Novel treatment modalities for nonalcoholic steatohepatitis

Astrocyte Elevated Gene-1 Cys75 S-Palmitoylation by ZDHHC6 Regulates Its Biological Activity

Nonalcoholic fatty liver disease is a major risk factor for hepatocellular carcinoma (HCC). Astrocyte elevated gene-1/Metadherin (AEG-1/MTDH) augments lipid accumulation (steatosis), inflammation, and tumorigenesis, thereby promoting the whole spectrum of this disease process. Targeting AEG-1 is a potential interventional strategy for nonalcoholic steatohepatitis (NASH) and HCC. Thus, proper understanding of the regulation of this molecule is essential. We found that AEG-1 is palmitoylated at residue cysteine 75 (Cys75). Mutation of Cys75 to serine (Ser) completely abolished AEG-1 palmitoylation. We identified ZDHHC6 as a palmitoyltransferase catalyzing the process in HEK293T cells. To obtain insight into how palmitoylation regulates AEG-1 function, we generated knock-in mice by CRISPR/Cas9 in which Cys75 of AEG-1 was mutated to Ser (AEG-1-C75S). No developmental or anatomical abnormality was observed between AEG-1-wild type (AEG-1-WT) and AEG-1-C75S littermates. However, global gene expression analysis by RNA-sequencing unraveled that signaling pathways and upstream regulators, which contribute to cell proliferation, motility, inflammation, angiogenesis, and lipid accumulation, were activated in AEG-1-C75S hepatocytes compared to AEG-1-WT. These findings suggest that AEG-1-C75S functions as dominant positive and that palmitoylation restricts oncogenic and NASH-promoting functions of AEG-1. We thus identify a previously unknown regulatory mechanism of AEG-1, which might help design new therapeutic strategies for NASH and HCC.

The mother relationship between insulin resistance and non-alcoholic steatohepatitis: Glucosinolates hydrolysis products as a promising insulin resistance-modulator and fatty liver-preventer

Non-alcoholic fatty liver disease (NFLD) is one of the present public health problems which have no specific and effective treatment. The speed of the disease progression depends on the patient's lifestyle. Due to life stresses and lack of time, a high number of people depend on fast food containing a high amount of fats which one of the main causes of insulin resistance (IR). IR is one of the metabolic disorders which strongly intersected with molecular NAFLD and leading to its progression into non-alcoholic steatohepatitis (NASH). In this review, we introduced the updated statistics of NAFLD and NASH progression all over the world shows its importance, etiologies, and pathogenesis. Also, IR and its role in NASH initiation and progression explored, and current treatments with its limitations have been explained. Glucosinolates (GLS) is a group of phytochemicals which known by its potent hydrolysis products with promising anti-cancer effect. In this review, we have collected the recent experimental studies of different GLS hydrolysis products against IR and chronic liver diseases supported by our lab finding. Finally, we recommend this group of phytochemicals as promising molecules to be studied experimentally and clinically against a wide range of chronic liver diseases with an acceptable safety margin.

Changes in the distribution of etiologies of cirrhosis among patients referred for liver transplantation over 11 years in Iran

BACKGROUND AND AIM

Cirrhosis is a major public health problem worldwide. The prevalence of cirrhosis is various in different geographical regions. The aim of the present study was to determine the distribution of the etiologies of cirrhosis and their proportional changes through recent 11 years in Iran.

METHODS

In this retrospective, observational study, the data of cirrhotic patients who have been listed for liver transplantation in the Namazi Transplant Center (Shiraz, Iran) between January 2006 and December 2016 were analyzed. Demographic and clinical data of the patients including model for end-stage liver disease score, year of registration, and the etiologic diagnosis for each patient were retrieved.

RESULTS

The ratio of males to females was the highest (2.6:1) in patients with age over 50 years. Of 4891 patients, hepatitis B virus cirrhosis had the highest frequency (23.53%) and alcoholic cirrhosis had the lowest frequency (1.70%). The percentages of waiting list patients with hepatitis B virus (34.48%-17.48%) (P < 0.001), autoimmune hepatitis (12.64%-8.50%) (P = 0.037), and alcoholic cirrhosis (2.30%-1.10%) were decreased (P = 0.008) and the percentages of waiting list patients with cholestatic (12.64%-25.20%) and nonalcoholic steatohepatitis cirrhosis (0.77%-8.82%) were increased over 11 years (both P < 0.001). Hepatitis B virus and autoimmune hepatitis cirrhosis were the most prevalent in male and female patients, respectively.

