2-Deoxy-glucose ameliorates the peritoneal mesothelial and endothelial barrier function perturbation occurring due to Peritoneal Dialysis fluids exposure.

Peritoneal dialysis (PD) and prolonged exposure to PD fluids (PDF) induce peritoneal membrane (PM) fibrosis and hypervascularity, leading to functional PM degeneration. 2-deoxy-glucose (2-DG) has shown potential as PM antifibrotic by inhibiting hyper-glycolysis induced mesothelial-to-mesenchymal transition (MMT). We investigated whether administration of 2-DG with several PDF affects the permeability of mesothelial and endothelial barrier of the PM. The antifibrotic effect of 2-DG was confirmed by the gel contraction assay with embedded mesothelial (MeT-5A) or endothelial (EA.hy926) cells cultured in Dianeal® 2.5 % (CPDF), BicaVera® 2.3 % (BPDF), Balance® 2.3 % (LPDF) with/without 2-DG addition (0.2 mM), and qPCR for αSMA, CDH2 genes. Moreover, 2-DG effect was tested on the permeability of monolayers of mesothelial and endothelial cells by monitoring the transmembrane resistance (RTM), FITC-dextran (10, 70 kDa) diffusion and mRNA expression levels of CLDN-1 to -5, ZO1, SGLT1, and SGLT2 genes. Contractility of MeT-5A cells in CPDF/2-DG was decreased, accompanied by αSMA (0.17 ± 0.03) and CDH2 (2.92 ± 0.29) gene expression fold changes. Changes in αSMA, CDH2 were found in EA.hy926 cells, though αSMA also decreased under LPDF/2-DG incubation (0.42 ± 0.02). Overall, 2-DG mitigated the PDF-induced alterations in mesothelial and endothelial barrier function as shown by RTM, dextran transport and expression levels of the CLDN-1 to -5, ZO1, and SGLT2. Thus, supplementation of PDF with 2-DG not only reduces MMT but also improves functional permeability characteristics of the PM mesothelial and endothelial barrier.

Malate dehydrogenase-2 inhibition shields renal tubular epithelial cells from anoxia-reoxygenation injury by reducing reactive oxygen species.

Ischemia-reperfusion (I-R) injury is the most common cause of acute kidney injury. In experiments involving primary human renal proximal tubular epithelial cells (RPTECs) exposed to anoxia-reoxygenation, we explored the hypothesis that mitochondrial malate dehydrogenase-2 (MDH-2) inhibition redirects malate metabolism from the mitochondria to the cytoplasm, towards the malate-pyruvate cycle and reversed malate-aspartate shuttle. Colorimetry, fluorometry, and western blotting showed that MDH2 inhibition accelerates the malate-pyruvate cycle enhancing cytoplasmic NADPH, thereby regenerating the potent antioxidant reduced glutathione. It also reversed the malate-aspartate shuttle and potentially diminished mitochondrial reactive oxygen species (ROS) production by transferring electrons, in the form of NADH, from the mitochondria to the cytoplasm. The excessive ROS production induced by anoxia-reoxygenation led to DNA damage and protein modification, triggering DNA damage and unfolded protein response, ultimately resulting in apoptosis and senescence. Additionally, ROS induced lipid peroxidation, which may contribute to the process of ferroptosis. Inhibiting MDH-2 proved effective in mitigating ROS overproduction during anoxia-reoxygenation, thereby rescuing RPTECs from death or senescence. Thus, targeting MDH-2 holds promise as a pharmaceutical strategy against I-R injury.

Therapeutic Advances in Diabetic Kidney Disease.

Although sodium glucose co-transporter type 2 (SGLT-2) inhibitors were initially introduced as glucose-lowering medications, it was later discovered that cardiorenal protection is the most important treatment effect of these agents. A triad of landmark trials consistently showed the benefits of SGLT-2 inhibitors on kidney and cardiovascular outcomes in patients with chronic kidney disease (CKD), irrespective of the presence or absence of Type 2 diabetes (T2D). Furthermore, finerenone is a novel, selective, nonsteroidal mineralocorticoid receptor antagonist (MRA) that safely and effectively improved cardiorenal outcomes in a large Phase 3 clinical trial program that included >13,000 patients with T2D and a wide spectrum of CKD. These two drug categories have shared and distinct mechanisms of action, generating the hypothesis that an overadditive cardiorenal benefit with their combined use may be biologically plausible. In this article, we describe the mechanism of action, and we provide an overview of the evidence for cardiorenal protection with SGLT-2 inhibitors and the nonsteroidal MRA finerenone in patients with CKD associated with T2D.

Routes of Albumin Overload Toxicity in Renal Tubular Epithelial Cells.

