Relationship between oxidative stress and hepatic glutathione levels in ethanol-mediated apoptosis of polarized hepatic cells

Depletion of hepatic glutathione and adenosine by glucocorticoid exposure in Wistar rats is pregnancy-independent

Liver diseases have gained increasing attention due to their substantial impact on health, independently as well as in association with cardio-metabolic disorders. Studies have suggested that glutathione and adenosine assist in providing protection against oxidative stress and inflammation while glucocorticoid (GC) therapy has been associated with chronic inflammatory disorders, even in pregnancy. The implications of Glucocorticoid exposure on maternal health and fetal growth is a concern, however, the possible role of glutathione and adenosine has not been thoroughly investigated. The study therefore hypothesize that exposure to glucocorticoids leads to depletion of hepatic glutathione and adenosine levels, contributing to oxidative stress and tissue injury. Additionally, we aim to investigate whether the effects of glucocorticoids on hepatic health are pregnancy dependent in female rats. Twelve Pregnant and twelve age-matched non-pregnant rats were used for this study; an exogenous administration of glucocorticoid (Dex: 0.2 mg/kg) or vehicle (po) was administered to six pregnant and six non-pregnant rats from gestational day 14 to 19 or for a period of 6 days respectively. Data obtained showed that GC exposure led to a decrease in hepatic glucose-6-phosphate dehydrogenase, glutathione peroxidase, GSH/GSSG ratio and adenosine content in both pregnant and non-pregnant rats. In addition, increased activities of adenosine deaminase and xanthine oxidase, along with increased production of uric acid and increased levels of lactate dehydrogenase, aspartate aminotransferase, alanine transferase, alkaline phosphatase and gamma-glutamyl transferase were observed. In summary, the study indicates that GC-induced liver damage is underlined by depleted hepatic adenosine and glutathione levels as well as elevated markers of tissue inflammation and/or injury. Furthermore, the findings suggest that the effects of GC exposure on hepatic health are pregnancy independent.

NLRP3: a new therapeutic target in alcoholic liver disease

The liver is in charge of a wide range of critical physiological processes and it plays an important role in activating the innate immune system which elicits the inflammatory events. Chronic ethanol exposure disrupts hepatic inflammatory mechanism and leads to the release of proinflammatory mediators such as chemokines, cytokines and activation of inflammasomes. The mechanism of liver fibrosis/cirrhosis involve activation of NLRP3 inflammasome, leading to the destruction of hepatocytes and subsequent metabolic dysregulation in humans. In addition, increasing evidence suggests that alcohol intake significantly modifies liver epigenetics, promoting the development of alcoholic liver disease (ALD). Epigenetic changes including histone modification, microRNA-induced genetic modulation, and DNA methylation are crucial in alcohol-evoked cell signaling that affects gene expression in the hepatic system. Though we are at the beginning stage without having the entire print of epigenetic signature, it is time to focus more on NLRP3 inflammasome and epigenetic modifications. Here we review the novel aspect of ALD pathology linking to inflammation and highlighting the role of epigenetic modification associated with NLRP3 inflammasome and how it could be a therapeutic target in ALD.

Alcohol: basic and translational research; 15th annual Charles Lieber &1st Samuel French satellite symposium

The present review is based on the research presented at the symposium dedicated to the legacy of the two scientists that made important discoveries in the field of alcohol-induced liver damage: Professors C.S. Lieber and S.W. French. The invited speakers described pharmacological, toxicological and patho-physiological effects of alcohol misuse. Moreover, genetic biomarkers determining adverse drug reactions due to interactions between therapeutics used for chronic or infectious diseases and alcohol exposure were discussed. The researchers presented their work in areas of alcohol-induced impairment in lipid protein trafficking and endocytosis, as well as the role of lipids in the development of fatty liver. The researchers showed that alcohol leads to covalent modifications that promote hepatic dysfunction and injury. We concluded that using new advanced techniques and research ideas leads to important discoveries in science.

