Novel regulators of macrophage function to repair sterile inflammation-induced heart injury

项目摘要 从免疫学的角度来看，心脏是一个独特的器官，因为它对损伤的耐受性极低 和炎症。越来越多的基础和临床研究证据表明， 急性心肌缺血/再灌注（I/R）或慢性代谢紊乱（即，2型糖尿病），起着至关重要的作用 在心力衰竭的发展中起作用，心力衰竭是全球死亡的主要原因。不幸的是，临床试验试图 调节心力衰竭炎症的方法要么令人失望，要么不一致， 适用因这一发人深省的事实加强了迫切需要探索新的心脏炎症介质， 更好地了解其潜在的分子/细胞机制。NIGMS支持的主要研究 在过去的5年里，研究者的实验室已经鉴定出几种新的介质及其相关的信号传导 炎症触发的心脏损伤中控制免疫功能障碍的途径。首先，我们发现， 和跨膜1a（Sectm 1a），一种在髓系免疫细胞中高度表达的蛋白质，对于 巨噬细胞（M β）吞噬细胞以清除I/R心脏中的死细胞，从而恢复心脏功能。第二、 使用2型糖尿病（T2 D）小鼠作为慢性低度炎症模型，我们确定了脂质运载蛋白10的缺失， （Lcn 10），脂质运载蛋白超家族的一个特征性较差的成员，可能会导致不平衡的M β极化， T2 D心脏最后，我们有了一个新的发现，益生菌释放的细胞外膜囊泡（EV） 细菌可促进巨噬细胞增多，但其潜在机制尚不清楚。在一起，这些不同的和 令人信服的数据为解决不育研究中的三个关键知识缺口提供了强有力的基础。 炎症引发的心脏损伤，这将通过本MIRA应用程序的三个不同项目进行检查：1） 内源性和外源性Sectm 1a在巨噬细胞增多症中的确切作用和机制是什么？ 急性心脏I/R？2)可以提高Mc中的Lcn 10和/或施用重组Lcn 10蛋白（rLcn 10） 驱动M β细胞成为抗炎表型以改善T2 D小鼠的心脏功能？和3）益生菌可以 开发基于细菌EV的纳米药物来调节M β功能或表型，以修复I/R或T2 D心脏？ 这项工作通过定义三种新型调节剂的作用，代表了微生物学的范式转变。 （Sectm 1a，Lcn 10和细菌EV）在调节M β功能和极化中的作用。我们将利用多种基因 小鼠模型（M β特异性转基因、全基因敲除和互交模型）和过继M β转移模型 以确定两种无菌炎症条件下的心脏结局（急性心肌I/R诱导的稳健和 慢性T2 D触发的低度炎症）。这些项目，如果完成，将大大推动该领域的M 研究，并提供新的治疗选择，以减少无菌炎症引起的心脏损伤， 提高心力衰竭患者生存率的希望。

Project Summary The heart is a unique organ from an immunological perspective, as it exhibits extremely low tolerance to damage and inflammation. Growing evidence from basic and clinical research suggests that sterile inflammation, triggered by either acute myocardial ischemia/reperfusion (I/R) or chronic metabolic disorders (i.e., type-2 diabetes), plays a critical role in the development of heart failure, a leading cause of death worldwide. Unfortunately, clinical trials attempting to modulate inflammation in heart failure have been either disappointing or inconsistent and none are yet clinically applicable. This sobering fact reinforces the urgent need to explore new mediators of cardiac inflammation and to better understand their underlying molecular/cellular mechanisms. The studies supported by NIGMS in the principal investigator’s laboratory over the past 5 years have identified several novel mediators and their associated signaling pathways to control immune dysfunction in inflammation-triggered heart injury. First, we discovered that secreted and transmembrane 1a (Sectm1a), a protein highly expressed in immune cells of myeloid lineage, is essential for macrophage (MФ) efferocytosis to clear dead cells from I/R hearts and thereby, restoring cardiac function. Second, using type-2 diabetic (T2D) mice as a chronic low-grade inflammation model, we identified that loss of lipocalin 10 (Lcn10), a poorly characterized member of the lipocalin superfamily, could cause an imbalanced MФ polarization in T2D hearts. Finally, we have made a novel finding that extracellular membrane vesicles (EVs) released by probiotic bacteria can promote MФ efferocytosis, but the underlying mechanism is unclear. Together, these diverse and compelling data provide a strong basis to address three critical knowledge gaps in the study of sterile inflammation-triggered heart injury, which will be examined by three different projects of this MIRA application: 1) what are exact roles and underlying mechanisms of endogenous and exogenous Sectm1a in MФ efferocytosis during acute cardiac I/R? 2) can elevation of Lcn10 in MФs and/or administration of recombinant Lcn10 protein (rLcn10) drive MФs to an anti-inflammatory phenotype for improving cardiac function in T2D mice? and 3) can a probiotic bacterial EV-based nano-drug be developed to modulate MФ function or phenotype for repairing I/R or T2D hearts? The proposed work represents a paradigm shift in MФ biology by defining the roles of three novel modulators (Sectm1a, Lcn10, and bacterial EVs) in the regulation of MФ function and polarization. We will utilize multiple genetic mouse models (MФ-specific transgenic, global knockout, and intercross models) and an adoptive MФ transfer model to determine cardiac outcomes in two sterile inflammation conditions (acute myocardial I/R-induced robust and chronic T2D-triggered low-grade inflammation). These projects, if completed, will significantly push the field of MФ research forward, and offer new therapeutic options for reducing sterile inflammation-caused heart injury, with the hope of improving heart failure patient survival.