Adipokines and cytokines in non-alcoholic fatty liver disease

Hypoadiponectinaemia in nonalcoholic fatty liver disease obese women is associated with infrequent intake of dietary sucrose and fatty foods

BACKGROUND

The present study aimed to investigate the relationship between adiponectinaemia and food intake among obese women with nonalcoholic fatty liver disease (NAFLD).

METHODS

In total, 60 obese women were examined by abdominal ultrasound for liver steatosis and subcutaneous and visceral adiposity. A standard interview (including questions about alcohol intake, medical history and physical activity), a physical examination (including height, weight, body mass index, waist and hip circumferences, waist-to-hip ratio, and body composition) and biochemical and clinical parameters (including serum glucose and insulin, homeostatic model assessment insulin resistance, lipid profile, aminotransferases, C-reactive protein, adiponectin, leptin, resistin, tumour necrosis factor-α, interleukin-6 levels and blood pressure) were performed. Food intake was evaluated by a qualitative food frequency questionnaire.

RESULTS

Twenty-four NAFLD patients and thirty-six controls were analysed. The Mann-Whitney test showed lower adiponectin levels in the liver disease group compared to controls (P < 0.05). The Pearson correlation coefficient indicated that adiponectinaemia was negatively correlated with lipid profile and serum tumour necrosis factor-α (P = 0.05) and was positively associated with adiposity measures and serum leptin (P < 0.05). By simple linear regression, all of these variables predicted serum adiponectin levels. Chi-squared and Fisher's exact tests indicated that, in both groups, food intake showed no differences, although sucrose and fatty foods were associated with lower adiponectin levels in the liver disease group (P < 0.05 and P < 0.05, respectively), as well as in the control group (P = 0.05 and P < 0.05, respectively).

CONCLUSIONS

Hypoadiponectinaemia in NAFLD was associated with dietary sucrose and fatty food intake, emphasising the important role of diet in the occurrence of this disease.

Choline's role in maintaining liver function: new evidence for epigenetic mechanisms

PURPOSE OF REVIEW

Humans eating diets low in choline develop fatty liver and liver damage. Rodents fed choline-methionine-deficient diets not only develop fatty liver, but also progress to develop fibrosis and hepatocarcinoma. This review focuses on the role of choline in liver function, with special emphasis on the epigenetic mechanisms of action.

RECENT FINDINGS

Dietary intake of methyl donors like choline influences the methylation of DNA and histones, thereby altering the epigenetic regulation of gene expression. The liver is the major organ within which methylation reactions occur, and many of the hepatic genes involved in pathways for the development of fatty liver, hepatic fibrosis, and hepatocarcinomas are epigenetically regulated.

SUMMARY

Dietary intake of choline varies over a three-fold range and many humans have genetic polymorphisms that increase their demand for choline. Choline is an important methyl donor needed for the generation of S-adenosylmethionine. Dietary choline intake is an important modifier of epigenetic marks on DNA and histones, and thereby modulates the gene expression in many of the pathways involved in liver function and dysfunction.

Non-invasive diagnosis of non-alcoholic fatty liver disease. A critical appraisal

Non-alcoholic fatty liver disease (NAFLD) affects one in every three subjects in the occidental world. The vast majority will not progress, but a relevant minority will develop liver cirrhosis and its complications. The classical gold standard for diagnosing and staging NAFLD and assessing fibrosis is liver biopsy (LB). However, it has important sample error issues and subjectivity in the interpretation, apart from a small but real risk of complications. The decision to perform an LB is even harder in a condition so prevalent such as NAFLD, in which the probability of finding severe liver injury is low. In an attempt to overcome LB and to subcategorize patients with NAFLD in different prognoses allowing better management decisions, several non-invasive methods have been studied in the last decade. The literature is vast and confusing. This review will summarize which methods have been tested and how they perform, which tests are adequate for clinical practice and how they can change the management of these patients.

Expression of inflammation-related genes is altered in gastric tissue of patients with advanced stages of NAFLD

Obesity is associated with chronic low-grade inflammation perpetuated by visceral adipose. Other organs, particularly stomach and intestine, may also overproduce proinflammatory molecules. We examined the gene expression patterns in gastric tissue of morbidly obese patients with nonalcoholic fatty liver disease (NAFLD) and compared the changes in gene expression in different histological forms of NAFLD. Stomach tissue samples from 20 morbidly obese NAFLD patients who were undergoing sleeve gastrectomy were profiled using qPCR for 84 genes encoding inflammatory cytokines, chemokines, their receptors, and other components of inflammatory cascades. Interleukin 8 receptor-beta (IL8RB) gene overexpression in gastric tissue was correlated with the presence of hepatic steatosis, hepatic fibrosis, and histologic diagnosis of nonalcoholic steatohepatitis (NASH). Expression levels of soluble interleukin 1 receptor antagonist (IL1RN) were correlated with the presence of NASH and hepatic fibrosis. mRNA levels of interleukin 8 (IL8), chemokine (C-C motif) ligand 4 (CCL4), and its receptor chemokine (C-C motif) receptor type 5 (CCR5) showed a significant increase in patients with advanced hepatic inflammation and were correlated with the severity of the hepatic inflammation. The results of our study suggest that changes in expression patterns for inflammatory molecule encoding genes within gastric tissue may contribute to the pathogenesis of obesity-related NAFLD.

Obesity, adipokines and hepatocellular carcinoma

Obesity is rapidly becoming pandemic and is associated with increased carcinogenesis, especially hepatocellular carcinoma (HCC). Adipose tissue is considered as an endocrine organ because of its capacity to secrete a variety of adipokines, such as leptin, adiponectin and resistin. Recently, adipokines have been demonstrated to be associated with kinds of chronic liver diseases including fibrosis, cirrhosis and carcinogenesis. Direct evidence is accumulating rapidly supporting the inhibitory and/or activating role of adipokines in the process of carcinogenesis and progression of human HCC. This review aims to provide important insight into the potential mechanisms of adipokines in the development of HCC.

Accuracy of prediction scores and novel biomarkers for predicting nonalcoholic fatty liver disease in obese children

BACKGROUND

Accurate prediction scores for liver steatosis are demanded to enable clinicians to noninvasively screen for nonalcoholic fatty liver disease (NAFLD). Several prediction scores have been developed, however external validation is lacking.

OBJECTIVE

The aim was to determine the diagnostic accuracy of four existing prediction scores in severely obese children, to develop a new prediction score using novel biomarkers and to compare these results to the performance of ultrasonography.

