Call for revolution: a new approach to describing allograft deterioration

Defining causes of death-censored kidney allograft failure: A 5-year multicentre ANZDATA and clinical cross-sectional study

AIM

Determining specific causes of allograft failure allows a focus on understanding and treating these conditions. Previous studies highlight chronic antibody-mediated rejection as a leading cause of late allograft failure. We sought to define causes of allograft failure in a large cohort of kidney transplant recipients across multiple centres in Australia and New Zealand, including cases previously attributed to chronic allograft nephropathy (CAN).

METHODS

All death-censored allograft failures at 9 participating centres between 1 January 2014 to 31 December 2018 were included. Available clinical and biopsy data were reviewed and the "most likely" cause assigned.

RESULTS

There were 642 death-censored allograft failures in the study period. Of these, 495 (77.1%) had an informative biopsy performed a median of 13.4 months (IQR 2.5-39.1 months) prior to allograft failure. Rejection of any type was the leading cause of allograft failure (47.5%), comprised chiefly of chronic antibody-mediated rejection (37.4%) and chronic T-cell mediated rejection (6.4%). Other leading causes were undifferentiated interstitial fibrosis and tubular atrophy (10.8%), late medical and surgical complications (8.1%) and recurrent or de novo glomerulonephritis (7.0%). Polyoma viral nephropathy and calcineurin inhibitor toxicity each contributed to <2%. Causes of allograft failure previously attributed to CAN (n = 419, 65.3%) had a similar distribution to the overall cohort, with 43.9% attributed to chronic antibody-mediated rejection.

CONCLUSION

To prolong allograft survival, improved strategies are needed to curtail alloimmune responses. Greater understanding of the causes of undifferentiated interstitial fibrosis and tubular atrophy and potential treatments would also be of considerable benefit.

The rejection that defies antirejection drugs-chronic vascular rejection (allograft vasculopathy): The role of terminology and linguistic relativity

While allograft loss due to acute rejection has been dramatically reduced due to the introduction of immunophilins, this therapy has little effect on allografts lost due to chronic vascular rejection. This situation may be due to a misnomer of the pathology. Specifically, its designation as 'chronic rejection' has given the wrong impression that the cause of the disease has been identified. Analyzing this phenomenon under the rubric of linguistic relativity suggests that the words chosen to name the disease may have restricted our cognitive ability to solve the problem. Thus, we have to step out of the 'alloimmunity/rejection box'. Let's pause between our words, Speak and fall silent again, So that the meaning of the word just spoken, Sounds a clearer echo in our heads. Let's pause between our words. Andrey Makarevich.

Correlation of Anti-HLA IgA Alloantibodies and Fc Receptor Motives with Kidney Allograft Survival

Immunoglobulin A (IgA) is the most abundant antibody isotype in humans and anti-HLA IgA was found in sera of transplant recipients. Focusing on patients awaiting kidney re-transplantation, we tested the impact of anti-HLA-class I/II IgA antibodies on graft survival. We analyzed 276 patients with and 238 without allograft failure. Eight motives of the Fcα receptor (FCAR) and Fcγ receptor were analyzed in patients with allograft failure. The distribution of anti-HLA IgA1/A2 and IgG antibodies differed significantly (p < 0.0001) between both patient groups, and IgA1 plus IgA2 antibodies were more abundant in patients with allograft failure. Allograft survival was significantly impaired if anti-HLA-class I plus II IgA was present, in the first 105 months (9 years) of follow-up (median of 43 vs. >105 months, p = 0.007). Patients with anti-HLA IgA and IgG vs. anti-HLA IgG only had a significantly shorter allograft survival within that follow-up period (88 vs. >105 months, p = 0.008). Moreover, allograft survival was shorter (p = 0.02) in carriers of GG vs. AA + AG genotypes of FCAR rs16986050. Thus, the presence of anti-HLA IgA plus IgG vs. IgG only was associated with shorter kidney allograft survival and FCAR motives may impact on graft survival.

The Biology and Molecular Basis of Organ Transplant Rejection

Allograft rejection is defined as tissue injury in a transplanted allogeneic organ produced by the effector mechanisms of the adaptive alloimmune response. Effector T lymphocytes and IgG alloantibodies cause two different types of rejection that can occur either individually or simultaneously: T cell-mediated rejection (TCMR) and antibody-mediated rejection (ABMR). In TCMR, cognate effector T cells infiltrate the graft and orchestrate an interstitial inflammatory response in the kidney interstitium in which effector T cells engage antigen-presenting myeloid cells, activating the T cells, antigen-presenting cells, and macrophages. The result is intense expression of IFNG and IFNG-induced molecules, expression of effector T cell molecules and macrophage molecules and checkpoints, and deterioration of parenchymal function. The diagnostic lesions of TCMR follow, i.e. interstitial inflammation, parenchymal deterioration, and intimal arteritis. In ABMR, HLA IgG alloantibodies produced by plasma cells bind to the donor antigens on graft microcirculation, leading to complement activation, margination, and activation of NK cells and neutrophils and monocytes, and endothelial injury, sometimes with intimal arteritis. TCMR becomes infrequent after 5-10 years post-transplant, probably reflecting adaptive mechanisms such as checkpoints, but ABMR can present even decades post-transplant. Some rejection is triggered by inadequate immunosuppression and non-adherence, challenging the clinician to target effective immunosuppression even decades post-transplant.

[Identifying the specific causes of kidney allograft loss: A population-based study]

INTRODUCTION

Results of kidney transplantation have been improving but long-term allograft survival remains disappointing. The objective of the present study was to identify the specific causes of renal allograft loss, to assess their incidence and long-term outcomes.

METHODS

A total of 4783 patients from four French centres, transplanted between January 2004 and January 2014 were prospectively included. A total of 9959 kidney biopsies (protocol and for cause) performed between January 2004 and March 2015 were included. Donor and recipient clinical and biological parameters as well as anti-HLA antibody directed against the donor were included. The main outcome was the long-term kidney allograft survival, including the study of the associated causes of graft loss, the delay of graft loss according to their causes and the determinants of graft loss.

RESULTS

There were 732 graft losses during the follow-up period (median time: 4.51 years) with an identified cause in 95.08 %. Kidney allograft survival at 9 years post-transplant was 78 %. The causes of allograft loss were: antibody-mediated rejection (31.69 %), thrombosis (25.55 %), medical intercurrent disease (14.62 %), recurrence of primary renal disease (7.1 %), BK- or CMV-associated nephropathy (n=35, 4.78 %), T cell-mediated rejection (4.78 %), urological disease (2.46 %) and calcineurin inhibitor nephrotoxicity (1.09 %).

CONCLUSION

The main causes of allograft loss were antibody-mediated rejection and thrombosis. These results encourage efforts to prevent and detect these complications earlier in order to improve allograft survival.

