Exploring the Involvement of ERAP1 in the Pathogenesis of Non-Infectious Uveitis: A Systematic Review

Background: Non-infectious uveitis (NIU) is an inflammatory ocular condition often associated with systemic immune-mediated disorders. The pathogenesis of NIU is complex and involves genes from the Human Leukocyte Antigen (HLA) class I system. Endoplasmic reticulum aminopeptidase 1 (ERAP1) cleaves antigenic peptides to an optimal length for loading and presentation on HLA I molecules. In this systematic review, we aimed to summarize the current knowledge regarding how susceptibility to developing NIU is linked to single-nucleotide polymorphisms (SNPs) in the ERAP1 gene, a locus well known for its connection to autoinflammatory disorders. Methods: We performed a PRISMA protocol-guided systematic review in various databases. Results: Out of the 311 screened studies, only 12 met the inclusion criteria. Five of them are Genome-Wide Association Studies. We found relevant research for three types of NIU: acute anterior uveitis, Behçet's uveitis, and birdshot chorioretinopathy. A frequently observed association between ERAP1 SNPs and disease risk was noted when analyzing the HLA-carriers (B*27, B*51, A*29), which points toward an epistatic interaction between ERAP1 and the MHC class I complex. Conclusions: Our findings suggest that ERAP1 gene variation is understudied in relation to NIU. A significant amount of research has also concentrated on risk stratification, and reliable markers for patient selection are needed, especially in view of emerging anti-ERAP therapies.