DESIGN AND RESULTS

Liver steatosis was measured using proton magnetic resonance spectroscopy in 119 severely obese children (mean age 14.3 ± 2.1 years, BMI z-score 3.35 ± 0.35). Prevalence of steatosis was 47%. The four existing predictions scores ("NAFLD liver fat score," "fatty liver index," "hepatic steatosis index," and the pediatric prediction score) had only moderate diagnostic accuracy in this cohort (positive predictive value (PPV): 70, 61, 61, 69% and negative predictive value (NPV) 77, 69, 68, 75%, respectively). A new prediction score was built using anthropometry, routine biochemistry and novel biomarkers (leptin, adiponectin, TNF-alpha, IL-6, CK-18, FGF-21, and adiponutrin polymorphisms). The final model included ALT, HOMA, sex, and leptin. This equation (PPV 79% and NPV 80%) did not perform substantially better than the four other equations and did not outperform ultrasonography for excluding NAFLD (NPV 82%).

CONCLUSION

The conclusion is in severely obese children and adolescents existing prediction scores and the tested novel biomarkers have insufficient diagnostic accuracy for diagnosing or excluding NAFLD.

What is the role of adiponectin in obesity related non-alcoholic fatty liver disease?

Non-alcoholic fatty liver disease (NAFLD) is recognized as the most common type of chronic liver disease in Western countries. Insulin resistance is a key factor in the pathogenesis of NAFLD, the latter being considered as the hepatic component of insulin resistance or obesity. Adiponectin is the most abundant adipose-specific adipokine. There is evidence that adiponectin decreases hepatic and systematic insulin resistance, and attenuates liver inflammation and fibrosis. Adiponectin generally predicts steatosis grade and the severity of NAFLD; however, to what extent this is a direct effect or related to the presence of more severe insulin resistance or obesity remains to be addressed. Although there is no proven pharmacotherapy for the treatment of NAFLD, recent therapeutic strategies have focused on the indirect upregulation of adiponectin through the administration of various therapeutic agents and/or lifestyle modifications. In this adiponectin-focused review, the pathogenetic role and the potential therapeutic benefits of adiponectin in NAFLD are analyzed systematically.

Knowledge-based identification of soluble biomarkers: hepatic fibrosis in NAFLD as an example

The discovery of biomarkers is often performed using high-throughput proteomics-based platforms and is limited to the molecules recognized by a given set of purified and validated antigens or antibodies. Knowledge-based, or systems biology, approaches that involve the analysis of integrated data, predominantly molecular pathways and networks may infer quantitative changes in the levels of biomolecules not included by the given assay from the levels of the analytes profiled. In this study we attempted to use a knowledge-based approach to predict biomarkers reflecting the changes in underlying protein phosphorylation events using Nonalcoholic Fatty Liver Disease (NAFLD) as a model. Two soluble biomarkers, CCL-2 and FasL, were inferred in silico as relevant to NAFLD pathogenesis. Predictive performance of these biomarkers was studied using serum samples collected from patients with histologically proven NAFLD. Serum levels of both molecules, in combination with clinical and demographic data, were predictive of hepatic fibrosis in a cohort of NAFLD patients. Our study suggests that (1) NASH-specific disruption of the kinase-driven signaling cascades in visceral adipose tissue lead to detectable changes in the levels of soluble molecules released into the bloodstream, and (2) biomarkers discovered in silico could contribute to predictive models for non-malignant chronic diseases.

Adiponectin: a key playmaker adipocytokine in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome and can progress to cirrhosis, liver failure, and hepatocellular carcinoma. In the last two decades, the prevalence of NAFLD has been growing in most developed countries, mainly as a consequence of its close association with obesity and diabetes mellitus. The exact pathogenesis of NAFLD and especially the mechanisms leading to disease progression have not been completely understood. Adipocytes produce and secrete several bioactive substances known as adipocytokines which are implicated in the pathogenesis of the disease. Among them, adiponectin is an insulin-sensitizing adipocytokine possessing multiple beneficial effects on obesity-related medical complication. This review focuses on the role of adiponectin in NAFLD pathogenesis and its potential use as a diagnostic tool but also as therapeutic target for NAFLD management.

Sphingolipid metabolism and obesity-induced inflammation

Obesity is a metabolic disorder developed by overnutrition and a major cause for insulin resistance and cardiovascular events. Since adipose tissue is one of the major sites for the synthesis and secretion of cytokines, enlarged adipose tissue in obese condition alters inflammatory state leading to pathophysiological conditions such as type 2 diabetes and increased cardiovascular risk. A plausible theory for development of metabolic dysregulation is that obesity increases secretion of inflammatory cytokines from adipose tissue and causes a chronic inflammation in the whole body. Additionally accumulation of lipids in non-adipose tissues elevates the cellular levels of bioactive lipids that inhibit the signaling pathways implicated in metabolic regulation together with activated inflammatory response. Recent findings suggest that obesity-induced inflammatory response leads to modulation of sphingolipid metabolism and these bioactive lipids may function as mediators for increased risk of metabolic dysfunction. Importantly, elucidation of mechanism regarding sphingolipid metabolism and inflammatory disease will provide crucial information to development of new therapeutic strategies for the treatment of obesity-induced pathological inflammation.

Markers in nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD), the most common liver disorder worldwide, encompasses a spectrum of abnormal liver histology ranging from simple steatosis to nonalcoholic steatohepatitis (NASH) and cirrhosis. Population studies show that NAFLD is strongly associated with insulin resistance, obesity, type 2 diabetes mellitus, and lipid abnormalities. In the context of hepatic steatosis, factors that promote cell injury, inflammation, and fibrosis include oxidative stress, early mitochondrial dysfunction, endoplasmic reticulum stress, iron accumulation, apoptosis, adipocytokines, and stellate cell activation. The exact NASH prevalence is unknown because of the absence of simple noninvasive diagnostic tests. Although liver biopsy is the "gold standard" for the diagnosis of NASH, other tests are needed to facilitate the diagnosis and greatly reduce the requirement for invasive liver biopsy. In addition, the development of new fibrosis markers in NASH is needed to facilitate the assessment of its progression and the effectiveness of new therapies. The aim of this chapter, which is overview of biomarkers in NASH, is to establish a systematic approach to laboratory findings of the disease.

Plasma visfatin levels and gene expression in morbidly obese women with associated fatty liver disease

OBJECTIVES

The few studies on the physiopathological role of visfatin in morbid obesity and the related metabolic diseases have led us to examine visfatin levels and its liver gene expression in morbidly obese women with non-alcoholic fatty liver disease (NAFLD).

DESIGN AND METHODS

We examined the circulating levels of visfatin by ELISA in serum samples from 95 morbidly obese women (MO) (BMI>40 kg/m(2)) who underwent bariatric surgery and 38 normal weight control women (BMI<25 kg/m(2)). We analysed visfatin liver and adipose tissue mRNA expression by RT-PCR. We evaluated the circulating levels and gene expression of adiponectin, resistin, RBP4, TNFα, IL6 and CRP.

