Decreased CD200R expression on monocyte-derived macrophages correlates with Th17/Treg imbalance and disease activity in rheumatoid arthritis patients.

CD200 is expressed on various cell types, including T cells, while the CD200 receptor (CD200R) is expressed on myeloid cells such as monocytes-derived macrophages (MDMs). The CD200-CD200R interaction has been shown to play an important role in the prevention of autoimmune disease. Thus, we hypothesized that CD200/CD200R1 is involved in the pathogenesis of rheumatoid arthritis (RA). In total, 35 RA patients and 17 healthy controls (HCs) were enrolled in this study. CD200/CD200R1 expression and Th17/Treg were examined by flow cytometry. Serum levels of interleukin (IL)-2, interferon-γ (IFN-γ), IL-4 and IL-10 were detected by ELISA. Disease activity was evaluated according to the C-reactive protein (CRP) levels, erythrocyte sedimentation rates (ESR) and 28-joint disease activity score (DAS28) scores. Compared with HCs, RA patients exhibited a significantly decreased level of CD200R1 on MDMs. CD200R1 expression correlated negatively with DAS28, ESR, and CRP levels. This abnormal expression was associated with Th17/Treg imbalance in the active RA patients. However, expression of CD200R1 was not correlated with Th1 (IL-2, IFN-γ) or Th2 (IL-4, IL-10) cytokine responses. In this study, we demonstrate a significant correlation between CD200R1(+) cells and disease severity in RA patients, thus indicating the relevance of the CD200/CD200R1 signaling pathway's potential involvement in the pathogenesis of RA.