Search Results (678)

Rhabdomyolysis is characterized by the breakdown of skeletal muscle tissue, frequently leading to acute kidney injury (AKI). Traditional conservative treatments have shown limited effectiveness in modifying the disease course, thereby necessitating targeted pharmacological approaches. Zileuton (Z), a selective inhibitor of 5-lipoxygenase (5-LOX), has demonstrated efficacy in enhancing renal function recovery in animal models of AKI induced by agents such as cisplatin, aminoglycosides, and polymyxins. The present study aimed to evaluate the therapeutic potential of a single dose of Z in mitigating rhabdomyolysis-induced AKI (RI-AKI) via modulation of myeloid-derived suppressor cells (MDSCs). Male C57BL/6 mice were assigned to four experimental groups: Sham (intraperitoneal administration of 0.9% saline), Z (single intraperitoneal injection of Z at 30 mg/kg body weight), glycerol (Gly; single intramuscular dose of 50% glycerol at 8 mL/kg), and glycerol plus Z (Z + Gly; concurrent administration of glycerol intramuscularly and Z intraperitoneally). Animals were sacrificed 24 h post-glycerol injection for analysis. Zileuton administration significantly improved renal function, as indicated by reductions in blood urea nitrogen (BUN) levels (129.7 ± 17.9 mg/dL in the Gly group versus 101.7 ± 6.8 mg/dL in the Z + Gly group, p < 0.05) and serum creatinine (Cr) levels (2.2 ± 0.3 mg/dL in the Gly group versus 0.9 ± 0.3 mg/dL in the Gly + Z group p < 0.05). Histopathological assessment revealed a marked decrease in tubular injury scores in the Z + Gly group compared to the Gly group. Molecular analyses demonstrated that Z treatment downregulated mRNA expression of macrophage-inducible C-type lectin (mincle) and associated macrophage infiltration-related factors, including Areg-1, Cx3cl1, and Cx3CR1, which were elevated 24 h following glycerol administration. Furthermore, the expression of NLRP-3, significantly upregulated post-glycerol injection, was attenuated by concurrent Z treatment. Markers of mitochondrial biogenesis, such as mitochondrial DNA (mtDNA), transcription factor A mitochondrial (TFAM), and carnitine palmitoyltransferase 1 alpha (CPT1α), were diminished 24 h after glycerol injection; however, their expression was restored upon simultaneous Z administration. Additionally, Z reduced protein levels of BNIP3, a marker of mitochondrial autophagy, while enhancing the expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), suggesting that Z ameliorates RI-AKI severity through the regulation of mitochondrial quality control mechanisms. Zileuton also decreased infiltration of CD11b(+) Gr-1(+) MDSCs and downregulated mRNA levels of MDSC-associated markers, including transforming growth factor-beta (TGF-β), arginase-1 (Arg-1), inducible nitric oxide synthase (iNOS), and iron regulatory protein 4 (Irp4), in glycerol-injured kidneys relative to controls. These markers were elevated 24 h post-glycerol injection but were normalized following concurrent Z treatment. Collectively, these findings suggest that Zileuton confers reno-protective effects in a murine model of RI-AKI, potentially through modulation of mitochondrial dynamics and suppression of MDSC-mediated inflammatory pathways. Further research is warranted to elucidate the precise mechanisms by which Z regulates MDSCs and to assess its therapeutic potential in clinical contexts. Full article

