Association Analysis Of IL-12B Gene And ADAM33 Gene Polymorphisms With Chronic Obstructive Pulmonary Disease In Shandong Han Population

[Background]Interleukin-12(IL-12) gene which is mainly expressed by the antigen-presenting cells(such as monocytes and macrophages,dendritic cells) and B cells is an important proinflammatory cytokines.The molecular weight is 70KD,composed of 40KD(p40) and 35KD(p35) polypeptide chain.Recent studies have found that regulation of IFN-γmay induce cell chemokine(CXCL10) expression,stimulate MMP-12 generation,inhibit the secretion of leukocyte protease inhibitor,and promote the process of airway inflammation in chronic obstructive pulmonary disease(COPD) and the process of emphysema.We also know that IFN-γcan promote IL-12 production through the positive feedback, and it has a synergistic effect in regulating the differentiation of Th subsets,IL-12B gene is located at chromosome 5q31-q33,encoding p40,a total length of 16kb.Some studies have found that it has association with certain respiratory diseases.ADAM33 is a one of the disintegrin - metalloproteinase(ADAM) family members which has been found in recently years.ADAM33 gene is located in the No.20 on the short arm of chromosome 13-bit(20 p13).It mainly relates to airway epithelial cell repair and it mainly expresses on the pulmonary smooth muscle cells,myofibroblast cells and fibroblasts.In airway epithelial cells,inflammatory cells and immune cells,it does not express.When the gene activity changed may cause airway smooth muscle cells and fibroblast function,so the ADAM33 gene may be associated with small airway remodeling and hyperresponsiveness and inflammation.Therefore,IL-12B gene and ADAM33 gene may play an important role on the occurrence and development of COPD,but the association between polymorphisms of these genes and chronic obstructive pulmonary disease in the Chinese Han population from Shandong province hasn't been well studied until now.[Objective]Using case-control study,we intend to determine the association between the single nuclear polymorphisms(SNPs) and susceptibility of the 1188A/C in interleukin 12B gene and the T1 in ADAM33 gene of chronic obstructive pulmonary disease(COPD) in the Chinese Han population from Shandong province.[Methods]1.Collect blood samples from COPD patients and healthy controls in the Chinese Han population and then extract DNA from the white blood cells in peripheral blood.2.Genotyping:SNPs 1188A/C of IL-12B gene and T1 A/G of ADAM33 gene were detected by polymerase chain reaction(PCR) based restriction fragment length polymorphism(RFLP) technique in COPD subjects and healthy controls.3.Evaluate each polymorphism for Hardy - Weinberg equilibrium(HWE) using chi-square test and make sure all the genotypic and allele results were at Hardy-Weinberg equilibrium in both COPD patients and healthy controls used in the study. 4.Compare the distribution of different genotypes and alleles of every polymorphism in the two groups using chi-square test to determine whether the polymorphisms were associated with COPD.[Results]1.The frequencies of genotypes AA,AC,CC at polymorphism sites 1188A/C were 0.3333,0.4784 and 0.1883 respectively in COPD group,while 0.3573,0.4756 and 0.1671 in control group.Resides,the A type allele frequencies were 0.5725 and 0.5951 in patients and controls respectively, and the C type allele frequencies were 0.4275 and 0.4049 in COPD patients and healthy controls.There was no significant difference in genotype frequencies(P value=0.689) or allele frequencies(P value=0.389).2.ADAM33 gene was genetically polymorphic in Chinese Han population and was in Hardy-Weinberg equilibrium in both groups.Neither genotype nor allele distribution was statistically different between COPD patients and healthy controls(P=0.117,P=0.090).[Conclusions]1.No significant association was found between IL-12B 1188A/C polymorphism and COPD susceptibility in Chinese Han population from Shandong province.But the probability that other polymorphisms in IL-12B might be associated with COPD couldn't be excluded.2.T1 in ADAM33 gene was not associated with COPD in Chinese Han population from Shandong province.But the probability that other polymorphisms in ADAM33 might be associated with COPD couldn't be excluded.