Cytotoxicity In Epithelial Cells Research Articles

Abstract LB-393: Genotoxicity of arsenic in primary human bronchial cells

Abstract Arsenic originates from both geochemical and numerous anthropogenic activities including mining, combustion of fossil fuels, wood preservation, agriculture and metallurgy. Exposure of the general public to significant levels of arsenic is widespread. Arsenic is a well-documented human carcinogen. Long-term exposure to low levels of arsenic in drinking water have been linked to bladder, lung, kidney, liver, prostate, and skin cancer. Among them, lung cancer is of great public concern. However, little is known about how arsenic causes lung cancer. The purpose of this study was to determine the cytotoxicity and genotoxicity in human primary bronchial fibroblasts cells (NHBF). Our data show that arsenic induces a concentration-dependent increase in cell death after acute (24 h) or chronic (120 h) exposure. 0.1, 1 and 10 uM arsenic for 24 h induced 85, 64 and 35 percent relative survival, respectively, and induced 73, 57 and 11 percent of relative survival, respectively after 120 h treatment. 24 h exposure of 5 and 10 uM arsenic induced 15 and 32 chromosome damage compared to the control. Comet assay was used to measure the formation of DNA double strand breaks. We found that 120 h exposure induced a concentration-dependent increase in double strand breaks. Future study will focus on arsenic cytotoxicity and genotoxicity in primary bronchial epithelial cells. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-393. doi:1538-7445.AM2012-LB-393

Multi‐walled carbon nanotubes induce cytotoxicity and genotoxicity in human lung epithelial cells

The increasing use of nanomaterials in consumer products highlights the importance of understanding their potential toxic effects. We evaluated cytotoxic and genotoxic/oxidative effects induced by commercial multi-walled carbon nanotubes (MWCNTs) on human lung epithelial (A549) cells treated with 5, 10, 40 and 100 µg ml⁻¹ for different exposure times. Scanning electron microscopy (SEM) analysis, MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] and lactate dehydrogenase (LDH) assays were performed to evaluate cytotoxicity. Fpg-modified comet assay was used to evaluate direct-oxidative DNA damage. LDH leakage was detected after 2, 4 and 24 h of exposure and viability reduction was revealed after 24 h. SEM analysis, performed after 4 and 24 h exposure, showed cell surface changes such as lower microvilli density, microvilli structure modifications and the presence of holes in plasma membrane. We found an induction of direct DNA damage after each exposure time and at all concentrations, statistically significant at 10 and 40 µg ml⁻¹ after 2 h, at 5, 10, 100 µg ml⁻¹ after 4 h and at 10 µg ml⁻¹ after 24 h exposure. However, oxidative DNA damage was not found. The results showed an induction of early cytotoxic effects such as loss of membrane integrity, surface morphological changes and MWCNT agglomerate entrance at all concentrations. We also demonstrated the ability of MWCNTs to induce early genotoxicity. This study emphasizes the suitability of our approach to evaluating simultaneously the early response of the cell membrane and DNA to different MWCNT concentrations and exposure times in cells of target organ. The findings contribute to elucidation of the mechanism by which MWCNTs cause toxic effects in an in vitro experimental model.

Structure–Activity Relationships Imply Different Mechanisms of Action for Ochratoxin A-Mediated Cytotoxicity and Genotoxicity

