University Of Pennsylvania

NIH Research Projects · FY 2026 · 2019-06

Abstract: Bone Morphogenetic Protein (BMP) signaling directs the development of multiple organs and tissues, and is the cause of multiple congenital and adult diseases, including cardiovascular defects, kidney disease, pulmonary hypertension, and is important in medical applications in orthopedics, endodontics, and tissue engineering. BMP heterodimers exhibit consistently higher signaling activity to BMP homodimers in a multitude of contexts. Understanding how BMP heterodimers signal more effectively will lead to their more successful use in tissue engineering, bone repair, regeneration, and therapeutics. The zebrafish offers a paradigm of exclusive BMP heterodimer signaling in patterning the dorsoventral embryonic axis as a morphogen, with different levels specifying distinct cell types. This grant revealed specialized functions of the BMP Type I receptors in the heterodimer signaling mechanism, with Acvr1 exclusively providing the kinase activity to transduce the signal, whereas surprisingly the Bmpr1 kinase is dispensable. Intriguingly, Bmp2 homodimers were also found to require the heteromeric Type I receptor complex of Acvr1 and Bmpr1, indicating that the role of the heterodimer is to bring these two Type I receptors together, which elicits higher signaling activity than homomeric Type I signaling complexes. This proposal investigates the nature of the subfunctionalized roles of the Type I receptors in signaling and their trafficking in signal regulation through in vivo live imaging analysis, taking advantage of the large translucent zebrafish embryo. This grant demonstrated that the BMP gradient is interpreted into three cell fate domains by concentration thresholds of signaling and not by signal duration or gradient slope thresholds. Further studies are proposed to understand the outcomes of gradient thresholds and its regulation over time. In most vertebrates, polarity of the egg determines polarity of the embryo and establishes the embryonic dorsal-ventral axis and germ line. Egg polarity originates during oogenesis with the first polarized structure in vertebrate oocytes, the Balbiani body (Bb), a large, membrane-less structure conserved from insects to mammals typically composed of mitochondria and ribonucleoproteins, destined to the vegetal pole of the oocyte and egg. Although fundamental to forming the major axes of most vertebrate embryos, vertebrate oocyte polarity has been little studied. In zebrafish, a key factor Bucky ball (Buc) was discovered that establishes the Bb and oocyte polarity. Buc is a highly disordered protein that can undergo a phase transition to form amyloid-like fibers in vitro. The role of Buc in aggregating the Bb will be studied through unique buc hypomorphic alleles identified in the previous period that reveal its distinct functions in oocyte polarity, axis formation, and germ line development. From proteomics analysis of the Bb in the previous period, new highly disordered proteins with predicted self-aggregation domains will be studied in regulating the Bb. Importantly, inappropriate amyloid protein aggregates in cells are hallmarks of neurodegenerative disease. Thus, these studies are relevant to understanding how these aggregates form and can be dissociated in therapeutics.

NIH Research Projects · FY 2026 · 2019-05

Project Abstract What are the major goals of the program The path to becoming a physician-scientist is increasingly challenging. The usual approach of postponing dedicated research time until after residency prolongs the path to independence and exacerbates the “leaky pipeline” of physician-scientists. Moreover, obtaining K Awards and other funding has grown more competitive. When such obstacles lead to funding breaches, the field risks losing considerable talent. These issues underscore the pressing need to increase the number of Physician Scientists in Psychiatry (PSPs) who obtain independent funding and pursue research careers. This renewal of the successful Educating Physician Scientists in Psychiatry program (EPSP) at the University of Pennsylvania (Penn) addresses these challenges. EPSP’s overarching goal is to intensively recruit, mentor, and train PSPs for rapid, successful career progression beginning early in residency. EPSP achieves this through its core missions: 1) recruit psychiatry residents with basic, translational, or clinical science research experience into psychiatric and neuroscience research careers; 2) intensively mentor PSPs as they embark on integrated research and clinical training; and 3) prepare PSPs for career development awards and, if needed, research fellowships, launching them as independent investigators. Over the past 4 years, EPSP has expanded from 4 to 14 PSPs, providing trainees with a flexible residency structure that maximizes research opportunities and training while maintaining seamless integration with the general psychiatry residency program. Our PSPs establish the foundations of their research programs early in residency so that, upon graduation, they are optimally prepared for transitions to independent research careers. We propose to increase our highly successful recruitment and training for research careers in psychiatry and neuroscience to ~15-20 PSPs over the next 5 years. Further, we propose innovations to strengthen EPSP.

NIH Research Projects · FY 2026 · 2019-05

Nitroarenes are carcinogens found in car exhaust and prominent in diesel exhaust. They pollute the air we breathe, contribute to air pollution which is rising due to extreme weather. Nitroarenes of concern are 1-nitropyrene (1-NP), 1,8-dinitropyrene (1,8-DNP), 3-nitrobenzanthrone (3-NBA) and 6-nitrochyrsene (6-NC). Nitroarenes undergo metabolic activation by nitroreduction via a nitroso- and hydroxylamino- intermediate and amine product and numerous enzymes have been implicated. In the last funding period, we found that prominent nitroreductases involved in the metabolic activation of 1-NP, 1,8-DNP and 3-NBA in human lung cells were the aldo-keto reductases AKR1C1-AKR1C3; furthermore, the genes encoding these enzymes were induced by the NRF2-KEAP1 stress response pathway and genetic knock out of this pathway eliminated nitroarene activation. These findings were among the first to demonstrate that activation of the NRF2-KEAP1 pathway may be harmful in the context of nitroarene exposure and could initiate the carcinogenesis process rather than prevent it. In this renewal we hypothesize that AKR1C enzymes induced by the NRF2-KEAP1 pathway activate nitroarenes to intermediates that adduct proteins and DNA, with a resultant increase in mutation, that ultimately leads to increased carcinogenesis. This hypothesis will be tested by using the following human lung cell lines: A549 (human adenocarcinoma cells with constitutive expression of NRF2 due to hypermethylation and mutation of KEAP1); A549 cells with NFE2L2/NRF2 heterozygous and homozygous knockout generated by CRISPR/Cas9, and HBEC3-KT cells (immortalized human bronchial epithelial cells with inducible NRF2). In Aim 1: We will determine whether human AKRs metabolically activate 6-nitrochrysene (6-NC) in the human lung cells described using both genetic and pharmacological approaches. 6-NC is unique in that it can be activated by monooxygenation and nitroreduction. We will determine whether human AKR1C enzymes reduce the nitro group of 6-NC-1,2-DHD to form 6-aminochrysene-1,2-DHD (6-AC-1,2-DHD) on route to DNA adducts or whether their dihydrodiol dehydrogenase activity will yield a highly reactive 6-nitrochysene-1,2-dione. In Aim 2: We will use a targeted proteomics approach to determine whether nitrosoarenes generated by AKR1C enzymes adduct proteins that control redox-state including KEAP1 itself in HBEC3-KT cells. Detection of sulfinamide and sulfonamide adducts in human lung cells would demonstrate that nitrosoarenes may modify the proteome and affect tumorigenesis. In Aim 3: We will determine whether the adductome resulting from nitroarene exposure in A549 and HBEC3-KT cells is NRF2 dependent. Covalent and oxidatively damaged DNA adducts will be measured by stable-isotope dilution liquid chromatography mass spectrometry. In Aim 4: We will determine for the first time if AKR1C enzymes increase the mutagenicity of nitroarenes on the HPRT gene. We will determine the mutation frequency, potency, pattern, spectrum, and signature and whether the distribution of single base substitutions is similar to COSMIC (catalog of somatic mutations in cancer) observed in human cancers.

