Authors: Ting Cheng, Sheng-Xiao Zhang, Jia Wang, Jun Qiao, Min-Jing Chang, Hong-Qing Niu, Guang-Ying Liu & Xiao-Feng Li
Abstract
Introduction
Osteoporosis (OP) is one of the major comorbidities of rheumatoid arthritis (RA). Recent studies have shown that immune cells modulate bone health and regulate bone remodeling. However, the alterations of lymphocyte subsets in RA patients with OP are unclear. Here, we assessed the absolute numbers and proportions of the subsets in RA sufferers with OP and investigated the clinical significance.
Methods
A total of 777 RA patients and 117 gender- and age-matched healthy controls (HCs) were enrolled in this study. Patients were divided into RA-non-OP and RA-OP group according to their bone mineral density (BMD) and the history of fragility fracture. Peripheral lymphocyte subsets of participants were assessed by flow cytometry.
Results
Among 220 (28.31%) RA-OP patients, there were higher levels of erythrocyte sedimentation rate (ESR) (P = 0.011), C-reactive protein (CRP) (P = 0.028), rheumatoid factor (RF) (P = 0.013) and anti-cyclic citrullinated peptide antibody (ACPA) (P = 0.010), while red blood cells (RBC) (P = 0.039) were lower than those in RA-non-OP group. Compared with those of HCs and RA-non-OP group, the level of circulating Th17 cells in RA-OP patients was significantly increased (P < 0.05), while those of Tregs decreased (P < 0.01), leading to a higher ratio of Th17/Treg (P < 0.01). Notably, the level of B cells in both RA-non-OP and RA-OP group was reduced, this alteration was more obvious in patients with OP (P < 0.05).
Conclusions
Immune disorders characterized by peripheral Th17/Treg imbalance and reduced B cells may contribute directly or indirectly to OP in RA, and this deserves more clinical attention.
Key Summary Points |
Why carry out this study?Osteoporosis (OP) is one of the major complications of rheumatoid arthritis (RA), which results in increased bone fragility and fracture risk, leading to the prolongation of the disease course and the reduced quality of life. Not only do immune disorders participate in the development of RA disease, but they also modulate bone health and regulate bone remodeling. We intended to investigate the levels of peripheral lymphocyte subsets in RA patients complicated with OP and expound the possible immunologic mechanisms of high incidence of osteoporosis in RA patients. |
What was learned from the study?Th17/Treg imbalance and reduced B cells were more significant in RA-OP patients than RA-non-OP patients, which provides clinical evidence for early prevention and treatment of OP in RA patients. It is necessary to focus on the level of peripheral lymphocyte subsets in future clinical practice. |