The role of the circadian clock in the development,progression, and treatment of non-alcoholic fatty liver disease

The circadian clock comprises a cellular endogenous timing system coordinating the alignment of physiological processes with geophysical time. Disruption of circadian rhythms has been associated with several metabolic diseases. In this review, we focus on liver as a major metabolic tissue and one of the most well-studied organs with regard to circadian regulation. We summarize current knowledge about the role of local and systemic clocks and rhythms in regulating biological functions of the liver. We discuss how the disruption of circadian rhythms influences the development of non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH). We also critically evaluate whether NAFLD/NASH may in turn result in chronodisruption. The last chapter focuses on potential roles of the clock system in prevention and treatment of NAFLD/NASH and the interaction of current NASH drug candidates with liver circadian rhythms and clocks. It becomes increasingly clear that paying attention to circadian timing may open new avenues for the optimization of NAFLD/NASH therapies and provide interesting targets for prevention and treatment of these increasingly prevalent disorders.     

左归降糖清脂方对2型糖尿病转基因MKR 鼠脂肪肝发生的影响

目的:探讨左归降糖清脂方对2型糖尿病转基因MKR鼠脂肪肝发生的影响。方法:30只MKR鼠随机分为MKR组、MKR高脂组和左归降糖清脂方组;左归降糖清脂方组以生药29.64 g.kg-1 ig干预治疗高脂饮食诱发脂肪肝的MKR鼠,观察其肝脏病理形态、血糖、血胰岛素、肝功能和血脂变化。结果:高脂饲料诱发MKR鼠形成非酒精性脂肪肝,肝细胞有大小不一的脂滴,呈脂肪性变;MKR高脂组小鼠空腹血糖、血胰岛素、肝质量、肝指数、肝功能指标[谷丙转氨酶(ALT),谷草转氨酶(AST)]、血清总胆固醇(TCHO)、高密度脂蛋白胆固醇(HDL-C)和低密度脂蛋白胆固醇(LDL-C)高于MKR组(P<0.05,P<0.01),甘油三酯(TG)下降,低于MKR组(P<0.01)。2型糖尿病并发脂肪肝MKR鼠经左归降糖清脂方治疗后,肝细胞内脂肪性变得到改善,空腹血糖、血胰岛素、肝质量、肝指数、肝功能指标(ALT,AST)和血脂(TCHO,LDL-C和TG)显著下降,低于MKR小鼠(P<0.05,P<0.01);HDL-C高于MKR小鼠(P<0.05)。结论:左归降糖清脂方可通过调节高脂饮食MKR鼠体内的糖脂代谢,改善肝脏脂肪性变。     

Src/NF-κB-targeted inhibition of LPS-induced macrophage activation and dextran sodium sulphate-induced colitis by Archidendron clypearia methanol extract

Ethnopharmacological relevance

Raw and processed Polygoni Multiflori Radix (PMR) are used in the prevention and treatment of non-alcoholic fatty liver disease (NAFLD), hyperlipidemia or related diseases. However, few researches compared the activities of raw and processed PMR on lipid metabolism regulation. Moreover, the active substances of Polygonum multiflorum are still not clearly elucidated.

Materials and methods

In this research, a sensitive, accurate and rapid in vitro model, steatosis hepatic L02 cell, was applied to compare the relative activities of raw and processed PMR on lipid metabolism regulation. Furthermore, the lipid regulation activities of emodin, physcion and 2,3,5,4′-tetrahydroxy-stilbene-2-O-β-d-glucoside (TSG) were evaluated. The steatosis L02 cells were obtained after cultured with 1% fat emulsion-10% fetal bovine serum (FBS)-RPMI 1640 medium for 48 h. Contents of total cholesterol (TC), triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C) in L02 cells are evaluated after exposure.

Results

The intracellular TG contents were increased from 16.50 ± 1.29 mmol/L to 34.40 ± 1.36 mmol/L in steatosis L02 cells, while the intracellular contents of TC were increased from 5.07 ± 1.80 mmol/L to 11.79 ± 0.54 mmol/L. Water extract of raw PMR showed much remarkable TG-regulation and TC-regulation effects than its processed products. Emodin displayed the best TG regulation activity while TSG showed the best TC regulation activity. At the same time, the exposure of emodin and physcion could reduce the LDL-C contents in steatosis L02 cells.

Conclusions

On account of these in vitro results, raw PMR might have more satisfactory effects in clinic treatment of NAFLD or hyperlipidemia characterized by the elevation of cholesterol than processed PMR.     

