Pre-Transplant Frequencies of FoxP3+CD25+ in CD3+CD8+ T Cells as Potential Predictors for CMV in CMV-Intermediate Risk Kidney Transplant Recipients.

Cytomegalovirus (CMV) infection detrimentally influences graft survival in kidney transplant recipients, with the risk primarily determined by recipient and donor serostatus. However, recipient CD8+ T cells play a crucial role in CMV control. The optimal preventive strategy (prophylaxis vs. pre-emptive treatment), particularly for seropositive (intermediate risk) recipients, remains uncertain. We investigated CD8+ T cell subpopulation dynamics and CMV occurrence (DNAemia ≥ 100 IU/mL) in 65 kidney transplant recipients, collecting peripheral blood mononuclear cells before (T1) and 1 year after transplantation (T2). Comparing the two timepoints, we found an increase in granulocyte, monocyte and CD3+CD8+ T cells numbers, while FoxP3+CD25+, LAG-3+ and PD-1+ frequencies were reduced at T2. CMV DNAemia occurred in 33 recipients (55.8%) during the first year. Intermediate risk patients were disproportionally affected by posttransplant CMV (N = 29/45, 64.4%). Intermediate risk recipients developing CMV after transplantation exhibited lower leukocyte, monocyte, and granulocyte counts and higher FoxP3+CD25+ frequencies in CD3+CD8+ T cells pre-transplantation compared to patients staying CMV negative. Pre-transplant FoxP3+CD25+ in CD3+CD8+ T cells had the best discriminatory potential for CMV infection prediction within the first year after transplantation (AUC: 0.746). The FoxP3+CD25+ CD3+CD8+ T cell subset may aid in selecting intermediate risk kidney transplant recipients for CMV prophylaxis.

Vaccination acceptance and its associated factors in patients on hemodialysis in Austria: A nationwide survey.

BACKGROUND: Vaccines are essential in disease prevention among patients on chronic hemodialysis (HD). However, during the coronavirus disease 2019 pandemic, there has been an increased rate of vaccination hesitancy. A better understanding of patients' opinions may help identify a more targeted approach to increase vaccination rates. MATERIALS AND METHODS: Questionnaires with 43 questions based on the recommendations of the Strategic Advisory Group of Experts (SAGE) on Immunization Working Group on Vaccine Hesitancy were administered to patients during routine HD sessions at different dialysis centers in Austria. RESULTS: In total, 347 patients participated in this study. Approximately 81% of the patients were aged > 54 years, and 65% were men. Further, 53% of patients were receiving HD from private units. In ~ 72% of patients, the dialysis physicians were the source of vaccination information. Meanwhile, the source of information in 28% of patients was the primary care physician (28%), and 18% of patients obtained vaccination details from the internet. The number of younger (aged < 55 years) patients who were more likely to use online content as the main source of information was significantly higher than that of older patients (32 vs. 15%, p = 0.001). Furthermore, the number of older patients who wanted to receive more information from the dialysis physician was significantly higher than that of younger patients (57 vs. 38%, p = 0.009). Only 65% of patients had a good understanding of the mechanisms of action of vaccines. The younger population (aged 18 - 54 years) had a higher number of individuals with a good understanding of vaccine mechanisms than the older population (78 vs. 62%, p = 0.016). Moreover, 86% of the whole population wanted to complete the recommended vaccinations. However, only 39% of respondents had sufficient information about the vaccination plan in Austrian. CONCLUSION: Numerous patients receiving HD wanted to obtain more information from their dialysis physicians. Increased awareness among providers and targeted communication might increase vaccination rates.

Extracorporeal Techniques in Kidney Failure.

During the last decades, various strategies have been optimized to enhance clearance of a variable spectrum of retained molecules to ensure hemodynamic tolerance to fluid removal and improve long-term survival in patients affected by kidney failure. Treatment effects are the result of the interaction of individual patient characteristics with device characteristics and treatment prescription. Historically, the nephrology community aimed to provide adequate treatment, along with the best possible quality of life and outcomes. In this article, we analyzed blood purification techniques that have been developed with their different characteristics.

Salivary potassium measured by genetically encoded potassium ion indicators as a surrogate for plasma potassium levels in hemodialysis patients-a proof-of-concept study.

