Localization of oxidized phosphatidylcholine in nonalcoholic fatty liver disease: impact on disease progression

Peroxisome proliferator-activated receptors as targets to treat non-alcoholic fatty liver disease

Lately, the world has faced tremendous progress in the understanding of non-alcoholic fatty liver disease (NAFLD) pathogenesis due to rising obesity rates. Peroxisome proliferator-activated receptors (PPARs) are transcription factors that modulate the expression of genes involved in lipid metabolism, energy homeostasis and inflammation, being altered in diet-induced obesity. Experimental evidences show that PPAR-alpha is the master regulator of hepatic beta-oxidation (mitochondrial and peroxisomal) and microsomal omega-oxidation, being markedly decreased by high-fat (HF) intake. PPAR-beta/delta is crucial to the regulation of forkhead box-containing protein O subfamily-1 expression and, hence, the modulation of enzymes that trigger hepatic gluconeogenesis. In addition, PPAR-beta/delta can activate hepatic stellate cells aiming to the hepatic recovery from chronic insult. On the contrary, PPAR-gamma upregulation by HF diets maximizes NAFLD through the induction of lipogenic factors, which are implicated in the fatty acid synthesis. Excessive dietary sugars also upregulate PPAR-gamma, triggering de novo lipogenesis and the consequent lipid droplets deposition within hepatocytes. Targeting PPARs to treat NAFLD seems a fruitful approach as PPAR-alpha agonist elicits expressive decrease in hepatic steatosis by increasing mitochondrial beta-oxidation, besides reduced lipogenesis. PPAR-beta/delta ameliorates hepatic insulin resistance by decreasing hepatic gluconeogenesis at postprandial stage. Total PPAR-gamma activation can exert noxious effects by stimulating hepatic lipogenesis. However, partial PPAR-gamma activation leads to benefits, mainly mediated by increased adiponectin expression and decreased insulin resistance. Further studies are necessary aiming at translational approaches useful to treat NAFLD in humans worldwide by targeting PPARs.

Dysregulation of iron and copper homeostasis in nonalcoholic fatty liver

Elevated iron stores as indicated by hyperferritinemia with normal or mildly elevated transferrin saturation and mostly mild hepatic iron deposition are a characteristic finding in subjects with non-alcoholic fatty liver disease (NAFLD). Excess iron is observed in approximately one third of NAFLD patients and is commonly referred to as the “dysmetabolic iron overload syndrome”. Clinical evidence suggests that elevated body iron stores aggravate the clinical course of NAFLD with regard to liver-related and extrahepatic disease complications which relates to the fact that excess iron catalyses the formation of toxic hydroxyl-radicals subsequently resulting in cellular damage. Iron removal improves insulin sensitivity, delays the onset of type 2 diabetes mellitus, improves pathologic liver function tests and likewise ameliorates NAFLD histology. Several mechanisms contribute to pathologic iron accumulation in NAFLD. These include impaired iron export from hepatocytes and mesenchymal Kupffer cells as a consequence of imbalances in the concentrations of iron regulatory factors, such as hepcidin, cytokines, copper or other dietary factors. This review summarizes the knowledge about iron homeostasis in NAFLD and the rationale for its therapeutic implications.

Transitions of histopathologic criteria for diagnosis of nonalcoholic fatty liver disease during the last three decades

Nonalcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome, and is the most common type of chronic liver diseases in the majority of developed countries. NAFLD shows a wide spectrum of disorders including simple steatosis, nonalcoholic steatohepatitis (NASH), and cirrhosis. While simple steatosis is recognized to be benign and stable, NASH is considered to be an aggressive form of the disease progressing to cirrhosis. Currently, differentiation between NASH and simple steatosis can be done only by liver biopsy. Despite many proposals and revisions, the histological criteria for the differentiation have not been perfected yet. In this review article, the changes in the histopathologic criteria of NAFLD during the last three decades are summarized, and perspectives of the future changes are demonstrated. The discussion focuses on how pathologists have been dealing with “hepatocellular ballooning”. Loose criteria, in which hepatocellular ballooning was not required for the diagnosis of NASH, were applied in many clinical studies published in around 2000’s, whereas a strict criterion based on the presence/absence of hepatocellular ballooning was approved recently. Hence, simple and reliable methods of identifying ballooned hepatocytes are being sought. Clinical and pathological predictors of NAFLD-related hepatocarcinogenesis will also be sought in the future.

Transcriptome analysis on the inflammatory cell infiltration of nonalcoholic steatohepatitis in bama minipigs induced by a long-term high-fat, high-sucrose diet

Long-term adherence to a high-fat, high-calorie diet influences human health and causes obesity, metabolic syndrome and nonalcoholic steatohepatitis (NASH). Inflammation plays a key role in the development of NASH; however, the mechanism of inflammation induced by over-nutrition remains largely unknown. In this study, we fed Bama minipigs a high-fat, high-sucrose diet (HFHSD) for 23 months. The pigs exhibited characteristics of metabolic syndrome and developed steatohepatitis with greatly increased numbers of inflammatory cells, such as lymphocytes (2.27-fold, P<0.05), Kupffer cells (2.59-fold, P<0.05), eosinophils (1.42-fold, P<0.05) and neutrophils (2.77-fold, P<0.05). High-throughput RNA sequencing (RNA-seq) was performed to explore the systemic transcriptome of the pig liver during inflammation. Approximately 18.2 gigabases of raw sequence data were generated, and over 303 million high-quality reads were assembled into 21,126 unigenes. RNA-seq data analysis showed that 822 genes were differentially expressed in liver (P<0.05) between the HFHSD and control groups. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the process of inflammation involved the inflammatory signal transduction-related toll-like receptor, MAPK, and PPAR signaling pathways; the cytokine-related chemokine signaling, cytokine-cytokine receptor interaction, and IL2, IL4, IL6, and IL12 signaling pathways; the leukocyte receptor signaling-related T cell, B cell, and natural killer cell signaling pathways; inflammatory cell migration and invasion- related pathways; and other pathways. Moreover, we identified several differentially expressed inflammation-related genes between the two groups, including FOS, JUN, TLR7, MYC, PIK3CD, VAV3, IL2RB and IL4R, that could be potential targets for further investigation. Our study suggested that long-term HFHSD induced obesity and liver inflammation, providing basic insight into the molecular mechanism of this condition and laying the groundwork for further studies on obesity and steatohepatitis.

Complement alternative pathway activation in human nonalcoholic steatohepatitis

The innate immune system plays a major role in the pathogenesis of nonalcoholic steatohepatitis (NASH). Recently we reported complement activation in human NASH. However, it remained unclear whether the alternative pathway of complement, which amplifies C3 activation and which is frequently associated with pathological complement activation leading to disease, was involved. Here, alternative pathway components were investigated in liver biopsies of obese subjects with healthy livers (n = 10) or with NASH (n = 12) using quantitative PCR, Western blotting, and immunofluorescence staining. Properdin accumulated in areas where neutrophils surrounded steatotic hepatocytes, and colocalized with the C3 activation product C3c. C3 activation status as expressed by the C3c/native C3 ratio was 2.6-fold higher (p<0.01) in subjects with NASH despite reduced native C3 concentrations (0.94±0.12 vs. 0.57±0.09; p<0.01). Hepatic properdin levels positively correlated with levels of C3c (r_s = 0.69; p<0.05) and C3c/C3 activation ratio (r_s = 0.59; p<0.05). C3c, C3 activation status (C3c/C3 ratio) and properdin levels increased with higher lobular inflammation scores as determined according to the Kleiner classification (C3c: p<0.01, C3c/C3 ratio: p<0.05, properdin: p<0.05). Hepatic mRNA expression of factor B and factor D did not differ between subjects with healthy livers and subjects with NASH (factor B: 1.00±0.19 vs. 0.71±0.07, p = 0.26; factor D: 1.00±0.21 vs. 0.66±0.14, p = 0.29;). Hepatic mRNA and protein levels of Decay Accelerating Factor tended to be increased in subjects with NASH (mRNA: 1.00±0.14 vs. 2.37±0.72; p = 0.22; protein: 0.51±0.11 vs. 1.97±0.67; p = 0.28). In contrast, factor H mRNA was downregulated in patients with NASH (1.00±0.09 vs. 0.71±0.06; p<0.05) and a similar trend was observed with hepatic protein levels (1.12±0.16 vs. 0.78±0.07; p = 0.08). Collectively, these data suggest a role for alternative pathway activation in driving hepatic inflammation in NASH. Therefore, alternative pathway factors may be considered attractive targets for treating NASH by inhibiting complement activation.

