Features of acute rejection that increase risk for chronic rejection

An Enhanced Role of Innate Immunity in the Immune Response After Kidney Transplant in People Living With HIV: A Transcriptomic Analysis

BACKGROUND

Although kidney transplantation (KT) has become the standard of care for people living with HIV (PLWH) suffering from renal failure, early experiences revealed unanticipated higher rejection rates than those observed in HIV- recipients. The cause of increased acute rejection (AR) in PLWH was assessed by performing a transcriptomic analysis of biopsy specimens, comparing HIV+ to HIV- recipients.

METHODS

An analysis of 68 (34 HIV+, 34 HIV-) formalin-fixed paraffin-embedded (FFPE) renal biopsies matched for degree of inflammation was performed from KT recipients with acute T cell-mediated rejection (aTCMR), borderline for aTCMR (BL), and normal findings. Gene expression was measured using the NanoString platform on a custom gene panel to assess differential gene expression (DE) and pathway analysis (PA).

RESULTS

DE analysis revealed multiple genes with significantly increased expression in the HIV+ cohort in aTCMR and BL relative to the HIV- cohort. PA of these genes showed enrichment of various inflammatory pathways, particularly innate immune pathways associated with Toll-like receptors.

CONCLUSIONS

Upregulation of the innate immune pathways in the biopsies of PLWH with aTCMR and BL is suggestive of a unique immune response that may stem from immune dysregulation related to HIV infection. These findings suggest that these unique HIV-driven pathways may in part be contributory to the increased incidence of allograft rejection after renal transplantation in PLWH.

HDAC6 inhibition: a significant potential regulator and therapeutic option to translate into clinical practice in renal transplantation

Histone deacetylase 6 (HDAC6), an almost exclusively cytoplasmic enzyme, plays an essential role in many biological processes and exerts its deacetylation-dependent/independent effects on a variety of target molecules, which has contributed to the flourishing growth of relatively isoform-specific enzyme inhibitors. Renal transplantation (RT) is one of the alternatively preferred treatments and the most cost-effective treatment approaches for the great majority of patients with end-stage renal disease (ESRD). HDAC6 expression and activity have recently been shown to be increased in kidney disease in a number of studies. To date, a substantial amount of validated studies has identified HDAC6 as a pivotal modulator of innate and adaptive immunity, and HDAC6 inhibitors (HDAC6i) are being developed and investigated for use in arrays of immune-related diseases, making HDAC6i a promising therapeutic candidate for the management of a variety of renal diseases. Based on accumulating evidence, HDAC6i markedly open up new avenues for therapeutic intervention to protect against oxidative stress-induced damage, tip the balance in favor of the generation of tolerance-related immune cells, and attenuate fibrosis by inhibiting multiple activations of cell profibrotic signaling pathways. Taken together, we have a point of view that targeting HDAC6 may be a novel approach for the therapeutic strategy of RT-related complications, including consequences of ischemia-reperfusion injury, induction of immune tolerance in transplantation, equilibrium of rejection, and improvement of chronic renal graft interstitial fibrosis after transplantation in patients. Herein, we will elaborate on the unique function of HDAC6, which focuses on therapeutical mechanism of action related to immunological events with a general account of the tantalizing potential to the clinic.

Estimated Renal Metabolomics at Reperfusion Predicts One-Year Kidney Graft Function

Renal transplantation is the gold-standard procedure for end-stage renal disease patients, improving quality of life and life expectancy. Despite continuous advancement in the management of post-transplant complications, progress is still needed to increase the graft lifespan. Early identification of patients at risk of rapid graft failure is critical to optimize their management and slow the progression of the disease. In 42 kidney grafts undergoing protocol biopsies at reperfusion, we estimated the renal metabolome from RNAseq data. The estimated metabolites' abundance was further used to predict the renal function within the first year of transplantation through a random forest machine learning algorithm. Using repeated K-fold cross-validation we first built and then tuned our model on a training dataset. The optimal model accurately predicted the one-year eGFR, with an out-of-bag root mean square root error (RMSE) that was 11.8 ± 7.2 mL/min/1.73 m2. The performance was similar in the test dataset, with a RMSE of 12.2 ± 3.2 mL/min/1.73 m2. This model outperformed classic statistical models. Reperfusion renal metabolome may be used to predict renal function one year after allograft kidney recipients.

Future Immunosuppressive Agents in Solid-Organ Transplantation

Objective

To review the pharmacology, pharmacokinetics, efficacy, and safety of mycophenolate sodium, everolimus, and FTY720.

Study Selection and Data Extraction

Clinical trials and abstracts evaluating mycophenolate sodium, everolimus, and FTY720 in solid-organ transplantation were considered for evaluation. English-language studies and published abstracts were selected for inclusion.

Data Synthesis

Mycophenolate sodium has recently been approved by the Food and Drug Adminstration for marketing in the United States; everolimus and FTY720 are immunosuppressive agents that may soon be available in the United States. These agents have proven efficacy in reducing the incidence of acute rejection in solid-organ transplantation. Clinical trials have shown that these newer agents are relatively well tolerated. The most common adverse events associated with these agents were gastrointestinal and hematologic effects (mycophenolate sodium); hyperlipidemia, increased serum creatinine, and hematologic effects (everolimus); and gastrointestinal effects, headache, and bradycardia (FTY720).

Conclusion

Mycophenolate sodium has been approved in some European countries and the United States. Everolimus has been approved in some European countries and a new drug application has been submitted to the Food and Drug Administration. FTY720 is currently in phase III clinical trials and submission to the Food and Drug Administration for approval is a few years away. The approval of these agents will furnish the transplant practitioner with even more options for immunosuppression.

Acute Rejection Clinically Defined Phenotypes Correlate With Long-term Renal Allograft Survival

BACKGROUND

Classification of acute rejection (AR) based on etiology and timing may provide a means for enhancing therapeutic results and allograft survival. This study evaluated graft and patient survival after the first AR episodes among kidney transplant recipients with an early or late antibody-mediated rejection (AMR), acute cellular rejection (ACR) or mixed AR (MAR).

METHODS

A prospective institutional review board-approved database was queried to identify biopsy-proven first AR episodes occurring from January 2005 to October 2012. The ACR was defined by Banff criteria; borderline AR was excluded. The AMR was defined as 3 of 4 criteria: renal dysfunction, donor specific antibody, C4d positivity on biopsy, and histological changes. The MAR met criteria for both ACR and AMR. Early AR occurred within six months post-transplant. AR episodes were then assigned to 1 of the 6 categories--early AMR, early ACR, early MAR, late AMR, late ACR, and late MAR.

RESULTS

One hundred eighty-two kidney transplant recipients identified with a first AR episode. Mean follow-up was 773 days (± 715 days). No difference was observed in patient survival. Death-censored graft survival was 84%. Death-censored graft loss was higher with late versus early AMR (P = 0.01) and late versus early ACR (P = 0.03), but not late versus early MAR (P = 0.3).

CONCLUSIONS

The AR type demonstrated a hierarchy for graft survival with ACR better than MAR better than AMR, which persisted for both early and late AR. Improvement in long-term results of AR may require development of specific treatment for individual AR types.

High proportion of pretransplantation activated regulatory T cells (CD4+CD25highCD62L+CD45RO+) predicts acute rejection in kidney transplantation: results of a multicenter study

BACKGROUND

Prognostic biomarkers of acute rejection (AR) in solid organ transplantation have been addressed in multiple small retrospective studies, and there is a critical need for multicenter studies. Because of their tolerogenic properties, regulatory T cells (Tregs) play an important role in transplant outcome.

