Histological Evolution of BK Virus-Associated Nephropathy: Importance of Integrating Clinical and Pathological Findings.

Long-term clinicopathological studies of BK-associated nephropathy (PyVAN) are not available. We studied 206 biopsies (71 patients), followed 3.09 ± 1.46 years after immunosuppression reduction. The biopsy features (% immunostain for PyV large T ag + staining and inflammation ± acute rejection) were correlated with viral load dynamics and serum creatinine to define the clinicopathological status (PyVCPS). Incidence of acute rejection was 28% in the second biopsy and 50% subsequently (25% mixed T cell-mediated allograft rejection (TCMR) + antibody-mediated allograft rejection (AMR); rejection overall affected 38% of patients (>50% AMR). Graft loss was 15.4% (0.8-5.3 years after PyVAN); 76% had complete viral clearance (mean 28 weeks). The only predictors of graft loss were acute rejection (TCMR p = 0.008, any type p = 0.07), and increased "t" and "ci" in the second biopsy (p = 0.006 and 0.048). Higher peak viremia correlated with poorer viral clearance (p = 0.002). Presumptive and proven PyVAN had similar presentation, evolution, and outcome. Late PyVAN (>2 years, 9.8%) justifies BK viremia evaluation at any point with graft dysfunction and/or biopsy evaluation. This study describes the histological evolution of PyVAN and corresponding clinicopathological correlations. Although the pathological features overall reflect the viral and immunological interactions, the PyVAN course remains difficult to predict based on any single feature. Appropriate clinical management requires repeat biopsies and determination of the PyVCPS at relevant time points, for corresponding personalized immunosuppression adjustment.

The Banff 2015 Kidney Meeting Report: Current Challenges in Rejection Classification and Prospects for Adopting Molecular Pathology.

The XIII Banff meeting, held in conjunction the Canadian Society of Transplantation in Vancouver, Canada, reviewed the clinical impact of updates of C4d-negative antibody-mediated rejection (ABMR) from the 2013 meeting, reports from active Banff Working Groups, the relationships of donor-specific antibody tests (anti-HLA and non-HLA) with transplant histopathology, and questions of molecular transplant diagnostics. The use of transcriptome gene sets, their resultant diagnostic classifiers, or common key genes to supplement the diagnosis and classification of rejection requires further consensus agreement and validation in biopsies. Newly introduced concepts include the i-IFTA score, comprising inflammation within areas of fibrosis and atrophy and acceptance of transplant arteriolopathy within the descriptions of chronic active T cell-mediated rejection (TCMR) or chronic ABMR. The pattern of mixed TCMR and ABMR was increasingly recognized. This report also includes improved definitions of TCMR and ABMR in pancreas transplants with specification of vascular lesions and prospects for defining a vascularized composite allograft rejection classification. The goal of the Banff process is ongoing integration of advances in histologic, serologic, and molecular diagnostic techniques to produce a consensus-based reporting system that offers precise composite scores, accurate routine diagnostics, and applicability to next-generation clinical trials.

Concurrent cytomegalovirus glomerulitis and BK polyomavirus-associated nephropathy in a kidney allograft biopsy.

A 58-year-old renal transplant recipient underwent biopsy 11 weeks post transplantation for increasing creatinine. The biopsy showed cytomegalovirus (CMV) glomerulitis together with BK polyomavirus (BKPyV)-associated nephropathy (PVAN). Treatment with intravenous ganciclovir and overall reduction in maintenance immunosuppression resulted in prompt resolution of the CMV glomerulitis, but with persistence of PVAN in a follow-up biopsy 4 weeks later. Stable creatinine and BKPyV viral clearance were observed at the last clinical visit 15 months post transplantation. This case exemplifies infectious glomerulitis, which requires differentiation from the more common glomerulitis caused by antibody-mediated allograft rejection. The morphological similarities and differences between BKPyV and CMV infections are discussed.

BK Polyomavirus Infection and Renourinary Tumorigenesis.

