Relationship between human oxoguanine-DNA glycosylase-1 polymorphism and the outcome of Chinese peritoneal dialysis patients

Abstract

Human oxoguanine-DNA glycosylase 1 (hOGG1) is the enzyme that has DNA repairing capacity. C1245 G substitution of the hOGG1 gene results in reduced enzyme activity. Peritoneal dialysis (PD) is known to cause oxidative DNA damage. We investigated the effect of hOGG1 polymorphism on the clinical outcomes of PD patients. We studied the hOGG1 polymorphism in 441 new PD patients (232 men, age 56.6 ± 13.5 years). The patients were followed for 41.4 ± 18.2 months for cardiovascular events. For the entire cohort, there was no significant difference in the 5-year event-free survival between the CC and CG/GG groups (42.9% vs. 33.2%; p = 0.1). However, for patients with baseline serum C-reactive protein (CRP) levels ≤ 5.0 mg/L, 5-year event-free survival of the CC group was significantly better than that of CG/GG group (50.3% vs. 31.9%, p = 0.046). Multivariate analysis showed that hOGG1 polymorphism was an independent predictor of the survival (p = 0.008). In contrast, for patients with baseline CRP > 5.0 mg/L, there was no significant difference in 5-year event-free survival between the CC and CG/GG groups (26.7% vs. 30.2%, p = 0.9). In PD patients with no systemic inflammation, hOGG1 1245CC genotype confers a survival benefit as compared to CG or GG genotype, but the protective effect disappears in patients with systemic inflammation. Our results suggest a complex interaction between hOGG1 and inflammation in the pathogenesis of cardiovascular disease in PD patients. 人類oxoguanine-DNA glycosylase 1 (hOGG1)是一種具DNA修復能力的酵素，其酵素活動在hOGG1基因的C1245G替換後會有所下降。此外，腹膜透析(PD)已知會導致DNA的氧化性損害。本研究調查了hOGG1多態性對PD患者的影響。 研究人員對441位剛開始接受PD的病人(男232人, 年齡56.6 ± 13.5歲)，作出hOGG1多態性的調查，並對心血管事件的發生進行共41.4 ± 18.2個月的追蹤。 在整體病人中，CC與CG/GG組別之間在5年無事件存活率上無明顯差異(42.9% vs. 33.2%, p = 0.1)；然而，在基線血清C-反應蛋白(CRP)水平 ≤ 5.0 mg/L的病人中，CC組的5年無事件存活率明顯高於CG/GG組(50.3% vs. 31.9%, p = 0.046)。多變數分析顯示，hOGG1多態性是存活的獨立預測因子(p = 0.008)。相反，在基線CRP > 5.0 mg/L的病人中， CC與CG/GG組別之間在5年無事件存活率上並無明顯差異(26.7% vs. 30.2%, p = 0.9)。 在不具系統性發炎的PD患者間，相比於CG或GG基因型，hOGG1 1245CC基因型具備若干的存活效益，但其效益並未出現於系統性發炎患者間。這些結果意味著，在PD患者的心血管致病過程中，hOGG1與發炎之間存在著複雜的交互關係。