Allocation Rules and Age-Dependent Waiting Times for Kidney Transplantation­an Analysis of Data From the German Transplantation Registry.

BACKGROUND: Rigid age limits in the current allocation system for post-mortem donor kidneys in Germany may have problematic effects. The new German national transplantion registry enables data analysis with respect to this question. METHODS: Using anonymized data from the German national transplantion registry, we extracted and evaluated information on the recipients and postmortem donors of kidneys that were allocated in Germany through Eurotransplant over the period 2006-2020. RESULTS: Data on 19 664 kidney transplantations in Germany from 2006 to 2020 were analyzed. The median waiting time for kidney transplantation was 5.8 years. Persons under age 18 waited a median of 1.7 years; persons aged 18 to 64, 7.0 years; and persons aged 65 and older, 3.8 years. Over the period of observation, post-mortem kidneys were transplanted into 401 people of age 64 (2.0% of all organ recipients) and 1,393 people of age 65 (7.1% of all organ recipients). The difference in waiting times between allocation programs for persons under age 65 (ETKAS, "Eurotransplant Kidney Allocation System") and those aged 65 and older (ESP, "Eurotransplant Senior Program") increased over the period of observation, from 2.6 years in 2006-2010 to 4.1 years in 2017-2020. CONCLUSION: The rigid age limits in the current allocation rules for post-mortem kidney donations in Germany are prolonging the waiting times for transplants among patients aged 18 to 64. We think these rules need to be fundamentally reassessed.

[Which dialysis method for whom? In-center dialysis vs home dialysis]. / Welches Dialyseverfahren für wen? Zentrumsdialyse vs. Heimdialyse.

There are various dialysis methods available to treat patients with chronic kidney failure. Generally, a distinction is made between peritoneal dialysis and hemodialysis, as well as between home dialysis methods and center-based dialysis methods. To be able to advise patients optimally, it is important to understand the opportunities and limitations of the different method variants. This article provides an overview of the therapy options and describes their strengths and weaknesses.

The Intersectoral Coordination Unit for the Sustainable Intensification of Peritoneal Dialysis in Schleswig-Holstein (SKIP-SH) cohort study.

BACKGROUND: Peritoneal dialysis (PD) remains underutilised in Germany, prompting the initiation of the Sustainable Intensification of Peritoneal Dialysis in Schleswig-Holstein (SKIP-SH) project. The SKIP-SH cohort study aims to demonstrate the presumed benefits of PD, including enhanced quality of life and reduced healthcare personnel requirements, and to generate data to strengthen the use of PD. METHODS: The prospective SKIP-SH cohort study recruits patients with advanced chronic kidney disease (CKD) and their caregivers. Comprehensive data, including demographic information, medical history, clinical course, laboratory data, and quality-of-life assessments, are collected. Additionally, biomaterials will be obtained. Primary study objectives are documenting the clinical course and complications, time on therapy for new dialysis patients, reasons influencing treatment modality choices, circumstances at the initiation of dialysis, and quality of life for patients with CKD and their caregivers. The collected biomaterials will serve as a basis for further translational research. Secondary objectives include identifying factors impacting disease-related quality of life, clinical complications, and therapy dropout, estimating ecological footprints, and evaluating healthcare costs and labour time for initiating and sustaining PD treatment. DISCUSSION: PD is notably underutilised in Germany. The current therapy approach for advanced CKD often lacks emphasis on patient-focused care and quality-of-life considerations. Furthermore, adequate explorative research programs to improve our knowledge of mechanisms leading to disease progression and therapy failure in PD patients are scarce. The overarching goal of the SKIP-SH cohort study is to address the notably low PD prevalence in Germany whilst advocating for a shift towards patient-focused care, quality-of-life considerations, and robust translational research. TRIAL REGISTRATION: This study was registered with the German trial registry (Deutsches Register klinischer Studien) on November 7, 2023, under trial number DRKS00032983.