METHODS

In the present multicenter study, we have retrospectively examined different Treg subpopulations in an independent cohort of kidney transplant patients within first year after kidney transplantation. All participating centers used identical flow cytometry standard operating procedures.

RESULTS

Seventy-five renal transplant patients were included, and six of them experienced an AR episode. The activated Treg (aTreg) subpopulation (CD4CD25CD62LCD45RO) was increased in the AR group before transplantation, and an aTreg percentage higher than 1.46% before kidney transplantation conferred an increased risk of AR. The univariate logistic regression model achieved an area under the curve of 81.6%. By including recipient age and thymoglobulin induction as variables in a multivariate logistic regression model, the prediction of AR improved to 92.4%.

CONCLUSION

The evaluation of CD4CD25CD62LCD45RO aTreg cells may be useful as pretransplantation predictive biomarker of AR in kidney transplant patients. Definitive confirmation of our results awaits tests in validation groups.

[The impact of obesity on renal function at one year after kidney transplantation: single-center experience]

INTRODUCTION

Kidney transplantation is the treatment of choice for ESRD. Several studies have investigated the factors that may affect kidney function at 1 year. The factors mentioned are anemia, hypercholesterolemia, immunosuppressors, etc. We studied the independent predictors of serum creatinine>100μmol/L at 1 year.

MATERIALS AND METHODS

We conducted a retrospective study from March 1999 to December 2009. We conducted a chart review of 402 kidney transplant patients. The kidneys were removed from cadaveric donors. Data collected included age, weight, height, preoperative BMI, the causal nephropathy, smoking, hypertension, diabetes, anticoagulation. Intraoperative data included operative time, and cold ischemia. Statistical analysis consisted of a t-test for independent samples comparing the group with a creatinine≤100μmol/L vs>100 group, and univariate and multivariate Cox regression for a serum creatinine>100μmol/L at 1 year and test of correlation between BMI and serum creatinine at 1 year postoperatively.

RESULTS

We found a significant difference in BMI and cold ischemia with P=0.008 and P=0.002, respectively. In contrast there was no difference in age, operative time and blood loss, P=0.758, P=0.941 and P=0.963, respectively. Multivariate Cox regression showed that donor age P=0.004 (HR: 1.016 and CI: 1.005-1.027), a recipient age P=0.023 (HR: 0.986 and CI: 0.974-0.998) and BMI P=0.001 (HR: 1.019 and CI: 1.010-1.028) were independent predictors of serum creatinine>100μmol/L at 1 year. The Pearson correlation coefficient r=0.154 (P=0.004) showed a significant correlation between BMI and serum creatinine.

CONCLUSION

Our study showed that donor age, recipient age and BMI were independent predictors of renal function>100μmol/L at 1 year. Our results highlight the difficulty of the management of obesity in renal transplant patients.

LEVEL OF EVIDENCE

5.

First clinical experience with polysol solution: pilot study in living kidney transplantation

In this study, we assessed the safety of the new organ preservation solution polysol solution in the clinical setting of living kidney transplantation. We conducted a prospective pilot study in nine adult donor-recipient couples using polysol solution for washout and cold storage of kidney grafts. Adverse reactions possibly related to the use of polysol solution as well as renal function at 1, 6, and 12 months after transplantation were monitored. All living kidney transplantation performed in adults in our center within 2002 to 2008 using the University of Winconsin solution served as controls (n = 190). The use of polysol solution was associated with a higher acute rejection rate compared to University of Wisconsin solution at all time points. Also, antibody-mediated rejection occurred more frequently in the polysol group. Renal function at all time points was also comparable between the groups. This pilot study in living kidney transplantation is the first clinical study on the use of polysol solution. Although the study was not powered on the endpoint rejection, we observed a high number of acute rejection and antibody-mediated rejection episodes in recipients of polysol solution preserved grafts as compared to University of Wisconsin solution controls. As a consequence the study was terminated prematurely.

Risk factors for steroid-resistant T-cell-mediated acute cellular rejection and their effect on kidney graft and patient outcome

OBJECTIVES

Acute rejection in renal transplant is considered a risk factor for short-term and long-term allograft survival. The expected reversal rate for the first acute cellular rejection, by steroid pulse, ranges between 60% and 100%, and lack of improvement within 1 week of treatment is defined as steroid-resistant rejection. This work sought to evaluate factors that lead to steroid-resistant acute cellular rejection among patients with first live-donor renal allotransplant and its effect on graft and patient survival.

MATERIALS AND METHODS

Patients with an improvement in serum creatinine levels were considered controls (group 1; n=100); while the others were considered an early steroid-resistant group (group 2; n=99). Both groups were matched demographically.

RESULTS

Patients with a target cyclosporine level below accepted therapeutic levels were significantly higher in group 2 (P = .02). We found no significant differences between the groups regarding posttransplant complications (P > .05). Mean hospital stay was longer in group 2 (P = .021). Living patients with functioning graft were more prevalent in group 1, while those alive on dialysis were more prevalent in group 2. The groups were comparable regarding long-term patient and graft survival despite significantly lower creatinine values in patients of group 1 at 6 months' follow-up (P ≤ .001).

CONCLUSIONS

Prebiopsy low cyclosporine trough levels and associated chronic changes among patients who were maintained on calcineurin inhibitor-based regimens represented the most-important risk factors for the early steroid-resistant group. Rescue therapies improve short-term graft outcome; however, they did not affect either patient or long-term graft survival after 5 years' follow-up.

Renal function following living, standard criteria deceased and expanded criteria deceased donor kidney transplantation: impact on graft failure and death

We examined United States Renal Data System (USRDS) data for adult kidney transplant recipients in 1995-2003 (n = 87 575) to investigate associations of 12-month renal function with long-term clinical outcomes. Estimated glomerular filtration rate (eGFR) was computed by the Modification of Diet in Renal Disease (MDRD) equation. Associations of eGFR at the first transplant anniversary with graft and patient-survival in years 1-9 post-transplant were evaluated by multivariate nonlinear regression with spline forms, adjusted for recipient, donor, and transplant factors. Regardless of donor type, the likelihood of graft failure and death increased significantly with lower eGFR. The impact of poor eGFR was more pronounced for graft failure than death. Relative effects were similar across donor types, but were strongest among living-donor recipients. For example, compared with reference eGFR of 80 ml/min/1.73 m2, 1-year eGFR of 20 ml/min/1.73 m2 was associated with adjusted hazards ratios for subsequent death-censored graft failure of 9.2 in living, 8.9 in standard criteria deceased, and 5.9 in expanded criteria deceased-donor recipients. First-year renal function after kidney transplantation has strong, nonlinear associations with subsequent allograft and patient survival regardless of donor type. Post-transplant eGFR may be a useful end-point for discriminating benefits of care strategies that differentially affect renal function.

