Targeting NPM1 Epigenetically Promotes Post-infarction Cardiac Repair by Reprogramming Reparative Macrophage Metabolism [CUT&Tag]

Background: Post-infarction heart failure is attributed to ischemia-induced myocardial inflammation and unfavorable remodeling, with reparative macrophages playing a crucial role in limiting excessive fibrosis and promoting cardiac repair via cytokine secretion and cross-cell interactions. Hence, a timely and adequate transition of macrophage phenotypes is essential for proper wound healing post-MI, but the precise mechanisms underlying this process remain incompletely elucidated. Methods: To elucidate the function of NPM1 in post-infarct cardiac repair, we generated macrophage-specific NPM1 knockout mouse models. Additionally, Cut&Tag assays were conducted on cardiac macrophages for the first time to explore the epigenetic mechanisms underlying NPM1-mediated regulation of macrophage metabolic reprogramming. Results: Macrophage-specific deletion of NPM1 in MI mouse models resulted in reduced tissue fibrosis and enhanced cardiac repair by promoting the phenotypic transition of macrophages towards a reparative state. NPM1 deletion also led to a shift in macrophage metabolism from glycolysis to mitochondrial OXPHOS via inactivation of the mTOR cascades. Mechanistically, we demonstrated that IL-4 induced NPM1 oligomerization, which recruited histone demethylase KDM5b to the promoter region of Tsc1, ultimately leading to macrophage metabolic rewiring. Antisense oligonucleotides and inhibitory compounds targeting NPM1 exhibited notable protective effects on cardiac repair post-MI. Conclusions: Our study demonstrates that NPM1 may serve as a promising prognostic biomarker and a valuable therapeutic target for ischemia-induced heart failure, shedding new light on the understanding of post-infarct cardiac repair and may pave the way for the development of innovative therapeutic strategies. Overall design: WT and Npm1-cKO mice suffered from MI for 3 days, and WT mice that underwent a sham operation were sacrificed by CO2 anesthesia. The hearts were rapidly extracted and used to isolate cardiac macrophages. The bone marrow-derived cells were isolated from WT and Npm1-cKO mice and stimulated with 50 ng/ml M-CSF for 7 days to develop into macrophages.