Effect of chronic psychosocial stress on nonalcoholic steatohepatitis in mice

Nonalcoholic fatty liver disease (NAFLD) is characterized by hepatic lipid accumulation which may progress towards inflammation (nonalcoholic steatohepatitis (NASH)). NAFLD is regarded as a consequence of a sedentary, food-abundant lifestyle which, in the modern world, often coincides with chronically high levels of perceived psychosocial stress. Here, we aimed to characterize the effect of chronic psychosocial stress on the development of NAFLD/NASH in male mice either fed with standard chow or NASH-inducing high fat diet. Chronic psychosocial stress was induced by chronic subordinate colony housing (CSC), a pre-clinically validated paradigm relevant for human affective and somatic disorders. Single housed (SHC) mice served as controls. Under standard chow conditions CSC mice revealed lower hepatic triglyceride levels but higher hepatic TNFα, MCP-1 and HMOX mRNA expression, while serum transaminase levels did not significantly differ from SHC mice. Under the NASH-inducing high-fat diet CSC and SHC mice showed similar body weight-gain and serum levels of glucose and adiponectin. Moreover, liver histology as well as TNFα, MCP-1 and HMOX expression were similar in CSC and SHC mice fed with HFD. Surprisingly, CSC showed even significantly lower transaminase levels than SHC mice fed with the same NASH-inducing diet. Together, these data indicate that under normal dietary conditions the CSC model induces noticeable hepatic oxidative stress and inflammation without causing manifest hepatocellular injury. In contrast, CSC exhibited a protective effect on hepatocellular injury in a dietary NASH-model. Identification of the underlying mechanisms of this phenomenon may lead to novel therapeutic strategies to prevent progression of NAFLD.     

Interleukin-17 exacerbates hepatic steatosis and inflammation in non-alcoholic fatty liver disease

Mechanisms associated with the progression of simple steatosis to non-alcoholic fatty liver disease (NAFLD) remain undefined. Regulatory T cells (T(regs)) play a critical role in regulating inflammatory processes in non-alcoholic steatohepatitis (NASH) and because T helper type 17 (Th17) functionally oppose T(reg)-mediated responses, this study focused on characterizing the role of Th17 cells using a NAFLD mouse model. C57BL/6 mice were fed either a normal diet (ND) or high fat (HF) diet for 8 weeks. Mice in the HF group had a significantly higher frequency of liver Th17 cells compared to ND-fed mice. Neutralization of interleukin (IL)-17 in HF mice ameliorated lipopolysaccharide (LPS)-induced liver injury reflected by decreased serum alanine aminotransferase (ALT) levels and reduced inflammatory cell infiltrates in the liver. In vitro, HepG2 cells cultured in the presence of free fatty acids (FFA; oleic acid and palmitic acid) for 24 h and IL-17 developed steatosis via insulin-signalling pathway interference. IL-17 and FFAs synergized to induce IL-6 production by HepG2 cells and murine primary hepatocytes which, in combination with transforming growth factor (TGF-β), expanded Th17 cells. It is likely that a similar process occurs in NASH patients, as there were significant levels of IL-17(+) cell infiltrates in NASH patient livers. The hepatic expression of Th17 cell-related genes [retinoid-related orphan receptor gamma (ROR)γt, IL-17, IL-21 and IL-23] was also increased significantly in NASH patients compared to healthy controls. Th17 cells and IL-17 were associated with hepatic steatosis and proinflammatory response in NAFLD and facilitated the transition from simple steatosis to steatohepatitis. Strategies designed to alter the balance between Th17 cells and T(regs) should be explored as a means of preventing progression to NASH and advanced liver diseases in NAFLD patients.     