Triptolide regulates oxidative stress and inflammation leading to hepatotoxicity via inducing CYP2E1

Triptolide (TP), the main active compound extracted from medicine-tripterygium wilfordii Hook f. (TWHF). It has anti-tumor and immunomodulatory properties. Our study aimed to investigate the mechanisms of hepatotoxicity treated with TP in vivo and in vitro, as well as their relationship with the NF-κB (p65) signal pathway; and to assess TP-induced hepatotoxicity after CYP2E1 modulation by the known inhibitor, clomethiazole, and the known inducer, pyrazole. Mice were given TP to cause liver injury and IHHA-1 cells were given TP to cause hepatocyte injury. The enzyme activity and hepatotoxicity changed dramatically when the CYP2E1 inhibitor and inducer were added. In comparison to the control group, the enzyme inducer increased the activity of CYP2E1, whereas the enzyme inhibitor had the opposite effect. Our findings suggest that TP is an inducer of CYP2E1 via a time-dependent activation mechanism. In addition, TP can promote oxidative stress, inflammatory and involving the NF-κB (p65) signal pathway. Therefore, we used triptolide to stimulate C57 mice and IHHA-1 cells to determine whether TP can promote oxidative stress and inflammation by activating CYP2E1 in response to exacerbated liver damage and participate in NF-κB (p65) signaling pathway.

Alcoholic-Hepatitis, Links to Brain and Microbiome: Mechanisms, Clinical and Experimental Research

The following review article presents clinical and experimental features of alcohol-induced liver disease (ALD). Basic aspects of alcohol metabolism leading to the development of liver hepatotoxicity are discussed. ALD includes fatty liver, acute alcoholic hepatitis with or without liver failure, alcoholic steatohepatitis (ASH) leading to fibrosis and cirrhosis, and hepatocellular cancer (HCC). ALD is fully attributable to alcohol consumption. However, only 10-20% of heavy drinkers (persons consuming more than 40 g of ethanol/day) develop clinical ALD. Moreover, there is a link between behaviour and environmental factors that determine the amount of alcohol misuse and their liver disease. The range of clinical presentation varies from reversible alcoholic hepatic steatosis to cirrhosis, hepatic failure, and hepatocellular carcinoma. We aimed to (1) describe the clinico-pathology of ALD, (2) examine the role of immune responses in the development of alcoholic hepatitis (ASH), (3) propose diagnostic markers of ASH, (4) analyze the experimental models of ALD, (5) study the role of alcohol in changing the microbiota, and (6) articulate how findings in the liver and/or intestine influence the brain (and/or vice versa) on ASH; (7) identify pathways in alcohol-induced organ damage and (8) to target new innovative experimental concepts modeling the experimental approaches. The present review includes evidence recognizing the key toxic role of alcohol in ALD severity. Cytochrome p450 CYP2E1 activation may change the severity of ASH. The microbiota is a key element in immune responses, being an inducer of proinflammatory T helper 17 cells and regulatory T cells in the intestine. Alcohol consumption changes the intestinal microbiota and influences liver steatosis and liver inflammation. Knowing how to exploit the microbiome to modulate the immune system might lead to a new form of personalized medicine in ALF and ASH.

Alcohol-induced microtubule acetylation leads to the accumulation of large, immobile lipid droplets

Although steatosis (fatty liver) is a clinically well-described early stage of alcoholic liver disease, surprisingly little is known about how it promotes hepatotoxicity. We have shown that ethanol consumption leads to microtubule hyperacetylation that can explain ethanol-induced defects in protein trafficking. Because almost all steps of the lipid droplet life cycle are microtubule dependent and because microtubule acetylation promotes adipogenesis, we examined droplet dynamics in ethanol-treated cells. In WIF-B cells treated with ethanol and/or oleic acid (a fatty acid associated with the "Western" diet), we found that ethanol dramatically increased lipid droplet numbers and led to the formation of large, peripherally located droplets. Enhanced droplet formation required alcohol dehydrogenase-mediated ethanol metabolism, and peripheral droplet distributions required intact microtubules. We also determined that ethanol-induced microtubule acetylation led to impaired droplet degradation. Live-cell imaging revealed that droplet motility was microtubule dependent and that droplets were virtually stationary in ethanol-treated cells. To determine more directly whether microtubule hyperacetylation could explain impaired droplet motility, we overexpressed the tubulin-specific acetyltransferase αTAT1 to promote microtubule acetylation in the absence of alcohol. Droplet motility was impaired in αTAT1-expressing cells but to a lesser extent than in ethanol-treated cells. However, in both cases, the large immotile droplets (but not small motile ones) colocalized with dynein and dynactin (but not kinesin), implying that altered droplet-motor microtubule interactions may explain altered dynamics. These studies further suggest that modulating cellular acetylation is a potential strategy for treating alcoholic liver disease.NEW & NOTEWORTHY Chronic alcohol consumption with the "Western diet" enhances the development of fatty liver and leads to impaired droplet motility, which may have serious deletrious effects on hepatocyte function.