RESULTS

Serum visfatin was significantly higher in MO compared with controls, and also in MO with NAFLD was significantly higher than MO with normal liver. We found that NAFLD diabetic patients presented similar serum visfatin levels than non-diabetic. Serum visfatin correlated with IL6 (r=0.496; p<0.001) and CRP levels (r=0.241; p=0.049). Liver visfatin expression was significantly higher in MO compared to controls and was also significantly higher in MO with NAFLD than in MO with normal liver. Visfatin liver expression correlated positively with resistin (r=0.436, p=0.018) and TNFα expression (r=0.328, p=0.028). Visfatin expression in adipose tissues was similar among the MO groups analysed.

CONCLUSION

Serum visfatin and its liver expression are higher in MO women with NAFLD, irrespective of the presence of diabetes. Serum visfatin and its liver expression correlate positively with pro-inflammatory factors. These findings suggest that visfatin may be a molecule related with fat inflammation in morbid obesity and fatty liver disease.

Focus on therapeutic strategies of nonalcoholic Fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the Western world (it affects 30% of the general adult population). The NAFLD encompasses a histological spectrum ranging from simple steatosis to nonalcoholic steatohepatitis (NASH), defined by steatosis, hepatocellular damage, and lobular inflammation in individuals without significant alcohol consumption and negative viral, congenital, and autoimmune liver disease markers. Currently, NAFLD is considered an emerging epidemic in light of the dramatic increase in obesity rates. With the progressive nature of NASH and its rising prevalence there is a significant need for a specific and targeted treatments since to date there has not been any validated therapies for NAFLD other than weight loss, which is well known to have a poor long-term success rate. In recent years, visceral adipose tissue has taken an important role in NAFLD pathogenesis, and current therapeutic approaches aim at reducing visceral obesity and free fatty acid overflow to the liver. This paper is focused on the treatments used for NAFLD and the potential new therapy.

How adiponectin, leptin, and ghrelin orchestrate together and correlate with the severity of nonalcoholic fatty liver disease

BACKGROUND

Adipose tissue contributes to nonalcoholic fatty liver disease (NAFLD), being a source of fatty acids and cytokines such as leptin and adiponectin, and regulating ghrelin production. Their role in NAFLD pathogenesis remains controversial. We aimed to study the influence of those cytokines on the severity of NAFLD.

METHODS

Morbidly obese individuals with biopsy-proven NAFLD were recruited. The NAFLD activity score was applied to liver histology. Serum concentrations of adiponectin, leptin, and ghrelin were determined.

RESULTS

Eighty-two patients were included, 13% with nonalcoholic steatohepatitis (NASH). Hypertriglyceridemia (P=0.018) and metabolic syndrome (P=0.040) were independent factors associated with NASH. Leptin associated positively and ghrelin associated negatively with BMI; adiponectin associated negatively with the waist to hip ratio. Adiponectin associated negatively with insulin resistance, hypertension, and metabolic syndrome; ghrelin associated positively with diabetes mellitus. Adiponectin below 23 ng/ml associated with NASH (odds ratio 12.95, P<0.001). Leptin increased progressively (P=0.032) and adiponectin decreased (P=0.004) with increasing severity of steatosis. Also, leptin increased progressively with more severe fibrosis (P=0.053). A formula incorporating the three cytokines yielded an AUROC of 0.789 (P=0.002), a sensitivity of 81.8%, and a specificity of 76.1% for NASH.

CONCLUSION

An imbalance in adiponectin, leptin, and ghrelin seems to be associated with more severe NAFLD. A formula combining the three cytokines showed good accuracy for NASH.

Visfatin levels in nonalcoholic fatty liver disease

PURPOSE

Recently, role of adipokin in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) has been suggested. Among adipokins, role of leptin and adiponectin is rather well known; however, there are only a few data concerning visfatin.

MATERIAL AND METHODS

NAFLD is confirmed in 30 patients by ultrasonography. As a control group, patients without fatty liver or other liver diseases were included. Viral hepatitis, metabolic liver diseases, and autoimmune hepatitis and consumption of alcohol were excluded in all patients. Fasting serum level of visfatin was determined by ELISA method.

RESULTS

Serum visfatin concentration in the NAFLD group (14.7 ± 8.1 ng/ml) was significantly higher than in controls (9.4 ± 1.6 ng/ml) (P < 0.001). There were no correlations between visfatin and anthropometric parameters, transaminases, lipids, and homeostasis model assessment-estimated insulin resistance (HOMA-IR).

CONCLUSION

Serum visfatin concentration increases in patients with NAFLD.

Enhanced A-FABP expression in visceral fat: potential contributor to the progression of NASH

Background/Aims

Adipose tissue is an active endocrine organ that secretes various metabolically important substances including adipokines, which represent a link between insulin resistance and nonalcoholic steatohepatitis (NASH). The factors responsible for the progression from simple steatosis to steatohepatitis remain elusive, but adipokine imbalance may play a pivotal role. We evaluated the expressions of adipokines such as visfatin, adipocyte-fatty-acid-binding protein (A-FABP), and retinol-binding protein-4 (RBP-4) in serum and tissue. The aim was to discover whether these adipokines are potential predictors of NASH.

Methods

Polymerase chain reaction, quantification of mRNA, and Western blots encoding A-FABP, RBP-4, and visfatin were used to study tissue samples from the liver, and visceral and subcutaneous adipose tissue. The tissue samples were from biopsy specimens obtained from patients with proven NASH who were undergoing laparoscopic cholecystectomy due to gallbladder polyps.

Results

Patients were classified into two groups: NASH, n=10 and non-NASH, n=20 according to their nonalcoholic fatty liver disease Activity Score. Although serum A-FABP levels did not differ between the two groups, the expressions of A-FABP mRNA and protein in the visceral adipose tissue were significantly higher in NASH group than in non-NASH group (104.34 vs. 97.05, P<0.05, and 190.01 vs. 95.15, P<0.01, respectively). Furthermore, the A-FABP protein expression ratio between visceral adipose tissue and liver was higher in NASH group than in non-NASH group (4.38 vs. 1.64, P<0.05).

Conclusions

NASH patients had higher levels of A-FABP expression in their visceral fat compared to non-NASH patients. This differential A-FABP expression may predispose patients to the progressive form of NASH.

