Antioxidant and methyl donor effects of betaine versus ethanol-induced oxidative stress in the rat liver

Oxidative stress is one hypothesis for the association of ethanol consumption with cardiovascular, cerebrovascular, and liver diseases. Thus, we examined whether oral betaine can act as a preventive agent in ethanol-induced oxidative stress on the rat liver. A total of 32 male Sprague–Dawley rats were divided into four equal groups. The control group received normal saline. The ethanol group was administered ethanol (4 g/kg). The betaine group received betaine [1.5 % (w/w) of the total diet], and the betaine plus ethanol group (Bet. & Eth.) were administered with betaine; after 120 min, the rats received ethanol. All of the treatments were applied for 2 months via gavage. Elevation of glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities were observed in the betaine-treated groups. Thiobarbituric acid reactive substances (TBARS, an indicator of lipid peroxidation) concentration also decreased in the betaine-treated rats as compared to the ethanol group. There was also a significant reduction in plasma total homocysteine (tHcy) concentration in the betaine and Bet. & Eth. groups as compared to the ethanol-treated rats. In contrast, ethanol treatment in rats resulted in significant lower antioxidant enzyme activities (GPx and SOD), and indicated lipid peroxidation to the liver, as monitored by the elevation in TBARS level. Administration of ethanol to rats also induced toxicity in their liver, as shown by the histopathological findings, whereas betaine could suppress liver damages in the Bet. & Eth. group. Overall, oral pretreatment with betaine significantly prevented ethanol-induced oxidative stress and hyperhomocysteinemia via increasing antioxidant enzyme activities and decreasing tHcy concentration. Thus, betaine may be recommended as a therapeutic agent for patients with liver damages induced by oxidative stress in various diseases.     

CYP2E1 induced by ethanol causes oxidative stress, proteasome inhibition and cytokeratin aggresome (Mallory body-like) formation

The role of oxidative stress in alcoholic liver disease and cytokeratin aggresome formation is the focus of this in vitro study. HepG2 cells transduced to over express CYP2E1 (E47) and control HepG2 cells (C34) were first treated with arachidonic acid, then Fe-NAT, and finally with ethanol. In the E47 ethanol-treated cells, CYP2E1 was induced and a higher level of reactive oxygen species and carbonyl proteins were generated. The proteasome activity decreased significantly in the E47 ethanol-treated cells. This inhibition was prevented when CYP2E1 was inhibited by DAS. Microarray analysis showed gene expression down regulation of the proteasome subunit, as well as ubiquitin pathway proteins in the E47 ethanol-treated cells. 4-Hydroxynonenal (4-HNE) adducts were increased in the E47 cells treated with ethanol. Furthermore, the immunoprecipitated 4-HNE modified proteins from these cells stained positive with antibodies to the proteasome subunit alpha 6. These results indicate that the ethanol induced CYP2E1 generates oxidative stress that is responsible for the decrease in proteasome activity. Cytokeratin 8 and 18 were induced by ethanol treatment of E47 cells and polyubiquitinated forms of these proteins were found in the polyubiquitin smear upon Western blots analysis. Cytokeratin aggresomes and Mallory body-like inclusions formed in the ethanol-treated E47 cells, indicating that the ubiquitinated cytokeratins accumulated as a result of the inhibition of the proteasome by ethanol treatment when oxidation of ethanol induced oxidative stress. This is the first report where ethanol caused Mallory body-like cytokeratin inclusions in transformed human liver cells in vitro.     