Cellular senescence and kidney aging.

Life expectancy is increasing worldwide, and by 2050 the proportion of the world's population over 65 years of age is estimated to surpass 1.5 billion. Kidney aging is associated with molecular and physiological changes that cause a loss of renal function and of regenerative potential. As the aging population grows, it is crucial to understand the mechanisms underlying these changes, as they increase the susceptibility to developing acute kidney injury (AKI) and chronic kidney disease (CKD). Various cellular processes and molecular pathways take part in the complex process of kidney aging. In this review, we will focus on the phenomenon of cellular senescence as one of the involved mechanisms at the crossroad of kidney aging, age-related disease, and CKD. We will highlight experimental and clinical findings about the role of cellular senescence in kidney aging and CKD. In addition, we will review challenges in senescence research and emerging therapeutic aspects. We will highlight the great potential of senolytic strategies for the elimination of harmful senescent cells to promote healthy kidney aging and to avoid age-related disease and CKD. This review aims to give insight into recent discoveries and future developments, providing a comprehensive overview of current knowledge on cellular senescence and anti-senescent therapies in the kidney field.

Prevalence of pericardial effusion in autosomal dominant polycystic kidney disease.

Background: Autosomal dominant polycystic kidney disease (ADPKD) has numerous extrarenal manifestations. Pericardial effusion (PE) may be an underrecognized complication with a reported prevalence of up to 35%. Our study is the first to systematically evaluate the prevalence of PE and associated risk factors in an ADPKD cohort outside the USA. Methods: Clinically stable ADPKD patients from a specialized outpatient clinic were evaluated retrospectively. Magnetic resonance tomography and computed tomography scans were analysed regarding the presence of PE (≥4 mm). Imaging results were linked to clinical characteristics. Results: Of 286 ADPKD patients, 208 had computed tomography or magnetic resonance imaging suitable for evaluation of PE. In this group we detected PE in 17 patients (8.2%). The overall prevalence of PE was 6.3%, with more females being affected (prevalence of PE was 7.8% in females and 3.8% in males). The PE mean size was 6.8 ± 3.3 mm. The prevalence of autoimmune diseases was higher in the patients with PE (11.8% versus 2.1%, P = .022), while the presence and size of PE was not associated with signs of rapid progressive disease, ADPKD genotype, patient age, body mass index and other clinical parameters. Exploratory investigation of individual characteristics of PE patients by regression tree analysis suggested renal functional impairment, sex and proteinuria as candidate variables. Conclusions: PE prevalence in our cohort was lower than previously reported and showed a clear female preponderance. Our data suggest that patients with PEs >10 mm deserve further attention, as they may have additional non-ADPKD-related pathologies.

Free heme and hemopexin in acute kidney injury after cardiopulmonary bypass and transient renal ischemia.

Free heme is released from hemoproteins during hemolysis or ischemia reperfusion injury and can be pro-inflammatory. Most studies on nephrotoxicity of hemolysis-derived proteins focus on free hemoglobin (fHb) with heme as a prosthetic group. Measurement of heme in its free, non-protein bound, form is challenging and not commonly used in clinical routine diagnostics. In contrast to fHb, the role of free heme in acute kidney injury (AKI) after cardiopulmonary bypass (CPB) surgery is unknown. Using an apo-horseradish peroxidase-based assay, we identified free heme during CPB surgery as predictor of AKI in patients undergoing cardiac valve replacement (n = 37). Free heme levels during CPB surgery correlated with depletion of hemopexin (Hx), a heme scavenger-protein. In mice, the impact of high levels of circulating free heme on the development of AKI following transient renal ischemia and the therapeutic potential of Hx were investigated. C57BL/6 mice were subjected to bilateral renal ischemia/reperfusion injury for 15 min which did not cause AKI. However, additional administration of free heme in this model promoted overt AKI with reduced renal function, increased renal inflammation, and reduced renal perfusion on functional magnetic resonance imaging. Hx treatment attenuated AKI. Free heme administration to sham operated control mice did not cause AKI. In conclusion, free heme is a predictor of AKI in CPB surgery patients and promotes AKI in transient renal ischemia. Depletion of Hx in CPB surgery patients and attenuation of AKI by Hx in the in vivo model encourage further research on Hx therapy in patients with increased free heme levels during CPB surgery.

