Exploring kidney allograft rejection: A proof-of-concept study using spatial transcriptomics.

In this proof-of-concept study, spatial transcriptomics combined with public single-cell ribonucleic acid-sequencing data were used to explore the potential of this technology to study kidney allograft rejection. We aimed to map gene expression patterns within diverse pathologic states by examining biopsies classified across nonrejection, T cell-mediated acute rejection, interstitial fibrosis, and tubular atrophy. Our results revealed distinct immune cell signatures, including those of T and B lymphocytes, monocytes, mast cells, and plasma cells, and their spatial organization within the renal interstitium. We also mapped chemokine receptors and ligands to study immune cell migration and recruitment. Finally, our analysis demonstrated differential spatial enrichment of transcription signatures associated with kidney allograft rejection across various biopsy regions. Interstitium regions displayed higher enrichment scores for rejection-associated gene expression patterns than tubular areas, which had negative scores. This implies that these signatures are primarily driven by processes unfolding in the renal interstitium. Overall, this study highlights the value of spatial transcriptomics for revealing cellular heterogeneity and immune signatures in renal transplant biopsies and demonstrates its potential for studying the molecular and cellular mechanisms associated with rejection. However, certain limitations must be borne in mind regarding the development and future applications of this technology.

Banff 2022 Liver Group Meeting report: Monitoring long-term allograft health.

The Banff Working Group on Liver Allograft Pathology met in September 2022. Participants included hepatologists, surgeons, pathologists, immunologists, and histocompatibility specialists. Presentations and discussions focused on the evaluation of long-term allograft health, including noninvasive and tissue monitoring, immunosuppression optimization, and long-term structural changes. Potential revision of the rejection classification scheme to better accommodate and communicate late T cell-mediated rejection patterns and related structural changes, such as nodular regenerative hyperplasia, were discussed. Improved stratification of long-term maintenance immunosuppression to match the heterogeneity of patient settings will be central to improving long-term patient survival. Such personalized therapeutics are in turn contingent on a better understanding and monitoring of allograft status within a rational decision-making approach, likely to be facilitated in implementation with emerging decision-support tools. Proposed revisions to rejection classification emerging from the meeting include the incorporation of interface hepatitis and fibrosis staging. These will be opened to online testing, modified accordingly, and subject to consensus discussion leading up to the next Banff conference.

Subclinical Pancreas Rejection on Protocol Biopsy Within the First Year of Simultaneous Pancreas Kidney Transplant.

This single-center retrospective study investigated subclinical rejection prevalence and significance in simultaneous pancreas and kidney transplant (SPKT) recipients. We analyzed 352 SPKT recipients from July 2003 to April 2022. Our protocol included pancreas allograft surveillance biopsies at 1, 4, and 12months post-transplant. After excluding 153 patients unable to undergo pancreas biopsy, our study cohort comprised 199 recipients. Among the 199 patients with protocol pancreas biopsies, 107 had multiple protocol pancreas biopsies in the first year, totaling 323. Subclinical rejection was identified in 132 episodes (41%). Of these, 72% were Grade 1, 20% were indeterminate, and 8% were Banff Grade 2 or higher. All episodes of subclinical rejection were treated. Rates of pancreas graft loss (10% vs. 7%) and clinical rejection (21% vs. 20%) at 3 years were similar between those with and without subclinical rejection. Subclinical rejection Banff Grade 2 or more was associated with poor pancreas graft survival HR of 5.5 (95% CI: 1.24-24.37, p = 0.025). Of 236 simultaneous protocol kidney and pancreas biopsies, 102 (43%) showed pancreas subclinical rejection, while only 17% had concurrent kidney subclinical rejection. Our findings suggest limited predictive value of pancreatic enzymes and euglycemia in detecting pancreas rejection. Furthermore, poor concordance existed between pancreas and kidney subclinical rejection.

Protocol biopsy of kidney allograft enables early detection of BK virus nephropathy to preserve kidney allograft function.