Manipulating molecular switches in brown adipocytes and their precursors: a therapeutic potential

Brown adipocytes constitute a metabolically active tissue responsible for non-shivering thermogenesis and the depletion of excess calories. Differentiation of brown fat adipocytes de novo or stimulation of pre-existing brown adipocytes within white adipose depots could provide a novel method for reducing the obesity and alleviating the consequences of type II diabetes worldwide. In this review, we addressed several molecular mechanisms involved in the control of brown fat activity, namely, the β₃-adrenergic stimulation of thermogenesis during exposure to cold or by catecholamines; the augmentation of thyroid function; the modulation of peroxisome proliferator-activated receptor gamma (PPARγ), transcription factors of the C/EBP family, and the PPARγ co-activator PRDM16; the COX-2-driven expression of UCP1; the stimulation of the vanilloid subfamily receptor TRPV1 by capsaicin and monoacylglycerols; the effects of BMP7 or its analogs; the cannabinoid receptor antagonists and melanogenesis modulating agents. Manipulating one or more of these pathways may provide a solution to the problem of harnessing brown fat's thermogenic potential. However, a better understanding of their interplay and other homeostatic mechanisms is required for the development of novel therapies for millions of obese and/or diabetic individuals.

Angiogenesis: a phenomenon which aggravates chronic liver disease progression

It has become increasingly clear that angiogenesis occurring during chronic wound healing and fibrogenesis provides a key contribution to disease progression and complications. The association of fibrogenesis and angiogenesis should be regarded as crucial in the modern evaluation of liver disease progression and in the search for therapeutic targets. Physiological hepatic angiogenesis occurs during liver regeneration, contributing to the formation of new functional sinusoids. Pathological angiogenesis in liver is characterized by intrahepatic vascular remodeling with capillarization of the sinusoids and development of intrahepatic shunts, which lead to increased hepatic resistance and decreased effective hepatocyte perfusion. The problem of angiogenesis in chronic hepatitis C and nonalcoholic fatty liver disease has not been fully resolved. This manuscript briefly describes pathogenesis of new blood vessel formation in chronic hepatitis and potential role of angiogenesis in disease progression.

A role for sphingolipids in the pathophysiology of obesity-induced inflammation

Following the initial discovery that adipose tissue actively synthesizes and secretes cytokines, obesity-induced inflammation has been implicated in the etiology of a host of disease states related to obesity, including cardiovascular disease and type II diabetes. Interestingly, a growing body of evidence similarly implicates sphingolipids as prime instigators in these same diseases. From the recent discovery that obesity-related inflammatory pathways modulate sphingolipid metabolism comes a novel perspective—sphingolipids may act as the dominant mediators of deleterious events stemming from obesity-induced inflammation. This paradigm may identify sphingolipids as an effective target for future therapeutics aimed at ameliorating diseases associated with chronic inflammation.

The increased prevalence of non-alcoholic fatty liver disease in psoriatic patients: a study from South India

BACKGROUND

  Psoriasis is an inflammatory disease of the skin and joints. Previous studies have shown a higher prevalence of metabolic syndrome (MS) in psoriatic patients. Recent studies show that non-alcoholic fatty liver disease (NAFLD) is also frequent in psoriasis patients.

OBJECTIVES

  To investigate the occurrence and severity of NAFLD in South Indian psoriatic patients and healthy controls.

METHODS

  In phase 1 we performed a case control study on 333 adult psoriasis patients and 330 controls matched by age, sex and body mass index. NAFLD was diagnosed by ultrasonography and liver enzymes after excluding other liver diseases. In phase 2 we compared the NAFLD subgroups in psoriasis patients and controls by determining their fibrosis, steatosis and non-alcoholic steatohepatitis (NASH) scores.

RESULTS

  The occurrence of NAFLD was higher in psoriasis patients than in controls (17.4 vs 7.9%; P = 0.002). NAFLD patients in the psoriasis group (n = 58) were more likely to have MS (P = 0.03) and diabetes (P = 0.02) than those with psoriasis alone (n = 254). The former group had a longer duration of psoriasis and arthritis (P = 0.003 and 0.005). Psoriasis patients with NAFLD had more severe disease as per the psoriasis area and severity index scores (P = 0.02). Psoriasis patients had more severe NAFLD than controls as reflected by the steatosis, NASH and fibrosis scores (P = 0.001, 0.003, 0.03 respectively).

CONCLUSION

  NAFLD is the commonest liver disease in Indian psoriatic patients when compared to controls. As NAFLD is more severe in psoriasis patients we suggest routine screening for NAFLD in this group especially when systemic therapy is considered.

Maternal high-fat diet is associated with altered pancreatic remodelling in mice offspring

PURPOSE

To investigate whether a maternal high-fat diet (HF) during pregnancy and/or suckling periods predisposes adult C57BL/6 mice offspring to morphological pancreatic modifications.

METHODS

Male pups were divided into 5 groups: SC (standard chow)-from dams fed SC during gestation and lactation, maintaining an SC diet from postweaning to adulthood; G-from dams fed HF diets during gestation; L-from dams fed HF diets during lactation; GL-from dams fed HF diets during gestation and lactation; and GL/HF-from dams fed HF diets during gestation and lactation, maintaining an HF diet from postweaning to adulthood. We analysed body mass (BM), plasma insulin, pancreas and adipose tissue structures.

RESULTS

During the entire experiment, the SC group had the lowest BM. However, GL/HF offspring were heavier than the other groups. This weight gain was also accompanied by adipocyte hypertrophy. At 3 months, G offspring showed an increased insulin levels and impairment in carbohydrates metabolism. Furthermore, pancreatic islets were hypertrophied in G, GL and GL/HF offspring in comparison with SC offspring.

CONCLUSION

HF diet administration during the gestation period is more harmful than during the lactation period, exerting deleterious effects on pancreatic morphology in addition to larger fat deposits in adult mice offspring.

Atorvastatin improves disease activity of nonalcoholic steatohepatitis partly through its tumour necrosis factor-α-lowering property

BACKGROUND

We have previously found that atorvastatin decreases liver injury markers in patients with nonalcoholic steatohepatitis. However, how atorvastatin treatment ameliorates the disease activity in nonalcoholic steatohepatitis patients remains unknown.

AIMS

We examined here which anthropometric, metabolic and inflammatory variables were improved and related with amelioration of disease activity in atorvastatin-treated nonalcoholic steatohepatitis patients.

METHODS

Forty-two biopsy-proven nonalcoholic steatohepatitis patients with dyslipidemia were enrolled. Patients were treated with atorvastatin (10mg/day) for 12 months.

RESULTS

Atorvastatin significantly decreased liver transaminase, γ-glutamyl transpeptidase, low-density lipoprotein-cholesterol, triglycerides, type IV collagen, and tumour necrosis factor-α levels, whilst it increased adiponectin and high-density lipoprotein-cholesterol. Atorvastatin improved nonalcoholic fatty liver disease activity score and increased liver to spleen density ratio. Multiple stepwise regression analysis revealed that γ-glutamyl transpeptidase, tumour necrosis factor-α and liver to spleen density ratio (inversely) were independently associated with nonalcoholic fatty liver disease activity score. Aspartate aminotransferase, low-density lipoprotein-cholesterol and nonalcoholic fatty liver disease activity score were independent determinants of decreased liver to spleen density ratio.

