Induction of cell cycle arrest by GL331 via triggering an ATM-dependent DNA damage response in HepG2 cells.

GL331, a topoisomerase II inhibitor, has been found to trigger DNA damage response (DDR) to induce cell cycle arrest. However, the underlying mechanism has not yet been fully understood. This study investigated the molecular mechanism involved in the GL331-induced cell cycle arrest via DDR in human hepatocellular carcinoma HepG2 cells. As a result, GL331 could induce S arrest and up-regulate the phosphorylation of the histone H2AX variant (γ-H2AX). Ataxia telangiectasia mutated protein kinase (ATM) was activated by GL331 through its autophosphorylation at Ser1981, which led to the activation of DNA damage signaling pathways including p53/p21 and Chk2/Cdc25A cascades. The DNA damage cascades triggered by GL331 finally induced the inactivation of cyclin A/Cdk2 complexes to some extent. These phenomena could be reversed by ATM siRNA, followed by a partial disruption of S arrest. The present results suggested that the S arrest induced by GL331 via DDR was in an ATM-dependent manner to some degree.

Partial synthesis and biological evaluation of bisbenzylisoquinoline alkaloids derivatives: potential modulators of multidrug resistance in cancer.

A series of new bisbenzylisoquinoline alkaloids was partially synthesized from tetrandrine and fangchinoline and evaluated for their ability to reverse P-glycoprotein-mediated multidrug resistance (MDR) in cancer cells. All the test compounds increased the intracellular accumulation rate of rhodamine 123 in MDR cells (Bel7402 and HCT8), and most exhibited more potent MDR-reversing activity relative to the reference compound verapamil. Compounds 8, 10, 13, and 14 enhanced intracellular accumulation of doxorubicin in Bel7402 and HCT8 cells.

[Advances in the study of p53 in response to DNA damage].

p53 (encoded by TP53) is undoubtedly one of the most extensively studied genes and proteins. It is a highly potent transcription factor which, under normal circumstances, is maintained at low level. Both genotoxic and non-genotoxic stresses can induce p53 stabilized leading to changes in the expression of p53-responsive genes. The biological outcome inducing this pathway can be either growth arrest and apoptosis or senescence to maintain the integrity of the genome or to delete the damaged cells. The biochemical activity of p53 itself and the cellular environment govern the choice between these outcomes in a cell type- and stress-specific manner. So, p53 is a pivotal tumour suppressor and a mainstay of our body's natural anticancer defence. This review could provide some useful information for further study on the mechanisms of tumorigenesis and its progression, and also could contribute to the discovery of antitumor agents.

The novel squamosamide derivative FLZ enhances BDNF/TrkB/CREB signaling and inhibits neuronal apoptosis in APP/PS1 mice.

AIM: The aim of this study was to study the effects of compound FLZ, a novel cyclic derivative of squamosamide from Annona glabra, on brain-derived neurotrophic factor (BDNF)/tropomyosin receptor kinase B (TrkB)/cAMP response element-binding protein (CREB) signaling and neuronal apoptosis in the hippocampus of the amyloid precursor protein (APP)/presenilin-1 (PS1) double transgenic mice. METHODS: APP/PS1 mice at the age of 5 months and age-matched wild-type mice (WT) were intragastrically administered FLZ (150 mg/kg) or vehicle [0.05% carboxymethyl cellulose sodium (CMC-Na)] daily for 20 weeks. The levels of BDNF in the hippocampus of WT and APP/PS1 mice were then measured by immunohistochemistry and Western blot analysis. Neuronal apoptosis in mouse hippocampus was detected by Nissl staining. Expression of NGF, NT3, pTrkB (Tyr515)/TrkB, pAkt (Ser473)/Akt, pERK/ERK, pCREB (Ser133)/CREB, Bcl-2/Bax, and active caspase-3 fragment/caspase-3 in the hippocampus of WT and APP/PS1 mice was detected by Western blot analysis. RESULTS: Compared with vehicle-treated APP/PS1 mice, FLZ (150 mg/kg) significantly increased BDNF and NT3 expression in the hippocampus of APP/PS1 mice. In addition, FLZ promoted BDNF high-affinity receptor TrkB phosphorylation and activated its downstream ERK, thus increasing phosphorylation of CREB at Ser133 in the hippocampus of APP/PS1 mice. Moreover, FLZ showed neuroprotective effects on neuronal apoptosis by increasing the Bcl-2/Bax ratio and decreasing the active caspase-3 fragment/caspase-3 ratio in the hippocampus of APP/PS1 mice. CONCLUSION: FLZ exerted neuroprotection at least partly through enhancing the BDNF/TrkB/CREB pathway and inhibiting neuronal apoptosis in APP/PS1 mice, which suggests that FLZ can be explored as a potential therapeutic agent in long-term Alzheimer's disease therapy.

