A multicentre, patient- and assessor-blinded, non-inferiority, randomised and controlled phase II trial to compare standard and torque teno virus-guided immunosuppression in kidney transplant recipients in the first year after transplantation: TTVguideIT.

BACKGROUND: Immunosuppression after kidney transplantation is mainly guided via plasma tacrolimus trough level, which cannot sufficiently predict allograft rejection and infection. The plasma load of the non-pathogenic and highly prevalent torque teno virus (TTV) is associated with the immunosuppression of its host. Non-interventional studies suggest the use of TTV load to predict allograft rejection and infection. The primary objective of the current trial is to demonstrate the safety, tolerability and preliminary efficacy of TTV-guided immunosuppression. METHODS: For this purpose, a randomised, controlled, interventional, two-arm, non-inferiority, patient- and assessor-blinded, investigator-driven phase II trial was designed. A total of 260 stable, low-immunological-risk adult recipients of a kidney graft with tacrolimus-based immunosuppression and TTV infection after month 3 post-transplantation will be recruited in 13 academic centres in six European countries. Subjects will be randomised in a 1:1 ratio (allocation concealment) to receive tacrolimus either guided by TTV load or according to the local centre standard for 9 months. The primary composite endpoint includes the occurrence of infections, biopsy-proven allograft rejection, graft loss, or death. The main secondary endpoints include estimated glomerular filtration rate, graft rejection detected by protocol biopsy at month 12 post-transplantation (including molecular microscopy), development of de novo donor-specific antibodies, health-related quality of life, and drug adherence. In parallel, a comprehensive biobank will be established including plasma, serum, urine and whole blood. The date of the first enrolment was August 2022 and the planned end is April 2025. DISCUSSION: The assessment of individual kidney transplant recipient immune function might enable clinicians to personalise immunosuppression, thereby reducing infection and rejection. Moreover, the trial might act as a proof of principle for TTV-guided immunosuppression and thus pave the way for broader clinical applications, including as guidance for immune modulators or disease-modifying agents. TRIAL REGISTRATION: EU CT-Number: 2022-500024-30-00.

Alterations in the Kynurenine-Tryptophan Pathway and Lipid Dysregulation Are Preserved Features of COVID-19 in Hemodialysis.

Coronavirus disease 2019 (COVID-19)-induced metabolic alterations have been proposed as a source for prognostic biomarkers and may harbor potential for therapeutic exploitation. However, the metabolic impact of COVID-19 in hemodialysis (HD), a setting of profound a priori alterations, remains unstudied. To evaluate potential COVID-19 biomarkers in end-stage kidney disease (CKD G5), we analyzed the plasma metabolites in different COVID-19 stages in patients with or without HD. We recruited 18 and 9 asymptomatic and mild, 11 and 11 moderate, 2 and 13 severely affected, and 10 and 6 uninfected HD and non-HD patients, respectively. Plasma samples were taken at the time of diagnosis and/or upon admission to the hospital and analyzed by targeted metabolomics and cytokine/chemokine profiling. Targeted metabolomics confirmed stage-dependent alterations of the metabolome in non-HD patients with COVID-19, which were less pronounced in HD patients. Elevated kynurenine levels and lipid dysregulation, shown by an increase in circulating free fatty acids and a decrease in lysophospholipids, could distinguish patients with moderate COVID-19 from non-infected individuals in both groups. Kynurenine and lipid alterations were also associated with ICAM-1 and IL-15 levels in HD and non-HD patients. Our findings support the kynurenine pathway and plasma lipids as universal biomarkers of moderate and severe COVID-19 independent of kidney function.

