Disease-specific mechanisms of fibrosis: hepatitis C virus and nonalcoholic steatohepatitis

Obesity, non-alcoholic fatty liver disease and hepatocellular carcinoma: current status and therapeutic targets

Obesity is a global epidemic and overwhelming evidence indicates that it is a risk factor for numerous cancers, including hepatocellular carcinoma (HCC), the third leading cause of cancer-related deaths worldwide. Obesity-associated hepatic tumorigenesis develops from nonalcoholic fatty liver disease (NAFLD), progressing to nonalcoholic steatohepatitis (NASH), cirrhosis and ultimately to HCC. The rising incidence of obesity is resulting in an increased prevalence of NAFLD and NASH, and subsequently HCC. Obesity represents an increasingly important underlying etiology of HCC, in particular as the other leading causes of HCC such as hepatitis infection, are declining due to effective treatments and vaccines. In this review, we provide a comprehensive overview of the molecular mechanisms and cellular signaling pathways involved in the pathogenesis of obesity-associated HCC. We summarize the preclinical experimental animal models available to study the features of NAFLD/NASH/HCC, and the non-invasive methods to diagnose NAFLD, NASH and early-stage HCC. Finally, since HCC is an aggressive tumor with a 5-year survival of less than 20%, we will also discuss novel therapeutic targets for obesity-associated HCC and ongoing clinical trials.

Antrodia camphorata-Derived Antrodin C Inhibits Liver Fibrosis by Blocking TGF-Beta and PDGF Signaling Pathways

Hepatic stellate cells (HSCs) play an essential role in the development of liver fibrosis. Antrodia camphorata (A. camphorata) is a medicinal fungus with hepatoprotective effect. This study investigated whether Antrodin C, an A. camphorata-fermented metabolite, could exert a protective role on liver fibrosis both in vitro and in vivo. The anti-fibrotic effect of Antrodin C was investigated in CFSC-8B cell (hepatic stellate cell) stimulated by transforming growth factor-β1 (TGF-β1) or platelet-derived growth factor-BB (PDGF-BB) in vitro and in CCl4 induced liver fibrosis in mice. Antrodin C (50 μM) inhibited TGF-β1 or PDGF-BB stimulated CFSC-8B cell activation, migration and extracellular matrix (ECM) accumulation (all p < 0.05). Antrodin C (3, 6 mg/kg/d) oral administration reduced the degree of liver fibrosis induced by CCl4 in mice. Antrodin C down-regulated the expression of α-smooth muscle actin (α-SMA) and collagen I in fibrotic livers. Furthermore, Antrodin C ameliorated alanine aminotransferase (ALT) and aspartate aminotransferase (AST) elevation in serum (all p < 0.05). Mechanistically, Antrodin C executes its anti-fibrotic activity through negatively modulate TGF-β1 downstream SMAD Family Member 2 (Smad2), AKT Serine/Threonine Kinase 1 (AKT), extracellular signal-regulated kinase (ERK), and P38 MAP Kinase (P38), as well as PDGF-BB downstream AKT and ERK signaling pathways. Antrodin C ameliorates the activation, migration, ECM production in HSCs and CCl4-induced liver fibrosis in mice, suggesting that Antrodin C could serve as a protective molecule against liver fibrosis.

Strategies Targeting the Innate Immune Response for the Treatment of Hepatitis C Virus-Associated Liver Fibrosis

Direct-acting antivirals eliminate hepatitis C virus (HCV) in more than 95% of treated individuals and may abolish liver injury, arrest fibrogenesis, and reverse fibrosis and cirrhosis. However, liver regeneration is usually a slow process that is less effective in the late stages of fibrosis. What is more, fibrogenesis may prevail in patients with advanced cirrhosis, where it can progress to liver failure and hepatocellular carcinoma. Therefore, the development of antifibrotic drugs that halt and reverse fibrosis progression is urgently needed. Fibrosis occurs due to the repair process of damaged hepatic tissue, which eventually leads to scarring. The innate immune response against HCV is essential in the initiation and progression of liver fibrosis. HCV-infected hepatocytes and liver macrophages secrete proinflammatory cytokines and chemokines that promote the activation and differentiation of hepatic stellate cells (HSCs) to myofibroblasts that produce extracellular matrix (ECM) components. Prolonged ECM production by myofibroblasts due to chronic inflammation is essential to the development of fibrosis. While no antifibrotic therapy is approved to date, several drugs are being tested in phase 2 and phase 3 trials with promising results. This review discusses current state-of-the-art knowledge on treatments targeting the innate immune system to revert chronic hepatitis C-associated liver fibrosis. Agents that cause liver damage may vary (alcohol, virus infection, etc.), but fibrosis progression shows common patterns among them, including chronic inflammation and immune dysregulation, hepatocyte injury, HSC activation, and excessive ECM deposition. Therefore, mechanisms underlying these processes are promising targets for general antifibrotic therapies.

