few examples provided by USF Health scientists:

Epidemiology:  Containing the spread of the virus

From the start, epidemiologists have been at the forefront of efforts to understand how fast and why SARS-CoV-2 is spreading. Also known as disease detectives or virus hunters, epidemiologists and the models using data they gather are instrumental in tracking and predicting the patterns of disease transmission in populations, said Thomas Unnasch, PhD, distinguished professor in the USF College of Public Health and codirector of the Center for Global Health Infectious Disease Research. Their work had been critical for both guiding policymakers’ plans to curb the pandemic and helping evaluate whether countermeasures to contain the virus are working.

“We’ve been hunkered down in the midst of a pandemic wildfire and testing only the symptomatic people most likely to be infected” — largely to prevent surges of sick patients from overwhelming the health care system, Dr. Unnasch said. “We’re still missing about 90 percent of the population with COVID-19 infections exhibiting mild or no symptoms.”

USF College of Public Health’s Thomas Unnasch, PhD, oversees the COVID-19 symptom surveillance network for Tampa Bay.

Dr. Unnasch oversees a symptom-based surveillance network launched in mid-April to help identify and map COVID-19 hotspots across the Tampa Bay region. USF College of Public Health researchers worked with the Hillsborough, Pinellas, Pasco and Polk County Health Departments to create the Tampa Bay symptom surveillance survey, adapting existing COVID-19 surveillance technology developed by the Puerto Rico Sciences Trust and deployed in Puerto Rico and, more recently, the Boston area through Harvard University.

The anonymous survey asks Tampa Bay residents questions about potential exposure and symptoms consistent with COVID-19. The information collected, which drills down to the zip code level, is provided to the local health departments and hospital groups.

Surveillance – a tool commonly used by public health agencies to identify and prevent the spread of HIV, tuberculosis, anthrax and other infectious diseases – can help fill in the gaps created by limitations inherent in a complex society, such as a lack of uniform testing, Dr. Unnasch said.

COVID-19 cases in Pinellas and Hillsborough County broken down by zip code, as tracked and entered by the Hillsborough County Health Department on April 16, 2020. Pasco and Polk counties have since been added to the symptom surveillance system.

“So far the only way to prevent the disease is to prevent transmission of the virus. That has meant everyone doing the right thing — staying at home, social distancing face masks, and hygiene,” Dr. Unnasch said.  “As we reopen our communities, surveillance can help us do that safely by detecting clusters of new cases early at a very targeted level, so we can stomp out the embers before they reignite COVID-19 outbreaks.”

Real-time mapping of suspected COVID-19 hotspots can be used to strategically direct Tampa Bay’s public health resources to specific areas where testing, contact tracing and isolation are most likely needed, he said.

“The more data we get and the more accurate the information, the more powerful the tool will be.”

Biostatisticians: Keeping the bias at bay

The data collected by epidemiologists or other health researchers can be fed into mathematical models that predict how fast COVID-19 infections may spread or the number of deaths expected in an overall population. At the community/clinical level, predictive models can help hospitals and medical staff triage patients and allocate limited health care resources (like ICU beds or ventilators) by estimating the risk of people being infected or having a poor disease outcome.

While they can be useful to prepare for worst-case scenarios, predictive models have differed widely in their forecasts – and sometimes they can cause more harm than benefit in guiding policy or clinical decisions, said Ambuj Kumar, MD, MPH, director of the Research Methodology and Biostatistics Core, USF Health Office of Research.

Dr. Kumar, a biostatistician and associate professor of internal medicine, points to a recently published systematic review analyzing studies of prediction models for the diagnosis and prognosis of patients with COVID-19. This review concluded that all 31 clinical models were poor quality, at high risk of bias, and their reported performance was likely overly optimistic.

Ambuj Kumar, MD, MPH, directs USF Health’s Research Methodology and Biostatistics Core.

Methodologist/biostatisticians like Dr. Kumar are trained to recognize the issues and complications arising from the analysis of human health data. They play a key role in any team designing and executing a model, providing the statistical methodology needed to draw meaningful conclusions or make predictions. These data scientists help reduce bias in selecting sample populations, observing or reporting findings, and measurement. They are attuned to factors that can interfere with an accurate estimate of cause-and-effect.

Requiring frequent updates, projections are only as good as the model’s underlying assumptions and the reliability and standardization of the data applied to the model, Dr. Kumar said.

For instance, the commonly cited Institute for Health Metrics and Evaluation model assumes social distancing and other strong voluntary measures to control viral spread will stay in place, but predicting how people will behave as the U.S. reopens in phases is tricky. And, the death data relied upon by many models may be confounded a lack of consistency in the way COVID-19 deaths are reported and counted by hospitals and health departments. (Public health experts have suggested that deaths are undercounted.)