CONCLUSION

The results of the present study showed an increase in the frequency of cholestasis and nonalcoholic steatohepatitis cirrhosis and therefore it should be considered in the health policy implementation.

Liver Transplantation for Nonalcoholic Steatohepatitis: Pathophysiology of Recurrence and Clinical Challenges

Nonalcoholic steatohepatitis is the fastest-growing indication for the liver transplant and a leading cause of hepatocellular carcinoma among patients listed for liver transplantation in the USA. Post-transplant nonalcoholic hepatic steatosis and steatohepatitis are frequent complications of liver transplantation. Nonalcoholic steatohepatitis poses a significant challenge in both pre- and post-transplant period due to its association with metabolic syndrome, coronary artery disease, chronic kidney disease, and obstructive sleep apnea. While optimal therapy is not yet available in the post-liver transplant setting, lifestyle interventions continue to remain as the mainstay of therapy for post-transplant nonalcoholic steatohepatitis. Early recognition with protocol biopsies and noninvasive modalities, along with modification of known risk factors, are the most effective methods to curtail the progression of nonalcoholic steatohepatitis in the absence of FDA-approved pharmacologic therapy.

PPAR δ inhibition protects against palmitic acid-LPS induced lipidosis and injury in cultured hepatocyte L02 cell

Background: Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, and its pathogenesis and mechanism are intricate. In the present study, we aimed to evaluate the role of PPAR δ in LPS associated NAFLD and to investigate the signal transduction pathways underlying PPAR δ treatment in vitro. Material and Methods: L02 cells were exposed to palmitic acid (PA) and/or LPS in the absence or presence of PPAR δ inhibition and/or activation. Results: LPS treatment markedly increased lipid deposition, FFA contents, IL-6 and TNF-α levels, and cell apoptosis in PA treatment (NAFLD model). PPAR δ inhibition protects L02 cells against LPS-induced lipidosis and injury. Conversely, the result of PPAR δ activation showed the reverse trend. LPS+PA treatment group significantly decreases the relative expression level of IRS-1, PI3K, AKT, phosphorylation of AKT, TLR-4, MyD88, phosphorylation of IKKα, NF-κB, Bcl-2 and increases the relative expression level of Bax, cleaved caspase 3 and cleaved caspase 8, compared with the cells treated with NAFLD model. PPAR δ inhibition upregulated the related proteins' expression level in insulin resistance and inflammation pathway and downregulated apoptotic relevant proteins. Instead, PPAR δ agonist showed the reverse trend. Conclusion: Our data show that PPAR δ inhibition reduces steatosis, inflammation and apoptosis in LPS-related NAFLD damage, in vitro. PPAR δ may be a potential therapeutic implication for NAFLD.

Mixed micelles loaded with the 5-benzylidenethiazolidine-2,4-dione derivative SKLB023 for efficient treatment of non-alcoholic steatohepatitis

Background: SKLB023, a novel 5-benzylidenethiazolidine-2,4-dione based-derivative, specifically inhibits inducible nitric oxide synthase and shows promise for treating non-alcoholic steatohepatitis (NASH). However, its poor water solubility and low bioavailability limits its clinical use. Here the drug was loaded into phosphatidylcholine-bile salt-mixed micelles (PBMM/SKLB023) to overcome these limitations. Methods: PBMM/SKLB023 was developed using a simple co-precipitation method, and formulation parameters were optimized. The pharmacokinetics of PBMM/SKLB023 were investigated in Wistar rats, and therapeutic efficacy was assessed in a mouse model of NASH induced by a diet deficient in methionine- and choline. Results: PBMM/SKLB023 particles were 11.36±2.08 nm based on dynamic light scattering, and loading the drug into micelles improved its water solubility 300-fold. PBMM/SKLB023 inhibited proliferation and activation of HSC-T6 cells more strongly than free SKLB023. PBMM/SKLB023 showed longer mean retention time and higher bioavailability than the free drug after intravenous injection in Wistar rats. In the mouse model of NASH, PBMM/SKLB023 alleviated hepatic lipid accumulation, inflammation, and fibrosis to a significantly greater extent than free SKLB023. Conclusion: PBMM/SKLB023 shows therapeutic potential for treating NASH and liver fibrosis.

