Tranilast, an antifibrogenic agent, ameliorates a dietary rat model of nonalcoholic steatohepatitis

Unlocking the potential of tranilast: Targeting fibrotic signaling pathways for therapeutic benefit

Fibrosis is the excessive deposition of extracellular matrix in an organ or tissue that results from an impaired tissue repair in response to tissue injury or chronic inflammation. The progressive nature of fibrotic diseases and limited treatment options represent significant healthcare challenges. Despite the substantial progress in understanding the mechanisms of fibrosis, a gap persists translating this knowledge into effective therapeutics. Here, we discuss the critical mediators involved in fibrosis and the role of tranilast as a potential antifibrotic drug to treat fibrotic conditions. Tranilast, an antiallergy drug, is a derivative of tryptophan and has been studied for its role in various fibrotic diseases. These include scleroderma, keloid and hypertrophic scars, liver fibrosis, renal fibrosis, cardiac fibrosis, pulmonary fibrosis, and uterine fibroids. Tranilast exerts antifibrotic effects by suppressing fibrotic pathways, including TGF-β, and MPAK. Because it disrupts fibrotic pathways and has demonstrated beneficial effects against keloid and hypertrophic scars, tranilast could be used to treat other conditions characterized by fibrosis.

Mast cells and the gut-liver Axis: Implications for liver disease progression and therapy

The role of mast cells, traditionally recognized for their involvement in immediate hypersensitivity reactions, has garnered significant attention in liver diseases. Studies have indicated a notable increase in mast cell counts following hepatic injury, underscoring their potential contribution to liver disorder pathogenesis. Predominantly situated in connective tissue that envelops the hepatic veins, bile ducts, and arteries, mast cells are central to both initiating and perpetuating liver disorders. Additionally, they are crucial for maintaining gastrointestinal barrier function. The gut-liver axis emphasizes the complex, two-way communication between the gut microbiome and the liver. Past research has implicated gut microbiota and their metabolites in the progression of hepatic disorders. This review sheds light on how mast cells are activated in various liver conditions such as alcoholic liver disease (ALD), non-alcoholic fatty liver disease (NAFLD), viral hepatitis, hepatic fibrogenesis, and hepatocellular carcinoma. It also briefly explores the connection between the gut microbiome and mast cell activation in these hepatic conditions.

Role of pattern recognition receptors in the development of MASLD and potential therapeutic applications

Metabolic dysfunction-associated steatotic liver disease (MASLD) has become one of the most prevalent liver diseases worldwide, and its occurrence is strongly associated with obesity, insulin resistance (IR), genetics, and metabolic stress. Ranging from simple fatty liver to metabolic dysfunction-associated steatohepatitis (MASH), even to severe complications such as liver fibrosis and advanced cirrhosis or hepatocellular carcinoma, the underlying mechanisms of MASLD progression are complex and involve multiple cellular mediators and related signaling pathways. Pattern recognition receptors (PRRs) from the innate immune system, including Toll-like receptors (TLRs), C-type lectin receptors (CLRs), NOD-like receptors (NLRs), RIG-like receptors (RLRs), and DNA receptors, have been demonstrated to potentially contribute to the pathogenesis for MASLD. Their signaling pathways can induce inflammation, mediate oxidative stress, and affect the gut microbiota balance, ultimately resulting in hepatic steatosis, inflammatory injury and fibrosis. Here we review the available literature regarding the involvement of PRR-associated signals in the pathogenic and clinical features of MASLD, in vitro and in animal models of MASLD. We also discuss the emerging targets from PRRs for drug developments that involved agent therapies intended to arrest or reverse disease progression, thus enabling the refinement of therapeutic targets that can accelerate drug development.

Diabetes Accelerates Steatohepatitis in Mice: Liver Pathology and Single-Cell Gene Expression Signatures

Glucose lowering independently reduces liver fibrosis in human nonalcoholic fatty liver disease. This study investigated the impact of diabetes on steatohepatitis and established a novel mouse model for diabetic steatohepatitis. Male C57BL/6J mice were fed a 60% high-fat diet (HFD) and injected with carbon tetrachloride (CCl4) and streptozotocin (STZ) to induce diabetes. The HFD+CCl4+STZ group showed more severe liver steatosis, hepatocyte ballooning, and regenerative nodules compared with other groups. Diabetes up-regulated inflammatory cytokine-associated genes and increased the M1/M2 macrophage ratios in the liver. Single-cell RNA sequencing analysis of nonparenchymal cells in the liver showed that diabetes reduced Kupffer cells and increased bone marrow-derived recruited inflammatory macrophages, such as Ly6Chi-RM. Diabetes globally reduced liver sinusoidal endothelial cells (LSECs). Furthermore, genes related to the receptor for advanced glycation end products (RAGE)/Toll-like receptor 4 (TLR4) were up-regulated in Ly6Chi-RM and LSECs in mice with diabetes, suggesting a possible role of RAGE/TLR4 signaling in the interaction between inflammatory macrophages and LSECs. This study established a novel diabetic steatohepatitis model using a combination of HFD, CCl4, and STZ. Diabetes exacerbated steatosis, hepatocyte ballooning, fibrosis, regenerative nodule formation, and the macrophage M1/M2 ratios triggered by HFD and CCl4. Single-cell RNA sequencing analysis indicated that diabetes activated inflammatory macrophages and impairs LSECs through the RAGE/TLR4 signaling pathway. These findings open avenues for discovering novel therapeutic targets for diabetic steatohepatitis.

Panaxydol extracted from Panax ginseng inhibits NLRP3 inflammasome activation to ameliorate NASH-induced liver injury

Activation of NOD-like receptor protein 3 (NLRP3) inflammasome exacerbates liver inflammation and fibrosis in nonalcoholic steatohepatitis (NASH), suggesting that development of inflammasome inhibitor can become leading candidate to ameliorate NASH. Panax ginseng (P. ginseng) contains numerous bioactive natural components to reduce inflammation. This study aims to identify inhibitory components of P. ginseng for NLRP3 inflammasome activation. We separated polar and non-polar fractions of P. ginseng and tested modulation of NLRP3 inflammasome, and then identified pure component for inflammasome inhibitor which ameliorates diet-induced NASH. Non-polar P. ginseng fractions obtained from ethyl acetate solvent attenuated IL-1β secretion and expression of active caspase-1. We revealed that panaxydol (PND) is pure component to inhibit NLRP3 inflammasome activation. PND blocked inflammasome cytokines release, pyroptotic cell death, caspase-1 activation and specking of inflammasome complex. Inhibitory effect of PND was specific to NLRP3-dependent pathway via potential interaction with ATP binding motif of NLRP3. Moreover, in vivo studies showed that PND plays beneficial roles to reduce tissue inflammations through disruption of NLRP3 inflammasome and to ameliorate the development of NASH. These results provide new insight of natural products, panaxydol, for NLRP3 inflammasome inhibitor and could offer potential therapeutic candidate for reliving NASH.

Dipeptedyl peptidase-4 (DPP-4) inhibitor downregulates HMGB1/TLR4/NF-κB signaling pathway in a diabetic rat model of non-alcoholic fatty liver disease

CONTEXT

Inflammatory and immune pathways play a crucial role in the pathophysiology of non-alcoholic fatty liver disease (NAFLD). Sitagliptin blocks the dipeptidyl peptidase-4 (DPP-4) enzyme, mechanisms that alter inflammatory pathways and the innate immune system, and by which Sitagliptin affects the pathogenesis of NAFLD weren't previously discussed.

OBJECTIVE

This study aims to understand the interaction between Sitagliptin and innate immune response in order to meliorate NAFLD.