Effects of epigallocatechin-3-gallate on pentylenetetrazole-induced kindling, cognitive impairment and oxidative stress in rats

Cognitive dysfunction is commonly observed in epileptic patients. It has been shown that not only epilepsy but also antiepileptic drugs could induce cognitive impairment. Thus, there is an urgent need for drugs that can suppress seizures without causing cognitive deficit. Recent studies have shown that oxidative stress is involved in the pathophysiology of epilepsy, and many antioxidants have an antiepileptic property. Epigallocatechin-3-gallate (EGCG), a catechin polyphenols component, is found to be an effective antioxidant. The purpose of this study was to assess the effect of EGCG against seizures, seizure-induced oxidative stress and cognitive impairment in pentylenetetrazole-induced kindling. Male Sprague-Dawley rats were injected intraperitoneally with a dose of 35 mg/kg of pentylenetetrazole (PTZ) once every alternate day for 13 injections. EGCG was administered daily in two doses (25mg/kg and 50mg/kg) intraperitoneally along with alternate-day PTZ. Morris water maze test was carried out 24h after the last injection of PTZ, and the oxidative stress parameters (malondialdehyde and glutathione) were assessed after the completion of the behavioral test. The results showed that EGCG dose-dependently suppressed the progression of kindling. EGCG also ameliorated the cognitive impairment and oxidative stress induced by PTZ kindling. These observations suggest that EGCG may be a potential agent for the treatment of epilepsy as well as a preventive agent against cognitive impairment induced by seizure.     

Redox signaling and the innate immune system in alcoholic liver disease

The development of alcoholic liver disease (ALD) is a complex process involving both parenchymal and nonparenchymal cells resident in the liver. Although the mechanisms for ALD are not completely understood, it is clear that increased oxidative stress, and activation of the innate immune system are essential elements in the pathophysiology of ALD. Oxidative stress from ethanol exposure results from increased generation of reactive oxygen species and decreased hepatocellular antioxidant activity, including changes in the thioredoxin/peroxiredoxin family of proteins. Both cellular and circulating components of the innate immune system are activated by exposure to ethanol. For example, ethanol exposure enhances toll-like receptor-4 (TLR-4)-dependent cytokine expression by Kupffer cells, likely due, at least in part, to dysregulation of redox signaling. Similarly, complement activation in response to ethanol leads to increased production of the anaphylatoxins, C3a and C5a, and activation C3a receptor and C5a receptor. Complement activation thus contributes to increased inflammatory cytokine production and can influence redox signaling. Here we will review recent progress in understanding the interactions between oxidative stress and innate immunity in ALD. These data illustrate that ethanol-induced oxidative stress and activation of the innate immune system interact dynamically during ethanol exposure, exacerbating ethanol-induced liver injury.     

S-adenosylmethionine prevents the up regulation of Toll-like receptor (TLR) signaling caused by chronic ethanol feeding in rats

Toll-like receptors (TLR) play a role in mediating the proinflammatory response, fibrogenesis and carcinogenesis in chronic liver diseases such as alcoholic liver disease, non-alcoholic liver disease, hepatitis C and hepatocellular carcinoma. This is true in experimental models of these diseases. For this reason, we investigated the TLR proinflammatory response in the chronic intragastric tube feeding rat model of alcohol liver disease. The methyl donor S-adenosylmethionine was also fed to prevent the gene expression changes induced by ethanol. Ethanol feeding tended to increase the up regulation of the gene expression of TLR2 and TLR4. SAMe feeding prevented this. TLR4 and MyD88 protein levels were significantly increased by ethanol and this was prevented by SAMe. This is the first report where ethanol feeding induced TLR2 and SAMe prevented the induction by ethanol. CD34, FOS, interferon responsive factor 1 (IRF-1), Jun, TLR 1,2,3,4,6 and 7 and Traf-6 were found to be up regulated as seen by microarray analysis where rats were sacrificed at high blood alcohol levels compared to pair fed controls. Il-6, IL-10 and IFNγ were also up regulated by high blood levels of ethanol. The gene expression of CD14, MyD88 and TNFR1SF1 were not up regulated by ethanol but were down regulated by SAMe. The gene expression of IL-1R1 and IRF1 tended to be up regulated by ethanol and this was prevented by feeding SAMe. The results suggest that SAMe, fed chronically prevents the activation of TLR pathways caused by ethanol. In this way the proinflammatory response, fibrogenesis, cirrhosis and hepatocellular carcinoma formation due to alcohol liver disease could be prevented by SAMe.     