Rab17 regulates apical delivery of hepatic transcytotic vesicles

A major focus for our laboratory is identifying the molecules and mechanisms that regulate basolateral-to-apical transcytosis in polarized hepatocytes. Our most recent studies have focused on characterizing the biochemical and functional properties of the small rab17 GTPase. We determined that rab17 is a monosumoylated protein and that this modification likely mediates selective interactions with the apically located syntaxin 2. Using polarized hepatic WIF-B cells exogenously expressing wild-type, dominant active/guanosine triphosphate (GTP)-bound, dominant negative/guanosine diphosphate (GDP)-bound, or sumoylation-deficient/K68R rab17 proteins, we confirmed that rab17 regulates basolateral-to-apical transcytotic vesicle docking and fusion with the apical surface. We further confirmed that transcytosis is impaired from the subapical compartment to the apical surface and that GTP-bound and sumoylated rab17 are likely required for apical vesicle docking. Because expression of the GTP-bound rab17 led to impaired transcytosis, whereas wild type had no effect, we further propose that rab17 GTP hydrolysis is required for vesicle delivery. We also determined that transcytosis of three classes of newly synthesized apical residents showed similar responses to rab17 mutant expression, indicating that rab17 is a general component of the transcytotic machinery required for apically destined vesicle docking and fusion.

A Serine/Threonine Kinase 16-Based Phospho-Proteomics Screen Identifies WD Repeat Protein-1 As A Regulator Of Constitutive Secretion

The plasma membrane of polarized hepatocytes is functionally divided into two domains: the apical and basolateral. Our focus is to define the molecular basis of polarized protein sorting of newly-synthesized membrane and secretory proteins in WIF-B cells, an excellent model system for polarized hepatocytes. We determined that MAL2 (myelin and lymphocyte protein 2) and its binding partner, serine/threonine kinase 16 (STK16) regulate basolateral constitutive secretion. Because STK16 is a constitutively active kinase, we reasoned that constitutively phosphorylated substrates must participate in constitutive secretion. To identify either STK16 substrates or other proteins that regulate constitutive secretion, we took a proteomics approach. Post-nuclear supernatants from cells expressing wild type or a kinase-dead (E202A) STK16 were separated on 2D gels and immunoblotted with antibodies against phospho-serine/threonine residues. Sixteen spots were identified from E202A-expressing cells that reproducibly displayed decreased immunoreactivity. From these spots, 28 proteins were identified as possible STK16 substrates. Out of these 28 possible substrates, 25% of them encode predicted STK16 phosphorylation consensus sites, with WD repeat containing protein-1 (WDR1) encoding two such sites. Based on this finding and on the finding that actin remodeling is required for hepatic secretion, we further confirmed that WDR1 is a phosphoprotein that regulates secretion.

Ethanol metabolism by alcohol dehydrogenase or cytochrome P450 2E1 differentially impairs hepatic protein trafficking and growth hormone signaling