[The pathology of renal transplants]

In order to make an objective assessment of the histopathology of a renal biopsy during a kidney transplant, all the various elements involved in the process must be understood. It is important to know the characteristics of the donor organ, especially if the donor is older than 65. The histopathological features of the donor biopsy, especially its vascular status, are often related to an initial poor function of the transplanted kidney. The T lymphocyte inflammatory response is characteristic in acute cellular rejection; the degree of tubulitis, together with the amount of affected parenchyme, are important factors. The proportion of cellular sub-populations, such as plasma cells and macrophages, is also important, as they can be related to antibody-mediated humoral rejection. Immunofluorescent or immunohistochemical studies are necessary to rule out C4d deposits or immunogloblulins. The presence of abundant deposits of C4d in tubular basement membranes supports a diagnosis of humoral rejection, as does the presence of capillaritis, glomerulitis which, together with vasculitis, are typical diagnostic findings in C4d negative cases. Interstitial fibrosis, tubular atrophy and glomerular sclerosis, although non-specific, imply a chronic phase. Transplant glomerulopathy and multilamination in more than 6 layers of the tubular and glomerular basement membranes are quasi-specific characteristics of chronic humoral rejection. Electron microscopy is essential to identify of these pathologies as well as to demonstrate the presence of other glomerular renal diseases.

Pharmacologic Complement Inhibition in Clinical Transplantation

Purpose of Review

Over the past two decades, significant strides made in our understanding of the etiology of antibody-mediated rejection (AMR) in transplantation have put the complement system in the spotlight. Here, we review recent progress made in the field of pharmacologic complement inhibition in clinical transplantation and aim to understand the impact of this therapeutic approach on outcomes in transplant recipients.

Recent Findings

Encouraged by the success of agents targeting the complement cascade in disorders of unrestrained complement activation like paroxysmal nocturnal hemoglobinuria (PNH) and atypical hemolytic uremic syndrome (aHUS), investigators are testing the safety and efficacy of pharmacologic complement blockade in mitigating allograft injury in conditions ranging from AMR to recurrent post-transplant aHUS, C3 glomerulopathies and antiphospholipid anti-body syndrome (APS). A recent prospective study demonstrated the efficacy of terminal complement inhibition with eculizumab in the prevention of acute AMR in human leukocyte antigen (HLA)-incompatible living donor renal transplant recipients. C1 esterase inhibitor (C1-INH) was well tolerated in two recent studies in the treatment of AMR and was associated with improved renal allograft function.

Summary

Pharmacologic complement inhibition is emerging as valuable therapeutic tool, especially in the management of highly sensitized renal transplant recipients. Novel and promising agents that target various elements in the complement cascade are in development. Graphical Abstractᅟ.

Clinical Courses of Graft Failure Caused by Chronic Allograft Dysfunction in Kidney Transplantation

BACKGROUND

Chronic allograft dysfunction (CAD) is a main cause of graft failure in kidney transplantation.

METHODS

We retrospectively analyzed 279 kidney transplant recipients who survived with a functioning graft for at least 2 years. CAD was defined as chronic graft deterioration, excluding other specific causes. We defined the pattern of decline in estimated glomerular filtration rate (eGFR), as follows: (1) "plateau" was defined as decline in eGFR ≤2 mL/min/1.73 m²/year; "long plateaus" were those lasting more than 5 years; (2) "rapid decline" was a decrease in eGFR ≥20 mL/min/1.73 m²/year. Patients diagnosed with CAD were categorized according to the occurrence of rapid decline and/or long plateau as follows: group 1, neither rapid decline nor long plateau; group 2, rapid decline only; group 3, long plateau only; and group 4, both rapid decline and long plateau.

RESULTS

From a total of 81 graft losses, 51 (63%) failed because of CAD, with a median of 9.4 years. Sixteen patients belonged to group 1, 14 to group 2, 12 to group 3, and nine to group 4. Mean graft survival times in the four groups were 7.7 ± 1.1, 6.1 ± 3.1, 16.2 ± 2.5, and 10.8 ± 3.6 years, respectively (P < .001). There were significant differences among groups in donor age, year of transplantation, mean eGFR at baseline, and acute rejection rate after transplantation.

CONCLUSIONS

The results indicate that this cohort of kidney transplant recipients who had CAD comprised subgroups with different clinical courses.

Increased circulating follicular helper T cells with decreased programmed death-1 in chronic renal allograft rejection

BACKGROUND

Chronic antibody-mediated rejection is a major issue that affects long-term renal allograft survival. Since follicular helper T (Tfh) cells promote the development of antigen-specific B cells in alloimmune responses, we investigated the potential roles of Tfh cells, B cells and their alloimmune-regulating molecules in the pathogenesis of chronic renal allograft rejection in this study.

METHODS

The frequency of Tfh, B cells and the levels of their alloimmune-regulating molecules including chemokine receptor type 5 (CXCR5), inducible T cell co-stimulator (ICOS), programmed death-1 (PD-1), ICOSL, PDL-1 and interleukin-21 (IL-21), of peripheral blood were comparatively measured in 42 primary renal allograft recipients within 1-3 years after transplantation. Among them, 24 patients had definite chronic rejection, while other 18 patients had normal renal function.

RESULTS

Tfh-cell ratio was significantly increased with PD-1 down-regulation in the patients with chronic renal allograft rejection, while B cells and the alloimmune-regulating molecules studied did not show any appreciable change in parallel.

CONCLUSIONS

The patients with chronic renal allograft rejection have a characteristic increase in circulating Tfh cells with a decrease in PD-1 expression. These pathological changes may be a therapeutic target for the treatment of chronic renal allograft rejection and can be useful as a clinical index for monitoring conditions of renal transplant.

Autophagy and liver ischemia-reperfusion injury

Liver ischemia-reperfusion (I-R) injury occurs during liver resection, liver transplantation, and hemorrhagic shock. The main mode of liver cell death after warm and/or cold liver I-R is necrosis, but other modes of cell death, as apoptosis and autophagy, are also involved. Autophagy is an intracellular self-digesting pathway responsible for removal of long-lived proteins, damaged organelles, and malformed proteins during biosynthesis by lysosomes. Autophagy is found in normal and diseased liver. Although depending on the type of ischemia, warm and/or cold, the dynamic process of liver I-R results mainly in adenosine triphosphate depletion and in production of reactive oxygen species (ROS), leads to both, a local ischemic insult and an acute inflammatory-mediated reperfusion injury, and results finally in cell death. This process can induce liver dysfunction and can increase patient morbidity and mortality after liver surgery and hemorrhagic shock. Whether autophagy protects from or promotes liver injury following warm and/or cold I-R remains to be elucidated. The present review aims to summarize the current knowledge in liver I-R injury focusing on both the beneficial and the detrimental effects of liver autophagy following warm and/or cold liver I-R.

Acidosis and hyperkalemia caused by losartan and enalapril in pediatric kidney transplant recipients

OBJECTIVES

To evaluate the efficacy and safety of losartan and enalapril in pediatric kidney transplant recipients.

MATERIALS AND METHODS

A retrospective review was performed in 31 pediatric kidney transplant recipients who were treated with losartan (50 mg/d, oral) for 1 to 6 months because of mild hypertension and persistent proteinuria. All patients were treated concurrently with enalapril (5 or 10 mg daily, oral), and 12 patients (39%) also were treated with amlodipine (5 or 10 mg daily, oral). Demographic and clinical characteristics of the patients were reviewed.