BACKGROUND: The Banff Working Group has updated the histological classification of BK virus nephropathy (BKVN), highlighting the importance of early detection. However, an early detection strategy for BKVN using biopsy has not yet been established. Our investigation aimed to assess the efficacy of protocol biopsy for the diagnosis of BKVN. METHODS: We performed a retrospective cohort study of 314 patients who had undergone kidney transplantation between 2006 and 2021. Kidney allograft biopsies were performed as part of a protocol biopsy at 3 months and 1 year post-transplantation. Following the diagnosis of BKVN, the immunosuppressant dose was reduced. RESULTS: Twelve patients (3.8%) were diagnosed with BKVN by biopsy. Most diagnoses are established during the early stages of BKVN (polyomavirus nephropathy class 1 in six, class 2 in five, and class 3 in one). Following the reduction in immunosuppressant dose, kidney allograft function did not deteriorate in any patients. Additionally, test for BK virus DNA in the blood was negative. All but one patient demonstrated histological resolution of BKVN, and the other had a very slight positivity for the simian virus 40 large T antigen. The median follow-up time after BKVN diagnosis was 6 years. One patient developed de novo donor-specific antibody and subclinical acute antibody-mediated rejection that was successfully cured. CONCLUSIONS: Our analysis indicates that protocol biopsy may enable the early detection of BKVN, resulting in the preservation of kidney function.

New Insights into Pediatric Kidney Transplant Rejection Biomarkers: Tissue, Plasma and Urine MicroRNAs Compared to Protocol Biopsy Histology.

The early identification of a subclinical rejection (SCR) can improve the long-term outcome of the transplanted kidney through intensified immunosuppression. However, the only approved diagnostic method is the protocol biopsy, which remains an invasive method and not without minor and/or major complications. The protocol biopsy is defined as the sampling of allograft tissue at pre-established times even in the absence of an impaired renal function; however, it does not avoid histological damage. Therefore, the discovery of new possible biomarkers useful in the prevention of SCR has gained great interest. Among all the possible candidates, there are microRNAs (miRNAs), which are short, noncoding RNA sequences, that are involved in mediating numerous post-transcriptional pathways. They can be found not only in tissues, but also in different biological fluids, both as free particles and contained in extracellular vesicles (EVs) released by different cell types. In this study, we firstly performed a retrospective miRNA screening analysis on biopsies and serum EV samples of 20 pediatric transplanted patients, followed by a second screening on another 10 pediatric transplanted patients' urine samples at one year post-transplant. In both cohorts, we divided the patients into two groups: patients with histological SCR and patients without histological SCR at one year post-transplantation. The isolated miRNAs were analyzed in an NGS platform to identify different expressions in the two allograft states. Although no statistical data were found in sera, in the tissue and urinary EVs, we highlighted signatures of miRNAs associated with the histological SCR state.

Prognostic value of the 7-year protocol biopsy of adult kidney allografts: impact of mesangiosclerosis and proteinuria.

AIM: The aim of the present study was to clarify the relationship between the Banff score of the 7-year protocol biopsy and the allograft outcome. METHODS: One-hundred-and-eighty-four patients received kidney transplantation from 2002 to 2008. We excluded patients aged <20 years at transplantation (n = 24), those who did not undergo a 7-year protocol biopsy (n = 66), and those who underwent for-cause biopsy (n = 5). Consequently, 89 patients who underwent a 7-year protocol biopsy were enrolled. We analyzed the relationship between the clinicopathological findings 7 years after transplantation and the estimated glomerular filtration rate (eGFR) change per year and allograft survival. Histological evaluation was performed using the Banff 2015 classification. RESULTS: Among the clinicopathological findings, each Banff mesangial matrix increase (mm) score ≥1 and proteinuria ≥1+ was independently associated with the eGFR decline per year during a median follow-up of 73 months. Furthermore, in the model of the clinicopathological findings including the presence of mm with proteinuria, mm ≥1 alone and mm ≥1 with proteinuria were each independently associated with the eGFR decline. The graft survival was significantly worse for those with mm ≥1 with proteinuria than those with mm ≥1 without proteinuria. CONCLUSION: Among the 7-year protocol biopsy findings, the presence of mm alone and mm with proteinuria were each significant predictors of eGFR decline. The presence of both proteinuria and mm had a negative impact on graft survival. These results underscore the significance of the Banff mm score and proteinuria at the time of the 7-year protocol biopsy to predict the allograft outcome.

Urinary tract infection in the context of mini-invasive procedures after kidney transplantation.