HSPA12A Is a Novel Player in Nonalcoholic Steatohepatitis via Promoting Nuclear PKM2-Mediated M1 Macrophage Polarization

Nonalcoholic steatohepatitis (NASH) is the most prevalent cause of chronic liver disease worldwide. Macrophage-mediated inflammation plays a critical role in NASH pathogenesis; however, optimum therapies for macrophage activation and NASH remain elusive. HSPA12A encodes a novel member of the HSP70 family. Here, we report that NASH patients showed increased hepatic HSPA12A expression and serum HSPA12A contents. Intriguingly, knockout of HSPA12A (Hspa12a-/- ) in mice attenuated high-fat diet (HFD)-induced hepatic steatosis and injury. HFD-induced macrophage polarization toward an M1 phenotype and inflammatory responses in the liver of Hspa12a-/- mice were also attenuated. Loss- and gain-of-function studies revealed that the de novo lipogenesis in hepatocytes was regulated by the paracrine effects of macrophage HSPA12A rather than by hepatocyte HSPA12A. In-depth molecular analysis revealed that HSPA12A interacted with the M2 isoform of pyruvate kinase (PKM2) in macrophages and increased its nuclear translocation, thereby promoting M1 polarization and secretion of proinflammatory M1 cytokines; this led, ultimately, to hepatocyte steatosis via paracrine effects. Taken together, these findings show that HSPA12A acts as a novel regulator of M1 macrophage polarization and NASH pathogenesis by increasing nuclear PKM2. Strategies that inhibit macrophage HSPA12A might be a potential therapeutic intervention for NASH.

A novel role of astrocyte elevated gene-1 (AEG-1) in regulating nonalcoholic steatohepatitis (NASH)

Nonalcoholic steatohepatitis (NASH) is the most prevalent cause of chronic liver disease in the Western world. However, an optimum therapy for NASH is yet to be established, mandating more in-depth investigation into the molecular pathogenesis of NASH to identify novel regulatory molecules and develop targeted therapies. Here, we unravel a unique function of astrocyte elevated gene-1(AEG-1)/metadherin in NASH using a transgenic mouse with hepatocyte-specific overexpression of AEG-1 (Alb/AEG-1) and a conditional hepatocyte-specific AEG-1 knockout mouse (AEG-1^ΔHEP ). Alb/AEG-1 mice developed spontaneous NASH whereas AEG-1^ΔHEP mice were protected from high-fat diet (HFD)-induced NASH. Intriguingly, AEG-1 overexpression was observed in livers of NASH patients and wild-type (WT) mice that developed steatosis upon feeding HFD. In-depth molecular analysis unraveled that inhibition of peroxisome proliferator-activated receptor alpha activity resulting in decreased fatty acid β-oxidation, augmentation of translation of fatty acid synthase resulting in de novo lipogenesis, and increased nuclear factor kappa B-mediated inflammation act in concert to mediate AEG-1-induced NASH. Therapeutically, hepatocyte-specific nanoparticle-delivered AEG-1 small interfering RNA provided marked protection from HFD-induced NASH in WT mice.

CONCLUSION

AEG-1 might be a key molecule regulating initiation and progression of NASH. AEG-1 inhibitory strategies might be developed as a potential therapeutic intervention in NASH patients. (Hepatology 2017;66:466-480).

Oxidative Stress as a Critical Factor in Nonalcoholic Fatty Liver Disease Pathogenesis

SIGNIFICANCE

Nonalcoholic fatty liver disease (NAFLD), characterized by liver triacylglycerol build-up, has been growing in the global world in concert with the raised prevalence of cardiometabolic disorders, including obesity, diabetes, and hyperlipemia. Redox imbalance has been suggested to be highly relevant to NAFLD pathogenesis. Recent Advances: As a major health problem, NAFLD progresses to the more severe nonalcoholic steatohepatitis (NASH) condition and predisposes susceptible individuals to liver and cardiovascular disease. Although NAFLD represents the predominant cause of chronic liver disorders, the mechanisms of its development and progression remain incompletely understood, even if various scientific groups ascribed them to the occurrence of insulin resistance, dyslipidemia, inflammation, and apoptosis. Nevertheless, oxidative stress (OxS) more and more appears as the most important pathological event during NAFLD development and the hallmark between simple steatosis and NASH manifestation.

CRITICAL ISSUES

The purpose of this article is to summarize recent developments in the understanding of NAFLD, essentially focusing on OxS as a major pathogenetic mechanism. Various attempts to translate reactive oxygen species (ROS) scavenging by antioxidants into experimental and clinical studies have yielded mostly encouraging results.

FUTURE DIRECTIONS

Although augmented concentrations of ROS and faulty antioxidant defense have been associated to NAFLD and related complications, mechanisms of action and proofs of principle should be highlighted to support the causative role of OxS and to translate its concept into the clinic. Antioxid. Redox Signal. 26, 519-541.