Background: Ischemia–reperfusion injury (IRI) is a major contributor to acute kidney injury (AKI). While the precise mechanisms of AKI are still incompletely defined, extensive evidence highlights tubular cell injury and death as key factors in its development. Necroptosis has recently emerged as a critical pathway in the pathogenesis of ischemia–reperfusion-induced AKI (IR-AKI). Although sex differences in susceptibility to IR-AKI have been reported, it remains unclear whether there are sex differences in necroptosis dynamics and whether these differences underlie the observed sexual dimorphism in kidney IRI. This study aimed to address these questions. Methods: male and female C57BL/6 J mice were subjected to AKI via ischemia induced by bilateral renal pedicle clamping for 18 min at 37 °C. Plasma, urine, and kidney samples were collected at 0 h, 3 h, 6 h, 12 h, 24 h, 48 h, and 72 h post-reperfusion. Kidney injury and function were assessed by measuring plasma creatinine (PCr), blood urea nitrogen (BUN) levels, and histological damage (PAS and cleaved caspase3 staining). Necroptosis activation was assessed by quantifying phosphorylated forms of key markers: p-RIPK1 and p-MLKL. To explore the role of sex hormones in regulating necroptosis dynamics, ovariectomized female mice were subjected to the same IR-AKI protocol, and their kidney injury and functional outcomes were compared with those of intact counterparts. Results: The PCr was 0.35 ± 0.04 and 0.32 ± 0.06 mg/dL for males and females, respectively, at 3 h of IR. The levels exponentially increased to 2.05 ± 0.18 at 48 h post-reperfusion in the males but only gradually to 0.94 ± 0.13 mg/dL in females. Necroptosis activation began as early as 3 h post-IR in males but was delayed until ~6 h in females. Males exhibited stronger and more sustained necroptosis activation than females, showing elevated phosphorylation levels of pRIPK1 and pMLKL in Western blot. Female sex hormone deficiency exacerbated the female response to IR-induced injury, which reduced the sex difference in the dynamic of the necroptotic activation and subsequent kidney injury. To our knowledge, this is the first study to characterize sex differences in the initiation and progression of necroptosis and subsequent injury in a mouse model of IR-AKI. Conclusions: Our findings reveal distinct temporal patterns of programmed cell death between sexes. Necroptosis-targeted therapies require early intervention in males, which can be delayed in females after IR-AKI, highlighting the need for sex-specific therapeutic windows. Full article

The rapid development of the nuclear industry and mining has increased environmental radioactive contamination, posing potentially ecological risks and health threats to humans. Uranium compounds are known to exhibit selective nephrotoxicity, but their toxicological processes and mechanisms still remain poorly understood and controversial. In this study, the uranyl-induced toxicity in human renal tubular epithelial cells (HK-2) were explored using flow cytometry, DAPI staining, and comet assays. Our results demonstrate that uranium exposure primarily triggers apoptosis. Kyoto Encyclopedia of Genes and Genomes pathway enrichment and protein–protein interaction (PPI) analyses revealed significant associations with DNA damage. Moreover, aberrant expression of ABC transporters (e.g., ABCB7) and mitochondrial-related proteins confirms uranium-induced mitochondrial dysfunction. Gene Ontology functional annotation implicated extrinsic apoptotic signaling pathways in uranium-induced cell death. The downregulation of the UBL5 protein also pointed to endoplasmic reticulum stress-mediated apoptosis. In summary, uranium exposure can induce the apoptosis of HK-2 cells through intrinsic pathways by damaging DNA and mitochondria and disrupting protein synthesis, with secondary contributions from endoplasmic reticulum stress and extrinsic apoptotic signaling. Full article

L-arginine and its derivatives L-homoarginine, asymmetric dimethylarginine (ADMA), and symmetric dimethylarginine (SDMA) show distinct (patho-) physiological properties as well as a differential renal handling. L-arginine and L-homoarginine have a lower renal clearance and are largely retained (i.e., reabsorbed) as compared to ADMA and SDMA, which are relatively enriched in the urine and excreted. To obtain a more complete picture of what is known regarding transport proteins involved in renal reabsorption and secretion of these substances, a comprehensive literature review and search of cell-specific gene expression databases were performed. Five transport proteins known to transport L-arginine and its derivatives were included, and the data available regarding their tubular expression pattern and their transport characteristics, as well as experimental and clinical data regarding their possible impact on the renal handling of L-arginine and its derivatives, are presented and discussed in a structured narrative review. Based on their transport properties and links to clinical phenotypes, b^0,+AT-rBAT and y⁺LAT1-4F2hc were identified as the most promising candidates to explain a significant part of the observed differential renal handling. This also makes them promising candidates for further investigations as mediators of possible adverse and beneficial drug effects involving L-arginine, L-homoarginine, ADMA, and SDMA. Full article

