磷脂酰胆碱对酒精性肝病保护作用的研究进展

酒精性肝病已逐渐成为第二大肝脏疾病,威胁着人类的健康。乙醇引发肝损伤的机制主要包括其代谢产物乙醛对肝细胞造成的毒性作用、自由基损伤及对肝脏线粒体产生的毒性作用等。已证实,磷脂酰胆碱对酒精肝损伤具有明显的保护作用。简要介绍了酒精肝病机制及磷脂酰胆碱对酒精性肝损伤的保护作用研究进展,以期为治疗酒精性肝病提供帮助。     

肝细胞程序性坏死与非酒精性脂肪性肝病

非酒精性脂肪性肝病是目前世界上最常见的慢性肝病,其发病机制尚不清楚。肝细胞死亡与该病的相关性已被广泛报道。程序性坏死是一种细胞死亡形式。研究发现,肝细胞程序性坏死在非酒精性脂肪性肝病的发展过程中发挥重要作用。本文就近年来肝细胞程序性坏死在非酒精性脂肪性肝病中的研究进展作一综述,旨在为非酒精性脂肪性肝病的发病机制与药物治疗提供新思路。     

肠道菌群在慢性肝脏疾病中作用的研究进展

随着肠-肝轴机制研究的不断深入,肠道菌群与多种慢性肝脏疾病如非酒精性脂肪性肝病、酒精性肝病、肝硬化等相关性研究日益增多。肠道菌群通过肠道菌群失调、物质能量代谢改变及免疫反应激活等机制在多种肝脏疾病发生发展中发挥重要作用。本文对肠道菌群与慢性肝脏疾病关系的研究进展进行综述。     

非酒精性脂肪性肝病与肠粘膜屏障关系的研究进展

近年来,非酒精性脂肪性肝病的发病率正呈逐年升高趋势,且可进一步发展为非酒精性肝炎、肝硬化甚至肝癌,但其具体的发病机制目前尚未完全阐明。迄今为止,关于非酒精性脂肪性肝病较为人们所接受的是"两次打击学说",即肝脏的脂肪变性及脂质的过氧化反应。自"肠-肝轴"被提出后,关于肠道粘膜屏障功能与非酒精性脂肪性肝病的发生和发展的关系备受研究人员的关注。近些年来,关于非酒精性脂肪性肝病与肠道粘膜的机械屏障、生物屏障、化学屏障、免疫屏障方面的研究越来越多,肠粘膜的四个屏障功能与非酒精性脂肪性肝病密切相关,相互影响共同促进疾病的发生发展。本文就非酒精性脂肪性肝病与肠粘膜屏障关系的研究进展进行了综述。     

血管新生在肝脏疾病发生与发展中作用的研究进展

血管新生是在现有血管的基础上,通过多种细胞因子的调控进而形成新的毛细血管的过程。近年来研究发现,血管新生不仅在组织修复过程中发挥其重要作用,而且在肝脏疾病的发生发展中扮演着重要的角色。本文就血管新生的概念以及其在各类肝脏疾病,如:酒精性肝病、非酒精性脂肪肝炎、病毒性肝炎、肝纤维化、肝细胞癌中的作用机制及研究进展作一综述,旨在为肝病的预防及治疗提供新的思路,并且为药物的开发提供一定的理论支持。     

PPARs在非酒精性脂肪性肝病发病机制中的作用

非酒精性脂肪性肝病(non-alcoholic fatty liver disease,NAFLD)是西方国家最常见的慢性肝脏疾病,其疾病谱包括肝脂肪变性,脂肪性肝炎,进一步的肝纤维化、肝硬化,甚至肝细胞性肝癌。其发病机制尚未明确,通常解释为"二次打击"学说。然而新的研究发现非甘油三酯在肝脏的沉积,而是脂肪酸(fatty acids,FAs)及其代谢产物等可能对肝脏有毒性作用。过氧化物酶体增殖物激活受体(PPARs)是配体激活的转录因子,是核受体超家族成员之一,具有调节脂质及糖代谢、抗炎和抗纤维化作用,尤其在FAs储存及分解代谢中起到核心作用,与NAFLD的发生发展密切相关,可能作为治疗NAFLD有效靶点。本文将对PPARs在NAFLD发病机制中的作用做一综述。     

