Urinary soluble CD90 predicts renal prognosis in patients with diabetic kidney disease

Background: Diabetic kidney disease (DKD), the major cause of chronic kidney disease, is associated with progressive renal fibrosis. The expression of CD90 correlated with fibrogenesis. However, the association between urinary soluble CD90 and renal disease severity, and whether it predicts outcomes in patients with DKD are still unclear. Methods: Urinary sCD90 was measured in 285 patients with DKD in a longitudinal cohort. The composite endpoint was defined as end-stage renal disease (ESRD) or 40% reduction of estimated glomerular filtration rate (eGFR). The associations between urinary sCD90/Cr and clinical parameters, as well as renal outcomes were evaluated. Moreover, we detected the intrarenal CD90 expression, and demonstrated the correlation of intrarenal CD90 with clinico-pathological parameters. Results: The urinary sCD90 level of DKD patients is significantly higher than diabetes patients without kidney injuries and healthy controls. We further showed urinary sCD90/Cr had significantly correlations with eGFR (r=-0.373, P<0.001), uACR (r=0.303, P<0.001), serum creatinine (r=0.344, P<0.001), and the eGFR slope (r=-0.27, P<0.001). Elevated urinary sCD90/Cr was an independent risk factor for the composite endpoint, adjustment for potential confounders in DKD patients (HR 1.20, 95% CI: 1.04-1.38, P=0.015). However, the CD90 expression in the renal tubulointerstitial compartment in DKD patients was significantly lower than healthy controls, and showed significant negative correlations with the interstitial fibrosis and tubular atrophy score (IFTA) (r=-0.3, P=0.047), and urinary sCD90/Cr (r=-0.399, P=0.029). Conclusions: This study provided evidence that urinary sCD90 could reflect the disease severity and serve as a valuable factor for renal outcome prediction in patients with DKD.