Immunosuppression: practice and trends

Treatment of acute tacrolimus toxicity with phenytoin in solid organ transplant recipients

The pharmacokinetics of tacrolimus are influenced by many factors, including genetic variability, acute infections, liver dysfunction, and interacting medications, which can result in elevated concentrations. The most appropriate management of acute tacrolimus toxicity has not been defined though case reports exist describing the therapeutic use of enzyme inducers to increase tacrolimus metabolism and decrease concentrations. We are reporting on the utilization of phenytoin to assist in decreasing tacrolimus concentrations in a case series of four solid organ transplant recipients with acute, symptomatic tacrolimus toxicity presenting with elevated serum creatinine, potassium, and tacrolimus trough concentrations greater than 30 ng/mL. All four patients had the potential causative agents stopped or temporarily held and were given 300 to 400 mg/day of phenytoin for two to three days. Within three days of beginning phenytoin, all four patients had a decrease in tacrolimus concentration to less than 15 ng/mL, a return to or near baseline creatinine concentration, and lack of phenytoin-related side effects. Therefore, phenytoin appears to be a safe and potentially beneficial treatment option in patients with symptomatic tacrolimus toxicity.

Effect of mycophenolate mofetil on hematological side effects incidence in renal transplant recipients

Mycophenolate mofetil (MMF), an immunosuppressant administered after solid organ transplantation, is generally well tolerated; however, it frequently causes hematological toxicity. In this study, we aimed to assess the relation between the pharmacokinetic parameters of MMF metabolites (mycophenolic acid [MPA] and 7-O-MPA glucuronide [MPAG]) and the adverse effects on the hematopoietic system in renal transplant recipients. The four-h pharmacokinetic profiles of MPA and MPAG were determined using the HPLC method for MMF-treated patients (n = 61) among 106 renal transplant recipients (during the late post-transplant period) participating in the study. Anemia was more frequently observed in the study group compared with the control group (30.7% vs. 20.0%) and although the difference was insignificant, plasma iron concentrations were significantly higher in patients treated with MMF (32.9 ± 9.4 μmol/L vs. 28.7 ± 9.4 μmol/L; p = 0.032). Iron supplementation was more frequently applied to patients with anemia (48.2%) compared with patients with hemoglobin within the norm (20.3%; p = 0.005). As all MPAG pharmacokinetic parameters correlated negatively with hemoglobin and hematocrit, and MPAG pharmacokinetic parameters were higher in patients with anemia, MPAG may be the predicting factor of MMF side effects. In renal transplant recipients, especially with deteriorated renal function, extensive iron supplementation may be ineffective as anemia was associated with declined renal function and was not caused by low iron concentration.

A retrospective analysis of the safety and efficacy of low dose tacrolimus (FK506) for living donor liver transplant recipients

We sought to evaluate the efficacy and effects of low-dose tacrolimus (FK506) to recipients with living donor liver transplantation (LDLT). A total of 66 patients who underwent LDLT between 2001 and 2007 were enrolled in this study. According to different doses of tacrolimus, the recipients were randomly divided into two groups: the low-dose tacrolimus group (group A) and the normal-dose tacrolimus group (group B). The blood concentration of tacrolimus and its side effects including infection, hyperglycemia, hypertension, high blood creatinine and jaundice were monitored once a week at the perioperative period, and once a month thereafter. Besides, the survival rates of the recipients were analyzed at the 1- and 3-year time point after operation. Among these patients, no significant acute rejection was detected after LDLT. The incidences of infection, hyperglycemia, liver dysfunction and renal impairment in group A were markedly lower than those in group B. However, no significant differences were detected in the incidence of hypertension between the two groups. Moreover, the recipients in each group had a similar survival rate according to the results of 1- and 3-year follow-up. The incidence of side effects that associated with tacrolimus positively correlated with tacrolimus blood concentration. In conclusion, long-term and low-dose administration of tacrolimus is a safe and effective treatment for LDLT recipients.

Comparison of Antibody-Conjugated Magnetic Immunoassay and Liquid Chromatography-Tandem Mass Spectrometry for the Measurement of Cyclosporine and Tacrolimus in Whole Blood

The aim of this work is to compare the results of a commercially available liquid chromatography tandem mass spectrometry (LC-MS/MS) method in a clinical pathology laboratory for routine Therapeutic Drug Monitoring (TDM) of cyclosporine (CsA) and tacrolimus (Tacr) in pediatric patients with those obtained with the current antibody-conjugated magnetic immunoassay (ACMIA). Whole blood levels of CsA (n= 135) and Tacr (n=100) were sequentially analyzed by using ACMIA and LC-MS/MS on pediatric transplanted patients. The differences were analyzed by using the Passing Bablok regression analysis and the Bland and Altman test. The LC-MS/MS method showed excellent reproducibility and lower limits of quantification compared to the ACMIA. A linear relationship between ACMIA and LC-MS/MS was obtained for both CsA (r= 0.9449; P<0.0001, 95% CI 0.9234 to 0.9605) and Tacr (r=0.9275; P<0.0001, 95% CI 0.8941 to 0.9506). No significant inter-method biases were observed. The analytical performances of the LC-MS/MS method make it suitable for the accurate measurement of CsA and Tacr in pediatric transplanted patients. However ACMIA results are also accurate and reliable. For this reason the choice of the method to be used in a routine clinical pathology laboratory can be made on the bases of non-analytical considerations such as costs, organization, availability of skilled personnel.

No harmful effect of mycophenolate mofetil on liver regeneration: an experimental study

AIM

The aim of this experimental study was to examine the effects of mycophenolate mofetil (MMF) on liver regeneration in a partial hepatectomy model.

METHODS

Rats were divided into 3 groups immediately following partial liver resection: saline, controls intraperitoneally (MMF; Group 1); MMF (15 mg/kg/d; Group II), and MMF (30 mg/kg/d; Group III). On days 3 and 7 following liver resection we humanely killed half of the rats in each group to measure alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels and to evaluate Ki-67 using immunohistochemistry. We calculated liver regeneration rates.

RESULTS

The difference between ALT levels on days 3 and 7 was not significantly different among the groups (P = .157; P = .292; P > .05, respectively). The AST levels were significantly different at 3 days (P = .018) but not 7 days (P = .385). The Ki-67 level were different among groups at day 3 (P = .002) but not at day 7 (P = .290). Liver regeneration rates were not different among the groups either at 3 or at 7 days (P = .264 and P = .925, respectively).

CONCLUSION

MMF stimulates mitosis but its effect on regeneration is not clear. MMF appeared to show no adverse effects on liver regeneration.

Human hepatocyte growth factor (hHGF)-modified hepatic oval cells improve liver transplant survival

Despite progress in the field of immunosuppression, acute rejection is still a common postoperative complication following liver transplantation. This study aims to investigate the capacity of the human hepatocyte growth factor (hHGF) in modifying hepatic oval cells (HOCs) administered simultaneously with orthotopic liver transplantation as a means of improving graft survival. HOCs were activated and isolated using a modified 2-acetylaminofluorene/partial hepatectomy (2-AAF/PH) model in male Lewis rats. A HOC line stably expressing the HGF gene was established following stable transfection of the pBLAST2-hHGF plasmid. Our results demonstrated that hHGF-modified HOCs could efficiently differentiate into hepatocytes and bile duct epithelial cells in vitro. Administration of HOCs at the time of liver transplantation induced a wider distribution of SRY-positive donor cells in liver tissues. Administration of hHGF-HOC at the time of transplantation remarkably prolonged the median survival time and improved liver function for recipients compared to these parameters in the other treatment groups (P<0.05). Moreover, hHGF-HOC administration at the time of liver transplantation significantly suppressed elevation of interleukin-2 (IL-2), tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) levels while increasing the production of IL-10 and TGF-β1 (P<0.05). HOC or hHGF-HOC administration promoted cell proliferation, reduced cell apoptosis, and decreased liver allograft rejection rates. Furthermore, hHGF-modified HOCs more efficiently reduced acute allograft rejection (P<0.05 versus HOC transplantation only). Our results indicate that the combination of hHGF-modified HOCs with liver transplantation decreased host anti-graft immune responses resulting in a reduction of allograft rejection rates and prolonging graft survival in recipient rats. This suggests that HOC-based cell transplantation therapies can be developed as a means of treating severe liver injuries.