Lipid peroxidation generates biologically active phospholipids including oxidatively N-modified phospholipids

Peroxidation of membranes and lipoproteins converts "inert" phospholipids into a plethora of oxidatively modified phospholipids (oxPL) that can act as signaling molecules. In this review, we will discuss four major classes of oxPL: mildly oxygenated phospholipids, phospholipids with oxidatively truncated acyl chains, phospholipids with cyclized acyl chains, and phospholipids that have been oxidatively N-modified on their headgroups by reactive lipid species. For each class of oxPL we will review the chemical mechanisms of their formation, the evidence for their formation in biological samples, the biological activities and signaling pathways associated with them, and the catabolic pathways for their elimination. We will end by briefly highlighting some of the critical questions that remain about the role of oxPL in physiology and disease.

Experimental nonalcoholic fatty liver disease in mice leads to cytochrome p450 2a5 upregulation through nuclear factor erythroid 2-like 2 translocation

Mouse cytochrome P450 2A5 (CYP2A5) is upregulated in various liver diseases and a putative common feature for all of these conditions is altered cellular redox status. Nuclear factor erythroid 2-like 2 (Nrf2) is a transcription factor that is post-translationally regulated by oxidative stress and controls the transcription of protective target genes. In the present study, we have characterized the regulation of CYP2A5 by Nrf2 and evaluated gene expression, protein content and activity of anti-oxidant enzymes in the Nrf2^+/+ and Nrf2^−/− mice model of non-alcoholic fatty liver (NAFLD). After eight weeks of feeding on a high-fat diet, livers from Nrf2^−/− mice showed a substantial increase in macro and microvesicular steatosis and a massive increase in the number of neutrophil polymorphs, compared to livers from wild-type mice treated similarly. Livers of Nrf2^−/− mice on the high-fat diet exhibited more oxidative stress than their wild-type counterparts as assessed by a significant depletion of reduced glutathione that was coupled with increases in malondialdehyde. Furthermore, results in Nrf2-deficient mice showed that CYP2A5 expression was significantly attenuated in the absence of Nrf2, as was found with the conventional target genes of Nrf2. The treatment of wild-type mice with high-fat diet leaded to nuclear accumulation of Nrf2, and co-immunoprecipitation experiments showed that Nrf2 was bound to Cyp2a5. These findings suggest that the high-fat diet induced alteration in cellular redox status and induction of CYP2A5 was modulated through the redox-sensitive transcription Nrf2.

•

CYP2A5 up-regulation in response to NAFLD was Nrf2 dependent.

•

NAFLD induces oxidant stress.

•

A protective role for Nrf2 against hepatic damage by NAFLD was demonstrated.

•

NAFLD induces translocation of Nrf2 from the cytoplasm to the nucleus.

•

Nrf2 binding to CYP2a5 was shown.

Suppression of Toll-like receptor 4 activation by endogenous oxidized phosphatidylcholine, KOdiA-PC by inhibiting LPS binding to MD2

OBJECTIVE

Activation of Toll-like receptor 4 (TLR4) triggers immune and inflammatory events by sensing endogenous danger signals as well as invading pathogens and contributes to the development of chronic inflammatory diseases. In this study, we investigated effect of 1-palmitoyl-2-(5-keto-6-octenedioyl)-sn-glycero-3-phosphocholine (KOdiA-PC), an oxidized phosphatidylcholine, on TLR4 activation and the underlying regulatory mechanism.

METHODS

RAW264.7 macrophages were used for the study. The levels of TNF-α, IFN-β, and COX-2 mRNA and protein were determined by quantitative PCR and ELISA, respectively. Activation of TLR4-signaling was examined by immunoblot and luciferase reporter assays. In vitro binding assay was performed to determine LPS binding to MD2. Macrophage migration was analyzed using a transwell-culture system.

RESULTS

KOdiA-PC prevented the activation of TLR4-signaling components including ERK, JNK, p38, NF-κB, and IRF3 leading to decrease of TNF-α, IFN-β, and COX-2 expression. In vitro binding assay revealed that KOdiA-PC interrupted LPS binding to MD2, a TLR4 co-receptor. Consistently, KOdiA-PC suppressed LPS-induced macrophage migration.

CONCLUSION

The results demonstrate that KOdiA-PC can modulate TLR4 activation by regulating ligand-receptor interaction. Therefore, endogenously generated, oxidized phospholipids may play a role in resolving inflammation by terminating TLR activation and macrophage recruitment to the inflamed site.

Association between insulin resistance and oxidative stress parameters in obese adolescents with non-alcoholic fatty liver disease

OBJECTIVE

Non-alcoholic fatty liver disease (NAFLD) has become one of the most common chronic liver diseases in children. The aim of this study was to investigate the associations of oxidative stress with insulin resistance and metabolic risk factors in obese adolescents with NAFLD.

METHODS

Forty-six obese adolescents (23 girls and 23 boys, mean age: 12.8 ± 2.2 years) and 29 control subjects (15 girls and 14 boys, mean age: 12.7 ± 2.7 years) were enrolled in the study. The obese subjects were divided into two groups (NAFLD group and non-NAFLD group) based on the elevated alanine aminotransferase levels (>30 IU/L) and the presence or absence of liver steatosis detected by ultrasonography. Insulin resistance was evaluated by homeostasis model assessment (HOMA-IR) from fasting samples. Plasma total antioxidant status (TAS) and total oxidant status (TOS) level measurements (REL Assay Diagnostics) were done in all participants. The ratio of TOS to TAS was regarded as an oxidative stress index (OSI), an indicator of the degree of OS.

RESULTS

Fasting insulin levels and HOMA-IR values in the NAFLD group were significantly higher than in the non-NAFLD and control groups. TAS measurements were decreased in both obese groups (NAFLD and non-NAFLD) in comparison with the control group. TOS and OSI measurements were higher in the NAFLD group than in the non-NAFLD and control groups. OSI was positively correlated with fasting insulin (r=0.67, p=0.01) and HOMA-IR (r=0.71, p=0.02) in the NAFLD obese group.

CONCLUSIONS

In this cross-sectional study, elevated OS markers in obese adolescents with NAFLD were associated with insulin resistance. This data suggest that an antioxidant therapy might have a potential for treating NAFLD associated with insulin resistance.

A murine model for non-alcoholic steatohepatitis showing evidence of association between diabetes and hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the third most common cause of cancer-related deaths. In addition to hepatitis viral infections, several cohort studies have shown that diabetes mellitus is a risk factor of HCC, making the incidence alarming high. However, it has not been demonstrated directly how diabetes develops to HCC, because of its difficulty to follow changes of liver histology in diabetic populations. Here, we report that non-alcoholic steatohepatitis (NASH) is pivotal to link diabetes with HCC by establishing a novel, reproducible NASH-HCC model in mice. Neonatal male mice exposed to low-dose streptozotocin (STZ) developed liver steatosis with diabetes 1 week after feeding high-fat diet (HFD). Continuous HFD decreased hepatic fat deposit whilst increased lobular inflammation with foam cell-like macrophages, showing NASH pathology. In parallel with decreased phagocytosis of macrophages, fibroblasts accumulated to form "chicken-wired" fibrosis. All mice developed multiple HCC later. Female mice treated with STZ-HFD and male mice treated with STZ alone showed diabetes but never developed HCC by the absence of NASH-based fibrosis. Thus, the present study provides the evidence in novel mouse model that NASH-based fibrosis is an essential histological process for diabetic populations to accelerate the development of HCC.