BACKGROUND: Hyperkalemia is a common complication in cardiorenal patients treated with agents interfering with renal potassium (K+) excretion. It frequently leads to discontinuation of potentially life-saving medication, which has increased the importance of K+ monitoring. Non-invasive means to detect hyperkalemia are currently unavailable, but would be of potential use for therapy guidance. The aim of the present study was to assess the analytical performance of genetically encoded potassium-ion indicators (GEPIIs) in measuring salivary [K+] ([K+]Saliva) and to determine whether changes of [K+]Saliva depict those of [K+]Plasma. METHODS: We conducted this proof-of-concept study: saliva samples from 20 healthy volunteers as well as plasma and saliva from 29 patients on hemodialysis (HD) before and after three consecutive HD treatments were collected. We compared [K+]Saliva as assessed by the gold standard ion-selective electrode (ISE) with GEPII measurements. RESULTS: The Bland-Altmann analysis showed a strong agreement (bias 0.71; 95% limits of agreement from -2.79 to 4.40) between GEPII and ISE. Before treatment, patients on HD showed significantly higher [K+]Saliva compared with healthy controls [median 37.7 (30.85; 48.46) vs 23.8 (21.63; 25.23) mmol/L; P < .05]. [K+]Plasma in HD patients decreased significantly after dialysis. This was paralleled by a significant decrease in [K+]Saliva, and both parameters increased until the subsequent HD session. Despite similar kinetics, we found weak or no correlation between [K+]Plasma and [K+]Saliva. CONCLUSION: GEPIIs have shown an excellent performance in determining [K+]Saliva. [K+]Plasma and [K+]Saliva exhibited similar kinetics. To determine whether saliva could be a suitable sample type to monitor [K+]Plasma, further testing in future studies are required.

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.

Blockade of tumor necrosis factor superfamily members CD30 and OX40 abrogates disease activity in murine immune-mediated glomerulonephritis.

Co-stimulation is a prerequisite for pathogenic activity in T cell-mediated diseases and has been demonstrated to achieve tolerance in organ-specific autoimmunity as a therapeutic target. Here, we evaluated the involvement of the tumor necrosis factor family members CD30 and OX40 in immune-complex mediated kidney disease. In vitro stimulation and proliferation studies were performed with CD4+ cells from wild type and CD30/OX40 double knock-out (CD30OX40-/-) mice. In vivo studies were performed by induction of nephrotoxic serum nephritis in wild type, CD30OX40- /- , CD30-/-, OX40-/-, reconstituted Rag1-/- and C57Bl/6J mice treated with αCD30L αOX40L antibodies. CD30, OX40 and their ligands were upregulated on various leukocytes in nephrotoxic serum nephritis. CD30OX40-/- mice, but not CD30-/- or OX40-/- mice were protected from nephrotoxic serum nephritis. Similar protection was found in Rag1-/- mice injected with CD4+ T cells from CD30OX40-/- mice compared to Rag1-/- mice injected with CD4+ T cells from wild type mice. Furthermore, CD4+ T cells deficient in CD30OX40-/- displayed decreased expression of CCR6 in vivo. CD30OX40-/- cells were fully capable of differentiating into disease mediating T helper cell subsets, but showed significantly decreased levels of proliferation in vivo and in vitro compared to wild type cells. Blocking antibodies against CD30L and OX40L ameliorated nephrotoxic serum nephritis without affecting pan-effector or memory T cell populations. Thus, our results indicate disease promotion via CD30 and OX40 signaling due to facilitation of exaggerated T cell proliferation and migration of T helper 17 cells in nephrotoxic serum nephritis. Hence, co-stimulation blockade targeting the CD30 and OX40 signaling pathways may provide a novel therapeutic strategy in autoimmune kidney disease.

Glucagon-Like Peptide-1 Receptor Agonism Improves Nephrotoxic Serum Nephritis by Inhibiting T-Cell Proliferation.