RESULTS

Losartan use was associated with a significant decrease in mean systolic (before losartan was started, 123 ± 14 mm Hg; before losartan was stopped, 111 ± 10 mm Hg; P ≤ .001) and diastolic blood pressure (before losartan was started, 78 ± 11 mm Hg; before losartan was stopped, 69 ± 10 mm Hg; P ≤ .001) and urinary protein excretion (before losartan was started, 51 ± 45 mg/m2/h; before losartan was stopped, 28 ± 34 mg/m2/h; P ≤ .001). However, losartan therapy was associated with a significant mean increase in serum potassium level (before losartan was started, 4.0 ± 0.4 mmol/L; before losartan was stopped, 5.7 ± 0.5 mmol/L; P ≤ .001) and decrease in pH (before losartan was started, 7.35 ± 0.0; before losartan was stopped, 7.23 ± 0.0; P ≤ .001). Losartan was stopped because of hyperkalemia and acidosis earlier in patients who were on tacrolimus than cyclosporine immunosuppression (tacrolimus, 3 ± 1 mo; cyclosporine, 4.7 ± 0.8 mo; P ≤ .001).

CONCLUSIONS

Losartan and enalapril may be beneficial in pediatric kidney transplant recipients by decreasing blood pressure and proteinuria, with maintenance of stable graft function, but may be associated with serious adverse events including hyperkalemia and life-threatening acidosis.

Antibody-mediated rejection, T cell-mediated rejection, and the injury-repair response: new insights from the Genome Canada studies of kidney transplant biopsies

Prospective studies of unselected indication biopsies from kidney transplants, combining conventional assessment with molecular analysis, have created a new understanding of transplant disease states and their outcomes. A large-scale Genome Canada grant permitted us to use conventional and molecular phenotypes to create a new disease classification. T cell-mediated rejection (TCMR), characterized histologically or molecularly, has little effect on outcomes. Antibody-mediated rejection (ABMR) manifests as microcirculation lesions and transcript changes reflecting endothelial injury, interferon-γ effects, and natural killer cells. ABMR is frequently C4d negative and has been greatly underestimated by conventional criteria. Indeed, ABMR, triggered in some cases by non-adherence, is the major disease causing failure. Progressive dysfunction is usually attributable to specific diseases, and pure calcineurin inhibitor toxicity rarely explains failure. The importance of ABMR argues against immunosuppressive drug minimization and stands as a barrier to tolerance induction. Microarrays also defined the transcripts induced by acute kidney injury (AKI), which correlate with reduced function, whereas histologic changes of acute tubular injury do not. AKI transcripts are induced in kidneys with late dysfunction, and are better predictors of failure than fibrosis and inflammation. Thus progression reflects ongoing parenchymal injury, usually from identifiable diseases such as ABMR, not destructive fibrosis.

The safe introduction of angiotensin-converting enzyme inhibitor in renal allograft recipients

Antihypertensive and renoprotective treatment with angiotensin-converting enzyme inhibitor (ACEI) or angiotensin II receptor blocker is indicated in almost all chronic renal failure patients. However, this treatment is not widely used for renal allograft recipients mainly because of the potential side effects, including a decrease in renal function as well as onset of hyperkalemia or anemia. Herein we investigated the effects of ACEI introduction to hypertensive renal transplantation patients who did not display renal artery stenosis. At least 2 months after transplantation, we exchanged amlodipine (5 mg) for either ramipril or perindopril (5 mg) in 25 patients who were free of renal artery stenosis as determined indirectly by measuring the renal arterial resistance index with the noninvasive, inexpensive Doppler ultrasound method. The resistance index was evaluated again at 2 weeks. Systolic and diastolic blood pressure, serum creatinine, calculated creatinine clearance, serum potassium, hemoglobin and hematocrit were also measured before as well as at 2, 4, and 12 weeks after conversion to ACEI. The conversion did not change the mean renal arterial resistance index, nor did it influence renal function or blood count, and it was equally effective for controlling blood pressure. The serum potassium level increased at 2 and 4 weeks; however, it was within the normal range in all patients. Our data suggested that measurement of the renal arterial resistance index is a noninvasive, inexpensive, and reliable preselection method before introduction of ACEI in renal allograft recipients.

Understanding the causes of kidney transplant failure: the dominant role of antibody-mediated rejection and nonadherence

We prospectively studied kidney transplants that progressed to failure after a biopsy for clinical indications, aiming to assign a cause to every failure. We followed 315 allograft recipients who underwent indication biopsies at 6 days to 32 years posttransplant. Sixty kidneys progressed to failure in the follow-up period (median 31.4 months). Failure was rare after T-cell-mediated rejection and acute kidney injury and common after antibody-mediated rejection or glomerulonephritis. We developed rules for using biopsy diagnoses, HLA antibody and clinical data to explain each failure. Excluding four with missing information, 56 failures were attributed to four causes: rejection 36 (64%), glomerulonephritis 10 (18%), polyoma virus nephropathy 4 (7%) and intercurrent events 6 (11%). Every rejection loss had evidence of antibody-mediated rejection by the time of failure. Among rejection losses, 17 of 36 (47%) had been independently identified as nonadherent by attending clinicians. Nonadherence was more frequent in patients who progressed to failure (32%) versus those who survived (3%). Pure T-cell-mediated rejection, acute kidney injury, drug toxicity and unexplained progressive fibrosis were not causes of loss. This prospective cohort indicates that many actual failures after indication biopsies manifest phenotypic features of antibody-mediated or mixed rejection and also underscores the major role of nonadherence.

Skin and kidney histological changes in graft-versus-host disease (GVHD) after kidney transplantation

Kidney transplantation (Ktx) is generally performed during end stage renal disease due to a loss of the kidneys' ability to filter wastes from the circulatory system. Acute graft-versus-host disease (GVHD) after Ktx is a life-threatening complication that progresses to organ failure, systemic complications, and death. The current study evaluated the significance of histologic findings of GVHD as obtained from skin biopsies following Ktx in swine. A swine model of Ktx with tacrolimus-based immunosuppression was used to assess possible correlations between acute-graft-cellular rejection and skin histological findings for prediction of GVHD. Animals were divided into a Ktx treatment group or a control group with no Ktx and skin and kidney biopsies were histologically assessed at postoperative days 0, 15, 30, 45 and 60. Skin samples were analyzed and classified from grade 1 to 4 of skin GVHD and the major histopathological changes of kidney acute cellular rejection were described using Banff's score system. We observed a significant linear correlation between the histological grading values of skin biopsy changes and the histological grading values of kidney biopsies (Kendall's tau_b=0.993) in the Ktx experimental group. No histological changes were observed in controls. Our findings demonstrate the diagnostic value of staging skin GVHD after Ktx and suggest it's future utility for monitoring long term Ktx-induced changes.