NIH Research Projects · FY 2025 · 2019-04

Abstract Genital herpes affects 650 million people globally. Vaccines are urgently needed to prevent infection and treat individuals already infected. During the current funding cycle, we developed a candidate vaccine for preventing genital herpes that uses nucleoside-modified mRNA encapsulated within lipid nanoparticles (LNP) to express herpes simplex virus type 2 (HSV-2) glycoproteins C, D, and E (gC2, gD2, gE2). The vaccine targets an entry molecule, gD2, and two immune evasion molecules, gC2 and gE2. Our vaccine candidate will enter phase 1 human trials in December 2022. Our new goals are to define the immune correlates of protection for the trivalent vaccine using sera we collected from immunized mice and guinea pigs during this grant cycle, and to develop an mRNA-based vaccine as immunotherapy. In Aim 1, we will define the immune correlates of protection. Our hypothesis is that by defining immune correlates, we will better understand the mechanisms of vaccine protection and the immune responses required for success in human trials. We will use high throughput biosensor technology and our extensive panel of gC2, gD2, and gE2 monoclonal antibodies to determine whether the trivalent vaccine produces antibodies to crucial epitopes on gC2, gD2 and gE2. The epitopes of interest include those on gC2 that bind complement component C3b to inhibit complement activation, gE2 that bind the IgG Fc domain to block Fc-mediated activities including complement activation and antibody-dependent cellular cytotoxicity, and gD2 that bind to cell receptors for virus entry and mediate cell-to-cell spread. We will correlate antibody binding to these important epitopes with protection against clinical outcomes including genital lesions and latent infection. The epitope mapping studies will enable us to assess the contribution of each of the glycoprotein immunogens to protection. Aim 2 uses mRNA immunogens to develop a genital herpes therapeutic vaccine. We hypothesize that T cell responses will be particularly important for a successful therapeutic vaccine. In Preliminary studies, we infected guinea pigs intravaginally with HSV-2 and once recovered, we immunized with glycoproteins E and I (gE2/gI2) mRNA-LNP. gE2/gI2 mRNA-LNP reduced the number of days with recurrent genital lesions by 47%, an excellent start towards our primary endpoint of >70% reduction in recurrent genital lesions. To achieve our goal of >70%, we will incorporate other antigens, including additional glycoproteins, immediate early, capsid and tegument immunogens and assess CD4 and CD8 T cell responses in male and female mice. We will advance the best candidates for efficacy studies in guinea pigs. We will focus initially on glycoprotein immunogens because of the remarkable success of a therapeutic vaccine for a closely related virus, varicella zoster virus, that uses glycoprotein E as the antigen. We will include the trivalent gC2/gD2/gE2 vaccine in the therapeutic studies to determine whether one vaccine formulation will be effective for prevention and treatment. If successful, the studies in Aims 1 and 2 will have a positive impact on billions of people by preventing and treating genital herpes.

NIH Research Projects · FY 2026 · 2019-04

SUMMARY Metabolic diseases are rising around the world as changing diets have led to striking increases in obesity rates. Co-morbidities including coronary artery disease and type 2 diabetes drive massive increases in medical costs and are leading causes of death worldwide. Adipose tissue is crucial for safely sequestering lipids to protect other organs as obesity progresses. Unhealthy expansion of adipose tissue due to genetic or environmental factors leads to increased inflammation and drives the progression of metabolic disease. Therefore, understanding the adipose tissue remodeling process in response is crucial for the development of novel therapies to promote metabolic health and reduce chronic inflammation. Mesenchymal progenitor cells (MPCs) are a heterogeneous cell population in adipose tissue that respond to environmental and metabolic cues to regulate various processes including adipogenesis, immune cell activity and fibrosis. We have found that during obesity progression, MPCs undergo a cell fate switch into cells with properties similar to cancer associated fibroblasts (CAFs). This CAF-like population expresses hallmark CAF genes including the transcription factor SOX4 and the pleotropic growth factor Midkine (MDK) that likely regulate adipogenesis and inflammation in adipose tissue. Importantly, both SOX4 and MDK levels correlate with type 2 diabetes status in humans. Our central hypothesis is that the induction inflammatory CAF-like cells in adipose tissue promotes maladaptive inflammation and decreases proper adipose tissue function. Specific Aim 1 investigates the role of the transcription factor SOX4 in driving MPC phenotype switching and adipose tissue remodeling during the development of obesity and insulin resistance. Specific Aim 2 investigates the role of MDK in regulating immune cell activity and adipose tissue function. Overall, these studies will provide insight into how adipose tissue remodels during the development of obesity, leading to an unhealthy metabolic profile and systemic inflammation that can drive the progression of cardiometabolic complications and other pathologies. Understanding these processes may uncover new therapeutic strategies for metabolic disease.

