Anti-Inflammatory Roles and Macrophage Metabolism of Lactate and Ketones during Myocardial Infarction

项目摘要/摘要 在美国，每年约有100万人患有心肌梗塞(MI)，导致 在约25%的存活患者中，进行性心功能障碍和心力衰竭(HF)的发展。糖尿病 糖尿病是心肌梗死的主要危险因素，糖尿病患者的死亡率更高，而且 罹患心力衰竭的风险。由于目前的治疗方法在预防不良心脏重塑方面的成功有限 心肌梗死后，需要新的治疗靶点来有效地促进充分的愈合和限制组织损伤， 尤其是在糖尿病患者中。过度的巨噬细胞介导的炎症是导致 心肌梗死后心脏重构不良，糖尿病患者心肌梗死后表现为恶化和持续 炎症反应。巨噬细胞在促炎的“M1”之间极化的一个关键机制 抗炎/促进修复的“M2”亚群是通过以表型为特征的代谢重新编程来实现的 在促进M1极化的糖酵解代谢和线粒体氧化之间切换 磷酸化(OXPHOS)，促进M2极化。使用海马新陈代谢流量分析，我有 发现在早期炎症阶段(小鼠心肌梗死后第1天和第3天)，梗死性巨噬细胞 糖酵解，而在愈合期(第7天)，巨噬细胞恢复到葡萄糖氧化和OXPHOS。在……里面 除葡萄糖外，巨噬细胞还可以代谢“替代”燃料，包括乳酸和酮体，这些 推广M2表型。然而，巨噬细胞在体内乳酸和酮体代谢中的作用 MI尚不清楚，这些化合物的给药或内源性生产是否能促进M2 巨噬细胞在心肌梗塞期间的极化也是未知的。我的初步数据表明基因的表达 与乳酸(MCT1，Ldhb)和酮(Oxct1)相关的代谢在创伤期间在巨噬细胞中上调 心肌梗塞的愈合期。进一步的初步数据表明，在体内给药乳酸盐或酮，或喂养 生酮饮食可减弱心肌梗塞后巨噬细胞的免疫代谢表型。这表明， 这些底物的代谢可能是心肌梗死后M2极化和心脏愈合的基础。因此，假设 因为这一提议是提高内源性生产或外源性乳酸盐和 酮类通过改善巨噬细胞改善心肌梗死后心脏重构和减轻心脏损伤 新陈代谢和极化。我还提出，糖尿病通过受损加重心肌梗死的损伤 巨噬细胞乳酸和酮代谢。为了解决这些假设，我将使用临床相关的鼠标 心肌梗塞和糖尿病的模型，以及巨噬细胞特异的转基因小鼠，加上- 最先进的心功能测量技术(高分辨率超声心动图和4D成像)， 活细胞代谢、免疫磁性分选巨噬细胞分离和流式细胞术。这些研究 将为乳酸和酮介导的心脏保护提供新的机制，并提供新的靶向策略 心脏损伤后的巨噬细胞代谢。

PROJECT SUMMARY/ABSTRACT Approximately 1 million people in the United States suffer a myocardial infarction (MI) each year, leading to progressive cardiac dysfunction and development of heart failure (HF) in ~25% of surviving patients. Diabetes mellitus is a major risk factor for MI, and patients with diabetes suffer from higher mortality rates and increased risk of developing HF. Due to the limited success of current therapies in preventing adverse cardiac remodeling after MI, novel therapeutic targets are needed to effectively promote adequate healing and limit tissue damage, especially in diabetic patients. Excessive macrophage-mediated inflammation is a key mechanism leading to adverse cardiac remodeling after MI, and patients with diabetes display exacerbated and persistent post-MI inflammatory responses. A key mechanism by which macrophages polarize between the pro-inflammatory “M1” and anti-inflammatory/pro-reparative “M2” subsets is via metabolic reprogramming characterized by phenotypic switches between glycolytic metabolism, which promotes M1 polarization, and mitochondrial oxidative phosphorylation (OXPHOS), which promotes M2 polarization. Using Seahorse metabolic flux analysis, I have found that during the early inflammatory phase (day 1 and 3 after MI in mice), infarct macrophages become glycolytic, whereas during the healing phase (day 7), macrophages revert to glucose oxidation and OXPHOS. In addition to glucose, macrophages can metabolize “alternative” fuels, including lactate and ketone bodies, which promote an M2 phenotype. However, the role of lactate and ketone body metabolism by macrophages during MI is unknown, and whether administration or endogenous production of these compounds can promote M2 macrophage polarization during MI is also not known. My preliminary data indicate that expression of genes related to lactate (Mct1, Ldhb) and ketone (Oxct1) metabolism are upregulated in macrophage during the wound healing phase of MI. Further preliminary data indicates that in vivo administration of lactate or ketones, or feeding a ketogenic diet attenuates the macrophage immunometabolic phenotype after MI. This indicates that metabolism of these substrates may underlie M2 polarization and cardiac healing after MI. Thus, the hypothesis for this proposal is that elevated endogenous production or exogenous administration of lactate and ketones will improve cardiac remodeling and reduces cardiac injury after MI via improved macrophage metabolism and polarization. I also propose that diabetes exacerbates MI injury via impaired macrophage lactate and ketone metabolism. To address these hypotheses, I will use clinically relevant mouse models of MI and diabetes mellitus, and macrophage-specific genetically modified mice, coupled with state-of- the-art techniques for measuring cardiac function (high resolution ultrasound echocardiography and 4D imaging), live cellular metabolism, macrophage isolation by immunomagnetic sorting, and flow cytometry. These studies will provide new mechanisms of lactate and ketone-mediated cardioprotection, and novel strategies for targeting macrophage metabolism following cardiac injury.