High-density lipoprotein and 4F peptide reduce systemic inflammation by modulating intestinal oxidized lipid metabolism: novel hypotheses and review of literature

Oxidized phospholipids are found in the vasculature of animal models of atherosclerosis, in human atherosclerotic lesions, and in other inflammatory diseases. Oxidized phospholipids cause vascular and nonvascular cells to initiate an inflammatory reaction. Metabolites of arachidonic acid, such as 12-hydroxyeicosatetraenoic acid, can mimic some of the inflammatory properties of oxidized phospholipids. In vitro and in vivo normal high-density lipoprotein (HDL), normal apolipoprotein A-I, and apolipoprotein A-I mimetic peptides, each likely acting in a different manner, prevent the inflammatory reaction characteristic of atherosclerosis, and this is associated with decreased levels of oxidized lipids in tissues and cells. HDL from animal models of atherosclerosis or from humans with atherosclerosis or from humans or animals with other chronic inflammatory diseases does not prevent the inflammatory reaction characteristic of atherosclerosis and may even enhance the inflammatory reaction. In mice and perhaps humans, ≈30% of the steady-state plasma HDL-cholesterol pool is derived from the small intestine. The metabolism of phospholipids by gut bacteria has been recently implicated in atherosclerosis in both mice and humans. Studies with apolipoprotein A-I mimetic peptides suggest that the small intestine is a major tissue regulating systemic inflammation in mouse models of atherosclerosis and may be important for determining the functionality of HDL.

Neutrophil-derived myeloperoxidase aggravates non-alcoholic steatohepatitis in low-density lipoprotein receptor-deficient mice

Background

Chronic inflammation and oxidative stress play fundamental roles in the pathogenesis of non-alcoholic steatohepatitis (NASH). Previously, we reported that myeloperoxidase (MPO), an aggressive oxidant-generating neutrophil enzyme, is associated with NASH severity in man. We now investigated the hypothesis that MPO contributes to the development and progression of NASH.

Methodology

Low-density lipoprotein receptor-deficient mice with an MPO-deficient hematopoietic system (LDLR^−/−/MPO^−/−tp mice) were generated and compared with LDLR^−/−/MPO^+/+tp mice after induction of NASH by high-fat feeding.

Results

High-fat feeding caused a ∼4-fold induction of liver MPO in LDLR^−/−/MPO^+/+ mice which was associated with hepatic sequestration of MPO-positive neutrophils and high levels of nitrotyrosine, a marker of MPO activity. Importantly, LDLR^−/−/MPO^−/−tp mice displayed markedly reduced hepatic neutrophil and T-lymphocyte infiltration (p<0.05), and strong down regulation of pro-inflammatory genes such as TNF-α and IL-6 (p<0.05, p<0.01) in comparison with LDLR^−/−/MPO^+/+tp mice. Next to the generalized reduction of inflammation, liver cholesterol accumulation was significantly diminished in LDLR^−/−/MPO^−/−tp mice (p = 0.01). Moreover, MPO deficiency appeared to attenuate the development of hepatic fibrosis as evident from reduced hydroxyproline levels (p<0.01). Interestingly, visceral adipose tissue inflammation was markedly reduced in LDLR^−/−/MPO^−/−tp mice, with a complete lack of macrophage crown-like structures. In conclusion, MPO deficiency attenuates the development of NASH and diminishes adipose tissue inflammation in response to a high fat diet, supporting an important role for neutrophils in the pathogenesis of metabolic disease.

Specific immunization strategies against oxidized low-density lipoprotein: a novel way to reduce nonalcoholic steatohepatitis in mice

Nonalcoholic steatohepatitis (NASH) is characterized by hepatic lipid accumulation combined with inflammation, which can ultimately progress into cirrhosis. Recently, we demonstrated that deletion of scavenger receptors (SRs) CD36 and SR-A in hematopoietic cells reduced hepatic inflammation. In addition to uptake of modified lipoproteins, CD36 and SR-A are also involved in other functions that can activate the inflammatory response. Therefore, the actual trigger for SR activation during NASH is unclear. Here, we hypothesized that hepatic inflammation is triggered by recognition of oxidized LDL (oxLDL) by Kupffer cells (KCs). To inhibit recognition of oxLDL by KCs, low-density lipoprotein receptor (Ldlr(-/-) ) mice were immunized with heat-inactivated pneumococci, which were shown to induce the production of anti-oxLDL immunoglobulin M (IgM) antibodies, due to molecular mimicry with oxLDL. The mice received a high-fat, high-cholesterol diet during the last 3 weeks to induce NASH. Immunization with pneumococci increased anti-oxLDL IgM levels and led to a reduction in hepatic inflammation, as shown by reduced macrophage, neutrophil, and T cell infiltration, and reduced gene expression of tumor necrosis factor (Tnf), interleukin-6 (Il-6), interleukin-1β (Il-1b), monocyte chemoattractant protein 1 (Mcp1), and fibrosis-related genes. In immunized mice, KCs were smaller and showed fewer cholesterol crystals compared with nonimmunized mice.

CONCLUSION

Antibodies to oxLDL play an important role in the pathogenesis of NASH. Therefore, the potential of phosphorylcholine-based vaccination strategies as a novel tool for the prevention and therapy of NASH should be tested in the future.

Silybin combined with phosphatidylcholine and vitamin E in patients with nonalcoholic fatty liver disease: a randomized controlled trial

The only currently recommended treatment for nonalcoholic fatty liver disease (NAFLD) is lifestyle modification. Preliminary studies of silybin showed beneficial effects on liver function. Realsil (RA) comprises the silybin phytosome complex (silybin plus phosphatidylcholine) coformulated with vitamin E. We report on a multicenter, phase III, double-blind clinical trial to assess RA in patients with histologically documented NAFLD. Patients were randomized 1:1 to RA or placebo (P) orally twice daily for 12 months. Prespecified primary outcomes were improvement over time in clinical condition, normalization of liver enzyme plasma levels, and improvement of ultrasonographic liver steatosis, homeostatic model assessment (HOMA), and quality of life. Secondary outcomes were improvement in liver histologic score and/or decrease in NAFLD score without worsening of fibrosis and plasma changes in cytokines, ferritin, and liver fibrosis markers. We treated 179 patients with NAFLD; 36 were also HCV positive. Forty-one patients were prematurely withdrawn and 138 patients analyzed per protocol (69 per group). Baseline patient characteristics were generally well balanced between groups, except for steatosis, portal infiltration, and fibrosis. Adverse events (AEs) were generally transient and included diarrhea, dysgeusia, and pruritus; no serious AEs were recorded. Patients receiving RA but not P showed significant improvements in liver enzyme plasma levels, HOMA, and liver histology. Body mass index normalized in 15% of RA patients (2.1% with P). HCV-positive patients in the RA but not the P group showed improvements in fibrogenesis markers. This is the first study to systematically assess silybin in NAFLD patients. Treatment with RA but not P for 12 months was associated with improvement in liver enzymes, insulin resistance, and liver histology, without increases in body weight. These findings warrant further investigation.

Presence and significance of microvesicular steatosis in nonalcoholic fatty liver disease

BACKGROUND & AIMS

Liver biopsies from patients with nonalcoholic fatty liver disease (NAFLD) sometimes exhibit non-zonal aggregates of hepatocytes with microvesicular steatosis, but its prevalence and significance are unclear. In this study, we have evaluated the frequency of microvesicular steatosis and assessed its association with histological markers of disease severity in a large sample of NAFLD liver biopsies.

METHODS

Liver biopsies from a large cohort of adults who participated in two studies conducted by the NASH Clinical Research Network (NASH CRN) were included in this cross-sectional study. Liver histology was assessed centrally and various histological features scored in a systematic fashion. The relationship between microvesicular steatosis and various histological features that characterize NAFLD was tested by multiple logistic regression, after controlling for age, gender, race, body mass index, and diabetes.

