BLRD Research Career Scientist Award Application

我目前研究的主要主题是了解生长激素(GH)和胰岛素样物质如何 生长因子I(IGF1)调节成人代谢功能以及GH/IGF1的合成和分泌如何失调 信号转导有助于代谢性疾病的进展，以及相关的组织损伤和修复。一位少校 我的工作重点是了解非酒精性脂肪性肝病(NAFLD)的病因。NAFLD代表 肝脏过度脂肪堆积(脂肪变性)，没有或有炎症/纤维化(非酒精性 脂肪性肝炎(NASH)。非酒精性脂肪肝通常见于肥胖和2型糖尿病，但也可见于 与心血管疾病相关的非肥胖患者，所有疾病在退伍军人中更常见， 与普通人群相比。NASH增加了患肝癌的风险，目前已被认识到 作为肝移植的首要原因。膳食脂肪酸(FA)和来源于脂肪组织的FA 脂肪分解，由于全身性胰岛素抵抗，是NAFLD的主要因素。此外，增强的肝硬化症 新的脂肪生成作用(DNL)有助于NAFLD的发生。临床和实验研究表明非酒精性脂肪肝与 生长激素信号减少(反映为血浆生长激素和肝脏生长激素抵抗降低，导致IGF1水平降低)。这个 生长激素信号的减少可能会加剧NAFLD，研究表明GH/GH受体中存在SNPs (GHR)/JAK2/Stat5信号通路与NAFLD相关。此外，增加生长激素可以减少非酒精性脂肪肝 无论是人类还是老鼠。 表达甲状腺激素结合球蛋白启动子驱动的Cre[AAV8-TBGp-Cre]的腺相关病毒载体 与DNL增加相关的脂肪变性的迅速发展(Cordoba-Chacon等人，糖尿病 2015年)。在翻译相关性方面，HepGHRkd后的肝脏DNL/脂肪变性随年龄和相关因素而持续 肝细胞肿胀、炎症和纤维化(NASH的特征；Cordoba-Chacon等人， 内分泌学2018年)。我目前的R01中概述的研究采用了多层次的方法来定义 肝细胞生长激素信号直接控制糖酵解DNL的生化/分子机制 和脂肪变性，通过操纵小鼠肝细胞生长激素信号，通过肝细胞特异性的AAV载体传递 然后评估生长激素信号通路中的转基因；酶的基因和蛋白质表达 糖酵解和脂肪生成途径、GC/MS分析的脂肪酸组成、糖酵解通量和三氯乙酸循环中间体 在高胰岛素状态下：使用稳定的同位素示踪剂，高血糖钳夹。在我的本期报告中概述的研究 BL&RD VA的优点在于肝细胞生长激素信号的减少如何在饮食诱导的NASH中起作用 以及如何使用AAV载体重建GHR信号通路(特别是Stat5b活性和/或IGF1 分娩)可以预防和/或逆转脂肪变性和肝脏损伤。到目前为止，我们已经有了令人兴奋的初步数据 提示，肝细胞GH信号独立于Stat5b/IGF1发挥抑制肝脏DNL的作用，而Stat5b 是保护肝脏免受饮食损伤的关键。这些保护作用可能延伸到其他类型的肝脏。 伤害，包括由环境毒素引起的伤害(重点纪念飞行员奖)。 除了评估GH/IGF1在保护肝脏免受损伤方面的作用外，与Timothy合作 KOH，PhD(UIC，伤口愈合专家)我们正在探索IGF1在调节糖尿病伤口愈合中的作用。 这些研究是由RR&D VA Merit资助的，并检查了小鼠伤口愈合的基本机制 有或没有肝脏IGF1产生的胰岛素抵抗(饮食诱导)和糖尿病(db/db)模型。研究 还将检查低强度振动贴片(由罗格斯大学Onur Bilgen博士开发和优化)是否可以 通过增强IGF1的产生/作用来加速伤口愈合。综上所述，这些基础研究将有助于 确定可用于制定治疗策略的独特目标，以防止有害的 肥胖/糖尿病的后果，这在退伍军人中很常见。

The overarching theme of my current research is to understand how growth hormone (GH) and insulin-like growth factor I (IGF1) regulate adult metabolic function and how dysregulation of GH/IGF1 production and signaling contributes to the progression of metabolic disease, as well as related tissue injury and repair. A major focus of my work is to understand the etiology of non-alcoholic fatty liver disease (NAFLD). NAFLD represents a spectrum of excess fat accumulation in the liver (steatosis) without or with inflammation/fibrosis (non-alcoholic steatohepatitis - NASH). NAFLD is commonly observed in obesity and type 2 diabetes, but is also observed in non-obese patients associated with cardiovascular disease, where all diseases are more prevalent in Veterans, compared to the general population. NASH increases the risk of developing liver cancer, and is now recognized as the leading cause for liver transplantation. Dietary fatty acids (FA) and FA derived from adipose tissue lipolysis, due to systemic insulin resistance, are major contributors to NAFLD. In addition, enhanced hepatic de novo lipogenesis (DNL) contributes to NAFLD. Clinical and experimental studies show NAFLD is associated with reduced GH-signaling (reflected by low plasma GH and hepatic GH resistance, leading to low IGF1 levels). The reduction in GH-signaling may exacerbate