INTRODUCTION: The use of antibiotic prophylaxis in invasive procedures is generally accepted and highly recommended. The question is the need to apply antibiotic prophylaxis even in the case of mini-invasive procedures in the post-transplantation period. The aim of the study was to dermine the occurrence of infectious complications during mini-invasive procedures (pig-tail extraction, protocol biopsy) withou the use of antibiotic (ATB) prophylaxis. The secondary aim was to identify risk factors for a positive urine culture finding at the time of mini-invasive procedures. MATERIAL: This is a prospective monocentric study in which pacients after kidney transplantation at Transplantation centrum in Martin were included (n = 68). We investigated the incidence of positive urine findings at the time of pig-tail extraction (6 weeks after transplantation) and at the time of protocol biopsy (3 months after transplantation) with comparison within the group with and without ATB prophylaxis. RESULTS: Patients in group without ATB prophylaxis had a significantly higher tacrolimus value at the time of pig-tail extraction (p = 0.0274) and a significantly higher dose of mycophenolic acid at the time of protocol biopsy (p = 0.0429). We did not confirm significant difference in occcurence of positive urine findings at the time of pig-tail extraction or at the time of protocol biopsy. We completed a univariate logistic regression in order to identify a potential risk predictor for positive urine findings at the time of pig-tail extraction and protocol biopsy. None of the monitored parameters, including ATB prophylaxis, was confirmed as risk or protective factor. CONCLUSION: The use of antibiotic prophylaxis during mini-invasive procedures (pig-tail extraction, protocol biopsy) in the posttransplantation period had no effect on positive culture findings at our department. Based on our analysis, we therefore do not use antibiotic prophylaxis in the case of these procedures at our centre (Tab. 3, Fig. 6, Ref. 23).

Posttransplant recurrence of calcium oxalate crystals in patients with primary hyperoxaluria: Incidence, risk factors, and effect on renal allograft function.

Primary hyperoxaluria (PH) is a metabolic defect that results in oxalate overproduction by the liver and leads to kidney failure due to oxalate nephropathy. As oxalate tissue stores are mobilized after transplantation, the transplanted kidney is at risk of recurrent disease. We evaluated surveillance kidney transplant biopsies for recurrent calcium oxalate (CaOx) deposits in 37 kidney transplants (29 simultaneous kidney and liver [K/L] transplants and eight kidney alone [K]) in 36 PH patients and 62 comparison transplants. Median follow-up posttransplant was 9.2 years (IQR: [5.3, 15.1]). The recurrence of CaOx crystals in surveillance biopsies in PH at any time posttransplant was 46% overall (41% in K/L, 62% in K). Higher CaOx crystal index (which accounted for biopsy sample size) was associated with higher plasma and urine oxalate following transplant (p < .01 and p < .02, respectively). There was a trend toward higher graft failure among PH patients with CaOx crystals on surveillance biopsies compared with those without (HR 4.43 [0.88, 22.35], p = .07). CaOx crystal deposition is frequent in kidney transplants in PH patients. The avoidance of high plasma oxalate and reduction of CaOx crystallization may decrease the risk of recurrent oxalate nephropathy following kidney transplantation in patients with PH. This study was approved by the IRB at Mayo Clinic.

Diffuse C4d staining of peritubular capillaries in renal allograft following bamlanivimab therapy.

Neutralizing monoclonal antibodies such as bamlanivimab emerged as promising agents in treating kidney transplant recipients with COVID-19. However, the impact of bamlanivimab on kidney allograft histology remains unknown. We report a case of a kidney transplant recipient who received bamlanivimab for COVID-19 with subsequent histologic findings of diffuse peritubular capillary C4d staining. A 33-year-old man with end-stage kidney disease secondary to hypertension who received an ABO compatible kidney from a living donor, presented for his 4-month protocol visit. He was diagnosed with COVID-19 44 days prior to his visit and had received bamlanivimab with an uneventful recovery. His 4-month surveillance biopsy showed diffuse C4d staining of the peritubular capillaries without other features of antibody-mediated rejection (ABMR). Donor-specific antibodies were negative on repeat evaluations. ABMR gene expression panel was negative. His creatinine was stable at 1.3 mg/dl, without albuminuria. Given the temporal relationship between bamlanivimab and our observations of diffuse C4d staining of the peritubular capillaries, we hypothesize that bamlanivimab might bind to angiotensin-converting enzyme 2, resulting in classical complement pathway and C4d deposition. We elected to closely monitor kidney function which has been stable at 6 months after the biopsy. In conclusion, diffuse C4d may present following bamlanivimab administration without any evidence of ABMR.

