Dual Agonist of Farnesoid X Receptor and Takeda G Protein-Coupled Receptor 5 Inhibits Hepatitis B Virus Infection In Vitro and In Vivo.

BACKGROUND AND AIMS: Chronic HBV infection is a major health problem worldwide. Currently, the first-line treatment for HBV is nucleos(t)ide analogs or interferons; however, efficient therapeutic approaches that enable cure are lacking. Therefore, anti-HBV agents with mechanisms distinct from those of current drugs are needed. Sodium taurocholate cotransporting polypeptide (NTCP) was previously identified as an HBV receptor that is inhibited by several compounds. Farnesoid X receptor (FXR) activation also inhibits NTCP function. APPROACH AND RESULTS: In this study, we investigated the inhibitory effect of bile acid (BA) derivatives-namely obeticholic acid (OCA), 6α-ethyl-24-nor-5ß-cholane-3α,7α,23-triol-23 sulfate sodium salt (INT-767; a dual agonist of FXR and Takeda G protein-coupled receptor [TGR5]), and 6α-ethyl-23(S)-methyl-cholic acid (INT-777; a TGR5 agonist)-3-(2,6-dichlorophenyl)-4-(3'-carboxy-2-chlorostilben-4-yl)oxymethyl-5-isopropylisoxazole (GW4064; a FXR agonist), cyclosporin A, and irbesartan. OCA and INT-777 suppressed HBV infection in HepG2-human NTCP-C4 cells. Interestingly, INT-767 showed potent inhibition by attaching to HBV particles rather than binding to NTCP. As an entry inhibitor, INT-767 was stronger than various natural BAs. Furthermore, in chimeric mice with humanized liver, INT-767 markedly delayed the initial rise of HBsAg, HBeAg, and HBV DNA and reduced covalently closed circular DNA. The strong inhibitory effect of INT-767 may be due to the cumulative effect of its ability to inhibit the entry of HBV and to stimulate FXR downstream signaling, which affects the postentry step. CONCLUSIONS: Our results suggest that BA derivatives, particularly INT-767, are prospective candidate anti-HBV agents. Clarifying the underlying mechanisms of BA derivatives would facilitate the development of anti-HBV agents.

Effect of Central Corticotropin-Releasing Factor on Hepatic Lipid Metabolism and Inflammation-Related Gene Expression in Rats.

Corticotropin-releasing factor (CRF) in the brain acts on physiological and pathophysiological modulation of the hepatobiliary system. Central CRF administration aggravates experimental acute liver injury by decreasing hepatic blood flow. Conversely, minimal evidence is available regarding the effect of centrally acting CRF on hepatic lipid metabolism and inflammation. We examined whether central CRF affects hepatic lipid metabolism and inflammation-related gene expression in rats. Male Long Evans rats were intracisternally injected with CRF (10 µg) or saline. Rats were sacrificed 2 h, 6 h, and 24 h after the CRF injection, the liver was isolated, and mRNA was extracted. Next, hepatic lipid metabolism and inflammation-related gene expression were examined. Hepatic SREBF1 (sterol regulatory element-binding transcription factor 1) mRNA levels were significantly increased 6 h and 24 h after intracisternal CRF administration when compared with those in the control group. Hepatic TNFα and IL1ß mRNA levels increased significantly 6 h after intracisternal CRF administration. Hepatic sympathectomy or guanethidine treatment, not hepatic branch vagotomy or atropine treatment, inhibited central CRF-induced increase in hepatic SREBF1, TNFα and IL1ß mRNA levels. These results indicated that central CRF affects hepatic de novo lipogenesis and inflammation-related gene expression through the sympathetic-noradrenergic nervous system in rats.

Effect of Adrenergic Agonists on High-Fat Diet-Induced Hepatic Steatosis in Mice.

