IL-7 primes IL-17 in mucosal-associated invariant T (MAIT) cells, which contribute to the Th17-axis in ankylosing spondylitis

Abstract

This study reveals a potential role for MAIT cells in patients with AS and is the first linking IL-7 to the elevated IL-17 profile in patients through the AS-associated risk gene IL7R.

Innate‐like CD8+ T‐cells and NK cells: converging functions and phenotypes

“…Thus, CD56 bright NK cells are highly enriched and activated within synovial fluid from patients with psoriatic arthritis and rheumatoid arthritis (RA),122, 123 as well as in inflamed tissues in tuberculosis 124. Similarly, MAIT cells are also well established to be recruited to sites of inflammation,81, 125 and have been found to be enriched in the synovial fluid of patients with ankylosing spondylitis126 and RA127. They have also been shown to be recruited to the lung of patients with active tuberculosis infection,81, 82 increased in inflamed intestinal tissues in patients with inflammatory bowel disease,125 adipose tissues of obese patients,128 and are present in multiple sclerosis (MS) lesions 129, 130, 131.…”

The role of the gastrointestinal tract in the pathogenesis of rheumatic diseases

“…Mucosal-associated invariant T (MAIT) cellsda novel innate-like T-cell population, recognizing a highly conserved antigen derived from the microbial riboflavin synthesis pathway [40]dhave been recently implicated in the pathogenesis of AS. Gracey E et al [41] recently demonstrated that MAIT cells are reduced in frequency in the blood of patients with AS compared with HCs. AS patients, however, have an elevated frequency of circulating and synovial IL-17Aþ MAIT cells, and IL-17 elevation in AS MAIT cells seems to be dependent on priming with IL-7, but not IL-23 or antigen stimulation.…”

MAIT cells: not just another brick in the wall

“…MR1 −/− mice, which lack MAIT cells, had reduced severity of antibody-induced arthritis and collagen-induced arthritis, both models for RA, suggesting a pathological role for MAIT cells in RA 9. In this issue of Annals of the Rheumatic diseases , Gracey et al 10 are the first to investigate the number of MAIT cells and their functional phenotype in patients with AS. As in many other inflammatory diseases,4 they report a relative abundance of IL-17-producing MAIT cells in patients with AS, both systemically and in synovial fluid compared with healthy controls and patients with RA 10.…”

“…In this issue of Annals of the Rheumatic diseases , Gracey et al 10 are the first to investigate the number of MAIT cells and their functional phenotype in patients with AS. As in many other inflammatory diseases,4 they report a relative abundance of IL-17-producing MAIT cells in patients with AS, both systemically and in synovial fluid compared with healthy controls and patients with RA 10. However, it still needs to be elucidated to what extent these cells are developmentally programmed to attain this IL-17A-producing phenotype or if they acquire these characteristics in the periphery under inflammatory conditions after being fully matured.…”

“…A similar situation was found in patients with AS and patients with RA, where MAIT cells were enriched in the synovial fluid and lowered systemically. Even though the numbers between AS and RA seem comparable, they phenotypically differ as only in patients with AS MAIT cells had a predominant IL-17A profile 10. Human MAIT cells are often characterised as CD3 + TCRVα7.2 + CD161 hi T cells 4 12.…”