Bicyclol attenuates tetracycline-induced fatty liver associated with inhibition of hepatic ER stress and apoptosis in mice.

Endoplasmic reticulum (ER) stress is known to be involved in the development of several metabolic disorders, including non-alcoholic fatty liver disease (NAFLD). Tetracycline can cause hepatic steatosis, and ER stress may be involved in tetracycline-induced fatty liver. Our previous study showed that bicyclol has been proven to protect against tetracycline-induced fatty liver in mice, and ER stress may also be involved in bicyclol's hepatoprotective effect. Therefore, this study was performed to investigate the underlying mechanisms associated with ER stress and apoptosis, by which bicyclol attenuated tetracycline-induced fatty liver in mice. Bicyclol (300 mg/kg) was given to mice by gavage 3 times. Tetracycline (200 mg/kg, intraperitoneally) was injected at 1 h after the last dose of bicyclol. At 6 h and 24 h after single dose of tetracycline injection, serum ALT, AST, TG, CHO and hepatic histopathological examinations were performed to evaluate liver injuries. Hepatic steatosis was assessed by the accumulation of hepatic TG and CHO. Moreover, hepatic apoptosis and ER stress related markers were determined by TUNEL, real-time PCR, and western blot. As a result, bicyclol significantly protected against tetracycline-induced fatty liver as evidenced by the decrease of elevated serum transaminases and hepatic triglyceride, and the attenuation of histopathological changes in mice. In addition, bicyclol remarkably alleviated hepatic apoptosis and the gene expression of caspase-3, and increased the gene expression of XIAP. The gene expressions of ER stress-related markers, including CHOP, GRP78, IRE-1α, and ATF6, which were downregulated by bicyclol pretreatment in tetracycline-injected mice. These results suggested that bicyclol protected tetracycline-induced fatty liver partly due to its ability of anti-apoptosis associated with ER stress.

Effects of bicyclol on the activity and expression of CYP450 enzymes of rats after partial hepatectomy.

The present study was performed to investigate the effect of bicyclol on hepatic microsomal cytochrome P450 (CYP) activity, as well as gene and protein expressions in rats after partial hepatectomy (PH). Bicyclol (300 mg x kg(-1)) was given to rats subjected to 70% hepatectomy three times before operation. At 6 and 48 h after PH, blood and liver tissue samples were collected for the measurement of serum alanine aminotransferase (ALT), hepatic microsomal malondialdehyde (MDA) and total hepatic CYP content. The activities of four CYP isozymes were detected with liquid chromatography-mass spectrometry (LC-MS) and the gene and protein expressions were determined by RT-PCR and Western blotting assay. As a result, bicyclol pretreatment markedly inhibited the elevation of serum ALT and hepatic microsomal MDA, and prevented the decrease of total hepatic CYP content in PH rats. In addition, bicyclol significantly attenuated the reduction of CYP2C6 activity and mRNA expression, as well as the reduction of CYP2C11 activity in PH rats. Bicyclol can inhibit the decrease of CYP3A1/2 activity, and up-regulate the mRNA and protein expressions of CYP3A1 and CYP2E1. These results showed that bicyclol pretreatment might ameliorate abnormality in CYP450 isoforms during liver regeneration after PH, and this protective effect was likely due to its anti-oxidative property and enzyme induction.

Mechanism of Huo-Xue-Qu-Yu Formula in Treating Nonalcoholic Hepatic Steatosis by Regulating Lipid Metabolism and Oxidative Stress in Rats.

Huo-Xue-Qu-Yu formula (HXQYF) is a prescription consisting of Ginkgo biloba leaf and Paeonia lactiflora Pall. for treating hyperlipidemia and NAFLD in China. Here, we investigated the hepatic and renal function, oxidative stress and lipid metabolism, and potential mechanisms of HXQYF on nonalcoholic fatty liver disease (NAFLD) rat models. NAFLD rat models were induced with high-fat diet (HFD) and 10% fructose water for 18 weeks and orally administered with or without HXQYF simultaneously. The results showed that HXQYF (22.5, 45, 90 mg/kg) significantly improved blood lipid levels via reducing serum TC, TG, LDL-C, and APOB values and elevating HDL-C and APOA1 levels in NAFLD rats. The higher levels of ALT, AST, CR, and BUN in serum induced by HFD were reduced by HXQYF. HE staining showed that HXQYF (90 mg/kg) reduced the accumulation of fat droplets and alleviated inflammatory response in liver cells. Three doses of HXQYF exhibited notable antioxidant effects by elevating SOD, GSH, and CAT activities and decreasing MDA and OH-1 levels in the liver. Furthermore, abnormal lipid metabolism caused by HFD was alleviated by HXQYF, which was associated with the upregulation of PPAR-α, AdipoR2, and CPT1 mRNAs as well as the downregulation of CYP2E1 and SREBP-1c mRNAs in liver tissue. In conclusion, our work verified that HXQYF could reduce the degree of hepatic steatosis, suppress oxidative stress, and attenuate lipid metabolism, thus preventing NAFLD.

