Nonalcoholic fatty liver disease (NAFLD), which is the most prevalent hepatic disorder worldwide, affecting 25% of the general population, describes a spectrum of progressive liver conditions ranging from relatively benign liver steatosis and advancing to nonalcoholic steatohepatitis (NASH), fibrosis, and cirrhosis. Hallmark features of NASH are fatty hepatocytes and inflammatory cell infiltrates in association with increased activation of hepatic nuclear factor kappa-B (NFκB) that exacerbates liver injury. Because no pharmacological treatments exist for NAFLD, emphasis has been placed on dietary approaches to manage NASH risk. Anti-inflammatory bioactivities of catechin-rich green tea extract (GTE) have been well-studied, especially in preclinical models that have detailed its effects on inflammatory responses downstream of NFκB activation. This review will therefore discuss the experimental evidence that has advanced an understanding of the mechanisms by which GTE, either directly through its catechins or potentially indirectly through microbiota-derived metabolites, limits NFκB activation and NASH-associated liver injury. Specifically, it will describe the hepatic-level benefits of GTE that attenuate intracellular redox distress and pro-inflammatory signaling from extracellular receptors that otherwise activate NFκB. In addition, it will discuss the anti-inflammatory activities of GTE on gut barrier function as well as prebiotic and antimicrobial effects on gut microbial ecology that help to limit the translocation of gut-derived endotoxins (e.g. lipopolysaccharides) to the liver where they otherwise upregulate NFκB activation by Toll-like receptor-4 signaling. This summary is therefore expected to advance research translation of the hepatic- and intestinal-level benefits of GTE and its catechins to help manage NAFLD-associated morbidity.

非酒精性脂肪肝疾病（NAFLD）是全球最普遍的肝病，影响了25％的普通人群，描述了一系列进行性肝病，范围从相对良性肝脂肪变性到非酒精性脂肪性肝炎（NASH），纤维化和肝硬化。NASH的标志性特征是脂肪肝细胞和炎性细胞浸润，与加剧肝损伤的肝核因子κB（NFκB）活化相关。由于不存在针对NAFLD的药物治疗，因此重点放在了控制NASH风险的饮食方法上。富含儿茶素的绿茶提取物（GTE）的抗炎生物活性已得到充分研究，尤其是在临床前模型中，该模型已详细阐明了其对NFκB活化下游炎症反应的影响。因此，本综述将讨论对GTE的机制有更深入了解的实验证据，GTE通过其儿茶素直接或潜在地通过微生物群衍生的代谢物间接限制NFκB活化和NASH相关的肝损伤。具体来说，它将描述GTE的肝水平益处，该作用可减轻细胞内氧化还原窘迫和来自细胞外受体的促炎性信号传导，否则它们会激活NFκB。此外，还将讨论GTE对肠道屏障功能的抗炎活性以及对肠道微生物生态的益生元和抗菌作用，这有助于限制肠道衍生的内毒素（例如脂多糖）向肝脏的转运，否则会上调肝脏的内毒素Toll样受体4信号传导激活NFκB。