Gamma-interferon-inducible lysosomal thiol reductase maintains cardiac immuno-metabolic homeostasis in heart failure

BackgroundThe lysosome is a central player in maintaining immuno-metabolic homeostasis. However, mechanistic insights into the regulation of lysosome-dependent immuno-metabolism in the heart are lacking. Lysosomal reductase Gamma Interferon-Inducible Thiol Reductase (GILT) is the only identified lysosomal reductase that controls diverse sets of lysosomal enzymes and cargoes. MethodsThe role of cardiac GILT was assessed by generating a novel genetic mouse model and employing a multidisciplinary approach including surgical interventions, live in situ high resolution microscopy, whole-tissue respirometry analysis, unbiased transcriptomic and metabolomic analyses, and various cell biology and biochemical assays. ResultsWe found that expression and activity of GILT are reduced in hearts from humans and mice with heart failure (HF). Mice with cardiac specific loss of GILT develop late onset systolic HF at baseline. In the setting of nutrient-overload and experimental left ventricular pressure overload conditions, loss of GILT in cardiomyocytes accelerates the development of heart dysfunction. Transcriptomic and metabolic analyses further revealed that cardiac GILT deficiency alters adaptive immuno-metabolic signatures in the heart. Finally, at the cellular level, cardiac GILT deletion impaired mitochondrial respiration, which was in part due to NLR Family Pyrin Domain Containing 3 (NLRP3)-mediated elevation of mitochondrial oxidative stress. ConclusionsTogether, these findings identify a causal link between a lysosome-inflammation axis, mitochondrial function and heart failure. Elucidation of these mechanisms will identify novel therapeutic strategies for treating HF.