Keqin Xie

Diallyl trisulfide (DATS) effectively attenuated oxidative stress-mediated liver injury and hepatic mitochondrial dysfunction in acute ethanol-exposed mice

The protective effects of diallyl trisulfide (DATS) on acute ethanol-induced liver injury were investigated. Mice were pretreated with DATS (30mg/kgbw) for 7d before being exposed to ethanol (4.8g/kgbw). The biochemical indices (aspartate amino transferase, AST; alanine amino transferase, ALT; triglyceride, TG) were examined to evaluate the protective effects. Mitochondria were isolated for the mitochondrial permeability transition (MPT), membrane potential (DeltaPsi(m)) and adenosine nucleotide pool assay. The lipid peroxidation (malondialdehyde, MDA), non-enzymatic antioxidant (glutathione, GSH) and enzymatic antioxidants (superoxide dismutase, SOD; catalase, CAT; glutathione reductase, GR; glutathione peroxidase, GSH-Px) were measured both in the liver homogenate and isolated mitochondria. Acute ethanol exposure resulted in the significant increase of the ALT, AST and TG levels and hepatic mitochondria dysfunction shown as MPT, and the decreases of DeltaPsi(m), ATP and energy charge (EC). However, DATS pretreatment dramatically attenuated these adverse effects. Beside this, DATS was found to significantly inhibit the increase of the hepatic and mitochondrial MDA levels, which were decreased by 33.3% (P<0.01) and 39.0% (P<0.01), respectively. In addition, DATS pretreatment markedly suppressed the ethanol-induced decrease of the hepatic GSH level and increased the mitochondrial GSH level. Moreover, the activities of the hepatic antioxidant enzymes (SOD, CAT, and GR) and the mitochondrial antioxidant enzymes (SOD, GR, and GSH-Px) were significantly boosted. Thus, we concluded that DATS dramatically attenuated acute ethanol-induced liver injury and mitochondrial dysfunction. The increase of the hepatic and mitochondrial GSH levels and the elevation of the antioxidant enzymes activities should account for the preventive effects.

The activation of HO-1/Nrf-2 contributes to the protective effects of diallyl disulfide (DADS) against ethanol-induced oxidative stress

BACKGROUND Diallyl disulfide (DADS) is a garlic-derived organosulfur compound. The current study is designed to evaluate the protective effects of DADS against ethanol-induced oxidative stress, and to explore the underlying mechanisms by examining the HO-1/Nrf-2 pathway. METHODS We investigated whether or not DADS could activate the HO-1 in normal human liver cell LO2, and then evaluated the protective effects of DADS against ethanol-induced damage in LO2 cells and in acute ethanol-intoxicated mice. The biochemical parameters were measured using commercial kits. HO-1 mRNA level was determined by RT-PCR. Histopathology and immunofluorescence assay were performed with routine methods. Protein levels were measured by western blot. RESULTS DADS significantly increased the mRNA and protein levels of HO-1, stimulated the nuclear translocation of Nrf-2 and increased the phosphorylation of MAPK in LO2 cells. The nuclear translocation of Nrf-2 was abrogated by MAPK inhibitors. DADS significantly suppressed ethanol-induced elevation of lactate dehydrogenase (LDH) and aspartate transaminase (AST) activities, decrease of glutathione (GSH) level, increase of malondialdehyde (MDA) levels, and apoptosis of LO2 cells, which were all blocked by ZnPPIX. In mice, DADS effectively suppressed acute ethanol-induced elevation of aminotransferase activities, and improved liver histopathological changes, which might be associated with HO-1 activation. CONCLUSION These results demonstrate that DADS could induce the activation of HO-1/Nrf-2 pathway, which may contribute to the protective effects of DADS against ethanol-induced liver injury. GENERAL SIGNIFICANCE DADS may be beneficial for the prevention and treatment of ALD due to significant activation of HO-1/Nrf-2 pathway.

Garlic oil alleviated ethanol-induced fat accumulation via modulation of SREBP-1, PPAR-α, and CYP2E1.