The liver metabolizes alcohol using alcohol dehydrogenase (ADH) and cytochrome P₄₅₀ 2E1 (CYP2E1). Both enzymes metabolize ethanol into acetaldehyde, but CYP2E1 activity also results in the production of reactive oxygen species (ROS) that promote oxidative stress. We have previously shown that microtubules are hyperacetylated in ethanol-treated polarized, hepatic WIF-B cells and livers from ethanol-fed rats. We have also shown that enhanced protein acetylation correlates with impaired clathrin-mediated endocytosis, constitutive secretion, and nuclear translocation and that the defects are likely mediated by acetaldehyde. However, the roles of CYP2E1-generated metabolites and ROS in microtubule acetylation and these alcohol-induced impairments have not been examined. To determine if CYP2E1-mediated alcohol metabolism is required for enhanced acetylation and the trafficking defects, we coincubated cells with ethanol and diallyl sulfide (DAS; a CYP2E1 inhibitor) or N-acetyl cysteine (NAC; an antioxidant). Both agents failed to prevent microtubule hyperacetylation in ethanol-treated cells and also failed to prevent impaired secretion or clathrin-mediated endocytosis. Somewhat surprisingly, both DAS and NAC prevented impaired STAT5B nuclear translocation. Further examination of microtubule-independent steps of the pathway revealed that Jak2/STAT5B activation by growth hormone was prevented by DAS and NAC. These results were confirmed in ethanol-exposed HepG2 cells expressing only ADH or CYP2E1. Using quantitative RT-PCR, we further determined that ethanol exposure led to blunted growth hormone-mediated gene expression. In conclusion, we determined that alcohol-induced microtubule acetylation and associated defects in microtubule-dependent trafficking are mediated by ADH metabolism whereas impaired microtubule-independent Jak2/STAT5B activation is mediated by CYP2E1 activity.NEW & NOTEWORTHY Impaired growth hormone-mediated signaling is observed in ethanol-exposed hepatocytes and is explained by differential effects of alcohol dehydrogenase (ADH)- and cytochrome P₄₅₀ 2E1 (CYP2E1)-mediated ethanol metabolism on the Jak2/STAT5B pathway.

Ethanol-dependent expression of the NKG2D ligands MICA/B in human cell lines and leukocytes

Alcohol consumption affects the human immune system, causing a variety of disorders. However, the mechanisms of development of these changes are not fully understood. We hypothesized that ethanol may influence the expression of MICA and MICB, stress-induced molecules capable of regulating the activity of cytotoxic lymphocytes through the interaction with receptor NKG2D, which substantially affects the functionality of cellular immunity. We analyzed the effects of ethanol on MICA/B expression in tumor cell lines and human leukocytes. In the cell line models, ethanol caused different changes in the surface expression of MICA/B; in particular, it induced the translocation of intracellular proteins MICA/B to the cell surface and shedding of MICA (in soluble and microparticle-associated forms) from the plasma membrane. The observed results are not linked with cell death in cultures, taking place only under higher doses of ethanol. Ethanol at physiologically relevant concentrations (and higher) stimulated expression of MICA/B genes in different cell types. The effect of ethanol was more pronounced in hepatocyte line HepG2 compared with hematopoietic cell lines K562, Jurkat, and THP-1. Among the tested leukocytes, the most sensitive to ethanol action were T cells activated ex vivo with IL-2, in which the increase of MICA/B mRNA expression was registered with the smallest dose of ethanol (0.125%). In human monocytes, ethanol may lead to elevations in surface MICA/B levels. Presumably, changes in MICA/B expression caused by ethanol can affect the functions of NKG2D-positive cytotoxic lymphocytes, modulating immune reactions at excessive alcohol consumption.

High Intrinsic Aerobic Capacity Protects against Ethanol-Induced Hepatic Injury and Metabolic Dysfunction: Study Using High Capacity Runner Rat Model

Rats artificially selected over several generations for high intrinsic endurance/aerobic capacity resulting in high capacity runners (HCR) has been developed to study the links between high aerobic fitness and protection from metabolic diseases (Wisloff et al., Science, 2005). We have previously shown that the HCR strain have elevated hepatic mitochondrial content and oxidative capacity. In this study, we tested if the elevated hepatic mitochondrial content in the HCR rat would provide "metabolic protection" from chronic ethanol-induced hepatic steatosis and injury. The Leiber-Decarli liquid diet with ethanol (7% v/v; HCR-E) and without (HCR-C) was given to HCR rats (n = 8 per group) from 14 to 20 weeks of age that were weight matched and pair-fed to assure isocaloric intake. Hepatic triglyceride (TG) content and macro- and microvesicular steatosis were significantly greater in HCR-E compared with HCR-C (p < 0.05). In addition, hepatic superoxide dismutase activity and glutathione levels were significantly (p < 0.05) reduced in the HCR-E rats. This hepatic phenotype also was associated with reduced total hepatic fatty acid oxidation (p = 0.03) and β-hydroxyacyl-CoA dehydrogenase activity (p = 0.01), and reductions in microsomal triglyceride transfer protein and apoB-100 protein content (p = 0.01) in HCR-E animals. However, despite these documented hepatic alterations, ethanol ingestion failed to induce significant hepatic liver injury, including no changes in hepatic inflammation, or serum alanine amino transferase (ALTs), free fatty acids (FFAs), triglycerides (TGs), insulin, or glucose. High intrinsic aerobic fitness did not reduce ethanol-induced hepatic steatosis, but protected against ethanol-induced hepatic injury and systemic metabolic dysfunction in a high aerobic capacity rat model.