METHODS

Thirty- two Wistar male albino rats were categorised into four groups. Rats have received a standard diet or a high-fat diet either with or without Sitagliptin. Serum HMGB1, protein and mRNA expressions of hepatic TLR4 and NF-κB, inflammatory cytokines, and histopathological changes were analysed.

RESULTS

An ameliorative action of Sitagliptin in NAFLD was demonstrated via decreasing HMGB1-mediated TLR4/NF-κB signalling in order to suppress inflammation and reduce insulin resistance.

CONCLUSION

Sitagliptin may in fact prove to be a beneficial therapeutic intervention in NAFLD.

New therapeutic approaches against pulmonary fibrosis

Pulmonary fibrosis is the end-stage change of a large class of lung diseases characterized by the proliferation of fibroblasts and the accumulation of a large amount of extracellular matrix, accompanied by inflammatory damage and tissue structure destruction, which also shows the normal alveolar tissue is damaged and then abnormally repaired resulting in structural abnormalities (scarring). Pulmonary fibrosis has a serious impact on the respiratory function of the human body, and the clinical manifestation is progressive dyspnea. The incidence of pulmonary fibrosis-related diseases is increasing year by year, and no curative drugs have appeared so far. Nevertheless, research on pulmonary fibrosis have also increased in recent years, but there are no breakthrough results. Pathological changes of pulmonary fibrosis appear in the lungs of patients with coronavirus disease 2019 (COVID-19) that have not yet ended, and whether to improve the condition of patients with COVID-19 by means of the anti-fibrosis therapy, which are the questions we need to address now. This review systematically sheds light on the current state of research on fibrosis from multiple perspectives, hoping to provide some references for design and optimization of subsequent drugs and the selection of anti-fibrosis treatment plans and strategies.

Hypo-osmolarity induces apoptosis resistance via TRPV2-mediated AKT-Bcl-2 pathway

In cirrhosis, several molecular alterations such as resistance to apoptosis could accelerate carcinogenesis. Recently, mechanotransduction has been attracting attention as one of the causes of these disturbances. In patients with cirrhosis, the serum sodium levels progressively decrease in the later stage of cirrhosis, and hyponatremia leads to serum hypo-osmolality. Since serum sodium levels in patients with cirrhosis with liver cancer are inversely related to cancer's number, size, stage, and cumulative survival, we hypothesized that hypo-osmolality-induced mechanotransduction under cirrhotic conditions might contribute to oncogenesis and/or progression of hepatocellular carcinoma (HCC). In this study, we adjusted osmosis of culture medium by changing the sodium chloride concentration and investigated the influence of hypotonic conditions on the apoptosis resistance of an HCC cell line, HepG2, using a serum-deprivation-induced apoptosis model. By culturing the cells in a serum-free medium, the levels of an antiapoptotic protein Bcl-2 were downregulated. In contrast, the hypotonic conditions caused apoptosis resistance by upregulation of Bcl-2. Next, we examined which pathway was involved in the apoptosis resistance. Hypotonic conditions enhanced AKT signaling, and constitutive activation of AKT in HepG2 cells led to upregulation of Bcl-2. Moreover, we revealed that the enhancement of AKT signaling was caused by intracellular calcium influx via a mechanosensor, TRPV2. Our findings suggested that hyponatremia-induced serum hypotonic in patients with cirrhosis promoted the progression of hepatocellular carcinoma.NEW & NOTEWORTHY Our study first revealed that hypo-osmolarity-induced mechanotransduction enhanced calcium-mediated AKT signaling via TRPV2 activation, resulting in contributing to apoptosis resistance. The finding indicates a possible view that liver cirrhosis-induced hyponatremia promotes hepatocellular carcinogenesis.

Utility of Human Relevant Preclinical Animal Models in Navigating NAFLD to MAFLD Paradigm

Fatty liver disease is an emerging contributor to disease burden worldwide. The past decades of work established the heterogeneous nature of non-alcoholic fatty liver disease (NAFLD) etiology and systemic contributions to the pathogenesis of the disease. This called for the proposal of a redefinition in 2020 to that of metabolic dysfunction-associated fatty liver disease (MAFLD) to better reflect the current understanding of the disease. To date, several clinical cohort studies comparing NAFLD and MAFLD hint at the relevancy of the new nomenclature in enriching for patients with more severe hepatic injury and extrahepatic comorbidities. However, the underlying systemic pathogenesis is still not fully understood. Preclinical animal models have been imperative in elucidating key biological mechanisms in various contexts, including intrahepatic disease progression, interorgan crosstalk and systemic dysregulation. Furthermore, they are integral in developing novel therapeutics against MAFLD. However, substantial contextual variabilities exist across different models due to the lack of standardization in several aspects. As such, it is crucial to understand the strengths and weaknesses of existing models to better align them to the human condition. In this review, we consolidate the implications arising from the change in nomenclature and summarize MAFLD pathogenesis. Subsequently, we provide an updated evaluation of existing MAFLD preclinical models in alignment with the new definitions and perspectives to improve their translational relevance.

S100 Proteins in Fatty Liver Disease and Hepatocellular Carcinoma

Non-alcoholic fatty liver disease (NAFLD) is a highly prevalent and slow progressing hepatic pathology characterized by different stages of increasing severity which can ultimately give rise to the development of hepatocellular carcinoma (HCC). Besides drastic lifestyle changes, few drugs are effective to some extent alleviate NAFLD and HCC remains a poorly curable cancer. Among the deregulated molecular mechanisms promoting NAFLD and HCC, several members of the S100 proteins family appear to play an important role in the development of hepatic steatosis, non-alcoholic steatohepatitis (NASH) and HCC. Specific members of this Ca²⁺-binding protein family are indeed significantly overexpressed in either parenchymal or non-parenchymal liver cells, where they exert pleiotropic pathological functions driving NAFLD/NASH to severe stages and/or cancer development. The aberrant activity of S100 specific isoforms has also been reported to drive malignancy in liver cancers. Herein, we discuss the implication of several key members of this family, e.g., S100A4, S100A6, S100A8, S100A9 and S100A11, in NAFLD and HCC, with a particular focus on their intracellular versus extracellular functions in different hepatic cell types. Their clinical relevance as non-invasive diagnostic/prognostic biomarkers for the different stages of NAFLD and HCC, or their pharmacological targeting for therapeutic purpose, is further debated.

Discovery and evaluation of phenacrylanilide derivatives as novel potential anti-liver fibrosis agents

Liver fibrosis is characterized by the excessive deposition of extracellular matrix components and results from chronic liver injury. At present, there is no approved drug for the treatment of liver fibrosis by the Food and Drug Administration. Here, we have reported a series of novel compounds with phenacrylanilide scaffolds that potently inhibit the transfer growth factor β1 (TGF-β1)-induced activation of LX-2, a hepatic stellate cell (HSC) line. Among them, compound 42 suppressed TGF-β1-induced upregulation of fibrotic markers (α-SMA and fibronectin) and showed excellent safety in vitro. Furthermore, in a carbon tetrachloride (CCl₄) -induced liver fibrosis model, 42 at a dose of 30 mg/kg/day through oral administration for 3 weeks effectively improved liver function, restored damaged liver structures, and reduced collagen deposition, with a greater effect than Tranilast. In addition, epithelial-mesenchymal transition (EMT) is inhibited by compound 42 in the process of fibrosis. Meanwhile, the imbalanced immune microenvironment could also be effectively reversed. More interestingly, compound 42 prolongs the survival of CCl₄ mice and ameliorates CCl₄-induced injury to spleen, kidney, lung and heart. Altogether, these results suggest that 42 could be a potential drug candidate for the treatment of liver fibrosis.

