Search

Resistin is a cysteine-rich protein, which is abundantly expressed at the site of inflammation, and acts as a regulator of the NF-kB-dependent cytokine cascade. The aim of this study was to evaluate resistin levels in relation to inflammatory mediators, disease phenotype and autoantibody status in a spectrum of pathological conditions of the gastrointestinal tract. Resistin levels were measured with an ELISA in sera originated from 227 patients and 40 healthy controls (HC). Fifty patients diagnosed with non-alcoholic fatty liver disease (NAFLD), 53 ulcerative colitis (UC), 51 Crohn's disease (CD), 46 autoimmune hepatitis (AIH) and 27 primary sclerosing cholangitis (PSC) were included. The sera were analysed with respect to biochemical parameters of systemic inflammation and liver function and to the presence of antibodies to nuclear antigens (ANA), mitochondria (AMA) and smooth muscle (SMA). Compared with HC, resistin levels were raised in AIH (P = 0.017) and PSC (P = 0.03); compared with NAFLD, levels were elevated in CD (P = 0.041), AIH (P < 0.001) and PSC (P < 0.001). Patients with elevated levels of resistin were more often treated with corticosteroids, but no difference was found between active disease and clinical remission. Resistin levels were significantly higher in ANA-positive individuals compared with ANA-negative (P = 0.025). Resistin levels were directly correlated with IL-6 (r = 0.30, P = 0.02) and IL-8 (r = 0.51, P < 0.001). Elevated levels of resistin were prominent in patients with hepatobiliary inflammation and were associated with breach of self-tolerance, i.e. ANA positivity. Thus, we propose that resistin may be an important marker of disease severity in autoantibody-mediated gastrointestinal inflammatory diseases., (© 2011 The Authors. Scandinavian Journal of Immunology © 2011 Blackwell Publishing Ltd.)

Aims/hypothesis: Apolipoprotein E (ApoE) deficiency is associated with reduced fat accumulation in white adipose tissue (WAT) and high liver triacylglycerol content. Elevated levels of endocannabinoids and cannabinoid receptor type 1 (CB(1)) receptors in the liver and in epididymal vs subcutaneous WAT are associated with fatty liver, visceral adipose tissue, inflammatory markers and insulin resistance., Methods: We investigated, in Apoe (-/-) and wild-type (WT) mice, the effect of a high-fat diet (HFD) on: (1) subcutaneous and epididymal WAT accumulation, liver triacylglycerols, phospholipid-esterified fatty acids, inflammatory markers in WAT and liver, and insulin resistance; and (2) endocannabinoid levels, and the gene expression levels of the Cb ( 1 ) receptor and endocannabinoid metabolic enzymes in liver and WAT., Results: After a 16 week HFD, Apoe (-/-) mice exhibited lower body weight, WAT accumulation and fasting leptin, glucose and insulin levels, and higher hepatic steatosis, than WT mice. Glucose clearance and insulin-mediated glucose disposal following the HFD were slower in WT than Apoe (-/-) mice, which exhibited higher levels of mRNA encoding inflammatory markers (tumour necrosis factor-α [TNF-α], monocyte chemoattractant protein-1 [MCP-1], cluster of differentiation 68 [CD68] and EGF-like module-containing mucin-like hormone receptor-like 1 [EMR1]) in the liver, but lower levels in epididymal WAT. HFD-induced elevation of endocannabinoid levels in the liver or epididymal WAT was higher or lower, respectively, in Apoe (-/-) mice, whereas HFD-induced decrease of subcutaneous WAT endocannabinoid and CB(1) receptor levels was significantly less marked. Alterations in endocannabinoid levels reflected changes in endocannabinoid catabolic enzymes in WAT, or the availability of phospholipid precursors in the liver., Conclusions/interpretation: Liver and adipose tissue endocannabinoid tone following an HFD is altered on Apoe deletion and strongly associated with inflammation, insulin resistance and hepatic steatosis, or lack thereof.

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., (© 2011 The Authors. Clinical and Experimental Immunology © 2011 British Society for Immunology.)

TLRs (Toll-like receptors), as evolutionarily conserved germline-encoded pattern recognition receptors, have a crucial role in early host defence by recognizing so-called PAMPs (pathogen-associated molecular patterns) and may serve as an important link between innate and adaptive immunity. In the liver, TLRs play an important role in the wound healing and regeneration processes, but they are also involved in the pathogenesis and progression of various inflammatory liver diseases, including autoimmune liver disease, alcoholic liver disease, non-alcoholic steatohepatitis, fibrogenesis, and chronic HBV (hepatitis B virus) and HCV (hepatitis C virus) infection. Hepatitis viruses have developed different evading strategies to subvert the innate immune system. Thus recent studies have suggested that TLR-based therapies may represent a promising approach in the treatment in viral hepatitis. The present review focuses on the role of the local innate immune system, and TLRs in particular, in the liver.

Objective: Obese adipose tissue shows hallmarks of chronic inflammation, which promotes the development of metabolic disorders. The mechanisms by which immune cells interact with each other or with metabolism-associated cell types, and the players involved, are still unclear. The CD40-CD40L costimulatory dyad plays a pivotal role in immune responses and in diseases such as atherosclerosis and may therefore be a mediator of obesity. Here we investigated whether CD40L is involved in adipose tissue inflammation and its associated metabolic changes., Methods and Results: To assess a putative role of CD40L in obesity in vivo, we evaluated metabolic and inflammatory consequences of 18 weeks of high-fat feeding in CD40L(+/+) and CD40L(-/-) mice. In addition, C57Bl6 mice were injected with neutralizing anti-CD40L (αCD40L) antibody for 12 weeks while being fed a high-fat diet. Genetic deficiency of CD40L attenuated the development of diet-induced obesity, hepatic steatosis, and increased systemic insulin sensitivity. In adipose tissue, it impaired obesity-induced immune cell infiltration and the associated deterioration of glucose and lipid metabolism. Accordingly, αCD40L treatment improved systemic insulin sensitivity, glucose tolerance, and CD4(+) T-cell infiltration in adipose tissue with limited effects on adipose tissue weight., Conclusions: CD40L plays a crucial role in the development of obesity-induced inflammation and metabolic complications.

The spleen could be considered a neglected organ. To date, it has been deemed an ancillary organ in portal hypertension or an organ localization in lymphoproliferative diseases, even though it has had significant attention in infectious diseases for some time. Now, it is thought to be central in regulating the immune system, a metabolic asset and involved in endocrine function with regard to nonalcoholic fatty liver disease. The main mechanisms involved in this complex network will be critically discussed in this article.