Betaine feeding prevents the blood alcohol cycle in rats fed alcohol continuously for 1 month using the rat intragastric tube feeding model

Background

Blood alcohol levels (BAL) cycle up and down over a 7–8 day period when ethanol is fed continuously for one month in the intragastric tube feeding rat model (ITFRM) of alcoholic liver disease. The cycling phenomenon is due to an alternating increase and decrease in the metabolic rate. Recently, we found that S-adenosyl-methionine (SAMe) fed with alcohol prevented the BAL cycle.

Method

Using the ITFRM we fed rats betaine (2 g/kg/day) with ethanol for 1 month and recorded the daily 24 h urine ethanol level (UAL) to measure the BAL cycle. UAL is equivalent to BAL because of the constant ethanol infusion. Liver histology, steatosis and BAL were measured terminally after 1 month of treatment. Microarray analysis was done on the mRNA extracted from the liver to determine the effects of betaine and alcohol on changes in gene expression.

Results

Betaine fed with ethanol completely prevented the BAL cycle similar to SAMe. Betaine also significantly reduced the BAL compared to ethanol fed rats without betaine. This was also observed when SAMe was fed with ethanol. The mechanism involved in both cases is that SAMe is required for the conversion of epinephrine from norepinephrine by phenylethanolamine methyltransferase (PNMT). Epinephrine is 5 to 10 fold more potent than norepinephrine in increasing the metabolic rate. The increase in the metabolic rate generates NAD, permitting ADH to increase the oxidation of alcohol. NAD is the rate limiting factor in oxidation of alcohol by alcohol dehydrogenase (ADH). This explains how SAMe and betaine prevented the cycle. Microarray analysis showed that betaine feeding prevented the up regulation of a large number of genes including TLR2/4, Il-1b, Jax3, Sirt3, Fas, Ifngr1, Tgfgr2, Tnfrsf21, Lbp and Stat 3 which could explain how betaine prevented fatty liver.

Conclusion

Betaine feeding lowers the BAL and prevents the BAL cycle by increasing the metabolic rate. This increases the rate of ethanol elimination by generating NAD.     

Epigallocatechin gallate attenuates adhesion and migration of CD8+ T cells by binding to CD11b

BACKGROUND: Although green tea polyphenol catechin has been reported to have antiallergic and anti-inflammatory activities, the precise mechanisms of its effect on the immune system have been poorly investigated. OBJECTIVE: In this study, we aimed to elucidate the mechanisms of the anti-inflammatory effect of catechin. For this purpose, we studied the effect of 2 kinds of catechin, epigallocatechin gallate (EGCG) and epicatechin gallate, on peripheral blood CD8+ T cells, which play the key role in immune responses. METHODS: Isolated peripheral blood mononuclear cells or CD8+ T cells were incubated without or with catechin, and the changes in the surface expression of integrin molecules were investigated by flow cytometry and the direct binding of catechin to CD11b molecule by competitive ELISA. Also, the effect of catechin on the ability of CD8+ T cells to bind intracellular adhesion molecule 1 and to migrate in response to chemokines was evaluated by using the adhesion and migration assays. RESULTS: The 2 catechins directly bound to CD11b expressed on CD8+ T cells, which caused a consequent decrease of flow-cytometric CD11b expression. The effect was more prominent with EGCG than epicatechin gallate, and the impaired expression of CD11b induced by EGCG resulted in decreased ability of CD8+ T cells to adhere intercellular adhesion molecule 1, and consequently decreased migration in response to chemokines. CONCLUSION: We concluded that catechin, especially EGCG, by downregulating CD11b expression on CD8+ T cells and, in consequence, inhibiting infiltration of these cells into the sites of inflammation, is a promising new potent anti-inflammatory agent.     