Ochratoxin A (OTA) is a fungal toxin that is classified as a possible human carcinogen based on sufficient evidence for carcinogenicity in animal studies. The toxin is known to promote oxidative DNA damage through production of reactive oxygen species (ROS). The toxin also generates covalent DNA adducts, and it has been difficult to separate the biological effects caused by DNA adduction from that of ROS generation. In the current study, we have derived structure-activity relationships (SAR) for the role of the C5 substituent of OTA (C5-X = Cl) by first comparing the ability of OTA, OTBr (C5-X = Br), OTB (C5-X = H), and OTHQ (C5-X = OH) to photochemically react with GSH and 2'-deoxyguanosine (dG). OTA, OTBr, and OTHQ react covalently with GSH and dG following photoirradiation, while the nonchlorinated OTB does not react photochemically with GSH and dG. These findings correlate with their ability to generate covalent DNA adducts (direct genotoxicity) in human bronchial epithelial cells (WI26) and human kidney (HK2) cells, as evidenced by the (32)P-postlabeling technique. OTB lacks direct genotoxicity, while OTA, OTBr, and OTHQ act as direct genotoxins. In contrast, their cytotoxicity in opossum kidney epithelial cells (OK) and WI26 cells did not show a correlation with photoreactivity. In OK and WI26 cells, OTA, OTBr, and OTB are cytotoxic, while the hydroquinone OTHQ failed to exhibit cytotoxicity. Overall, our data show that the C5-Cl atom of OTA is critical for direct genotoxicity but plays a lesser role in OTA-mediated cytotoxicity. These SARs suggest different mechanisms of action (MOA) for OTA genotoxicity and cytotoxicity and are consistent with recent findings showing OTA mutagenicity to stem from direct genotoxicity, while cytotoxicity is derived from oxidative DNA damage.

Titanium dioxide nanoparticles induced cytotoxicity, oxidative stress and DNA damage in human amnion epithelial (WISH) cells

Titanium dioxide nanoparticles (TiO2-NPs) induced cytotoxicity and DNA damage have been investigated using human amnion epithelial (WISH) cells, as an in vitro model for nanotoxicity assessment. Crystalline, polyhedral rutile TiO2-NPs were synthesized and characterized using X-ray diffraction (XRD), UV–Visible spectroscopy, Fourier transform infra red (FTIR) spectroscopy, and transmission electron microscopic (TEM) analyses. The neutral red uptake (NRU) and [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) assays revealed the concentration dependent cytotoxic effects of TiO2-NPs (30.6nm) in concentration range of 0.625–10μg/ml. Cells exposed to TiO2-NPs (10μg/ml) exhibited significant reduction (46.3% and 34.6%; p<0.05) in catalase activity and glutathione (GSH) level, respectively. Treated cells showed 1.87-fold increase in intracellular reactive oxygen species (ROS) generation and 7.3% (p<0.01) increase in G2/M cell cycle arrest, as compared to the untreated control. TiO2-NPs treated cells also demonstrated the formation of DNA double strand breaks with 14.6-fold (p<0.05) increase in Olive tail moment (OTM) value at 20μg/ml concentration, vis-à-vis untreated control, under neutral comet assay conditions. Thus, the reduction in cell viability, morphological alterations, compromised antioxidant system, intracellular ROS production, and significant DNA damage in TiO2-NPs exposed cells signify the potential of these NPs to induce cyto- and genotoxicity in cultured WISH cells.

Co-exposure to nickel and cobalt chloride enhances cytotoxicity and oxidative stress in human lung epithelial cells

Nickel and cobalt are heavy metals found in land, water, and air that can enter the body primarily through the respiratory tract and accumulate to toxic levels. Nickel compounds are known to be carcinogenic to humans and animals, while cobalt compounds produce tumors in animals and are probably carcinogenic to humans. People working in industrial and manufacturing settings have an increased risk of exposure to these metals. The cytotoxicity of nickel and cobalt has individually been demonstrated; however, the underlying mechanisms of co-exposure to these heavy metals have not been explored. In this study, we investigated the effect of exposure of H460 human lung epithelial cells to nickel and cobalt, both alone and in combination, on cell survival, apoptotic mechanisms, and the generation of reactive oxygen species and double strand breaks. For simultaneous exposure, cells were exposed to a constant dose of 150 μM cobalt or nickel, which was found to be relatively nontoxic in single exposure experiments. We demonstrated that cells exposed simultaneously to cobalt and nickel exhibit a dose-dependent decrease in survival compared to the cells exposed to a single metal. The decrease in survival was the result of enhanced caspase 3 and 7 activation and cleavage of poly (ADP-ribose) polymerase. Co-exposure increased the production of ROS and the formation of double strand breaks. Pretreatment with N-acetyl cysteine alleviated the toxic responses. Collectively, this study demonstrates that co-exposure to cobalt and nickel is significantly more toxic than single exposure and that toxicity is related to the formation of ROS and DSB.