In this study, we were aimed to evaluate the probable effect of the crud extract of Silybum marianum, with high polyphenolic content, on experimental nonalcoholic steatohepatitis (NASH). To induce NASH, a methionine and choline deficient (MCD) diet was given to N-Mary rats for 8 weeks. After NASH development, MCD-fed rats were divided into two groups: MCD groups received MCD diet and MCD+S group was fed MCD diet plus crude extract of S. marianum orally for 3 weeks. Control group was fed a normal diet for 11 weeks. Finally, all rats were sacrificed. Plasma alanine amino transferase (ALT) and aspartate amino transferase (AST) levels were evaluated. In addition, the following hepatic factors were also evaluated: liver histology, malondialdehyde (MDA) and reduced glutathione (GSH) contents, gene expressions of TNF-α and TGF-β and immunoblot evaluations of caspase-3, ERK/p-ERK, JNK/pJNK and p38/pp38. Histopathological evaluations of the liver samples revealed that treatment with the S. marianum extract has abated the severity of NASH among the MCD-fed rats. Also, a significant reduction was observed in the sera ALT and AST activities. In addition, the extract caused dramatic reduction in the elevated hepatic TNF-α and TGF-β mRNA and MDA levels along with an increase in the GSH content. Moreover, the plant extract treatments significantly lowered activation of procaspase-3 to active caspase-3 and also lowered the phosphorylated form of JNK among the same group of rats. These results suggest that the S. marianum crude extract beneficial effects on NASH are mainly due to its antioxidant and anti-inflammatory activities., (Copyright © 2010 Elsevier GmbH. All rights reserved.)

Great progress has been made in understanding the development of non-alcoholic fatty liver disease (NAFLD) but less is known about the mechanisms underlying the progress from steatosis to steatohepatitis (NASH). Our aim was to evaluate if the amount and type of storage of fat in hepatocytes is of importance for hepatocyte injury. We also wanted to show if not only the innate immunity but also the adaptive immunity is involved in NASH. Thirty-one patients with NASH or borderline NASH and 18 non-NASH patients were investigated. Liver biopsies were scored for NASH according to Kleiner et al. Paraffin-embedded liver biopsies were stained with antibodies against CD3, TLR4, CD68, Cleaved Caspase-3, ICAM1, Foxp3 and ApopTag by immunohistochemistry. Serum soluble ICAM-1 (sICAM-1) were analysed by ELISA. The volume density of fat was 59% in the NASH patients and microvesicular fat, increased in high NAS score patients. ICAM-1 positive hepatocytes were seen in NASH patients and were localized in areas with microvesicular fat. Non-NASH biopsies were negative for ICAM-1 positive hepatocytes. The sICAM-1 were significantly higher in NASH-patients (339.8 ± 34.07) than in non-NASH patients (229.5 ± 12.14), p = 0.0015. Patients with NAS score over four had higher area of CD68 positive cells p = 0.0011 and Foxp3 positive cells (p = 0.024) than non-NASH patients. In liver tissue with NASH, hepatocytes with microvesicular steatosis seem to be expressing more inflammatory markers, and in this liver tissue an increased number of CD68 cells and regulatory T-cells (Tregs, e.g. Foxp3+ cells) were seen, indicating an involvement of, both the innate and the adaptive immunity., (© 2011 The Authors. APMIS © 2011 APMIS.)

Background and Aim: Cholesterol accumulation plays an important role in the progression of non-alcoholic fatty liver disease. We have demonstrated that inflammation aggravated cholesterol accumulation, causing tissue injury in the vessel and kidney. This study was undertaken to investigate whether inflammatory stress exacerbates hepatic cholesterol accumulation and we explored the underlying mechanisms., Methods: We used casein injection in C57BL/6J mice, interleukin-1β and interleukin-6 stimulation in human hepatoblastoma cell line (HepG2) cells to induce inflammatory stress. Oil Red O staining and intracellular cholesterol assay were used to quantify cellular cholesterol levels. Real-time reverse transcription polymerase chain reaction and Western blot were used to measure messenger RNA (mRNA) and protein expression of target genes. HMGCoA reductase (HMGCoA-r) enzymatic activity and cellular cholesterol synthesis were measured by radioactive methods., Results: We demonstrated that inflammatory stress increased hepatic cholesterol accumulation and enhanced sterol regulatory element binding protein 2 (SREBP2), low-density lipoprotein receptor (LDLr) and HMGCoA-r mRNA and protein expression in livers of C57BL/6J mice and in HepG2 cells. A high-fat diet in mice or LDL loading in HepG2 cells inhibited mRNA and protein expression of these genes. However, the suppressive effect was overridden by inflammatory stress both in vivo and in vitro. Inflammatory stress increased HMGCoA-r enzymatic activity and cellular cholesterol synthesis in HepG2 cells in the absence or presence of LDL loading., Conclusion: Inflammatory stress disrupted hepatic SREBP2-mediated low-density lipoprotein receptor and HMGCoA-r feedback regulation resulting in exacerbated cholesterol accumulation in livers of C57BL/6J mice and HepG2 cells., (© 2011 Journal of Gastroenterology and Hepatology Foundation and Blackwell Publishing Asia Pty Ltd.)

Stimulation of the innate immune receptors Toll-like receptor (TLR)-2 and TLR4 has been shown to promote the development of a variety of diseases involving dysregulated metabolism, including atherosclerosis, type 2 diabetes and non-alcoholic fatty liver disease. However, the origin and nature of the agents responsible for stimulating TLR2 or TLR4 signalling in these conditions remain to be clearly identified. This review summarises the evidence supporting the proposal that 'pathogen-associated molecular patterns' (PAMPs) derived from dietary and commensal sources may contribute to the chronic inflammatory processes that underpin the development of these diseases via stimulation of TLR2 and TLR4. In particular, insights gained from recent studies employing TLR-transfectant based bioassays to quantify the abundance of PAMPs in foodstuffs and specific commensal compartments are discussed. Finally, the major mechanisms by which TLR-stimulants may gain access to the circulation to promote systemic low-grade inflammation are considered., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Aim: To determine if natural killer T cell (NKT) populations are affected in nonalcoholic fatty liver disease (NAFLD)., Methods: Patients undergoing bariatric surgery underwent liver biopsy and blood sampling during surgery. The biopsy was assessed for steatosis and immunocyte infiltration. Intrahepatic lymphocytes (IHLs) were isolated from the remainder of the liver biopsy, and peripheral blood mononuclear cells (PBMCs) were isolated from the blood. Expression of surface proteins on both IHLs and PBMCs were quantified using flow cytometry., Results: Twenty-seven subjects participated in this study. Subjects with moderate or severe steatosis had a higher percentage of intrahepatic CD3+/CD56+ NKT cells (38.6%) than did patients with mild steatosis (24.1%, P = 0.05) or those without steatosis (21.5%, P = 0.03). Patients with moderate to severe steatosis also had a higher percentage of NKT cells in the blood (12.3%) as compared to patients with mild steatosis (2.5% P = 0.02) and those without steatosis (5.1%, P = 0.05)., Conclusion: NKT cells are significantly increased in the liver and blood of patients with moderate to severe steatosis and support the role of NKT cells in NAFLD.

Background and Aim: Non-alcoholic steatohepatitis (NASH) is one entity in the spectrum of non-alcoholic fatty liver disease (NAFLD). The aim of this study was to explore the prevention and therapeutic effect of sophocarpine on experimental rat NASH., Methods: Sophocarpine with the dosage of 20 mg/kg/day was injected into NASH rats. At the end of 12 weeks, all rats were killed to detect the degree of fatty degeneration, inflammation and fibrosis., Results: Sophocarpine intervention (in the pro-treated and treated groups) resulted in a significant decrease of liver weight, liver index, serum transaminase and serum lipids. Messenger RNA expressions of leptin, interleukin (IL)-6, tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-β1, procollagen-I and α-smooth muscle actin (SMA) and deposition of IL-6, TNF-α and TGF-β1 in liver decreased, whereas the messenger RNA expression of adiponectin increased significantly compared with that in the model group. Moreover, histological improvement was also observed in the sophocarpine intervention group. In addition, there was no significant difference in any detected indicator between the pro-treated and treated group., Conclusions: Sophocarpine could decrease the level of serum transaminase, improve lipid metabolism, reduce synthesis of inflammatory cytokines TNF-α, TGF-β1 and IL-6, activate protective adipocytokine adiponectin, and might be selected as a promising agent for the clinical prevention and therapy of NASH., (© 2011 Journal of Gastroenterology and Hepatology Foundation and Blackwell Publishing Asia Pty Ltd.)