Predictive modeling uses existing data and reasonable assumptions to forecast how an infectious disease spreads in the real world. As more data becomes available, it triggers adjustment of the model, resulting in different outcomes.

Many people understandably want to know now what to expect during this pandemic: How many more cases? How long will it last? When can I safely return to work, or school? Will there be a second wave?

But, many uncertainties about testing, immunity, susceptibility and treatments still influence the variables that make up the algorithms forecasting COVID-19 outcomes, Dr. Kumar said. As the reliability and accuracy of rapidly accumulating data improves, so should the models, he added.

“Predicting the future is particularly challenging when we’re dealing with a virus new to the entire world,” Dr. Kumar said.  “Whether you’re battling COVID-19 or another crisis, you can’t compromise on the systematic, standardized approach needed to create a useful model, or study. If you want accurate results, there’s no substitute for good, rigorous science.”

Virology:  Studying how SARS-CoV-2 works

To develop effective therapies and vaccines to combat COVID-19, scientists need to understand how the virus functions, including its interaction with human immune response. That’s the role of virologists like Michael Teng, PhD, associate professor of internal medicine in the USF Health Morsani College of Medicine.

Dr. Teng has spent many years working with the National Institutes of Health and other groups on research and development of a vaccine for respiratory syncytial virus, or RSV. While RSV was discovered over 60 years ago, researchers continue to work on a vaccine for this common respiratory virus that infects virtually every child by age 2.

Like many other scientists, USF Health virologist Michael Teng, PhD, quickly pivoted from his usual research activities to respond to the new global health threat.

Scientists and companies now testing a myriad of SARS-CoV-2 vaccines in the pipeline have benefited from the extensive RSV research, Dr. Teng said. “They’ve learned a lot from RSV about what works and what pitfalls to avoid in vaccine development.”

Like many other scientists, Dr. Teng quickly pivoted from his usual research activities to respond to the new global health threat. In mid-March his laboratory studied the durability and effectiveness of the 3D-printed nasal swabs successfully created for COVID-19 testing by a team at USF Health Radiology and its innovative 3D Clinical Applications Division, directed by  associate professor Summer Decker, PhD.  Faculty with expertise  in anatomy and infectious diseases as well as radiology contributed to the effort. The ambitious 3D design, modeling and printing project teamed USF Health with Formlabs, a 3D printer manufacturer, and Northwell Health, the largest hospital system in New York, the pandemic’s U.S. epicenter.

An integral part of coronavirus test kits that detect the RNA virus’s genetic code, swabs were in extremely short supply as the pandemic escalated. The slender, flexible device collects a sample from the nasal passages or throat, and that sample goes into a test tube containing transport media for preservation until the specimen is processed by a hospital or commercial laboratory. Using RSV as a proxy for a SARS-CoV-2, synthetic respiratory tract mucous (made by USF Health’s Sophie Darch, PhD), and a World Health Organization recipe for transport media, Dr. Teng demonstrated that the 3D-printed alternative swabs worked as well as conventional commercial swabs to safely collect enough of the sample, without leeching into transport media or interfering with the nucleic acid test’s ability to detect virus particles.

Top:  A USF Health Radiology-led team successfully designed, tested and produced a prototype 3D printed nasopharyngeal swab in record time. As of late May, more than 50,000 of the nasal swabs had been mass produced and were being used worldwide by health care providers to alleviate bottlenecks in COVID-19 testing. Bottom: Jonathan Ford, PhD, a biomedical engineer in USF Health Radiology, holds a cube of the 3D diagnostic nasal swabs.

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The 3D printed swabs, fabricated with FDA-approved, nontoxic materials, also passed performance benchmarks when clinically validated in hospitalized patients undergoing COVID-19 screening at Tampa General Hospital and Northwell Health sites. (A larger-scale multisite clinical trial, led by USF Health Infectious Disease Division Director Kami Kim, MD, is further evaluating the performance of the investigational 3D swabs for diagnostic testing.) Meanwhile, several hundred hospitals and academic medical centers across the country, many state governments, and international agencies and health care facilities are already using the USF-patented swabs to alleviate bottlenecks in COVID-19 testing.

The team worked late nights, taking only about a week from swab prototype design and bench testing to the start of clinical validation. “That’s an incredibly fast turnaround time,” Dr. Teng said.