Higher infiltration by Th17 cells compared with regulatory T cells is associated with severe acute T-cell-mediated graft rejection

The aim of this study was to evaluate whether the Th17 and Treg cell infiltration into allograft tissue is associated with the severity of allograft dysfunction and tissue injury in acute T cell-mediated rejection (ATCMR). Seventy-one allograft tissues with biopsy-proven ATCMR were included. The biopsy specimens were immunostained for FOXP3 and IL-17. The allograft function was assessed at biopsy by measuring serum creatinine (Scr) concentration, and by applying the modified diet in renal disease (MDRD) formula, which provides the estimated glomerular filtration rate (eGFR). The severity of allograft tissue injury was assessed by calculating tissue injury scores using the Banff classification. The average numbers of infiltrating Treg and Th17 cells were 11.6 ± 12.2 cells/mm² and 5.6 ± 8.0 cells/mm², respectively. The average Treg/Th17 ratio was 5.6 ± 8.2. The Treg/Th17 ratio was significantly associated with allograft function (Scr and MDRD eGFR) and with the severity of interstitial injury and tubular injury (P < 0.05, all parameters). In separate analyses of the number of infiltrating Treg and Th17 cells, Th17 cell infiltration was significantly associated with allograft function and the severity of tissue injury. By contrast, Treg cell infiltration was not significantly associated with allograft dysfunction or the severity of tissue injury. The results of this study show that higher infiltration of Th17 cell compared with Treg cell is significantly associated with the severity of allograft dysfunction and tissue injury.

Consideration of donor age and human leukocyte antigen matching in the setting of multiple potential living kidney donors

BACKGROUND

Defining living donor (LD)-related risk factors affecting kidney transplant outcome will allow better donor selection and more educated informed consent when there is more than one potential donor. We studied risk factors in a large cohort at a single institution.

METHODS

We reviewed 1632 recipients who underwent LD kidney transplantation at the University of Minnesota between January 1, 1990, and October 1, 2009. Using Cox regression, we studied the effect of donor and recipient risk factors on patient and graft survival. We specifically examined the effect of donor age and human leukocyte antigen (HLA) matching because these are variables that may help clinical decision making when multiple potential donors exist.

RESULTS

Mean donor age was 40.6 years for all transplants; 180 (11%) donors were 55 years or older, and 24 (1.5%) donors were older than 65 years. Mean number of HLA mismatches (per transplant) was 2.9 (29.2% of recipients had one to two HLA mismatches, 39.8% had three to four HLA mismatches, and 25% had five to six HLA mismatches). Donor age more than 65 years, five to six HLA mismatches, delayed graft function, and acute rejection were independent predictors of decreased patient and graft survival. When controlling for recipient age, donor age more than 65 years remained a risk factor for worse outcome.

CONCLUSIONS

Our data suggest that advanced donor age (>65 years) and degree of HLA mismatch (≥5) are independent donor-related risk factors associated with worse outcome. When multiple potential LDs exist, it may be ideal to attempt to use a donor younger than 65 years and with less than five HLA mismatches.

Improving long-term renal allograft survival via a road less traveled by

It has become cliché to state that improvements in early renal allograft survival over the past two decades have not led to increased long-term renal allograft survival. However, it is not clear how long-term graft survival can be improved. Here, we present the viewpoint that the road forward does not involve searching for new and more ideal immunosuppressive regimens, but rather detailed patient follow-up to identify specific causes of late renal allograft loss and the development of new therapy designed to address these problems before allograft damage becomes irreversible.

The histology of solitary renal allografts at 1 and 5 years after transplantation

Previous studies suggest that the majority of renal allografts are affected by progressive, severe chronic histologic injury, yet studies using current protocols are lacking. The goal of this study was to examine the prevalence and progression of histologic changes using protocol allograft biopsies at 1 and 5 years after solitary kidney transplantation in patients transplanted between 1998 and 2004. Chronic histologic changes generally were mild at both 1 and 5 years and were similar in deceased and living donor kidneys. The overall prevalence of moderate or severe fibrosis was 13% (60/447) at 1 year and 17% (60/343) at 5 years. In a subgroup of 296 patients who underwent both 1- and 5-year biopsies, mild fibrosis present at 1 year progressed to more severe forms at 5 years in 23% of allografts. The prevalence of moderate or severe arteriolar hyalinosis was similar in tacrolimus and calcineurin inhibitor-free immunosuppression. These results in the recent era of transplantation demonstrate fewer, less severe and less progressive chronic histologic changes in the first 5 years after transplantation than previously reported.

Clinical significance of slow recovery of graft function in living donor kidney transplantation

BACKGROUND

The clinical significance of slow recovery of graft function (SGF) in living donor kidney transplantation is unclear. We evaluated the incidence, risk factors, and clinical outcome of SGF in living donor transplantation.

METHODS

Three hundred ten living donor kidney recipients were included and categorized into immediate recovery of graft function (IGF; n=239) and SGF (n=71), according to estimated glomerular filtration rate (60 mL/min/1.73 m) at posttransplant day 14. We compared the clinical parameters, protocol biopsy findings, acute rejection (AR), and 10-year graft survival between the two groups.

RESULTS

The SGF group had an older recipient age, lower ratio of donor to recipient body mass index, and higher incidence of AR than IGF group, as shown by protocol biopsies. The SGF group had significantly more AR episodes than IGF group within 12 months (21.1% vs. 13.4%, P<0.05) and during follow-up period (32.4% vs. 20.1%, P<0.05). The 10-year graft survival rate did not differ between groups, but AR presence was significantly associated with a lower graft survival in the SGF group than the IGF group (64.9% vs. 78.9%, P<0.05).

CONCLUSIONS

SGF in the early posttransplant period is immunologically active and should be considered as one of the risk factors for determining long-term graft survival in living donor kidney transplantation.

Clinical impacts of CD38+ B cells on acute cellular rejection with CD20+ B cells in renal allograft

BACKGROUND

There is an increasing evidence that the presence of CD20 B cells is associated with poor clinical outcomes in acute cellular rejection (ACR), but clinical significance of CD38 B cells is undetermined. We attempted to examine the clinical significance of the CD38 B cells alone or in combination with CD20 B cells in renal transplant recipients with ACR.

METHODS

Fifty-four patients with ACR were included. Biopsy specimens were stained for CD20 and CD38. The clinical outcomes of CD20 or CD38 B cells were evaluated with late-onset and repeated ACR, steroid resistance, incomplete recovery after rejection treatment, and allograft survival.

RESULTS

Twenty-three patients (42.6%) had CD20 and 25 (46.3%) patients had CD38 B cells. Of these, 15 patients (27.8%) were positive for both CD20 and CD38 (CD20CD38). CD38 patients had higher rates of late-onset or repeated ACR and incomplete recovery compared with CD38 patients (P<0.05). The patients with CD20CD38 had a higher incomplete recovery rate than did patients with only CD20 or CD38 (P<0.05). The 5-year allograft survival was lower in CD20 and CD38 patients than in CD20 or CD38 patients (P<0.05 for each). CD20CD38 patients had lower graft survival than did patients with CD20 or CD38 alone (P<0.05).

CONCLUSION

Infiltration of CD38 B cells alone or in combination with CD20 B cells is a predictor for poor clinical outcomes of ACR in renal allograft.

Steroid avoidance or withdrawal after renal transplantation increases the risk of acute rejection but decreases cardiovascular risk. A meta-analysis

INTRODUCTION

The morbidity related to long-term steroid therapy has led to continued interest in withdrawal of steroids from immunosuppressant regimens after renal transplantation. A number of recent trials have provided long-term information regarding the risks and benefits of steroid avoidance or withdrawal (SAW).

METHODS

A literature search was performed using Ovid Medline, Embase, the Cochrane Library, and the Transplant Library. Randomized controlled trials comparing a maintenance steroid group with complete avoidance or withdrawal of steroids were selected. All studies were assessed for methodological quality. Trials were pooled by meta-analysis to provide summary effects (relative risk [RR] or weighted mean difference) with 95% confidence intervals (CI).

