Transforming growth factor-beta1 plasma levels in stable renal allograft recipients under different immunosuppression

Transforming growth factor-beta1 gene expression and cyclosporine A-induced gingival overgrowth: a pilot study

AIMS

The relationship between gingival overgrowth (GO) induced by cyclosporine A (CsA) and transforming growth factor-beta1 (TGF-beta1) remains unclear. The aims of the present study were to evaluate TGF-beta1 gene expression under different immunosuppressive treatments and its association with TGF-beta1 gene functional polymorphism and GO in renal transplant recipients.

MATERIAL AND METHODS

The study included 98 CsA-treated renal transplant recipients (with and without GO) and 44 tacrolimus-treated transplant patients (without GO). TGF-beta1 mRNA expression was measured using a real-time quantitative polymerase chain reaction assay. The levels were correlated with TGF-beta1 gene polymorphisms at codons 10 and 25, with different immunosuppressive treatment and GO.

RESULTS

The level of TGF-beta1 gene expression was insignificantly lower in the CsA-treated group compared with the tacrolimus group, and significantly lower in the group with GO compared with patients without GO. In tacrolimus- and CsA-treated patients, but not in patients with GO, the level of TGF-beta1 gene expression was associated with functional phenotypes of TGF-beta1. The incidence, degree and extent of GO were higher in recipients with lower TGF-beta1 gene expression.

CONCLUSIONS

Lower level TGF-beta1 gene expression, not functional polymorphism, in patients treated with CsA may be considered to be a risk factor for GO.

Profibrotic cytokines and lymphocyte proliferation in stable renal allograft recipients treated with or without cyclosporine A

Profibrotic cytokines such as transforming growth factor-beta 1 (TGF-beta1) and endothelin-1 (ET-1) are involved in the pathogenesis of chronic allograft nephropathy. We assessed the effect of maintenance immunosuppression with or without cyclosporine A on TGF-beta1 and ET-1 expression as well as lymphocyte proliferation in renal allograft recipients. Patients were divided into groups according to their maintenance immunosuppression: A, azathioprine + methylprednisolone; B, cyclosporine A + azathioprine + methylprednisolone. TGF-beta1 and ET-1 plasma concentrations were not different between both groups. TGF-beta1 concentrations in cell culture supernatants and lymphocyte proliferation were higher in group B as compared to group A. No correlation was found between TGF-beta1 plasma concentrations and lymphocyte proliferation. Multiple linear regression analysis revealed that patient characteristics influence TGF-beta1 and ET-1 expression. In conclusion, plasma levels of profibrotic cytokines do not reflect the existing profibrotic potential of immunosuppressive drugs. Demographic factors and the employed co-medication confound the results.

Molecular comparison of calcineurin inhibitor-induced fibrogenic responses in protocol renal transplant biopsies

The calcineurin inhibitor cyclosporine (CsA) induces a fibrogenic response that may lead to scarring of the renal allograft. This study investigated whether tacrolimus, a novel calcineurin inhibitor, exerts fibrogenic effects to a similar extent. Sixty patients were enrolled in a randomized study: 29 received CsA, and 31 received tacrolimus. Patients were subjected to tailored exposure-controlled calcineurin inhibitor regimens. Protocol biopsies were obtained at the time of transplantation and 6 and 12 mo after transplantation. Cortical TGF-beta and collagens alpha1(I) and alpha1(III) mRNA steady-state levels were determined with real-time PCR. The extent of protein deposition of TGF-beta, alpha-smooth muscle actin, and interstitial collagens in the renal cortex was quantified with computer-assisted image analysis. The extent of interstitial collagen deposition measured with Sirius red and the accumulation of alpha-smooth muscle actin and TGF-beta protein after 6 and 12 mo were similar for both immunosuppressive regimens. mRNA levels of TGF-beta and collagens alpha1(I) and alpha1(III) were not significantly different in the treatment groups either. It is concluded that the fibrogenic response in renal allografts is similar in patients who receive CsA-based regimens and patients who receive tacrolimus-based regimens.