BK polyomavirus (BKPyV) infection represents a major problem in transplantation, particularly for renal recipients developing polyomavirus-associated nephropathy (PyVAN). The possibility that BKPyV may also be oncogenic is not routinely considered. Twenty high-grade renourinary tumors expressing polyomavirus large T antigen in the entirety of the neoplasm in 19 cases, including the metastases in six, have been reported in transplant recipients with a history of PyVAN or evidence of BKPyV infection. Morphological and phenotypical features consistent with inactivation of the tumor suppressors pRB and p53 were found in the bladder tumors, suggesting a carcinogenesis mechanism involving the BKPyV large tumor oncoprotein/antigen. The pathogenesis of these tumors is unclear, but given the generally long interval between transplantation and tumor development, the risk for neoplasms after BKPyV infections may well be multifactorial. Other elements potentially implicated include exposure to additional exogenous carcinogens, further viral mutations, and cell genomic instability secondary to viral integration, as occurs with the Merkel cell PyV-associated carcinoma. The still scarce but increasingly reported association between longstanding PyVAN and renourinary neoplasms requires a concerted effort from the transplant community to better understand, diagnose, and treat the putative association between the BKPyV and these neoplasms.

Islet Amyloid in Whole Pancreas Transplants for Type 1 Diabetes Mellitus (DM): Possible Role of Type 2 DM for Graft Failure.

Long-term results with whole pancreas (WPTx) and islet transplantation (IT) continue to be suboptimal. Graft failure with undetectable C-peptide level is attributed to graft sclerosis (chronic rejection), recurrence of Type 1 diabetes mellitus (DM), or insufficient islet mass. In contrast, graft failure with measurable C-peptide has overlapping clinical features with Type 2 DM (suggesting persistent but insufficient ß cell function), but is poorly understood. In general, the morphological substrate for islet failure is unclear because grafted islets are not routinely evaluated. We present two patients with graft failure at 5 and 8 years after successful WPTx for Type 1 DM, presenting with preserved C-peptide levels. On histopathology, the islets had preserved both α and ß cell populations but also prominent accumulation of islet amyloid (IA), the morphological hallmark of Type 2 DM. IA previously reported in IT, represents fibrillary aggregates of islet amyloid polypeptide, a hormone normally cosecreted with insulin. Accumulation of IA correlates quantitatively with the development of hyperglycemia and is known to cause ß cell dysfunction and loss. Accumulation of IA and development of Type 2 DM should be considered and studied as a potential cause of long-term islet failure in IT and WPTx.

Bartonella henselae infection-associated vasculitis and crescentic glomerulonephritis leading to renal allograft loss.

Bartonella henselae (BH) is the main cause of cat scratch disease (CSD), which more typically presents as a self-limited localized suppurative lymphadenopathy in immunocompetent individuals. In contrast, immunocompromised patients commonly have systemic disease with life-threatening complications. In addition to the angioproliferative lesions, such as bacillary angiomatosis, an increasing number of immune post-infectious complications are being recognized with BH infections, including glomerulonephritis, vasculitis, hemophagocytic syndrome, and neurological problems. We report the case of a renal transplant recipient who developed CSD in the second year post transplantation. In addition to prolonged fever and generalized lymphadenopathy and splenomegaly requiring differentiation from a post-transplant lymphoproliferative disorder, the course was complicated by the development of dermal leukocytoclastic vasculitis and pauci-immune necrotizing and crescentic glomerulonephritis, which led to failure of the renal graft. Glomerulonephritis as a complication of CSD has never been described in a kidney allograft, to our knowledge. Awareness of the diverse clinical symptoms associated with BH, including granulomatous/suppurative lesions and other less common complications can lead to more rapid and accurate diagnosis. Also, as recommended by the current guidelines, a thorough history of pet ownership should be part of the clinical evaluation before and after transplantation for all transplant recipients.

Banff 2013 meeting report: inclusion of c4d-negative antibody-mediated rejection and antibody-associated arterial lesions.

