Renal Cell Apoptosis Research Articles

Enhanced therapeutic effects of hypoxia-preconditioned mesenchymal stromal cell-derived extracellular vesicles in renal ischemic injury

BackgroundExtracellular vesicles (EVs) secreted by mesenchymal stromal cells (MSCs) have been shown to provide significant protection against renal ischemia–reperfusion injury (IRI). Hypoxia has emerged as a promising strategy to enhance the tissue repair capabilities of MSCs. However, the specific effects of hypoxia on MSCs and MSC-EVs, as well as their therapeutic potential in renal IRI, remain unclear. In this study, we investigated the alterations occurring in MSCs and the production of MSC-EVs following hypoxia pre-treatment, and further explored the key intrinsic mechanisms underlying the therapeutic effects of hypoxic MSC-EVs in the treatment of renal IRI.MethodsHuman umbilical cord MSCs were cultured under normoxic and hypoxic conditions. Proliferation and related pathways were measured, and RNA sequencing was used to detect changes in the transcriptional profile. MSC-EVs from both normoxic and hypoxic conditions were isolated and characterized. In vivo, the localization and therapeutic effects of MSC-EVs were assessed in a rat renal IRI model. Histological examinations were conducted to evaluate the structure, proliferation, and apoptosis of IRI kidney tissue respectively. Renal function was assessed by measuring serum creatinine and blood urea nitrogen levels. In vitro, the therapeutic potential of MSC-EVs were measured in renal tubular epithelial cells injured by antimycin A. Protein sequencing analysis of hypoxic MSC-EVs was performed, and the depletion of Glutathione S-Transferase Omega 1 (GSTO1) in hypoxic MSC-EVs was carried out to verify its key role in alleviating renal injury.ResultsHypoxia alters MSCs transcriptional profile, promotes their proliferation, and increases the production of EVs. Hypoxia-pretreated MSC-EVs demonstrated a superior ability to mitigate renal IRI, enhancing proliferation and reducing apoptosis of renal tubular epithelial cells both in vivo and in vitro. Protein profiling of the EVs revealed an accumulation of numerous anti-oxidative stress proteins, with GSTO1 being particularly prominent. Knockdown of GSTO1 significantly reduced the antioxidant and therapeutic effects on renal IRI of hypoxic MSC-EVs.ConclusionsHypoxia significantly promotes the generation of MSC-EVs and enhances their therapeutic effects on renal IRI. The antioxidant stress effect induced by GSTO1 is identified as one of the most critical underlying mechanisms. Our findings highlight that hypoxia-pretreated MSC-EVs represent a novel and promising therapeutic strategy for renal IRI.Graphical

Penehyclidine hydrochloride activates PARK2 and modulates ubiquitination of AIFM1 to rescue renal tubular injury in diabetic kidney disease

BackgroundRenal tubular injury (RTI) is one of the key characteristics of diabetic nephropathy (DN). Penehyclidine hydrochloride (PHC) was an anticholinergic drug with renoprotective effects, but its specific mechanism in the treatment of DN was still unclear. MethodsWe treated different diabetic mouse models and high glucose-induced RTI models by PHC. Histological analyses were performed using flow cytometry and staining, and ELISA evaluated the ROS, apoptosis, and related markers under different treatments. The molecular interactions were analyzed by ChIP, dual-luciferase reporter, and CoIP. ResultsPHC alleviated RTI by activating mitophagy and inhibiting apoptosis, and the protective effect could be rescued by PARK2 knockdown. Nrf2 bound to the promoter region of PARK2 and promoted its expression. PHC reduced the level of apoptosis by reducing the degree of nuclear translocation of AIFM1, which was rescued by PARK2 knockdown. PARK2 knockdown reduced the non-degradative ubiquitination of AIFM1, thus promoting its nuclear translocation and ultimately facilitating renal tubular cells (RTCs) apoptosis. The over-expression of AIFM1 rescued the RTCs apoptosis antagonized by PHC. ConclusionsPHC activated Nrf2 to up-regulate PARK2 transcription to induce mitophagy and inhibit apoptosis mediated by nuclear translocation of AIFM1 through promoting non-degradative ubiquitination of AIFM1, ultimately rescuing RTI in DN.

Senolytic procyanidin C1 alleviates renal fibrosis by promoting apoptosis of senescent renal tubular epithelial cells.

