Urinary transforming growth factor-β1 excretion in renal allograft recipients during the early post-transplantation period

Background. Transforming growth factor-beta(1) (TGF-beta(1)), the major fibrogenic growth factor, is implicated in the pathogenesis of renal scarring in experimental and clinical nephropathies as well as in chronic allograft nephropathy. In this study we examined the pattern of changes of TGF-beta(1) excretion in the urine and the sites of TGF-beta(1) expression in the kidney of transplanted patients during the early post-transplantation period. Methods. Eighteen renal allograft recipients were included in the study. In all patients urinary TGF-beta(1) levels were determined by ELISA in sequential measurements during the first two postoperative months and compared to that of 14 healthy subjects. The renal expression of TGF-beta(1) protein was studied in 4 patients that underwent a biopsy of the transplanted kidney at the same period. All patients were treated with prednisolone, cyclosporin, and mycophenolate mofetil. Results. Urinary TGF-beta(1) levels were increased during the first postoperative days. Although they were gradually reduced during the first two post-operative months, they remained significantly higher compared to those of normal subjects (580+/-148 ng/24 h vs. 310+/-140 ng/24 h p<0.01). The decline of urinary TGF-beta(1) excretion followed that of serum creatinine. TGF-beta(1) protein expression was identified within the cytoplasm of tubular epithelial cells of transplanted patients. Conclusions. Elevated urinary TGF-beta(1) levels are observed during the early post-transplantation period in renal allograft recipients and are maintained high even after restoration of renal function to normal.