Mechanisms for the Resolution of Organ Fibrosis

Fibrosis is a dynamic process with the potential for reversibility and restoration of near-normal tissue architecture and organ function. Herein, we review mechanisms for resolution of organ fibrosis, in particular that involving the lung, with an emphasis on the critical roles of myofibroblast apoptosis and clearance of deposited matrix.

Triggering and resolution of inflammation in NASH

Nonalcoholic steatohepatitis (NASH) is considered the progressive form of nonalcoholic fatty liver disease (NAFLD) and is characterized by liver steatosis, inflammation, hepatocellular injury and different degrees of fibrosis. A central issue in this field relates to the identification of those factors that trigger inflammation, thus fuelling the transition from nonalcoholic fatty liver to NASH. These triggers of liver inflammation might have their origins outside the liver (such as in adipose tissue or the gut) as well as inside the organ (for instance, lipotoxicity, innate immune responses, cell death pathways, mitochondrial dysfunction and endoplasmic reticulum stress), both of which contribute to NASH development. In this Review, we summarize the currently available information on the key upstream triggers of inflammation in NASH. We further delineate the mechanisms by which liver inflammation is resolved and the implications of a defective pro-resolution process. A better knowledge of these mechanisms should help to design targeted therapies able to halt or reverse disease progression.

Activation of Insulin-PI3K/Akt-p70S6K Pathway in Hepatic Stellate Cells Contributes to Fibrosis in Nonalcoholic Steatohepatitis

BACKGROUND AND AIMS

Hyperinsulinemia and insulin resistance are hallmark features of nonalcoholic fatty liver disease and steatohepatitis (NASH). It remains unclear whether and how insulin contributes to the development of fibrosis in NASH. In this study, we explored insulin signaling in the regulation of hepatic stellate cell (HSC) activation and the progression of NASH-fibrosis.

METHODS

Phosphorylation of Akt and p70S6K were examined in primary HSC and in a rat model of NASH-fibrosis induced by high-fat and high-cholesterol diet for 24 weeks. HSC activation was analyzed for the changes in cell morphology, intracellular lipid droplets, expression of α-SMA and cell proliferation. The serum markers and histology for NASH-fibrosis were also characterized in animals.

RESULTS

Insulin enhanced the expression of smooth muscle actin-α in quiescent but not in activated HSC in culture. Insulin-mediated activation of the PI3K/Akt-p70S6K pathway was involved in the regulation of profibrogenic effects of insulin. Although insulin did not stimulate HSC proliferation directly, the insulin-PI3K/Akt-p70S6K pathway was necessary for serum-enhanced cell proliferation during initial HSC activation. In a rat model of NASH-fibrosis induced by high-fat and high-cholesterol diet, hyperinsulinemia is associated with the activation of p70S6K and enhanced fibrosis.

CONCLUSION

The insulin-PI3K/Akt-p70S6K pathway plays an important role in the early activation of HSC. The profibrogenic effect of insulin is dependent on the activation stage of HSC. Dysregulation of the insulin pathway likely correlates with the development of fibrosis in NASH, suggesting a potentially novel antifibrotic target of inhibiting insulin signaling in HSC.

MicroRNA in Metabolic Re-Programming and Their Role in Tumorigenesis

The process of metabolic re-programing is linked to the activation of oncogenes and/or suppression of tumour suppressor genes, which are regulated by microRNAs (miRNAs). The interplay between oncogenic transformation-driven metabolic re-programming and modulation of aberrant miRNAs further established their critical role in the initiation, promotion and progression of cancer by creating a tumorigenesis-prone microenvironment, thus orchestrating processes of evasion to apoptosis, angiogenesis and invasion/migration, as well metastasis. Given the involvement of miRNAs in tumour development and their global deregulation, they may be perceived as biomarkers in cancer of therapeutic relevance.

