Manganese superoxide dismutase polymorphism affects the oxidized low-density lipoprotein-induced apoptosis of macrophages and coronary artery disease.

AIMS: Oxidative damage promotes atherosclerosis. Manganese superoxide dismutase (MnSOD) is an antioxidant enzyme localized in mitochondria. We investigated the associations of the MnSOD polymorphism (valine-to-alanine in the mitochondrial-targeting domain) with its activity in leukocytes, with macrophage apoptosis by oxidized low-density lipoprotein (oxLDL), and with coronary artery disease (CAD). METHODS AND RESULTS: Blood samples were taken from 50 healthy subjects. The mitochondrial MnSOD activities in leukocytes were 542.4 +/- 71.6 U/mg protein (alanine/alanine, n = 2), 302.0 +/- 94.9 U/mg protein (alanine/valine, n = 12), and 134.0 +/- 67.1 U/mg protein (valine/valine, n = 36; P < 0.0001 for non-valine/valine vs. valine/valine). Macrophages were treated with oxLDL. After incubation, the percentages of apoptotic macrophages were 48.6 +/- 3.6% (alanine/alanine), 78.6 +/- 9.8% (alanine/valine), and 87.5 +/- 7.0% (valine/valine) (P < 0.0001, non-valine/valine vs. valine/valine). The association of the MnSOD polymorphism with CAD was investigated using blood samples collected from 498 CAD patients and 627 healthy subjects; the alanine allele was found to reduce the risk of CAD and acute myocardial infarction (AMI). CONCLUSION: Our data indicate that the alanine variant of signal peptide increases the mitochondrial MnSOD activity, protects macrophages against the oxLDL-induced apoptosis, and reduces the risk of CAD and AMI.

Association of eNOS Glu298Asp polymorphism with end-stage renal disease.

Nitric oxide (NO) derived from endothelial cells is profoundly related to the maintenance of physiological vascular tone. Impairment of endothelial NO generation brought about by gene polymorphism is considered the major deterioration factor for progressive renal disease, including diabetic nephropathy. The present study aimed to elucidate the Glu298Asp polymorphism of endothelial NO synthase (eNOS) in patients with end-stage renal disease (ESRD) and its role as a predisposing factor for cardiovascular complications. Glu298Asp in exon 7 of the eNOS gene was determined by polymerase chain reaction, followed by restriction fragment length polymorphism analysis, in ESRD patients (n=185) and compared with that of unrelated healthy individuals (n=304). The occurrence of 298Asp was significantly higher in the ESRD group (P=0.0020; odds ratio [OR] 1.65; 95% confidential interval [CI]: 1.21 to 2.25). In this group, 72 patients had type 2 diabetes mellitus (DM). Although 298Asp did not reach a significant level in the non-DM ESRD subgroup, the occurrence of 298Asp was significantly higher in DM-derived ESRD patients (P=0.0010; OR 2.02; 95% CI: 1.37 to 3.07). The functional effect of the Glu298Asp was examined using Chinese hamster ovary (CHO) cells stably overexpressing either 1917G or 1917T. NO-selective electrode measurements and fluorometric nitrite assay revealed a statistically significant difference in NO production or nitrite accumulation between CHO 1917G and 1917T (P<0.01). These data indicated that Glu298Asp is the predisposing factor in ESRD, especially DM-derived ESRD. The functional difference in NO generation depending on eNOS with either glutamate or aspartate at position 298 was also confirmed in vitro.