Penta-O-galloyl-β-d-glucose attenuates cisplatin-induced nephrotoxicity via reactive oxygen species reduction in renal epithelial cells and enhances antitumor activity in Caki-2 renal cancer cells

Cisplatin shows limited therapeutic efficacy due to serious side effects such as nephrotoxicity and hepatotoxicity. In the present study, we demonstrate that 1,2,3,4,6-penta-O-galloyl-β-d-glucose (PGG) has protective effects against cisplatin-induced cytotoxicity and apoptosis in normal human primary renal epithelial cells (HRCs) while showing synergistic effect against cisplatin-induced cell death in human Caki-2 renal cancer cells. PGG significantly blocked cisplatin-mediated cytotoxicity and reduced cisplatin-induced sub-G1 accumulation in HRCs. Consistently, PGG reduced the number of apoptotic cell populations by TdT-mediated dUTP nick end labeling (TUNEL) and Live/Dead assays in cisplatin-treated HRCs. Furthermore, PGG suppressed PARP cleavage and caspase-3 activation, cytochrome c release, up-regulation of bax and p53 in cisplatin-treated HRCs. Moreover, PGG attenuated reactive oxygen species (ROS) production mediated by cisplatin treatment, suggesting that PGG prevented cisplatin-induced apoptosis by inhibiting ROS generation in HRCs. Notably, PGG significantly enhanced cytotoxicity and PARP cleavage in cisplatin-treated Caki-2 renal cancer cells. Combination Index (CI) revealed synergism between PGG and cisplatin in Caki-2 cells. Taken together, our findings suggest the dual effects of PGG as a protective supplement against cisplatin-induced toxicity in normal renal cells and a combination chemotherapeutic drug with cisplatin in renal cancer cells.

Melatonin synergistically enhances cisplatin‐induced apoptosis via the dephosphorylation of ERK/p90 ribosomal S6 kinase/heat shock protein 27 in SK‐OV‐3 cells

To evaluate melatonin's ability to enhance ovarian cancer cells to cisplatin treatment for ovarian cancer, this study was performed. Melatonin by itself had no significant cytotoxicity against SK-OV-3 cells, while cisplatin suppressed the cell viability in a dose-dependent manner. Combined treatment with cisplatin and melatonin synergistically inhibited the viability of SK-OV-3 cells with the synergism between two drugs (1 > combination index). In contrast, melatonin revealed the protective effect against cisplatin-induced cytotoxicity in OSEN normal ovarian epithelial cells. Cotreatment with cisplatin and melatonin increased the sub-G1 DNA contents and TdT-mediated dUTP nick end-labeling (TUNEL)-positive cells compared with cisplatin control in SK-OV-3 cells, suggesting that melatonin augments cisplatin-induced apoptosis. Consistently, combined treatment of cisplatin and melatonin increased the cleavage of caspase-3 and poly-(ADP-ribose) polymerase (PARP). Importantly, melatonin synergistically inhibited the phosphorylation of extracellular signal-regulated kinase (ERK) along with dephosphorylation of 90-kDa ribosomal S6 kinase (p90RSK) and heat shock protein 27 (HSP27) induced by cisplatin. Furthermore, melatonin remarkably blocked the expression and colocalization of p90RSK and HSP27 by combination treatment with cisplatin. Taken together, our findings demonstrate that melatonin enhances cisplatin-induced apoptosis via the inactivation of ERK/p90RSK/HSP27 cascade in SK-OV-3 cells as a potent synergist to cisplatin treatment.