Bicyclol protects HepG2 cells against D-galactosamine-induced apoptosis through inducing heat shock protein 27 and mitochondria associated pathway.

AIM: To study the inducing effect of bicyclol on heat shock protein 27 (HSP27) and its role on anti-apoptosis in HepG2 cells intoxicated with D-galactosamine (D-GaIN). METHODS: HepG2 cells were treated with various concentrations of bicyclol and then subjected to D-GaIN intoxication. Apoptosis was assayed by hoechst 33258 staining and flow cytometry analysis. HSP27, cytochrome c, apoptosis inducing factor (AIF) and c-Jun N-terminal kinase (JNK) were assayed by Western blot. Heat shock factor 1 (HSF1) was determined by electrophoretic mobility shift assay and the interactions of HSP27 with cytochrome c and AIF were detected by co-immunoprecipitation. RESULTS: The results showed that bicyclol induced HSP27 protein and mRNA expression in HepG2 cells in both time- and dose-dependent manners (the maximal response: 1.23 fold increase at 100 micromol/L). Bicyclol treatment stimulated HSF1 activation and increased the HSF1-HSE binding activity (the maximal response: 2.1 fold increase at 100 micromol/L). This inducing effect of bicyclol on HSP27 and HSF1 was markedly blocked by quercetin. Pretreatment of the cells with bicyclol markedly attenuated D-GaIN-induced apoptosis and the release of cytochrome c and AIF from mitochondria. The induced HSP27 by bicyclol suppressed the activity of caspase-3 and the phosphorylation of JNK caused by D-GaIN in HepG2 cells. All the above effect of bicyclol against D-GaIN-induced hepatocytes apoptosis were significantly reversed by quercetin. CONCLUSION: HSP27 is involved in the anti-hepatocytes apoptosis of bicyclol, and this effect of bicyclol-induced HSP27 is mainly through inhibition of mitochondria and JNK apoptotic pathways.

Involvement of HSP70 in the protection of bicyclol on apoptosis of HepG2 cells intoxicated by d-galactosamine.

Heat shock proteins (HSPs), the best known endogenous factors, play important roles in the cytoprotection and repair of cells and tissues against the harmful effects of stress and insults. In this study, RNAi technology was used to identify whether HSP70 was involved in the protection of bicyclol against d-galactosamine (d-GaIN)-induced apoptosis in HepG2 cells. As a result, bicyclol induced HSP70 in a time- and dose-dependent manner in HepG2 cells. Bicyclol markedly alleviated apoptosis and caspase-3 activity in HepG2 cells intoxicated by d-GaIN. The degradation of inhibitory kappa B, phosphorylation of inhibitory kappa B kinase, nuclear factor kappa B (NF-kappaB) nuclear translocation, and DNA-binding activity were all inhibited by bicyclol in HepG2 cells intoxicated by d-GaIN. In addition, bicyclol decreased the nitric oxide production and inducible nitric oxide synthase (iNOS) expression. The inhibitory effects of bicyclol on all the above biomarkers were attenuated when the HSP70 gene was silenced accordingly. Our data also showed that MG132 (inhibitor of NF-kappaB) and NG-nitro-l-arginine methyl ester (inhibitor of iNOS) inhibited hepatocyte apoptosis induced by d-GaIN. These in vitro results suggested that HSP70 partially contributed to the hepatoprotection of bicyclol through suppressing the NF-kappaB-iNOS pathway.

