Diltiazem induces regulatory T cells in vitro by modulating human dendritic cell maturation.

Diltiazem is a calcium channel antagonist that has been commonly associated with currently used immunosuppressants to prevent acute graft rejection in humans. In this study, we examined the possibility that diltiazem may affect human dendritic cell (DC) functions in response to lipopolysaccharide (LPS) stimulation and may induce the generation of DC with the capacity to generate CD4(+) regulatory T cells (Tregs). Blood monocytes were cultured in the presence of diltiazem at the beginning of their differentiation process into DC. Monocyte-derived DCs were stimulated with LPS, and DCs differentiated in the presence of diltiazem showed a decreased interleukin (IL)-12 production and an enhanced IL-10 production. When cultured with CD4(+) CD45RA(+) they were able to enhance the CD4(+) Foxp3(+) T-cell population and to induce slowly proliferating T cells, which showed a significant increase of transforming growth factor (TGF)-ß production. These T cells suppress proliferation of activated autologous T cells, and we show that this effect is attributable to soluble factors, primarily to TGF-ß. Blockade of TGF-ß by specific monoclonal antibodies reversed this inhibitory effect. Herein, we provide new evidence that diltiazem-conditioned monocyte-derived DC induce T cells which acquire a regulatory phenotype and activity similar to those described for Tregs.

Cholera toxin B subunit promotes the induction of regulatory T cells by preventing human dendritic cell maturation.

Cholera toxin B subunit (CTB) is an efficient mucosal carrier molecule for the generation of immune responses to linked antigens. There is also good evidence that CTB acts as an immunosuppressant, as it is able to down-modulate human monocyte/macrophage cell line activation and to suppress Th1-type responses. In the present study, we examined the possibility that recombinant CTB (rCTB) may affect human dendritic cell (DC) functions in response to LPS stimulation and may induce the generation of DC with the capacity to generate CD4(+) regulatory T cells (Tregs). Our findings show that rCTB partially prevents the LPS-induced maturation process of monocyte-derived DC (MDDC) and decreases their IL-12 production with no relevant effect on IL-10 production. LPS-stimulated MDDC pretreated with rCTB are able to promote the induction of low proliferating T cells, which show an enhanced IL-10 production associated with a reduced IFN-gamma production and the same high levels of TGF-beta as the control. These T cells suppress proliferation of activated autologous T cells. Transwell experiments and blockade of IL-10R and TGF-beta showed that the immunomodulatory effect is mediated by soluble factors. Thus, T cells induced by rCTB-conditioned MDDC acquire a regulatory phenotype and activity similar to those described for type 1 Tregs.

Liver transplantation in Italy: analysis of risk factors associated with graft outcome.

OBJECTIVE: To analyze the graft outcome after liver transplantation in Italy in the years 1995 to 2000. METHODS: We performed a longitudinal study with follow-up at 3 months, 1 year, 3 years, and 5 years on 1987 liver grafts. The effect of several variables on graft survival was also analyzed. RESULTS: Several variables affect graft survival: Donor and recipient older age, gender mismatching, prolonged cold ischemia time, acute hepatic necrosis, and retransplantation are reported to significantly affect liver graft survival. Donors older than 60 years show a relative risk of 1.59 (95% CI, 1.23-2.05) compared with donors with an age between 19 and 60 years; recipients older than 50 years show a relative risk of 1.29 (95% CI, 1.04-1.60) compared with recipients aged 19 to 50 years. A cold ischemia time of 12 hours or longer doubled the risk of failure (relative risk = 2.01, 95% CI, 1.36-2.96) compared with a cold ischemia time of less than 6 hours. CONCLUSIONS: The results show that the overall quality of liver transplantation in Italy is satisfying and comparable to the outcome reported by international registries. Follow-up studies on large numbers of liver transplants are useful to define predictors of outcome, and subsequently modify the criteria for organ allocation.

Kidney graft survival in Italy and factors influencing it.

PURPOSE: National registry data are often a suitable basis for examination of transplant outcomes. Using data supplied by the Italian National Transplant Registry, established in 1995, we performed the first nationwide analysis of this kind. METHODS: A retrospective analysis of 4893 recipients of cadaveric kidneys transplanted in all Italian centers from 1995 through 2000 was done to study 5-year graft survival. The association between some donor and recipient variables and outcomes in renal transplantation was analyzed. Graft survival was 93% at 3 months, 89% at 1 year, 82% at 3 years, and 80% at 5 years after transplantation. RESULTS: A significant association between graft survival and donor age (old vs young, relative risk [RR] = 1.62, 95% CI 1.27-2.06) and recipient age (old vs young, RR = 1.25, 95% CI 1.02-1.53). Graft survival was also associated with cold ischemia time (24-36 hours, RR= 1.39, 95% CI 1.05-1.85 and >36 hours, RR= 1.94, 95% CI 1.32-2.86 vs 0-24 hours) and donor/recipient sex mismatch (female/male vs male/male, RR= 1.50, 95% CI 1.17-1.93). CONCLUSION: The quality of kidney transplantation in Italy is satisfactory and is comparable to that in other developed countries. Furthermore, our experience confirms that both donor and recipient factors are major determinants of renal allograft function.