Abstract
BackgroundExcessive reactive oxygen species from endothelial mitochondria in type 2 diabetes individuals (T2DM) may occur through multiple related mechanisms, including production of mitochondrial reactive oxygen species (mtROS), inner mitochondrial membrane (Δψm) hyperpolarization, changes in mitochondrial mass and membrane composition, and fission of the mitochondrial networks. Inner mitochondrial membrane proteins uncoupling protein-2 (UCP2) and prohibitin (PHB) can favorably impact mtROS and mitochondrial membrane potential (Δψm). Circulating levels of UCP2 and PHB could potentially serve as biomarker surrogates for vascular health in patients with and without T2DM.MethodsPlasma samples and data from a total of 107 individuals with (N = 52) and without T2DM (N = 55) were included in this study. Brachial artery flow mediated dilation (FMD) was measured by ultrasound. ELISA was performed to measure serum concentrations of PHB1 and UCP2. Mitochondrial membrane potential was measured from isolated leukocytes using JC-1 dye.ResultsSerum UCP2 levels were significantly lower in T2DM subjects compared to control subjects (3.01 ± 0.34 vs. 4.11 ± 0.41 ng/mL, P = 0.04). There were no significant differences in levels of serum PHB. UCP2 levels significantly and positively correlated with FMDmm (r = 0.30, P = 0.03) in T2DM subjects only and remained significant after multivariable adjustment. Within T2DM subjects, serum PHB levels were significantly and negatively correlated with UCP2 levels (ρ = − 0.35, P = 0.03).ConclusionCirculating UCP2 levels are lower in T2DM patients and correlate with endothelium-dependent vasodilation in conduit vessels. UCP2 could be biomarker surrogate for overall vascular health in patients with T2DM and merits additional investigation.
Highlights
Excessive reactive oxygen species from endothelial mitochondria in type 2 diabetes individuals (T2DM) may occur through multiple related mechanisms, including production of mitochondrial reactive oxygen species, inner mitochondrial membrane (Δψm) hyperpolarization, changes in mitochondrial mass and membrane composition, and fission of the mitochondrial networks
Total and LDL cholesterol levels were lower in T2DM subjects likely due to great use of HMG-CoA reductase medications in T2DM patients 51% were on HMG-CoA inhibitors
No variables were independently predictive of absolute flow-mediated dilation (FMDmm) models with PHB and inner mitochondrial membrane potential (Δψm), Discussion In this cross-sectional study, we found population-specific correlation of vascular measurements with measurements of circulating levels of mitochondrial proteins (UCP2 and PHB) involved with modulating Δψm and mitochondrial superoxide production, as well as Δψm itself
Summary
Excessive reactive oxygen species from endothelial mitochondria in type 2 diabetes individuals (T2DM) may occur through multiple related mechanisms, including production of mitochondrial reactive oxygen species (mtROS), inner mitochondrial membrane (Δψm) hyperpolarization, changes in mitochondrial mass and membrane composition, and fission of the mitochondrial networks. Partial mitochondrial membrane depolarization of arterioles improve endothelium-dependent vasodilation and NO bioavailability in arterioles from patients with T2DM or arterioles from health individuals exposed acutely to abnormal glucose levels [7, 8, 13] These data suggest proteins involved with regulating mitochondrial membrane potential could potentially serve as biomarker surrogates for vascular health in T2DM [7, 14]. This concept is further supported by data suggesting mitochondrial-derived proteins and nucleotides may serve play paracrine and endocrine-like signaling roles regulating vascular health [15, 16]
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