Alcohol-induced defects in hepatic transcytosis may be explained by impaired dynein function

Alcoholic liver disease has been clinically well described, but the molecular mechanisms leading to hepatotoxicity have not been fully elucidated. Previously, we determined that microtubules are hyperacetylated and more stable in ethanol-treated WIF-B cells, VL-17A cells, liver slices, and in livers from ethanol-fed rats. From our recent studies, we believe that these modifications can explain alcohol-induced defects in microtubule motor-dependent protein trafficking including nuclear translocation of a subset of transcription factors. Since cytoplasmic dynein/dynactin is known to mediate both microtubule-dependent translocation and basolateral to apical/canalicular transcytosis, we predicted that transcytosis is impaired in ethanol-treated hepatic cells. We monitored transcytosis of three classes of newly synthesized canalicular proteins in polarized, hepatic WIF-B cells, an emerging model system for the study of liver disease. As predicted, canalicular delivery of all proteins tested was impaired in ethanol-treated cells. Unlike in control cells, transcytosing proteins were observed in discrete sub-canalicular puncta en route to the canalicular surface that aligned along acetylated microtubules. We further determined that the stalled transcytosing proteins colocalized with dynein/dynactin in treated cells. No changes in vesicle association were observed for either dynein or dynactin in ethanol-treated cells, but significantly enhanced dynein binding to microtubules was observed. From these results, we propose that enhanced dynein binding to microtubules in ethanol-treated cells leads to decreased motor processivity resulting in vesicle stalling and in impaired canalicular delivery. Our studies also importantly indicate that modulating cellular acetylation levels with clinically tolerated deacetylase agonists may be a novel therapeutic strategy for treating alcoholic liver disease.

Chronic liver inflammation: Clinical implications beyond alcoholic liver disease

Chronic alcohol exposure can lead to alcoholic liver disease, including hepatitis, cirrhosis and hepatocellular carcinoma, and chronic inflammation can simultaneously cause systemic medical illness. Recent evidence suggests that alcoholic liver disease is a predictor for liver-related diseases, cardiovascular disease, immunologic disease, and bone disease. Chronic inflammation in alcoholic liver disease is mediated by a direct inflammatory cascade from the alcohol detoxification process and an indirect inflammatory cascade in response to gut microflora-derived lipopolysaccharides (LPS). The pathophysiology of alcoholic liver disease and its related systemic illness is characterized by oxidative stress, activation of the immune cascade, and gut-liver interactions. Integrative therapeutic strategies for alcoholic liver disease include abstaining from alcohol consumption; general anti-inflammatories such as glucocorticoid, pentoxifylline, and tumour necrosis factor-α antagonist; antioxidants such as N- acetylcysteine; gut microflora and LPS modulators such as rifaximin and/or probiotics. This review focuses on the impact of chronic liver inflammation on systemic health problems and several potential therapeutic targets.

Inhibition of CYP2E1 leads to decreased malondialdehyde-acetaldehyde adduct formation in VL-17A cells under chronic alcohol exposure

AIM

Ethanol metabolism leads to the formation of acetaldehyde and malondialdehyde. Acetaldehyde and malondialdehyde can together form malondialdehyde-acetaldehyde (MAA) adducts. The role of alcohol dehydrogenase (ADH) and cytochrome P4502E1 (CYP2E1) in the formation of MAA-adducts in liver cells has been investigated.

MAIN METHODS

Chronic ethanol treated VL-17A cells over-expressing ADH and CYP2E1 were pretreated with the specific CYP2E1 inhibitor - diallyl sulfide or ADH inhibitor - pyrazole or ADH and CYP2E1 inhibitor - 4-methyl pyrazole. Malondialdehyde, acetaldehyde or MAA-adduct formation was measured along with assays for viability, oxidative stress and apoptosis.