Donor-derived cell-free DNA and renal allograft rejection in surveillance biopsies and indication biopsies.

To evaluate the role of circulating dd-cfDNA in allograft surveillance in immunologically high-risk patients, a retrospective cross-sectional study of 261 kidney transplant recipients who underwent outpatient allograft biopsy at our center between September 2020 and August 2021 was performed. Of the 236 dd-cfDNA results included, 37 samples were obtained at the time of a surveillance biopsy in sensitized recipients and 199 at the time of a clinically indicated biopsy. The median serum creatinine at the time of the biopsy was 1.3 mg/dl and 2.1 mg/dl for surveillance biopsies and clinically indicated biopsies, respectively (P < .001). Rejection was diagnosed in 27% of surveillance biopsies and 29% of clinically indicated biopsies. Among surveillance biopsies, sensitivity and specificity to detect rejection were 0% and 89%, respectively, and among clinically indicated biopsies they were 28% and 96%, respectively. The sensitivity and specificity to detect antibody-mediated rejection were 0% and 91% among surveillance biopsies and 50% and 94% among clinically indicated biopsies. Nine biopsies without rejection findings had corresponding dd-cfDNA of ≥1%. Our data does not support dd-cfDNA as a biomarker for kidney allograft rejection, even in immunologically high-risk patients in the absence of graft dysfunction.

Histologic acute graft pyelonephritis after kidney transplantation: Incidence, clinical characteristics, risk factors, and association with graft loss.

BACKGROUND: Histologic acute graft pyelonephritis (HAGPN) after kidney transplantation (KT) has been assessed less frequently than urinary tract infections (UTIs) or clinical acute graft pyelonephritis. Risk factors for HAGPN, its association with graft loss, and measures that might prevent it are not known. METHODS: We performed a retrospective review of HAGPN cases identified from KT occurring between January 2008 and December 2017 at our institution. We compared the HAGPN cases to a randomly selected control group of KTs to identify risk factors using univariate and multivariate Cox regression models. The association between HAGPN and graft loss was also assessed, similarly. RESULTS: HAGPN was identified in 46 of 1391 patients (cumulative incidence, 5% [95% CI, 3%-7%]) undergoing KT at a single center from January 2008 through December 2017 (median time to diagnosis, 241 days after KT; interquartile range, 122-755 days). Indications for biopsy were follow-up of treated rejection (n = 20 [43%]), KT protocol biopsy (n = 19 [41%]), and acute kidney injury (n = 7 [15%]). Histologic rejection, UTI, and asymptomatic bacteriuria (ASB) were present in 23 (50%), 9 (20%), and 16 (35%). Multivariate Cox proportional hazards models comparing KT recipients with or without HAGPN (n = 46 and n = 138, respectively) showed that HAGPN was associated with urologic complication by day 30, delayed graft function, previous UTI or ASB, and a history of rejection. In the univariate and multivariate analyses, HAGPN was associated with an increased risk of graft loss. CONCLUSION: HAGPN is an infrequent, unanticipated, and clinically significant complication of KT.

Economic analysis of screening for subclinical rejection in kidney transplantation using protocol biopsies and noninvasive biomarkers.

Subclinical rejection (SCR) screening in kidney transplantation (KT) using protocol biopsies and noninvasive biomarkers has not been evaluated from an economic perspective. We assessed cost-effectiveness from the health sector perspective of SCR screening in the first year after KT using a Markov model that compared no screening with screening using protocol biopsy or biomarker at 3 months, 12 months, 3 and 12 months, or 3, 6, and 12 months. We used 12% subclinical cellular rejection and 3% subclinical antibody-mediated rejection (SC-ABMR) for the base-case cohort. Results favored 1-time screening at peak SCR incidence rather than repeated screening. Screening 2 or 3 times was favored only with age <35 years and with high SC-ABMR incidence. Compared to biomarkers, protocol biopsy yielded more quality-adjusted life years (QALYs) at lower cost. A 12-month biopsy cost $13 318/QALY for the base-case cohort. Screening for cellular rejection in the absence of SC-ABMR was less cost effective with 12-month biopsy costing $46 370/QALY. Screening was less cost effective in patients >60 years. Using biomarker twice or thrice was cost effective only if biomarker cost was <$700. In conclusion, in KT, screening for SCR more than once during the first year is not economically reasonable. Screening with protocol biopsy was favored over biomarkers.

