Interaction Of Single Nucleotide Polymorphisms In ORMDL3 Gene And Risk Factors Of Childhood Asthma Impact On Childhood Asthma

BACKGROUNDChildhood asthma is one of the chronic diseases in pediatric system, despite the current domestic and foreign health level has been improved, but the study shows the world within the scope of children asthma disease incidence is increasing year by year, causing a huge burden on the family and the society. Currently, the cause and the pathogenesis of asthma has been a hot research all over the world.Asthma is induced of complex gene- gene and gene- environment correlation. So far, the candidate genes associated with asthma were more than 200,43 genes in which has been successfully verify in repetitive independent experimental in many populations. Oresomueo id 1-like protein 3 is a new candidate gene of asthma found by Moffatt for the first time in a genome-wide association study in 2007. A number of research showed that the ORMDL3 gene is the most sufficient evidence of gene associated with asthma so far, but the pathogenesis is not clear. It is generally believed that ORMDL3 gene single nucleotide polymorphism (SNP) loci in regulation of ORMDL3 gene expression level, thus affecting the occurrence of asthma. The relationship between ORMDL3 and asthma has been confirmed in multiple independent duplication study of multiple individual species, but the existence of racial and ethnic differences of asthma susceptibility gene, which makes asthma related gene locus were found in a population may not associated with asthma in other populations. Research has found that the ORMDL3 gene is located near SNP on rs7216389 is most strongly related markers of asthma, this loci have been confirmed in a number of races, regions, such as in German, Scotland, Mexican, Puerto Rican, Japanese, Australians and other different races, but in Mexico children and American black children was ORMDL3 gene SNP rs12603332,rs 4378650. Chinese scholars in the study of the correlation between ORMDL3 gene and Han asthma, genotyping SNP rs12603332 and rs7216389, to detect the expression of two loci in peripheral blood of normal individuals and patients, confirmed that the regulation of ORMDL3 gene SNP loci expression levels SNP loci may be the true susceptibility loci, but because these two sites are in strong linkage disequilibrium, still can not determine which sites are truly functional sites. In addition, China’s Hong Kong Han children ORMDL3 gene SNP rs4378650 was considered only a marginal associated with childhood asthma. And how the Guangdong region, there is no research. We chose the ORMDL3 gene 2 SNP loci rs12603332, rs4378650 polymorphism analysis of the Guangdong region may have significant gains in childhood asthma.2009 Global Initiative for Asthma (GINA) pointed out that the main factors affecting childhood asthma were family history of asthma, respiratory viral infections, atopy, smoking during pregnancy and so on, but because of the different environment factors, the incidence of childhood asthma have different risk factors around rates. In many studies, family history of asthma is the most important risk factors, parents are suffering from asthma, the chance of their children suffer from asthma are 10 times than healthy children, one parent with asthma, their children were 2 to 5 times higher risk of illness than healthy children. Reveals asthma susceptibility genes are more likely to lead to asthma than other risk factors. Epidemiological survey shows that more than 50% of asthma cases have a history of allergies, the risk of suffering from allergic diseases of asthma increased by 30%, family history of allergies was one of the major risk factors in asthma. In addition, parents allergy symptoms will increase the risk of respiratory infections and asthma in children. Research shows that asthmatic children who with atopic family history accounted for 32.6%, which suggesting that rhinitis, eczema and other atopic diseases are also risk factors for asthma.Breastfeeding is a risk factor for children or protective factors remains controversial, an overseas birth cohort study has confirmed that breastfeeding in a significant genetic family history of asthmatic children has an important protective role. And also studies show that breastfeeding may increases the risk of children suffering from post-atopic asthma, this impact is particularly significant in mother atopic constitution. Mother smoking during pregnancy is another major risk factor for childhood asthma, exposure to tobacco can affect fetal airways, make the baby born with a narrow airway and lung function decreased. Some food allergens such as milk, eggs, fish were absorpt in the gastrointestinal tract, the allergen epitopes cause the release of inflammatory mediators, absorption and direct effect on bronchial and induced asthma. Respiratory viral infections was the most important incentive of 1-3 years old children with asthma, respiratory viral infections damage airway epithelial integrity, increase its permeability, resulting in increased sensitivity to the allergen, which make the airway β2 receptor excitability down, destroy M2 cholinergic receptor function and increased the reactivity of cholinergic nerve. By affecting various inflammatory cytokines, a variety of cell surface molecules involved in regulating the pathogenesis of bronchial asthma.Japanese research team has reported that after respiratory viral infections, ORMDL3 gene expression was significantly higher in vivo. Recent research results show that the chromosome 17 gene polymorphisms closely associated with rhinovirus-induced in childhood asthma, and after nasal virus infection in children, ORMDL3 gene expression levels were significantly elevated in peripheral blood mononuclear cells. Shows that respiratory viral infections regulate the expression levels of the gene ORMDL3.Foreign literature shows that ORMDL3 can cause a series of inflammatory