Autophagy is a critical pathway for the degradation of intracellular components by lysosomes. Established functions for both macroautophagy and chaperone-mediated autophagy in hepatic lipid metabolism, insulin sensitivity and cellular injury suggest a number of potential mechanistic roles for autophagy in nonalcoholic steatohepatitis (NASH). Decreased autophagic function in particular may promote the initial development of hepatic steatosis and progression of steatosis to liver injury. Additional functions of autophagy in immune responses and carcinogenesis may also contribute to the development of NASH and its complications. The impairment in autophagy that occurs with cellular lipid accumulation, obesity and aging may therefore have an important impact on this disease, and agents to augment hepatic autophagy have therapeutic potential in NASH.

Toll-like receptor 4 (TLR4) and its coreceptor, myeloid differentiation factor-2 (MD-2), are key in recognition of lipopolysaccharide (LPS) and activation of proinflammatory pathways. Here we tested the hypothesis that TLR4 and its coreceptor MD-2 play a central role in nonalcoholic steatohepatitis (NASH) and liver fibrosis in nonalcoholic fatty liver disease. Mice of control genotypes and those deficient in MD-2 or TLR4 [knockout (KO)] received methionine choline-deficient (MCD) or methionine choline-supplemented (MCS) diet. In mice of control genotypes, MCD diet resulted in NASH, liver triglycerides accumulation, and increased thiobarbituric acid reactive substances, a marker of lipid peroxidation, compared with MCS diet. These features of NASH were significantly attenuated in MD-2 KO and TLR4 KO mice. Serum alanine aminotransferase, an indicator of liver injury, was increased in MCD diet-fed genotype controls but was attenuated in MD-2 KO and TLR4 KO mice. Inflammatory activation, indicated by serum TNF-α and nictoinamide adenine dinucleotide phosphate oxidase complex mRNA expression and activation, was significantly lower in MCD diet-fed MD-2 KO and TLR4 KO compared with corresponding genotype control mice. Markers of liver fibrosis [collagen by Sirius red and α-smooth muscle actin (SMA) staining, procollagen-I, transforming growth factor-β1, α-SMA, matrix metalloproteinase-2, and tissue inhibitor of matrix metalloproteinase-1 mRNA] were attenuated in MD-2 and TLR4 KO compared with their control genotype counterparts. In conclusion, our results demonstrate a novel, critical role for LPS recognition complex, including MD-2 and TLR4, through NADPH activation in liver steatosis, and fibrosis in a NASH model in mice.

Background: Endotoxin is hypothesized to play an important role in the activation of inflammatory pathways associated with nonalcoholic steatohepatitis (NASH). However, demonstration of hepatic endotoxin exposure is challenging due to the inaccessibility of the portal circulation. Furthermore, reliable measurement of the relatively low endotoxin levels in plasma of patients with liver disease and subsequent interpretation remain difficult., Goals: In this study, we used the EndoCab assay that measures endogenous antibodies to the core region of endotoxin to estimate hepatic endotoxin exposure over time., Study: IgG levels against endotoxin were measured in peripheral plasma obtained from 21 severely obese patients with NASH and 9 severely obese patients with healthy livers., Results: Plasma IgG levels against endotoxin were significantly elevated in patients with NASH compared with patients with healthy livers (48±63 GMU/mL vs. 10±13 GMU/mL). Moreover, these IgG levels progressively increased with NASH grade (grade 1 29±37; grade 2 58±51; grade 3 84±132 GMU/mL, P<0.05). There was no relation between plasma IgG levels and NASH stage., Conclusions: Plasma IgG levels against endotoxin were found to be increased in biopsy-proven human NASH and increased with aggravated inflammation in NASH, suggesting a relationship between chronic endotoxin exposure and the severity of human NASH.

Unlabelled: The aim of the study was to compare the features of immune response in patients with alcoholic liver disease and non-alcoholic steatohepatitis., Materials: There was investigated immune status of 46 patients with alcoholic liver disease and 34 patients with non-alcoholic steatohepatitis., Results: It was found the resemblance of the immune regulation of pathogenesis in both diseases. It was also established that in the history of alcoholic liver disease necrosis starts earlier because of loosing immune regulation of programmed cell death. This leads to forming liver cirrhosis in younger age.

Background: Higher levels of white blood cell (WBC) count are known to be associated with metabolic syndrome and insulin resistance. Nonalcoholic fatty liver disease (NAFLD) is also considered a hepatic manifestation of insulin resistance., Aims: The present study aimed to determine the relation between WBC count and the presence of NAFLD based on abdominal sonographic findings., Methods: A cross-sectional study with 3681 healthy subjects (2066 men, 1615 women) undergoing medical check-up was conducted. The odds ratios (ORs) and 95% confidence intervals (CIs) for NAFLD were calculated using multivariate logistic regression analyses across WBC quartiles., Results: A graded independent relationship between higher levels of WBC count and the prevalence risk of NAFLD was observed. After adjusting for age, smoking status, regular exercise, body mass index (BMI), blood pressure, fasting plasma glucose, triglyceride, and HDL-cholesterol, the ORs (95% CIs) for NAFLD according to WBC quartiles were 1.00, 1.48 (1.10-1.98), 1.59 (1.18-2.14), and 1.84 (1.35-2.51) for men and 1.00, 1.15 (0.67-1.96), 1.88 (1.13-3.11), and 2.74 (1.68-4.46) for women., Conclusions: WBC count was found to be independently associated with the presence of NAFLD regardless of classical cardiovascular risk factors and other components of metabolic syndrome., (Copyright © 2010 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.)

Background: Invariant natural killer T (iNKT) cells have been suggested to play critical roles in a wide range of immune responses by acting in a proinflammatory or anti-inflammatory manner. Nonalcoholic steatohepatitis (NASH) is a chronic liver disease progressing to advanced cirrhosis and hepatocellular carcinoma. Despite the abundance of iNKT cells in the liver, their role in the pathogenesis of NASH remains obscure. Here, we investigated their role in the development of diet-induced steatosis/steatohepatitis., Methods: We used BALB/c wild-type mice and Jα18-deficient (KO) mice lacking iNKT cells fed either a normal diet or a high-fat diet (HFD). The liver and blood were collected from these mice to examine liver inflammation, steatosis, and fibrosis at the indicated time points., Results: KO mice fed the HFD, compared with control mice fed the HFD, exhibited a clearly higher serum alanine aminotransferase level and a greater number of hepatic inflammatory foci, although there was no significant difference in hepatic lipid retention between these groups of mice. The HFD enhanced hepatic messenger RNA expression of inflammatory cytokines and chemokines in KO but not in control mice. The HFD also increased the proportion of hepatic CD4 T cells and CD8 T cells that composed hepatic inflammatory foci in KO mice, but not in the controls. Prolonged feeding with the HFD augmented liver fibrosis in KO but not in control mice., Conclusions: These findings indicate that iNKT cells play a protective role against liver inflammation progressing to fibrosis, but not against steatosis, enhanced by dietary excess fat, suggesting a key role of these cells in NASH pathogenesis.

