Inhibition of lactate-histone lactylation mediated cardiomyocyte-fibroblast communication mitigates cardiac fibrosis in cardiomyopathy models with Hippo pathway activation

Metabolic remodeling is a fundamental mechanism that underlies cardiomyopathy and heart failure. Preclinical and clinical studies in diverse types of heart disease have provided evidence for the activation of the myocardial Hippo pathway and that cardiomyocyte-specific Hippo pathway activation or YAP-TEAD1 inactivation drives cardiomyocyte mitochondrial damage, metabolic abnormalities and fibrosis. Here we studied whether intervention of myocardial lactate metabolism have therapeutic effect on cardiac fibrosis in cardiomyopathy models. In a Hippo pathway-activated mouse model (Mst1-cTG), single-nucleus RNA-sequencing (snRNA-seq) revealed activated fibroblasts while cardiomyocytes displayed downregulation of gene sets of mitochondrial metabolism and augmented HIF-1 signaling. Seahorse assay in isolated cardiomyocytes from adult TG mice showed impaired oxidative respiratory capacity together with enhanced glycolysis and lactate production. In TG mouse myocardium, fibroblast histone H3 lysine 18 lactylation (H3K18la), regulated by p300, was elevated starting from young age. By CUT&Tag, H3K18la was found to be enriched in promoter regions of numerous fibrotic genes with enhanced transcription. Treatment of TG mice with inhibitors to suppress either glycolysis (PX-478 as HIF-1α inhibitor) or lactate production (FX-11 as LDHA inhibitor) reduced both myocardial lactate content and H3K18la level, and ameliorated cardiac fibrosis and dysfunction. Similar efficacy was achieved in vitro or in vivo by fibroblast p300 knockdown using siRNA or AAV9. Treatment with FX-11 was similarly effective in inhibiting histone lactylation and fibrosis in mice subjected to chronic ischemia-reperfusion. Finally, we integrated our snRNA-seq and CUT&Tag studies to identify RUNX2 as a crucial transcription factor that promotes fibrotic gene expression in concert with H3K18la levels. Treatment with RUNX2 inhibitor CADD522 in TG mice improved heart dysfunction and fibrosis. In the setting of myocardial Hippo pathway activation, inhibiting the lactate-histone lactylation-RUNX2 axis effectively attenuated cardiac fibrosis.