Effects of bicyclol on immunological liver fibrosis in rats.

Liver fibrosis results from chronic liver injury in conjunction with the accumulation of extracellular matrix proteins. The present study was performed to estimate the effect of bicyclol on bovine serum albumin (BSA)-induced immunological liver fibrosis in rats. Bicyclol (1) (100, 200, and 300 mg/kg) was given to rats by oral administration once a day for 5 weeks from the fourth week of intravenous injection of BSA. Blood and liver tissues were collected for the measurement of hydroxyproline (Hyp), procollagen type III (PIIIP), hyaluronic acid (HA), and transforming growth factor beta-1 (TGF-beta1) levels and liver pathological changes. The mRNA and protein expressions of hepatic TGF-beta1, interleukin-1 (IL-1), IL-10, MMP-2, TIMP-1, phosphorylated p38 (Pp38), and Smad2/3 were detected by reverse transcription polymerase chain reaction and Western blot. As a result, bicyclol significantly protected against BSA-induced liver fibrosis as evidenced by the reduction of elevated serum HA, PIIIP, and hepatic Hyp in rats, while liver pathological changes were also alleviated. The overexpressions of hepatic TGF-beta1, IL-1beta, IL-10, MMP-2, and TIMP-1 were suppressed by bicyclol in BSA-treated rats. The phosphorylations of Pp38 and Smad2/3 were also inhibited after bicyclol treatment. The hepatoprotection of bicyclol was mainly due to the modulation on the expression of inflammatory/anti-inflammatory cytokines, downregulation of hepatic TGF-beta1, and inhibition of hepatic collagen synthesis.

Protective effect of bicyclol on liver injury induced by hepatic warm ischemia/reperfusion in rats.

AIM: Bicyclol is a synthetic anti-hepatitis drug with anti-oxidative property. The purpose of this study was to investigate the effect of bicyclol on hepatic ischemia/reperfusion (I/R) injury and related mechanisms. METHODS: Rats were subjected to 90 min of hepatic ischemia followed by reperfusion for 1, 3, 6 and 24 h. Three doses of bicyclol were orally administered before ischemia. Liver injury was evaluated by biochemical and histopathological examinations. Liver malondialdehyde (MDA), superoxide dismutase (SOD), nitric oxide (NO), inducible nitric oxide synthase (iNOS) and myeloperoxidase (MPO) contents, and plasma endotoxin levels were spectrophotometrically measured. The expressions of inflammatory and anti-inflammatory cytokines were detected by reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay. Liver intercellular adhesion molecule-1 (ICAM-1) was examined by immunohistochemistry, and the expressions of nuclear factor (NF)-kappaB, inhibitor of NF-kappaB (IkappaB) and toll-like receptor 4 (TLR4) were determined by western blot. RESULTS: Bicyclol significantly inhibited the elevations of serum alanine aminotransferase, total bilirubin and plasma endotoxin levels, alleviated the formation of liver MDA and nitrite/nitrate, restored impaired antioxidant SOD, attenuated hepatic necrosis and neutrophil infiltration, and also improved the 7-day survival in I/R rats. Additionally, bicyclol markedly downregulated the overexpression of ICAM-1, modulated the expression of inflammatory/anti-inflammatory cytokines and inhibited the expression of NF-kappaB and TLR4 in I/R rats. CONCLUSION: Bicyclol had a remarkable protective effect on hepatic I/R injury, which was partially due to inhibiting the expression of TLR4 and NF-kappaB via its ability to attenuate oxidative stress and endotoxin.

Effects of bicyclol on liver regeneration after partial hepatectomy in rats.