The monosialoganglioside GM1a protects against complement attack.

The complement system is a part of the innate immune system in the fluid phase and efficiently eliminates pathogens. However, its activation requires tight regulation on the host cell surface in order not to compromise cellular viability. Previously, we showed that loss of placental cell surface sialylation in mice in vivo leads to a maternal complement attack at the fetal-maternal interface, ultimately resulting in loss of pregnancy. To gain insight into the regulatory function of sialylation in complement activation, we here generated trophoblast stem cells (TSC) devoid of sialylation, which also revealed complement sensitivity and cell death in vitro. Glycolipid-analysis by multiplexed capillary gel electrophoresis coupled to laser-induced fluorescence detection (xCGE-LIF) allowed us to identify the monosialoganglioside GM1a as a key element of cell surface complement regulation. Exogenously administered GM1a integrated into the plasma membrane of trophoblasts, substantially increased binding of complement factor H (FH) and was sufficient to protect the cells from complement attack and cell death. GM1a treatment also rescued human endothelial cells and erythrocytes from complement attack in a concentration dependent manner. Furthermore, GM1a significantly reduced complement mediated hemolysis of erythrocytes from a patient with Paroxysmal nocturnal hemoglobinuria (PNH). This study demonstrates the complement regulatory potential of exogenously administered gangliosides and paves the way for sialoglycotherapeutics as a novel substance class for membrane-targeted complement regulators.

The aging kidney is characterized by tubuloinflammaging, a phenotype associated with MHC-II gene expression.

Introduction: Even during physiologic aging, the kidney experiences a loss of mass and a progressive functional decline. This is clinically relevant as it leads to an increased risk of acute and chronic kidney disease. The kidney tubular system plays an important role in the underlying aging process, but the involved cellular mechanisms remain largely elusive. Methods: Kidneys of 3-, 12- and 24-month-old male C57BL/6J mice were used for RNA sequencing, histological examination, immunostaining and RNA-in-situ-hybridization. Single cell RNA sequencing data of differentially aged murine and human kidneys was analyzed to identify age-dependent expression patterns in tubular epithelial cells. Senescent and non-senescent primary tubular epithelial cells from mouse kidney were used for in vitro experiments. Results: During normal kidney aging, tubular cells adopt an inflammatory phenotype, characterized by the expression of MHC class II related genes. In our analysis of bulk and single cell transcriptional data we found that subsets of tubular cells show an age-related expression of Cd74, H2-Eb1 and H2-Ab1 in mice and CD74, HLA-DQB1 and HLADRB1 in humans. Expression of MHC class II related genes was associated with a phenotype of tubular cell senescence, and the selective elimination of senescent cells reversed the phenotype. Exposure to the Cd74 ligand MIF promoted a prosenescent phenotype in tubular cell cultures. Discussion: Together, these data suggest that during normal renal aging tubular cells activate a program of 'tubuloinflammaging', which might contribute to age-related phenotypical changes and to increased disease susceptibility.

Induction of ferroptosis selectively eliminates senescent tubular cells.