The autonomic nervous system, consisting of sympathetic and parasympathetic branches, plays an important role in regulating metabolic homeostasis. The sympathetic nervous system (SNS) regulates hepatic lipid metabolism by regulating adrenergic receptor activation, resulting in the stimulation of hepatic very-low-density lipoprotein-triglyceride (TG) production in vivo. However, only a few studies on the relationship between SNS and hepatic steatosis have been reported. Here, we investigate the effect of adrenergic receptor agonists on hepatic steatosis in mice fed a high-fat diet (HFD). The α-adrenergic receptor agonist phenylephrine (10 mg/kg/d) or the ß-adrenergic receptor agonist isoproterenol (30 mg/kg/d) was coadministered with HFD to male mice. After five weeks, hepatic steatosis, TG levels, and hepatic fat metabolism-related biomarkers were examined. HFD treatment induced hepatic steatosis, and cotreatment with phenylephrine, but not isoproterenol, attenuated this effect. Phenylephrine administration upregulated the mRNA levels of hepatic peroxisome proliferator-activated receptor alpha and its target genes (such as carnitine palmitoyltransferase 1) and increased hepatic ß-hydroxybutyrate levels. Additionally, phenylephrine treatment increased the expression of the autophagosomal marker LC3-II but decreased that of p62, which is selectively degraded during autophagy. These results indicate that phenylephrine inhibits hepatic steatosis through stimulation of ß-oxidation and autophagy in the liver.

Characteristics of bile acid composition in high fat diet-induced nonalcoholic fatty liver disease in obese diabetic rats.

Bile acid has attracted attention as a signal transmission molecule in energy metabolism. Although a high-fat diet (HFD) or obesity is known to increase hepatic fat content and alter bile acid composition, the changes in bile acid composition due to HFD or obesity remain to be elucidated. We sought to examine the bile acid composition in high fat diet-induced non-alcoholic fatty liver disease (NAFLD) in obese diabetic rats. Eight-week-old male spontaneously diabetic Torii fatty (SDTF) rats or control rats were fed an HFD. Twelve weeks post the commencement of HFD, serum and hepatic bile acid compositions and serum GLP-1 levels, which is stimulated by the secondary bile acid deoxycholic acid (DCA), were measured. The correlation between the bile acid composition and serum GLP-1 levels was also examined. While serum and hepatic levels of cholic acid (CA), a primary bile acid, tended to decrease in HFD-fed control rats, they were significantly decreased in HFD-fed SDTF rats. Hepatic CYP8B1, which plays a role in CA synthesis, the mRNA levels were significantly decreased in HFD-fed control and SDTF rats. In contrast, while serum and hepatic DCA levels were not changed in HFD-fed control rats, they were decreased in HFD-fed SDTF rats. Hepatic DCA/CA did not change in HFD-fed SDTF rats, but significantly increased in HFD-fed control rats. While serum GLP-1 levels were not changed in SDTF rats, they were significantly increased in HFD-fed control rats. Hepatic DCA/CA tended to correlate with serum GLP-1 levels, which tended to negatively correlate with the hepatic triglyceride content in SDTF rats. These results indicate that relatively increased DCA might contribute to an increase in serum GLP-1 levels, which inhibits hepatic steatosis in NAFLD.

Conophylline inhibits high fat diet-induced non-alcoholic fatty liver disease in mice.

Conophylline (CnP), a vinca alkaloid extracted from the leaves of the tropical plant Tabernaemontana divaricate, attenuates hepatic fibrosis in mice. We have previously shown that CnP inhibits non-alcoholic steatohepatitis (NASH) using a methionine-choline-deficient (MCD) diet-fed mouse model. However, little is known about the CnP mediated inhibition of hepatic steatosis in high-fat diet-induced non-alcoholic fatty liver disease (NAFLD) mouse models. CnP (0.5 and 1 µg/g/body weight) was co-administered along with a high-fat diet to male BALB/c mice. After nine weeks of administering the high-fat diet, hepatic steatosis, triglyceride, and hepatic fat metabolism-related markers were examined. Administration of a high-fat diet for 9 weeks was found to induce hepatic steatosis. CnP dose-dependently attenuated the high-fat diet-induced hepatic steatosis. The diet also attenuated hepatic peroxisome proliferator-activated receptor alpha (PPARA) mRNA levels. PPARA is known to be involved in ß-oxidation. CnP upregulated the mRNA levels of hepatic PPARA and its target genes, such as carnitine palmitoyl transferase 1 (CPT1) and CPT2, in a dose-dependent manner in the liver. Furthermore, levels of hepatic ß-hydroxybutyrate, which is a type of ketone body, were increased by CnP in a dose-dependent manner. Finally, CnP increased the expression of the autophagosomal marker LC3-II and decreased the expression of p62, which are known to be selectively degraded during autophagy. These results indicate that CnP inhibits hepatic steatosis through the stimulation of ß-oxidation and autophagy in the liver. Therefore, CnP might prove to be a suitable therapeutic target for NAFLD.