Adipose Tissue Inflammation and Pulmonary Dysfunction in Obesity

Obesity is a chronic disease caused by an excess of adipose tissue that may impair health by altering the functionality of various organs, including the lungs. Excessive deposition of fat in the abdominal area can lead to abnormal positioning of the diaphragm and consequent reduction in lung volume, leading to a heightened demand for ventilation and increased exposure to respiratory diseases, such as chronic obstructive pulmonary disease, asthma, and obstructive sleep apnoea. In addition to mechanical ventilatory constraints, excess fat and ectopic deposition in visceral depots can lead to adipose tissue dysfunction, which promotes metabolic disorders. An altered adipokine-secretion profile from dysfunctional adipose tissue in morbid obesity fosters systemic, low-grade inflammation, impairing pulmonary immune response and promoting airway hyperresponsiveness. A potential target of these adipokines could be the NLRP3 inflammasome, a critical component of the innate immune system, the harmful pro-inflammatory effect of which affects both adipose and lung tissue in obesity. In this review, we will investigate the crosstalk between adipose tissue and the lung in obesity, highlighting the main inflammatory mediators and novel therapeutic targets in preventing pulmonary dysfunction.

NLRP3 and pyroptosis blockers for treating inflammatory diseases

The nucleotide-binding oligomerization domain, leucine-rich repeat and pyrin domain-containing protein 3 (NLRP3) inflammasome has emerged as a key mediator of pathological inflammation in many diseases and is an exciting drug target. Here, we review the molecular basis of NLRP3 inhibition by drug-like small molecules under development as novel therapeutics. We also summarize recent strategies to block pyroptosis as a novel approach to suppress chronic inflammation. Major recent developments in this area include the elucidation of mechanisms of action (MoAs) by which small molecules block NLRP3 inflammasome assembly and gasdermin D (GSDMD)-induced pyroptosis. We also discuss the status of clinical trials using agents that block specific components of the NLRP3 pathway, including their potential clinical applications for the treatment of many diseases.

Chymase as a Possible Therapeutic Target for Amelioration of Non-Alcoholic Steatohepatitis

The development and progression of non-alcoholic steatohepatitis (NASH) are linked to oxidative stress, inflammation, and fibrosis of the liver. Chymase, a chymotrypsin-like enzyme produced in mast cells, has various enzymatic actions. These actions include activation of angiotensin II, matrix metalloproteinase (MMP)-9, and transforming growth factor (TGF)-β, which are associated with oxidative stress, inflammation, and fibrosis, respectively. Augmentation of chymase activity in the liver has been reported in various NASH models. Generation of hepatic angiotensin II and related oxidative stress is upregulated in NASH but attenuated by treatment with a chymase inhibitor. Additionally, increases in MMP-9 and accumulation of inflammatory cells are observed in NASH but are decreased by chymase inhibitor administration. TGF-β and collagen I upregulation in NASH is also attenuated by chymase inhibition. These results in experimental NASH models demonstrate that a chymase inhibitor can effectively ameliorate NASH via the reduction of oxidative stress, inflammation, and fibrosis. Thus, chymase may be a therapeutic target for amelioration of NASH.

Erica multiflora extract rich in quercetin-3-O-glucoside and kaempferol-3-O-glucoside alleviates high fat and fructose diet-induced fatty liver disease by modulating metabolic and inflammatory pathways in Wistar rats

The wide morbidity of obesity has heightened interest in providing natural and safe compounds to maintain optimal health. The present study was designed to determine the chemical constituents and the effects of methanol leaf extract from Erica multiflora (M-EML) on mitigating high-fat and high-fructose diet (HFFD)-induced metabolic syndrome (MS). LC-MS/MS characterization of M-EML allowed the identification of 14 secondary metabolites and showed that quercetin-3-O-glucoside and kaempferol-3-O-glucoside were the main compounds of our extract. In the in vivo study, the oral administration of M-EML (250 mg/kg) during the last 4 weeks of the experimentation alleviated HFFD-induced obesity, insulin resistance (IR) and cardiovascular diseases. Thus, M-EML treatment significantly normalized body and liver weight, allowed to a sharp decline in plasma levels of TC, TG and LDL-c by 32%, 35% and 66%, respectively. Moreover, hepatic enzymes, total and direct bilirubin, lipase and uric acid levels have been diminished in treated group. Histopathology of the liver confirmed the changes induced by HFFD and the hepatoprotective effect of M-EML. The supply of M-EML reduced NO production and cellular lysosomal enzyme activity by 44% and 60%, respectively compared to HFFD. Besides, M-EML showed decreased pro-inflammatory cytokines levels (259.5±47.35 pg/ml and 56.08±1.56 pg/ml) of TNF-α and IL-6, respectively. In addition, M-EML reduced liver malondialdehyde (MDA) content and enhanced superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities. In contrast, these enzymatic activities have been disrupted in HFFD rats. Overall, M-EML prevented obesity through the modulation of metabolic syndrome, reducing inflammation and promoting antioxidant enzymes activities.

Histopathological changes and onset of severe hepatic steatosis in rats fed a choline-free diet

Hepatic steatosis significantly increases morbidity and mortality associated with major liver surgery. Several rodent models of hepatic steatosis have been previously reported, which aimed to investigate the effect of various pharmaceutical agents and interventional procedures on the pathophysiology of steatotic liver. The aim of the present study was to investigate the time frame of severe hepatic steatosis in rats after they were fed a choline-free diet and any associated histopathological changes. The duration of feeding with a choline-free diet required to develop severe hepatic steatosis was investigated in Wistar rats. The severity of hepatic steatosis in liver specimens was evaluated at 8, 10, 12 and 14 weeks following the onset of the choline-free diet. Comparisons were made with rats receiving standardized laboratory food. Feeding rats for 12–13 weeks with a choline-free diet led to 66% fatty liver infiltration, which exceeded 68% after 14 weeks. Prior to 8 weeks, the fatty infiltration reached 43%, with a gradual increase revealing a stronger rate from 8–12 weeks and a gradual decline after 14 weeks. At 12–13 weeks the fatty infiltration was considered representative of severe hepatic steatosis. Macrovesicular fatty infiltration revealed a significant increase at a steady rate between 8 and 14 weeks, with evidence of the onset of lobular inflammation and steatohepatitis after 14 weeks of feeding with the choline-free diet. Microvesicular fatty infiltration demonstrated a lower growth rate between 8 and 12 weeks while maintaining a steady rate between 12 and 14 weeks. Mixed fatty infiltration maintained its steady rate of hepatic parenchyma from 8.8–9.5%. Rats fed with the standard laboratory diet did not demonstrate fatty infiltration >4.5%, so they did not develop hepatic steatosis. Developing an ideal model of hepatic steatosis is a particular challenge. The findings of the present study indicate that severe hepatic steatosis in rodents may lead to the development of steatohepatitis after feeding with a choline-free diet for at least 14 weeks. This model is of particular interest in experimental liver surgery and associated surgical maneuvers, and is easily reproducible.

Chymase Inhibitor as a Novel Therapeutic Agent for Non-alcoholic Steatohepatitis

Non-alcoholic steatohepatitis (NASH) is characterized by inflammation and fibrosis, in addition to steatosis, of the liver, but no therapeutic agents have yet been established. The mast cell protease chymase can generate angiotensin II, matrix metalloproteinase-9 and transforming growth factor-β, all of which are associated with liver inflammation or fibrosis. In animal models of NASH, augmented chymase has been observed in the liver. In histological analysis, chymase inhibitor prevented hepatic steatosis, inflammation, and fibrosis. Chymase inhibitor also attenuated the augmentation of angiotensin II, matrix metalloproteinase-9, and transforming growth factor-β observed in the liver of NASH. Oxidative stress, inflammatory markers, and collagen were attenuated by chymase inhibition. Moreover, chymase inhibitor showed a mitigating effect on established NASH, and survival rates were significantly increased by treatment with chymase inhibitor. In this review, we propose that chymase inhibitor has potential as a novel therapy for NASH.

