Cardiac lipotoxicity and fibrosis underlie impaired contractility in a mouse model of metabolic dysfunction‐associated steatotic liver disease

Abstract

Abstract The leading cause of death among patients with metabolic dysfunction‐associated steatotic liver disease (MASLD) is cardiovascular disease. A significant percentage of MASLD patients develop heart failure driven by functional and structural alterations in the heart. Previously, we observed cardiac dysfunction in hepatocyte‐specific peroxisome proliferator‐activated receptor alpha knockout (PparaHepKO), a mouse model that exhibits hepatic steatosis independent of obesity and insulin resistance. The goal of the present study was to determine mechanisms that underlie hepatic steatosis‐induced cardiac dysfunction in PparaHepKO mice. Experiments were performed in 30‐week‐old PparaHepKO and littermate control mice fed regular chow. We observed decreased cardiomyocyte contractility (0.17 ± 0.02 vs. 0.24 ± 0.02 μm, p < 0.05), increased cardiac triglyceride content (0.96 ± 0.13 vs. 0.68 ± 0.06 mM, p < 0.05), collagen type 1 (4.65 ± 0.25 vs. 0.31 ± 0.01 AU, p < 0.001), and collagen type 3 deposition (1.32 ± 0.46 vs. 0.05 ± 0.03 AU, p < 0.05). These changes were associated with increased apoptosis as indicated by terminal deoxynucleotidyl transferase dUTP nick end labeling staining (30.9 ± 4.7 vs. 13.1 ± 0.8%, p < 0.006) and western blots showing increased cleaved caspase‐3 (0.27 ± 0.006 vs. 0.08 ± 0.01 AU, p < 0.003) and pro‐caspase‐3 (5.4 ± 1.5 vs. 0.5 ± 0.3 AU, p < 0.02), B‐cell lymphoma protein 2‐associated X (0.68 ± 0.07 vs. 0.04 ± 0.04 AU, p < 0.001), and reduced B‐cell lymphoma protein 2 (0.29 ± 0.01 vs. 1.47 ± 0.54 AU, p < 0.05). We further observed elevated circulating natriuretic peptides and exercise intolerance in PparaHepKO mice when compared to controls. Our data demonstrated that lipotoxicity, and fibrosis underlie cardiac dysfunction in MASLD.

Keywords

• cardiac apoptosis
• cardiac fibrosis
• cardiac lipid accumulation
• cardiomyocyte contractility
• heart failure
• hepatic steatosis