TGF-β1 mRNA upregulation influences chronic renal allograft dysfunction

Acute rejection (AR) is a dominant risk factor for developing chronic allograft nephropathy (CAN) after kidney transplantation. CAN is characterized by progressive interstitial fibrosis. It has been associated with increased transforming growth factor (TGF)-β1 expression, however, kinetic studies are absent. We investigated whether intragraft TGF-β1 expression in various causes of early graft dysfunction may influence late renal allograft dysfunction. A total of 174 human renal biopsies were quantified for TGF-β1 mRNA expression using real-time reverse transcriptase-polymerase chain reaction. Expression levels were correlated with the Banff histopathological grades, TGF-β1 immunohistology, and clinical follow-up. TGF-β1 was most markedly upregulated in AR, CAN, and acute tubular necrosis – delayed graft function compared to non-rejecting controls (P<0.001). TGF-β1 expression was heightened in borderline changes (P<0.01), recurrence of glomerulonephritis, and cyclosporine toxicity (P<0.05). There was no correlation between intragraft TGF-β1 expression during AR and short-term outcome of a rejection episode. TGF-β1 gene overexpression during CAN has been shown to be associated with the increased risk for renal allograft dysfunction 18 months after biopsy (odds ratios 9.9 vs 3.2, respectively). Intragraft TGF-β1 mRNA expression is significantly upregulated in both AR and CAN. Thus, our results support the hypothesis that TGF-β1 might play a key role in chronic allograft dysfunction.