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Background: Macrophages contribute to epithelial-mesenchymal transition (EMT) in diabetic nephropathy (DN). Exosomal long non-coding RNAs (lncRNAs) derived from macrophages play a major role in transmitting biological information, whereas related studies on DN are rare. Here we investigated the effects of exosomal lncRNAs from high glucose-treated macrophages on EMT., Methods: High glucose-treated macrophage exosomes (HG-exos) were extracted by coprecipitation and stabilized. Then, mouse renal tubular epithelial cells were treated with HG-exos for 24 h. Expression of E-cadherin, α-smooth muscle actin (α-SMA), and fibronectin was detected by western blotting, qPCR, and immunofluorescence. High-throughput sequencing was then applied to analyze the bioinformatics of HG-exos., Results: HG-exos inhibited the proliferation of tubular epithelial cells. Additionally, HG-exos markedly upregulated α-SMA and fibronectin expression and downregulated E-cadherin expression in tubular epithelial cells, indicating EMT induction. A total of 378 differentially expressed lncRNAs and 674 differentially expressed mRNAs were identified by high-throughput sequencing of HG-exos. Bioinformatics analysis and subsequent qPCR validation suggested 27 lncRNAs were enriched in the EMT-related MAPK pathway. Among them, ENSMUST00000181751.1, XR_001778608.1, and XR_880236.2 showed high homology with humans., Conclusion: Exosomes from macrophages induce EMT in DN and lncRNAs in exosomes enriched in the MAPK signaling pathway may be the possible mechanism., (© 2023. The Author(s).)

Introduction: Diabetic kidney disease (DKD) is one of the complications of diabetes; however, the pathogenesis is not yet clear. A recent study has shown that senescence is associated with the course of DKD. In the present study, we explored whether senescent renal tubular cells promote renal tubulointerstitial fibrosis by secreting Sonic hedgehog (Shh) which mediates fibroblast activation and proliferation in DKD., Methods: A 36-week-old db/db mice model and the renal tubular epithelial cells were cultured in high glucose (HG, 60 mmol/L) medium for in vivo and in vitro experiments., Results: Compared to db/m mice, blood glucose, microalbuminuria, serum creatinine, urea nitrogen, and UACR (microalbuminuria/urine creatinine) were markedly increased in db/db mice. Collagen III, monocyte chemoattractant protein-1 (MCP-1), and tumor necrosis factor-alpha (TNF-α) were also increased in db/db mice kidneys, suggesting fibrosis and inflammation in the organ. Moreover, the detection of SA-β-galactosidase (SA-β-Gal) showed that the activity of SA-β-Gal in the cytoplasm of renal tubular epithelial cells increased, and the cell cycle inhibition of the expression of senescence-related gene cell cycle inhibitor p16 INK 4 A protein and p21 protein increased, indicating that renal fibrosis in db/db mice was accompanied by cell senescence. Furthermore, Shh is highly expressed in the injured renal tubules and in the kidney tissue of db/db mice, as detected by enzyme-linked immunosorbent assay (ELISA). The results of immunofluorescence staining showed increased positive staining for Shh in renal tubular epithelial cells of db/db mice and decreased positive staining for Lamin B1, but increased positive staining for γH2A.X in cells with high Shh expression; similar results were obtained in vitro . In addition, HG stimulated renal tubular epithelial cells to secrete Shh in the supernatant of the medium. D-gal treatment of renal tubular epithelial cells increased the protein levels of Shh and p21. We also found enhanced activation and proliferation of fibroblasts cultured with the supernatant of renal tubular epithelial cells stimulated by HG medium but the proliferative effect was significantly diminished when co-cultured with cyclopamine (CPN), an inhibitor of the Shh pathway., Discussion: In conclusion, HG induces renal tubular epithelial cell senescence, and the secretion of senescence-associated proteins and Shh mediates inflammatory responses and fibroblast activation and proliferation, ultimately leading to renal fibrosis., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Wang, Yin, Chen, Tan, Liang, Xiang, Zhang, Zhou, Deng, Guo and Wang.)

Background: Studies have shown oxidative stress and apoptosis are the main pathogenic mechanisms of renal ischemia/reperfusion (IR) injury (IRI). Genistein, a polyphenolic non-steroidal compound, has been extensively explored in oxidative stress, inflammation and apoptosis. Our research aims to reveal the potential role of genistein on renal IRI and its potential molecular mechanism both in vivo and in vitro., Methods: In vivo experiments, mice were pretreated with or without genistein. Renal pathological changes and function, cell proliferation, oxidative stress and apoptosis were measured. In vitro experiments, overexpression of ADORA2A and knockout of ADORA2A cells were constructed. Cells proliferation, oxidative stress and apoptosis were analyzed., Results: Our results in vivo showed that the renal damage induced by IR was ameliorated by genistein pretreatment. Moreover, ADORA2A was activated by genistein, along with inhibition of oxidative stress and apoptosis. The results in vitro showed that genistein pretreatment and ADORA2A overexpression reversed the increase of apoptosis and oxidative stress in NRK-52E cells induced by H/R, while the knockdown of ADORA2A partially weakened this reversal from genistein treatment., Conclusions: Our results demonstrated that genistein have a protective effect against renal IRI by inhibiting oxidative stress and apoptosis via activating ADORA2A, presenting its potential use for the treatment of renal IRI.

