T Nagao

Kinetics of unresponsiveness induced by a short course of cyclosporin A.

The kinetics of unresponsiveness induced by a short course of cyclosporin A was studied using accessory heart allografts in rats. Skin grafts from the heart donor or a third-party donor were performed at several different times after heart transplantation. The fate of the skin and heart grafts demonstrated that the properties of the unresponsive state induced by short-term cyclosporin A therapy changed with time so that three different stages could be recognized: (1) stable nonspecific immunosuppression, (2) weak moderately specific immunosuppression, and (3) strong stable donor-specific immunosuppression.

Immunosuppressant pharmacodynamics on lymphocytes from healthy subjects and patients with chronic renal failure, nephrosis, and psoriasis: Possible implications for individual therapeutic efficacy

In organ transplantation, patients with peripheral blood mononuclear cells (PBMCs) that exhibit resistance to cyclosporine (INN, ciclosporin) or glucocorticoids in vitro are refractory to therapy based on these drugs in vivo. However, detection or distribution of the resistant patients with immunologic disorders remains to be documented.

Glucocorticoids and cyclosporine induce apoptosis in mitogen-activated human peripheral mononuclear cells

Induction of apoptosis by immunosuppressive agents such as glucocorticoids (GCs) and cyclosporine (CsA) in cultured lymphoid cells has been suggested. However, there are few studies which demonstrate the induction of apoptosis by these agents in the activation process of human peripheral blood mononuclear cells (PBMCs). Here we show that potent immunosuppressive GCs and CsA induce apoptosis in concanavalin A (con A)-activated human PBMCs. In this study, GCs and CsA suppressed human PBMC-blastogenesis when activated by con A in a dose-dependent manner, where healthy PBMCs treated with > 100 ng/ml of each immunosuppressive agent exhibited a DNA-ladder structure in electrophoretic analysis. In three chronic renal failure (CRF) patients, dose-dependency of the PBMC-apoptosis induction was confirmed by our quantification of fragmented DNA using ELISA. Furthermore, the enrichment of DNA fragmentation was significantly associated with the rate of PBMC-blastogenesis when treated with GCs or CsA (r = -0.466, P < 0.01). These results suggested that suppression of the mitogen-induced PBMC-blastogenesis by the immunosuppressive agents should be correlated with the induction of apoptosis.

Comparative study of the cellular pharmacodynamics of calcineurin inhibitors between patients with chronic renal failure awaiting renal transplantation and cirrhosis patients awaiting liver transplantation.

The in vitro response of peripheral blood mononuclear cells (PBMCs) to the suppressive effects of calcineurin inhibitors is known to correlate with the clinical efficacy of drugs used in renal transplantations. The present study was conducted to examine the differences of PBMC responses to calcineurin inhibitors between chronic renal failure (CRF) patients awaiting renal transplantation and cirrhosis patients awaiting liver transplantation. The study included 99 CRF patients awaiting renal transplantation and 27 cirrhosis patients awaiting liver transplantation. Twenty milliliters of venous blood was taken 1–7 days before transplantation. The in vitro drug concentrations giving 50% inhibition of PBMC blastogenesis stimulated with concanavalin A (IC50s) were calculated. The suppressive effects of tacrolimus against PBMC blastogenesis were more than 10–100 times stronger than those of cyclosporine. The median IC50 value for cyclosporine against the CRF PBMCs was not significantly different from the median IC50 value against the cirrhosis PBMCs. In contrast, tacrolimus sensitivity in cirrhosis PBMCs is approximately seven times higher than that in CRF PBMCs. The median IC50 value for tacrolimus against cirrhosis PBMCs was significantly lower and therefore the effect was stronger in comparison to the CRF PBMCs (p < 0.001). These data suggest that the PBMCs of cirrhosis patients, in comparison to those of CRF patients, are highly sensitive to the suppressive effect of tacrolimus. However, PBMC sensitivity to cyclosporine was not significantly different between the CRF and cirrhosis patients. These observations raise the possibility that treatment with tacrolimus, rather than cyclosporine, may therefore be a better choice to reduce the risks of allograft rejection in liver transplantation.

A comparison of prednisolone and methylprednisolone for renal transplantation.

A large difference in immunosuppressive potency between methylprednisolone and prednisolone has been suggested in vitro. However, the selection of the best glucocorticoid for renal transplantation has been seldom considered so far. Thus, the present study was undertaken to compare therapeutic efficacy between prednisolone and methylprednisolone in renal transplantation. We studied 42 renal transplant recipients who were operated on between 1990 and 1994. The patients were divided into two treatment groups: a methylprednisolone/cyclosporine group (n=19) and a prednisolone/cyclosporine group (n=23). Clinical outcome and drug side effects were compared retrospectively between the treatment groups 24–84 months after transplantation. The overall graft survival time in patients treated with methylprednisolone/cyclosporine was superior to that in patients treated with prednisolone/cyclosporine (p<0.05). Among the recipients from cadaver donors, 5/16 (31.3%) treated with prednisolone required nephrectomy, whereas none of the 10 patients treated with methylprednisolone received nephrectomy (p<0.01). An examination of the recipients from living related donors revealed that serum creatinine levels 24–36 months after operation were significantly lower in the methylprednisolone group (p<0.05). Cyclosporine trough levels and glucocorticoid side effects were similar between the treatment groups. The results raised the possibility that methylprednisolone is superior to prednisolone when combined with cyclosporine for maintenance immunosuppressive therapy in renal transplantation.

