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Background and Aims Survivors of acute coronary syndromes face an elevated risk of recurrent atherosclerosis-related vascular events despite advanced medical treatments. The underlying causes remain unclear. This study aims to investigate whether myocardial infarction (MI)-induced trained immunity in monocytes could sustain proatherogenic traits and expedite atherosclerosis. Methods Apolipoprotein-E deficient (ApoE−/−) mice and adoptive bone marrow transfer chimeric mice underwent MI or myocardial ischaemia–reperfusion (IR). A subsequent 12-week high-fat diet (HFD) regimen was implemented to elucidate the mechanism behind monocyte trained immunity. In addition, classical monocytes were analysed by flow cytometry in the blood of enrolled patients. Results In MI and IR mice, blood monocytes and bone marrow-derived macrophages exhibited elevated spleen tyrosine kinase (SYK), lysine methyltransferase 5A (KMT5A), and CCHC-type zinc finger nucleic acid-binding protein (CNBP) expression upon exposure to a HFD or oxidized LDL (oxLDL) stimulation. MI-induced trained immunity was transmissible by transplantation of bone marrow to accelerate atherosclerosis in naive recipients. KMT5A specifically recruited monomethylation of Lys20 of histone H4 (H4K20me) to the gene body of SYK and synergistically transactivated SYK with CNBP. In vivo small interfering RNA (siRNA) inhibition of KMT5A or CNBP potentially slowed post-MI atherosclerosis. Sympathetic denervation with 6-hydroxydopamine reduced atherosclerosis and inflammation after MI. Classical monocytes from ST-elevation MI (STEMI) patients with advanced coronary lesions expressed higher SYK and KMT5A gene levels. Conclusions The findings underscore the crucial role of monocyte trained immunity in accelerated atherosclerosis after MI, implying that SYK in blood classical monocytes may serve as a predictive factor for the progression of atherosclerosis in STEMI patients. [ABSTRACT FROM AUTHOR]

This study aims to investigate the mechanism of Mailuo Shutong Pills(MLST) on posterior limb muscle swelling caused by femoral fracture(SCFF) through network pharmacology and animal experiments. The plasma components of MLST were analyzed by LC-MS, and the target and signal pathway of SCFF were predicted by network pharmacology and verified by molecular docking. SCFF model rats were established through animal experiments, and different doses of MLST were administered to detect the degree of limb swelling. Hematoxylin-eosin(HE) staining was used to observe pathological changes in muscle tissue, and interleukin-6(IL-6), interleukin-1β(interleukin-1β), and tumor necrosis factor-α(TNF-α) in peripheral blood were determined by enzyme-linked immunosorbent assay(ELISA). The expression of relevant signaling pathways was measured by Western blot. Network pharmacological results showed that MLST and SCFF had a total of 153 disease targets, and the key targets were IL-6, TNF, etc., involving mitogen-activated protein kinase(MAPK) signaling pathway, phosphatidylinositol 3-kinase(PI3K)/protein kinase B(AKT) signaling pathway, etc. The binding energies of the main components and key targets were lower than-7.0 kcal·mol~(-1), indicating that the network analysis results were reliable. The results of animal experiments showed that MLST could reduce the swelling degree and pathological damage of the posterior limb muscles of SCFF rats compared with the model group. ELISA results showed that MLST could reduce the levels of IL-6, IL-1β, and TNF-α in the serum of SCFF rats. Western blot results showed that MLST can reduce the expression of p-AKT, p-PI3K, p-NF-κB, p-p38 MAPK, and p-ERK in SCFF rats. MLST may reduce the content of inflammatory factors in serum by regulating the expression of PI3K/AKT and MAPK-related signaling pathway protein and improving posterior limb muscle SCFF in rats.