CONCLUSION

The present study suggests that atorvastatin improves the disease activity of nonalcoholic steatohepatitis partly via its tumour necrosis factor-α-lowering property.

Dietary supplementation with methyl donors reduces fatty liver and modifies the fatty acid synthase DNA methylation profile in rats fed an obesogenic diet

Non-alcoholic fatty liver disease (NAFLD) is one of the first hepatic manifestations of metabolic syndrome, whose progression can lead to cirrhosis and hepatic carcinoma. Interestingly, methyl donor supplementation could improve obesogenic diet-induced hepatic triglyceride accumulation. The aim of this research is to describe methyl donor effects on a high-fat-sucrose (HFS) diet in both sexes and epigenetic changes induced on fatty acid synthase (FASN) promoter methylation pattern as well as gene expression of NAFLD key metabolic genes. Twenty-four male and 28 female Wistar rats were assigned to three dietary groups: control, HFS, and HFS supplemented with methyl donors (choline, betaine, vitamin B12, and folic acid). After 8 weeks of treatment, somatic, biochemical, mRNA, and epigenetic measurements were performed. Rats fed the HFS diet presented an overweight phenotype and alterations in plasma biochemical measurements. Methyl donor supplementation reverted the HFS-diet-induced hepatic triglyceride accumulation. Analysis of FASN promoter cytosine methylation showed changes in both sexes due to the obesogenic diet at -1,096, -780, -778, and -774 CpG sites with respect to the transcriptional start site. Methyl donor supplementation modified DNA methylation at -852, -833, -829, -743, and -733 CpGs depending on the sex. RT-PCR analysis confirmed that FASN expression tended to be altered in males. Our findings reinforce the hypothesis that methyl donor supplementation can prevent hepatic triglyceride accumulation induced by obesogenic diets in both sexes. Changes in liver gene expression profile and epigenetic-mediated mechanisms related to FASN DNA hypermethylation could be involved in methyl donor-induced NAFLD improvement.

Molecular mechanisms of liver injury and hepatocarcinogenesis: focusing on the role of stress-activated MAPK

Hepatocellular carcinoma (HCC) is the third most common cause of cancer mortality. Short-term prognosis of patients with HCC has improved recently due to advances in early diagnosis and treatment, but long-term prognosis is still unsatisfactory. Therefore, obtaining a further understanding of the molecular carcinogenic mechanisms and the unique pathogenic biology of HCC is important. The most characteristic process in hepatocarcinogenesis is underlying chronic liver injury, which leads to repeated cycles of hepatocyte death, inflammation, and compensatory proliferation and subsequently provides a mitogenic and mutagenic environment leading to the development of HCC. Recent in vivo studies have shown that the stress-activated mitogen-activated protein kinase (MAPK) cascade converging on c-Jun NH(2)-terminal kinase (JNK) and p38 plays a central role in these processes, and it has attracted considerable attention as a therapeutic target. However, JNK and p38 have complex functions and a wide range of cellular effects. In addition, crosstalk with each other and the nuclear factor-kappaB pathway further complicate these functions. A full understanding is essential to bring these observations into clinical settings. In this paper, we discuss the latest findings regarding the mechanisms of liver injury and hepatocarcinogenesis focusing on the role of the stress-activated MAPK pathway.

The potential role of prebiotic fibre for treatment and management of non-alcoholic fatty liver disease and associated obesity and insulin resistance

Non-alcoholic fatty liver disease (NAFLD) and the more severe non-alcoholic steatohepatitis (NASH) represent a spectrum of diseases involving hepatic fat accumulation and histological features essentially identical to alcoholic liver disease; however, they occur in the absence of excessive alcohol intake. They typically arise in conjunction with one or more features of the metabolic syndrome. Lifestyle mediated weight loss remains the primary mode of therapy for NAFLD and NASH, but this is often ineffective and adjunctive medical and surgical treatments are presently lacking. Prebiotic fibres are a group of non-digestible carbohydrates that modulate the human microbiota in a manner that is advantageous to host health. Rodent studies suggest that dietary supplementation with prebiotic fibres positively impacts NAFLD by modifying the gut microbiota, reducing body fat, and improving glucoregulation. Future research should focus on placebo-controlled, human, clinical trials using histological endpoints to address the effects of prebiotics on NAFLD and NASH. The aim of this review is to summarize current knowledge about prebiotics as an emerging therapeutic target for NAFLD.

Obesity, inflammation, and liver cancer

Obesity has become a universal and major public health problem with increasing prevalence in both adults and children in the 21st century, even in developing countries. Extensive epidemiological studies reveal a strong link between obesity and development and progression of various types of cancers. The connection between obesity and liver cancer is particularly strong and obesity often results in liver diseases such as non-alcoholic fatty liver disease (NAFLD) and the more severe non-alcoholic steatohepatitis (NASH). NASH is characterized by fatty liver inflammation and is believed to cause fibrosis and cirrhosis. The latter is a known liver cancer risk factor. In fact due to its much higher prevalence obesity may be a more substantial contributor to overall hepatocellular carcinoma burden than infection with hepatitis viruses. Here we review and discuss recent advances in elucidation of cellular and molecular alterations and signaling pathways associated with obesity and liver inflammation and their contribution to hepatocarcinogenesis.

Inflammation and fibrogenesis in steatohepatitis

Nonalcoholic fatty liver disease consists of a range of disorders characterized by excess accumulation of triglyceride within the liver. Whereas simple steatosis is clinically benign, nonalcoholic steatohepatitis (NASH) often progresses to cirrhosis. Inflammation and fibrogenesis are closely inter-related and are major targets of NASH research. Experimental data have shown that inflammation in NASH is caused by insulin resistance, systemic lipotoxicity due to overnutrition, lipid metabolites, the production of proinflammatory cytokines and adipokines by visceral adipose tissue, gut-derived bacteria, and oxidative stress. In NASH-associated fibrosis, the principal cell type responsible for extracellular matrix production is recognized as the hepatic stellate cell. Although the fibrotic mechanisms underlying NASH are largely similar to those observed in other chronic liver diseases, the altered patterns of circulating adipokines, the generation of oxidative stress, and the hormonal profile associated with the metabolic syndrome might play unique roles in the fibrogenesis associated with the disease. Information on the basic pathogenesis of NASH with a focus on the generation of inflammation and fibrosis will be discussed.

Serum interleukin 1 receptor antagonist as an independent marker of non-alcoholic steatohepatitis in humans

BACKGROUND & AIMS

Mechanisms leading to non-alcoholic steatohepatitis (NASH) have remained unclear, and non-invasive diagnosis of NASH is challenging. In this study, we investigated the benefits of measuring serum interleukin 1 receptor antagonist (IL-1RA) levels.