Dr. Teng is also a coinvestigator for a Morsani College of Medicine-College of Public Health project led by Dr. Kim, which is working to find and map epitopes, the parts of SARS-CoV-2 proteins recognized by the immune system. Antibodies are made by the immune system in response to a threat from a specific virus, bacteria and other harmful pathogen. Some epitopes are associated with protective antibody responses that neutralize (inactivate) a virus when that pathogen is recognized by the immune system again. Others may actually lead to a harmful immune response when a person is exposed to the same virus a second time. The USF Health team wants to identify specific epitopes triggering strong protective antibodies to help researchers design vaccines that mimic a beneficial immune response against COVID-19.

“The data we gather may also be useful in screening (convalescent) plasma for specific antibodies that may best be used to treat critically ill COVID-19 patients,” Dr. Teng said.

Thomas McDonald, MD, USF Health professor of cardiovascular sciences, is investigating whether genetic, physiological or medication-interaction factors may contribute to racial and ethnic disparities in COVID-19 infection rates and cardiovascular complications.

A coronavirus “pseudotype” created by Dr. Teng’s laboratory is being used by the team working on finding neutralizing antibodies and a second USF Health team investigating what factors may affect who suffers worse COVID outcomes.

The second team, led by Thomas McDonald, MD, professor of cardiovascular sciences at the USF Health Heart Institute, wants to know if socioeconomic differences alone account for racial and ethnic disparities in who gets sicker and dies from COVID-19, or if genetic, physiological, or even medication-interaction factors contribute to disproportionate infection rates and cardiovascular complications.

Human pluripotent stem cells grown in Dr. McDonald’s laboratory are prodded to become lung, immune, and heart cells in a petri dish. The stem cells come from blood samples donated by many patient volunteers of different ages, genders and races, as well as various pre-existing cardiovascular conditions. These tissue samples will be infected with the COVID-19 proxy virus engineered by Dr. Teng.

The substitute virus combines the well-studied vesicular stomatitis virus (VSV) with an outer shell containing the spike protein on the surface of SARS-CoV-2 that allows the coronavirus to enter human cells. This non-replicating virus is “a sheep in wolf’s clothing,” invading cells like the COVID-19 virus without harming scientists working with the pathogen, Dr. McDonald said. VSV also expresses the same enzyme, luciferase, that gives fireflies their glow. When hit with a chemical, this “firefly luciferase” lights up the virus so researchers can trace how much invades cells and which cell types are vulnerable.

“With a machine we can image the range of light, which is the level of infection coming out of the cells,” Dr. Teng said.

For the Dr. Kim-led study evaluating the ability of different serum antibodies to block the virus from entering human cells, less light would indicate that the antibodies protected against infection, he added.

Luciferase, the same enzyme that gives fireflies their glow, is helping USF Health researchers track how much proxy COVID-virus invades human cells and which cells are most vulnerable.

Structural biology: A key to drug discovery

Unraveling the structure of viral proteins and identifying the receptors they use to enter cells can help guide discovery and design of potential antiviral treatments.

Yu Chen, PhD, is a USF Health associate professor of molecular medicine with a background in structural biology and biochemistry. Dr. Chen applies his expertise in structure-based drug design using advanced techniques — including X-ray crystallography and molecular docking — to help develop inhibitors (drug compounds) that target bacterial enzymes causing resistance to certain commonly prescribed antibiotics such as penicillin.

Now he’s turned his attention toward looking for new or existing drugs to stop SARS-CoV-2.

Yu Chen, PhD, an associate professor of molecular medicine who has expertise in structure-based drug design, has turned toward looking for new or existing drugs to stop SARS-CoV-2.

One way to do this would be to block the virus’s main protease, known as M^pro, an enzyme that cuts out proteins from a long strand that the virus produces when it invades a cell. Without it, the virus cannot replicate. Dr. Chen works with colleagues at the University of Arizona College of Pharmacy (Jun Wang, PhD) and the USF Department of Chemistry (James Leahy, PhD) on this project.

“M^pro represents a promising target for drug development against COVID-19 because of the enzyme’s essential role in viral replication and the absence of a similar protease in humans,” Dr. Chen said. Since people do not have the enzyme, drugs targeting this protein are less likely to cause side effects, he explained.

This winter, an international team of scientists shared their description of the complex crystal structure of M^pro and in April published their discovery of its inhibitors, a half-dozen leading drug candidates identified by targeting the viral enzyme. Taking advantage of the breakthrough, Dr. Chen and other scientists worldwide hope to add more candidates to the drug discovery pipeline soon.

