N-Propargyl caffeate amide (PACA) prevents cardiac fibrosis in experimental myocardial infarction by promoting pro-resolving macrophage polarization

Macrophages control the initiation and resolution of cardiac fibrosis in post-infarction cardiac remodeling. The aim of the present study was to investigate whether N-propargyl caffeate amide (PACA) could suppress myocardial fibrosis via regulating macrophage polarization. By using rat model of isoproterenol-induced myocardial fibrosis, we discovered that PACA could reduce cardiac fibrosis in a dose-dependent manner. To elucidate the anti-fibrotic mechanisms, we examined whether PACA affected pro-inflammatory M1 and pro-resolving macrophage biomarkers in macrophage polarization. As result, PACA reduced the expression of pro-inflammatory M1 biomarkers (e.g., iNOS, TNF-α, CXCL10, IL-6, CCL2 and CD80) while increased the expression of pro-resolving M2a biomarkers (e.g., IL-10, arginase-1, FZZ1, YM-1 and CD163) in LPS-stimulated RAW264.7 macrophages. PACA also suppressed the elevation of M1 biomarker ED1 in the early phase but up-regulated the expression of pro-resolving biomarker ED2 in the later phase. Moreover, PACA reduced the expression of pro-fibrotic TGF-β1 and PDGF-α while maintained or even increased the production of pro-apoptotic MMP-13, MMP-9 and TRAIL. Importantly, mechanistic studies revealed that PACA might promote the switch of macrophage polarization towards a pro-resolving macrophage phenotype via activating PPAR-γ pathway. Taken together, this study suggested that PACA might be a drug candidate for preventing cardiac fibrosis in myocardial infarction.