The accumulation of senescent cells is an important contributor to kidney aging, chronic renal disease, and poor outcome after kidney transplantation. Approaches to eliminate senescent cells with senolytic compounds have been proposed as novel strategies to improve marginal organs. While most existing senolytics induce senescent cell clearance by apoptosis, we observed that ferroptosis, an iron-catalyzed subtype of regulated necrosis, might serve as an alternative way to ablate senescent cells. We found that murine kidney tubular epithelial cells became sensitized to ferroptosis when turning senescent. This was linked to increased expression of pro-ferroptotic lipoxygenase-5 and reduced expression of anti-ferroptotic glutathione peroxidase 4 (GPX4). In tissue slice cultures from aged kidneys low dose application of the ferroptosis-inducer RSL3 selectively eliminated senescent cells while leaving healthy tubular cells unaffected. Similar results were seen in a transplantation model, in which RSL3 reduced the senescent cell burden of aged donor kidneys and caused a reduction of damage and inflammatory cell infiltration during the early post-transplantation period. In summary, these data reveal an increased susceptibility of senescent tubular cells to ferroptosis with the potential to be exploited for selective reduction of renal senescence in aged kidney transplants.

Myeloid CCR2 Promotes Atherosclerosis after AKI.

BACKGROUND: The risk of cardiovascular events rises after AKI. Leukocytes promote atherosclerotic plaque growth and instability. We established a model of enhanced remote atherosclerosis after renal ischemia-reperfusion (IR) injury and investigated the underlying inflammatory mechanisms. METHODS: Atherosclerotic lesions and inflammation were investigated in native and bone marrow-transplanted LDL receptor-deficient (LDLr-/- ) mice after unilateral renal IR injury using histology, flow cytometry, and gene expression analysis. RESULTS: Aortic root atherosclerotic lesions were significantly larger after renal IR injury than in controls. A gene expression screen revealed enrichment for chemokines and their cognate receptors in aortas of IR-injured mice in early atherosclerosis, and of T cell-associated genes in advanced disease. Confocal microscopy revealed increased aortic macrophage proximity to T cells. Differential aortic inflammatory gene regulation in IR-injured mice largely paralleled the pattern in the injured kidney. Single-cell analysis identified renal cell types that produced soluble mediators upregulated in the atherosclerotic aorta. The analysis revealed a marked early increase in Ccl2, which CCR2+ myeloid cells mainly expressed. CCR2 mediated myeloid cell homing to the post-ischemic kidney in a cell-individual manner. Reconstitution with Ccr2-/- bone marrow dampened renal post-ischemic inflammation, reduced aortic Ccl2 and inflammatory macrophage marker CD11c, and abrogated excess aortic atherosclerotic plaque formation after renal IR. CONCLUSIONS: Our data introduce an experimental model of remote proatherogenic effects of renal IR and delineate myeloid CCR2 signaling as a mechanistic requirement. Monocytes should be considered as mobile mediators when addressing systemic vascular sequelae of kidney injury.

Single cell versus single nucleus: transcriptome differences in the murine kidney after ischemia-reperfusion injury.

The kidney is a complex organ, which consists of multiple components with highly diverse cell types. A detailed understanding of these cell types in health and disease is crucial for the future development of preventive and curative treatment strategies. In recent years, single-cell RNA sequencing (scRNAseq) and single-nucleus RNA sequencing (snRNAseq) technology has opened up completely new possibilities in investigating the variety of renal cell populations in physiological and pathological states. Here, we systematically assessed differences between scRNAseq and snRNAseq approaches in transcriptome analysis of murine kidneys after ischemia-reperfusion injury. We included tissues from control kidneys and from kidneys harvested 1 wk after mild (17-min clamping time) and severe (27-min clamping time) transient unilateral ischemia. Our findings revealed important methodological differences in the discovery of inflammatory cells, tubular cells, and other specialized cell types. Although the scRNAseq approach was advantageous for investigating immune cells, the snRNAseq approach allowed superior insights into healthy and damaged tubular cells. Apart from differences in the quantitative discovery rate, we found important qualitative discrepancies in the captured transcriptomes with crucial consequences for the interpretation of cell states and molecular functions. Together, we provide an overview of method-dependent differences between scRNAseq and snRNAseq results from identical postischemic kidney tissues. Our results highlight the importance of choosing the right approach for specific research questions.NEW & NOTEWORTHY Single-cell and single-nucleus RNA sequencing technologies provide powerful new tools to examine complex tissues such as the kidney. This research reference paper provides practical information on the differences between the two technologies when examining murine kidneys after ischemia-reperfusion injury. The results will serve those who are debating which protocols to use in their given study.