Diabetic nephropathy (DN) is thought to be the major cause of end-stage renal disease. Due to its complicated pathogenesis and the low efficacy of DN treatment, a deep understanding of new etiological factors may be useful. Ferroptosis, a nonapoptotic form of cell death, is characterized by the accumulation of iron-dependent lipid peroxides to lethal levels. Ferroptosis-triggered renal tubular injury is reported to participate in the development of DN, and blocking ferroptosis might be an effective strategy to prevent the development of DN. Quercetin (QCT), a natural flavonoid that is present in a variety of fruits and vegetables, has been reported to ameliorate DN. However, its underlying nephroprotective mechanism is unclear. Herein, we explored the antiferroptosic effect of QCT and verified its nephroprotective effect using DN mice and high glucose (HG)-incubated renal tubular epithelial cell models. We found HG-induced abnormal activation of ferroptosis of renal tubular epithelial cells, and QCT treatment inhibited ferroptosis by downregulating the expression of transferrin receptor 1 (TFR-1) and upregulating the expression of glutathione peroxidase 4 (GPX4), ferritin heavy chain 1 (FTH-1), and the cystine/glutamate reverse antiporter solute carrier family 7 member (SLC7A11) in DN mice and HG-incubated HK-2 cells. Subsequently, both in vitro and in vivo results confirmed that QCT activated the NFE2-related factor 2 (Nrf2)/Heme oxygenase-1(HO-1) signaling pathway by increasing the levels of Nrf2 and HO-1. Therefore, this study supports that QCT inhibits the ferroptosis of renal tubular epithelial cells by regulating the Nrf2/HO-1 signaling pathway, providing a novel insight into the protective mechanism of QCT in DN treatment.

Renal tubular epithelial cells (TECs) are vulnerable to mitochondrial dysregulation, which is an integral part of diabetic kidney disease (DKD). We found that CD36 knockout ameliorated mitochondrial dysfunction and diabetic kidney injury in mice, improved renal function, glomerular hypertrophy, tubular injury, tubulointerstitial fibrosis, and kidney cell apoptosis. Furthermore, CD36 knockout conferred protection against diabetes-induced mitochondrial dysfunction and restored renal tubular cells and mitochondrial morphology. CD36 knockout also restored mitochondrial fatty acid oxidation (FAO) and enhanced FAO-associated respiration in diabetic TECs. CD36 was found to alter cellular metabolic pathways in diabetic kidneys partly via PDK4 the -AMPK axis inactivation. Because CD36 protects against DKD by improving mitochondrial function and restoring FAO, it can serve as a potential therapeutic target.

Aim Apoptosis is one of the most important mechanisms underlying renal tubulointerstitial fibrosis. We identified a role of protein Peroxiredoxin 1 ( Prx1) in protecting apoptosis occurred in tubular epithelial cells of the rat and human kidney. Methods Immunohistochemistry ( IHC) staining was used to detect Prx1 expression in kidney derived from unilateral-ureteral obstruction ( UUO) rats or patients with obstructive nephropathy. Modulation of Prx1 expression by transfecting siRNA and overexpression plasmid approach were carried out in NRK-52 E (rat kidney tubular epithelial cell line) cells. UUO-induced apoptosis was determined using TUNEL assay. Results Immunohistochemistry staining showed that Prx1 expressed in the cytoplasm of renal tubular epithelial cells, in the kidneys of UUO rats. The reduction was confirmed by both IHC and real-time polymerase chain reaction following a course of renal tubulointerstitial fibrosis in UUO rats and a decrease of Prx1 occurred concomitantly with an elevation of TUNEL-positive cells. Fluorofenidone ( AKF-PD), a new anti-tubulointerstitial fibrotic agent, attenuated Prx1 reduction in UUO rats. Furthermore, hydrogen peroxide ( H2O2)-derived oxidative stress activated p38 MAPK, and induced apoptosis in NRK-52 E cells; knockdown of Prx1 sensitized both events in NRK-52 E cells, and overexpression of Prx1 diminished the apoptosis and the phosphorylation of p38 Conclusion Downregulation of Prx1 occurred in renal tubular epithelial cells of UUO rats and patients with obstructive nephropathy. Prx1 may alleviate the pathogenesis by inhibiting H2O2-induced apoptosis via inhibiting the p38 MAPK pathway. Prx1 may represent a useful target for a protective therapy towards renal tubulointerstitial fibrosis. [ABSTRACT FROM AUTHOR]