Interleukin-1α deficiency attenuates endoplasmic reticulum stress-induced liver damage and CHOP expression in mice

BACKGROUND & AIMS

ER stress promotes liver fat accumulation and induction of inflammatory cytokines, which contribute to the development of steatohepatitis. Unresolved ER stress upregulates the pro-apoptotic CHOP. IL-1α is localized to the nucleus in apoptotic cells, but is released when these cells become necrotic and induce sterile inflammation. We investigated whether IL-1α is involved in ER stress-induced apoptosis and steatohepatitis.

METHODS

We employed WT and IL-1α-deficient mice to study the role of IL-1α in ER stress-induced steatohepatitis.

RESULTS

Liver CHOP mRNA was induced in a time dependent fashion in the atherogenic diet-induced steatohepatitis model, and was twofold lower in IL-1α deficient compared to WT mice. In the ER stress-driven steatohepatitis model, IL-1α deficiency decreased the elevation in serum ALT levels, the number of apoptotic cells (measured as caspase-3-positive hepatocytes), and the expression of IL-1β, IL-6, TNFα, and CHOP, with no effect on the degree of fatty liver formation. IL-1α was upregulated in ER-stressed-macrophages and the protein was localized to the nucleus. IL-1β mRNA and CHOP mRNA and protein levels were lower in ER-stressed-macrophages from IL-1α deficient compared to WT mice. ER stress induced the expression of IL-1α and IL-1β also in mouse primary hepatocytes. Recombinant IL-1α treatment in hepatocytes did not affect CHOP expression but upregulated both IL-1α and IL-1β mRNA levels.

CONCLUSION

We show that IL-1α is upregulated in response to ER stress and IL-1α deficiency reduces ER stress-induced CHOP expression, apoptosis and steatohepatitis. As a dual function cytokine, IL-1α may contribute to the induction of CHOP intracellularly, while IL-1α released from necrotic cells accelerates steatohepatitis via induction of inflammatory cytokines by neighboring cells.

Can serum pin1 level be regarded as an indicative marker of nonalcoholic steatohepatitis and fibrotic stages?

BACKGROUND

We aimed to investigate serum Pin1 as an indicator of the presence of nonalcoholic steatohepatitis (NASH) and its association with the histopathological liver fibrosis stages.

METHODS

Serum samples were collected from consecutive biopsy-proven NASH patients and healthy controls, and then serum levels of Pin1 were measured. The correlations between clinical and histopathological features of NASH and Pin1 were evaluated. Patients who had fibrotic stages <2 were termed mild fibrosis group and those who had ≥ 2 as advanced fibrosis group. We performed univariate and multivariate logistic regression analyses to evaluate the independent predicting factors for the presence of liver fibrosis caused by NASH.

RESULTS

Fifty-six consecutive NASH patients and 56 age- and sex-matched healthy controls were enrolled in the study. Serum Pin1 levels were significantly higher in NASH patients (39.24 ± 30.94) than in controls (27.7 ± 9.56, p < 0.001). In NASH patients, serum Pin1 levels were correlated with the histopathological features. Patients with advanced fibrosis had higher serum Pin1 levels than the mild fibrosis group (53.42 ± 33.8 vs. 33.24 ± 20.90, respectively; p < 0.001). In multivariate analysis, Pin1 remained an independent predicting factor of advanced liver fibrosis (OR: 1.051, 95% CI: 1.013-1.089, p < 0.05).

CONCLUSION

Serum Pin1 level can be used as a potential independent marker of the presence of the NASH and advanced fibrotic scores.

Antioxidant vitamins in the context of nonalcoholic fatty liver disease in obese children and adolescents

OBJECTIVE:

To review the literature on the importance of antioxidant vitamins, analyzed in the context of dietary intake, its plasma levels, and its current use as a supplementation treatment in obese children and adolescents with nonalcoholic fatty liver disease.

DATA SOURCES:

The articles were identified in Lilacs, Ibecs, SciELO, PubMed/Medline, and Scopus databases. To conduct the survey, the "fatty liver" descriptor was associated to the following words: "children", "antioxidants" and "vitamins". The search was limited to articles written in Portuguese, Spanish and English, with publication date until December, 2012.

DATA SYNTHESIS:

Six studies were selected. The survey revealed a low dietary intake and low antioxidant vitamins serum levels in this population. The changes in lifestyle, with adequate dietary intake of vitamins, and the increase in physical activity were associated with a significant improvement in liver histology and in laboratory tests. Vitamin supplementation also improved the disease progression markers, as the alanine aminotransferase serum levels and the histological characteristics of lobular inflammation and hepatocellular damage. However, these improvements were not statistically significant in all studies.