A novel hamster nonalcoholic steatohepatitis model induced by a high-fat and high-cholesterol diet

Nonalcoholic steatohepatitis (NASH), in which there is steatosis and fibrosis in the liver, is linked to metabolic syndrome and progresses to hepatic cirrhosis. In this study, a novel hamster NASH model derived from metabolic syndrome was made using hamsters. Hamsters were fed a normal or a high-fat and high-cholesterol (HFC) diet for 12 weeks. Body weight and the ratio of liver weight to body weight were significantly greater in HFC diet-fed hamsters than in normal diet-fed hamsters. Triglyceride, low-density lipoprotein cholesterol, and glucose levels in blood were significantly increased in HFC diet-fed hamsters, and blood pressure also tended to be high, suggesting that the HFC diet-fed hamsters developed metabolic syndrome. Hepatic steatosis and fibrosis were observed in liver sections of HFC diet-fed hamsters, as in patients with NASH, but they were not seen in normal diet-fed hamsters. Chymase generates angiotensin II and transforming growth factor (TGF)-β, both of which are related to hepatic steatosis and fibrosis, and a significant augmentation of chymase activity was observed in livers from HFC diet-fed hamsters. Both angiotensin II and TGF-β were also significantly increased in livers of HFC diet-fed hamsters. Thus, HFC diet-fed hamsters might develop metabolic syndrome-derived NASH that clinically resembles that in NASH patients.

Role of physical exercise on hepatic insulin, glucocorticoid and inflammatory signaling pathways in an animal model of non-alcoholic steatohepatitis

AIMS

Pro-inflammatory mediators, glucocorticoids and transforming growth factor (TGF)-β are implicated in the pathogenesis of non-alcoholic steatohepatitis (NASH)-related insulin resistance. As physical activity is beneficial against NASH, we analyzed the voluntary physical activity (VPA) and endurance training (ET) (preventive and therapeutic strategies) effects on hepatic insulin, pro-inflammatory and glucocorticoid signaling regulators/mediators in high-fat (Lieber-DeCarli) diet (HFD)-induced NASH.

MAIN METHODS

Adult male Sprague-Dawley rats were divided in standard diet (SD) or HFD, with sedentary, VPA and ET animals in both diet regimens. Plasma glucose and insulin concentrations were analyzed; plasma insulin sensitivity index (ISI) was calculated. Hepatic insulin, pro-inflammatory and glucocorticoid signaling regulators/mediators were evaluated by Western blot or reverse transcriptase-PCR.

KEY FINDINGS

ET improved ISI in both diet regimens. HFD-feeding increased interleukin-1β and induced a similar pattern on interleukin-6 and TGF-β, which were globally reduced by physical exercise. ET decreased HFD leukemia inhibitory factor level, SD+VPA animals presenting higher values than HFD+VPA animals. HFD increased the ratio of IRS-1(Ser307)/total IRS-1, which was completely mitigated by physical exercise. Physical exercise reduced total ERK and JNK (total and activated) expression in HFD. In SD vs. HFD, VPA presented higher activated JNK and ET presented higher total JNK. Generally, in HFD, the ratio (activated/total) of AKT, and each separately, decreased with exercise and also for activated AKT in SD. Overall, in both diets, exercise reduced 11β-hydroxysteroid dehydrogenase type 1. ET increased glucocorticoid receptor and reduced PTP1B in HFD.

SIGNIFICANCE

Physical exercise mitigates the expression of pro-inflammatory mediators and positively modulates insulin and glucocorticoid signaling in NASH.

Tranilast: a review of its therapeutic applications

Tranilast (N-[3',4'-dimethoxycinnamoyl]-anthranilic acid) is an analog of a tryptophan metabolite. Initially, tranilast was identified as an anti-allergic agent, and used in the treatment of inflammatory diseases, such as bronchial asthma, atypical dermatitis, allergic conjunctivitis, keloids and hypertrophic scars. Subsequently, the results showed that it could be also effective in the management of a wide range of conditions. The beneficial effects of tranilast have also been seen in a variety of disease states, such as fibrosis, proliferative disorders, cancer, cardiovascular problems, autoimmune disorders, ocular diseases, diabetes and renal diseases. Moreover, several trials have shown that it has very low adverse effects and it is generally well tolerated by patients. In this review, we have attempted to accurately summarize previously published studies relating to the use of tranilast for a range of disorders and discuss the drug's possible mode of action. The major mode of the drug's efficacy appears to be the suppression of the expression and/or action of the TGF-β pathway, but the drug affects other factors as well. The findings presented in this review demonstrate the potential of tranilast for the control of a vast array of pathological situations, furthermore, it is a prescribed drug without severe side effects.

Increased SSeCKS expression in rat hepatic stellate cells upon activation in vitro and in vivo

Recent reports suggest that src suppressed c kinase substrates (SSeCKS) are early inflammatory response protein. However, there is only scarce knowledge on the functional role of SSeCKS in liver under conditions of acute inflammation. In the present study, we investigated SSeCKS expression in liver after administration of carbon tetrachloride (CCl4) in rats and in isolated primary hepatic stellate cells (HSCs) upon activation on a plastic dish. We found that SSeCKS mRNA was hardly detectable in healthy liver tissue and further increased in carbon tetrachloride-mediated acute liver failure. SSeCKS protein expression was mainly found in hepatic stellate cells. In vitro, SSeCKS expression in activated rat HSCs was dramatically increased. The upregulation of SSeCKS protein expression in rat HSCs during activation in vitro and in vivo suggested the possibility of SSeCKS, an important part of function of the activated HSCs, perhaps through modulation of liver regeneration or formation of liver fibrosis after various injuries.

Experimental models of non-alcoholic fatty liver disease in rats

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the Western world, and it persists at a high prevalence. NAFLD is characterised by the accumulation of triglycerides in the liver and includes a spectrum of histopathological findings, ranging from simple fatty liver through non-alcoholic steatohepatitis (NASH) to fibrosis and ultimately cirrhosis, which may progress to hepatocellular carcinoma. The pathogenesis of NAFLD is closely related to the metabolic syndrome and insulin resistance. Understanding the pathophysiology and treatment of NAFLD in humans has currently been limited by the lack of satisfactory animal models. The ideal animal model for NAFLD should reflect all aspects of the intricate etiopathogenesis of human NAFLD and the typical histological findings of its different stages. Within the past several years, great emphasis has been placed on the development of an appropriate model for human NASH. This paper reviews the widely used experimental models of NAFLD in rats. We discuss nutritional, genetic and combined models of NAFLD and their pros and cons. The choice of a suitable animal model for this disease while respecting its limitations may help to improve the understanding of its complex pathogenesis and to discover appropriate therapeutic strategies. Considering the legislative, ethical, economical and health factors of NAFLD, animal models are essential tools for the research of this disease.

Protection against ovariectomy-induced bone loss by tranilast

Background

Tranilast (N-(3′,4′-dimethoxycinnamonyl) anthranilic acid) has been shown to be therapeutically effective, exerting anti-inflammatory and anti-oxidative effects via acting on macrophage. We hypothesized that Tranilast may protect against oxidative stress-induced bone loss via action in osteoclasts (OCs) that shares precursors with macrophage.