Hepatocellular carcinoma in a mouse model fed a choline‐deficient,L‐amino acid‐defined,high‐fat diet

Hepatocellular carcinoma (HCC) is a common cancer worldwide and represents the outcome of the natural history of chronic liver disease. The growing rates of HCC may be partially attributable to increased numbers of people with non‐alcoholic fatty liver disease (NAFLD) and non‐alcoholic steatohepatitis (NASH). However, details of the liver‐specific molecular mechanisms responsible for the NAFLD–NASH–HCC progression remain unclear, and mouse models that can be used to explore the exact factors that influence the progression of NAFLD/NASH to the more chronic stages of liver disease and subsequent HCC are not yet fully established. We have previously reported a choline‐deficient, L‐amino acid‐defined, high‐fat diet (CDAHFD) as a dietary NASH model with rapidly progressive liver fibrosis in mice. The current study in C57BL/6J mice fed CDAHFD provided evidence for the chronic persistence of advanced hepatic fibrosis in NASH and disease progression towards HCC in a period of 36 weeks. When mice fed CDAHFD were switched back to a standard diet, hepatic steatosis was normalized and NAFLD activity score improved, but HCC incidence increased and the phenotype of fibrosis‐associated HCC development was observed. Moreover, when mice continued to be fed CDAHFD for 60 weeks, HCC further developed without severe body weight loss or carcinogenesis in other organs. The autochthonous tumours showed a variety of histological features and architectural patterns including trabecular, pseudoglandular and solid growth. The CDAHFD mouse model might be a useful tool for studying the development of HCC from NAFLD/NASH, and potentially useful for better understanding pathological changes during hepatocarcinogenesis.     

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 α(1)-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.     

Pathology of the liver in obese and diabetic ob/ob and db/db mice fed a standard or high-calorie diet

Non‐alcoholic fatty liver disease (NAFLD) is one of the commonest liver diseases in Western countries. Although leptin deficient ob/ob and db/db mice are frequently used as murine models of NAFLD, an exhaustive characterization of their hepatic lesions has not been reported to date, particularly under calorie overconsumption. Thus, liver lesions were characterized in 78 ob/ob and db/db mice fed either a standard or high‐calorie (HC) diet, for one or three months. Steatosis, necroinflammation, apoptosis and fibrosis were assessed and the NAFLD activity score (NAS) was calculated. Steatosis was milder in db/db mice compared to ob/ob mice and was more frequently microvesicular. Although necroinflammation was usually mild in both genotypes, it was aggravated in db/db mice after one month of calorie overconsumption. Apoptosis was observed in db/db mice whereas it was only detected in ob/ob mice after HC feeding. Increased apoptosis was frequently associated with microvesicular steatosis. In db/db mice fed the HC diet for three months, fibrosis was aggravated while steatosis, necroinflammation and apoptosis tended to alleviate. This was associated with increased plasma β‐hydroxybutyrate suggesting an adaptive stimulation of hepatic mitochondrial fatty acid oxidation (FAO). Nevertheless, one‐third of these db/db mice had steatohepatitis (NAS ≥ 5), whereas none of the ob/ob mice developed non‐alcoholic steatohepatitis under the same conditions. Steatosis, necroinflammation, apoptosis and fibrosis are modulated by calorie overconsumption in the context of leptin deficiency. Association between apoptosis and microvesicular steatosis in obese mice suggests common mitochondrial abnormalities. Enhanced hepatic FAO in db/db mice is associated with fibrosis aggravation.     

Elevated systemic monocyte chemoattractrant protein-1 in hepatic steatosis without significant hepatic inflammation

Non-alcoholic fatty liver disease (NAFLD) is strongly associated with obesity and the metabolic syndrome. It encompasses a clinico-pathologic spectrum of conditions ranging from simple steatosis to nonalcoholic steatohepatitis (NASH). The latter develops upon pro-inflammatory cell infiltration and is widely considered as the first relevant pathophysiological step in NAFLD-progression. The chemokine monocyte chemoattractant protein 1 (MCP-1) plays an important role in the progression of hepatic inflammation and fibrosis, and both increased hepatic expression and circulating serum levels have been described in NASH. Here, we aimed to investigate MCP-1 expression in simple hepatic steatosis. Upon feeding a high-fat diet mice developed hepatic steatosis in the absence of significant hepatic inflammation, but elevated hepatic MCP-1 expression compared to control mice fed a standard chow. Interestingly, high-fat diet fed mice had significantly higher MCP-1 serum levels, and MCP-1 mRNA expression was significantly increased in visceral adipose tissue. Furthermore, MCP-1 serum levels were also elevated in patients with ultrasound-diagnosed NAFLD and correlated with the body-mass index and fasting glucose. In conclusion, our data indicate both the liver and adipose tissue as cellular sources of elevated circulating MCP-1 levels already in the early phase of hepatic steatosis. Since MCP-1 derived from visceral adipose tissue reaches the liver via portal circulation at high concentrations it may significantly contribute to the progression of simple steatosis to NASH.     