Together with the scientists from University of Arizona, Dr. Chen has found that several known protease inhibitors, including an FDA-approved hepatitis C (HCV) drug boceprevir and an investigational veterinary antiviral drug GC376, showed potent inhibition of the viral protein, and were more active than the previously identified inhibitors. Dr. Chen and his doctoral student, Michael Sacco, have recently determined the first structure of GC376 bound by M^pro, and characterized the molecular interactions between the compound and the viral enzyme.  Their paper describing these results will soon be published in the prestigious scientific journal Cell Research.

Generated by X-ray crystallograhy, this image depicts the overall structure of the COVID-19 virus’s main protease (Mpro), which plays a key role in viral replication. Dr. Chen and colleagues recently found two new protease inhibitors that offer promise in blocking the drug target. –Photo courtesy of Yu Chen.

Dr. Chen and colleagues are also looking for small molecules that can effectively stop the M^pro enzyme from working or last long enough in the body to kill the COVID-19 virus.

The researchers use the latest computer software to visualize and predict how different drug candidates (M^pro inhibitors) bind with the viral proteins. This 3D structural analysis of “binding hotspots” can help in designing and chemically modifying other types of protease inhibiting-drugs with improved activity against SARS-CoV-2, Dr. Chen said.

The most potent antiviral compounds would be tested in human respiratory cell cultures growing the virus. Only then can a drug candidate move to animal models, and, eventually, human trials.

Genomics: Linking genetic variations to outcomes

Why do some individuals get so ill from the COVID-19 virus, while others barely notice symptoms? Why do certain countries and populations have higher death rates than others? Age, underlying medical conditions, socioeconomic and environmental factors play a role – but genetic variation, both in the virus itself and the humans it invades, are likely part of the equation.

“This virus has swept across the world, and some differences in immune response, virulence and disease outcomes of people infected with SARS-CoV-2 could be due to various strains of the virus yet to be defined,” USF Health’s Dr. Liggett said.

Differences in immune response, virulence and disease outcomes of people infected with SARS-CoV-2 could be due to various strains of the virus not yet defined, Dr.  Liggett says.

Sequencing all genes that make up the COVID-19 virus — not just certain sections of the virus’s genome — will be key to uncovering genetic changes that could make a difference in patient susceptibility and outcomes, Dr. Liggett said. More than a decade ago, a team led by Dr. Liggett sequenced for the first time all known genomes of the human rhinovirus, providing a framework for antiviral treatments or vaccine development for this common respiratory virus implicated in asthma flare-ups.

“All parts of a virus’s genome work together for its existence, reproduction and infectivity,” he said. “So, to sequence only one part would be like looking at just the spark plugs, instead of the whole engine, when your car is not running well.”

The data gathered so far indicates that SARS-CoV-2 mutates slowly in the population. Most people have only 10 or so genetic variations in the 30,0000 nucleotide viral genome compared to the reference standard, Dr. Liggett said. “This may be a good sign that antibodies developed from an infection, a vaccine, or derived from an infusion, will provide long-lived immunity. This lower level of mutations also allows us to track a viral strain, potentially knowing how a community became infected.”

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Noting where genetic variation does not occur is also important, since this may represent a “soft-spot” in the virus’s genome that cannot tolerate change because it is so vital, he added. “That might offer a clue about where to target a vaccine or therapy.”

As for human genetic variations that might influence whether certain individuals or subgroups of patients with COVID-19 fare better or worse, Dr. Liggett says the scientific community understands many human genes responsible for mounting an immune defense against this SARS-CoV-2 virus, and other respiratory viruses.

“With enough samples and epidemiology, we may be able to identify patients at genetic risk for serious, life-threatening outcomes,” he said. “However, it will be extremely challenging to find those needles in this big haystack.”

Clinical Trials: Testing treatments that attack on several fronts

As clinicians cared for more patients, one thing became increasingly clear – COVID-19 is more than a respiratory disease that injures the lungs.

It can strike many cell types and organs throughout the body including the brain, heart, blood vessels and kidneys; destroy taste and smell; cause life-threatening blood clots; and trigger a dangerous inflammatory cytokine storm. People with weakened immune systems are more vulnerable to severe illness – including the elderly and those with heart or lung diseases, diabetes, obesity or other underlying medical conditions. Black and Latino populations are disproportionately more likely to die from the virus. And while children are largely spared, a rare inflammatory pediatric syndrome with cardiac complications has been associated with COVID-19.

USF Health, working with Tampa General Hospital, had been at the forefront of a wide range of COVID-19 clinical trials in the Tampa Bay region.

Physicians and scientists are exploring many possible treatments to increase survival and improve prognoses for critically ill patients. Some target the virus itself or human cellular pathways that the virus exploits to replicate. Others aim to prevent collateral inflammatory damage in the human host. A disease affecting so many parts of the body will need drugs, or combinations of drugs, to attack on several fronts, said USF Health infectious disease physician-scientist Dr. Kim.

