Oxidative stress induced by intermittent hypoxia exacerbates lipid accumulation and inflammation in a cell model of non-alcoholic steatohepatitis

Oral PresentationBackground/Aims: The prevalence of obstructive sleep apnea (OSA) is high in patients with non-alcoholic fatty liver disease (NAFLD) and NASH is a progressive hallmark of the pathogenesis of NAFLD. Chronic intermittent hypoxia is associated with recurrent episodes of oxygen desaturation and reoxygenation in OSA patients, leading to excessive production of reactive oxygen species (ROS). The causal link between OSA and NAFLD is not known and the mechanistic effect of intermittent hypoxia (IH) on the pathogenesis of NAFLD remains elusive. Here we tested the hypothesis that IH-induced oxidative stress aggravates lipid accumulation and inflammation induced by sodium palmitate in HepG2 cells. Materials and Methods: HepG2 cells were treated with sodium palmitate or vehicle under normoxia (Nx) or IH condition for 72 hours in the present or absence of a ROS scavenger MnTBAP. Cell viability was detected by MTT assay and intracellular lipid deposit was examined by oil red staining. Lipid peroxidation was measured by malondialdehyde (MDA) assay and levels of reactive oxygen species (ROS) were detected by CM-H2DCFDA staining. The expressions of pro-inflammatory cytokines (IL-1β, TNF-α, IL-6), fatty acid uptake-associated genes (caveolin-1 and FATP5), fatty acid synthesis genes (SREBP1 and ACC1) and fatty acid β-oxidation gene ACOX were determined by real-time PCR. Results: Results showed that sodium palmitate increased lipid deposit in the cells and it also decreased cell viability. The effect of sodium palmitate was more prominent in the group co-treated with hypoxia. Levels of MDA and ROS and the expressions of IL-1β, TNF-α, IL-6 and caveolin-1, but not FATP5, were significantly increased in the palmitate- or hypoxia-treated group and were remarkably elevated in the co-treated group. These effects were abolished by MnTBAP treatment. In addition, levels of the expression of ACOX, SREBP1 and ACC1 were significantly lowered in the cells treated with palmitate or hypoxia and the expressions were much less in the cotreated group. Treatment of MnTBAP prevented the decreased expression of ACOX but had no effect on the SREBP1 and ACC1 expression. Conclusion: IH-induced oxidative stress exacerbates lipid accumulation and inflammation induced by sodium palmitate in HepG2 cells, probably mediated by an increase in lipid uptake and a decrease in the fatty acid β-oxidation.published_or_final_versio

Reduction in Hepatic Apoptosis Modulated by Garlic Derived S-Allylmercaptocysteine (SAMC) in Non-Alcoholic Fatty Liver Disease Rat Model Through P53-Dependent Pathways

Poster PresentationPurpose Previous study demonstrated that administration of garlic-derived antioxidant S-allylmercaptocysteine (SAMC) ameliorated hepatic injury in a non-alcoholic fatty liver disease (NAFLD) rat model. In the present study, we investigated the effect and mechanism of SAMC on NAFLD-induced cellular apoptosis in the liver. Methods Adult Sprague-Dawley female rats were fed with a diet comprising of highly unsaturated fat diet (30% fish oil) for 8 weeks to develop NAFLD with or without intraperitoneal injection of 200 mg/kg SAMC three times per week. After chemical euthanasia, liver samples were collected for histological, biochemical and molecular analyses. Results During NAFLD development, increased apoptotic cells were observed in the liver. Hepatic apoptosis was accompanied by activated intrinsic apoptotic pathway as shown by expressional changes of cytochrome c and Bcl-2 family genes. Extrinsic apoptotic pathway was also activated as shown by expressional changes of Fas, TRAIL, FADD and cleaved caspase-8. Increased activity of caspase-3 further confirmed the activation of apoptosis. In addition, reduced activity of LKB1/AMPK and PI3K/Akt pathways could be observed with increased expression of pro-apoptotic regulator p53 in NAFLD rats. Administration of SAMC reduced the number of apoptotic cells through down-regulation of both intrinsic and extrinsic apoptotic mechanisms. Phosphorylation status of LKB1, AMPK, PI3K, and Akt were also restored by SAMC co-treatment, leading to the reduction of p53 expression. Conclusion Administration of SAMC during NAFLD development in rats protects liver from apoptosis through p53-dependent intrinsic and extrinsic apoptotic pathways.published_or_final_versio

Garlic-derived S-allylmercaptocysteine is a hepato-protective agent in non-alcoholic fatty liver disease in vivo animal model

Purpose: To investigate the hepato-protective properties and underlying mechanisms of SAMC in a non-alcoholic fatty liver disease (NAFLD) rat model. Methods: Female rats were fed with a diet comprising highly unsaturated fat diet (30% fish oil) for 8 weeks to develop NAFLD with or without an intraperitoneal injection of 200 mg/kg SAMC three times per week. After euthanasia, blood and liver samples of rats were collected for histological and biochemical analyses. Results: Co-treatment of SAMC attenuated NAFLD-induced liver injury, fat accumulation, collagen formation and free fatty acids (FFAs). At the molecular level, SAMC decreased the lipogenesis marker and restored the lipolysis marker. SAMC also reduced the expression levels of pro-fibrogenic factors and diminished liver oxidative stress partly through the inhibition in the activity of cytochrome P450 2E1-dependent pathway. NAFLD-induced inflammation was also partially mitigated by SAMC treatment via reduction in the pro-inflammatory mediators, chemokines and suppressor of cytokine signaling. The protective effect of SAMC is also shown partly through the restoration of altered phosphorylation status of FFAs-dependent MAP kinase pathways and diminished in the nuclear transcription factors (NF-κB and AP-1) activity during NAFLD development. Conclusions: SAMC is a novel hepato-protective agent against NAFLD caused by abnormal liver functions. Garlic or garlic derivatives could be considered as a potent food supplement in the prevention of fatty liver disease. © 2012 The Author(s).published_or_final_versio