RESULTS

Thirty-four studies including 5,637 patients met the inclusion criteria. SAW regimens significantly increased the risk of acute rejection (AR) over maintenance steroids (RR 1.56, CI 1.31-1.87, P<0.0001). No significant differences in corticosteroid resistant AR, patient survival, or graft survival were observed. Serum creatinine was increased and creatinine clearance was reduced with SAW. Cardiovascular risk factors including incidence of hypertension (RR 0.90, CI 0.85-0.94, P<0.0001), new onset diabetes (RR 0.64, CI 0.50-0.83, P=0.0006), and hypercholesterolemia (RR 0.76, CI 0.67-0.87, P<0.0001) were reduced significantly by SAW.

CONCLUSION

Despite an increase in the risk of AR with SAW protocols, there is only a small effect on graft function with no measurable effect on graft or patient survival. There are significant benefits in cardiovascular risk profiles after SAW. SAW protocols would seem justified with current immunosuppressive protocols in low-risk recipients.

Acute Rejection Features in Dual Kidney Transplant Recipients from Elderly Donors: Comparison of Calcineurin Inhibitor-Based and Calcineurin Inhibitor-Free Immunosuppressive Protocols

Features of acute rejection in dual kidney transplant have not been studied. The aim of this study is to compare acute rejections in dual kidney transplant recipients from elderly donors on different immunosuppressive protocols. Sixty-nine patients were evaluated: 28 received calcineurin inhibitor-based (group 1) and 41 received calcineurin inhibitor-free immunosuppression (group 2). Histology of all donor kidneys was evaluated before implantation. All rejections showed tubulitis in both groups, and were classified as T cell-mediated acute rejections. Incidence and Banff grade of rejections in the two groups were not significantly different. Late rejections however, were observed in group 1 ( P < 0.01) whereas steroid-resistant rejections occurred in group 2 ( P < 0.03). C4d deposition was only observed in group 2. Occurrence of acute rejection was significantly associated with graft loss due to interstitial fibrosis/tubular atrophy in both groups. In group 1 mean serum creatinine levels of patients with rejections at six months and one year were higher than those of patients without rejections ( P < 0.03 and P < 0.009, respectively). In group 2 they were higher at six months ( P < 0.01) but not at one year. In addition, graft loss due to interstitial fibrosis/tubular atrophy occurred in 3/28 patients in group 1 (10.7%, OR= 1.95, 95%CI 1.02–3.71), and in 1/41 patients in group 2 (2.4%, OR= 0.41, 95%CI 0.07–2.24). Taken together these results suggest better renal function in patients on calcineurin inhibitor-free immunosuppression. In conclusion, acute rejections were detrimental irrespective of the type of immunosuppression, but different features were observed with each therapy. A tailored approach should be advantageous for prevention and treatment of acute rejections.

Immunosuppression for lung transplantation

As a result of advances in surgical techniques, immunosuppressive therapy, and postoperative management, lung transplantation has become an established therapeutic option for individuals with a variety of end-stage lung diseases. The current 1-year actuarial survival rate following lung transplantation is approaching 80%. However, the 5- year actuarial survival rate has remained virtually unchanged at approximately 50% over the last 15 years due to the processes of acute and chronic lung allograft rejection (1). Clinicians still rely on a vast array of immunosuppressive agents to suppress the process of graft rejection, but find themselves limited by an inescapable therapeutic paradox. Insufficient immunosuppression results in graft loss due to rejection, while excess immunosuppression results in increased morbidity and mortality from opportunistic infections and malignancies. Indeed, graft rejection, infection, and malignancy are the three principal causes of mortality for the lung transplant recipient. One should also keep in mind that graft loss in a lung transplant recipient is usually a fatal event, since there is no practical means of long-term mechanical support, and since the prospects of re-transplantation are low, given the shortage of acceptable donor grafts. This chapter reviews the current state of immunosuppressive therapy for lung transplantation and suggests alternative paradigms for the management of future lung transplant recipients.

Long-term outcome of pediatric renal transplantation: the Norwegian experience in three eras 1970-2006

During the years 1970-2006, 251 renal transplantations were performed in 178 children in Norway. The proportion of LD was 84%. Transplantations were performed preemptively in 52%. Pretransplant dialysis time was median three months. Structural abnormalities and hereditary renal disorders constituted 69% of end-stage renal diseases, 29% were caused by glomerulopathies and other acquired disorders and 2% of unknown cause. Patient survival rates were 94.2, 93.5, and 84.4% at five, 10, and 20 yr, respectively. The most frequent cause of death was infections followed by cardiovascular events. For recipients of living donor grafts (n = 149), survival of first transplant was 82, 68.8, and 45.1% at five, 10, and 20 yr, respectively, and was significantly higher than for recipients of deceased donor organs (n = 29; log rank, p = 0.008). The only significant predictor for better transplant survival when modeled with multiple regression analysis adjusted for pretransplant dialysis, diagnosis, donor age, sex and immunosuppressive era, was the use of LD compared with DD (HR = 2.1, 95% CI [1.1-4.0], p = 0.02). The acute rejection rate declined significantly from 61.5% in 1970-1982 to 14.5% in 2000-2006 (log rank, p = 0.002). It remains to be seen whether the reduction in acute rejection rate and present immunosuppressive therapy will have a positive impact on long-term graft survival in years to come.

Steroid avoidance regimens: a comparison of outcomes with maintenance steroids versus continued steroid avoidance in recipients having an acute rejection episode

Roughly 15% of kidney transplant recipients on a rapid discontinuation of prednisone (RDP) protocol have > or =1 episode of acute rejection (AR). One clinically important question is whether long-term maintenance steroids should be introduced in those recipients having AR. Of 842 adult kidney transplant recipients on an RDP protocol, 149 (17.7%) have had at least 1 AR episode. Of these, 51 (34%) started on maintenance prednisone (5 mg/day) after treatment of the AR, while 98 (66%) remained steroid free. Demographics for the two groups were similar. With mean follow-up of 26 months, 48 (32%) of the recipients have had a 2nd AR episode: 15 (29.4%) in those on maintenance steroids vs. 33 (33.7%) in those remaining steroid free (p = 0.12). Graft survival was not significantly different between the two groups. Multivariate analysis of risk factors for a 2nd episode found the histologic appearance of the initial AR episode to be the most significant risk factor. But, whether steroids were added to the maintenance regimen or not, also seemed to have an impact (RR = 2.1, p = 0.07). At present there is evidence to suggest that some SA patients should start on maintenance steroids after AR. However, longer follow-up with more patients is necessary.

Chronic Allograft Nephropathy

Chronic allograft nephropathy (CAN) remains the Achilles heel of renal transplantation. In spite of the significant strides achieved in one-year renal allograft survival with newer immunosuppressant strategies, the fate of long-term renal allograft survival remains unchanged. The number of renal transplant recipients returning to dialysis has doubled in the past decade. This is especially important since these patients pose a significantly increased likelihood of dying while on the waiting list for retransplantation, due to increasing disparity between donor organ availability versus demand and longer waiting time secondary to heightened immunologic sensitization from their prior transplants. In this review we analyze the latest literature in detail and discuss the definition, natural history, pathophysiology, alloantigen dependent and independent factors that play a crucial role in CAN and the potential newer therapeutic targets on the horizon. This article highlights the importance of early identification and careful management of all the potential contributing factors with particular emphasis on prevention rather than cure of CAN as the core management strategy.

