PAX2 re-expression in renal tubular epithelial cells and correlation with renal interstitial fibrosis of rats with obstructive nephropathy

Abstract

Objective: To investigate the effect of paired box 2 (PAX2) gene re-expression in renal tubular epithelial cells on renal interstitial fibrosis in rats with obstructive nephropathy. Methods: Wistar rats were randomly divided into two groups: sham-operated group (sham group) and unilateral ureteral obstruction group (UUO group), 40 in each group. After the surgery, rats were killed at 3, 5, 7, and 14 days (n = 10 each) to remove and collect kidneys. Morphological changes of the kidney were determined by histopathology. Protein and mRNA expression of PAX2 in the kidney were determined by immunohistochemistry, Western blot and real-time polymerase chain reaction (PCR). Results: The new major findings of this study include the following: (1) Hematoxylin and Eosin (HE) and Masson staining revealed obvious renal interstitial fibrosis in UUO group; (2) increased PAX2 expression was found in renal tubular epithelial cells in UUO group by immunohistochemistry, but not in sham group; (3) by Western blot, a significant increase in PAX2 protein level in UUO group was detected 3d after the surgery when compared to sham group (p < 0.05), which continued to increase with prolonged obstruction; the same pattern was also found in PAX2 mRNA expression by real-time PCR in UUO group after the surgery; (4) PAX2 protein level was positively correlated with the severity of renal tubular damage (r = 0.937 and p < 0.05) and the level of renal interstitial fibrosis (r = 0.987 and p < 0.05). Conclusion: In rats with obstructive nephropathy, embryonic development gene PAX2 is re-expressed in the renal tubules, which may participate in the pathogenesis of renal tubular damage and renal interstitial fibrosis.