Effect Of Interaction Between Shift Work And RAAS Gene Polymorphism On Essential Hypertension In Coal Workers

ObjectivesEssential hypertension (EH) is a complex disease caused by genetic andenvironmental factors. We should explore mechanism of EH combined genetic factorswith environmental factors, for which the interaction between genetic factors andenvironmental factors plays an important role in the pathogenesis of EH. Therenin-angiotensin-aldosterone system (RAAS), which can regulate blood volume andblood pressure levels, is important for the pathogenesis and pathology ofcardiovascular disease, therefore the gene from RAAS maybe important candidategenes of hypertension. Shift work as a potential risk factor is likely to causecardiovascular disease and other chronic diseases. A case-control study based on coalworkers was designed to analyze the relationship among gene polymorphisms, shiftwork and EH, the interaction of gene-environmental was analyzed too.Methods1Choice of objectA case-control study was adopted.1048coal workers, who acceptedoccupational health examination were chosen to participate in this study.2Field epidemiological investigationDesign occupational epidemiology questionnaire, face-to-face interview wasconducted. The survey contents including demographic data, occupational history,family history, personal history (smoking, drinking, etc), as well as eating habits, etc.;measuring height, weight, blood pressure and other physical examination.3Laboratory test5ml venous blood were extracted in early morning, some used for the detectionof biochemical indicators including blood glucose (GLU), uric acid (UA),triglycerides (TG), total cholesterol (TC), high-density lipoprotein (HDLC), lowdensity lipoprotein (LDLC), C-reactive protein (CRP) and so on. Separate whiteblood cells with hyptonic method, and genomic DNA were extracted with phenol-chloroform methods. Polymerase chain reaction (PCR) was used to detectpolymorphism of insertion/deletion (I/D) polymorphism of angiotensin-convertingenzyme (ACE). The polymorphisms of AGT-M235T, AT1R-A1166C andCYP11B2-344T/C gene were detected by polymerase chain reaction-restrictionfragment length polymorphism (PCR-RFLP).4Statistical AnalysisDatabase was established with Epi-data3.0, SPSS16.0, SAS8.0and MDR2.0statistical analysis software were used for data analysis. The measurement data wereexpressed as x±s, t test or ANOVAS were used to compare the difference betweengroups.The χ²test were used to analyze whether distribution of genotype in accordancewith Hardy-Weinberg genetic equilibrium or not; and compared the distribution ofgenotype and allele between case and control groups; Univariate analysis analyzed therelationship of environmental factors and gene polymorphism with essentialhypertension risk. Using stratifies analysis and multivariate analysis methodsanalyzed the relationship between interaction of genes-genes, environment-genewith EH.Test level of α=0.05, P <0.05expressed the difference was statisticallysignificant.Results1Environmental factors with EHUnivariate analysis demonstrated that overweight or obese increased the risk ofEH2.14(95%CI:1.67².74) times; family history of hypertension increased therisk of EH1.49(95%CI:1.14¹.94) times; shift work increase the risk of EH1.45(95%CI:1.12¹.86) times; participate in regular physical exercise increased the riskof suffering from EH0.64(95%CI:0.49⁰.84) times compared with not participatein physical exercise; snorers with the risk of EH was1.28(95%CI:1.09¹.51) timescompared with not snorers, and the difference was statistically significant (P <0.05).Much more salt intake is likely to increase the risk of EH of1.20(95%CI:1.04¹.39) times, but eat more coarse grains, vegetables, fruits may reduce the risk of EH.There was significant difference of GLU, UA, TG, TC, HDLC and LDLC levelbetween case group and control group.With multivariate analysis, BMI≥24kg/m², family history of hypertension, shift work, blood glucose, TC/HDLC≥4.5, LDLC≥2.7mmol may increase the risk ofEH of2.09(95%CI:1.59².74).1.47(95%CI:1.09¹.966),1.44(95%CI:1.09¹.90),1.45(95%CI:1.04².01),2.39(95%CI:1.69³.38) and2.18(95%CI:1.62².95) times separately, and the difference was statistically significant (P <0.05),they were risk factors of EH. Increase intake of fruit, more physical exercise mayreduced the risk of EH, and the OR (95%CI) were0.65(0.49⁰.88) and0.74(0.61⁰.91), the difference was significant (P <0.05), they were protective factors of EH.2The relationship between gene polymorphism and essential hypertensionThere were significant differences in M235T genotypes and allele frequencies ofAGT gene between cases and control group (χ²=8.92, P=0.01); the T allele frequencyin case group (62.88%) was higher than control group (57.16%), the difference wassignificant (χ²=7.16, P=0.01). However, there is not yet that M235T polymorphism ofAGT gene is related with EH (P>0.05) in multivariate analysis.The II, ID and DD genotype frequency of ACE gene in cases and control groupswere45.99%,39.31%,14.70%and49.81%,40.46%,9.73%separately, and there wasno significant difference of distribution of genotype between case and control groups(χ²=6.16, P=0.05). The allele frequency of D in case group (34.35%)was