Garlic oil (GO) has been shown to partially attenuate ethanol-induced fatty liver, but the underlying mechanisms remain unclear. The current study was designed to evaluate the protective effects of GO against ethanol-induced steatosis in vitro and in vivo, and to explore potential mechanisms by investigating the sterol regulatory element binding protein-1c (SREBP-1c), peroxisome proliferators-activated receptor-α (PPAR-α), cytochrome P4502E1 (CYP2E1), and etc. In the in vitro study, human normal cell LO2 was exposed to 100 mM ethanol in the presence or absence of GO for 24 h. We found that ethanol increased the protein levels of n-SREBP-1c and CYP2E1, but decreased the protein levels of PPAR-α, which was significantly attenuated by GO co-treatment. In the in vivo study, male Kun-Ming mice were pretreated with single dose of GO (50-200 mg/kg body weight) at 2 h before ethanol (4.8 g/kg body weight) exposure. The changes of n-SREBP-1c, PPAR-α and CYP2E1 were paralleled well to those of in vitro study. Furthermore, GO significantly reduced the protein levels of fatty acid synthase (FAS), and suppressed ethanol-induced hepatic mitochondrial dysfunction. These results suggested that GO had the potential to ameliorate alcoholic steatosis which might be related to its modulation on SREBP-1c, PPAR-α, and CYP2E1.

PI3K/Akt pathway activation was involved in acute ethanol-induced fatty liver in mice.

Accumulating evidences support the important roles of sterol regulatory element-binding protein-1 (SREBP-1) activation in ethanol-induced fatty liver, but the underlying mechanisms for its activation are not fully understood. Recent studies have demonstrated that phosphatidylinositol 3 kinase (PI3K)/Akt pathway activation could enhance SREBP-1 activity. The current study was designed to investigate the potential roles of PI3K/Akt pathway in acute ethanol-induced fatty liver in mice. In the first experiment, mice were treated with ethanol (2.5 or 5 g/kg bw) or isocaloric/isovolumetric maltose-dextrin solution, and sacrificed at several time points after ethanol exposure. As expected, ethanol dose-dependently increased the hepatic triglyceride (TG) levels and the protein levels of the mature form of SREBP-1 (n-SREBP-1). The phosphorylation of Akt and glycogen synthase kinase-3β (GSK-3β) was significantly increased in mice treated with ethanol (5 g/kg bw), while the protein levels of PI3K-p85 were significantly reduced. To confirm the roles of PI3K/Akt pathway, mice were then pretreated with wortmannin (0.7 or 1.4 mg/kg bw), a specific PI3K/Akt pathway inhibitor, before exposure to ethanol. Interestingly, a dual effect of wortmannin was observed. Low dose of wortmannin significantly reduced the hepatic TG levels, while high dose of wortmannin aggravated ethanol-induced fatty liver. The ratio of LC3II/LC3I of wortmannin (1.4 mg/kg bw) group mice was significantly increased, while the p62 protein level was significantly decreased compared to those of ethanol group, which indicated that wortmannin (1.4 mg/kg bw) might suppress the lipid degradation by autophagy. These results supported the hypothesis that PI3K/Akt activation might be involved in acute ethanol-induced fatty liver, and PI3K/Akt inhibitors might have therapeutic potential for the treatment of ethanol-induced fatty liver.

A meta‐analysis of randomized, double‐blind, placebo‐controlled trials for the effects of garlic on serum lipid profiles

BACKGROUND Inconsistent results were obtained for the lipid-regulating effects of garlic in clinical trials. With increasing interest in complementary medicine for hyperlipoidemia, it is important to explore the real effects of garlic. This meta- analysis was performed to investigate the influence of garlic on serum lipid parameters. RESULTS A total of 26 studies were included into meta-analysis. Overall, garlic was superior to placebo in reducing serum total cholesterol (TC) and triglyceride (TG) levels. Compared with the placebo groups, serum TC and TG levels in the garlic group were reduced by 0.28 (95% CI, -0.45, -0.11) mmol L⁻¹ (P = 0.001) and 0.13 (95% CI, -0.20, -0.06) mmol L⁻¹ (P < 0.001), respectively. The effects of garlic were more striking in subjects with long-term intervention and higher baseline TC levels. Garlic powder and aged garlic extract were more effective in reducing serum TC levels, while garlic oil was more effective in lowering serum TG levels. In contrast, garlic did not influence other lipid parameters, including low-density lipoprotein cholesterol, high-density lipoprotein cholesterol (HDL-C), apolipoprotein B, and TC/HDL-C ratio. CONCLUSION Garlic could reduce serum TC and TG levels, and garlic therapy should benefit patients with risk of cardiovascular diseases.