Obesity is increasingly being recognized as a risk factor for a number of benign and malignant gastrointestinal conditions. However, literature on the underlying pathophysiological mechanisms is sparse and ambiguous. There is compelling evidence that both overnutrition and undernutrition negatively interfere with the immune system. Overnutrition has been found to increase susceptibility to the development of inflammatory diseases, autoimmune diseases and cancer. In the regulation of immune and inflammatory processes, white adipose tissue plays a critical role, not only as an energy store but also as an important endocrine organ. The obese state is characterised by a low-grade systemic inflammation, mainly as a result of increased adipocytes as well as fat resident- and recruited-macrophage activity. In the past few years, various products of adipose tissue including adipokines and cytokines have been characterised and a number of pathways linking adipose tissue metabolism with the immune system have been identified. Activation of the innate immune system plays a major role in hepatic steatosis. Non-alcoholic fatty liver disease includes a wide spectrum of diseases, from pure steatosis to non-alcoholic steatohepatitis in the absence of significant alcohol consumption. Although steatosis is considered a non-progressive disease, non-alcoholic steatohepatitis may deteriorate in advanced chronic liver diseases, cirrhosis, and hepatocellular carcinoma. An important parallel between obesity-related pathology of adipose tissue and liver pertains to the emerging role of macrophages, and growing evidence suggests that Kupffer cells critically contribute to progression of non-alcoholic fatty liver disease. Moreover, a close link between specific immune activation and atherosclerosis has been well established, suggesting that fat can directly trigger immune responses. This review discusses the role of fat as "a matter of disturbance for the immune system" with a focus on hepatic steatosis.

Nonalcoholic fatty liver disease (NAFLD) has become the most common liver disease in the United States and other developed countries and is expected to increase in the next few years. Emerging data suggest that some patients with NAFLD may progress to nonalcoholic steatohepatitis (NASH), cirrhosis and even hepatocellular carcinoma. NAFLD can also promote the development and progression of disease in other organ systems, such as the cardiovascular and endocrine (i.e. diabetes) systems. Thus, understanding the pathogenesis of NAFLD is of great clinical importance and is critical for the prevention and treatment of the disease. Although the "two-hit hypothesis" is generally accepted, the exact pathogenesis of NAFLD has not been clearly established. The liver is an important innate immune organ with large numbers of innate immune cells, including Kupffer cells (KCs), natural killer T (NKT) cells and natural killer (NK) cells. Recent data show that an imbalance in liver cytokines may be implicated in the development of fatty liver disease. For example, Th1 cytokine excess may be a common pathogenic mechanism for hepatic insulin resistance and NASH. Innate immune cells in the liver play important roles in the excessive production of hepatic Th1 cytokines in NAFLD. In addition, liver innate immune cells participate in the pathogenesis of NAFLD in other ways. For example, activated KCs can generate reactive oxygen species, which induce liver injury. This review will focus primarily on the possible effect and mechanism of KCs, NKT cells and NK cells in the development of NAFLD.

Background: Factors responsible for the progression of primary biliary cirrhosis (PBC) are still poorly understood. In the present study, we investigated the associations between the stage of PBC and the immune reaction triggered by oxidative stress; the presence of obesity, steatosis,steatohepatitis; and other toxic, metabolic, or steatogenic factors., Methods: We studied clinical, laboratory, and histological data for 274 untreated patients with serum antimitochondrial antibody (AMA)-positive PBC. Circulating IgG against human serum albumin adducted with malondialdeyde, the major product of lipid peroxidation, was measured in these patients and in a group of 98 sex-, age and body mass index (BMI)-matched controls., Results: Steatosis was present in 40.5% of all patients. Steatohepatitis was present in 14.9% of all patients. There was a significant association between the frequencies of steatosis and steatohepatitis and the worsening of PBC. Circulating IgG against lipid peroxidation products was significantly higher in the PBC patients than in the controls. Titers of lipid peroxidation-related antibodies were significantly increased in patients with steatosis and inpatients at more advanced stages. Bivariate analysis revealed a significant association between indirect evidence of oxidative stress, steatosis, steatohepatitis, age, BMI, frequency of diabetes, alcohol intake, iron grade after Perl's stain, and PBC stage. Logistic regression analysis confirmed that the titers of antibodies against lipid peroxidation products (odds ratio 4.5, p< .001, 95% confidence interval 3.9–14.4), the presence of steatosis (odds ratio 4.1, 95% confidence interval 2.5–15.4, p< .001), higher BMI (odds ratio 3.9, p< .021, 95%confidence interval 1.4–9.5), and alcohol intake (males ≥ 30 g/day, females ≥ 20 g/day, odds ratio 4.5,95% confidence interval 1.3–19.8, p< .029) were independently associated with more advanced stages of the disease., Conclusions: The immune reactions triggered by oxidative stress, steatosis, obesity, and alcohol intake are independent predictors of PBC stage progression.

We have investigated the presence and the possible clinical implications of oxidative stress in children with non-alcoholic fatty liver disease (NAFLD). The present study was an observational study of oxidative stress parameters in the progression of paediatric NAFLD. We observed the role of oxidative stress in children diagnosed with NAFLD by evaluating: serum protein carbonyls, hepatic expression of 8-hydroxy-2-deoxyguanosine (8-OHG), and circulating antibody against malondialdehyde adducted human serum albumin (MDA-HSA). Forty consecutive children with biopsy-proven NAFLD (27 male; 13 female) referred to Bambino Gesù Children's Hospital, Rome, Italy, from January 2007 to April 2008 were included in the study. Serum variations of protein carbonyls, 8-OHG, and circulating antibody against MDA-HSA were evaluated. Elevated protein carbonyls were evident in 33 subjects (83%) irrespective of obesity and insulin resistance. Moreover, liver biopsies of NAFLD patients positive for circulating protein carbonyls also showed a significant increase in the nuclear staining for 8-OHG (p=0.006; 95% CI 3.1-17.7). Anti-MDA-HSA IgG above control threshold was detected in 25 (63%) children. Although protein carbonyl levels were unrelated with disease severity, patients with elevated anti-MDA-HSA IgG had scores for lobular inflammation significantly higher (p=0.019) than subjects with antibodies within the control range, while steatosis, hepatocyte ballooning and fibrosis were similar. High anti-MDA-HSA reactivity was also associated with a 13-fold increased risk (OR=12.9; 95= CI 1.5-113.8; p=0.013) of a NAFLD activity score (NAS) >or=5. These results demonstrate that oxidative stress has an high prevalence in children with NAFLD and is associated with an increased severity of steatohepatitis.

