Department of Thoracic and Cardiovascular Surgery, National Clinical Research Center for Child Health, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China.
Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States.
Front Immunol. 2021 Apr 30;12:670676. doi: 10.3389/fimmu.2021.670676. eCollection 2021.
Studies have revealed important roles for IL-17A in the development of acute lung injury (ALI) following sepsis. However, the mechanism underlying the regulation of lung IL-17A remains to be fully addressed. Recent studies suggested the effect of neuromedin U (NMU) on immune cell activation and the role of group 2 innate lymphoid cells (ILC2s) in the modulation of IL-17A production. We aimed to gain in-depth insight into the mechanism underlying sepsis-induced lung IL-17A production, particularly, the role of NMU in mediating neuronal regulation of ILC2s and IL-17A-producing γδ T cells activation in sepsis.
Wild type mice were subjected to cecal ligation and puncture (CLP) to induce sepsis with or without intraperitoneal injection of NMU. The levels of ILC2s, γδ T cells, IL-17A, NMU and NMU receptor 1 (NMUR1) in the lung were then measured. In order to determine the role of NMU signaling in ILC2 activation and the role of ILC2-released IL-9 in ILC2-γδ T cell interaction, ILC2s were sorted, and the genes of and in the ILC2s were knocked down using CRISPR/Cas9. The genetically manipulated ILC2s were then co-cultured with lung γδ T cells, and the levels of IL-17A from co-culture systems were measured.
In septic mice, the levels of NMU, IL-17A, ILC2s, and IL-17A-producing γδ T cells in the lung are significantly increased, and the expression of NMUR1 in ILC2s is increased as well. Exogenous NMU further augments these increases. The main source of IL-17A in response to CLP is γδ T cells, and lung is specifically expressed in ILC2s. co-culture of ILC2s and γδ T cells leads to increased number of γδ T cells and higher production of IL-17A from γδ T cells, and these alterations are further augmented by septic treatment and exogenous NMU. Genetic knockdown of or in ILC2s attenuated the upregulation of γδ T cells and IL-17A production.
In sepsis, NMU acting through NMUR1 in lung ILC2s initiates the ILC2 activation, which, in turn, promote IL-17A-producing γδ T cell expansion and secretion of IL-17A. ILC2-derived IL-9 plays an important role in mediating γδ T cell expansion and IL-17A production. This study explores a new mechanism underlying neuronal regulation of innate immunity in sepsis.
研究表明白细胞介素-17A（IL-17A）在脓毒症引起的急性肺损伤（ALI）发展中起着重要作用。然而，肺内 IL-17A 调节的机制仍有待充分阐明。最近的研究表明，神经肽 U（NMU）对免疫细胞激活的影响，以及 2 型固有淋巴细胞（ILC2）在调节 IL-17A 产生中的作用。我们旨在深入了解脓毒症引起的肺内 IL-17A 产生的机制，特别是 NMU 在介导神经元对 ILC2 调节以及在脓毒症中 IL-17A 产生的 γδ T 细胞激活中的作用。
野生型小鼠接受盲肠结扎和穿刺（CLP）以诱导脓毒症，并在腹腔内注射 NMU。然后测量肺内 ILC2、γδ T 细胞、IL-17A、NMU 和 NMU 受体 1（NMUR1）的水平。为了确定 NMU 信号在 ILC2 激活中的作用以及 ILC2 释放的 IL-9 在 ILC2-γδ T 细胞相互作用中的作用，我们对 ILC2 进行了分选，并使用 CRISPR/Cas9 敲低了 ILC2 中的 和 基因。然后将经过基因操作的 ILC2 与肺 γδ T 细胞共培养，并测量共培养系统中 IL-17A 的水平。
在脓毒症小鼠中，肺内的 NMU、IL-17A、ILC2 和产生 IL-17A 的 γδ T 细胞的水平显著增加，并且 ILC2 中 NMUR1 的表达也增加。外源性 NMU 进一步增强了这些增加。CLP 反应中 IL-17A 的主要来源是 γδ T 细胞，而肺 特异性表达于 ILC2。ILC2 和 γδ T 细胞的共培养导致 γδ T 细胞数量增加，γδ T 细胞产生的 IL-17A 增加，而脓毒症处理和外源性 NMU 进一步增强了这些改变。ILC2 中的 或 基因敲低减弱了 γδ T 细胞的上调和 IL-17A 的产生。
在脓毒症中，NMU 通过肺 ILC2 中的 NMUR1 启动 ILC2 激活，进而促进 IL-17A 产生的 γδ T 细胞扩增和 IL-17A 的分泌。ILC2 衍生的 IL-9 在介导 γδ T 细胞扩增和 IL-17A 产生中起重要作用。本研究探讨了脓毒症中神经元对固有免疫调节的新机制。