Immune monitoring and biomarkers to predict chronic allograft dysfunction

Late failure of a kidney transplant continues to be a major problem after transplantation, in spite of more potent immunosuppressive strategies and the focus of clinical management shifting toward prolonging long-term graft survival. It is now recognized that graft failure occurs because of two major complications: death with a functioning graft and intrinsic allograft failure. Recent studies of late kidney graft loss have indicated a complexity of findings, including etiologies that are both immune and non-immune. These studies suggest that late graft failure is not an inevitable fact and that further investigation into the etiology of transplant graft failure may lead to a new understanding of the biology that will provide novel therapeutic strategies and biomarkers. In this review, we will focus on late allograft failure due to intrinsic injury to the transplant. The role of immune monitoring will be discussed in the context of monitoring for ongoing injury or for identifying late injury. A variety of methodologies have been used, including genomics, proteomics, and metabolomics, not only for monitoring allograft injury but also for identifying markers of graft failure that are more sensitive than serum creatinine. The available studies, as they relate to late or chronic graft injury, will also be reviewed.

Chemokines and their receptors in human renal allotransplantation

BACKGROUND

Chemokines and their receptors play a critical role in leukocyte trafficking, and inhibition of select chemokines has been shown to attenuate kidney disease and allograft rejection in animal models. Therefore, we evaluated chemokine and chemokine receptor transcripts in human renal allograft biopsies, correlating transcript levels with clinical course and immunohistochemical analysis to relate chemokine expression to relevant clinical human disease phenotypes.

METHODS

Renal biopsies were grouped as postreperfusion (n=10), stable function (n=10), subclinical (n=10) or acute rejection (n=17), or calcineurin inhibitor nephrotoxicity (n=9) based on clinical presentation and histopathologic assessment. Using quantitative real-time polymerase chain reaction analysis, chemokine transcripts were assessed relative to transcript levels in preprocurement biopsies from live donor kidneys (n=15).

RESULTS

Transcripts from several inflammatory chemokines (CCL3, CCL5, CXCL9, CXCL10, and CXCL11) and chemokine receptors (CCR5, CCR7, and CXCR3) were significantly increased in allografts with subclinical and clinical acute rejection, indicating a strong polarization toward a T-helper 1 effector phenotype during rejection. These transcripts also distinguished acutely rejecting allografts from allografts with nonrejection causes of renal dysfunction. Biopsies from patients with stable function without histologic evidence of rejection had increased chemokine transcript levels that were qualitatively similar but quantitatively reduced compared with rejecting allografts.

CONCLUSIONS

This comprehensive evaluation of chemokines and their receptors in human renal transplantation defines associations between chemokine expression and clinical phenotypes, may have diagnostic utility, and highlights relevant pathways for therapeutic intervention.

Contribution of Toll-like receptor activation to lung damage after donor brain death

INTRODUCTION

Donor brain death is the first injurious event that can produce inflammatory dysfunction after pulmonary transplantation. This study was designed to determine whether stimulation of the toll-like receptor (TLR) system contributes to the changes produced by brain death.

MATERIALS AND METHODS

Rats were repeatedly treated with specific agonists for TLR4 or TLR2/6 to desensitize these receptors. Brain death was then induced by inflation of a balloon catheter within the extradural space. Mean arterial pressure changes and inflammatory markers were measured serially by protein and mRNA analysis.

RESULTS

Both desensitizing pretreatments prevented the neurogenic hypotension (P<0.001) and metabolic acidosis (P<0.001) observed in control animals after brain death. These treatments also reduced the levels of tumor necrosis factor-α and CXCL1 in serum and bronchoalveolar lavage fluid, although desensitization of TLR4 produced a greater inhibition than desensitization of TLR2. Desensitization of TLR4 also reduced (P<0.05) expression of the adhesive integrin CD11b on blood neutrophils after brain death. Examination of mRNA levels in lung tissue 5 hr after brain death showed that desensitization of TLR4 limited the expression of interferon (IFN)-γ, IFNβ, and CXCL10, whereas desensitization of TLR2/6 reduced only the expression of IFNγ.

CONCLUSION

These results indicate that activation of TLR signaling pathways can contribute to the lung damage produced by brain death; this may increase subsequent graft injury after transplantation.

An integrated view of molecular changes, histopathology and outcomes in kidney transplants

Data-driven approaches to deteriorating kidney transplants, incorporating histologic, molecular and HLA antibody findings, have created a new understanding of transplant pathology and why transplants fail. Transplant dysfunction is best understood in terms of three elements: diseases, the active injury-repair response and the cumulative burden of injury. Progression to failure is mainly attributable to antibody-mediated rejection, nonadherence and glomerular disease. Antibody-mediated rejection usually develops late due to de novo HLA antibodies, particularly anti-class II, and is often C4d negative. Pure treated T cell-mediated rejection does not predispose to graft loss because it responds well, even with endothelialitis, but it may indicate nonadherence. The cumulative burden of injury results in atrophy-fibrosis (nephron loss), arterial fibrous intimal thickening and arteriolar hyalinosis, but these are not progressive without ongoing disease/injury, and do not explain progression. Calcineurin inhibitor toxicity has been overestimated because burden-of-injury lesions invite this default diagnosis when diseases such as antibody-mediated rejection are missed. Disease/injury triggers a stereotyped active injury-repair response, including de-differentiation, cell cycling and apoptosis. The active injury-repair response is the strongest correlate of organ function and future progression to failure, but should always prompt a search for the initiating injury or disease.

Maintenance of donor-specific chimerism despite osteopontin-associated bone fibrosis in a vascularized bone marrow transplantation model

BACKGROUND

The role of vascularized bone allografting is not established in plastic and reconstructive surgery. The authors evaluated the contribution by osteopontin to fibrosis of allografted bone in a vascularized bone marrow transplantation model across a major histocompatibility complex barrier.

METHODS

Thirty-six transplantations were performed between Brown Norway (RT1 n) donors and Lewis (RT1 l) recipients divided into three groups: group 1, isografts between Lewis rats (n = 12); group 2, allografts without treatment (n = 8); and group 3, allografts under a 7-day alphabeta-T-cell receptor/cyclosporine protocol (n = 16). Flow cytometry assessed the presence of chimerism for donor major histocompatibility complex class I (RT1 n) antigens. Immunostaining was used to determine osteopontin expression in grafted and recipient bone, and histologic examination was used to assess bone architecture.

RESULTS

Early engraftment of donor bone marrow cells (RT1 n) into the recipient bone marrow compartment was achieved at posttransplantation day 7. This corresponded with osteopontin expression restricted to the endosteum of trabecular bone and was associated with the preservation of hematopoietic cells within donor bone. Cell migration between donor and recipient bone marrow compartments was confirmed by the presence of recipient cells (RT1 l) within the allografted bone and donor-origin cells (RT1 n) within the recipient bone. At posttransplantation day 63, osteopontin expression within allografted bone was associated with allograft bone fibrosis and lack of hematopoietic properties. In contrast, the recipient's contralateral bone demonstrated a highly localized osteopontin expression pattern within the endosteum and active hematopoiesis with the presence of donor-specific (RT1 n) cells and correlated with chimerism maintenance.