Evaluation of liver fatty acid oxidation in the leptin-deficient obese mouse

We hypothesized that liver fatty acid oxidation (FAO) is compromised in the leptin-deficient obese (Lep(ob)/Lep(ob)) mouse model, and that this would be further challenged when these mice were fed a high-fat diet. Obese mice had a 3.8-fold increased body fat content and a 9-fold increased liver fat content as compared to control mice when both groups were fed a low-fat diet. The expression of liver FAO enzymes, carnitine palmitoyltransferase-1a, long-chain acyl-CoA dehydrogenase, medium-chain acyl-CoA dehydrogenase, and short-chain acyl-CoA dehydrogenase, was not affected in obese mice as compared to controls on either a low-fat or a high-fat diet. The expression of very-long-chain acyl-CoA dehydrogenase was elevated in obese mice on the control diet, as compared to control mice. For all measures evaluated, increasing the level of fat in the diet had a smaller effect than leptin deficiency. In summary, despite obese mice having an excess of fat available for mitochondrial beta-oxidation in liver, overall energy balance appeared to dictate that the net liver FAO remained at control levels.     

The clinicopathologic spectrum and management of nonalcoholic fatty liver disease.

Nonalcoholic fatty liver disease (NAFD) comprises a spectrum of conditions characterized by the presence of predominantly macrovesicular fatty change in the liver and the absence of alcohol consumption in amounts considered detrimental to the liver. The histologic spectrum of NAFLD includes fatty liver alone or steatohepatitis (NASH). Nonalcoholic steatohepatitis is associated with increasing fibrosis is some cases and may progress to cirrhosis. Nonalcoholic fatty liver disease is often associated with insulin resistance. It is likely that there are one or more additional pathophysiologic defects in those with NASH, rendering them more susceptible to injury from oxidative stress. The clinical and histologic features of NASH are described, and an approach to the diagnosis and treatment of NAFLD is provided.     

Protease-activated receptor 1 and hematopoietic cell tissue factor are required for hepatic steatosis in mice fed a Western diet

Nonalcoholic fatty liver disease (NAFLD) is the hepatic manifestation of obesity and metabolic syndrome and contributes to increased risk of cardiovascular disease and liver-related morbidity and mortality. Indeed, obese patients with metabolic syndrome generate greater amounts of thrombin, an indication of coagulation cascade activation. However, the role of the coagulation cascade in Western diet-induced NAFLD has not been investigated. Using an established mouse model of Western diet-induced NAFLD, we tested whether the thrombin receptor protease-activated receptor 1 (PAR-1) and hematopoietic cell-derived tissue factor (TF) contribute to hepatic steatosis. In association with hepatic steatosis, plasma thrombin-antithrombin levels and hepatic fibrin deposition increased significantly in C57Bl/6J mice fed a Western diet for 3 months. PAR-1 deficiency reduced hepatic inflammation, particularly monocyte chemoattractant protein-1 expression and macrophage accumulation. In addition, PAR-1 deficiency was associated with reduced steatosis in mice fed a Western diet, including reduced liver triglyceride accumulation and CD36 expression. Similar to PAR-1 deficiency, hematopoietic cell TF deficiency was associated with reduced inflammation and reduced steatosis in livers of low-density lipoprotein receptor-deficient mice fed a Western diet. Moreover, hematopoietic cell TF deficiency reduced hepatic fibrin deposition. These studies indicate that PAR-1 and hematopoietic cell TF are required for liver inflammation and steatosis in mice fed a Western diet.     