Objective: To investigate predictors of hepatic steatosis in HBeAg-negative chronic hepatitis B (CHB) patients and their diagnostic values in hepatic inflammation and fibrosis., Methods: A total of 106 HBeAg-negative CHB patients with clinically and pathologically proven steatosis and 98 patients without steatosis were recruited into this study. The levels of fasting blood glucose (FBG), fasting insulin (FINS), triglyceride (TG), cholesterol (CHOL), alanine aminotransferase (ALT), aspartate aminotransferase (AST), albumin (Alb), globulin (Glb), HBV DNA, body mass index (BMI), homeostatic model assessment of insulin resistance (HOMA-IR) and pathological changes of the liver in inflammation, fibrosis and fatty deposition were examined in all patients., Results: The levels of BMI, HOMA-IR, FBG, insulin, TG, and CHOL were significantly higher in patients with steatosis than those without steatosis (all P<0.05). But ALT, AST and HBV DNA levels were significantly lower in patients with steatosis (all P<0.05). Logistic regression analysis showed that only FINS was a significant predictor for hepatic steatosis (P<0.05); FINS and Glb were significant predictors for hepatic inflammation (all P<0.05); BMI and TC were significant predictors for hepatic fibrosis (all P<0.05)., Conclusions: Hepatic steatosis, a common disease in HBeAg-negative CHB patients, was positively associated with BMI, FBG, FINS, TG, TC, GGT, ALP and HOMA-IR. In these patients, the prevalence of hepatic inflammation and fibrosis was also increased.

Background/aims: The magnitude of antigen-specific immunity was assessed in a murine model of nonalcoholic fatty liver diseases (NAFLD). Because antigen-specific immunity was diminished in NAFLD mice, the underlying mechanisms were evaluated through analysis of the functions of antigen-presenting dendritic cells (DC) and other immunocytes., Methods: For 12 weeks, NAFLD mice received a high-fat (60%) and high-calorie (520 kcal/100 g) diet. C57BL/6 mice (controls) received a standard diet. NAFLD mice and control mice were immunized with hepatitis B vaccine containing hepatitis B surface antigen (HBsAg) and hepatitis B core antigen (HBcAg). Antibody to HBsAg (anti-HBs), HBsAg and HBcAg-specific cellular immune response and functions of whole spleen cells, T lymphocytes, B lymphocytes and spleen DCs of NAFLD and control mice were assessed in vitro., Results: Levels of anti-HBs and the magnitude of proliferation of HBsAg and HBcAg-specific lymphocytes were significantly lower in NAFLD mice than control mice (P < 0.05). The spleen cells of NAFLD mice produced significantly higher levels of inflammatory cytokines (P < 0.05) and exhibited significantly increased T cell proliferation compared with control mice (P < 0.05). However, the antigen processing and presenting capacities of spleen DCs were significantly decreased in NAFLD mice compared with control mice (P < 0.05). Palmitic acid, a saturated fatty acid, caused diminished antigen processing and presenting capacity of both murine and human DCs., Conclusions: Nonalcoholic fatty liver disease mice exhibit decreased magnitudes of antigen-specific humoral and cellular immune responses. This effect is mainly, if not solely, due to impaired antigen processing and presentation capacities of DC.

Background & Aims: Complement is involved in the development of alcoholic liver disease in mice; however, the mechanisms for complement activation during ethanol exposure have not been identified. C1q, the recognition subunit of the first complement component, binds to apoptotic cells, thereby activating the classical complement pathway. Because ethanol exposure increases hepatocellular apoptosis, we hypothesized that ethanol-induced apoptosis would lead to activation of complement via the classical pathway., Methods: Wild-type and C1qa-/- mice were allowed free access to ethanol-containing diets or pair-fed control diets for 4 or 25 days., Results: Ethanol feeding for 4 days increased apoptosis of Kupffer cells in both wild-type and C1qa-/- mice. Ethanol-induced deposition of C1q and C3b/iC3b/C3c was colocalized with apoptotic Kupffer cells in wild-type, but not C1qa-/-, mice. Furthermore, ethanol-induced increases in tumor necrosis factor-alpha and interleukin-6 expression at this early time point were suppressed in C1q-deficient mice. Chronic ethanol feeding (25 days) increased steatosis, hepatocyte apoptosis, and activity of serum alanine and aspartate aminotransferases in wild-type mice. These markers of hepatocyte injury were attenuated in C1qa-/- mice. In contrast, chronic ethanol (25 days)-induced increases in cytochrome P450 2E1 expression and oxidative stress did not differ between wild-type and C1qa-/- mice., Conclusions: For the first time, these data indicate that ethanol activates the classical complement pathway via C1q binding to apoptotic cells in the liver and that C1q contributes to the pathogenesis of ethanol-induced liver injury., (Copyright (c) 2010 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Dietary fatty acids are major contributors to the development and progression of insulin resistance and nonalcoholic fatty liver disease (NAFLD). Dietary fatty acids also alter hepatic NKT cells that are activated by antigens presented by CD1d. In the current study, we examine the mechanism of dietary fatty acid induced hepatic NKT cell deficiency and its causal relationship to insulin resistance and NAFLD. We discover that dietary saturated fatty acids (SFA) or monounsaturated fatty acids (MUFA), but not polyunsaturated fatty acids (PUFA), cause hepatic NKT cell depletion with increased apoptosis. Dietary SFA or MUFA also impair hepatocyte presentation of endogenous, but not exogenous, antigen to NKT cells, indicating alterations of the endogenous antigen processing or presenting pathway. In vitro treatment of normal hepatocytes with fatty acids also demonstrates impaired ability of CD1d to present endogenous antigen by dietary fatty acids. Furthermore, dietary SFA and MUFA activate the NFkappaB signaling pathway and lead to insulin resistance and hepatic steatosis. In conclusion, both dietary SFA and MUFA alter endogenous antigen presentation to hepatic NKT cells and contribute to NKT cell depletion, leading to further activation of inflammatory signaling, insulin resistance, and hepatic steatosis.

Mammalian sirtuin 1 (SIRT1) may control fatty acid homeostasis in liver. However, this possibility and underlying mechanism remain to be established. In this study, we addressed the issues by examining the metabolic phenotypes of SIRT1 heterozygous knockout (SIRT1(+/-)) mice. The study was conducted in the mice on three different diets including a low-fat diet (5% fat wt/wt), mediate-fat diet (11% fat wt/wt), and high-fat diet (HFD, 36% fat wt/wt). On low-fat diet, the mice did not exhibit any abnormality. On mediate-fat diet, the mice exhibited a significant increase in hepatic steatosis with elevated liver/body ratio, liver size, liver lipid (triglyceride, glycerol, and cholesterol) content, and liver inflammation. The hepatic steatosis was deteriorated in the mice by HFD. In the liver, lipogenesis was increased, fat export was reduced, and beta-oxidation was not significantly changed. Body weight and fat content were increased in response to the dietary fat. Fat was mainly increased in sc adipose tissue and liver. Inflammation was also elevated in epididymal fat. Whole body energy expenditure and substrate utilization were reduced. Food intake, locomotor activity, and fat absorption were not changed. These data suggest that a reduction in the SIRT1 activity increases the risk of fatty liver in response to dietary fat. The liver steatosis may be a result of increased lipogenesis and reduced liver fat export. The inflammation may contribute to the pathogenesis of hepatic steatosis as well. A reduction in lipid mobilization may contribute to the hepatic steatosis and low energy expenditure.

