Nicotine and Alcoholic Liver Disease

摘要 酗酒是一个重大的全球健康问题。长期饮酒会导致酒精性肝病， 其范围从脂肪变性(脂肪肝)到脂肪性肝炎、纤维化和肝硬变。大约90%的重酒 饮酒者会患上酒精性脂肪肝(AFL)，这是酒精性肝病的一种症状。最近，我们发现， 慢性酒精摄入可诱导细胞色素P450 2A5(人体中的细胞色素P450 2 A6)表达，酗酒者细胞色素P450 2 A6水平升高 病人。细胞色素P450 2A5/6是一种主要的尼古丁代谢酶。酒精和烟草经常被共同滥用， 吸烟会增加AFL。我们发现尼古丁，一种在烟草烟雾中形成碱性的主要成瘾性物质， 能提高AFL和高甘油三酯血症(HTG)，这在WT小鼠中观察到，但在cyp2a5-/-小鼠中观察不到。 PPARα调控的成纤维细胞生长因子21是一种在肝脏中高表达的新的代谢调节因子。我们观察到了一个本构的 Cyp2a5-/-小鼠肝脏PPARα-FGF21的升高。乙醇诱导α-/-小鼠酒精性高血糖的观察 RFGF21可阻断极低水平的血清FGF21。乙醇/尼古丁诱导的AFL 在肝脏特异性FGF21 KO小鼠中更为明显。这些结果表明，FGF21可能起重要的作用 FGF21通过成纤维细胞生长因子受体1(FR1)调节细胞活性，FR1主要在脂肪中表达 在组织中，在肝脏中的程度要小得多。我们没有观察到AFL和HTG在肝脏和肝脏之间有任何差异。 特异性FR1KO小鼠和它们的WT对照小鼠，表明在我们的模型中，更重要的可能是 脂肪FR1，但不是肝脏FR1。肝脏FGF21可以释放到血液中，以内分泌方式发挥作用。FGF21 可刺激脂肪细胞分泌脂联素，进而作用于肝脏，改善AFL。在目标1中，我们 将通过AAV8将CYP2A5重新引入cyp2a5/-小鼠，以验证CYP2A5在 尼古丁增强AFL和HTG以及应用可替宁和抗氧化剂来检测CYP2A5产生的作用 尼古丁增强的AFL和HTG中的尼古丁代谢物和氧化应激。在AIM 2中，我们将研究 PPARα-FGF21轴在尼古丁增强的AFL和HTG中的作用应用PPARα-/-/cyp2a5-/-小鼠，肝- 特异性FGF21基因敲除小鼠和PPARα特异性激动剂WY-14,643。在AIM 3中，细胞与细胞之间的相互作用 脂肪细胞和肝细胞的培养体系将被检查以反映器官与器官之间的相互作用 脂肪组织和肝脏。脂联素基因敲除小鼠将接受rFGF21治疗，以评估肝脏FGF21是否 通过脂联素，即PPARα-FGF21-脂联素在脂肪组织中发挥作用，调节尼古丁- 增强的AFL和HTG。最后，将脂联素和细胞色素P450 2A5双基因敲除小鼠应用于研究 脂联素在观察尼古丁增强的WT小鼠AFL和HTG中的作用 在cyp2a5-/-小鼠中不存在。

ABSTRACT Alcohol abuse is a significant global health problem. Chronic alcohol drinking can induce alcoholic liver disease, which ranges from steatosis (fatty liver) to steatohepatitis, fibrosis and cirrhosis. About 90% of heavy alcohol drinkers develop alcoholic fatty livers (AFL), an onset of alcoholic liver disease. Recently, we found that CYP2A5 (CYP2A6 in humans) is induced by chronic ethanol feeding and CYP2A6 is elevated in alcoholic patients. CYP2A5/6 is a major nicotine metabolic enzyme. Alcohol and tobacco are frequently co-abused and tobacco smoke can increase AFL. We found that nicotine, a major addictive forming alkaline in tobacco smoke, can enhance AFL and hypertriglyceridemia (HTG), which was observed in WT mice but not in cyp2a5-/- mice. PPARα-regulated FGF21 is a novel metabolic regulator highly expressed in liver. We observed a constitutive elevation of hepatic PPARα-FGF21 in cyp2a5-/- mice. Ethanol-induced HTG observed in pparα-/- mice with an extremely low serum FGF21 can be blocked by the treatment of rFGF21. Ethanol/nicotine-induced AFL was more pronounced in liver-specific FGF21 KO mice. These results suggest that FGF21 may play an important role in FGF21 modulates cellular activity through FGF receptor 1 (FR1), which is mainly expressed in adipose tissues and to a much lesser extent in liver. We didn’t observe any difference in AFL and HTG between liver- specific FR1 KO mice and their WT control mice, suggesting that in our model the more important might be adipose FR1 but not liver FR1. Liver FGF21 can be released into blood to act in an endocrine manner. FGF21 can stimulate adipocytes to secret adiponectin, which in turn acts on the liver to ameliorate AFL. In AIM 1, we will reintroduce CYP2A5 back to cyp2a5-/- mice via AAV8 to validate the essential role of CYP2A5 in the nicotine-enhanced AFL and HTG and apply cotinine and antioxidant to examine the role of CYP2A5-produced nicotine metabolites and oxidative stress in the nicotine-enhanced AFL and HTG. In AIM 2, we will examine the role of a PPARα-FGF21 axis in the nicotine-enhanced AFL and HTG by applying pparα-/-/cyp2a5-/- mice, liver- specific FGF21 knockout mice and PPARα specific agonist WY-14,643. In AIM 3, cell-cell interaction in cell co- culture system of adipocytes and hepatocytes will be examined to reflect organ-organ interaction between adipose tissue and liver. Adiponectin knockout mice will be treated with rFGF21 to evaluate if liver FGF21 exerts its action in adipose tissue through adiponectin i.e. the PPARα-FGF21-adiponectin to regulate nicotine- enhanced AFL and HTG. At last, adiponectin and CYP2A5 double knockout mice will be applied to investigate the role of adiponectin in the observation that nicotine-enhanced AFL and HTG was observed in WT mice but not in cyp2a5-/- mice.