NIH Research Projects · FY 2026 · 2019-04

Program Director/Principal Investigator (Last, First, Middle): Ren, Dejian The major goal of the proposed research is to understand how the ion channel TMEM175 we discovered controls lysosomal function and regulates neurodegenerative diseases. Lysosomes are uniquely important for many functions such as material digestion, recycling, cellular clearance, exocytosis, wound repair, Ca2+ signaling, nutrient sensing. They are also the platform for signaling networks involving the mTOR and AKT kinases and transcription factor TFEB. Lysosomal dysfunctions are implicated in numerous diseases such as lysosomal storage and neural degenerative diseases, and is a hallmark of aging. Despite the importance, their biophysical properties have been poorly defined, and there are several “controversies” even in processes as basic as acidification. We have recently started to fill the knowledge gap by using organelle electrophysiology, channel protein discovery and functional studies in mice and human. In the past period, we have focused on the TMEM175 protein that we discovered to form the K+ channel we first recorded. TMEM175 is a major locus linked to several neurodegenerative diseases including Parkinson's disease (PD) and Lewy body dementia. We found that TMEM175 is important for the acidification of lysosomes. TMEM175 knockout (KO) neurons are prone to stress-induced damages and have accelerated spreading of misfolded α-synuclein. KO mice lose dopaminergic neurons, a hallmark of PD. We also found that a PD-associated variations affect lysosomal ion channel function and modulate Parkinson's disease pathology. Thus, TMEM175 is important for lysosomal function and neuronal fitness, and bidirectionally regulates neurodegenerative diseases. We propose to further reveal how TMEM175 is activated by the kinase protein AKT (Aim 1), how the channel contributes to lysosomal function such as acidification (Aim 2) and how its genetic variations contribute to variations in neuronal function and neurological diseases (Aim 2). As TMEM175 is implicated in PD and several other neurodegenerative diseases, the work will also reveal how genetic variations contribute to functional variations of lysosomes and neuronal fitness, and will provide foundation for the intervention of neural degeneration diseases. Page

NIH Research Projects · FY 2026 · 2019-04

ABSTRACT The core mission of the Cooperative Human Tissue Network (CHTN) has been to serve the public good by fostering biomedical research through collecting and supplying high quality, well- characterized human biospecimens to the scientific community. The proof of our success over the past 36 years is evidenced by the growing bibliography of 5000 publications and 272 published patent applications by the researchers (CHTN investigators) using our service. The CHTN Eastern Division (ED) has built a dynamic infrastructure and brought the CHTN resource to over 1000 researchers who otherwise would have lacked access to the tissue essential to their work. The purpose of this proposal is to report the successes, strengths, and innovations of the ED at the University of Pennsylvania (UPENN) and to present our plan to continue as an adult division of the CHTN in the next 5-year cycle. The Specific Aims of the ED were developed as the operational blueprint for this division to maximize participation in the national CHTN by leveraging local resources. To this end, our Aims, highly successful to date, refresh and reinforce our highly unified approach to procedures, informatics, and operations to ensure procuring and supplying premium quality biospecimens with personalized customer service. The Specific Aims of the ED will remain consistent in the proposed funding cycle because they continue to reflect the innovative approach to collection, quality management, and distribution of biospecimens, the core of the CHTN Mission.

NIH Research Projects · FY 2026 · 2019-04

Project Summary/Abstract Chromosomes are the functional unit of inheritance and must segregate with high fidelity every time a cell divides. For eukaryotes, a common mechanism is employed, where sister chromatids are physically attached to each other and bidirectionally oriented towards poles of the microtubule-based spindle that physically move complete sets of chromosomes to the daughter cells. This bidirectionally-oriented attachment is mediated by a proteinaceous structure called the kinetochore, which forms at the microtubule/chromosome interface during mitosis. The site of kinetochore formation is defined by the centromere. Without functional centromeres, chromosomes are mis-segregated at cell division, leading to a genetic catastrophe—aneuploidy—in the daughter cells. Over the last 15+ years, the centromere has been the major focus of our attention, and altogether we have contributed to elucidating the molecular basis for centromere identity, the epigenetic pathway that propagates centromeric chromatin in perpetuity, the relationship between epigenetic and genetic information in driving centromere evolution in eukaryotes, and key steps in the quality control pathway that ensures proper chromosome segregation at cell division. Over the last ~five years, some of our most important contributions emerging from MIRA-supported projects have come through harnessing this knowledge to develop new and powerful types of human artificial chromosomes, and using standard structural biology approaches as well as solution biophysical approaches to advance our understanding of the proteins that drive chromosome inheritance at cell division. A major focus for our proposed studies will be to use cryo-electron tomography to visualize the centromere in its natural chromosomal context. In the first research area, we propose to visualize the centromere during mitosis. This work will fill a major gap in our understanding of how centromeric chromatin demarcates the site of kinetochore formation. In the second research area, we will advance our current understanding of how centromeric chromatin propagates centromere identity by visualizing this part of the chromosome at key steps through the cell cycle. Altogether, the two research areas will provide answers to vital questions related to how chromosomes are faithfully inherited through cell division.

NIH Research Projects · FY 2025 · 2019-04

Abstract The meniscus plays a vital role in knee function, but injury is common and healing is limited in adults. Development of effective regenerative solutions is challenged by our limited understanding of the cellular mechanisms that regulate meniscus formation, maturation, and maintenance. In the previous funding cycle, we queried the origins of cell fate and biosynthetic function in the developing meniscus. We found that the embryonic-to-early postnatal growth period is the most active time frame of meniscus cell specification, patterning, and regional specialization. We also demonstrated a central role of external mechanical loading and internal cell mechanosensing in regulating meniscus patterning, growth and matrix organization during this early developmental phase. Despite these findings, the timing and mechano-epigenetic mechanisms controlling the early development of meniscus remain unresolved. To address this, in this renewal, we aim to elucidate the roles of cellular force generation and mechanosensing machinery in the formation of the meniscus during early development, as well as its maintenance in the adult. Our central hypothesis is that cell generated tension is essential for meniscus cell inner-to-outer specification and maintenance across the meniscus lifecycle. To test this hypothesis, we will induce timed ablation of cellular force generating machinery, the non-muscle myosin (NMII) genes Myh9 and Myh10 (Myh9/10) in meniscus progenitors at key developmental time points, as well as in the adult meniscus. We will test if this ablation results in aberrant patterning and matrix formation during early development and if it results in loss of cell phenotype and matrix degeneration in adults. Specifically, Aim 1 will determine the role of acto-myosin contractility in the specification and development of the embryonic meniscus. We will test if early ablation of Myh9/10 in the murine embryonic meniscus results in aberrant patterning, and if later ablation leads to insufficient matrix elaboration and impaired maturation. Aim 2 will establish the mechano- epigenetic basis of contractility-mediated regional specification within the embryonic meniscus. Single cell RNA- seq will be applied to evaluate phenotypic heterogeneity at key time points. We will also apply ATAC-seq to determine if ablation of contractility and/or Myh9/10 decreases the accessibility at fibrous matrix genomic loci and increases the accessibility at chondrogenic/remodeling loci in porcine meniscus progenitors cultured in vitro. Aim 3 will determine if loss of cellular force generation and mechanosensing machinery in the adult instigates meniscus degeneration. We will test the effect of Myh9/10 ablation in adult mice by evaluating meniscus cell mechanosensing, fate, matrix production and mechanical properties, and assess how adult porcine and human meniscus cells shift their phenotype upon the loss of tension in vitro. We expect the outcomes to generate novel data defining the mechanobiologic basis of cell fate determination, matrix specialization in the developing meniscus, and postnatal maintenance, providing new insight to direct regenerative strategies in adults.

NIH Research Projects · FY 2026 · 2019-04

Project Summary Sleep and metabolic disorders are often comorbid, but how they interact is poorly understood. The salt inducible kinase SIK3 was identified (first in C. elegans and 8 years later in flies and mice) as a sleep drive regulator. Our findings suggest that SIKs connect sleep and metabolic regulation. In the prior funding cycle, we demonstrated hierarchical somatic/neural interactions regulating both sleep and energy homeostasis. We have shown that the sleep and energy-regulating roles of KIN-29/SIK occur by inhibiting the class 2 histone deacetylase HDA-4 (HDAC4) in 12 pairs of glutamatergic neurons. Illuminating the mechanism by which KIN- 29 signals in glutamatergic neurons during high sleep drive will be the goal of aim 1. We will study the role of CREB and CREB-regulated transcription coactivator 1 (CRTC1) in glutamatergic neurons. In aim 2, we will test the hypothesis that reactive oxygen species promote sleep. In aim 3 we will test the hypothesis that NAD+ precursors promote sleep and are reduced in kin-29 mutants. Finally, in aim 4, we will identify genes whose expression is regulated by the KIN-29--|HDA-4 signaling module. Such genes will be candidates for mediating sleep-promoting signaling by glutamatergic neurons. At the completion of these aims, we will have an improved understanding of the genetic and metabolic regulation of sleep. Data collected in aim 4 will motivate additional genetic hypotheses that will be tested in future research.

NIH Research Projects · FY 2025 · 2019-03

PROJECT SUMMARY For the past 6 years, my independent laboratory has leveraged new approaches in human genomics and pioneered new types of post-genomic functional studies—empowered by genome-editing technologies—to elucidate novel mechanisms that drive cardiovascular diseases. My laboratory has characterized the roles of specific genes involved in lipid metabolism, coronary heart disease, and diabetes, as well yielding insights into how noncoding DNA variation influences the functions of these genes. Going forward, my research will take advantage of recent advances in disease modeling and therapeutic genome editing—advances in which my laboratory played a part—to tackle two exemplary translational challenges in the cardiovascular field: (1) the use of therapeutic genome editing to prevent coronary heart disease, the leading cause of death worldwide; and (2) the use of genome editing to empower high-throughput functional annotation of variants of uncertain significance detected in patients by clinical sequencing.

NIH Research Projects · FY 2025 · 2019-03

Project Abstract Background/Description. Given our mutual interest in direct brain stimulation as an effective treatment for non-adherent eating disorders associated with refractory obesity, our multidisciplinary team at Stanford University has developed a collaboration with NeuroPace, Inc, a company that recently received FDA approval for a responsive neurostimulator. We previously found that electrically stimulating the nucleus accumbens (NAc) of mice attenuates binge-like eating. In addition, increased power in low frequency oscillations appears to temporally correlate with anticipation of food reward and predict the onset of a binge. There is increasing awareness that obese individuals frequently lose control over food, which leads to binge-like eating. We hypothesize that a responsive neurostimulator could be used to identify low frequency oscillations that represent loss of control over eating and deliver responsive stimulation to the NAc to prevent a binge. Objective. To test stimulation parameters and detection algorithms for responsive neurostimulation in humans in an Early Feasibility Study. Methods. All needed regulatory avenues will be pursued, and an Early Feasibility Study will be performed in human subjects with refractory obesity due to loss of control eating. We will primarily assess device function and safety, but will utilize multimodal controlled and ambulatory measures to test the potential of this clinical program for LOC eating in obesity.

NIH Research Projects · FY 2026 · 2019-03

Project Summary Leishmaniasis is a neglected tropical disease that occurs worldwide with ineffective anti-parasite drugs and no vaccine. The disease severity is often due to an exaggerated immune response rather than uncontrolled parasite replication. Our goal is to define the mechanisms promoting immunopathology in the disease in order to develop new host-directed therapies. Our new data shows that the skin microbiome contributes to the development of more severe disease in patients and experimental models. Qualitative and quantitative changes in the bacteria present in leishmanial lesions, and high levels of Staphylococcus aureus, were associated with delayed healing. Similarly, bacterial colonization of mice infected with Leishmania leads to more severe disease without altering the parasite burden. Thus, our results indicate that disease outcome is profoundly affected by the host response and the skin microbiome. We cultured S. aureus isolates from patients and we will test the hypothesis that S. aureus promotes increased disease in a strain-specific manner. Building on preliminary data that strain-level variation in S. aureus underlies differential immunopathology in cutaneous leishmaniasis, we will use a comparative genomics approach combined with host-directed phenotyping to identify S. aureus virulence factors that promote disease. We also found that L. braziliensis patients had variable numbers of regulatory T cells (Tregs) in their lesions and that low numbers of Tregs were associated with delayed healing. We recapitulated those findings in a mouse model, showing that mice with low numbers of Tregs colonized with S. aureus and infected with L. braziliensis develop severe disease with high levels of IFN-γ and S. aureus. We will use our murine models and in vitro skin organoids to define the mechanisms leading to severe immunopathologic responses. The studies defining qualitative differences in S. aureus and the immunopathologic responses associated with S. aureus colonization will be used to identify potential targets for microbial- and host-directed therapies. Pentavalent antimony is the standard of care for CL in Brazil, but it is often ineffective. Our findings strongly support the concomitant use of host-directed therapies to improve outcomes. However, to ensure that such therapies do not lead to an increase in S. aureus burden, we aim to develop therapies that limit host immunopathologic responses while limiting S. aureus burden and virulence. To accomplish this, we will test a combination of host-directed therapies with a consortium of skin commensal bacteria that directly inhibit S. aureus, and in an alternative approach, test a pan-caspase inhibitor that blocks cell death but also controls S. aureus. Together, these studies will uncover how S. aureus worsens disease caused by Leishmania, information vital for developing new leishmaniasis treatments, and will also define how S. aureus, a major cause of skin and soft tissue infections, promotes inflammatory diseases when there is a deficit in regulatory T cells.