Biocompatibility and biofilm inhibition of N, N-hexyl,methyl-polyethylenimine bonded to Boston Keratoprosthesis materials

The biocompatibility and antibacterial properties of N, N-hexyl,methyl-polyethylenimine (HMPEI) covalently attached to the Boston Keratoprosthesis (B-KPro) materials was evaluated. By means of confocal and electron microscopies, we observed that HMPEI-derivatized materials exert an inhibitory effect on biofilm formation by Staphylococcus aureus clinical isolates, as compared to the parent poly(methyl methacrylate) (PMMA) and titanium. There was no additional corneal epithelial cell cytotoxicity of HMPEI-coated PMMA compared to that of control PMMA in tissue cultures in vitro. Likewise, no toxicity or adverse reactivity was detected with HMPEI-derivatized PMMA or titanium compared to those of the control materials after intrastromal or anterior chamber implantation in rabbits in vivo.

Synthesis and characterization of arginine-modified and europium-doped hydroxyapatite nanoparticle and its cell viability

The arginine-modified and europium-doped hydroxyapatite nanoparticles (HAP-Eu) were synthesized by hydrothermal synthesis. The prepared nanoparticles were characterized by transmission electron microscopy (TEM), X-ray diffractometry (XRD), Fourier transform infrared (FTIR) and zeta potential analyzer. The cell viability of HAP-Eu was tested by image flow cytometry. The results indicated that HAP-Eu is short column shapes and its size is approximately 100 nm, its zeta potential is about 30.10 mV at pH of 7.5, and shows no cytotoxicity in human epithelial cells and endothelial cells.

Proinflammatory Exoprotein Characterization of Toxic Shock Syndrome Staphylococcus aureus

Pulsed-field gel electrophoresis (PFGE) clonal type USA200 is the most widely disseminated Staphylococcus aureus colonizer of the nose and is a major cause of toxic shock syndrome (TSS). Exoproteins derived from these organisms have been suggested to contribute to their colonization and causation of human diseases but have not been well-characterized. Two representative S. aureus USA200 isolates, MNPE (α-toxin positive) and CDC587 (α-toxin mutant), isolated from pulmonary post-influenza TSS and menstrual vaginal TSS, respectively, were evaluated. Biochemical, immunobiological, and cell-based assays, including mass spectrometry, were used to identify key exoproteins derived from the strains that are responsible for proinflammatory and cytotoxic activity on human vaginal epithelial cells. Exoproteins associated with virulence were produced by both strains, and cytolysins (α-toxin and γ-toxin), superantigens, and proteases were identified as the major exoproteins, which caused epithelial cell inflammation and cytotoxicity. Exoprotein fractions from MNPE were more proinflammatory and cytotoxic than those from CDC587 due to high concentrations of α-toxin. CDC587 produced a small amount of α-toxin, despite the presence of a stop codon (TAG) at codon 113. Additional exotoxin identification studies of USA200 strain [S. aureus MN8 (α-toxin mutant)] confirmed that MN8 also produced low levels of α-toxin despite the same stop codon. The differences observed in virulence factor profiles of two USA200 strains provide insight into environmental factors that select for specific virulence factors. Cytolysins, superantigens, and proteases were identified as potential targets, where toxin neutralization may prevent or diminish epithelial damage associated with S. aureus.

MicroRNA and mRNA Expression Profiling Analysis of Dichlorvos Cytotoxicity in Porcine Kidney Epithelial PK15 Cells