The Therapeutic Potential of Zinc-Alpha2-Glycoprotein (AZGP1) in Fibrotic Kidney Disease.

Chronic kidney disease (CKD) is characterized by a long-term loss of kidney function and, in most cases, by progressive fibrosis. Zinc-alpha2-glycoprotein (AZGP1) is a secreted protein, which is expressed in many different tissues and has been associated with a variety of functions. In a previous study, we have shown in cell culture and in AZGP1 deficient mice that AZGP1 has protective anti-fibrotic effects. In the present study, we tested the therapeutic potential of an experimental increase in AZGP1 using two different strategies. (1) C57Bl/6J mice were treated systemically with recombinant AZGP1, and (2) a transgenic mouse strain was generated to overexpress AZGP1 conditionally in proximal tubular cells. Mice underwent unilateral uretic obstruction as a pro-fibrotic kidney stress model, and kidneys were examined after 14 days. Recombinant AZGP1 treatment was accompanied by better preservation of tubular integrity, reduced collagen deposition, and lower expression of injury and fibrosis markers. Weaker but similar tendencies were observed in transgenic AZGP1 overexpressing mice. Higher AZGP1 levels led to a significant reduction in stress-induced accumulation of tubular lipid droplets, which was paralleled by improved expression of key players in lipid metabolism and fatty acid oxidation. Together these data show beneficial effects of elevated AZGP1 levels in fibrotic kidney disease and highlight a novel link to tubular cell lipid metabolism, which might open up new opportunities for CKD treatment.

Graft function and pregnancy outcomes after kidney transplantation.

BACKGROUND: After kidney transplantation, pregnancy and graft function may have a reciprocal interaction. We evaluated the influence of graft function on the course of pregnancy and vice versa. METHODS: We performed a retrospective observational study of 92 pregnancies beyond the first trimester in 67 women after renal transplantation from 1972 to 2019. Pre-pregnancy eGFR was correlated with outcome parameters; graft function was evaluated by Kaplan Meier analysis. The course of graft function in 28 women who became pregnant after kidney transplantation with an eGFR of < 50 mL/min/1.73m2 was compared to a control group of 79 non-pregnant women after kidney transplantation during a comparable time period and with a matched basal graft function. RESULTS: Live births were 90.5% (fetal death n = 9). Maternal complications of pregnancy were preeclampsia 24% (graft loss 1, fetal death 3), graft rejection 5.4% (graft loss 1), hemolytic uremic syndrome 2% (graft loss 1, fetal death 1), maternal hemorrhage 2% (fetal death 1), urinary obstruction 10%, and cesarian section. (76%). Fetal complications were low gestational age (34.44 ± 5.02 weeks) and low birth weight (2322.26 ± 781.98 g). Mean pre-pregnancy eGFR was 59.39 ± 17.62 mL/min/1.73m2 (15% of cases < 40 mL/min/1.73m2). Pre-pregnancy eGFR correlated with gestation week at delivery (R = 0.393, p = 0.01) and with percent eGFR decline during pregnancy (R = 0.243, p = 0.04). Pregnancy-related eGFR decline was inversely correlated with the time from end of pregnancy to chronic graft failure or maternal death (R = -0.47, p = 0.001). Kaplan Meier curves comparing women with pre-pregnancy eGFR of ≥ 50 to < 50 mL/min showed a significantly longer post-pregnancy graft survival in the higher eGFR group (p = 0.04). Women after kidney transplantation who became pregnant with a low eGFR of > 25 to < 50 mL/min/1.73m2 had a marked decline of renal function compared to a matched non-pregnant control group (eGFR decline in percent of basal eGFR 19.34 ± 22.10%, n = 28, versus 2.61 ± 10.95%, n = 79, p < 0.0001). CONCLUSIONS: After renal transplantation, pre-pregnancy graft function has a key role for pregnancy outcomes and graft function. In women with a low pre-pregnancy eGFR, pregnancy per se has a deleterious influence on graft function. TRIAL REGISTRATION: Since this was a retrospective observational case series and written consent of the patients was obtained for publication, according to our ethics' board the analysis was exempt from IRB approval. Clinical Trial Registration was not done. The study protocol was approved by the Ethics Committee of Hannover Medical School, Chairman Prof. Dr. H. D. Troeger, Hannover, December 12, 2015 (IRB No. 2995-2015).