Same But Different? Covid-19 Metabolome in Hemodialysis

BACKGROUND AND AIMS The ongoing coronavirus disease 2019 (COVID-19) pandemic presents a major health and economical challenge. Chronic kidney disease (CKD) patients on haemodialysis (HDp) are at a particularly high risk of severe and fatal courses [1]. The COVID-19 metabolome is distinct [2] and may harbour potential prognostic markers and therapeutic targets. However, the metabolome in SARS-CoV-2 infected HDp remains unstudied. METHOD Untargeted and targeted metabolomics via high-performance liquid chromatography and tandem mass spectrometry of EDTA-plasma were performed in 39 individuals without CKD (non-HDp) and 41 HDp. Individuals were further grouped according to COVID-19 disease status and severity: negative, asymptomatic/mild (no or mild symptoms) and moderate/severe (requiring hospitalization). RESULTS Principal component analysis shows a clear separation of non-HDp and HDp alongside PC2, independent of COVID-19. Non-HDp with moderate/severe courses are shifted to the right of PC1. The influence of COVID-19 is less pronounced in HDp (Figure 1). Free fatty acids are main contributors to PC1, whereas PC2 reflects the complex metabolic disarray as seen in uraemia (Table 1). FIGURE 1: Principal component analysis of non-HDp and HDp without COVID-19 and with asymptomatic/mild or moderate/severe COVID-19.Table 1. Top 10 metabolites contributing to PC1 and PC2PC1PC2FFA C16:2 (Palmitolinoleic acid)CytidineFFA C20:2 (Eicosadienoic acid)CreatinineFFA C17:1 (Heptadecenoic acid)Gluconic acidFFA C16:0 (Palmitic acid)Glucuronic acidFFA C19:1 (Nonadecenoic acid)OrotidineFFA C20:1 (Eicosenoic acid)MethylhistidineFFA C22:4 (Adrenic acid)ADMAFFA C18:1 (Oleic acid)TryptophanFFA C22:5 (Docosapentaenoic acid)TrehaloseFFA C16:3 (Hiragonic acid)Lactose CONCLUSION Our data underlines the fundamental metabolic differences between non-HDp and HDp [3]. Furthermore, moderate/severe COVID-19 leads to a distinct metabolite signature in non-HDp. This effect is less pronounced in HDp, which could be indicative of a decreased capability to adapt to infectious challenges. In summary, these findings warrant caution when extrapolating COVID-19 metabolomics from otherwise healthy individuals, as the validity of prognostic markers and/or effectiveness of therapeutic approaches based on the metabolome may be limited in HDp.

Chronic Inflammation Might Protect Haemodialysis Patients from Severe COVID-19

BACKGROUND AND AIMS Patients on haemodialysis (HD) are expected to have excess mortality in coronavirus disease 2019 (COVID-19). This was challenged by a recent study reporting HD patients to have comparable mortality and decreased ICU admissions when hospitalized with COVID-19. It was speculated that an altered immune system due to chronic inflammation might protect HD patients from severe COVID-19. Therefore, we designed a study to describe the peripheral blood immune phenotype in HD patients and respective controls with COVID-19. METHOD Sixty-four patients (31 HD, 33 non-HD) with PCR-confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and 16 control patients (10 HD, 6 non-HD) were prospectively included. According to symptoms, COVID-19 patients were categorized as asymptomatic/mild and moderate/severe COVID-19 phenotypes. Cytokine profiling and immune phenotyping were performed. RESULTS Th1 and Th17 plasma cytokine levels were highly increased in HD patients without SARS-CoV-2 infection and were not significantly regulated during COVID-19. In non-HD COVID-19 patients, these cytokines increased significantly with disease severity. While all patients with moderate/severe COVID-19 showed hallmarks of COVID-19 such as decreased CD3+ CD4+ and CD8+ and CD4+CD25hiFoxP3+ regulatory T cells, significantly increased CD38+CD8+ effector memory and CD38+CD8+ TEMRA T cells were detected in HD compared to non-HD patients with moderate/severe COVID-19. Furthermore, CD161+CD8+ T cells decreased significantly in non-HD COVID-19 patients dependent on disease severity, but not in HD patients. Dynamics of B cells and subtypes were comparable in HD and non-HD COVID-19 patients. Significantly fewer moderate/severe COVID-19 HD patients needed ICU treatment [1/13 (7.7%) HD, 12/24 (50%) non-HD], whereas no difference in mortality was observed [4/31 (12.9%) HD, 6/33 non-HD (18.2%)]. CONCLUSION HD patients might be protected from severe COVID-19 due to their chronic inflammatory state with increased CD38+CD8+ effector memory and TEMRA T cells as well as CD161+CD8+ T cells.

