Associations between ERAP1 polymorphisms and susceptibility to ankylosing spondylitis: A meta-analysis of East Asian Population

Shedding Light on the Role of ERAP1 in Axial Spondyloarthritis

Spondyloarthritis (SpA) is a multifactorial chronic inflammatory disease affecting the axial skeleton (axSpA) and/or peripheral joints (p-SpA) and entheses. The disease's pathogenesis depends on genetic, immunological, mechanical, and environmental factors. Endoplasmic reticulum aminopeptidase 1 (ERAP1) is a multifunctional enzyme that shapes the peptide repertoire presented by major histocompatibility complex (MHC) class I molecules. Genome-wide association studies (GWAS) have identified different single nucleotide polymorphisms (SNPs) in ERAP1 that are associated with several autoimmune diseases, including axSpA. Therefore, a deeper understanding of the ERAP1 role in axSpA could make it a potential therapeutic target for this disease and offer greater insight into its impact on the immune system. Here, we review the biological functions and structure of ERAP1, discuss ERAP1 polymorphisms and their association with axSpA, highlight the interaction between ERAP1 and human leukocyte antigen (HLA)-B27, and review the association between ERAP1 SNPs and axSpA clinical parameters.

HLA-B27 may modulate the interaction between ERAP1 polymorphisms and smoking in ankylosing spondylitis patients

BACKGROUND

Ankylosing spondylitis (AS) is an autoimmune disease that affects the enthesis and synovial membrane of the spine, the sacroiliac vertebrae and peripheral joints. Genetic susceptibility to AS is mainly due to the presence of the HLA-B*27 (B27) allele, and endoplasmic reticulum aminopeptidase-1 (ERAP-1) plays a key role in antigen processing and presentation to HLA class I molecules. Tobacco consumption is one of the main environmental factors involved in the pathogenesis of various diseases, including AS. The objective of the present study was to evaluate the association and the interactive effects of variants of the ERAP1 gene with smoking in modulating the risk of AS.

METHODS AND RESULTS

A case-control study in the Mexican population. The association of two functional variants of the ERAP1 gene (rs30187 and rs27044) in patients with AS was analyzed by the allelic discrimination method using TaqMan probes. B27 was typified by PCR-SSP. The interaction between the variants of ERAP1 and B27 and smoking was assessed using the multifactorial dimensionality reduction (MDR) method. There was no significant association of the two variants of ERAP1 in the cases compared with the controls (P > 0.05); however, a strong interaction between the variants and smoking could be demonstrated, with entropy values of 4.97% for rs30187 and 5.13% for rs27044. In addition, these interaction effects were increased in patients carrying the B27 allele.

CONCLUSIONS

The rs30187 and rs27044 variants of the ERAP1 gene appear to potentiate the effect of smoking in patients with AS carrying the B27 allele.

Associations between ERAP1 polymorphisms and ankylosing spondylitis susceptibility in HLA-B27 positive population: a Meta-analysis and bioinformatics analysis

Human leukocyte antigen (HLA)-B27 confers a key role in ankylosing spondylitis (AS) susceptibility. Endoplasmic reticulum aminopeptidase 1 (ERAP1) polymorphisms are associated with AS susceptibility in common population. In this study we intended to evaluate the possible association between ERAP1 polymorphisms and AS susceptibility in HLA-27 positive population. Data were collected from Pubmed, Embase, and Cochrane databases. The pooled odds ratios and 95% confidence intervals of the minor allele of each locus were calculated to appraise the associations under ERAP1 polymorphisms and AS in HLA-B27 positive population. Bioinformatics analysis was performed to explore the underlying mechanism. Four studies were included in this meta-analysis. There was a significant association between the minor allele of rs2287987 and reducing the risk of developing AS in HLA-B27 positive population. But there was no significant association between the minor allele of rs30187, rs27044, rs10050860 and rs17482078 and AS susceptibility. According to HaploReg, 5 motifs changed for rs2287987 were found. The eQTL analysis demonstrated that rs2287987 may influence ERAP1 expression. Rs2287987 in ERAP1 may have small influence on AS susceptibility in HLA-B27 positive population. Bioinformatics analysis indicated that the altered motifs and the change of EARP1 expression may influence the AS susceptibility.