The efficient synthetic routes and evaluates cytotoxic profiles of denitroaristolochic acids II–V (DAA-II–V) were demonstrated in this study. Based on retrosynthetic analysis, a modular synthetic strategy was developed through Suzuki–Miyaura coupling, Wittig reaction, and bismuth triflate-catalyzed intramolecular Friedel–Crafts cyclization to efficiently construct the phenanthrene core. Process optimization significantly improved yields: aryl bromide intermediate A reached 50.8% yield via bromination refinement, while arylboronic ester intermediate B overcame selectivity limitations. Combining Darzens condensation with Wittig reaction enhanced throughput, achieving 88.4% yield in the key cyclization. Structures were confirmed by NMR and mass spectra. CCK-8 cytotoxicity assays in human renal proximal tubular epithelial cells revealed distinct toxicological profiles: DAA-III and DAA-IV exhibited IC₅₀ values of 371 μM and 515 μM, respectively, significantly higher than the nitro-containing prototype AA-I (270 μM), indicating that the absence of nitro group attenuates but does not eliminate toxicity, potentially via altered metabolic activation. DAA-II and DAA-V showed no detectable cytotoxicity within assay limits, suggesting reduced toxicological impact. Structure–activity analysis exhibited that the nitro group is not essential for cytotoxicity, with methoxy substituents exerting limited influence on potency. This challenges the conventional DNA adduct-dependent toxicity paradigm, implying alternative mechanisms like oxidative stress or mitochondrial dysfunction may mediate damage in denitro derivatives. These systematic findings provide new perspectives for AA analog research and a foundation for the rational use and safety assessment of Aristolochiaceae plants. Full article

Hypertension and diabetes mellitus are key contributors to kidney damage, with the renal tubule playing a central role in the progression of kidney disease. MicroRNAs have important regulatory roles in renal injury and are among the most abundant cargos within extracellular vesicles (EVs), emerging as novel kidney disease biomarkers and therapeutic tools. Previously, we identified miR-200a-3p and its target SIRT1 as having a potential role in kidney injury. We aimed to evaluate miR-200a-3p levels in EVs from patient’s urine and delve into its function in causing tubular injury. We quantified miR-200a-3p urinary EV levels in hypertensive patients with and without diabetes (n = 69), 42 of which were with increased urinary albumin excretion (UAE). We analysed miR-200a-3p levels in EVs and cellular pellets, as well as their targets at mRNA and protein levels in renal tubule cells (RPTECs) subjected to high glucose and Angiotensin II treatments, and observed their influence on apoptosis, RPTEC markers and tubular injury markers. We conducted microRNA mimic and inhibitor transfections in treated RPTECs. Our findings revealed elevated miR-200a-3p levels in increased UAE patient urinary EVs, effectively discriminating UAE (AUC of 0.75, p = 0.003). In vitro, miR-200a-3p and renal injury markers increased, while RPTEC markers, SIRT1, and apoptosis decreased under treatments. Experiments using miR-200a-3p mimics and inhibitors revealed a significant impact on SIRT1 and decrease in tubular damage through miR-200a-3p inhibition. Increased levels of miR-200a-3p emerge as a potential disease marker, and its inhibition provides a therapeutic target aimed at reducing renal tubular damage linked to hypertension and diabetes. Full article

Background and Clinical Significance: Although dietary supplements have often been deemed safe, some have been linked to drug-induced nephropathy due to their diverse ingredients. The aim of this report is to enhance clinical awareness of a novel and emerging cause of Fanconi syndrome due to red yeast rice supplements and to contribute new histopathological and clinical data. Case Presentation: We report two cases of renal dysfunction and Fanconi syndrome associated with the use of red yeast rice supplements. Both patients presented with renal impairment accompanied by elevated markers of tubular injury, hypouricemia, hypokalemia, and glucosuria, consistent with Fanconi syndrome. Following the discontinuation of the red yeast rice supplement and initiation of steroid therapy, Fanconi syndrome resolved, however, moderate renal dysfunction persisted. Urinary NGAL levels improved after treatment in both cases. KIM-1 normalized in one case but remained elevated in the other. Uromodulin recovery was complete in one case and partial in the other. Renal biopsy revealed mild tubulointerstitial nephritis, with notable shedding of proximal tubular epithelial cells. Immunohistochemical analysis demonstrated reduced expression of URAT-1, Na-K ATPase, and Na-Pi IIa in some tubules. Conclusions: These findings suggest that renal injury induced by red yeast rice supplements is mediated by direct proximal tubular necrosis caused by a harmful substance in the supplement, resulting in persistence of tubular dysfunction. Full article