Cadaveric kidney transplantation: five years experience at a single center

BACKGROUND

In the past, the majority of renal transplantations in Iran were from living donors, but recently cadaveric donation of organs is increasing. We reviewed our experience on kidney transplantation from cadaveric donors for the past 5 years in our center.

METHODS

Between July 1998 and September 2004, 122 kidneys were removed from 61 cases of brain-dead patients and transplanted in 114 patients with end-stage renal disease in our center. Two kidneys had tumoral involvement and were discarded. Three kidneys were transplanted in other centers and three patients received en bloc kidney transplantations. In addition, we performed nine cases of heart, one case of liver, and one case of lung transplantations. All the recipients were followed for at least 1 year and posttreatment renal function and graft survival were determined.

RESULTS

All cadaveric donors were brain dead due to car (30%) and motocycle (70%) accidents, with ages ranging from 5 to 56 years (mean, 24/4 years). The mean warm and total cold ischemia times were 7 minutes and 8.1 hours, respectively. The mean distance between harvesting center and our hospital was 65 km. The 1-year graft survival was 92.3%, with mean serum creatinine of 1.76 +/- 0.79 at 1 year. Of other transplanted organs, the liver and lung recipients died 24 hours and 45 days after operation. Among heart recipients, four are still alive.

CONCLUSION

Cadaveric donors in developing countries including Iran can be excellent sources of organ donation.

Why hasn't eliminating acute rejection improved graft survival?

Although patients with end-stage renal disease can be maintained with dialysis therapy, the superiority of patient survival with renal transplantation makes transplantation the preferred method of renal replacement. Potent immunosuppressive therapies, particularly calcineurin inhibitors, have greatly reduced the incidence of acute rejection. However, long-term allograft survival remains limited. We discuss the impact of acute rejection on long-term allograft survival and discuss other factors leading to late allograft loss, including calcineurin inhibitor toxicity, chronic allograft nephropathy, and BK virus nephropathy, as well as donor and recipient factors associated with long-term allograft loss.

Risk factors for rising creatinine in renal allografts with 1 and 3 yr survival

BACKGROUND

Determining factors associated with negative slope of inverse creatinine vs. time (1/Cr vs. t) may help prevent a decline in renal allograft function.

METHODS

A total of 1389 adult recipients of primary renal transplants were divided into quartiles based on the slope of 1/Cr vs. t calculated from 6 and 12 months post transplant. A multivariate analysis of risk factors for being in the worst vs. best quartile employed these variables: donor source, HLA mismatch, recipient age, donor age, panel-reactive antibody (PRA), acute rejection (AR), 3-month cyclosporin A (CsA) level, 1-yr CsA level and acute tubular necrosis. Two separate analyses compared risk factors in patients with 1 and 3 yr survival, respectively.

RESULTS

In recipients with > or = 1 yr graft survival, high PRA and AR were associated with negative slopes of 1/Cr vs. t. For those with > or = 3 yr graft survival, both AR and 3-month CsA level > 150 ng/mL were significant risk factors, using both 6- and 12-month slopes. Stratification of AR showed 1 AR episode > or = 6 months and multiple AR episodes carried significant risk for negative slopes.

CONCLUSION

Optimization of allograft function invokes a conundrum between the needs to avoid both AR and high early CsA levels. We support a policy of carefully balancing these two risks.

Recipient age and risk of chronic allograft nephropathy in primary deceased donor kidney transplant

Single center and registry data studies have had conflicting results regarding the impact of recipient age on chronic allograft nephropathy (CAN). We tested the hypothesis that advanced recipient age is a risk factor for graft failure due to CAN. All patients who underwent primary deceased donor kidney transplant between January 1, 1995 and December 31, 2000 recorded in the United Network of Organ Sharing (UNOS) database were analyzed for the occurrence of death censored graft loss and by two different definitions of graft loss due to CAN. Kaplan-Meier analysis based on the recipient age, and Cox proportional hazard regression was used to estimate the independent effect of recipient age on the three endpoints of interest. For all endpoints, after age of 9 years, the risk of graft loss declined with each successive decade increase in age. This pattern of risk was similar for both Caucasian and African-American recipients, although for any given age the risk of graft loss was always higher in African-American recipients. Analysis of UNOS data does not support the hypothesis that advanced recipient age is a risk factor for CAN.

Overcoming Barriers to Long-Term Graft Survival

Although short-term kidney graft survival has improved in recent years, the focus has shifted to the challenge of improving long-term graft survival. Acute rejection, chronic allograft nephropathy, and cardiovascular disease are associated with graft loss and patient death. Reducing the potential for such posttransplantation complications may improve long-term graft survival. In addition, gaining a better understanding of the role that various immunosuppressive therapies have in decreasing the risk for graft injury will help clinicians make better-informed decisions about appropriate treatment regimens for individual kidney transplant recipients.

Chronic allograft nephropathy

With the advent of calcineurin inhibitors, the success of kidney and other solid-organ transplants has improved significantly from the standpoint of reducing the incidence of acute rejection. Over the past 2 decades, both short-term allograft survival and acute rejection rates have dramatically improved with improved diagnostic and therapeutic techniques such as standardized pathology scoring; potent antirejection drugs such as anti-thymocyte globulin, interleukin-2 receptor antibodies, cyclosporine, tacrolimus, sirolimus, and mycophenolate mofetil; and improved infection control such as valganciclovir and antifungal therapy. However, long-term graft loss has remained at nearly constant levels over the same period of time, with the average half-life of a deceased-donor kidney transplant in the United States remaining approximately 1 decade. In addition to death with a functioning allograft and calcineurin toxicity, a chronic fibrotic process-known at various times as chronic rejection, chronic allograft dysfunction, and chronic allograft nephropathy (CAN)-account for the leading causes of transplant failure.

Immunosuppression for lung transplantation

As a result of advances in surgical techniques, immunosuppressive therapy, and postoperative management, lung transplantation has become an established therapeutic option for individuals with a variety of end-stage lung diseases. The current 1-year actuarial survival rate following lung transplantation is approximately 75%. However, the processes of acute and chronic lung allograft rejection have limited the long-term success of lung transplantation. Clinicians currently rely on a vast armamentarium of immunosuppressive agents to ameliorate graft rejection, but find themselves limited by an inescapable therapeutic paradox. Insufficient immunosuppression results in graft loss due to rejection, while excess immunosuppression results in increased morbidity and mortality from opportunistic infections and malignancies. Indeed, graft rejection, infection, and malignancy are the three principal causes of mortality for the lung transplant recipient. One should also keep in mind that graft loss in a lung transplant recipient is usually a fatal event, since there is no practical means of long-term mechanical support, and since the prospects of re-transplantation are low, given the shortage of acceptable donor grafts. This chapter reviews the current state of immunosuppressive therapy for lung transplantation, and suggests alternative paradigms for the management of future lung transplant recipients.

Influence of kidney function to the impact of acute rejection on long-term kidney transplant survival

In kidney transplantation, timing of an initial acute rejection (AR) is correlated with a variable risk of graft loss. However, it is unknown whether the increased risk for graft loss because of AR is conditioned by impaired graft function. A total of 730 cadaveric kidney transplant recipients were retrospectively evaluated from 1994 to 2001. When AR occurred, the risk ratio (RR) for graft loss was strongly time-dependent and increased, the later the rejection episode occurred. Compared with the reference group (no rejection) having an AR within 0-30, 31-365, or >365 days post-transplant conferred a 3.1-, 9.1- and 49.3-fold risk for subsequent graft loss (P < 0.001). By including serum creatinine as an indicator for graft function at the time of rejection RR decreased to 2.4-, 7.1- and 21.8-fold, but remained still significant (P = 0.023). In conclusion, the higher risk of graft loss after late AR is not fully explained by impaired graft function measured by serum creatinine.