Effects of chess-based cognitive remediation training as therapy add-on in alcohol and tobacco use disorders: protocol of a randomised, controlled clinical fMRI trial.

BACKGROUND: Alcohol and tobacco use disorders (AUD, TUD) are frequent, both worldwide and in the German population, and cognitive impairments are known to facilitate instances of relapse. Cognitive training has been proposed for enhancing cognitive functioning and possibly improving treatment outcome in mental disorders. However, these effects and underlying neurobiological mechanisms are not yet fully understood regarding AUD and TUD. Examining the effect of chess-based cognitive remediation training (CB-CRT) on neurobiological, neuropsychological and psychosocial aspects as well as treatment outcomes will provide insights into mechanisms underlying relapse and abstinence and might help to improve health behaviour in affected individuals if used as therapy add-on. METHODS AND ANALYSIS: N=96 individuals with either AUD (N=48) or TUD (N=48) between 18 and 65 years of age will participate in a randomised, controlled clinical functional MRI (fMRI) trial. Two control groups will receive treatment as usual, that is, AUD treatment in a clinic, TUD outpatient treatment. Two therapy add-on groups will receive a 6-week CB-CRT as a therapy add-on. FMRI tasks, neurocognitive tests will be administered before and afterwards. All individuals will be followed up on monthly for 3 months. Endpoints include alterations in neural activation and neuropsychological task performance, psychosocial functioning, and relapse or substance intake. Regarding fMRI analyses, a general linear model will be applied, and t-tests, full factorial models and regression analyses will be conducted on the second level. Behavioural and psychometric data will be analysed using t-tests, regression analyses, repeated measures and one-way analyses of variance. ETHICS AND DISSEMINATION: This study has been approved by the ethics committee of the medical faculty Mannheim of the University of Heidelberg (2017-647N-MA). The findings of this study will be presented at conferences and published in peer-reviewed journals. TRIAL REGISTRATION: The study was registered in the Clinical Trials Register (trial identifier: NCT04057534 at clinicaltrials.gov).

[Inhibition of the renin-angiotensin-aldosterone system]. / Blockierung des Renin-Angiotensin-Aldosteron-Systems: Einfluss auf die Progression der chronischen Nierenerkrankung.

Chronic kidney diseases (CKD) are often progressive and usually associated with a relatively slow loss of function. This principally offers the opportunity for drug interventions over a prolonged period. The prerequisite is that clear therapeutic targets can be identified. One of the most important targets is the renin-angiotensin-aldosterone system (RAAS), the activation of which is a key contributor to the progression and deterioration of renal function. This article reviews the pathomechanistic principles of RAAS-mediated renal damage and the pharmaceutical possibilities for inhibition of the RAAS. The evidence from clinical studies on nephroprotection is summarized and the international guideline recommendations are discussed. As a future perspective, the novel possibility of a combined add-on treatment with nonsteroidal mineralocorticoid receptor antagonists is discussed based on the FIDELIO-DKD study.

Human MSC-Derived Exosomes Reduce Cellular Senescence in Renal Epithelial Cells.