A prospective, multinational pharmacoepidemiological study of clinical conversion to sirolimus immunosuppression after renal transplantation

This prospective pharmacoepidemiological study examined treatment and outcomes in patients converted to sirolimus (SRL) after renal transplantation. 484 subjects in 36 centres in 7 countries were followed for up to 5 years. Principal reasons for conversion were declining graft function (146/484, 30%) and side effects of prior therapy (144/484, 30%) and the major treatment combinations after conversion were SRL ± MMF (62%), SRL + TAC (21.5%), SRL + CSA (16.5%). The cumulative probability of biopsy-confirmed acute rejection (BCAR) was 5% (n = 22), death-censored graft loss 12% (n = 56) and death 6% (n = 22), and there was no significant relationship to the treatment combination employed. Median calculated creatinine clearance was 48.4 (29.3, 64.5) mL/min at conversion, rising to 54.1 (41.2, 69.0) mL/min at month 1, 55.7 (39.0, 73.0) mL/min at month 12, 58.6 (39.7, 75.2) mL/min at two years and 60.9 (36.0, 77.0) mL/min at three years post-conversion. The most common adverse events were hypertension (47%), hyperlipidemia (26%), urinary tract infections (25%), anaemia (24%) and diarrhea (14%), and cardiac events, hyperlipemia and CMV infection were more common in patients converted during the first year. SRL was most frequently combined with MMF after conversion, but principal clinical outcomes were not significantly influenced by the treatment combination employed in normal practice.

Simultaneous determination of cyclosporine A, tacrolimus, sirolimus, and everolimus in whole-blood samples by LC-MS/MS

Objectives. Cyclosporine A (CyA), tacrolimus (TRL), sirolimus (SIR), and everolimus (RAD) are immunosuppressive drugs frequently used in organ transplantation. Our aim was to confirm a robust sensitive and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for determination of CyA, TRL, SIR, and RAD in whole-blood samples. Materials and Methods. We used an integrated online solid-phase extraction-LC-MS/MS system and atmospheric pressure ionization tandem mass spectrometry (API-MS/MS) in the multiple reaction monitoring (MRM) detection mode. CyA, TRL, SIR, and RAD were simultaneously analyzed in whole blood treated with precipitation reagent taken from transplant patients. Results. System performance parameters were suitable for using this method as a high-throughput technique in clinical practice. The high concentration of one analyte in the sample did not affect the concentration of other analytes. Total analytical time was 2.5 min, and retention times of all analytes were shorter than 2 minutes. Conclusion. This LC-MS/MS method can be preferable for therapeutic drug monitoring of these immunosuppressive drugs (CyA, TRL, SRL, and RAD) in whole blood. Sample preparation was too short and simple in this method, and it permits robust, rapid, sensitive, selective, and simultaneous determination of these drugs.

Effect of mycophenolate mofetil on plasma bioelements in renal transplant recipients

The proper concentrations of plasma bioelements may favorably reduce the incidence of metabolic disorders, which often occur during immunosuppressive therapy. Mycophenolate mofetil (MMF) is currently one of the most frequently administered immunosuppressive agents; however, MMF treatment is often related to gastrointestinal side effects. The aim of this study was thus to verify whether the MMF treatment itself, or its metabolite pharmacokinetics, has an effect on the concentrations of plasma bioelements. To determine this, the effect of MMF on the levels of both major (sodium [Na], potassium [K], calcium [Ca], magnesium [Mg]), and trace (iron [Fe], zinc [Zn], copper [Cu]) plasma bioelements in 61 renal transplant recipients was assessed in comparison to a control group (n = 45). The pharmacokinetic parameters of mycophenolic acid were determined by the high-performance liquid chromatography method. All patients filled out a 24-h diet history questionnaire. The results showed high plasma concentrations of Fe and low plasma concentrations of Mg and Zn as compared with diagnostic norms. The patients treated with MMF had significantly lower plasma Na (P < 0.001) and significantly higher plasma Zn (P = 0.030) and Cu concentrations (P < 0.001). In conclusion, MMF treatment was found to affect plasma Fe, Zn, and Cu levels by increasing their concentrations while decreasing the plasma Na concentration. Mg and Zn deficiencies, as well as excessive Fe levels, are frequently observed irrespective of the immunosuppressive regimen applied, which suggests that monitoring of these bioelements may be favorable.

Immunosuppressive protocols and immunological challenges related to hand transplantation

There are many immunological challenges related to hand transplantation. Curbing the immune system's ability to effectively mount an immune response against the graft is the goal. As the various components of the immune response are defined and their mechanisms of action delineated, more specific immunosuppressive agents and protocols have been developed. Complications related to immunosuppression in hand transplant recipients are similar to incidences among solid organ recipients. With longer follow-up, the increased cardiovascular risk factors or the development of a neoplasm will likely cause mortality. Standardizing immunosuppression in hand transplantation with the long-term goal of minimization is critically needed.

Correlation of tacrolimus levels in peripheral blood mononuclear cells with histological staging of rejection after liver transplantation: preliminary results of a prospective study

Therapeutic drug monitoring of tacrolimus (TAC) is characterized by a complex relationship between trough blood TAC concentrations and therapeutic efficacy. This prospective study evaluates the predictive value of intrahepatic, peripheral blood mononuclear cells (PBMCs) and blood TAC concentrations during the early postliver transplantation (LT) period. In a cohort of 90 adult liver recipients under TAC-based monotherapy, liver biopsies were performed at day 7 post-LT, and PBMCs TAC concentrations were measured at day 1, 3, 5, and 7 post-LT. Both intrahepatic and PBMCs TAC concentrations were determined. All biopsies were graded following the Banff scoring. Intrahepatic, and day 3, 5, 7 PBMCs concentrations correlated very well with day 7 liver Banff rejection scores (P < 0.05). Clinical rejection was characterized by significantly lower mean TAC PBMCs concentrations at day 5 and 7 (P < 0.05) and tended to be associated to lower mean intrahepatic TAC concentrations at day 7 (P = 0.059). Intrahepatic TAC concentrations at day 7 significantly correlated with TAC PBMCs concentrations from day 5 post-LT (P < 0.05). TAC PBMCs concentrations might be reliable markers of immunosuppression efficacy during the early phase after LT. This finding could represent an additional tool to individualize more precisely early immunosuppressive schemes after liver transplantation.

Timing of basiliximab induction and development of acute rejection in lung transplant patients

BACKGROUND

Acute rejection affects more than 36% of recipients within the first year post-transplantation. The interleukin-2 (IL-2) receptor antagonist basiliximab has been associated with decreased frequency and severity of acute rejection. We investigated whether the timing of induction administration would impact the frequency and severity of acute rejection in the first year after transplantation.

METHODS

In this study we reviewed 119 patients who underwent lung transplantation at Henry Ford Hospital from October 1994 to January 2009. Prior to January 2000 no patients received induction. From January 2000 to March 2006 the initial dose was given after implantation, and from March 2006 to 2009 basiliximab was given prior to implantation. The primary outcome was cumulative acute rejection score (CAR) in the first post-operative year comparing post- vs pre-implant induction.

RESULTS

The CAR score for pre-implant basiliximab was 2.5 ± 2.3. This was significantly lower than CAR score of 4.6 ± 3.9 in the post-implant group (p = 0.025). The no-induction group had the highest CAR score at 6.3 ± 3.8 (p = 0.077 compared with the post group). The mean follow-up times in the post and pre group were 5.9 ± 2.3 and 2.3 ± 0.7 years, respectively (p < 0.001). There was no difference in freedom from bronchiolitis obliterans syndrome (BOS), survival or invasive infections between pre- and post-implant induction groups.

CONCLUSIONS

Basiliximab prior to implant is associated with a lower cumulative acute rejection score over 1 year compared with induction post-implantation. Despite a lower cumulative acute rejection score, there was no significant difference in freedom from BOS or survival.

