T1D remains the primary cause of DCM. The long-term goal is to understand the mechanism of T1D leading to DCM. Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays an important role in degrading the low-density lipoprotein receptors (LDLRs) and that increases the circulating LDL cholesterol (LDL-C). Further, PCSK9 increases duringT1D and that, in turn, decreases mitochondrial bioenergetics, transcription factor- mitochondrial (TFAM), and the mitochondrial numbers thus creates an oxidative stress. These changes lead to oxidation of high-density lipoprotein paraoxonase-1 (HDL-Pon1). Because Pon1 hydrolyzes homocysteine (Hcy), the oxidized Pon1 thus causes accumulation of Hcy (i.e. hyperhomocysteinemia; HHcy). Also, the 'metabolic memory' is associated with epigenetic modification (methylation) of genes encoding proteins such as thioredoxin interacting protein (TXNIP). Since methylation/epigenetics inhibits genes, this phenomenon generates even more amounts of Hcy. Investigators have shown that HHcy decreases G-protein coupled receptor (GPCR) Gαs subunit, protein kinase-B (AKT), focal adhesion kinase (FAK) but increases calpain-1, inflammasome and oxidative stress. The central hypothesis is that an increase in PCSK9 causes oxidative stress and decreases TXNIP thus causing oxidation of HDL-Pon1 and subsequent accumulation of Hcy. These alterations lead to decrease in Gαs, AKT, FAK and concomitant increase in PCSK9 and calpain-1 causing metabolic, diastolic, and systolic cardiac dysfunction. Treatment with ketone bodies (the food for mitochondria) will mitigate these changes.
This study will demonstrate the beneficial effects of ketone bodies in type 1 diabetes (T1D) patients and will have significant translational applications to prevent serious metabolic conditions such as T1D induced diabetic cardiomyopathy (DCM).