ScoMorphoFISH: A deep learning enabled toolbox for single-cell single-mRNA quantification and correlative (ultra-)morphometry.

Increasing the information depth of single kidney biopsies can improve diagnostic precision, personalized medicine and accelerate basic kidney research. Until now, information on mRNA abundance and morphologic analysis has been obtained from different samples, missing out on the spatial context and single-cell correlation of findings. Herein, we present scoMorphoFISH, a modular toolbox to obtain spatial single-cell single-mRNA expression data from routinely generated kidney biopsies. Deep learning was used to virtually dissect tissue sections in tissue compartments and cell types to which single-cell expression data were assigned. Furthermore, we show correlative and spatial single-cell expression quantification with super-resolved podocyte foot process morphometry. In contrast to bulk analysis methods, this approach will help to identify local transcription changes even in less frequent kidney cell types on a spatial single-cell level with single-mRNA resolution. Using this method, we demonstrate that ACE2 can be locally upregulated in podocytes upon injury. In a patient suffering from COVID-19-associated collapsing FSGS, ACE2 expression levels were correlated with intracellular SARS-CoV-2 abundance. As this method performs well with standard formalin-fixed paraffin-embedded samples and we provide pretrained deep learning networks embedded in a comprehensive image analysis workflow, this method can be applied immediately in a variety of settings.

B Cell Composition Is Altered After Kidney Transplantation and Transitional B Cells Correlate With SARS-CoV-2 Vaccination Response.

BACKGROUND: The COVID-19 pandemic has major implications on kidney transplant recipients (KTRs) since they show increased mortality due to impaired immune responses to SARS-CoV-2 infection and a reduced efficacy of SARS-CoV-2 vaccination. Surprisingly, dialysis patients have shown superior seroconversion rates after vaccination compared to KTRs. Therefore, we investigated peripheral blood B cell (BC) composition before and after kidney transplantation (KT) and aimed to screen the BC compartment to explain impaired antibody generation. METHODS: A total of 105 patients were recruited, and multicolor flow cytometric phenotyping of peripheral venous blood BC subpopulations was performed before and 1 year after KT. Complete follow-up was available for 71 individuals. Anti-SARS-CoV-2 antibodies were collected retrospectively and were available for 40 subjects, who had received two doses of an mRNA-based vaccine (BNT162b2 or mRNA-1273). RESULTS: Overall, relative BC frequencies within lymphocytes decreased, and their absolute counts trended in the same direction 1 year after KT as compared to CKD G5 patients. Frequencies and absolute numbers of naïve BCs remained stable. Frequencies of double negative BCs, a heterogeneous subpopulation of antigen experienced BCs lacking CD27 expression, were increased after KT, yet their absolute counts were similar at both time points. Transitional BCs (TrBCs) and plasmablasts were significantly reduced after KT in absolute and relative terms. Memory BCs were affected differently since class-switched and IgM-only subsets decreased after KT, but unswitched and IgD-only memory BCs remained unchanged. CD86+ and CD5+ expression on BCs was downregulated after KT. Correlational analysis revealed that TrBCs were the only subset to correlate with titer levels after SARS-CoV-2 vaccination. Responders showed higher TrBCs, both absolute and relative, than non-responders. CONCLUSION: Together, after 1 year, KTRs showed persistent and profound compositional changes within the BC compartment. Low TrBCs, 1 year after KT, may account for the low serological response to SARS-CoV-2 vaccination in KTRs compared to dialysis patients. Our findings need confirmation in further studies as they may guide vaccination strategies.

The basement membrane in the cross-roads between the lung and kidney.

