Association of rs2910164 Polymorphism in miRNA-146 and rs3746444 Polymorphism in miRNA-499 with Inflammatory Arthritis: A Meta-Analysis

Objectives The purpose of this study was to explore the association of miRNA-146 and miRNA-499 polymorphisms with inflammatory arthritis. Methods A systematic search of studies on the association of miRNA-146 and miRNA-499 polymorphisms with inflammatory arthritis susceptibility was conducted in PubMed, Web of science, Elsevier ScienceDirect, and Cochrane Library. Eventually, 18 published studies were included. The strength of association between miRNA-146/499 polymorphisms and inflammatory arthritis susceptibility was assessed by odds ratios (ORs) with its 95% confidence intervals (CIs). Results A total of 18 case-control studies, consisting of 3385 inflammatory arthritis patients and 4584 controls, were included in the meta-analysis. This meta-analysis showed significant association between miRNA-499 rs3746444 polymorphism and inflammatory arthritis susceptibility in overall population (C vs T, OR: 1.422, 95% CI= 1.159-1.745, P=0.001). Similar results were found in subgroup analysis by region. But we did not find association between miRNA-146 rs2910164 polymorphism and inflammatory arthritis susceptibility in overall population (C vs T, OR: 1.061, 95% CI= 0.933-1.207, P=0.365). Conclusions The present study indicates that miRNA-499 rs3746444 polymorphism is associated with inflammatory arthritis susceptibility. However, there is lack of association between miRNA-146 rs2910164 polymorphism and inflammatory arthritis susceptibility. But, we also find miRNA-146 rs2910164 and miRNA-499 rs3746444 polymorphism are associated with inflammatory arthritis in Middle East. Therefore, more large-scale studies are warranted to replicate our findings.


Introduction
Inflammatory arthritis is a group of complex diseases, including rheumatoid arthritis (RA), psoriatic arthritis (PsA), juvenile idiopathic arthritis (JIA), etc. And it is characterized by inflammatory cell infiltration into the joints [1,2]. There is no doubt that environmental factors and genetic factors play an important role in the development of inflammatory arthritis.
MicroRNAs (miRNAs) are small noncoding RNAs, which are about 22 nucleotides long. They play an important role in regulating transcription and translation [3][4][5][6]. Some studies indicated that they also participate in cell proliferation, differentiation, and apoptosis [7,8]. And, miRNAs can cause the degradation or translation repression of their target miRNA by binding to the 3 -untranslated region of specific mRNAs (messenger RNAs) [9][10][11][12]. Recently, some studies reported that miRNA may associate with inflammatory arthritis, such as miRNA-146 rs2910164 and miRNA-499 rs3746444. Therefore, we chose miRNA-146 rs2910164 and miRNA-499 rs3746444 to explore the association between its polymorphisms and inflammatory arthritis.
Considering the results of miRNA-146 and miRNA-499 polymorphisms with inflammatory arthritis are inconsistent [16][17][18][19][20], this discrepancy might be caused by some studies that have small sample size, low statistical power, ethnicity differences, and publication bias. It is necessary to conduct meta-analysis to explore this association.

Search Strategy.
A systematic search of studies on the association of miRNA-146 and miRNA-499 polymorphisms with inflammatory arthritis susceptibility was conducted in PubMed, Web of science, Elsevier ScienceDirect, and Cochrane Library. Keywords for the search were as follows: ("microRNA" or "miRNA" or "microRNAs") and ("Inflammatory arthritis") and ("polymorphism" or "variant" or "genotype" or "SNP" or "mutations"). All relevant studies were retrieved. We screened those studies by reading its titles, abstracts, and contents carefully.

Eligibility
Criteria. The inclusion criteria were (i) studies involving the association between miRNA gene polymorphisms and inflammatory arthritis; (ii) case-control study; (iii) studies based on human; (iv) studies providing the detailed relevant genotype data of both case group and control group. Studies were excluded if (i) the study was a review, editorial, abstract, case report, or unpublished article; (ii) studies were nonhuman studies or animal experiments or cell experiments; (iii) studies had no controls or no detailed relevant genotype data.