The Potential Role of Genetics, Environmental Factors, and Gut Dysbiosis in the Aberrant Non-Coding RNA Expression to Mediate Inflammation and Osteoclastogenic/Osteogenic Differentiation in Ankylosing Spondylitis

Ankylosing spondylitis (AS) or radiographic axial spondyloarthritis is a chronic immune-mediated rheumatic disorder characterized by the inflammation in the axial skeleton, peripheral joints, and soft tissues (enthesis, fascia, and ligament). In addition, the extra-skeletal complications including anterior uveitis, interstitial lung diseases and aortitis are found. The pathogenesis of AS implicates an intricate interaction among HLA (HLA-B27) and non-HLA loci [endoplasmic reticulum aminopeptidase 1 (ERAP1), and interleukin-23 receptor (IL23R), gut dysbiosis, immune plasticity, and numerous environmental factors (infections, heavy metals, stress, cigarette smoking, etc.) The latter multiple non-genetic factors may exert a powerful stress on epigenetic regulations. These epigenetic regulations of gene expression contain DNA methylation/demethylation, histone modifications and aberrant non-coding RNAs (ncRNAs) expression, leading to inflammation and immune dysfunctions. In the present review, we shall discuss these contributory factors that are involved in AS pathogenesis, especially the aberrant ncRNA expression and its effects on the proinflammatory cytokine productions (TNF-α, IL-17 and IL-23), T cell skewing to Th1/Th17, and osteoclastogenic/osteogenic differentiation. Finally, some potential investigatory approaches are raised for solving the puzzles in AS pathogenesis.

A meta-analysis for association of TNF-α -308G>A polymorphism with susceptibility to Ankylosing Spondylitis

Objective

We performed a meta-analysis of all eligible studies on the association of TNF-α -308G>A polymorphism with risk of Ankylosing spondylitis (AS).

Methods

A comprehensive literature research was performed in online databases.

Results

A total of 28 studies with 4489 cases and 5919 controls were included. Pooled ORs showed a significant association between TNF-α -308G>A polymorphism and risk of AS. Moreover, stratified analysis by ethnicity showed a significant association between TNF-α -308G>A polymorphism and AS risk in Asians, Caucasians and Mixed populations, but not in Chinese population.

Conclusion

This meta-analysis suggested that the TNF-α -308G>A polymorphism was associated with AS risk.

Susceptibility to ERAP1 gene single nucleotide polymorphism modulates the inflammatory cytokine setting in ankylosing spondylitis

AIM

To evaluate the association of ERAP1 gene single nucleotide polymorphisms (SNPs) with the risk of ankylosing spondylitis (AS) and their role in modulation of the inflammatory interleukin (IL)-17/IL-23 axis in the disease.

METHODS

For genotyping, 190 AS cases and 190 healthy controls were enrolled. After DNA extraction, all the subjects were genotyped for rs17482078, rs469876, and rs27038 polymorphisms using single specific primer polymerase chain reaction (PCR) assay. After isolation of peripheral blood mononuclear cells, RNA extraction and complementary DNA synthesis, real-time PCR using SYBR Green master mix was employed to determine messenger RNA (mRNA) expression of IL-17A and IL-23 in PBMCs. Using enzyme-linked immunosorbent assay, the concentration of these cytokines was determined in serum samples.

RESULTS

It was observed that the A allele of rs27038 polymorphism significantly increased AS risk (odds ratio [OR] = 1.53, 95% CI =1.11-2.12; P = 0.0096). Moreover, AA and AG genotypes of this SNP were associated with increased (OR = 2.89, 95% CI = 1.42-5.85; P = 0.0031) and decreased (OR = 0.57, 95% CI = 0.36-0.92; P = 0.021), respectively, risk of the disease. The rs27038 SNP was associated with C-reactive protein level. There were significantly increased mRNA and serum concentrations of both IL-17A and IL-23 in AS patients compared with controls. Furthermore, AS patients with the AA in comparison to other genotypes for rs27038 SNP indicated significantly increased mRNA and serum concentration levels for both cytokines.

CONCLUSIONS

This study demonstrated the association of ERAP1 gene rs27038 polymorphism with the risk of AS in an Iranian population. Additionally, it seems that rs27038 is involved in the modulation of the inflammatory IL-17/IL-23 axis in AS.

Association of TNF, IL12, and IL23 gene polymorphisms and psoriatic arthritis: meta-analysis

BACKGROUND

Psoriatic arthritis (PsA) is a chronic skin and joint condition that considerably affects patient quality of life. Several studies have demonstrated different associations of genetic polymorphisms in the pathogenic process of PsA. Therefore, we conducted a meta-analysis to estimate the effect of polymorphisms in the cytokines TNF, IL12B, IL23A, and IL23R on PsA risk.

METHODS

We screened 1,097 abstracts and identified 14 relevant studies published between January 2007 and December 2017. A systematic search was conducted in PubMed, Web of Knowledge and Scopus databases. Meta-analyses were performed for the comparisons of alleles and multiple genetic models.

RESULTS

Among the cytokines studied, we found 17 polymorphisms that were the most investigated. The association to PsA was observed in the presence of polymorphisms: TNF-238 G > A (rs361525), -308 G > A (rs1800629), and -857 C > T (rs1799724); IL12B C > G (rs6887695) and A > C (rs3212227); IL23A A > G (rs2066808) and IL23R G > A (rs11209026).

CONCLUSION

Our findings suggest that these variant cytokine genes may strongly influence the immunological response of PsA.