Renal fibrosis is a common pathological process in various chronic kidney diseases. The accumulation of senescent renal tubular epithelial cells (TECs) in renal tissues plays an important role in the development of renal fibrosis. Eliminating senescent TECs has been proven to effectively reduce renal fibrosis. Procyanidin C1 (PCC1) plays a senolytic role by specifically eliminating senescent cells and extending its overall lifespan. However, whether PCC1 can alleviate unilateral ureteral obstruction (UUO)-induced renal fibrosis and the associated therapeutic mechanisms remains unclear. Here, we observed a marked increase in senescent TECs within obstructed human renal tissue and demonstrated the positive correlation between the accumulation of senescent TECs and renal fibrosis in UUO-induced renal fibrosis in mice. We found that PCC1 reduced the number of senescent TECs, restored the regenerative phenotype in kidneys with reduced fibrosis, and improved tubular repair after UUO-induced injury. Invitro, PCC1 effectively cleared senescent HK2 cells by inducing apoptosis via ANGPTL4/NOX4 signaling. Incubation with culture medium from senescent HK2 cells promoted fibroblast activation, whereas PCC1 impeded profibrotic effects by downregulating senescence-associated secretory phenotype (SASP) factors from senescent HK2 cells. Therefore, PCC1 alleviated interstitial renal fibrosis not only by clearing senescent TECs and improving tubular repair but also by indirectly attenuating myofibroblast activation by reducing the level of SASP. In summary, PCC1 may be a novel therapeutic senolytic agent for treating renal fibrosis.

Ameliorative Effect of Biochanin A against Gentamicin-induced Nephrotoxicity in Rats

Background Gentamicin (GM), a commonly used aminoglycoside anti-biotic, is effective against various bacterial infections. However, its clinical use is often limited due to its significant nephrotoxic side effects. Nephrotoxicity results from oxidative stress, inflammation, and apoptosis of renal cells. In previous research, Biochanin A (BCA), a natural isoflavone found in various plants, has demonstrated anti-oxidant, anti-inflammatory, and anti-apoptotic properties. This study explores the potential protective effects of BCA against GM-induced nephrotoxicity. Purpose To investigate the protective effects of BCA on GM-induced nephrotoxicity in male Wistar rats by assessing kidney function, oxidative stress markers, inflammatory response, and apoptotic regulation. Methods Male Wistar rats were divided into four groups, each group containing six animals: Group 1 as the control, Group 2 received BCA alone [50 mg/kg, intraperitoneal (IP)], Group 3 received GM alone (100 mg/kg, IP), and Group 4 received BCA (50 mg/kg, IP) along with GM (100 mg/kg, IP). At the end of the experiment day (on the 12th day), the animals were sacrificed, the organs were removed, and used for the following parameters. Results GM administration significantly increased the levels of creatinine, urea, uric acid, blood urea nitrogen (BUN), and lipid peroxidation levels and decreased the levels of anti-oxidant enzymes. Administration with BCA has significantly mitigated kidney function markers and oxidative stress while enhancing anti-oxidant activities. Furthermore, GM-induced rats exhibited significant upregulation in proinflammatory cytokines, proapoptotic proteins, and downregulation of anti-apoptotic proteins. Administration of BCA significantly downregulated proinflammatory cytokines and proapoptotic proteins and upregulated anti-apoptotic proteins in GM-induced rats. These results underscore the utility of necrotic and apoptotic markers in the early detection of tubular kidney damage. Conclusion This study conclusively demonstrates that BCA protects the kidneys from GM-induced oxidative stress, inflammation, and apoptosis of renal tubular cells, offering promise for mitigating GM-induced nephrotoxicity.

Sivelestat sodium protects against renal ischemia/reperfusion injury by reduction of NETs formation.

Ischemia-reperfusion injury (IRI) often results in renal impairment. While the presence of neutrophil extracellular traps (NETs) is consistently observed, their specific impact on IRI is not yet defined. Sivelestat sodium, an inhibitor of neutrophil elastase which is crucial for NET formation, may offer a therapeutic approach to renal IRI, warranting further research. A mouse model was established for early-stage renal IRI, confirmed by injury markers and histological assessments. The involvement of NETs in renal I/R was demonstrated using immunofluorescence and Western blot. Renal function and pathology were further evaluated through a comprehensive set of methods, including Periodic Acid-Schiff staining (PAS) and Terminal Deoxynucleotidyl Transferase dUTP Nick End Labeling (TUNEL) staining, enzyme-linked immunosorbent assay (ELISA), Real time Glomerular Filtration Rate (RT-GFR) monitoring, Polymerase Chain Reaction (PCR), biochemical analysis, and additional Western blot and immunofluorescence assays. We firstly quantified NET expression in renal IRI mice, noting a peak at 24 hours. Subsequently, sivelestat sodium treatment was administered, resulting in decreased MPO, CitH3, and attenuated tubular damage. Moreover, it resulted in a decrease in serum levels of creatinine, blood urea nitrogen (BUN), as well as neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1). Additionally, it lowered the abundance of renal tissue inflammatory markers interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), and mitigated the levels of oxidative stress indicators malondialdehyde (MDA) and 4 Hydroxynonenal (4HNE), accompanied by a decline in renal cell apoptosis and an enhancement of GFR in renal I/R mice. Sivelestat sodium ameliorates renal IRI by downregulating neutrophil NETs, reducing inflammation, oxidative stress, and apoptosis, thereby enhancing renal function.

Neng-Jing-Huo Essential Oil Blend Inhibits Lipopolysaccharide-Induced Intracellular Reactive Oxygen Species Accumulation, Inflammation, and Apoptosis in Renal Tubular Epithelial Cells.

