Association Study Of MicroRNA-146a Gene Polymorphism With Susceptibility To Rheumatoid Arthritis

ObjectiveThe relationship between microRNA-146a(miR-146a)single nucleotide gene polymorphism(SNP)and rheumatoid arthritis is still unclear.Considering that only the association between miR-146a gene region SNP rs29101064 and rheumatoid arthritis was reported,we speculate that the previous studies may have omitted the genetic association signals of multiple loci.The aim of this study was to systematically evaluate the association between miR-146a gene polymorphism and RA risk using data from previous genome-wide association studies(GWASs)and a new Chinese population replication study,and to provide evidence for exploring the etiology of RA.MethodsWe extracted the available data of miR-146a from the three previous GWASs(European GWAS,Japanese and Korean GWAS,and Chinese GWAS).Then we performed an independent Anhui replication cohort.The data of RA patients were collected from two hospitals in Anhui province according to the 1987 American College of Rheumatology(ACR)standard.We collect the laboratory data and venous blood samples of the subjects under the principle of obtaining the informed consent of the subjects.Then we extracted DNA and plasma samples from the venous blood samples.SNPscan technology(Genesky Biotechnologies Inc.,Shanghai,China)was used to genotyped the selected SNP of rs2431697 in replication cohort.Quality control was carried out by Hardy-Weinberg equilibrium test.We performed association analysis for the Anhui replication cohort based on an additive model using PLINK 1.07.We compared the relationship between miR-146a gene polymorphism and RA susceptibility.Besides,differences in genotype frequency and allele frequency of SNP rs2431697 between laboratory parameters positive and negative cases were also be studied.In order to verify the reliability of the results,the data of the previous 3 GWASs were combined with the data of Anhui replication cohort for meta-analysis by ethnic group,and the heterogeneity test also conducted to test the magnitude of heterogeneity.We evaluate the functionally annotate of the leading SNP and its surrounding related SNPs(R~2>0.8in the Asian sample)and analyze the overlap of the SNP with epigenetic markers.In addition,plasma levels of four pro-inflammatory cytokines(TNF-ɑ,IL-6,IL-17A,and IFN-ɑ)were quantified using the Human Luminex Screening Test in 201 genotypes of healthy controls to estimated the association between number of RA risk alleles and plasma levels of these cytokines.Possible confounding factors were included as covariates in the regression model,including gender,age and test batches.ResultsData extracted from the previous three GWASs showed that among the selected SNPs,only SNP rs2431697 was significantly correlated with RA in each GWAS(P<0.05).Allele C of SNP rs2910164 and allele G of SNP rs57095329 may be associated with an increased risk of RA in European populations,but the results of these two alleles did not reach a significant value in Asian populations(P>0.05).The results of Anhui replication cohort were consistent with the above discovery cohort.The genotype frequency of rs2431697(c~2=444.52,P<0.001)and allele frequency[OR=1.24(1.06,1.46),P=8.69E-03]were significantly different between the case group and the control group.However,no association was found between the genotype and allele frequency of this SNP with anti-CCP antibody(ACPA),rheumatoid factor(RF)and anti-keratin antibody(AKA)(P>0.05).In addition,the results of the meta analysis showed that SNP rs2431697 was significantly correlated with RA in the trans-ethnic population[OR=1.07(1.04,1.10),P=1.79E-06]and Asian population[OR=1.15(1.09,1.22),P=4.37E-07].However,the effect size in Asian population was larger than that in European population,and there was greater heterogeneity across ethnic groups,while there was no significant heterogeneity in Asian population.Haploreg functional annotation suggests that rs2431697 overlaps with multiple epigenetic markers of immune system histone labeled cells.Cytokine analysis showed that the risk allele T of rs2431697 was only negatively correlated with plasma TNF-ɑlevels in healthy controls(P=0.016).ConclusionOur research supported that SNP rs2431697 in the miR-146a gene region is associated with RA susceptibility.More importantly,this study found that the effect size of the selected SNPs was significantly larger in Asians than in Europeans,suggesting that the role of rs2431697 is somewhat ethnically different.Further independent studies in different ethnic groups are needed to determine the exact role of this gene in RA pathogenesis.The specific mechanism of this SNP in RA pathogenesis also needs to be further studied.