Glucagon-like peptide (GLP)-1 analogs such as liraglutide improved albuminuria in patients with type 2 diabetes in large randomized controlled trials. One of the suspected mechanisms is the anti-inflammatory potential of GLP-1 receptor (Glp1r) agonism. Thus, the anti-inflammatory action of Glp1r agonism was tested in a nondiabetic, T-cell-mediated murine model of nephrotoxic serum nephritis (NTS). The role of Glp1r in NTS was evaluated by using Glp1r-/- mice or C57BL/6 mice treated with liraglutide. In vitro, murine T cells were stimulated in the presence of liraglutide or vehicle. Glp1r-/- mice displayed increased renal infiltration of neutrophils and T cells after induction of NTS. Splenocyte proliferation and TH1 cytokine transcription were increased in spleen and lymph nodes of Glp1r-/- mice. Liraglutide treatment significantly improved the renal outcome of NTS in C57BL/6 mice by decreasing renal infiltration and proliferation of T cells, which resulted in decreased macrophage infiltration. In vitro, T cells stimulated in the presence of liraglutide showed decreased proliferation of TH1 and TH17 cells. Liraglutide blocked glycolysis in T cells and decreased their Glut1 mRNA expression. Together, Glp1r agonism protects mice from a T-cell-dependent glomerulonephritis model by inhibition of T-cell proliferation, possibly by interacting with their metabolic program. This mechanism may explain in part the renoprotective effects of Glp1r agonism in diabetic nephropathy.

Impact of cardiovascular risk stratification strategies in kidney transplantation over time.

BACKGROUND: Kidney transplant recipients exhibit a dramatically increased cardiovascular (CV) risk. In 2007, Austrian centres implemented a consensus of comprehensive CV screening programme prior to kidney transplantation (KT). The consensus placed a particular emphasis on screening for coronary artery disease (CAD) with cardiac computed tomography (CT) or coronary angiography (CAG) in patients with diabetes mellitus, known CAD or those having multiple conventional CV risk factors. Here, we investigate if this affected risk stratification and post-transplant CV outcomes. METHODS: In a retrospective chart review, we evaluated 551 KTs performed from 2003 to 2015 in our centre. Patients were categorized into three groups: KT before (2003-07), directly after (2008-11) and 5 years after (2012-15) implementation of the consensus. We analysed clinical characteristics, the rate of cardiac CTs and CAGs prior to KT as well as major adverse cardiac events (MACEs) during a 2-year follow-up after KT. RESULTS: The three study groups showed a homogeneous distribution of comorbidities and age. Significantly more cardiac CTs (13.6% versus 10.2% versus 44.8%; P = 0.002) and CAGs (39.6% versus 43.9% versus 56.2%; P = 0.003) were performed after the consensus. Coronary interventions were performed during 42 out of 260 CAGs (16.2%), the cumulative 2-year MACE incidence was 8.7%. Regarding MACE occurrence, no significant difference between the three groups was found. CONCLUSION: CV risk stratification has become more rigorous and invasive after the implementation of the consensus; however, this was not associated with an improvement in CV outcome.

Intradialytic kinetics of middle molecules during hemodialysis and hemodiafiltration.

BACKGROUND: The kinetics of ß2-microglobulin during hemodialysis and hemodiafiltration is well described by a two-compartment model where clearance by the dialyzer is from a central compartment volume that approximates plasma volume and a total distribution volume that approximates extracellular fluid volume. The kinetics of middle molecules with molecular weights larger than ß2-microglobulin have not been extensively studied. METHODS: Intradialytic plasma concentrations and overall dialyzer clearances of ß2-microglobulin (11.8 kD), myoglobin (16.7 kD) and complement factor D (24.4 kD) were used to estimate three kinetic parameters from a two-compartment model, namely intercompartmental clearance, central compartment volume and total distribution volume, in hemodialysis patients; these data were collected during two clinical trials of medium cut-off dialyzers (with extended middle molecule removal) during hemodialysis and high-flux dialyzers during hemodialysis and hemodiafiltration. In the current exploratory analyses, the kinetic parameters from all dialyzers were combined. Overall dialyzer clearance was evaluated by total mass removed in the dialysate. RESULTS: In total, 345 sets of kinetic parameters from 35 patients were determined. Intercompartmental clearance and central compartment volume for myoglobin and complement factor D were smaller (P < 0.001) than those for ß2-microglobulin. Independent of middle molecule, intercompartmental clearance and central compartment volume were associated with overall dialyzer clearance (P < 0.001), but total distribution volume was not (P = 0.083). CONCLUSIONS: A two-compartment kinetic model can only describe intradialytic kinetics of middle molecules with molecular weights larger than ß2-microglobulin if the central compartment is small and dependent on overall dialyzer clearance.

