Finding and pushing the limits of macrophage efferocytosis in atherosclerosis

PROJECT SUMMARY The search for mechanism-driven therapeutic targets in atherosclerosis remains ongoing and the scientific community needs breakthroughs to identify novel therapeutic strategies to further reduce the residual risk of atherosclerotic cardiovascular disease (ACVD). Preclinical, clinical, and human genomic studies support that enhancing macrophage (Mφ) efferocytosis may represent an attractive therapeutic strategy in ACVD. Current pro-efferocytic therapeutics in clinical studies are mostly based on our understanding of targets regulating the “eating” phase, highlighting major knowledge gaps and opportunities to: (1) identify efferocytosis regulators supported by human genetic evidence; and (2) understand the “digestion” phase and target multiple molecular steps of efferocytosis. The overall vision of my R35 program is to turn fundamental knowledge of Mφ efferocytosis into a portfolio of pro-efferocytic targets, expanding the translational pipeline for atherosclerosis therapies. The unique niche of my program is to apply integrative genomic, functional genomic, and imaging- based screening as unbiased discovery pipelines. My lab has expertise in functional genomic screening to identify candidate causal genes for coronary artery disease (CAD) inspired by human GWASs, followed by deep mechanistic studies using human iPSC-derived Mφs and transgenic mouse models. We have identified ILRUN as a candidate causal gene for CAD that suppresses efferocytosis. Project 1 will determine how the knockout of Ilrun enhances Mφ efferocytosis and mitigates atherosclerosis. We have also successfully completed a genome-wide CRISPR screening to discover new regulators of efferocytosis with a focus on the engulfment phase. Built upon the success of this platform, Project 2 will apply CRISPR screening to identify new regulators for the “digestion” phase and determine the potential to target both engulfment and lysosomal degradation to mitigate atherosclerosis. Our imaging-based efferocytosis assay reveals Mφ heterogeneity with polyploid Mφs showing enhanced capacity of both engulfment and degradation during efferocytosis. Given the presence of polyploid Mφs in advanced atherosclerosis, Project 3 will define their functional contribution in atherosclerosis. The program leverages unbiased discovery pipelines, followed by hypothesis-driven mechanistic and translational studies using primary and iPSC-derived Mφs, transgenic mice, nanoparticle-mediated delivery of siRNA to Mφs, and human carotid plaques. With our established expertise and proven track record in Mφ efferocytosis and functional genomics, my program occupies a distinctive niche to uncover new insights into potential therapeutic opportunities targeting Mφ efferocytosis in atherosclerosis. These discoveries hold promise to mitigate the residual risks associated with ACVD, and more broadly, other diseases associated with defective efferocytosis, such as autoimmune disorders, acute cardiac injury, impaired wound healing, and cancer.