The 12th Banff Conference on Allograft Pathology was held in Comandatuba, Brazil, from August 19-23, 2013, and was preceded by a 2-day Latin American Symposium on Transplant Immunobiology and Immunopathology. The meeting was highlighted by the presentation of the findings of several working groups formed at the 2009 and 2011 Banff meetings to: (1) establish consensus criteria for diagnosing antibody-mediated rejection (ABMR) in the presence and absence of detectable C4d deposition; (2) develop consensus definitions and thresholds for glomerulitis (g score) and chronic glomerulopathy (cg score), associated with improved inter-observer agreement and correlation with clinical, molecular and serological data; (3) determine whether isolated lesions of intimal arteritis ("isolated v") represent acute rejection similar to intimal arteritis in the presence of tubulointerstitial inflammation; (4) compare different methodologies for evaluating interstitial fibrosis and for performing/evaluating implantation biopsies of renal allografts with regard to reproducibility and prediction of subsequent graft function; and (5) define clinically and prognostically significant morphologic criteria for subclassifying polyoma virus nephropathy. The key outcome of the 2013 conference is defining criteria for diagnosis of C4d-negative ABMR and respective modification of the Banff classification. In addition, three new Banff Working Groups were initiated.

Mast cell quantitation in renal transplant biopsy specimens as a potential marker for the cumulative burden of tissue injury.

Although mast cells (MC) play an ambiguous role in acute rejection, they have been implicated in chronic fibrotic processes overall and also in the kidney. Their morphological assessment in the context of comprehensive renal allograft pathology has not been sufficiently addressed, however. Using the CD117 immunostain in 461 consecutive kidney allograft biopsy specimens we counted the number of MC in the most inflamed biopsy area. The number of MC was correlated with the presence of the Banff defined features of T-cell-mediated and antibody-mediated rejection. No correlation was found between the number of MC and the presence or degree of T-cell-mediated rejection or with most parameters defining acute or chronic antibody-mediated rejection. Significant correlation was found, however, with the degree of interstitial fibrosis (IF; P = .000), and time post- transplantation (P = .000). Peritubular C4d staining correlated negatively with the number of MC (P = .000). Correlation of MC infiltration and peritubular capillary multilamellation (P = .000) indicated an association between general interstitial and microvascular chronic pathology. We conclude that MC represent a somewhat unique cellular component that correlates poorly with parameters of active T-cell or antibody-mediated allograft rejection. In contrast, because MC correlate strongly with IF and time post-transplantation, they could potentially be valuable as a surrogate marker for the cumulative burden of tissue injury.

End-stage renal disease and African American race are independent predictors of mild liver fibrosis in patients with chronic hepatitis C infection.

Recipients of haemodialysis for end-stage renal disease (ESRD) have a higher prevalence of hepatitis C virus (HCV) infection relative to the general US population. However, the natural course of HCV infection in patients with renal failure, including African Americans (AAs) and Caucasian Americans (CAs), is not well known. We compared the degree of liver inflammation and fibrosis in AA and CA patients with HCV infection, with and without ESRD. This was a cross-sectional study of 156 HCV patients with ESRD (130 AAs and 26 CAs) with a liver biopsy between 1992 and 2005. The control group consisted of 138 patients (50 AAs; 88 CAs) with HCV infections and a serum creatinine <1.5 mg/dL with a liver biopsy between 1995 and 1998. Specimens were graded for inflammation and fibrosis using Knodell histological activity index. Compared to patients without renal impairment, HCV patients with renal failure were older and more likely to be AA. Patients with renal impairment had lower mean serum transaminases, a higher mean serum alkaline phosphatase levels (all P < 0.0001) and less hepatic necro-inflammation (Knodell histological activity index -I, II and III; P < 0.05) and fibrosis (Knodell histological activity index -IV; P < 0.0001). There were no racial differences in serum liver chemistry and histology scores among patients with renal failure. In a multivariate analysis, younger age, ESRD, AA race and a lower serum alkaline phosphatase were associated with lower odds for advanced liver fibrosis. Thus, HCV patients with ESRD had a lower degree of hepatic inflammation and fibrosis compared to those without renal disease, independent of race.

Banff 2011 Meeting report: new concepts in antibody-mediated rejection.

The 11th Banff meeting was held in Paris, France, from June 5 to 10, 2011, with a focus on refining diagnostic criteria for antibody-mediated rejection (ABMR). The major outcome was the acknowledgment of C4d-negative ABMR in kidney transplants. Diagnostic criteria for ABMR have also been revisited in other types of transplants. It was recognized that ABMR is associated with heterogeneous phenotypes even within the same type of transplant. This highlights the necessity of further refining the respective diagnostic criteria, and is of particular significance for the design of randomized clinical trials. A reliable phenotyping will allow for definition of robust end-points. To address this unmet need and to allow for an evidence-based refinement of the Banff classification, Banff Working Groups presented multicenter data regarding the reproducibility of features relevant to the diagnosis of ABMR. However, the consensus was that more data are necessary and further Banff Working Group activities were initiated. A new Banff working group was created to define diagnostic criteria for ABMR in kidneys independent of C4d. Results are expected to be presented at the 12th Banff meeting to be held in 2013 in Brazil. No change to the Banff classification occurred in 2011.

