Targeting senescence induced by age or chemotherapy with a polyphenol-rich natural extract improves longevity and healthspan in mice.

Accumulating senescent cells within tissues contribute to the progression of aging and age-related diseases. Botanical extracts, rich in phytoconstituents, present a useful resource for discovering therapies that could target senescence and thus improve healthspan. Here, we show that daily oral administration of a standardized extract of Salvia haenkei (Haenkenium (HK)) extended lifespan and healthspan of naturally aged mice. HK treatment inhibited age-induced inflammation, fibrosis and senescence markers across several tissues, as well as increased muscle strength and fur thickness compared with age-matched controls. We also found that HK treatment reduced acutely induced senescence by the chemotherapeutic agent doxorubicin, using p16LUC reporter mice. We profiled the constituent components of HK by mass spectrometry, and identified luteolin-the most concentrated flavonoid in HK-as a senomorphic compound. Mechanistically, by performing surface plasmon resonance and in situ proximity ligation assay, we found that luteolin disrupted the p16-CDK6 interaction. This work demonstrates that administration of HK promotes longevity in mice, possibly by modulating cellular senescence and by disrupting the p16-CDK6 interaction.

A transfer learning framework to elucidate the clinical relevance of altered proximal tubule cell states in kidney disease.

The application of single-cell technologies in clinical nephrology remains elusive. We generated an atlas of transcriptionally defined cell types and cell states of human kidney disease by integrating single-cell signatures reported in the literature with newly generated signatures obtained from 5 patients with acute kidney injury. We used this information to develop kidney-specific cell-level information ExtractoR (K-CLIER), a transfer learning approach specifically tailored to evaluate the role of cell types/states on bulk RNAseq data. We validated the K-CLIER as a reliable computational framework to obtain a dimensionality reduction and to link clinical data with single-cell signatures. By applying K-CLIER on cohorts of patients with different kidney diseases, we identified the most relevant cell types associated with fibrosis and disease progression. This analysis highlighted the central role of altered proximal tubule cells in chronic kidney disease. Our study introduces a new strategy to exploit the power of single-cell technologies toward clinical applications.

Taurine Deficiency Is a Hallmark of Injured Kidney Allografts.

BACKGROUND: Taurine is one of the most abundant amino acids in humans. Low taurine levels are associated with cellular senescence, mitochondrial dysfunction, DNA damage, and inflammation in mouse, all of which can be reversed by supplementation. It is unknown whether taurine metabolism is associated with kidney allograft function and survival. METHODS: We performed urine metabolomic profiling of kidney transplant recipients in the early and late phases after transplantation combined with transcriptomic analysis of human kidney allografts. Single-nucleus RNA sequencing data sets of mouse kidneys after ischemia-reperfusion injury were analyzed. We analyzed the association of urinary taurine levels and taurine metabolism genes with kidney function, histology, and graft survival. RESULTS: Urine taurine concentrations were significantly lower in kidney transplant recipients who experienced delayed graft function. In a mouse model of ischemia-reperfusion injury, the taurine biosynthesis gene, CSAD, but not the taurine transporter SLC6A6, was repressed. In the late stage of transplantation, low level of taurine in urine was associated with impaired kidney function and chronic structural changes. Urine taurine level in the lowest tertile was predictive of graft loss. Expression of the taurine transporter SLC6A6 in the upper median, but not CSAD, was associated with chronic kidney injury and was predictive of graft loss. CONCLUSIONS: Low urine taurine level is a marker of injury in the kidney allograft, is associated with poor kidney function, is associated with chronic histological changes, and is predictive of graft survival. The differential expression of CSAD and SLC6A6, depending on the time after transplantation and marks of injury, highlights different mechanisms affecting taurine metabolism.

SOX9 switch links regeneration to fibrosis at the single-cell level in mammalian kidneys.

The steps governing healing with or without fibrosis within the same microenvironment are unclear. After acute kidney injury (AKI), injured proximal tubular epithelial cells activate SOX9 for self-restoration. Using a multimodal approach for a head-to-head comparison of injury-induced SOX9 lineages, we identified a dynamic SOX9 switch in repairing epithelia. Lineages that regenerated epithelia silenced SOX9 and healed without fibrosis (SOX9on-off). By contrast, lineages with unrestored apicobasal polarity maintained SOX9 activity in sustained efforts to regenerate, which were identified as a SOX9on-on Cadherin6pos cell state. These reprogrammed cells generated substantial single-cell WNT activity to provoke a fibroproliferative response in adjacent fibroblasts, driving AKI to chronic kidney disease. Transplanted human kidneys displayed similar SOX9/CDH6/WNT2B responses. Thus, we have uncovered a sensor of epithelial repair status, the activity of which determines regeneration with or without fibrosis.