Acute kidney injury (AKI) is a common serious complication of sepsis that is characterized by the rapid deterioration of kidney function. Neng-Jing-Huo (NJH) is an essential oil blend, including Gaultheria procumbens, Zingiber officinale, Bulnesia sarmientoi, Artemisia vulgaris, and Styrax benzoin oils, with antimicrobial, antioxidant, and anti-inflammatory activities. Here, we investigated the effects of NJH on oxidative stress, inflammatory response, and apoptosis in an in vitro septic AKI model and explored the underlying mechanisms. A cellular model of septic AKI was established using lipopolysaccharide (LPS). Cell viability was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Action mechanisms of NJH were analyzed using the Griess reagent, 2',7'-dichlorodihydrofluorescein diacetate, 5,5',6,6' tetrachloro-1,1'3,3' tetraethylbenzimidazolcarbocyanine iodide, annexin V, caspase activity, western blotting, and semi-quantitative reverse transcription polymerase chain reaction assays. Results showed that pretreatment with NJH significantly improved cell survival and suppressed nitric oxide (NO) production in LPS-stimulated NRK-52E renal tubular epithelial cells. NJH also decreased the levels of intracellular reactive oxygen species and maintained the mitochondrial membrane potential by upregulating the nuclear factor (NF) erythroid 2-related factor 2/heme oxygenase-1 levels and downregulating the NADPH oxidase 4 levels. In addition, NJH suppressed the activation of the toll-like receptor 4/NF-κB and NLRP3/caspase-1 pathways, thereby decreasing the inflammatory response in LPS-stimulated NRK-52E cells. Moreover, NJH decreased the levels of Bax, caspase-9, and caspase-3 but increased those of Bcl-2, which led to a reduction in LPS-induced apoptosis. Overall, our findings revealed that NJH ameliorated LPS-induced damage in NRK-52E cells by inhibiting oxidative stress, inflammation, and apoptosis, highlighting its therapeutic potential for septic AKI.

Therapeutic Effects of Tea Polyphenols on Renal Damage Induced by High Uric Acid.

Hyperuricemia (HUA) is a condition characterized by excessive uric acid production and/or inadequate uric acid excretion due to abnormal purine metabolism in the human body. Uric acid deposits resulting from HUA can lead to complications such as renal damage. Currently, drugs used to treat HUA lack specificity and often come with specific toxic side effects. This study aimed to investigate the renal protective effects of an optimized tea polyphenol formula and allopurinol in a rat model of hyperuricemia following renal resection. The goal was to explore the mechanisms underlying these effects. Initially, a blend was formulated based on the distinctive functions of catechins, thearubigins, tea polysaccharides, and theanine. Orthogonal experiments were then employed to select a rational combination. A 5/6 renal resection rat model was successfully established, and the animals were fed a 2% oxonic acid diet to induce hyperuricemia. Urinary protein content was measured using the biuret method, and serum levels of uric acid, creatinine, and urea nitrogen were determined biochemically. Kidney pathology was examined through HE staining and renal tubulointerstitial pathological scoring. The expression of α-SMA, CD34, PCNA, and TGF-β in renal tissue was detected using immunohistochemistry. Apoptosis of renal tubular epithelial cells was assessed using the TUNEL method. Hyperuricemia markedly worsens renal damage in rats following nephrectomy, while tea polyphenols demonstrate the ability to reduce levels of blood uric acid, urea nitrogen, creatinine, and urinary protein. Additionally, tea polyphenols enhance smooth muscle proliferation in renal glomerular arterioles, prevent the loss of interstitial capillaries, alleviate apoptosis of renal tubular epithelial cells, promote their proliferation, and reduce interstitial fibrosis. A significant improvement in the severity of renal damage is observed in rats subjected to nephrectomy combined with hyperuricemia, and this effect surpasses that of allopurinol. Tea polyphenols could effectively alleviate renal damage in rats with nephrectomy combined with hyperuricemia. They demonstrate high cost-effectiveness and minimal side effects, positioning them as a promising new therapeutic option for hyperuricemia- induced renal damage.

Dahuang chuanxiong decoction against contrast-induced nephropathy: Multi-omics, crosstalk between BNIP3-mediated mitophagy and IL-17 pathway.

