Therapeutic Role of TGF-β–Neutralizing Antibody in Mouse Cyclosporin A Nephropathy

Morphologic Improvement Associated with Functional Preservation

Abstract

ABSTRACT. TGF-β is believed to play a central role in the development of Cyclosporin A (CsA)-induced nephropathy. This study investigated the effects of 1D11, a murine pan-specific TGF-β–neutralizing monoclonal antibody, in an ICR mouse model of chronic CsA nephropathy. Mice were administered a low-salt diet (0.01% sodium) for 1 wk followed by CsA treatment (30 mg/kg, subcutaneously, daily) for 4 wk. 1D11 was administered (2.5 mg/kg, intraperitoneally, 3 times/wk) beginning immediately after the termination of CsA dosing and continued through 8 wk. CsA caused extensive renal histopathologic alterations, including tubular damage, interstitial infiltrates and fibrosis, deposition of collagen III, and apoptosis of tubular epithelial cells. 1D11 ameliorated the CsA-induced histopathologic alterations, with significant reduction in collagen III expression and deposition. Additionally, elevated levels of mRNA encoding TGF-β1 and TGF-β2 were significantly reduced. 1D11 also protected tubular epithelial cells from apoptosis by 48% (P < 0.05). In contrast, 13C4 (a control antibody) had no significant effect on any of the endpoints described above. Importantly, the effects of 1D11 on the CsA-induced morphologic alterations were followed by a reduction in serum creatinine level when compared with CsA mice treated with 13C4 (13C4, 0.45 ± 0.09; 1D11, 0.30 ± 0.08; P < 0.05) after 8 wk of treatment. Endothelial nitric oxide synthase (eNOS), inducible NOS (iNOS), nitrotyrosine, and tissue hypoxia were examined by immunostaining using specific antibodies. eNOS was significantly reduced in the endothelium of arterioles in the kidneys of mice treated with CsA, whereas iNOS was induced in the cortical tubules. Tissue hypoxia was found in both the arterioles and tubules, whereas nitrotyrosine was localized in the tubules. Administration of 1D11 improved tissue hypoxia and reduced nitrotyrosine formation. Moreover, the reciprocal changes in iNOS and eNOS expression were normalized by 1D11. This study demonstrates that 1D11 administration ameliorated morphologic alterations and preserved renal function in the context of existing chronic CsA nephropathy. E-mail: [email protected]