Ambient temperature and kidney function in primary care patients.

INTRODUCTION: Exposure to high ambient temperatures is associated with a risk of acute kidney injury. However, evidence comes from emergency departments or extreme weather exposures. It is unclear whether temperature-related adverse kidney outcomes can also be detected at a community level in a temperate climate zone. METHODS: In a 9.5-year retrospective cohort study we correlated estimated glomerular filtration rate (eGFR) values of Swiss adult primary care patients from the FIRE cohort (Family medicine Research using Electronic medical records) with same-day maximum local ambient temperature data. We investigated 5 temperature groups (< 15 °C, 15-19 °C, 20-24 °C, 25-29 °C and ≥ 30 °C) as well as possible interactions for patients with increased kidney vulnerability (chronic heart failure, diabetes, chronic kidney disease, therapy with renin-angiotensin-aldosterone-system (RAAS) inhibitors, diuretics or non-steroidal anti-inflammatory drugs). RESULTS: We included 18,000 primary care patients who altogether provided 132,176 creatinine measurements. In the unadjusted analysis, higher ambient temperatures were associated with lower eGFR across all age and vulnerability groups. In the adjusted models, we did not find a consistent association.The highest ambient temperature differences (> 25 or > 30 versus < 15 °C) were associated with marginally reduced kidney function only in patients with ≥ 3 risk factors for kidney vulnerability, with a maximum estimated glomerular filtration rate reduction of -2.9 ml/min/1.73m2 (SE 1.0), P 0.003. DISCUSSION: In a large primary care cohort from a temperate climate zone, we did not find an association between ambient temperatures and kidney function. A marginal inverse association in highly vulnerable patients is of unclear clinical relevance.

Immune Monitoring-Guided Versus Fixed Duration of Antiviral Prophylaxis Against Cytomegalovirus in Solid-Organ Transplant Recipients: A Multicenter, Randomized Clinical Trial.

BACKGROUND: The use of assays detecting cytomegalovirus (CMV)-specific T cell-mediated immunity may individualize the duration of antiviral prophylaxis after transplantation. METHODS: In this randomized trial, kidney and liver transplant recipients from 6 centers in Switzerland were enrolled if they were CMV-seronegative with seropositive donors or CMV-seropositive receiving antithymocyte globulins. Patients were randomized to a duration of antiviral prophylaxis based on immune monitoring (intervention) or a fixed duration (control). Patients in the control group were planned to receive 180 days (CMV-seronegative) or 90 days (CMV-seropositive) of valganciclovir. Patients were assessed monthly with a CMV ELISpot assay (T-Track CMV); prophylaxis in the intervention group was stopped if the assay was positive. The co-primary outcomes were the proportion of patients with clinically significant CMV infection and reduction in days of prophylaxis. Between-group differences were adjusted for CMV serostatus. RESULTS: Overall, 193 patients were randomized (92 in the immune-monitoring group and 101 in the control group), of whom 185 had evaluation of the primary outcome (87 and 98 patients). CMV infection occurred in 26 of 87 (adjusted percentage, 30.9%) in the immune-monitoring group and in 32 of 98 (adjusted percentage, 31.1%) in the control group (adjusted risk difference, -0.1; 95% confidence interval [CI], -13.0% to 12.7%; P = .064). The duration of prophylaxis was shorter in the immune-monitoring group (adjusted difference, -26.0 days; 95%, CI, -41.1 to -10.8 days; P < .001). CONCLUSIONS: Immune monitoring resulted in a significant reduction of antiviral prophylaxis, but we were unable to establish noninferiority of this approach on the co-primary outcome of CMV infection. CLINICAL TRIALS REGISTRATION: NCT02538172.

Peritoneal dialysis discontinuation: to the root of the problem.