Glucocorticoid-resistance in peripheral-blood lymphocytes does not correlate with number or affinity of glucocorticoid-receptors in chronic renal failure patients

Glucocorticoid (GC) resistance in patients with chronic renal failure (CRF) seriously impairs successive GC therapy after renal transplantation. We examined the relationship between GC-receptor (GC-R) parameters in peripheral-blood mononuclear cells (PBMC) and PBMC resistance to GC in 21 CRF patients and 18 healthy subjects. Each subject group was divided into two subgroups according to PBMC sensitivity to prednisolone in a mitogen assay procedure; i.e., sensitive (IC50 < 381 ng/mL) and resistant (IC50 > 381 ng/mL) groups. In healthy subjects, the mean GC-R Bmax and Kd in quiescent PBMC of the GC-sensitive group were 2.89 +/- 1.23 fmol/10(6) cells and 4.00 +/- 2.24 nM, respectively. The Bmax in these subjects significantly increased to 6.61 +/- 2.02 (257.7 +/- 107.8%) after 24 h stimulation with concanavalin A (p < 0.01), while the Kd change was not significant. The GC-R Bmax and Kd in quiescent PBMC of the GC-resistant group were 5.33 +/- 1.37 fmol/10(6) cells and 3.20 +/- 1.39 nM, respectively. Both of these parameters, however, did not change significantly after mitogen stimulation. There was a significant negative correlation between IC50S of prednisolone and increase-ratios (post/pre ratio) of Bmax after mitogen stimulation (p < 0.05). In CRF patients, Bmax and Kd in quiescent PBMC of the GC-sensitive group were 6.04 +/- 2.35 fmol/10(6) cells and 3.49 +/- 1.72 nM, respectively, while those in PBMC of the GC-resistant group were 5.13 +/- 2.31 fmol/10(6) cells and 4.04 +/- 1.62 nM, respectively. The Bmax and Kd were not significantly changed after mitogen stimulation in both subgroups of CRF. Moreover, in contrast to healthy subjects, there was no correlation between IC50 and GC-R parameters in CRF. We concluded that, in healthy subjects, decreased PBMC capacity to amplify GC-R numbers in response to mitogen is correlated with GC resistance, whereas in CRF patients the resistant mechanism is not correlated with GC-R parameters. An unknown event might be involved in GC-resistance of CRF.

Evidence of Different Pharmacokinetics Between Cyclosporine and Tacrolimus in Renal Transplant Recipients: Why Cyclosporine Is Monitored by C2 Level and Tacrolimus by Trough Level

The clinical efficacy of calcineurin inhibitors administered to renal transplant recipients is considered to be a strong function of the area under the concentration time curve (AUC). Monitoring of blood concentrations for two similar calcineurin inhibitors, cyclosporine (CyA) and tacrolimus (TAC) are different. Namely, CyA blood concentration is usually monitored at two hours after administration (C2), a surrogate for peak concentration (Cp), and TAC at trough concentration (Ct). We examined the behavior of blood concentration curves simultaneously for both CyA and TAC in renal transplant recipients with similar clinical backgrounds. Furthermore, we analyzed the correlation of Cp and Ct vs AUC implementing an area under the trough level, or area above the trough level as new pharmacokinetic parameters, so that C2 for CyA and Ct for TAC has validated using controlled clinical data. We observed differences in the pharmacokinetics between.

Biliary Complications After 52 Adult Living Donor Liver Transplantations: A Single-Center Experience

OBJECTIVE The incidence of biliary complications after adult living donor liver transplantation (ALDLT) are still high even though various devices have been reported to overcome them. METHOD From October 2000 to April 2007, we performed 52 ALDLTs which included 15 ABO-incompatible grafts. Median follow-up was 565 days. In 49 procedures, we used duct-to-duct anastmosis with a stent inserted in the recipient duct and out through the common bile duct wall as an external stent, and in 3 procedures, we used duct-to-jejunostomy anastomosis. We investigated postoperative biliary complications and their management. RESULTS Forty-four patients received right lobe grafts and 8 received left lobe grafts. Among patients in whom duct-to-duct anastomosis was used, nine (20.5%) developed biliary complications including bile leakage in five and biliary strictures in four. All bile leakage was treated with reoperation. Three biliary strictures were treated with stent placement, and one biliary stricture was treated with magnetic compression anastomosis. Among the three patients in whom duct-to-jejunostomy was used, two (66.7%) had bile leakage and stricture, respectively. Two of four ABO-incompatible patients (50%) had hepatic artery thrombosis with biliary complications, a high incidence. CONCLUSION In our series of ABO-incompatible patients undergoing ALDLT, those who developed hepatic artery thrombosis exhibited a high incidence of biliary complications.