Interleukin-6 blockade with tocilizumab increases Tregs and reduces T effector cytokines in renal graft inflammation: A randomized controlled trial.

Interleukin-6 (IL-6) is a proinflammatory cytokine and key regulator of Treg: T effector cell (Teff) balance. We hypothesized that IL-6 blockade with tocilizumab, a monoclonal antibody to IL-6R, would increase Tregs, dampen Teff function, and control graft inflammation. We conducted a randomized controlled clinical trial (2014-2018) of clinically stable kidney transplant recipients on calcineurin inhibitor, mycophenolate mofetil, and prednisone, with subclinical graft inflammation noted on surveillance biopsies during the first year posttransplant. Subjects received tocilizumab (8 mg/kg IV every 4 weeks; 6 doses; n = 16) or no treatment (controls; n = 14) on top of usual maintenance immunosuppression. Kidney biopsies pre- and post-treatment were analyzed using Banff criteria. Blood was analyzed for serum cytokines, Treg frequencies, and T cell effector molecule expression (IFN-γ, IL-17, granzyme B) post-stimulation ex vivo. Tocilizumab-treated subjects were more likely to show improved Banff ti-score (62.5% vs. 21.4%, p = .03), increased Treg frequency (7.1% ± 5.55% vs. 3.6% ± 1.7%, p = .0168), and a blunted Teff cytokine response compared to controls. Changes in Banff i- and t-scores were not significantly different. The treatment was relatively well tolerated with no patient deaths or graft loss. Blockade of IL-6 is a novel and promising treatment option to regulate the T cell alloimmune response in kidney transplant recipients. NCT02108600.

Nephrotoxicity of calcineurin inhibitors as a risk factor for BK polyomavirus replication after kidney transplantation.

BK polyomavirus-associated nephropathy (PyVAN) is responsible for a significant percentage of transplanted kidneys prematurely terminating their function. Its occurrence is closely related to the intensity of immunosuppressive therapy. In a group of 161 newly transplanted patients, we prospectively evaluated 457 protocol renal biopsies performed within the first year after transplantation. Using the calcineurin inhibitors (CI) nephrotoxicity score, the incidence of nephrotoxicity was monitored as a manifestation of excessive immunosuppression. Findings were correlated with clinical evidence of active BK polyomavirus (BKPyV) replication and PyVAN. Compared to the normal histology, nephrotoxicity was associated with more frequent BKPyV viremia and viruria (p = .01 and p < .01, respectively) and more common occurrence of PyVAN. The persistence of toxicity in the subsequent biopsy proved to be a negative risk factor of viremia and viruria (p = .03 and p < .01, respectively), independently of the initial BKPyV status. Toxicity could also be used as a predictor of viremia and viruria (p = .04 and p < .01, respectively) even in the absence of viral replication at the time of initial biopsy. The early histological manifestation of CI nephrotoxicity was associated with significant BKPyV reactivation in the risky first posttransplant year.

Serum Mac-2 binding protein glycosylation isomer as a biomarker of fibrosis in living donor liver transplant graft.