The effect of body weight on the severity and clinical course of ulcerative colitis

PURPOSE

Obesity is a risk factor for inflammatory diseases such as nonalcoholic steatohepatitis, pancreatitis, and Crohn's disease. The effect of being overweight or obese on the severity and clinical course of ulcerative colitis (UC) was assessed in a retrospective analysis of data from 2000-2006.

METHODS

Two hundred and two consecutive UC patients were categorized according to body mass index (BMI). Patient and disease characteristics were compared between BMI categories using chi-square or Kruskal-Wallis tests. The percentage of patients with active UC, complications, steroid therapy, or immunosuppressive therapy was calculated for each group, and matched pair analyses were performed.

RESULTS

Ten patients (5%) were underweight, 111 (55%) were normal weight, 54 (26.7%) were overweight, and 27 (13.4%) were obese. Pancolitis was inversely related to weight. BMI was also inversely correlated to disease severity, with a significantly smaller proportion of years with chronic active disease among overweight subjects versus normal-weight subjects (17.6 versus 23.9%, p = 0.05). More overweight than normal-weight patients had no chronic active disease in any year (66 versus 49%, p = 0.06), and the proportion of years with disease complications was higher in normal weight than in overweight subjects (1.8 versus 0.4%, p = 0.08). Disease activity during 2000-2006 was higher for underweight versus normal-weight patients, and only 20% of underweight subjects had no hospital admission compared to 80% of normal-weight patients (p = 0.07).

CONCLUSIONS

This first study to explore the influence of obesity on UC showed that high BMI had rather a favorable effect on the prognosis, whereas low BMI pointed to a more severe course of the disease.

Vitamin D and nonalcoholic fatty liver disease (NAFLD): is it more than just an association?

Vitamin D is a secosteroid with known effects on calcium homeostasis that has recently been shown to have other significant functions regarding immune modulation, cell differentiation and proliferation, and the inflammatory response. As our understanding of the many functions of vitamin D has grown, the presence of vitamin D deficiency (VDD) has become more evident in Western populations. Concomitantly, nonalcoholic fatty liver disease (NAFLD) has become the most common cause of chronic liver disease. NAFLD and VDD are often found together, and while this is not unexpected, given their similar associations with obesity and sedentary lifestyle, a growing body of evidence points to a closely linked and potentially causative relationship between VDD and NAFLD. The epidemiologic association between VDD and NAFLD as well as the role of VDD in the pathogenesis of NAFLD and the available evidence on the clinical utility of vitamin D replacement in NAFLD populations are discussed.

Inflammation and liver tumorigenesis

Inflammation has been considered as one of the hallmarks of cancer, and chronic hepatitis is a major cause of liver cancer. This review will focus on the pathogenic role of inflammation in hepatocarcinogenesis and will discuss recent advances in understanding the chronic hepatitis-liver cancer link based on hot spots in liver cancer research, including cellular interaction, cytokines, microRNA and stem cells. All of these mechanisms should be taken into consideration because they are crucial for the development of more efficacious therapeutic strategies for preventing and treating human chronic hepatitis and hepatocellular carcinoma.

miRNAs, polyphenols, and chronic disease

MicroRNAs (miRNAs) are small noncoding RNAs, approximately 18-25 nucleotides in length, that modulate gene expression at the posttranscriptional level. Thousands of miRNAs have been described, and it is thought that they regulate some aspects of more than 60% of all human cell transcripts. Several polyphenols have been shown to modulate miRNAs related to metabolic homeostasis and chronic diseases. Polyphenolic modulation of miRNAs is very attractive as a strategy to target numerous cell processes and potentially reduce the risk of chronic disease. Evidence is building that polyphenols can target specific miRNAs, such as miR-122, but more studies are necessary to discover and validate additional miRNA targets.

Oxidative stress is closely associated with insulin resistance in genotypes 1 and 3 chronic hepatitis C

BACKGROUND

Chronic hepatitis C (CHC) infection is associated with insulin resistance and with oxidative stress, but the relationship between the two has not been thoroughly examined.