Role of neuronal nitric oxide synthase in the antiallodynic effects of intrathecal EGCG in a neuropathic pain rat model

Epigallocatechin-3-gallate (EGCG), the major catechin in green tea, is known to have antioxidant activity against nitric oxide (NO) by scavenging free radicals, chelating metal ions, and inducing endogenous antioxidant enzymes. NO and NO synthase (NOS) play an important role in nociceptive processing. In this study, we examined the effects of intrathecal EGCG in neuropathic pain induced by spinal nerve ligation and the possible involvement of NO. Intrathecal EGCG attenuated mechanical allodynia in spinal nerve ligated-rats, compared to sham-operated rats, with a maximal possible effect of 69.2%. This antinociceptive effect was reversed by intrathecal pretreatment with l-arginine, a precursor of NO. Intrathecal EGCG also blocked the increase in nNOS expression in the spinal cord of spinal nerve-ligated rats, but iNOS expression was not significantly suppressed. These findings suggest that intrathecal EGCG could produce an antiallodynic effect against spinal nerve ligation-induced neuropathic pain, mediated by blockade of nNOS protein expression and inhibition of the pronociceptive effects of NO.     

The effect of betaine treatment on triglyceride levels and oxidative stress in the liver of ethanol-treated guinea pigs

We investigated the effect of betaine supplementation on ethanol induced steatosis and alterations in prooxidant and antioxidant status in the liver of guinea pigs. Animals were fed with normal chow or betaine containing chow (2% w/w) for 30 days. Ethanol (3 g/kg, i.p.) was given for the last 10 days. We found that ethanol treatment caused significant increases in plasma transaminase activities, hepatic triglyceride and lipid peroxide levels. Significant decreases in glutathione (GSH), -tocopherol and total ascorbic acid (AA) levels were also observed, but hepatic superoxide dismutase, glutathione peroxidase and glutathione transferase activities remained unchanged as compared with those in controls. Betaine treatment together with ethanol in guinea pigs is found to decrease hepatic triglyceride, lipid peroxide levels and serum transaminase activities and to increase GSH levels. No changes in a-tocopherol and total AA levels and antioxidant enzyme activities were observed with betaine treatment in alcohol treated guinea pigs. In addition, histopathological assessment of guinea pigs showed that betaine reduced the alcoholic fat accumulation in the liver. Based on these data, betaine treatment has a restoring effect on the alterations in triglyceride, lipid peroxide and GSH levels following ethanol ingestion.     

The regulation of non-coding RNA expression in the liver of mice fed DDC

Mallory-Denk bodies (MDBs) are found in the liver of patients with alcoholic and chronic nonalcoholic liver disease, and hepatocellular carcinoma (HCC). Diethyl 1,4-dihydro-2,4,6,-trimethyl-3,5-pyridinedicarboxylate (DDC) is used as a model to induce the formation of MDBs in mouse liver. Previous studies in this laboratory showed that DDC induced epigenetic modifications in DNA and histones. The combination of these modifications changes the phenotype of the MDB forming hepatocytes, as indicated by the marker FAT10. These epigenetic modifications are partially prevented by adding to the diet S-adenosylmethionine (SAMe) or betaine, both methyl donors. The expression of three imprinted ncRNA genes was found to change in MDB forming hepatocytes, which is the subject of this report. NcRNA expression was quantitated by real-time PCR and RNA FISH in liver sections. Microarray analysis showed that the expression of three ncRNAs was regulated by DDC: up regulation of H19, antisense Igf2r (AIR), and down regulation of GTL2 (also called MEG3). S-adenosylmethionine (SAMe) feeding prevented these changes. Betaine, another methyl group donor, prevented only H19 and AIR up regulation induced by DDC, on microarrays. The results of the SAMe and betaine groups were confirmed by real-time PCR, except for AIR expression. After 1 month of drug withdrawal, the expression of the three ncRNAs tended toward control levels of expression. Liver tumors that developed also showed up regulation of H19 and AIR. The RNA FISH approach showed that the MDB forming cells' phenotype changed the level of expression of AIR, H19 and GTL2, compared to the surrounding cells. Furthermore, over expression of H19 and AIR was demonstrated in tumors formed in mice withdrawn for 9 months. The dysregulation of ncRNA in MDB forming liver cells has been observed for the first time in drug-primed mice associated with liver preneoplastic foci and tumors.     

