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。     

Liver mitochondrial function and redox status in an experimental model of non-alcoholic fatty liver disease induced by monosodium L-glutamate in rats

The purpose of this work was to determine if mitochondrial dysfunction is involved in the development of non-alcoholic fatty liver disease (NAFLD). Using a model of obesity induced by the neonatal treatment of rats with monosodium l-glutamate (MSG), several parameters of liver mitochondrial function and their impact on liver redox status were evaluated. Specifically, fatty acid β-oxidation, oxidative phosphorylation and Ca²⁺-induced mitochondrial permeability transition were assessed in isolated liver mitochondria, and reduced glutathione (GSH), linked thiol contents and the activities of several enzymes involved in the control of redox status were measured in the liver homogenate. Our results demonstrate that liver mitochondria from MSG-obese rats exhibit a higher β-oxidation capacity and an increased capacity for oxidising succinate, without loss in the efficiency of oxidative phosphorylation. Also, liver mitochondria from obese rats were less susceptible to the permeability transition pore (PTP) opening induced by 1.0 μM CaCl₂. Cellular levels of GSH were unaffected in the livers from the MSG-obese rats, whereas reduced linked thiol contents were increased. The activities of glucose-6-phosphate dehydrogenase, glutathione reductase and glutathione peroxidase were increased, while catalase activity was unaffected and superoxide dismutase activity was reduced in the livers from the MSG-obese rats. In this model of obesity, liver fat accumulation is not a consequence of mitochondrial dysfunction. The enhanced glucose-6-phosphate dehydrogenase activity observed in the livers of MSG-obese rats could be associated with liver fat accumulation and likely plays a central role in the mitochondrial defence against oxidative stress.     

脂联素与非酒精性脂肪肝肝纤维化及胰岛素抵抗的关系

目的：研究脂联素水平与非酒精性脂肪肝（NAFLD）患者肝纤维化指标及胰岛素抵抗指数（IRI）的关系。方法：采用ELISA法检测NAFLD患者和正常对照组的脂联素水平及Ⅲ型前胶原（PCⅢ）、透明质酸（HA）、Ⅳ型胶原（CⅣ）、层黏蛋白（LN）水平,采用稳态模式胰岛素抵抗指数（HOMA IRI）评估胰岛素抵抗。结果：NAFLD组脂联素水平显著低于对照组,胰岛素抵抗指数与肝纤维化指标显著高于对照组（P〈0.05）,IRI与PCⅢ、PCⅣ、HA和LN呈显著正相关（P〈0.05）,脂联素水平与WHR、BMI、FBG、Tg、FINS、HOMA-IRI、PCⅢ、PCⅣ、HA和LN呈显著负相关（P〈0.01或〈0.05）。结论：NAFLD患者血清脂联素水平降低,脂联素的表达在NAFLD患者肝纤维化与胰岛素抵抗进程中可能起重要作用。     

非酒精性脂肪性肝病发病机制的研究进展

非酒精性脂肪性肝病（NAFLD）是指与过量饮酒无关的临床综合征,主要病理改变包括肝细胞弥漫性脂肪变性和脂肪堆积。NAFLD动物模型表现出显著的肝脏微循环障碍,关于其形成机制,被广为接受的为＂二次打击＂学说。该学说认为肥胖、胰岛素抵抗等因素作为＂第一次打击＂,导致肝脏中脂质堆积,形成单纯性脂肪肝,增加了＂第二次打击＂造成的肝脏损伤的易感性,这些因素包括炎症、枯否细胞功能障碍、氧化应激、线粒体障碍、脂肪因子调节紊乱等,导致非酒精性脂肪性肝炎甚至纤维化等更严重疾病的发生。     

Molecular evolution of adiponectin in Carnivora and its mRNA expression in relation to hepatic lipidosis

Adiponectin is a novel adipocyte-derived hormone with low circulating concentrations and/or mRNA expression in obesity and non-alcoholic fatty liver disease (NAFLD). The adiponectin mRNA of several Carnivora species was sequenced to enable further gene expression studies in this clade with potential experimental species to examine the connections of hypoadiponectinemia to hepatic lipidosis. In addition, adiponectin mRNA expression was studied in the retroperitoneal fat of the American mink (Neovison vison), as hepatic lipidosis with close similarities to NAFLD can be rapidly induced to the species by fasting. The mRNA expression was determined after overnight-7 d of food deprivation and 28 d of re-feeding and correlated to the liver fat %. The homologies between the determined carnivoran mRNA sequences and that of the domestic dog were 92.2-99.1%. As the mRNA expression was not affected by short-term fasting and did not correlate with the liver fat %, there seems to be no clear connection between adiponectin and the development of lipidosis in the American mink. In the future, the obtained sequences can be utilized in further studies of adiponectin expression in comparative endocrinology.     

Protective effect of bicyclol on tetracycline-induced fatty liver in mice

Peroxisome proliferators-activated receptor α (PPARα) and oxidative stress are two important pathological factors in non-alcoholic fatty liver disease (NAFLD). Tetracycline-induced fatty liver was partly due to the disturbance of mitochondrial fatty acids β-oxidation regulated by PPARα. Bicyclol was found to protect against high fat diet-induced fatty liver through modulating PPARα and clearing reactive oxygen species (ROS). The present study was performed to further investigate the effect of bicyclol on tetracycline-induced fatty liver and related mechanism in mice. Bicyclol (75, 150, 300 mg/kg) was given orally three times in two consecutive days. Tetracycline (200 mg/kg) was injected intraperitoneally 1 h after the last administration of bicyclol. Oxidative stress, mitochondrial function, PPARα and its target genes were evaluated by biochemical and RT-PCR analysis. The activity of CYP4A was assessed by liquid chromatography/mass spectrometry (LC/MS) method. Bicyclol significantly protected against tetracycline-induced fatty liver by reducing the accumulation of hepatic lipids and elevation of serum aminotransferase. In addition, bicyclol remarkably alleviated the over-production of thiobarbituric acid-reactive substance. The reduced activity of mitochondrial respiratory chain (MRC) complexes I and IV and mitochondrial permeability transition (MPT) were also improved by bicyclol. Furthermore, bicyclol inhibited the decrease of PPARα expression and its target genes, including long-chain acyl CoA dehydrogenase (LCAD), acetyl CoA oxidase (AOX) and CYP4A at mRNA and enzyme activity level. Bicyclol protected against tetracycline-induced fatty liver mainly through modulating the disturbance of PPARα pathway and ameliorating mitochondrial function.     