Unlabelled: Liver inflammation is greater in nonalcoholic steatohepatitis (NASH) than steatosis, suggesting that immune responses contribute to nonalcoholic fatty liver disease (NAFLD) progression. Livers normally contain many natural killer T (NKT) cells that produce factors that modulate inflammatory and fibrogenic responses. Such cells are relatively depleted in steatosis, but their status in more advanced NAFLD is uncertain. We hypothesized that NKT cells accumulate and promote fibrosis progression in NASH. We aimed to determine if livers become enriched with NKT cells during NASH-related fibrosis; identify responsible mechanisms; and assess if NKT cells stimulate fibrogenesis. NKT cells were analyzed in wildtype mice and Patched-deficient (Ptc(+/-)) mice with an overly active Hedgehog (Hh) pathway, before and after feeding methionine choline-deficient (MCD) diets to induce NASH-related fibrosis. Effects of NKT cell-derived factors on hepatic stellate cells (HSC) were examined and fibrogenesis was evaluated in CD1d-deficient mice that lack NKT cells. NKT cells were quantified in human cirrhotic and nondiseased livers. During NASH-related fibrogenesis in wildtype mice, Hh pathway activation occurred, leading to induction of factors that promoted NKT cell recruitment, retention, and viability, plus liver enrichment with NKT cells. Ptc(+/-) mice accumulated more NKT cells and developed worse liver fibrosis; CD1d-deficient mice that lack NKT cells were protected from fibrosis. NKT cell-conditioned medium stimulated HSC to become myofibroblastic. Liver explants were 2-fold enriched with NKT cells in patients with non-NASH cirrhosis, and 4-fold enriched in patients with NASH cirrhosis., Conclusion: Hh pathway activation leads to hepatic enrichment with NKT cells that contribute to fibrosis progression in NASH.

Objective: Nonalcoholic fatty liver disease is highly prevalent in obese and type 2 diabetic individuals and is strongly associated with dyslipidemia and inflammation. Weight loss and/or pharmacotherapy are commonly used to correct these abnormalities., Research Design and Methods: We performed a 16-week intervention trial of a hypocaloric, low-fat diet plus 10 mg/day ezetimibe (n = 15) versus a hypocaloric, low-fat diet alone (n = 10) on intrahepatic triglyceride (IHTG) content, plasma high sensitivity-C-reactive protein (hs-CRP), adipocytokines, and fetuin-A concentrations and apolipoprotein (apo)B-100 kinetics in obese subjects. ApoB-100 metabolism was assessed using stable isotope tracer kinetics and compartmental modeling; liver and abdominal fat contents were determined by magnetic resonance techniques., Results: Both weight loss and ezetimibe plus weight loss significantly (all P < 0.05) reduced body weight, visceral and subcutaneous adipose tissues, insulin resistance and plasma triglycerides, VLDL-apoB-100, apoC-III, fetuin-A, and retinol-binding protein-4 and increased plasma adiponectin concentrations. Compared with weight loss alone, ezetimibe plus weight loss significantly (all P < 0.05) decreased IHTG content (-18%), plasma hs-CRP (-53%), interleukin-6 (-24%), LDL cholesterol (-18%), campesterol (-59%), and apoB-100 (-14%) levels, with a significant increase in plasma lathosterol concentrations (+43%). The LDL-apoB-100 concentration also significantly fell with ezetimibe plus weight loss (-12%), chiefly owing to an increase in the corresponding fractional catabolic rate (+29%). The VLDL-apoB-100 secretion rate fell with both interventions, with no significant independent effect of ezetimibe., Conclusions: Addition of ezetimibe to a moderate weight loss diet in obese subjects can significantly improve hepatic steatosis, inflammation, and LDL-apoB-100 metabolism.

Background: Obese subjects with chronic hepatitis C virus (HCV) infection have more rapidly progressive liver disease. Objective In this study, we aimed to compare the hepatic cytokine and chemokine profiles in obese and lean subjects with chronic HCV infection using qRT-PCR and immunohistochemistry., Methods: Liver biopsies from 55 subjects were studied, including 20 with chronic hepatitis C, 25 with non-alcoholic fatty liver disease and 10 subjects with non-diseased liver., Results: Compared to the control groups, the liver injury in chronic hepatitis C was characterised by increased expression of several T-helper-1 cytokines including interferon-gamma and tumour necrosis factor-alpha, and chemokines such as RANTES, IP-10 and MCP-1. In particular, in comparison with lean (BMI or=30 kg/m(2)) HCV infected subjects had increased hepatic expression of interferon-gamma (p=0.004) and tumour necrosis factor-alpha (p<0.001), as well as increased expression of IP-10 (p=0.009) and MCP-1 (p<0.001). Localisation of these inflammatory chemokines revealed that in comparison to lean-HCV subjects, HCV infected liver from obese subjects exhibited significantly increased expression of IP-10 (p<0.001) and MCP-1 (p=0.02) in the inflammatory infiltrate of the portal tracts. In parallel, there was increased CD3 infiltration in the liver of obese-HCV subjects., Conclusions: The data provide important mechanistic information on the cause of hepatic injury in obese-HCV subjects including: (1) enhanced T helper-1 cytokine response patterns-to promote hepatocellular injury; (2) increased expression of the chemokines IP-10 and MCP-1 at both the mRNA and protein levels-to enhance inflammatory cell recruitment; (3) differing localisation of these chemokines within the liver of obese-HCV versus lean-HCV subjects-implying different inducing stimuli and; (4) increased CD3 expression in the liver of obese-HCV subjects-concordant with the increased expression of T cell chemoattractants.

The Kampo formula keishibukuryogan (KBG, Guizhifulingwan) is frequently used in traditional Japanese and Chinese medicine to treat several symptoms and manifests anti-inflammatory and scavenging effects. Nonalcoholic fatty liver disease (NAFLD) is a common manifestation of the metabolic syndrome and has the potential to evolve to liver cirrhosis through chronic inflammation and steatohepatisis (NASH). We have recently reported the KBG significant effectiveness on liver injury in a NASH animal model that prompted us to prescribe to KBG (TJ-25). We performed a retrospective study and reviewed the charts of outpatients who were prescribed KBG for 8-12 weeks due to non-liver-related symptoms (n= 11) over the past year to evaluate the clinical outcome. In six of these cases, biochemical and ultrasound signs of NAFLD were observed. KBG led to a significant reduction in liver injury tests and blood cholesterol but had no effects on body weight in all NAFLD cases. Further, liver tests and lipid profiles returned to baseline values when KBG treatment was stopped. On the basis of data on a small number of subjects, we suggest that the use of KBG is a safe complementary treatment in patients with NAFLD. While it is unlikely that Kampo formulas may substitute the current nutritional approaches to the metabolic syndrome, future studies should address the possibility of an additive effect, possibly through anti-inflammatory mechanisms.