Methodology and Principal Findings

To elucidate the role of Tranilast, ovariectomy (OVX)-induced bone loss in vivo and OC differentiation in vitro were evaluated by µCT and tartrate-resistant acid phosphatase staining, respectively. Oral administration of Tranilast protected against OVX-induced bone loss with decreased serum level of reactive oxygen species (ROS) in mice. Tranilast inhibited OC formation in vitro. Decreased osteoclastogenesis by Tranilast was due to a defect of receptor activator of nuclear factor-κB ligand (RANKL) signaling, at least partly via decreased activation of nuclear factor-κB and reduced induction and nuclear translocation of nuclear factor of activated T cells, cytoplasmic 1 (or NFAT2). Tranilast also decreased RANKL-induced a long lasting ROS level as well as TGF-β to inhibit osteoclastogenesis. Reduced ROS caused by Tranilast was due to the induction of ROS scavenging enzymes (peroxiredoxin 1, heme oxygenase-1, and glutathione peroxidase 1) as well as impaired ROS generation.

Conclusions/Significance

Our data suggests the therapeutic potential of Tranilast for amelioration of bone loss and oxidative stress due to loss of ovarian function.

Time course of the development of nonalcoholic Fatty liver disease in the Otsuka long-evans Tokushima Fatty rat

Nonalcoholic fatty liver disease (NAFLD) is considered a hepatic manifestation of metabolic syndrome. In this study, we investigated histological and biochemical changes in NAFLD and the gene expression involving de novo lipogenesis in Otsuka Long-Evans Tokushima fatty (OLETF) rats. We used OLETF rats and Long-Evans Tokushima Otsuka (LETO) rats as animal models of NAFLD and as controls, respectively. Consistent observations were made at 4-week intervals up to 50 weeks of age, and all rats were fed ad libitum with standard food. Biochemical and histological changes were observed, and gene expression involved in de novo lipogenesis was measured using real-time polymerase chain reactions. As a results hepatic micro- and macrovesicular steatosis and hepatocyte ballooning were evident in the OLETF rats at 22-38 weeks of age but disappeared after 42 weeks; no fibrosis or collagen deposition was observed. Gene expression involved in de novo lipogenesis followed a pattern similar to that of the histological changes. In conclusion, in the absence of dietary manipulation, hepatic steatosis in OLETF rats is evident at 22-38 weeks and declines after 42 weeks. Therefore, OLETF rats at 22-38 weeks are recommended as animal models of hepatic steatosis.

Role of Pin1 protein in the pathogenesis of nonalcoholic steatohepatitis in a rodent model

Nonalcoholic steatohepatitis (NASH) is a disorder characterized by simultaneous fat accumulation and chronic inflammation in the liver. In this study, Pin1 expression was revealed to be markedly increased in the livers of mice with methionine choline-deficient (MCD) diet-induced NASH, a rodent model of NASH. In addition, Pin1 KO mice were highly resistant to MCD-induced NASH, based on a series of data showing simultaneous fat accumulation, chronic inflammation, and fibrosis in the liver. In terms of Pin1-induced fat accumulation, it was revealed that the expression levels of peroxisome proliferator-activated receptor α and its target genes were higher in the livers of Pin1 KO mice than in controls. Thus, resistance of Pin1 KO mice to hepatic steatosis is partially attributable to the lack of Pin1-induced down-regulation of peroxisome proliferator-activated receptor α, although multiple other mechanisms are apparently involved. Another mechanism involves the enhancing effect of hematopoietic Pin1 on the expressions of inflammatory cytokines such as tumor necrosis factor and monocyte chemoattractant protein 1 through NF-κB activation, eventually leading to hepatic fibrosis. Finally, to distinguish the roles of hematopoietic or nonhematopoietic Pin1 in NASH development, mice lacking Pin1 in either nonhematopoietic or hematopoietic cells were produced by bone marrow transplantation between wild-type and Pin1 KO mice. The mice having nonhematopoietic Pin1 exhibited fat accumulation without liver fibrosis on the MCD diet. Thus, hepatic Pin1 appears to be directly involved in the fat accumulation in hepatocytes, whereas Pin1 in hematopoietic cells contributes to inflammation and fibrosis. In summary, this is the first study to demonstrate that Pin1 plays critical roles in NASH development. This report also raises the possibility that hepatic Pin1 inhibition to the appropriate level might provide a novel therapeutic strategy for NASH.

Black tea prevents high fat diet-induced non-alcoholic steatohepatitis

The chemoprotective actions of aqueous black tea extract (BTE) against high-fat diet (HFD) (60%)-induced non-alcoholic steatohepatitis (NASH) were examined in Wistar rats of both sexes. The results indicated that the HFD rats had higher concentrations of serum glucose, cholesterol, triglycerides, low-density lipoprotein, very low-density lipoprotein, high-density lipoprotein and bilirubin than the corresponding control rats. The enzymes serum aspartate aminotransferase and alanine aminotransferase, which are indicators of liver function, also exhibited higher levels of activity in HFD rats. BTE extract supplementation was found to correct such steatohepatitis-linked biochemical changes. HFD-induced steatohepatitis was associated with substantial pro-oxidant conditions in rat liver, as evidenced by the higher content of malondialdehyde, nitric oxide production and glutathione depletion, with a concomitant decrease in liver antioxidant status caused by reducing superoxide dismutase and catalase activity. In addition, rats with steatohepatitis showed a significantly higher expression of inducible nitric oxide synthase, caspase-3 activity and DNA fragmentation. BTE reversed the changes in the pro-oxidant and antioxidant status of the liver, and protected against apoptotic, cytogenetic and hepatocellular damage. In summary, these data suggest that nutritional support with antioxidants may be useful in preventing oxidative damage and the progression of NASH.

Silymarin suppresses hepatic stellate cell activation in a dietary rat model of non-alcoholic steatohepatitis: analysis of isolated hepatic stellate cells

Non-alcoholic steatohepatitis (NASH) is characterized by hepatocellular injury and initial fibrosis severity has been suggested as an important prognostic factor of NASH. Silymarin was reported to improve carbon tetrachloride-induced liver fibrosis and reduce the activation of hepatic stellate cells (HSC). We investigated whether silymarin could suppress the activation of HSCs in NASH induced by methionine- and choline-deficient (MCD) diet fed to insulin-resistant rats. NASH was induced by feeding MCD diet to obese diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats. Non-diabetic Long-Evans Tokushima Otsuka (LETO) rats were fed with standard chow and served as the control. OLETF rats were fed on either standard laboratory chow, or MCD diet or MCD diet mixed with silymarin. Histological analysis of the liver showed improved non-alcoholic fatty liver disease (NAFLD) activity score in silymarin-fed MCD-induced NASH. Silymarin reduced the activation of HSCs, evaluated by counting α-smooth muscle actin (SMA)-positive cells and measuring α-SMA mRNA expression in the liver lysates as well as in HSCs isolated from the experimental animals. Although silymarin decreased α₁-procollagen mRNA expression in isolated HSCs, the anti-fibrogenic effect of silymarin was not prominent so as to show significant difference under histological analysis. Silymarin increased the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and decreased tumor necrosis factor (TNF)-α mRNA expression in the liver. Our study suggested that the possible protective effect of silymarin in diet induced NASH by suppressing the activation of HSCs and disturbing the role of the inflammatory cytokine TNF-α.

Establishment of a standardized liver fibrosis model with different pathological stages in rats

Objective. To establish a standardized animal model for liver fibrosis with the same assessment criteria for liver fibrosis studies that have been established on a unified platform. Methods. The standardized liver fibrosis model was established using Sprague-Dawley (SD) rats that either received an intraperitoneal injection of carbon tetrachloride (CCl(4)) in small dosages or ingested an ethanol solution. Results. The definite corresponding rules among modeling of different weeks and corresponding serology indices as well as different pathological staging can be observed by modeling with small dosages and slow, individualized, and combined administrations. Conclusion. This method can be used for the standardized establishment of a liver fibrosis model in rats across 5 pathological stages, ranging from S0 to S4, with a high success rate (89.33%) and low death rate (17.3%) because of the application of multiple hypotoxic chemicals for modeling. We refer to the criteria of Histological Grading and Staging of Chronic Hepatitis for Fibrosis established by the 10th World Digestive Disease Academic Conference in Los Angeles in September 1994 (revised in November 2000).

