W184 - Unraveling TIM-3 as a Myeloid Immune Checkpoint in Autoinflammatory Diseases

Michela Comi – Yale School of Medicine; David Hafler – Yale School of Medicine; Greta Leissa – Yale School of Medicine; Tomokazu Sumida – Yale School of Medicine

Abstract Text: In the central nervous system, TIM-3 functions as an immune checkpoint inhibitor modulating pro-inflammatory responses. While TIM-3 has been extensively studied in terminally differentiated IFNγ-secreting CD4+ T helper cells and dysfunctional CD8+ T cytotoxic cells, the immunoregulatory role of TIM-3 in myeloid cell biology remains unexplored. Recent discoveries link germline loss-of-function mutations of TIM-3, specifically Y82C, 197M, and T101I variants, as potentially causal in subcutaneous panniculitis-like T cell lymphoma (SPTCL), with nearly 20% of SPTCL patients also developing systemic lupus erythematosus (SLE). Individuals harboring heterozygous TIM-3 variants exhibited reduced TIM-3 surface expression and higher pro-inflammatory cytokine production by immune cells. In multiple sclerosis (MS) patients, we observed surface TIM-3 downregulation on myeloid cells ex vivo, which was restored after B cell depletion therapy. These findings in human myeloid cells from autoinflammatory diseases strongly suggest TIM-3’s regulatory role in myeloid-mediated inflammation. In vitro gene perturbation by shRNA knockdown and CRISPR-Cas9 knockout on human primary myeloid cells revealed low TIM-3 expression upregulated CD80 and CD86, prompting a pro-inflammatory macrophage phenotype, whereas loss-of-TIM-3 increased susceptibility to inflammasome activation with upregulation of IL-1β secretion and caspase-1 cleavage upon LPS priming and nigericin stimulation. Employing proteome profiler human phospho-kinase array and antibody array assays, downstream intracellular mediator candidates and activated signaling pathways, such as LYN, WNK, HSP60, NFκB, and MAP Kinase demonstrated TIM-3 signaling in human myeloid cells. Targeting downstream candidates via TIM-3 perturbation offers compelling therapeutic potential. TIM-3 surface and signaling blockade together could address immune dysregulation in autoinflammatory diseases like SPTCL and MS.