As the global burden of chronic kidney disease continues to increase, the use of peritoneal dialysis is often advocated as the preferred initial dialysis modality. Observational studies suggest a survival advantage for peritoneal dialysis over hemodialysis for the initial 2-3 years of dialysis. Peritoneal dialysis has been associated with better graft survival after kidney transplantation and has a reduced cost burden compared to hemodialysis. However, several medical and non-medical reasons may limit access to peritoneal dialysis, and less than 20% of patients with end-stage kidney disease are treated with peritoneal dialysis worldwide. In this narrative review, we sought to summarize the recent medical literature on risk factors for peritoneal dialysis discontinuation, distinguishing the early and the late phase after peritoneal dialysis initiation. Although the definition of clinically relevant outcomes varies among studies, we observed that center size, older age, and the presence of many comorbidities are risk factors associated with peritoneal dialysis discontinuation, regardless of the phase after peritoneal dialysis initiation. On the contrary, poor technique training and late referral to nephrology care, as opposed to the need for a caregiver, patient burnout and frequent hospitalizations, are related to early and late peritoneal dialysis drop-out, respectively. The aim of the review is to provide an overview of the most relevant parameters to be considered when advising patients in the selection of the most appropriate dialysis modality and in the clinical management of peritoneal dialysis patients. In addition, we wish to provide the readers with a critical appraisal of current literature and a call for a consensus on the definition of clinically relevant outcomes in peritoneal dialysis to better address patients' needs.

Neutralization, effector function and immune imprinting of Omicron variants.

Currently circulating SARS-CoV-2 variants have acquired convergent mutations at hot spots in the receptor-binding domain1 (RBD) of the spike protein. The effects of these mutations on viral infection and transmission and the efficacy of vaccines and therapies remains poorly understood. Here we demonstrate that recently emerged BQ.1.1 and XBB.1.5 variants bind host ACE2 with high affinity and promote membrane fusion more efficiently than earlier Omicron variants. Structures of the BQ.1.1, XBB.1 and BN.1 RBDs bound to the fragment antigen-binding region of the S309 antibody (the parent antibody for sotrovimab) and human ACE2 explain the preservation of antibody binding through conformational selection, altered ACE2 recognition and immune evasion. We show that sotrovimab binds avidly to all Omicron variants, promotes Fc-dependent effector functions and protects mice challenged with BQ.1.1 and hamsters challenged with XBB.1.5. Vaccine-elicited human plasma antibodies cross-react with and trigger effector functions against current Omicron variants, despite a reduced neutralizing activity, suggesting a mechanism of protection against disease, exemplified by S309. Cross-reactive RBD-directed human memory B cells remained dominant even after two exposures to Omicron spikes, underscoring the role of persistent immune imprinting.

Growth Differentiation Factor 15 and Risk of Death in Haemodialysis Patients.

Aim: Noninvasive identification of haemodialysis patients at high risk of cardiovascular events and death might improve their outcome. Growth differentiation factor 15 is a prognostic biomarker in multiple disease entities, including cardiovascular disease. The aim of this study was to assess the association between plasma GDF-15 and mortality in a cohort of haemodialysis patients. Methods: Circulating GDF-15 was measured in 30 patients after a regular haemodialysis session, followed by a clinical follow-up for all-cause death. Measurements were performed using the Proseek Multiplex Cardiovascular disease panels (Olink Proteomics AB) and validated using the Elecsys GDF-15 electrochemiluminescence immunoassay on a Cobas E801 analyzer (Roche Diagnostics). Results: During a median of 38 months, 9 patients (30%) died. Seven deaths occurred in the group of patients with a circulating GDF-15 above the median and two in the group with lower GDF-15. Mortality was significantly higher in patients with circulating GDF-15 levels above the median, log-rankP = 0.044. The performance of circulating GDF-15 to predict long-term mortality has an area under the ROC curve of 0.76, P = 0.028. Prevalence of most relevant comorbidities and the Charlson comorbidity index were similar across the two groups. A high agreement with a correlation among both diagnostic methods was observed (Spearman's rho = 0.83, P < 0.001). Conclusion: Plasma GDF-15 displays promising prognostic properties for the prediction of long-term survival beyond clinical parameters in patients on maintenance haemodialysis.

Proximal tubule responses to injury: interrogation by single-cell transcriptomics.