METHODS

Liver biopsies from 119 morbidly obese individuals (47.5 ± 9.0 years, BMI 44.9 ± 5.9 kg/m(2)) were used for histological and gene expression assessment. In a cross-sectional population-based cohort of 6447 men (58 ± 7 years, BMI 27.0 ± 3.9 kg/m(2)) the association of serum IL1-RA with serum alanine aminotransferase (ALT) levels was investigated.

RESULTS

Serum levels of IL-1RA, and liver mRNA expression of IL1RN are associated with NASH and the degree of lobular inflammation in liver (p<0.05). The decrease in serum IL-1RA level and expression of IL1RN after obesity surgery correlated with the improvement of lobular inflammation (p<0.05). We developed a novel NAFLD Liver Inflammation Score, including serum Il-1RA concentration, which performed better to diagnose NASH than did previously published scores. Results from the population study confirmed the potential of measuring serum IL-1RA level. The strongest determinants of the ALT concentration at the population level were Matsuda insulin sensitivity index (r(2)=0.130, p=7 × 10(-197)) and serum IL-1RA concentration (r(2)=0.074, p=1 × 10(-110)). IL-1RA concentrations associated significantly with ALT levels even after adjusting for BMI, alcohol consumption and insulin sensitivity (p=2 × 10(-21)).

CONCLUSIONS

IL-1RA serum levels associate with liver inflammation and serum ALT independently of obesity, alcohol consumption and insulin resistance, suggesting a potential use of IL-1RA as a non-invasive inflammatory marker for NASH.

The association between adipocytokines and biomarkers for nonalcoholic fatty liver disease-induced liver injury: a study in the general population

BACKGROUND AND AIM

Leptin and adiponectin have been implicated in the development of nonalcoholic fatty liver disease (NAFLD). However, the usefulness of adipocytokines as a screening tool for nonalcoholic steatohepatitis (NASH) and fibrosis could not be evaluated in the general population due to the invasive nature of liver biopsy. The aim was to evaluate the association between adipocytokines and presumed liver injury in the general population using noninvasive biomarkers.

METHODS

A cross-sectional study of 375 individuals, sampled from the National Health Survey was conducted. The exclusion criterion was any known secondary etiology for liver disease. Anthropometrics, serum leptin, adiponectin, insulin, lipids, and FibroMax were measured.

RESULTS

Three hundred and thirty-eight individuals met the inclusion criteria and had valid FibroMax. Fibrosis diagnosed by the FibroTest was found in 25.7% of the patients, of whom 12.8% had significant fibrosis. Steatohepatitis was diagnosed by the NASH test in 0.9% and borderline NASH in 31.4% of the patients. Adiponectin was an independent negative correlate of borderline NASH [odds ratio (OR): 0.92; 95% confidence interval (CI): 0.86-0.98/1 µg/ml] together with high-density lipoprotein, and leptin was a positive correlate (OR: 1.03; CI: 1.01-1.06/1 ng/ml), together with abdominal obesity, serum triglycerides, and HbA1C. The OR for borderline NASH was 20.7 (CI: 7.5-57.5) when both high leptin (upper quartile) and suboptimal adiponectin were present, adjusting for age and sex. The FibroTest was not associated with leptin and adiponectin. The strongest predictors for fibrosis were age, sex, abdominal obesity, and insulin.

CONCLUSION

Low adiponectin and high leptin and the combination of both have a strong independent association with presumed early-stage NASH. However, early-stage fibrosis cannot be predicted by these adipocytokines.

Role of cytokines and chemokines in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) includes a variety of histological conditions (ranging from liver steatosis and steatohepatitis, to fibrosis and hepatocarcinoma) that are characterized by an increased fat content within the liver. The accumulation/deposition of fat within the liver is essential for diagnosis of NAFLD and might be associated with alterations in the hepatic and systemic inflammatory state. Although it is still unclear if each histological entity represents a different disease or rather steps of the same disease, inflammatory processes in NAFLD might influence its pathophysiology and prognosis. In particular, non-alcoholic steatohepatitis (the most inflamed condition in NAFLDs, which more frequently evolves towards chronic and serious liver diseases) is characterized by a marked activation of inflammatory cells and the upregulation of several soluble inflammatory mediators. Among several mediators, cytokines and chemokines might play a pivotal active role in NAFLD and are considered as potential therapeutic targets. In this review, we will update evidence from both basic research and clinical studies on the potential role of cytokines and chemokines in the pathophysiology of NAFLD.

Caffeine is protective in patients with non-alcoholic fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD), the hepatic manifestation of metabolic syndrome, is the most common cause of primary liver disease. Although recent studies have found that coffee drinking is protective against end stage chronic liver disease, there are scarce caffeine intake data in NAFLD specifically.

AIM

To investigate the effects of dietary behaviour in NAFLD patients, using four continuous cycles of the National Health and Nutrition Examination Surveys (NHANES 2001-2008).

METHODS

Using data from four continuous cycles of NHANES, dietary intake questionnaires that list 62 nutrition components. Logistic regression was used to identify independent predictors of NAFLD among nutrition components after adjustment for potential clinical confounders. All analyses were run using sas 9.1 and SUDAAN 10.0 (SAS Institute Inc., Cary, NC, USA).

RESULTS

Of the 62 nutrient components used for the univariate analysis, 38% were significant (P-value <0.05) in NAFLD with caffeine consumption being higher in the control group (P-value <0.001). The multivariate analysis using demographics, clinical parameters and nutritional components found five factors independently associated with NAFLD [African American Race P-value <0.001); Male gender P-value <0.001); Obesity (BMI ≥ 30) P-value <0.001); Caffeine intake (mg) P-value <0.001) and total plain water consumption (g) P-value ≤ 0.02)].

CONCLUSIONS

Our analysis shows that caffeine intake is independently associated with a lower risk for NAFLD suggesting a potential protective effect. These data necessitate further research to elucidate the mechanism by which caffeine can protect against NAFLD.

Colorectal neoplasms in relation to non-alcoholic fatty liver disease in Korean women: a retrospective cohort study

BACKGROUND AND AIM

Metabolic syndrome has been associated with an increased risk for colorectal cancer. Non-alcoholic fatty liver disease (NAFLD) is regarded as a hepatic manifestation of metabolic syndrome. We investigated whether NAFLD is associated with colorectal neoplasms in Korean women.

METHODS

This retrospective cohort study included data from 5517 women, aged 35-80 years, who underwent life insurance company health examinations between July 2002 and June 2006. Fatty liver disease was assessed by abdominal ultrasound, with NAFLD defined as fatty liver disease in the absence of alcohol use of > 40 g/week or other secondary causes. The incidence of colorectal neoplasms through December 2008 was obtained through medical certificate codes for insurance claims. The association between NAFLD and the risk of colorectal neoplasms was estimated using standard Cox proportional hazards models.