Lipid Peroxidation was Involved in the Memory Impairment of Carbon Monoxide-induced Delayed Neuron Damage

Carbon monoxide (CO)-induced delayed neuron damage is the serious complication, but the underlying mechanisms are poorly understood. This study was designed to investigate the time-dependent changes of the lipid peroxidation (malondialdehyde, MDA) and antioxidative status (glutathione, GSH; glutathione peroxidase, GSH-Px; glutathione reductase, GR; and anti-reactive oxygen species anti-ROS) in nerve tissues for the possible mechanisms exploration. Adult rats were treated with CO by peritoneal injection, and sacrificed after day 0, 1, 3, 7, 14 and 21 of treatment. The results showed that the step-down latency progressively shortened while the numbers of error increased. Comparing with the level of day 0, MDA levels in serum, cerebral cortex and hippocampus significantly increased on day 1, 3 and 7. The level of GSH increased firstly but then decreased. The activities of GR, GSH-Px, and anti-ROS decreased in serum, cerebral cortex and hippocampus of rats after day 1, 3, 7, 14 and 21. Thus, we concluded that CO-mediated delayed neuron damage might be associated with elevation of lipid peroxidation and reduction of antioxidative status. The time-dependent changes of lipid peroxidation and antioxidative status in serum, cerebral cortex and hippocampus, at least in part, are involved in the toxic effects of CO poisoning on neuron.

The Roles of Garlic on the Lipid Parameters: A Systematic Review of the Literature

Garlic has long been the focus of experimental and clinical attentions due to its promising lipid-lowering effects. Numerous animal studies as well as in vitro ones have demonstrated the hypolipidemic effects of garlic, while clinical trials are highly inconsistent. Based on some double-blind, randomized, placebo-controlled clinical trials which denied the hypolipidemic effects of garlic, some meta-analysis concluded that garlic did not possess beneficial effects for hyperlipidemia. However, we should not ignore the abundant supporting data in the literature. It should be noted that the doses of garlic used in clinical trials were usually far lower than those used in animal studies, which might cover its potential effects. The type of the garlic products may be another important factor responsible for the conflicting outcomes, as different garlic products are composed of different organosulfur compounds. In addition, the biological availability of garlic products is of importance, which was omitted in many studies. Moreover, some studies indicated that different people might have a different response to garlic, and thus garlic may be more beneficial for some specific groups. Collectively, it may be inappropriate to draw a conclusion that garlic does not benefit for hyperlipidemia. Future studies with larger samples are needed to further clarify the effects of garlic used at higher but non-toxic doses on specific groups.

Pentoxifylline for the treatment of nonalcoholic fatty liver disease: a meta-analysis of randomized double-blind, placebo-controlled studies.