NAFLD, based on studies showing SNPs within the GH / GH receptor (GHR) /JAK2 / Stat5 signaling pathway are associated with NAFLD. Also, increasing GH can reduce NAFLD in both humans and mice. We have reported that adult-onset loss of hepatocyte GH signaling (aHepGHRkd; GHRfl/fl mice treated with an adeno-associated viral vector expressing thyroxine binding globulin promoter driven Cre [AAV8-TBGp-Cre]) led to the rapid development of steatosis, associated with an increase in DNL (Cordoba-Chacon et al., Diabetes 2015). Of translational relevance, hepatic DNL/steatosis after aHepGHRkd is sustained with age and associated with hepatocyte ballooning, inflammation and fibrosis (hallmarks of NASH; Cordoba-Chacon et al., Endocrinology 2018). Studies outlined in my current R01 take a multi-level approach to define the biochemical/molecular mechanisms by which hepatocyte GH-signaling directly controls glycolysis-driven DNL and steatosis, by manipulating hepatocyte GH signaling in mice by hepatocyte-specific, AAV-vector delivery of transgenes within the GH-signaling pathway then assessing; gene and protein expression of enzymes in glycolytic and lipogenic pathways, fatty acid composition by GC/MS, glycolytic flux and TCA cycle intermediates under hyperinsulinemic:hyperglycemic clamps, using stable isotope tracers. Studies outlined in my current BL&RD VA Merit are focused how the reduction in hepatocyte GH signaling contributes to diet-induced NASH and how reconstitution of the GHR signaling pathway (specifically Stat5b activity and/or IGF1 using AAV vector delivery) may prevent and/or reverse steatosis and liver injury. To date we have exciting preliminary data suggesting, hepatocyte GH-signaling works independently of Stat5b/IGF1 to suppress hepatic DNL, while Stat5b is critical to protect the liver from diet-induced injury. These protective effects may extend to other types of liver injury including those induced by environmental toxins (focus of CACHET pilot award). In addition to assessing the role of GH/IGF1 in protecting the liver from injury, in collaboration with Timothy Koh, PhD (UIC, wound healing expert) we are exploring the role of IGF1 in regulating diabetic wound healing. These studies are funded by a RR&D VA Merit and examine the basic mechanisms of wound healing in mouse models of insulin-resistance (diet-induced) and diabetes (db/db) with or without hepatic IGF1 production. Studies will also examine if low-intensity vibration patches (developed and optimized by Onur Bilgen PhD, Rutgers) can speed wound healing via enhanced IGF1 production/actions. Taken together, these basic studies will help to identify unique targets that can be used to develop treatment strategies, in order to prevent the deleterious consequences of obesity/diabetes, which are commonly found in the Veteran population.