Fatty liver as a consequence and cause of insulin resistance: lessons from type 2 diabetic liver

Obesity is less common in the Asian population, but Asian people may be susceptible to obesity-associated metabolic dysregulation. Accumulating evidence suggests that insulin resistance is closely associated with ectopic fat accumulation in the liver. Whether this correlation is due to a causal relationship between the conditions has long been the subject of debate. Insulin resistance and type 2 diabetes affects liver pathology, typically leading to nonalcoholic fatty liver disease (NAFLD) by dynamically altering the hepatic genes involved in glucose and lipid metabolism. Conversely, how overnutrition induces hepatic insulin resistance has been studied intensively, and has been shown to involve excessive energy flux into mitochondria, toxic lipids, reactive oxygen species, and hepatokines. In this review, we focus on NAFLD both as a consequence and as a cause of insulin resistance through lessons learned from the liver of patients with type 2 diabetes.

Treatment of nonalcoholic fatty liver disease in adults and children: a closer look at the arsenal

Nonalcoholic fatty liver disease encompasses a spectrum of disease from asymptomatic steatosis, with or without elevated aminotransferases, to cirrhosis with relative complications and hepatocellular carcinoma. Owing to the increasing prevalence of nonalcoholic fatty liver disease and the potential for nonalcoholic steatohepatitis to progress to cirrhosis and liver-related mortality, more research has been focused on therapy of this important liver disease over the last two decades. To date, weight loss and physical activity represent the cornerstone of treatment, with interventions being limited to subjects at risk of disease progression, but the type of treatment remains a matter of debate. A few medications have shown promising results in preliminary pilot studies, but few agents have been tested rigorously. Today, multiple therapeutic approaches are considered the way to go in treating nonalcoholic steatohepatitis patients. In this paper we review the status of current and emerging therapeutic strategies for children and adult patients with nonalcoholic steatohepatitis.

Targets of chymase inhibitors

INTRODUCTION

Chymase converts angiotensin I to angiotensin II and it can also convert precursors of TGF-β and MMP-9 to their active forms. Therefore, diseases related to angiotensin II TGF-β, and MMP-9 could potentially be treated with chymase inhibitors.

AREAS COVERED

This review discusses the appropriate targets and safety of chymase inhibitors. Six diseases with notable mortality or morbidity as targets of chymase inhibitors are focused on; abdominal aortic aneurysms (AAAs), nephropathy and retinopathy, cardiomyopathy, nonalcoholic steatohepatitis (NASH), organ fibrosis and intestinal diseases.

EXPERT OPINION

If chymase inhibition proves to be a useful strategy for the attenuation of angiotensin II, TGF-β and MMP-9 in vivo, the application of chymase inhibitors is likely to become widespread in various diseases in the clinical setting. Chymase inhibitors are anticipated not to interfere with the homeostasis of resting tissues, that is, those not affected by injury or inflammation.

Comparison of dietary control and atorvastatin on high fat diet induced hepatic steatosis and hyperlipidemia in rats

Background

Treatment with atorvastatin (ATO) or dietary control has been demonstrated to benefit patients with non-alcoholic fatty liver disease (NAFLD) and hyperlipidemia. However, little is known on whether combination of dietary control and ATO treatment could enhance the therapeutic effect.

Methods

We employed a rat model of NAFLD to examine the therapeutic efficacy of dietary control and/or ATO treatment. Sprague-Dawley rats were fed with normal chow diet as normal controls or with high fat diet (HFD) for 12 weeks to establish NAFLD. The NAFLD rats were randomized and continually fed with HFD, with normal chow diet, with HFD and treated with 30 mg/kg of ATO or with normal chow diet and treated with the same dose of ATO for 8 weeks. Subsequently, the rats were sacrificed and the serum lipids, aminotranferase, hepatic lipids, and liver pathology were characterized. The relative levels of fatty acid synthesis and β-oxidation gene expression in hepatic tissues were measured by quantitative real-time polymerase chain reaction (qRT-PCR). Hepatic expression of hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase was determined by Western blot assay.

Results

While continual feeding with HFD deteriorated NAFLD and hyperlipidemia, treatment with dietary control, ATO or ATO with dietary control effectively improved serum and liver lipid metabolism and liver function. In comparison with ATO treatment, dietary control or combined with ATO treatment significantly reduced the liver weight and attenuated the HFD-induced hyperlipidemia and liver steatosis in rats. Compared to ATO treatment or dietary control, combination of ATO and dietary control significantly reduced the levels of serum total cholesterol and low density lipoprotein cholesterol (LDL-C). However, the combination therapy did not significantly improve triglyceride and free fatty acid metabolism, hepatic steatosis, and liver function, as compared with dietary control alone.

Conclusions

ATO treatment effectively improved NAFLD-related hyperlipidemia and inhibited liver steatosis, accompanied by modulating the expression of genes for regulating lipid metabolism. ATO enhanced the effect of dietary control on reducing the levels of serum total cholesterol and LDL-C, but not triglyceride, free fatty acid and hepatic steatosis in HFD-induced fatty liver and hyperlipidemia in rats.

Involvement of microsomal triglyceride transfer protein in nonalcoholic steatohepatitis in novel spontaneous mouse model

BACKGROUND & AIMS

Nonalcoholic fatty liver disease (NAFLD) is currently recognized as a global health issue and encompasses a wide spectrum of entities, ranging from simple hepatic steatosis to nonalcoholic steatohepatitis (NASH). The lack of a spontaneous animal model of NASH, however, has hampered basic research in this field.

METHODS

We examined the hepatic lesions in the inbred Fatty Liver Shionogi (FLS) mouse, which exhibits type 2 diabetes, and investigated the molecular mechanism leading to NAFLD/NASH. Using vector-mediated hepatic expression of microsomal triglyceride transfer protein (MTP), a key molecule for very low density lipoprotein (VLDL) assembly and export, its contribution to the hepatic lesions as well as to glucose intolerance was examined.

RESULTS

The FLS mouse, maintained on normal chow, exhibited excessive hepatic triglyceride (TG) accumulation due to impaired VLDL secretion, and subsequently hepatic lesions comparable to NASH, with increased expression of inflammatory molecules as well as insulin resistance. Gene expression and Western blot analyses demonstrated reduced hepatic expression of MTP in the FLS mouse. Hepatic induction of MTP resulted in a reduction in hepatic TG accumulation, improvement of VLDL export, and amelioration of NASH-like lesions, as well as glucose intolerance.

CONCLUSIONS

These data suggest that the FLS mouse could serve as a spontaneous model of NASH with insulin resistance, and that reduced MTP is involved in the development of NASH, pointing towards MTP as a critical target for the prevention and treatment of NASH.

Inflammatory mediators and insulin resistance in obesity: role of nuclear receptor signaling in macrophages

Visceral obesity is coupled to a general low-grade chronic inflammatory state characterized by macrophage activation and inflammatory cytokine production, leading to insulin resistance (IR). The balance between proinflammatory M1 and antiinflammatory M2 macrophage phenotypes within visceral adipose tissue appears to be crucially involved in the development of obesity-associated IR and consequent metabolic abnormalities. The ligand-dependent transcription factors peroxisome proliferator activated receptors (PPARs) have recently been implicated in the determination of the M1/M2 phenotype. Liver X receptors (LXRs), which form another subgroup of the nuclear receptor superfamily, are also important regulators of proinflammatory cytokine production in macrophages. Disregulation of macrophage-mediated inflammation by PPARs and LXRs therefore underlies the development of IR. This review summarizes the role of PPAR and LXR signaling in macrophages and current knowledge about the impact of these actions in the manifestation of IR and obesity comorbidities such as liver steatosis and diabetic osteopenia.

