Abstract P3197: Sarm1 Deficiency Protects Mice Against Diabetic Cardiomyopathy: Potential Mechanisms Via Ameliorating Lipotoxicity

Abstract

Heart failure occurs at nearly twice the rate in diabetic patients as compared to normal patients. NAD levels are decreased in human and murine heart disease models including diabetic hearts. Strategies to raise NAD in these models have primarily focused on increasing NAD synthesis. Alternatively, inhibiting NAD consumption provides another viable path to increasing NAD levels in diabetic hearts. Sterile Alpha and Tir Motif Containing 1 (SARM1) is an NAD hydrolase that mediates axonal degeneration through NAD degradation and promotion of mitochondrial dysfunction. However, the role SARM1 plays in heart disease has not been investigated. We subjected male wild type (WT) and global SARM1 knockout mice (KO) to chronic diabetic stress induced by streptozotocin injections. We showed that 16-week diabetic stress promoted progressive decline in systolic and diastolic function as measured by longitudinal echocardiography. SARM1 deletion (diabetic KO) improved systolic and diastolic function of diabetic mice, despite similar glucose, and plasma aqueous and lipid metabolite levels as the diabetic wild-type mice. Diabetic KO hearts showed increased NAD levels, suggesting that SARM1 may be activated to promote NAD decline in diabetic hearts. Transcriptomic analysis identified 1948 differentially expressed genes in diabetic WT hearts, compared to non-diabetic WT hearts. Gene Module Network Analysis identified upregulation of fatty acid metabolic processes and suppression of genes involved in mitochondrial processes in diabetic hearts. We measured mitochondrial oxygen consumption rate and found suppressed mitochondrial respiration in diabetic WT hearts. SARM1 deficiency reversed the upregulated fatty acid metabolic genes, improved mitochondrial respiration, and elevated NAD levels in diabetic hearts. Genes such as CD36, HADHA, Acot2, and malonyl-CoA are all downregulated by SARM1 deficiency, indicating that SARM1 deficiency may relieve lipotoxicity by improving mitochondrial function and modifying metabolic transcriptional networks in diabetic hearts. Future analysis will shed light on how SARM1 contributes to lipotoxicity as a new pathogenic mechanism of diabetic cardiomyopathy.