GSE158230
Secretory Leukocyte Peptidase Inhibitor (SLPI) is a Novel Predictor of Tubulointerstitial Injury and Renal Outcome in Patients with Diabetic Nephropathy
Tubulointerstitial injury plays an important role in diabetic nephropathy (DN) progression; however, no reliable urinary molecule has been used to predict tubulointerstitial injury and renal outcome of DN clinically. In this study, based on tubulointerstitial transcriptome, we identified secretory leukocyte peptidase inhibitor (SLPI) as the molecule associated with renal fibrosis and prognosis of DN. In tubular cells, high glucose could upregulate SLPI, which bound with ß-catenin and GSK-3ß reciprocally, abolished the interaction between ß-catenin and GSK-3ß, diminished GSK-3ß-regulated ß-catenin phosphorylation and the subsequent ubiquitination and degradation, thus led to ß-catenin signaling activation and renal fibrosis. Db/db mice injected with adenovirus carrying Slpi-3xflag-GFP (Ad-Slpi-GFP) developed ß-catenin signaling activation in the proximal tubule, worse albuminuria and tubulointerstitial fibrosis. Conversely, Slpi knockout (KO) mice with STZ-induced DN developed less albuminuria, tubulointerstitial fibrosis and ß-catenin signaling activation. Furthermore, clinical studies showed that urinary SLPI protein level (uSLPI/Cr) had significant correlation with intrarenal SLPI mRNA and interstitial fibrosis. In an independent prospective cohort enrolled 711 patients with biopsy proven DN, uSLPI/Cr level was significantly associated with eGFR slope and improved the prediction value of renal outcome. Together, our study identified SLPI as a novel critical regulator for the progression of tubulointerstitial injury, which may be used as an independent risk predictor of DN progression. Overall design: We examined the effect of SLPI overexpression by gene expression profiling in HK-2 cells.