PURPOSE

To evaluate the association between insulin resistance and oxidative stress in CHC patients.

METHOD

In 115 CHC patients (68 with genotype 1 and 47 with genotype 3), the relationship between the serum concentration of malondialdehyde (MDA), a marker of oxidative stress and insulin resistance as defined by the homeostasis model (HOMA-IR) was examined.

RESULTS

There was no significant difference in MDA levels between genotype 1- and genotype 3-infected subjects (12.882 vs. 12.426 ng/mL, p = 0.2). By univariate analysis, factors associated with HOMA-IR in both genotypes were oxidative stress as measured by MDA (p = 0.002), body mass index (BMI), portal activity, and fibrosis. Genotype-specific differences in HOMA-IR association were steatosis and triglycerides (TG) for genotype 1, and age and glutathione (GSH) for genotype 3. In a stepwise multiple linear regression analysis in both genotypes, MDA was a significant and independent predictor of HOMA-IR (p = 0.04). As expected, BMI and fibrosis were likewise independently correlated to HOMA-IR. In addition, MDA levels were higher (p < 0.001) and GSH levels were lower (p = 0.023) in insulin-resistant subjects compared to their insulin-sensitive counterparts.

CONCLUSIONS

It is concluded that in CHC, oxidative stress is an independent predictor of HOMA-IR, irrespective of virus genotype. Further studies on the role of oxidative stress in the development of insulin resistance in CHC are warranted.

Vitamin d deficiency in patients with chronic liver disease and cirrhosis

Vitamin D is now widely recognized to have multiple extraskeletal health functions. The liver is one of the major organs involved in its metabolism. Recent studies have demonstrated a very high prevalence of vitamin D deficiency and insufficiency in patients with chronic liver disease and cirrhosis. There is an emerging interest to explore the relationship between vitamin D deficiency and prevalence and severity of non-alcoholic liver disease and response to antiviral therapy in hepatitis C. In this review, we discuss the current status of our understanding of vitamin D metabolism and vitamin D deficiency in patients with chronic liver disease and cirrhosis.

p38 mitogen-activated protein kinase and liver X receptor-α mediate the leptin effect on sterol regulatory element binding protein-1c expression in hepatic stellate cells

Leptin, a key hormone in regulating energy homeostasis, is mainly produced by adipocytes. Cogent evidence indicates a unique role of leptin in the promotion of liver fibrosis. Hepatic stellate cell (HSC) activation is a pivotal step in the process of liver fibrosis. Sterol regulatory element binding protein (SREBP)-1c, a critical transcription factor for lipid synthesis and adipocyte differentiation, functions as a key transcription factor in inhibition of HSC activation. SREBP-1c is highly expressed in quiescent HSCs and downregulated upon HSC activation. The aim of this study is to examine the effect of leptin on SREBP-1c gene expression in HSCs in vitro and in vivo and elucidate the underlying mechanisms. The results of the present study demonstrated that leptin strongly inhibited SREBP-1c expression in HSCs in vivo and in vitro. p38 MAPK was involved in leptin regulation of SREBP-1c expression in cultured HSCs. Leptin-induced activation of p38 MAPK led to the decreases in liver X receptor (LXR)-α protein level, activity and its binding to the SREBP-1c promoter, which caused the downregulation of SREBP-1c expression. Moreover, leptin inhibition of SREBP-1c expression via p38 MAPK increased the expression of alpha1(I) collagen in HSCs. Our results might provide new insights into the mechanisms of the unique role of leptin in the development of liver fibrosis and might have potential implications for clarifying the molecular mechanisms underlying liver fibrosis in diseases in which circulating leptin levels are elevated such as nonalcoholic steatohepatitis, type 2 diabetes mellitus and alcoholic cirrhosis.