KEY FINDINGS

Inhibition of CYP2E1 with 10 μM diallyl sulfide or ADH with 2mM pyrazole or ADH and CYP2E1 with 5mM 4-methyl pyrazole led to decreased oxidative stress and toxicity in chronic ethanol (100 mM) treated VL-17A cells. In vitro incubation of VL-17A cell lysates with acetaldehyde and malondialdehyde generated through ethanol led to increased acetaldehyde (AA)-, malondialdehyde (MDA)-, and MAA-adduct formation. Specific inhibition of CYP2E1 or ADH and the combined inhibition of ADH and CYP2E1 greatly decreased the formation of the protein aldehyde adducts. Specific inhibition of CYP2E1 led to the greatest decrease in oxidative stress, toxicity and protein aldehyde adduct formation, implicating that CYP2E1 accelerates the formation of protein aldehyde adducts which can be an important mechanism for alcohol mediated liver injury.

SIGNIFICANCE

CYP2E1-mediated metabolism of ethanol leads to increased AA-, MDA-, and MAA-adduct formation in liver cells which may aggravate liver injury.

Ethanol promotes cytotoxic effects of tumor necrosis factor-related apoptosis-inducing ligand through induction of reactive oxygen species in prostate cancer cells

BACKGROUND

Effective treatment of prostate cancer (PCa) remains a major challenge due to chemoresistance to drugs including tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Ethanol and ethanol extracts are known apoptosis inducers. However, cytotoxic effects of ethanol on PCa cells are unclear.

METHODS

In this study we utilized PC3 and LNCaP cell culture models. We used immunohistochemical analysis, western blot analysis, reactive oxygen species (ROS) measurement, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) Cell Proliferation Assay, Annexin-V staining and flow cytometry for quantification of apoptosis. In vitro soft agar colony formation and Boyden chamber invasion assays were used. Tumorigenicity was measured in a xenotransplantation mouse model.

RESULTS

Here, we demonstrate that ethanol enhances the apoptosis-inducing potential of TRAIL in androgen-resistant PC3 cells and sensitizes TRAIL-resistant, androgen sensitive LNCaP cells to apoptosis through caspase activation, and a complete cleavage of poly (ADP)-ribose polymerase, which was in association with increased production of ROS. The cytotoxicity of ethanol was suppressed by an antioxidant N-acetyl cystein pretreatment. Furthermore, ethanol in combination with TRAIL increased the expression of cyclin-dependent kinase inhibitor p21 and decreased the levels of Bcl-2 and phosphorylated-AKT. These molecular changes were accompanied by decreased proliferation, anchorage-independent growth and invasive potential of PC3 and LNCaP cells. In vivo studies using a xenotransplantation mouse model with PC3 cells demonstrated significantly increased apoptosis in tumors treated with ethanol and TRAIL in combination.

CONCLUSIONS

Taken together, use of ethanol in combination with TRAIL may be an effective strategy to augment sensitivity to TRAIL-induced apoptosis in PCa cells.

Inflammation in alcoholic liver disease

Frank Burr Mallory's landmark observation in 1911 on the histopathology of alcoholic liver disease (ALD) was the first identification of a link between inflammation and ALD. In this review, we summarize recent advances regarding the origins and roles of various inflammatory components in ALD. Metabolism of ethanol generates a number of metabolites, including acetate, reactive oxygen species, acetaldehyde, and epigenetic changes, that can induce inflammatory responses. Alcohol and its metabolites can also initiate and aggravate inflammatory conditions by promoting gut leakiness of microbial products, by sensitizing immune cells to stimulation, and by activating innate immune pathways, such as complement. Chronic alcohol consumption also sensitizes nonimmune cells, e.g., hepatocytes, to inflammatory signals and impairs their ability to respond to protective signals. Based on these advances, a number of inflammatory targets have been identified with potential for therapeutic intervention in ALD, presenting new opportunities and challenges for translational research.