RESULTS

Among 1022 liver biopsies included, 102 (10%) had microvesicular steatosis. No demographic differences were noted between patients with or without microvesicular steatosis. The presence of microvesicular steatosis was associated with higher grades of steatosis (p<0.001), ballooning cell injury (p<0.001), presence of Mallory-Denk bodies (p<0.007), presence of megamitochondria (p<0.0001), higher NAS scores (p<0.0001), more advanced fibrosis (p<0.0001), and diagnosis of borderline or definite NASH (p<0.0001).

CONCLUSIONS

Microvesicular steatosis correlates with more advanced histology of NAFLD. Longitudinal studies are needed to address the role of microvesicular steatosis in mediating cellular injury and disease progression in NAFLD.

Prevalence of NAFLD in Healthy and Young Male Individuals

Introduction. Nonalcoholic fatty liver disease (NAFLD) is an important cause of liver disease in adults and the most common cause of liver disease in children (Lavine and Schwimmer 2004). The abnormalities include increased liver fat without inflammation (steatosis) and nonalcoholic steatohepatitis (NASH). NASH may lead to fibrosis, cirrhosis, and ultimately liver failure if it is not treated (Matteoni et al. 1999). The objective of the study is to estimate the magnitude of the problem which will help us to formulate strategies in managing the potentially difficult problem. Materials and Methods. We included 1000 individuals between the ages of 30 and 50 years who came for annual checkup. The patients with other comorbidities like diabetes, ischemic heart disease, chronic liver disease, or renal diseases were excluded from the study. History of alcohol ingestion was also taken; any individual with history of alcohol intake was also excluded. All of them underwent investigations including CBC, LFTs, height and weight. The individuals who were found to have increased ALT (50 to 150 u/L) further underwent investigations including ultrasound of abdomen hepatitis b and c serology RA and ANA antibodies. All the individuals who were found to have viral or autoimmune illness were excluded from the study. The individuals having raised ALT levels and ultrasound evidence of fatty liver were taken. Results. 13.5% of the individuals were found to have NAFLD among those selected for the study. Conclusion. Mass campaign regarding physical and dietary measures needs to be undertaken in general masses regarding the gravity and potential prevention of the disease.

Inflammation in nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) describes a range of disorders characterized by excess accumulation of triglyceride within the liver. While simple steatosis may be clinically stable, nonalcoholic steatohepatitis (NASH) can be progressive. Inflammation is believed to be the driving force behind NASH and the progression to fibrosis and subsequent cirrhosis. This article will review and interpret the current literature in an attempt to expand our understanding of the environmental and genetic causes of inflammation and its effects in NAFLD.

Hepatocellular ballooning in nonalcoholic steatohepatitis: the pathologist's perspective

Nonalcoholic fatty liver disease (NAFLD) is an important complication of the metabolic syndrome. The increasing prevalence of the metabolic syndrome is paralleled by an increasing prevalence of NAFLD, which has become one of the most common chronic liver diseases. NAFLD comprises a morphological spectrum ranging from nonalcoholic fatty liver (NAFL), characterized by accumulation of fat in hepatocytes, to nonalcoholic steatohepatitis (NASH). The key histological features of NASH accepted by most pathologists include steatosis, hepatocellular ballooning and lobular inflammation, whereas, like in other chronic liver diseases, the presence of fibrosis is not considered a requirement for the diagnosis. The diagnosis of NASH and the distinction from NAFL carries important prognostic and therapeutic implications because NASH, in contrast to NAFL, is associated with an increased risk of progression to cirrhosis and hepatocellular carcinoma. Hepatocellular ballooning is a key feature required for the diagnosis of NASH and a component of currently used histological grading and staging systems of NAFLD. However, it represents an ill-defined form of liver cell injury associated with cell swelling and rounding of the cytoplasm, the detection of which is prone to intra- as well as inter-observer variation. Some of the factors that may contribute to ballooning are the rearrangement of the intermediate filament cytoskeleton, accumulation of small-droplet fat in the cytoplasm and dilation of the endoplasmic reticulum. The rearrangement of the intermediate filament cytoskeleton can be demonstrated by the loss of keratin 8/18 immunostaining of the cytoplasm, and may thus be evaluated in the future as a marker for the more objective detection of hepatocellular ballooning in NASH.

Dietary cholesterol, female gender and n-3 fatty acid deficiency are more important factors in the development of non-alcoholic fatty liver disease than the saturation index of the fat

Background

The central feature of NAFLD is a disturbed fatty-acid metabolism with hepatic lipid accumulation. However, the factors that determine the severity of NAFLD, including the role of nutrition, gender, and plasma lipid levels, remain to be determined.

Methods

High-fat diets (42 en% fat), containing 0.2% cholesterol, were fed to male and female wild-type and hyperlipidemic APOE2ki C57BL/6J mice for three weeks. The fats were, in order of decreasing saturation, fractionated palm fat (fPF; ~95%), cocoa butter (CB; ~60%), olive oil (OO; ~15%), sunflower oil (SO; ~12%), and high-oleic-acid sunflower oil (hoSO; ~7%). Plasma and liver triglycerides (concentration and composition), liver inflammation (Ccl2, Cd68, Tnf-α mRNA), and infiltration of macrophages (Cd68, Cd11b immunohistochemistry) and neutrophils (Mpo) were quantified.

Results

Addition of cholesterol to a low-fat diet decreased plasma HDL and increased (V)LDL levels in APOE2ki mice. Plasma cholesterol levels in female, but not male APOE2ki mice correlated significantly with inflammation. Kupffer cells of inflamed livers were swollen. Wild-type mice refused the highly saturated fPF diet. The high-fat CB, OO, and SO diets induced hyperglycemia and a 2-fold increase in hepatic fat content in male, but not female wild-type mice (in females, hepatic fat content was similar to that in males fed a high-fat diet). All high-fat diets induced macrovesicular setatosis. APOE2ki mice were protected against high-fat diet-induced steatosis and hyperglycemia, except when fed a hoSO diet. This diet caused a 5-fold increase in liver triglyceride and mead-acid content, and an increased expression of lipogenic genes, suggesting a deficiency in poly-unsaturated fatty acids. Irrespective of the composition of the high-fat diet, oleic acid was the main triglyceride component of liver fat in wild-type and APOE2ki mouse livers. Liver inflammation was dependent on genotype (APOE2ki > wild type), gender (female > male), and cholesterol content (high > low) of the diet, but not on dietary fat composition.

Conclusions

Dietary cholesterol plays a determining, independent role in inflammation, especially in female mice. The fatty-acid saturation of the diet hardly affected hepatic steatosis or inflammation.

Liquid chromatography-mass spectrometry-based parallel metabolic profiling of human and mouse model serum reveals putative biomarkers associated with the progression of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease in most western countries. Current NAFLD diagnosis methods (e.g., liver biopsy analysis or imaging techniques) are poorly suited as tests for such a prevalent condition, from both a clinical and financial point of view. The present work aims to demonstrate the potential utility of serum metabolic profiling in defining phenotypic biomarkers that could be useful in NAFLD management. A parallel animal model/human NAFLD exploratory metabolomics approach was employed, using ultra performance liquid chromatography-mass spectrometry (UPLC-MS) to analyze 42 serum samples collected from nondiabetic, morbidly obese, biopsy-proven NAFLD patients, and 17 animals belonging to the glycine N-methyltransferase knockout (GNMT-KO) NAFLD mouse model. Multivariate statistical analysis of the data revealed a series of common biomarkers that were significantly altered in the NAFLD (GNMT-KO) subjects in comparison to their normal liver counterparts (WT). Many of the compounds observed could be associated with biochemical perturbations associated with liver dysfunction (e.g., reduced Creatine) and inflammation (e.g., eicosanoid signaling). This differential metabolic phenotyping approach may have a future role as a supplement for clinical decision making in NAFLD and in the adaption to more individualized treatment protocols.

