Ginsenoside Rg1 protects human renal tubular epithelial cells from lipopolysaccharide-induced apoptosis and inflammation damage

Ginsenoside Rg1, one of the most notable active components of Panax ginseng, has been widely reported to exert anti-inflammatory actions. This study aimed to reveal whether ginsenoside Rg1 also exhibits beneficial roles against lipopolysaccharide (LPS)-induced apoptosis and inflammation in human renal tubular epithelial cells, and to evaluate the potential role of the component on tubulointerstitial nephritis treatment. HK-2 cells were treated with various doses of ginsenoside Rg1 (0, 50, 100, 150, and 200 μM) in the absence or presence of 5 μg/mL LPS. Thereafter, CCK-8 assay, flow cytometry, western blot, migration assay, reactive oxygen species (ROS) assay, and ELISA were carried out to respectively assess cell viability, apoptosis, migration, ROS activity, and the release of inflammatory cytokines. As a result, ginsenoside Rg1 protected HK-2 cells from LPS-induced injury, as cell viability was increased, cell apoptosis was decreased, and the release of MCP-1, IL-1β, IL-6, and TNF-α was reduced. Ginsenoside Rg1 functioned to HK-2 cells in a dose-dependent manner, and the 150 μM dose exhibited the most protective functions. Ginsenoside Rg1 had no significant impact on cell migration and ROS activity, while it alleviated LPS-induced ROS release and migration impairment. Furthermore, the down-regulations of p-PI3K, p-AKT, and up-regulations of PTEN, p-IκBα, p-p65, Bcl-3 induced by LPS were recovered to some extent after ginsenoside Rg1 treatment. In conclusion, ginsenoside Rg1 protects HK-2 cells against LPS-induced inflammation and apoptosis via activation of the PI3K/AKT pathway and suppression of NF-κB pathway.

Oxidative Stress-Activated NHE1 Is Involved in High Glucose-Induced Apoptosis in Renal Tubular Epithelial Cells

PURPOSE: Diabetic nephropathy (DN) is a prevalent chronic microvascular complication of diabetes mellitus involving disturbances in electrolytes and the acid-base balance caused by a disorder of glucose metabolism. NHE1 is a Na+/H+ exchanger responsible for keeping intracellular pH (pHi) balance and cell growth. Our study aimed to investigate roles of NHE1 in high glucose (HG)-induced apoptosis in renal tubular epithelial cells. MATERIALS AND METHODS: Renal epithelial tubular cell line HK-2 was cultured in medium containing 5 mM or 30 mM glucose. Then, cell apoptosis, oxidative stress, NHE1 expression, and pHi were evaluated. NHE1 siRNA and inhibitor were used to evaluate its role in cell apoptosis. RESULTS: HG significantly increased cell apoptosis and the production of reactive oxygen species (ROS) and 8-OHdG (p<0.05). Meanwhile, we found that HG induced the expression of NHE1 and increased the pHi from 7.0 to 7.6 after 48 h of incubation. However, inhibiting NHE1 using its specific siRNA or antagonist DMA markedly reduced cell apoptosis stimulated by HG. In addition, suppressing cellular oxidative stress using antioxidants, such as glutathione and N-acetyl cysteine, significantly reduced the production of ROS, accompanied by a decrease in NHE1. We also found that activated cyclic GMP-Dependent Protein Kinase Type I (PKG) signaling promoted the production of ROS, which contributed to the regulation of NHE1 functions. CONCLUSION: Our study indicated that HG activates PKG signaling and elevates the production of ROS, which was responsible for the induction of NHE1 expression and dysfunction, as well as subsequent cell apoptosis, in renal tubular epithelial cells.

2D map of proteins from human renal stone matrix and evaluation of their effect on oxalate induced renal tubular epithelial cell injury

Purpose Proteins constitute a major portion of the organic matrix of human calcium oxalate (CaOx) renal stones and the matrix is considered to be important in stone formation and growth. The present study evaluates the effect of these proteins on oxalate injured renal epithelial cells accompanied by a 2D map of these proteins. Materials and Methods Proteins were isolated from the matrix of kidney stones containing CaOx as the major constituent using EGTA as a demineralizing agent. The effect of more than 3kDa proteins from matrix of human renal (calcium oxalate) CaOx stones was investigated on oxalate induced cell injury of MDCK renal tubular epithelial cells. A 2D map of >3kDa proteins was also generated followed by protein identification using MALDI-TOF MS. Results The >3kDa proteins enhanced the injury caused by oxalate on MDCK cells. Also, the 2D map of proteins having MW more than 3kDa suggested the abundance of proteins in the matrix of renal stone. Conclusion Studies indicate that the mixture of >3kDa proteins in the matrix of human renal stones acts as promoter of calcium oxalate crystal nucleation and growth as it augments the renal epithelial cell injury induced by oxalate. The effect of promoters masks the inhibitors in the protein mixture thereby leading to enhanced renal cell injury. 2D map throws light on the nature of proteins present in the kidney stones. .

