RELMalpha-expressing macrophages mediate host disease tolerance in mucosal infection

宿主对微生物病原体的最佳反应需要平衡有效的病原体杀灭 限制由病原体或宿主自身免疫反应引起的组织病理学。 这种宿主疾病耐受现象对于蠕虫感染尤其重要， 是大型寄生虫，可导致严重的组织损伤和炎症。使用鼠标 巴西尼波圆线虫（Nppostrongylus brasiliensis，Nb）钩虫感染模型，我们鉴定出抵抗素样 分子 (RELM)a 作为一种高度分泌的蛋白质，可保护宿主免受潜在致命的伤害 感染引起的肺组织损伤，以牺牲最佳钩虫杀灭为代价。我们的中央 假设 RELMa 是一种宿主疾病耐受机制，它改变了平衡 杀死蠕虫以解决炎症和组织愈合。 RELMa 由免疫表达 细胞如巨噬细胞和非免疫细胞如上皮细胞（EC）。在初步 利用骨髓嵌合体和巨噬细胞共培养物的数据，我们确定了 RELMa- 表达替代激活的巨噬细胞 (AAMac) 杀灭 Nb 的效率较低，但 相反，可以抑制肺部炎症并促进组织修复。此外，我们还生成独特的 Arginase1/RELMa AAMac 双报告基因，揭示 AAMac 异质性并暗示 RELMa AAMacs 作为一种新的伤口愈合巨噬细胞亚群。根据这些发现， 该提案的重点是将新型细胞特异性 RELMa KO/报告小鼠与功能性 共培养测定和新的 RELMa 试剂来描绘巨噬细胞中的 RELMa 功能 蠕虫相互作用和粘膜组织愈合。在目标 1 中，我们将采用细胞特异性 RELMa KO/报告小鼠和过继细胞转移以描绘源自 RELMa 的贡献 先天细胞（AAMac 或嗜酸性粒细胞）或 EC 对 Nb 的免疫和组织愈合。在目标 2 中，我们将 使用 AAMac 双报告小鼠研究 RELMa 对巨噬细胞-Nb 相互作用的调节， RELMa 融合蛋白和封闭抗体，以及优化的共培养测定。在目标 3 中，我们 将采用 3D 肺支架和 EC 气液界面与 AAMac 共培养， 间充质干细胞以确定表达 RELMa 的 AAMac 和 EC 如何与 肺基质并帮助肺组织恢复。我们期望能够更好地理解 RELMa 在蠕虫感染中的有益与致病作用可以指导治疗 增强抗蠕虫免疫力同时限制病理性炎症的策略 促进组织愈合。我们的发现为替代激活巨噬细胞提供了新的见解 生物学和巨噬细胞-基质细胞相互作用，可广泛应用于解决 粘膜组织损伤和炎症是重要的公共卫生问题。

The optimal host response to microbial pathogens requires balancing effective pathogen killing with limiting tissue pathology caused by the pathogen or by the host’s own immune response. This host disease tolerance phenomenon is especially critical in infections with helminths, which are macroparasites that can cause severe tissue damage and inflammation. Using a mouse model of hookworm infection with Nippostrongylus brasiliensis (Nb), we identify Resistin-like molecule (RELM)a as a highly secreted protein that protects the host from potentially fatal infection-induced lung tissue damage at the expense of optimal hookworm killing. Our central hypothesis is that RELMa is a host disease tolerance mechanism that shifts the balance from helminth killing to resolution of inflammation and tissue healing. RELMa is expressed by immune cells such as macrophages and non-immune cells such as epithelial cells (EC). In preliminary data utilizing bone marrow chimeras and macrophage co-cultures, we identified that RELMa- expressing alternatively activated macrophages (AAMac) are less efficient at Nb killing, but instead dampen lung inflammation and promote tissue repair. Further, we generate unique Arginase1/RELMa AAMac dual reporters, that reveal AAMac heterogeneity and implicate RELMa+ AAMacs as a new wound healing macrophage subset. Based on these findings, the focus of this proposal is to combine novel cell-specific RELMa KO/reporter mice with functional co-culture assays and new RELMa reagents to delineate RELMa function in macrophage- helminth interactions and mucosal tissue healing. In Aim 1, we will employ cell-specific RELMa KO/reporter mice and adoptive cell transfers to delineate the contribution of RELMa derived from innate cells (AAMac or eosinophils) or EC to Nb immunity and tissue healing. In Aim 2, we will investigate RELMa regulation of macrophage-Nb interaction using AAMac dual reporter mice, RELMa fusion proteins and blocking antibodies, and optimized co-culture assays. In Aim 3, we will employ 3D lung scaffold and EC air-liquid interface co-cultures with AAMacs and mesenchymal stem cells to determine how RELMa-expressing AAMacs and ECs interact with the lung stroma and aid lung tissue recovery. We anticipate that a better understanding of the beneficial versus pathogenic effects of RELMa in helminth infection could guide therapeutic strategies to enhance anti-helminth immunity while limiting pathologic inflammation and promoting tissue healing. Our findings provide new insight into alternatively activated macrophage biology and macrophage-stromal cell interactions, which could be broadly applicable to resolving mucosal tissue injury and inflammation that are of significant public health concern.