Dichlorvos (DIC) is an organophosphate compound with cholinergic and noncholinergic neurotoxicity as well as non-neuronal cytotoxicity. Little is known about the mechanisms of DIC cytotoxicity in non-neuronal cells. In this study, we established a porcine kidney epithelial cell line (PK15) as a model to explore the mechanisms underlying DIC cytotoxicity based on miRNA and mRNA expression profiling analysis. We found that DIC inhibited the proliferation of PK15 cells in a dose- and time-dependent manner, which may result from apoptosis induced by DIC. Microarray analyses revealed that 16 and 14 miRNAs were significantly upregulated and downregulated in PK15 cells treated by 0.875 mM DIC for 8 h. Among the 30 differentially expressed miRNAs, 7 new miRNAs in pigs were predicted by homology-based searches. In addition, DIC upregulated 339 and downregulated 282 mRNA transcripts. A target prediction algorithm was used to analyze the pattern of differentially expressed miRNAs and mRNAs. Functional analysis indicated that these mRNAs belonged to different functional categories, forming a network participating in the DIC-induced apoptosis in PK15 cells. Therefore, our findings provide new insights into the role of miRNAs in the gene expression and function in DIC-related noncholinergic cytotoxicity.

Evaluation of protein stability and in vitro permeation of lyophilized polysaccharides-based microparticles for intranasal protein delivery

Biocompatible microparticles prepared by lyophilization were developed for intranasal protein delivery. To test for the feasibility of this formulation, stability of the incorporated protein and enhancement of in vitro permeation across the nasal epithelium were evaluated. Lyophilization was processed with hydroxypropylmethylcellulose (HPMC) or water soluble chitosan (WCS) as biocompatible polymers, hydroxypropyl-β-cyclodextrin (HP-β-CD) and d-alpha-tocopheryl poly(ethylene glycol 1000) succinate (TPGS 1000) as permeation enhancers, sugars as cryoprotectants and lysozyme as the model protein. As a result, microparticles ranging from 6 to 12 μm were developed where the maintenance of the protein conformation was verified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), circular dichroism and fluorescence intensity detection. Moreover, in vitro bioassay showed that the lysozyme activity was preserved during the preparation process while exhibiting less cytotoxicity in primary human nasal epithelial (HNE) cells. Results of the in vitro release study revealed slower release rate in these microparticles compared to that of the lysozyme itself. On the other hand, the in vitro permeation study exhibited a 9-fold increase in absorption of lysozyme when prepared in lyophilized microparticles with HPMC, HP-β-CD and TPGS 1000 (F4-2). These microparticles could serve as efficient intranasal delivery systems for therapeutic proteins.

Calcium Condensation of DNA Complexed with Cell-Penetrating Peptides Offers Efficient, Noncytotoxic Gene Delivery

Drug delivery strategies using cell-penetrating peptides (CPPs) have been widely explored to improve the intracellular delivery of a large number of cargo molecules. Electrostatic complexation of plasmid DNA using CPPs has been less explored due to the relatively large complexes formed and the low levels of gene expression achieved when using these low-molecular-weight polycations as DNA condensing agents. Here, condensing nascent CPP polyplexes using CaCl(2) produced small and stable nanoparticles leading to gene expression levels higher than observed for control polyethylenimine gene vectors. This simple formulation approach showed negligible cytotoxicity in A549 lung epithelial cells and maintained particle size and transfection efficiency even in the presence of serum.

Inhibitory effects of 6-(phenylsulfonyl)nicotinonitrile against Vibrio vulnificus infection to host (56.16)

Abstract Vibrio vulnificus is a gram-negative bacterium that is present in marine environment, and infection of the bacteria shows rapid pathological progress. V. vulnificus induces the fever, septic shock, the formation of secondary lesions, accompanied in many cases by ulcer and edema on the patients. Mortality of primary septicemia exceeds 50 % in septic patients. In this study, we examined the antimicrobial activity of 6-(phenylsulfonyl)nicotinonitrile, named U262, against V. vulnificus in vitro and in vivo. Treatment with U262 significantly inhibited the V. vulnificus-induced cytotoxicity in human intestinal epithelial INT-407 cells. U262 itself was not toxic to host cells, and did not affect the growth of the bacteria. Interestingly, U262 treatment significantly decreased the attachment of V. vulnificus to the INT-407 cells. Furthermore, the administration of U262 increased the survival period of V. vulnificus-infected mice. The numbers of viable V. vulnificus in the small intestine, liver, spleen and blood were significantly lower in the U262-treated mice, compared with those of the untreated mice. Taken together, these results demonstrate that U262 suppresses the V. vulnificus-mediated cytotoxicity in human intestinal epithelial cells, maybe via the down-regulation of bacterial attachment to the epithelial cells, and suggest that U262 can be utilized as a novel candidate in the treatment of V. vulnificus infection.