Background/Aims: Defective tissue repair underlies renal tissue degeneration during chronic kidney disease (CKD) progression. Unbalanced presence of TGF-β opposes effective cell proliferation and differentiation processes, necessary to replace damaged epithelia. TGF-β also retains arrested cells in a fibrotic phenotype responsible for irreversible scarring. In order to identify prospective molecular targets to prevent the effect of TGF-β during CKD, we studied the signaling pathways responsible for the antiproliferative effect of this cytokine. Methods: Tubule epithelial HK2 and MDCK cells were treated with TGF-β (or not as control) to study cell proliferation (by MTT), cell signaling (by Western blot), cell cycle (by flow cytometry) and apoptosis (DNA fragmentation). Results: TGF-β fully activates the ALK-5 receptor pathway, whereas it has no effect on the ALK-1 and MAPK pathways in both HK2 and MDCK cells. Interestingly, TGF-β exerts an antiproliferative effect only on MDCK cells, through a cytostatic effect in G0/G1. Inhibition of the ALK-5 pathway with SB431542 prevents the cytostatic effect of TGF-β on MDCK cells. Conclusion: Activation of the ALK-5 pathway is not sufficient for the antiproliferative effect of TGF-β. The presence of undetermined permissive conditions or absence of undetermined inhibitory conditions seems to be necessary for this effect. The ALK-5 pathway appears to provide targets to modulate fibrosis, but further research is necessary to identify critical circumstances allowing or inhibiting its role at modulating tubule epithelial cell proliferation and tubule regeneration in the context of CKD progression. © 2015 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Recent evidence showed that peroxisome proliferator-activated receptor γ (PPARγ) ameliorates a variety of inflammatory conditions. The present study aimed to investigate the role of PPARγ in regulating NOD-like receptor family, pyrin domain containing 3 (NALP3) inflammasome and interleukin (IL)-1β levels during monosodium urate (MSU) crystal-induced inflammation. HK-2 cells were incubated with or without 200 µg/ml MSU crystals, and mRNA and protein levels of PPARγ were determined using reverse t ranscription quantitative polymerase chain reaction and western blot analysis, respectively. To verify the role of PPARγ, HK-2 cells were pre-treated with PPARγ agonist pioglitazone, and the levels of NALP3 inflammasome and IL-1β were detected by western blot analysis and ELISA. The results showed that MSU crystals increased PPARγ expression in HK-2 cells at 24 h, while the expression decreased to normal levels at 48 h. It was also demonstrated that although the PPARγ agonist pioglitazone did not alter the mRNA and protein levels of PPARγ, it significantly reduced the MSU crystal-induced production of NALP3 inflammasome and IL-1β in HK-2 cells, possibly by increasing the level of PPARγ activity. In conclusion, the results of the present study indicated that PPARγ prevented NALP3 inflammasome formation and IL-1β production in HK-2 cells stimulated by MSU crystals, which indicated that PPARγ may represent a novel target for the treatment of hyperuricemic nephropathy. [ABSTRACT FROM AUTHOR]

Renal fibrosis is an inevitable outcome of end-stage chronic kidney disease. During this process, epithelial cells lose E-cadherin expression. β-Catenin may act as a mediator by accumulation and translocation to the nucleus. Studies have suggested that CIP4, a Cdc42 effector protein, is associated with β-catenin. However, whether CIP4 contributes to E-cadherin loss in epithelial cells by regulating β-catenin translocation is unclear. In this study, we investigated the involvement of CIP4 in β-catenin translocation. Expression of CIP4 was upregulated in renal tissues of 5/6 nephrectomized rats and mainly distributed in renal tubular epithelia. In TGF-β1-treated NRK-52E cells, upregulation of CIP4 expression was accompanied by reduced expression of E-cadherin. CIP4 overexpression promoted the translocation of β-catenin to the nucleus, which was accompanied by reduced expression of E-cadherin even without TGF-β1 stimulation. In contrast, CIP4 depletion by using siRNA inhibited the translocation of β-catenin to the nucleus and reversed the decrease in expression of E-cadherin. The interaction between CIP4 and β-catenin was detected. We also show that β-catenin depletion could restore the expression of E-cadherin that was suppressed by CIP4 overexpression. In conclusion, these results suggest that CIP4 overexpression represses E-cadherin expression by promoting β-catenin translocation to the nucleus. [ABSTRACT FROM AUTHOR]