CONCLUSIONS

These results confirm that despite up-regulation of osteopontin expression and fibrosis of allografted bone, vascularized bone marrow transplantation resulted in efficient engraftment of donor cells into the recipient's bone marrow compartment, leading to chimerism maintenance.

Identifying specific causes of kidney allograft loss

The causes of kidney allograft loss remain unclear. Herein we investigated these causes in 1317 conventional kidney recipients. The cause of graft loss was determined by reviewing clinical and histologic information the latter available in 98% of cases. During 50.3 +/- 32.6 months of follow-up, 330 grafts were lost (25.0%), 138 (10.4%) due to death with function, 39 (2.9%) due to primary nonfunction and 153 (11.6%) due to graft failure censored for death. The latter group was subdivided by cause into: glomerular diseases (n = 56, 36.6%); fibrosis/atrophy (n = 47, 30.7%); medical/surgical conditions (n = 25, 16.3%); acute rejection (n = 18, 11.8%); and unclassifiable (n = 7, 4.6%). Glomerular pathologies leading to failure included recurrent disease (n = 23), transplant glomerulopathy (n = 23) and presumed nonrecurrent disease (n = 10). In cases with fibrosis/atrophy a specific cause(s) was identified in 81% and it was rarely attributable to calcineurin inhibitor (CNI) toxicity alone (n = 1, 0.7%). Contrary to current concepts, most cases of kidney graft loss have an identifiable cause that is not idiopathic fibrosis/atrophy or CNI toxicity. Glomerular pathologies cause the largest proportion of graft loss and alloinmunity remains the most common mechanism leading to failure. This study identifies targets for investigation and intervention that may result in improved kidney transplantation outcomes.

Randomized trial of single-dose versus divided-dose rabbit anti-thymocyte globulin induction in renal transplantation: an interim report

BACKGROUND

The optimal dosing protocol for rabbit anti-thymocyte globulin (rATG) induction in renal transplantation has not been determined, but evidence exists that rATG infusion before renal allograft reperfusion improves early graft function. Infusing a large rATG dose over a short interval has not previously been evaluated for its effect on renal function and allograft nephropathy in a prospective, randomized comparison against conventional rATG induction.

METHODS

Between April 20, 2004 and December 26, 2007 we enrolled renal transplant patients into a prospective, randomized, nonblinded trial of two rATG dosing protocols (single dose, 6 mg/kg vs. divided doses, 1.5 mg/kg every other day x 4; target enrollment=160) followed after 6 months by calcineurin-inhibitor withdrawal. Primary endpoints are renal function by calculated glomerular filtration rate (GFR) and chronic allograft nephropathy at protocol biopsy. We now present the early GFR data of all 160 patients and safety and efficacy data of the first 142 patients with 6 months follow up and before calcineurin inhibitor withdrawal (average follow up=23.3+/-11.6 months).

RESULTS

There were no differences between groups in rATG-related adverse events, patient and graft survival, acute rejection, or chronic allograft nephropathy rate at 6 months. Calculated DeltaGFR (POD 1-4) was significantly better in the single-dose group (P=0.02), with a trend toward improved renal function from months 2 to 6 in recipients of deceased donor kidneys (P=0.08).

CONCLUSIONS

This study demonstrates that administering 6 mg/kg of rATG over 24 hr is safe and is associated with improved early renal function compared with administering rATG in alternate-day doses.

Hematopoietic stem cell engraftment and seeding permits multi-lymphoid chimerism in vascularized bone marrow transplants

Vascularized bone marrow transplantation (VBMT) across a MHC barrier under a 7-day alphabeta-TCR mAb and CsA protocol facilitated multiple hematolymphoid chimerism via trafficking of the immature (CD90) bone marrow cells (BMC) between donor and recipient compartments. Early engraftment of donor BMC [BN(RT1(n))] into the recipient BM compartment [LEW(RT1(l))] was achieved at 1 week posttransplant and this was associated with active hematopoiesis within allografted bone and correlated with high chimerism in the hematolymphoid organs. Two-way trafficking between donor and recipient BM compartments was confirmed by the presence of recipient MHC class I cells (RT1(l)) within the allografted bone up to 3 weeks posttransplant. At 10 weeks posttransplant, decline of BMC viability in allografted bone corresponded with bone fibrosis and lack of hematopoiesis. In contrast, active hematopoiesis was present in the recipient bone as evidenced by the presence of donor-specific immature (CD90/RT1(n)) cells, which correlated with chimerism maintenance. Clonogenic activity of donor-origin cells (RT1(n)) engrafted into the host BM compartment was confirmed by colony-forming units (CFU) assay. These results confirm that hematolymphoid chimerism is developed early post-VBMT by T-cell lineage and despite allografted bone fibrosis chimerism maintenance is supported by B-cell linage and active hematopoiesis of donor-origin cells in the host BM compartment.

Renin angiotensin system blockade in kidney transplantation: a systematic review of the evidence

ACE-inhibitors and angiotensin receptor blockers (ARB) slow the progression of renal disease in non-transplant patients. A systematic review of randomized trials (n = 21 trials with 1549 patients) was conducted to determine the effect of ACE-inhibitor or ARB use following kidney transplantation. With a median follow-up of 27 months, ACE-inhibitor or ARB use was associated with a significant decrease in glomerular filtration rate (-5.8 mL/min; 95% CI -10.6 to -0.99). ACE-inhibitor or ARB use resulted in a lower hematocrit (-3.5%; 95% CI -6.1 to -0.95), reduction in proteinuria (-0.47 gm/d; 95% CI -0.86 to -0.08) but no change in the serum potassium (0.18 mmol/L; 95% CI -0.03 to 0.40). ACE-inhibitor or ARB use results in clinically important reductions in proteinuria, hematocrit and glomerular filtration rate in renal transplant recipients, but there are insufficient data to determine the effect on patient or graft survival. Randomized trials of sufficient power and duration that examine these hard outcomes should be conducted. Until such trials are completed, this study provides quantitative estimates of the risks and benefits of ACE-inhibitor or ARB use that can be used by clinicians considering prescribing these medications to kidney transplant recipients or to researchers designing future trials.

CMV increases tubular apoptosis through the TNF-alpha-TNF-R1 pathway in a rat model of chronic renal allograft rejection

INTRODUCTION

Destruction of transplanted kidneys through chronic allograft nephropathy [CAN], also known as chronic rejection, is the greatest obstacle in successful kidney transplantation. Causes behind CAN are many, from pre-transplant causes to infections. Viral infections, especially CMV, are a risk factor for chronic rejection. We have previously developed a rat kidney transplant model, in which CMV enhances the development of chronic rejection under triple drug treatment. In this model we have now further studied the routes of apoptosis in virus induced early CAN vs. the routes of apoptosis in a later developing non-infectious CAN.