From the metabolic syndrome to NAFLD or vice versa?

The metabolic syndrome encompasses metabolic and cardiovascular risk factors which predict diabetes and cardiovascular disease (CVD) better than any of its individual components. Nonalcoholic fatty liver disease (NAFLD) comprises a disease spectrum which includes variable degrees of simple steatosis (nonalcoholic fatty liver, NAFL), nonalcoholic steatohepatitis (NASH) and cirrhosis. NAFLD is the hepatic manifestation of the metabolic syndrome, with insulin resistance as the main pathogenetic mechanism. Recent data indicate that hyperinsulinemia is probably the consequence rather than cause of NAFLD and NAFLD can be considered an independent predictor of cardiovascular disease. Serum free fatty acids derived from lipolysis of visceral adipose tissue are the main source of hepatic triglycerides in NAFLD, although hepatic de novo lipogenesis and dietary fat supply contribute to the pathogenesis of NAFLD. Approximately 10-25% NAFLD patients develop NASH, the evolutive form of hepatic steatosis. Presumably in a genetically predisposed environment, this increased lipid overload overwhelms the oxidative capacity and reactive oxygen species are generated, leading to lipid peroxidation, cytokine induction, chemoattraction of inflammatory cells, hepatic stellate cell activation and finally fibrogenesis with extracellular matrix deposition. No currently available therapies for NAFLD and NASH exist. Recently nuclear receptors have emerged as key regulators of lipid and carbohydrate metabolism for which specific pharmacological ligands are available, making them attractive therapeutic targets for NAFLD and NASH.

Chymase inhibitor prevents the nonalcoholic steatohepatitis in hamsters fed a methionine- and choline-deficient diet

AIM

Mast cells may be involved in the pathogenesis of nonalcoholic steatohepatitis (NASH). The mast cell protease chymase contributes to the formation of angiotensin II and matrix metalloproteinase (MMP)-9, both of which are intimately involved in liver fibrosis. Therefore, we hypothesized that chymase plays an important role in the development of NASH.

METHODS

Hamsters were fed a methionine- and choline-deficient (MCD) diet for 8 weeks. These animals were divided into two groups and received either TY-51469 (1 mg/kg per day) or placebo. A third group was fed a normal diet as a control.

RESULTS

Total plasma bilirubin, triglycerides, and hyaluronic acid levels were significantly higher in the MCD diet-fed hamsters than in the normal diet-fed hamsters, but the levels were significantly lower in chymase inhibitor-treated MCD diet-fed hamsters than in placebo-treated MCD diet-fed hamsters. Using histological analysis, marked steatosis and fibrosis were observed in MCD diet-fed hamsters, but these changes were significantly attenuated by treatment with the chymase inhibitor. Increases in mast cells and chymase-positive cells were observed in the liver after the MCD diet, but the increases disappeared in the chymase inhibitor-treated group. The significant increase observed in chymase activity in liver tissue extract from the MCD diet-fed group was also reduced by treatment with the chymase inhibitor. Chymase inhibition significantly reduced not only angiotensin II expression but also matrix metallopeptidase 9 activity in MCD diet-fed hamsters.

CONCLUSION

These findings demonstrate that the mast cell protease chymase may play a crucial role in the development of NASH in hamsters.

Characterization of high-fat, diet-induced, non-alcoholic steatohepatitis with fibrosis in rats

An ideal animal model is necessary for a clear understanding of the etiology, pathogenesis, and mechanisms of human non-alcoholic steatohepatitis (NASH) and for facilitating the design of effective therapy for this condition. We aimed to establish a rat model of NASH with fibrosis by using a high-fat diet (HFD). Male Sprague-Dawley (SD) rats were fed a HFD consisting of 88 g normal diet, 10 g lard oil, and 2 g cholesterol. Control rats were fed normal diet. Rats were killed at 4, 8, 12, 16, 24, 36, and 48 weeks after HFD exposure. Body weight, liver weight, and epididymal fat weight were measured. Serum levels of fasting glucose, triglyceride, cholesterol, alanine aminotransferase (ALT), free fatty acids (FFA), insulin, and tumor necrosis factor-alpha (TNF-alpha) were determined. Hepatic histology was examined by H&E stain. Hepatic fibrosis was assessed by VG stain and immunohistochemical staining for transforming growth factor beta 1 (TGF-beta1), and alpha-smooth-muscle actin (alpha-SMA). The liver weight and liver index increased from week 4, when hepatic steatosis was also observed. By week 8, the body weight and epididymal fat weight started increasing, which was associated with increased serum levels of FFA, cholesterol, and TNF-alpha, as well as development of simple fatty liver. The serum ALT level increased from week 12. Steatohepatitis occurred from weeks 12 through 48. Apparent hepatic perisinosodial fibrosis did not occur until week 24, and progressed from week 36 to 48 with insulin resistance. Therefore, this novel model may be potentially useful in NASH study.

Histological course of nonalcoholic fatty liver disease in Japanese patients: tight glycemic control, rather than weight reduction, ameliorates liver fibrosis

OBJECTIVE

The goal of this study was to examine whether metabolic abnormalities are responsible for the histological changes observed in Japanese patients with nonalcoholic fatty liver disease (NAFLD) who have undergone serial liver biopsies.

RESEARCH DESIGN AND METHODS

In total, 39 patients had undergone consecutive liver biopsies. Changes in their clinical data were analyzed, and biopsy specimens were scored histologically for stage.

RESULTS

The median follow-up time was 2.4 years (range 1.0-8.5). Liver fibrosis had improved in 12 patients (30.7%), progressed in 11 patients (28.2%), and remained unchanged in 16 patients (41%). In a Cox proportional hazard model, decrease in A1C and use of insulin were associated with improvement of liver fibrosis independent of age, sex, and BMI. However, DeltaA1C was more strongly associated with the improvement of liver fibrosis than use of insulin after adjustment for each other (chi(2); 7.97 vs. 4.58, respectively).

CONCLUSIONS

Tight glycemic control may prevent histological progression in Japanese patients with NAFLD.

Novel crystalline solid dispersion of tranilast with high photostability and improved oral bioavailability

Tranilast (TL) is an anti-allergic agent and widely used in the clinical treatment of bronchial asthma, atopic rhinitis, atopic dermatitis and keloids. However, therapeutic potential of TL could be partly limited because of its poor solubility, bioavailability, and photostability. To overcome these drawbacks, crystalline solid dispersion of TL (CSD/TL) was prepared by wet-milling technique with aim of improving physicochemical and pharmacokinetic properties. Physicochemical properties of the formulations prepared were characterized by laser diffraction and dynamic light scattering for particle size analysis, scanning electron microscope for morphological analysis, and powder X-ray diffraction and differential scanning calorimetry for crystallinity assessment. TL particles in CSD/TL appeared to be crystalline with diameter of 122 nm, and CSD/TL exhibited marked improvement in the dissolution behavior as compared to crystalline TL. Under irradiation of UVA/B (250 W/m(2)), solution and amorphous solid dispersion of TL were found to be highly photodegradable, whereas high photochemical stability was seen in CSD/TL. After oral administration of CSD/TL, enhanced TL exposure was observed with increase of C(max) and AUC by 60- and 32-fold, respectively, as compared to crystalline TL. According to these observations, taken together with dissolution and pharmacokinetic behaviors, crystalline solid dispersion strategy would be efficacious to enhance bioavailability of TL with high photochemical stability.