Renal function refers to the combined actions of the glomerulus and tubular system to achieve homeostasis in bodily fluids. While the glomerulus is essential in the first step of urine formation through a coordinated filtration mechanism, the tubular system carries out active mechanisms of secretion and reabsorption of solutes and proteins using specific transporters in the epithelial cells. The assessment of renal function usually focuses on glomerular function, so the tubular function is often underestimated as a fundamental part of daily clinical practice. Therefore, it is essential to properly understand the tubular physiological mechanisms and their clinical association with prevalent human pathologies. This review discusses the primary solutes handled by the kidneys, including glucose, amino acids, sodium, potassium, calcium, phosphate, citrate, magnesium and uric acid. Additionally, it emphasizes the significance of physicochemical characteristics of urine, such as pH and osmolarity. The use of a concise methodology for the comprehensive assessment of urine should be strengthened in the basic training of nephrologists when dealing with problems such as water and electrolyte balance disorders, acid-base disorders, and harmful effects of commonly used drugs such as chemotherapy, antibiotics, or diuretics to avoid isolated replacement of the solute without carrying out comprehensive approaches, which can lead to potentially severe complications. Full article

Background/Objectives: Automation improves efficiency in laboratory workflow but may fail to detect clinically relevant abnormalities in patients with nephropathy. This study aimed to identify dipstick parameters associated with nephropathy-related sediment findings and to propose practical criteria to guide manual microscopy review based on these associations. Methods: Urine samples from in- and outpatients, primarily from the nephrology unit, were collected at a university hospital from July 2022 to September 2023. Samples were analyzed within two hours using LabUMat 2 and UriSed 3 analyzers. Manual microscopy was performed on all specimens by two experienced technicians. Sediments were classified as suggestive or not of nephropathy based on hematuria with dysmorphism, hyaline and pathological casts, lipiduria, or renal tubular epithelial cells. Results: Of 503 samples, 146 (29%) showed sediment findings indicative of nephropathy, which were significantly associated with dipstick positivity for protein and blood. Among nephropathy samples, 71.2% had protein ≥1+ or blood ≥2+. Using this combination as a criterion for manual sediment review yielded a sensitivity of 71.2%, a specificity of 73.9%, and a 3.84-fold increased relative risk of detecting nephropathy-related elements (p < 0.001). The criteria performed best among nephrology outpatients, with sensitivity of 79.5%, specificity of 63.9%, and relative risk of 3.91 (p < 0.001). Conclusions: Dipstick protein ≥1+ or blood ≥2+ helps identify patients who may benefit from manual sediment review, supporting diagnostic accuracy in nephropathy. Each institution should define its criteria based on patient profile, analytical methods, and workflow. Full article