Besides being a marker of kidney disease severity, albuminuria exerts a toxic effect on renal proximal tubular epithelial cells (RPTECs). We evaluated whether an unfolded protein response (UPR) or DNA damage response (DDR) is elicited in RPTECs exposed to high albumin concentration. The deleterious outcomes of the above pathways, apoptosis, senescence, or epithelial-to-mesenchymal transition (EMT) were evaluated. Albumin caused reactive oxygen species (ROS) overproduction and protein modification, and a UPR assessed the level of crucial molecules involved in this pathway. ROS also induced a DDR evaluated by critical molecules involved in this pathway. Apoptosis ensued through the extrinsic pathway. Senescence also occurred, and the RPTECs acquired a senescence-associated secretory phenotype since they overproduced IL-1ß and TGF-ß1. The latter may contribute to the observed EMT. Agents against endoplasmic reticulum stress (ERS) only partially alleviated the above changes, while the inhibition of ROS upregulation prevented both UPR and DDR and all the subsequent harmful effects. Briefly, albumin overload causes cellular apoptosis, senescence, and EMT in RPTECs by triggering UPR and DDR. Promising anti-ERS factors are beneficial but cannot eliminate the albumin-induced deleterious effects because DDR also occurs. Factors that suppress ROS overproduction may be more effective since they could halt UPR and DDR.

Interleukin Variants Are Associated with the Development and Progression of IgA Nephropathy: A Candidate-Gene Association Study and Meta-Analysis.

The interleukin-1 gene cluster encodes cytokines, which modulate mesangial cell proliferation and matrix expansion, both constituting central factors in the development and progression of immunoglobulin A nephropathy (IgAN). A candidate-gene study was performed to examine the association of polymorphisms of the interleukin-1 gene cluster with the risk of progressive IgAN. To gain deeper insights into the involvement of interleukin genes in IgAN, a meta-analysis of genetic association studies (GAS) that examine the association between interleukin variants and IgAN was conducted. Association study: The case-control study consisted of 121 unrelated Caucasians with sporadic, histologically diagnosed IgAN and of 246 age- and sex-matched healthy controls. Persistent proteinuria (>2 g/24 h) and/or impaired kidney function (serum creatinine > 1.5 mg/dL) defined progressive (n = 67) vs. non-progressive (n = 54) IgAN cases. Genotypes were assessed for two promoter-region single-nucleotide polymorphisms, C-899T (rs1800587) in IL1A and C-511T (rs16944) in IL1B, and for one penta-allelic variable-length tandem repeat polymorphism (VNTR 86 bp intron 2) in IL1RN. The association of these variants with the susceptibility of IgAN and the development of progressive IgAN (healthy status, IgAN, progressive IgAN) was tested using the generalized odds ratio (ORG) metric. Linkage disequilibrium and haplotype analysis were also performed. Meta-analysis: We included in the meta-analysis 15 studies investigating association between 14 interleukin variants harbored in eight different genes and IgAN. The ORG was used to evaluate the association between interleukin variants and IgAN using random effects models. The present case-control study revealed association of IL1B C-511T (rs16944) with the progression of IgAN (p = 0.041; ORG = 2.11 (1.09-4.07)). On haplotype analysis, significant results were derived for the haplotypes C-C-1 (p = 0.005; OR = 0.456 (0.261~0.797)) and C-T-2 (p = 0.003; OR = 4.208 (1.545-11.50)). Regarding association and meta-analysis results, variants in IL1B (rs1143627 and rs16944), IL1RN (rs928940, rs439154, and rs315951) and IL10 (rs1800871) were associated with IgAN based on either genotype or allele counts. Genetic variants and haplotypes in the IL1B, IL1RN, and IL10 genes might contribute to an increased risk for development and progression of IgAN.

Cellular communication network 2 (connective tissue growth factor) aggravates acute DNA damage and subsequent DNA damage response-senescence-fibrosis following kidney ischemia reperfusion injury.

Chronic allograft dysfunction with progressive fibrosis of unknown cause remains a major issue after kidney transplantation, characterized by ischemia-reperfusion injury (IRI). One hypothesis to account for this is that spontaneous progressive tubulointerstitial fibrosis following IRI is driven by cellular senescence evolving from a prolonged, unresolved DNA damage response (DDR). Since cellular communication network factor 2 ((CCN2), formerly called connective tissue growth factor), an established mediator of kidney fibrosis, is also involved in senescence-associated pathways, we investigated the relation between CCN2 and cellular senescence following kidney transplantation. Tubular CCN2 overexpression was found to be associated with DDR, loss of kidney function and tubulointerstitial fibrosis in both the early and the late phase in human kidney allograft biopsies. Consistently, CCN2 deficient mice developed reduced senescence and tubulointerstitial fibrosis in the late phase; six weeks after experimental IRI. Moreover, tubular DDR markers and plasma urea were less elevated in CCN2 knockout than in wild-type mice. Finally, CCN2 administration or overexpression in epithelial cells induced upregulation of tubular senescence-associated genes including p21, while silencing of CCN2 alleviated DDR induced by anoxia-reoxygenation injury in cultured proximal tubule epithelial cells. Thus, our observations indicate that inhibition of CCN2 can mitigate IRI-induced acute kidney injury, DNA damage, and the subsequent DDR-senescence-fibrosis sequence. Hence, targeting CCN2 might help to protect the kidney from transplantation-associated post-IRI chronic kidney dysfunction.

