Clinical significance of sPD-1 and sPD-L1 in serum and urine of children with primary nephrotic syndrome

Abstract

Objectives To detect the level of soluble programmed death 1 (sPD-1) and soluble programmed death ligand 1 (sPD-L1) in serum and urine of children with primary nephrotic syndrome (PNS), and explore its clinical significance. Methods From July 2017 to November 2017, children with PNS admitted to the Children's Hospital Affiliated to Soochow University were divided into onset group (36 cases) and remission group (33 cases). Thirty healthy children who underwent medical examination for enrollment, undersize or overweight in the outpatient department of pediatric health care and inpatient department of Endocrinology were selected as healthy control group. Serum and urine samples were collected, in which the levels of sPD-1 and sPD-L1 were detected by enzyme-linked immunosorbent assay (ELISA). The correlation between serum and urine sPD-1, sPD-L1 levels and lymphocyte subsets, urinary protein were analyzed by Pearson and Spearman correlation analysis. Results The level of sPD-1 in serum was lower in remission group than those in healthy control group [1.60(0.48, 8.15) ng/ml vs 7.38(2.15, 19.02) ng/ml, P<0.01]. The level of urinary sPD-1 in onset group was higher than that in remission group [1.21(0.61, 2.56) pg/μg vs 0.51(0.31, 0.97) pg/μg, P<0.001] and healthy control group [1.21(0.61, 2.56) pg/μg vs 0.82(0.34, 1.15) pg/μg, P<0.01]. The levels of sPD-L1 in serum and urine were higher in onset and remission group than those in healthy control group (P<0.001). The level of sPD-1 in the serum was positive correlated with the numbers of CD3+, CD3+CD4+, CD3+ CD8+ T lymphocytes and CD3-CD19+, CD19+CD23+ B lymphocytes (r=0.537, 0.478, 0.454, 0.429 and 0.374; P=0.002, 0.008, 0.012, 0.018 and 0.042). The level of sPD-1 in the urine had positive relation with the ratio of 24 hours urinary albumin and weight (24 h UmAlb/Wt), N-acetylglucosaminidase and urinary creatinine (UNAG/Cr) and β2 microglobulin and urinary creatinine (Uβ2MG/Cr) (r=0.409, 0.588 and 0.276; P=0.016, 0.000 and 0.032). Conclusions The dynamic changes of sPD-1 and sPD-L1 in serum and urine suggested that PD-1/PD-L1 signaling pathway is involved in the development process of childhood primary nephrotic syndrome. Key words: Nephrotic syndrome, Primary; Children; Lymphocyte subsets; Soluble programmed death 1; Soluble programmed death ligand 1