higher thancontrol group (29.96%), the difference was significant (χ²=4.63, P=0.03). Multivariateanalysis revealed that carrying DD genotype increased the risk of EH of1.73(95%CI:1.12².68) times, the difference was statistically significant (P <0.05), DD genotypeof ACE gene might be the susceptible genotypes for EH.There was significant difference in distribution of AA genotype of AT1R genebetween case and control groups(χ²=5.00, P=0.03). The distribution of alleles A andC was no significant difference between the two groups (P>0.05). Multivariateanalysis showed that the genotype that carrying C allele increase the risk of EH0.55(95%CI:0.35⁰.87) times than AA genotype, the difference was statisticallysignificant (P <0.05), which suggesting that A allele may be susceptible gene for EH.TT, TC and CC genotype frequencies of CYP11B2gene-334T/C loci in case andcontrol groups were50.76%,41.22%,8.02%and49.24%,42.56%,8.20%respectively; carrying T allele and C allele frequencies in case group were71.37%,28.63%, in control group were70.52%,29.48%, there was no significant difference ofgenotype and allele distribution in the two groups (P>0.05), and multivariate analysisconcluded that it can not be considered CYP11B2gene was related with thepathogenesis of EH. 3Analysis of interaction among genesStratify analysis method was used to analyze interaction based on the additivemodel among the genes, the results showed that there were negative interactionbetween the AGT gene and ACE gene (χ²=19.26, P=0.01); There was significantdifference of interactions between AGT gene and CYP11B2gene (χ²=16.47, P=0.04),between AGT gene and AT1R gene, between ACE gene and AT1R gene. Still, nosignificant interactions based on the additive model between ACE gene and CYP11B2gene, AT1R gene and CYP11B2gene were founded.After adjusted shift work, BMI, family history of hypertension and other factors,gene variables and their interaction terms were introduced to logistic regression modelfor the multiplicative model of interaction analysis, the results show that there was notinteraction among genes during the development of EH(P>0.05).4Interaction analysis between gene and shift workStratify analysis method was used to analyze interaction based on the additivemodel between shift work and gene, the results showed that there was negativeinteraction between shift work and AGT,ACE,AT1R genes, and the differences weresignificant (P<0.05). Shift work, genetic variables, and the interaction term wereintroduced to logistic regression model, to analyze the relationship of shift work andgene interaction based on the multiplicative model with EH, the interaction OR_intvalues of shift work and AGT,ACE,AT1R,CYP11B2genes were1.05(95%CI:0.70¹.56),0.84(95%CI:0.56¹.25),0.58(95%CI:0.23¹.47),0.81(95%CI:0.52¹.27) separately, there were not statistically significant (P>0.05), still it can notbelieve that there were interactions based on multiplicative model between shift workand each gene.5Interaction analysis between gene and family history of hypertensionStratify analysis method was used to analyze interaction based on the additivemodel between family history of hypertension and genes, it found that OR_int values ofinteraction terms between family history of hypertension and AGT, AT1R, ACE genewas1.40,1.12,0.71respectively, the difference were significantly (P<0.05); therewas no interactions between family history of hypertension and CYP11B2gene.Logistic regression analysis was used to analyze the interaction between familyhistory and gene based on multiplicative model, it can not believe that there weresignificant difference between family history of hypertension and AGT,ACE,AT1R, CYP11B2genes.6Interaction analysis between gene and BMIStratify analysis method was used to analyze interaction based on the additivemodel between BMI and genes, it concluded that there were significant difference ininteractions between BMI and AGT, ACE, AT1R, CYP11B2genes(P<0.05). Logisticregression analysis was used to analyze the relationship of interaction between BMIand genes based on multiplicative model, OR_intvalues of interaction terms betweenBMI and AGT,AT1R,CYP11B2were1.11(95%CI:0.75～1.64),0.66(95%CI:0.27～1.62),1.29(95%CI:0.84～1.99) respectively, there were no significantdifference in interactions(P>0.05). However, there was interactions between BMIand ACE gene.7Gene-environment interaction analysis with MDR methodMDR method was used to analyze gene-environment interaction, the resultsshowed that the4-factor and7-factor model were MDR interaction models of gene-environmental factors. There were interactions between shift work and BMI, fruitintake, TC/HDLC, AGT, ACE, CYP11B2gene, which can increase the risk of theincidence of EH.Conlusions1Shift work may be risk factor of EH.2The polymorphism of sequence I/D of ACE gene and A1166C of AT1R gene mightrelated with EH. DD genotype of ACE gene and AA genotype of AT1R gene may besusceptible genotype of EH.3There were interactions based on additive model between shift work and ACE geneI/D polymorphism, AT1R gene A1166C polymorphism. Still there were interactionsbetween shift work and BMI, fruit intake, TC/HDLC AGT, ACE, of CYP11B2, andwhich could increase the risk of the incidence of EH.