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Polyomaviruses are widespread, with BK viruses being most common in humans who require immunosuppression due to allotransplantation. Infection with BK polyomavirus (BKV) may manifest as BK virus-associated nephropathy and hemorrhagic cystitis. Established diagnostic methods include the detection of polyomavirus in urine and blood by PCR and in tissue biopsies via immunohistochemistry. In this study, 79 patients with pathological renal retention parameters and acute kidney injury (AKI) were screened for BK polyomavirus replication by RNA extraction, reverse transcription, and virus-specific qPCR in urine sediment cells. A short fragment of the VP2 coding region was the target of qPCR amplification; patients with (n = 31) and without (n = 48) a history of renal transplantation were included. Urine sediment cell immunofluorescence staining for VP1 BK polyomavirus protein was performed using confocal microscopy. In 22 patients with acute renal injury, urinary sediment cells from 11 participants with kidney transplantation (KTX) and from 11 non-kidney transplanted patients (nonKTX) were positive for BK virus replication. BK virus copies were found more frequently in patients with AKI stage III (n = 14). Higher copy numbers were detected in KTX patients having experienced BK polyoma-nephropathy (BKPyVAN) in the past or diagnosed recently by histology (5.6 × 10 9 -3.1 × 10 10 ). One patient developed BK viremia following delayed graft function (DGF) with BK virus-positive urine sediment. In nonKTX patients with BK copies, decoy cells were absent; however, positive staining of cells was found with epithelial morphology. Decoy cells were only found in KTX patients with BKPyVAN. In AKI, damage to the tubular epithelium itself may render the epithelial cells more permissive for polyoma replication. This non-invasive diagnostic approach to assess BK polyomavirus replication in urine sediment cells has the potential to identify KTX patients at risk for viremia and BKPyVAN during AKI. This method might serve as a valuable screening tool for close monitoring and tailored immunosuppression decisions.

All transplanted kidneys are subjected to some degree of injury as a result of the donation-implantation process and various post-transplant stresses such as rejection. Because transplants are frequently biopsied, they present an opportunity to explore the full spectrum of kidney response-to-wounding from all causes. Defining parenchymal damage in transplanted organs is important for clinical management because it determines function and survival. In this study, we classified the scenarios associated with parenchymal injury in genome-wide microarray results from 1,526 kidney transplant indication biopsies collected during the INTERCOMEX study. We defined injury groups by using archetypal analysis (AA) of scores for gene sets and classifiers previously identified in various injury states. Six groups and their characteristics were defined in this population: No injury, minor injury, two classes of acute kidney injury ("AKI," AKI1, and AKI2), chronic kidney disease (CKD), and CKD combined with AKI. We compared the two classes of AKI, namely, AKI1 and AKI2. AKI1 had a poor function and increased parenchymal dedifferentiation but minimal response-to-injury and inflammation, instead having increased expression of PARD3, a gene previously characterized as being related to epithelial polarity and adherens junctions. In contrast, AKI2 had a poor function and increased response-to-injury, significant inflammation, and increased macrophage activity. In random forest analysis, the most important predictors of function (estimated glomerular filtration rate) and graft loss were injury-based molecular scores, not rejection scores. AKI1 and AKI2 differed in 3-year graft survival, with better survival in the AKI2 group. Thus, injury archetype analysis of injury-induced gene expression shows new heterogeneity in kidney response-to-wounding, revealing AKI1, a class of early transplants with a poor function but minimal inflammation or response to injury, a deviant response characterized as PC3, and an increased risk of failure. Given the relationship between parenchymal injury and kidney survival, further characterization of the injury phenotypes in kidney transplants will be important for an improved understanding that could have implications for understanding native kidney diseases (ClinicalTrials.gov #NCT01299168)., Competing Interests: PH is a consultant to Natera, holds shares in Transcriptome Sciences Inc (TSI), a University of Alberta research company dedicated to developing molecular diagnostics, supported in part by a licensing agreement between TSI and Thermo Fisher, and by a research grant from Natera. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Halloran, Böhmig, Bromberg, Einecke, Eskandary, Gupta, Myslak, Viklicky, Perkowska-Ptasinska, Madill-Thomsen and the INTERCOMEX Investigators.)

Background: Drug-induced immunosuppression in kidney transplant recipients is crucial to prevent allograft rejection, but increases risk for infectious disease. Immunologic monitoring to tailor immunosuppressive drugs might prevent alloreactivity and adverse effects simultaneously. The apathogenic torque teno virus (TTV) reflects the immunocompetence of its host and might act as a potential candidate for a holistic monitoring., Methods: We screened all 1010 consecutive patients from the prospective Vienna Kidney Transplant Cohort Study for availability of allograft biopsies and adequately stored sera for TTV quantification by polymerase chain reaction., Results: Patients with acute biopsy-proven alloreactivity according to the Banff classification (n = 33) showed lower levels of TTV in the peripheral blood compared to patients without rejection (n = 80) at a median of 43 days before the biopsy. The risk for alloreactivity decreased by 10% per log level of TTV copies/mL (risk ratio, .90 [95% confidence interval, .84-.97]; P = .005). TTV levels >1 × 106 copies/mL exclude rejection with a sensitivity of 94%. Multivariable generalized linear modeling suggests an independent association between TTV level and alloreactivity., Conclusions: TTV is a prospective biomarker for risk stratification of acute biopsy-proven alloreactivity in kidney transplant recipients and might be a potential tool to tailor immunosuppressive drug therapy., (© The Author(s) 2019. Published by Oxford University Press for the Infectious Diseases Society of America.)

Background: The proportion of older donors and recipients is constantly rising in heart transplantation (HTX). The impact of age on different outcomes after HTX has been studied; however, effects of interaction between donor and recipient age remain elusive., Methods: This retrospective cohort study comprised 1,190 patients who underwent HTX between 1984 and 2011 at the Medical University Vienna. Multivariable models consisted of a basic set that included donor age, recipient age, and transplant eras and were adjusted for 2 sets of 6 possible confounders and 3 mediator variables. Cox models were used to estimate the risk of death. To search for age-related effects on the development of cardiac allograft vasculopathy (CAV), we applied cause-specific Cox models and proportional sub-distribution hazard models for competing risk data., Results: Survival was 80%, 77%, 69%, and 56% after 1, 2, 5, and 10 years, respectively. Donor age (hazard ratio [HR], 1.1; 95% confidence interval [CI], 1.0-1.2), recipient age (HR, 1.1; 95% CI, 1.0-1.2), admission from intensive care unit to HTX (HR, 1.5; 95% CI, 1.2-1.9), and diabetes (HR, 1.4; 95% CI, 1.1-1.7) were identified as significant independent risk factors for death. Significant risk factors for CAV were donor age (HR, 1.4; 95% CI, 1.3-1.5) and male recipient sex (HR, 1.5; 95% CI, 1.0-2.2). Recipient age was inversely associated with initiation of CAV (HR, 0.8; 95% CI, 0.8-1.0). Analysis of the interaction between donor and recipient age was not significant for death (p = 0.8) or CAV (p = 0.6)., Conclusions: We found no interaction between donor and recipient age negatively affecting mortality and CAV. The identified independent risk factors may have implications for allocation strategies in elderly recipients., (Copyright © 2014 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.)