Role of Urinary Biomarkers in RWE Clinical Paradigm

Purpose: Due to heterogeneity observed in the kidney transplant population, it has been extremely challenging for traditional methods such as histopathology to predict graft outcomes. In this real-world evidence(RWE) study, we applied machine learning (ML) models to a multi-analyte urinary biomarker assay to predict whether a kidney allograft would experience a rejection episode. Method(s): A cohort of 550 (37.5% biopsy matched) urine samples from patients across 3 renal transplant centers were used to develop a predictive ML model (scaled 0-100) to prognosticate allograft failure. Samples were collected between 1-1539 days post-transplant from allograft recipients with ages ranging from 7-77 years. Of the 206 biopsy matched samples, acute kidney allograft rejection (AR) and no-rejection (NR) phenotypes were confirmed in 136 and 70 respectively. We also evaluated the developed ML model on two additional cohorts of 15 COVID+ transplant recipients and 30 non-transplant healthy population. The ML model incorporates clinico-demographics with 6 urinary biomarkers: Clusterin, total protein, CXCL10, Creatinine, cfDNA and methylated cfDNA. Monte Carlo confidence intervals for the model incorporated biomarker assay and sample variances. Result(s): The novel rejection score was able to discriminate AR from NR efficiently. Score below 32 classified stable allograft, score range of 32 - 55 identified progression of AR, and Score > 55 identified AR with high sensitivity: 92%, and specificity: 89%;AUC: 96% and accuracy: 91%(figure). The associated NPV and PPV of 87% and 93% respectively. In the COVID cohort with 86% clinician assessed rejection, the median score was 51(IQR:30-87). In the non-transplants the median score was 19(IQR:13-26). It was established that presence of COVID was not a confounder in the model. Conclusion(s): The accuracy of the novel rejection score emphasizes the promise of applying ML algorithms as an aid to decision-making in evaluating graft outcomes with high sensitivity and specificity. Moreover, this RWE retrospective analysis demonstrates the efficacy of the urine multi-analyte approach to accurately predict acute rejection in kidney transplant recipients. (Figure Presented).

Beyond GWAS-Could Genetic Differentiation within the Allograft Rejection Pathway Shape Natural Immunity to COVID-19?

COVID-19 infections pose a serious global health concern so it is crucial to identify the biomarkers for the susceptibility to and resistance against this disease that could help in a rapid risk assessment and reliable decisions being made on patients' treatment and their potential hospitalisation. Several studies investigated the factors associated with severe COVID-19 outcomes that can be either environmental, population based, or genetic. It was demonstrated that the genetics of the host plays an important role in the various immune responses and, therefore, there are different clinical presentations of COVID-19 infection. In this study, we aimed to use variant descriptive statistics from GWAS (Genome-Wide Association Study) and variant genomic annotations to identify metabolic pathways that are associated with a severe COVID-19 infection as well as pathways related to resistance to COVID-19. For this purpose, we applied a custom-designed mixed linear model implemented into custom-written software. Our analysis of more than 12.5 million SNPs did not indicate any pathway that was significant for a severe COVID-19 infection. However, the Allograft rejection pathway (hsa05330) was significant (p = 0.01087) for resistance to the infection. The majority of the 27 SNP marking genes constituting the Allograft rejection pathway were located on chromosome 6 (19 SNPs) and the remainder were mapped to chromosomes 2, 3, 10, 12, 20, and X. This pathway comprises several immune system components crucial for the self versus non-self recognition, but also the components of antiviral immunity. Our study demonstrated that not only single variants are important for resistance to COVID-19, but also the cumulative impact of several SNPs within the same pathway matters.

Chronic Inflammatory Placental Disorders Associated With Recurrent Adverse Pregnancy Outcome.