Bicyclol is a synthetic antihepatitis drug with antioxidative property. The present study was performed to investigate the effect of bicyclol on liver regeneration after partial hepatectomy in rats. Bicyclol (300 mg/kg) was given to rats subjected to 70% hepatectomy three times before operation. At 6, 24, and 48 h after resection, samples were collected for the measurement of serum alanine aminotransferase (ALT), total bilirubin (TBil), hepatic glycogen, malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione (GSH). Moreover, liver regeneration rate, proliferating cell nuclear antigen (PCNA) labeling, proliferation index, and histopathological examination were evaluated at 48 h after hepatectomy. As a result, bicyclol significantly increased regeneration rate, mitotic index (MI), PCNA labeling index, and proliferation index in PH rats. Additionally, bicyclol remarkably inhibited the elevation of serum ALT and TBil levels, alleviated the formation of liver MDA, restored impaired antioxidant SOD and GSH, increased hepatic glycogen content, and also attenuated hepatic vacuolar degeneration. These results suggested that bicyclol had a beneficial effect on liver regenerative capacity of the remnant liver tissue after hepatectomy, probably due to its antioxidative property.

Human acyl-CoA:cholesterol acyltransferase 2 gene expression in intestinal Caco-2 cells and in hepatocellular carcinoma.

Humans express two ACAT (acyl-CoA:cholesterol acyltransferase) genes, ACAT1 and ACAT2. ACAT1 is ubiquitously expressed, whereas ACAT2 is primarily expressed in intestinal mucosa and plays an important role in intestinal cholesterol absorption. To investigate the molecular mechanism(s) responsible for the tissue-specific expression of ACAT2, we identified five cis-elements within the human ACAT2 promoter, four for the intestinal-specific transcription factor CDX2 (caudal type homeobox transcription factor 2), and one for the transcription factor HNF1alpha (hepatocyte nuclear factor 1alpha). Results of luciferase reporter and electrophoretic mobility shift assays show that CDX2 and HNF1alpha exert a synergistic effect, enhancing the ACAT2 promoter activity through binding to these cis-elements. In undifferentiated Caco-2 cells, the ACAT2 expression is increased when exogenous CDX2 and/or HNF1alpha are expressed by co-transfection. In differentiated Caco-2 cells, the ACAT2 expression significantly decreases when the endogenous CDX2 or HNF1alpha expression is suppressed by using RNAi (RNA interference) technology. The expression levels of CDX2, HNF1alpha, and ACAT2 are all greatly increased when the Caco-2 cells differentiate to become intestinal-like cells. These results provide a molecular mechanism for the tissue-specific expression of ACAT2 in intestine. In normal adult human liver, CDX2 expression is not detectable and the ACAT2 expression is very low. In the hepatoma cell line HepG2 the CDX2 expression is elevated, accounting for its elevated ACAT2 expression. A high percentage (seven of fourteen) of liver samples from patients affected with hepatocellular carcinoma exhibited elevated ACAT2 expression. Thus, the elevated ACAT2 expression may serve as a new biomarker for certain form(s) of hepatocellular carcinoma.

[Study on the strategy of interrupting schistosomiasis transmission in a hilly new endemic area of Taoyuan County].

OBJECTIVE: To develop a strategy for interrupting the transmission of schistosomiasis japonica in a hilly new endemic area. METHODS: Since 1996, chemotherapy with praziquantel (adult 40 mg/kg, child 50 mg/kg, cattle 30 mg/kg, once a year) on human beings in Taoyuan County who had ever contacted with infectious water and cattle which were herded in endemic situation was the major intervention, with focal control of Oncomelania snails in susceptible areas as supplementary one. RESULTS: The positive rate of stool examination for schistosomiasis in human and cattle reduced from 5.69% and 6.76% in 1996 to 0.04% and 0 in 2005 respectively. The positive rate of indirect hemagglutination test (IHA) in human dropped from 7.45% in 1996 to 1.61% in 2004. Though living snails were still found in most habitats, the density of infected snails decreased from 0.0036/0.11m2 in 1997 to 0 in 2005 and no infected snails were found since 2000. CONCLUSION: Due to less movement of human and cattle populations and the hilly area relatively isolated, chemotherapy combined with focal mollusciciding have been highly effective in eliminating the infection sources and interrupting transmission of schistosomiasis.

Computational design of glutamate dehydrogenase in Bacillus subtilis natto.

