Increased plasma markers of oxidative stress are associated with coronary heart disease in males with diabetes mellitus and with 10-year risk in a prospective sample of males

Background: Increased oxidative stress is associated with coronary heart disease (CHD). We examined the association between plasma markers of oxidative stress and CHD in a cross-sectional sample of patients with diabetes and prospective CHD risk in a sample of men predominantly without diabetes. Methods: Plasma total antioxidant status (TAOS) and the ratio of oxidized LDL (Ox-LDL) to LDL-cholesterol (LDL-C) were determined in a cross-section of 761 Caucasian individuals with diabetes (UDACS study). Plasma TAOS was also determined in 310 baseline samples from a 10-year prospective cohort of 3012 healthy males (NPHSII). Results: Within UDACS, males with CHD had lower mean (SD) plasma TAOS [no CHD, 43.4 (13.2)%; CHD, 40.3 (13.8)%; P = 0.04]. The prevalence of CHD was higher in the lowest compared with the upper quartiles (32.7% vs 19.7%; P = 0.004). We observed a significant association between plasma Ox-LDL:LDL-C and CHD status [no CHD vs CHD, 16.9 (3.1) vs 19.3 (5.0) units/mmol; P = 0.04], with the prevalence of CHD being higher among men in the upper compared with lower quartiles (18.4% vs 35.1%; P = 0.003). No association was observed in females. In NPHSII, TAOS was lower in those who developed CHD [35.1 (8.0)% vs 37.1 (7.9)%; P = 0.04]. The odds ratio for CHD in the lowest compared with the upper quartile was 1.91 (95% confidence interval, 0.99–3.70; P = 0.04). This remained unchanged after adjustment for classic risk factors. Conclusions: A cross-sectional and prospective association exists between baseline plasma measures of oxidative stress and CHD risk. The association with prospective CHD risk remained after adjustment for "traditional" risk factors, implying an independent role for oxidative stress in CHD risk

The use of a genetic strategy to study the role of modulation of oxidative stress by uncoupling proteins 2 and 3 in the pathogenesis of Type 2 Diabetes

Mitochondrial dysfunction has been implicated in the early pathogenesis of Type 2 Diabetes. The uncoupling proteins 2 and 3 are mitochondrial proteins found in man that have been implicated in protecting mammals from the effects of over-nutrition. Examination of the effect of genetic variation in the UCP2-UCP3 genetic cluster has so far been inconclusive. The aim of this thesis was to examine, using a genetic strategy, the hypothesis that the role of the uncoupling proteins 2 and 3 in the pathogenesis of Type 2 Diabetes is via modification of oxidative stress. In a prospective study of nearly 3000 men the risk of type 2 diabetes at 10 years was increased for both the UCP2-866AA (1.94 [1.18-3.19]: p=0.009) and the UCP3-55TT (2.06 [1.06-3.99]: p=0.03) homozygotes. This increased risk was not explained by the association with any measured conventional risk factors. Paradoxically, in a Europe-wide cross-sectional study of 598 subjects the UCP2-866A variant was associated with lower waist-hip ratio (GX v AA,1.00 [0.06] v 0.98 [0.07]; p=0.003), although also associated with lower insulin secretion (42.6 [24.6] v 35.6 [18.6]; p=0.03). The UCP3 variant was not significantly associated with any metabolic trait. The significant heritability of plasma markers of oxidative stress (TAS 0.54, TOAS 0.49) suggests anti-oxidant function is a plausible mechanism to determine Type 2 Diabetes risk. The predictors of anti-oxidant stress in a family study were examined, as was the impact of UCP2-UCP3 gene cluster variation. Genetic variation in the UCP2-UCP3 was found to increase the risk of the Type 2 diabetes. While UCP2 may modify insulin secretion directly, the mechanism of action for UCP3 is likely to involve novel risk factors for Type 2 Diabetes such as modification of mitochondrial oxidative stress. Finally, the development of a human model is described to examine genetic influences on oxidative stress burden using a meal rich in used cooking oil

The use of a genetic strategy to study the role of modulation of oxidative stress by uncoupling proteins 2 and 3 in the pathogenesis of Type 2 Diabetes.

Mitochondrial dysfunction has been implicated in the early pathogenesis of Type 2 Diabetes. The uncoupling proteins 2 and 3 are mitochondrial proteins found in man that have been implicated in protecting mammals from the effects of over-nutrition. Examination of the effect of genetic variation in the UCP2-UCP3 genetic cluster has so far been inconclusive. The aim of this thesis was to examine, using a genetic strategy, the hypothesis that the role of the uncoupling proteins 2 and 3 in the pathogenesis of Type 2 Diabetes is via modification of oxidative stress. In a prospective study of nearly 3000 men the risk of type 2 diabetes at 10 years was increased for both the UCP2-866AA (1.94 [1.18-3.19]: p=0.009) and the UCP3-55TT (2.06 [1.06-3.99]: p=0.03) homozygotes. This increased risk was not explained by the association with any measured conventional risk factors. Paradoxically, in a Europe-wide cross-sectional study of 598 subjects the UCP2-866A variant was associated with lower waist-hip ratio (GX v AA,1.00 [0.06] v 0.98 [0.07]; p=0.003), although also associated with lower insulin secretion (42.6 [24.6] v 35.6 [18.6]; p=0.03). The UCP3 variant was not significantly associated with any metabolic trait. The significant heritability of plasma markers of oxidative stress (TAS 0.54, TOAS 0.49) suggests anti-oxidant function is a plausible mechanism to determine Type 2 Diabetes risk. The predictors of anti-oxidant stress in a family study were examined, as was the impact of UCP2-UCP3 gene cluster variation. Genetic variation in the UCP2-UCP3 was found to increase the risk of the Type 2 diabetes. While UCP2 may modify insulin secretion directly, the mechanism of action for UCP3 is likely to involve novel risk factors for Type 2 Diabetes such as modification of mitochondrial oxidative stress. Finally, the development of a human model is described to examine genetic influences on oxidative stress burden using a meal rich in used cooking oil.