The RNA m6A reader protein YTHDF2 controls iNKT cell development and function 2308066

Abstract Introduction Invariant natural killer T (iNKT) cells are a unique subset of T lymphocytes that recognize glycolipid antigens presented by CD1d. As key liver-resident immune cells, they contribute to the pathogenesis of liver diseases such as autoimmune hepatitis. Understanding mechanisms regulating iNKT cell development and function may uncover therapeutic targets. N6-methyladenosine (m6A), the most abundant eukaryotic RNA modification, controls mRNA stability and translation, primarily via the m6A reader YTHDF2. While YTHDF2 is known to regulate immune cell functions, its role in iNKT cells and liver disease remains unclear. Methods We generated Ythdf2 conditional knockout (cKO) mice and assessed iNKT cell development in thymus, spleen, and liver by flow cytometry. Thymic iNKT cells from Ythdf2 cKO and controls underwent scRNA-seq. α-GalCer- and Con A-induced liver injury models were used to evaluate YTHDF2 function. Liver iNKT cells post-α-GalCer treatment were analyzed by bulk RNA-seq. Results Ythdf2 cKO mice showed markedly reduced iNKT cell numbers in thymus, liver, and spleen, with a significant loss of stage 3 thymic iNKT cells. YTHDF2 was dispensable for differentiation into NKT1, NKT2, and NKT17 subsets. scRNA-seq analysis identified transcription factor Bach2 as a potential YTHDF2 target during iNKT cell development. Loss of YTHDF2 in iNKT cells exacerbated α-GalCer- and Con A-induced acute liver injury. Ythdf2 cKO mice displayed elevated serum TNF-α levels compared to controls; however, TNF-α was mainly secreted by monocyte-derived macrophages rather than iNKT cells. Bulk RNA-seq of liver iNKT cells revealed that Csf1 (macrophage colony-stimulating factor), a key cytokine for macrophage differentiation, survival, migration, and function, is likely regulated by YTHDF2 in iNKT cells. Conclusion YTHDF2 is essential for iNKT cell development and modulates iNKT cell-mediated liver injury. Further studies are needed to define underlying mechanisms. Funding Source NIH Topic Categories Immune Response Regulation: Molecular Mechanisms (IRM)