Ameliorative effects of dimetylthiourea and N-acetylcysteine on nanoparticles induced cyto-genotoxicity in human lung cancer cells-A549

We study the ameliorative potential of dimetylthiourea (DMTU), an OH^• radical trapper and N-acetylcysteine (NAC), a glutathione precursor/H₂O₂ scavenger against titanium dioxide nanoparticles (TiO₂-NPs) and multi-walled carbon nanotubes (MWCNTs) induced cyto-genotoxicity in cultured human lung cancer cells-A549. Cytogenotoxicity was induced by exposing the cells to selected concentrations (10 and 50 µg/ml) of either of TiO₂-NPs or MWCNTs for 24 h. Anti-cytogenotoxicity effects of DMTU and NAC were studied in two groups, i.e., treatment of 30 minutes prior to toxic insult (short term exposure), while the other group received DMTU and NAC treatment during nanoparticles exposure, i.e., 24 h (long term exposure). Investigations were carried out for cell viability, generation of reactive oxygen species (ROS), micronuclei (MN), and expression of markers of oxidative stress (HSP27, CYP2E1), genotoxicity (P⁵³) and CYP2E1 dependent n- nitrosodimethylamine-demethylase (NDMA-d) activity. In general, the treatment of both DMTU and NAC was found to be effective significantly against TiO₂-NPs and MWCNTs induced cytogenotoxicity in A549 cells. Long-term treatment of DMTU and NAC during toxic insults has shown better prevention than short-term pretreatment. Although, cells responded significantly to both DMTU and NAC, but responses were chemical specific. In part, TiO_2-NPs induced toxic responses were mediated through OH^• radicals generation and reduction in the antioxidant defense system. While in the case of MWCNTs, adverse effects were primarily due to altering/hampering the enzymatic antioxidant system. Data indicate the applicability of human lung cancer cells-A549 as a pre-screening tool to identify the target specific prophylactic and therapeutic potential of drugs candidate molecules against nanoparticles induced cellular damages.

Hepatoprotective role of vitamin B(12) and folic acid in arsenic intoxicated rats

The present study elucidated the protective role of vitamin B(12) with folic acid against arsenic-induced hepatotoxicity in female rats. Ingestion of sodium-arsenite- contaminated water [0.4 ppm/100 g body weight (b.w.)/day] in combination with vitamin B(12) plus folic acid (0.07 and 4.0 μg, respectively/100 g b.w./day) for 24 days to Wistar rats offered a significant protection against alone arsenic-induced distorted liver function, damaged histoarchitecture, elevated oxidative stress, and DNA fragmentation of hepatic tissues. Arsenic only exposure decreased hepatic superoxide dismutase (SOD), catalase activities, and the level of nonprotein-soluble thiol (NPSH), with a concomitant increase in thiobarbituric acid reactive substances (TBARS) and conjugated dienes (CDs) in the liver. Vitamin supplementation restrained the increase of TBARS and CDs by restoring catalase, SOD, and NPSH levels. Restricted generation of free radicals may be correlated to the protection of DNA stability and hepatic morphology. This study explains the decisive role of vitamin B(12) with folic acid to ameliorate arsenic-mediated liver injuries.

Protective role of Moringa oleifera (Sajina) seed on arsenic-induced hepatocellular degeneration in female albino rats

In an attempt to develop new herbal therapy, an aqueous extract of the seed of Moringa oleifera was used to screen the effect on arsenic-induced hepatic toxicity in female rat of Wistar strain. Subchronic exposure to sodium arsenite (0.4 ppm/100 g body weight/day via drinking water for a period of 24 days) significantly increased activities of hepatic and lipid function markers such as alanine transaminase, aspartate transaminase, cholesterol, triglycerides, LDL along with a decrease in total protein and HDL. A notable distortion of hepatocellular histoarchitecture was prominent with a concomitant increase in DNA fragmentation following arsenic exposure. A marked elevation of lipid peroxidation in hepatic tissue was also evident from the hepatic accumulation of malondialdehyde and conjugated dienes along with suppressed activities in the antioxidant enzymes such as superoxide dismutase and catalase. However, co-administration of aqueous seed extract of M. oleifera (500 mg/100 g body weight/day for a period of 24 days) was found to significantly prevent the arsenic-induced alteration of hepatic function markers and lipid profile. Moreover, the degeneration of histoarchitecture of liver found in arsenic-treated rats was protected along with partial but definite prevention against DNA fragmentation induction. Similarly, generation of reactive oxygen species and free radicals were found to be significantly less along with restored activities of antioxidant enzymes in M. oleifera co-administered group with comparison to arsenic alone treatment group. The present investigation offers strong evidence for the hepato-protective and antioxidative efficiencies of M. oleifera seed extract against oxidative stress induced by arsenic.