RESULTS

Of the study population, 15.1% were diagnosed with NAFLD. During follow-up, 65 women were verified as having adenomatous polyps and 15 as having colorectal cancer. Adjusted relative risks (95% confidence interval [CI]) for adenomatous polyps by age, low high-density lipoprotein-cholesterol, and NAFLD were 1.12 (95% CI 1.09-1.15), 2.56 (95% CI 1.53-4.28) and 1.94 (95% CI 1.11-3.40). Adjusted relative risks (95% CI) for colorectal cancer by age and NAFLD were 1.23 (95% CI 1.17-1.29) and 3.08 (95% CI 1.02-9.34).

CONCLUSIONS

  Our findings demonstrate a significant relationship between NAFLD and colorectal neoplasms. Among the various manifestations of metabolic syndrome, NAFLD may predict the development of colorectal neoplasms in Korean women.

Non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) refers to the accumulation of hepatic steatosis not due to excess alcohol consumption. The prevalence of NAFLD is up to 30% in developed countries and nearly 10% in developing nations, making NAFLD the most common liver condition in the world. The pathogenesis of NAFLD is related to insulin resistance and, thus, it is frequently found in individuals who have central obesity or diabetes. Insulin resistance and excess adiposity are associated with increased lipid influx into the liver and increased de novo hepatic lipogenesis, promoting hepatic triglyceride accumulation. Defects in lipid utilization via mitochondrial oxidation and lipid export may also contribute to hepatic lipid build-up. Adipocytokine alterations, lipotoxicity from saturated fatty acids and fructose have been all been implicated in causing hepatocyte injury in NAFLD through pathways involving oxidative and endoplasmic reticulum stress. Clinically, NAFLD is commonly asymptomatic and frequently detected incidentally by blood liver function tests or imaging performed for other reasons. Subjects with NAFLD have a higher mortality rate than the general population and are at increased risk of developing cardiovascular disease and diabetes in the future. Histologically, NAFLD occurs as a spectrum from mild hepatic steatosis only, to non-alcoholic steatohepatitis (NASH) characterized by hepatocellular injury and inflammation, to cirrhosis. A diagnosis of NASH with associated fibrosis heralds a more significant prognosis as it is more likely to progressive to cirrhosis with complications of hepatic failure and hepatocellular carcinoma. Currently, the diagnosis of NASH requires a liver biopsy, however, serum based markers of hepatocyte apoptosis such as cytokeratin-18 fragments offer promise as accurate non-invasive diagnostic tests. Treatment of NAFLD revolves around addressing concomitant metabolic risk factors and improving insulin resistance through weight loss measures and exercise. Insulin sensitizing agents such as pioglitazone and anti-oxidant agents such as vitamin E show some promise in improving liver histology in patients with NASH, however, the long-term benefit of these medications has not been demonstrated.

Plasma adiponectin--an independent indicator of liver fat accumulation

Proinflammatory cytokines and adipokines have a significant role in the development and progression of fatty liver. The aim of our current study was to explore the major indicators for hepatic fat determined as liver brightness. In addition to peptide hormones, several known cardiovascular and metabolic risk factors were included in the model. This is a population-based, epidemiological, cross-sectional study where 1200 subjects (600 men and 600 women, aged 40-59 years) were randomly selected, half of them having hypertension and half of them being controls. The severity of liver adiposity was measured by ultrasound and based on the brightness of the liver estimated as a numerical value ranging from 0 to 2. With respect to the studied peptide hormones, the associations between liver brightness and plasma adiponectin (P < .001), leptin (P < .001), ghrelin (P = .005), and highly sensitive C-reactive protein concentrations (P < .001) were significant before adjustments. When several other risk factors (age, sex, body mass index, waist circumference, quantitative insulin sensitivity check index, smoking, and alcohol consumption) and novel risk markers (adiponectin, leptin, ghrelin, and highly sensitive C-reactive protein concentrations) were considered simultaneously, of the peptide hormones, adiponectin remained the strongest independent indicator of the brightness of the liver (P = .025). Adiponectin is a very strong predictor for liver brightness, even after adjustment for the numerous other metabolic risk factors, markers of inflammation, and novel obesity-related peptide hormones. Whether low adiponectin levels predict to liver fat accumulation remains to be explored in a future prospective follow-up of this cohort.

Some inflammatory cytokine levels, iron metabolism and oxidan stress markers in subjects with nonalcoholic steatohepatitis

OBJECTIVES

The relation between nonalcoholic steatohepatitis and iron metabolism is still controversial. Free fatty acids, iron, and other sources of oxidative stress probably result in cell damage, and necroinflammation mediated by various cytokines.

DESIGN AND METHODS

Sixty patients were diagnosed with NASH were included in the study, and the patient group was divided into three subgroups. Iron metabolism markers, inflammatory cytokines, including TNF-α, IL-6 and IL-8, MDA and nitric oxide levels were measured.

RESULTS

Serum ferritin, inflammatory cytokines, and oxidative stress markers were significantly higher in the patient group. Among three patient groups, divided according to the results of ultrasonic examination, there were significant changes with regard to these parameters.

CONCLUSION

The study results suggest that liver iron and fat accumulation, oxidant stres, and inflammatory cytokines are closely related. Therefore, levels of serum ferritin, MDA, IL-6, TNF-α and IL-8 could represent the indices of activity and progression of NASH.

Safety and impact on cardiovascular events of long-term multifactorial treatment in patients with metabolic syndrome and abnormal liver function tests: a post hoc analysis of the randomised ATTEMPT study

INTRODUCTION

Non-alcoholic fatty liver disease (NAFLD), a hepatic manifestation of metabolic syndrome (MetS), is common and accounts for 80% of cases of elevated liver function tests (LFTs). We assessed the long-term effects of multifactorial intervention on LFTs and their association with cardiovascular disease (CVD) events in patients with MetS without diabetes mellitus or CVD.

MATERIAL AND METHODS

This prospective, randomized, open label study included 1,123 patients (aged 45-65 years). Patients received intensive lifestyle intervention and pharmacotherapy: atorvastatin in all patients (low density lipoprotein cholesterol [LDL-C] targets of<100 mg/dl [group A] or<130 mg/dl [group B]), inhibitors of the renin-angiotensin-aldosterone axis for hypertension, metformin for dysglycaemia and orlistat for obesity.

RESULTS

Among participants, 326 had modestly elevated LFTs and ultrasonographic (US) evidence of NAFLD (165 patients in group A2 and 161 patients in group B2). The NAFLD resolved during the 42-month treatment period in 86% of patients in group A2 and in 74% of patients in group B2 (p<0.001). In both groups nearly 90% of patients attained lipid goals. Mean LDL-C and TG levels were higher in group B2 than in group A2 (p<0.001). There were no CVD events in group A2 whereas 5 non-fatal events occurred in group B2 (log-rank-p = 0.024). There were no major side-effects.