Guidelines for the diagnosis of antibody-mediated rejection in pancreas allografts-updated Banff grading schema.

The first Banff proposal for the diagnosis of pancreas rejection (Am J Transplant 2008; 8: 237) dealt primarily with the diagnosis of acute T-cell-mediated rejection (ACMR), while only tentatively addressing issues pertaining to antibody-mediated rejection (AMR). This document presents comprehensive guidelines for the diagnosis of AMR, first proposed at the 10th Banff Conference on Allograft Pathology and refined by a broad-based multidisciplinary panel. Pancreatic AMR is best identified by a combination of serological and immunohistopathological findings consisting of (i) identification of circulating donor-specific antibodies, and histopathological data including (ii) morphological evidence of microvascular tissue injury and (iii) C4d staining in interacinar capillaries. Acute AMR is diagnosed conclusively if these three elements are present, whereas a diagnosis of suspicious for AMR is rendered if only two elements are identified. The identification of only one diagnostic element is not sufficient for the diagnosis of AMR but should prompt heightened clinical vigilance. AMR and ACMR may coexist, and should be recognized and graded independently. This proposal is based on our current knowledge of the pathogenesis of pancreas rejection and currently available tools for diagnosis. A systematized clinicopathological approach to AMR is essential for the development and assessment of much needed therapeutic interventions.

Vascularized bone marrow-based immunosuppression inhibits rejection of vascularized composite allografts in nonhuman primates.

Vascularized composite allograft (VCA) transplantation (also referred to as composite tissue allotransplantation) has demonstrated clinical success in cases of hand, arm and face transplantation despite prior belief that skin provides an insurmountable barrier to allograft rejection. These overall good outcomes are facilitated by substantial immunosuppressive requirements in otherwise healthy patients, yet still demonstrate frequent rejection episodes. We developed a nonhuman primate model of facial segment allotransplantation to elucidate the unique pathophysiology and immunosuppressive requirements of VCA with addition of concomitant vascularized bone marrow (VBM). Heterotopically transplanted facial segment VCA with VBM treated only with tacrolimus and mycophenolate mofetil (MMF) demonstrated prolonged rejection-free survival, compared to VCA without VBM that demonstrated early rejection episodes and graft loss. While VCA with VBM demonstrated sporadic macrochimerism, acute and chronic rejection and graft loss occurred after discontinuation of immunosuppression. These data support an immunomodulatory role of VBM in VCA that reduces immunosuppressive requirements while providing improved outcomes.

Pancreas allograft biopsies with positive c4d staining and anti-donor antibodies related to worse outcome for patients.

C4d+ antibody-mediated rejection following pancreas transplantation has not been well characterized. Therefore, we assessed the outcomes of 27 pancreas transplantation patients (28 biopsies), with both C4d staining and donor-specific antibodies (DSA) determined, from a cohort of 257 patients. The median follow-up was 50 (interquartile range [IQR] 8-118) months. Patients were categorized into 3 groups: group 1, patients with minimal or no C4d staining and no DSA (n = 13); group 2, patients with either DSA present but no C4d, diffuse C4d+ and no DSA or focal C4d+ and DSA (n = 6); group 3, patients with diffuse C4d+ staining and DSA (n = 9). Active septal inflammation, acinar inflammation and acinar cell injury/necrosis were significantly more abundant in group 3 than in group 2 (respective p-values: 0.009; 0.033; 0.025) and in group 1 (respective p-values: 0.034; 0.009; 0.002). The overall uncensored pancreas graft survival rate for groups 1, 2 and 3 were 53.3%, 66.7% and 34.6%, respectively (p = 0.044). In conclusion, recipients of pancreas transplants with no C4d or DSA had excellent long-term graft survival in comparison with patients with both C4d+ and DSA present. Hence, C4d should be used as an additional marker in combination with DSA in the evaluation of pancreas transplant biopsies.