Blockade of prostaglandin E2 receptor 4 ameliorates nephrotoxic serum nephritis.

Prostaglandin E2 (PGE2) signaling is known to modulate inflammation and vascular resistance. Receptors of PGE2 [E-type prostanoid receptors (EP)] might be an attractive pharmacological target in immune-mediated diseases such as glomerulonephritis. We hypothesized that selective EP4 antagonism improves nephrotoxic serum nephritis (NTS) by its anti-inflammatory properties. Mice were subjected to NTS and treated with the EP4 antagonist ONO AE3-208 (10 mg·kg body wt-1·day-1] or vehicle starting from disease initiation. In one set of experiments, treatment was started 4 days after NTS induction. Tubular epithelial cells were evaluated in vitro under starving conditions. EP4 antagonist treatment significantly improved the NTS phenotype without affecting blood pressure levels. Remarkably, the improved NTS phenotype was also observed when treatment was started 4 days after NTS induction. EP4 antagonism decreased tubular chemokine (C-X-C motif) ligand ( Cxcl) 1 and Cxcl-5 expression and thereby subsequently reduced interstitial neutrophil infiltration into the kidney. In vitro, tubular epithelial cells increasingly expressed Cxcl-5 mRNA and Cxcl-5 protein when treated with PGE2 or an EP4 agonist under starving conditions, which was blunted by EP4 antagonist treatment. Together, EP4 antagonism improves the NTS phenotype, probably by decreasing mainly Cxcl-5 production in tubular cells, thereby reducing renal neutrophil infiltration.

NorUrsodeoxycholic acid ameliorates cholemic nephropathy in bile duct ligated mice.

BACKGROUND & AIMS: Severe cholestasis may cause cholemic nephropathy that can be modeled in common bile duct ligated (CBDL) mice. We aimed to explore the therapeutic efficacy and mechanisms of norursodeoxycholic acid (norUDCA) in cholemic nephropathy. METHODS: In 8-week CBDL mice fed with norUDCA (prior or post CBDL) or chow we evaluated serum urea levels, urine cytology and urinary neutrophil gelatinase associated lipocalin (uNGAL), kidney and liver tissue quantification of fibrosis by hydroxyproline content and gene chip expression looking at key genes of inflammation and fibrosis. Moreover, we comprehensively analysed bile acid profiles in liver, kidney, serum and urine samples. RESULTS: NorUDCA-fed CBDL mice had significantly lower serum urea and uNGAL levels and less severe cholemic nephropathy as demonstrated by normal urine cytology, significantly reduced tubulointerstitial nephritis, and renal fibrosis as compared to controls. NorUDCA underwent extensive metabolism to produce even more hydrophilic compounds that were significantly enriched in kidneys. CONCLUSION: NorUDCA ameliorates cholemic nephropathy due to the formation of highly hydrophilic metabolites enriched in kidney. Consequently, norUDCA may represent a medical treatment for cholemic nephropathy. LAY SUMMARY: The term cholemic nephropathy describes renal dysfunction together with characteristic morphological alterations of the kidney in obstructive cholestasis that can be mimicked by ligation of the common bile duct in mice. Feeding the hydrophilic bile acid norUDCA to bile duct ligated mice leads to a significant amelioration of the renal phenotype due to the formation of highly hydrophilic metabolites enriched in the kidney and may therefore represent a medical treatment for cholemic nephropathy.

Performance of hemodialysis with novel medium cut-off dialyzers.