MATERIALS AND METHODS

Renal transplantations were performed in a strain combination of DA/BN under immunosuppression. One group of animals was infected with RCMV and the other was left uninfected. The grafts were harvested on days 3-40 after transplantation. Apoptotic cells were visualised by in situ terminal transferase mediated dUTP nick end labelling [TUNEL] from paraffin embedded, formalin fixed kidney grafts. Cytokines were labelled imunohistochemically from frozen sections, among them tumour necrosis factor alpha [TNF-alpha] and its receptor-protein 1 [TNF-R1] as well as CD 95 [FAS], caspase 3 and CD14. The results were semi-quantitatively scored from 0 to 3+ over various tissues structures separately.

RESULTS

In the CMV infected grafts, we could demonstrate a more intense TUNEL reaction in tubular epithelium [2.0+/-1.0 vs. 0.8+/-0.5 at day 14, P<0.05] as well as an earlier increase in the expression TNF-alpha in the vascular endothelium [2.0+1.0 vs. 0.0+0.0 at days 3-5, P<0.05] than in the non-infected group. There was also an earlier increase in the tubular TNF-R1 expression [2.2+0.8 vs. 1.0+0.0 at days 5-7, P<0.05]. There was no difference in the expression of CD14, caspase 3 or FAS between the groups.

CONCLUSIONS

CMV enhanced development of CAN was associated with tubular apoptosis and concomitant increase of TNF-alpha-TNF-R1, rather than the FAS-FAS-ligand activation.

Intrarenal Cytokine and Chemokine Gene Expression and Kidney Graft Outcome

AIMS

Proinflammatory cytokines are thought to play an important role in various kidney graft diseases resulting in interstitial fibrosis and tubular atrophy frequently found in case biopsies. To explore the role of various cytokines and chemokines in the long-term graft outcome, the transcription patterns of their genes in kidney allograft biopsies were evaluated.

METHODS

The real-time RT-PCR was used to identify intragraft mRNA expression of cytokines and chemokines in 74 kidney graft recipients and the results were correlated with histological and clinical parameters and long-term graft outcome.

RESULTS

We observed up-regulated IL-10 (p < 0.001), TGF-beta1, IL-6, MCP-1, RANTES (p < 0.01) and TNF-alpha (p < 0.05) mRNA expression in patients with chronic allograft nephropathy (CAN) as compared to controls. There were positive correlations between the mRNA expression of IL-6 (p < 0.001), IL-10 (p < 0.01), TNF-alpha, MCP-1 (p < 0.05) and the proteinuria. The up-regulation of intrarenal MCP-1 in patients with CAN increased the risk for the graft failure within the next 42 months (OR 5.1, p < 0.05). Kaplan-Meier survival analysis revealed that proteinuria and higher intragraft expression of TGF-beta1 and MCP-1 predict a poor kidney graft outcome.

CONCLUSION

Expression patterns of intrarenal proinflammatory genes might discriminate patients at a higher risk for the earlier allograft failure.

Four-year follow-up of a prospective trial of HLA and MICA antibodies on kidney graft survival

In 2002, 1329 patients with functioning transplants were prospectively tested for HLA antibodies in the 13th International Histocompatibility Workshop. Four years after testing, deceased donor graft survival among 806 patients not having antibodies in 2002 was 81% compared to 58% for 158 patients with HLA antibodies (p < 0.0001) and 72% for 69 patients with MICA antibodies (p = 0.02). Hazard ratio (HR) using death-censored graft survival from multivariate analysis of HLA antibodies was 3.3 (p < 0.00001) and 2.04 for MICA (p = 0.01). In the 14th Workshop, at 1 year follow-up, survival for 1319 patients receiving deceased donor grafts and no HLA antibodies was 96% compared to 94% for 344 patients with HLA antibodies (p = 0.0004) and 83% survival for 33 patients with MICA (p = 0.0005). HR from multivariate analysis: HLA antibodies was 3.6 (p < 0.00001) and 6.1 for MICA (p = 0.006). Twelve patients with donor specific antibodies tested by single antigen beads had a 1 year survival of 64% (p = 0.008), and 27 patients with non-donor specific 'strong' antibodies had a 66% survival (p = 0.0003) compared to 92% survival in those with no antibodies. In conclusion, these two prospective trials, after 1 and 4 years, provided strong evidence that HLA and MICA antibodies are associated with graft failure.

Conversion from calcineurin inhibitors to sirolimus for chronic renal allograft dysfunction: a systematic review of the evidence

BACKGROUND

Conversion from a calcineurin inhibitor to sirolimus has been used as a strategy to improve deteriorating renal allograft function but the efficacy and safety of this intervention is unknown.

METHODS

We performed a systematic review of studies that involved conversion from a calcineurin inhibitor to sirolimus in kidney transplantation. The search yielded five randomized trials (n=1,040 patients) and 25 nonrandomized studies (n=977 patients).

RESULTS

In the randomized trials, conversion to sirolimus improved short-term creatinine clearance (weighted mean difference 6.4 mL/min; 95% CI 1.9 to 11.0) compared to controls. In the nonrandomized studies, renal function improved or stabilized in 66% (95% CI 61% to 72%), creatinine clearance improved (weighted mean change 5.7 mL/min; 95% CI 1.4 to 10.1), cholesterol increased (weighted mean change 20.8 mg/dL; 95% CI 11.2 to 30.4) and triglycerides increased (weighted mean change 40.1 mg/dL; 95% CI 18.6 to 61.7). Sirolimus was discontinued by 28% of patients (95% CI 0 to 59%) in the randomized trials and 17% (95% CI 12 to 22%) in the nonrandomized trials.

CONCLUSION

Conversion to sirolimus is associated with an improvement in short-term renal function. However, given the discontinuation rate and potential side effects, adequately powered randomized trials with longer follow-up of hard outcomes are needed to determine whether this strategy leads to a lasting benefit in the clinical care of transplant recipients.

Expression of TGFbeta-1 and Type I TGFbeta-receptor on sequential biopsies of renal transplants with chronic allograft nephropathy

The aim of this study was to determine the expression of transforming growth factor-beta (TGFbeta)-1 and type I TGFbeta-receptor on sequential biopsies from renal transplants with and without chronic allograft nephropathy. Twenty-four renal transplant recipients entered the study. They underwent sequential biopsies performed before (T1: 1.44 +/- 1.2 months) and 6 months after (T2: 15.96 +/- 7.2 months) transplantation. Lesions were graded according to the criteria of the Banff classification. C4d was detected by fluorescence microscopy. Immunohistochemistry was performed in order to identify cells expressing TGFbeta-1 and type I TGFbeta-receptor. In normal renal tissue (n = 4), TGFbeta-1 is expressed by tubular epithelial cells and endothelial cells lining glomerular and peritubular capillaries, whereas type 1 TGFbeta-receptor is expressed by tubular epithelial cells and smooth muscle cells in the media of arteries. In recipients with chronic allograft nephropathy (group 1, n = 14), diffuse epithelial expression of both molecules was found in more patients at T2 than at T1 (42.8% vs 21.4%). In contrast, this pattern of expression remained stable or decreased over time in recipients with long-term normal transplants (group 2, n = 10). Furthermore, type 1 TGFbeta-receptor was detected on the smooth muscle cells of arteries in 12/14 (85.7%) of recipients in group 1 and only in 4/9 (44.4%) of recipients in group 2. No relationship was noticed with regard to C4d deposits. These data suggest that the synthesis of TGFbeta-1 and type I TGFbeta-receptor increases over time in recipients developing chronic allograft nephropathy. Further studies are in progress in order to quantify mRNA of both molecules with real-time polymerase chain reaction.