Background: The pathophysiology of Cardiorenal Syndrome Type 1 (CRS1) is widely studied, although the mechanisms by which renal tubular epithelial cells (TECs) cease to proliferate and embark upon terminal differentiation, following the initial insult of heart failure (HF), remain a key target. This study seeks to provide insight into the pathophysiological pathways in CRS1; we evaluated in vitro the effects of CRS1 plasma on TECs. Methods: We enrolled 40 acute HF patients and 15 controls (CTR) without HF or acute kidney injury (AKI). Ten out of 40 HF patients exhibited AKI at the time of admission for HF or developed AKI during hospitalization and were classified as CRS1. In vitro, cell viability, DNA fragmentation and caspase-3 levels were investigated in TECs incubated with HF, CRS1, and CTR plasma. We assessed inflammatory cytokines and NGAL expression at the gene and protein levels. Results: We observed a marked pro-apoptotic activity and a significantly increased in vitro level of apoptosis in TECs incubated with plasma from CRS1 patients compared to HF and CTR (p < 0.01). In the CRS1 group, the mRNA expression of IL-6, IL-18 and NGAL resulted significantly higher in TECs incubated with CRS1 plasma compared with those incubated with plasma from HF and CTR (p < 0.01). IL-6, IL-18, NGAL, and RANTES levels were significantly higher in TECs supernatant incubated with CRS1 plasma compared with HF patients and CTR plasma (p < 0.01). Conclusion: In vitro exposure to plasma from CRS1 patients altered the expression profile of TECs characterized by increases in proinflammatory mediators, release of tubular damage markers, and apoptosis. © 2015 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Curcumin has been observed to exhibit an anti-fibrotic effect in the liver, lung and gallbladder. However, the mechanisms underlying the cytoprotective effects of curcumin remain to be elucidated. The epithelial-to-mesenchymal transition (EMT) of mature tubular epithelial cells in the kidney is considered to contribute to the renal accumulation of matrix proteins associated with diabetic nephropathy. The EMT is also closely associated with the progression of renal interstitial fibrosis and oxidative stress. This process may occur through abrogation of high glucose (HG)-induced oxidative stress via activation of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and heme oxygenase-1 (HO-1) in kidney tubular epithelial cells. In the present study, the effect of curcumin on HG-induced EMT in the NRK-52E normal rat kidney tubular epithelial cell line was investigated, and whether the effect of curcumin was mediated by the induction of Nrf2 and HO-1 expression was examined. The present study revealed that curcumin was able to prevent events associated with EMT, including the downregulation of E-cadherin and the increased expression of α-smooth muscle actin. Further analysis revealed that the expression levels of Nrf2 and HO-1 protein were elevated to a greater extent in the curcumin pretreated NRK-52E cells compared with those of the control. Notably, knockdown of Nrf2 with small interfering RNA prevented the curcumin-induced elevation in expression of HO-1 and the associated anti-fibrotic effects. In conclusion, the present findings suggested that curcumin may be significant in cellular antioxidant defense, through the activation of Nrf2 and HO-1, thereby protecting the NRK-52E cells from HG-induced EMT. [ABSTRACT FROM AUTHOR]

Objective To investigate the effects of artesunate (Art) on cell apoptosis, tumor necrosis factor-alpha (TNF-α) and interleukin-8 (IL-8) expression induced by high glucose in rat renal tubular epithelial cells (NRK-52E). Methods NRK-52E cells were cultured and divided into normal control group, high glucose group, high glucose with different concentrations of Art (10 mg/L, 20 mg/L and 30 mg/L) groups, and high glucose with Ena (5 mg/L) group. MTT assay was used to detect the cell proliferation. The apoptotic rate was evaluated by flow cytometry with AnnexinV-FITC/PI double stains. The protein levels of TNF-a and IL-8 in the cell culture supernatant were determined using ELISA. Results High glucose inhibited NRK-52E proliferation, induced its apoptosis, and the expressions of TNF-α and IL-8 in the supernatant. Application of Art obviously abolished the effects of high glucose, and the effects of Art were showed in dose-dependent manner. Conclusion Art can suppress high glucose-stimulated cell apoptosis, enhance TNF-α and IL-8 expression in NRK-52E cells. The anti-inflammatory action and immune regulation of Art could be a novel approach of treating diabetic nephropathy. [ABSTRACT FROM AUTHOR]

New Findings: What is the central question of this study? Activation of the glycogen synthase kinase 3 β (GSK-3β)-hypoxia-inducible factor 1 α (HIF-1α) pathway results in stimulation of pyroptosis under high glucose, and exerts actions in a number renal diseases: does this pathway have a role in renal tubular epithelial cells? What is the main finding and its importance? Down-regulation of GSK-3β can inhibit pyroptosis of renal tubular epithelial cells induced by high glucose and this may be related to down-regulation of HIF-1α. This role of the GSK-3β-HIF-1α pathway has not previously been reported and identifies a potential new therapeutic target in diabetic nephropathy., Abstract: Diabetic nephropathy (DN) is not only one of the main complications of diabetes, but also has a high incidence rate and a high mortality rate. Glycogen synthase kinase 3 β (GSK-3β) and hypoxia-inducible factor 1 α (HIF-1α) have been demonstrated to influence DN by regulating pyroptosis. This study aimed to investigate the effect of the GSK-3β-HIF-1α pathway on pyroptosis of high-glucose (HG)-induced renal tubular cells. Mouse renal proximal tubular epithelial cells (TKPT cells) were induced by HG to simulate DN cell and we transfected TKPT cells with GSK-3β knockdown lentivirus. Western blot analysis confirmed the transfection effects and detected the expression of GSK-3β, HIF-1α, Nod-like receptor protein 3 (NLRP3), cleaved-caspase-1, pro-caspase-1, gasdermin D (GSDMD) and GSDMD-N. The expression of GSDMD-N and HIF-1α were also verified by immunofluorescence. The levels of interleukin (IL)-1β and IL-18 were measured by enzyme linked immunosorbent assay. Flow cytometric analysis determined the apoptosis rate. Results showed that HIF-1α expression was increased in HG-induced TKPT cells, and GSK-3β knockdown could decrease the levels of NLRP3, cleaved-caspase-1, GSDMD-N and HIF-1α, verified by immunofluorescence. Moreover, GSK-3β knockdown suppressed the expression of IL-1β and IL-18, and reduced the apoptosis rate. Lithium chloride (LiCl) interference could cause the same changes as GSK-3β knockdown for HG-induced TKPT cells, and dimethyloxallyl glycine could reverse the effect of GSK-3β-knockdown interference. Our studies definitively demonstrate that the GSK-3β-HIF-1α signalling pathway mediates HG-stimulated pyroptosis in renal tubular epithelial cells and that down-regulation of GSK-3β inhibited HG-induced pyroptosis by inhibiting the expression of HIF-1α. These findings suggest a new potential target for the treatment of DN., (© 2022 The Authors. Experimental Physiology © 2022 The Physiological Society.)

