Identifying Inflammatory Mediators of Clonal Hematopoiesis

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PROJECT SUMMARY/ABSTRACT Clonal hematopoiesis (CH) is a common phenomenon defined as the presence of somatic mutations in hematopoietic stem and progenitor cells (HSPCs) and their expansion in the absence of overt hematological disease. CH-mutant mature, myeloid cells are believed to generate an inflammatory microenvironment promoting the fitness advantage of mutant HSPCs. These, in turn, would expand at higher rates and differentiate into more elevated numbers of myeloid cells, thereby establishing a positive feedback loop between inflammatory signaling and clonal expansion. Yet, whether CH-mutant HSPCs can also trigger cell-autonomous inflammatory signaling to provide a selective clonal advantage for themselves remains unknown. CH increases the risk of hematological malignancy, cardiovascular disease, and mortality from solid tumors. Due to these adverse outcomes and the high prevalence of CH in the elderly, there is an unmet need to develop novel therapies. Targeting inflammation specifically in mutant HSPCs —to avoid disruption of general immune responses— may be a potentially effective strategy. My predoctoral research (Aim 1) aims to identify inflammatory mediators of CH-mutant HSPCs and evaluate their potential as therapeutic targets to restore oligoclonal hematopoiesis. To find novel, cell-autonomous inflammatory pathways in CH, I have designed an sgRNA library to target inflammation-associated genes. Using this library for high-throughput CRISPR/Cas9 screening, I have identified both general and genotype-specific inflammatory dependencies of CH-mutant murine HSPCs. In this proposal, Specific Aim 1.1 seeks to validate the negative selection hits, demonstrate that, when present, the hit genes confer a selective advantage to CH-mutant HSPCs versus wild-type counterparts, and delineate the specific role of credential top hits in clonal expansion. In Specific Aim 1.2, I will use small molecule inhibitors targeting the candidate genes —both ex vivo and in mice— to identify gene expression and cytokine profile changes spanning the hematopoietic cell subsets. I will then assess differences between genetic and chemical approaches concerning their efficiency in achieving adequate target inhibition. My postdoctoral research (Aim 2) will focus on the role of inflammation at the nexus of aging and CH by uncovering the transcriptional and epigenetic mechanisms by which age-related inflammation promotes CH and potential malignant transformation to leukemia. Overall, these two projects, which will use human samples to validate the mouse findings, will lead to developing new therapies targeting inflammation to halt or revert CH and mitigate its clinical sequelae. I, the applicant, will conduct this proposal in the laboratory of Dr. Ross Levine at Memorial Sloan Kettering Cancer Center (MSK), one of the world's leading institutions in cancer treatment and research. MSK's rich environment and abundant resources in conjunction with the support of the Gerstner Sloan Kettering Graduate School, guarantee the successful completion of the proposed research and career development plans.