NIH Research Projects · FY 2026 · 2019-03

Project Abstract The goal of this proposal is to define novel functions of STING in autoinflammation, cytokine secretion, and immune dysregulation mediated by macrophages, innate lymphoid cells, and radioresistant cells. This work builds on our prior discoveries using our model of STING-associated autoinflammation. The proposed studies utilize several newly generated, already-validated model systems that will allow us to define cell type-specific functions of STING in autoinflammatory disease pathogenesis. STING gain-of-function mutations cause STING-associated vasculopathy with onset in infancy (SAVI), an autoinflammatory disease characterized by T cell cytopenia, interstitial lung disease, Raynaud’s, skin lesions, vasculopathy, and up-regulation of interferon (IFN)-stimulated genes. We previously generated a mouse model of SAVI and discovered that the disease is mediated by type II IFN (IFN-γ) rather than type I or type III IFN. This discovery was unexpected since type I IFN had been predicted to mediate disease. Additionally, we found that innate lymphoid cell functions are altered in STING gain-of-function mice, and that macrophage activation phenotypes and cytokine secretion are perturbed by constitutive STING signaling. We have previously generated and published our floxed-STOP STING mutant mice, which permit cell type-specific expression of STING. However, we have not yet studied cell type-specific functions of the type II IFN receptor and STING in myeloid cells, innate lymphoid cells, and radioresistant cells in our model of STING-induced autoinflammation. Therefore, we will define functions of the type II IFN receptor (Aim 1) and the effects of cell type-specific expression of STING (Aim 2) in SAVI mice. In unbiased, whole-genome CRISPR screening studies, we were led to the discovery that both WT STING and STING gain-of-function can non-transcriptionally regulate pro-inflammatory cytokine secretion by altering the post-Golgi endosomal pathways, and that this occurs without impacting secretion of other proteins. This function of STING requires the protein ArfGAP2. Additionally, we found that ArfGAP2 deletion has no appreciable effect on Golgi structure or on the transit of proteins from the ER to the Golgi when STING is inactive. However, when STING is activated, cytokine trafficking and secretion is greatly diminished in the absence of ArfGAP2, and this effect is non-transcriptional. We generated Arfgap2f/f mice crossed to transgenic Cre animals, and we found that ArfGAP2 is deleted efficiently without impacting survival of target cells. In Aim 3, we will define the immunological and physiological functions of ArfGAP2 in STING-mediated cytokine secretion and autoinflammation (Aim 3).

NIH Research Projects · FY 2026 · 2019-02

Mental health disorders are very common. Last year, 120 million Americans were treated with a psychoactive prescription drug. The use of psychoactive prescription drugs is increasing despite their untoward side effects, some of which are very serious and can result in hospitalization and death. These side effects may be substan- tially amplified by concomitantly used medications, i.e., a harmful drug interaction (DI). This is concerning since the use of multiple drugs is common and increasing among persons with mental health disorders, including in older adults with multiple chronic conditions. In fact, harmful DIs are projected to result in nearly 5 million hospitalizations and 150,000 premature deaths of older adults in the next decade. Unfortunately, nearly all existing evidence on DIs with psychoactive prescription drugs comes from case reports or pharmacokinetic studies examining drug concentration changes rather than clinical endpoints. Thus, DI compendia and clinical decision support software surely fail to warn against unrecognized harmful psychoactive DIs, and falsely warn against safe combinations that prevent appropriate use and contribute to alert fatigue. Of the very few studies of effects of psychoactive DIs on clinical endpoints, most examined injurious falls. None have systematically examined venous thromboembolism (VTE) or serious bleeding, despite well documented associations between VTE and antipsychotics and benzodiazepines, and between serious bleeding and antidepressants. Biologically plausible mechanisms support both VTE and bleeding risks, including antipsychotics’ dopamine antagonism increasing platelet aggregation and antidepressants’ serotonin reuptake inhibition increasing gastric acid secretion, inhibiting platelet activity, and increasing bleeding time. Effects of psychoactive DIs on VTE and bleeding have been hypothesized by many, but remain unstudied. Given high rates of VTE and serious bleeding in older adults, it is imperative to identify drugs that increase patients’ risks of these serious clinical endpoints when co-administered with commonly used psychoactive prescription drugs. We propose a triphasic strategy to: a) generate signals of psychoactive DIs resulting in VTE and/or serious bleeding, via screening of longitudinal healthcare data; b) prioritize signals via multidisciplinary expert panel focus groups; and then c) test, in an independent population, these prioritized signals in a series of rigorous cohort studies built on a causal inference framework designed to emulate target trials. These complementary phases ensure achievement of our broad objective to generate clinically-actionable psychoactive DI evidence to prevent iatrogenic harm in patients. We will apply each of the three phases to each of the following specific aims: 1) generate signals for antipsychotics (by class and for individual agents) resulting in emergency department treatment ± hospitalization for acute VTE (phase a), prioritize DI signals (phase b), then test their associations via emulated target trials in independent data (phase c); 2) perform these steps for benzodiazepines and related drugs and acute VTE; and 3) perform these steps for antidepressants and serious bleeding.

NIH Research Projects · FY 2025 · 2018-12

Project Summary and Abstract Evading immune responses is a hallmark of cancer. Solid tumors create a microenvironment that prevent detection of tumor cells by the immune system and block anti-tumor T cell activity. The therapeutic value of targeting immune evasion pathways is highlighted by the recent clinical successes of alleviating T cell suppression via immune checkpoint blockade in a handful of solid tumors. However, anti-tumor T cells are not generated in most solid tumors, which greatly limits the application of checkpoint blockade. One reason for this is the paucity and dysfunction of antigen-presenting dendritic cells (APCs) in solid tumor microenvironment (TME), but the underlying pathways are poorly understood. Our long-term goal is to discover and delineate pathways that control APC recruitment, differentiation, and function in TME. The overarching goal is to target these pathways to enhance antigen presentation and adaptive immune responses for solid tumor immunotherapy. I have previously developed powerful genetically engineered mouse models of sarcomas, a type of lethal solid tumor, as well as murine models to study antigen-presenting cells. Using these tools, we have recently discovered that retinoic acid (RA) produced by tumor cells act on tumor-infiltrating monocytes to prevent their differential into dendritic cells, instead promoting their differentiation into immunosuppressive macrophages. Furthermore, we have found that the cytokine IL13 promotes RA production in tumor cells. Based on these findings, our central hypothesis is that IL13-induced RA production by tumor cells prevents the generation of monocyte-derived dendritic cells in TME. Our three specific aims will; delineate the mechanism by which RA affects monocyte differentiation and antigen presentation (Aim 1), uncover the source of IL13 in TME and its impact on anti-tumor immune responses (Aim 2), and examine the potential of targeting IL13 and RA signaling for tumor immunotherapy (Aim 3). This work will have significant impact on our understanding of immunomodulation in solid tumors and extend our understanding of how tissue metabolites can control monocyte differentiation. Our findings will also open new avenues for solid tumor immunotherapy based on targeting RA signaling and APCs. The clinical implications are particularly impactful for sarcomas where current treatment options are extremely limited. Our work is innovative because it will open new avenues of research examining the role of retinoid signaling in APC differentiation and tumor immunity. There are many commercially available small molecule inhibitors of RA signaling, but none has been used for therapeutic purposes. Therefore, our work will not only provide a proof of concept for RA blockade in tumor immunotherapy, but is also amenable to rapid human translation.