Background/Objectives: Chronic kidney disease (CKD) is twice as prevalent in individuals with obesity-associated non-alcoholic fatty liver disease (Ob-NAFLD), highlighting the need to determine the link and mechanisms of kidney injury as well as explore therapies. Metformin, a first-line treatment for type 2 diabetes, shows promise in managing NAFLD, but its renal benefits in Ob-NAFLD remain unclear. This study investigates the impact of Ob-NAFLD on kidney injury and assesses the potential protective effects of metformin. Methods: Five-week-old female Zucker rats (obese fa/fa and lean Fa/Fa) were fed an AIN-93G diet for 8 weeks to induce Ob-NAFLD, then fed the diet with Metformin for 10 weeks. Kidneys were collected for histopathological and biochemical analyses. Results: Histopathological studies showed increased tubular injury, mesangial matrix expansion, and fibrosis in kidneys with Ob-NAFLD compared to lean control (LC) rats. Immunohistochemistry further revealed an elevated macrophage and neutrophil infiltration and increased levels of nitrotyrosine and p22phox in Ob-NAFLD kidneys. Furthermore, Ob-NAFLD rat kidneys showed upregulation of TNF-α and CCL2 genes and increased levels of caspase-3 (total and cleaved). Interestingly, metformin treatment significantly decreased TNF-α mRNA and blunted nitrotyrosine levels, and modestly reduced immune cell infiltration in Ob-NAFLD. Conclusions: These findings indicate that Ob-NAFLD promotes CKD as evidenced by tubular injury, oxidative stress, inflammation, and fibrosis. While short-term metformin treatment showed anti-oxidative and anti-inflammatory effects in Ob-NAFLD, its impact on structural kidney damage was limited, highlighting the need for longer treatment or alternative therapeutics such as oxidant scavengers and anti-inflammatory drugs to effectively mitigate renal pathologies. Full article

Oxidative stress plays a crucial role in disease pathogenesis. While reactive oxygen species (ROS) directly cause cellular injury, emerging evidence suggests oxidatively modified proteins like albumin may also contribute significantly to tissue damage. Although oxidized albumin (ox-Alb) is linked to renal pathology, the direct effects and mechanisms of ox-Alb on renal cell injury remain unclear. This study was created to address these questions. In mouse models of renal injury initiated by vitamin C/copper or ischemia/reperfusion, levels of serum ox-Alb were significantly elevated. The treatment of albumin with copper/vitamin C increased Alb carbonylation and reduced the number of sulfhydryl groups, causing Alb oxidation. In cultured renal tubular epithelial NRK-52E cells, ox-Alb triggered cell death, associated with increased intracellular albumin accumulation—enhanced cellular protein carbonylation, and p38 MAPK activation. Notably, ox-Alb induced ferroptosis, evidenced by decreased GPX4 and xCT, increased ACSL4, elevated iron and lipid peroxidation, and suppression by deferoxamine and liproxstatin-1. In vivo, administration of ox-Alb exacerbated doxorubicin-induced nephropathy, as indicated by the elevated BUN, creatinine, and proteinuria, and intensified renal ferroptotic responses, including altered GPX4 and ACSL4. Our findings demonstrate that ox-Alb induces renal cell ferroptosis and promotes renal disease progression, suggesting its pivotal pathogenic role in oxidative stress-related kidney diseases. Full article

Studies on populations exposed to inorganic arsenic (iAs) have shown an association with the development of chronic kidney disease (CKD) and renal cell carcinoma (RCC). However, there are few studies addressing how acute exposure of the human kidney to iAs might lead to the long-term alterations that might lead to CKD or RCC. This laboratory’s hypothesis is that renal exposure to iAs might alter the renal cells responsible for the repair and regeneration of nephrons damaged by iAs exposure or other renal toxicants. The kidney possesses a minority epithelial cell population that co-expresses PROM1 and CD24, which are believed to be involved in renal epithelial cell repair. The purpose of this work is to understand the pathogenesis of CKD in renal cortical epithelial cells. Our model consists of acute and chronic exposure of i-As (III) to “Human Renal Tubular Precursor TERT” (HRTPT). The microarray and gene validation study demonstrated a sudden induction of microfibril associated protein 5 (MFAP5) and carcinoembryonic antigen related cell adhesion molecule 5 and 6 (CEACAM 5 and 6) in chronic i-As (III)-exposed cells. Chronically exposed cells also exhibited an induction of the pAKT/AKT pathway and SOX9 transcription factor. The targeting of MFAP5 and CEACAM 5/6 could, therefore, provide a potential therapeutic approach to CKD. Full article

