Novel evidence demonstrates that epithelial-mesenchymal transition contributes to nephrolithiasis-induced renal fibrosis.

Purpose: To investigate fibrotic lesions in renal tissues obtained from patients with large calculi, and to selectively evaluate the expression and clinical significance of Twist and E-cadherin in nephrolithiasis patients.

Methods: We recruited 50 patients with kidney stone and 32 matched healthy controls. We determined plasma creatinine (Cr) and corrected Cr clearance (CCr). For the 50 patients, we detected daily urine protein excretion. At the end of percutaneous nephroscopic lithotomy, we performed puncture biopsy to acquire kidney tissue. We obtained normal control kidney tissues from non-nephrolithiasis patients who received a surgical biopsy during open surgery. We determined the expression of Twist and E-cadherin by immunohistochemical staining and scored it with clinical parameters. In addition, we analyzed the degree of expression of Twist and its correlation with long-term renal survival.

Results: Overall, the renal function of patients significantly decreased, as indicated by Cr and reduced CCr compared with healthy controls. Activated Twist was strongly expressed in tubular epithelial cells from kidneys of nephrolithiasis patients, whereas we found little positive staining of Twist in normal kidneys. Meanwhile, the expression of E-cadherin was significantly suppressed in kidneys of nephrolithiasis patients. Twist expression was inversely correlated with E-cadherin expression; using multivariate analysis, data showed that the factors influencing renal survival in patients were CCr (relative ratio, 4.39; 95% confidence interval, 1.34-14.38; P = 0.013) and the extent of Twist expression (relative ratio, 3.45; 95% confidence interval, 1.10-10.68; P = 0.033).

Conclusions: Our data suggest that the possible novel EMT marker molecule Twist and Twist staining might be a valuable index predicting renal fibrosis progression in human nephrolithiasis.