表儿茶素可降低醛固酮造成的胰岛β细胞损伤

目的：研究表没食子儿茶素没食子酸酯（ epigallocatechin gallate, EGCG）是否可以对醛固酮（ aldosterone, ALD）造成的胰岛β细胞功能障碍和凋亡起到保护作用。方法用不同浓度的EGCG处理胰岛β细胞后给予ALD刺激。通过放射性免疫与MTT方法检测其胰岛β细胞功能和凋亡,同时用Western印迹检测肌腱膜纤维肉瘤癌基因同系物A （ v?maf musculoaponeurotic fibrosarcoma oncogene homolog A, MafA）的蛋白表达水平。结果给予胰岛β细胞不同浓度的EGCG处理后可以浓度梯度依赖性的保护胰岛β细胞免受由ALD造成的功能障碍与凋亡,且能够恢复MafA的表达。结论 EGCG可以对ALD造成的胰岛β细胞的功能障碍和凋亡起到保护作用,这可能与EGCG维持MafA的表达有关。     

Protective effect of apocynin in an established alcoholic steatohepatitis rat model

Apocynin is a widely used antioxidant in both basic and clinical research. The current study aimed to investigate the protective effect of apocynin in an established alcoholic steatohepatitis rat model. Healthy SD rats were gastrically fed with ethanol (4.0?g/kg) for 8 weeks to induce alcoholic steatohepatitis. After 8 weeks, rats were fed with ethanol for another 2 weeks with or without a daily intraperitoneal injection of 25?mg/kg apocynin. After sacrificing, serum and liver samples were subjected to hepatic injury measurements. After 8-week ethanol induction, rats exhibited typical alcoholic steatohepatitis features including reduced body weight, hepatic histological changes, elevated serum alanine transaminase (ALT) level, increased levels of oxidative stress and inflammatory markers, NADPH oxidases, and renin-angiotensin system (RAS) marker. Co-treatment of apocynin alleviated the hepatic injury and biochemical parameters induced by alcoholic steatohepatitis. In conclusion, addition of apocynin significantly attenuates hepatic oxidative stress and inflammation induced by alcoholic steatohepatitis. This effect is partly through the inhibition of the RAS system.     

The effect of 1,25-dihydroxyvitamin D3 on liver damage,oxidative stress,and advanced glycation end products in experimental nonalcoholic- and alcoholic- fatty liver disease

Background/aim Oxidative stress and advanced glycation end products (AGEs) formation are proposed as effective mechanisms in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) and alcoholic liver disease (ALD). 1,25(OH)2D3 was proposed to have antioxidant, antiinflammatory and antiglycation properties. In this study, the effect of 1,25(OH)2D3 treatment on oxidative stress parameters and AGEs levels together with hepatic histopathology was investigated in high fructose (HFr) or ethanol (EtOH)-treated rats. Materials and methods Rats were treated with fructose (30%) or ethanol (5-20%) in drinking water with and without 1,25(OH)2D3 treatment (5 µg/kg two times a week) for 8 weeks. Insulin resistance (IR), oxidative stress parameters, AGEs, triglyceride (TG), and hydroxyproline (Hyp) levels together with histopathology were investigated in the liver. Results1,25(OH)2D3 decreased hepatic reactive oxygen species, lipid and protein oxidation products together with histopathological improvements in HFr- and EtOH-treated rats. 1,25(OH)2D3 treatment was observed to decrease significantly serum and hepatic AGEs in HFr group, and hepatic AGEs in EtOH group.Conclusion Our results clearly show that 1,25(OH)2 D3 treatment may be useful in the alleviation of hepatic lesions by decreasing glycooxidant stress in both NAFLD and ALD models created by HFr- and EtOH-treated rats, respectively.     

