Uveitis and spondyloarthropathies

Uveitis is a frequently occurring extra-articular manifestation of spondyloarthropathies (SpAs), ankylosing spondylitis (AS), reactive arthritis (ReA), psoriatic arthritis (PsA) and inflammatory bowel disease (IBD), occurring in both adults and children with SpA. Uveitis occurs with varying frequency according to the SpA subtype (33% in AS, 6-9% in PsA, 25% in ReA, 13% in undifferentiated SpA and 2-5% in IBD), the presence of HLA-B27 and with increasing duration of disease. The majority of cases of uveitis in SpA are attributed to acute anterior uveitis but a minority of uveitis cases occur in the posterior segment of the eye. The latter are more frequently complicated by cystoid macular oedema (CMO) and sight loss. The nature of the tissue specificity exhibited by the SpAs is poorly understood. Three current investigational approaches are discussed: high-throughput genomics to identify and confirm uveitis-specific susceptibility alleles; investigation of the role of the intestinal microbiome and its potential role in innate immune signalling in uveitis; and study of a novel IL23R-bearing cell population in several entheseal sites including the eye. The treatment for uveitis in SpAs is predominantly with topical corticosteroids for acute episodes. Among the systemic drugs used for the treatment of SpAs, infliximab, adalimumab and certolizumab are effective in reducing the frequency of uveitis but etanercept is not. Other targets in spondyloarthropathy include cytokines within the IL23/IL17 axis, of which the IL17A inhibitor secukinumab has not been shown to be effective in uveitis. Future therapeutic approaches may include small molecules such as selective and non-selective janus kinase and tyrosine kinase inhibitors.