Diminution of oxalate induced renal tubular epithelial cell injury and inhibition of calcium oxalate crystallization in vitro by aqueous extract of Tribulus terrestris

PURPOSE: Recurrence and persistent side effects of present day treatment for urolithiasis restrict their use, so an alternate solution, using phytotherapy is being sought. The present study attempted to evaluate the antilithiatic properties of Tribulus terrestris commonly called as “gokhru” which is often used in ayurveda to treat various urinary diseases including urolithiasis. MATERIALS AND METHODS: The activity of Tribulus terrestris was investigated on nucleation and the growth of the calcium oxalate (CaOx) crystals as well as on oxalate induced cell injury of NRK 52E renal epithelial cells. RESULTS: Tribulus terrestris extract exhibited a concentration dependent inhibition of nucleation and the growth of CaOx crystals. When NRK-52E cells were injured by exposure to oxalate for 72 h, Tribulus terrestris extract prevented the injury in a dose-dependent manner. On treatment with the different concentrations of the plant, the cell viability increased and lactate dehydrogenase release decreased in a concentration dependent manner. CONCLUSION: The current data suggests that Tribulus terrestris extract not only has a potential to inhibit nucleation and the growth of the CaOx crystals but also has a cytoprotective role. Our results indicate that it could be a potential candidate for phytotherapy against urolithiasis.

Hypoxia Induces Connective Tissue Growth Factor mRNA Expression

Connective tissue growth factor (CTGF) is known to be a profibrotic growth factor, which mediate the fibrotic effect of transforming growth factor-beta(TGF-beta) and to stimulate cell proliferation and matrix production. CTGF has been shown to be hypoxiainducible in several cell types. Here we investigated the effect of hypoxia on CTGF gene expression in cultured mouse renal tubular cells (MTC). Quiescent cultures of MTC were exposed to hypoxia (1% O2) or normoxia in serum-free medium. The effects on hypoxia-induced CTGF expression were evaluated by Northern blot and real-time PCR. The roles of mitogen-activated protein kinase (MAPK) and TGF-beta were also determined using specific biochemical inhibitors. Exposure of quiescent tubular cells to hypoxia for 24 hr in a conditioned medium resulted in a significant increase TGF-beta. Hypoxia caused a significant increase in CTGF mRNA expression in MTC. Either JNK or ERK inhibitor did not block the hypoxia-induced stimulation of CTGF, whereas an inhibitor of p38 MAPK reduced the hypoxia-induced changes of CTGF. Although hypoxia stimulated TGF-betaproduction, neutralizing anti-TGF-beta1 antibody did not abolish the hypoxia-induced CTGF mRNA expression. The data suggest that hypoxia up-regulates CTGF gene expression, and that p38 MAPK plays a role in hypoxic-stimulation of CTGF. We also demonstrated that hypoxia induces CTGF mRNA expression via a TGF-beta1-independent mechanism.

Effective penetration of cell-permeable peptide mimic of tyrosine residue 654 domain of beta-catenin into human renal tubular epithelial cells / 华中科技大学学报（医学）（英德文版）

Phosphorylation of beta-catenin tyrosine residue 654 plays an important role in the epithelial to myofibroblast transition (EMT). Introducing mimic peptide of tyrosine residue 654 domain of beta-catenin into cells may influence phosphorylation of beta-catenin tyrosine residue 654. To deliver this mimic peptide into renal epithelial cells, we used penetratin as a vector, which is a novel cell permeable peptide, to deliver hydrophilic molecules into cells. A tyrosine 654 residue domain mimic peptide of beta-catenin (PM) with fused penetratin was constructed, purified and then detected for the penetration of the mimic peptide into human renal tubular epithelial cells (HK-2). The results showed that purified fusion mimic peptide could efficiently and rapidly translocate into human renal tubular epithelial cells. It is concluded that a cell-permeable peptides mimic of tyrosine residue 654 domain of beta-catenin was successfully obtained, which may provide a useful reagent for interfering the human renal tubular epithelial-mesenchymal transition.