Cellular senescence of renal tubular cells is associated with chronic diseases and age-related kidney disorders. Therapies to antagonize senescence are, therefore, explored as novel approaches in nephropathy. Exosomes derived from human mesenchymal stroma-/stem-like cells (MSC) entail the transfer of multiple bioactive molecules, exhibiting profound regenerative potential in various tissues, including therapeutic effects in kidney diseases. Here, we first demonstrate that exosomes promote proliferation and reduce senescence in aged MSC cultures. For potential therapeutic perspectives in organ rejuvenation, we used MSC-derived exosomes to antagonize senescence in murine kidney primary tubular epithelial cells (PTEC). Exosome treatment efficiently reduced senescence while diminishing the transcription of senescence markers and senescence-associated secretory phenotype (SASP) factors. Concomitantly, we observed less DNA damage foci and more proliferating cells. These data provide new information regarding the therapeutic property of MSC exosomes in the development of renal senescence, suggesting a contribution to a new chapter of regenerative vehicles in senotherapy.

[What is evidence-based in the treatment of autosomal dominant polycystic kidney disease?] / Was ist gesichert in der Therapie der autosomal-dominanten polyzystischen Nierenerkrankung?

The cystic transformation of the kidneys and liver are the most common symptoms of autosomal dominant polycystic kidney disease (prevalence 1:400-1:1000). A set of other manifestations can be observed less frequently, such as intracranial aneurysms. End-stage renal disease affects 50% of patients by the age of 70 years. To date, a targeted treatment is only available for patients at risk of rapidly progressive kidney failure. In 2015, the vasopressin receptor antagonist tolvaptan was approved in Germany for slowing down the decline of renal function in autosomal dominant polycystic kidney disease. Selecting the patients that benefit from tolvaptan treatment remains a major challenge. In recent years numerous clinical trials were carried out showing unspecific approaches to slow down the decline in renal function: strictly controlling blood pressure is one of the most important factors. Furthermore, unspecific approaches comprise suppression of vasopressin by sufficient fluid intake and restricted intake of salt. Weight reduction is recommended for obese patients. Lacking more causal approaches, these unspecific measures should be exploited in all patients. Currently, preclinical and clinical trials are testing numerous agents for the establishment of targeted treatment against the cystic degeneration of the kidneys and liver. This also includes dietary approaches. So far, in contrast to other genetic diseases, there are currently no gene therapy approaches for autosomal dominant polycystic kidney disease.

Induction of Stress-Induced Renal Cellular Senescence In Vitro: Impact of Mouse Strain Genetic Diversity.

Cellular senescence, a stress-induced state of irreversible cell cycle arrest, is associated with organ dysfunction and age-related disease. While immortalized cell lines bypass key pathways of senescence, important mechanisms of cellular senescence can be studied in primary cells. Primary tubular epithelial cells (PTEC) derived from mouse kidney are highly susceptible to develop cellular senescence, providing a valuable tool for studying such mechanisms. Here, we tested whether genetic differences between mouse inbred strains have an impact on the development of stress-induced cellular senescence in cultured PTEC. Kidneys from 129S1, B6, NOD, NZO, CAST, and WSB mice were used to isolate PTEC. Cells were monitored for expression of typical senescence markers (SA-ß-galactosidase, γ-H2AX+/Ki67-, expression levels of CDKN2A, lamin B1, IL-1a/b, IL-6, G/M-CSF, IFN-g, and KC) at 3 and 10 days after pro-senescent gamma irradiation. Clear differences were found between PTEC from different strains with the highest senescence values for PTEC from WSB mice and the lowest for PTEC from 129S1 mice. PTEC from B6 mice, the most commonly used inbred strain in senescence research, had a senescence score lower than PTEC from WSB and CAST mice but higher than PTEC from NZO and 129S1 mice. These data provide new information regarding the influence of genetic diversity and help explain heterogeneity in existing data. The observed differences should be considered when designing new experiments and will be the basis for further investigation with the goal of identifying candidate loci driving pro- or anti-senescent pathways.