Vanadium (V) is a common environmental and industrial pollutant that can cause nephrotoxicity in animals in excess. The purpose of this research was to explore the interaction between endoplasmic reticulum (ER) stress and autophagy induced by V in the kidney of ducks. Duck renal tubule epithelial cells were exposed to different concentrations of sodium metavanadate (NaVO 3) (0, 100 and 200 μM) and PERK inhibitor (GSK, 1 μM), or autophagy inhibitor (chloroquine, 50 μM) alone for 24 h (chloroquine for the last 4 h). The results showed that exposure to V caused the dilatation and swelling of the ER and intracellular calcium overload, and upregulated PERK, eIF2α, ATF4 and CHOP mRNA levels and p-PERK and CHOP protein levels associated with ER stress in cells. Additionally, V markedly increased the number of autophagosomes, acidic vesicular organelles (AVOs) and LC3 puncta, as well as the mRNA levels of Beclin1, Atg5, Atg12, LC3A and LC3B and protein levels of Beclin1, Atg5 and LC3B-II/LC3B–I, but decreased the imRNA and protein levels of p62. Moreover, treatment with the PERK inhibitor ameliorated the changed factors above induced by V, but the V-induced variation of ER-stress related factors were aggravated after treatment with the autophagy inhibitor. Together, our data suggested that excessive V could induce ER stress and autophagy in duck renal tubular epithelial cells. ER stress might promote V-induced autophagy via the PERK/ATF4/CHOP signaling pathway, and autophagy may play a role in alleviating ER stress induced by V. [Display omitted] • Vanadium (V) has toxic effect on duck renal tubular epithelial cells. • V could induce endoplasmic reticulum (ER) stress via PERK/ATF4/CHOP pathway. • V could trigger autophagy in duck renal tubular epithelial cells. • ER stress might promote V-induced autophagy, and autophagy may play a role in alleviating ER stress induced by V. [ABSTRACT FROM AUTHOR]

Environmental pollution often releases multiple contaminants resulting in as yet largely uncharacterized additive toxicities. Cadmium (Cd) is a widespread pollutant that induces nephrotoxicity in animal models and humans. However, the combined effect of Cd in causing nephrotoxicity with 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), a typical congener of polybrominated diphenyl ethers (PBDEs), has not been evaluated and mechanisms are not completely clear. Here, we applied transcriptome sequencing analysis to investigate the combined toxicity of Cd and BDE-47 in the renal tubular epithelial cell lines HKCs. Cd or BDE-47 exposure decreased cell viability in a dose-dependent manner, and exhibited cell swelling and rounding similar to necrosis, which was exacerbated by co-exposure. Transcriptomic analysis revealed 2191, 1331 and 3787 differentially-expressed genes following treatment with Cd, BDE-47 and co-exposure, respectively. Interestingly, functional annotation and enrichment analyses showed involvement of pathways for oxidative stress, NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome and inflammatory cell death for all three treatments. Examination of indices of mitochondrial function and oxidative stress in HKC cells showed that the levels of reactive oxygen species (ROS), malondialdehyde (MDA) and intracellular calcium ion concentration [Ca2+]i were elevated, while superoxide dismutase (SOD) and mitochondrial membrane potential (MMP) were decreased. The ratio of apoptotic and necrotic cells and intracellular lactate dehydrogenase (LDH) release were increased by Cd or BDE-47 exposure, and was aggravated by co-exposure, and was attenuated by ROS scavenger N-Acetyl- L -cysteine (NAC). NLRP3 inflammasome and pyroptosis pathway-related genes of NLRP3, adaptor molecule apoptosis-associated speck-like protein (ASC), caspase-1, interleukin-18 (IL-18) and IL-1β were elevated, while gasdermin D (GSDMD) was down-regulated, and protein levels of NLRP3, cleaved caspase-1 and cleaved GSDMD were increased, most of which were relieved by NAC. Our data demonstrate that exposure to Cd and BDE-47 induces mitochondrial dysfunction and triggers NLRP3 inflammasome and GSDMD-dependent pyroptosis leading to nephrotoxicity, and co-exposure exacerbates this effect, which could be attenuated by inhibiting ROS. This study provides a further mechanistic understanding of kidney damage, and co-exposure impact is worthy of concern and should be considered to improve the accuracy of environmental health assessment. [Display omitted] • Cd and BDE-47 decreased cell viability and posed an additive effect. • Differentially-expressed genes were generated greater in co-exposure. • Oxidative stress, inflammasome complex, pyroptosis and necroptosis were induced. • Co-exposure enhanced mitochondrial dysfunction and oxidative/antioxidative imbalance. • NLRP3 inflammasome and pyroptosis were activated and attenuated by NAC. [ABSTRACT FROM AUTHOR]

