Abstract 4362958: RNS-Related Myocardial Injury: Sympathetic Activation-Induced Proinflammatory Bone Marrow Remodeling and Trained Immunity

An RNS mouse model was established using a “24-hour sleep deprivation and 48-hour recovery cycle” repeated for 5 cycles. RNS mice exhibited elevated peripheral inflammation and myocardial injury. Single-cell RNA sequencing (scRNA-seq) combined with flow cytometry revealed increased infiltration of macrophages in cardiac tissues of RNS mice, primarily originating from the bone marrow. Reactome enrichment analysis identified significant activation of the Dectin-1 signaling pathway in cardiac-infiltrating monocytes and macrophages, and genetic knockout of Dectin-1 (Dectin-1-/-) markedly attenuated RNS-induced macrophage infiltration and myocardial injury. Epigenetic profiling (ATAC-seq and CUT–Tag) demonstrated that even after a 4-week recovery period, RNS-exposed hematopoietic stem and progenitor cells (HSPCs) maintained increased chromatin accessibility at genes related to leukocyte migration and myeloid cell differentiation, accompanied by persistent enrichment of H3K4me3 modifications at these loci, suggesting the establishment of trained immunity. Furthermore, RNS-induced trained immunity could be transferred to recipient mice via bone marrow transplantation, leading to exaggerated inflammatory responses upon secondary challenges such as RNS or ischemia-reperfusion injury. Mechanistic studies showed that sympathetic activation elevated norepinephrine levels in bone marrow, which primarily via β1-adrenergic receptor (β1-AR) upregulated EGR1 expression in HSPCs. ChIP-qPCR and dual-luciferase reporter assays confirmed that EGR1 directly binds to and transactivates the promoters of histone methyltransferases SETD1B and KMT2B. EGR1 knockout significantly suppressed norepinephrine-induced pro-inflammatory reprogramming and trained immunity in bone marrow. In vitro siRNA knockdown experiments further revealed that SETD1B depletion more potently inhibited H3K4me3 establishment compared to KMT2B, implicating the β1-AR/EGR1/SETD1B axis as dominant in sympathetic-driven trained immunity. Clinical translational studies detected consistent H3K4me3 enrichment and upregulated Dectin-1 signaling pathway genes in peripheral blood monocytes of night-shift workers. In animal models, EGR1-/- mice exhibited suppressed Dectin-1 signaling pathway and reduced myocardial injury, while AAV-mediated Dectin-1 overexpression reversed this protection, confirming that RNS-activated trained immunity exacerbates myocardial injury via the Dectin-1 pathway.