Abstract：
BACKGROUND: We have previously shown that asthma-like airways inflammation may be induced by topical exposure to respiratory tract pathogens such as S. pneumoniae (SP) in concert with epithelial alarmins such as IL-33. Details of the pathogenesis of this murine surrogate remain however unexplored.
METHODS: Airways inflammation was induced by repeated, intranasal exposure of Il-4-/-, Rag1-/- and Rag2-/-Il2rg-/- mice (in which B lymphocyte IgE switching, adaptive and innate immunity are respectively ablated) as well as wild type mice to inactivated SP, IL-33 or both. Airways pathological changes were analysed, and the subsets and functions of locally accumulated ILC2s investigated by single cell RNA sequencing and flow cytometry.
RESULTS: In the presence of IL-33, repeated exposure of the airways to inactivated SP caused marked eosinophil- and neutrophil-rich inflammation and local accumulation of ILC2s, which was retained in the Il-4-/- and Rag1-/- deficient mice but abolished in the Rag2-/-Il2rg-/- mice, an effect partly reversed by adoptive transfer of ILC2s. Single cell sequencing analysis of ILC2s recruited following SP and IL-33 exposure revealed a Klrg1+Ly6a+subset, expressing particularly elevated quantities of the pro-inflammatory cytokine IL-6, type 2 cytokines (IL-5 and IL-13) and MHC class II molecules, promoting type 2 inflammation as well as involved in neutrophil-mediated inflammatory responses.
CONCLUSIONS: Local accumulation of KLRG1+Ly6a+ ILC2s in the lung tissue is a critical aspect of the pathogenesis of airways eosinophilic and neutrophil-rich inflammation induced by repeated exposure to SP in the presence of the epithelial alarmin IL-33.
METHODS: Airways inflammation was induced by repeated, intranasal exposure of Il-4-/-, Rag1-/- and Rag2-/-Il2rg-/- mice (in which B lymphocyte IgE switching, adaptive and innate immunity are respectively ablated) as well as wild type mice to inactivated SP, IL-33 or both. Airways pathological changes were analysed, and the subsets and functions of locally accumulated ILC2s investigated by single cell RNA sequencing and flow cytometry.
RESULTS: In the presence of IL-33, repeated exposure of the airways to inactivated SP caused marked eosinophil- and neutrophil-rich inflammation and local accumulation of ILC2s, which was retained in the Il-4-/- and Rag1-/- deficient mice but abolished in the Rag2-/-Il2rg-/- mice, an effect partly reversed by adoptive transfer of ILC2s. Single cell sequencing analysis of ILC2s recruited following SP and IL-33 exposure revealed a Klrg1+Ly6a+subset, expressing particularly elevated quantities of the pro-inflammatory cytokine IL-6, type 2 cytokines (IL-5 and IL-13) and MHC class II molecules, promoting type 2 inflammation as well as involved in neutrophil-mediated inflammatory responses.
CONCLUSIONS: Local accumulation of KLRG1+Ly6a+ ILC2s in the lung tissue is a critical aspect of the pathogenesis of airways eosinophilic and neutrophil-rich inflammation induced by repeated exposure to SP in the presence of the epithelial alarmin IL-33.
摘要：
背景：我们以前已经表明，哮喘样气道炎症可能是通过局部暴露于呼吸道病原体如肺炎链球菌（SP）与上皮性警报如IL-33共同诱导的。然而，这种鼠替代品的发病机理的细节仍未被探索。
方法：反复诱发气道炎症，IL-4-/-鼻内暴露，Rag1-/-和Rag2-/-Il2rg-/-小鼠（其中B淋巴细胞IgE转换，适应性和先天免疫分别被消融)以及野生型小鼠对灭活的SP，IL-33或两者。分析气道病理变化，以及通过单细胞RNA测序和流式细胞术研究局部积累的ILC2s的亚群和功能。
结果：在存在IL-33的情况下，反复暴露于灭活的SP的气道引起明显的嗜酸性粒细胞和中性粒细胞丰富的炎症和ILC2s的局部积累，保留在IL-4-/-和Rag1-/-缺陷小鼠中，但在Rag2-/-Il2rg-/-小鼠中废除，ILC2的过继转移部分逆转了这种效应。SP和IL-33暴露后招募的ILC2s的单细胞测序分析显示Klrg1Ly6a子集，表达特别升高量的促炎细胞因子IL-6，2型细胞因子（IL-5和IL-13）和MHCII类分子，促进2型炎症以及参与中性粒细胞介导的炎症反应。
结论：KLRG1+Ly6a+ILC2s在肺组织中的局部积累是在上皮alarminIL-33存在下反复暴露于SP诱导的气道嗜酸性粒细胞和富含中性粒细胞炎症的发病机理的一个关键方面。
方法：反复诱发气道炎症，IL-4-/-鼻内暴露，Rag1-/-和Rag2-/-Il2rg-/-小鼠（其中B淋巴细胞IgE转换，适应性和先天免疫分别被消融)以及野生型小鼠对灭活的SP，IL-33或两者。分析气道病理变化，以及通过单细胞RNA测序和流式细胞术研究局部积累的ILC2s的亚群和功能。
结果：在存在IL-33的情况下，反复暴露于灭活的SP的气道引起明显的嗜酸性粒细胞和中性粒细胞丰富的炎症和ILC2s的局部积累，保留在IL-4-/-和Rag1-/-缺陷小鼠中，但在Rag2-/-Il2rg-/-小鼠中废除，ILC2的过继转移部分逆转了这种效应。SP和IL-33暴露后招募的ILC2s的单细胞测序分析显示Klrg1Ly6a子集，表达特别升高量的促炎细胞因子IL-6，2型细胞因子（IL-5和IL-13）和MHCII类分子，促进2型炎症以及参与中性粒细胞介导的炎症反应。
结论：KLRG1+Ly6a+ILC2s在肺组织中的局部积累是在上皮alarminIL-33存在下反复暴露于SP诱导的气道嗜酸性粒细胞和富含中性粒细胞炎症的发病机理的一个关键方面。