CONCLUSIONS:

There is insufficient evidence to recommend or to refute antioxidant supplementation in patients with simple steatosis or steatohepatitis. The changes in lifestyle seem to be, at the present time, the more advisable therapy.

Management of nonalcoholic fatty liver disease: an evidence-based clinical practice review

AIM

To build a consensus among Chilean specialists on the appropriate management of patients with nonalcoholic fatty liver disease (NAFLD) in clinical practice.

METHODS

NAFLD has now reached epidemic proportions worldwide. The optimal treatment for NAFLD has not been established due to a lack of evidence-based recommendations. An expert panel of members of the Chilean Gastroenterological Society and the Chilean Hepatology Association conducted a structured analysis of the current literature on NAFLD therapy. The quality of the evidence and the level of recommendations supporting each statement were assessed according to the recommendations of the United States Preventive Services Task Force. A modified three-round Delphi technique was used to reach a consensus among the experts.

RESULTS

A group of thirteen experts was established. The survey included 17 open-ended questions that were distributed among the experts, who assessed the articles associated with each question. The levels of agreement achieved by the panel were 93.8% in the first round and 100% in the second and third rounds. The final recommendations support the indication of lifestyle changes, including diet and exercise, for all patients with NAFLD. Proven pharmacological therapies include only vitamin E and pioglitazone, which can be used in nondiabetic patients with biopsy-proven nonalcoholic steatohepatitis (the progressive form of NAFLD), although the long-term safety and efficacy of these therapies have not yet been established.

CONCLUSION

Current NAFLD management is rapidly evolving, and new pathophysiology-based therapies are expected to be introduced in the near future. All NAFLD patients should be evaluated using a three-focused approach that considers the risks of liver disease, diabetes and cardiovascular events.

Lack of interleukin-1α in Kupffer cells attenuates liver inflammation and expression of inflammatory cytokines in hypercholesterolaemic mice

BACKGROUND

The role of Kupffer cell interleukin (IL)-1 in non-alcoholic steatohepatitis development remains unclear.

AIMS

To evaluate the role of Kupffer cell IL-1α, IL-1β or IL-1 receptor type-1 (IL-1R1) in steatohepatitis.

METHODS

C57BL/6 mice were irradiated and transplanted with bone marrow-derived cells from WT, IL-1α-/-, IL-1β-/- or IL-1R1-/- mice combined with Kupffer cell ablation with Gadolinium Chloride, and fed atherogenic diet. Plasma and liver triglycerides and cholesterol, serum alanine aminotransferase (ALT), liver histology and expression levels of inflammatory genes were assessed.

RESULTS

The ablation and replacement of Kupffer cells with bone marrow-derived cells was confirmed. The atherogenic diet elevated plasma and liver cholesterol, reduced plasma and liver triglycerides and increased serum ALT levels in all groups. Steatosis and steatohepatitis were induced, but without liver fibrosis. A reduction in the severity of portal inflammation was observed only in mice with Kupffer cell deficiency of IL-1α. Accordingly, liver mRNA levels of inflammatory genes encoding for IL-1α, IL-1β, TNFα, SAA1 and IL-6 were significantly lower in mice with Kupffer cell deficiency of IL-1α compared to WT mice.

CONCLUSION

Selective deficiency of IL-1α in Kupffer cells reduces liver inflammation and expression of inflammatory cytokines, which may implicate Kupffer cell-derived IL-1α in steatohepatitis development.

Lactobacillus casei strain Shirota protects against nonalcoholic steatohepatitis development in a rodent model

Gut microbiota alterations are associated with various disorders. In this study, gut microbiota changes were investigated in a methionine-choline-deficient (MCD) diet-induced nonalcoholic steatohepatitis (NASH) rodent model, and the effects of administering Lactobacillus casei strain Shirota (LcS) on the development of NASH were also investigated. Mice were divided into three groups, given the normal chow diet (NCD), MCD diet, or the MCD diet plus daily oral administration of LcS for 6 wk. Gut microbiota analyses for the three groups revealed that lactic acid bacteria such as Bifidobacterium and Lactobacillus in feces were markedly reduced by the MCD diet. Interestingly, oral administration of LcS to MCD diet-fed mice increased not only the L. casei subgroup but also other lactic acid bacteria. Subsequently, NASH development was evaluated based on hepatic histochemical findings, serum parameters, and various mRNA and/or protein expression levels. LcS intervention markedly suppressed MCD-diet-induced NASH development, with reduced serum lipopolysaccharide concentrations, suppression of inflammation and fibrosis in the liver, and reduced colon inflammation. Therefore, reduced populations of lactic acid bacteria in the colon may be involved in the pathogenesis of MCD diet-induced NASH, suggesting normalization of gut microbiota to be effective for treating NASH.

