Abstract 334: Gut Microbiome Derived Trimethyl-n-oxide Exacerbates Inflammation And Induces Cardiac Fibrosis In Human Cardiac Fibroblasts And In Rodent Model Of Cardiorenal Disease

Abstract

Trimethlyamine N-oxide (TMAO), a gut-microbiome derived metabolite of dietary choline and other trimethylamine containing nutrients, has been consistently associated with poor prognosis with cardiovascular diseases (CVD) in recent years. Clinical studies have demonstrated that systemic circulating TMAO levels are independently associated with adverse CVD events such as MI, heart failure (HF), stroke, CKD and death. Previous studies have reported elevated TMAO both in mice models of atherosclerosis and in patients with atherosclerosis, and association between increased TMAO levels with adverse outcomes in HF patients, with significant correlation between increased TMAO levels and heart failure risk. The role and underlying mechanisms of TMAO in mediating disease pathophysiology remains elusive. Here, we use primary human cardiac fibroblasts and rodent models of heart failure with TMAO challenge to study its role in the heart and in cardiac fibroblasts. C57BL/6 mice were administered with TMAO (0.2%) in the drinking water for 2, 4 and 8 weeks. Heart tissues were collected at the end of the study to evaluate cardiac fibrosis, and blood samples were evaluated for TMAO levels. For heart failure studies, ZSF1 rats that underwent uninephrectomy surgery were fed high salt diet and were used as a model for heart failure with preserved ejection fracture (HFpEF), and were followed for 12 weeks. ZSF1 rats were also fed with high choline diet and cardiac function was measured using echocardiography. We demonstrated an elevation in blood TMAO levels, with a concomitant increase in circulating pro-inflammatory cytokine levels and upregulation in fibrosis markers in hearts from mice administered TMAO. In a ZSF1 rat model of HFpEF, we showed that increased TMAO levels correlated with deteriorating cardiac dysfunction. In human cardiac fibroblasts, stimulation with TMAO promoted upregulation of key fibrosis markers such as TGF-β1 in a dose-dependent manner. Inflammation, cardiac function, and cardiac fibrosis were exacerbated in mice administered with TMAO in their drinking water. Furthermore, in ZSF1 rat model for HFpEF, there was a significant association of high TMAO levels to worsening of cardiac and renal dysfunction.