Bacillus subtilis natto is widely used in industry to produce natto, a traditional and popular Japanese soybean food. However, during its secondary fermentation, high amounts of ammonia are released to give a negative influence on the flavor of natto. Glutamate dehydrogenase (GDH) is a key enzyme for the ammonia produced and released, because it catalyzes the oxidative deamination of glutamate to alpha-ketoglutarate using NAD(+) or NADP(+) as co-factor during carbon and nitrogen metabolism processes. To solve this problem, we employed multiple computational methods model and re-design GDH from Bacillus subtilis natto. Firstly, a structure model of GDH with cofactor NADP(+) was constructed by threading and ab initio modeling. Then the substrate glutamate were flexibly docked into the structure model to form the substrate-binding mode. According to the structural analysis of the substrate-binding mode, Lys80, Lys116, Arg196, Thr200, and Ser351 in the active site were found could form a significant hydrogen bonding network with the substrate, which was thought to play a crucial role in the substrate recognition and position. Thus, these residues were then mutated into other amino acids, and the substrate binding affinities for each mutant were calculated. Finally, three single mutants (K80A, K116Q, and S351A) were found to have significant decrease in the substrate binding affinities, which was further supported by our biochemical experiments.

Protective effect of bicyclol on tetracycline-induced fatty liver in mice.

Peroxisome proliferators-activated receptor alpha (PPARalpha) and oxidative stress are two important pathological factors in non-alcoholic fatty liver disease (NAFLD). Tetracycline-induced fatty liver was partly due to the disturbance of mitochondrial fatty acids beta-oxidation regulated by PPARalpha. Bicyclol was found to protect against high fat diet-induced fatty liver through modulating PPARalpha and clearing reactive oxygen species (ROS). The present study was performed to further investigate the effect of bicyclol on tetracycline-induced fatty liver and related mechanism in mice. Bicyclol (75, 150, 300 mg/kg) was given orally three times in two consecutive days. Tetracycline (200 mg/kg) was injected intraperitoneally 1h after the last administration of bicyclol. Oxidative stress, mitochondrial function, PPARalpha and its target genes were evaluated by biochemical and RT-PCR analysis. The activity of CYP4A was assessed by liquid chromatography/mass spectrometry (LC/MS) method. Bicyclol significantly protected against tetracycline-induced fatty liver by reducing the accumulation of hepatic lipids and elevation of serum aminotransferase. In addition, bicyclol remarkably alleviated the over-production of thiobarbituric acid-reactive substance. The reduced activity of mitochondrial respiratory chain (MRC) complexes I and IV and mitochondrial permeability transition (MPT) were also improved by bicyclol. Furthermore, bicyclol inhibited the decrease of PPARalpha expression and its target genes, including long-chain acyl CoA dehydrogenase (LCAD), acetyl CoA oxidase (AOX) and CYP4A at mRNA and enzyme activity level. Bicyclol protected against tetracycline-induced fatty liver mainly through modulating the disturbance of PPARalpha pathway and ameliorating mitochondrial function.

Two human ACAT2 mRNA variants produced by alternative splicing and coding for novel isoenzymes.

Acyl coenzyme A:cholesterol acyltransferase 2 (ACAT2) plays an important role in cholesterol absorption. Human ACAT2 is highly expressed in small intestine and fetal liver, but its expression is greatly diminished in adult liver. The full-length human ACAT2 mRNA encodes a protein, designated ACAT2a, with 522 amino acids. We have previously reported the organization of the human ACAT2 gene and the differentiation-dependent promoter activity in intestinal Caco-2 cells. In the current work, two human ACAT2 mRNA variants produced by alternative splicing are cloned and predicted to encode two novel ACAT2 isoforms, named ACAT2b and ACAT2c, with 502 and 379 amino acids, respectively. These mRNA variants differ from ACAT2a mRNA by lack of the exon 4 (ACAT2b mRNA) and exons 4-5 plus 8-9-10 (ACAT2c mRNA). Significantly, comparable amounts of the alternatively spliced ACAT2 mRNA variants were detected by RT-PCR, and Western blot analysis confirmed the presence of their corresponding proteins in human liver and intestinecells. Furthermore, phosphorylation and enzymatic activity analyses demonstrated that the novel isoenzymes ACAT2b and ACAT2c lacked the phosphorylatable site SLLD, and their enzymatic activities reduced to 25%-35% of that of ACAT2a. These evidences indicate that alternative splicing produces two human ACAT2 mRNA variants that encode the novel ACAT2 isoenzymes. Our findings might help to understand the regulation of the ACAT2 gene expression under certain physiological and pathological conditions.