Immunologic Mechanisms of Alcoholic Liver Disease

酒精性肝病的免疫学机制

• 批准号: 8746472
• 负责人: bin gao
• 金额: $ 88.82万
• 依托单位: NATIONAL INSTITUTE ON ALCOHOL ABUSE AND ALCOHOLISM
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8746472
• 关键词: Acetaldehyde; Acute; Adrenal Cortex Hormones; Affect; Agreement; Alanine Transaminase; Alcohol consumption; Alcoholic Hepatitis; Alcoholic Liver Diseases; Asians; Attenuated; Autoimmune Hepatitis; Blood alcohol level measurement; Carbon Tetrachloride; Cells; Chronic; Cirrhosis; Concanavalin A; Diet; Disease Progression; Endocannabinoids; Enzymes; Ethanol; Ethanol Metabolism; Exhibits; Fatty Liver; Fibrosis; Galactosylceramides; Genes; Glucocorticoid Receptor; Goals; Hepatic; Hepatitis; Hepatocellular Damage; Human; Immunologics; In Vitro; Individual; Inflammation; Inflammatory; Inflammatory Response; Interleukin-6; Kupffer Cells; Laboratories; Liquid substance; Liver; Liver Fibrosis; Liver Regeneration; Liver diseases; Malondialdehyde; Mediating; Modeling; Mus; National Institute on Alcohol Abuse and Alcoholism; Neutrophil Infiltration; Oral; Organ; Pathogenesis; Patients; Primary carcinoma of the liver cells; Production; Reporting; Resistance; Role; Serum; Signaling Molecule; Slice; Staging; Stat3 protein; Steatohepatitis; Steroid therapy; Steroids; System; Therapeutic; Wild Type Mouse; acetaldehyde dehydrogenase; adduct; aldehyde dehydrogenases; chronic alcohol ingestion; chronic liver disease; feeding; hepatotoxin; in vivo; interleukin-22; liver inflammation; liver injury; liver repair; macrophage; mouse model; neutrophil; new therapeutic target; paracrine; prednisolone; prevent; problem drinker; regenerative

Our laboratory has been actively studying the pathogenesis of alcoholic liver disease, focusing on the role of acetaldehyde dehydrogenase 2 (ALDH2) and prednisolone in alcoholic liver injury, and we have also developed a mouse model of chronic plus binge ethanol feeding model, which represents early stages of human alcoholic steatohepatitis. Chronic alcohol consumption is a leading cause of chronic liver disease worldwide, leading to cirrhosis and hepatocellular carcinoma. Currently, the most widely used model for alcoholic liver injury is ad libitum feeding with the Lieber-DeCarli liquid diet containing ethanol for 4-6 weeks; however, this model, without the addition of a secondary insult, only induces mild steatosis, slight elevation of serum alanine transaminase (ALT) and little or no inflammation. During this reporting period, we developed a simple mouse model of alcoholic liver injury by chronic ethanol feeding (10-d ad libitum oral feeding with the Lieber-DeCarli ethanol liquid diet) plus a single binge ethanol feeding. This chronic-plus-single-binge ethanol feeding synergistically induces liver injury, inflammation and fatty liver, which mimics acute-on-chronic alcoholic liver injury in patients. Chronic-binge ethanol feeding leads to high blood alcohol levels; thus, this simple model will be very useful for the study of alcoholic liver disease (ALD) and of other organs damaged by alcohol consumption. Aldehyde dehydrogenase 2 (ALDH2) is the major enzyme that metabolizes acetaldehyde produced from alcohol metabolism. Approximately 40 to 50% of East Asians carry an inactive ALDH2 gene and exhibit acetaldehyde accumulation after alcohol consumption. However, the role of ALDH2 deficiency in the pathogenesis of alcoholic liver injury remains obscure. During this