Gut microbiome and metabolic diseases

The prevalence of obesity and obesity-related disorders is increasing worldwide. In the last decade, the gut microbiota has emerged as an important factor in the development of obesity and metabolic syndrome, through its interactions with dietary, environmental, and host genetic factors. Various studies have shown that alteration of the gut microbiota, shifting it toward increased energy harvest, is associated with an obese phenotype. However, the molecular mechanisms by which the gut microbiota affects host metabolism are still obscure. In this review, we discuss the complexity of the gut microbiota and its relationship to obesity and obesity-related diseases. Furthermore, we discuss the anti-obesity potential of probiotics and prebiotics.

Non-alcoholic steatohepatitis: a microbiota-driven disease

Non-alcoholic fatty liver disease (NAFLD) has emerged as a major health problem worldwide. Whereas overnutrition and obesity are crucially involved in the development of a simple fatty liver, it remains unclear why approximately 10% of all affected individuals develop the 'inflammatory' phenotype so-called non-alcoholic steatohepatitis (NASH). A link between the intestinal microbiota and the development of obesity and its metabolic consequences including NAFLD is becoming clearer. First clinical, but especially experimental, studies are suggesting that microbiotal factors are driving forces of hepatic steatosis and inflammation that involve Toll-like receptors and proinflammatory cytokines such as tumor necrosis factor-α (TNFα). Future studies focused on deciphering how manipulation of the gut microbiota might prove beneficial for patients with NAFLD are warranted.

Ursodeoxycholyl lysophosphatidylethanolamide inhibits lipoapoptosis by shifting fatty acid pools toward monosaturated and polyunsaturated fatty acids in mouse hepatocytes

Ursodeoxycholyl lysophosphatidylethanolamide (UDCA-LPE) is a hepatoprotectant in inhibiting apoptosis, inflammation, and hyperlipidemia in mouse models of nonalcoholic steatohepatitis (NASH). We studied the ability of UDCA-LPE to inhibit palmitate (Pal)-induced apoptosis in primary hepatocytes and delineate cytoprotective mechanisms. We showed that lipoprotection by UDCA-LPE was mediated by cAMP and was associated with increases in triglycerides (TGs) and phospholipids (PLs). An inhibitor of cAMP-effector protein kinase A partially reversed the protective effects of UDCA-LPE. Lipidomic analyses of fatty acids and PL composition revealed a shift of lipid metabolism from saturated Pal to monounsaturated and polyunsaturated fatty acids, mainly, oleate, docosapentaenoate, and docosahexaenoate. The latter two ω-3 fatty acids were particularly found in phosphatidylcholine and phosphatidylserine pools. The catalysis of Pal by stearoyl-CoA desaturase-1 (SCD-1) is a known mechanism for the channeling of Pal away from apoptosis. SCD-1 protein was upregulated during UDCA-LPE lipoprotection. SCD-1 knockdown of Pal-treated cells showed further increased apoptosis, and the extent of UDCA-LPE protection was reduced. Thus, the major mechanism of UDCA-LPE lipoprotection involved a metabolic shift from toxic saturated toward cytoprotective unsaturated fatty acids in part via SCD-1. UDCA-LPE may thus be a therapeutic agent for treatment of NASH by altering distinct pools of fatty acids for storage into TGs and PLs, and the latter may protect lipotoxicity at the membrane levels.

Diabetes and nonalcoholic Fatty liver disease: a pathogenic duo

Recent data increasingly support a complex interplay between the metabolic condition diabetes mellitus and the pathologically defined nonalcoholic fatty liver disease (NAFLD). NAFLD predicts the development of type 2 diabetes and vice versa, and each condition may serve as a progression factor for the other. Although the association of diabetes and NAFLD is likely to be partly the result of a "common soil," it is also probable that diabetes interacts with NAFLD through specific pathogenic mechanisms. In particular, through interrelated metabolic pathways currently only partly understood, diabetes appears to accelerate the progression of NAFLD to nonalcoholic steatohepatitis, defined by the presence of necroinflammation, with varying degrees of liver fibrosis. In the research setting, obstacles that have made the identification of clinically significant NAFLD, and particularly nonalcoholic steatohepatitis, difficult are being addressed with the use of new imaging techniques combined with risk algorithms derived from peripheral blood profiling. These techniques are likely to be used in the diabetes population in the near future. This review examines the pathogenic links between NAFLD and diabetes by exploring the epidemiological evidence in humans and also through newer animal models. Emerging technology to help screen noninvasively for differing pathological forms of NAFLD and the potential role of preventive and therapeutic approaches for NAFLD in the setting of diabetes are also examined.