α,β-Amyrin prevents steatosis and insulin resistance in a high-fat diet-induced mouse model of NAFLD via the AMPK-mTORC1-SREBP1 signaling mechanism

Nonalcoholic fatty liver disease (NAFLD), characterized by hepatosteatosis and steatohepatitis, is intrinsically related to obesity. Our previous study reported on the anti-obese activity of α,β-amyrin (AMY), a pentacyclic triterpene isolated from Protium heptaphyllum. This study investigated its ability to prevent fatty liver and the underlying mechanism using the mouse model of NAFLD. NAFLD was induced in male Swiss mice fed a high fat diet (HFD) for 15 weeks. The controls were fed a normal chow diet (ND). The mice were simultaneously treated with AMY at 10 and 20 mg/kg or fenofibrate at 50 mg/kg. Lipid levels along with metabolic and inflammatory parameters were assessed in liver and serum. The liver sections were histologically examined using H&E staining. RT-qPCR and western blotting assays were performed to analyze signaling mechanisms. Mice fed HFD developed severe hepatic steatosis with elevated triglycerides and lipid droplets compared with ND controls. This was associated with a decrease in AMP-activated protein kinase (AMPK) activity, an increase of mechanistic target of rapamycin complex 1 (mTORC1) signaling, and enhanced sterol regulatory element binding protein 1 (SREBP1) expression, which have roles in lipogenesis, inhibition of lipolysis, and inflammatory response. AMY treatment reversed these signaling activities and decreased the severity of hepatic steatosis and inflammatory response, evidenced by serum and liver parameters as well as histological findings. AMY-induced reduction in hepatic steatosis seemed to involve AMPK-mTORC1-SREBP1 signaling pathways, which supported its beneficial role in the prevention and treatment of NAFLD.     

受体相互作用蛋白激酶调控非酒精性脂肪肝中细胞程序性坏死的研究进展

非酒精性脂肪性肝病（NAFLD）是一种常见的慢性肝病,如果得不到有效控制,则会进一步发展为非酒精性脂肪性肝炎（NASH）,进而引起肝纤维化、肝硬化,甚至癌变。程序性坏死是近年来发现的一种新型细胞程序性死亡方式,由受体相互作用蛋白激酶（RIPK）介导所致,最终可以导致细胞膜溶解破裂,引发炎症。RIPK家族作为细胞内和细胞外应激的重要传感器,诱导调控程序性坏死的发生,并参与炎症及其他免疫反应。近年来研究表明,RIPK调控的程序性坏死在非酒精性脂肪性肝病的发生发展中具有重要作用,在动物NAFLD/NASH模型中,RIPK的表达情况与肝脂肪变性程度密切相关。在一些临床研究中亦观察到,NAFLD/NASH患者比健康人RIPK表达水平上升。但程序性坏死到底是加速肝病进程的因素,还是肝病发展过程中的保护因素,仍然没有定论。有研究表明,RIPK抑制剂可能为NAFLD治疗提供方向。我们综述了程序性坏死的分子机制及与非酒精性脂肪性肝病的关系,以及RIPK在其中扮演的重要角色,并总结了其在NAFLD/NASH治疗方面的研究进展,为进一步探究其机制,探索新的治疗手段提供理论依据。     

Regulation of oxidative stress and inflammation by hepatic adiponectin receptor 2 in an animal model of nonalcoholic steatohepatitis

The pathogenesis of nonalcoholic steatohepatitis (NASH) is not well understood; however, the progression of fatty liver to NASH has been linked to oxidative stress and lipid peroxidation in the liver, leading to inflammation. Although the adiponectin receptor 2 (AdipoR2) has been identified as a modulator of oxidative stress and inflammation in the liver, it remains unclear whether the receptor has hepatic antioxidant and anti-inflammatory effects in NASH. In this study, we used an animal model of NASH to examine hepatic AdipoR2. Obese fa/fa Zucker rats fed a high-fat and high-cholesterol (HFC) diet spontaneously developed fatty liver with inflammation and fibrosis, characteristic of NASH, after 4, 8, or 12 weeks of HFC diet consumption. AdipoR2 expression was significantly decreased, whereas the expression of genes related to NADPH oxidase complex were increased. As a result of the decrease in AdipoR2 expression, the mRNA expression of genes located downstream of AdipoR2, i.e., Cu-Zn superoxide dismutase (Cu-Zn SOD) and Mn-SOD, also decreased. Furthermore, the expression of genes related to inflammation was increased. Increased oxidative stress and inflammation by down-regulation of AdipoR2 may contribute to the progression of NASH. Thus, the AdipoR2 might be a crucially important regulator of hepatic oxidative stress and inflammation in NASH.     

