Protective role of adenosine 2A receptor in NAFLD

腺苷2A受体在NAFLD中的保护作用

• 批准号: 9043865
• 负责人: Chaodong Wu
• 金额: $ 31.72万
• 依托单位: TEXAS A&M AGRILIFE RESEARCH
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-15 至 2018-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9043865
• 关键词: ADORA2A gene; Adenosine; Agonist; Anti-Inflammatory Agents; Anti-inflammatory; Binding; Binding Proteins; Bone Marrow Transplantation; Carbohydrates; Cells; Coculture Techniques; Conditioned Culture Media; Development; Elements; Enzymes; Event; Exhibits; Family; Fatty Liver; Functional disorder; G-Protein-Coupled Receptors; Gene Expression; Genes; Goals; Health; Hepatic; Hepatocyte; High Fat Diet; Immune; In Vitro; Inflammation; Inflammatory; Inflammatory Response; Interleukin-6; Knowledge; Kupffer Cells; Leukocytes; Liver; Liver Cirrhosis; Liver diseases; Metabolic; Metformin; Methionine; Mus; Myeloid Cells; Nutrient; Palmitates; Pathogenesis; Phosphorylation; Play; Prevention; Primary carcinoma of the liver cells; Property; Purinergic P1 Receptors; Receptor Activation; Receptor Inhibition; Regulatory Element; Research; Role; Sterols; TNF gene; Testing; Wild Type Mouse; base; cell type; choline deficient diet; cytokine; effective therapy; evidence base; expectation; feeding; in vivo; knock-down; lipid biosynthesis; liver inflammation; macrophage; member; non-alcoholic fatty liver; nonalcoholic steatohepatitis; novel; novel strategies; prevent; promoter; receptor; receptor function; research study

DESCRIPTION (provided by applicant): Nonalcoholic fatty liver disease (NAFLD) is one of the most common causes of terminal liver diseases including liver cirrhosis and hepatocellular carcinoma. Growing evidence demonstrates the critical importance of inflammation in the pathogenesis of NAFLD. For instance, nutrient overload triggers inflammation, which can act through stimulating lipogenesis to increase hepatic steatosis. The latter, in turn, can exacerbate liver inflammation and progress to non-alcoholic steatohepatitis (NASH). However, the precise mechanisms underlying the interaction between hepatic steatosis and liver inflammation remain to be elucidated. Thus, the long-term goal of the proposed research is to dissect the metabolic and inflammatory mechanisms underlying NAFLD in order that novel evidence-based approaches can be developed for preventing and/or treating NASH. As a G-protein-coupled receptor, adenosine 2A receptor (A2AR) is abundantly expressed in immune cells and exhibits powerful anti-inflammatory properties. A2AR is also highly expressed in hepatocytes, in which A2AR functions are largely unknown. For this project, the central hypothesis is that the A2AR in hepatocytes and macrophages protects against the development of different aspects of NAFLD in a cell-type-dependent manner. This hypothesis is based on the following novel findings: 1) A2AR deficiency in hepatocytes plays a more important role than A2AR deficiency in myeloid cells (macrophages) in exacerbating high-fat diet (HFD)- induced hepatic steatosis, which is associated with increased hepatic expression of lipogenic enzymes; 2) A2AR deficiency exacerbates HFD-induced liver inflammation, which is likely attributed to increased macrophage/Kupffer cell proinflammatory activation; and 3) A2AR activation by a specific agonist protects mice from HFD-induced NAFLD. Thus, the goal of this project is to define a novel protective role for A2AR in NAFLD. For this purpose, mice that lack A2AR in hepatocytes and/or myeloid cells are generated. For Specific Aim 1, in vivo experiments will be performed to examine the extent to which the A2AR in hepatocytes acts through inhibiting lipogenesis to protect against NAFLD. Moreover, cellular experiments will be performed to elucidate the involvement of SREBP1c and ChREBP in A2AR inhibition of lipogenic gene expression. For Specific Aim 2, in vivo experiments will be performed to examine the extent to which the A2AR in macrophages or hepatocytes protects against NAFLD by suppressing liver inflammatory response. For Specific Aim 3, in vivo experiments will be performed to define A2AR coordination of hepatocyte-macrophage crosstalk in NAFLD. Moreover, in vitro co-culture experiments will be performed to examine the extent to which factors generated by A2AR-deficient macrophages, i.e., TNF? and IL-6, stimulate hepatocyte lipogenesis, and the extent to which factors generated by A2AR-deficient hepatocytes, i.e., palmitate, stimulate macrophage proinflammatory activation. Together, the proposed research will illustrate a new paradigm on NAFLD, and provide the experimental basis for prevention and/or treatment of NASH by means of A2AR activation.

描述（由申请人提供）：非酒精性脂肪肝病（NAFLD）是终末肝病（包括肝肝硬化和肝细胞癌）最常见的原因之一。越来越多的证据表明，炎症在NAFLD的发病机理中的重要性。例如，营养超负荷会触发炎症，可以通过刺激脂肪生成来增加肝脂肪变性。后者反过来会加剧肝脏炎症并发展为非酒精性脂肪性肝炎（NASH）。然而，肝脂肪变性与肝脏炎症之间相互作用的确切机制尚待阐明。因此，拟议的研究的长期目标是剖析NAFLD潜在的代谢和炎症机制，以便可以开发出新颖的基于证据的方法来预防和/或治疗NASH。作为G蛋白偶联受体，腺苷2A受体（A2AR）在免疫细胞中大量表达，并表现出强大的抗炎特性。 A2AR在肝细胞中也高度表达，其中A2AR功能在很大程度上未知。对于这个项目，中心假设是肝细胞和巨噬细胞中的A2AR可以以细胞型依赖性方式保护NAFLD不同方面的发展。该假设基于以下新颖的发现：1）肝细胞中的A2AR缺乏症在加剧高脂饮食（HFD）诱导的肝脂肪变性的髓样细胞（巨噬细胞）中起着比A2AR缺乏症的重要作用，这与脂肪生成性肾上腺素肝表达增加相关。 2）A2AR缺乏加剧了HFD诱导的肝脏炎症，这可能归因于巨噬细胞/库普弗细胞促进促炎激活的增加； 3）特定激动剂的A2AR激活可保护小鼠免受HFD诱导的NAFLD的影响。因此，该项目的目的是定义NAFLD中A2AR的新型保护作用。为此，产生了在肝细胞和/或髓样细胞中缺乏A2AR的小鼠。对于特定的目标1，将进行体内实验，以检查肝细胞中A2AR通过抑制脂肪生成以预防NAFLD的作用的程度。此外，将进行细胞实验，以阐明SREBP1C和CHREBP参与A2AR抑制脂肪生成基因表达。对于特定的目标2，将进行体内实验，以检查巨噬细胞或肝细胞中A2AR通过抑制肝脏炎症反应来预防NAFLD的程度。对于特定的目标3，将进行体内实验，以定义NAFLD中肝细胞巨噬细胞串扰的A2AR协调。此外，将进行体外共培养实验，以检查A2AR缺陷型巨噬细胞产生的因素，即TNF？ IL-6刺激肝细胞脂肪生成，以及A2AR缺陷型肝细胞产生的因素，即棕榈酸酯，刺激巨噬细胞促进促炎的激活。拟议的研究将共同​​说明NAFLD的新范式，并通过A2AR激活为预防和/或治疗NASH提供实验基础。