酒精性肝病合并HBV感染并发肝衰竭对NF-κB信号通路的影响

由于酗酒人数的增长,HBV感染合并酒精性肝病患者的数量在中国逐年增加,酒精性肝病与HBV感染会严重影响肝功能。目前中国已成为引起肝硬化的第二大病因。而乙型肝炎病毒感染合并酒精性肝病是最常见的,且会对肝脏造成严重的损伤。本实验的检测了NF-κB信号通路和IL-8、TNF-α和Cleaved caspase-3基因及蛋白的表达,结果表明,酒精性肝病合并HBV感染并发肝衰竭会激活NF-κB信号通路,并上调IL-8、TNF-α和Cleaved caspase-3基因和蛋白的表达,说明酒精性肝病合并HBV感染不仅对肝脏造成了极其严重的损伤,还造成肝脏组织或细胞炎症的发生和细胞凋亡及组织纤维化。通过以上的研究,本实验为揭示酒精性肝病合并HBV并发肝衰竭的分子机制,以及为后续研究酒精性肝病合并HBV并发肝衰竭的靶向治疗提供理论参考。     

肠道菌群与肝脏疾病相关性

肠道菌群是一个复杂的微生态系统,其种类、数量、比例、定位等要素的平衡对宿主健康产生重大影响,尤其与消化系统关系紧密。肝脏是身体内以代谢功能为主的器官,大量研究显示,肠道菌群可对酒精性肝病、非酒精性肝病、肝性脑病、肝硬化、肝癌以及自身自身免疫性肝炎等肝病的发生发展产生重要影响。本文从肠道菌群与肝脏疾病的相关性,肠道菌群影响肝脏疾病的可能机制等方面进行综述,为以肠道菌群为靶点的肝病临床治疗研究提供借鉴。     

非酒精性脂肪性肝病的研究进展

非酒精性脂肪性肝病(NAFLD)在西方国家较为常见,近年来在我国的发病呈上升趋势,且发展逐渐低龄化。非酒精性脂肪性肝病患者可能因持续性肝损伤而导致纤维化进展,可与慢性病毒性肝炎和酒精性肝病一样发展到终末期肝硬化,并出现肝硬化严重并发症,也有可能发展成肝癌,最终需要肝移植治疗。它严重危害人类的健康,影响人类的生活及生存质量。多因素的发病机制使其愈来愈被人们所重视,研究和了解非酒精性脂肪性肝病的流行病学、发病机制、诊断及治疗方法,对人类非常重要,如果在疾病的早期,也就是单纯性脂肪肝阶段就对疾病进行干预,这样可以取得很好的治疗效果,NAFLD是人类在本世纪需要面对的疾病之一,因此研究它的发病机制及治疗方法是非常必要的。     

肠道菌群影响非酒精性脂肪性肝病的机制及应对策略

非酒精性脂肪性肝病(nonalcoholic fatty liver disease,NAFLD)的发病率逐年升高,已成为最常见的肝脏疾病之一。目前其发病机制未被完全阐明,尚无有效治疗药物。肠道菌群与人体共生,作为人体的“第二基因组”,其在消化、吸收及代谢中发挥重要作用。新近研究表明,肠道菌群已成为影响NAFLD发生、进展的重要因素,肠道菌群失调和肠肝轴紊乱与非酒精性单纯性脂肪肝(nonalcoholic fatty liver,NAFL)发展为非酒精性脂肪性肝炎(nonalcoholic steatohepatitis,NASH)、肝纤维化和肝细胞癌(hepatocellular carcinoma,HCC)密切相关。因此,肠道微生态干预有望成为预防或治疗NAFLD的新手段。本综述主要探讨肠道菌群异常对NAFLD/NASH发病过程、机制的影响及干预措施。     

Changing pattern of alcoholic liver disease in Great Britain: relation to sex and signs of autoimmunity.