An improved mouse model that rapidly develops fibrosis in non‐alcoholic steatohepatitis

Non‐alcoholic steatohepatitis (NASH) is a progressive fibrotic disease, the pathogenesis of which has not been fully elucidated. One of the most common models used in NASH research is a nutritional model where NASH is induced by feeding a diet deficient in both methionine and choline. However, the dietary methionine‐/choline‐deficient model in mice can cause severe weight loss and liver atrophy, which are not characteristics of NASH seen in human patients. Exclusive, long‐term feeding with a high‐fat diet (HFD) produced fatty liver and obesity in mice, but the HFD for several months did not affect fibrosis. We aimed to establish a mouse model of NASH with fibrosis by optimizing the methionine content in the HFD. Male mice were fed a choline‐deficient, L‐amino acid‐defined, high‐fat diet (CDAHFD) consisting of 60 kcal% fat and 0.1% methionine by weight. After 1–14 weeks of being fed CDAHFD, the mice were killed. C57BL/6J mice maintained or gained weight when fed CDAHFD, while A/J mice showed a steady decline in body weight (of up to 20% of initial weight). In both strains of mice, plasma levels of alanine aminotransferase increased from week 1, when hepatic steatosis was also observed. By week 6, C57BL/6J mice had developed enlarged fatty liver with fibrosis as assessed by Masson's trichrome staining and by hydroxyproline assay. Therefore, this improved CDAHFD model may be a mouse model of rapidly progressive liver fibrosis and be potentially useful for better understanding human NASH disease and in the development of efficient therapies for this condition.     

Hepatic steatosis causes induction of the chemokine RANTES in the absence of significant hepatic inflammation

Nonalcoholic fatty liver disease (NAFLD) encompasses a spectrum ranging from simple steatosis to cirrhosis. Hepatocellular lipid accumulation is a hallmark of both nonalcoholic steatosis and steatohepatitis (NASH). The latter develops upon pro-inflammatory cell infiltration and is widely considered as the first relevant pathophysiological step in NAFLD-progression. The chemokine CCL5/RANTES plays an important role in the progression of hepatic inflammation and fibrosis. We here aimed to investigate its expression in NAFLD. Incubation of primary human hepatocytes with palmitic acid induced a dose-dependent lipid accumulation, and corresponding dose-dependent RANTES induction in vitro. Furthermore, we observed significantly elevated hepatic RANTES expression in a dietary model of NAFLD, in which mice were fed a high-fat diet for 12 weeks. This diet induced significant hepatic steatosis but only minimal inflammation. In contrast to the liver, RANTES expression was not induced in visceral adipose tissue of the group fed with high-fat diet. Finally, RANTES serum levels were elevated in patients with ultrasound-diagnosed NAFLD. In conclusion, our data indicate hepatocytes as cellular source of elevated hepatic as well as circulating RANTES levels in response to hepatic steatosis. Noteworthy, upregulation of RANTES in response to lipid accumulation occurs in the absence of relevant inflammation, which further indicates that hepatic steatosis per se has pathophysiological relevance and should not be considered as benign.     