Intrahepatic gene expression profiles in chronic hepatitis B and autoimmune liver disease.

BACKGROUND: DNA microarray technology has enabled genomewide analysis of gene transcript levels, yielding insight into the molecular nature of liver disease. METHODS: We compared gene expression of liver biopsy specimens in 16 patients with different stages of chronic hepatitis B, five with autoimmune hepatitis (AIH), five with primary biliary cirrhosis (PBC), and six with druginduced hepatitis. RESULTS: Of 21 073 genes, 424 showed different expression in a particular disease group on analysis of variance. Genes associated with extracellular matrix, cell growth, and DNA repair were noted in the advanced fibrotic stage of chronic hepatitis B (B-3), while gene expression regarding complement activation and the innate immune response decreased. When we compared gene expression at the relatively early stage in each disease group with pathway analysis, pathways relating to chemotaxis and cell homeostasis were selected in chronic hepatitis B. In PBC, gene expression relating to structural constituents and contractions of muscle such as actin and myosin were enhanced, in contrast to the downregulation of genes relating to protein binding in AIH. A hierarchical clustering analysis of hepatitis B genes defined five clusters. Generally, the transcripts upregulated according to disease progression were associated with signaling pathway/transcription, including tumor-associated calcium signal transducer 1 and chemokine ligand 19, and with cell communication, such as collagen. In two groups, all transcripts were downregulated; transcripts related to chemokine ligands and metallothionein were further depressed in B-3. CONCLUSIONS: Analysis of gene expression in liver may be useful for understanding features of distinct liver diseases and for guiding disease progression, particularly in chronic hepatitis B.

Changes in intrahepatic gene expression profiles from chronic hepatitis to hepatocellular carcinoma in patients with hepatitis C virus infection.

AIM: DNA microarray technology has enabled genome-wide analysis of gene transcript levels, which has yielded insight into the molecular nature of hepatitis C virus infection. However, little insight into the molecular nature of the early to advanced stages of chronic liver disease has as yet been obtained. METHODS: We compared the gene expression profiles of liver biopsy specimens from 14 patients at different stages of chronic hepatitis C. We also evaluated the liver tissue of hepatocellular carcinoma and its surrounding region obtained surgically in seven patients with hepatitis C virus infection. RESULTS: Of 21 073 genes, 582 genes showed significant changes in expression levels across the disease group. Twenty-eight samples from six disease groups clustered according to the histological classification except for 4 samples. A heat map produced by hierarchical clustering revealed nine clusters where gene expression profiles were changed in abundance. Among 44 genes which changed twofold or more in transcript abundance, transcripts from chronic hepatitis tended to be upregulated, and gradually downregulated according to disease progression toward hepatocellular carcinoma in five of nine clusters. In chronic hepatitis, transcripts relating to metabolism and immune response were upregulated, while in hepatocellular carcinoma, transcripts associated with cell cycle, growth, proliferation, apoptosis and signaling pathway were upregulated. CONCLUSION: Disease progression in hepatitis C virus-infected patients appeared to be associated with changes in gene expression profiles in the liver consistent with plausible functional categories, although we should confirm these findings using larger samples.

Deficiency of forkhead box P3 and cytotoxic T-lymphocyte-associated antigen-4 gene expressions and impaired suppressor function of CD4(+)CD25(+) T cells in patients with autoimmune hepatitis.

