Decreased expression of TIGIT on CD14 + monocytes correlates with clinical features and laboratory parameters of patients with primary Sjögren's syndrome

Objectives: The purpose of this study was to investigate the expression of T-cell immunoglobulin and ITIM domain (TIGIT) in peripheral circulation of primary Sjögren's syndrome (pSS) and its role in the development of pSS.

Methods: The expression of TIGIT on T cells, B cells, natural killer (NK) cells, and CD14 + monocytes was detected by flow cytometry in pSS and healthy control (HC). The correlations between expression of TIGIT and clinical features and laboratory parameters of pSS were analyzed. Meanwhile, we analyzed the change in expression of TIGIT before and after treatment, and its role in the prognosis of pSS treatment was evaluated.

Results: The expression of TIGIT on CD3 + , CD4 + , and CD8 + T cells increased and decreased on CD14 + monocytes in pSS compared to HC; however, there was no significance of B lymphocytes and NK cells. The correlation analysis between the expression of TIGIT on T lymphocytes and CD14 + monocytes and clinical features of pSS showed that the decrease in TIGIT expression on CD14 + monocytes was more closely related to pSS. The expression of TIGIT + CD14 + monocytes negatively correlated with the disease activity of pSS. The expression of TIGIT + CD14 + monocytes of pSS with arthralgia, fatigue, decayed tooth, xerostomia, interstitial lung disease, anti-Ro52 positive, and high IgG decreased compared to that in negative patients. Furthermore, it was significantly lower in active patients than in nonactive patients. After treatment, the expression of TIGIT + CD14 + monocytes tended to increase.

Conclusion: Our study suggested that decreased TIGIT expression on CD14 + monocytes was associated with the clinical manifestations, disease activity, and prognosis of pSS patients. TIGIT + CD14 + monocytes may present as a potential target and a biomarker of the prognosis for immunomodulatory therapy in pSS. Key Points • The expression of TIGIT+CD14+ monocytes significantly decreased in pSS patients compared to HC. • There was a negative correlation between TIGIT+CD14+ monocytes and the disease activity of pSS. • TIGIT+CD14+ monocyte expression was associated with the clinical manifestations, autoantibodies, IgG, and prognosis of pSS patients.