Epidemiology of Hypertension among Patients on Peritoneal Dialysis Using Standardized Office and Ambulatory Blood Pressure Recordings.

INTRODUCTION: Prior studies conducted in peritoneal dialysis (PD) patients in the late 1990s provided considerably variable estimates of the prevalence and control of hypertension. The present study aimed to investigate the current state of hypertension management in this high-risk population. METHODS: In 140 stable PD patients, we performed standardized automated office blood pressure (BP) measurements and 24-h ambulatory BP monitoring (ABPM) using the Mobil-O-Graph device (IEM, Germany). Office and ambulatory hypertension was diagnosed in patients with office BP ≥140/90 mm Hg and 24-h BP ≥130/80 mm Hg, respectively. Patients treated with ≥1 BP-lowering medications were also classified as hypertensives. RESULTS: The prevalence of office and ambulatory hypertension was 92.9% and 95%, respectively. In all, 92.1% of patients were being treated with an average of 2.4 BP-lowering medications daily. Adequate BP control was achieved in 52.3% and 38.3% of hypertensives by office BP and ABPM, respectively. The agreement between these 2 techniques in the identification of patients with BP levels above the diagnostic thresholds of hypertension was moderate (k-statistic: 0.524). In all, 5% of patients were normotensives with both techniques, 31.4% had controlled hypertension, 5% had white-coat hypertension, 19.3% had masked hypertension, and 39.3% had sustained hypertension. Isolated nocturnal hypertension was detected in 23.6% of patients, whereas no patient had isolated daytime hypertension. CONCLUSION: Among PD patients, hypertension is highly prevalent and remains often inadequately controlled. The use of ABPM enables the better classification of severity of hypertension and identification of isolated nocturnal hypertension, which is a common BP phenotype in the PD population.

Molecular Aspects of Renal Immunology: Current Status and Future Perspectives.

Kidney transplantation is the most promising treatment available for patients with end-stage kidney disease [...].

Key Genetic Components of Fibrosis in Diabetic Nephropathy: An Updated Systematic Review and Meta-Analysis.

Renal fibrosis (RF) constitutes the common end-point of all kinds of chronic kidney disease (CKD), regardless of the initial cause of disease. The aim of the present study was to identify the key players of fibrosis in the context of diabetic nephropathy (DN). A systematic review and meta-analysis of all available genetic association studies regarding the genes that are included in signaling pathways related to RF were performed. The evaluated studies were published in English and they were included in PubMed and the GWAS Catalog. After an extensive literature review and search of the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, eight signaling pathways related to RF were selected and all available genetic association studies of these genes were meta-analyzed. ACE, AGT, EDN1, EPO, FLT4, GREM1, IL1B, IL6, IL10, IL12RB1, NOS3, TGFB1, IGF2/INS/TH cluster, and VEGFA were highlighted as the key genetic components driving the fibrosis process in DN. The present systematic review and meta-analysis indicate, as key players of fibrosis in DN, sixteen genes. However, the results should be interpreted with caution because the number of studies was relatively small.

Dapagliflozin Prevents High-Glucose-Induced Cellular Senescence in Renal Tubular Epithelial Cells.

Gliflozins are a new class of antidiabetic drugs with renoprotective properties. In cultures of primary human renal tubular epithelial cells (RPTECs) subjected to high-glucose conditions in the presence or absence of dapagliflozin, we evaluated cellular senescence pathways. High glucose increased sodium-glucose cotransporter-2 (SGLT-2) expression and glucose consumption, enhancing reactive oxygen species production. The latter induced DNA damage, ataxia telangiectasia mutated kinase (ATM), and p53 phosphorylation. Stabilized p53 increased the cell cycle inhibitor p21, resulting in cell cycle arrest and increasing the cellular senescence marker beta-galactosidase (GLB-1). RPTECs under high glucose acquired a senescence-associated secretory phenotype, which was detected by the production of IL-1ß, IL-8, and TGF-ß1. By decreasing SGLT-2 expression and glucose consumption, dapagliflozin inhibited the above pathway and prevented RPTEC senescence. In addition, dapagliflozin reduced the cell cycle inhibitor p16 independently of the glucose conditions. Neither glucose concentration nor dapagliflozin affected the epithelial-to-mesenchymal transition when assessed with α-smooth muscle actin (α-SMA). Thus, high glucose induces p21-dependent RPTEC senescence, whereas dapagliflozin prevents it. Since cellular senescence contributes to the pathogenesis of diabetic nephropathy, delineating the related molecular mechanisms and the effects of the widely used gliflozins on them is of particular interest and may lead to novel therapeutic approaches.