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

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

Features, diagnosis, and treatment of nonalcoholic fatty liver disease

As the global incidence of obesity has increased, nonalcoholic fatty liver disease (NAFLD) has become a worldwide health concern. NAFLD occurs in children and adults of all ethnicities and includes isolated fatty liver and nonalcoholic steatohepatitis (NASH). Patients with NASH are at risk for developing cirrhosis, hepatic decompensation, and hepatocellular carcinoma and have increased all-cause mortality. NAFLD is associated with a variety of clinical conditions and is an independent risk factor for hepatocellular carcinoma. The pathogenesis of NAFLD and the specific steps that lead to NASH and advanced fibrosis are not fully understood, although researchers have found that a combination of environmental, genetic, and metabolic factors lead to advanced disease. There have been improvements in noninvasive radiographic methods to diagnose NAFLD, especially for advanced disease. However, liver biopsy is still the standard method of diagnosis for NASH. There are many challenges to treating patients with NASH, and no therapies have been approved by the U.S. Food and Drug Administration; multimodal approaches are being developed and becoming the standard of care. We review pathogenesis and treatment approaches for the West's largest liver-related public health concern.

Adropin deficiency is associated with increased adiposity and insulin resistance

Adropin is a secreted peptide that improves hepatic steatosis and glucose homeostasis when administered to diet-induced obese mice. It is not clear if adropin is a peptide hormone regulated by signals of metabolic state. Moreover, the significance of a decline in adropin expression with obesity with respect to metabolic disease is also not clear. We investigated the regulation of serum adropin by metabolic status and diet. Serum adropin levels were high in chow-fed conditions and were suppressed by fasting and diet-induced obesity (DIO). High adropin levels were observed in mice fed a high-fat low carbohydrate diet, whereas lower levels were observed in mice fed a low-fat high carbohydrate diet. To investigate the role of adropin deficiency in metabolic homeostasis, we generated adropin knockout mice (AdrKO) on the C57BL/6J background. AdrKO displayed a 50%-increase in increase in adiposity, although food intake and energy expenditure were normal. AdrKO also exhibited dyslipidemia and impaired suppression of endogenous glucose production (EndoR(a)) in hyperinsulinemic-euglycemic clamp conditions, suggesting insulin resistance. While homo- and heterozygous carriers of the null adropin allele exhibited normal DIO relative to controls, impaired glucose tolerance associated with weight gain was more severe in both groups. In summary, adropin is a peptide hormone regulated by fasting and feeding. In fed conditions, adropin levels are regulated dietary macronutrients, and increase with dietary fat content. Adropin is not required for regulating food intake, however, its functions impact on adiposity and are involved in preventing insulin resistance, dyslipidemia, and impaired glucose tolerance.

Nonalcoholic fatty liver disease/steatohepatitis: epidemiology, pathogenesis, clinical presentation and treatment

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic hepatic disorder in Western countries, with a prevalence of 20-30%. NAFLD comprises 'silent liver disease', in which simple steatosis is the only histological finding and which is benign in course, and nonalcoholic steatohepatitis, which is characterized by hepatocellular injury and inflammation with or without fibrosis. NAFLD is clinically important, because even benign fatty liver can progress to steatohepatitis in many patients, which can lead to liver cirrhosis and its complications and hepatocellular carcinoma. NAFLD is a hepatic manifestation of metabolic syndrome; it is closely related to other clinical features of metabolic syndrome, and thus to cardiovascular morbidity. There are several different noninvasive techniques for formal diagnosis and follow-up, but liver biopsy remains the gold standard. The most important therapeutic strategies include lifestyle changes, including changes in dietary habits aimed at weight loss and blood pressure regulation, with a consequent decrease in insulin resistance. For some patients with NAFLD/nonalcoholic steatohepatitis, pharmacological treatment is the best option, although further studies are needed to confirm its efficacy and tolerability.

Non-alcoholic Fatty liver disease: the bile Acid-activated farnesoid x receptor as an emerging treatment target

Non-alcoholic fatty liver disease (NAFLD) is currently evolving as the most common liver disease worldwide. It may progress to liver cirrhosis and liver cancer and is poised to represent the most common indication for liver transplantation in the near future. The pathogenesis of NAFLD is multifactorial and not fully understood, but it represents an insulin resistance state characterized by a cluster of cardiovascular risk factors including obesity, dyslipidemia, hyperglycemia, and hypertension. Importantly, NAFLD also has evolved as independent risk factor for cardiovascular disease. Unfortunately thus far no established treatment does exist for NAFLD. The bile acid-activated nuclear farnesoid X receptor (FXR) has been shown to play a role not only in bile acid but also in lipid and glucose homeostasis. Specific targeting of FXR may be an elegant and very effective way to readjust dysregulated nuclear receptor-mediated metabolic pathways. This review discusses the body's complex response to the activation of FXR with its beneficial actions but also potential undesirable side effects.

