The effect of cyclosporin A and tacrolimus on cultured human epithelial cells: the role of TGF-beta

Predictors of renal function following lung or heart-lung transplantation

BACKGROUND

Renal failure is a common complication following non-renal solid organ transplantation. The purpose of our study was to define the rate of decline in renal function and to identify independent risk factors associated with renal failure following lung or heart-lung transplantation.

METHODS

Between May 1986 and December 1998, 219 patients underwent lung or heart-lung transplantation at the University of Minnesota and survived at least six months (33 heart-lung, 66 bilateral single lung, and 120 unilateral single lung transplants). The mean age at the time of transplant was 45.9 +/- 11.6 years (mean +/- SD; range, 15 to 65 years), and the mean pre-transplant serum creatinine level was 0.88 +/- 0.19 mg/dL. All patients were treated with a calcineurin inhibitor (164 cyclosporine, 55 tacrolimus).

RESULTS

During the follow-up period (median 44 months, range 6.8 to 163 months), 16 patients (7.3%) developed end-stage renal disease. The cumulative incidence of doubling of serum creatinine was 34% at one year, 43% at two years and 53% by five years. Factors associated with the primary end point of the time to doubling of the baseline serum creatinine by proportional hazards regression were cumulative periods with diastolic blood pressure greater than 90 mm Hg [relative risk (RR) 1.30, P = 0.02] and the serum creatinine value at one month post-transplantation (RR 1.28, P = 0.03). Use of tacrolimus during the first six months after transplantation was associated with a significant decrease in the risk for time to doubling of serum creatinine (RR 0.38, P = 0.009) and a lower rate of acute rejection.

CONCLUSIONS

These results suggest that potential renoprotective strategies following lung or heart-lung transplantation include avoidance of peri-transplant renal injury, diligent blood pressure control, and preferential use of tacrolimus over cyclosporine.

Replicative senescence of biliary epithelial cells precedes bile duct loss in chronic liver allograft rejection: increased expression of p21(WAF1/Cip1) as a disease marker and the influence of immunosuppressive drugs

Early chronic liver allograft rejection (CR) is characterized by distinctive cytological changes in biliary epithelial cells (BECs) that resemble cellular senescence, in vitro, and precede bile duct loss. If patients suffering from early CR are treated aggressively, the clinical and histopathological manifestations of CR can be completely reversed and bile duct loss can be prevented. We first tested whether the senescence-related p21(WAF1/Cip1) protein is increased in BECs during early CR, and whether treatment reversed the expression. The percentage of p21+ BECs and the number of p21+ BECs per portal tract is significantly increased in early CR (26 +/- 17% and 3.6 +/- 3.1) compared to BECs in normal liver allograft biopsies or those with nonspecific changes (1 +/- 1% and 0.1 +/- 0.3; P: < 0.0001 and P: < 0.02), chronic hepatitis C (2 +/- 3% and 0.7 +/- 1; P: < 0.0001 and P: < 0.04) or obstructive cholangiopathy (7 +/- 7% and 0.7 +/- 0.6; P: < 0.006 and P: = 0.04). Successful treatment of early CR is associated with a decrease in the percentage of p21+ BECs and the number of p21+ BECs per portal tract. In vitro, nuclear p21(WAF1/Cip1) expression is increased in large and multinucleated BECs, and is induced by transforming growth factor (TGF)-beta. TGF-beta1 also increases expression of TGF-beta receptor II, causes phosphorylation of SMAD-2 and nuclear translocation of p21(WAF1/Cip1), which inhibits BEC growth. Because conversion from cyclosporine to tacrolimus is an effective treatment for early CR, we next tested whether these two immunosuppressive drugs directly influenced BEC growth in vitro. The results show that cyclosporine, but not tacrolimus, stimulates BEC TGF-beta1 production, which in turn, causes BEC mito-inhibition and up-regulation of nuclear p21(WAF1/Cip1). In conclusion, expression of the senescence-related p21(WAF1/Cip1) protein is increased in BECs during early CR and decreases with successful recovery. Replicative senescence accounts for the characteristic BEC cytological alterations used for the diagnosis of early CR and lack of a proliferative response to injury. The ability of cyclosporine to inhibit the growth of damaged BECs likely accounts for the relative duct sparing properties of tacrolimus.

TGF-beta expression in renal transplant biopsies: a comparative study between cyclosporin-A and tacrolimus

BACKGROUND

Chronic rejection is a major cause of graft dysfunction after kidney transplantation. This fibroproliferative disease may be promoted by overproduction of transforming growth factor beta (TGF-beta). Previous studies have suggested that CsA might increase production of this growth factor. The current study was designed to measure the expression of TGF-beta(b) in renal transplant biopsy specimens from patients undergoing immunosuppressive therapy with either CsA or tacrolimus (FK506).

METHOD

Paraffin-embedded renal biopsy specimens were sectioned, dewaxed, and incubated with primary antibody against TGF-beta(b)1 latency-associated protein and active TGF-beta(b1). After washing, the sections were treated with secondary antibody conjugated with FITC. In each case, the sections were assessed by semi-quantitative scanning laser confocal microscopic method.

RESULTS

There was no significant difference in latent TGF-beta(b) expression between biopsy specimens from patients receiving CsA and patients receiving FK506. However, biopsy specimens from patients receiving CsA expressed significantly more active TGF-beta(b1) than biopsy specimens from patients receiving FK506 (P<0.0001, Mann-Whitney test).

DISCUSSION

The increased level of active TGF-beta1 expression in renal biopsy specimens of patients receiving CsA may indicate a mechanism of chronic rejection. However, these biopsies were performed to assess deranged renal function; therefore, the specimens may reflect events rather than differences in medication.

Which calcineurin inhibitor is preferred in renal transplantation: tacrolimus or cyclosporine?

Cyclosporine and tacrolimus are potent inhibitors of the calcineurin-dependent cytokine synthesis in activated lymphocytes. In renal transplant patients tacrolimus is more powerful in preventing severe and refractory rejections, even when compared with the new cyclosporine microemulsion formulation. Both drugs are equally nephrotoxic, but tacrolimus induces less hypertension and less pronounced hyperlipidaemia. Especially in some categories of patients, a higher incidence of de-novo diabetes mellitus is seen with tacrolimus therapy.