In the Tampa Bay region, USF Health, working with Tampa General Hospital, is at the forefront of a wide range of COVID-19 clinical trials. Creating drugs from scratch can take years, so several trials are investigating medications already prescribed for other infectious or inflammatory diseases to determine their effectiveness against SARS-CoV-2. For instance, Dr. Kim is local lead investigator for a multisite randomized controlled trial testing the safety and effectiveness of sarilumab in blocking acute lung damage in hospitalized COVID-19 patients. Sarilumab, approved for treating rheumatoid arthritis, is a monoclonal antibody targeting the proinflammatory cytokine receptor interleukin 6. Another trial will evaluate the ability of nitazoxanide, originally developed as an antiparasitic drug for gastrointestinal infections, to prevent respiratory virus replication in health care workers.

Dr. Kim is also working with Tampa General’s laboratory to analyze and validate the reliability of commercial tests that test patient blood samples for antibodies, proteins that provide evidence of past COVID-19 infection and recovery.

Kami Kim, MD, director of the Division of Infectious Disease and International Medicine at USF Health, leads a study evaluating the accuracy of antibody testing.

The accuracy of the antibody testing – different from the nasopharynx swab or saliva tests used to diagnose a current active infections – is important because it can give health officials a clearer picture of how widely COVID-19 has spread in the community and the extent of asymptomatic cases. Based on past experience with other coronaviruses like SARS and MERS, a positive SARS-CoV-2 antibody test would typically indicate some level of immunity. Researchers like Dr. Kim want to confirm that and hope to define the concentration of antibodies needed to confer immunity as well as how long that immunity lasts.

(In late May, the Centers for Disease Control and Prevention released new guidelines cautioning that some antibody tests have high false positive rates, and more definitive data is needed before they can be used to make decisions about returning to work, school or other public places.)

“We need to know if people who have the antibodies are actually protected against another infection,” Dr. Kim said. “It’s not yet clear… but, preliminary data indicates that a fairly large proportion of those people who recover from COVID-19 infection will have what are the protective (neutralizing) antibodies.”

SARS-CoV-2 shares genetic and some clinical similarities with the first SARS virus (SARS-CoV) — which caused a smaller scale global outbreak and has not re-emerged since the last reported case in 2004. But the new coronavirus is both more highly contagious and more apt to spread asymptomatically.

Based on past experience with other coronaviruses like SARS and MERS, a positive SARS-CoV-2 antibody test would typically indicate some level of immunity. Scientists are working to figure out how much immunity and how long it lasts.

“It’s the thing that has kept all of us in public health and infectious diseases up at night – a completely new pathogen that explodes before we had a real chance to get a handle on what was happening,” Dr. Kim said. “We’re learning more as we go, but teamwork is essential. No one will be able to solve all the pieces of this pandemic puzzle by themselves,” she added.

It will take time for scientists to fully understand the COVID-19 virus and how genetics, the environment, medications, lifestyle and public health measures impact the course of the disease.

“COVID-19 has essentially shut down the entire world,” added Dr. Kim, who as a clinical infectious diseases fellow at the University of California San Francisco in the 1980s witnessed firsthand the devastating consequences of the domestic HIV/AIDS epidemic. “A lesson we need to learn is the importance of maintaining preventive public health infrastructures — not only in our local communities, but globally, so that we can efficiently combat any future pandemics.”

How has the COVID-19 pandemic affected the types of research being conducted at USF Health? The fourth in an eight-part series looking at how COVID-19 is impacting the way we live, work and access health care. Dr. Stephen Liggett, USF Health associate vice president for research, discusses how COVID-19 has changed how the school conducts research and the types of conditions researchers study.  

Responding to the urgent need for solutions to a potentially deadly emerging infectious disease, USF Health has jumpstarted a variety of COVID 19-related research projects.

The work may contribute to worldwide efforts to accelerate the discovery and validation of new technologies to diagnose and prevent the spread of SARS-CoV-2, as well as finding potential new treatments for COVID-19, the respiratory disease caused by the new coronavirus.

The new studies are being conducted by scientists across disciplines including biochemistry, infectious diseases and international medicine, medical engineering, nursing, pharmacy, public health, structural biology and virology. The ambitious research efforts include the joint clinical trials launched last month by USF Health and Tampa General Hospital.