CONCLUSIONS

Attaining multiple treatment targets is safe and beneficial in primary prevention patients with MetS and NAFLD. Lipid levels and LFTs normalized, US findings associated with NAFLD resolved and no CVD events occurred in patients with LDL-C levels<100 mg/dl (group A2). Resolution of NAFLD might have contributed to the prevention of CVD events.

Adipokines and redox signaling: impact on fatty liver disease

Adipokines (adipose tissue cytokines) are polypeptide factors secreted by adipose tissue in a highly regulated manner. The 'classical' adipokines (leptin, adiponectin, and resistin) are expressed only by adipocytes, but other adipokines have been shown to be released by resident and infiltrating macrophages, as well as by components of the vascular stroma. Indeed, adipose tissue inflammation is known to be associated with a modification in the pattern of adipokine secretion. Several studies indicate that adipokines can interfere with hepatic injury associated with fatty infiltration, differentially modulating steatosis, inflammation, and fibrosis. Moreover, plasma levels of adipokines have been investigated in patients with nonalcoholic fatty liver disease in order to establish correlations with the underlying state of insulin resistance and with the type and severity of hepatic damage. In this Forum article, we provide a review of recent data that suggest a significant role for oxidative stress, reactive oxygen species, and redox signaling in mediating actions of adipokines that are relevant in the pathogenesis of nonalcoholic fatty liver disease, including hepatic insulin resistance, inflammation, and fibrosis.

Role of adiponectin in the pathogenesis and treatment of nonalcoholic fatty liver disease

Adiponectin is an insulin-sensitizing adipokine possessing multiple beneficial effects on nonalcoholic fatty liver disease. This adipokine is secreted from adipocytes into the circulation as three oligomeric isoforms: trimer, hexamer and the high molecular weight (HMW) oligomeric complex. Adiponectin binds to its receptor to exert its effects on target organs. The hepato-protective activities of adiponectin have been demonstrated by many clinical and experimental studies. Decreased level of serum adiponectin represents an independent risk factor for (NAFLD and liver dysfunction in humans. In animals, elevation of circulating adiponectin by either pharmacological or genetic approaches leads to a significant alleviation of hepatomegaly, steatosis and necro-inflammation associated with various liver diseases. In adiponectin knockout mice, there is a pre-existing condition of hepatic steatosis and mitochondrial dysfunction, which might contribute to increased vulnerability of these mice to secondary liver injuries induced by obesity and other conditions. This review aims to summarize the recent advances in research of the structural, molecular and cellular mechanisms underlying the hepato-protective properties of adiponectin.

Potential role of leptin, adiponectin and three novel adipokines--visfatin, chemerin and vaspin--in chronic hepatitis

Chronic hepatitis C (CHC) is generally a slowly progressive disease, but some factors associated with rapid progression have been identified. Steatosis, independently of its metabolic or viral origin, leads to liver injury and fibrosis. It is suggested that hepatitis C virus may contribute to a wide spectrum of metabolic disturbances-namely, steatosis, insulin resistance, increased prevalence of impaired glucose tolerance, type 2 diabetes mellitus and lipid metabolism abnormalities. Adipokines, which are produced mainly by adipose tissue, may influence the inflammatory response and insulin sensitivity and contribute to the development of metabolic abnormalities in CHC and also regulate fibrogenesis and angiogenesis. Visfatin was described as an adipokine with immunomodulating and proinflammatory properties that promotes B-cell maturation and enhances activation of leukocytes, synthesis of adhesion molecules and production of proinflammatory cytokines. Visfatin exerts insulin-mimetic effects, decreases plasma glucose levels and regulates cell energy balance. Chemerin stimulates chemotaxis of dendritic cells, macrophages and natural killer (NK) cells toward the site of inflammation. On the other hand, it inhibits synthesis of proinflammatory mediators and enhances adiponectin production, influences adipocyte differentiation and maturation and regulates glucose uptake in adipocytes. Vaspin expression in human adipose tissue seems to be a compensatory mechanism associated with obesity and insulin resistance. Vaspin suppresses leptin, tumor necrosis factor (TNF)-α and resistin expression. Leptin protects against liver steatosis but accelerates fibrosis progression and exacerbates the inflammatory process. In contrast, adiponectin exerts a hepatoprotective effect. In this report, data indicating a possible role of these adipokines in the pathogenesis of chronic hepatitis are summarized.

Drug metabolism alterations in nonalcoholic fatty liver disease

Drug-metabolizing enzymes play a vital role in the elimination of the majority of therapeutic drugs. The major organ involved in drug metabolism is the liver. Chronic liver diseases have been identified as a potential source of significant interindividual variation in metabolism. Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the United States, affecting between 60 and 90 million Americans, yet the vast majority of NAFLD patients are undiagnosed. NAFLD encompasses a spectrum of pathologies, ranging from steatosis to nonalcoholic steatohepatitis and fibrosis. Numerous animal studies have investigated the effects of NAFLD on hepatic gene expression, observing significant alterations in mRNA, protein, and activity levels. Information on the effects of NAFLD in human patients is limited, though several significant investigations have recently been published. Significant alterations in the activity of drug-metabolizing enzymes may affect the clearance of therapeutic drugs, with the potential to result in adverse drug reactions. With the enormous prevalence of NAFLD, it is conceivable that every drug currently on the market is being given to patients with NAFLD. The current review is intended to present the results from both animal models and human patients, summarizing the observed alterations in the expression and activity of the phase I and II drug-metabolizing enzymes.

Melanin and melanogenesis in adipose tissue: possible mechanisms for abating oxidative stress and inflammation?

Obesity has become a worldwide epidemic and can lead to multiple chronic diseases. Adipose tissue is increasingly thought to play an active role in obesity-related pathologies such as insulin resistance and non-alcoholic fatty liver disease. Obesity has been strongly associated with systemic inflammation and, to a lesser degree, with oxidative stress, although the causal relationships among these factors are unclear. A recent study demonstrating an expression of the components of the melanogenic pathway and the presence of melanin in visceral adipose has raised questions regarding the possible role of melanogenesis in adipose tissue. As this study also found larger amounts of melanin in the adipose tissue of obese patients relative to lean ones, we hypothesize that melanin, a pigment known for its antioxidant and anti-inflammatory properties, may scavenge reactive oxygen species and abate oxidative stress and inflammation in adipose tissue. This review considers the evidence to support such a hypothesis, and speculates on the role of melanin within adipocytes. Furthermore, we consider whether the α-melanocyte-stimulating hormone or its synthetic analogues could be used to stimulate melanin production in adipocytes, should the hypothesis be supported in future experiments.