The basement membrane (BM) is a specialized layer of extracellular matrix components that plays a central role in maintaining lung and kidney functions. Although the composition of the BM is usually tissue specific, the lung and the kidney preferentially use similar BM components. Unsurprisingly, diseases with BM defects often have severe pulmonary or renal manifestations, sometimes both. Excessive remodeling of the BM, which is a hallmark of both inflammatory and fibrosing diseases in the lung and the kidney, can lead to the release of BM-derived matrikines, proteolytic fragments with distinct biological functions. These matrikines can then influence disease activity at the site of liberation. However, they are also released to the circulation, where they can directly affect the vascular endothelium or target other organs, leading to extrapulmonary or extrarenal manifestations. In this review, we will summarize the current knowledge of the composition and function of the BM and its matrikines in health and disease, both in the lung and in the kidney. By comparison, we will highlight, why the BM and its matrikines may be central in establishing a renal-pulmonary interaction axis.

Evaluation of Endothelial Dysfunction and Inflammatory Vasculopathy After SARS-CoV-2 Infection-A Cross-Sectional Study.

Background: Rising data suggest that COVID-19 affects vascular endothelium while the underlying mechanisms promoting COVID-19-associated endothelial dysfunction and inflammatory vasculopathy are largely unknown. The aim was to evaluate the contribution of COVID-19 to persisting vascular injury and to identify parameters linked to COVID-19-associated endothelial dysfunction and inflammatory vasculopathy. Methods: In a cross-sectional design, flow-mediated dilation (FMD), nitroglycerine-related dilation (NMD), pulse-wave velocity (PWV), augmentation index, intima-media thickness (IMT), compounds of the arginine and kynurenine metabolism, homocysteine, von Willebrand factor (vWF), endothelial microparticles (EMP), antiendothelial cell antibodies, inflammatory, and immunological parameters, as well as nailfold capillary morphology were measured in post-COVID-19 patients, patients with atherosclerotic cardiovascular diseases (ASCVD) and healthy controls without prior or recent SARS-CoV-2 infection. Results: Post-COVID-19 patients had higher values of PWV, augmentation index, IMT, asymmetric and symmetric dimethylarginine, vWF, homocysteine, CD31+/CD42b- EMP, C-reactive protein, erythrocyte sedimentation rate, interleukin-6, and ß-2-glycoprotein antibodies as well as lower levels of homoarginine and tryptophan compared to healthy controls (all with p < 0.05). A higher total number of pathologically altered inflammatory conditions and higher rates of capillary ramifications, loss, caliber variability, elongations and bushy capillaries with an overall higher microangiopathy evolution score were also observed in post-COVID-19 patients (all with p < 0.05). Most parameters of endothelial dysfunction and inflammation were comparably altered in post-COVID-19 patients and patients with ASCVD, including FMD and NMD. Conclusion: COVID-19 may affect arterial stiffness, capillary morphology, EMP and selected parameters of arginine, kynurenine and homocysteine metabolism as well as of inflammation contributing to COVID-19-associated endothelial dysfunction and inflammatory vasculopathy.

Immunologically relevant aspects of the new COVID-19 vaccines-an ÖGAI (Austrian Society for Allergology and Immunology) and AeDA (German Society for Applied Allergology) position paper.

BACKGROUND: The vaccines against the coronavirus disease 2019 (COVID-19) approved in the European Union represent a decisive step in the fight against the pandemic. The application of these available vaccines to patients with pre-existing immunological conditions leads to a multitude of questions regarding efficacy, side effects and the necessary patient information. RESULTS: This review article provides insight into mechanisms of action of the currently available severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines and summarises the current state of science as well as expert recommendations regarding tolerability of the vaccines. In addition, the potential to develop protective immune responses is determined. A special focus is given on patients under immunosuppression or in treatment with immunomodulatory drugs. Special groups of the population such as children, pregnant women and the elderly are also considered. CONCLUSION: Despite the need for a patient-specific risk-benefit assessment, the consensus among experts is that patients with immunological diseases in particular benefit from the induced immune protection after COVID-19 vaccination and do not have an increased risk of side effects.