Establishing the mechanism of benefit and dose of exercise required to improve liver histology in patients with nonalcoholic steatohepatitis

建立改善小鼠肝脏组织学所需的益处和运动剂量的机制 非酒精性脂肪性肝炎患者 项目总结-在这个职业发展计划中，我将研究锻炼如何改善非酒精 脂肪性肝炎(NASH)，并回答关于运动的(1)益处机制的三个非常重要的问题， (2)剂量；(3)对肝脏组织学的影响。这个项目建立在我在NASH的临床经验上 指导培训：(1)机械研究(Scot Kimball博士)，(2)锻炼(Kathryn Schmitz博士，Christopher博士 (3)NASH试验(罗希特·伦巴博士)。这项提议的中心假设是练习 训练将通过耗尽肝糖原激活AMP激活的蛋白激酶(AMPK)，导致肝脏 NASH患者的脂肪减少和中间组织学终点改善。因为 糖原是运动过程中产生ATP的主要底物，我假设运动会导致糖原 AMPK的解离和随后的AMPK激活。中心假设是基于16周的证明 18例成人NASH患者的概念性研究，其中我只发现那些完成750代谢测试的患者 任务当量(MET)-分钟/周运动量在以下方面实现了最小的临床重要差异 磁共振成像质子密度脂肪分数(MRI-PDFF)测量的肝脏脂肪，可以替代 组织学反应。我观察到这与AMPK通路的间接变化是平行的，提示AMPK 是通过锻炼而激活的。虽然我没有研究运动剂量&gt；750 Met-min/wk，但有可能更高的剂量 可能更有效，因为糖原耗竭需要持续的中等强度 锻炼身体。根据这些试验数据，我将进行一项为期16周的临床试验，并将患有NASH的成年人随机分成不同的组 运动量(750或1,000 Met-min/wk)或标准临床护理。为了确保遵守，每个练习 会议将在直接监督下完成，无论是面对面的还是远程远程医疗，随后 立即计算运动剂量，如强度(METS)×频率(一次会议)×时间(分钟)。在目标1中，我 将通过磁共振波谱测量肝糖原的变化来研究运动有益的机制和 单次持续中等强度运动后的三磷酸腺苷。在目标2中，我将辨别哪种剂量是 最有效的减少16周运动训练后的MRI-PDFF。在目标3中，我将衡量重要的 中间组织学终点(NASH活性评分)和机制(AMPK激活，AMPK靶点)。共同-- 肝组织中结合AMPK的糖原的定位将被用来证实间接磁共振波谱证据 当我成功时，我将提供严格的证据来破译所需的剂量和 解释运动训练如何改善中间组织学的潜在机制 端点，包括NASH活动。这项研究将通过为样本生成数据来为未来的试验设计提供信息 研究运动对包括肝纤维化在内的长期组织学结果的影响所需的大小估计。我 我致力于内科科学家的职业生涯，并制定了我的培训计划，以实现科学 并为推进NASH和公共卫生的研究做出了实质性贡献。

Establishing the mechanism of benefit and dose of exercise required to improve liver histology in patients with nonalcoholic steatohepatitis PROJECT SUMMARY— In this career development program, I will study how exercise improves nonalcoholic steatohepatitis (NASH) and answer three highly significant questions about exercise’s (1) mechanism of benefit, (2) dose, and (3) impact on liver histology. This program builds on my clinical experience in NASH through mentored training in: (1) mechanistic study (Dr. Scot Kimball), (2) exercise (Drs. Kathryn Schmitz, Christopher Sciamanna), and (3) NASH trials (Dr. Rohit Loomba). The central hypothesis of this proposal is that exercise training will activate AMP-activated protein kinase (AMPK) by depleting liver glycogen, leading to liver fat reduction and intermediate histologic endpoint improvement in patients with NASH. Because glycogen is the main substrate used during exercise to generate ATP, I hypothesize exercise will lead to glycogen dissociation from AMPK and subsequent AMPK activation. The central hypothesis is based on a 16-wk proof of concept study in 18 adult patients with NASH in which I found only those who completed a 750 Metabolic Equivalents of Task (MET)-min/wk dose of exercise achieved the minimal clinically important difference in magnetic resonance imaging proton density fat fraction (MRI-PDFF) measured liver fat, that surrogates for histologic response. I observed this in parallel with indirect changes in the AMPK pathway, suggesting AMPK was activated by exercise. While I did not study exercise dose >750 MET-min/wk, it is plausible that higher doses may be even more effective because glycogen depletion requires sustained moderate-vigorous intensity exercise. Given these pilot data, I will conduct a 16-wk clinical trial and randomize adults with NASH to different exercise doses (750 or 1,000 MET-min/wk) or standard clinical care. To ensure adherence, each exercise session will be completed under direct supervision, either in-person or remotely with telehealth, followed by immediate calculation of exercise dose as intensity (METs) x frequency (one session) x time (min). In Aim 1, I will study the mechanism of exercise’s benefit with MR-spectroscopy measured change in liver glycogen and ATP following a single session of sustained moderate-vigorous exercise. In Aim 2, I will discern which dose is most effective in reducing MRI-PDFF after 16-wks of exercise training. In Aim 3, I will measure important intermediate histologic endpoints (NASH activity score) and mechanisms (AMPK activation, AMPK targets). Co- localization of glycogen binding to AMPK in liver tissue will be used to confirm indirect MR-spectroscopy evidence from Aim 1. When I am successful, I will have provided rigorous evidence to decipher the dose required and the underlying mechanisms explaining how exercise training leads to improvement in intermediate histologic endpoints, including NASH activity. This research will inform future trial design by generating data for sample size estimates necessary to study exercise’s impact on long-term histologic outcomes, including liver fibrosis. I am committed to a career as a physician scientist and have constructed my training plan to achieve scientific independence and make substantial contributions to advancing the study of NASH and public health.