Arsenic, in the form of inorganic arsenite, is toxic to the kidney and can cause acute kidney injury, manifesting as destruction of proximal tubule cells. Nephron repair is possible through the proliferation of resident tubular progenitor cells expressing CD133 and CD24 surface markers. We simulated regenerative repair in the continued presence of i-As (III) using a cell culture model of a renal progenitor cell line expressing CD133 (PROM1) and CD24. Continued exposure and subculturing of progenitor cells to i-As (III) led to a reduction in the expression of PROM1 and CD24, as well as a decrease in the ability to differentiate into tubule-like structures. Cessation of i-As (III) and recovery for up to three passages resulted in continued repression of PROM1 and reduced ability to differentiate. Chronically exposed cells exhibited an ability to form colonies in soft agar, suggesting neoplastic transformation. Chronically exposed cells also exhibited an induction of CD44, a cell surface marker commonly found in renal cell carcinoma, as well as in tubular repair in chronic renal injury such as chronic kidney disease. These results demonstrate potential adverse outcomes of renal progenitor cells chronically exposed to a nephrotoxicant, as well as in environmental exposure to arsenic. Full article

Background: Renal ischemia–reperfusion injury (IRI) is a frequent cause of kidney transplant failure. Recent studies have shown that the extent of injury is closely linked to ferroptosis, and the process of cellular ferroptosis is diurnal and regulated by circadian genes. NRF2, involved in iron–heme metabolism, may be related to ferroptosis. We hypothesize that the pathway plays a role in circadian regulation in ferroptosis in renal IRI. Methods: Using hematoxylin and eosin (H&E) staining, enzyme-linked immunosorbent assay (ELISA), Cell Counting Kit-8 (CCK8), flow cytometry, real-time quantitative reverse transcription PCR (qRT-PCR), and Western blotting, we analyzed renal tubular tissues in vivo and in vitro and compared the groups with IR injury treatment, inhibition of ferroptosis, and inhibition of BMAL1 gene expression at the ZT0 (zeitgeber time 0) and ZT12 (zeitgeber time 12) time points. Results: IR injury treatments caused exacerbation of injury, both in vivo and in vitro, and were more pronounced at the ZT12 time point, which correlates with circadian rhythms. The use of the ferroptosis inhibitor (Fer-I) attenuated IR injury, suggesting that IRI is associated with ferroptosis. In contrast, reduced BMAL1-gene expression exacerbated injury, and NRF2, which is elevated in IR injury, was suppressed. Conclusions: The circadian gene BMAL1 affects the circadian rhythm of ferroptosis in renal IRI through the regulation of NRF2 and its downstream pathway. In this study, renal injury is well ameliorated by the ferroptosis inhibitor, exhibiting potential as a therapeutic agent for use in renal transplantation. Full article

Cisplatin (CIS) is a widely used chemotherapeutic agent that is highly effective against various cancers. However, its clinical application is frequently limited by its substantial nephrotoxic side effects. The gastrin-releasing peptide receptor (GRPR), a critical regulator in inflammatory diseases, has been identified as a promising therapeutic target. Our previous studies have demonstrated that the GRPR antagonists PD176252 and RH-1402 can mitigate CIS-induced nephrotoxicity through anti-inflammatory mechanisms. Based on these findings, we designed and synthesized a series of 2-arylpropanoic acid-L-tryptophan derivatives to enhance the therapeutic effects. Among these compounds, 3m exhibited superior renal protection by significantly improving mouse renal tubular epithelial cell (mRTEC) viability from 50.2 ± 2.6% to 80.5 ± 3.9%, surpassing PD176252 (70.8 ± 1.4%) and RH-1402 (73.9 ± 3.7%). Moreover, compound 3m markedly reduced the expression of kidney injury molecule-1 (KIM-1) and inflammatory cytokines [Tumor Necrosis Factor-α (TNF-α), Interleukin-6 (IL-6), Monocyte Chemoattractant Protein-1 (MCP-1)]. Finally, molecular docking results revealed that 3m exhibited a high binding affinity for GRPR. Computational predictions using SwissADME further indicated that 3m possesses favorable drug-like properties, thereby supporting its potential as a promising candidate for mitigating CIS-induced nephrotoxicity. Full article