The latest idea in NAFLD/NASH pathogenesis

Nonalcoholic fatty liver disease (NAFLD) is a metabolic disorder characterized by fatty accumulation in the liver without alcohol consumption. NAFLD ranges from simple steatosis to nonalcoholic steatohepatitis (NASH), which may progress to end-stage liver disease. The prevalence of NAFLD is rising because of an increasing prevalence of obesity and metabolic syndrome. The progression of these diseases is considered to be related to metabolic syndrome, which is characterized by obesity, glucose impairment, dyslipidemia, hypertension, and adipocytokine impairment. In addition, the pathogenesis of NAFLD/NASH is considered to be multifactorial and complex and is influenced by lifestyle habits, nutritional factors, and genetics. In particular, the PNPLA3 gene has been recently recognized as the most important functional gene polymorphism in the progression of NASH. Disruption in hepatic lipid metabolism is closely related to the development of fatty liver. Accumulation of excess triglycerides (TGs) induces hepatic steatosis. However, TG accumulation itself is not harmful to hepatocytes and may instead act as a protective mechanism against free fatty acid (FFA)-induced lipotoxicity. Excess FFAs also contribute to hepatotoxicity in NAFLD/NASH because oxidation of FFAs in hepatic microsomes generates excessive oxidative stress. Oxidative stress is considered one of the most important pathogenic factors in the development of NASH. Mitochondrial abnormalities, which are frequently observed in NASH-affected livers, are associated with impaired electron transport and result in further oxidative stress formation. The aims of this review are to assess the mechanisms of lipid metabolism and hepatic steatosis, the background of the disease, and the potential molecular mechanisms involved.

Imaging of Oxidation-Specific Epitopes in Atherosclerosis and Macrophage-Rich Vulnerable Plaques

Oxidative stress, and in particular oxidation of lipoproteins, is a hallmark of atherosclerosis. Upon entry of lipoproteins into the vessel wall, a cascade of pro-atherogenic pathways is initiated whereby the reaction of reactive oxygen species with substrates amenable to oxidation, such as polyunsaturated fatty acids, generates a variety of oxidation-specific epitopes on lipoproteins, proteins in the vessel wall, and apoptotic macrophages. Several of these oxidation-specific epitopes have been well characterized and specific murine and fully human antibodies have been generated in our laboratory to detect them in the vessel wall. We have developed radionuclide, gadolinium and iron oxide based MRI techniques to noninvasively image oxidation-specific epitopes in atherosclerotic lesions. These approaches quantitate plaque burden and also allow detection of atherosclerosis regression and plaque stabilization. In particular, gadolinium micelles or lipid-coated ultrasmall superparamagnetic iron oxide particles containing oxidation-specific antibodies accumulate within macrophages in the artery wall, suggesting they may image the most unstable plaques. Translation of these approaches to humans may allow a sensitive technique to image and monitor high-risk atherosclerotic lesions and may guide optimal therapeutic interventions.

Hepatocellular ballooning in NASH

BACKGROUND & AIMS

Hepatocellular ballooning is a key finding in nonalcoholic steatohepatitis (NASH). It is conventionally defined by hemotoxylin and eosin (H&E) staining showing enlarged cells with rarefied cytoplasm and recently by changes in the cytoskeleton. Fat droplets are emerging as important organelles in cell metabolism. To address a possible relation between fat droplets and ballooning, we studied fat staining, H&E, and keratin 18 staining in human NASH.

METHODS

Sequential staining and high resolution imaging were used to study freshly prepared cryo-sections from 10 patients with histologically confirmed steatohepatitis using oil red O for fat droplet identification, H&E to identify ballooning, and anti-K18 to confirm cytoskeletal changes. High resolution images were captured at each stage using the Aperio Scanscope. To provide ultrastructural correlation, glutaraldehyde-fixed specimens were studied using transmission electron microscopy (TEM) with serial sectioning for localization of ballooned cells by light microscopy and TEM in identical specimens.

RESULTS

Serial staining consistently demonstrated that hepatocellular ballooning is associated with fat droplet accumulation evident by oil red O positivity and depletion of cytoplasmic keratin 18 with K-18 positive Mallory-Denk bodies (MDB). TEM confirmed the association between osmium stained fat droplets, MDB formation, and cellular enlargement and suggested droplet-associated dilation of the endoplasmic reticulum.

CONCLUSIONS

These results indicate a relationship between cellular ballooning, fat droplet accumulation, and cytoskeletal injury in NASH. We speculate that injury to multiple, organelles including fat droplets and endoplasmic reticulum, contribute to this characteristic finding.

Macroautophagy and chaperone-mediated autophagy are required for hepatocyte resistance to oxidant stress

The function of the lysosomal degradative pathway of autophagy in cellular injury is unclear, because findings in nonhepatic cells have implicated autophagy as both a mediator of cell death and as a survival response. Autophagic function is impaired in steatotic and aged hepatocytes, suggesting that in these settings hepatocellular injury may be altered by the decrease in autophagy. To delineate the specific function of autophagy in the hepatocyte injury response, the effects of menadione-induced oxidative stress were examined in the RALA255-10G rat hepatocyte line when macroautophagy was inhibited by a short hairpin RNA (shRNA)-mediated knockdown of the autophagy gene atg5. Loss of macroautophagy sensitized cells to apoptotic and necrotic death from normally nontoxic concentrations of menadione. Loss of macroautophagy led to overactivation of the c-Jun N-terminal kinase (JNK)/c-Jun signaling pathway that induced cell death. Death occurred from activation of the mitochondrial death pathway with cellular adenosine triphosphate (ATP) depletion, mitochondrial cytochrome c release, and caspase activation. Sensitization to death from menadione occurred despite up-regulation of other forms of autophagy in compensation for the loss of macroautophagy. Chaperone-mediated autophagy (CMA) also mediated resistance to menadione. CMA inhibition sensitized cells to death from menadione through a mechanism different from that of a loss of macroautophagy, because death occurred in the absence of JNK/c-Jun overactivation or ATP depletion.

CONCLUSION

Hepatocyte resistance to injury from menadione-induced oxidative stress is mediated by distinct functions of both macroautophagy and CMA, indicating that impaired function of either form of autophagy may promote oxidant-induced liver injury.

Expression of LYVE-1 in sinusoidal endothelium is reduced in chronically inflamed human livers

BACKGROUND

LYVE-1, a specific marker of lymphatics, is expressed in hepatic sinusoidal endothelium. A previous study revealed that LYVE-1 expression in sinusoidal endothelium was reduced in cirrhosis. However, it is still obscure how LYVE-1 expression in sinusoidal endothelium was reduced during the disease progression. To elucidate whether there were relationships among LYVE-1 attenuation, sinusoidal capillarization, and disease progression, we performed immunohistochemical investigations based on frozen human livers.

METHODS

Frozen liver sections of chronic hepatitis (n = 8), cirrhosis (n = 13), and normal/control liver (n = 10) were examined by immunostaining for lymphatic endothelial markers (LYVE-1 and D2-40) and vascular endothelial markers (CD31 and von Willebrand factor). Computer-aided morphometry was applied to obtain objective data. The diseased liver tissues were also examined ultrastructurally.

RESULTS

In controls, sinusoidal endothelium was positive for LYVE-1 and CD31, but negative for D2-40 and von Willebrand factor. In chronic hepatitis and cirrhosis, LYVE-1 expression in sinusoidal endothelium was attenuated, especially in areas adjacent to active inflammatory or fibrotic lesions, while von Willebrand factor was reciprocally expressed in sinusoidal endothelium. The morphometric analyses revealed that LYVE-1 positivity in sinusoidal endothelium was significantly (P < 0.0001) decreased in chronic hepatitis and cirrhosis compared to controls and was negatively correlated (Rs = -0.72, P < 0.0001) to von Willebrand factor positivity. Furthermore, LYVE-1 positivity was negatively correlated to inflammatory grade (Rs = -0.51, P = 0.021) and fibrosis severity (Rs = -0.46, P = 0.038). Sinusoidal endothelium in the diseased livers showing LYVE-1 attenuation had lost fenestrations.

