Increased urinary excretion of transforming growth factor-β1 in renal transplant recipients during cytomegalovirus infection

Aims: Cytomegalovirus (CMV) is a suggested risk factor for chronic allograft nephropathy, and transforming growth factor-beta (TGF-beta) is a key fibrogenic molecule in this process. CMV has been shown to induce the expression of TGF-beta and several cytokines. We analyzed the impact of CMV on urinary excretion of TGF-beta, ICAM-1, TNF-alpha and correlated findings with biopsy histology. Material: Urine samples from 46 renal transplant recipients were available for the study. Urine samples were taken when CMV infection was suspected, or for controlling of proteinuria or bacteriuria. Method: CMV was diagnosed by antigenemia and viral cultures. Patients with previous CMV infection were excluded from the analysis. Urine samples were analyzed by ELISA-method to detect the levels of TNF-alpha, ICAM-1 and TGF-beta(1). Banff '97 criteria were used for scoring of protocol biopsies taken 6 months after transplantation. Results: At the time of the urine collection, 13/46 patients had CMV infection. Eight patients with no CMV infection were used as controls. TGF-beta(1) was significantly increased in the CMV group (samples taken mean 137 79 days post-transplantation) compared to controls (samples 139 64 days post-transplantation) (51.1 +/- 28.0 vs. 13.3 +/- 6.7 ng/mmol crea,p < 0.001). No differences in the levels of other molecules were recorded. In the biopsies, interstitial fibrosis was significantly increased in the CMV group compared to controls. Conclusions: Urinary excretion of TGF-beta(1) was increased in patients during CMV infection. This was associated with increased fibrosis in the biopsies. (c) 2005 Elsevier B.V. All rights reserved.