A dimension reduction approach for modeling multi-locus interaction in case-control studies

Studying one locus or one single nucleotide polymorphism (SNP) at a time may not be sufficient to understand complex diseases because they are unlikely to result from the effect of only one SNP. Each SNP alone may have little or no effect on the risk of the disease, but together they may increase the risk substantially. Analyses focusing on individual SNPs ignore the possibility of interaction among SNPs. In this paper, we propose a parsimonious model to assess the joint effect of a group of SNPs in a case-control study. The model implements a data reduction strategy within a likelihood framework and uses a test to assess the statistical significance of the effect of the group of SNPs on the binary trait. The primary advantage of the proposed approach is that the dimension reduction technique produces a test statistic with degrees of freedom significantly lower than a multiple logistic regression with only main effects of the SNPs, and our parsimonious model can incorporate the possibility of interaction among the SNPs. Moreover, the proposed approach estimates the direction of association of each SNP with the disease and provides an estimate of the average effect of the group of SNPs positively and negatively associated with the disease in the given SNP set. We illustrate the proposed model on simulated and real data, and compare its performance with a few other existing approaches. Our proposed approach appeared to outperform the other approaches for independent SNPs in our simulation studies.

Regression of new-onset diabetes mellitus after conversion from tacrolimus to cyclosporine in liver transplant patients: results of a pilot study

INTRODUCTION

New-onset diabetes mellitus (NODM) has important implications for long-term outcome following liver transplantation.

AIM

To evaluate the impact of conversion from tacrolimus to cyclosporine in liver transplant patients presenting NODM.

METHOD

In a 12-month pilot study, 39 liver transplant patients with NODM were converted from tacrolimus to cyclosporine. Most patients (59%) were receiving antidiabetic therapy (18% insulin, 41% oral) and all patients had received dietary advice prior to the study.

RESULTS

At month 12, NODM had significantly resolved (FBG<7 mmol/L without treatment) in 36% of patients (95% CI 20.8-51.0%). In the 16 patients not receiving antidiabetic drugs at baseline, mean FBG decreased from 8.1 mmol/L to 6.6 mmol/L (P=0.008) and mean HbA(1c) decreased from 6.4 to 6.0% (P=0.05). Steroids were stopped rapidly in the nine patients receiving steroids at inclusion but NODM resolution was observed in only one of these nine patients. No significant factors were identified that could have affected NODM resolution. There were three episodes of biopsy-proven acute rejection (7.7%), no graft losses and one death. Overall, cyclosporine tolerance was good with no significant change in creatinine clearance at month 12. Total cholesterol increased from 4.6 mmol/L to 5.1 mmol/L (P<0.001).

CONCLUSIONS

These results suggest that liver transplant patients with NODM may benefit from conversion to cyclosporine from tacrolimus through improved glucose metabolism. Confirmation in a prospective, randomized comparative study is required.

Evolving concepts in the selection of immunosuppression regimen for liver transplant recipients

The introduction of calcineurin inhibitor (CNI) based immunosuppression has revolutionized the field of liver transplantation by dramatically reducing the incidence of acute cellular rejection and prolonging patient and allograft survival. However, the introduction of CNIs has also come at the price of increased patient morbidity, particularly with regard to the well-known nephrotoxic effects of the medications. In an effort to minimize the adverse effects, immunosuppression regimen have evolved to include the use of various induction agents and purine synthesis inhibitors to limit the dose of CNI necessary to achieve low acute cellular rejection rates. Careful assessments of risks and benefits are needed as these newer agents have their own side effect profiles. In addition, the impact of newer immunosuppression regimen on hepatitis C (HCV) recurrence has not been completely elucidated. This review will provide an overview of the most common immunosuppression regimen used in liver transplantation and discuss their impact on acute cellular rejection, patient and allograft survival, and HCV recurrence.

Mycophenolate monitoring in liver, thoracic, pancreas, and small bowel transplantation: a consensus report

Assessing the value of mycophenolic acid (MPA) monitoring outside renal transplantation is hindered by the absence of any trial comparing fixed-dose and concentration-controlled therapy. However, in liver and thoracic transplantation particularly, clinical trials, observational studies with comparison groups, and case series have described MPA efficacy, exposure/efficacy relationships, pharmacokinetic variability, and clinical outcomes relating to plasma MPA concentrations. On the basis of this evidence, this report identifies MPA as an immunosuppressant for which the combination of variable disposition, efficacy, and adverse effects contributes to interindividual differences seemingly in excess of those optimal for a fixed-dosage mycophenolate regimen. Combined with experiences of MPA monitoring in other transplant indications, the data have been rationalized to define circumstances in which measurement of MPA concentrations can contribute to improved management of mycophenolate therapy in nonrenal transplant recipients.

Anti-thymocyte globulin for the treatment of acute cellular rejection following liver transplantation

INTRODUCTION

Acute cellular rejection (ACR) post-liver transplantation (LT) can usually be reversed with pulse dose steroids. Anti-thymocyte globulin (ATG) is used to treat steroid-resistant rejection (SRR).

PATIENTS AND METHODS

We report 15 male and five female LT recipients with a median age of 48.3 (range 14.3-71.7) years, who received ATG for biopsy-proven steroid-resistant rejection (n =13), severe rejection (6), and severe rejection/recurrent autoimmune hepatitis (n = 1) median 42 (range 6-2,456) days following LT.

RESULTS

Underlying liver diseases included HCV (n = 7), alcoholic cirrhosis (n = 3), NASH (n = 2), HBV (n = 2), autoimmune hepatitis (n =1), PSC (n = 1), miscellaneous (n = 4) including three re LTs. All patients responded to treatment (median AST declined from 172 to 34U/l, median total bilirubin from 9.1 to 1.3 mg/dl; p < 0.001). Three patients developed recurrent ACR, and none chronic rejection. All HCV patients developed recurrence with significant rises in HCV RNA levels. Infections included pneumonia, sepsis, intraabdominal infection, chronic diarrhea, wound infection, EBV, and CMV disease. After a median follow-up of 65.5 (range 4.3-101.7) months post-ATG and median 67.7 (range 9.3-306.3) months post-LT, 17 patients are alive, two died from sepsis/multi-organ failure and one from HCV recurrence.

CONCLUSION

ATG effectively reversed severe and SSR; HCV recurrence and infections remain significant complications.

Comparable Renal Function at 6 Months with Tacrolimus Combined with Fixed-Dose Sirolimus or MMF: Results of a Randomized Multicenter Trial in Renal Transplantation

In a multicenter trial, renal transplant recipients were randomized to tacrolimus with fixed-dose sirolimus (Tac/SRL, N = 318) or tacrolimus with MMF (Tac/MMF, N = 316). Targeted tacrolimus trough levels were lower in the Tac/SRL group after day 14. The primary endpoint was renal function at 6 months using creatinine clearance (Cockcroft-Gault) and was comparable at 66.4 mL/min (SE 1.4) with Tac/SRL and at 65.2mL/min (SE 1.3) with Tac/MMF (completers). Biopsy-confirmed acute rejection was 15.1% (Tac/SRL) and 12.3% (Tac/MMF). In both groups, graft survival was 93% and patient survival was 99.0%. Premature withdrawal due to an adverse event was twice as high in the Tac/SRL group, 15.1% versus 6.3%. Hypercholesterolemia incidence was higher with Tac/SRL (P < .05) while CMV, leukopenia, and diarrhea incidences were higher with Tac/MMF (P < .05). The incidence of any antidiabetic treatment for >30 consecutive days in previously nondiabetic patients was 17.8%, Tac/SRL, and 24.8%, Tac/MMF. Evaluation at 6 months showed comparable renal function using tacrolimus/sirolimus and tacrolimus/MMF regimens.

Pharmacokinetic optimization of immunosuppressive therapy in thoracic transplantation: part II

Part I of this article, which appeared in the previous issue of the Journal, reviewed calcineurin inhibitors--ciclosporin and tacrolimus. In part II, we review the pharmacokinetics and therapeutic drug monitoring of mycophenolate and mammalian target of rapamycin inhibitors--sirolimus and everolimus--in thoracic transplantation, and we provide an overall discussion and suggest various areas for future study.