B cells: a rational target in alloantibody-mediated solid organ transplantation rejection

Loss of allografts over time remains a barrier to achieving successful outcomes in solid organ transplantation. Although the role of donor-specific alloantibody-mediated mechanisms in hyperacute rejection is well known, research and management of early and late post-transplant rejection have traditionally focused on T cell-mediated mechanisms. However, available agents that affect T-cell pathways have minimal impact on long-term graft survival, suggesting that other effector mechanisms are involved. A growing body of evidence now supports a role for alloantibody-mediated mechanisms in early and late graft rejection, which can significantly impact on long-term graft survival. The important role of B cells in generating and perpetuating alloantibody production provides a rationale for B-cell depletion therapy as an approach to prevent or reduce alloantibody formation before transplantation and to treat or prevent early and late alloantibody-mediated rejection. The use of monoclonal antibodies that directly target B cells, in combination with standard alloantibody-depleting therapies and/or immunosuppression, has been investigated in several small non-controlled studies. Promising results suggest that this strategy warrants further investigation in larger controlled studies.

Mechanisms of Disease: alloimmunization in renal diseases

Graft rejection has long been considered the paradigm of renal diseases induced by alloimmunization, particularly alloimmunization directed against HLA antigens. Accumulating evidence indicates that non-HLA immunity also has an important role in clinical transplantation. Targets of alloimmunization include antigens of tubular basement membrane, tubular epithelial cells and endothelial cells. They can be polymorphic allovariants (as shown in the rat) or 'hidden' antigens exposed when the graft is damaged. Alloimmunization can also occur when a person genetically deficient in a renal protein (e.g. the alpha5 (IV) collagen chain in X-linked Alport's syndrome or nephrin in Finnish-type nephrotic syndrome) is transplanted to treat end-stage renal failure. The non-mutated protein in the donor kidney is recognized as a foreign antigen, and the resulting alloimmune response can damage the graft. We have demonstrated that alloimmunity can also affect the native kidney. We have characterized a novel fetomaternal disease in which a genetic defect in the MME gene encoding neutral endopeptidase (NEP) in the mother leads to the development of membranous nephropathy in her fetus (maternal anti-NEP antibodies bind to NEP on fetal podocytes). Our findings raise the possibility that mutations or genetic polyporphisms in MME or other genes expressed by the podocyte are involved in alloimmune-mediated development of membranous nephropathy after kidney or bone marrow transplantation.

Mechanisms of chronic allograft dysfunction

This review was designed to highlight new findings that have contributed to our knowledge of the pathogenesis of late graft dysfunction. Both immune and nonimmune causes contribute to its development. Specific contributors to late graft dysfunction have been recently recognized and are potential targets for new treatment options. The variables associated with late graft failure include donor age and tissue quality, brain death and other issues specific to the deceased donor, tissue injury secondary to organ preservation, alloimmune-mediated injury, and posttransplantation factors in the recipient, such as viral infections, hypertension, drug toxicity, and hyperlipidemia. One of the critical variables that is controllable is the total ischemic time; the longer the ischemic episode, the worse the long-term results of the transplant are. Another significant obstacle to long-term allograft survival is the MHC barrier. The roles of B cells and alloantibody as effectors of alloimmunity have been underestimated; emerging studies strongly suggest that previous sensitization and/or de novo donor-anti-human lymphocyte antigen (HLA) antibodies secondary to poor HLA matching portend a poor prognosis for allograft survival, even in the presence of chronic T-cell-specific immunosuppression.

Chronologically different impacts of immunologic and non-immunologic risk factors on renal allograft function

INTRODUCTION

Upon analysis of the risk factors affecting renal graft survival and function, the time-dependent effects of each risk factor should be differentiated from their net effects. To evaluate the chronologically different impacts of risk factors on graft renal function, we reviewed 390 recipients who received a kidney from 1-haplotype-matched living-related donors.

MATERIALS AND METHODS

Until 5-yr post-transplantation (TX), yearly serum creatinine (Scr), 24-h urinary excretion of protein, and their yearly changes were compared by the episodes of acute rejection within 1 yr, the kidney weight to recipient body weight (KW/BW) ratio, the donor/recipient (D/R) age ratio, and the D/R gender pairing. The Kaplan-Meier method, Cox proportional hazard model, ANOVA, and repeated measures ANOVA were each applied for different purposes.

RESULTS

Only the episodes of acute rejection were a significant risk factor affecting graft survival. The episodes of acute rejection, KW/BW ratio, D/R age ratio, and D/R gender pairing consistently and independently had significant influences on Scr. Recipients having the lowest KW/BW ratio (first quartile) or the highest D/R age ratio (fourth quartile) had rapid increments of Scr after 4-yr post-TX. After 3-yr post-TX, there were significant correlations between the number of non-immunologic risk factors present and the yearly changes in Scr.

CONCLUSIONS

Non-immunologic factors had a detrimental effect on renal graft function, especially after 3-yr post-TX. If immunologic risks seem to be similar, size matching, age, and gender pairing should be considered for better long-term graft function in renal TX recipients.

Study of mRNA growth factors in urinary cells of kidney transplant recipients as predictors of chronic allograft nephropathy

BACKGROUND

Chronic allograft nephropathy (CAN) is responsible for a significant proportion of graft loss. Current diagnostic methods for CAN are inadequate, and noninvasive assays for detecting allograft dysfunction/rejection and predicting long-term outcomes are a priority in transplantation.

METHODS

Urine samples were collected from 48 kidney transplant recipients (KTR): 18 recipients with stable graft function (creatinine levels<2.0 mg/dL) and proteinuria of less than 500 mg/24 hr (Group 1); 18 recipients with stable graft function and proteinuria of greater than 500 mg/24 hr (Group 2); and 12 recipients with biopsy confirmed CAN. Urinary cell levels of transforming growth factor-beta1 (TGF-beta1) mRNA or epidermal growth factor (EGF) mRNA were measured using real-time quantitative PCR assay, and levels were correlated with renal allograft status. The integrity of RNA isolated from urine sediments was also assessed using the Agilent 2100 Bioanalyzer.

RESULTS

Urinary cell TGF-beta1 mRNA levels were higher in the CAN group compared to Group 1 (P<0.0001) or Group 2 (P<0.0001). Urinary cell EGF mRNA levels were higher in Group 1 compared to Group 2 (P<0.0001) or the CAN group (P<0.0001). There were no significant differences in the urinary cell levels of EGF mRNA between patients with greater than 500 mg/24 hr proteinuria (Group 2) and the CAN group (P=0.75).

CONCLUSION

These results demonstrate that urinary cell TGF-beta1 mRNA levels distinguish CAN patients from long-term transplant patients with stable renal function and varied levels of proteinuria. Urinary cells may be a good resource for the noninvasive diagnosis of CAN.

Long-term trends in allograft survival

Kidney transplantation has changed dramatically over the past decade. Many advances have occurred that result in shorter hospital stays, decreased acute rejection, less infectious morbidity, and improved long-term allograft survival. Many factors are responsible for the improvement in kidney transplantation, and these factors are discussed in this review. These successes have led to a paradox in the care of the kidney-transplant recipient, however. As the short-term complications are prevented or successfully managed, more patients will develop chronic problems with the function of the allograft.

Impact of HLA Antibodies on Transplant Glomerulopathy

The influence of humoral rejection on the development of chronic allograft nephropathy (CAN) is controversial, especially in relation to transplant glomerulopathy. The aim of our study was to analyse the influence of anti-HLA antibodies on the development of transplant glomerulopathy (cg0, cg1, cg2, and cg3; Banff'97). We selected all renal transplants patients from 1975 to 2003 who had a functioning graft for at least 6 months and a clinically indicated graft biopsy with CAN and chronic glomerular changes (case group). We studied the presence of anti-HLA antibodies (Ab) in the last serum taken while the graft was functioning and divided them into three groups according to the severity of glomerular lesions. We also selected 52 contemporary and comparable cases without transplant glomerulopathy (control group). A total of 77 case had transplant glomerulopathy: 39 cg1, 29 cg2, and 9 cg3. Pretransplant Ab titers and number of previous blood transfusions were higher among the subgroup with the most severe glomerulopathy. Patients who developed posttransplant anti-HLA Ab more frequently showed transplant glomerulopathy. Serum creatinine and proteinuria were higher among cases with chronic glomerulopathy, and more grafts were lost in that group. Thus, the presence of HLA-Ab is a key factor in the development of transplant glomerulopathy and chronic allograft rejection.

Three-year efficacy and safety results from a study of everolimus versus mycophenolate mofetil in de novo renal transplant patients

Everolimus 1.5 or 3 mg/day was compared with mycophenolate mofetil (MMF) 2 g/day in a randomized, multicenter 36-month trial in de novo renal allograft recipients (n = 588) receiving cyclosporine microemulsion (CsA) and corticosteroids. The study was double-blind until all patients had completed 12 months, then open-label. By 36 months, graft loss occurred in 7.2, 16.7 and 10.7% of patients in the everolimus 1.5, 3 mg/day, and MMF groups, respectively (p = 0.0048 for everolimus 1.5 mg/day vs. 3 mg/day); efficacy failure (biopsy-proven acute rejection (BPAR), graft loss, death or lost to follow-up) occurred in 33.0, 38.9 and 37.2% of patients (p = 0.455 overall), respectively. Mortality and incidence of BPAR were comparable in all groups. Creatinine values were higher in everolimus groups, requiring a protocol amendment that recommended lower CsA exposure. Diarrhea, lymphocele, peripheral edema and hyperlipidemia were more common among everolimus-treated patients, whereas viral infections, particularly cytomegalovirus infection, increased in the MMF group. Overall safety and tolerability were better with MMF and everolimus 1.5 mg/day than with everolimus 3 mg/day. In conclusion, at 36 months, an immunosuppressive regimen containing everolimus 1.5 mg/day had equivalent patient, and graft survival and rejection rates compared with MMF in de novo renal transplant recipients, whereas everolimus 3 mg/day had inferior graft survival. Renal dysfunction in everolimus cohorts necessitates close monitoring.

2005 immunosuppressive strategies in kidney transplantation: which role for the calcineurin inhibitors?

The calcineurin inhibitors (CNIs) cyclosporine and tacrolimus have been the cornerstones of immunosuppressive strategies in clinical transplantation. Currently, regimens that are most widely used for induction and maintenance therapy include CNIs. However, many clinical trials aiming at reducing or eliminating CNIs have been performed in recent years. Here, we review and discuss current and future immunosuppressive strategies with a special emphasis on the role of CNIs, in the light of recent studies in the field of kidney transplantation. In the current era, CNIs still play an important role.

Low-dose carbon monoxide inhalation prevents development of chronic allograft nephropathy

Chronic allograft nephropathy (CAN) is the primary cause for late kidney allograft loss. Carbon monoxide (CO), a product of heme metabolism by heme oxygenases, is known to impart protection against various stresses. We hypothesized that CO could minimize the chronic fibroinflammatory process and protect kidney allografts from CAN. Lewis kidney grafts were orthotopically transplanted into binephrectomized Brown-Norway rats under short-course tacrolimus. Recipients were maintained in room air or exposed to CO at 20 parts/million for 30 days after transplant. Efficacy of inhaled CO was studied at day 30 and day 80. Isografts maintained normal kidney function throughout the experiment with creatinine clearance of approximately 1.5 ml/min. Renal allograft function in air controls progressively deteriorated, and creatinine clearance declined to 0.2 +/- 0.1 ml/min by day 80 with substantial proteinuria. CO-treated animals had significantly better creatinine clearance (1.3 +/- 0.2 ml/min) with minimal proteinuria. Histological examination revealed the development of progressive CAN in air-exposed grafts, whereas CO-treated grafts had minimal tubular atrophy and interstitial fibrosis, with negligible collagen IV deposition. In vitro analyses revealed that CO-treated recipients had significantly less T cell proliferation against donor peptides via the indirect allorecognition pathway and less anti-donor IgG antibodies compared with air controls. Intragraft mRNA levels for chemokines (regulated on activation normal T cell expressed and secreted, macrophage inflammatory protein-1alpha, chemokine receptors (CCR1, CXCR3, CXCR5), IL-2, and intercellular adhesion molecule-1 were significantly decreased in CO-treated than in air-treated allografts. Furthermore, reduction of blood flow in air-treated allografts was prevented with CO. In conclusion, inhaled CO at a low concentration efficiently abrogates chronic fibroinflammatory changes associated with CAN and improves long-term renal allograft function.

Chronic renal allograft rejection: Pathophysiologic considerations

Chronic rejection is currently the most prevalent cause of renal transplant failure. Clinically, chronic rejection presents by chronic transplant dysfunction, characterized by a slow loss of function, often in combination with proteinuria and hypertension. The histopathology is not specific in most cases but transplant glomerulopathy and multilayering of the peritubular capillaries are highly characteristic. Several risk factors have been identified such as young recipient age, black race, presensitization, histoincompatability, and acute rejection episodes, especially vascular rejection episodes and rejections that occur late after transplantation. Chronic rejection develops in grafts that undergo intermittent or persistent damage from cellular and humoral responses resulting from indirect recognition of alloantigens. Progression factors such as advanced donor age, renal dysfunction, hypertension, proteinuria, hyperlipidemia, and smoking accelerate deterioration of renal function. At the tissue level, senescence conditioned by ischemia/reperfusion (I/R) may contribute to the development of chronic allograft nephropathy (CAN). The most effective option to prevent renal failure from chronic rejection is to avoid graft injury from both immune and nonimmune mechanism together with nonnephrotoxic maintenance immunosuppression.