Background: Compared to high-flux dialysis membranes, novel medium cut-off (MCO) membranes show greater permeability for larger middle molecules. Methods: In two prospective, open-label, controlled, randomized, crossover pilot studies, 39 prevalent hemodialysis (HD) patients were studied in four dialysis treatments as follows: study 1, three MCO prototype dialyzers (AA, BB and CC with increasing permeability) and one high-flux dialyzer in HD; and study 2, two MCO prototype dialyzers (AA and BB) in HD and high-flux dialyzers in HD and hemodiafiltration (HDF). Primary outcome was lambda free light chain (λFLC) overall clearance. Secondary outcomes included overall clearances and pre-to-post-reduction ratios of middle and small molecules, and safety of MCO HD treatments. Results: MCO HD provided greater λFLC overall clearance [least square mean (standard error)] as follows: study 1: MCO AA 8.5 (0.54), MCO BB 11.3 (0.51), MCO CC 15.0 (0.53) versus high-flux HD 3.6 (0.51) mL/min; study 2: MCO AA 10.0 (0.58), MCO BB 12.5 (0.57) versus high-flux HD 4.4 (0.57) and HDF 6.2 (0.58) mL/min. Differences between MCO and high-flux dialyzers were consistently significant in mixed model analysis (each P < 0.001). Reduction ratios of λFLC were greater for MCO. Clearances of α1-microglobulin, complement factor D, kappa FLC (κFLC) and myoglobin were generally greater with MCO than with high-flux HD and similar to or greater than clearances with HDF. Albumin loss was moderate with MCO, but greater than with high-flux HD and HDF. Conclusions: MCO HD removes a wide range of middle molecules more effectively than high-flux HD and even exceeds the performance of high-volume HDF for large solutes, particularly λFLC.

Innate and adaptive immunity in experimental glomerulonephritis: a pathfinder tale.

The role of innate and adaptive immune cells in the experimental model of nephrotoxic serum nephritis (NTS) has been rigorously studied in recent years. The model is dependent on kidney-infiltrating T helper (TH) 17 and TH1 cells, which recruit neutrophils and macrophages, respectively, and cause sustained kidney inflammation. In a later phase of disease, regulatory T cells (Tregs) infiltrate the kidney in an attempt to limit disease activity. In the early stage of NTS, lymph node drainage plays an important role in disease initiation since dendritic cells present the antigen to T cells in the T cell zones of the draining lymph nodes. This results in the differentiation and proliferation of TH17 and TH1 cells. In this setting, immune regulatory cells (Tregs), namely, CCR7-expressing Tregs and mast cells (MCs), which are recruited by Tregs via the production of interleukin-9, exert their immunosuppressive capacity. Together, these two cell populations inhibit T cell differentiation and proliferation, thereby limiting disease activity by as yet unknown mechanisms. In contrast, the spleen plays no role in immune activation in NTS, but constitutes a place of extramedullary haematopoiesis. The complex interactions of immune cells in NTS are still under investigation and might ultimately lead to targeted therapies in glomerulonephritis.

A porcine model of hypertensive cardiomyopathy: implications for heart failure with preserved ejection fraction.

Heart failure with preserved ejection fraction (HFPEF) evolves with the accumulation of risk factors. Relevant animal models to identify potential therapeutic targets and to test novel therapies for HFPEF are missing. We induced hypertension and hyperlipidemia in landrace pigs (n = 8) by deoxycorticosteroneacetate (DOCA, 100 mg/kg, 90-day-release subcutaneous depot) and a Western diet (WD) containing high amounts of salt, fat, cholesterol, and sugar for 12 wk. Compared with weight-matched controls (n = 8), DOCA/WD-treated pigs showed left ventricular (LV) concentric hypertrophy and left atrial dilatation in the absence of significant changes in LV ejection fraction or symptoms of heart failure at rest. The LV end-diastolic pressure-volume relationship was markedly shifted leftward. During simultaneous right atrial pacing and dobutamine infusion, cardiac output reserve and LV peak inflow velocities were lower in DOCA/WD-treated pigs at higher LV end-diastolic pressures. In LV biopsies, we observed myocyte hypertrophy, a shift toward the stiffer titin isoform N2B, and reduced total titin phosphorylation. LV superoxide production was increased, in part attributable to nitric oxide synthase (NOS) uncoupling, whereas AKT and NOS isoform expression and phosphorylation were unchanged. In conclusion, we developed a large-animal model in which loss of LV capacitance was associated with a titin isoform shift and dysfunctional NOS, in the presence of preserved LV ejection fraction. Our findings identify potential targets for the treatment of HFPEF in a relevant large-animal model.