Scutellarin protects against lipopolysaccharide-induced acute lung injury via inhibition of NF-kappaB activation in mice.

This paper investigates the effect of natural scutellarin on acute lung injury (ALI) induced by Escherichia coli endotoxin lipopolysaccharide (LPS) in mice and its mechanism of action. Mouse ALI was induced by the injection of LPS (15 mg/kg) via the tail vein, and mice were intraperitoneally injected with 50 and 25 mg/kg of scutellarin before the LPS injection. The lung index, serum NO2(-)/NO3(-), and tumor necrosis factor-alpha (TNF-alpha) levels were determined using kits. The lung lesions were examined by light microscope. The mRNA levels of TNF-alpha, inducible nitric oxide synthase (iNOS), and FasL in pulmonary tissues were detected by RT-PCR. c-Fos, c-Jun, IkappaB, and iNOS proteins were detected by the western blotting method. Pretreatment with 25 and 50 mg/kg of scutellarin significantly reduced lung injury induced by LPS, which expressed in the decrease in lung morphological lesions, serum NO2(-)/NO3(-), TNF-alpha levels, lactate dehydrogenase release, and total protein in the lavage fluid of bronchoalveolar of the lung. The mRNA level of TNF-alpha, iNOS, the protein content of c-Fos, iNOS, and the activation of NF-kappaB in pulmonary tissues were all inhibited, while the lung glutathione level increased. In conclusion, scutellarin has protective action against LPS-induced lung damage in mice, and its underlying mechanism might be the inhibition of IkappaB alpha degradation and the expression of TNF-alpha mRNA.

Synthesis and MDR inhibitory activity evaluation of derivatives of schizandrin A.

Eighteen schizandrin A derivatives, possessing an acyl group at 7-OH and/or halogen(s) at C-4 and C-11, were designed and synthesized for evaluation of their in vitro ability to inhibit multidrug resistance (MDR). They exhibit weak ability to restore the intracellular Rhodamine 123 in human hepatocarcinoma MDR cell lines Bel7402 and HCT8 relative to the reference drug verapamil.

[Neurodegenerative conformational disease and heat shock proteins].

Many major neurodegenerative diseases are associated with proteins misfolding and aggregation, which are also called "neurodegenerative conformational disease". The interaction of gene mutation and environmental factors are probably primary events resulting in oligomer and aggregate formations of proteins. Moreover, the dysfunctions of protein control systems, i.e. the ubiquitin-proteasome system and autophagy-lysosomal system, also contribute to the neurodegenerative process. The present review mainly summarizes protein misfolding and aggregation in the development of neurodegenerative conformational disease and the underling mechanisms, as well as upregulation of heatshock proteins as a promising treatment method for this kind of disease.

Induction of overexpression of the 27- and 70-kDa heat shock proteins by bicyclol attenuates concanavalin A-Induced liver injury through suppression of nuclear factor-kappaB in mice.

