Circulating levels of mitochondrial uncoupling protein 2, but not prohibitin, are lower in humans with type 2 diabetes and correlate with brachial artery flow-mediated dilation

Cardiovasc Diabetol. 2019 Nov 9;18(1):148. doi: 10.1186/s12933-019-0956-4.

Abstract

Background: 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. 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.

Methods: Plasma 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.

Results: Serum 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).

Conclusion: Circulating 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.

Keywords: Endothelium; Mitochondria; Mitochondrial membrane potential; PHB; UCP2.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Biomarkers / blood
  • Brachial Artery / diagnostic imaging
  • Brachial Artery / physiopathology*
  • Case-Control Studies
  • Diabetes Mellitus, Type 2 / blood*
  • Diabetes Mellitus, Type 2 / diagnosis
  • Diabetes Mellitus, Type 2 / physiopathology
  • Female
  • Humans
  • Leukocytes / metabolism*
  • Male
  • Membrane Potential, Mitochondrial
  • Middle Aged
  • Mitochondria / metabolism*
  • Pilot Projects
  • Prohibitins
  • Repressor Proteins / blood*
  • Uncoupling Protein 2 / blood*
  • Vasodilation*

Substances

  • Biomarkers
  • PHB protein, human
  • Prohibitins
  • Repressor Proteins
  • UCP2 protein, human
  • Uncoupling Protein 2