PURPOSE OF REVIEW: Acute kidney injury (AKI) occurs in approximately 10-15% of patients admitted to hospital and is associated with adverse clinical outcomes. Despite recent advances, management of patients with AKI is still mainly supportive, including the avoidance of nephrotoxins, volume and haemodynamic management and renal replacement therapy. A better understanding of the renal response to injury is the prerequisite to overcome current limitations in AKI diagnostics and therapy. RECENT FINDINGS: Single-cell technologies provided new opportunities to study the complexity of the kidney and have been instrumental for rapid advancements in the understanding of the cellular and molecular mechanisms of AKI. SUMMARY: We provide an update on single-cell technologies and we summarize the recent discoveries on the cellular response to injury in proximal tubule cells from the early response in AKI, to the mechanisms of tubule repair and the relevance of maladaptive tubule repair in the transition to chronic kidney disease.

Selective Bcl-2 inhibition promotes hematopoietic chimerism and allograft tolerance without myelosuppression in nonhuman primates.

Hematopoietic stem cell transplantation (HSCT) has many potential applications beyond current standard indications, including treatment of autoimmune disease, gene therapy, and transplant tolerance induction. However, severe myelosuppression and other toxicities after myeloablative conditioning regimens have hampered wider clinical use. To achieve donor hematopoietic stem cell (HSC) engraftment, it appears essential to establish niches for the donor HSCs by depleting the host HSCs. To date, this has been achievable only by nonselective treatments such as irradiation or chemotherapeutic drugs. An approach that is capable of more selectively depleting host HSCs is needed to widen the clinical application of HSCT. Here, we show in a clinically relevant nonhuman primate model that selective inhibition of B cell lymphoma 2 (Bcl-2) promoted hematopoietic chimerism and renal allograft tolerance after partial deletion of HSCs and effective peripheral lymphocyte deletion while preserving myeloid cells and regulatory T cells. Although Bcl-2 inhibition alone was insufficient to induce hematopoietic chimerism, the addition of a Bcl-2 inhibitor resulted in promotion of hematopoietic chimerism and renal allograft tolerance despite using only half of the dose of total body irradiation previously required. Selective inhibition of Bcl-2 is therefore a promising approach to induce hematopoietic chimerism without myelosuppression and has the potential to render HSCT more feasible for a variety of clinical indications.

Study protocol for Vascular Access outcome measure for function: a vaLidation study In hemoDialysis (VALID) : A multi-center, multinational validation study to assess the accuracy and feasibility of measuring vascular access function in clinical practice.

BACKGROUND: A functioning vascular access (VA) is crucial to providing adequate hemodialysis (HD) and considered a critically important outcome by patients and healthcare professionals. A validated, patient-important outcome measure for VA function that can be easily measured in research and practice to harvest reliable and relevant evidence for informing patient-centered HD care is lacking. Vascular Access outcome measure for function: a vaLidation study In hemoDialysis (VALID) aims to assess the accuracy and feasibility of measuring a core outcome for VA function established by the international Standardized Outcomes in Nephrology (SONG) initiative. METHODS: VALID is a prospective, multi-center, multinational validation study that will assess the accuracy and feasibility of measuring VA function, defined as the need for interventions to enable and maintain the use of a VA for HD. The primary objective is to determine whether VA function can be measured accurately by clinical staff as part of routine clinical practice (Assessor 1) compared to the reference standard of documented VA procedures collected by a VA expert (Assessor 2) during a 6-month follow-up period. Secondary outcomes include feasibility and acceptability of measuring VA function and the time to, rate of, and type of VA interventions. An estimated 612 participants will be recruited from approximately 10 dialysis units of different size, type (home-, in-center and satellite), governance (private versus public), and location (rural versus urban) across Australia, Canada, Europe, and Malaysia. Validity will be measured by the sensitivity and specificity of the data acquisition process. The sensitivity corresponds to the proportion of correctly identified interventions by Assessor 1, among the interventions identified by Assessor 2 (reference standard). The feasibility of measuring VA function will be assessed by the average data collection time, data completeness, feasibility questionnaires and semi-structured interviews on key feasibility aspects with the assessors. DISCUSSION: Accuracy, acceptability, and feasibility of measuring VA function as part of routine clinical practice are required to facilitate global implementation of this core outcome across all HD trials. Global use of a standardized, patient-centered outcome measure for VA function in HD research will enhance the consistency and relevance of trial evidence to guide patient-centered care. TRIAL REGISTRATION: Clinicaltrials.gov: NCT03969225. Registered on 31st May 2019.