Epigallocatechin gallate induces apoptosis of monocytes

BACKGROUND: Monocytes are the main effector cells of the immune system, and the regulation of their survival and apoptosis is essential for monocyte-involved immune responses. Green tea polyphenol catechin has been reported to have antiallergic and anti-inflammatory activities, but its effect on monocytes has not yet been explored. OBJECTIVE: To elucidate the mechanisms of the anti-inflammatory effect of catechin, we studied the effect of catechin, especially epigallocatechin gallate (EGCG), on the apoptosis of monocytes. METHODS: Isolated peripheral blood monocytes were incubated without or with catechin, and apoptosis was evaluated by annexin V and propidium iodide double-staining or terminal deoxynucleotidyl assay. The activation of caspases 3, 8, and 9 was also evaluated by flow cytometry. The influence of GM-CSF or LPS, the known monocyte survival factors, on the EGCG-induced apoptosis of monocytes was investigated. RESULTS: Among the 4 catechin derivatives tested, EGCG and epicatechin gallate induced apoptosis of monocytes. Caspases 3, 8, and 9, which play a central role in the apoptotic cascade, were dose-dependently activated by EGCG treatment. The EGCG-induced apoptosis of monocytes was not affected by GM-CSF or LPS. CONCLUSION: Catechin, especially EGCG, by promoting monocytic apoptosis, may be a new promising anti-inflammatory agent, and should be tested in clinical trials.     

Antioxidant effects of oleuropein versus oxidative stress induced by ethanol in the rat intestine

Purified oleuropein from olive leaf extract indicated antioxidant properties in our previous reports. The recent study demonstrated that the lesions of absolute ethanol could be attributed to the increasing reactive oxygen species, subsequently lipid peroxidation and gastric ulcers. Therefore, the antioxidant effects of oleuropein as a natural antioxidant agent on intestine mucosal damages induced by absolute ethanol were investigated in the present study. The 42 adult male rats were divided into four (control, oleuropein, ethanol, and oleuropein plus ethanol) groups. Oleuropein at a dosage of 12 mg/kg was used for 10 consecutive days in oleuropein and oleuropein plus ethanol groups, thereafter absolute ethanol (once, 1 ml/rat) was administrated orally in ethanol and oleuropein plus ethanol groups at fasting state by gavage. The duodena of rats were removed for histopathology and antioxidant assay. Histological evidence of severe mucosal damages were confirmed by histopathology findings in ethanol group and prevented in oleuropein plus ethanol group. In this setting, glutathione peroxidase and catalase activities were significantly higher in oleuropein and oleuropein plus ethanol groups than the ethanol-treated rats. In contrast, thiobarbituric acid reactive substances concentration (as a lipid peroxidation marker) significantly increased in ethanol-treated rats when compared to the other groups. Our results suggest that olive leaf extract (containing oleuropein) exerts a potent antioxidant agent against oxidative stress. These findings allow us to exploit the advantages of oleuropein treatment in various diseases induced by oxidative stress in humans.     

Uncoupling of oxidative phosphorylation prevents the urinary alcohol level cycling caused by feeding ethanol continuously at a constant rate

The mechanism of the UAL cycle in the intragastric feeding model of alcoholic liver disease in the rat was investigated by administering dinitrophenol (DNP) with ethanol in the diet. The question was: is the rate of oxidative phosphorylation fluxuation essential for the cycle to occur? The question has been partially answered by showing that rotenone, which inhibits complex I, blocks the cycle by preventing the generation of NAD from NADH. This would inhibit ATP generation from complex I but would not affect oxidative phosphorylation by complex 2 and 3. Since the rate of O2 consumption is normal at the troughs of the cycle and decreases at the peaks of the cycle and the levels of ATP are reduced at the peaks of the cycle, it is likely that the rate of oxidative phosphorylation also cycles. Since 2-4 dinitrophenol (DNP) uncouples oxidative phosphorylation, it was anticipated that feeding it with ethanol would prevent the cycle from occurring. This proved to be the case. In addition, DNP caused energy wasting and prevented the increase in serum alanine aminotranspeptidase caused by ethanol feeding, probably by preventing the hypoxia which occurs at the peaks of the cycle.     