response, leading to asthma, were further explained the asthma susceptibility gene interaction with respiratory viral infections could induce asthma. This conclusion is good for asthma susceptibility gene carriers daily care and provides a theoretical basis for prevention of asthma.In 1997, foreign scholars confirmed the occurrence and development of asthma was closely related to an increase of multi-unsaturated fatty acids (PUFAs) as well as a reduce in the consumption of saturated fatty acids, proposed that 6 polyunsaturated fatty acids play an important role in the regulation of immune responses and inflammatory reactions. Subsequently, many scholars began to study the relationship between lipids and asthma. Studies have shown that phospholipase A2 (PLA2) was hydrolyzed to give arachidonic acid (AA) and lysophosphatidylcholine (Lyso-PC) on the cell membrane. AA as an enhancement of inflammatory mediators before vascular and bronchial lipid formation. Lyso-PC not only can lead to lung damage, increased capillary permeability, alter pulmonary surfactant, induced mast cell secretion and increased airway hyperresponsiveness but also can reduce the sensitivity of the bronchial smooth muscle β-adrenergic. In addition, Lyso-PC can enhance cytokine-induced expression of interferon-y expression in human T lymphocytes as well as growth factor gene in endothelial cells. Recent research about cardiovascular disease reports indicate that apolipoprotein changes in inflammatory diseases are more sensitive than plasma lipid. Lipid transport system is divided into two subclasses:apolipoproteinβ (apo β) system, including very low density lipoprotein (VLDL), intermediate density lipoprotein and low density lipoprotein cholesterol; Apolipoprotein AI (apoAI) systems, including high-density lipoprotein (HDL-C). Apo β by inhibiting endogenous fibrinolysis and stimulate cytokine production and inflammation to enhance fibrinolytic system, apo β was related with non-asthmatic and allergic inflammation.OBJECTIVE1、To find out risk factors related to childhood asthma in Guangdong region by multivariate questionnaire.2、To understand the characteristics of ORMDL3 gene polymorphisms Guangdong Han asthmatic children and to investigate the interaction between ORMDL3 gene polymorphisms and asthma risk factors.3、To analysis the relationship between lipid indicators (lysolecithin,β-apolipoproteins) and ORMDL3 genotype in asthmatic children. To investigate whether the ORMDL3 gene impact on lipid metabolism process thus contributing to the pathogenesis of asthma, and to determine the possible mechanism of ORMDL3 gene in the pathogenesis of asthma.METHODSIt is a multi-center, large, prospective case-control study.598 children were selected from Guangdong area (300 cases in asthma group 300 cases,298 cases in control group).1、To guide parents of children fill in childhood asthma questionnaires and collect data.2、Extract all subjects’blood to extract genomic DNA and to test lysolecithin, β-apolipoprotein levels;①、Genotyping SNP by TaqMan (Applied Biosystems) probe.②、Lysolecithin and β-apolipoprotein levels were detected by enzyme-linked immunosorbent assay (ELISA).3、Using the chi-square test to compare the difference between the genotype and allele in two groups.4、Using multi logistic regression analysis to explore the interaction of ORMDL3 gene polymorphisms and asthma-related factors on childhood asthma.5、Using t-test to analysis Lysolecithin and β-apolipoprotein levels between asthma and control groups, Using analysis of variance compare the differences between genotypes of lipid metabolism.RESULTS1、There was a relationship between ORMDL3 gene SNP rs 12603332 and childhood asthma in a Guangdong population, SNP rs 4378650 was not related to childhood asthma.ORMDL3 gene SNP rs12603332 CC genotype was advantage in asthmatic children.2、ORMDL3 gene SNP rs12603332 CC genotype was significantly associated with family history(P=0.007, OR=1.845,95%CI=1.178-2.889) and respiratory virus infection(P=0.007, OR=1.976,95%CI=1.206-3.235).3、ORMDL3 gene SNP rs12603332 CC genotype, CT genotype and TT genotype had interactive effect with family history, OR=22.644,95%CI=9.390-54.606, OR=33.500,95%CI=7.839-143.157, OR=11.16795%CI=1.319-94.559, respectively.4、ORMDL3 gene SNP rs12603332 CC genotype, CT genotype and TT genotype had interactive effect with respiratory virus infection, OR=32.476 95%CI=9.875-106.805, OR=12.667　95%CI=3.699-43.375, OR=7.917 95%CI=0.909-68.945, respectively.5、There was higher Lysolecithin and β-apolipoprotein concentration in asthmatic children. Lysolecithin and β-apolipoprotein concentration of CC genotype was significantly higher than the other genotypes.CONCLUSION1、ORMDL3 gene SNP rs12603332 locus may be associated with childhood asthma in Guangdong area.ORMDL3 gene SNP rs4378650 are not related to childhood asthma in Guangdong area.2、ORMDL3 gene SNP rs12603332 CC genotype is a risk factor of childhood asthma in Guangdong area. There are no significant correlation between CT genotype, TT genotype and childhood asthma.3、ORMDL3 gene SNP rs12603332 CC genotype frequencies appear higher in asthmatic children who with family history of asthma. The children who had ORMDL3 gene SNP rs12603332 CC genotype were easily attacked by virus.4、Compared with other asthma risk factors, SNP rs12603332 and family history of asthma or SNP rs12603332 and respiratory virus infection are more likely to contribute to childhood asthma in Guangdong population.5、There was higher Lysolecithin and β-apolipoprotein concentration in asthmatic children. Indicating Lysolecithin and β-apolipoprotein may intervene in the pathological process of asthma.6、Lysolecithin and β-apolipoprotein concentration of CC genotype was significantly higher than the other genotypes. Indicating high Lysolecithin and β-apolipoprotein concentration may be associated with pro-inflammatory gene ORMDL3 SNP rs 12603332 jointly lead to the occurrence of childhood asthma.