Analysis of cyclosporine A and its metabolites in rat urine and feces by liquid chromatography-tandem mass spectrometry

A sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantification of cyclosporine A (CyA) and the identification of its metabolites in rat urine and feces. The analytes were extracted from waste samples via liquid-liquid extraction. A Turboionspray source was used as a detector. It was operated in a positive ion mode with transitions of m/z 1225-->m/z 1112 for CyA and in a selected multiple reactions monitoring (MRM) mode with transitions of m/z 1239-->m/z 1099 for the internal standard (cyclosporine D, CyD). Linear calibration curves were obtained for CyA concentration ranges of 12.5-250 ng mL(-1) in urine and 2.5-375 ng mg(-1) in feces. The intra- and inter-day precision values (relative standard deviation) obtained were less than 8%, and the accuracy was within +/-15% for each of the analytes. Extraction recoveries of CyA and CyD were both over 80%. The identification of the metabolites and elucidation of their structure were performed on the basis of their retention times and mass spectrometry fragmentation behaviors. A total of seven metabolites in rat feces were identified as dimethyl CyA, hydroxy CyA, and dihydroxy CyA after the oral administration of cyclosporine A-Eudragit S100 nanoparticles (CyA-NP). Six of these metabolites were also detected in rat urine. A possible metabolic pathway was also proposed. The newly developed method was proven to be sensitive, simple, reproducible, and suitable for the rapid determination of CyA. It was successfully employed to study the excretion of CyA in rats and could be used to better understand the in vivo metabolism of CyA-NP, a potentially effective nanoparticle system.

Limited sampling strategies drawn within 3 hours postdose poorly predict mycophenolic acid area-under-the-curve after enteric-coated mycophenolate sodium

Previous studies predicted that limited sampling strategies (LSS) for estimation of mycophenolic acid (MPA) area-under-the-curve (AUC(0-12)) after ingestion of enteric-coated mycophenolate sodium (EC-MPS) using a clinically feasible sampling scheme may have poor predictive performance. Failure of LSS was thought to be due to the slow absorption of MPA causing late and variable times of maximum MPA concentration and variable predose concentrations. The aim of this study was to formally test the performance of LSS by developing and validating LSS for estimation of MPA AUC(0-12) after EC-MPS administration. Pharmacokinetic data from 109 renal transplant recipients collected during the maintenance period after transplantation were analysed retrospectively. LSS were developed separately for renal transplant patients who concurrently used cyclosporine (n = 79) and for patients not concurrently treated with cyclosporine (n = 30). Data were split into an index and a validation data set. For clinical feasibility reasons, a LSS could consist of a maximum of 3 sampling time points with the latest sample drawn 2 hours after drug administration. LSS with the latest sample drawn 3 hours after drug administration or even later were also tested. The validation of the developed LSS showed that MPA AUC(0-12) for patients concurrently treated with cyclosporine was best estimated by AUC(0-12) (mg x h x L(-1)) = 36.536 + 1.642 x C0.5 + 0.569 x C1.5 + 0.905 x C2 (r2 = 0.33, bias = -1.0 mg x h x L(-1), precision = 24 mg x h x L(-1)), whereas AUC(0-12) [mg x h x L(-1)] = 19.801 + 1.827 x C0.5 + 1.111 x C1 + 1.429 x C2 was the best AUC(0-12) estimator for patients not cotreated with cyclosporine (r2 = 0.31, bias = 0.4 mg x h x L(-1), precision = 14.5 mg x h x L(-1)). Both LSS showed poor precision and overestimation of AUC(0-12) values below the therapeutic window and underestimation of AUC(0-12) values above the therapeutic window of MPA. Using C3 as latest sampling time point improved the fit slightly, but not satisfactory, with r2 still <0.40 and precision still >14.0 mg x h x L(-1). Estimation of MPA AUC(0-12) with LSS for EC-MPS drawn within 2 or 3 hours postdose in renal transplant recipients in the maintenance period is likely to result in biased and imprecise results.

Prospective observational study of sirolimus as primary immunosuppression after renal transplantation

BACKGROUND.: Sirolimus (SRL) is an important component of clinical immunosuppression in renal transplantation, but few international studies have examined how this agent is used in routine practice. METHODS.: Within a large prospective pharmacoepidemiological study, 718 de novo renal graft recipients treated with SRL in 65 centers in 10 countries were monitored for up to 5 years posttransplant to compare the principal outcomes and adverse effects by treatment regimen. RESULTS.: Principal treatment regimens were SRL without a calcineurin inhibitor (33%), SRL+cyclosporine A (CsA) (33%), and SRL+tacrolimus (TAC) (34%); 18% of subjects discontinued SRL, 124/718 (17%) developed biopsy-confirmed acute rejection (BCAR), 64/718 (9%) lost their graft, and 50/718 (7%) died during follow-up. Calculated creatinine clearance was 66+/-26 mL/min at 2 years. The most common adverse events were hypertension, hyperlipidemia, anemia, urinary tract infections, and diabetes. BCAR was significantly lower in subjects receiving SRL+TAC (hazard ratio [HR] 0.46, P=0.009) but not significantly lower in those receiving SRL+CsA (HR 0.62, P=0.102) compared with SRL without a calcineurin inhibitor. Graft loss or death did not significantly differ between treatment groups but were associated, respectively, with deceased donor grafts (HR 3.33, P<0.001) and increased age (HR 1.04, P<0.001). No improvement was observed in patients receiving mycophenolate mofetil in any treatment combination (HR 0.80, P=0.438 for BCAR; HR 0.93, P=0.849 for graft loss; and HR 0.75, P=0.531 for death). CONCLUSIONS.: SRL is most commonly used in combination with mycophenolate mofetil, CsA, or TAC. BCAR was least common in subjects receiving SRL+TAC, but other outcomes seemed comparable between the treatment regimens in routine practice.

Calcineurin inhibitors activate the proto-oncogene Ras and promote protumorigenic signals in renal cancer cells

The development of cancer is a major problem in immunosuppressed patients, particularly after solid organ transplantation. We have recently shown that calcineurin inhibitors (CNI) used to treat transplant patients may play a critical role in the rapid progression of renal cancer. To examine the intracellular signaling events for CNI-mediated direct tumorigenic pathway(s), we studied the effect of CNI on the activation of proto-oncogenic Ras in human normal renal epithelial cells (REC) and renal cancer cells (786-0 and Caki-1). We found that CNI treatment significantly increased the level of activated GTP-bound form of Ras in these cells. In addition, CNI induced the association of Ras with one of its effector molecules, Raf, but not with Rho and phosphatidylinositol 3-kinase; CNI treatment also promoted the phosphorylation of the Raf kinase inhibitory protein and the downregulation of carabin, all of which may lead to the activation of the Ras-Raf pathway. Blockade of this pathway through either pharmacologic inhibitors or gene-specific small interfering RNA significantly inhibited CNI-mediated augmented proliferation of renal cancer cells. Finally, it was observed that CNI treatment increased the growth of human renal tumors in vivo, and the Ras-Raf pathway is significantly activated in the tumor tissues of CNI-treated mice. Together, targeting the Ras-Raf pathway may prevent the development/progression of renal cancer in CNI-treated patients.

NFAT proteins: emerging roles in cancer progression

The roles of nuclear factor of activated T cells (NFAT) transcription factors have been extensively studied in the immune system. However, ubiquitous expression of NFAT isoforms in mammalian tissues has recently been observed, and a role for these transcription factors in human cancer is emerging. Various NFAT isoforms are functional in tumour cells and multiple compartments in the tumour microenvironment, including fibroblasts, endothelial cells and infiltrating immune cells. How do NFAT isoforms regulate the complex interplay between these compartments during carcinoma progression? The answers lie with the multiple functions attributed to NFATs, including cell growth, survival, invasion and angiogenesis. In addition to elucidating the complex role of NFATs in cancer, we face the challenge of targeting this pathway therapeutically.