Metabolic syndrome and hepatic resection: improving outcome

OBJECTIVE

A review of the peri-operative risk associated with hepatic resection in patients with metabolic syndrome (MetS) and identification of measures for the improvement of cardiometabolic disturbances and liver-related mortality.

BACKGROUND

MetS and its hepatic manifestation non-alcoholic fatty liver disease (NAFLD) are associated with an increased operative mortality in spite of a significant improvement in peri-operative outcome after hepatic resection.

METHODS

A review of the English literature on MetS, liver resection and steatosis was performed from 1980 to 2011 using the MEDLINE and PubMed databases.

RESULTS

MetS is a predictor of NAFLD and patients with multiple metabolic risk factors may harbour non-alcoholic steatohepatitis (NASH) predictive of operative and cardiovascular mortality. Pre-operative diagnosis of unsuspected NASH with the selective use of a liver biopsy can modify the operative strategy by limiting the extent of hepatic resection, avoiding or altering the pre-operative chemotherapy regimen and the utilization of portal vein embolization. Thiazolidinediones are therapeutic for MetS and NASH and Vitamin E for active NASH; however, their utility in improving the peri-operative outcome after hepatic resection is unknown. A short-term regimen for weight loss improves post-operative patient and liver-related outcomes in patients with >30% steatosis. Cardiovascular disease associated with MetS or NAFLD should be managed aggressively. Peri-operative measures to minimize thrombotic events and acute renal injury secondary to the pro-inflammatory, prothrombotic state of MetS may further improve the outcome.

CONCLUSION

Potential candidates for hepatic resection should be screened for MetS as the pre-operative identification of NASH, short-term treatment of significant steatosis, cardiovascular risk assessment and optimization of each component of MetS may improve the peri-operative outcome in this high-risk subset of patients.

Galantamine alleviates inflammation and other obesity-associated complications in high-fat diet-fed mice

Obesity, a serious and growing health threat, is associated with low-grade inflammation that plays a role in mediating its adverse consequences. Previously, we have discovered a role for neural cholinergic signaling in controlling inflammation, and demonstrated that the cholinergic agent galantamine suppresses excessive proinflammatory cytokine release. The main objective of this study was to examine the efficacy of galantamine, a clinically-approved drug, in alleviating obesity-related inflammation and associated complications. After 8 wks on a high-fat diet, C57BL/6J mice were treated with either galantamine (4 mg/kg, intraperitoneally [i.p.]) or saline for 4 wks in parallel with mice on a low-fat diet and treated with saline. Galantamine treatment of obese mice significantly reduced body weight, food intake, abdominal adiposity, plasma cytokine and adipokine levels, and significantly improved blood glucose, insulin resistance and hepatic steatosis. In addition, galantamine alleviated impaired insulin sensitivity and glucose intolerance significantly. These results indicate a previously unrecognized potential of galantamine in alleviating obesity, inflammation and other obesity-related complications in mice. These findings are of interest for studying the efficacy of this clinically-approved drug in the context of human obesity and metabolic syndrome.

Expert opinion on current therapies for nonalcoholic fatty liver disease

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) is rapidly becoming one of most common liver diseases in industrialized countries owing to the increasing prevalence of obesity and being overweight. Until now, loss of weight and physical activity have represented the cornerstone of treatment, but they are very difficult to achieve and to maintain. Therefore, new treatments based on pathogenetic mechanisms leading to NAFLD are under evaluation to establish an effective pharmacological therapy for this disorder.

AREAS COVERED

An overview of current therapeutic interventions to treat NAFLD is given. This review provides evidence of the efficacy of natural and pharmacological agents used so far in the treatment of both adult and pediatric NAFLD, on the basis of clinical trials published in the last 10 years.

EXPERT OPINION

In the last 10 years, many pharmacological agents on the basis of the pathogenetic mechanism of NAFLD have been attempted, but so far guidelines for the management of NAFLD are lacking. We believe that the advance in the understanding of pathogenesis and factors involved in the progression of the disease may disclose the way to defining new, solid, therapeutic strategies. A multidisciplinary approach considering the risk factors and comorbidities of fatty liver will represent in the future a successful therapeutic strategy for NAFLD.