Heat shock proteins (HSPs) are molecular chaperones critical for cell survival under adverse environmental conditions and for normal cellular homeostasis. Bicyclol, a novel antihepatitis drug, has been shown to protect against liver injury in animals. However, it is unclear how bicyclol protects against liver injury. We recently found that bicyclol is an inducer of HSPs. We wondered whether bicyclol regulated the expression of HSPs to produce a liver protection in vivo. Thus, this study was designed to address these questions using a mouse model with concanavalin A (ConA)-induced liver injury. Oral administration of bicyclol markedly alleviated ConA-caused liver injury in mice as indicated by the reduction of serum aminotransferases, liver necrosis, and the release of cytochrome c and apoptosis-inducing factor from mitochondria and hepatic DNA fragmentation. Correlated with this, bicyclol induced the increase of mRNA and protein levels of hepatic 27- and 70-kDa HSPs (HSP27 and HSP70) in the mice. Correspondingly, the elevated HSP27 and HSP70 suppressed inhibitor kappaB degradation and nuclear factor kappaB (NF-kappaB) activation that were caused by ConA. The protective effects of bicyclol on ConA-induced mouse liver injury were markedly attenuated by quercetin, an inhibitor of HSPs synthesis. Our results suggest that the antihepatitis drug bicyclol may protect against liver injury by inducing the expression of hepatic HSP27 and HSP70 and consequently inhibit the transcription factor NF-kappaB-mediated apoptosis and necrosis in liver tissue.

Protective effects of compound FLZ, a novel synthetic analogue of squamosamide, on beta-amyloid-induced rat brain mitochondrial dysfunction in vitro.

AIM: The aim of the present study was to assess the effects of N-[2-(4-hydroxyphenyl)ethyl]-2-(2,5-dimethoxyphenyl)-3-(3-methoxy-4-hydroxyphenyl) acrylamide (compound FLZ), a novel synthetic analogue of squamosamide, on the dysfunction of rat brain mitochondria induced by Abeta(25-35) in vitro. METHODS: Isolated rat brain mitochondria were incubated with aged Abeta(25-35) for 30 min in the presence and absence of FLZ (1-100 micromol/L). The activities of key mitochondrial enzymes, the production of hydrogen peroxide (H(2)O(2)) and superoxide anion (O2*-), and the levels of glutathione (GSH) in mitochondria were examined. Mitochondrial swelling and the release of cytochrome c from mitochondria were assessed by biochemical and Western blot methods, respectively. RESULTS: Incubation of mitochondria with aged Abeta(25-35) inhibited the activities of alpha-ketoglutarate dehydrogenase (alpha-KGDH), pyruvate dehydrogenase (PDH) and respiratory chain complex IV. It also resulted in increased H(2)O(2) and (O2*-) production, and decreased the GSH level in mitochondria. Furthermore, it induced mitochondrial swelling and cytochrome c release from the mitochondria. The addition of FLZ (100 micromol/L) prior to treatment with Abeta(25-35) significantly prevented these toxic effects of Abeta(25-35) on the mitochondria. CONCLUSION: FLZ has a protective effect against Abeta(25-35)-induced mitochondrial dysfunction in vitro.

Compound FLZ inhibits lipopolysaccharide-induced inflammatory effects via down-regulation of the TAK-IKK and TAK-JNK/p38MAPK pathways in RAW264.7 macrophages.

AIM: The aim of this study was to investigate the effect of the squamosamide derivative FLZ (N-2-(4-hydroxy-phenyl)-ethyl-2-(2,5-dimethoxy-phenyl)-3-(3-methoxy-4-hydroxy-phenyl)-acrylamide) on lipopolysaccharide (LPS)-induced inflammatory mediator production and the underlying mechanism in RAW264.7 macrophages. METHODS: RAW264.7 cells were preincubated with non-toxic concentrations of compound FLZ (1, 5, and 10 micromol/L) for 30 min and then stimulated with 10 microg/L LPS. The production of nitric oxide (NO), the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2), and the activation of nuclear factor kappa-B (NF-kappaB) and mitogen-activated protein kinase (MAPK) pathways were examined. RESULTS: FLZ significantly inhibited the LPS-induced production of NO, as well as the expression of iNOS and COX-2 at both the RNA and the protein levels in RAW264.7 cells. The LPS-induced increase in the DNA binding activity of NF-kappaB and activator protein 1 (AP-1), the nuclear translocation of NF-kappaB p65, the degradation of the inhibitory kappaBalpha protein (IkappaBalpha) and the phosphorylation of IkappaBalpha, IkappaB kinase (IKK) alpha/beta, c-Jun NH(2)-terminal kinase (JNK) and p38 MAPKs were all suppressed by FLZ. However, the phosphorylation of extracellular signal-regulated kinase (ERK) was not affected. Further study revealed that FLZ inhibited the phosphorylation of transforming growth factor-beta (TGF-beta)-activated kinase 1 (TAK1), which is an upstream signaling molecule required for IKKalpha/beta, JNK and p38 activation. CONCLUSION: FLZ inhibited the LPS-induced production of inflammatory mediators at least partly through the downregulation of the TAK-IKK and TAK-JNK/p38MAPK pathways.