A survey of 293 patients with alcoholic liver disease showed that women, particularly those aged under 45, had a significantly higher incidence of alcoholic hepatitis, with or without superimposed cirrhosis, than men. The long-term prognosis for both women who continued to drink and those who stopped drinking was worse than that for men. Autoantibodies were more common in women, which suggested that immune mechanisms may play a part in the pathogenesis and progression of alcoholic liver disease in women.     

Innate immunity in alcoholic liver disease

Excessive alcohol consumption is a leading cause of chronic liver disease in the Western world. Alcohol-induced hepatotoxicity and oxidative stress are important mechanisms contributing to the pathogenesis of alcoholic liver disease. However, emerging evidence suggests that activation of innate immunity involving TLR4 and complement also plays an important role in initiating alcoholic steatohepatitis and fibrosis, but the role of adaptive immunity in the pathogenesis of alcoholic liver disease remains obscure. Activation of a TLR4-mediated MyD88-independent (TRIF/IRF-3) signaling pathway in Kupffer cells contributes to alcoholic steatohepatitis, whereas activation of TLR4 signaling in hepatic stellate cells promotes liver fibrosis. Alcohol consumption activates the complement system in the liver by yet unidentified mechanisms, leading to alcoholic steatohepatitis. In contrast to activation of TLR4 and complement, alcohol consumption can inhibit natural killer cells, another important innate immunity component, contributing to alcohol-mediated acceleration of viral infection and liver fibrosis in patients with chronic viral hepatitis. Understanding of the role of innate immunity in the pathogenesis of alcoholic liver disease may help us identify novel therapeutic targets to treat this disease.     

Lipid peroxidation contributes to immune reactions associated with alcoholic liver disease.

Increasing evidence indicates the involvement of immune reactions in the pathogenesis of alcoholic liver disease. We have investigated whether ethanol-induced oxidative stress might contribute to immune response in alcoholics. Antibodies against human serum albumin modified by reaction with malondialdehyde (MDA), 4-hydroxynonenal (HNE), 2-hexenal, acrolein, methylglyoxal, and oxidized arachidonic and linoleic acids were measured by ELISA in 78 patients with alcoholic cirrhosis and/or hepatitis, 50 patients with nonalcoholic cirrhosis, 23 heavy drinkers with fatty liver, and 80 controls. Titers of IgG-recognizing epitopes derived from MDA, HNE, and oxidized fatty acids were significantly higher in alcoholic as compared to nonalcoholic cirrhotics or healthy controls. No differences were instead observed in the titers of IgG-recognizing acrolein-, 2-hexenal-, and methylglyoxal-modified albumin. Alcoholics showing high IgG titers to one adduct tended to have high titers to all the others. However, competition experiments showed that the antigens recognized were structurally unrelated. Anti-MDA and anti-HNE antibodies were significantly higher in cirrhotics with more severe disease as well as in heavy drinkers with cirrhosis or extensive fibrosis than in those with fatty liver only. We conclude that antigens derived from lipid peroxidation contribute to the development of immune responses associated with alcoholic liver disease.     

Alcoholic liver disease: Current insights into cellular mechanisms

Alcoholic liver disease (ALD) due to chronic alcohol consumption is a significant global disease burden and a leading cause of mortality. Alcohol abuse induces a myriad of aberrant changes in hepatocytes at both the cellular and molecular level. Although the disease spectrum of ALD is widely recognized, the precise triggers for disease progression are still to be fully elucidated. Oxidative stress, mitochondrial dysfunction, gut dysbiosis and altered immune system response plays an important role in disease pathogenesis, triggering the activation of inflammatory pathways and apoptosis. Despite many recent clinical studies treatment options for ALD are limited, especially at the alcoholic hepatitis stage. We have therefore reviewed some of the key pathways involved in the pathogenesis of ALD and highlighted current trials for treating patients.     