CONCLUSIONS

These findings indicated that LYVE-1 attenuation in sinusoidal endothelium was one of the manifestations of capillarization, and was associated with hepatic disease progression.

Kupffer cell and interleukin-12-dependent loss of natural killer T cells in hepatosteatosis

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.

Expression of perilipin and adipophilin in nonalcoholic fatty liver disease; relevance to oxidative injury and hepatocyte ballooning

AIMS

Perilipin and adipophilin, PAT family proteins, play important roles in lipid metabolism. Although nonalcoholic fatty liver disease (NAFLD) is initiated by hepatocyte lipidation, little is known about the relationship between these proteins and hepatocellular injury. We investigated the expressions of perilipin and adipophilin and their relation to inflammation, fibrosis, hepatocellular ballooning, and oxidized phosphatidylcholine (oxPC) localization in human NAFLD.

METHODS AND RESULTS

Liver biopsies of nonalcoholic steatohepatitis (NASH, n=39) or simple steatosis (n=9) were studied by immunohistochemical techniques using anti-perilipin, anti-adipophilin and anti-oxPC antibodies. The severity of liver damage was histologically assessed by the Brunt system and NAFLD activity score (NAS). Enlarged hepatocytes usually containing Mallory-Denk bodies were defined as ballooned. Perilipin and adipophilin were detected on the rim of lipid droplets in both NASH and simple steatosis. Perilipin was more evident in larger lipid droplets while adipophilin expression was frequent in lipid droplets of ballooned hepatocytes. The frequency of adipophilin-positive ballooned hepatocytes was correlated to inflammation (Rs=0.72, p<0.0001), fibrosis (Rs=0.46, p=0.005), NAS (Rs=0.47, p=0.004) and oxPC-positive ballooned hepatocytes (Rs=0.35, p=0.033).

CONCLUSIONS

Expression patterns of perilipin and adipophilin in NASH livers varied with the size of lipid droplets. In partiew or, adipophilin expression in ballooned hepatocytes was closely associated with oxidative damage.

Tissue factor-deficiency and protease activated receptor-1-deficiency reduce inflammation elicited by diet-induced steatohepatitis in mice

Altered hepatic lipid homeostasis, hepatocellular injury, and inflammation are features of nonalcoholic steatohepatitis, which contributes significantly to liver-related morbidity and mortality in the Western population. A collection of inflammatory mediators have been implicated in the pathogenesis of steatohepatitis in mouse models. However, the pathways essential for coordination and amplification of hepatic inflammation and injury caused by steatosis are not completely understood. We tested the hypothesis that tissue factor (TF)-dependent thrombin generation and the thrombin receptor protease activated receptor-1 (PAR-1) contribute to liver inflammation induced by steatosis in mice. Wild-type C57Bl/6J mice fed a diet deficient in methionine and choline for 2 weeks manifested steatohepatitis characterized by increased serum alanine aminotransferase activity, macrovesicular hepatic steatosis, hepatic inflammatory gene expression, and lobular inflammation. Steatohepatitis progression was associated with thrombin generation and hepatic fibrin deposition. Coagulation cascade activation was significantly reduced in low TF mice, which express 1% of normal TF levels. Hepatic triglyceride accumulation was not affected in low TF mice or PAR-1-deficient mice. In contrast, biomarkers of hepatocellular injury, inflammatory gene induction, and hepatic accumulation of macrophages and neutrophils were greatly reduced by TF-deficiency and PAR-1-deficiency. The results suggest that TF-dependent thrombin generation and activation of PAR-1 amplify hepatic inflammation and injury during the pathogenesis of steatohepatitis.

Chronic oxidative stress sensitizes hepatocytes to death from 4-hydroxynonenal by JNK/c-Jun overactivation

Sustained activation of the c-Jun NH(2)-terminal kinase (JNK) signaling pathway mediates the development and progression of experimental diet-induced nonalcoholic fatty liver disease (NAFLD). Delineating the mechanism of JNK overactivation in the setting of a fatty liver is therefore essential to understanding the pathophysiology of NAFLD. Both human and experimental NAFLD are associated with oxidative stress and resultant lipid peroxidation, which have been proposed to mediate the progression of this disease from simple steatosis to steatohepatitis. The ability of oxidants and the lipid peroxidation product 4-hydroxynonenal (HNE) to activate JNK signaling suggested that these two factors may act synergistically to trigger JNK overactivation. The effect of HNE on hepatocyte injury and JNK activation was therefore examined in cells under chronic oxidant stress from overexpression of the prooxidant enzyme cytochrome P450 2E1 (CYP2E1), which occurs in NAFLD. CYP2E1-generated oxidant stress sensitized a rat hepatocyte cell line to death from normally nontoxic concentrations of HNE. CYP2E1-overexpressing cells underwent a more profound depletion of glutathione (GSH) in response to HNE secondary to decreased gamma-glutamylcysteine synthetase activity. GSH depletion led to overactivation of JNK/c-Jun signaling at the level of mitogen-activated protein kinase kinase 4 that induced cell death. Oxidant stress and the lipid peroxidation product HNE cause synergistic overactivation of the JNK/c-Jun signaling pathway in hepatocytes, demonstrating that HNE may not be just a passive biomarker of hepatic oxidant stress but rather an active mediator of hepatocellular injury through effects on JNK signaling.

Nitric oxide and redox regulation in the liver: Part I. General considerations and redox biology in hepatitis

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are created in normal hepatocytes and are critical for normal physiologic processes, including oxidative respiration, growth, regeneration, apoptosis, and microsomal defense. When the levels of oxidation products exceed the capacity of normal antioxidant systems, oxidative stress occurs. This type of stress, in the form of ROS and RNS, can be damaging to all liver cells, including hepatocytes, Kupffer cells, stellate cells, and endothelial cells, through induction of inflammation, ischemia, fibrosis, necrosis, apoptosis, or through malignant transformation by damaging lipids, proteins, and/or DNA. In Part I of this review, we will discuss basic redox biology in the liver, including a review of ROS, RNS, and antioxidants, with a focus on nitric oxide as a common source of RNS. We will then review the evidence for oxidative stress as a mechanism of liver injury in hepatitis (alcoholic, viral, nonalcoholic). In Part II of this review, we will review oxidative stress in common pathophysiologic conditions, including ischemia/reperfusion injury, fibrosis, hepatocellular carcinoma, iron overload, Wilson's disease, sepsis, and acetaminophen overdose. Finally, biomarkers, proteomic, and antioxidant therapies will be discussed as areas for future therapeutic interventions.

Increased hepatic myeloperoxidase activity in obese subjects with nonalcoholic steatohepatitis

Inflammation and oxidative stress are considered critical factors in the progression of nonalcoholic fatty liver disease. Myeloperoxidase (MPO) is an important neutrophil enzyme that can generate aggressive oxidants; therefore, we studied the association between MPO and nonalcoholic fatty liver disease. The distribution of inflammatory cells containing MPO in liver biopsies of 40 severely obese subjects with either nonalcoholic steatohepatitis (NASH) (n = 22) or simple steatosis (n = 18) was investigated by immunohistochemistry. MPO-derived oxidative protein modifications were identified by immunohistochemistry and correlated to hepatic gene expression of CXC chemokines and M1/M2 macrophage markers as determined by quantitative PCR. MPO plasma levels were determined by ELISA. The number of hepatic neutrophils and MPO-positive Kupffer cells was increased in NASH and was accompanied by accumulation of hypochlorite-modified and nitrated proteins, which can be generated by the MPO-H2O2 system. Liver CXC chemokine expression was higher in patients with accumulation of MPO-mediated oxidation products and correlated with hepatic neutrophil sequestration. Plasma MPO levels were elevated in NASH patients. Interestingly, neutrophils frequently surrounded steatotic hepatocytes, resembling the crown-like structures found in obese adipose tissue. Furthermore, hepatic M2 macrophage marker gene expression was increased in NASH. Our data indicate that accumulation of MPO-mediated oxidation products, partly derived from Kupffer cell MPO, is associated with induction of CXC chemokines and hepatic neutrophil infiltration and may contribute to the development of NASH.