Bicyclol: a novel drug for treating chronic viral hepatitis B and C.

Chronic viral hepatitis B and C are diseases worldwide. At present, the number of effective and safe drugs for treatment of HBV and HCV is still limited. In order to develop novel anti-viral hepatitis drug, a number of analogues of the active component schizandrin C from Fructus Schiznadrae, a Chinese herb used in the therapy of viral hepatitis, were synthesized. Bicyclol, one of the analogues, was demonstrated to have actions of anti-hepatitis virus replication in duck hepatitis model and 2.2.15 cell line, anti-experimental liver injury induced by hepatotoxins such as CCl4, acetaminophen and ConA, and anti-liver fibrosis in rats and mice. The active mechanism of bicyclol might be anti-apoptosis of hepatocytes through multiple signaling pathways mainly inducing the expressions of hepatic heat shock proteins (HSP27 and HSP70), molecular chaperons. Clinical trial was performed by double blind, randomized and positive control or placebo method in multi-medical centers in China. Patients received bicyclol 25mg thrice daily for six months, then stopped treatment and followed up for 3 months. Oral administration of bicyclol normalized the elevated serum transaminases (ALT, AST) by approximately 50% in chronic viral hepatitis B and C, and also showed certain level of inhibiting HBV and HCV replication. No noticeable adverse reaction has been observed. In combination therapy of bicyclol with interferon alpha, lamivudine and adefovir dipivoxil in HBV or HCV, bicyclol may potentiate the anti-viral efficacy and reduce YMDD mutant and side effects. In 2004 China FDA issued license to manufacture bicyclol. Since then bicyclol has been widely used to treat chronic HBV and HCV in China.

Inhibitory effect of anti-hepatitis drug bicyclol on invasion of human hepatocellular carcinoma MHCC97-H cells with high metastasis potential and its relative mechanisms.

To assess the anti-invasion effect of bicyclol (1) and its mechanism in human hepatocellular carcinoma (HCC) MHCC97-H cells with high metastatic potential. MTT assay was performed to evaluate the cytotoxicity of 1 to MHCC97-H cells and its inhibitory effect on the adhesion of these cells to laminin (LN) and fibronectin (FN). The anti-invasion effect of 1 was detected in an experiment using a transwell chamber. Transcription of vascular endothelial growth factor (VEGF), nm23-H1, and urokinase-type plasminogen activator receptor (uPAR) mRNAs was determined by an RT-PCR assay. The secretion and expression of alpha-fetoprotein (AFP) were analyzed by ELISA and flow cytometry, respectively. At concentrations of 10, 50, and 100 mumol/l, 1 obviously inhibited the adhesion of the MHCC97-H cells to LN and FN. The rates of inhibition of MHCC97-H cell invasion by 50 and 100 mumol/l for 1 were 37.3 and 50.2%, respectively. Drug 1 also decreased the expressions of VEGF, nm23-H1, and uPAR mRNA and the secretion of AFP in MHCC97-H cells. At low cytotoxic concentrations, the anti-hepatitis drug 1 demonstrated a significant anti-invasive effect in human HCC MHCC97-H cells with high metastatic potential. The inhibition of the expressions of VEGF, nm23-H1, and uPAR should contribute, at least in part, to the anti-invasion property of 1.

[The role of vitagene in aging and Alzheimer's disease and relevant advances of pharmacological study].

