Antibody to transforming growth factor-beta ameliorates tubular apoptosis in unilateral ureteral obstruction

Background. Unilateral ureteral obstruction (UUO) is characterized by progr essive renal atrophy, renal interstitial fibrosis, an increase in renal tra nsforming growth factor-beta (TGF-beta), and renal tubular apoptosis. The p resent study was undertaken to determine the effect of a monoclonal antibod y to TGF-beta (ID11) in UUO. Methods. Mechanical stretch was applied to tubular epithelial cells (NRK-52 E) by a computer-assisted system. Three doses of 1D11 (either 0.5, 2, or 4 mg/rat) were administered to rats one day prior to UUO and every two days t hereafter, and kidneys were harvested at day 13. Fibrosis was assessed by m easuring tissue hydroxyproline and mRNA for collagen and fibronectin. Apopt osis was assessed with the terminal deoxy transferase uridine triphosphate nick end-labeling assay. TGF-beta levels were determined by bioassay. Weste rn blot and immunostaining were used to identify proliferating cell nuclear antigen (PCNA), p53, bcl-2, and inducible nitric oxide synthase (iNOS). Results. Stretch significantly induced apoptosis in NRK-52E cells, which wa s accompanied by an increased release of TGF-beta; 1D11 (10 mug/mL) totally inhibited stretch-induced apoptosis. Control obstructed kidney contained 2 0-fold higher TGF-beta as compared with its unobstructed kidney; 1D11 neutr alized tissue TGF-beta of the obstructed kidney. Control obstructed kidney exhibited significantly more fibrosis and tubular apoptosis than its unobst ructed counterpart, which was blunted by 1D11. In contrast, 1D11 significan tly increased tubular proliferation. p53 immunostaining was localized to re nal tubular nuclei of control obstructed kidney and was diminished by 1D11. In contrast, bcl-2 was up-regulated in the 1D11-treated obstructed kidney. Total NOS activity and iNOS activity of the obstructed kidney were increas ed by 1D11 treatment. Conclusion. The present study strongly suggests that an antibody to TGF-bet a is a promising agent to prevent renal tubular fibrosis and apoptosis in U UO.