reporting period, we have used wild-type (WT) and ALDH2-/- mice to examine the roles of ALDH2 in alcoholic liver injury and fibrosis by using ethanol feeding and/or carbon tetrachloride (CCl4) treatment. Compared with WT mice, ethanol-fed ALDH2-/- mice had higher levels of malondialdehyde and acetaldehyde (MAA) adduct and greater hepatic inflammation, with higher hepatic interleukin-6 (IL-6) expression but surprisingly lower levels of steatosis and serum ALT. Higher IL-6 levels were also detected in ethanol-treated precision-cut-liver slices from ALDH2-/- mice and in Kupffer cells isolated from ethanol-fed ALDH2-/- mice than those levels in WT mice. In vitro incubation with MAA enhanced the LPS-mediated stimulation of IL-6 production in Kupffer cells. In agreement with these findings, hepatic activation of the major IL-6 downstream signaling molecule signal transducer and activator of transcription 3 (STAT3) was higher in ethanol-fed ALDH2-/- mice than in WT mice. An additional deletion of hepatic STAT3 resulted in increased steatosis and hepatocellular damage in ALDH2-/- mice. Finally, ethanol-fed ALDH2-/- mice were more prone to CCl4-induced liver inflammation and fibrosis than ethanol-fed WT mice. CONCLUSIONS: ALDH2-/- mice are resistant to ethanol-induced steatosis but prone to inflammation and fibrosis via MAA-mediated paracrine activation of IL-6 in Kupffer cells. These findings suggest that ALDH2-deficient individuals may be resistant to steatosis, but are prone to liver inflammation and fibrosis following alcohol consumption. Prednisolone is a corticosteroid that has been used to treat inflammatory liver diseases, such as autoimmune hepatitis and alcoholic hepatitis. However, the results have been controversial, and how prednisolone affects liver disease progression remains unknown. During this reporting period, we examined the effect of prednisolone treatment on several models of liver injury, including T/NKT cell hepatitis induced by concanavalin A (Con A) and -galactosylceramide (-GalCer), and hepatotoxin-mediated hepatitis induced by carbon tetrachloride (CCl4). Prednisolone administration attenuated ConA- and -GalCer-induced hepatitis and systemic inflammatory responses. Treating mice with prednisolone also suppressed inflammatory responses in a model of hepatotoxin (CCl4)-induced hepatitis, but surprisingly exacerbated liver injury and delayed liver repair. Immunohistochemical and flow cytometric analyses demonstrated that prednisolone treatment inhibited hepatic macrophage and neutrophil infiltration in CCl4-induced hepatitis and suppressed their phagocytic activities in vivo and in vitro. Macrophage and/or neutrophil depletion aggravated CCl4-induced liver injury and impeded liver regeneration. Finally, conditional disruption of glucocorticoid receptor in macrophages and neutrophils abolished prednisolone-mediated exacerbation of hepatotoxin-induced liver injury. Conclusion: Prednisolone treatment prevents T/NKT cell hepatitis but exacerbates hepatotoxin-induced liver injury by inhibiting macrophage- and neutrophil-mediated phagocytic and regenerative functions. These findings may not only increase our understanding of the steroid treatment mechanism but also help us to better manage steroid therapy in liver diseases. In addition, we are also collaborating with Drs. George Kunos and Pal Pacher from NIAAA to investigate the role of the endocannabinoid system in alcoholic liver disease.