Banff '09 meeting report: antibody mediated graft deterioration and implementation of Banff working groups.

The 10th Banff Conference on Allograft Pathology was held in Banff, Canada from August 9 to 14, 2009. A total of 263 transplant clinicians, pathologists, surgeons, immunologists and researchers discussed several aspects of solid organ transplants with a special focus on antibody mediated graft injury. The willingness of the Banff process to adapt continuously in response to new research and improve potential weaknesses, led to the implementation of six working groups on the following areas: isolated v-lesion, fibrosis scoring, glomerular lesions, molecular pathology, polyomavirus nephropathy and quality assurance. Banff working groups will conduct multicenter trials to evaluate the clinical relevance, practical feasibility and reproducibility of potential changes to the Banff classification. There were also sessions on quality improvement in biopsy reading and utilization of virtual microscopy for maintaining competence in transplant biopsy interpretation. In addition, compelling molecular research data led to the discussion of incorporation of omics-technologies and discovery of new tissue markers with the goal of combining histopathology and molecular parameters within the Banff working classification in the near future.

Tubular epithelial cell and podocyte apoptosis with de novo sirolimus based immunosuppression in renal allograft recipients with DGF.

Sirolimus is associated with prolonged delayed graft function (DGF) following renal transplantation and exacerbation of proteinuria. We assessed renal allograft biopsies from DGF patients treated with de novo sirolimus (n = 10) for renal tubular cell and podocyte apoptosis and expression of activated caspase-3, Bcl-2, and mTOR and compared them to biopsies from DGF patients not receiving sirolimus (n = 15). Both groups received mycophenolate mofetil, prednisone and antibody induction. Apoptosis was assessed using terminal deoxynucleodidyl transferase mediated dUTP nick end labeling (TUNEL) staining. Caspase-3, Bcl-2, and mTOR expression were assessed by immunohistochemistry. Sirolimus treated patients had 334+/-69 TUNEL positive cells per 5 high power fields compared to 5.5+/-2.9 TUNEL positive cells in control patients (p<0.001). The number of TUNEL positive cells correlated with tubular architectural disruption. Expression of activated caspase-3, Bcl-2, or activated mTOR did not differ between groups. 60% of biopsies from sirolimus treated patients compared to 7% of biopsies from controls showed diffuse podocyte apoptosis (p = 0.007). There was no podocyte expression of activated mTOR, activated caspase-3, or Bcl-2 in either group. These data suggest that DGF patients treated with sirolimus have increased renal tubular cell apoptosis and podocyte apoptosis.

The impact of c4d pattern and donor-specific antibody on graft survival in recipients requiring indication renal allograft biopsy.

We examined the pattern of PTC C4d by immunohistochemistry and DSA in 297 kidney recipients with indication biopsies, and evaluated their predictive value for graft survival. Median biopsy time was 5.1 months posttransplant. Patients were followed for 17.9 +/- 9.4 months postbiopsy. An 18.5% had focal and 15.2% had diffuse C4d, with comparable graft survival (adjusted graft failure HR: 2.3, p = 0.001; HR:1.9, p < 0.02, respectively). 31.3% were DSA+, 19.5% class I and 22.9% class II DSA. Only those with class II DSA had worse outcome (adjusted HR:2.5, p = 0.001 for class II only; HR:2.7, p < 0.001 for class I/II DSA). Among patients with <10%C4d, 23.9% had DSA, compared to 68.9% with diffuse staining. For patients biopsied in first-year posttransplant presence of DSA, regardless of C4d positivity in biopsy, was a poor prognostic factor (adjusted graft failure HR: 4.2, p < 0.02 for C4d-/DSA+; HR:4.9, p = 0.001 for C4d+/DSA+), unlike those biopsied later. We have shown that focal C4d had similar impact on graft survival as diffuse pattern. During the first-year posttransplant either class I or II DSA, and afterward only class II DSA were associated with worse graft survival. DSA was predictive of worse outcome regardless of C4d for patients biopsied in first year and only with C4d positivity afterward, supporting the importance of assessment of both DSA and C4d pattern in biopsy.

Positive cross-match living donor kidney transplantation: longer-term outcomes.