Implications of Immunohistochemical Detection of C4d along Peritubular Capillaries in Late Acute Renal Allograft Rejection

BACKGROUND

Immunohistochemical detection of the C4d complement product along peritubular capillaries (PC) may indicate humoral rejection of renal allografts. We examined the frequency of PC C4d expression in renal-allograft biopsies with acute rejection (AR) arising more than 6 months after transplantation and the impact of this finding.

METHODS

C4d was detected by immunoperoxidase in 2-micron paraffin sections of consecutive biopsies obtained over a 3-year period. The extent was classified as diffuse (> or =50% PC C4d+), focal (<50% C4d+), and negative (C4d-). Clinical data were obtained by retrospective chart review. Fifty-five AR episodes with Banff 97 types 1A (n = 13), 1B (n = 26), 2A (n = 11), 2B (n = 3), and 3 (n = 2) met inclusion criteria.

RESULTS

PC C4d expression was diffuse in 23 (42%), focal in 9 (16%), and negative in 23 (42%) biopsies. AR episodes with focal and diffuse C4d expression had higher proportionate elevation of serum creatinine at biopsy and 4 weeks after diagnosis (P< or =0.05). Biopsies with diffuse PC C4d had interstitial hemorrhage (56.5%) and plasmacytic infiltrates (52%) more frequently than C4d- biopsies (22% and 16%), P = 0.02, but had no other distinctive histologic features. Graft loss was greater in diffuse (65%) compared with focal C4d+ (33%) and C4d- (33%) groups 1 year after diagnosis, P = 0.03. Other clinical and pathologic parameters did not differ significantly, including treatment received for AR.

CONCLUSION

Evidence of acute cellular with occult humoral rejection is identified in more than 40% of late AR episodes. Late acute humoral rejection may be associated with interstitial hemorrhage and plasma cells and contributes significantly to graft loss.

Everolimus (Certican) 12-Month Safety and Efficacy Versus Mycophenolate Mofetil in de Novo Renal Transplant Recipients

BACKGROUND

Everolimus is a proliferation inhibitor designed to target chronic rejection, including prevention of acute rejection. Everolimus blocks growth factor-mediated transduction signals, preventing organ rejection by a mechanism different than that of calcineurin inhibitors and of mycophenolate mofetil (MMF). METHODS.: Everolimus (1.5 mg or 3 mg daily) was compared with MMF (2 g daily) in a randomized, multicenter, multinational, 12-month double-blind, double-dummy and 2-year open-label, phase 3 trial in de novo renal allograft recipients (n = 588) who also received cyclosporine and corticosteroids as part of a triple immunosuppressive regimen.

RESULTS

At 12 months, there were no statistically significant differences between doses of 1.5 and 3 mg/day everolimus and MMF (2 g/day) in incidence of biopsy-proven acute rejection (23.2%, 19.7%, and 24.0%, respectively), graft loss (4.6%, 10.6%, and 9.2%), or death (5.2%, 4.0%, and 2.6%), respectively. Everolimus 1.5 mg/day and MMF were generally equally well tolerated. Both were better tolerated than everolimus 3 mg/day. The incidence of cytomegalovirus infection was significantly lower in patients receiving either 1.5 or 3 mg/day everolimus than in those receiving MMF (5.2% and 7.6% vs. 19.4%, respectively) (P = .001).

CONCLUSIONS

Everolimus is effective in preventing acute rejection and graft loss in de novo renal allograft recipients receiving a triple immunosuppressive regimen. Prevention of acute rejection, along with reduction in cytomegalovirus infection, addresses two factors known to contribute to chronic rejection in such patients.

Future immunosuppressive agents in solid-organ transplantation

OBJECTIVE

To review the pharmacology, pharmacokinetics, efficacy, and safety of mycophenolate sodium, everolimus, and FTY720.

STUDY SELECTION AND DATA EXTRACTION

Clinical trials and abstracts evaluating mycophenolate sodium, everolimus, and FTY720 in solid-organ transplantation were considered for evaluation. English-language studies and published abstracts were selected for inclusion.

DATA SYNTHESIS

Mycophenolate sodium has recently been approved by the Food and Drug Adminstration for marketing in the United States; everolimus and FTY720 are immunosuppressive agents that may soon be available in the United States. These agents have proven efficacy in reducing the incidence of acute rejection in solid-organ transplantation. Clinical trials have shown that these newer agents are relatively well tolerated. The most common adverse events associated with these agents were gastrointestinal and hematologic effects (mycophenolate sodium); hyperlipidemia, increased serum creatinine, and hematologic effects (everolimus): and gastrointestinal effects, headache, and bradycardia (FTY720).

CONCLUSION

Mycophenolate sodium has been approved in some European countries and the United States. Everolimus has been approved in some European countries and a new drug application has been submitted to the Food and Drug Administration. FTY720 is currently in phase III clinical trials and submission to the Food and Drug Administration for approval is a few years away. The approval of these agents will furnish the transplant practitioner with even more options for immunosuppression.

Steroid sparing with tacrolimus and mycophenolate mofetil in renal transplantation

Evidence suggests that steroid sparing in renal transplantation is associated with good outcomes, although there are limited data regarding steroid sparing in Tacrolimus and Mycophenolate Mofetil (MMF)-based regimes. In this study we describe the use of these agents in 101 consecutive patients undergoing renal transplantation using only a 7-day course of prednisolone. Median follow-up was 33 months (range 18-44). Patient and graft survival at 1 year were 100% and 98%, respectively. The acute rejection rate at both 6 and 12 months was 19%, with two episodes beyond 12 months. Anti-CD25 monoclonal antibody (anti-CD25 mAb) was administered to 25 patients at high immunological risk: a trend toward a lower rejection rate was seen in these patients compared with those at lower risk but not receiving induction therapy (8% vs. 22%; p = 0.11). Two patients experienced recurrent rejection. Of the twenty-three rejection episodes in total, 26% showed vascular involvement. Allograft function was preserved at 12 months with a mean creatinine of 144 micromol/L and mean estimated glomerular filtration rate (GFR) of 55 mL/min. At 12 months, the incidence of post-transplant diabetes mellitus was 3.5%. This steroid-sparing regime is associated with excellent patient and graft outcomes, and a low incidence of side effects.

Resource use and treatment costs after kidney transplantation: impact of demographic factors, comorbidities, and complications

BACKGROUND

Our goal was to quantify outcomes, resource use, and treatment costs for the first 2 years after renal transplantation in a "real-life" European setting and to assess the impact of preoperative risk factors and postoperative complications on treatment costs.

METHODS

Inpatient and outpatient records of all patients who received a renal transplant at Medizinische Hochschule Hannover, Germany, between January 1998 and July 2000, were evaluated. Key clinical events were recorded. Direct costs were calculated for primary hospitalization, the remainder of year 1, and year 2 after transplantation. Cost of organ procurement, pretransplant care, and transplant surgery were excluded. Cost consequences for key clinical events were determined.