Free radical hypothesis of aging emphasized that the age-related accumulation of free radicals results in cell injury. Alzheimer's disease (AD) is the most common form of neurodegenerative disease characterized by impaired cognition and memory of the elderly. Aging is a key risk factor in AD. Substantial evidence suggests that imbalance between free radical formation and clearance promotes AD pathogenesis. The brain overcomes oxidative stress by inducing expression of a set of genes called vitagenes. The protein products of vitagenes include heat shock proteins, heme oxygenases and thioredoxin systems, which serve as endogenous lifeguard of cells. This paper is a review of the expression and function of vitagenes in aging and AD brain, as well as relevant pharmacological study.

[Effect and mechanism of Coeloglossum viride var. bracteatum extract on scopolamine-induced deficits of learning and memory behavior of rodents].

The aim of the present study is to investigate the effect and mechanism of Coeloglossum viride var. bracteatum extract (CE) on scopolamine-induced learning and memory deficits. Learning and memory deficits of mice were evaluated by step-down passive avoidance test. Long-term potentiation of rats was detected in the dentate gyrus of hippocampus. Brain acetylcholinesterase (AChE) and choline acetyltransferase (ChAT) activities were also determined. The results showed that scopolamine impaired learning and memory performance and LTP induction in hippocampus. Oral administration of CE (5, 10, and 20 mg x kg(-1)) significantly alleviated scopolamine-induced memory deficits measured by step-down test (P < 0.05). CE (5 mg x kg(-1), ip) significantly reversed the inhibitory effect of scopolamine on LTP in rats. In addition, CE was found to increase the activity of ChAT in rat brain. These results suggested that CE could alleviate scopolamine-induced learning and memory deficits, which might be due to the LTP-improvement and ChAT activity enhancement.

Bicyclol: a novel antihepatitis drug with hepatic heat shock protein 27/70-inducing activity and cytoprotective effects in mice.

Heat shock proteins (HSPs) are the best-known endogenous factors that protect against cell injury under various pathological conditions and that can be induced by various physical, chemical, and biological stressors. New research seeks to discover a compound that is clinically safe and can induce the accumulation of HSPs in patients. This paper reports that the oral administration of three doses of bicyclol, a novel antihepatitis drug, induced hepatic HSP27 and HSP70 expression in a time- and dose-dependent manner, and that bicyclol treatment stimulated heat shock factor 1 (HSF1) activation in mice. The inducing effects of bicyclol on HSP27, HSP70 and HSF1 were all blocked by quercetin, an inhibitor of HSP biosynthesis. The cytoprotective effect of HSP27/70 induced by bicyclol against hepatotoxicity of acetaminophen (AP) was assessed in mice. The prior administration of bicyclol markedly suppressed AP-induced liver injury as indicated by the reduction in the elevation of serum alanine aminotransferase and aspartate aminotransferase, in liver necrosis, in the release of cytochrome c and apoptosis-inducing factor from mitochondria, as well as in hepatic deoxyribonucleic acid fragmentation in mice. However, all the above actions of bicyclol against AP-induced mouse liver injuries were significantly attenuated by quercetin. This is the first report to show that bicyclol induces hepatic HSP27/70 expression via activation of HSF1 and that the cytoprotective action of bicyclol against liver injury is mediated by its induction of HSP27/70. These results provide new evidence for elucidating the mechanism of the hepatoprotective action of bicyclol in animals and patients.

Pinocembrin prevents glutamate-induced apoptosis in SH-SY5Y neuronal cells via decrease of bax/bcl-2 ratio.

