Intestinal Microbiota, HLA-B27, and Spondyloarthritis: Dangerous Liaisons.

Spondyloarthritis, although primarily a joint-centered disease, is associated with extra-articular features, such as gut inflammation, psoriasis, and/or uveitis. Evidence points to underlying genetic predisposing factors and/or environmental factors. This is most clear in the gut, with progress through 16S and metagenomics sequencing studies and the results of functional studies in preclinical arthritis models. Translation of these findings to the clinic is making progress based on encouraging results of fecal microbial transplant studies in several human diseases. This review elaborates on novel trends in host-microbial interplay in spondyloarthritis, focusing on microbiota, immune dysregulation, and disease progression, and modulation by HLA-B27.