Pharmacokinetic optimization of immunosuppressive therapy in thoracic transplantation: part I

Although immunosuppressive treatments and therapeutic drug monitoring (TDM) have significantly contributed to the increased success of thoracic transplantation, there is currently no consensus on the best immunosuppressive strategies. Maintenance therapy typically consists of a triple-drug regimen including corticosteroids, a calcineurin inhibitor (ciclosporin or tacrolimus) and either a purine synthesis antagonist (mycophenolate mofetil or azathioprine) or a mammalian target of rapamycin inhibitor (sirolimus or everolimus). The incidence of acute and chronic rejection and of mortality after thoracic transplantation is still high compared with other types of solid organ transplantation. The high allogenicity and immunogenicity of the lungs justify the use of higher doses of immunosuppressants, putting lung transplant recipients at a higher risk of drug-induced toxicities. All immunosuppressants are characterized by large intra- and interindividual variability of their pharmacokinetics and by a narrow therapeutic index. It is essential to know their pharmacokinetic properties and to use them for treatment individualization through TDM in order to improve the treatment outcome. Unlike the kidneys and the liver, the heart and the lungs are not directly involved in drug metabolism and elimination, which may be the cause of pharmacokinetic differences between patients from all of these transplant groups. TDM is mandatory for most immunosuppressants and has become an integral part of immunosuppressive drug therapy. It is usually based on trough concentration (C(0)) monitoring, but other TDM tools include the area under the concentration-time curve (AUC) over the (12-hour) dosage interval or the AUC over the first 4 hours post-dose, as well as other single concentration-time points such as the concentration at 2 hours. Given the peculiarities of thoracic transplantation, a review of the pharmacokinetics and TDM of the main immunosuppressants used in thoracic transplantation is presented in this article. Even more so than in other solid organ transplant populations, their pharmacokinetics are characterized by wide intra- and interindividual variability in thoracic transplant recipients. The pharmacokinetics of ciclosporin in heart and lung transplant recipients have been explored in a number of studies, but less is known about the pharmacokinetics of mycophenolate mofetil and tacrolimus in these populations, and there are hardly any studies on the pharmacokinetics of sirolimus and everolimus. Given the increased use of these molecules in thoracic transplant recipients, their pharmacokinetics deserve to be explored in depth. There are very few data, some of which are conflicting, on the practices and outcomes of TDM of immunosuppressants after thoracic transplantation. The development of sophisticated TDM tools dedicated to thoracic transplantation are awaited in order to accurately evaluate the patients' exposure to drugs in general and, in particular, to immunosuppressants. Finally, large cohort TDM studies need to be conducted in thoracic transplant patients in order to identify the most predictive exposure indices and their target values, and to validate the clinical usefulness of improved TDM in these conditions. In part I of the article, we review the pharmacokinetics and TDM of calcineurin inhibitors. In part II, we will review the pharmacokinetics and TDM of mycophenolate and mammalian target of rapamycin inhibitors, and provide an overall discussion along with perspectives.

Pharmacokinetic modelling of the plasma protein binding of mycophenolic acid in renal transplant recipients

BACKGROUND AND OBJECTIVES

Renal function and the plasma albumin concentration have been shown to correlate with clearance of total mycophenolic acid (MPA). The hypothesis for the underlying mechanism is that low plasma albumin concentrations and accumulation of the glucuronide metabolite of MPA (MPAG) decrease the binding of MPA to albumin. The subsequent increase in the unbound fraction (f(u)) of MPA (MPA(u)) produces an increase in total MPA (MPA(t)) clearance. This study aimed to develop an empirical population pharmacokinetic model to describe the relationships between renal function and albumin concentration and MPAG, MPA(u) and MPA(t), in order to provide insight into the mechanism by which renal function and plasma albumin affect the disposition of MPA.

METHODS

774 MPA(t), 479 MPA(u) and 772 total MPAG (MPAG(t)) plasma concentrations were available from 88 renal transplant recipients on days 11 and 140 after transplantation. Data were analysed using non-linear mixed-effects modelling.

RESULTS

Time profiles of MPA(u) and MPAG(t) concentrations were adequately described by two 2-compartment pharmacokinetic models with a link between the central compartments, representing the glucuronidation of MPA(u) to form MPAG. MPA(t) concentrations were modelled using: [MPA(t)] = [MPA(u)] + [MPA(u)] * theta(pb), with [MPA(u)] * theta(pb) representing the bound MPA concentration, where [MPA(t)], [MPA(u)] and theta(pb) represent MPA(t) concentration, MPA(u) concentration and a factor that correlates to the total number of protein binding places, respectively. According to this equation, f(u) = [MPA(u)]/[MPA(t)] = 1/(1 + theta(pb)) * theta(pb), and therefore [MPA(t)], was significantly and independently correlated with creatinine clearance (CL(CR)), the plasma albumin concentration and the MPAG(t) concentration (all p < 0.001). A reduction in CL(CR) from 60 to 25 mL/min correlated with an increase in f(u) from 2.7% to 3.5%, accumulation of MPAG(t) concentrations from 50 to 150 mg/L correlated with an increase in f(u) from 2.8% to 3.7%, and a decrease in plasma albumin concentration from 40 to 30 g/L correlated with an increase in f(u) from 2.6% to 3.5%. No significant correlations were detected between MPA(u) clearance and the plasma albumin concentration or CL(CR).

CONCLUSION

The model shows that low CL(CR), low plasma albumin concentrations and high MPAG concentrations decrease MPA(t) exposure by affecting MPA binding to albumin.

Multicentric outcome analysis of sirolimus-based immunosuppression in 252 liver transplant recipients

SUMMARY

The use of sirolimus (SRL) in orthotopic liver transplantation (OLT) has been controversial after experimental data suggested an increased risk of hepatic artery thrombosis (HAT). To assess the safety and efficacy of SRL as de novo immunosuppression in OLT recipients. Outcomes of 252 OLT patients who received SRL were compared with outcomes of 291 OLT recipients who received calcineurin inhibitor in a retrospective study. Primary outcomes of this study were: patient- and graft survivals, vascular, biliary, wound complications and rejection rates. Secondary outcomes were: postoperative infection rate, bone marrow and renal function and changes of lipid levels. Patient- and graft survivals, rejection and infection rates were similar. In the SRL group, HAT occurred in 1.2%, biliary complications in 19.4%, and incisional hernias in 9.1%. In the control group the incidence of HAT was 5.8% (P = 0.004), biliary complications 18.5% (P = NS) and incisional hernias 7.2% (P = NS). Patients on SRL experienced significantly higher levels of serum triglycerides but fewer acute cellular rejections. Bone marrow and renal functions were similar in both the groups. Our findings would suggest that SRL is safe and effective for very selected OLT recipients. Randomized controlled trials are necessary to confirm our results.

Interpatient variability in IMPDH activity in MMF-treated renal transplant patients is correlated with IMPDH type II 3757T > C polymorphism

OBJECTIVES

The active metabolite of mycophenolate mofetil (MMF), mycophenolic acid, inhibits the activity of the target enzyme inosine monophosphate dehydrogenase (IMPDH). The aim of this study was to correlate eight different single nucleotide polymorphisms of the IMPDH type II gene to the activity of the IMPDH enzyme to explain between-patient differences in IMPDH activity.

METHODS AND RESULTS

In a prospective study, we measured IMPDH activity, mycophenolic acid plasma concentrations, and eight polymorphisms of IMPDH type II in de novo kidney transplant recipients, 6 days posttransplantation while on MMF treatment. Polymorphisms in the IMPDH type II gene were only observed for the IMPDH type II 3757T > C (rs11706052) single nucleotide polymorphism. Ten of 101 patients (10%) were heterozygous and two of 101 patients (2%) homozygous for IMPDH type II 3757T > C. The allele frequency was 6.9%. The IMPDH activity over 12 h (AUC(act)) was 49% higher for patients with an IMPDH type II 3757C variant [n = 12 vs. n = 68; 336 (95% confidence interval: 216-521) vs. 227 (95% confidence interval: 198-260) hmicromol/s/mol adenosine monophosphate; P = 0.04]. The IMPDH activity measured before transplantation (Act(pre-Tx)) was not significantly different between IMPDH type II 3757TT wild-type and variant carrier patients (P = 0.99).