Pinocembrin is the most abundant flavonoids in propolis, and has been proven to have antioxidant, antibacterial and anti-inflammatory property. To assess the protective effects of pinocembrin on neurons, SH-SY5Y neuronal cells were pretreated with pinocembrin for 2 h followed by co-treatment with glutamate (2 mM) for 12 h. Cell viability was determined by(3,4,5-dimethylthiazol-2-yl)-2,5-diphenylte-trazolium bromide assay, and apoptosis was confirmed by cell morphology, capillary zone electrophoresis and flow cytometry assay. Cell morphology was evaluated with Hoechst33258/PI dye. Treatment with pinocembrin (10(-5), 10(-6), 10(-7) mol/l) increased cell viability dose-dependently, inhibited LDH release and attenuated apoptosis. Intracellular free [Ca(2+)] was increased after glutamate exposure, and this increase was attenuated in cells treated with pinocembrin. bax mRNA expression increased remarkably following glutamate exposure and pinocembrin treatment manifested a reduction effect. bcl-2 mRNA expression changes were not detected in groups with or without pinocembrin. Western blotting results indicated that pinocembrin treatment reduced the expression of Bax and had no effect on Bcl-2, thus decreased the Bax-Bcl-2 ratio, which is in consistent with the gene expression result. Pinocembrin could also down-regulate the expression of p53 protein, and inhibit the release of cytochrome c from mitochondria to cytosol. Thus we conclude that pinocembrin exerts its neuroprotective effects in glutamate injury model partly by inhibiting p53 expression, thus Bax-Bcl-2 ratio, and the release of cytochrome c.

The establishment of a novel non-alcoholic steatohepatitis model accompanied with obesity and insulin resistance in mice.

Non-alcoholic steatohepatitis (NASH) is a hepatic manifestation of the metabolic syndrome that can progress to liver cirrhosis. The major aim of this study was to establish a novel NASH mouse model accompanied by obesity and insulin resistance, then explore the molecular mechanisms of NASH and evaluate the effects of both the peroxisome proliferator-activated receptor alpha (PPARalpha) agonist fenofibrate and the PPARgamma agonist rosiglitazone in this established NASH model. The novel model was induced in C57BL/6 mice by 23 weeks of ad libitum feeding of a modified high-fat diet (mHFD), with lower methinione and choline and higher fat content. In comparison to the controls, the model animals developed pronounced obesity, dyslipidemia and insulin resistance. Marked liver lesions characterized by severe steatosis, inflammation, fibrosis, increased hepatic triglyceride content, and elevated serum alanine aminotransferase (ALT) levels were observed in the models. In this novel model, treatment with fenofibrate or rosiglitazone significantly improved insulin sensitivity and corrected dyslipidemia; however, fenofibrate was more effective than rosiglitazone in improving hepatic morphology and ALT levels. Further study showed that long-term feeding of mHFD significantly increased expression of mRNA for hepatic PPARgamma, adipose fatty acid binding protein (ap2) and CD36 and suppressed expression of mRNA for hepatic PPARalpha and carnitine palmitoyl transferase-1a (CPT-1a). These results showed the successful establishment of the combined NASH and obese-insulin resistance mouse model. Additionally, aberrant expressions of hepatic PPARalpha and PPARgamma may play a major role in the pathogenesis of NASH by affecting hepatic lipogenesis and fatty acid oxidation in this novel model.

[The roles of Kupffer cells in the development and regression of liver fibrosis].

Hepatic fibrosis results from iterative hepatic injury with sustained inflammation, formation of scar tissue, loss of tissue architecture and organ failure. There is no doubt, from both human and animal studies, that too much or too protracted inflammation in the liver leads to excess scarring. During liver injury, Kupffer cells can quickly flood the hepatic milieu with soluble mediators, including oxidants, cytokines, and proteinases, which can affect stellate cell proliferation, migration, and differentiation. On the other hand, the contribution of Kupffer cells to regression of hepatic fibrosis has been demonstrated. These findings underscore the potential importance of hepatic macrophages in regulating both stellate cell biology and extracellular material degradation during regression of hepatic fibrosis. Therefore, biological characterization of Kupffer cells, their interactions with stellate cells in the cytokine environment are essential to understand the mechanisms underlying the progressive development of excessive scarring in the liver as well as the ability of the liver for tissue repair and recovery.