“Many fundamental questions remain about this newest coronavirus, including how it functions, the ability of antibodies to convey immunity, and whether genetic differences in certain populations affect their susceptibility to COVID-19 infection or severity of the illness,” said Stephen Liggett, MD, associate vice president of the USF Health Office of Research and vice dean for research in the Morsani College of Medicine. “Our faculty and student researchers have been quick to mobilize their talent and resources, because they want to do whatever they can to find answers — both to help fight this pandemic and to prepare for future outbreaks.”

Some of the COVID-19 related projects build upon knowledge and insights USF Health scientists have acquired using advanced technologies to study the underlying molecular and cellular biology of other viruses and pathogens, including respiratory syncytial virus and HIV.

Among the more than 60 new research projects underway, or being scaled up, are:

• 3D printed nasal swabs for testing: This multidisciplinary project was recently cited in Nature. At the request of USF Health Senior Vice President Dr. Charles J. Lockwood, USF Health Morsani College of Medicine faculty in partnership with faculty at Northwell Health (New York, NY), developed, bench lab-tested, and clinically validated 3D printable flocked nasopharyngeal (NP) swabs to obtain viral RNA samples for COVID-19 testing. The NP swabs were designed with FDA-cleared software and produced on FDA-cleared 3D printers using FDA-cleared surgical grade material that can withstand high-temperature sterilization. The swabs are comparable to commercially available, conventional NP swabs composed of nylon or polyester to obtain enough viral particles to reliably diagnose COVID-19. The FDA has cleared the use of 3D printed swabs made with medical/dental grade materials. USF Health and Northwell Health hold the provisional patent for this technology but are sharing the print file with institutions that have the FDA-cleared technology and materials to print their own swabs. The 3D formula has been provided to medical centers throughout the U.S. and to other countries.

• Antibody tests and immunity: The reliability of new tests that detect blood markers of SARS-CoV-2 infection (antibodies) varies. This collaborative research with Tampa General Hospital’s laboratory, will compare different combinations of antibody tests and analyze which best determines whether a person infected with the virus develops a protective immune response. Knowing whether, and when, antibodies convey immunity could help hospitals and other health care employers decide whom among their medical staff might safely return to work. It can also help researchers recalculate a more accurate fatality rate in the general population by providing a broader picture of COVID-19 infections (including in those with mild or no symptoms). Principal investigator: Kami Kim, MD

• Susceptibility in different ethnic backgrounds: African Americans and Hispanics have double the infection rates and deaths from COVID-19, and in some disease hotspots they are among those disproportionately affected by pre-existing cardiovascular conditions like hypertension and heart failure. This project seeks to answer key questions about COVID-19 related racial/ethnic disparities, including whether socioeconomic differences alone account for differences in infection rates and cardiovascular complications, or if cellular-level or other physiological factors contribute to worse disease outcomes. Principal investigator: Thomas McDonald, MD, USF Health Heart Institute, MCOM.

• Protective antibodies and vaccines: People previously exposed to SARS CoV-2 make immune responses to viral proteins. This public health-medicine team project aims to find parts of the viral proteins, called epitopes, that are recognized by antibodies. Some epitopes are associated with strong protective antibody responses that neutralize the virus while others are not. This Morsani College of Medicine-College of Public Health study will help identify specific epitopes that lead to strong neutralizing antibodies so that researchers can develop more effective vaccines. The information will also help in screening donor plasma that can be best used for treatment of critically ill COVID-19 patients. Principal investigator: Kami Kim, with co-investigators Michael Teng, PhD; John Adams, PhD; and Thomas Unnasch, PhD.

• Portable biomedical testing system: This project explores whether a mobile phone version of the Enzyme Linked Immunosorbent Assay (ELISA), technology patented by USF, could be used to accurately measure antibodies (proteins) made in response to the COVID-19 virus. Laboratory-based ELISA is the gold standard in biochemical analysis of proteins, but the blood test requires big, expensive machines for its complex steps, including incubation and reading. The lightweight Mobile Enzyme Linked Immunosorbent Assay (MELISA) device may allow patients to cost-effectively obtain point-of-care antibody testing and results at a clinic or even a remote area. Anna Pyayt, PhD, principal investigator, College of Engineering (affiliated with Department of Medical Engineering).

• Targeting viral replication– This study applies advanced techniques, including X-ray crystallography and molecular docking, to identify new or existing drugs that prevent viral replication by inhibiting SARS-CoV-2 main protease, or by blocking entry of the virus into human cells. Principal investigator: Yu Chen, PhD, Department of Molecular Medicine, MCOM.

For a complete list of all USF Health COVID-19 related research studies, click here. The list includes some proposals and some projects internally funded by the newly created University of South Florida COVID-19 Rapid Response Research Grants program.