Immunolocalization of anion exchanger 1 (Band 3) in the renal collecting duct of the common marmoset

The purpose of this study was to determine the expression and distribution of band 3 in the collecting duct and connecting tubules of the kidney of the marmoset monkey (Callithrix jacchus), and to establish whether band 3 is expressed in type A intercalated cells. The intracellular localization of band 3 in the different populations of intercalated cells was determined by double-labeling immunohistochemistry. Immunohistochemical microscopy demonstrated that band 3 is located in the basolateral plasma membranes of all type A intercalated cells in the connecting tubule (CNT), cortical collecting duct (CCD), and outer medullary collecting duct (OMCD) of the marmoset. However, type B intercalated cells and non-A/ non-B intercalated cells did not show band 3 labeling. Electron microscopy of the CNT, CCD and OMCD confirmed the light microscopic observation of the basolateral plasma membrane staining for band 3 in a subpopulation of interacted cells. Basolateral staining was seen on the plasma membrane and small coated vesicles in the perinuclear structure, some of which were located in the Golgi region. In addition, there was no labeling of band 3 in the mitochondria of the CNT, CCD and in OMCD cells. The intensity of the immunostaining of the basolateral membrane was less in the CNT than in the CCD and OMCD. In contrast, band 3 immunoreactivity was greater in the intracellular vesicles of the CNT. From these results, we suggest that the basolateral Cl-/HCO3- exchanger in the monkey kidney is in a more active state in the collecting duct than in the CNT.

Efecto citotóxico de la toxina Shiga tipo 2 y su subunidad B en células epiteliales tubulares renales humanas en cultivo / Cytotoxic effect of Shiga toxin type 2 and its B subunit on human renal tubular epithelial cell cultures

Escherichia coli enterohemorrágica productora de toxina Shiga (Stx) causa diarrea acuosa, colitis hemorrágica y síndrome urémico hemolítico (SUH). En Argentina, el SUH es la principal causa de insuficiencia renal en niños. El objetivo de este trabajo fue estudiar la toxicidad de Stx tipo 2 (Stx2) y su subunidad B (Stx2B) en células epiteliales tubulares renales humanas (CERH), en presencia y ausencia de factores inflamatorios. Los efectos citotóxicos se evaluaron como alteración de la funcionalidad del epitelio; daños histológicos; viabilidad celular; síntesis de proteínas y apoptosis celular. Los resultados muestran que Stx2 regula el pasaje de agua a través de CERH a tiempos menores de 1h de incubación. A tiempos mayores, hasta 72 hs, el estudio de la morfología, la viabilidad, la síntesis de proteínas y la apoptosis demostró que las CERH fueron sensibles a la acción citotóxica de Stx2 y Stx2B de una manera dosis y tiempo dependiente. Estos efectos fueron potenciados por lipopolisacáridos bacterianos (LPS), IL-1, y butirato.

The effect of connective tissue growth factor on human renal tubular epithelial cell transdifferentiation / 华中科技大学学报（医学）（英德文版）

To investigate the role of connective tissue growth factor (CTGF) in transdifferentiation of human renal tubular epithelial cell (HKC), in vitro cultured HKC cells were divided into 3 groups: negtive control, low dose CTGF-treated group (rh CTGF, 2.5 ng/ml) and high dose CTGF-treated (rhCTGF, 5.0 ng/ml). Then the expression of alpha-smooth muscle actin (alpha-SMA) were assessed by indirect immuno-fluorescence, and the percentage of alpha-SMA positive cells were assessed by flow cytometry. RT-PCR were also performed to examine the mRNA level of alpha-SMA. Upon the stimulation of different concentrations of rhCTGF, the expression of alpha-SMA were markedly stronger than that in negative controls. The percentages of alpha-SMA positive cells were significantly higher in the stimulated groups than that of negative controls (38.9%, 65.5% vs 2.4%, P<0.01). alpha-SMA mRNA levels were also up-regulated by the stimulation of rhCTGF (P<0.01). These results suggest that CTGF can promote the transdifferentiation of human renal tubular epithelial cells towards myofibroblast (Myo-F).

Heat Shock Protein Expression in Adenosine Triphosphate Depleted Renal Epithelial Cells

