Evaluation of ERAP1 Gene Single Nucleotide Polymorphism in Impressing the Inflammatory Cytokine Profile of Ankylosing Spondylitis Patients

Abstract

Ankylosing spondylitis (AS), an autoinflammatory disease, has been associated with impaired Endoplasmic reticulum aminopeptidase (ERAP) 1 activity, which is involved in priming antigenic peptides. The purpose of this study was to evaluate if the genetic variant of ERAP1 gene could impress the inflammation status of the AS patients.

For genotyping, 140 AS cases and 140 healthy controls were enrolled. After isolation of peripheral blood mononuclear cells (PBMCs) and DNA extraction, all the subjects were genotyped for rs27044 polymorphism using SSP-PCR assay. Total RNA of PBMCs was isolated, cDNA was synthesized, and quantitative analyses of mRNA expression of cytokines were performed via Real-time PCR using the SYBR Green Gene Expression MasterMix. To measure the concentration of cytokines in serum of subjects, ELISA was used.

It was observed that the G allele of rs27044 polymorphism was significantly prevalent in AS patients. Moreover, the GG genotype and the GG+GC dominant model had significantly different distribution between study groups. There was a significant overexpression of mRNAs of IL-17A, IL-6, IL-33, TNF-α, and IFN-γ, while IL-10 was significantly downregulated in AS patients. The ELISA results were in line with that of the gene expression analysis. No significant differences in mRNA expression and concentration of cytokine were identified among AS patients with three genotypes for rs27044 SNP.

This study replicated the association of polymorphisms in ERAP1 gene with the risk of AS in a population from Iranian. However, it did not directly determine the inflammatory profile of the AS patients.