Dysfunctional very-low-density lipoprotein synthesis and release is a key factor in nonalcoholic steatohepatitis pathogenesis

The specific mechanisms of nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH) pathogenesis remain unknown. In the present study we investigated the differences between NAFL and NASH in terms of liver lipid metabolites and serum lipoprotein. In all, 104 Japanese subjects (50 men and 54 postmenopausal women) with histologically verified NAFL disease (NAFLD) (51 with NAFL, 53 with NASH) were evaluated; all diagnoses were based on liver biopsy findings and the proposed diagnostic criteria. To investigate the differences between NAFL and NASH in humans, we carefully examined (1) lipid inflow in the liver, (2) lipid outflow from the liver, (3) very-low-density lipoprotein (VLDL) synthesis in the liver, (4) triglyceride (TG) metabolites in the liver, and (5) lipid changes and oxidative DNA damage. Most of the hepatic lipid metabolite profiles were similar in the NAFL and NASH groups. However, VLDL synthesis and lipid outflow from the liver were impaired, and surplus TGs might have been produced as a result of lipid oxidation and oxidative DNA damage in the NASH group.

CONCLUSION

A growing body of literature suggests that a deterioration in fatty acid oxidation and VLDL secretion from the liver, caused by the impediment of VLDL synthesis, might induce serious lipid oxidation and DNA oxidative damage, impacting the degree of liver injury and thereby contributing to the progression of NASH. Therefore, dysfunctional VLDL synthesis and release may be a key factor in progression to NASH.

Inhibition of hepatic stellate cell activation following Yinchenhao decoction administration to dimethylnitrosamine-treated rats

AIM

In an effort to investigate the mechanism by which Yinchenhao decoction (YCHD) acts on liver injury, we investigated the potential antifibrogenic effects of YCHD in an experimental liver fibrosis rat model, with special focus on the mechanisms inhibiting the activation and promoting apoptosis of hepatic stellate cells (HSC).

METHODS

The rats were initially randomized into two groups: the control (n = 10) and dimethylnitrosamine-treated (DMN; n = 30) groups. DMN (10 mg/kg body weight) was administered intraperitoneally to the DMN-treated rats for three consecutive days each week. At the end of the second week, three rats from the control and six rats from the DMN-treated groups were killed for the fibrosis development assessment. The remaining DMN rats were further randomized into two groups: the DMN-water group (n = 12) and the DMN-YCHD group (n = 12). Both groups continued to receive weekly DMN treatment for another 2 weeks in addition to daily administration of either water or YCHD, which were given intragastrically at a dose of 0.418 g/100 g body weight.

RESULTS

Hepatic hydroxyproline content decreased and had improved histopathology in the DMN-YCHD rats. Compared to the DMN group, alpha-smooth muscle actin (SMA) and CD68 expression in the DMN-YCHD group was reduced significantly; however, alpha-SMA-positive HSC apoptosis was not observed by confocal microscopy; Fibrogenic proteins (tissue inhibitor matrix proteinases-1 and 2 and matrix metalloproteinase [MMP]-2/14) and cytokines (tumor necrosis factor-alpha and transforming growth factor-beta(1)) were decreased; MMP-9 was significantly upregulated.

CONCLUSION

Yinchenhao administration attenuates liver fibrosis at least in part by inhibiting HSC activation directly, rather than promoting cell apoptosis of activated HSC, and the suppressive activation of Kupffer cells.

The role of phospholipid oxidation products in inflammatory and autoimmune diseases: evidence from animal models and in humans

Since the discovery of oxidized phospholipids (OxPL) and their implication as modulators of inflammation in cardiovascular disease, roles for these lipid oxidation products have been suggested in many other disease settings. Lipid oxidation products accumulate in inflamed and oxidatively damaged tissue, where they are derived from oxidative modification of lipoproteins, but also from membranes of cells undergoing apoptosis. Thus, increased oxidative stress as well as decreased clearance of apoptotic cells has been implied to contribute to accumulation of OxPL in chronically inflamed tissues.A central role for OxPL in disease states associated with dyslipedemia, including atherosclerosis, diabetes and its complications, metabolic syndrome, and renal insufficiency, as well as general prothrombotic states, has been proposed. In addition, in organs which are constantly exposed to oxidative stress, including lung, skin, and eyes, increased levels of OxPL are suggested to contribute to inflammatory conditions. Moreover, accumulation of OxPL causes general immunmodulation and may lead to autoimmune diseases. Evidence is accumulating that OxPL play a role in lupus erythematosus, antiphospholipid syndrome, and rheumatoid arthritis. Last but not least, a role for OxPL in neurological disorders including multiple sclerosis (MS), Alzheimer's and Parkinson's disease has been suggested.This chapter will summarize recent findings obtained in animal models and from studies in humans that indicate that formation of OxPL represents a general mechanism that may play a major role in chronic inflammatory and autoimmune diseases.

Molecular basis and mechanisms of progression of non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH), a cause of cirrhosis and hepatocellular carcinoma, is characterized by fatty infiltration of the liver, inflammation, hepatocellular damage and fibrosis. Progress has been made in understanding the molecular and cellular mechanisms implicated in the pathogenesis of this condition, therefore, we here review recent developments regarding the basic mechanisms of NASH development. Accumulation of triglycerides in the hepatocytes is the result of increased inflow of free fatty acids and de novo lipogenesis. Steatosis leads to lipotoxicity, which causes apoptosis, necrosis, generation of oxidative stress and inflammation. The resulting chronic injury activates a fibrogenic response that leads eventually to end-stage liver disease. A better understanding of these mechanisms is crucial for the design of novel diagnostic and therapeutic strategies.

The effect of QuYuHuaTanTongLuo Decoction on the non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH) is the most common cause of cryptogenic cirrhosis, is becoming more prevalent in China. However, there is as yet no clearly established therapy for reversing fatty liver. Our aim is to explore the effect of traditional Chinese herbs QuYuHuaTanTongLuo Decoction (QYHTTLD) on non-alcoholic steatohepatitis. Sixty-nine non-alcoholic steatohepatitis patients were randomly divided into two groups. One group of 35 patients were treated by QYHTTLD, another group of 34 patients were treated by Ursodeoxycholic acid (UDCA). The TNF-alpha, IL-8, MDA level, SOD activity and liver function, as well as B ultrasonic image were detected before and after being treated. The results showed: after 6 months treatment, MBI of the treatment group was obviously decreased (p<0.05). The levels of TC, TG and LDL-C were significantly decreased whereas the level of HDL-C increased (p<0.01, p<0.05, p<0.05, and p<0.05, respectively) in the treatment group, the levels of TC, TG, LDL-C and HDL-C had no significant difference in the control group (p>0.05). The levels of TNF-alpha, IL-8 and MDA were significantly decreased whereas SOD activity was significantly increased (p<0.01, p<0.05, p<0.01, and p<0.01, respectively) in the treatment group, the level of MDA was significantly decreased in the control group (p<0.05). B ultrasonic images were ameliorated in different degree (p<0.01 and p<0.01, respectively). Both QYHTTLD and UDCA had the effect in improving the scores of symptoms and signs of patients, however, the difference value of the scores in treatment group were significantly higher than that in control group after being treated for 6 months (p<0.05).

CONCLUSION

QYHTTLD is effective for treating non-alcoholic steatohepatitis, and its effect seems to relate with the ways of QYHTTL down-regulating inflammation cytokine IL-8 level and relieving lipid peroxidation of liver.