我们实验室一直在积极研究酒精性肝病的发病机制，重点研究乙醛脱氢酶2（ALDH2）和泼尼松龙在酒精性肝损伤中的作用，并建立了代表人类酒精性脂肪性肝炎早期阶段的慢性加暴食乙醇喂养模型的小鼠模型。 长期饮酒是全世界慢性肝病的主要原因，可导致肝硬化和肝细胞癌。目前，最广泛使用的酒精性肝损伤模型是随意饲喂含乙醇的Lieber-DeCarli流质饲料4-6周；然而，该模型在不添加继发性损伤的情况下，仅诱导轻度脂肪变性、血清丙氨酸转氨酶（ALT）轻微升高并且很少或没有炎症。在本报告期内，我们通过慢性乙醇喂养（10天随意口服Lieber-DeCarli乙醇液体饮食）加单次暴饮乙醇喂养，开发了一种简单的酒精性肝损伤小鼠模型。这种长期加单次暴饮暴食的乙醇协同诱导肝损伤、炎症和脂肪肝，类似于患者慢性酒精性肝损伤。长期酗酒会导致血液中酒精浓度升高；因此，这个简单的模型对于研究酒精性肝病（ALD）和其他因饮酒而受损的器官非常有用。 乙醛脱氢酶 2 (ALDH2) 是代谢酒精代谢产生的乙醛的主要酶。大约 40% 至 50% 的东亚人携带不活跃的 ALDH2 基因，饮酒后会出现乙醛积聚。然而，ALDH2 缺乏在酒精性肝损伤发病机制中的作用仍不清楚。在本报告期内，我们使用野生型（WT）和 ALDH2-/- 小鼠，通过乙醇喂养和/或四氯化碳（CCl4）治疗来研究 ALDH2 在酒精性肝损伤和纤维化中的作用。与WT小鼠相比，乙醇喂养的ALDH2-/-小鼠具有更高水平的丙二醛和乙醛（MAA）加合物和更严重的肝脏炎症，具有更高的肝脏白细胞介素6（IL-6）表达，但令人惊讶的是脂肪变性和血清ALT水平较低。在乙醇处理的 ALDH2-/- 小鼠精密切割肝脏切片中以及从乙醇喂养的 ALDH2-/- 小鼠中分离的 Kupffer 细胞中也检测到比 WT 小鼠更高的 IL-6 水平。与 MAA 体外孵育增强了 Kupffer 细胞中 LPS 介导的 IL-6 产生刺激。与这些发现一致的是，乙醇喂养的 ALDH2-/- 小鼠中主要 IL-6 下游信号分子信号转导子和转录激活子 3 (STAT3) 的肝脏激活高于 WT 小鼠。额外删除肝脏 STAT3 会导致 ALDH2-/- 小鼠脂肪变性和肝细胞损伤增加。最后，乙醇喂养的 ALDH2-/- 小鼠比乙醇喂养的 WT 小鼠更容易发生 CCl4 诱导的肝脏炎症和纤维化。结论：ALDH2-/- 小鼠对乙醇诱导的脂肪变性有抵抗力，但容易通过 MAA 介导的 Kupffer 细胞中 IL-6 的旁分泌激活而发生炎症和纤维化。这些发现表明，缺乏 ALDH2 的个体可能对脂肪变性有抵抗力，但饮酒后容易出现肝脏炎症和纤维化。 泼尼松龙是一种皮质类固醇，已用于治疗炎症性肝病，例如自身免疫性肝炎和酒精性肝炎。然而，结果存在争议，泼尼松龙如何影响肝病进展仍不清楚。在本报告期内，我们研究了泼尼松龙治疗对多种肝损伤模型的影响，包括刀豆蛋白 A (Con A) 和半乳糖神经酰胺 (-GalCer) 诱导的 T/NKT 细胞肝炎，以及四氯化碳 (CCl4) 诱导的肝毒素介导的肝炎。泼尼松龙给药可减弱 ConA 和 GalCer 诱导的肝炎和全身炎症反应。在肝毒素（CCl4）诱导的肝炎模型中，用泼尼松龙治疗小鼠也抑制了炎症反应，但令人惊讶的是，它加剧了肝损伤并延迟了肝脏修复。免疫组织化学和流式细胞术分析表明，泼尼松龙治疗可抑制 CCl4 诱导的肝炎中的肝脏巨噬细胞和中性粒细胞浸润，并抑制其体内和体外的吞噬细胞活性。巨噬细胞和/或中性粒细胞耗竭加剧了 CCl4 诱导的肝损伤并阻碍了肝再生。最后，巨噬细胞和中性粒细胞中糖皮质激素受体的条件性破坏消除了泼尼松龙介导的肝毒素诱导的肝损伤的恶化。结论：泼尼松龙治疗可预防 T/NKT 细胞肝炎，但通过抑制巨噬细胞和中性粒细胞介导的吞噬和再生功能，加剧肝毒素诱导的肝损伤。这些发现不仅可以增加我们对类固醇治疗机制的了解，还可以帮助我们更好地管理肝脏疾病的类固醇治疗。 此外，我们还与博士合作。 NIAAA 的 George Kunos 和 Pal Pacher 致力于研究内源性大麻素系统在酒精性肝病中的作用。