Garlic-derived S-allylmercaptocysteine ameliorates nonalcoholic fatty liver disease in a rat model through inhibition of apoptosis and enhancing autophagy

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The iron-chelating drug M30 down-regulates carbon tetrachloride (CCI4)-induced hepatic oxidative stress, inflammation and apoptosis in vitro

Topic: 2 Acute Liver FailureThis journal suppl. entitled: APASL Liver Week 2013BACKGROUND/AIMS: The novel multifunctional brain permeable ironchelator M30 possesses neuroprotective activities against several insults applicable to various neurodegenerative diseases. However, the effect of M30 on CCl4 induced acute liver damage is still unknown. The aim of this study is to investigate whether the multifunctional drug M30 could ameliorate CCl4 induced hepatic injury in human HepG2 cell line. METHODS: HepG2 cells were grown in DMEM supplemented with ...postprin

Zeaxanthin Dipalmitate Therapeutically Improves Hepatic Functions in an Alcoholic Fatty Liver Disease Model through Modulating MAPK Pathway

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Intermittent hypoxia aggravates early pathogenesis of non-alcoholic fatty liver disease in rats

BACKGROUND/AIMS: Chronic intermittent hypoxia (CIH) is associated with recurrent episodes of oxygen desaturation and reoxygenation in obstructive sleep apnea (OSA) patients. The prevalence of OSA is high in patients with non-alcoholic fatty liver disease (NAFLD). The mechanistic effect of CIH on the early pathogenesis of NAFLD remains elusive. Here we tested the hypothesis that IH aggravates oxidative stress and inflammation induced by high fat diet at an initial stage of pathogenesis ...postprin

Adult heart transplantation under tacrolimus (FK506) immunosuppression: Histopathologic observations and comparison to a cyclosporine-based regimen with lympholytic (ATG) induction

Background: Tacrolimus (FK506) is an effective immunosuppressant for human heart transplantation, but information about its effects on cardiac allograft and nonallograft kidney and liver histopathologic study is limited. Methods: We therefore reviewed 1145 endomyocardial biopsy specimens and eight autopsy results from 80 heart transplant recipients who received tacrolimus as baseline immunosuppression. These were compared with 619 endomyocardial biopsy specimens and four autopsy results from 51 patients treated with cyclosporine-based immunosuppression with lympholytic induction (CLI) by use of rabbit anti-thymocyte globulin. Twenty-one histologic features including the International Society for Heart and Lung Transplantation histopathologic grade were retrospectively assessed without knowledge of the treatment regimen. The lymphocyte growth index on biopsy specimens obtained from these patients was also compared. Results: In general, there were no qualitative differences in the histopathologic appearance of various allograft syndromes between tacrolimus- and CLI-treated patients. Thus histopathologic criteria used to diagnose various graft syndromes are applicable under tacrolimus immunosuppression. However, early (between 10 and 30 days) after transplantation, biopsy specimens from patients treated with tacrolimus showed a significantly higher percentage of inflamed fragments (p = 0.02), the inflammation tended to be more severe (p = 0.09), and the rejection grade tended to be slightly higher (p = 0.08). In contrast, during the late transplantation period (275 to 548 days), biopsy specimens from patients treated with CLI showed a significantly higher percentage of inflamed fragments (p = 0.03), more severe inflammation (p = 0.03), higher rejection grades (p = 0.01), and a higher frequency of Quilty lesions (p = 0.05). Although overall freedom from any grade 3A or higher rejection was greater in the CLI-treated arm, tacrolimus was successfully used to treat refractory rejection in three patients from the CLI-treated arm. Concern has been raised in the literature about the possibility of tacrolimus being a direct hepatotoxin and an accelerant of allograft obliterative arteriopathy. However, no evidence to support either of these contentions was detected in this patient population. In contrast, tacrolimus is clearly nephrotoxic, although similar to cyclosporine in this regard. Conclusions: Tacrolimus is an effective immunosuppressive drug for heart transplantation. The cardiac allograft histopathologic study of patients treated with tacrolimus immunosuppression does not significantly differ from those given conventional, cyclosporine-based triple therapy with lympholytic induction

Polysaccharides from Lycium barbarum attenuates hepatic steatosis, fibrosis and inflammation in a non-alcoholic fatty liver diseases (NAFLD) rat model

Topic: 4.a Basic ScienceThis journal suppl. entitled: APASL Liver Week 2013BACKGROUND/AIMS: Lycium barbarum polysaccharides (LBP) are derivative from Wolfberry with antioxidant and neuroprotective properties. Although it shows beneficial effects against aging and oxidative stress in neuron, but whether LBP possesses protective effects in chronic liver injury, such as in non-alcoholic fatty liver disease, (NAFLD), is still unknown. We aimed to investigate the protective effects of ...postprin