Ethanol enhances susceptibility to apoptotic cell death via down-regulation of autophagy-related proteins

BACKGROUND

Alcohol induces cellular stress and promotes cell death in immune cells. Molecular mechanisms by which ethanol impairs the function of immune cells are largely unknown. Autophagy is a degradation pathway, acting either as a pro-survival or pro-death mechanism activated during stress conditions. We examined whether ethanol influences autophagy in monocytic human U937, CD4 Jurkat, and MCF-7 cells.

METHODS

Effects of ethanol during starvation-induced autophagy were investigated, treating cells with ethanol alone and in combination with activation of autophagy by rapamycin or inhibition by wortmannin. Apoptotic and necrotic cell death features such as the breakdown of the mitochondrial membrane potential, DNA fragmentation, and cell permeability were assessed using FACS analyses. Expression level of Beclin-1, LC3-II, Bcl-2, and the activation of caspase-3, and PARP-1 were determined using Western blot analyses. Influence of ethanol on formation of LC3-II complexes was assessed using fluorescence microscopy in MCF-7 cells stable transfected with a GFP-LC3-II-expression vector.

RESULTS

Ethanol down regulated autophagy proteins such as Beclin-1 and LC3-II. Apoptosis was enhanced as shown by breakdown of mitochondrial potential, up-regulation of cleaved caspase-3 and PARP-1 and down-regulation of anti-apoptotic protein Bcl-2. Formation of LC3-II complexes was inhibited by ethanol in caspase-3 deficient MCF-7 cells. Stimulation of autophagy by rapamycin prevented ethanol-induced apoptotic cell death. Inhibition of autophagy by wortmannin aggravated ethanol-mediated necrotic cell death.

CONCLUSION

Inhibition of autophagy via ethanol enhances susceptibility to cell death.

Evidence for the role of oxidative stress in the acetylation of histone H3 by ethanol in rat hepatocytes

The relationship between ethanol-induced oxidative stress and acetylation of histone H3 at lysine 9 (H3AcK9) remains unknown and was therefore investigated in primary cultures of rat hepatocytes. Cells were treated with ethanol, and a select group of pharmacological agents and the status of H3AcK9 and reactive oxygen species (ROS) were monitored. Pretreatment of hepatocytes with N-acetyl cystein (ROS reducer), or dietary antioxidants (quercetin, reserveratrol), or NADPH (reduced nicotinamide adenine dinucleotide phosphate) oxidase inhibitor apocynin, significantly reduced ethanol (50 mM, 24 h) induced increases in ROS and H3AcK9. In contrast, l-buthionine sulfoximine (ROS inducer) and inhibitor of mitochondrial complexes I (rotenone) and III (antimycin) increased ethanol-induced H3AcK9 (P<.01). Oxidative stress also affected ethanol-induced alcohol dehydrogenase 1 mRNA expression. These results demonstrate for the first time that oxidative stress is involved in the ethanol-induced histone H3 acetylation in hepatocytes.

Transcriptome sequencing, microarray, and proteomic analyses reveal cellular and metabolic impact of hepatitis C virus infection in vitro

Hepatitis C virus (HCV) is a major cause of liver disease but the full impact of HCV infection on the hepatocyte is poorly understood. RNA sequencing (RNA-Seq) is a novel method to analyze the full transcriptional activity of a cell or tissue, thus allowing new insight into the impact of HCV infection. We conducted the first full-genome RNA-Seq analysis in a host cell to analyze infected and noninfected cells, and compared this to microarray and proteomic analyses. The combined power of the triple approach revealed that HCV infection affects a number of previously unreported canonical pathways and biological functions, including pregnane X receptor/retinoic acid receptor activation as a potential host antiviral response, and integrin-linked kinase signaling as an entry factor. This approach also identified several mechanisms implicated in HCV pathogenesis, including an increase in reactive oxygen species. HCV infection had a broad effect on cellular metabolism, leading to increases in cellular cholesterol and free fatty acid levels, associated with a profound and specific decrease in cellular glucose levels.

CONCLUSION

RNA-Seq technology, especially when combined with established methods, demonstrated that HCV infection has potentially wide-ranging effects on cellular gene and protein expression. This in vitro study indicates a substantial metabolic impact of HCV infection and highlights new mechanisms of virus-host interaction which may be highly relevant to pathogenesis in vivo.