Glutamate‐gated N‐methyl‐D‐aspartate (NMDA) channels are the mechanistic link between ammonia and epithelial cell cytotoxicity in Helicobacter pylori infection

Background Ammonia (A), a cytotoxin liberated by Helicobacter pylori, is thought to play an important role in cancer development by affecting cell death mechanisms. Our aim was to determine how A is cytotoxic to gastric epithelial cells. Methods Live gastric epithelial cells were used to examine, by microscopy, changes in intracellular Ca2+, mitochondrial membrane potential, and the simultaneous localization of numerous organelle markers in the presence of A with or without specific cellular pathway inhibitors. Biochemical assays were used to quantify cell viability, ATP, protease activation, and the expression of pro-apoptotic proteins. Results A dose-dependently induced Ca2+ influx that was dependent on cAMP. A-induced Ca2+ influx reduced mitochondrial membrane potential and ATP, increased cell death effectors, and activated proteases that overall reduced the viability of gastric epithelial cells. The effects of A could be blocked completely by chelating Ca2+ or by blocking NMDA channels, which are Ca2+ influx channels, with highly specific antagonists. Conclusions Our results are the first to identify NMDA channel activity in epithelial cells, particularly in GI epithelial cells. Our data strongly support that NMDA channels regulate gastric cell viability in the presence of A, rather than other proposed mechanisms including A-induced changes in intracellular pH. Supported by NIH DK-015681.

Effect of Different Forms of Anionic Nanoclays on Cytotoxicity

Anionic nanoclays, so-called layered double hydroxide (LDH) nanoparticles, have been extensively applied as drug delivery systems, since they efficiently enter cells via endocytosis pathway and possess controlled release property. However, the stability of LDHs varies, depending on the type of interlayer anions, which can also affect their toxicity. In this study, we investigated the effects of two different forms of LDH, carbonate form (MgAl-LDH-CO3) and chloride form (MgAl-LDH-Cl), on cytotoxicity in human lung epithelial cells. The result showed that MgAl-LDH-Cl was more easily dissolved into metal ions under simulated lysosomal (pH 4.5) and body fluid (pH 7.4) conditions than did MgAl-LDH-CO3. According to cytotoxicity evaluation, MgAl-LDH-CO3 exhibited high toxicity compared with MgAl-LDH-Cl in terms of induction of oxidative stress, apoptosis and membrane damage. These results suggest that easily dissoluble MgAl-LDH-Cl has low cytotoxicity, while high stability of MgAl-LDH-CO3 is correlated to elevated cytotoxicity.

Preventive Effect of Chlorogenic Acid on Lens Opacity and Cytotoxicity in Human Lens Epithelial Cells

The present study reveals the pharmacological effect of chlorogenic acid, a major phenolic compound in plants, food, and coffee, on diabetic cataracts. Chlorogenic acid examined the inhibitory effects upon rat lens aldose reductase (AR) activity and xylose-induced rat lens opacity. The effect of chlorogenic acid on high glucose-induced cytotoxicity in lens epithelial cells was also examined. Chlorogenic acid showed potential inhibitory activity against rat lens AR, with an IC₅₀ value of 0.95 µM. The xylose-induced opacity of lenses was significantly improved after treatment with chlorogenic acid in a dose-dependent manner. Chlorogenic acid prevented high glucose-induced cytotoxicity in human lens epithelial (HLE-B3) cells in a dose-dependent manner. These results suggest that chlorogenic acid may provide a potential therapeutic approach for prevention of diabetic complications, such as cataracts.