Complement factor C5 deficiency significantly delays the progression of biliary fibrosis in bile duct-ligated mice

Fibrogenesis represents the universal response of the liver to chronic liver injury. Complement factor C5 has been linked to fibrosis in murine toxic liver injury and human chronic hepatitis C. C5 may also play a central role in chronic cholestatic disorders, since the BA receptor FXR has been characterized as an activator of the C3 gene. We aimed to investigate, whether C5 deficiency is able to prevent biliary fibrosis in the mouse bile-duct-ligation model. BDL for 1-4 weeks was performed in either Hc(0)/Hc(0) mice (deficient for C5) or WT controls. BA levels were measured by RIA. Histological examination included H&E, sirius-red and immunohistochemistry. mRNA expression was quantified by RT-PCR. Protein expression levels were determined by Western blotting or ELISA. Enzymatic MMP-activity was analysed by zymography. One week BDL leads to fibrosis in WT (F2.0 ± 0), while it is almost absent in Hc(0)/Hc(0) mice (F0.5 ± 0.5). No differences in fibrosis can be detected at week-4. Together with delayed fibrogenesis at week-1, fibrotic markers are decreased in Hc(0)/Hc(0) mice. Expression of the inflammatory cytokine TNF-α is decreased in Hc(0)/Hc(0) mice. In parallel C5 deficiency leads to an attenuated peribiliary infiltration of CD45(+) cells in fibrotic areas together with decreased MMP-9 expression and gelatinase activity. The present study proves a functional role of C5 during biliary fibrogenesis. C5 deficiency leads to attenuated inflammation and normalized MMP-9 activity concomitantly with a significant reduction of fibrosis. C5 appears to be an attractive target for future therapeutic intervention in chronic cholestatic liver disease.

Cytokeratins in hepatitis

Experimental and clinical evidence suggests that cytokeratins (CK), among other physiological functions, are expressed in hepatocytes and can be released in the bloodstream after acute or chronic inflammatory liver injury. Interest in CK in viral and nonviral hepatitis has been rapidly increasing during the last years, especially as they have been proposed as circulating biomarkers of hepatocyte necrosis and apoptosis. In the present review, we sought to summarize and discuss the alterations in circulating CK levels in different form viral and nonviral hepatitis, as well as their potential relation with liver histology. Understanding the mechanisms of hepatitis impact on CK and vice versa is a promising area of research that will positively enhance our understanding of the complexity of acute and chronic inflammatory liver injury.

microRNAs: Fad or future of liver disease

microRNAs (miRs) are small non-coding RNAs that regulate both mRNA and protein expression of target genes, which results in alterations in mRNA stability or translation inhibition. miRs influence at least one third of all human transcripts and are known regulators of various important cellular growth and differentiation factors. miRs have recently emerged as key regulatory molecules in chronic liver disease. This review details recent contributions to the field of miRs that influence liver development and the broad spectrum of disease, from non-alcoholic fatty liver disease to fibrosis/cirrhosis, with particular emphasis on hepatic stellate cells and potential use of miRs as therapeutic tools.

Oxidative stress and steatosis are cofactors of liver injury in primary biliary cirrhosis

BACKGROUND

Factors responsible for the progression of primary biliary cirrhosis (PBC) are still poorly understood. In the present study, we investigated the associations between the stage of PBC and the immune reaction triggered by oxidative stress; the presence of obesity, steatosis,steatohepatitis; and other toxic, metabolic, or steatogenic factors.

METHODS

We studied clinical, laboratory, and histological data for 274 untreated patients with serum antimitochondrial antibody (AMA)-positive PBC. Circulating IgG against human serum albumin adducted with malondialdeyde, the major product of lipid peroxidation, was measured in these patients and in a group of 98 sex-, age and body mass index (BMI)-matched controls.

RESULTS

Steatosis was present in 40.5% of all patients. Steatohepatitis was present in 14.9% of all patients. There was a significant association between the frequencies of steatosis and steatohepatitis and the worsening of PBC. Circulating IgG against lipid peroxidation products was significantly higher in the PBC patients than in the controls. Titers of lipid peroxidation-related antibodies were significantly increased in patients with steatosis and inpatients at more advanced stages. Bivariate analysis revealed a significant association between indirect evidence of oxidative stress, steatosis, steatohepatitis, age, BMI, frequency of diabetes, alcohol intake, iron grade after Perl's stain, and PBC stage. Logistic regression analysis confirmed that the titers of antibodies against lipid peroxidation products (odds ratio 4.5, p< .001, 95% confidence interval 3.9–14.4), the presence of steatosis (odds ratio 4.1, 95% confidence interval 2.5–15.4, p< .001), higher BMI (odds ratio 3.9, p< .021, 95%confidence interval 1.4–9.5), and alcohol intake (males ≥ 30 g/day, females ≥ 20 g/day, odds ratio 4.5,95% confidence interval 1.3–19.8, p< .029) were independently associated with more advanced stages of the disease.