The objective of the study was to observe whether connexin 43 (Cx43) could regulate epithelial mesenchymal transformation (EMT) of renal tubular epithelial cells (RTECs) by influencing Akt/mTOR signaling pathway, and whether ASV could inhibit the development of renal interstitial fibrosis by regulating Cx43. Lentivirus infection was transfected into RTECs with the final concentration of 50 × PFU/ cell to regulate the expression of Cx43. And RTECs were intervened by different doses of Astragaloside IV (ASV). After synchronous culture of RTECs in each group，the expression levels of EMT-related indicators and Cx43 were detected by fluorescence microscope and Western-Blotting (WB), even the protein expressions and phosphorylation levels of AKT and mTOR in different groups were detected by WB. When the expression of Cx43 in RTECs was regulated by lentivirus infection, the degree of EMT induced by TGF‑β1 and the phosphorylation level of Akt and mTOR were changed accordingly, indicating that Akt/mTOR pathway might be a downstream molecular mechanism by which Cx43 could regulate EMT. After intervention with different doses of ASV, the expression level of Cx43 increased with obvious concentration dependence, and the expression levels of p-Akt and p- mTOR were significantly altered, suggesting that ASV could effectively increase the protein expressions of TGF‑β1-induced Cx43 in RTECs and inhibit the phosphorylation levels of Akt and mTOR. Cx43 were the main material basis of RTECs' injury, and ASV could inhibit TGF-β1- induced RTECs' transdifferentiation. In-depth study of the mechanism might provide a broad application prospect for the treatment of renal interstitial fibrosis. • Cx43 is the main material basis of functional injury in RTECSs. • Akt/mTOR pathway is a downstream molecular mechanism by which Cx43 regulates the occurrence of EMT. • ASV could inhibit TGF-β1 induced RTECs transdifferentiation. [ABSTRACT FROM AUTHOR]

Tubular epithelial-to-mesenchymal transition (EMT) plays a crucial role in the progression of renal tubular interstitial fibrosis (TIF), which subsequently leads to chronic kidney disease (CKD) and eventually, end-stage renal disease (ESRD). We propose that augmenter of liver regeneration (ALR), a member of the newly discovered ALR/Erv1 protein family shown to ameliorate hepatic fibrosis, plays a similar protective role in renal tubular cells and has potential as a new treatment option for CKD. Here, we showed that recombinant human ALR (rhALR) inhibits EMT in renal tubular cells by antagonizing activation of the transforming growth factor-β1 (TGF-β1) signaling pathway. Further investigation revealed that rhALR suppresses the expression of TGF-β receptor type II (TβR II) and significantly alleviates TGF-β1-induced phosphorylation of Smad2 and nuclear factor-κB (NF-κB). No apparent adverse effects were observed upon the addition of rhALR alone to cells. These findings collectively suggest that ALR plays a role in inhibiting progression of renal tubular EMT, supporting its potential utility as an effective antifibrotic strategy to reverse TIF in CKD. [ABSTRACT FROM AUTHOR]

Notch1 plays an important role in the regulation of immune responses and epithelial-mesenchymal transdifferentiation ( EMT). Previous studies have observed inflammatory cell infiltration and tubulointerstitial fibrosis in the renal biopsies from patients with HBV-associated glomerulonephritis ( HBV- GN). We hypothesized that Notch1 may be involved in the progression of HBV- GN. In this study, we evaluated the distribution of Notch1 in patients with HBV- GN. Our results showed that Notch1 was mainly distributed in renal tubules and the interstitial area, and the expression levels of Notch1 had a positive correlation with the renal tubular pathology. In this respect, we used human proximal tubular epithelial cells ( HK-2) as target cells, which were transiently transfected with the hepatitis B virus X ( HBx) gene using a eukaryotic vector. HBx expression resulted in significantly increased detection of Notch1, alpha-smooth muscle actin (α- SMA), major histocompatibility complex- II ( MHC-II), CD40 and interleukin-4 ( IL-4). At the same time, E-cadherin and interferon-γ ( IFN-γ) expression levels were significantly inhibited. These HBx-induced phenotypes were exacerbated by upregulation of Notch1. Knock-down of Notch1 by specific sh RNA caused decreases of α- SMA, MHC- II, CD40 and IL-4, and increases of E-cadherin and IFN-γ. These findings suggest that Notch1 is significantly associated with renal tubular and interstitial lesions. Notch1 can mediate HBx-induced EMT of HK-2 cells, promote HBx-induced increases in immune molecule expression and exacerbation of cytokine disorders, which may contribute to the progression of HBV- GN. Inhibitors of Notch1 signalling may be useful as new therapeutics for the treatment of HBV- GN. [ABSTRACT FROM AUTHOR]