INTRODUCTION: Non-invasive assessment of graft fibrosis is important in liver transplantation. Mac-2 binding protein glycosylation isomer (M2BPGi) has been reported as a diagnostic marker for this purpose, and thus, this predictive ability of M2BPGi was assessed in this study. PATIENTS AND METHODS: In this retrospective study, 236 patients who received living donor liver transplantation (LDLT) from August 1997 to March 2017 were enrolled. Among them, 94 biopsy patients were analyzed. Further, the predictive ability of fibrotic biopsy using M2BPGi, Fibroscan, and Fib-4 index was compared. RESULTS: Of 94 LDLT patients (53 men, 41 women), the median ages of recipients and donors were 57.5 and 33.0 years, respectively. The median M2BPGi values in patients with F0 (n = 11), F1 (n = 38), F2 (n = 35), and F3/4 (n = 10) were 0.680, 0.760, 1.240, and 4.110 COI, respectively. There were significant correlations between the fibrotic stage and M2BPGi levels (Kruskal-Wallis test, P < .0001). The area under the ROC curve for the diagnosis of F ≥ 2 in M2BPGi was 0.778, which was superior to Fibroscan (0.701) and Fib-4 index (0.639). CONCLUSION: M2BPGi is an accurate, non-invasive detection method for significant fibrosis after LDLT.

Two-year protocol biopsy after kidney transplantation in clinically stable recipients - a retrospective study.

The idea of protocol biopsy is to detect subclinical pathologies, including rejection, recurrent disease, or infection for early intervention and adjustment of immunosuppressants. Nevertheless, it is not adopted by most clinicians because of its low yield rate and uncertain long-term benefits. This retrospective study evaluated the impact of protocol biopsy on renal function and allograft survival. A two-year protocol biopsy was proposed for 190 stable patients; 68 of them accepted [protocol biopsy (PB) group], while 122 did not [nonprotocol biopsy (NPB) group]. The rejection diagnosis was made in 13 patients by protocol biopsy, and 11 of them had borderline rejection. In the following 5 years, graft survival was better in the PB group than in the NPB group (P = 0.0143). A total of 4 and 17 patients in the PB and NPB groups, respectively, had rejection events proven by indication biopsy. Renal function was better preserved in the PB group than in the NPB group (P = 0.0107) for patients with rejection events. Nevertheless, the survival benefit disappeared by a longer follow-up period (12-year, P = 0.2886). In conclusion, 2-year protocol biopsy detects subclinical pathological changes in rejection and preserves renal function by early intervention so as to prolong graft survival within 5 years.

Early surveillance biopsy utilization and management of pediatric renal allograft acute T cell-mediated rejection in Canadian centers: Observations from the PROBE multicenter cohort study.

BACKGROUND: Early TCMR surveillance with protocol kidney biopsy is used differentially among pediatric kidney transplant centers. Little has been reported about actual center-based differences, and this variability may influence TCMR ascertainment, treatment, and monitoring more broadly. METHODS: Data from the PROBE multicenter study were used to identify patients from centers conducting ESB or LSIB. ESB was defined as >50% of patients having at least 1 surveillance biopsy in the first 9 months. Patients were compared for number of biopsies, rejection episodes, treatment, and follow-up monitoring. RESULTS: A total of 261 biopsies were performed on 97 patients over 1-2 years of follow-up. A total of 228 (87%) of biopsies were performed in ESB centers. Compared to LSIB centers, ESB centers had 7-fold more episodes of TCMR diagnosed on any biopsy [0.8 ± 1.2 vs 0.1 ± 0.4; P < .001] and a 3-fold higher rate from indication biopsies [0.3 ± 0.9 vs 0.1 ± 0.3; P = .04]. The proportion of rejection treatment varied based on severity: Banff borderline i1t1 (40%);>i1t1 and < Banff 1A (86%); and ≥ Banff 1A (100%). Biopsies for follow-up were performed after treatment in 80% of cases (n = 28) of rejection almost exclusively at ESB centers, with 17 (61%) showing persistence of TCMR (≥i1t1). CONCLUSIONS: Practice variation exists across Canadian pediatric renal transplant centers with ESB centers identifying more episodes of rejection. Additionally, treatment of Banff borderline is not universal and varies with severity regardless of center type. Lastly, follow-up biopsies are performed inconsistently and invariably show persistence of rejection.

Recurrence of DNAJB9-Positive Fibrillary Glomerulonephritis After Kidney Transplantation: A Case Series.

