Expert opinion on current therapies for nonalcoholic fatty liver disease

GADD45β stabilized by direct interaction with HSP72 ameliorates insulin resistance and lipid accumulation

Growth arrest and DNA damage-inducible 45β (GADD45β) belongs to the GADD45 family which is small acidic proteins in response to cellular stress. GADD45β has already been reported to have excellent capabilities against cancer, innate immunity and neurological diseases. However, there is little information regard GADD45β and non-alcoholic fatty liver disease (NAFLD). In the current work, we found that the expression of GADD45β was markedly decreased in the livers of NAFLD patients via analyzing Gene Expression Omnibus (GEO) dataset and in mouse model through detecting its mRNA in high-fat-high-fructose diet (HFHFr)-fed mice. Moreover, the results from in vivo experiment demonstrated that overexpression of GADD45β by AAV8-mediated gene transfer in HFHFr-fed mouse model could reduce the level of serum and hepatic triglyceride (TG), and alleviate insulin resistance. Subsequently, by combining immunoprecipitation (IP) and mass spectrometry, we identified that HSP72 directly interacted with GADD45β to prevent GADD45β from being degraded by the proteasome pathway. Finally, the benefits of GADD45β in regulating key factors of TG synthesis and insulin signaling pathway were abolished after HSP72 knockdown. In conclusion, GADD45β stabilized by the interaction with HSP72 could alleviate the NAFLD-related pathologies, suggested it might be a potential target for the treatment of NAFLD.

Bibliometric analysis of top 100 cited articles in nonalcoholic fatty liver disease research

AIM

To identify and assess the research situation of top 100 cited articles in nonalcoholic fatty liver disease (NAFLD).

METHODS

The global scientific research articles in the Science Citation Index-Expanded relevant to NAFLD were retrieved and listed according to their citation times from the most to the least. The 100 most frequently cited original articles were selected to systematically evaluate their bibliometric parameters including times cited, publication year, journals, subject categories, and the highly related concepts of NAFLD, which reflected the history and current situation, publication distribution of leading countries and institutes as well as the research hotspots of NAFLD.

RESULTS

Top 100 cited articles in NAFLD were published from 1965 to 2015 with a citation ranging of 227 to 2151 times since publication, in which the United States was the most predominant country and Mayo Clin was the most productive institution. The majority of the top 100 cited articles were concentrated in SCI subject category of Gastroenterology and Hepatology. Hepatology and Gastroenterology is the top journal that published over half 100 top-cited articles. The significant peak of top cited articles present in the first half of the 2000s while the highest mean number of citation presents in first half of the 1980s. In addition, concepts related to pathology characteristics, epidemiology and medicalization, metabolic syndrome and its combination of symptoms including insulin resistance, biomarkers of lipid metabolism and obesity are listed as the highly related concepts.

CONCLUSION

The 100 top-cited articles marked with the leading countries, institutions, journals, hotspots and development trend in NAFLD field that could provide the foundation for further investigations.

Global publication trends and research hotspots of nonalcoholic fatty liver disease: a bibliometric analysis and systematic review

With the globally increasing prevalence, nonalcoholic fatty liver disease (NAFLD) becomes the predominant cause of chronic liver disease. A global look at the publication trends and the research hotspots of NAFLD are urgently needed to assess the situation of NAFLD research. The global scientific research in the Science Citation Index-Expanded covered articles relevant to NAFLD was retrieved and its bibliometric parameters and research hotspots of NAFLD were systematically evaluated. To sum up, 6356 articles were published in 994 different journals covering 93 SCI subject categories during 1986–2013, in which English was the most predominant language used. Starting from the late 1980s, the publication on NAFLD grew slowly and entered into a highly developing period in the 21st century, especially in the last decade. Besides hepatic steatosis, metabolic syndrome and its combination of symptoms such as obesity, insulin resistance are listed as the top frequent keywords. Bibliometric results suggest that the obviously rapid growth of the articles in recent years appears to be associated with the accelerating incidence of NAFLD and its cofactors such as metabolic syndrome. In addition, epidemiology focusing on comparing different regions and population is attracting ever-growing attention. Meantime, pathology plays an important role in NAFLD research.

Nuciferine downregulates Per-Arnt-Sim kinase expression during its alleviation of lipogenesis and inflammation on oleic acid-induced hepatic steatosis in HepG2 cells