Therapeutic effects of angiotensin II type 1 receptor blocker, irbesartan, on non-alcoholic steatohepatitis using FLS-ob/ob male mice

Non-alcoholic steatohepatitis (NASH) is the hepatic manifestation of a metabolic syndrome characterized by accumulation of hepatic fat, inflammation and varying degrees of fibrosis. Angiotensin (AT)-II has been reported to play a role in the establishment of NASH. This study examined the effects of an AT-II receptor blocker, irbesartan, on NASH using fatty liver Shionogi (FLS)-ob/ob male mice as the closest animal model of human metabolic syndrome-related NASH. Irbesartan (30 mg/kg/day) was orally administered to FLS-ob/ob mice for 12 weeks (irbesartan group). The effects of irbesartan on steatohepatitis were examined using factors including steatosis, fibrosis, inflammation and oxidative stress. The areas of hepatic fibrosis and hepatic hydroxyproline content were significantly lower in the irbesartan group compared to controls. The areas of α-smooth muscle actin-positivity and F4/80-positive cells were significantly decreased in the irbesartan group. The percentage of 8-hydroxy-2-deoxyguanosine (8-OHdG)-positive cells and 8-OHdG DNA content were significantly decreased in the irbesartan group compared to controls. Levels of RNA expression for procollagen I, transforming growth factor β1, tumor necrosis factor-α, sterol regulatory element-binding protein 1c and fatty acid synthase were significantly lower in the irbesartan group compared to controls. In contrast, the gene expression of peroxisome proliferator activated receptor-α was significantly higher in the irbesartan group compared to controls. Irbesartan administration improved hepatic steatosis and attenuated the progression of hepatic fibrosis by inhibiting the activation of hepatic stellate cells and Kupffer cells and reducing oxidative stress.     

Japanese herbal medicines shosaikoto,inchinkoto, and juzentaihoto inhibit high‐fat diet‐induced nonalcoholic steatohepatitis in db/db mice

Few studies have investigated the effects of Japanese herbal medicines on nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH). To the best of our knowledge, only one study has examined whether high‐fat (HF) diet‐fed db/db mice are appropriate animal models of NASH. We investigated the effects of four types of Japanese herbal medicines (shosaikoto (TJ‐9), inchinkoto (TJ‐135), juzentaihoto (TJ‐48), and keishibukuryogan (TJ‐25)) on hepatic lesions of HF diet‐fed db/db mice. Db/db mice were divided into six groups: control diet (control); HF diet (HF); and HF diet supplemented with TJ‐9, TJ‐135, TJ‐48, or TJ‐25 (TJ‐9, TJ‐135, TJ‐48, and TJ‐25, respectively). Mice were killed after 6 weeks of treatment, and biochemical and pathological analyses were performed. Mice in the HF group consistently developed histopathological features consistent with definite NASH, and marked necroinflammation occurred. Serum alanine aminotransferase levels in the TJ‐9, TJ‐135, and TJ‐48 groups were significantly improved compared with those in the HF group. With regard to liver histology, TJ‐9 and TJ‐48 significantly improved lobular inflammation, and TJ‐135 significantly improved ballooning degeneration. We have shown that HF diet‐fed db/db mice are animal models that correctly recapitulate the histopathology of human NASH and that TJ‐9, TJ‐135, and TJ‐48 inhibit necroinflammatory activity in this model.     

The obesity and nonalcoholic fatty liver disease mouse model revisited: Liver oxidative stress,hepatocyte apoptosis,and proliferation

The study revisited the diet-induced obesity (DIO) mice and the nonalcoholic fatty liver disease (NAFLD) pathogenesis to serve as a translational model. Hepatic beta-oxidation pathways, lipogenesis, oxidative stress, hepatocyte apoptosis, and proliferation were investigated in obese mice. Three-month-old male mice were divided according to their diet for fifteen weeks, the control diet (C group, containing 10% energy from fat) and the high-fat diet (HF group, containing 50% energy from fat). Body weight (BW), liver mass, and steatosis were higher in the HF group than in the C group. Also, gene expression related to beta-oxidation and lipogenesis showed an adverse profile, and insulin and glucose signaling pathways were impaired in the HF group compared to the C group. As a result, steatosis was prevalent in the HF group but not in the C group. Furthermore, the pathways that generate NAFLD were negatively modulated by oxidative stress in the HF animals than in the C ones. The caspase 3 immunolabeled HF hepatocytes with increased gene and protein expressions related to apoptosis while proliferating cell nuclear antigen labeled C hepatocytes. In conclusion, the findings in the DIO mouse model reproduce the NAFLD profile relative to the human NAFLD’s apoptosis, insulin signaling, lipogenesis, beta-oxidation, and oxidative stress. Therefore, the model is adequate for a translational perspective’s morphological, biochemical, and molecular research on NAFLD.     