CONCLUSIONS

The immune reactions triggered by oxidative stress, steatosis, obesity, and alcohol intake are independent predictors of PBC stage progression.

Hepatitis C virus induces the cannabinoid receptor 1

BACKGROUND

Activation of hepatic CB(1) receptors (CB(1)) is associated with steatosis and fibrosis in experimental forms of liver disease. However, CB(1) expression has not been assessed in patients with chronic hepatitis C (CHC), a disease associated with insulin resistance, steatosis and metabolic disturbance. We aimed to determine the importance and explore the associations of CB(1) expression in CHC.

METHODS

CB(1) receptor mRNA was measured by real time quantitative PCR on extracted liver tissue from 88 patients with CHC (genotypes 1 and 3), 12 controls and 10 patients with chronic hepatitis B (CHB). The Huh7/JFH1 Hepatitis C virus (HCV) cell culture model was used to validate results.

PRINCIPAL FINDINGS

CB(1) was expressed in all patients with CHC and levels were 6-fold higher than in controls (P<0.001). CB(1) expression increased with fibrosis stage, with cirrhotics having up to a 2 fold up-regulation compared to those with low fibrosis stage (p<0.05). Even in mild CHC with no steatosis (F0-1), CB(1) levels remained substantially greater than in controls (p<0.001) and in those with mild CHB (F0-1; p<0.001). Huh7 cells infected with JFH-1 HCV showed an 8-fold upregulation of CB(1), and CB(1) expression directly correlated with the percentage of cells infected over time, suggesting that CB(1) is an HCV inducible gene. While HCV structural proteins appear essential for CB(1) induction, there was no core genotype specific difference in CB(1) expression. CB(1) significantly increased with steatosis grade, primarily driven by patients with genotype 3 CHC. In genotype 3 patients, CB(1) correlated with SREBP-1c and its downstream target FASN (SREBP-1c; R=0.37, FASN; R=0.39, p<0.05 for both).

CONCLUSIONS/SIGNIFICANCE

CB(1) is up-regulated in CHC and is associated with increased steatosis in genotype 3. It is induced by the hepatitis C virus.

Leptin inhibits PPARgamma gene expression in hepatic stellate cells in the mouse model of liver damage

Hepatic stellate cell (HSC) activation is a key cellular event in the development of liver fibrosis. Peroxisome proliferator-activated receptor-gamma (PPARgamma) has been shown to function as a key transcription regulator linked to suppressing HSC activation. Compelling evidence indicates that leptin plays a unique role in the development of liver fibrosis. The aim of this study is to investigate the in vivo impact of leptin on PPARgamma expression in HSCs in the model of TAA-induced liver damage. The results of the present study provide the first in vivo evidence that leptin might exert an inhibitory effect on PPARgamma protein expression in HSCs, which is mediated at least through leptin-induced ERK1/2 activation. Long-form leptin receptor is involved in leptin-induced ERK1/2 activation and the subsequent decline in PPARgamma expression in HSCs in the model. Furthermore, the inhibitory effect of leptin on PPARgamma protein expression enhances HSC activation and proliferation in this model. The in vivo findings from this report might provide additional insights into the mechanisms underlying the profibrogenic action of leptin in liver.

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.

Fatty liver and lipotoxicity

Fatty liver disease comprises a spectrum ranging from simple steatosis to steatohepatitis which can progress to liver cirrhosis and hepatocellular cancer. Hepatic lipotoxicity may ensue when the hepatic capacity to utilize, store and export fatty acids (FA) as triglycerides is overwhelmed. Additional mechanisms of hepatic lipotoxicity include abnormal FA oxidation with formation of reactive oxygen species, disturbances in cellular membrane FA and phospholipid composition, alterations of cholesterol content and ceramide signalling. Lipotoxicity is a key factor for the progression of fatty liver disease by inducing hepatocellular death, activating Kupffer cells and an inflammatory response, impairing hepatic insulin signalling resulting in insulin resistance, and activation of a fibrogenic response in hepatic stellate cells that can ultimately lead to cirrhosis. Therefore, the concept of hepatic lipotoxicity should be considered in future therapeutic concepts for fatty liver disease.