AIM: Recently, forkhead box P3 (Foxp3), cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4), glucocorticoid-induced tumor necrosis factor receptor family-related gene (GITR), and CD28 were identified as the key molecules that control the development and activation of CD4+CD25+ regulatory T cells (T-reg). We investigated the expression pattern of these molecules on T-reg, and investigated the ability of T-reg to produce cytokines in patients with autoimmune hepatitis (AIH). METHODS: Fifteen patients with AIH and nine healthy patients were included. To determine the frequency of T-reg, a two-color flow cytometry analysis was performed. T-reg were isolated using immunomagnetic beads, and the mRNA levels of Foxp3, CTLA-4, GITR, and CD28 were quantified by real-time polymerase chain reaction (PCR). The ability of T-reg to produce interferon-gamma, interleukin (IL)-10, transforming growth factor-beta, and tumor necrosis factor-alpha after stimulation by OKT3 was evaluated by measuring the levels of mRNA in T-reg by real-time PCR. RESULTS: The frequency of T-reg was increased in AIH. The mRNA levels of Foxp3 and CTLA-4 were significantly lower in AIH. The ability of T-reg to produce IL-10 was impaired in AIH. CONCLUSION: We speculate that the inferiority of the Foxp3 and CTLA-4 gene expressions on T-reg results in the impaired suppressor function of T-reg, and eventually in the breakdown of self-tolerance.

Conophylline inhibits non-alcoholic steatohepatitis in mice.

Conophylline (CnP), a vinca alkaloid extracted from the leaves of the tropical plant Ervatamia microphylla, attenuates hepatic fibrosis in mice. However, little is known about whether CnP inhibits steatosis, inflammation, and fibrosis in non-alcoholic steatohepatitis (NASH) in mice. A methionine-choline-deficient (MCD) diet was administered to male db/db mice as a NASH model, and CnP (1 µg/kg/d) was co-administered. Eight weeks after the commencement of the MCD diet, hepatic steatosis, inflammation, and fibrosis, and hepatic fat metabolism-, inflammation-, and fibrosis-related markers were examined. Feeding on an MCD for 8 weeks induced hepatic steatosis, inflammation, and fibrosis. CnP significantly attenuated the MCD-induced increases in hepatic steatosis, as well as hepatic inflammation and fibrosis. The MCD diet increased hepatic transforming growth factor-ß (TGF-ß) mRNA levels, which are correlated with hepatic steatosis, inflammation, and fibrosis. The diet also attenuated acyl-coenzyme A oxidase 1 (ACOX1) and carnitine palmitoyltransferase 1 (CPT1) mRNA levels, which are involved in ß-oxidation. The putative mechanism of the CnP effect involves reduced hepatic TGF-ß mRNA levels, and increased mRNA levels of hepatic peroxisome proliferator-activated receptor (PPAR) α and its target genes ACOX1 and CPT1. The results of this study indicate that CnP inhibits steatohepatitis, possibly through the inhibition of hepatic TGF-ß mRNA levels, and induces an increase in PPARα mRNA levels, resulting in the attenuation of hepatic steatosis, inflammation, and fibrosis in mice. CnP might accordingly be a suitable therapeutic option for NASH.

Influence of nicotine on choline-deficient, L-amino acid-defined diet-induced non-alcoholic steatohepatitis in rats.

Nicotine, a major compound in cigarette smoke, decreases food intake and body weight gain in mammals; however, the influence of nicotine on the progression of non-alcoholic steatohepatitis (NASH) remains controversial. This study aimed to investigate the effect of nicotine on NASH in rat models. Male Wistar rats were fed choline-deficient, l-amino acid-defined (CDAA) diet and treated with nicotine or saline. Food intake, body weight gain, presence of hepatic steatosis, inflammation, and fibrosis were assessed 6 weeks after the rats were fed CDAA diet. Hepatic branch vagotomy was performed to elucidate the mechanism through which nicotine affected steatohepatitis. CDAA diet induced hepatic steatosis, inflammation, and fibrosis, as well as increased the expression of inflammation-related genes. Conversely, nicotine significantly attenuated food intake, body weight gain, and inhibited the CDAA-diet-induced hepatic steatosis, inflammation, and fibrosis, together with increased expression of inflammation-related genes. Hepatic branch vagotomy by itself decreased food intake, body weight gain, and attenuated the CDAA-diet-induced hepatic steatosis, but not inflammation. However, nicotine did not change the food intake, body weight gain, and CDAA diet-induced hepatic steatosis and inflammation in vagotomized rats. These results suggest that nicotine attenuates the CDAA-diet-induced hepatic steatosis and inflammation through the hepatic branch of the vagus nerve in rats.