Krill Oil Supplementation Reduces Exacerbated Hepatic Steatosis Induced by Thermoneutral Housing in Mice with Diet-Induced Obesity

Preclinical evidence suggests that n-3 fatty acids EPA and DHA (Omega-3) supplemented as phospholipids (PLs) may be more effective than triacylglycerols (TAGs) in reducing hepatic steatosis. To further test the ability of Omega-3 PLs to alleviate liver steatosis, we used a model of exacerbated non-alcoholic fatty liver disease based on high-fat feeding at thermoneutral temperature. Male C57BL/6N mice were fed for 24 weeks a lard-based diet given either alone (LHF) or supplemented with Omega-3 (30 mg/g diet) as PLs (krill oil; ω3PL) or TAGs (Epax 3000TG concentrate; ω3TG), which had a similar total content of EPA and DHA and their ratio. Substantial levels of TAG accumulation (~250 mg/g) but relatively low inflammation/fibrosis levels were achieved in the livers of control LHF mice. Liver steatosis was reduced by >40% in the ω3PL but not ω3TG group, and plasma ALT levels were markedly reduced (by 68%) in ω3PL mice as well. Krill oil administration also improved hepatic insulin sensitivity, and its effects were associated with high plasma adiponectin levels (150% of LHF mice) along with superior bioavailability of EPA, increased content of alkaloids stachydrine and trigonelline, suppression of lipogenic gene expression, and decreased diacylglycerol levels in the liver. This study reveals that in addition to Omega-3 PLs, other constituents of krill oil, such as alkaloids, may contribute to its strong antisteatotic effects in the liver.     

Liver enzymes and vitamin D levels in metabolically healthy but obese individuals: Korean National Health and Nutrition Examination Survey

Objective

Increased liver enzymes and decreased vitamin D levels are associated with insulin resistance and type 2 diabetes. We examined liver enzymes and vitamin D levels in metabolically healthy but obese (MHO) individuals and compared the values with those of other body size phenotypes in the Korean population.

Materials/Methods

A total of 16,190 people over the age of 18 years were analyzed using data from the Fourth Korean National Health and Nutrition Examination Survey, which is a nationally representative survey. Body size phenotypes were classified into four groups by body mass index (BMI) and number of metabolic syndrome components.

Results

The prevalence of MHO was 14.9% in the entire population and 47.7% in the obese population. In a correlation analysis adjusted for age, sex, and BMI, AST and ALT levels were positively correlated with insulin resistance and cardiometabolic risk factors of the metabolic syndrome, whereas vitamin D level was negatively correlated with these variables. MHO individuals had significantly lower concentrations of AST and ALT compared to metabolically abnormal obese (MAO) subjects, although vitamin D levels were not significantly different. Furthermore, a multiple logistic regression analysis revealed that MHO individuals had lower risk of liver enzyme abnormality compared to MAO after adjusting for potential confounding factors. However, the risk of vitamin D deficiency was not significantly different among groups with different body size phenotypes.

Conclusions

Although both liver enzymes and vitamin D levels are related to insulin resistance and metabolic syndrome, only liver enzymes were independently associated with MHO phenotype.     

基于网络药理学的降脂理肝汤治疗非酒精性脂肪肝病作用机制研究

目的筛选降脂理肝汤主要活性成分,预测其活性成分的作用靶点,探讨降脂理肝汤治疗非酒精性脂肪肝病(non-alcoholic fatty liver disease,NAFLD)的多成分-多靶点-多通路作用机制。方法通过多个数据库联合检索并筛选降脂理肝汤活性成分和其作用靶点以及NAFLD相关靶点,并预测降脂理肝汤治疗NAFLD的潜在靶点。采用Cytoscape软件构建降脂理肝汤活性成分-作用靶点网络,通过Cytoscape的插件Clue GO对靶点基因功能及通路进行富集分析。结果网络分析结果表明,从降脂理肝汤中筛选得到82个活性成分,涉及NAFLD靶点53个,靶点主要关联NAFLD中胰岛素抵抗、氧化应激和炎症反应,并且参与了NAFLD中PI3K/Akt信号通路、炎症小体途径、白细胞介素-10(IL-10)信号通路以及T细胞信号通路,这些生物过程和信号通路介导了降脂理肝汤干预NAFLD潜在机制。结论为进一步深入研究降脂理肝汤治疗NAFLD作用机制提供了重要依据。     

Nonalcoholic Fatty Liver Disease and the Heart: JACC State-of-the-Art Review

Nonalcoholic fatty liver disease (NAFLD) and cardiovascular disease (CVD) are both manifestations of end-organ damage of the metabolic syndrome. Through multiple pathophysiological mechanisms, CVD and NAFLD are associated with each other. Systemic inflammation, endothelial dysfunction, hepatic insulin resistance, oxidative stress, and altered lipid metabolism are some of the mechanisms by which NAFLD increases the risk of CVD. Patients with NAFLD develop increased atherosclerosis, cardiomyopathy, and arrhythmia, which clinically result in cardiovascular morbidity and mortality. Defining the mechanisms linking these 2 diseases offers the opportunity to further develop targeted therapies. The aim of this comprehensive review is to examine the association between CVD and NAFLD and discuss the overlapping management approaches.