Activation status of mucosal-associated invariant T cells reflects disease activity and pathology of systemic lupus erythematosus.

BACKGROUND: Mucosal-associated invariant T (MAIT) cells are innate-like lymphocytes constituting a large proportion of peripheral blood T cells expressing αß T-cell receptor in humans. In this study, we aimed to investigate their involvement in systemic lupus erythematosus (SLE). METHODS: Peripheral blood MAIT cells from patients with SLE were assessed for their frequency, activation markers, and cell death by flow cytometry. The correlation between plasma cytokine levels and CD69 expression on MAIT cells was analyzed. The major histocompatibility complex class I-related protein MR1-restricted antigen-presenting capacity of antigen-presenting cells was investigated. Cytokine-mediated activation of MAIT cells in the absence of exogenous antigens was also examined. RESULTS: The frequency of MAIT cells was markedly reduced in SLE. The reduced number of MAIT cells was not attributable to the downregulation of surface markers, but it was partially due to the enhanced cell death of MAIT cells, possibly by activation-induced cell death. The CD69 expression levels on MAIT cells in SLE correlated with disease activity. Moreover, monocytes from patients with SLE exhibited increased ability to induce MAIT cell activation. The plasma concentration of interleukin (IL)-6, IL-18, and interferon (IFN)-α positively correlated with the expression levels of CD69 on MAIT cells in SLE. MAIT cells were activated by cytokines, including IFN-α, IL-15, and IL-12 plus IL-18, in the absence of exogenous antigens. CONCLUSIONS: These results suggest that MAIT cells reflect the pathological condition of SLE and that their activated status correlates with presence of disease.

Safety and efficacy of the leukocytapheresis procedure in eighty-five patients with rheumatoid arthritis.

Rheumatoid arthritis (RA) is a systemic inflammatory disease in which the predominant symptom is polyarthritis that follows a chronic and progressive clinical course characterized by destructive synovitis and various immune disorders. Striking progress in RA treatment was achieved with the emergence of monoclonal antibodies to target cytokines. However, drug choices are limited for many patients due to resistance to multidrug antirheumatic therapy, concomitant disease, and infection. We evaluated the efficacy of treatment in 85 patients with RA for whom leukocytapheresis (LCAP) was initiated at our hospital between 2006 and 2015. All patients continued drug therapy and were treated with LCAP once a week for up to 5 weeks. The clinical response was evaluated at the completion of LCAP series and 4 weeks later using the American College of Rheumatology (ACR) criteria and the 28-joint disease activity score (DAS28) of European League Against Rheumatism (EULAR). The tender joint counts, swollen joint counts, and C-reactive protein (CRP) levels decreased remarkably. DAS28-CRP was significantly improved by LCAP. And furthermore, the efficacy lasted at least 4 weeks after the completion of LCAP. These results suggest that LCAP is a beneficial and are consistent with several trials' reported effect of LCAP. This treatment can contribute to improvements in activities of daily living (ADLs) and long-term outcome by improving swollen and tender joint counts and CRP levels even in refractory patients for whom the use of conventional disease-modifying antirheumatic drugs (DMARDs) and biopharmaceuticals is problematic. LCAP might be a promise therapy to refractory RA.

Involvement of Mucosal-associated Invariant T cells in Ankylosing Spondylitis.

OBJECTIVE: Ankylosing spondylitis (AS) is characterized by chronic inflammation of the axial and peripheral joints and ligamentous attachments. Gut immunity is thought to be involved in AS, because a prominent coexistence of gut and joint inflammation has been observed in patients with AS. Mucosal-associated invariant T (MAIT) cells are preferentially located in the gut lamina propria and produce inflammatory cytokines such as interleukin 17 (IL-17) and tumor necrosis factor-α (TNF-α), which are therapeutic targets for AS. This study aimed to investigate the involvement of MAIT cells in AS. METHODS: The frequency of MAIT cells and their cytokine production were determined in patients with AS and healthy controls (HC). The expression of a MAIT cell activation marker (CD69) was analyzed in patients with AS by using flow cytometry. RESULTS: The frequency of MAIT cells in the peripheral blood was lower in patients with AS compared with HC. The levels of IL-17 produced by MAIT cells after activation were higher in patients with AS than in the HC. CD69 expression on MAIT cells correlated with the Ankylosing Spondylitis Disease Activity Score in patients with AS. CONCLUSION: These results suggest the involvement of MAIT cells in the pathogenesis of AS.