University of South Florida study suggests a new approach to inhibit the buildup of brain-damaging tau tangles associated with FTLD, Alzheimer’s disease and related dementias

TAMPA, Fla. (Feb. 18, 2020) — The protein β-arrestin2 increases the accumulation of neurotoxic tau tangles, a cause of several forms of dementia, by interfering with removal of excess tau from the brain, a new study by the University of South Florida Health (USF Health) Morsani College of Medicine found.

A beta-arrestin2 oligomer (foreground) shown within a nerve cell (background). Oligomerized beta-arrestin2 plays a central role in impairing tau clearance and the development of tau aggregates (magenta) in frontotemporal lobe degeneration and Alzheimer’s disease. | Image courtesy of artist Cynthia Greco and Eric Lewandowski (beta-arrestin2 protein modeling)

The USF Health researchers discovered that a form of the protein comprised of multiple β-arrestin2 molecules, known as oligomerized β-arrestin2, disrupts the protective clearance process normally ridding cells of malformed proteins like disease-causing tau. Monomeric β-arrestin2, the protein’s single-molecule form, does not impair this cellular toxic waste disposal process known as autophagy.

Their findings were first published Feb. 18 in the Proceedings of the National Academy of Science (PNAS).

The study focused on frontotemporal lobar degeneration (FTLD), also called frontotemporal dementia — second only to Alzheimer’s disease as the leading cause of dementia. This aggressive, typically earlier onset dementia (ages 45-65) is characterized by atrophy of the front or side regions of the brain, or both. Like Alzheimer’s disease, FTLD displays an accumulation of tau, and has no specific treatment or cure.

“Our research could lead to a new strategy to block tau pathology in FTLD, Alzheimer’s disease and other related dementias, which ultimately destroys cognitive abilities such as reasoning, behavior, language, and memory,” said the paper’s lead author JungA (Alexa) Woo, PhD, an assistant professor of molecular pharmacology and physiology and an investigator at the USF Health Byrd Alzheimer’s Center.

“It has always been puzzling why the brain cannot clear accumulating tau” said Stephen B. Liggett, MD, senior author and professor of medicine and medical engineering at the USF Health Morsani College of Medicine. “It appears that an ‘incidental interaction’ between β-arrestin2 and the tau clearance mechanism occurs, leading to these dementias. β-arrestin2 itself is not harmful, but this unanticipated interplay appears to be the basis for this mystery.”

The USF Health research team included, from left: Stephen Liggett, MD, senior author; David Kang, PhD, coauthor; and JungA (Alexa) Woo, PhD, lead author. | Photo by Freddie Coleman

“This study identifies beta-arrestin2 as a key culprit in the progressive accumulation of tau in brains of dementia patients,” said coauthor David Kang, PhD, professor of molecular medicine and director of basic research for the Byrd Alzheimer’s Center. “It also clearly illustrates an innovative proof-of-concept strategy to therapeutically reduce pathological tau by specifically targeting beta-arrestin oligomerization.”

The two primary hallmarks of Alzheimer’s disease are clumps of sticky amyloid-beta (Aβ) protein fragments known as amyloid plaques and neuron-choking tangles of a protein called tau. Abnormal accumulations of both proteins are needed to drive the death of brain cells, or neurons, in Alzheimer’s, although the tau accumulations now appear to correlate better with cognitive dysfunction than Aβ, and drugs targeting Ab have been disappointing as a treatment. Aβ aggregation is absent in the FTLD brain, where the key feature of neurodegeneration appears to be excessive tau accumulation, known as tauopathy. The resulting neurofibrillary tangles — twisted fibers laden with tau — destroy synaptic communication between neurons, eventually killing the brain cells.

“Studying FTLD gave us that window to study a key feature of both types of dementias, without the confusion of any Aβ component,” Dr. Woo said.

Monomeric β-arrestin2 is mostly known for its ability to regulate receptors, molecules on the cell that are responsible for hormone and neurotransmitter signaling. β-arrestin2 can also form multiple interconnecting units, called oligomers. The function of β-arrestin2 oligomers is not well understood.

The monomeric form was the basis for the laboratory’s initial studies examining tau and its relationship with neurotransmission and receptors, “but we soon became transfixed on these oligomers of β-arrestin2,” Dr Woo said.

Neurofibrillary tangles laden with tau (stained red) destroy synaptic communication between neurons, eventually killing the brain cells. This tau pathology is a feature of frontotemporal dementia, Alzheimer’s disease and several other dementias. | Image courtesy of David Kang

Among the researchers’ findings reported in PNAS:

– Both in cells and in mice with elevated tau, β-arrestin2 levels are increased. Furthermore, when β-arrestin 2 is overexpressed, tau levels increase, suggesting a maladaptive feedback cycle that exacerbates disease-causing tau.

