Upregulation of circulating soluble programmed death-1 molecule and its correlation with the disease activity of rheumatoid arthritis patients in Ethiopia

Abstract Background: Rheumatoid arthritis is an autoimmune disease characterized by the destruction of joints and, if left untreated, leads to functional impairment. Various elements heightened the inflammation and progress of the disease. Although the pioneered role of soluble programmed death-1 is controversial, it is believed to be correlated to the disease activity of Rheumatoid arthritis. So this study aimed to assess plasma soluble programmed death 1 (sPD-1) level and its correlation with disease activity in rheumatoid arthritis patients at Tikur Anbesa Specialty Hospital, Addis Ababa, Ethiopia. Method: The hospital-based cross-sectional study was undertaken from February 2021 to June 2021. Participants were enrolled through consécutive sampling. Sociodemographic data was collected using structured questionnaires, while clinical data was collected using a data collection sheet. The disease activity of the Rheumatoid arthritis patients was measured with disease activity score-érythrocytes sédimentation rate (DAS28-ESR) score. Plasma soluble programmed death one concentrations were measured using an enzyme-linked immunosorbent assay (ELISA) kit. A median variation in the concentration of soluble programmed death one between Rheumatoid arthritis patients and healthy controls were evaluated using the Mann-Whitney U-test, while Spearman’s correlation coefficient was measured to test the correlation between predictor and outcome variables. Results: This study included 50 rheumatoid patients with a mean age of 48.08 ± 9.391 and 50 healthy controls with a mean age of 38.30 ± 13.386. In patients with RA, soluble PD-1 levels were (median; 1023 pg/mL, IQR; 850.5 - 1304.54) compared to healthy controls (median; 531.9 pg/mL, IQR: 364 - 809) increased significantly (p<0.001). Soluble PD-1 has a strong positive correlation with DAS28 (r=0.7157, p<0.001), ESR (r=0, 5657, p<0.001), and number of swollen and tender joints (r=0.5533, p<0.001). Plasma-soluble PD-1 levels were significantly lower in patients in remission compared to active RA patients. Conclusion: soluble PD-1 Is significantly higher in RA patients and positively correlates with DAS28. This result demonstrates that sPD-1 is associated with RA disease activity and is a biomarker of RA disease activity.