Artery tertiary lymphoid organs encode a pathogenic high-affinity autoantibody-autoantigen pair in atherosclerosis

Artery tertiary lymphoid organs (ATLOs) emerge in atherosclerosis, which is a chronic inflammatory artery disease with an autoimmune component. However, whether disease-relevant autoimmune B cells emerge in ATLOs remains unknown. In this study, we isolate germinal center (GC) B cells from ATLOs and lymph nodes from healthy and atherosclerosis-burdened mice, expression clone 60 autoantibodies and screen them for arterial wall reactivity. ATLO GC B cell-derived autoantibodies skew to atherosclerosis-relevant autoantigens versus their counterparts in lymph nodes of both genotypes. One ATLO GC B cell-derived autoantibody (termed A6) binds to histone 2B (H2B) with high affinity. Both vaccination with H2B and adoptive transfer of A6 accelerate atherosclerosis, revealing a pathogenic autoantibody-autoantigen pair. Mechanistically, ATLOs specifically show both distorted B cell activation and immune tolerance checkpoint-regulating gene expression profiles. In a human cohort, circulating anti-H2B antibody titers positively correlate with aortic calcification in humans. We suggest that ATLOs harbor a dysregulated immune tolerance environment permissive for autoreactive B cells that express pathogenic autoantibodies promoting atherosclerosis.