The metabolic syndrome: how it may influence hepatic stellate cell activation and hepatic fibrosis

PURPOSE OF REVIEW

To highlight the metabolic or inflammatory components, deregulated in or pathogenic for the metabolic syndrome, that may, directly or indirectly, modulate hepatic fibrogenesis.

RECENT FINDINGS

Advanced glycation end products signal profibrogenetic transformation of hepatic stellate cells. Altered adipocytokines favor insulin resistance and steatosis. They participate to the proinflammatory status of the metabolic syndrome. Among them, leptin has been shown to directly enhance fibrogenesis, whereas adiponectin has shown antifibrotic properties. The renin-angiotensin system, a component of arterial hypertension, is activated in the diseased liver, and there is convincing evidence that blockade of angiotensin II signaling attenuates fibrosis. Endocannabinoids, whose hepatic production and signaling capability are increased with insulin resistance and obesity, signal profibrotic response via the preponderant receptor, cannabinoid receptor 1, whereas antifibrotic and anti-inflammatory signals are rather generated via stimulation of cannabinoid receptor 2. Finally, recent data demonstrate that modulation of innate immunity, particularly modulation of natural killer and natural killer T cells, has potential roles in the resolution of steatohepatitis and fibrosis.

SUMMARY

Several features associated with the metabolic syndrome can undoubtedly modulate liver fibrosis. More studies are needed to identify those that are prominent determinants of fibrosis in the metabolic syndrome and the benefit of their targeting for fibrosis prevention and treatment.

Therapeutic effects of Lanyuzan granules on hepatic fibrosis in rats

AIM: To explore the curative effects of Lanyuzan granules on hepatic fibrosis in dimethylnitrosamine (DMN)-induced SD rat model and its mechanism.

METHODS: Forty-five female SD rats were randomly divided into six groups: a control group (n = 5), a model group (n = 8), three treatment groups with different dosage of Lanyuzan granules (n = 8), and a positive control group (n = 8). In the following 30 days, an intraperitoneal injection of dimethylnitrosamine (DMN) 10 mg/kg was performed in five groups every three days, except in the control group. On the thirty-first day, the five indexes of hepatic function, serum concentrations of ALT, AST and ALB, the expressions of a-smooth muscle actin (a-SMA) and matrix metalloproteinase-2 (MMP-2) were measured. Moreover, pathological changes were observed on liver tissue with HE staining.

RESULTS: In liver fibrosis model group, serum concentrations of ALT and AST were significantly higher and concentration of ALB was significantly lower (P < 0.05), while significant increase in a-SMA expression and significant decrease in MMP-2 expression were observed compared with the normal group (182.042 ± 0.658 vs 60.879 ± 0.987; 145.612 ± 4.66 vs 74.824 ± 9.004; 16.078 ± 0.633 vs 28.971 ± 0.443; 161.667 ± 26.766 vs 80.167 ± 10.135; 5.994 ± 1.360 vs 8.270 ± 0.289, all P < 0.05). Decreased ALT and AST serum concentrations, significantly increased ALB concentration, lowered a-SMA expression and elevated MMP-2 expression in liver tissue, were observed in Lanyuzan granules treatment group compared with model control group (87.856 ± 8.526, 106.69 ± 0.987, 136.11 ± 0.329 vs 182.042 ± 0.658; 94.208 ± 2.017, 107.602 ± 20.014, 118.847 ± 5.486 vs 145.612 ± 4.66; 23.412 ± 0.775, 19.653 ± 0.775, 18.635 ± 0.221 vs 16.078 ± 0.633; 109.958 ± 3.607, 117.833 ± 6.600, 119.833 ± 6.167 vs 161.667 ± 26.766; 11.610 ± 0.523, 10.367 ± 0.714 vs 5.994 ± 1.360, all P < 0.05). No notable difference was observed between low dosage group and model control group. The pathological observation showed hepatic fibrosis was alleviated markedly.

CONCLUSION: Lanyuzan granules may play a part in the alleviation of inflammation and the protection of liver by markedly relieving and inhibiting the formation of hepatic fibrosis induced by dimethylnitrosamine.