A Decreased Absolute Number of Treg Cells in Patients with Active Rheumatoid Arthritis is Associated with Elevated Serum Osteopontin Levels with Disease Progression.

Abstract

Rheumatoid arthritis (RA) is a chronic and refractory autoimmune disease characterized by synovial inflammation with unknown aetiology. Immune system dysfunction mediated by CD4+ Tlymphocytes, which is regulated by the cytokine osteopontin (OPN), plays an important role in the pathogenesis of RA. In this study, the levels of peripheral CD4+ Tsubsets and serum OPN in patients with active RA were measured and analysed to determine the possible pathogenesis of RA and to provide potential therapeutic targets. Serum OPN levels in both patients with active RA and patients with refractory RA were higher than those in healthy controls (HCs). Compared with HCs, the absolute numbers of Th2 cells increased in patients with active RA, while the absolute counts of Th1 and Treg cells decreased. There was no significant difference in CD4+ Tsubset levels between new-onset and refractory patients. As the condition persisted or deteriorated, a gradual increase in the levels of OPN and gradual declines in the absolute counts of Th1 and Treg cells were observed in patients with active RA. The fewest Th1 and Treg cells and the highest OPN levels were observed in patients with high disease activity. The serum OPN level was only significantly negatively correlated with the absolute counts of Treg cells in the CD4+ Tlymphocyte subsets. Fewer Treg cells with the increase in disease activity may be related to the increased OPN concentration, which may provide new ideas and directions for the targeted immunoregulatory treatment of RA.