The long-term graft outcomes after positive cross-match (PXM) living donor kidney transplantation (LDKT) are unknown and the descriptive published data present short-medium term results. We conducted a retrospective cohort study of LDKT with PXM by flow cytometry performed at our center during February 1999 to October 2006, compared to a control group, matched 1:1 for age, sex, race, retransplantation and transplant year. The PXM group was treated with a course of plasmapheresis/low-dose intravenous immunoglobulin (IVIg) preoperatively, and OKT3 or thymoglobulin induction. Both groups (n = 41 each) were comparable except for duration of end-stage renal disease (ESRD), induction, HLA mismatch and panel-reactive antibody (PRA). During the period of up to 9 years, 14 PXM and 7 controls lost their grafts (p < 0.04). Graft survival rates at 1 and 5 years were 89.9% and 69.4% for PXM group and 97.6% and 80.6% for the controls, respectively. PXM was associated with higher risk of graft loss (HR 2.6, p = 0.04; 95%CI 1.03-6.4) (t(1/2)= 6.8 years), but not with patient survival (HR 1.96, p = 0.29; 95%CI 0.6-7.0) or 1-year serum creatinine (beta= 0.06, p = 0.59 for ln (SCr); 95% CI -0.16 to 0.28). These results suggest that despite the favorable short-term results of PXM LDKT after PP/IVIg conditioning, medium-long-term outcomes are notably worse than expected, perhaps comparable to non-ECD deceased donor kidney transplantation (KT).

The detrimental effect of poor early graft function after laparoscopic live donor nephrectomy on graft outcomes.

We undertook this study to assess the rate of poor early graft function (EGF) after laparoscopic live donor nephrectomy (lapNx) and to determine whether poor EGF is associated with diminished long-term graft survival. The study population consisted of 946 consecutive lapNx donors/recipient pairs at our center. Poor EGF was defined as receiving hemodialysis on postoperative day (POD) 1 through POD 7 (delayed graft function [DGF]) or serum creatinine >/= 3.0 mg/dL at POD 5 without need for hemodialysis (slow graft function [SGF]). The incidence of poor EGF was 16.3% (DGF 5.8%, SGF 10.5%), and it was stable in chronologic tertiles. Poor EGF was independently associated with worse death-censored graft survival (adjusted hazard ratio (HR) 2.15, 95% confidence interval (CI) 1.34-3.47, p = 0.001), worse overall graft survival (HR 1.62, 95% CI 1.10-2.37, p = 0.014), worse acute rejection-free survival (HR 2.75, 95% CI 1.92-3.94, p < 0.001) and worse 1-year renal function (p = 0.002). Even SGF independently predicted worse renal allograft survival (HR 2.54, 95% CI 1.44-4.44, p = 0.001). Risk factors for poor DGF included advanced donor age, high recipient BMI, sirolimus use and prolonged warm ischemia time. In conclusion, poor EGF following lapNx has a deleterious effect on long-term graft function and survival.

The Maryland aggregate pathology index: a deceased donor kidney biopsy scoring system for predicting graft failure.

Despite the common use of diagnostic pretransplant deceased donor kidney biopsy, there is no consensus on the prognostic significance of the pathologic findings. In order to assist clinicians with interpretation we analyzed 371 pretransplant biopsies and correlated the findings with graft failure. Glomerular pathology was assessed with percent glomerulosclerosis (GS), glomerular size and periglomerular fibrosis (PGF); vascular pathology with arterial wall-to-lumen ratio (WLR) and arteriolar hyalinosis and interstitial pathology with measurement of cumulative fibrosis and presence of scar. Using two-thirds of the study population as a model-development cohort, we found that biopsy features independently associated with an increased risk of graft failure were GS > or =15%, interlobular arterial WLR > or =0.5 and the presence of PGF, arteriolar hyalinosis or scar. The Maryland Aggregate Pathology Index (MAPI), was developed from these parameters and validated on the remaining one-third of the population. Five-year actuarial graft survival was 90% for kidneys with MAPI scores between 0 and 7, 63% for scores from 8 to 11 and 53% for scores from 12 to 15 (p < 0.001). We conclude MAPI may help transplant physicians estimate graft survival from the preimplantation biopsy findings, in clinical situations similar to this study population (cold ischemia over 24 h, GS < 25%).