Aims Pentoxifylline has been used to treat nonalcoholic fatty liver diseases (NAFLDs) due to its anti-tumor necrosis factor-&agr; effects. We conducted a meta-analysis of randomized, double-blinded, placebo-controlled trials to investigate the effect of pentoxifylline on the biochemical and histological parameters of NAFLD patients. Materials and methods A comprehensive literature search was conducted in the database including PubMed, Embase, ISI web of knowledge, the Cochrane Library, and Google Scholar to identify randomized, double-blind, placebo-controlled clinical trials about the effects of pentoxifylline on NAFLD. The pooled weighted mean difference (WMD) with 95% confidence interval (CI) was calculated to compare the effects of pentoxifylline and placebo. Results Five well-designed studies were retrieved. Pooled results showed that pentoxifylline significantly reduced the serum alanine transaminase activity (WMD=−27.97; 95% CI: −42.59, −13.34) and aspartate transaminase activity (WMD=−13.97; 95% CI: −23.31, −4.63) in NAFLD patients compared with placebo. In addition, pentoxifylline significantly improved steatosis (WMD=−0.68; 95% CI: −1.01, −0.34), lobular inflammation (WMD=−0.49; 95% CI: −0.86, −0.12), and fibrosis (WMD=−0.60; 95% CI: −0.99, −0.21). Furthermore, pentoxifylline also led to significant reduction in BMI (WMD=−0.51; 95% CI: −0.96, −0.06) and fasting glucose (WMD=−8.97; 95% CI: −14.52, −3.42), but did not significantly affect the serum tumor necrosis factor &agr; and adiponectin levels when compared with placebo. Conclusion Pentoxifylline could reduce the aminotransferase activities and improve the histological parameters in NAFLD patients. Large well-designed, randomized, placebo-controlled studies are needed to confirm these results.

Garlic oil attenuated nitrosodiethylamine-induced hepatocarcinogenesis by modulating the metabolic activation and detoxification enzymes.

Nitrosodiethylamine (NDEA) is a potent carcinogen widely existing in the environment. Our previous study has demonstrated that garlic oil (GO) could prevent NDEA-induced hepatocarcinogenesis in rats, but the underlying mechanisms are not fully understood. It has been well documented that the metabolic activation may play important roles in NDEA-induced hepatocarcinogenesis. Therefore, we designed the current study to explore the potential mechanisms by investigating the changes of hepatic phase Ⅰ enzymes (including cytochrome P450 enzyme (CYP) 2E1, CYP1A2 and CYP1A1) and phase Ⅱ enzymes (including glutathione S transferases (GSTs) and UDP- Glucuronosyltransferases (UGTs)) by using enzymatic methods, real-time PCR, and western blotting analysis. We found that NDEA treatment resulted in significant decreases of the activities of CYP2E1, CYP1A2, GST alpha, GST mu, UGTs and increases of the activities of CYP1A1 and GST pi. Furthermore, the mRNA and protein levels of CYP2E1, CYP1A2, GST alpha, GST mu and UGT1A6 in the liver of NDEA-treated rats were significantly decreased compared with those of the control group rats, while the mRNA and protein levels of CYP1A1 and GST pi were dramatically increased. Interestingly, all these adverse effects induced by NDEA were simultaneously and significantly suppressed by GO co-treatment. These data suggest that the protective effects of GO against NDEA-induced hepatocarcinogenesis might be, at least partially, attributed to the modulation of phase I and phase II enzymes.

The modulatory effects of garlic oil on hepatic cytochrome P450s in mice

In order to probe into the effects of garlic oil (GO) on the hepatic CYP2E1, CYP1A2 and CYP3A, male Kun-Ming mice were treated with GO (100 mg/kg body weight) or corn oil for 1 day or consecutive 60 days, respectively, and then the protein expressions and the activities of the enzymes were examined. GO did not alter the physical activities of mice and did not induce lesion to the liver. However, it dramatically inhibited the activities and protein levels of hepatic CYP2E1 and 1A2, but not CYP3A. In addition, we noticed that the inhibition of CYP2E1 and 1A2 by GO was more potent in group of 1 day treatment than those in group of 60 days treatment. Compared with the respective control value, the protein levels of CYP2E1 were decreased by 87.40% (p < .01) and 62.26% (p < .01) by 1 day and 60 days of GO treatment, respectively, while the CYP1A2 protein levels were decreased by 70.76% (p < .01) and 41.49% (p < .01), respectively. These data indicated that the mice could adapt to the prolonged treatment, which might be one reasonable explanation for the conflicting data in the literature. The CYP2E1 and 1A2 suppression might contribute to its hepatoprotection, and data about CYP3A indicated that GO was unlikely to alter the metabolism of the concomitantly used drugs.