RESULTS

Of 204 patients undergoing transplantation, 195 and 149 completed 1 year and 2 years of follow-up, respectively. The outcomes of years 1 and 2, respectively, were as follows: graft failure, 5.4%, 0.7%; acute rejection, 35.9%, 5.4%; cytomegalovirus (CMV) infection, 29.2%, 2.0%; and delayed graft function, 30.9%. Costs for primary hospitalization, the remainder of year 1, and year 2 averaged Euro 15,380, Euro 18,636, and Euro 14,484, respectively. Cost-driving events included graft failure Euro 36,228), acute rejection (Euro 9,638), delayed graft function (Euro7,359), and CMV infection (Euro 4,149). Graft failure and acute rejection for year 1 also added significantly to the costs for year 2.

CONCLUSIONS

These results show that posttransplant clinical outcomes result in a significant increase in treatment costs. Because the economic impact of primary causes of chronic rejection (acute rejection and CMV) and delayed graft function is substantial, careful selection of the most appropriate immunosuppressive regimen is essential.

Role of integrin CD103 in promoting destruction of renal allografts by CD8 T cells

Infiltration of CD8(+)TCRalphabeta(+) T-effector populations (CD8 effectors) into graft epithelial compartments has long been recognized as a key lesion in progression of clinical renal allograft rejection. While the afferent phase of allograft immunity is increasingly well-defined, the efferent pathways by which donor-reactive CD8-effector populations access and ultimately destroy the graft renal tubules (rejection per se) have received remarkably little attention. This is an important gap in our knowledge of transplantation immunology, because epithelial compartments comprise the functional elements of most commonly transplanted organs including not only kidney, but also liver, lung, pancreas, and intestine. Furthermore, there is increasing evidence that attack of graft epithelial elements by CD8-effector populations not only causes short-term graft dysfunction but is also a major contributor to development of chronic allograft nephropathy and late graft loss, which now represent the salient clinical problems. Recent studies of the T-cell integrin, alpha(E)beta(7) (CD103), have provided insight into the mechanisms that promote interaction of CD8 effectors with graft epithelial compartments. The purpose of this communication is to review the known properties of the CD103 molecule and its postulated role in the efferent phase of renal allograft rejection.

Meta-analysis of basiliximab for immunoprophylaxis in renal transplantation

BACKGROUND

Basiliximab is a high-affinity chimeric monoclonal antibody directed against the alpha-chain of the interleukin (IL)-2 receptor. Individual studies have shown that it is highly effective in preventing acute rejection and causes no measurable incremental toxicity. However, incorporation of basiliximab immunoprophylaxis into routine practice depends upon the demonstration of benefit across treatment regimens and quantitation of the treatment effect.

METHODS

This study employed a meta-analysis to examine the clinical benefit of basiliximab. Parameter estimates were derived from four randomised prospective double-blind studies conducted in 93 renal transplant centres in 18 countries. A total of 1185 adult primary allograft recipients were randomised within the centres to receive either basiliximab 20mg intravenously on days 0 and 4 or placebo, in addition to double or triple immunosuppression consisting of cyclosporin-microemulsion (Neoral((R))The use of tradenames is for product identification purposes only and does not imply endorsement.), corticosteroids, and azathioprine or mycophenolate mofetil. Key clinical events included patient and graft survival, graft rejection and complications. Analysis was performed using a variable model; odds ratios and the numbers needed to treat (NNT) to benefit or to harm one patient were calculated for each principal outcome at 6 or 12 months post-transplant.

RESULTS

Basiliximab reduced the relative risk (RR) and absolute risk (AR) of clinical and biopsy-proven acute graft rejection across all treatment regimens. The overall RR of clinical acute graft rejection was decreased by 35% in patients receiving basiliximab. AR was reduced by 15.6% (pooled incidence: 28.8% vs 44.4%, p < 0.0001), and the NNT for efficacy was six. The reduction in RR of biopsy-proven rejection was similar (32%) with an absolute risk reduction (ARR) of 11.7% (pooled incidence: 25.1% vs 36.8%, p < 0.0001) and NNT of nine over 6 months. There was a concomitant reduction in the risk of graft loss which did not reach statistical significance (p = 0.14). The RR of graft loss was reduced by 26% with an AR reduction of 2.3% (pooled incidence: 6.4% vs 8.7%) and an NNT of 42 over 6 months. The risk of death was unchanged.

CONCLUSIONS

Immunoprophylaxis with basiliximab produces a significant reduction in the RR and AR of clinical and biopsy-proven acute graft rejection with a trend towards a concomitant reduction in the risk of graft loss. The magnitude of protection provided by basiliximab, the fact that it is observed across treatment regimens and the safety of this therapy are arguments for its routine use in renal transplantation.

Prediction of renal allograft function with early Doppler ultrasonography

INTRODUCTION

Doppler ultrasonography (USG) is an useful, noninvasive diagnostic tool for the management and follow-up of the transplanted kidney. However, it is believed that the value of Doppler USG is limited to discrimination of acute rejection episodes. We tested whether early Doppler USG findings were predictive of 1-month and 1-year allograft functions in noncomplicated renal transplant recipients (RTRs).

PATIENTS AND METHODS

Resistive index (RI) and pulsatile index (PI) values obtained by doppler USG within the first week of transplantation were correlated with allograft function at 1 month and 1 year in 45 (10 women, 35 men, mean age: 27 years) noncomplicated cases. Patients with complications during the first posttransplant year were not included.

RESULTS

There was a negative correlation between both RI and PI with creatinine clearance values at 1 month and at 1 year posttransplant. There was a significant decline in allograft function among cases with either RI > or = 0.7 or PI > or = 1.1. Patients with impaired allograft function have higher RI and PI values.

CONCLUSION

Renal allograft survival is influenced by many factors. However, no reliable simple parameter has been identified to predict long-term outcome. Doppler USG performed during the early transplantation period with calculation of RI and PI may have a predictive value to forecast early and long-term outcomes of noncomplicated kidney transplants.

Sequential changes in plasma selenium concentration after cadaveric renal transplantation

Background

Previous investigations have shown that plasma selenium concentrations are significantly lower in patients with established chronic graft nephropathy (CGN) than in healthy transplant controls. The aims of this study were to determine when in the transplant process low selenium concentrations become apparent and to explore the relationship between selenium levels and risk factors for CGN.

Methods

Plasma selenium concentrations were measured in 40 patients (20 receiving cyclosporin, 20 receiving tacrolimus) undergoing transplantation. Samples were obtained immediately before transplantation and at 3, 6 and 12 months after transplantation.

Results

A low plasma selenium concentration was found in 30 patients at the time of transplantation but this had normalized in the majority of patients by 3 months. Plasma selenium concentrations at 3, 6 and 12 months were significantly higher than baseline values for both treatment arms, but were significantly lower at 3 months in patients who experienced either clinical acute rejection (CAR) or cytomegalovirus (CMV) infection during the preceding months.

Conclusion

Low plasma selenium concentrations are common at the time of transplantation but appear to normalize thereafter. The identification of low selenium levels in patients who experience CAR or CMV (two important risk factors for clinically apparent CGN) suggests that the relationship between selenium and CGN warrants further investigation.

An economic model of 2-hour post-dose ciclosporin monitoring in renal transplantation

BACKGROUND

Monitoring of microemulsion ciclosporin (cyclosporine; Neoral) by 2-hour post-dose drug concentrations (C2) is an accurate measure of ciclosporin absorption efficiency and exposure, and appears superior to trough (C0) monitoring for prediction of rejection risk. A predictive decision model was used to determine if this approach also reduces total treatment costs in the first 12 months after renal transplantation.