Recent advances in nonalcoholic fatty liver disease

PURPOSE OF REVIEW

This review focuses on recent advances in the study of the epidemiology, pathogenesis, natural history and treatment of nonalcoholic fatty liver disease (NAFLD).

RECENT FINDINGS

Study of hepatic lipid metabolism with respect to the contribution of de-novo lipogenesis to hepatic steatosis and insulin resistance and the dysregulation of cellular adaptive response to stress, that is, the unfolded protein response has added to our current understanding of NAFLD. microRNA has recently emerged and has been shown to be differentially expressed in patients with nonalcoholic steatohepatitis. Its mechanism of action remains to be further explored. There is no proven pharmacotherapy for the treatment of NAFLD. Lifestyle intervention to achieve weight loss and increase exercise is persistently associated with improved liver histology. The diagnostic utility of noninvasive markers and imaging modalities in assessing fibrosis remains to be elucidated.

SUMMARY

The underlying mechanism and pathogenesis of NAFLD remain elusive. Although research effort has advanced the understanding of the natural history, pathogenesis and management of the disease, there is no proven therapy for this medical condition. At present, treatment concentrates on managing underlying metabolic risk factors.

Hepatic fibrosis

PURPOSE OF REVIEW

This review will summarize the most significant work that contributed to the understanding of liver fibrosis progression and resolution, which in turn has yielded new areas of therapeutic targeting.

RECENT FINDINGS

Liver fibrosis is the result of an imbalance between production and dissolution of extracellular matrix. Stellate cells, portal myofibroblasts, and bone marrow derived cells converge in a complex interaction with hepatocytes and immune cells to provoke scarring in response to liver injury. Uncovering the specific effects of growth factors on these cells, defining the interaction of different cell population during liver fibrosis and characterizing the genetic determinants of fibrosis progression will enable the discovery of new therapeutic approaches.

SUMMARY

The outcome of improved understanding of liver fibrosis process, especially the regulation and activation of stellate cells, is reflected in the development of new therapeutic strategies, which are validated in animal models.

Nonalcoholic fatty liver disease in type 2 diabetes mellitus

PURPOSE OF REVIEW

To increase awareness about the close interrelationship between nonalcoholic fatty liver disease and type 2 diabetes mellitus, and of recent diagnostic and treatment advances in the field.

RECENT FINDINGS

The perception of nonalcoholic fatty liver disease as an uncommon and benign condition is rapidly changing. Approximately 70% of persons with type 2 diabetes mellitus have a fatty liver and the disease follows a more aggressive course with necroinflammation and fibrosis (i.e. nonalcoholic steatohepatitis) in diabetes. New evidence suggests that it is not steatosis per se but the development of lipotoxicity-induced mitochondrial dysfunction and activation of inflammatory pathways that leads to progressive liver damage. Nonalcoholic steatohepatitis is a leading cause of end-stage liver disease and contributes to cardiovascular disease in patients with type 2 diabetes mellitus. Because nonalcoholic steatohepatitis may develop even in the presence of normal liver transaminases, a liver biopsy is still necessary for a definitive diagnosis. However, new imaging methods and plasma biomarkers are emerging as alternative diagnostic tools. Lifestyle intervention is the gold standard for the management of nonalcoholic steatohepatitis. Recent randomized controlled trials suggest thiazolidiendiones are promising therapeutic agents.

SUMMARY

Nonalcoholic steatohepatitis is a frequently overlooked and potentially severe complication of type 2 diabetes mellitus. Patients may benefit from its early diagnosis and treatment.

The hepatic circadian clock is preserved in a lipid-induced mouse model of non-alcoholic steatohepatitis

Recent studies have correlated metabolic diseases, such as metabolic syndrome and non-alcoholic fatty liver disease, with the circadian clock. However, whether such metabolic changes per se affect the circadian clock remains controversial. To address this, we investigated the daily mRNA expression profiles of clock genes in the liver of a dietary mouse model of non-alcoholic steatohepatitis (NASH) using a custom-made, high-precision DNA chip. C57BL/6J mice fed an atherogenic diet for 5 weeks developed hypercholesterolemia, oxidative stress, and NASH. DNA chip analyses revealed that the atherogenic diet had a great influence on the mRNA expression of a wide range of genes linked to mitochondrial energy production, redox regulation, and carbohydrate and lipid metabolism. However, the rhythmic mRNA expression of the clock genes in the liver remained intact. Most of the circadianly expressed genes also showed 24-h rhythmicity. These findings suggest that the biological clock is protected against such a metabolic derangement as NASH.

Hepatoprotective effect of Apocynum venetum L extract on fatty liver disease of 2K1C rats with high-fat and refined-carbohydrate diet

AIM: To explore effect of extracts of Apocynum venetum L extract (AVLE) on fatty liver disease of rats with metabolic syndrome.

METHODS: Fatty liver disease of rats with metabolic syndrome were copied by two-Kidney, one-Clip method (2K1C) and high-fat and refined-carbohydrate diet for twelve weeks. Systolic blood pressure (SBP) was determined at 5th week. Forty-two rats with SBP exceeding 160 mmHg were randomly assigned to five groups: AVLE with high-, middle- and low-dose groups [200, 100, 50 mg/(kg·d), n = 8], captopril group [30 mg/(kg·d), n = 8) and model group (0.5% carboxymethylcellulose [5 mg/(kg·d), n = 10], another laying sham-operation group [0.5% carboxymethylcellulose 5 mg/(kg·d), n = 10]. Rats were intragastrically administrated between 9:00-10:00 everyday for eight weeks according to above-mentioned setting dosage. At 13th week, body weight and liver humid weight were weighed, SBP and functional, oxidative and antioxidative indexes for liver tissue were determined. Pathological changes of liver tissue was observed using hematoxylin-eosin staining method.

RESULTS: Levels of insulin, FFA, GOT and GPT in serum were significantly increased in model group; activities of T-SOD and GSH-Px in liver tissue and ISI were notably decreased, and content of lipid perhydride MDA was increased. HE staining revealed that there was hepatic cellular swelling in hepatic lobules, inequality of size of lipid droplets (most of fat drops were bullous) in periplast, nucleus on one side, narrowed sinus hepaticus and inflammatory cell infiltration in hepatic lobules and portal area. Decrease levels of insulin, FFA, GOT and GPT for serum (41.31 ± 14.46, 48.03 ± 10.19 vs 62.56 ± 19.48; 468.52 ± 205.36, 584.14 ± 185.89 vs 830.51 ± 355.17; 192.63 ± 67.41, 325.18 ± 96.47 vs 466.16 ± 95.63; 49.06 ± 21.52, 108.32 ± 38.63 vs 178.37 ± 66.55, P < 0.05 or 0.01) and content of lipid perhydride MDA (17.36 ± 3.45, 25.69 ± 5.46 vs 37.69 ± 4.13) for liver tissue were obviously observed in high- and middle-dosage AVLE groups; activities of T-SOD and GSH-Px in liver tissue and ISI were notably increased (83.80 ± 7.10, 70.86 ± 11.68 vs 47.33 ± 12.53; 681.85 ± 173.99, 481.27 ± 70.05 vs 250.50 ± 102.97; -5.19 ± 0.44, -5.45 ± 0.31 vs -5.79 ± 0.42, P < 0.05 or 0.01); lipidoses in liver cells and inflammatory cell infiltration in hepatic lobules and portal area were ameliorated.

CONCLUSION: AVLE plays a great role in antioxidative stress and has protective effect upon fatty liver disease of rats with metabolic syndrome.