Contrast-induced nephropathy (CIN), also known as contrast-induced acute kidney injury (CI-AKI), represents a prevalent form of hospital-acquired renal injury. However, the mechanisms underlying its pathogenesis remain unclear. Based on our previous research findings, the Dahuang Chuanxiong decoction (DCH), composed of Radix et Rhizoma Rhei (DH) and Rhizoma Chuanxiong (CX), has demonstrated efficacy for inhibiting CI-AKI by attenuating oxidative stress and apoptosis in renal tubular epithelial cells. Despite these findings, the detailed mechanisms underlying the renoprotective actions have not been thoroughly clarified. The objective of this study was to screen potential targets and signaling pathways involved in inhibition of CI-AKI by DCH using multi-omics analysis and to verify whether the renoprotective mechanism of DCH is related to these identified targets or pathways through in vivo and in vitro experiments. Initially, we identified the components of DCH using UPLC-Q-TOF-MS. Transcriptomics and proteomics, combined with experimental validation, were used to further elucidate the molecular mechanisms of the herbal pair in CI-AKI treatment. A CI-AKI rat model was established, and the expression levels of proteins related to mitophagy and the IL-17 signaling pathway were detected in renal tissues using immunofluorescence, immunohistochemistry, and western blotting analysis to elucidate the nephroprotective effects of DCH. Additionally, siRNA was used in the HK-2 cell model to investigate the crosstalk between the mitophagy and IL-17 signaling pathways and the impact on apoptosis when these pathways were inhibited. Multi-omics results revealed that the crucial signaling pathways involved were mitophagy, the MAPK signaling pathway, and the IL-17 signaling pathway. In vivo experiments indicated that contrast media (CM) led to an increase in AKI biomarkers, with upregulated expression of Parkin, BNIP3, IL-17, and p-NF-κB. Notably, pretreatment with DCH markedly reversed the expression of these proteins. Furthermore, we confirmed the importance of IL-17-mediated inflammation in the pathogenesis of CIN in vitro. We stimulated HK-2 cells with human IL-17 recombinant protein and observed an increase in the expression of p-NF-κB. Conversely, knockdown of IL-17 receptor A (IL-17RA) on the cell membrane reduced the expression of p-NF-κB and BNIP-3 under IL-17 stimulation. Additionally, the results revealed that BNIP3 knockdown reduced p-NF-κB production and alleviated the inflammation triggered by CM. The crosstalk between the two signaling pathways was initially explored. In conclusion, these findings suggested that DCH may exert ameliorative effects on CI-AKI through a multifaceted approach, including inhibition of BNIP3-mediated mitophagy and IL-17-mediated inflammation. This study elucidated the renoprotective mechanism of DCH through transcriptomics, proteomics, and experimental validation, providing evidence for the therapeutic potential of this agent in the clinical treatment of CI-AKI.

Boeravinone C ameliorates lipid accumulation and inflammation in diabetic kidney disease by activating PPARα signaling.

The roots of Oxybaphus himalaicus Edgew. is a traditional Tibetan herbal medicine with kidney reinforcing and tonifying effects, which is commonly applied to treat nephritis. Boeravinone C has been identified as one of the primary constituents of O. himalaicus. However, the potential renal protective effects of boeravinone C remains unclear. This research aimed to investigate the protective effects of boeravinone C on diabetic kidney disease and the underlying mechanisms. Streptozotocin (100 mg/kg) was intraperitoneally injected to induce DKD in mice. High glucose (50 mM)-induced HK-2 cells were utilized to investigate the mechanisms of boeravinone C against tubular injuries in vitro. Anti-DKD activity was assessed by measuring reactive oxygen species (ROS) levels, analyzing apoptosis through flow cytometry, and evaluating inflammation, apoptosis, and FAO-related proteins via Western blotting. Additionally, serum biochemical assays, as well as histopathological and immunohistochemical analyses of kidney tissues, were performed to explore the pharmacological effects of boeravinone C. In vivo, boeravinone C administered significantly reduced the creatinine (CRE), blood urea nitrogen (BUN), triglycerides (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) levels in serum of DKD mice. In vitro, boeravinone C significantly restored the apoptosis induced by HG in HK-2 cells, which is further validated by an upregulation of the apoptosis-inhibiting protein Bcl-2, along with a decreased expression of the apoptosis-promoting proteins Bax and caspase-3. Mechanistically, boeravinone C reversed HG-induced downregulation of peroxisome proliferator-activated receptor α (PPARα) expression. As a transcription factor, elevated expression of PPARα led to upregulation of CPT1A and ACOX1, which then enhanced fatty acid oxidation (FAO) to reduce lipid accumulation in HK-2 cells. Furthermore, boeravinone C-mediated high expression of PPARα sequestered p65 subunit of NF-κB in the cytoplasm, leading to reduced expression of proinflammatory cytokines such as iNOS, TNF-α and IL-6. To verify that the therapeutic effects of boeravinone C in diabetic kidney disease (DKD) are mediated via PPARα activation, we developed a PPARα knockdown HK-2 cell line. Our findings revealed that PPARα downregulation modified biological effects of boeravinone C, especially regarding fatty acid metabolism and the inflammatory response, with significant repercussions on apoptosis. This study demonstrates that the major component boeravinone C from O. himalaicus promotes the fatty acid oxidation and suppresses inflammatory response by upregulating PPARα expression, thereby reducing apoptosis in HG-induced renal tubule cells. Consequently, boeravinone C restores tubular function in DKD mice. Collectively, this study provides a pharmacological basis for utilizing of O. himalaicus in treating DKD.

Impact of Methotrexate and 7-Hydroxymethotrexate Exposure on Renal Toxicity in Pediatric Non-Hodgkin Lymphoma.

