Clonal Haematopoiesis-related Mutant ASXL1 Promotes Atherosclerosis in Mice via Dysregulated Innate Immunity

Certain somatic mutations confer a fitness advantage in hematopoietic stem cells, resulting in the clonal expansion of mutant blood cells, known as clonal haematopoiesis (CH). Among the top 3 CH mutations, ASXL1 mutations present the highest risk for developing cardiovascular diseases (CVDs). However, how ASXL1 mutations induce CVDs remains totally elusive. Here we show that haematopoietic cells harbouring C-terminally truncated form of ASXL1 mutant (ASXL1-MT) accelerated development of atherosclerosis in Ldlr–/– mice. Transcriptome analyses of plaque-cells showed inflammatory signatures of monocytes and macrophages expressing ASXL1-MT. Mechanistically, wild-type ASXL1 inhibited innate immune signalling through the inhibition of IRAK1-TAK1 interaction in the cytoplasm, indicating an unexpected non-epigenetic role of ASXL1. In contrast, ASXL1-MT lost this regulatory function, leading to NF-?B activation. Intriguingly, IRAK1/4 inhibition decreased inflammatory monocytes and atherosclerosis driven by ASXL1-MT. The present work connects ASXL1 mutations with inflammation and CVDs, giving a clue to prevent CVDs in ASXL1-CH. Overall design: To investigate how ASXL1-MT KI macrophages exerted their effects on atherosclerotic lesions compared to normal cells , we carried out RNA-sequencing of the CD11b+ F4/80+ cells dissociated from the aortae of Ldlr-/- mice reconstituted with ASXL1-MT KI or control BMCs. Three biological replicates were analyzed for each of 2 groups (two genotypes).