Role Of SDF:CXCR4 In Diet‐Induced Cardiac Injury

Abstract

IntroductionDiabetic cardiomyopathy (DCM) is a major cardiovascular complication in patients with diabetes and is defined as ventricular dysfunction (in diabetes) independent of coronary artery disease. In this study, we define a novel role for the SDF‐1: CXCR4 axis in diabetes‐associated myocardial dysfunction.MethodsWild‐type mice were randomly assigned to a high fat high sugar diet (HFHS) or control diet (LF) for 14 months. Serial echocardiography was used to assess cardiac function. The hSDF‐1 plasmid was injected into the LV wall of HFHS mice 7 months and 14 months after HFHS diet. The mRNA levels in the hearts were quantified by qPCR.ResultsHFHS‐fed mice (vs. control diet) showed significantly increased deceleration time (diastolic dysfunction) 7 months after HFHS diet and decreased Ejection Fraction (EF) (systolic dysfunction) 14 months after the HFHS diet. We observed a significant increase in cardiac myocytes surface area and a decrease in vascular density in the hearts of HFHS mice. HFHS‐fed mice showed decreased P‐selectin, E‐selectin expression and increased CXCR4, Resistin, and DDR2 expression in the heart. There is no significant improvement in diastolic function after the SDF‐1 injection at 7 month. However, direct myocardial injection of hSDF‐1 plasmid led to a significant improvement in EF compared to the control group. To determine the role of CM CXCR4 in hyperglycemia associated cardiac injury, we quantified cardiac function and survival rate in HFHS‐fed CM‐CXCR4 null mice. We observed a significantly increased mortality rate before 14 months on HFHS fed CM‐CXCR4 null mice compare to HFHS‐fed control mice.ConclusionHFHS diet induces diastolic dysfunction in the short term then systolic dysfunction after a long term. SDF‐1 treatment ameliorates systolic dysfunction but not diastolic dysfunction. Our data suggest that cardiac myocyte expression of CXCR4 has an important role in diabetes‐associated cardiac injury.