7-Hydroxymethotrexate (7-OHMTX) is the main metabolite in plasma following high-dose MTX (HD-MTX), which may result in activity and toxicity of the MTX. Moreover, 7-OHMTX could produce crystalline-like deposits within the renal tubules under acidic conditions or induce renal inflammation, oxidative stress, and cell apoptosis through various signaling pathways, ultimately leading to kidney damage. The objectives of this study were thus to explore the exposure-safety relationship of two compounds and search the most reliable marker for predicting HDMTX nephrotoxicity. A total of 280 plasma concentration data (140 for MTX and 140 for 7-OHMTX) for 60 pediatric patients with non-Hodgkin lymphoma (NHL) were prospectively collected. Plasma MTX and 7-OHMTX concentrations were determined using a high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method. A nonlinear mixed effect model approach was used to build a joint population pharmacokinetic (PopPK) model. After validation, the model estimated the peak concentration (Cmax) and area under the curve within the initial 48 h (AUC0-48h) of the patients after drug administration by Bayesian feedback. The receiver operating characteristic (ROC) curves were generated to identify an exposure threshold associated with nephrotoxicity. A three-compartment chain model (central and peripheral compartments for MTX and central compartment 7-OHMTX) with the first-order elimination adequately characterized the invivo process of MTX and 7-OHMTX. The covariate analysis identified that the aspartate aminotransferase (AST) was strongly associated with the peripheral volume of distribution of MTX. Moreover, the Cmax of MTX and 7-OHMTX showed significant differences (p < 0.0001, p = 0.0472, respectively) among patients with or without nephrotoxicity. Similarly, individuals with nephrotoxicity also exhibited substantially higher ratio of 7-OHMTX to MTX peak concentration and the sum of MTX + 2.25 times the concentration of 7-OHMTX (p < 0.0001, p = 0.0426, respectively). By ROC analysis, the Cmax of MTX and 7-OHMTX had the greatest area under the curve (AUC) values (0.769 and 0.771, respectively). A Cmax threshold of 9.26 μmol/L for MTX or a Cmax threshold of 0.66 μmol/L for 7-OHMTX was associated with the best sensitivity/specificity for toxicity events (MTX: sensitivity = 0.886; specificity = 0.70; 7-OHMTX: sensitivity = 0.886; specificity = 0.70). We demonstrated that the Cmax of MTX and 7-OHMTX were the most reliable markers associated with nephrotoxicity and proposed a Cmax threshold of 9.26 μmol/L for MTX and 0.66 μmol/L for 7-OHMTX as the point with a high risk of nephrotoxicity. Altogether, this study may contribute to crucial insights for ensuring the safe administration of drugs in pediatric clinical practice.

Genome-wide CRISPR-based screen identifies E2F transcription factor 1 as a regulator and therapeutic target of aristolochic acid-induced nephrotoxicity.

Aristolochic Acid I (AAI) is widely present in traditional Chinese medicines derived from the Aristolochia genus and is known to cause significant damage to renal tubular epithelial cells. Genome-wide screening has proven to be a powerful tool in identifying critical genes associated with the toxicity of exogenous substances. To identify undiscovered key genes involved in AAI-induced renal toxicity, a genome-wide CRISPR library screen was conducted in the human kidney-2 (HK-2) cell line. Among the altered sgRNAs, a significant enrichment of those targeting the E2F transcription factor 1 (E2F1) gene was observed in surviving HK-2 cells in the AAI-treated group. Interestingly, the role of E2F1 had not been previously explored in studies of AAI nephrotoxicity. Further investigations revealed that E2F1 promotes apoptosis by activating the p53 signaling pathway and upregulating pro-apoptotic genes, such as BAK and BAX. Additionally, using the high-throughput experiment- and reference-guided database of traditional Chinese medicine (HERB), cannabidiol (CBD) was identified as an inhibitor of E2F1 by suppressing the activity of NF-κB pathway. In vitro and in vivo models confirmed that CBD inhibits AAI-induced upregulation of E2F1, thereby suppressing p53-mediated apoptosis. In conclusion, this study highlights the crucial role of E2F1 in AAI-induced renal cell apoptosis and identifies CBD as a novel therapeutic candidate for mitigating AAI nephrotoxicity.

Usp9x contributes to the development of sepsis-induced acute kidney injury by promoting inflammation and apoptosis in renal tubular epithelial cells via activation of the TLR4/nf-κb pathway