Vitronectin deficiency attenuates hepatic fibrosis in a non‐alcoholic steatohepatitis‐induced mouse model

Vitronectin (VN), an extracellular matrix protein, is a promising immune biomarker of non‐alcoholic steatohepatitis (NASH); however, its precise function remains unclear. This study investigated how VN deficiency contributes to the development of NASH. Towards this aim, wild‐type (WT) and VN?/? mice were fed with a choline‐deficient, L‐amino acid‐defined, high‐fat diet (CDAHFD) for 6 and 10 weeks to induce NASH, and the livers were isolated. In WT mice fed with CDAHFD for 6 and 10 weeks, the expression of Vn mRNA and protein was up‐regulated compared with that in mice fed with the MF control diet, indicating that VN is regulated in NASH condition. VN?/? mice showed decreased picrosirius red staining in the liver area and Col1a2 mRNA expression levels, compared with WT mice, indicating that the severity of hepatic fibrosis is attenuated in the CDAHFD‐fed VN?/? mice. In addition, VN deficiency did not affect the area of lipid droplets in haematoxylin‐eosin staining and the mRNA expression levels of fatty acid synthases, Srebp, Acc and Fas in the CDAHFD‐fed mice. Moreover, VN deficiency decreased the inflammation score and the mRNA expression levels of Cd11b and F4/80, macrophage markers, as well as Tnf‐α and Il‐1β, inflammatory cytokines in the CDAHFD‐fed mice. Furthermore, VN deficiency decreased the protein and mRNA expression levels of α‐smooth muscle actin in the CDAHFD‐fed mice, suggesting that VN deficiency inhibits the activation of hepatic stellate cells (HSCs). Our findings indicate that VN contributes to the development of fibrosis in the NASH model mice via modulation of the inflammatory reaction and activation of HSCs.     

糖尿病非酒精性脂肪肝病大鼠肝组织胰岛素受体、瘦素受体 mRNA的表达

目的：观察2型糖尿病大鼠肝脏的病理变化,探讨肝组织胰岛素受体（insulin R）、瘦素受体（leptin R）mRNA表达在糖尿病性非酒精性脂肪肝病（NAFLD）发病机制中的作用。方法：SD大鼠随机分成2组：正常组与2型糖尿病组。2型糖尿病组在以高脂饮食4周后,加小剂量(30 mg/kg)链脲佐菌素（STZ）诱导2型糖尿病性非酒精性脂肪性肝病大鼠模型,继续给予高脂饮食12周。分别采用HE染色、苏丹Ⅲ染色、Masson染色光镜下观察肝脏组织的病理改变;透射电镜观察肝脏超微结构改变;生化法检测血糖、血甘油三酯（TG）、血总胆固醇（TC）、丙氨酸转氨酶（ALT）和天门冬氨酸转氨酶（AST）水平;放免法检测血清胰岛素水平;ELISA法检测血清瘦素水平;RT-PCR法检测肝组织磷酸烯醇式丙酮酸羧激酶（PEPCK）、葡萄糖-6-磷酸酶（G6Pase）、insulin R、leptin R mRNA表达水平。结果：糖尿病大鼠肝细胞明显脂肪变性、碎片状坏死伴炎细胞浸润及肝纤维化病变,电镜下主要表现为肝细胞核固缩,胞浆内含大量脂滴,狄氏间隙胶原纤维增生;血糖、血胰岛素、TG、ALT、AST水平明显升高（P<0.01）,TC水平升高(P<0.05）,血清瘦素水平明显下降（P<0.01）;肝组织insulin R、leptin R mRNA表达显著升高（P<0.01）,PEPCK、G6Pase mRNA表达无显著变化。结论：2型糖尿病时的胰岛素抵抗是NAFLD发生的根源,由于胰岛素抵抗而致的低血清瘦素水平、肝组织insulin R、leptin R 表达上调参与了NAFLD的发生。