The effects of 48 weeks of rosiglitazone on hepatocyte mitochondria in human nonalcoholic steatohepatitis

Rosiglitazone, a thiazolidinedione peroxisome proliferator-activated receptor gamma ligand, reduces disease activity in nonalcoholic steatohepatitis (NASH), a disease associated with hepatocyte mitochondrial crystalline inclusions that are not seen in animal models of NASH. In human and animal studies of adipose tissue, thiazolidinediones may induce mitochondrial biogenesis and associated morphological changes. To determine if rosiglitazone alters the hepatocyte mitochondrial morphology in human NASH, we prospectively and systematically examined liver biopsies from human subjects with NASH before and after 48 weeks of rosiglitazone by transmission electron microscopy. Twenty patients (body mass index = 34 +/- 7) were studied. Four coded sections from each of 20 pretherapy biopsies and each of 20 posttherapy biopsies were examined by transmission electron microscopy. The total hepatocyte mitochondria and crystal-containing mitochondria were counted, and semiquantitative scoring was performed for macrosteatosis, microsteatosis, dilated endoplasmic reticulum, apoptosis, Mallory bodies, and hepatocyte enlargement. The total mitochondria count was unchanged after therapy, but there was a significant increase in crystal-containing mitochondria from 4.0% (95% confidence interval = 1.8-8.8) to 7.2% (95% confidence interval = 3.9-12.6; odds ratio = 1.80; P = 0.04) after the treatment with rosiglitazone. Macrosteatosis (P < 0.001) and Mallory bodies (P = 0.05) significantly decreased, but no change was evident in microsteatosis, cellular enlargement, dilated endoplasmic reticulum, or apoptosis.

CONCLUSION

Rosiglitazone therapy of NASH is associated with increased crystalline inclusions in hepatocyte mitochondria. Whether these are adaptive or pathological remains unknown, and further studies are warranted to assess hepatic mitochondrial function during thiazolidinedione therapy for NASH.

Combined pantethine and probucol therapy for Japanese patients with non-alcoholic steatohepatitis

AIMS

To evaluate the efficacy and mechanism of combined pantethine and probucol therapy in Japanese patients with non-alcoholic steatohepatitis (NASH), liver function, serum cytokines, serum adiponectin and liver biopsy findings were investigated.

METHODS

Sixteen patients with NASH and hyperlipidemia were treated with pantethine (600 mg/day) and probucol (500 mg/day) for 48 weeks.

RESULTS

The mean pretreatment aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were 66 IU/L and 113 IU/L, respectively, which showed a significant decrease with treatment to 33 IU/L and 51 IU/L (P < 0.01 and P < 0.05), respectively. Total cholesterol was also significantlydecreased (P < 0.01). In addition, the mean serum TGF-beta level was significantly decreased, while the mean serum level of high molecular adiponectin was increased. In eight patients, liver biopsy was performed both before and after treatment. In four of these patients, inflammation was improved, and fibrosis was improved in two patients. No side-effects of this treatment were noted.

CONCLUSION

Combined pantethine and probucol therapy was safe and effective for Japanese NASH patients, with its efficacy being mediated through adiponectin and TGF-beta.

Nitrosative stress predicts the presence and severity of nonalcoholic fatty liver at different stages of the development of insulin resistance and metabolic syndrome: possible role of vitamin A intake

BACKGROUND

Although nonalcoholic fatty liver disease (NAFLD) is associated with the metabolic syndrome, the mechanisms responsible for the development of NAFLD at different stages of the development of insulin resistance are unknown. Diet, adipokines, and nitrosative stress have been linked to both NAFLD and insulin resistance.

OBJECTIVE

We aimed to identify the factors that are specifically associated with NAFLD at different stages in the development of insulin resistance and the metabolic syndrome.

DESIGN

Circulating concentrations of adipokines (ie, tumor necrosis factor-alpha, adiponectin, resistin, leptin, and interleukin-6), markers of nitrosative stress (nitrotyrosine), dietary habits, and MTP -493G/T polymorphism were cross-sectionally related to the presence and severity of insulin resistance (homeostasis model assessment index for insulin resistance: >or=2), the metabolic syndrome, and fatty liver in 64 nonobese nondiabetic patients with NAFLD (33 insulin-sensitive and 31 insulin-resistant subjects) and 74 control subjects without liver disease who were matched for sex, BMI, homeostasis model assessment index for insulin resistance status, and the various features of the metabolic syndrome.

RESULTS

Persons with NAFLD had greater systemic nitrosative stress and a lower intake of vitamins A and E than did control subjects, but the 2 groups did not differ significantly in any other features. Nitrotyrosine and adiponectin concentrations and vitamin A intakes independently predicted alanine aminotransferase concentrations in NAFLD patients and liver histology in a subgroup of 29 subjects with biopsy-proven nonalcoholic steatohepatitis.

CONCLUSIONS

Oxidative stress is operating in NAFLD and nonalcoholic steatohepatitis, even in the absence of insulin resistance, the metabolic syndrome, and hypoadiponectinemia, which aggravate liver histology at more severe stages of metabolic disease. The possible pathogenetic role of reduced vitamin A intake in NAFLD warrants further investigation.

Influence of TNF gene polymorphisms in Japanese patients with NASH and simple steatosis

BACKGROUND/AIMS

Tumor necrosis factor (TNF) is considered to play a role in the second hit of non-alcoholic steatohepatitis (NASH). To clarify the effects of TNF in NASH we investigated TNF gene polymorphisms that might influence TNF production were investigated.

METHODS

We analyzed 102 patients with non-alcoholic fatty liver disease (NAFLD; 36 with simple steatosis and 66 with NASH) and 100 control subjects. The serum level of soluble TNF receptor (sTNFR)-2 was measured. The TNF-alpha promoter region positions -1031, -863, -857, -308, and -238 and the TNF-beta gene Nco1 polymorphism site were investigated.

RESULTS

The level of sTNFR-2 was significantly higher in NASH patients than in those with simple steatosis or control subjects. In the analysis of TNF gene polymorphisms, there were no significant deviations between the group of all NAFLD patients and the control subjects. The carrier frequencies of polymorphisms at positions -1031C and -863A were significantly higher in patients with NASH than in those with simple steatosis. In the multivariate analysis, TNF-alpha promoter polymorphisms proved to be significant independent factors distinguishing NASH from simple steatosis.

CONCLUSIONS

TNF polymorphisms, which influence TNF production, might be associated with the progression of NAFLD.

Has natural selection in human populations produced two types of metabolic syndrome (with and without fatty liver)?

Fatty liver is closely related to the development of the insulin resistance syndrome that largely results from abnormal insulin signaling in three major organs: (i) skeletal muscle in which insulin sensitivity depends on fat content and metabolic activity (exercise); (ii) adipose tissue, which serves as a reservoir of energy in the form of triglycerides; and (iii) the liver, which variably serves as a source or storage site of carbohydrates and lipids. In many respects, the fatty liver resembles a mixture of brown adipose tissue (microvesicular steatosis) and white adipose tissue (macrovesicular steatosis) including the stages of fatty droplet accumulation, and the expression of uncoupling proteins and perilipin-like substances. Furthermore, the development of an inflammatory infiltrate and the increased production of cytokines as occurs in adipose tissue, suggest that the liver in some individuals serves as an extension of adipose tissue. Moreover, current evidence indicates that these morphological changes represent altered gene expression similar to that of adipocytes. However, fatty liver does not appear to be a uniform feature of the metabolic syndrome and there is substantial variation in humans in the development of fatty liver independent of insulin resistance. In this regard, the variable development of fatty liver in Palmipedes (migratory fowl) and its close relationship to skeletal muscle utilization of fatty acids, lipoprotein metabolism and thermoregulation are instructive. The predilection to non-alcoholic fatty liver disease among some varieties of Palmipedes suggests that the development of fatty liver represents an adaptive process, closely integrated with skeletal muscle fat utilization and adipose tissue distribution, and facilitates survival in a very cold, resource-scarce environment. Variation in human populations with metabolic syndrome likewise suggests that the trait evolved in populations exposed in ancient times to different environmental challenges and, because the liver plays a central role in lipid metabolism, the presence or absence of fatty liver is likely to be integrated with insulin sensitivity in other target organs and with lipoprotein metabolism.