NIH Research Projects · FY 2025 · 2018-09

Modified Project Summary/Abstract Section The objective of this proposed research is to provide one of the first in-depth, mixed-method analysis of women’s reproductive trajectories in the context of public health crises in a country hard-hit by such crises. These analyses will center on how contextual and individual-level experiences with these public health shocks have influenced women’s reproductive lives both in the short-term and long-term. Understanding women’s reproductive responses to infectious disease crises is key to developing a nuanced understanding of how the impact of these shocks extend beyond mortality to fertility and reproductive wellbeing. With the increased risk of novel infectious disease crises, it is pertinent to consider how the successive nature of such population health shocks have lasting, interconnected implications for the course of women’s reproductive lives. This is especially important in the context of a developing country where vast inequalities in economic security, healthcare access, unintended pregnancy, and morbidity and mortality persist. Currently, little population-based data or research is available on how women’s reproductive trajectories have evolved through different stages of public health crises anywhere. To address this, the proposed study will expand upon an existing three-year longitudinal study (DZC-1), the first-ever panel study on women’s reproductive lives in South America of any kind, for an additional three years to generate one of the longest empirical records of reproductive trajectories of a multi-age cohort (ages 18-34 in 2020) of women (DZC-1-2). This data will be collected twice each year for the next three years and include information on individual and municipality contextual experiences, reproductive intentions, behaviors, and outcomes (with questions on monthly contraceptive use history and relationship history), and a range of potential mediators such as risk perceptions, knowledge about disease transmission, economic vulnerability, healthcare access, and contraceptive self-efficacy. We will link new waves of data with DZC-1 waves to understand if, and how, the experience of living through successive public health crises produces immediate, lagged, and compounded effects. We will also merge DZC 1-2 data with municipality and census tract data to address the implications of contextual conditions on reproductive processes. In addition to creating a 6-year panel, the aims of this study are to examine how varied individual and contextual experiences across space and time have influenced women’s reproductive lives, including their child’s health. We will use panel data methods and difference-in-difference models for our proposed analyses. We will add nuance to these analyses with in-depth interviews to understand how women classified as outliers navigated pregnancy during public health crises.

NIH Research Projects · FY 2025 · 2018-09

Receiving high-quality, accessible, affordable, and well-coordinated health care is fundamental to the health, wellbeing, function, and independence of older adults, but the current U.S. health care system is not organized to uniformly provide this care. Services are often inaccessible or unaffordable, with persistent barriers to access. There is a critical need to grow and support a well-trained scientific workforce to address these shortcomings and disseminate findings effectively. The Center for Improving Care Delivery for the Aging (CICADA), a Resource Center for Minority Aging Research (RCMAR) at the University of Pennsylvania (Penn), is dedicated to these objectives. In its first funding period, CICADA succeeded in developing a robust learning and longitudinal mentoring environment for 15 RCMAR Scientists. Our focus has been on health services research (HSR), an interdisciplinary scientific field that studies the most effective ways to organize, manage, finance, and deliver high-quality care; reduce medical errors; and improve health and wellbeing. HSR spans the investigation and discovery of gaps in evidence-based care delivery, the development of evidence-based interventions to address those gaps, and the study of factors that influence and promote the uptake and sustainment of evidence-based treatments into routine practice via implementation science. Taken together, HSR approaches strive to ensure that all aging adults receive high-quality, equitable, evidence-supported health care and maintain or improve their health and wellbeing as they age. HSR is particularly in need of concerted efforts to increase its workforce. Workforce shortages have scientific and clinical costs, as having too few aging-focused HSR researchers limits our ability to understand and address ways to improve health and health care for older adults. Developing research leaders who can address the challenges facing aging populations is an absolute priority. Based in Penn’s Leonard Davis Institute of Health Economics (LDI), a cooperative venture that spans all 12 schools and centers at Penn, CICADA has offered exceptional training in quantitative and econometric methods and supported the next generation of researchers and mentors. In recognition of ongoing needs in the field, our renewal application seeks to continue and build upon these activities. The overall Specific Aims for CICADA are: (1) To increase and enhance the aging-focused research workforce by mentoring promising scientists for careers dedicated to improving health care delivery for older adults; and (2) To develop and sustain infrastructure to promote science that improves the health, wellbeing, function, and independence of older adults through transformation in health care delivery, with the goal of achieving health for all.

NIH Research Projects · FY 2025 · 2018-09

Abstract The broad, long-term objective of this project concerns the development of novel statistical methods, theory and computational tools for statistical modeling of large-scale multiple high-dimensional genomic data motivated by im- portant biological questions and experiments. New high-throughput technologies and next generation sequencing are generating various types of very high-dimensional genetics, genomic, epigenomics, metabolomics data in order to obtain an integrative understanding of various complex phenotypes. Integrative analysis of genomic data from differ- ent populations and tissues can potentially increase the power of detecting disease associated genetic variants and genes, and provide the possibility of making causal inference in genomic studies, eventually leading to understanding of the disease causal pathways and genomics-based risk prediction. The specific aims of the current project are to develop new statistical models and methods for polygenic risk score (PRS) prediction and for integrative analysis of eQTL and genome wide genetic association (GWAS) data for identification of possible causal genes and pathways of complex diseases. In order to effectively utilize data across different ethnicity groups and different tissues, this project will develop several novel transfer learning methods in order to achieve better estimate of polygenic risk scores and to increase the power of detecting trait associated variants in minority populations. The project will also develop method of meta-learning to predict ethnicity- and tissue-specific gene expressions in order to increase the power of transcriptome-wide association analysis (TWAS). Finally, statistical methods for genome-wide co-localization analysis that can effectively integrate GTEx data with GWAS association summary statistics will be developed in order to identify possible causal disease genes and pathways. These methods hinge on novel integration of methods for multiple re- lated high-dimensional regressions, high-dimensional Gaussian sequence models and subspace estimation. The new methods can be applied to different types of genomic data and will ideally help facilitate the identification of genes as well as the biological pathways underlying various complex human diseases and genomics-based disease risk predic- tion. The work proposed here will contribute statistical methodology and theory for transfer learning and meta-learning in high-dimensional genomic data to study complex phenotypes and to offer insights into each of the biological areas represented by the various data sets, including Alzheimer's disease, cardiometabolic syndrome, and chronic kidney disease. All algorithms, software tools and the resulting polygenic risk score models and tissue-specific gene expres- sion prediction models together with detailed documentation will be made available on the GitHub.