Cytotoxicity and Induction of Inflammation by Pepsin in Acid in Bronchial Epithelial Cells

Introduction. Gastroesophageal reflux has been associated with chronic inflammatory diseases and may be a cause of airway remodelling. Aspiration of gastric fluids may cause damage to airway epithelial cells, not only because acidity is toxic to bronchial epithelial cells, but also since it contains digestive enzymes, such as pepsin. Aim. To study whether pepsin enhances cytotoxicity and inflammation in airway epithelial cells, and whether this is pH-dependent. Methods. Human bronchial epithelial cells were exposed to increasing pepsin concentrations in varying acidic milieus, and cell proliferation and cytokine release were assessed. Results. Cell survival was decreased by pepsin exposure depending on its concentration (F = 17.4) and pH level of the medium (F = 6.5) (both P < 0.01). Pepsin-induced interleukin-8 release was greater at lower pH (F = 5.1; P < 0.01). Interleukin-6 induction by pepsin was greater at pH 1.5 compared to pH 2.5 (mean difference 434%; P = 0.03). Conclusion. Pepsin is cytotoxic to bronchial epithelial cells and induces inflammation in addition to acid alone, dependent on the level of acidity. Future studies should assess whether chronic aspiration causes airway remodelling in chronic inflammatory lung diseases.

23-Hydroxytormentic Acid and Niga-Ichgoside F1 Isolated from Rubus coreanus Attenuate Cisplatin-Induced Cytotoxicity by Reducing Oxidative Stress in Renal Epithelial LLC-PK1 Cells

The unripe fruits of Rubus coreanus (Rosaceae) are used in traditional Chinese medicine to relieve kidney dysfunction. In the present study, we evaluated the protective effects of the triterpenoid glycoside niga-ichigoside F₁ (NIF₁) and of its aglycone 23-hydroxytormentic acid (23-HTA) isolated from the unripe fruits of Rubus coreanus (Rosaceae) against cisplatin-induced cytotoxicity in renal epithelial LLC-PK₁ cells. Pretreating LLC-PK₁ cells with 23-HTA or NIF₁ was found to prevent cisplatin-induced cytotoxicity and apoptosis. In addition, 23-HTA or NIF₁ pretreatment significantly improved the changes associated with cisplatin toxicity by increasing levels of glutathione (GSH) and decreasing levels of malondialdehyde (MDA) and reactive oxygen species (ROS). The activity of antioxidant enzymes including catalase (CAT) and superoxide dismutase (SOD) was significantly lower in cisplatin-treated LL-PK₁ cells, and 23-HTA or NIF₁ treatment notably increased the these enzyme activity and protein and mRNA levels of CAT and manganese SOD (MnSOD). Moreover, cisplatin caused a significant decrease in nuclear levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and pretreatment with 23-HTA or NIF₁ significantly suppressed the cisplatin-induced translocation of Nrf2 in LLC-PK₁ cells. Taken together, these results suggest that 23-HTA ameliorates cisplatin-induced toxicity via modulation of antioxidant enzymes through activation of Nrf2 in LLC-PK₁ cells.

Light chain-mediated tubulopathies.

Immunoglobulin light chains are low molecular weight proteins that are filtered through the glomerulus and reabsorbed into the proximal tubular epithelium by binding initially to a heteromeric receptor complex composed of megalin and cubilin. Saturation of this receptor-mediated endocytotic process results in the presence of free light chains in the distal nephron and urine. In the course of metabolism of monoclonal light chains, nephrotoxicity can occur, resulting in clinical manifestations that can include acute kidney injury and progressive chronic kidney disease. Patterns of tubulopathic renal injury include proximal tubular epithelial cell cytotoxicity, tubulointerstitial nephritis and cast nephropathy (also known as 'myeloma kidney'). Research efforts over the past two decades have refined understanding of the molecular mechanisms involved in light chain-mediated tubular injury and are the subject of this review.