Perturbation of Invariant Natural Killer T cells by the Clonal Hematopoiesis-related inflammatory environment

Abstract Invariant Natural Killer T (iNKT) cells are T cells characterized by a semi-invariant TCR and NK markers. They respond to glycolipid antigens presented by the major histocompatibility complex (MHC)-like molecule CD1d. Our single-cell transcriptomic profiling of several tissues identified marrow iNKT as a unique subset, possibly modulating marrow homeostasis. However, little is known about their role in hematological malignancies and how the disease-related environment impacts iNKT cells. For example, clonal hematopoiesis of indeterminate potential (CHIP) corresponds to a condition in which mutated hematopoietic cells have an enhanced fitness and expansion, increasing the risk of leukemia and other diseases. Loss of TET2 in CHIP promotes myeloid skewing and inflammation. TET2 is a methycytosine dioxygenase catalyzing DNA demethylation of genes involved in proliferation, differentiation and oncogenesis. However, the impact that TET2 loss has on iNKT lineage output and function is yet to be defined. In our chimeric mouse model of CHIP, only 15% of TET2 mutants differentiate into iNKT. We also observe a decrease of non-transformed iNKT cells in the marrow of our mice, suggesting environmental inhibition. We expect these bystander iNKT cells to be functionally impaired where inflammation leads to their chromatin rewiring potentially contributing to disease. This is addressed by studying CHIP-exposed iNKT transcriptomes and chromatin accessibility. Understanding the molecular basis of the functional reprogramming by the disease-related inflammation will improve clinical outcomes for marrow transplantation and for the development of cellular therapies using iNKT cells.