Chlorella vulgaris extract ameliorates carbon tetrachloride-induced acute hepatic injury in mice

The possible protective effects of Chlorella vulgaris extract (CVE) on carbon tetrachloride (CCl₄)-induced acute hepatic injury in mice and the mechanism underlying these effects was investigated. CCl₄ administration caused a marked increase in the levels of serum aminotransferases, lipid peroxidation and cytochrome P450-2E1 (CYP450) expression. Also, decreased glutathione (GSH) content and activities of cellular antioxidant defense enzymes such as superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase and glutathione-S-transferase (GST) were found after CCl₄ exposure. All of these phenotypes were markedly reversed by preadministration of the mice with CVE. In addition, CVE exhibited antioxidant effects on FeCl₂–ascorbate induced lipid peroxidation in mouse liver homogenates, and on superoxide radical scavenging activity. Taken together, these results suggest that CVE produced a protective action on CCl₄-induced acute hepatic injury in mice, presumably through blocking CYP-mediated CCl₄ bioactivation, inducing the GSH levels, antioxidant enzyme activities and free radical scavenging effect. Therefore, CVE may be an effective hepatoprotective agent and viable candidate for treating hepatic disorders and other oxidative stress-related diseases.     

Hepatocyte proliferation is the possible mechanism for the transient decrease in liver injury during steatosis stage of alcoholic liver disease

Steatosis is a frequent pathologic stage in alcoholic liver disease (ALD). Although the mechanisms for increased susceptibility of steatotic liver to injury have been postulated, the ability of these hepatocytes to proliferate and withstand injury is unknown. There are conflicting reports on the status of hepatocyte regeneration following chronic alcohol ingestion. Hence, the objective of this study was to investigate the temporal dynamics between the pattern of liver injury and hepatocyte proliferation during the steatosis stage of ALD. Alcoholic steatosis was induced in male Sprague-Dawley rats by feeding an ethanol (EtOH)-containing Lieber-DeCarli liquid diet for a period of 5 weeks. Microvesicular steatosis was evident in H&E sections by three weeks in the EtOH-treated rats, which further developed into panlobular macrovesicular steatosis by 5 weeks. Plasma transaminase activities indicated progressive increase in liver injury peaking at 3 weeks with significant but mild decrease at 4 and 5 weeks. CYP2E1 protein and activity was significantly increased in EtOH-fed rats as measured by Western blot and pNP hydroxylation assay. PCNA analysis of liver sections indicated that EtOH-treated rats had a significantly higher number of cells in S phase of cell division at weeks 1 (3.20 +/- 0.19), 2 (7.03 +/- 0.92), and 3 (4.23 +/- 1.41) when compared to controls (1.5 +/- 0.22). NF-kappaB DNA binding and Cyclin D1 proteins increased significantly in the EtOH-treated rats corresponding with enhanced hepatic proliferation. These data suggest the transient decline in liver injury during alcoholic steatosis is due to enhanced NF-kappaB-dependent hepatocyte proliferation.     

Epigallocatechin gallate, the main component of tea polyphenol, binds to CD4 and interferes with gp120 binding

BACKGROUND: Epigallocatechin gallate (EGCG), the major component of tea polyphenol, has been reported to have various physiologic modulatory activities. Several reports also have shown that catechin has a protective effect against HIV infection, part of which is mediated by inhibiting virions to bind to the target cell surface. OBJECTIVE: We investigated the effect of EGCG on the expression of CD4 molecules and on its ability to bind gp120, an envelope protein of HIV-1. METHODS: Peripheral blood CD4+ T cells were incubated in the presence of EGCG, and the expression of CD4 was evaluated by means of flow cytometry. The effect of EGCG on the antibody binding to CD4 was investigated by using a sandwich ELISA, and the effect on the gp120 binding to CD4 was analyzed by means of flow cytometry. RESULTS: EGCG efficiently inhibited binding of anti-CD4 antibody to its corresponding antigen. This effect was mediated by the direct binding of EGCG to the CD4 molecule, with consequent inhibition of antibody binding, as well as gp120 binding. CONCLUSION: The present results suggest a potential preventive effect of EGCG on HIV-1 infection by modulating binding to CD4.