P1197 ERAP2 genetic variant rs2248374 is linked to paradoxical skin reactions induced by TNF-alpha inhibitors in Romanian patients with Inflammatory Bowel Diseases

Abstract

Abstract Background The endoplasmic reticulum aminopeptidases (ERAPs) are responsible for trimming protein residues to optimal length for major histocompatibility complex class-1 mediated antigen presentation process. Genome-wide association studies have shown the influence of ERAP1 and ERAP2 genetic variants in disease susceptibility for autoimmune disorders. Their role in inflammatory bowel diseases (IBD) however remains obscure due to literature data paucity. The aim of this study was to evaluate the role of a single nucleotide polymorphism (SNP) rs2248374 (G/A) of ERAP2 gene in disease susceptibility and response to treatment in Romanian population with IBD. This SNP is of particular importance because the G allele produces a truncated ERAP2 transcript undergoing nonsense-mediated decay and therefore individuals with GG genotype have no functional ERAP2 enzyme. Methods The study involved 186 IBD patients (87/99 UC/CD, 91M/69F) and 150 healthy controls (77M/73F) all unrelated and of Romanian ethnicity. Extraintestinal manifestations (EIM) were documented in 43 IBD patients (19UC/24BC). Among patients with biological treatment against TNF-alpha (N=113) there were 31 (27.4%) primary non-responders and 13 (11.5%) with paradoxical skin reactions. All subjects were genotyped for ERAP2 rs2248374 (G/A) using TaqMan Allelic Discrimination Assay (C_25649529_10 Real-Time PCR System, Applied Biosystems by Thermo Fisher Scientific, USA). Association tests were performed with OpenEpi online software using Two by Two Table statistics. P-values (2-tail from Mid-P exact test) were considered significant if <0.05. Results Controls and patients were in Hardy-Weinberg equilibrium for the investigated SNP. No significant differences were observed in relation with the risk of disease or with the therapy response. The minor allele A frequency was significantly lower in IBD patients with paradoxical skin reactions (27%) versus patients without these manifestations (50%, p=0.02, OR 0.36). The genotype AA, responsible for full ERAP2 expression, had 0% frequency in the group with adverse skin reactions compared with 23.2% in patients without (p=0.04, OR 0.0). The GG genotype which is related with no ERAP2 protein expression was more frequent in the subgroup of patients with EIM (41.8%) than in patients without EIM (26.7%), showing a marginal association (p=0.06, OR 1.97). Conclusion Our results point to the fact that ERAP2 rs2248374 AA genotype exerts a protective effect over paradoxical skin reaction induced by TNF antagonist agents, and GG genotype shows marginal association with the presence of EIM in Romanian patients with IBD. We consider these results worthy of replication in larger cohorts of patients.