Exposure to Type 2 Diabetes Provokes Mitochondrial Impairment in Apparently Healthy Human Hearts.

Cardiac mitochondrial alterations are suspected to play a key role in the development of diabetes-related heart failure as reported in some animal and few human studies in type 2 diabetes (1). It is yet unclear whether these alterations are induced by diabetes-related metabolic changes or develop secondary to other factors underlying heart failure including micro- and macrovascular disease. We hypothesized that 1 ) exposure to type 2 diabetes provokes myocardial mitochondrial impairment prior to apparent left ventricular heart failure in humans and 2 ) these mitochondrial alterations are accompanied by increased oxidative stress, edema, and intracellular inflammation. The cohort of this cross-sectional clinical study (study number 5263R; ClinicalTrials.gov NCT03386864) comprised adult heart transplant recipients undergoing routine transcatheter ventricular endomyocardial biopsies (EMB) post-transplantation, who received heart transplants of donors without type 2 diabetes. Thus, time between transplantation and EMB (2.9 ± 2.4 years) corresponded to the exposure of the hearts to type 2 diabetes. The first post-transplantation visit was included; exclusion criteria comprised allograft rejection (>0R according to International Society for Heart and Lung Transplantation criteria) and coronary artery disease (assessed via coronary angiography). Participants underwent oral glucose tolerance tests to assess glucose tolerance and insulin sensitivity (oral glucose insulin sensitivity [OGIS]). Cardiac magnetic resonance imaging was conducted at 1.5T to determine ventricular volumes and function, left ventricular T2 relaxation time, global left ventricular longitudinal strain (GLS), and diastolic strain rate. EMBs were attained for assessment of allograft rejection, mRNA expression of nuclear factor κ-light-chain-enhancer of activated B cells p105 subunit (NF-κB1), Toll-like receptor 9 (TLR9), and mitochondrially encoded cytochrome c oxidase I (CO1) and mitochondrial function using high-resolution respirometry in permeabilized …