Chronic inflammatory placental disorders are a group of rare but devastating gestational syndromes associated with adverse pregnancy outcome. This review focuses on three related conditions: villitis of unknown etiology (VUE), chronic histiocytic intervillositis (CHI) and massive perivillous fibrin deposition (MPFD). The hallmark of these disorders is infiltration of the placental architecture by maternal immune cells and disruption of the intervillous space, where gas exchange between the mother and fetus occurs. Currently, they can only be detected through histopathological examination of the placenta after a pregnancy has ended. All three are associated with a significant risk of recurrence in subsequent pregnancies. Villitis of unknown etiology is characterised by a destructive infiltrate of maternal CD8+ T lymphocytes invading into the chorionic villi, combined with activation of fetal villous macrophages. The diagnosis can only be made when an infectious aetiology has been excluded. VUE becomes more common as pregnancy progresses and is frequently seen with normal pregnancy outcome. However, severe early-onset villitis is usually associated with fetal growth restriction and recurrent pregnancy loss. Chronic histiocytic intervillositis is characterised by excessive accumulation of maternal CD68+ histiocytes in the intervillous space. It is associated with a wide spectrum of adverse pregnancy outcomes including high rates of first-trimester miscarriage, severe fetal growth restriction and late intrauterine fetal death. Intervillous histiocytes can also accumulate due to infection, including SARS-CoV-2, although this infection-induced intervillositis does not appear to recur. As with VUE, the diagnosis of CHI requires exclusion of an infectious cause. Women with recurrent CHI and their families are predisposed to autoimmune diseases, suggesting CHI may have an alloimmune pathology. This observation has driven attempts to prevent CHI with a wide range of maternal immunosuppression. Massive perivillous fibrin deposition is diagnosed when >25% of the intervillous space is occupied by fibrin, and is associated with fetal growth restriction and late intrauterine fetal death. Although not an inflammatory disorder per se, MPFD is frequently seen in association with both VUE and CHI. This review summarises current understanding of the prevalence, diagnostic features, clinical consequences, immune pathology and potential prophylaxis against recurrence in these three chronic inflammatory placental syndromes.

Collateral Effects and Mortality of Kidney Transplant Recipients during the COVID-19 Pandemic.

Background: Collateral effects and consequences of the coronavirus disease 19 (COVID-19) pandemic on kidney transplant recipients remain widely unknown. Methods: This retrospective cohort study examined changes in admission rates, incidences of diseases leading to hospitalization, in-patient procedures, and maintenance medication in long-term kidney transplant recipients with functioning graft during the early COVID-19 pandemic in Germany. Data were derived from a nationwide health insurance database. Analysis was performed from March 15 to September 30 and compared the years 2019 and 2020. Effects on mortality and adverse allograft events were compared with COVID-19-attributed effects. Results: A total of 7725 patients were included in the final analysis. Admissions declined in 2020 by 17%, with the main dip during a 3-month lockdown (-31%) but without a subsequent rebound. Incidences for hospitalization did not increase for any investigated disease entities, whereas decreasing trends were noted for non-COVID-19 pulmonary and urogenital infections (incidence rate ratio 0.8, 95% CI, 0.62 to 1.03, and 0.82, 95% CI, 0.65 to 1.04, respectively). Non-COVID-19 hospital stays were 0.6 days shorter (P=0.03) and not complicated by increased dialysis, ventilation, or intensive care treatment rates. In-hospital and 90-day mortality remained stable. Incidences of severe COVID-19 requiring hospitalization was 0.09 per 1000 patient-days, and in-hospital mortality was 9%. A third (31%) of patients with calcineurin-inhibitor medication and without being hospitalized for COVID-19 reduced doses by at least 25%, which was associated with an increased allograft rejection risk (adjusted hazard ratio 1.29, 95% CI, 1.02 to 1.63). COVID-19 caused 17% of all deaths but had no significant association with allograft rejections. All-cause mortality remained stable (incidence rate ratio 1.15, 95% CI, 0.91 to 1.46), also when restricting analysis to patients with no or outpatient-treated COVID-19 (0.97, 95% CI, 0.76 to 1.25). Conclusion: Despite significant collateral effects, mortality remained unchanged during the early COVID-19 pandemic. Considerable temporary reductions in admissions are safe, whereas reducing immunosuppression results in increased allograft rejection risk.

Occurrence of De novo Donor-Specific Antibodies After COVID-19 in Kidney Transplant Recipients Is Low Despite Immunosuppression Modulation.

Introduction: Decreased immunosuppression has been proposed for kidney transplant recipients infected with coronavirus disease 2019 (COVID-19), but the impact on the alloreactive immune response during and after infection has been poorly investigated. We evaluated the occurrence of antihuman leukocyte antigen (HLA) donor-specific antibodies (DSAs) (post-COVID-19) and rejection episodes after COVID-19 with particular focus on immunosuppression modulation. Methods: Kidney transplant recipients from 2 French institutions had anti-HLA antibody screening before and after COVID-19. Management of immunosuppression, rejection episodes, COVID-19 severity, inflammatory markers, and antiviral therapies were recorded. Results: From 251 recruited patients, 72 were excluded because of COVID-19-related death (n = 25) and incomplete immunologic follow-up (n = 47). Among the remaining 179 included patients, almost half were hospitalized (49.2%). Antimetabolites were interrupted in 47% of patients (82% in hospitalized, median time of resumption of 23 days and in 15% nonhospitalized, median time of resumption of 7 days). Calcineurin inhibitors were interrupted in 12% of patients (all hospitalized, median time of resumption of 11 days). The incidence of post-COVID-19 DSA was 4% (8% and 0% in hospitalized and nonhospitalized, respectively). Allograft rejection occurred in 3 patients (1.7%) and all were hospitalized. Younger age, transplantation <1 year, and preexisting DSA were more frequently observed in patients with post-COVID-19 DSA, whereas inflammatory markers, lymphopenia, and use of antiviral therapies were not. Conclusion: The incidence of post-COVID-19 DSA among COVID-19-positive kidney transplant recipients was low (4%) despite a significant decrease in immunosuppression and was mainly restricted to high-risk immunologic patient's status. COVID-19 severity was not associated with post-COVID-19 DSA and/or rejection.

