Programmed death 1 (PD-1) serum level and gene expression in recent onset systemic lupus erythematosus patients

Aim of the workTo investigate the potential association of protein programmed death 1 (PD-1) serum level and its gene expression inrecent onset systemic lupus erythematosus (SLE) patients and study its association with the disease activity.Patients and methodsThe study included 80 recently diagnosed SLE patients and 80 healthy controls. SLE disease activity index (SLEDAI) was assessed. The serum level of soluble (sPD-1) was assessed by enzyme linked immunosorbent assay (ELISA) and its gene expression level was evaluated by real time-polymerase chain reaction (RT-PCR).ResultsThey were 68 females and 12 males (F: M 5.7:1) with age 30.8 ± 8.7 years and disease duration of 3.2 ± 1.7 months. The sPD-1 and PD-1 gene expression level (folds) were significantly elevated in patients (1280.6 ± 1448.1 pg/ml and 0.3 ± 0.06 folds) than controls (109.1 ± 11.9 pg/ml and 0.03 ± 0.008 folds) (p < 0.001). A significant correlation was found between sPD-1 and hematuria, pyuria, fever and C3 level (p = 0.01, p = 0.001, p = 0.02, and p = 0.03 respectively), and between PD-1gene expression and psychosis and fever (p = 0.03, p = 0.014). No significant correlation was found between SLEDAI and PD-1 gene expression or sPD-1 level (p = 0.1, p = 0.23 respectively). No significant correlation was found between sPD-1 and PD-1 gene expression levels and the autoantibodies.ConclusionPD-1 gene expression as well as the serum level of sPD-1 are elevated significantly in recent onset SLE patients denoting that they may have a role in the pathogenesis of the disease while there was no relation to the disease activity. This biomarker may be potentially promising for the development of a novel lupus immunotherapy by targeting the PD-1 pathway.