NIH Research Projects · FY 2025 · 2018-09

Project Summary The overarching goal of this chemistry is to develop new avenues in biomimetic transition metal chemistry as a way of modelling metalloenzyme active sites. This work is divided into two sections. The first aims to evaluate the ability of strong, local electrostatic fields in the secondary coordination sphere of a metal center to impact the metal’s electronic structure and reactivity profile. Electrostatic fields play critical roles in enzymology, and recent computational studies have provided the first indication that they operate at metalloenzymes. Lipoxygenases, blue copper proteins, photosystem II, and both heme and non-heme Fe centers have been variously predicted to use local electrostatic fields to facilitate electron transfer, proton transfer, or proton-coupled electron transfer (PCET). Preliminary results from our laboratory have mimicked the ability of enzymes to organize electric fields in a way that is advantageous to the active site’s chemistry. This electrostatic preorganization in our molecular compounds was then shown to regulate both O2 binding to CuI ions and the rates of subsequent intermolecular PCET chemistry. The proposed research will first delineate the extent to which electrostatic fields are able to gate PCET – a process of fundamental importance to metabolism. Unexpected trends in the preliminary data hint at interesting electrostatic field effects that will need to be investigated in a systematic fashion. Next, the use of secondary coordination sphere electrostatic effects will be explored for their ability to stabilize key intermediates that have been proposed to develop during O2 processing at various monocopper sites in biology. Electrostatic effects are expected to provide a useful shift in the energy landscape for stabilizing these species. Lastly, a new approach will be developed for identifying secondary coordination sphere electrostatic effects with X-ray absorption spectroscopy and density functional theory, based on the expectation that oriented electrostatic fields will tune the energies and intensities of XAS acceptor states. The broad scope of this section of the research program is intended to improve our ability to identify, tune, and use electrostatic fields in molecular transition metal systems, as is needed for creating effective biomimetics. In the second section of this research program, we will investigate the ability of constrained geometry cluster compounds to effect biologically relevant N2 fixation chemistry. Many metalloenzymes use multinuclear active sites for small molecule activation, but efforts to mimic their structures and catalytic activities have lagged, with most relying on mononuclear transition metal complexes. Recent developments in the study of the nitrogenase enzymes have identified constrained geometry dinuclear sites as the likely locations for N2 fixation. In preliminary investigations, we have made use of a ligand system that is able to constrain the positions of two metal centers housed within a macrocyclic framework. The diiron version of this complex has been shown to form a number of species that are relevant to mechanisms that have been put forward for N2 fixation at the nitrogenase enzymes. The proposed work will perform a step-by-step investigation into the ability of constrained geometry diiron sites to shuttle nitrogenous substrates along an N2 reduction pathway. Together, these two sections are expected to advance our understanding of ways in which metalloenzymes perform some of the most challenging transformations in biology.

NIH Research Projects · FY 2026 · 2018-08

ABSTRACT The Philadelphia Regional Stroke Trials Network Coordinating Center (PRSTNCC) is a highly effective collaborative stroke research team comprised of adult and pediatric vascular neurologists, neurosurgeons, neuroradiologists, emergency physicians, rehabilitation specialists, and other experts who conduct clinical trials focused on stroke treatment, prevention, and recovery. The PRSTNCC is based at the University of Pennsylvania (Penn), an urban, tertiary care, academic medical center in Philadelphia, PA, which serves as the "Hub" of the consortium, and has joined forces with the Children’s Hospital of Philadelphia (CHOP) and 13 additional member hospitals ("Spokes") located in geographically and ethnically diverse areas in and around Philadelphia. The PRSTNCC thereby unites comprehensive stroke centers, primary stroke centers, and a regional pediatric center, providing access to a broad and diverse population of patients with stroke to a multidisciplinary group of clinicians and researchers. The overarching goal of the PRSTNCC is to reduce the burden of stroke among patients of all ages and backgrounds within this region by conducting interdisciplinary trials of promising clinical interventions for stroke treatment, prevention, and recovery. The multi-disciplinary PRSTNCC leadership team, led by Multiple Principal Investigators (MPIs) Scott Kastner, MD, and Brett Cucchiara, MD, has extensive experience conducting multicenter stroke clinical trials, and has been a major contributor to the current NIH Stroke Net. The PRSTNCC infrastructure supports efficient and effective conduct of stroke trials among the participant hospitals. Research support and expertise are provided by the Hub, particularly in the areas of human subjects protections and other regulatory activities, and education and orientation of clinical and research staff in an effort to streamline trial implementation and expedite patient enrollment. The Hub provides ongoing support for data collection and transfer during trial execution, and provides timely feedback and education about trial results to member specialists and hospitals to encourage translation of research results into clinical practice. In addition, we are training a new generation of stroke researchers and coordinators in the conduct and design of clinical trials by providing them with the knowledge and skills necessary for a successful academic career as independently-funded clinician-scientists.

NIH Research Projects · FY 2025 · 2018-08

Project Summary/Abstract The goal of this project is the optical control of the actin cytoskeleton with photoswitchable molecules. These compounds target monomeric G-actin, polymeric F-actin, the nucleator complex Arp2/3, and the motor protein myosin II. Our probes aimed at F-actin and G-actin are derived from the natural products jasplakinolide, yielding opto-Jasp, cytochalasin D (opto-Chal), and latrunculin B (opto-Lat), respectively. The photoswitchable molecules for Arp2/3 stem from CK-666 (opto-CK) and the photoswitchable myosin 2 inhibitors from blebbistatin and similar compounds (opto-MI). We have already obtained significant preliminary results in a variety of cells (e.g. yeast, HeLa, neurons, oligodendrocytes, microglia). Our proposed program constitutes the continuation of our long-standing and successful program on optically controlling actin and tubulin, as well as associated motor proteins with photoswitchable small molecules. The close collaboration between a chemical biologist and a structural biologist will yield useful probes that are shared with the community and could form the basis of a new form of precision chemotherapeutics.

