CANDIDATE/TRAINING: My goal for this career development award is to obtain the necessary training to become an independent physician-scientist studying novel circuits that control regulatory T cell (Treg) differentiation and functio. I am a transfusion medicine fellow who earned a Ph.D. in Immunology studying the regulation of T cell receptor gene assembly. Subsequently, I began pursuing a specific interest in the differentiation of naive T cells into TH subsets. Building on foundational skills in molecular genetics, I now plan to add expertise and mentored research experience in cellular immunology, chemical biology and animal models of inflammation to further our understanding of Treg development and function in the context of inflammatory disease. My mentor is an immunologist leader in IBD genetics and biology and provides an unparalleled environment uniquely suited to the success of this project and my career. My research advisory committee brings all necessary additional expertise and my oversight committee comprises successful investigators who are excellent mentors. My prior research and clinical training, together with mentored research and coursework during the award period will build fundamental skills and highlight important findings in the regulation of Treg differentiation that I will follow up as an independent, R01-funded investigator with the long-term goal of understanding how T cell biology is modulated in the context of inflammatory disease. PROJECT: Tregs are critical anti-inflammatory cells, impaired development and/or function of which leads to inflammatory disease. Emerging data shows that Tregs typically exhibit organ-specific specializations to facilitate niche-relevant roles, calling nto question whether current approaches to expand Tregs ex vivo can adequately reproduce such functions. I hypothesize that local microenvironments contain the cues necessary to induce specializations required for niche-specific functions. Our pioneering unbiased chemical biology efforts identified novel small molecule enhancers of Treg differentiation, including harmine and 2 scaffolds from the Broad DOS collection. The experimental pipeline described in Specific Aim 1 highlights optimized enhancers based on these scaffolds. Harmine and the optimized DOS enhancers are used to address the core hypothesis in Specific Aim 2, that delivery of small molecule Treg enhancers to mucosal surfaces promotes Treg development and function locally and distally, both at steady state and using in vivo models of inflammation.
In Specific Aim 3, we address novel and testable mechanistic hypotheses raised by pilot studies with harmine, including lineage plasticity, as well as the role of novel candidate genes (DYRK1a and DYRK2) and pathways (Creb and NF-kB1 signaling) in Treg differentiation. These studies have important impact on the conceptual approach to Treg-based therapy and are likely to highlight novel regulators of Treg differentiation, as well as point to multidisciplinary approaches to rapidly generate mechanistic hypotheses, enhancing our basic understanding of Treg biology in the context of inflammatory disease.

Public Health Relevance

Regulatory T cells (Tregs) play a central role in regulating inflammation. Despite significant interest in therapeutically expanding Tregs ex vivo, increasingly widespread evidence of site-specific specialized functions raises concern as to the efficacy of such approaches. This project uses novel chemical biology to test the hypothesis that local induction of Treg differentiation can leverage cues in the microenvironment to promote development of fully functional Tregs, examines effects on distant circuits and tests novel mechanisms implicated by these approaches in Treg development.

National Institute of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Clinical Investigator Award (CIA) (K08)
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Digestive Diseases and Nutrition C Subcommittee (DDK)
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Podskalny, Judith M,
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Massachusetts General Hospital
United States
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Johannessen, Liv; Sundberg, Thomas B; O'Connell, Daniel J et al. (2017) Small-molecule studies identify CDK8 as a regulator of IL-10 in myeloid cells. Nat Chem Biol 13:1102-1108
Khor, Bernard (2017) Regulatory T Cells: Central Concepts from Ontogeny to Therapy. Transfus Med Rev 31:36-44
Sundberg, Thomas B; Liang, Yanke; Wu, Huixian et al. (2016) Development of Chemical Probes for Investigation of Salt-Inducible Kinase Function in Vivo. ACS Chem Biol 11:2105-11
Khor, Bernard; Gagnon, John D; Goel, Gautam et al. (2015) The kinase DYRK1A reciprocally regulates the differentiation of Th17 and regulatory T cells. Elife 4: