Histological alterations in implant and one-year protocol biopsy specimens of renal allografts

Calcineurin inhibitors: a double-edged sword

Recently, research has directed its interests into identifying molecular pathways implicated in calcineurin inhibitor (CNI)-induced renal fibrosis. An emerging body of studies investigating calcineurin (CnA) activity has identified distinct actions of two main ubiquitously expressed isoforms: CnAα and CnAβ. CNIs have the capacity to inhibit both of these CnA isoforms. In the kidney, CnAα is required for development, whereas CnAβ predominantly modulates the immune response and glomerular hypertrophic signaling powered by activation of the transcription factor, nuclear factor of activated T lymphocytes (NFAT). Interestingly, data have shown that loss of CnAα activity contributes to the expression of profibrotic proteins in the kidney. Although this finding is of great significance, follow-up studies are needed to identify how loss of the CnAα isoform causes progressive renal damage. In addition, it is also necessary to identify downstream mediators of CnAα signaling that assist in upregulation of these profibrotic proteins. The goal of this review is to provide insight into strides taken to close the gap in elucidating CnA isoform-specific mechanisms of CNI-induced renal fibrosis. It is with hope that these contributions will lead to the development of newer generation CNIs that effectively blunt the immune response while circumventing extensive renal damage noted with long-term CNI use.

Strategies for an Expanded Use of Kidneys From Elderly Donors

The old-for-old allocation policy used for kidney transplantation (KT) has confirmed the survival benefit compared to remaining listed on dialysis. Shortage of standard donors has stimulated the development of strategies aimed to expand acceptance criteria, particularly of kidneys from elderly donors. We have systematically reviewed the literature on those different strategies. In addition to the review of outcomes of expanded criteria donor or advanced age kidneys, we assessed the value of the Kidney Donor Profile Index policy, preimplantation biopsy, dual KT, machine perfusion and special immunosuppressive protocols. Survival and functional outcomes achieved with expanded criteria donor, high Kidney Donor Profile Index or advanced age kidneys are poorer than those with standard ones. Outcomes using advanced age brain-dead or cardiac-dead donor kidneys are similar. Preimplantation biopsies and related scores have been useful to predict function, but their applicability to transplant or refuse a kidney graft has probably been overestimated. Machine perfusion techniques have decreased delayed graft function and could improve graft survival. Investing 2 kidneys in 1 recipient does not make sense when a single KT would be enough, particularly in elderly recipients. Tailored immunosuppression when transplanting an old kidney may be useful, but no formal trials are available.Old donors constitute an enormous source of useful kidneys, but their retrieval in many countries is infrequent. The assumption of limited but precious functional expectancy for an old kidney and substantial reduction of discard rates should be generalized to mitigate these limitations.

Immunosuppressive regimen and interstitial fibrosis and tubules atrophy at 12 months postrenal transplant

BACKGROUND AND OBJECTIVES

Chronic renal transplant dysfunction is histopathologically characterized by interstitial fibrosis and tubular atrophy. This study investigated the relative contribution of baseline donor, recipient, and transplant characteristics to interstitial fibrosis and tubular atrophy score at month 12 after renal transplantation.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This retrospective study includes all 109 consecutive recipients with adequate implantation and month 12 biopsies transplanted between April of 2003 and February of 2007. Immunosuppression regimen was tacrolimus and steroids (10 days) plus either sirolimus or mycophenolate mofetil.

RESULTS

Average interstitial fibrosis and tubular atrophy score increased from 0.70 to 1.65 (P<0.001). In an adjusted multiple linear regression analysis, interstitial fibrosis and tubular atrophy score at month 12 was significantly related to donor type (donors after cardiac death versus living donor had interstitial fibrosis and tubular atrophy score+0.41, 95% confidence interval=0.05-0.76, P=0.02), baseline interstitial fibrosis and tubular atrophy, and immunosuppression regimen. Because of interaction between the latter two variables (P=0.002), results are given separately: recipients with a baseline interstitial fibrosis and tubular atrophy score of zero had a 0.60 higher score at month 12 (95% confidence interval=0.09-1.10, P=0.02) when mycophenolate mofetil-treated, whereas recipients with a baseline interstitial fibrosis and tubular atrophy score more than zero had a 0.38 higher score at month 12 (95% confidence interval=0.01-0.74, P=0.04) when sirolimus-treated. A higher score at month 12 correlated with a lower estimated GFR (ρ=-0.45, P<0.001).

CONCLUSIONS

These findings suggest that histologic assessment of a preimplantation biopsy may guide choice of immunosuppresion to maximize transplant survival and its interaction with type of immunosuppression.

Surveillance protocol kidney transplant biopsies: their evolving role in clinical practice

Protocol renal allograft biopsies at fixed time points from transplantation have aided research and provided insights into the pathogenesis of early and late allograft injury. Their role is evolving from research to a clinical management tool needed to detect subclinical pathology requiring treatment adjustment. They frequently reveal unexpected findings and influence therapy in the majority of patients. Detection of subclinical rejection (SCR) remains important despite declining prevalence with triple therapy, the evidence favors treatment, if found. Surveillance biopsies in steroid avoidance and calcineurin inhibitor (CNI) withdrawal programs provide an important safety net against the increased rates of late acute and SCR. Individualization of therapy in high-risk patients and safe reduction of immunosuppression in standard risk individuals becomes possible. Other potentially reversible chronic pathologies that may be detected, include chronic T-cell or antibody-mediated rejection, recurrent disease, BK virus-associated nephropathy, interstitial fibrosis and tubular atrophy and CNI nephrotoxicity, allowing modifications of therapy to limit ongoing graft injury. Biopsy is safe and inexpensive compared with costs of earlier graft failure and return to dialysis. This review summarizes current evidence on use of surveillance histology for the clinical practice of renal transplantation.

Posttransplant inflammation associated with onset of chronic kidney disease

BACKGROUND

Chronic allograft nephropathy (CAN), a major complication in renal transplant patients, is an important cause of graft loss. Inflammation as measured in the pretransplant and posttransplant phases, using various markers, has been associated with worse renal function and a greater risk of cardiovascular disease and of long-term graft loss.

OBJECTIVE

The objective of our study was to evaluate whether worsening inflammation in the first 3 months postoperatively was a risk factor for developing CAN.

PATIENTS AND METHODS

We performed a cross-sectional study in 207 patients. The following markers of inflammation (MIF) were determined pretransplant and at 3 months after grafting: C-reactive protein (CRP) (mg/L), interleukin (IL)-6 (pg/mL), IL-10 (pg/mL), tumor necrosis factor (TNF)-α (pg/mL), and its soluble receptor (ng/mL), soluble-IL2R (UI/mL), pregnancy-associated plasma protein A (PAPP-A; mUI/L), and IL-4 (pg/mL). We also calculated the ratio at 3 months versus the pre value of MIF.

RESULTS

CAN was diagnosed after the first year in 23 patients (11.3%) always by renal biopsy performed for clinical indications. Patients with CAN showed worse inflammation, eg, MIF ratios over one, with statistically significant differences for the ratios of TNF-α and PAPP-A (P=.032 and P=.051 respectively). Upon multivariate logistic regression analysis, using CAN as the dependent variable and age, sex, donor age, months on dialysis, acute tubular necrosis, acute rejection, and MIF ratios as covariates, we observed that an acute rejection episode (OR=13.03; CI=2.8-60.9; P=.001), CRP ratio (OR=1.36; CI=1.07-1.73; P=.013), and PAPP-A ratio (OR=1.80; CI=0.92-3.53; P=.005) were independent markers of CAN.

CONCLUSIONS

Among other factors, inflammation may determine the onset of CAN as diagnosed by renal biopsy.

Histopathologic clusters differentiate subgroups within the nonspecific diagnoses of CAN or CR: preliminary data from the DeKAF study

The nonspecific diagnoses 'chronic rejection''CAN', or 'IF/TA' suggest neither identifiable pathophysiologic mechanisms nor possible treatments. As a first step to developing a more useful taxonomy for causes of new-onset late kidney allograft dysfunction, we used cluster analysis of individual Banff score components to define subgroups. In this multicenter study, eligibility included being transplanted prior to October 1, 2005, having a 'baseline' serum creatinine < or =2.0 mg/dL before January 1, 2006, and subsequently developing deterioration of graft function leading to a biopsy. Mean time from transplant to biopsy was 7.5 +/- 6.1 years. Of the 265 biopsies (all with blinded central pathology interpretation), 240 grouped into six large (n > 13) clusters. There were no major differences between clusters in recipient demographics. The actuarial postbiopsy graft survival varied by cluster (p = 0.002). CAN and CNI toxicity were common diagnoses in each cluster (and did not differentiate clusters). Similarly, C4d and presence of donor specific antibody were frequently observed across clusters. We conclude that for recipients with new-onset late graft dysfunction, cluster analysis of Banff scores distinguishes meaningful subgroups with differing outcomes.

A systematic review of kidney transplantation from expanded criteria donors

BACKGROUND

During the past few years, there has been renewed interest in the use of expanded criteria donors (ECD) for kidney transplantation to increase the numbers of deceased donor kidneys available. More kidney transplants would result in shorter waiting times and limit the morbidity and mortality associated with long-term dialysis therapy.

STUDY DESIGN

Systematic review of the literature.

SETTING & POPULATION

Kidney transplantation population.

SELECTION CRITERIA FOR STUDIES

Studies were identified by using a comprehensive search through MEDLINE and EMBASE databases. Inclusion criteria were case series, cohort studies, and randomized controlled trials assessing kidney transplantation in adult recipients using ECDs.

PREDICTOR

A special focus was given to studies comparing the evolution of kidney transplantation between standard criteria donors (defined as a donor who does not meet criteria for donation after cardiac death or ECD) and ECDs (defined as any brain-dead donor aged > 60 years or a donor aged > 50 years with 2 of the following conditions: history of hypertension, terminal serum creatinine level >or= 1.5 mg/dL, or death resulting from a cerebrovascular accident).

OUTCOMES

Criteria used to define and select ECDs, practice patterns, long-term outcomes, early complications, and some patient issues, such as selection criteria and immunosuppressive management.

RESULTS

ECD kidneys have worse long-term survival than standard criteria donor kidneys. The optimal ECD kidney for donation depends on adequate glomerular filtration rate and acceptable donor kidney histological characteristics, albeit the usefulness of biopsy is debated.

LIMITATIONS

This review is based mainly on data from observational studies, and varying amounts of bias could be present. We did not attempt to quantitatively analyze the effect of ECD kidneys on kidney transplantation because of the huge heterogeneity found in study designs and definitions of ECD.

CONCLUSIONS

Based on the available evidence, we conclude that patients younger than 40 years or scheduled for kidney retransplantation should not receive an ECD kidney. Patients 40 years or older, especially with diabetic nephropathy or nondiabetic disease, but a long expected waiting time for kidney transplantation, show better survival receiving an ECD kidney than remaining on dialysis therapy.

Chronic allograft nephropathy: what have we learned from protocol biopsies?

Chronic allograft nephropathy, characterized by interstitial fibrosis and tubular atrophy, is still a major cause of graft loss after kidney transplantation. The complex pathophysiology of chronic allograft nephropathy is still poorly understood, and could be clarified by a more systematic performance of implantation and protocol biopsies of the renal allograft. This review highlights the contribution of implantation and protocol biopsies to our current knowledge of the complex interaction of multiple processes, ultimately leading to the development of interstitial fibrosis and tubular atrophy in the transplanted kidney. In addition, the safety and the limitations of protocol biopsies are discussed, as well as potential future directions for clinical practice and clinical research.

An image analysis-based method for quantification of chronic allograft damage index parameters

Chronic allograft damage index (CADI) is a semi-quantitative histopathological score that predicts renal graft outcome. We aimed to develop an objective image analysis-based method for quantification of CADI parameters. Thirty-five kidney transplant biopsies were visually analyzed according to the original CADI criteria, and divided into normal, mildly, moderately and severely altered groups. Digital images of the same samples were then analyzed with IPLab software. Areas of inflammation and fibrosis measured using image analysis increased simultaneously with corresponding visual scores, although the difference between non-inflamed and mildly inflamed groups was not statistically significant. Area of normal tubuli decreased in the images of samples with visually mild/moderate tubular atrophy and tended to be even smaller in the group with severe tubular atrophy. Image analysis-based glomerular sclerosis score increased concurrently with increasing visual score. Mesangial matrix increase score in image analysis was greater in the samples with visually mild/moderate mesangial matrix increase score compared to those with normal glomeruli, and it was highest in the group with severe mesangial matrix increase. An image analysis-based CADI scoring of renal allograft biopsies could provide more precise data for scientific studies, and help pathologists in renal allograft biopsy scoring.

Better renal function with enhanced immunosuppression and protocol biopsies after kidney transplantation in children

Subclinical rejection may be associated with decreased graft function after renal transplantation (Tx). Detection by protocol biopsies and treatment could thus be important for the long-term prognosis. We have earlier discovered that glomerular filtration rate (GFR) declined in young children during the first 18 months. Consequently, we slightly enhanced and individualized each patient's immunosuppression. This was a retrospective study of 59 pediatric renal Tx patients between 1995 and 2001. The 35 historical controls received triple-therapy of azathioprine, methylprednisolone and cyclosporine. GFR was measured by protocol at discharge, 6 and 18 months, and a core biopsy was obtained at 18 months. The 24 study patients in addition received basiliximab, had GFR measured at 3 and 12 months, and a biopsy taken at 3 months. Based on histology and function, immunosuppression was individually adjusted. The groups were compared for GFR and histology at 18 months after Tx. There were less acute rejection episodes in the study group (0.38 vs. 1.23 per patient) and serum creatinine concentrations were lower. Subclinical rejection was detected and treated in 39% at 3 months. There were more chronic changes in the control (47%) than in the study group (29%) at 18 months. GFR was significantly higher in the study group at 18 months (87 vs. 68 mL/min/1.73 m(2)), most remarkably in patients < or =2 yr of age (99 vs. 68 mL/min/1.73 m(2)). Detection of subclinical rejection and slightly enhanced and individualized immunosuppression improved GFR 18 months after renal Tx, especially in the youngest patients.

The effect of different immunosuppressive regimens on TGF-beta1 expression in kidney transplant patients

Transforming growth factor (TGF)-beta1 is a key profibrogenic cytokine associated with the pathogenesis of chronic allograft nephropathy (CAN). The primary aim of this study was to evaluate TGF-beta1 expression in protocol kidney graft biopsy in patients treated with different immunosuppressive regimens. Protocol kidney graft biopsies were carried out in 77 patients with stable graft function at 1 year after kidney transplantation, treated with a triple-drug regimen based on cyclosporin A (CyA; n = 49) or tacrolimus (TAC; n = 28). Morphological findings were assessed using the Banff 97 classification. TGF-beta1 expression was analysed using immunochemistry, and semiquantitatively scored in different renal structures (total score 0-18). Clinical data were analysed at the time of biopsy, and 12 months thereafter. No significant relation was found between the used immunosuppressive regimen and the histomorphological picture in the graft. TGF-beta1 expression within graft tissue was significantly higher in patients treated with CyA when compared with TAC (9.94 +/- 4.2 vs. 5.0 +/- 3.2; P < 0.001). Serum creatinine and glomerular filtration rate (GFR; Cockroft-Gault calculation) were comparable in both groups but, in the course of the next 12 months, GFR significantly decreased only in the CyA-treated group (from 1.03 +/- 0.33 to 0.96 +/- 0.37 ml/s) while not changing in the TAC-treated group. Patients treated with TAC had significantly lower diastolic blood pressure and serum cholesterol. The significantly lower TGF-beta1 expression in 1-year protocol kidney graft biopsy in TAC-treated patients with stable renal function, and the different development of graft function in both groups suggest a possible benefit of TAC for long-term graft acceptance.

Randomized prospective trial of early steroid withdrawal compared with low-dose steroids in renal transplant recipients using serial protocol biopsies to assess efficacy and safety

BACKGROUND

Corticosteroid therapy after renal transplantation is associated with many adverse effects. Newer immunosuppressive agents may allow for safe and effective reductions in dose or early steroid withdrawal.

METHODS

In this prospective, single-center clinical trial, 60 patients were randomized into 2 groups: control patients (n = 28), who received low doses of prednisone throughout, and study patients (n = 32), who were withdrawn from steroids 7 days posttransplant. Patients received a limited course of rabbit antilymphocyte globulin (rALG) induction therapy, tacrolimus (TAC), and mycophenolate mofetil (MMF). Patients were followed for clinical outcomes and renal function. Protocol biopsies were performed at 1, 6, and 12 months.

RESULTS

Clinical rejections occurred in 11% of controls and 13% of study patients. Renal function was well maintained and equivalent in both groups. In all, 111 protocol biopsies were performed without complications. Subclinical rejection was noted in only 2 protocol biopsies, and borderline changes were seen in 12 biopsies, all of which were distributed equally between both groups. Unsuspected acute TAC toxicity was seen in 8 biopsies. Protocol biopsies led to changes in therapy in 10% of patients. In both groups, serial protocol biopsies demonstrated increased allograft fibrosis over time, which was significant at 1 year in the steroid withdrawal group.

CONCLUSION

The immunosuppressive combination of rALG, TAC, and MMF prevents subclinical rejection and the need for high doses of steroids after transplantation. However, continual low-dose steroid therapy may aid in preventing chronic allograft fibrosis. Protocol biopsies help define the short-term and long-term risks of steroid withdrawal therapy.

Baseline Glomerular Sclerosis Influences Morphological Changes, But Not Level of Serum Creatinine

The aim of this study was to investigate whether glomerular sclerosis (GS) at the time of engraftment affects subsequent morphology and clinical course of renal allografts. Eighty-one renal transplant recipients were recruited for this study. Protocol biopsies of the renal allografts were performed at engraftment, as well as at 1, 3, 5, and 7 years after transplantation. All cases were divided into 2 groups based on the presence of GS at engraftment, namely, non-GS and GS groups. Morphological changes in the renal allografts were graded from 0 to 3+ based on the severity of chronic allograft nephropathy (CAN) of the Banff classification based on 5 factors: percentage of GS, extent of interstitial fibrosis, tubular atrophy, arterial intimal thickening, and arteriolar hyalinosis. Furthermore, the level of serum creatinine (s-Cr) at each year was examined by recipient age and gender, donor age and gender, type of donor (living/cadaver), delayed graft function, acute rejection within 1 year after transplantation, mean blood pressure, and use of calcineurin inhibitors as well as the presence of GS at engraftment. The extent of GS at engraftment significantly correlated with donor age (P = .0038) but with a weak correlation coefficient. Although the severity of CAN developed gradually in both non-GS and GS groups, differences in morphological changes at engraftment between the 2 groups persisted throughout 7 years. Donor age and recipient gender influenced s-Cr significantly. In conclusion, the presence of GS at engraftment aggravates subsequent morphological changes and affects short-term but not long-term allograft prognosis.

Predictors of renal allograft histologic damage progression

The objective of this study was to analyze factors that are involved in the progression of renal allograft damage in the first 6 mo after transplantation. Donor and 6-mo protocol biopsies of 83 patients who received a renal transplant were classified using the Chronic Allograft Damage Index (CADI). Histologic changes were compared and correlated to clinical parameters at transplantation, at 6 mo, and annually over 2 yr. All CADI components increased significantly in the 6-mo posttransplantation period, except chronic vascular changes and the percentage of glomerulosclerosis. Total cholesterol and LDL- cholesterol at the time of biopsy correlated positively with mesangial matrix increase, and HDL cholesterol correlated negatively with vascular intima increase. High BP at biopsy was associated with tubular atrophy. Diastolic BP at biopsy correlated with 6-mo CADI (CADI-6). Patients with diastolic BP > or =85 mmHg at biopsy had a higher difference between CADI score in protocol biopsies and CADI score in donor biopsies (DeltaCADI) and higher creatinine at 1 and 2 yr. CADI in donor biopsies (CADI-0) >1 was more frequently found in older (odds ratio [OR], 1.07; 95% confidence interval [CI], 1.01 to 1.14) and nontraumatic dead donors (OR, 3.89; 95% CI, 1.13 to 13.33). CADI-6 >3 was more frequently found in those with CADI-0 >1 (OR, 3.82; 95% CI, 1.19 to 12.21), older donors (OR, 1.05; 95% CI, 1.01 to 1.10), and number of AB mismatches (OR, 2.36; 95% CI, 1.09 to 5.10). CADI-0, CADI-6, and DeltaCADI correlated significantly with serum creatinine at hospital discharge, at 6 mo, and at 2 yr. DeltaCADI was affected by initial percentage of glomerulosclerosis (OR, 1.10; 95% CI, 1.02 to 1.19) and creatinine at hospital discharge (OR, 1.01; 95% CI, 1.00 to 1.02). Donor-related as well as nonimmunologic factors, such as hypertension and dyslipidemia, are associated with increased risk for renal allograft damage progression.

Protocol biopsies after kidney transplantation

Numerous studies have investigated features of allograft injury in renal biopsies obtained in stable kidney transplants. Evaluation of protocol biopsies has revealed a considerably high prevalence of subclinical acute rejection (SAR) and chronic allograft nephropathy (CAN) already in early phases after transplantation. The meanwhile well-established association of SAR and CAN in protocol biopsy with long-term allograft failure and the finding of superior allograft outcome after treatment of SAR in a randomized prospective study may point to clinical relevance of this procedure. In this review, potential benefits and risks associated with kidney allograft biopsy in stable renal transplant recipients are discussed.

Clinicopathological study of vesicoureteral reflux (VUR)-associated pyelonephritis in renal transplantation

We retrospectively studied the occurrence of vesicoureteral reflux (VUR)-associated pyelonephritis using renal biopsies obtained from the transplanted kidneys, and correlated the histological changes with clinical parameters. Out of a total of 131 renal biopsies performed between 1990 and 2001 on renal transplant patients at the department of Urology of Nagasaki University Graduate School of Biomedical Sciences, 12 patients showed pyuria more than twice in a single year. Seven of these 12 patients were available for determining VUR by voiding cystourethrography (VCUG). Cystoureterography demonstrated VUR in three of seven studied patients with pyuria. A histopathological examination revealed dilatation of both proximal and distal tubules in renal biopsies of transplant patients with VUR, compared to renal biopsies of transplant patients without VUR, or non-transplanted patients with thin membrane disease. One of the patients with VUR showed advanced features of chronic pyelonephritis in four consecutive biopsies at different time points, suggesting a late stage of reflux nephropathy in the transplanted kidney. We conclude from our study that the occurrence of VUR-related pyelonephritis may be one of the important long-term complications in the survival of renal allografts.

Clinicopathological evaluation of renal allografts of four patients by 20-year protocol biopsies

Twenty-year protocol biopsies were performed in four cases of renal transplant recipients with grafts that had survived 20 years or more. All four recipients received transplants from their parents, and never had episodes of acute rejection. They were maintained with the conventional immunosuppressive protocol including azathioprine, mizoribine, and prednisolone. Three of them had past history of malignant diseases such as breast cancer and tongue cancer. In spite of fair graft function, the microscopic findings of 20-year protocol biopsy showed various degrees of histological damage; e.g. obsolescence of the glomeruli, glomerulosclerosis, arteriole wall thickening, interstitial fibrosis and tubular atrophy. Although two of the four grafts were functioning with low serum creatinine levels (1.3-1.4 mg dL-1) at 24 years and 26 years following transplantation, respectively, the function of the other two grafts had decreased more than 20 years after transplantation. In the two grafts with decreased function, glomerulosclerosis and arteriole wall thickening tended to be more severe (Banff classification of chronic allograft nephropathy [CAN] grade II and III) at the 20-year protocol biopsy compared with the two well-functioning grafts (CAN grade I and II). We conclude that the protocol biopsies even at 20 years can contribute to predict the fate of renal allografts.

Computer-assisted quantification of fibrosis in chronic allograft nephropaty by picosirius red-staining: a new tool for predicting long-term graft function

BACKGROUND

Chronic allograft nephropathy (CAN) has become the predominant limiting factor for long-term transplant survival. A cardinal histomorphologic correlate for CAN is interstitial fibrosis. Currently, no method has been established in routine use that reliably quantifies the extent of interstitial fibrosis in renal grafts. We have used staining with picrosirius red followed by computerized image analysis to study the correlation between graft fibrosis and future development of glomerular filtration rate (GFR) in a group of children with advanced CAN.

METHODS

Renal biopsies were performed in 56 children (mean age, 13.7+/-3.6 years) after a mean period of 4.6+/-3.1 years after transplantation because of significant increases in serum creatinine. All biopsy specimens were stained with picrosirius red. The magnitude of fibrotic tissue was calculated by computerized image analysis. Linear regression analysis was performed correlating the intensity of graft fibrosis and the changes in the GFR at the time points of renal biopsy and 2 years later.

RESULTS

There was a significant positive correlation (r=0.62, P<0.001) between the picrosirius red-stained cortical fractional interstitial fibrosis volume (V(intFib)) and the decrease of GFR within 2 years postrenal biopsy. When V(intFib) was below 5%, 82% of the patients had an increase in GFR within 2 years. Ninety-three percent of the patients with greater than 10% of fibrosis experienced a worsening renal function after 2 years. When comparing patients with stable GFR with patients having a decrease in GFR, a highly significant difference in V(intFib) was found (P=0.008).

CONCLUSIONS

The quantitative measurement of fibrosis by picrosirius red staining appears to be a useful prognostic indicator for estimating long-term graft function in CAN and may provide an easy, fast, and inexpensive tool helpful for treatment decisions in patients developing CAN.

The impact of repeated subclinical acute rejection on the progression of chronic allograft nephropathy

Chronic allograft nephropathy (CAN) is due to both immunologic and non-immunologic factors and results in the development of nonspecific pathologic features that may even be present in long-term well-functioning renal allografts. To investigate the natural history of CAN and potential risk factors associated with progression of these histologic lesions, this study evaluated the of histologic alterations of 124 sequential protocol biopsies performed at 2, 3, and 5 yr after transplantation in 46 patients who exhibited histologic evidence of CAN in the 1-yr biopsy. The occurrence of late acute rejection (AR) greater than 4 mo posttransplant was significantly associated with the development of histologic CAN. In contrast, early clinical AR occurring within 3 mo had no impact on the subsequent development of CAN at 1 yr. Subclinical AR was evident in association with CAN in 50%, 32%, 19%, and 16% of cases with CAN at 1, 2, 3, and 5 yr, respectively. These acute lesions correlated significantly with histologic progression defined as an increased CADI score of the follow-up biopsies. Furthermore, a group of patients who exhibited repeated subclinical AR in the sequential follow-up biopsies had a lower creatinine clearance at 5 yr after transplantation and worse long-term graft survival. In contrast, the absence of evidence of acute inflammation in association with CAN at any time point was associated with minimal deterioration in renal function or progression of renal lesions during the observation period. These results suggest that the persistence of chronic active inflammation may be responsible for the histologic progression of CAN.

The influence of organ donor factors on early allograft function

PURPOSE OF REVIEW

Postischaemic acute renal allograft failure is among the main risk factors for reduced transplant survival. Although new immunosuppressive protocols have reduced the number of acute rejections, the incidence of acute renal failure remained unchanged. On the basis of histomorphology it is not possible to predict donor kidneys at risk of subsequent failure. Some factors are associated with failure, but even combinations of these risk factors can not precisely predict the development of acute renal failure. Studies have therefore evaluated the influence of demographic donor and recipient factors on acute renal failure. New biotechnology and data mining tools are currently being used to study and identify the molecular predictors of acute renal failure.

RECENT FINDINGS

Recent studies showed that donor factors contributed to approximately 40% of the variability in early allograft function. Deductive approaches identified some isolated molecular targets, such as adhesion molecules, as risk factors. Explorative analysis of the entire human genome, however, identified several predictive clusters of genes, which can be functionally grouped into categories such as cell death, stress response, cell adhesion, transcription factors, inflammatory response or cell cycle-related genes. Based on this information, preventative strategies using antisense oligonucleotides or antibodies were adopted. Clinical studies identified the use of catecholamines in the organ donor as beneficial. All these efforts aim to reduce renal tubular damage.

SUMMARY

A detailed analysis of the molecular events and pathways of renal gene expression in the donor and after reperfusion, together with sophisticated data analysis tools, will provide new insights into the pathophysiology of acute renal failure.

Real-time monitoring of acute liver-allograft rejection using the Banff schema

BACKGROUND

The Banff schema is the internationally accepted standard for grading acute liver-allograft rejection, but it has not been prospectively tested.

METHODS

Complete Banff grading was prospectively applied to 2,038 liver-allograft biopsies from 901 adult tacrolimus-treated primary hepatic allograft recipients between August 1995 and September 2001. Histopathologic data was melded with demographic, clinical, and laboratory data into a database on an ongoing basis using locally developed software.

RESULTS

Acute rejection developed in 575 of 901 (64%) patients and the worst grade was mild in 422 of 575 (73%). At least one episode of moderate or severe acute rejection developed in 153 of 901 (17%) patients and most episodes, irrespective of severity, occurred within the first year after transplantation. Patients with moderate or severe acute rejection showed higher alanine aminotransferase (P =0.007) and aspartate aminotransferase ( P=0.07) levels and were more likely to develop perivenular fibrosis on follow-up biopsies (P =0.001) and graft failure from acute or chronic rejection ( P=0.004) than those with mild rejection. Regardless of severity, 80% of patients with acute rejection did not develop significant fibrosis in follow-up biopsies, and graft failure from acute or chronic rejection occurred in only 11 of 901 (1%) allografts.

CONCLUSIONS

Most acute-rejection episodes are mild and do not lead to clinically significant architectural sequelae. When tested prospectively under real-life and -time conditions, the Banff schema can be used to identify those few patients who are potentially at risk for more significant problems. Creation, capture, and integration of non-free text, or "digital," pathology data can be used to prospectively conduct outcomes-based research in transplantation.