RATIONALE & OBJECTIVE: Fibrillary glomerulonephritis (FGN) is a rare glomerular disease that often progresses to kidney failure requiring kidney replacement therapy. We have recently identified a novel biomarker of FGN, DnaJ homolog subfamily B member 9 (DNAJB9). In this study, we used sequential protocol allograft biopsies and DNAJB9 staining to help characterize a series of patients with native kidney FGN who underwent kidney transplantation. STUDY DESIGN: Case series. SETTING & PARTICIPANTS: Between 1996 and 2016, kidney transplantation was performed on 19 patients with a reported diagnosis of FGN in their native/transplant kidneys. Using standard diagnostic criteria and DNAJB9 staining, we excluded 5 patients (4 atypical cases diagnosed as possible FGN and 1 donor-derived FGN). Protocol allograft biopsies had been performed at 4, 12, 24, 60, and 120 months posttransplantation. DNAJB9 immunohistochemistry was performed using an anti-DNAJB9 rabbit polyclonal antibody. Pre- and posttransplantation demographic and clinical characteristics were collected. Summary statistical analysis was performed, including nonparametric statistical tests. OBSERVATIONS: The 14 patients with FGN had a median posttransplantation follow-up of 5.7 (IQR, 2.9-13.8) years. 3 (21%) patients had recurrence of FGN, detected on the 5- (n=1) and 10-year (n=2) allograft biopsies. Median time to recurrence was 10.2 (IQR, 5-10.5) years. Median levels of proteinuria and iothalamate clearance at the time of recurrence were 243mg/d and 56mL/min. The remaining 11 patients had no evidence of histologic recurrence on the last posttransplantation biopsy, although the median time of follow-up was significantly less at 4.4 (IQR, 2.9-14.4) years. 3 (21%) patients had a monoclonal protein detectable in serum obtained pretransplantation; none of these patients had recurrent FGN. LIMITATIONS: Small study sample and shorter follow-up time in the nonrecurrent versus recurrent group. CONCLUSIONS: In this series, FGN had an indolent course in the kidney allograft in that detectable histologic recurrence did not appear for at least 5 years posttransplantation.

Anti-Hla donor-specific antibody monitoring in pancreas transplantation: Role of protocol biopsies.

In kidney transplantation, de novo donor-specific antibodies (DSA) correlate with poor graft survival, and Consensus Guidelines recommend a protocol biopsy. In pancreas transplantation, DSA are also associated with poor graft outcomes; however, there are no recommendations on protocol biopsies. We started an antibody screening protocol on pancreas transplant patients at 0, 3, 6, 12 months, and yearly. Patients with DSA or high MFI non-DSA were considered for protocol biopsies of both organs. Results: 143 pancreas recipients were screened. 84 patients had negative antibodies throughout the study, 11 patients were found to have antibodies at graft dysfunction, and 48 patients had positive antibodies at screening without acute organ dysfunction (study group). Among the 30 non-DSA patients, 9 had protocol simultaneous pancreas and kidney biopsies performed with negative results in all of them. In contrast, among the 18 DSA patients, 15 had these biopsies performed, and 47% presented with subclinical rejection of the kidney, the pancreas, or both. In addition, some of the DSA patients without a protocol biopsy presented with rejection during the first 15 months of follow-up. Conclusion: We conclude that protocol biopsies of both grafts may play a role in the follow-up of pancreas transplant patients with de novo DSA appearance.

Modeling graft loss in patients with donor-specific antibody at baseline using the Birmingham-Mayo (BirMay) predictor: Implications for clinical trials.

Predicting which renal allografts will fail and the likely cause of failure is important in clinical trial design to either enrich patient populations to be or as surrogate efficacy endpoints for trials aimed at improving long-term graft survival. This study tests our previous Birmingham-Mayo model (termed the BirMay Predictor) developed in a low-risk kidney transplant population in order to predict the outcome of patients with donor specific alloantibody (DSA) at the time of transplantation and identify new factors to improve graft loss prediction in DSA+ patients. We wanted define ways to enrich the population for future therapeutic intervention trials. The discovery set included 147 patients from Mayo Cohort and the validation set included 111 patients from the Paris Cohort-all of whom had DSA at the time of transplantation. The BirMay predictor performed well predicting 5-year outcome well in DSA+ patients (Mayo C statistic = 0.784 and Paris C statistic = 0.860). Developing a new model did not improve on this performance. A high negative predictive value of greater than 90% in both cohorts excluded allografts not destined to fail within 5 years. We conclude that graft-survival models including histology predict graft loss well, both in DSA+ cohorts as well as DSA- patients.