ChGn‐2 Plays a Cardioprotective Role in Heart Failure Caused by Acute Pressure Overload

Abstract

Background Cardiac extracellular matrix is critically involved in cardiac homeostasis, and accumulation of chondroitin sulfate glycosaminoglycans (CS‐GAGs) was previously shown to exacerbate heart failure by augmenting inflammation and fibrosis at the chronic phase. However, the mechanism by which CS‐GAGs affect cardiac functions remains unclear, especially at the acute phase. Methods and Results We explored a role of CS‐GAG in heart failure using mice with target deletion of ChGn‐2 (chondroitin sulfate N‐acetylgalactosaminyltransferase‐2) that elongates CS chains of glycosaminoglycans. Heart failure was induced by transverse aortic constriction in mice. The role of CS‐GAG derived from cardiac fibroblasts in cardiomyocyte death was analyzed. Cardiac fibroblasts were subjected to cyclic mechanical stretch that mimics increased workload in the heart. Significant CS‐GAGs accumulation was detected in the heart of wild‐type mice after transverse aortic constriction, which was substantially reduced in ChGn‐2‐/‐ mice. Loss of ChGn‐2 deteriorated the cardiac dysfunction caused by pressure overload, accompanied by augmented cardiac hypertrophy and increased cardiomyocyte apoptosis. Cyclic mechanical stretch increased ChGn‐2 expression and enhanced glycosaminoglycan production in cardiac fibroblasts. Conditioned medium derived from the stretched cardiac fibroblasts showed cardioprotective effects, which was abolished by CS‐GAGs degradation. We found that CS‐GAGs elicits cardioprotective effects via dual pathway; direct pathway through interaction with CD44, and indirect pathway through binding to and activating insulin‐like growth factor‐1. Conclusions Our data revealed the cardioprotective effects of CS‐GAGs; therefore, CS‐GAGs may play biphasic role in the development of heart failure; cardioprotective role at acute phase despite its possible unfavorable role in the advanced phase.

Keywords

• cardiac fibroblasts
• cardiomyocytes
• chondroitin sulfate glycosaminoglycan
• extracellular matrix
• heart failure
• mechanical stretch