As a pattern recognition receptor, Toll-like receptor 4 (TLR4) is crucial for the development and progression of acute kidney injury (AKI). This study aims to explore whether the deubiquitinase Usp9x influences the TLR4/NF-B pathway to cause sepsis-induced acute kidney injury (S-AKI). The model of AKI was established in Sprague-Dawley rats using the cecal ligation and puncture (CLP) method, while renal tubular epithelial cell NRK-52E was stimulated with lipopolysaccharide (LPS) in vitro. All plasmids were transfected into NRK-52E cells according to the indicated group. The deubiquitinase of TLR4 was predicted by the online prediction software Ubibrowser. Subsequently, Western blot and Pearson correlation analysis identified Usp9x protein as a potential candidate. Co-IP analysis verified the interaction between TLR4 and Usp9x. Further research revealed that overexpression of Usp9x inhibited degradation of TLR4 protein by downregulating its ubiquitination modification levels. Both in vivo and in vitro experiments observed that interference with Usp9x effectively alleviated the inflammatory response and apoptosis of renal tubular epithelial cells (RTECs) induced by CLP or LPS, whereas overexpression of TLR4 reversed this situation. Transfection with sh-Usp9x in NRK-52E cells suppressed the expression of proteins associated with the TLR4/NF-κB pathway induced by LPS. Moreover, the overexpression of TLR4 reversed the effect of sh-Usp9x transfection. Therefore, the deubiquitinase Usp9x interacts with TLR4, leading to the upregulation of its expression through deubiquitination modification, and the activation of the TLR4/NF-κB signaling pathway, thereby promoting inflammation and apoptosis in renal tubular epithelial cells and contributing to sepsis-induced acute kidney injury.

MC-LR induced apoptosis in human embryonic kidney (HEK293) cells through activation of TNF-R1/RIPK1 pathway

ABSTRACT In recent years, the outbreak of cyanobacterial blooms has become increasingly frequent. Microcystin-LR (MC-LR), a metabolite of cyanobacteria, poses a significant threat to the ecosystem and human health. Several studies have demonstrated that MC-LR might induce renal cell apoptosis, as a consequence of tissue damage. However, the molecular mechanisms underlying MC-LR-initiated renal injury remain to be determined. This investigation aimed to determine the role of apoptosis in MC-LR-induced kidney damage and its potential underlying mechanisms using the human embryonic kidney (HEK293) cell line. The results of TUNEL and immunofluorescence assays indicated that MC-LR induced increased apoptosis in HEK293 cells. Compared to control, the mRNA expression levels of RIPK1, caspase-8, and TNF-α were elevated following incubation with MC-LR, while the mRNA expression level of Bcl-2/Bax was decreased. The protein levels of RIPK1, TNF-R1, and caspase-8 were elevated in the MC-LR-treated HEK293 cells. Data demonstrated that MC-LR induced renal cell apoptosis through activation of the TNF-R1/RIPK1 pathway, providing new insights into understanding the toxic mechanisms attributed to MC-LR.

Melanin-Deferoxamine Nanoparticles Targeting Ferroptosis Mitigate Acute Kidney Injury via RONS Scavenging and Iron Ion Chelation.

Rhabdomyolysis (RM)-induced acute kidney injury (AKI) involves the release of large amounts of iron ions from excess myoglobin in the kidneys, which mediates the overproduction of reactive species with the onset of iron overload via the Fenton reaction, thus inducing ferroptosis and leading to renal dysfunction. Unfortunately, there are no effective treatments for AKI other than supportive care. Herein, we developed a multifunctional nanoplatform (MPD) by covalently bonding melanin nanoparticles (MP NPs) to deferoxamine. The nanoplatform has good dispersion and physiological stability, excellent chelating performance to iron ions, and broad-spectrum reactive species scavenging activity. Furthermore, cellular experiments showed that the NPs possessed high biocompatibility, antiapoptotic activity, antioxidant properties, and strong scavenging capacity of Fe2+ to mitigate iron overload, protecting the intracellular mitochondria from oxidative stress. Meanwhile, the intrinsic photoacoustic imaging capability of melanin allows the real-time monitoring of MPD NPs' target uptake and metabolic behavior in healthy and AKI mice. Most importantly, MPD NPs led to downregulation of the antioxidant pathway by targeting ferroptosis, thus effectively rescuing renal function in vivo, mitigating oxidative stress and inflammatory responses, and inhibiting renal tubular cell apoptosis. The nanoplatform offers a novel therapeutic strategy for RM-induced AKI.

Apoc1 Knockdown Alleviates High Glucose-induced Oxidative Stress and Apoptosis of Renal Tubular Cells by Binding to Clusterin.

Diabetic nephropathy (DN) is a serious diabetic complication. Renal tubular damage is an important aspect of DN. Increased apolipoprotein C1 (Apoc1) has been confirmed in serum of patients with DN. The exact mechanism of Apoc1 in DN is unclear as yet. We aimed to elaborate the molecular mechanism underlying high glucose (HG)-induced renal tubular epithelial damage. In this content, a DN mouse model was established to assess renal damage. Apoc1 and Clusterin expression in renal tissue was detected using immunoblotting and immunofluorescence staining. In vitro, human kidney proximal tubular epithelial cells (HK-2 cells) were exposed to HG to simulate the DN model. After Apoc1 and/or Clusterin knockdown, HK-2 cell viability under HG conditions was detected using CCK-8 assay. DCFH-DA staining was used to examine the production of intracellular reactive oxygen species (ROS). MDA and SOD levels were tested by kits. Moreover, cell apoptosis was measured using TUNEL staining. Immunoblotting was employed to evaluate the expression of proteins. Additionally, the binding between Apoc1 and Clusterin was analyzed using co-immunoprecipitation experiments. Our data revealed that Apoc1 expression was upregulated while Clusterin expression was downregulated in renal tissue of DN mice and HG-treated HK-2 cells. Apoc1 knockdown alleviated oxidative stress and apoptosis in HG-treated HK-2 cells. Importantly, Apoc1 could bind to Clusterin and regulate Clusterin expression in HK-2 cells. Finally, Clusterin silencing blocked the influences of Apoc1 knockdown on the oxidative stress and apoptosis in HK-2 cells under HG conditions. Collectively, Apoc1 knockdown exerts potential anti-DN effects by binding to Clusterin to alleviate HG-induced renal tubular damage, suggesting that Apoc1/Clusterin can be used as a valuable therapeutic target for DN.