CONCLUSION

We report that the IMPDH type II 3757T > C polymorphism is associated with an increased IMPDH activity in MMF-treated renal transplant patients. This polymorphism explains 8.0% of the interpatient variability in IMPDH activity.

Select phytochemicals suppress human T-lymphocytes and mouse splenocytes suggesting their use in autoimmunity and transplantation

We have considered a novel "rational" gene targeting approach for treating pathologies whose genetic bases are defined using select phytochemicals. We reason that one such potential application of this approach would be conditions requiring immunosuppression such as autoimmune disease and transplantation, where the genetic target is clearly defined; i.e., interleukin-2 and associated T-cell activation. Therefore, we hypothesized that select phytochemicals can suppress T-lymphocyte proliferation both in vitro and in vivo. The immunosuppressive effects of berry extract, curcumin, quercetin, sulforaphane, epigallocatechin gallate (EGCG), resveratrol, alpha-tocopherol, vitamin C and sucrose were tested on anti-CD3 plus anti-CD28-activated primary human T-lymphocytes in culture. Curcumin, sulforaphane, quercetin, berry extract and EGCG all significantly inhibited T-cell proliferation, and this effect was not due to toxicity. IL-2 production was also reduced by these agents, implicating this important T-cell cytokine in proliferation suppression. Except for berry extract, these same agents also inhibited mouse splenic T-cell proliferation and IL-2 production. Subsequent in vivo studies revealed that quercetin (but not sulforaphane) modestly suppressed mouse splenocyte proliferation following supplementation of BALB/c mice diets. This effect was especially prominent if corrected for the loss of supplement "recall" as observed in cultured T-cells. These results suggest the potential use of these select phytochemicals for treating autoimmune and transplant patients, and support our strategy of using select phytochemicals to treat genetically-defined pathologies, an approach that we believe is simple, healthy, and cost-effective.

A comprehensive review of immunosuppression used for liver transplantation

Since liver transplantation was approved for the treatment of end stage liver disease, calcineurin inhibitors (CNI's) have played a critical role in the preservation of allograft function. Unfortunately, these medications cause a variety of Side effects such as diabetes, hypertension and nephrotoxicity which in turn result in significant morbidity and reduced quality of life. A variety of newer immunosuppressants have been evaluated over the last decade in an attempt to either substitute for CNI's or use with reduced dose CNI's while still preserving allograft function However, current data does not recommend complete cessation of CNI's due to unacceptably high rates of allograft rejection. As these medications have their own unique adverse effects, a careful assessment on their risks and benefits is essential, particularly when additive or synergistic effects with CNI's may occur. Furthermore, the impact of these newer medications on the risk of hepatitis C recurrence and progression remains to be elucidated. Controlled trials are urgently required to assist transplant physicians with choosing the optimum immunosuppressive regimen for their patients. This review will discuss commonly used immunosuppressants prescribed in liver transplantation, emerging therapties and where appropriate, the impact of these medications on the recurrence of hepatitis C after liver transplantation.

Extra-adrenal glucocorticoid synthesis in the intestinal epithelium: more than a drop in the ocean?

Glucocorticoids (GC) are lipophilic hormones commonly used as therapeutics in acute and chronic inflammatory disorders such as inflammatory bowel disease due to their attributed anti-inflammatory and immunosuppressive actions. Although the adrenal glands are the major source of endogenous GC, there is increasing evidence for the production of extra-adrenal GC in the brain, thymus, skin, vasculature, and the intestine. However, the physiological relevance of extra-adrenal-produced GC remains still ambiguous. Therefore, this review attracts attention to discuss possible biological benefits of extra-adrenal-synthesized GC, especially focusing on the impact of locally synthesized GC in the regulation of intestinal immune responses.

A matched cohort pharmacoepidemiological analysis of steroid free immunosuppression in renal transplantation

BACKGROUND

This longitudinal, sequential, matched closed-cohort design pharmacoepidemiological analysis examined the influence of maintenance steroid therapy in 380 first graft recipients after renal transplantation under conditions of normal clinical practice.

METHODS

Nonexposed (steroid avoidance, n=190) and exposed (steroid treated, n=190) cohorts were matched 1:1 for key demographic factors, including donor source (living or deceased), diabetic status, panel reactive antibody level, recipient age (by decade), and sex.

RESULTS

Cohorts were comparable for all variables except median human leukocyte antigen mismatch (4 vs. 3, P=0.03), use of tacrolimus (90.0% vs. 59.5%, P<or=0.0001), and of basiliximab (94.7% vs. 57.4%, P<or=0.0001), which were higher in the nonexposed cohort. Estimated glomerular filtration rate (mL/min/1.73 m) was comparable at 1 year (median: 58.1 vs. 58.3, P=0.92) and 2 years (median: 55.5 vs. 58.0, P=0.97) in nonexposed and in exposed cohorts (P=0.97). There was no difference in Kaplan-Meier estimates of biopsy-proven acute rejection (14.8% vs. 17.0%; hazard ratio: 0.88, P=0.60) or of 2-year death censored graft failure (4.7% vs. 3.2%; P=0.44) between nonexposed or exposed cohorts. Median total cholesterol (4.6 vs. 5.0 mmol/L, P=0.0002), low-density lipoprotein (2.6 vs. 2.8 mmol/L, P=0.005), high-density lipoprotein levels (1.1 vs. 1.3, P=0.0001), and median weight change from baseline (-1.7 vs. +1.0 kg, P=0.001) were significantly lower in the nonexposed cohort. Forty-five patients (29%) in the nonexposed cohort commenced steroid therapy, principally for graft dysfunction or acute rejection.

CONCLUSION

In summary, steroid avoidance did not negatively impact 2-year graft function, biopsy-proven acute rejection rate, or short-term graft survival and offers clinical benefits, which weigh in the decision regarding maintenance therapy.

Neural progenitors derived from human embryonic stem cells are targeted by allogeneic T and natural killer cells

Neural progenitor cells (NPC) of foetal origin or derived from human embryonic stem cells (HESC) have the potential to differentiate into mature neurons after transplantation into the central nervous system, opening the possibility of cell therapy for neurodegenerative disorders. In most cases, the transplanted NPC are genetically unrelated to the recipient, leading to potential rejection of the transplanted cells. Very few data provide reliable information as to the potential immune response of allogeneic neural progenitors derived from HESC. In this study, we analyzed in vitro the allogeneic immune response of T lymphocytes and natural killer (NK) cells to NPC derived from HESC or of foetal origin. We demonstrate that NPC induce T-cell stimulation and a strong NK cytotoxic response. NK-cell activity is unrelated to MHC-I expression but driven by the activating NKG2D receptor. Cyclosporine and dexamethasone previously used in clinical studies with foetal NPC did not only fail to prevent NK alloreactivity but strongly inhibited the terminal maturation from NPC into mature neurons. We conclude that allogenic transplantation of NPC in the central nervous system will most likely require an immunosuppressive regimen targeting allogenic T and NK cells, whereas possible interference with the differentiation of NPC needs to be carefully evaluated.

Tacrolimus versus cyclosporine microemulsion for heart transplant recipients: a meta-analysis

BACKGROUND

Tacrolimus and cyclosporine microemulsion are the 2 major immunosuppressants for heart transplantation. Several studies have compared these 2 drugs, but the outcomes were not consistent. This meta-analysis of randomized controlled trials compared the beneficial and harmful effects of tacrolimus and microemulsion cyclosporine for heart transplant recipients.

METHODS

Electronic databases and manual bibliography searches were conducted. A meta-analysis was performed of all randomized controlled trials comparing tacrolimus with cyclosporine microemulsion as primary immunosuppression for heart transplant recipients. Data for mortality, acute rejection, withdrawals, and adverse events were extracted. The combined results of the data of the randomized controlled trials were summarized as relative risk with 95% confidence intervals.