Data Extraction.
The data of the eligible studies were extracted by one investigator (Mr.Wang). The following information were collected: first author's name; year of publication; type of disease; country; region; genotyping methods; number of cases and controls in each study; characteristics of controls; category of polymorphisms and other additional information.

Quality Assessment.
The included studies in this metaanalysis were evaluated by another inspector (Pan). The quality assessment was based on the modified Newcastle-Ottawa Quality Assessment Scale (NOS). The scale consists of eight multiple-choice questions that involve subjects' selection, comparability in cases and controls, and assessment of exposure. High-quality response earns a point, totaling up to nine points (the comparability question earns up to two points). The higher score indicates better quality. chose fixed-effects or random-effects model. All subgroups were analyzed. Sensitivity analysis was used to evaluate the influence of individual study on the overall OR. Publication bias was assessed by Funnel's plot, Begg's test and Egger's test. An asymmetric plot and the value of Egger's test or Begg's test less than 0.05 were considered as significant publication bias.

Literature Search.
A total of 390 studies were retrieved from PubMed, Web of science, Elsevier Science Direct and Cochrane Library. Finally, 18 eligible studies were included in this meta-analysis. A flowchart of the included and excluded studies was shown in Figure 1.     OR: 0.935, 95% CI=0.821-1.065, P=0.310). After stratifying by region, it only showed the association between miRNA-146 rs2910164 polymorphism and inflammatory arthritis susceptibility in Middle East ( Figure 2). This may be due to the differences in geographic region, ethnicity, and sample size.

Meta-Analysis of Association between miRNA-499 rs3746444 Polymorphism and Inflammatory Arthritis.
Meta-analysis indicated significant association between miRNA-499 rs3746444 polymorphism and inflammatory arthritis susceptibility in the overall population (C vs T  Figure 3). But, we did not find this association in Asia and North America.

Heterogeneity and Publication Bias.
The results of heterogeneity test were shown in Table 2. And the results of Begg's test and Egger's test were also shown in Table 2. As for some studies that had heterogeneity ( 2 > 50%), the random-effects models were performed; others were analyzed by fixed-effects model. As for miRNA-499 rs3746444 polymorphism, the plot of sensitivity analysis was shown in Figure 4. And there was no significant evidence of publication bias found in the metaanalysis.

Discussion
Both environmental factors and genetic factors are related to the development of inflammatory arthritis. As for miR-NAs, it is reported that they are involved in cancers and autoimmune diseases [15,21]. But some recent studies about miRNA-146/499 polymorphisms and inflammatory arthritis are inconsistent; it needs us to explore the real association  between miRNA-146/499 polymorphisms and inflammatory arthritis by conducting this meta-analysis. Present meta-analysis included 18 relevant studies, 9 only about miRNA-146 rs2910164, 3 only about miRNA-499 rs3746444, and 6 about both miRNA-146 rs2910164 and miRNA-499 rs3746444. There were 5 studies not met Hardy-Weinberg equilibrium; we did not exclude those 5 studies. We conducted subgroup analysis according to HWE and found that the results are similar ( Table 2).
Of course, there were some limitations in this metaanalysis. First, we searched literature based on English; it may cause language bias. Second, the number of included studies was not sufficient, which could not conduct comprehensive analysis. Third, our data of meta-analysis were from retrospective research, which may be related to the methodological deficiencies. Finally, our meta-analysis did not take the interactions between environmental factors and genetic factors into account. Therefore, the results should be interpreted with caution.
In conclusion, the present study indicates that miRNA-499 rs3746444 polymorphism is associated with inflammatory arthritis susceptibility. However, there is lack of association between miRNA-146 rs2910164 polymorphism and inflammatory arthritis susceptibility. But, we find miRNA-146 rs2910164 and miRNA-499 rs3746444 polymorphism are associated with inflammatory arthritis in Middle East. Therefore, it is necessary to conduct more large-sample and more high-quality studies to further validate our findings.

Conflicts of Interest
All members declare they have no conflicts of interest.