Heparin-induced thrombocytopenia following Shiga-toxin-associated hemolytic uremic syndrome: a case report.

BACKGROUND: Up to 50% of cases of Shiga-toxin-producing Escherichia coli hemolytic uremic syndrome occur in adults, and the clinical presentation is variable. Microbiological analyses must be performed in all patients with thrombotic microangiopathy to identify Shiga-toxin-producing Escherichia coli, even in the absence of diarrhea. CASE PRESENTATION: A 79-year-old Caucasian woman was admitted to hospital because of severe proctitis. In the following days, the patient's level of consciousness declined, and she developed acute kidney injury, thrombocytopenia, and hemolytic anemia. Shiga-toxin-producing Escherichia coli was found in fecal cultures, suggesting the diagnosis of hemolytic uremic syndrome. In the following days, her clinical conditions improved, but thrombocytopenia worsened, and the patient developed posterior tibial vein thrombosis. The discordant evolution of thrombocytopenia compared with other clinical and laboratory parameters prompted a new evaluation of its causes. Diagnosis of heparin-induced thrombocytopenia was confirmed by heparin-induced platelet aggregation assay and positive antibodies to platelet factor 4. CONCLUSIONS: A discordant evolution of platelet count in patients with thrombotic microangiopathy requires a systematic reevaluation of the thrombocytopenia.

Impaired fatty acid metabolism perpetuates lipotoxicity along the transition to chronic kidney injury.

Energy metabolism failure in proximal tubule cells (PTCs) is a hallmark of chronic kidney injury. We combined transcriptomic, metabolomic, and lipidomic approaches in experimental models and patient cohorts to investigate the molecular basis of the progression to chronic kidney allograft injury initiated by ischemia/reperfusion injury (IRI). The urinary metabolome of kidney transplant recipients with chronic allograft injury and who experienced severe IRI was substantially enriched with long chain fatty acids (FAs). We identified a renal FA-related gene signature with low levels of carnitine palmitoyltransferase 2 (Cpt2) and acyl-CoA synthetase medium chain family member 5 (Acsm5) and high levels of acyl-CoA synthetase long chain family member 4 and 5 (Acsl4 and Acsl5) associated with IRI, transition to chronic injury, and established chronic kidney disease in mouse models and kidney transplant recipients. The findings were consistent with the presence of Cpt2-Acsl4+Acsl5+Acsm5- PTCs failing to recover from IRI as identified by single-nucleus RNA-Seq. In vitro experiments indicated that ER stress contributed to CPT2 repression, which, in turn, promoted lipids' accumulation, drove profibrogenic epithelial phenotypic changes, and activated the unfolded protein response. ER stress through CPT2 inhibition and lipid accumulation engaged an auto-amplification loop leading to lipotoxicity and self-sustained cellular stress. Thus, IRI imprints a persistent FA metabolism disturbance in the proximal tubule, sustaining the progression to chronic kidney allograft injury.

The "FIFTY SHADOWS" of the RALES Trial: Lessons about the Potential Risk of Dietary Potassium Supplementation in Patients with Chronic Kidney Disease.

Hyperkalaemia (HK) is one of the most common electrolyte disorders and a frequent reason for nephrological consultations. High serum potassium (K+) levels are associated with elevated morbidity and mortality, mainly due to life-threatening arrhythmias. In the majority of cases, HK is associated with chronic kidney disease (CKD), or with the use of renin-angiotensin-aldosterone system inhibitors (RAASis) and/or mineral corticoid antagonists (MRAs). These drugs represent the mainstays of treatment in CKD, HF, diabetes, hypertension, and even glomerular diseases, in consideration of their beneficial effect on hard outcomes related to cardiovascular events and CKD progression. However, experiences in relation to the Randomised Aldactone Evaluation Study (RALES) cast a long shadow that extends to the present day, since the increased risk for HK remains a major concern. In this article, we summarise the physiology of K+ homeostasis, and we review the effects of dietary K+ on blood pressure and cardiovascular risk in the general population and in patients with early CKD, who are often not aware of this disease. We conclude with a note of caution regarding the recent publication of the SSaSS trial and the use of salt substitutes, particularly in patients with a limited capacity to increase K+ secretion in response to an exogenous load, particularly in the context of "occult" CKD, HF, and in patients taking RAASis and/or MRAs.