Functional effects of NAD(P)H oxidase p22 phox C242T mutation in human leukocytes and association with thrombotic cerebral infarction

Abstract

Background: Previous study showed that polymorphism of the NAD(P)H oxidase p22 phox gene is associated with atherosclerosis, although others could not confirm such association. We investigated the association between p22 phox C242T polymorphism and thrombotic cerebral infarction and the role of this polymorphism on superoxide-production activity in human neutrophils and promyelocytic HL-60 cells as a model system. Methods: PCR-RFLP analysis revealed that genotype and allele frequencies of C242T polymorphism in 120 patients with thrombotic cerebral infarction and 177 control subjects. The superoxide-production activity in neutrophils was determined by cytochrome c reduction assay. To clarify the role of p22 phox C242T polymorphism on NAD(P)H oxidase activity, we used transgenic HL-60 cells transfected with expression plasmids carrying p22 phox cDNAs with or without C242T polymorphism. Results: Genotype and allele frequencies of C242T polymorphism in patients and control subjects were not significantly different. The superoxide-production activity in neutrophils with T allele was higher than in neutrophils without T allele. Moreover, expression analysis showed that superoxide-production activity in p22 phox C242T-expressing HL-60 cells were significantly higher than in p22 phox-expressing HL-60 cells. Conclusions: We conclude that C242T of p22 phox gene is not involved in thrombotic cerebral infarction but more likely in increased NAD(P)H oxidase activity in phagocytes.