RESULTS

The study assessed 7 randomized controlled trials including 885 patients. There was no difference in mortality at 1 year between recipients treated with tacrolimus and cyclosporine microemulsion. Tacrolimus-treated patients had less acute rejection risk at 6 months and 1 year. Fewer patients stopped tacrolimus than cyclosporine microemulsion. The rate of new-onset diabetes mellitus requiring insulin treatment was higher with tacrolimus. More post-transplantation hypertension occurred with cyclosporine microemulsion. The groups had comparable incidences of malignancy and renal failure needing dialysis.

CONCLUSIONS

The use of tacrolimus as primary immunosuppressant for heart transplant recipients results in comparable survival and a significant reduction in acute rejection compared with cyclosporine microemulsion.

Calcineurin inhibitors modulate CXCR3 splice variant expression and mediate renal cancer progression

Calcineurin inhibitors (CNI) are used to prevent inflammatory diseases and allograft rejection. However, little is known about the mechanism(s) underlying their ability to promote the development and recurrence of cancer. Recent studies suggested that the chemokine receptor CXCR3 may play important roles in tumorigenesis. CXCR3 has two splice variants with opposite functions: CXCR3-A promotes cell proliferation, and CXCR3-B inhibits cell growth. Here, we explored the effects of CNI on the expression and function of CXCR3 splice variants. Compared with normal renal tissues and renal epithelial cells, human renal cancer tissues and renal cancer cell lines demonstrated higher expression of CXCR3-A and markedly lower expression of CXCR3-B. In human renal cancer cells (786-0 and Caki-1) and renal epithelial cells, CNI markedly downregulated the expression of CXCR3-B, whereas expression of CXCR3-A was unchanged. This CNI-mediated downregulation of CXCR3-B resulted in increased proliferation and migration of renal cancer cells; CNI-mediated cell proliferation involved signaling through G(i) proteins, perhaps via CXCR3-A. Finally, it was observed that CNI treatment increased the growth of human renal tumors in vivo, and the expression of CXCR3-B was significantly decreased in these tumors. In summary, these observations suggest that CNI may mediate the progression of human renal cancer by downregulating CXCR3-B and by promoting proliferative signals, likely through CXCR3-A. Targeting CXCR3 splice variants or the signaling pathways downstream of CXCR3 receptors may provide a therapeutic strategy for the prevention of CNI-mediated renal cancer progression.

Minimization protocols in pancreas transplantation

Diagnosis of immunologic injury (acute and chronic) is much more difficult in pancreas transplants when compared with transplants of other organs. Currently, the immunosuppressive regimen for induction involves calcineurin inhibitors (CNI), antimetabolites and corticosteroids (Cs). This strong and nonspecific regimen does not take into consideration pancreas specificities (i.e. the need to avoid diabetogenic compounds). For obvious reasons, CNI might be calling for review, if permanently indicated in recipients of solitary pancreas with mild renal dysfunction. CNI as well as corticosteroids may induce hyperglycemia and contribute to differential diagnosis of a rejection process. However, in spite of the benefits accruing from withdrawal of above immunosuppressive agents, minimization or avoidance of these drugs could be dangerous and may end up with graft loss (i.e. antibody-mediated process). Long-term results of pancreas transplantation are now achieving comparable survival rates similar to the transplant of traditional organs such as kidney and liver. As a consequence, the physicians' objectives are to prolong the patient's quality of life and organ function as long as possible. Weaning strategies in regard to CNI and steroids are tested. Sirolimus, everolimus, CTLA-4 Ig, etc, are agents known to be either both nonnephrotoxic and nondiabetogenic or less so when compared with CNI. Their impact on pancreas transplantation is beginning to be evaluated. Large randomized trials in all pancreas categories, with long-term clinical and histologic results, are mandatory to establish new guidelines for immunosuppressive regimens for pancreas transplantation.

Mycophenolate mofetil: ten years' experience of a renal transplant unit

Mycophenolate mofetil (MMF) use in renal transplantation has allowed a significant decrease in early acute rejection rates. We retrospectively evaluated the incidence of acute rejection episodes, renal function at the first year posttransplant, patient and graft survivals, cytomegalovirus (CMV) infection rate, influence of the degree of sensitization, and number of MHC antigen mismatches on graft survival in two groups of patients receiving either MMF or azathioprine. Group 1 included 149 patients receiving cyclosporine, MMF, and prednisolone; group 2 included 191 patients receiving cyclosporine, azathioprine, and prednisolone. The two groups did not differ in terms of age, sex, degree of sensitization (expressed as percentage of antibodies reactive to panel), MHC mismatch number, cold ischemia time, donor age, or anti-thymocyte globulin induction. In group 1 (MMF) there was a significant decrease in early acute rejection rate (19% vs 57%, P < .0001), longer graft survival at 10 years (92% vs 75%, P = .006), and higher rate of CMV infection (22% vs 12%, P = .004). Renal function at the first year posttransplant and patient survival during follow-up did not differ between the groups. The degree of sensitization influenced graft survival in group 2. The number of MHC mismatches did not influence graft survival in either group. With MMF, there was a significant reduction in early acute rejection rate, a significant increase in graft survival at 10-year follow-up, and diminished impact of the degree of sensitization on graft survival.

Prolonging islet allograft survival using in vivo bioluminescence imaging to guide timing of antilymphocyte serum treatment of rejection

BACKGROUND

Bioluminescence imaging (BLI) is a sensitive and noninvasive method for tracking the fate of transplanted islets. The aim of this study was to investigate whether early detection of rejection by BLI can aid in the timing of antilymphocyte serum (ALS) treatment for prolonging islet graft survival.

METHODS

Transgenic islets (200 per recipient) expressing the firefly luciferase from FVB/NJ strain (H-2q) mice were transplanted under the kidney capsule of streptozotocin-induced diabetic allogeneic Balb/c strain (H-2q) mice. BLI signals and serum glucose levels were measured daily after transplant. Four groups of mice were transplanted: group 1 recipients were untreated controls (n=12), group 2 (n=8) received ALS before transplant, group 3 (n=10) received ALS at a time after transplant when normoglycemic but prompted by a reduction (approximately 30%) in BLI signal intensity for 2 consecutive days, and group 4 (n=5) received ALS after transplant when prompted by blood glucose levels increasing approximately 20% from the normoglycemic baseline (BLI reduction approximately 70%).

RESULTS

The incidence of graft loss from rejection in groups 1, 2, 3, and 4 was 92.3%, 88%, 40%, and 100%, respectively. The mean (+/-SE) time to graft loss in groups 1, 2, 3 and 4 was 22.5+/-4.8, 29.2+/-9.9, 53.5+/-17.9, and 22.1+/-2.4 days, respectively.

CONCLUSIONS

Noninvasive imaging modalities of functional islet mass, such as BLI (but not blood glucose levels), can prompt the appropriate timing of ALS treatment of islet allograft rejection and significantly prolong graft survival or protect the grafts from permanent loss.

Pharmacokinetics of mycophenolic acid, tacrolimus and sirolimus after gastric bypass surgery in end-stage renal disease and transplant patients: a pilot study

BACKGROUND

Promising data regarding the safety and efficacy of gastric bypass surgery (GBS) as an option to address obesity in the transplant population are emerging. The data lack on how GBS may alter the pharmacokinetics (PK) of modern immunosuppression. The objective of this study was to describe the alterations in the PK of modern immunosuppressants and the GBS population.

METHODS

Data are presented on six subjects who participated in this trial--four were on dialysis and two were renal transplant recipients. Dialysis-dependent bypass subjects received a single dose of 6 mg of sirolimus, two 4-mg doses of tacrolimus and two 1000-mg doses of mycophenolate mofetil (MMF) over the 24-h study period. Transplant recipients continued their current regimen. Maximum plasma concentration (C(max)), time to reach the maximum plasma concentration (T(max)) and the area under the plasma concentration vs. time curve (AUC(0-12) and AUC(0-infinity) where appropriate) were calculated for tacrolimus, sirolimus, mycophenolic acid (MPA) and mycophenolic acid glucuronide (MPAG).