NIH Research Projects · FY 2025 · 2018-07

PROJECT SUMMARY/ABSTRACT The Neuroscience Graduate Group (NGG) at the University of Pennsylvania is the home of a highly successful Jointly Sponsored NIH Predoctoral Training Program in the Neurosciences, which we refer to as the Neuroscience Training Grant (NTG), that is helping to prepare exceptional predoctoral students in their first two years of graduate school for productive careers in basic neuroscience research and related fields. The NGG is part of Biomedical Graduate Studies (BGS), which provides oversight and resources to ensure effective curricular development, quality control, and uniform admission standards across all participating Graduate Groups, including the NGG. Direct management of the NTG is provided by two highly experienced co-PIs, who have complementary administrative roles and are also part of a five-person Executive Committee that sets and reviews policy and selects trainees. NTG faculty come from 42 Departments in 7 Schools of the University of Pennsylvania plus the affiliated Children's Hospital of Philadelphia. Faculty membership is governed by: 1) expertise in a relevant field of study, 2) significant contribution to training, 3) commitment to the goals of the program, and 4) extramural funding to support trainees. Junior faculty receive extensive guidance on mentoring. NTG students are selected from the highly talented pool of NGG students, based on scientific interests and plans, academic achievement, and diversity. Support for each NTG trainee encompasses their first two years in graduate school, during which time they complete two years of coursework plus at least two lab rotations before settling into a dissertation laboratory. Trainees are active participants in numerous complementary activities that provide training in the responsible conduct of research, scientific rigor and reproducibility, and quantitative methodologies including faculty-led workshops and a newly developed Quantitative Neuroscience Core course. Trainees also participate in seminars, journal clubs, annual retreats, scientific meetings, paper and poster presentations, social events that encourage interactions, and other activities central to successful scientific careers. At the end of their period of support, trainees complete a comprehensive Candidacy Examination that marks the start of their independent dissertation research. Both during and after the period of NTG support, trainees receive extensive mentoring and guidance to help them navigate the challenges of establishing their independence as scientists. The NGG and NTG have a strong record of success in recruiting and retaining diverse and talented trainees whose extensive accomplishments include high academic achievement, substantial involvement in community outreach, publishing and presenting their research to broad audiences, earning fellowships and awards, and going on to successful neuroscience-related careers. We request continued support for 12 trainees per year (typically 6 first-year and 6 second-year students), so we can build on and extend this history of success in helping to train the next generation of leaders in the field of neuroscience.

NIH Research Projects · FY 2025 · 2018-07

PROJECT ABSTRACT Neurofibrillary tau is consistently linked to neurodegeneration and cognitive decline in Alzheimer’s disease (AD) over a range of clinical presentations and anatomical phenotypes, including patients with primary impairment in memory, visuospatial, language, and somatomotor domains. One model of tau progression that has attracted recent attention involves region-to-region transport of pathologic tau along axonal white matter (WM) connections; however, evidence for axonal transport in murine models may not translate to the complex biology of AD in humans. One potential test of the axonal transport hypothesis is whether changes in WM connections predict disease progression between tau-positive and tau-negative regions. If axonal transport is a common mechanism of tau spread, it should leave signature WM changes consistent with a patient’s anatomical and clinical phenotype. However, WM changes are underinvestigated in non-amnestic mild cognitive impairment (MCI) and AD and rarely studied in the context of longitudinal tau changes. Moreover, imaging markers of WM change may reflect features of the AD pathologic process or co-occurring cerebrovascular disease. We propose a multimodal clinical, imaging, and pathologic investigation to test the hypothesis that WM changes predict region-to-region tau spread independent of CVD. Aim 1 will combine longitudinal positron emission tomography (PET) imaging of tau progression with 3-Tesla MR imaging of WM changes using diffusion MRI to assess evidence that WM changes mediate tau spread in a syndrome-specific manner. The axonal transport model predicts that longitudinal changes in diffusion MRI will mediate region-to- region tau PET progression in syndrome-specific brain networks. Aim 2 will use high-resolution 7-Tesla MRI of CVD-related brain changes, including WM hyperintensities and microbleeds, to quantify vascular disease burden across amnestic and non-amnestic AD and to assess CVD co-pathology as a potential confound that would explain WM changes in AD. Based on preliminary data, we hypothesize that all clinical variants of AD will exhibit age-related CVD including WM hyperintensities and microbleeds but will not fully explain tau-related WM changes. Finally, Aim 3 will provide postmortem validation of imaging findings and advance digital pathologic methods to quantify AD- and CVD-related pathology in amnestic and non-amnestic AD. In this aim, the axonal transport model predicts that longitudinal change in grey matter tau will be mediated by tau deposition and degeneration in connecting WM tracts, but not by CVD pathologic burden. By comparing heterogeneous phenotypes and cognitive networks, we seek to demonstrate that WM-mediated tau spread is a generalizable mechanism of disease progression across cognitive subtypes of MCI/AD and is independent of CVD-related changes. This research will contribute to multiple milestones in AD and related dementias (ADRD) by investigating relationships between tau, CVD, and WM change (Milestones 2.L and 2.S); and developing non-invasive markers for longitudinal tracking of CVD-related brain changes (Milestone 9.R).

NIH Research Projects · FY 2025 · 2018-07

SUMMARY Type 2 Diabetes and its precursor insulin resistance (IR) continue to rise and drive cardiovascular complications worldwide. The mechanisms underlying IR remain incompletely understood. Epidemiological studies have consistently revealed a signature of elevated plasma branched chain amino acids (BCAAs) in patients with diabetes or IR, as well as subjects who will go on to develop IR. Mouse studies in laboratories worldwide have shown that systemic suppression of BCAA catabolism worsens IR, while systemic activation of BCAA catabolism (most often with BT2, a specific inhibitor of BCKDK, which in turn inhibits BCKDH, the rate-limiting step of BCAA catabolism) improves IR. There is thus strong interest in targeting this pathway, and multiple pharmaceutical companies are developing novel BT2-based molecule series. Despite these efforts, how systemic activation of BCAA catabolism improves IR remains surprisingly unknown. In our search for potential mechanisms, we discovered that BT2 promotes vasodilation and lowers blood pressure, and that it does so independently of nitric oxide (NO) production by endothelial cells, suggesting that BT2 acts on smooth muscle cells (SMCs) instead. Substantial literature indicates that insulin-stimulated vasodilation contributes to glucose uptake, although how insulin promotes vasodilation remains incompletely understood. These observations and additional preliminary data have led us to the hypothesis that insulin promotes BCAA catabolism in SMCs, in turn promoting vasodilation and glucose tolerance, thereby explaining the metabolic benefits of systemic activation of BCAA catabolism. We will test this hypothesis with novel genetic murine models; with state-of-the-art vascular physiology assays; with hyperinsulinemic euglycemic clamps; and with human studies to test the impact of this pathway on human vascular tone and reactivity. These highly focused studies will elucidate the role of BCAA catabolism in regulating vascular reactivity and glucose tolerance, including human studies.