Background: Interleukin (IL)-12 is a proinflammatory cytokine produced by antigen-presenting cells upon stimulation by diverse stimuli. This study aimed to explore the relationship between IL-12 serum levels and different stages of alcoholic liver disease, alcoholic intake status and abstinence from alcohol., Methods: A total of 35 healthy controls without alcohol consumption and 94 patients with alcoholic liver disease (17 with alcoholic steatosis, 37 with alcoholic hepatitis, 40 with alcoholic cirrhosis) were included. Their serum IL-12 levels were measured and followed-up at the 3(rd), 6(th) and 9(th) months. Data were further analyzed according to abstinence from alcohol or not., Results: Mean serum IL-12 levels were higher in the alcoholic hepatitis group (163.1 +/- 57.8 pg/mL) than in the alcoholic liver cirrhosis group (110.5 +/- 41.6 pg/mL) and alcoholic steatosis group (74.4 +/- 26.2 pg/mL). All of these 3 alcoholic groups had higher serum IL-12 levels than the control group (39.3 +/- 8.3 pg/mL; p < 0.02). Among the patients who abstained from alcohol, there was no difference in serum IL-12 levels between control and steatosis patients at the 9(th) month, but the serum IL-12 levels of the hepatitis and cirrhosis groups were still higher than in the control group (p < 0.001 and p = 0.001, respectively). In addition, the patients who continued to drink alcohol had higher serum IL-12 levels than those who abstained from alcohol in the steatosis, hepatitis and cirrhosis groups. At the cut-off value of 54 pg/mL, IL-12 had good sensitivity and specificity in the diagnosis of alcoholic liver disease., Conclusion: Serum IL-12 levels reflected the different stages of alcoholic liver disease and can represent the status of continuous alcohol consumption. It has the potential to be a biomarker of alcoholic liver disease., (Copyright 2010 Elsevier. Published by Elsevier B.V. All rights reserved.)

Aim: To investigate the macrophage migration inhibitory factor (MIF) expression and -173 G/C polymorphism of the MIF gene in nonalcoholic fatty liver disease (NAFLD)., Method: Ninety-one patients with diagnosis of NAFLD and 104 healthy controls were included in the study. MIF -173 G/C polymorphism was detected using the PCR-restriction fragment length polymorphism based method. NAFLD was stratified as nonalcoholic steatohepatitis (NASH), probable NASH and steatosis, respectively in groups 1, 2 and 3, according to NAFLD Activity Score. MIF expression was detected by immunohistochemistry staining., Results: Mean age of the patients was 50.1+/-9.6 years, and 54 of them were male. Serum alanine aminotransferase and aspartate aminotransferase were 50/83, 42/63 and 31/32, respectively in groups 1, 2 and 3, (P<0.05). Both the MIF expression of hepatocytes and mononuclear cells were more prominent in groups 1 and 2 than group 3. There was no correlation between MIF expression of hepatocytes and fibrosis stage. However, MIF expression of mononuclear cells significantly increased according to fibrosis stage (P<0.05, R : 0.2). There was no significant correlation between MIF genotype and MIF expression in the liver., Conclusion: MIF expression is significantly increased especially by mononuclear cells in liver tissue of patients with NASH secondary to inflammation. Thus, it should be considered as a consequence not a causal factor.

The article describes a positive effect of adjuvant therapy (diet therapy, tsitrarginin, trental) on regression of fatty liver disease, inflammation and prevention of liver fibrosis through influence on the system of L-arginine-NO, exchange of collagen proteins, anti-inflammatory cytokines in patients with steatohepatitis and second type diabetes mellitus.

Unlabelled: Stress-induced soluble major histocompatibility complex class I-related chains A/B (MIC A/B) are increased in chronic liver diseases and hepatocellular malignancy. We investigated the impact of these molecules on liver injury, apoptosis, and fibrosis in nonalcoholic steatohepatitis (NASH). Blood and liver tissue were obtained from 40 patients with NASH undergoing bariatric surgery for obesity. The control group consisted of 10 healthy individuals. We also investigated 10 patients with nonalcoholic fatty liver (NAFL). Polymerase chain reaction was used to measure messenger RNA (mRNA) transcripts of MIC A/B, natural killer cell receptor G2D (NKG2D), CD95/Fas, and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-death receptor 5 (DR5). Apoptosis was quantified by way of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) (intrahepatic) and M30/M65 (systemic). Liver injury was assessed histopathologically and serologically (alanine aminotransferase/aspartate aminotransferase). Fibrosis was identified by Sirius red staining, quantitative morphometry, and alpha-smooth muscle actin and collagen 1alpha transcripts. Compared with controls, patients with NASH revealed significant increases in (1) NKG2D mRNA (13.1-fold) and MIC A/B mRNA (3.6-fold and 15.8-fold, respectively); (2) TRAIL-DR5 and CD95/Fas mRNA (2.7-fold and 3.6-fold, respectively); (3) TUNEL-positive hepatocytes (4.0-fold); and (4) M30 and M65 levels (4.6-fold and 3.4-fold, respectively). We found relevant correlations between MIC protein expression rates and NAS and fibrosis stages. In contrast, NKG2D and MIC A/B transcripts were attenuated in patients with NAFL compared with NASH. Histopathologically, NASH patients revealed increased NAS scores, an accumulation of natural killer cells, and 2.7-fold increased hepatic fibrosis by quantitative morphometry., Conclusion: Our findings suggest an important role for MIC A/B in liver injury. Therapeutic intervention aimed at reducing MIC A/B levels may beneficially affect the progression of NASH.

Unlabelled: Hepatosteatosis is associated with increased expression of tumor necrosis factor alpha (TNF-alpha) and interleukin (IL)-12, major T helper (Th) 1 cytokines, and reduced hepatic natural killer T (NKT) cell numbers. The relationship between lipid accumulation, cytokine expression, and hepatic NKT cells is not known. This study was conducted to assess the role of IL-12 in the development of hepatic steatosis and its potential impact on liver NKT cells. Male C57Bl/6 wildtype (WT) and IL-12-deficient (IL-12(-/-)) mice were fed a choline-deficient diet (CDD) for 0, 10, or 20 weeks. CDD led to marked hepatosteatosis, reduced hepatic but not splenic NKT cell numbers and function, and increased hepatic expression of the T(h)1-type cytokines IL-12, interferon gamma (IFN-gamma), and TNF-alpha in WT mice. The absence of IL-12 resulted in similar CDD-induced hepatosteatosis, but preserved hepatic NKT cells and significantly reduced hepatic IFN-gamma and TNF-alpha expression. Treatment of CDD-fed mice with lipopolysaccharide led to a significant increase in hepatic IL-12 expression, and Kupffer cell (KC) depletion reduced liver IL-12 expression and restored NKT cells in CDD-induced fatty liver. Interestingly, KCs from CDD-fed mice failed to produce increased quantities of IL-12 upon activation in vitro when compared to similarly treated KCs from control fed mice, suggesting that secondary factors in vivo promote heightened IL-12 production. Finally, human livers with severe steatosis showed a substantial decrease in NKT cells., Conclusion: Hepatosteatosis reduces the numbers of hepatic NKT cells in a KC-and IL-12-dependent manner. Our results suggest a pivotal and multifunctional role of KC-derived IL-12 in the altered immune response in steatotic liver, a process that is likely active within human nonalcoholic fatty liver disease.

Autoimmune diseases of the liver are chronic inflammatory processes leading to injury of hepatocytes and cholangiocytes. Cell death by apoptosis is a prominent feature in a variety of liver diseases. It is likely that apoptosis is the initial cellular response to liver and biliary injury and may thus initiate several cellular and cytokine cascades. Obviously, this cascade of events is of particular clinical importance. This short overview will focus on the role of apoptosis in immune-mediated liver diseases. Recently, also soluble forms of major histocompatibility complex class I-related chains A and closely related B (MIC A and B) were reported to be increased in the sera of patients with autoimmune and cholestatic liver diseases, and also in non-alcoholic steatohepatitis. MIC A and B are cell surface glycoproteins that function as indicators for cellular stress by displaying peptides derived from proteins degraded in the cytosol on the cell surface, and thus facilitate the recognition of intracellular antigens by circulating cytotoxic natural killer cells, leading to enhanced cell death. Nowadays rational-based strategies are being developed to suppress apoptotic cell death as a novel therapeutic option for the treatment of these liver diseases., (Copyright 2010 S. Karger AG, Basel.)