Pattern recognition receptors (PRRs) are now recognized to be key triggers of injury in a variety of renal diseases. Several families of these receptors are present in the kidney, and recent data suggest that they are differentially expressed and regulated in the kidney. This study evaluated the interaction between two distinct PRRs that are expressed in the kidney, i.e. TLR2 (Toll-like receptor 2) and the NLRP3 inflammasome. The regulation and activation of these receptors in primary renal tubular epithelial (RTE) cells from murine kidneys were evaluated. RTE cells were extracted from WT and NLRP3-mutant mice and treated ex vivo with ligands specific for TLR2 or NLRP3. We found that TLR2 upregulated NLRP3 as well as its substrate IL-1β, and that signaling through the NLRP3 inflammasome induced RTE cell necrosis. The results of this study suggest a previously unknown interaction between TLR2 and NLRP3 in primary RTE cells and highlight the importance of the cross talk that occurs in kidney-related PRRs. Understanding how PRRs are regulated is important for the design of rationale therapeutic strategies to modulate these receptors in renal disease. © 2014 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

The article discusses a study which shows the role of down-regulated miR-15a in mediating the epithelial-mesenchymal transition (EMT) in renal tubular epithelial cells promoted by high glucose (HG). The researchers identified the down-regulation of miR-15a which was accompanied with the HG-induced EMT. The study indicates the possible role of the weakening regulation on the AP4 expression by miR-15a in HG-induced EMT in renal tubular epithelial cells.

The aim of this study was to investigate the effect of benazepril on the transdifferentiation of renal tubular epithelial cells from diabetic rats. Thirty male Sprague-Dawley rats were included in the present study. Eight of the 30 rats were randomly selected and served as the normal control group (N group), while the remaining 22 rats, injected with streptozotocin (STZ), comprised the diabetic rat model. Rats with diabetes were randomly divided into the diabetic (DM group) and benazepril (B group) groups. The total course was conducted over 12 weeks. Blood glucose, body weight, kidney/body weight, 24-h urinary protein, serum creatinine and blood urea nitrogen were measured at the start and end of the study. We observed the tubulointerstitial pathological changes, and applied immunohistochemistry and western blotting to detect the expression of α-smooth muscle actin (α-SMA) in renal tissue. The levels of blood glucose, kidney/body weight, 24-h urinary protein, serum creatinine, blood urea nitrogen and tubulointerstitial damage index (TII) in the DM group were significantly higher than that in the N group (p < 0.01). Except for blood glucose and kidney/body weight, the remaining indices were lower in the B group compared with those in the DM group (p < 0.01). Immunohistochemical staining results revealed the expression of α-SMA in renal tubular epithelial cells to be significantly higher in the DM and B groups compared with the control (N) group (p < 0.01). Western blot analysis revealed that the expression of α-SMA in diabetic renal tissue increased 3.27-fold compared with that of the N group, while the expression of α-SMA in the B group decreased 45% compared with that in the DM group. In conclusion, benazepril significantly reduced the expression of α-SMA in renal tubular epithelial cells obtained from diabetic rats, inhibited the transdifferentiation of renal tubular epithelial cells and played an important role in kidney protection. [ABSTRACT FROM AUTHOR]

The aim of the present study was to examine the effects of epithelial-mesenchymal transition (EMT) and apoptosis of renal tubular epithelial cells on the prognosis of immunoglobulin A (IgA) nephropathy. Renal biopsy tissues from 74 cases of IgA nephropathy were divided into a mild mesangial proliferation group (27 cases), a focal hyperplasia group (28 cases) and a proliferative sclerosis group (19 cases). The blood pressure, serum creatinine and 24 h urinary protein excretion of all patients were detected. To define EMT, α-smooth muscle actin (α-SMA), vimentin and collagen fibers were assessed. Apoptosis was determined by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL). The blood pressure, serum creatinine and 24 h urinary protein excretion of patients with IgA nephropathy altered with increasing pathological grade. All clinical indices of patients in the proliferative sclerosis group were higher than those of the other two groups, and the 24 h urinary protein excretion of the focal hyperplasia group was statistically higher than that of the mild mesangial proliferation group. The expression of tubular interstitial α-SMA, vimentin and collagen fibers increased with the pathological grade and was closely correlated with clinical indices, including collagen fibers and 24 h urinary protein excretion. TUNEL-positive cells increased with the exacerbation of pathological changes. The EMT and apoptosis of renal tubular epithelial cells reflected the clinical severity of IgA nephropathy. α-SMA, vimentin and the apoptotic index may be used as important markers for evaluating the prognosis of IgA nephropathy. [ABSTRACT FROM AUTHOR]