METHODS

Parameter estimates for key clinical events were derived from the literature and from prospective pharmacokinetic studies comprising 234 adult HLA-non-identical renal graft recipients at seven Canadian centres. Patients were treated with microemulsion ciclosporin (Neoral), corticosteroids and azathioprine or mycophenolate mofetil. Using the perspective of the Canadian healthcare provider, total treatment costs for the C2 versus the C0 strategy were modelled over 12 months, and then remodelled using conservative estimates to extend the timeframe to 5 years. Health resources were valued in 1999 Canadian dollars.

RESULTS

The incidence of acute rejection was estimated to be 25% at 1 year in patients monitored by C0 and 18% in those monitored by C2. Patient survival was considered to be independent of monitoring strategy, and graft loss was predicted to be 1.4% lower in the C2 group. The studies suggested no important differences in comorbidity and the costs of C0 and C2 monitoring and ambulatory-based adverse events were held equivalent. Using these inputs, the average cost per patient for the first year post-transplant was Can dollars 46,857 for C0 monitoring and Can dollars 45,306 for C2 monitoring, rising to Can dollars 146,879 and Can dollars 142,569 after 5 years. The predicted cost for initial hospitalisation was Can dollars 11,280 for C0 and Can dollars 10,806 for C2 monitoring. The cost of maintenance immunosuppressive drug use, graft loss and dialysis was Can dollars 19,098 in the C0 group and Can dollars 18,612 in the C2 group, while acute rejection treatment costs were Can dollars 2169 and Can dollars 1577, respectively. An additional Can dollars 14,310 was consumed by other events, including repeat hospitalisation, for each group. Sensitivity analysis indicated that the most influential parameters affecting savings due to C2 monitoring were a reduction in the duration of initial and follow-up hospitalisations and reduced risks of acute rejection and subsequent graft loss.

CONCLUSIONS

Compared with traditional trough concentration monitoring, ciclosporin monitoring at 2 hours post-dose produced a predicted saving of Can dollars 1551 during the first year after renal transplant. Although modelling assumptions become more restrictive over time, this projection allows a preliminary assessment of the long-term economic impact of the routine use of C2 monitoring.

Influence of hypercholesterolemia and acute graft rejection on chronic nephropathy development in renal transplant recipients

Graft endothelial lesions resulting from acute rejection may be sustained by concomitant hypercholesterolemia, thus increasing the risk of chronic graft failure. The present study was undertaken to examine the influence of hypercholesterolemia and acute graft rejection (AGR) episodes on graft function and graft loss due to chronic nephropathy. A cohort of 336 patients transplanted between 1993 and 2000 having graft function at 12 months after transplantation were examined. Immunosuppressive therapy consisted of CsA, azathioprine, and corticosteroids in 90% with 10% of patients receiving mycophenolate mofetil in place of azathioprine. During the first year after transplantation, AGR occurred in 134 (39.8%) and hypercholesterolemia (6.2 mmol/L) in 132 (39.2%) of patients. The population was divided into four groups according to AGR occurrence and cholesterol concentrations during the first year after transplantation for analysis of serum creatinine concentrations and graft loss at 5 years of follow-up. Patients with AGR irrespective of cholesterol levels displayed significantly higher creatinine concentrations. Graft loss in these patients increased over twofold compared to the remaining groups. Patients without hypercholesterolemia and AGR showed normal creatinine concentrations and low graft loss rates during 5 years of follow-up.

Resource utilization among kidney transplant recipients

BACKGROUND

Hospitalization consumes a significant portion of the end-stage renal disease (ESRD) program, which includes kidney transplant recipients. Identification of kidney transplant recipients at risk of increased resource utilization could lead to appropriate interventions to attenuate the complications related to kidney transplant, which may reduce resource utilization.

METHODS

This retrospective cohort study of kidney transplant recipients was performed to identify risk factors for hospital utilization. The study population consisted of patients who received kidney transplant at our center between October 1990 and September 1999 and were followed in the outpatient clinic.

RESULTS

Of the 220 patients, 171 (78%) were hospitalized during a median follow-up of 36 months. The number of hospitalizations, hospital days, and outpatient visits per patient-year at risk were 1.1, 6.3, and 21.6, respectively. Infection episodes were the leading cause of hospitalization. In a multivariate regression analysis, cytomegalovirus (CMV)-positive status of donor (RR 1.58; 95% CI 1.15, 2.18) and a higher number of hospital days during the transplant hospitalization (RR 1.10 per 7 days increase; 95% CI 1.03, 1.19) were associated with a higher risk of hospitalization, while higher serum albumin (RR 0.84 per 0.5 g/dL increase; 95% CI 0.73, 0.97), higher hematocrit (RR 0.95 per 1% increase; 95% CI 0.92, 0.98), higher glomerular filtration rate (GFR) (RR 0.91 per 10 mL/min/1.73 m2; 95% CI 0.85, 0.99), and an increased interval since transplant (RR 0.84 per 6 months increase; 95% CI 0.75, 0.93) were associated with a lower risk of hospitalization. CMV-positive status of the donor (RR 1.11; 95% CI 1.00, 1.21) and presence of cardiovascular disease (RR 1.12; 95% CI 1.00, 1.24) were associated with a higher risk of outpatient visits, while Caucasian race (RR 0.82; 95% CI 0.73, 0.94), higher serum albumin (RR 0.88 per 0.5 g/dL increase; 95% CI 0.84, 0.93), higher hematocrit (RR 0.96 per 1% increase; 95% CI 0.95, 0.97), and an increased interval since transplant (RR 0.79 per 6 months increase; 95% CI 0.76, 0.83) were associated with a lower risk of outpatient visits.

CONCLUSION

Identification of risk factors associated with increase resource utilization among kidney transplant recipients could aid in the development of targeted interventions to improve clinical and economic outcomes.

Molecular heterogeneity in acute renal allograft rejection identified by DNA microarray profiling

BACKGROUND

The causes and clinical course of acute rejection vary, and it is not possible to predict graft outcome reliably on the basis of available clinical, pathological, and genetic markers. We hypothesized that previously unrecognized molecular heterogeneity might underlie some of the variability in the clinical course of acute renal allograft rejection and in its response to treatment.

METHODS

We used DNA microarrays in a systematic study of gene-expression patterns in biopsy samples from normal and dysfunctional renal allografts. A combination of exploratory and supervised bioinformatic methods was used to analyze these profiles.

RESULTS

We found consistent differences among the gene-expression patterns associated with acute rejection, nephrotoxic effects of drugs, chronic allograft nephropathy, and normal kidneys. The gene-expression patterns associated with acute rejection suggested at least three possible distinct subtypes of acute rejection that, although indistinguishable by light microscopy, were marked by differences in immune activation and cellular proliferation. Since the gene-expression patterns pointed to substantial variation in the composition of immune infiltrates, we used immunohistochemical staining to define these subtypes further. This analysis revealed a striking association between dense CD20+ B-cell infiltrates and both clinical glucocorticoid resistance (P=0.01) and graft loss (P<0.001).

CONCLUSIONS

Systematic analysis of gene-expression patterns provides a window on the biology and pathogenesis of renal allograft rejection. Biopsy samples from patients with acute rejection that are indistinguishable on conventional histologic analysis reveal extensive differences in gene expression, which are associated with differences in immunologic and cellular features and clinical course. The presence of dense clusters of B cells in a biopsy sample was strongly associated with severe graft rejection, suggesting a pivotal role of infiltrating B cells in acute rejection.