Recent Advances in Alcoholic Liver Disease I. Role of intestinal permeability and endotoxemia in alcoholic liver disease

A significant body of evidence indicates that endotoxemia and endotoxin-mediated hepatocellular damage play a crucial role in the pathogenesis of alcoholic liver disease. A close correlation between endotoxemia and the severity of alcohol-induced liver injury is supported by a number of clinical and experimental studies. Elevated intestinal permeability appears to be the major factor involved in the mechanism of alcoholic endotoxemia and the pathogenesis of alcoholic liver disease. Ethanol and its metabolic derivatives, acetaldehyde in particular, alter intracellular signal-transduction pathways leading to the disruption of epithelial tight junctions and an increase in paracellular permeability to macromolecules. Studies addressing the mechanisms of such epithelial disruption and the protective factors that prevent ethanol and acetaldehyde-mediated disruption of epithelial tight junctions are critically important in the investigations toward the search of preventive and therapeutic strategies for alcoholic liver disease.     

Oxidative mechanisms in the pathogenesis of alcoholic liver disease

Although the capacity of ethanol to induce oxidative stress in the liver is well established, the mechanisms by which oxidative damage contributes to the pathogenesis of alcoholic liver disease (ALD) is still incompletely understood. Recent reports have implicated oxidative mechanisms in the onset of alcoholic steatosis and in the formation of Mallory's bodies. Moreover, by inducing mitochondrial alterations, oxidative stress promotes hepatocyte necrosis and contributes to alcohol-induced sensitization of hepatocyte to the pro-apoptotic action of TNF-alpha. Oxidative mechanisms play also a role in the progression of liver fibrosis by triggering the release of pro-fibrotic cytokines and activating collagen gene expression in hepatic stellate cells. Finally, immune responses towards antigens originating from the reactions of lipid peroxidation products with hepatic proteins might represent one of the mechanisms that contribute to perpetuate chronic hepatic inflammation in ALD. Altogether these observations give a rationale to the possible clinical application of antioxidants in the therapy of ALD.     

Free radical mechanisms in immune reactions associated with alcoholic liver disease.

Immune reactions toward the liver have been implicated in the pathogenesis of alcoholic liver disease (ALD), however the antigens involved are still poorly characterized. The contribution of free radical mechanisms to the immune reactions associated with ALD first emerged from the observation that the binding of hydroxyethyl free radicals (HER) to hepatic proteins, including cytochrome P4502E1 (CYP2E1), stimulates the production of specific antibodies in both alcohol-fed rats and alcoholic patients. We have subsequently observed that ALD patients have increased titers of antibodies directed against protein adducts with different lipid peroxidation products and antigens derived from the combination of malonildialdehyde and acetaldehyde. Free radical mechanisms can also contribute in promoting the autoimmune reactions often associated with ALD. Indeed, we have observed that antiphospholipid antibodies present in more than 50% of ALD patients recognize oxidized cardiolipin complexed with beta2-glycoprotein 1. Furthermore, a strict association between anti-HER IgG and the development of autoantibodies against CYP2E1 indicates that CYP2E1 modification by HER might promote anti-CYP2E1 autoreactivity in subjects with alcoholic cirrhosis. Altogether, these observations suggest the importance of ethanol-induced oxidative stress in stimulating immune reactions towards both liver allo-and self-antigens.     

Modification of proteins and other biological molecules by acetaldehyde: adduct structure and functional significance.

1. Chronic ethanol consumption is a major cause of liver disease. The modification of hepatic proteins by acetaldehyde (AcH), the primary metabolite of ethanol, has for some time been suggested as one of the major events initiating alcoholic liver disease. 2. These alterations in protein structure are believed to affect liver cell function, and may serve to activate the immune system. 3. This review considers the interaction between AcH and macromolecules and its functional implications.     

Intermediate filaments in hyaline material in alcoholic liver disease (Mallory bodies) and in cultured hepatoma cells.

Antibodies specific for cytoskeletal intermediate (10 nm) filaments reacted both with the hyaline deposits in alcoholic liver disease (Mallory bodies) and with perinuclear hyaline material of cultured hepatoma cells used as a model for hyaline formation in vitro. Our results suggest that disorganization and accumulation of intermediate filaments is an important step in the pathogenesis of alcoholic liver injury.