Imaging Findings for Identifying and Evaluating Complications After Lung Transplantation in Patients with Advanced COVID-19: Two Case Reports.

BACKGROUND: Lung transplantation might be a viable alternative for patients with irreversible lung injury secondary to coronavirus disease 2019 (COVID-19). Here, we describe two patients with end-stage COVID-19 that received lung transplantations, the clinical-radiologic manifestations of postoperative complications, and the imaging features of allograft rejection. CASE PRESENTATION: In case 1, a 66-year-old woman presented severe hypoxia after lung transplantation. Chest imaging revealed diffuse homogeneous infiltration in the donor's lung. Dramatic resolution of the imaging abnormalities after intravenous administration of methylprednisolone favored a diagnosis of hyperacute rejection. The second is a 70-year-old man who was infected with bacterial postoperatively. During the empiric antibiotic therapy, chest CT showed newly developed groundglass opacities with septal thickening, suggesting a diagnosis of acute rejection. High-dose corticosteroids therapy was initiated, and the patient recovered gradually. CONCLUSION: This is the first report describing postoperative complications of lung transplantation in patients with advanced COVID-19. We presumed that imaging procedures could be a useful tool in early detecting lung transplant complications and selecting specific interventions for patients with COVID-19.

Immunosuppression minimization in kidney transplant recipients hospitalized for COVID-19.

BACKGROUND: Immunosuppressed patients such as kidney transplant recipients (KTs) have increased mortality risk in the setting of coronavirus disease 2019 (COVID-19). The role and management of chronic immunosuppressive therapies during COVID-19 must be characterized. METHODS: Herein, we report the follow-up of a cohort of 47 KTs admitted at two Spanish Kidney Transplant Units, who survived COVID-19. The impact of the management of immunosuppression during COVID-19 on graft function and immunologic events was evaluated. RESULTS: At least one immunosuppressive agent was withdrawn in 83% of patients, with antimetabolites being the most frequent. Steroids were generally not stopped and the dose was even increased in 15% of patients as part of the treatment of COVID-19. Although immunosuppressive drugs were suspended during a median time of 17 days, no rejection episodes or de novo donor-specific antibodies were observed up to 3 months after discharge, and no significant changes occurred in calculated panel reactive antibodies. Acute graft dysfunction was common (55%) and the severity was related to tacrolimus trough levels, which were higher in patients receiving antivirals. At the end of follow-up, all patients recovered baseline kidney function. CONCLUSIONS: Our observational study suggests that immunosuppression in KTs hospitalized due to COVID-19 could be safely minimized.

Practicing With Uncertainty: Kidney Transplantation During the COVID-19 Pandemic.

The coronavirus disease 2019 (COVID-19) pandemic required transplant nephrologists, surgeons, and care teams to make decisions about the full spectrum of transplant program operations and clinical practices in the absence of experience or data. Initially, across the country, there was a reduction in kidney transplant procedures and a striking pause in the conduct of living donation and living-donor transplant surgeries. Aspects of candidate evaluation and follow-up rapidly converted to telehealth. Months into the pandemic, much has been learned from experiences worldwide, yet many questions remain. In this Perspective, we reflect on some of the practice decisions made by the transplant community in the initial response to the pandemic and consider lessons learned, including those related to the risks, benefits, and logistical considerations of proceeding with versus delaying deceased-donor transplantation, living donation, and living-donor transplantation during the pandemic. We review the evolution of therapeutic strategies for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and their use in transplant recipients, current consensus related to immunosuppression management in infected transplant recipients, and emerging information on vaccination against SARS-CoV-2. We share our thoughts on research priorities, discuss the areas in which we are still practicing with uncertainty, and look ahead to the next phase of the pandemic response.