RESULTS

Significant inter-patient variability in the C(max), T(max) and AUC of tacrolimus, sirolimus MPA and MPAG was observed. A notable difference in the AUC:dose ratio for tacrolimus was seen when comparing data with published data in the non-bypass population. Similar differences in PK were seen with sirolimus, MPA and MPAG.

CONCLUSIONS

When comparing the PK of sirolimus, tacrolimus, MPA and MPAG to published PK data in the non-bypass population, significant differences are observed. It is likely that transplant recipients with GBS would need higher doses of tacrolimus, sirolimus and MMF to provide similar exposure to a non-bypass patient.

Alloantigen-pulsed host dendritic cells induce T-cell regulation and prolong allograft survival in a rat model of hindlimb allotransplantation

BACKGROUND

Composite tissue allotransplantation is restricted due to the risks presented by long-term therapeutic immunosuppression. This study is conducted to investigate whether treatment with recipient immature dendritic cells (DCs) pulsed with donor alloantigens can prolong allograft survival and induce T-cell regulation in a rodent model.

MATERIALS AND METHODS

Orthotopic hindlimb transplants from Brown-Norway (RT1(n)) to Lewis (RT1(1)) rats were performed (day 0). DCs were propagated from the recipient bone marrow and pulsed with the donor alloantigen lysate. Group 1 (control group) did not receive any treatment. Groups 2 and 3 received cyclosporine A (CsA) at a concentration of 10 and 16 mg.kg(-1).day(-1), respectively, on days 0-20 following composite tissue allotransplantation. Group 4 received antilymphocyte serum (i.p. administered 4 d before and 1 d after transplantation) therapy. Group 5 received combined treatment with CsA (10 mg.kg(-1).day(-1), days 0-20) and donor alloantigen-pulsed recipient DCs (i.v. administered on days 7, 14, and 21). Group 6 received combined treatment with CsA (10 mg.kg(-1).day(-1) on days 0-20), antilymphocyte serum (administered i.p. 4 d before and 1 d after transplantation), and DCs (administered i.v. on days 7, 14, and 21). Graft rejection was defined as epidermolysis/desquamation of the donor skin. The mixed lymphocyte reaction was performed to determine the donor T-cell reactivity. Tissue samples were biopsied to analyze the histological changes, and flow cytometry was performed to quantify the donor T-cells.

RESULTS

Allograft survival was significantly prolonged (>200 d) in Group 6 when compared with the other groups (P < 0.001). The mixed lymphocyte reaction performed for Group 6 revealed hyporesponsiveness of the T-cells to donor alloantigens. Flow cytometric analysis in Group 6 revealed a significant increase in the percentage of CD4(+)/CD25(+) and CD4(+)/foxP3(+) T-cells expression, and significant increase in the percentage of donor cells (RT1(n)) in the recipient peripheral blood. Immunohistochemical staining of allo-skin revealed a significant increase in the proportion of CD25(+) cells in the subcutaneous and dermis layers in Group 6, as compared to other groups.

CONCLUSION

Treatment with donor alloantigen-pulsed recipient immature DCs in combination with transient immunosuppression prolongs allograft survival and induced tolerance by inducing T-cell hyporesponsiveness to donor alloantigens and increasing the CD4(+)/CD25(+) T-cell population.

Efficacy of interferon in immunocompromised HCV patients after liver transplantation or with HIV co-infection

BACKGROUND

Interferon (IFN)-based antiviral therapy is increasingly used in immunocompromised patients with chronic hepatitis C after orthotopic liver transplantation (OLT) and HIV-HCV co-infection. Differences in early viral kinetics have not been compared in these patients.

MATERIALS AND METHODS

We retrospectively analysed 76 patients (31 OLT, 20 HIV-HCV and 25 HCV control patients) undergoing IFN sensitivity testing before starting antiviral therapy with pegylated IFN-alpha 2a (180 microg week(-1)) plus ribavirin (0.8-1.2 g day(-1)) for 48 weeks. We compared baseline parameters, response to IFN and treatment outcome between the groups and assessed the influence of specific calcineurin inhibitors in OLT patients and immune status in HIV-HCV patients on treatment response.

RESULTS

Viral loads pretherapy were higher in OLT compared to nontransplanted HCV controls (P = 0.003). The same trend was present in HIV-HCV (P = 0.09). The log-drop after test dose was less in OLT compared to HCV (P = 0.02), while no significant difference was found between HIV-HCV and HCV. In HIV-HCV patients viral load log-drop correlated significantly with CD4(+) cell counts (P = 0.001). No difference in viral load pretherapy, log-drop and treatment outcome was noted between different calcineurin inhibitors in OLT patients. Sustained virological response rates were 28% in OLT, 50% in HIV-HCV and 56% in HCV patients.

CONCLUSIONS

Immunosuppression results in high HCV viral loads. Initial efficacy of IFN is significantly impaired in OLT patients, but not in HIV-HCV with largely preserved CD4(+) cell counts. Sustained virological response rates of 28% in OLT patients are suboptimal, but encouraging results are shown for HIV-HCV patients with relatively high CD4(+) cell counts.

Impact of acute rejection and new-onset diabetes on long-term transplant graft and patient survival

BACKGROUND AND OBJECTIVES

Development of new therapeutic strategies to improve long-term transplant outcomes requires improved understanding of the mechanisms by which these complications limit long-term transplant survival.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The association of acute rejection and new-onset diabetes was determined in the first posttransplantation year with the outcomes of transplant failure from any cause, death-censored graft loss, and death with a functioning graft in 27,707 adult recipients of first kidney-only transplants, with graft survival of at least 1 yr, performed between 1995 and 2002 in the United States.

RESULTS

In multivariate analyses, patients who developed acute rejection or new-onset diabetes had a similar risk for transplant failure from any cause, but the mechanisms of transplant failure were different: Acute rejection was associated with death-censored graft loss but only weakly associated with death with a functioning graft. In contrast new-onset diabetes was not associated with death-censored graft loss but was associated with an increased risk for death with a functioning graft.

CONCLUSIONS

Acute rejection and new-onset diabetes have a similar impact on long-term transplant survival but lead to transplant failure through different mechanisms. The mechanisms by which new-onset diabetes leads to transplant failure should be prospectively studied. Targeted therapeutic strategies to minimize the impact of various early posttransplantation complications may lead to improved long-term outcomes.

Current concepts in transplant surgery: liver transplantation today

INTRODUCTION

The discipline of liver transplantation (LTx) has been developed over the past decades, and LTx is now considered the gold standard for the treatment of patients with end-stage liver diseases and early liver tumors in cirrhotic livers. This procedure is now performed routinely in many transplant centers, and it has provided an enormous technical innovation to the field of hepatobiliary surgery. Allocation decision of liver organs is based on medical need and timing.

MATERIALS AND METHODS

The Mayo Model for End Stage Liver Disease based on patient-specific criteria was developed and applied to prioritize patients on the waiting list. From the donor aspects of LTx, sources of organ, excluding xenotransplantation, can be brain-dead donors, living donors, and non-heart-beating donors. Today, the majority of livers are procured from cadaveric donors. In addition to the conventional LTx, other types are living-donor LTx, reuse of grafts as domino transplantation, ex situ as well as in situ split LTx, and reduced-size LTx. The transplantation procedure consists of several steps including donor selection and management, liver procurement and preservation, back-table preparation, recipient operation with liver implantation, postoperative care, immunosuppression, and follow-up.

RESULTS

The postoperative complications are divided into surgical, non-surgical, and multifactorial complications. Surgical complications account about 34% of morbidities after LTx and are mainly categorized to vascular and biliary complications. The main medical ones are non-surgical bleeding and infections. The multifactorial complications include primary non- or poor function and small-for-size syndrome. The pretransplant outcome predictors of LTx can be divided into donor, recipient, operative, and postoperative factors.

CONCLUSION

LTx is now considered a safe and standardized procedure with a substantially improved graft and patient survival and acceptable morbidity rates. However, the new problems, including recurrence of hepatitis C or hepatocellular carcinoma, chronic biliary complications, opportunistic infections, and development of de-novo malignancies are the major problems affecting the long-term outcome of transplanted patients.