Background & Aims: Chronic liver disease is characterized by fibrosis that may progress to cirrhosis. Nucleotide oligomerization domain 2 (Nod2), a member of the Nod-like receptor (NLR) family of intracellular immune receptors, plays an important role in the defense against bacterial infection through binding to the ligand muramyl dipeptide (MDP). Here, we investigated the role of Nod2 in the development of liver fibrosis. Methods: We studied experimental cholestatic liver disease induced by bile duct ligation or toxic liver disease induced by carbon tetrachloride in wild type and Nod2 −/− mice. Results: Nod2 deficiency protected mice from cholestatic but not toxin-induced liver injury and fibrosis. Most notably, the hepatic bile acid concentration was lower in Nod2 −/− mice than wild type mice following bile duct ligation for 3weeks. In contrast to wild type mice, Nod2 −/− mice had increased urinary excretion of bile acids, including sulfated bile acids, and an upregulation of the bile acid efflux transporters MRP2 and MRP4 in tubular epithelial cells of the kidney. MRP2 and MRP4 were downregulated by IL-1β in a Nod2 dependent fashion. Conclusions: Our findings indicate that Nod2 deficiency protects mice from cholestatic liver injury and fibrosis through enhancing renal excretion of bile acids that in turn contributes to decreased concentration of bile acids in the hepatocyte. [Copyright &y& Elsevier]

Hyperglycemia is a characteristic of diabetic nephropathy, inducing renal tubular cell apoptosis by eliciting oxidative stress and inflammation. Zinc (Zn) is known as an essential trace element in many enzymes and proteins involved in antioxidant defenses, electron transport, and exerting antiapoptotic or cytoprotective effects. In this study, the underlying mechanisms involved in the protective effects of Zn on high glucose-induced cytotoxicity were explored using cultured renal tubular epithelial cells (NRK-52E). The authors discovered that Zn supplementation inhibited high glucose (HG)-induced NRK-52E cell apoptosis by attenuating reactive oxygen species production, inhibiting HG-induced caspase-3 and caspase-9 activation, and inhibiting the release of cytochrome c from mitochondria to the cytosol. Further analysis revealed that Zn supplementation facilitated cell survival through increasing nuclear translocation of NF-E2-related factor 2 (Nrf2), leading to increased regulation of levels of two antioxidant enzymes, hemeoxygenase-1 and glutamate cysteine ligase, which provided an adaptive survival response against the HG-induced oxidative cytotoxicity. Moreover, the Zn-mediated increases in Nrf2 activity were suppressed by the pharmacological inhibition of Akt or extracellular signal-regulated kinase 1/2. Taken together, these findings suggest that Zn antiapoptosis capacity through the activation of Akt and ERK signal pathways leads to Nrf2 activation and, subsequently, Nrf2 target gene induction, thereby protecting the NRK-52E cells from HG-induced apoptosis. [ABSTRACT FROM AUTHOR]

Objective: Ubiquitin-specific protease 4 (USP4) facilitates the development of transforming growth factor-beta 1 (TGF-β1)-induced epithelial-mesenchymal transition (EMT) in various cancer cells. Moreover, EMT of renal tubular epithelial cells (RTECs) is required for the progression of renal interstitial fibrosis. However, the role of USP4 in EMT of RTECs remains unknown. The present study aimed to explore the effect of USP4 on the EMT of RTECs as well as the involved mechanism., Methods: In established unilateral ureteral obstruction (UUO) rats and NRK-52E cells, immunohistochemistry and Western blot assays were performed., Results: USP4 expression was increased significantly with obstruction time. In NRK-52E cells stimulated by TGF-β1, USP4 expression was increased in a time-dependent manner. In addition, USP4 silencing with specific siRNA indicated that USP4 protein was suppressed effectively. Meanwhile, USP4 siRNA treatment restored E-cadherin and weakened alpha smooth muscle actin (α-SMA) expression, indicating that USP4 may promote EMT. After treatment with USP4 siRNA and TGF-β1 for 24 h, the expression of TGF-β1 receptor type I (TβRI) was decreased., Conclusion: USP4 promotes the EMT of RTECs through upregulating TβRI, thereby facilitating renal interstitial fibrosis. These findings may provide a potential target of USP4 in the treatment of renal fibrosis., (© 2022. Huazhong University of Science and Technology.)

Acute kidney injury (AKI) is defined as a pathological condition in which the glomerular filtration rate decreases rapidly over a short period of time, resulting in changes in the physiological function and tissue structure of the kidney. An increasing amount of evidence indicates that there is an inseparable relationship between acute kidney injury and chronic kidney disease (CKD). With the progress in research in this area, researchers have found that the recovery of AKI may also result in the occurrence of CKD due to its own maladaptation and other potential mechanisms, which involve endothelial cell injury, inflammatory reactions, progression to fibrosis and other pathways that promote the progress of the disease. Based on these findings, this review summarizes the occurrence and potential mechanisms of maladaptive repair in the progression of AKI to CKD and explores possible treatment strategies in this process so as to provide a reference for the inhibition of the progression of AKI to CKD.