LMK235 ameliorates inflammation and fibrosis after myocardial infarction by inhibiting LSD1-related pathway

Abstract Background: Histone deacetylase 4 (HDAC4) and histone deacetylase 5 (HDAC5) are two isoforms of class IIa HDACs, and LMK235 is an HDAC inhibitor with higher selectivity for HDAC4/5. This study aimed to explore the expression and subcellular localization of HDAC4/5 and determine the mechanisms underlying the impact of LMK235 on ventricular remodelling post-MI. Methods: The MI model was established by left anterior descending branch (LAD) ligation, and LMK235 or vehicle was intraperitoneally injected daily for 3 weeks. Cardiac function was determined by echocardiography. Inflammation was evaluated by HE staining and measuring inflammatory cytokine expression, and fibrosis was evaluated by Masson staining and measuring fibrotic biomarker expression. Results: We found that LMK235 ameliorated cardiac dysfunction post-MI by suppressing inflammation and fibrosis, and LMK235 inhibited upregulation of lysine-specific demethylase 1 (LSD1) expression post-MI. In macrophages, LMK235 attenuated lipopolysaccharide (LPS) - induced inflammatory cytokine expression and inhibited LSD1 expression, while overexpression of LSD1 abrogated the anti-inflammatory effect of LMK235. In cardiac fibroblasts, LMK235 attenuated transforming growth factor-β1 (TGF-β1) - induced fibrotic biomarker expression and inhibited LSD1 expression, while overexpression of LSD1 abrogated the antifibrotic effect of LMK235. Conclusion: LMK235 can attenuate chronic inflammation and interstitial fibrosis post-MI, leading to improved cardiac function. The anti-inflammatory effect of LMK235 results from inhibition of the LSD1-NF-κB pathway in macrophages. The antifibrotic effect of LMK235 results from inhibition of the LSD1-Smad2/3 pathway in cardiac fibroblasts.