The Significance Of MiR-146a And IRAK1Polymorphisms, MiR-146a Expression In Rheumatoid Arthritis

Objective Studies have shown that defective negative regulation of TRAF6(TNFreceptor-associated factor6) or IRAK1(IL-1receptor-associated kinase1) by theincreased miR-146a in peripheral blood mononuclear cells (PBMCs) with RA patients isthe cause of prolonged TNF-α production. A G>C polymorphism (rs2910164) which islocated in the sequence of miR-146a precursor, results in a change from a G: U pair to aC: U mismatch in its stem region. To explore the association of miRNA-146a variantrs2910164and of two IRAK1polymorphisms rs3027898(in the3’-untranslated region)and rs1059703(exon12: Ser532Leu) with RA in South-central Chinese Han population;and investigate the association between miR-146a polymorphism and miR-146aexpression, and analyze the relationship between miR-146a expression and clinicalcharacteristics in RA patients.Methods Three single-nucleotide polymorphisms (SNPs), Pre-miR-146a/rs2910164,IRAK1/rs3027898, and IRAK1/1059703were genotyped in188Han Chinese patientswith RA and220healthy controls using the polymerase chain reaction–ligationdetection reaction (PCR-LDR) method. Expression of miR-146a in PBMCs was studiedusing quantitative real-time polymerase chain reaction (qRT-PCR) in68RA patients,10OA patients and20healthy controls. After receiving the therapy of Glucocorticoid andNSAIDs combined with DMARDs for three months in10active patients with RA,miR-146a expression was again analyzed by qRT-PCR. Clinical characteristicsincluding age, gender, disease duration, age at onset, tender joint count(TJC), swollen joint count (SJC), joint functional classification, bone erosion stage, VAS score, HAQscore, CRP, ESR, DAS28score, RF titer and anti-CCP antibody titer were taken intoaccount. According to DAS28score, patients were divided into less active group(DAS28≤3.2) and active group (DAS28>3.2). The patients of active group were dividedinto moderately active group (3.2<DAS28≤5.1) and very active group (DAS28>5.1).According to X-ray stage of bone erosion, patients were divided into mild bone erosiongroup (X-ray≤II stage) and severe bone erosion group (X-ray> II stage).Results①No significant association was found between RA and Pre-miR-146ars2910164and IRAK1rs3027898/rs1059703genotype distribution (P=0.808,0.986and0.395, respectively) and allele frequency (P=0.998,0.981and0.569, respectively).②When stratified by negative or positive of RF and anti-CCP, genotype distribution(P>0.05for each) and allele frequency (P>0.05for each) of the three SNPs were alsonot correlated with RA in four groups.③No significant relationship was observedbetween Pre-miR-146a rs2910164and IRAK1rs3027898/rs1059703genotypedistribution and sex, age at onset, status of RF and anti-CCP, RA activity(excludingrs3027898) and severe bone erosion in RA patients (P>0.05for each).④The patientswith rs3027898CC genotype had more RA activity (DAS28>3.2) as compared to thepatients with rs3027898AC+AA genotype (P=0.024). The patients with rs3027898CCgenotypes had a2.692-fold a higher probability for disease activity as compared to thepatients with rs3027898AC+AA genotype (P=0.025, OR=2.692,95%CI=1.136~6.380).⑤No significant association were observed between rs2910164genotypes andmiR-146a expression in RA patients and healthy controls, respectively (P>0.05foreach).⑥MiR-146a expression was significantly higher in patients with RA than inthose with OA and in healthy controls (P=0.006and0.000, respectively) but did notdiffer between the latter two groups (P=0.823).⑦MiR-146a expression wassignificantly increased in very active group and moderately active group compared with less active group(DAS28≤3.2)(P=0.000and0.010, respectively); in the RA patients,very active group had the higher expression of miR-146a than moderately active group(P=0.004). Moreover, miR-146a expression did not differ between less active group andhealthy controls (P=0.879).⑧MiR-146a expression was significantly lower in activepatients with RA receiving formal treatment for three months (P=0.003).⑨Nosignificant differences were detected in miRNA-146a expression of RA patientsbetween male and female groups, disease duration≤2years and>2years groups, boneerosion≤II stage and> II stage groups, RF negative and positive groups, and anti-CCPantibody negative and positive groups, respectively (P>0.05for each).⑩MiR-146aexpression positively correlated TJC, STJ, VAS score, ESR, CRP and DAS28score(r=0.529, r=0.412, r=0.523, r=0.493, r=0.323, r=0.551; each P<0.01). No significantassociations were found between miR-146a expression and age, disease duration, age ofonset, joint functional classification, X-ray stage, HAQ score, RF titer and anti-CCPantibody titer (r=0.114, r=0.006, r=0.116, r=0.045, r=0.033, r=0.162, r=0.096, r=-1.31;each P>0.05).Conclusion The SNPs of the Pre-miR-146a/rs2910164and IRAK1rs3027898/1059703are not correlated with susceptibility to RA in South-central Chinese Han population.The polymorphism of the rs3027898could be a genetic risk factor for RA activity. Nosignificant significant association is observed between rs2910164genotypes andmiR-146a expression in RA patients and healthy controls. MiR-146a expression isupregulated in patients with RA, and associated with the level of RA disease activity.