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Research background: Chronic obstructive pulmonary disease is a disease that the etiological factor and pathogenesis are uncertain entirely, and it is a preventable, treatable disease currently. Smoking is one of the amongst major risk factors for the development of COPD. Genetic susceptibility, infection, occupational environment, air pollution and socio-economic status are also risk factors. However, only 10-20% of chronic heavy smokers develop symptomatic COPD, which indicates that a difference in susceptibility to tobacco smoke injury must exist and may be related to genetic factors. With the deepening of molecular biology, it has been elucidated that such a complex gene disease as COPD exist the phenomenon of microsatellite DNA, single nucleotide polymorphism, etc. These genetic polymorphisms cause changes in the structure of protein, altered the gene expression levels or mRNA stability that the modified, and thus leading to a decline in lung function and cause lung damage. At present, the protease-antiprotease balance and the oxidant-antioxidant balance raised widespread attention, in addition to the pathogenesis mechanism of airway inflammation of COPD was generally accepted. Nevertheless, researchers have found these balance were the changes of phenotype of genetic material, and the underlying reason was gene polymorphism and gene mutation. Because genetic polymorphism has obvious ethnic differences, different races have different role in gene - environment interaction model.Therefore, it is so significant that carrying out the study of disease caused by genetic polymorphism and environmental effects in our country population. Objective: To explore the association of genetic polymorphism of superoxide dismutase and chronic obstructive pulmonary disease. The aim is to further reveal genetic susceptible factor and the pathogenesis of chronic obstructive pulmonary disease, and to improve awareness,diagnosis and treatment of COPD.Methods: 80 patients with COPD (the COPD group), 80 chronic smokers with near normal lung function (the resistant smokers group) and 40 healthy volunteers (the control group) were enrolled in this study. Limosis peripheral blood was taken and whole blood corpuscle genomic DNA was extracted. The genetic polymorphism of SOD1-3 genes was determined by ligase detection reaction and polymerase chain reaction (LDR-PCR) and serum SOD3 concentration was measured using ELISA.Results: (1)The AA,AC genotype of SOD1, TC, TT and CC genotype of SOD2, and CC, CG genotype of SOD3 were detected in selected objects,but CC genotype of SOD1 and GG genotype of SOD3 were not discovered among three groups.(2) the frequency of distribution of SOD1 AA,AC genotype among the COPD group , the resistant smokers group and the control group were(91%,93%,90%) and (9%,7%,10%) respectively, and TT, TC, CC genotype of SOD2 were(68%,65%,58%),(21%,25%,30%) and (11%,10%12%),but there were no significant difference (P >0.05). the frequency of distribution of SOD3 CC,CG genotype among the three groups were(98%,88%,98%) and (2%,12%,2%), resistant smokers had a significantly higher CG genotype frequency than subjects in the other two groups, the difference was significant (P<0.05). (3) The serum SOD3 concentration of SOD3CG genotype carriers was 252.1±46.6 U/ml, and 45.5±23.2 U/ml with noncarriers. moreover, the serum SOD3 concentration of SOD3CG genotype carriers was increased more than 5-fold compared with noncarriers, the difference was significant between the two groups (P<0.05). (4) The serum SOD3 concentration of the COPD group was 60.3±28.2U/ml,and 57.9±27.5 U/ml was found in resistant smokers, the COPD group was slightly higher than the resistant smokers group, but with no significant(P>0.05).Conclusions: (1) There were no difference among three groups for the SOD1, SOD2 polymorphisms tested(P>0.05). (2) Significantly higher frequencies of the CG genotype of the 213 SOD3 polymorphism were found in resistant smokers than in those with COPD and healthy volunteers(P<0.05). (3) The concentration of SOD3 in the serum of SOD3 heterozygous carriers was increased more than 5-fold compared with noncarriers(P<0.05). (4) The serum SOD3 concentration of the COPD group was slightly higher than the resistant smokers group(P>0.05).
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