–  Genetically reducing β-arrestin2 lessens tauopathy, synaptic dysfunction, and the loss of nerve cells and their connections in the brain. For this experiment researchers crossed a mouse model of early tauopathy with genetically modified mice in which the β–arrestin2 gene was inactivated, or knocked out.

– Oligomerized β-arrestin2 — but not the protein’s monomeric form – increases tau.  The researchers blocked β-arrestin-2 molecules from binding together to create oligeromized forms of the protein. They demonstrated that pathogenic tau significantly decreased when β-arrestin2 oligomers are converted to monomers

– Oligomerized β-arrestin2 increases tau by impeding the ability of cargo protein p62 to help selectively degrade excess tau in the brain. In essence, this reduces the efficiency of the autophagy process needed to clear toxic tau, so tau “clogs up” the neurons.

– Blocking of β-arrestin2 oligomerization suppresses disease-causing tau in a mouse model that develops human tauopathy with signs of dementia.

Above: Control nerve cells (green), in which oligomerized beta-arrestin-2 contributes to the accumulation of disease-causing tau (magenta). Below: When the neurons are transduced with b-arrestin2 oligomerization blocking viruses, tau pathology is dramatically reduced. | Images appearing in PNAS (Fig 6D) courtesy of Alexa Woo

“We also noted that decreasing β-arrestin2 by gene therapy had no apparent side effects, but such a reduction was enough to open the tau clearance mechanism to full throttle, erasing the tau tangles like an eraser,” Dr. Liggett said. “This is something the field has been looking for — an intervention that does no harm and reverses the disease.”

“Based on our findings, the effects of inhibiting β-arrestin2 oligomerization would be expected to not only inhibit the development of new tau tangles, but also to clear existing tau accumulations due to the mechanism of enhancing tau clearance,” the paper’s authors conclude.

The work is consistent with a new treatment strategy that could be preventive for those at risk or with mild cognitive impairment, and also for those with overt dementias caused by tau, by decreasing the existing tau tangles.

The study was supported in part by grants from the National Institutes of Health, National Institute on Aging.

Physician-scientist Dr. Allan Levey of Emory University will share his perspective on “Racing to a Cure for Alzheimer’s Disease”

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USF Health Research Day 2020 – Friday, Feb 21, in the USF Marshall Student Center — is right around the corner.  The annual event showcases the best scientific work of students, residents, and postdoctoral scholars across all four USF Health colleges, as well as biomedical science-related collaborations with other USF colleges and several hospital affiliates.

Roy H. Behnke Keynote speaker Allan Levey, MD, PhD, professor and chair at Emory University’s Department of Neurology, will share his outlook on Racing to a Cure for Alzheimer’s Disease, beginning at 9 a.m.  Dr. Levey, a neurologist and neuroscientist, is internationally recognized for his work in neurodegenerative diseases. He directs Emory’s Goizueta Alzheimer’s Disease Research Center and co-leads a National Institutes of Health-funded, multi-institutional Open Drug Discovery Center for Alzheimer’s Disease dedicated to advancing and diversifying the pipeline for innovative therapeutics.

No cure or treatment to address the root cause of Alzheimer’s disease currently exists.  Research has taken on increased urgency in the wake of recent failures of investigational Alzheimer’s drugs from major pharmaceutical companies to halt or slow brain degeneration.

“At USF Health we have a strategic focus on trying to find the underlying basis and treatments and a cure for Alzheimer’s disease, so it’s very appropriate this year for our speaker to be an expert in Alzheimer’s and related neurodegenerative diseases,” said Stephen Liggett, MD, vice dean for research and professor of internal medicine, molecular pharmacology and physiology, and medical engineering.

“As an MD and PhD, Dr. Levey brings a unique perspective on the translation of laboratory findings into new diagnostic, treatment and preventative approaches for Alzheimer’s disease and its related dementias.”

This year, a record number of poster presentations (over 400) were submitted by trainees from the colleges of Medicine, Nursing, Public Health and Pharmacy on topics ranging from basic and translational science to clinical, epidemiological and outcomes studies.

Nearly all the trainees presenting at Research Day have a faculty mentor who helps guide them through the process of developing a hypothesis, concisely explaining their findings and why they matter, and concluding how their investigation supports or disproves the hypothesis.

“Each year the research is becoming more sophisticated, which is both a reflection of our great faculty, as well as the quality of our students,” Dr. Liggett said.  “The energy you feel when you walk into that big hall is contagious… It makes for a great day.”

For the Research Day 2020 agenda, click here.