Glucagon-like peptide-1 analogue prevents nonalcoholic steatohepatitis in non-obese mice.

AIM: To investigate whether a glucagon-like peptide-1 (GLP-1) analogue inhibits nonalcoholic steatohepatitis (NASH), which is being increasingly recognized in Asia, in non-obese mice. METHODS: A methionine-choline-deficient diet (MCD) along with exendin-4 (20 µg/kg per day, ip), a GLP-1 analogue, or saline was administered to male db/db mice (non-obese NASH model). Four or eight weeks after commencement of the diet, the mice were sacrificed and their livers were excised. The excised livers were examined by histochemistry for evidence of hepatic steatosis and inflammation. Hepatic triglyceride (TG) and free fatty acid (FFA) content was measured, and the expression of hepatic fat metabolism- and inflammation-related genes was evaluated. Oxidative stress-related parameters and macrophage recruitment were also examined using immunohistochemistry. RESULTS: Four weeks of MCD feeding induced hepatic steatosis and inflammation and increased the hepatic TG and FFA content. The expression of fatty acid transport protein 4 (FATP4), a hepatic FFA influx-related gene; macrophage recruitment; and the level of malondialdehyde (MDA), an oxidative stress marker, were significantly augmented by a 4-wk MCD. The levels of hepatic sterol regulatory element-binding protein-1c (SREBP-1c) mRNA (lipogenesis-related gene) and acyl-coenzyme A oxidase 1 (ACOX1) mRNA (ß-oxidation-related gene) had decreased at 4 wk and further decreased at 8 wk. However, the level of microsomal triglyceride transfer protein mRNA (a lipid excretion-related gene) remained unchanged. The administration of exendin-4 significantly attenuated the MCD-induced increase in hepatic steatosis, hepatic TG and FFA content, and FATP4 expression as well as the MCD-induced augmentation of hepatic inflammation, macrophage recruitment, and MDA levels. Additionally, it further decreased the hepatic SREBP-1c level and alleviated the MCD-mediated inhibition of the ACOX1 mRNA level. CONCLUSION: These results suggest that GLP-1 inhibits hepatic steatosis and inflammation through the inhibition of hepatic FFA influx and oxidative stress in a non-obese NASH model.

Changes in natural killer T cells subsets during therapy in type C hepatitis and hepatocellular carcinoma.

Natural killer T (NKT) cells share features of both classical T cells and NK cells. NKT are heterogenous populations, and recognize glycolipids associated with CD1d molecule. We investigated Th1/Th2 cytokine production as well as frequency and phenotype of circulating NKT cells in 14 healthy subjects and in patients during therapy with type C chronic hepatitis (CH; 14 cases) and hepatocellular carcinoma (HCC; 13 cases). Peripheral blood mononuclear cells (PBMC) were obtained before and 2 weeks later interferon (IFN)/ribavirin and radiofrequency ablation therapy for CH and HCC, respectively. PBMC were cultured for 10 days with alpha-galactosylceramide (alpha-GalCer) and interleukin-2 (IL-2). Frequencies and IFN-gamma/IL-4 production of NKT cells were analyzed using flow cytometry. Intrahepatic lymphocytes were analyzed in seven CH patients with liver biopsy specimen. Prevalence of circulating Valpha24+CD3+ T cells was 0.9+/-0.9% of PBMC for controls and increased to 8.5+/-8.9% (p<0.001) in response to alpha-GalCel. Similar frequency and expansion were noted in CH. The frequency increased during therapy. The prevalence in HCC tended to be high compared to controls and response to alpha-GalCel was well. Although frequency of Valpha24+Vbeta11+CD3+ T cells was low in all groups, the distribution pattern was similar to Valpha24+Vbeta11-CD3+ T cells. Prevalence of CD56+CD3+ T cells was low independent of therapy in CH (2-3%) compared to 5.0+/-4.0% of controls, although response to alpha-GalCel was not impaired. IFN-gamma production of Valpha24+CD3+ T cells did not differ among groups, but became greater after treatment in contrast to lowered IL-4 production. Frequencies of NKT populations were higher in liver than in peripheral blood. Our study suggests that CD1d-reactive T cells have distinct distribution in different populations and therapy for patients alters cytokine response of NKT cells.

