Caffeic acid mitigates myocardial fibrosis via suppressing MAPKs/CREB-mediated inflammation in myocardial ischemia–reperfusion injury mice

BACKGROUND: Myocardial ischemia-reperfusion injury (MIRI) represents a major form of secondary damage during reperfusion therapy, in which inflammation and myocardial fibrosis are key pathological features. Caffeic acid (CA), a natural phenolic compound abundant in dietary sources, has been implicated in cardiovascular protection; however, the mechanisms by which CA modulates post-MIRI inflammation and fibrosis remain insufficiently defined. OBJECTIVE: To clarify the molecular target(s) and signaling mechanism(s) through which CA attenuates inflammation-associated myocardial fibrosis after MIRI. METHODS: A LAD ligation-based murine MIRI model was used to evaluate the anti-inflammatory and anti-fibrotic efficacy of CA. A co-culture system using cardiac fibroblasts and RAW 264.7 macrophages, along with adoptive cell transfer, was applied to interrogate macrophage-fibroblast crosstalk. Transcriptomic profiling (RNA-seq) was performed to identify candidate pathways involved in CA-mediated protection. Surface plasmon resonance (SPR) assay, CETSA, immunofluorescence, and western blotting were used to assess MAPKs/CREB signaling as a putative intervention axis, and pharmacological activation of MAPKs (anisomycin) or CREB (forskolin), or MAPK14 ablation, was employed to probe pathway involvement. RESULTS: CA improved cardiac function and alleviated inflammatory and fibrotic pathology in MIRI mice, accompanied by suppression of pro-inflammatory cytokines. Conditioned medium from LPS-stimulated RAW 264.7 cells promoted fibroblast activation, and adoptively transferred macrophages within the myocardium promoted fibrotic protein expression; both effects were attenuated by CA. RNA-seq implicated MAPK signaling in the protective mechanism of CA, and downstream analyses supported inhibition of the MAPKs/CREB axis. Notably, CA achieved effects comparable to those of MAPK14 ablation, whereas anisomycin or forskolin partially blunted the anti-inflammatory and anti-fibrotic effects of CA, consistent with functional involvement of MAPKs/CREB signaling in CA-mediated protection during MIRI. CONCLUSION: CA mitigates MIRI-associated myocardial fibrosis by suppressing MAPKs/CREB-mediated inflammatory signaling, supporting its potential to improve long-term post-MIRI remodeling.