BACKGROUND: In this study, the putative interactions between apoptosis and heat shock proteins disturbed as a result of ATP depletion were investigated as a hypoxia model. METHODS: The direct cellular damages were assessed by the release of LDH from the cytoplasm of the human tubular epithelial cells (HK-2 cells) following ATP depletion. The Bcl-2/Bax mRNA expression ratio, used as an index to assess to what extent apoptosis contributed to tubular cell damage, and the expressions of HSP 90, 72 and 27 in relation to the Bcl-2/Bax ratio in the ischemic model, as parameters of their functional contributions to tubule cell damage, were also studied. Heat preconditioning (HS) was performed at 43 degrees in a temperature-regulated water bath for 1 h. RESULTS: The release of LDH due to ATP depletion was not significantly increased in HK-2 cells compared to the control, but was slightly increased in heat preconditioned cells compared to non heat preconditioned cells, but the difference was not statistically significant (6.33 +/- 0.57 U/L vs. 8.67 +/- 2.52 U/L, p> 0.05). The Bcl-2/ Bax mRNA expression ratio increased progressively from the control to the heat preconditioned and ATP depleted cells (control; 100%, ATP depletion; 154 +/- 6%, heat preconditioning; 212 +/- 6%, heat preconditioning and ATP depletion; 421 +/- 8%). No contribution of heat preconditioning and ATP depletion was observed on the expressions of HSP90 and HSP27. However, HSP72 expression was prominent by ATP depletion, especially after heat preconditioning. CONCLUSION: There may be a possibility that the preservation of cytolytic damage and an increase in the Bcl-2/Bax mRNA expression ratio is related to the increase of HSP72 in ATP depletion as a hypoxia model.

Aspectos celulares e moleculares da interaçäo entre cristais de oxalato de cálcio e células tubulares renais / Cell and molecular aspects of the interaction between calcium oxalate crystals and the kidney tubular cells

Nos últimos anos o emprego de técnicas de biologia celular e molecular permitiu que conceitos acerca da origem da litíase do trato urinário mudassem consideravelmente. A interaçao entre cristais de oxalato de cálcio e o epitélio tubular renal exerce importante papel na gênese dos cálculos renais. Os aspectos envolvendo a adesao destes cristais às células tubulares, desencadeando internalizaçao dos mesmos e uma resposta celular proliferativa expressiva sao aqui revistos e podem representar um novo caminho para a prevençao e o tratamento da nefrolitíase.

Effect of tissue and plasma factors on kidney proliferation

Liver extract, plasma from intact mice, ES2 tumour extract and plasma from tumour bearing mice has an inhibiting effect on the mitotic activity of hepatocytes and duodenal enterocytes. In the present experiments, the effect of these treatments on the mitotic activity of renal tubular cells was studied. C3HS 28 day-old male mice, standardized for periodicity analysis were used. The determination of normal mitotic circadian curve of the renocytes was done. A second batch of mice were injected with 0.01 ml/gr of either liver extract, plasma from intact mice, ES2 tumour extract or plasma from tumour bearing mice, at 16:00 hours and controlled at 08:00, 12:00 and 16:00 hs during 2 consecutive days post treatment. Colchicine (2 micrograms/gr) was injected 4 hours before killing. Kidneys were processed for histology and mitotic index determinations. Results were expressed as colchicine metaphases per 1000 nuclei, and showed that mitotic activity values of treated animals were significantly lower than those of controls. In conclusion, mitotic activity inhibition of renocytes may be due to some non specific plasmatic and/or tissue factors.

Rol del calcio intracelular en la nefrotoxicidad por gentamicina / Role of increased intracellular calcium in the nephrotoxicity produced by gentamicin

Recientemente se ha llamado la atención sobre el rol que tendría el aumento del calcio intracelular en el mecanismo de la injuria celular isquémica y de otras formas de injurias. Para evaluar ésta hipótesis utilizamos el modelo de daño renal tubular tóxico producido por la gentamicina. Nosotros tratamos ratas con verapamil (V) (Bloqueante de los canales de calcio), antes y después de provocarle una nefrotoxicidad por gentamicina (G) y no encontramos protección de la nefrotoxicidad observándose una disminución similar del Clearance de Creatinina (G: 0,47 ñ 0,09; G + V: 0,59 ñ 0,05 ml/min/100 g peso corporal), un incremento semejante de la excreción fraccional de sodio (G: 1,68 ñ 0,50; G + V: 1,23 ñ 0,1%) y el mismo grado de daño tubular histológico (G: 3 ñ 0,23; G + V: 2,7 ñ 0,19). El aumento de la disponibilidad de calcio extracelular, producido por la hipercalcemia inducida por vitamina D, (H), durante la producción de toxicidad renal por gentamicina, no exacerbó la injuria tubular renal como lo demuestran la misma disminución de Clearance de creatinina (G: 0,18 ñ 0,2; G + H: 0,6 ñ 0,1 ml/min/100 g peso corporal), el mismo aumento de la excreción fraccional de sodio (G: 1,25 ñ 0,2; G + H: 1,5 ñ 0,3%) y el mismo grado de daño tubular histológico (G: 1,85 ñ 0,26; G + H: 2 ñ 0,37). Nuestros resultados no apoyan la hipótesis que propone el aumento de calcio intracelular como mediador de la injuria nefrotóxica