Rostellularia procumbens (L) Nees. extract attenuates adriamycin-induced nephropathy by maintaining mitochondrial dynamics balance via SIRT1/PGC-1α signaling pathway activation.

Rostellularia procumbens (L) Nees. (R. procumbens) is a classical Chinese herbal medicine that has been used for effective treatment of kidney disease for nearly a thousand years in China. Recently, significant progress has been achieved in understanding the abnormal mitochondrial structure and function from chronic kidney disease (CKD). However, the regulatory mechanisms underlying R. procumbens treatment for CKD and its association with dysfunctional mitochondrial function remain elusive. To study the protective effect of N-butanol extract from R. procumbens (J-NE) on chronic glomerulonephritis (CGN) mice using a mice model and mitochondrial function-related experiments. A renal injury mouse model was developed using a single tail vein injection of adriamycin (9 mg/kg). Renal pathology was analyzed through hematoxylin-eosin (HE) staining and transmission electron microscopy (TEM). Cell apoptosis in kidney tissues was analyzed using TUNEL staining. Protein levels were measured via immunohistochemistry (HIF-1α, FN, α-SMA, and Collagen I) and Western blot (Mn-SOD, p-Drp-S637, MFN1, MFN2, OPA1, TFAM, Nrf1, ATP6, SIRT1, and PGC-1α) analysis. LC-MS was used to analyze the presence of bioactive phytocompounds in J-NE. The results reported that the levels of kidney injury markers (urinary protein, glomerular atrophy, and renal cell apoptosis), mitochondrial dysfunction markers (mitochondrial ultrastructure, Mn-SOD, HIF-1α, FN and α-SMA),mitochondrial dynamic imbalance markers (p-Drp-S637, MFN1, MFN2 and OPA1) and SIRT1/PGC-1α signaling pathway markers (TFAM, Nrf1, ATP6, SIRT1, and PGC-1α) were settled to a significant improvement by the oral administration of J-NE. In conclusion, R. procumbens could be able to protect the kidneys from podocyte injury caused mitochondrial dynamics and energy metabolism dysregulation by modulating the SIRT1/PGC-1α signaling pathway.

Moringa isothiocyanate-1 mitigates the damage of oxidative stress and apoptosis in diabetic nephropathy mice.

Diabetic nephropathy (DN) is a prevalent cause of end-stage kidney disease worldwide. Moringa isothiocyanate-1 (MIC-1) has shown potential for DN management, however, the exact mechanisms remain unclear. This research intended to evaluate the impact and mechanism of MIC-1 on DN. Six C57BLKS/J-db/m mice served as controls. Eighteen C57BLKS/J-db/db mice were randomly separated into three groups: db/db, db/db + irbesartan (IBS), and db/db + MIC-1. Three weeks post-drug administration, the body weight and kidney weight of mice in each group were measured. Concurrently, serum creatinine (Scr), urine albumin, insulin, glycosylated hemoglobin (GHb), oxidative stress-, and inflammatory-related factors were determined. Additionally, the pathological injury, apoptosis, apoptosis-related markers, NLRP3, and ASC levels in the kidney tissues were examined utilizing H&E, Masson, PAS, TUNEL staining, and Western blot. MIC-1 decreased the body weight, kidney weight, the levels of Glu, Scr, and urine albumin in db/db mice. Moreover, MIC-1 significantly suppressed the levels of MDA, insulin, GHb, TNF-α, IL-1β, and IL-6, while increased the activities of SOD, CAT, and GPX in the serum of db/db mice. MIC-1 also mitigated the kidney tissue injury in db/db mice. Western blot assay showed that MIC-1 enhanced the Bcl-2 level and suppressed the Bax, cleaved caspase-3, cleaved caspase-9, NLRP3, ASC, and caspase-1 levels of the kidney tissues in db/db mice. MIC-1 ameliorated the kidney injury in DN mice, and its mechanism may be associated with the suppression of renal cell apoptosis, oxidative stress, and inflammatory responses.