Increased sensitivities of peripheral blood mononuclear cells to immunosuppressive drugs in cirrhosis patients awaiting liver transplantation.

Successful immunosuppressive therapy is critical for liver transplantation. However, a considerable number of patients show clinical resistance to the therapy and experience rejection episodes, or alternatively exhibits serious adverse effects of drugs. We examined the in vitro response of peripheral blood mononuclear cells (PBMCs) to immunosuppressive drugs in cirrhosis patients awaiting liver transplantation. We evaluated the suppressive efficacy of prednisolone, methylprednisolone, cyclosporine, and tacrolimus on the in vitro blastogenesis of PBMCs obtained from 22 cirrhosis patients and 31 healthy subjects. In vitro drug concentrations giving 50% inhibition of PBMC blastogenesis (IC50s) were calculated. Two out of these 22 patients received liver transplantation from living donors, and their clinical courses were surveyed until 5 weeks after operation. The median IC50 values for prednisolone, cyclosporine, and tacrolimus against blastogenesis of PBMCs from cirrhosis patients were significantly lower than those of PBMCs from healthy subjects (p < 0.01). However, large individual differences were observed in the IC50 values of the immunosuppressive drugs examined, especially in the cirrhosis patients. One recipient exhibiting high PBMC sensitivity to tacrolimus (IC50 = 0.001 ng/ml) showed good clinical course without rejection until 5 weeks after liver transplantation. The other recipient exhibiting relatively low PBMC sensitivity to taclolimus (IC50 = 0.30) showed allograft rejection at 1 week after operation. We concluded from these observations that PBMCs of cirrhosis patients are vulnerable to the immunosuppressive effects of prednisolone and calcineurin inhibitors. However, large individual variations in the IC50 values suggest that patients exhibiting relatively lower sensitivity to these drugs may have risks of rejection, whereas highly sensitive patients are possibly able to reduce the dose of immunosuppressive drugs to avoid serious drug-adverse effects, after liver transplantation.

Serum cholesterol levels and kidney transplantation outcome: attenuation of cyclosporine efficacy?

The role of high serum cholesterol levels in the clinical outcome of kidney-transplanted patients has been described in a recent report by Roodnat et al. (1). Their study of 676 kidney graft recipients showed that serum cholesterol levels have an independent influence on the graft, patient, and over-all graft failure. Because hyperlipidemia occurs in 60 – 80% of kidney transplant recipients (2), their findings might be of clinical value for the future improvement of kidney transplantation outcome. Although the underlying mechanisms of their findings are not clear, high serum cholesterol levels may increase the risks of cardiovascular disease and impair renal function, which may influence graft and patient survivals. In this letter, we will highlight another aspect of the role of high serum cholesterol levels on graft outcome in kidney transplanted patients. Serum cholesterol levels are reported to have an influence on cyclosporine blood disposition (3). In blood, about 40% of cyclosporine are bound to erythrocytes and 50 – 60% to cholesteroland triglyceride-containing lipoproteins (4). Cyclosporine is suggested to be incorporated into peripheral blood lymphocytes (PBLs) through low density lipoprotein(LDL) receptors on the cell surface such as the LDL-cyclosporine complex (5). High blood levels of LDL possibly increase the amount of LDL-bounded cyclosporine, but this may in turn down-regulate LDL-receptors on the cell surface (6), and subsequently reduce cellular uptake of LDL-cyclosporine complex. Indeed, hypercholesterolemia is reported to inhibit cyclosporine efficacy in nephrotic syndrome (7). In our retrospective pilot study in patients with nephrosis, we found that both total serum cholesterol and LDL-cholesterol levels are significantly correlated with individual IC50 values of cyclosporine against PBL blastogenesis in these patients (r50.733; P,0.002; n516 and r50.830; P,0.03; n57, respectively; unpublished results). A high serum cholesterol level is one of the typical clinical symptoms of nephrotic syndrome. Thus, these observations suggest that high serum cholesterol levels attenuate suppressive efficacy of cyclosporine against blastogenesis of patients’ PBLs in nephrosis. Of 676 recipients in the study of Roodnat et al.(1), 456 were treated with cyclosporine, and therefore serum cholesterol levels may possibly have had an influence on pharmacokinetics and/or pharmacodynamics of cyclosporine in these 456 recipients. One possible explanation for the increased incidence of graft failure in the recipients with high serum cholesterol levels is cyclosporine efficacy attenuation through an intervention of cyclosporine uptake into T lymphocytes via LDL-receptor down-regulation. From these points of view, a comparative evaluation of the effects of serum cholesterol levels on clinical outcome, especially incidences of rejection episodes and graft failure, between recipients treated with azathioprine and those treated with cyclosporine could be both interesting and informative in the study of Roodnat et al. (1). In addition, careful monitoring of immunological status and signs of rejection due to attenuation of cyclosporine immunosuppressive efficacy appears to be important to the recipients treated with cyclosporine when their serum cholesterol levels are unusually high.