Dysbiotic microbiome induce cardiac impairment by attenuating brain-derived neurotrophic factor in inflammatory bowel diseases

Abstract

Abstract Background & Aims Mounting evidence suggests that inflammatory bowel disease (IBD) is associated with increased incidences of cardiovascular diseases (CVD), including myocardial infarction and heart failure. However, the molecular mechanisms by which IBD predisposes patients to CVD are poorly understood. This study aimed to identify the role of dysbiosis in gut-heart crosstalk. Methods Chronic colitis-induced cardiac impairment was assessed in mice subjected to dextran sodium sulfate (DSS), rats treated with trinitrobenzenesulfonic acid, and IL10-/-mice which develop spontaneous colitis after weaning. Fecal microbiota of wild type or IL10-/- mice were transplanted to C57BL/6J mice treated with microbiome-depleting antibiotic cocktail and germ-free mice to determine if dysbiosis afflicts the heart. Heart function was evaluated by echocardiography. Heart transcriptomes were profiled by RNA-sequencing. Gut microbiota profiling was performed by 16S rRNA sequencing. Adverse effect of brain-derived neutrophic factor (BDNF) deficiency on the heart was evaluated in cardiac-specific BDNF knockout mice (BdnfΔheart). Results Impairment of heart function, evidenced by decreased left ventricle ejection fraction (LVEF), increased LV mass, and elevated serum B-type natriuretic peptide, was observed in all 3 models of colitis, providing direct evidence that chronic colitis deteriorates the heart (Figure 1). RNA-sequencing revealed loss of Bdnf and alterations of multiple genes critical to heart homeostasis in the myocardium. Many of the changes, including Bdnf reduction, were found in microbiota-depleted C57BL/6J mice and germ-free mice received dysbiotic fecal microbiome, compared to controls, suggesting that dysbiosis impaired the heart by suppressing Bdnf. BdnfΔheart mice had impaired heart function, including decreased contractility and EF, increased fibrosis, and impaired coronary microcirculation (lower CD31), compared to Bdnf[2lox] mice. Mechanistically, miR-155 in the heart and exosomal miR-29b in the plasma were significantly elevated by chronic colitis. miR-155 and miR-29b mimics suppressed BDNF in cardiomyocytes both in vitro and in vivo. Administration of miR-155 inhibitors or exosomes packaged with miR-29b antagonists ameliorated BDNF reduction in the heart of IL10-/- mice. BDNF supplementation markedly improved heart function in DSS mice. Conclusions Chronic colitis impairs the heart through dysbiosis/miR-29b/miR-155/BDNF signaling axis. Targeting this pathway is a promising strategy to overcome gut dysbiosis harmful for the heart in IBD.