The Effect of Apigenin on Renal Damage Induced by Aristolochic Acid I and the Involvement of Nrf2/HO-1 Pathway

Background Aristolochic acid is naturally found in plants of the Aristolochiaceae family and possesses antitumor, anti-infection, and anti-inflammatory properties. Purpose This study investigated the protective effect of apigenin (API) on aristolochic acid I (AAI)-induced renal damage in mice and its underlying mechanisms. Methods Male C57BL/6J mice were assigned to the control group, model group, and API low, medium, and high-dose groups (10, 20, 40 mg/kg). On the 5th day, 2 h after administration, except for the control group, all other groups were intraperitoneally injected with AAI (10 mg/kg). Following final administration, 24-h urinary protein levels, serum creatinine (Scr), and blood urea nitrogen (BUN) levels were assessed along with hematoxylin–eosin (HE) staining of kidneys and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining, as well as analysis of malondialdehyde (MDA) levels and superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity. Results When compared with the model group, mice in API treatment groups exhibited significantly reduced 24-h urinary protein levels and serum levels of Scr and BUN ( p &lt; 0.05) with an improvement in renal tissue histopathological changes and cell apoptosis as well as decreased MDA and increased SOD and GSH-Px ( p &lt; 0.05). Tumor necrosis factor alpha protein (TNF-α)/interleukin (IL)-1β/IL-6 levels showed a reduction ( p &lt; 0.05). Nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) were upregulated, while NF-κB/Cleaved Caspase-3 were downregulated ( p &lt; 0.01). Conclusion API protects against renal damage induced by AAI possibly through Nrf2/HO-1 pathway, which in turn inhibits oxidative stress damage, inflammatory responses, and cell apoptosis.

Cadmium and polyvinyl chloride microplastics induce mitochondrial damage and apoptosis under oxidative stress in duck kidney

Polyvinyl chloride microplastics (PVC-MPs) and Cadmium (Cd) are widely occurring water pollutants that interact with each other to exert toxic effects. As a waterfowl, Muscovy duck is more susceptible to PVC-MPs and Cd than land poultry. In this study, Muscovy duck was used as a research model, and 10 mg/L PVC-MPs and 50 mg/kg Cd were used alone and in combine to explore the effect on the kidney of Muscovy duck. We found that treatment of Cd or PVC-MPs alone changed the kidney weight, increased creatinine and urea nitrogen content, and disrupted oxidative balance and macro/trace element metabolism, while the combination of PVC-MPs+Cd reduced the accumulation of Cd in the kidney. In addition, treatment of Cd and PVC-MPs alone caused mitochondrial damage, increase or decrease of mitochondria-associated proteins (Fis1, Drp1, PGC-1α, Nrf1), and Nrf2 signaling pathway plays a key role in detoxification and alleviation of oxidative stress, and we found that PVC-MPs+Cd treatment recovered related proteins (Nrf2, Keap-1, HO-1, NQO1, AC-SOD2, SOD2) compared with the Cd and PVC-MPs alone treatment. Finally, we detected changes in apoptosis-related proteins and genes (Caspase-3, Caspase-9, Bax, Bcl-2, Cytc) and TUNEL staining, and after PVC-MPs+Cd treatment, apoptosis-related proteins/genes recovered and the apoptosis rate decreased compared with the Cd and PVC-MPs alone treatment. These results indicate that renal function is impaired, oxidative stress and trace element metabolism disorder, nuclear factor-E2 related factor 2 (Nrf2) is activated into the nucleus to induce the expression of related antioxidant proteins (such as HO-1, NQO1). These injuries can induce mitochondrial damage and eventually lead to renal cell apoptosis. To sum up, these evidence show that Cd or PVC-MPs can induce kidney oxidative damage, trace element metabolism disorder, mitochondrial damage and apoptosis.

New Therapeutic Method for Alleviating Damage of Acute Kidney Injury Through BCL-2 Gene Promoter I-Motif.

Acute kidney injury (AKI) is a global public health problem with its pathogenesis not fully understood. Excessive apoptosis of renal tubular epithelial cells is an important feature of AKI patients, and therefore an anti-apoptotic approach could be used in the treatment for AKI. Up-regulation of B-cell lymphoma-2 (BCL-2) gene and protein has been found to be correlated with anti-apoptosis of cells. It has been found that the presence of the C-rich sequence on the upstream region of the BCL-2 gene promoter could form DNA secondary i-motif structure, and its stabilization by small molecules could up-regulate gene transcription and translation. In the present study, we constructed AKI models through folic acid (FA) induction. With these in vitro and in vivo models, we demonstrated that the acridone derivative A22 could up-regulate the expression of BCL-2 by targeting its gene promoter i-motif to reduce renal tubular epithelial cell apoptosis and improve renal function in many ways. A22 could alleviate FA-induced oxidative stress injury, inflammatory response, and endoplasmic reticulum stress in mouse kidneys. Our results provided a potentially new anti-apoptotic approach for the treatment of early stages of AKI. Our employed model focused on its short-term effect on AKI, while its long-term efficacy and safety, particularly regarding the regeneration of renal tubular epithelial cells, require further investigation before clinical application. This study further demonstrated that promoter i-motif could be targeted for up-regulating BCL-2 expression for the treatment of important diseases caused by excessive apoptosis.