Angiotensin II type 1 receptor antagonist prevents hepatic carcinoma in rats with nonalcoholic steatohepatitis.

BACKGROUND: Angiotensin II type 1 receptor blockers (ARBs) have been reported to attenuate hepatic fibrosis in non-alcoholic steatohepatitis (NASH). However, it is uncertain whether ARBs prevent hepatocarcinogenesis in NASH even after hepatic fibrosis has developed. METHODS: Male Wistar rats were fed with a choline-deficient, L-amino acid-defined (CDAA) diet for 24 weeks, and then fed with the CDAA diet with telmisartan (2 mg/kg/day), a novel ARB, or vehicle for another 24 weeks. The liver histology and the expression of genes and proteins related to angiogenesis were investigated. RESULTS: The 24-week CDAA diet induced liver cirrhosis. The 48-week CDAA diet exacerbated liver cirrhosis, and developed hepatocellular carcinoma (HCC) in 54.6 % of the rats concurrently with increases of hypoxia-inducible factor-1α (HIF-1α) protein and vascular endothelial growth factor (VEGF) mRNA, which are potent angiogenic factors in the liver. Telmisartan inhibited hepatic fibrosis and preneoplastic lesions and prevented the development of HCC along with inducing decreases in HIF-1α protein and VEGF mRNA. CONCLUSIONS: These data indicated that telmisartan may prevent hepatocarcinogenesis through the inhibition of hepatic angiogenesis even after liver cirrhosis has been established.

Expression of Toll-like receptors in chronic hepatitis C virus infection.

BACKGROUND: Toll-like receptors (TLRs) are involved in innate immunity. Certain viruses interact with TLRs and mediate antiviral effects as well as immune responses. The aim of this study was to investigate the effect of TLRs on pathogenesis in hepatitis C virus (HCV)-infected patients. METHODS: Peripheral blood mononuclear cells (PBMC) and CD14+ (monocytes) or CD14- cells from 25 patients with chronic liver disease and 15 healthy subjects were studied for expression of TLRs 2-9 and cytokines of extracted RNA using real-time PCR. Then TLR expression was examined in HepG2 cells transfected with entire or parts (core-NS3, NS3-NS5B) of the HCV open reading frame. TLR expression was calculated as the relative mRNA levels. RESULTS: Expression of TLRs 4, 7 and 8 in CD14+ cells of PBMC was increased in patients. Levels of tumor necrosis factor (TNF)-alpha, interleukin (IL)-6 and IL-12 p35 for PBMC were also increased in patients. When PBMC were incubated with HCV core protein, enhancement of TLR2 expression and suppression of TLR4 and TLR7 were noted in patients. Similar alteration of TLRs expression was observed in controls. Among HepG2 transfectants, only TLR3 expression was changed; it was suppressed in entire gene transfectant and enhanced in core-NS3 transfectant. Expression of some proteins related to the TLR signaling pathway was suppressed in the entire gene transfectant. CONCLUSIONS: The results suggest a correlation between expression levels of TLRs and cytokines, and chronic HCV infection. TLR3 recognizes double-stranded RNA and induces type 1 interferon synthesis. Collectively, suppressed expression of TLR3 in cells transfected with entire HCV may be responsible for continuous HCV infection, although a part of the HCV gene enhances its expression.