Non-alcoholic fatty liver disease (NAFLD) is a prevalent liver disease associated with lipotoxicity, lipid peroxidation, oxidative stress, and inflammation. Nuciferine, an active ingredient extracted from the natural lotus leaf, has been reported to be effective for the prevention and treatment of NAFLD. Per-Arnt-Sim kinase (PASK) is a nutrient responsive protein kinase that regulates lipid and glucose metabolism, mitochondrial respiration, and gene expression. The aim of the present study was to investigate the protective effect of nuciferine against NAFLD and its inhibitory effect on PASK, exploring the possible underlying mechanism of nuciferine-mediated inhibition on NAFLD. Relevant biochemical parameters (lipid accumulation, extent of oxidative stress and release of inflammation cytokines) in oleic acid (OA)-induced HepG₂ cells that mimicked steatosis in vitro were measured and compared with the control. It was found that nuciferine and silenced-PASK (siRNA PASK) both inhibited triglyceride (TG) accumulation and was effective in decreasing fatty acid (FFAs). The content of total antioxidant capacity (T-AOC) and superoxide dismutase (SOD) were increased respectively by nuciferine and siRNA PASK without increase in glutathione (GSH). Malondialdehyde (MDA) was decreased respectively by nuciferine and siRNA PASK. In addition, nuciferine decreased TNF-a, IL-6 and IL-8 as well as the siRNA PASK group. IL-10 was increased by nuciferine and siRNA PASK respectively. Further investigation revealed that nuciferine and siRNA PASK could respectively regulate the expression of target genes involved in lipogenesis and inflammation, suggesting that nuciferine may be a potential therapeutic treatment for NAFLD. Furthermore, the modulated effect of nuciferine on (OA)-induced HepG₂ cells lipogenesis and inflammation, which was accompanied with PASK inhibition, was also consistent with siRNA PASK, implying that PASK might play a role in nuciferine-mediated regulation on NAFLD.

Dietary walnut oil modulates liver steatosis in the obese Zucker rat

Purpose

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of the metabolic syndrome. We aimed to clarify the impact of dietary walnut oil versus animal fat on hepatic steatosis, representing the initial step of multistage pathogenesis of NAFLD, in Zucker obese rats.

Methods

Zucker lean ad libitum (a.l.), Zucker obese a.l. or Zucker obese pair fed (p.f.) to the lean received isocaloric diets containing 8 % walnut oil (W8), W14 or 14 % lard (L14) (n = 10/group). Body weight, clinical serology, liver weight, lipid content and fatty acid composition and hepatic lipid metabolism-related transcripts were evaluated.

Results

Compared to lean, Zucker obese a.l. and p.f. showed hepatic triacylglyceride (TAG) accumulation. In Zucker obese p.f., W14 compared to W8 and L14 reduced liver lipids, TAG as well as hepatic omega-6 (n-6)/n-3 ratio and SCD activity index [(C18:0 + C18:1)/C18:0 ratio] paralleled by decreased lipoprotein lipase mRNA in obese p.f. and elevated microsomal triglyceride transfer protein mRNA in lean and obese. Further, W14 elevated the fasting blood TAG and reduced cholesterol levels in obese.

Conclusions

In our model, consumption of W14 inhibited hepatic lipid accumulation along with modulated hepatic gene expression implicated in hepatic fatty acid influx or lipoprotein assembly. These results provide first indication that dietary lipids from walnut oil are modulators of hepatic steatosis as the initial step of progressive NAFLD pathogenesis.

Non-alcoholic fatty liver disease in children now: lifestyle changes and pharmacologic treatments

Over the past decade, non-alcoholic fatty liver disease (NAFLD) has become one of most common chronic liver diseases in children. A greater understanding about the risk factors and molecular pathogenesis of NAFLD suggests that lifestyle interventions aiming to decrease obesity/body mass index and metabolic derangement are the first line of treatments adopted in children affected by this disease. However, because these therapeutic options are often at the beginning misjudged by the patients and their parents, the use of pharmacologic agents may help to protect the liver and other organs from further irreversible tissue damage. Pharmacologic therapies against one or more specific factors and/or molecules involved in the development of NAFLD (i.e., insulin resistance, free fatty acid lipid toxicity, and oxidative stress) also might slow the progression of this increasingly prevalent pediatric disorder. On this basis, insulin sensitizers, antioxidants, cytoprotective agents, and dietary supplementations have been evaluated in pediatric clinical trials. In this review, we discuss the efficacy of the dietary approaches, possibly coupled with regular exercise, on decreasing the metabolic and histologic damage in pediatric NAFLD. We also emphasize several advantages of the pharmacologic treatments adopted or adoptable in combination with lifestyle interventions in children with NAFLD.

Treatment of nonalcoholic fatty liver disease in adults and children: a closer look at the arsenal

Nonalcoholic fatty liver disease encompasses a spectrum of disease from asymptomatic steatosis, with or without elevated aminotransferases, to cirrhosis with relative complications and hepatocellular carcinoma. Owing to the increasing prevalence of nonalcoholic fatty liver disease and the potential for nonalcoholic steatohepatitis to progress to cirrhosis and liver-related mortality, more research has been focused on therapy of this important liver disease over the last two decades. To date, weight loss and physical activity represent the cornerstone of treatment, with interventions being limited to subjects at risk of disease progression, but the type of treatment remains a matter of debate. A few medications have shown promising results in preliminary pilot studies, but few agents have been tested rigorously. Today, multiple therapeutic approaches are considered the way to go in treating nonalcoholic steatohepatitis patients. In this paper we review the status of current and emerging therapeutic strategies for children and adult patients with nonalcoholic steatohepatitis.