Nonalcoholic fatty liver disease (NAFLD) is rapidly becoming a world-wide public health problem. NAFLD represents a spectrum of disease ranging from "simple steatosis", which is considered relatively benign, to nonalcoholic steatohepatitis and to NAFLD-associated cirrhosis and end-stage liver disease. The etiology of NAFLD and its progression is complex and remains incompletely understood. The progression of the disease involves many factors. Apart from the two hits, the accumulation of TG and the development of fibrosis and necroinflammatory processes, exit numerous molecules associated with these two hits. Among them we can highlight the pro-inflammatory molecules and adiponectins. This review focuses on the growing evidence from both experimental and human studies suggesting a central role of cytokines in the pathogenesis of NAFLD. We review the role of cytokines as key regulators of insulin sensitivity and hepatic lipid overloading, liver injury and inflammation, and fibrosis with an emphasis on potential therapeutic implications.

Background/aims: Chemokines are small chemotactic molecules which regulate the infiltration of immune cells to sites of inflammatory injury. In recent years their contribution to the initiation and perpetuation of liver injury has been better defined. However, the role of chemokines in liver diseases related to the metabolic syndrome still needs to be elucidated in detail., Methods: Chemokines were mostly detected at the mRNA level in the liver and as proteins in the serum of patients with non-alcoholic steatohepatitis (NASH) or fatty liver. Animals with targeted deletion of chemokines have recently been subjected to NASH models to functionally dissect the role of chemokines in fatty liver diseases., Results: In human liver with features of NASH, different CC and CXC chemokines have been detected at elevated mRNA levels in comparison to healthy subjects. Some of these chemokines have also been associated with NASH by demonstrating higher serum levels in affected patients. Until now, only a few animal models have been analyzed with respect to the functional role of these molecules. However, data from CCL2 and CXCR3 knockout mice suggest that these pathways are important in liver injury. CCL2 seems to influence the infiltration of macrophages to adipose tissue and thereby modulate insulin resistance., Conclusions: The further elucidation of the pathophysiology of NASH will lead to new therapeutic options to halt or reverse progressive liver disease. In this respect, chemokines are attractive target molecules, as they influence immunologic and metabolic pathways and the first oral chemokine receptor antagonists have already been licensed for humans., (Copyright 2010 S. Karger AG, Basel.)

Objective: Atherosclerosis is a chronic inflammatory disease of major conduit arteries. Similarly, obesity and type 2 diabetes mellitus are associated with accumulation of macrophages in visceral white adipose tissue and pancreatic islets. Our goal was to characterize systemic inflammation in atherosclerosis with hypercholesterolemia, but without obesity., Methods and Results: We compared 22-week-old apolipoprotein E knockout (ApoE(-/-)) with wild-type mice kept for 14 weeks on a high cholesterol (1.25%) diet (CD, n=8) and 8-week-old ApoE(-/-) with wild-type mice kept on a normal diet (ND, n=8). Hypercholesterolemic, atherosclerotic ApoE(-/-) mice on CD exhibited increased macrophages and T-cells in plaques and periadventitial adipose tissue that revealed elevated expression of MIP-1alpha, IL-1beta, IL-1 receptor, and IL-6. Mesenteric adipose tissue and pancreatic islets in ApoE(-/-) mice showed increased macrophages. Expression of IL-1beta was enhanced in mesenteric adipose tissue of ApoE(-/-) mice on CD. Furthermore, these mice exhibited steatohepatitis with macrophage and T-cell infiltrations as well as increased MIP-1alpha and IL-1 receptor expression. Blood glucose, insulin and total body weight did not differ between the groups., Conclusions: In hypercholesterolemic lean ApoE(-/-) mice, inflammation extends beyond atherosclerotic plaques to the periadventitial and visceral adipose tissue, liver, and pancreatic islets without affecting glucose homeostasis.

Unlabelled: Activation of the innate immune system plays a major role in nonalcoholic fatty liver disease (NAFLD). The complement system is an important component of innate immunity that recognizes danger signals such as tissue injury. We aimed to determine whether activation of the complement system occurs in NAFLD, to identify initiating pathways, and to assess the relation between complement activation, NAFLD severity, apoptosis, and inflammatory parameters. Liver biopsies of 43 obese subjects with various degrees of NAFLD and of 10 healthy controls were analyzed for deposition of complement factors C1q, mannose-binding lectin (MBL), C4d, activated C3, and membrane attack complex (MAC)-associated C9. Furthermore, hepatic neutrophil infiltration, apoptosis, and pro-inflammatory cytokine expression were quantified. Whereas complement activation was undetectable in the liver of healthy subjects, 74% of the NAFLD patients showed hepatic deposition of activated C3 and C4d. C1q as well as MBL accumulation was found in most activated C3-positive patients. Strikingly, 50% of activated C3-positive patients also displayed MAC-associated C9 deposition. Deposition of complement factors was predominantly seen around hepatocytes with macrovesicular steatosis. Subjects showing accumulation of activated C3 displayed increased numbers of apoptotic cells. Importantly, hepatic neutrophil infiltration as well as interleukin (IL)-8 and IL-6 expression was significantly higher in patients showing activated C3 deposition, whereas patients with C9 deposition additionally had increased IL-1beta expression. Moreover, nonalcoholic steatohepatitis (NASH) was more prevalent in patients showing hepatic C9 or activated C3 deposition., Conclusion: There is widespread activation of the complement system in NAFLD, which is associated with disease severity. This may have important implications for the pathogenesis and progression of NAFLD given the function of complement factors in clearance of apoptotic cells, hepatic fibrosis, and liver regeneration.

Hepatic steatosis is a risk factor for the progression of non-alcoholic fatty liver disease. The role of pro-inflammatory interleukin (IL)-6 in hepatic steatosis etiology is controversial. We investigated in vivo and in primary hepatocyte cultures whether IL-6 has a modulator role in liver and mitochondria lipid composition and cell death in a choline-deficient (CD) diet rat model of hepatic steatosis. Dietary choline deficiency increased triglycerides and cholesterol, and reduced phosphatidylcholine (PC), phosphatidylethanolamine (PE) and the membrane integrity marker PC:PE ratio in liver. Choline-deficient diet enhanced systemic IL-6, and IL-6 receptor expression and cell death vulnerability in hepatocytes. Derangement of the mitochondrial electron transport chain and of its phospholipid environment was found in CD rat liver mitochondria, which exhibited elevated concentrations of triglycerides, cardiolipin and PC and elevated PC:PE ratio. The cell treatment with IL-6, but not PC, eliminated much of the CD-promoted lipid imbalance in mitochondria but not tumor-necrosis factor (TNF)-alpha-induced cell death. However, PC supplementation prevented the TNF-alpha-induced DNA fragmentation, cytochrome-c release and caspase-3 activity in control and CD hepatocytes. In conclusion, IL-6 ameliorated the mitochondria lipid disturbance in hepatocytes isolated from steatotic animals. Furthermore, PC is identified as a new survival agent that reverses several TNFalpha-inducible responses that are likely to promote steatosis and necrosis.