Analysis of gut homing receptors in circulating MAIT cells and their presence in synovial tissue from patients with axial spondyloarthritis.

Abstract

OBJECTIVE mucosal-associated invariant T cells (MAIT) have been involved in the pathophysiology of axial spondyloarthritis (axSpA). We aimed to further investigate the phenotype of circulating MAIT cells in patients with axSpA by assessing the expression of an activation marker and gut homing receptors as well as the impact of TNF-α blockade. The presence of MAIT cells in synovial biopsies from axSpA patients was also studied. METHODS blood samples were obtained from 26 axSpA patients (11 radiographic, 15 nonradiographic) and 27 healthy controls (HC). Frequency of Vα7.2+CD161+ MAIT cells was determined in axSpA and HC. Expression of CD69, CCR9 and CD49d on MAIT cells was analyzed by flow cytometry. The presence of MAIT cells was examined in synovial biopsy samples from three axSpA patients and compared to synovial biopsies from 3 rheumatoid arthritis (RA) patients and 4 osteoarthritis (OA) patients by confocal microscopy. RESULTS patients with axSpA were characterized by a higher frequency of CD3+ and CD8+ MAIT cells expressing CD69, CCR9 and CD49d, especially in the radiographic subgroup. MAIT cells were detected in a synovial biopsy sample from one patient with axSpA. After TNF-α blockade, a decrease in the frequency of MAIT cells and TNF-α/IL-17A - producing-MAIT cells was observed. CONCLUSION MAIT cells were activated and expressed gut homing receptors, indicating their potential involvement in the gut-joint axis of axSpA. MAIT cell frequency and function were reduced by TNF-α blockade. MAIT cells could be found in synovial tissue in axSpA.