Mechanism of CX3CR1+ macrophage-mediated resolution of eosinophilic allergic lung inflammation

标题：CX 3CR 1+巨噬细胞介导的嗜酸性变应性肺炎消退机制 摘要： 最近的研究表明，组织驻留的巨噬细胞不仅参与炎症的启动， 也可用于解决和预防局部炎症。为了精确地确定巨噬细胞的亚群 为了解决肺部炎症并深入了解其功能，我们采用了新技术， 质谱细胞术和单细胞RNA-seq（sc-RNA-seq）分析人和小鼠巨噬细胞中的 肺。我们的支持数据表明，肺泡巨噬细胞（AM）是表型多样性和高度 动态响应过敏原挑战。基于sc-RNA-seq数据，AM可以被聚类成几个 群体处于稳定状态。在这些组中，表达CX 3CR 1的AM（CX 3CR 1 + AM）的子集是 与经典的常驻AM相比， CX 3CR 1阴性。在过敏性哮喘患者和哮喘小鼠模型中，我们发现CX 3CR 1 + 通过变应原激发，BAL中AM显著增加。CX 3CR 1 + AM不仅表达 巨噬细胞，而且嗜酸性粒细胞标志物，如人Siglec-8。对CX 3CR 1的进一步研究- 报道者和Epx-cre（a.k.a. Eo-cre）报告小鼠揭示，CX 3CR 1+巨噬细胞以约100 μ g/ml的速率吞噬嗜酸性粒细胞。 稳定状态和过敏性肺部炎症。小鼠模型中CX 3CR 1+巨噬细胞的消耗导致 在稳定状态下自发组织嗜酸性粒细胞增多和变应性肺中持续组织嗜酸性粒细胞增多中 炎症基于这些数据，我们假设新募集的CX 3CR 1 + AM亚群促进了CX 3CR 1的表达。 清除组织嗜酸性粒细胞，并促进变应性肺部炎症的消退。在目标1中， 关注CX 3CR 1+巨噬细胞在变应性肺炎中的细胞动力学。关于 CX 3CR 1+介导的嗜酸性粒细胞清除的分子机制，我们检测了CX 3CR 1+介导的嗜酸性粒细胞清除的潜在配体。 CX 3CR 1-CX 3CL 1和CCL 26。我们发现CCL 26在激活CX 3CR 1+中起关键作用， 巨噬细胞，而CX 3CL 1是必不可少的。我们的sc-RNA-seq数据显示，CX 3CR 1 + AM亚群是 C1 q转录本的唯一来源--C1 q是红细胞增多症的关键分子。在体外环境中，CCL 26触发 CX 3CR 1+巨噬细胞以CX 3CR 1受体介导的方式分泌C1 q。C1 q和CCL 26 在过敏性哮喘患者中，通过过敏原激发使BAL中的该数据表明CCL 26 激活CX 3CR 1+巨噬细胞，通过C1 q分泌促进红细胞增多。在目标2中，我们将研究 CX 3CR 1+巨噬细胞通过CCL 26介导的C1 q分泌活化的详细机制。最后我们 将使用IRB批准的节段性研究方案， 用过敏原激发以评价上述提出的实验的人类相关性。的 提出的研究是基于我们强有力的支持数据，即CX 3CR 1+巨噬细胞在肿瘤中的新作用。 过敏性肺部炎症消退。这项研究将导致更好地了解决议的过程 过敏性哮喘

Title: Mechanism of CX3CR1+ macrophage-mediated resolution of eosinophilic allergic lung inflammation Abstract: Recent studies show that tissue-resident macrophages participate in not only the initiation of inflammation but also in the resolution and prevention of local inflammation. To precisely determine the subsets of macrophages engaged in resolving lung inflammation and gain insight into their functions, we adopted new techniques of mass cytometry and single-cell RNA-seq (sc-RNA-seq) to analyze human and mouse macrophages in the lung. Our supporting data showed that alveolar macrophages (AMs) are phenotypically diverse and highly dynamic in response to allergen challenge. Based on the sc-RNA-seq data, AMs can be clustered into a few groups at a steady status. Among these groups, a subset of CX3CR1-expressing AMs (CX3CR1+ AMs) are unique in terms of their phenotype and patterns of gene expression, compared to classical resident AMs which are CX3CR1 negative. In patients with allergic asthma and a mouse model of asthma, we found that CX3CR1+ AMs are markedly increased in BAL by allergen challenge. The CX3CR1+ AMs express not only the macrophage but also eosinophil markers such as human Siglec-8. Further investigation with the CX3CR1- reporter and Epx-cre (a.k.a. Eo-cre) reporter mice reveals that CX3CR1+ macrophages engulf eosinophils at a steady state and in allergic lung inflammation. Depletion of CX3CR1+ macrophages in mouse models resulted in spontaneous tissue eosinophilia at a steady status and prolonged tissue eosinophilia in allergic lung inflammation. Based on this data, we hypothesized that the newly recruited CX3CR1+ AM subset promote the clearance of tissue eosinophils and facilitates the resolution of allergic lung inflammation. In aim 1, we will focus on the cellular dynamics of CX3CR1+ macrophages in allergic lung inflammation. Regarding the molecular mechanism of CX3CR1+ mediated-eosinophil clearance, we examined the potential ligands for CX3CR1 – CX3CL1 and CCL26. We discovered that CCL26 plays a key role in activating CX3CR1+ macrophages, whereas CX3CL1 is indispensable. Our sc-RNA-seq data revealed that CX3CR1+ AM subset is the sole source of the transcript of C1q - a key molecule for efferocytosis. In in-vitro setting, CCL26 triggers CX3CR1+ macrophages to secrete C1q in a CX3CR1 receptor-mediated manner. Furthermore, C1q and CCL26 are increased in BAL by allergen challenge in patients with allergic asthma. This data suggests CCL26 activates CX3CR1+ macrophages to facilitate efferocytosis via C1q secretion. In aim 2, we will examine the detailed mechanisms of CX3CR1+ macrophage activation through CCL26-mediated C1q secretion. Finally, we will extend the study to translational human research using the IRB-approved protocol for the segmental provocation with an allergen to evaluate the human relevance of the above proposed experiments. The proposed study is based on our strong supporting data on the new roles of CX3CR1+ macrophages in the resolution of allergic lung inflammation. This study will lead to a better understanding of the resolution process of allergic asthma.