Loss of peptidylarginine deiminase 4 mitigates maladaptive cardiac remodeling after myocardial infarction through inhibition of inflammatory and profibrotic pathways

Inflammation and progressive fibrosis represent predictive risk factors for heart failure (HF) development following myocardial infarction (MI). Peptidylargininine deiminase 4 (PAD4) catalyzes the citrullination of arginine residues in polypeptides and has recently been identified as a contributor to HF pathogenesis. This study aimed to evaluate the role of PAD4 in monocytes / macrophages (Mo/Mφ) and cardiac fibroblasts (CFs) for cardiac repair following MI and HF progression. Cardiac Padi4 expression significantly increased in mice subjected to MI by permanent coronary artery ligation as well as in humans who died from MI. Transcriptome analysis revealed marked downregulation of inflammation-related genes in infarcted hearts and cardiac Mo/Mφ from global PAD4 knockout (PAD4^−/−) mice on day 7 post-MI accompanied by increased frequency of reparative CD206⁺ macrophages. Mechanistically, pharmacological and genetic PAD4 inhibition abrogated nuclear NF-κB translocation and inflammatory gene expression in bone marrow-derived macrophages (BMDM). Simultaneously, reduced inflammation and diminished cardiac levels of transforming growth factor-β (TGF-β) along with impaired IL-6 / TGF-β signaling in PAD4^−/− CFs were associated with decreased expression of fibrotic genes, reduced collagen deposition, improved cardiac function, and enhanced 28-day survival in PAD4^−/− mice. Strikingly, whereas pharmacological PAD inhibition in the acute phase after MI exacerbated cardiac damage, treatment starting on day 7 ameliorated cardiac remodeling and improved long-term survival in mice. Collectively, we here identified PAD4 as a critical regulator of inflammatory genes in Mo/Mφ and of profibrotic pathways in CFs. Thus, therapeutic approaches directed against PAD4 are promising interventions to alleviate adverse cardiac remodeling and subsequent HF development.