Macrophage Rmp Ameliorates Myocardial Infarction by Modulating Macrophage Polarization in Mice

BACKGROUND: Inflammation plays important roles during myocardial infarction (MI). Macrophage polarization is a major factor that drives the inflammatory process. Our previous study found that RNA polymerase II subunit 5-mediating protein (RMP) knockout in cardiomyocytes caused heart failure by impairing mitochondrial structure and function. However, whether macrophage RMP plays a role in MI has not been investigated. METHODS: Macrophage RMP-knockout in combination with a mouse model of MI was used to study the function of macrophage RMP in MI. Next, we modified bone marrow-derived macrophages (BMDMs) by plasmid transfection, and the BMDMs were administered to LysM-Cre/DTR mice by tail vein injection. Immunoblotting and immunofluorescence were used to detect macrophage polarization, fibrosis, angiogenesis, and the p38 signaling pathway in each group. RESULTS: Macrophage RMP deficiency aggravates cardiac dysfunction, promotes M1 polarization, and inhibits angiogenesis after MI. However, RMP overexpression in macrophages promotes M2 polarization and angiogenesis after MI. Mechanistically, we found that RMP regulates macrophage polarization through the heat shock protein 90– (HSP90–) p38 signaling pathway. CONCLUSIONS: Macrophage RMP plays a significant role in MI, likely by regulating macrophage polarization via the HSP90–p38 signaling pathway.