Department of Physiology and Biophysics, Biological Sciences Institute, Federal University of Minas Gerais, Belo Horizonte, Brazil.
Department of Biochemistry and Immunology, Biological Sciences Institute, Federal University of Minas Gerais, Belo Horizonte, Brazil.
Front Immunol. 2018 Jan 29;9:58. doi: 10.3389/fimmu.2018.00058. eCollection 2018.
Defective apoptosis of eosinophils, the main leukocyte in the pathogenesis of asthma, and delay in its removal lead to lung damage and loss of pulmonary function due to failure in the resolution of inflammation. Here, we investigated the ability of angiotensin-(1-7) [Ang-(1-7)], a pivotal peptide of the renin-angiotensin system, to promote resolution of an allergic lung inflammatory response. Balb/c mice were sensitized and challenged with ovalbumin and treated with Ang-(1-7) at the peak of the inflammatory process. Bronchoalveolar lavage (BAL) fluid and lungs were collected 24 h after treatment. Different lung lobes were processed for histology to evaluate inflammatory cell infiltration, airway and pulmonary remodeling, total collagen staining, and measurements of (i) collagen I and III mRNA expression by qRT-PCR; (ii) ERK1/2, IκB-α, and GATA3 protein levels by Western blotting; and (iii) eosinophilic peroxidase activity. Total number of inflammatory cells, proportion of apoptotic eosinophils and immunofluorescence for caspase 3 and NF-κB in leukocytes were evaluated in the BAL. Mas receptor immunostaining was evaluated in mouse and human eosinophils. Engulfment of human polimorphonuclear cells by macrophages, efferocytosis, was evaluated . Ang-(1-7) reduced eosinophils in the lung and in the BAL, increased the number of apoptotic eosinophils, shown by histology criteria and by increase in caspase 3 immunostaining. Furthermore, Ang-(1-7) decreased NF-kB immunostaining in eosinophils, reduced GATA3, ERK1/2, and IκB-α expression in the lung and decreased pulmonary remodeling and collagen deposition. Importantly, Ang-(1-7) increased efferocytosis. Our results demonstrate, for the first time, Ang-(1-7) activates events that are crucial for resolution of the inflammatory process of asthma and promotion of the return of lung homeostasis, indicating Ang-(1-7) as novel endogenous inflammation-resolving mediator.
嗜酸性粒细胞凋亡缺陷，以及其在炎症消退过程中的清除延迟，导致哮喘发病机制中的主要白细胞肺损伤和肺功能丧失。在这里，我们研究了血管紧张素-(1-7)[Ang-(1-7)]，即肾素-血管紧张素系统的关键肽，促进变应性肺炎症反应消退的能力。Balb/c 小鼠用卵清蛋白致敏和攻毒，并在炎症过程的高峰期用 Ang-(1-7)处理。在治疗后 24 小时收集支气管肺泡灌洗液（BAL）和肺。对不同的肺叶进行处理，以评估炎症细胞浸润、气道和肺重塑、总胶原染色，以及通过 qRT-PCR 测量(i)胶原 I 和 III mRNA 表达；(ii)通过 Western 印迹测量 ERK1/2、IκB-α 和 GATA3 蛋白水平；以及(iii)嗜酸性过氧化物酶活性。在 BAL 中评估总炎症细胞数、凋亡嗜酸性粒细胞的比例以及白细胞中的 caspase 3 和 NF-κB 的免疫荧光。在小鼠和人嗜酸性粒细胞中评估 Mas 受体免疫染色。评估巨噬细胞吞噬人多形核细胞的作用，即吞噬作用。Ang-(1-7)减少肺和 BAL 中的嗜酸性粒细胞，增加 caspase 3 免疫染色显示的凋亡嗜酸性粒细胞数量。此外，Ang-(1-7)减少嗜酸性粒细胞中的 NF-kB 免疫染色，降低肺和肺重塑和胶原沉积中的 GATA3、ERK1/2 和 IκB-α 表达。重要的是，Ang-(1-7)增加了吞噬作用。我们的结果首次表明，Ang-(1-7)激活了对哮喘炎症过程消退和促进肺内稳态恢复至关重要的事件，表明 Ang-(1-7)是一种新型的内源性炎症消退介质。