Trajectories of glycaemic traits exhibit sex-specific associations with hepatic iron and fat content: Results from the KORA-MRI study

Background

Non-alcoholic fatty liver disease (NAFLD) represents a major disease burden in the population. While the bidirectional association between NAFLD and diabetes is established, little is known about the association of hepatic iron content and glycaemia. Moreover, analyses of sex-specific effects and of dynamic changes in glycaemia are scarce.

Methods

We investigated 7-year sex-specific trajectories of glycaemia and related traits (HbA1c, fasting glucose, fasting insulin, HOMA-IR, 2-h glucose and cross-sectional 2-h insulin) in a sample from a population-based cohort (N = 365; 41.1% female). Hepatic iron and fat content were assessed by 3T-Magnetic Resonance Imaging (MRI). Two-step multi-level models adjusted for glucose-lowering medication and confounders were applied.

Results

In women and men, markers of glucose metabolism correlated with hepatic iron and fat content. Deterioration of glycaemia was associated with increased hepatic iron content in men (normoglycaemia to prediabetes: beta = 2.21 s⁻¹, 95% CI [0.47, 3.95]). Additionally, deterioration of glycaemia (e.g. prediabetes to diabetes: 1.27 log(%), [0.84, 1.70]) and trajectories of glucose, insulin and HOMA-IR were significantly associated with hepatic fat content in men. Similarly, deterioration of glycaemia as well as trajectories of glucose, insulin and HOMA-IR was significantly associated with increased hepatic fat content in women (e.g. trajectory of fasting insulin: 0.63 log(%), [0.36, 0.90]).

Conclusions

Unfavourable 7-year trajectories of markers of glucose metabolism are associated with increased hepatic fat content, particularly in women, whereas the association with hepatic iron content was less clear. Monitoring changes of glycaemia in the sub-diabetic range might enable early identification of hepatic iron overload and steatosis.     

PNPLA3 I148M and response to treatment for hepatic steatosis: A systematic review

Background

It is unclear whether the patatin-like phospholipase domain-containing protein 3 (PNPLA3) rs738409 C-to-G single nucleotide polymorphism, resulting in the substitution of isoleucine to methionine at position 148 (I148M), impedes regression of hepatic steatosis when treating non-alcoholic fatty liver disease (NAFLD).

Objectives

Investigate if carriage of the PNPLA3 148M allele affects the anti-steatotic efficacy of all possible anti-NAFLD interventions, identify gaps in current knowledge and provide guidance for individual treatment.

Methods

Research available in public databases was searched up to 13 November 2022. Studies were included if a treatment in NAFLD patients decreased hepatic steatosis in the pooled patient group or a PNPLA3 I148M polymorphism subgroup (II/IM/MM). The risk of bias was assessed using the Cochrane Risk-Of-Bias 2 Tool and the Newcastle–Ottawa Scale.

Results

Moderate evidence indicates that NAFLD patients homozygous for the PNPLA3 148M allele benefit less or not at all from omega-3 carboxylic acids to decrease liver fat, while the PNPLA3 148I allele shows moderate benefit. Low evidence suggests that interventions employing lifestyle changes are more effective to reduce liver fat in NAFLD patients homozygous for the PNPLA3 148M allele compared to patients with wild-type PNPLA3.

Conclusions

NAFLD patients homozygous for the PNPLA3 148M allele might not benefit from omega-3 carboxylic acids to reduce hepatic steatosis in contrast to patients with wild-type PNPLA3. Instead, patients with two PNPLA3 148M alleles should be especially advised to adopt lifestyle changes. Genotyping for PNPLA3 I148M should be encouraged in therapeutic studies for NAFLD.

Registration Number (Prospero)

CRD42022375028.     

The relationship between the contents of 13 amino acids in brain tissues and the progression of NAFLD via C57BL/6 model mice

Non-alcoholic fatty liver disease (NAFLD) is the steatosis of liver parenchyma unrelated to alcoholism, autoimmunity, and viral infection. It is also a metabolism-related syndrome, which has an unseparated relationship with adipose tissue dysfunction and obesity. Hepatic encephalopathy (HE) is one of the severe complications of chronic liver disease and one of the end-stage syndromes of liver disease. Some researchers have suggested that NAFLD, like other forms of liver injury, may be related to the metabolic disorder of branched-chain amino acids (BCAAs), which have been approved to be associated with HE influencing ammonia and energy metabolism. However, several studies have revealed the relationship among amino acids in serum, HE, and chronic liver disease; there are few studies on the contents of amino acids in brain tissues of an animal model with NAFLD. In the present research, we established a NAFLD mouse model with C57BL/6 mice and determined the contents of 13 amino acids in brain tissues of model mice by HPLC-FLD derivatization method using ortho-phthalaldehyde (OPA) to explore the relationship between the contents of amino acids in brain tissues and the progression of NAFLD. Moreover, the study showed that the changes of amino acid contents in the brain of the C57BL/6 mice were associated with the advancement of NAFLD, and this change might be related to the mechanism of HE.