Reducing serum uric acid attenuates TGF-ß1-induced profibrogenic progression in type 2 diabetic nephropathy.

BACKGROUND: The pivotal role of transforming growth factor-ß1 (TGF-ß1)-induced tubulointerstitial fibrosis in the progression of chronic kidney disease is an active topic of research. Recent evidence indicates that hyperuricemia is associated with increased TGF-ß1 and progressive tubulointerstitial injury. We examined the hypothesis that lowering serum uric acid attenuates TGF-ß1-induced profibrogenic tubular change in type 2 diabetic nephropathy. METHODS: KK-A(y)/Ta mice, an animal model of type 2 diabetes, were provided access to either regular drinking water or drinking water containing 10 mg/dl of allopurinol. Normal rat kidney epithelial cells were cultured and stimulated with 5 mM uric acid with or without allopurinol. RESULTS: Type 2 diabetic mice that received allopurinol exhibited smaller increases in urinary albumin:creatinine ratio than diabetic control mice, as well as attenuated TGF-ß1 and Smad pathway-induced profibrogenic tubular changes in diabetic kidneys. Allopurinol attenuated TGF-ß1-induced Smad pathway activation in tubular cells. These findings were related to increases in E-cadherin, and decreases in vimentin and α-smooth muscle actin. Uric acid-induced upregulation of TGF-ß1 depends on mitogen-activated protein kinase signaling. CONCLUSIONS: This is the first study to demonstrate that reducing serum uric acid has preventive effects against to profibrogenic progression in type 2 diabetic kidney disease. These findings suggest that lowering serum uric acid may be an effective therapeutic intervention to prevent the progression of type 2 diabetic kidney disease.

Validation study of peripheral blood diagnostic test for acute rejection in kidney transplantation.

BACKGROUND: Diagnosing acute rejection (AR) in kidney transplant recipients typically requires an invasive kidney biopsy. A previous study has suggested that expression of five genes in peripheral blood can indicate the presence of AR in American pediatric kidney transplant recipients. This study aims to validate if these five genes are also useful to diagnose AR in Korean adult kidney transplant patients. METHODS: Blood samples were collected from 143 patients (39 biopsy-proven AR, 84 stable patients, and 20 other graft injuries) at an average of 9 months posttransplantation and performed real-time PCR for five-gene biomarkers (DUSP1, NKTR, MAPK9, PSEN1, and PBEF1). RESULTS: Patients with acute cellular rejection (ACR) had a significantly decreased level of MAPK9 and a significantly increased level of PSEN1 when compared with controls and also with patients with other graft injury (OGI). In multivariate logistic regression analysis, for discrimination between ACR and OGI, an excellent diagnostic accuracy was observed in the gene sets but five-gene set generated a higher AUC than two-gene set. With clinical variables combined to these gene sets, the diagnostic accuracy increased in both five-gene set and two-gene set. CONCLUSIONS: These results support the validity of 5 gene-set for the prediction of AR in Asian adult kidney transplant recipients and suggest the promising role of the peripheral blood gene test in the diagnosis of AR in kidney transplantation.