Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
Institute of Biomedical Sciences/Institute of Microbiology Paulo de Góes, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
J Allergy Clin Immunol. 2018 Feb;141(2):571-585.e7. doi: 10.1016/j.jaci.2017.07.048. Epub 2017 Sep 21.
Eosinophils mediate the immune response in different infectious conditions. The release of extracellular DNA traps (ETs) by leukocytes has been described as an innate immune response mechanism that is relevant in many disorders including fungal diseases. Different stimuli induce the release of human eosinophil ETs (EETs). Aspergillus fumigatus is an opportunistic fungus that may cause eosinophilic allergic bronchopulmonary aspergillosis (ABPA). It has been reported that eosinophils are important to the clearance of A fumigatus in infected mice lungs. However, the immunological mechanisms that underlie the molecular interactions between A fumigatus and eosinophils are poorly understood.
Here, we investigated the presence of EETs in the bronchial mucus plugs of patients with ABPA. We also determined whether A fumigatus induced the release of human eosinophil EETs in vitro.
Mucus samples of patients with ABPA were analyzed by light and confocal fluorescence microscopy. The release of EETs by human blood eosinophils was evaluated using different pharmacological tools and neutralizing antibodies by fluorescence microscopy and a fluorimetric method.
We identified abundant nuclear histone-bearing EETs in the bronchial secretions obtained from patients with ABPA. In vitro, we demonstrated that A fumigatus induces the release of EETs through a mechanism independent of reactive oxygen species but associated with eosinophil death, histone citrullination, CD11b, and the Syk tyrosine kinase pathway. EETs lack the killing or fungistatic activities against A fumigatus.
Our findings may contribute to the understanding of how eosinophils recognize and act as immune cells in response to A fumigatus, which may lead to novel insights regarding the treatment of patients with ABPA.
嗜酸性粒细胞在不同感染情况下介导免疫反应。白细胞释放细胞外 DNA 陷阱 (ETs) 已被描述为一种固有免疫反应机制，在包括真菌病在内的许多疾病中都有相关。不同的刺激会诱导人嗜酸性粒细胞 ETs (EETs) 的释放。烟曲霉是一种机会性真菌，可能导致嗜酸性粒细胞过敏性支气管肺曲霉病 (ABPA)。据报道，嗜酸性粒细胞对于感染小鼠肺部中烟曲霉的清除很重要。然而，烟曲霉与嗜酸性粒细胞之间分子相互作用的免疫机制仍知之甚少。
本研究旨在研究 ABPA 患者的支气管粘液栓中是否存在 EETs，并确定烟曲霉是否在体外诱导人嗜酸性粒细胞 EETs 的释放。
通过光镜和共聚焦荧光显微镜分析 ABPA 患者的粘液样本。通过荧光显微镜和荧光法评估不同药理学工具和中和抗体对人血嗜酸性粒细胞 EETs 释放的影响。
我们在 ABPA 患者的支气管分泌物中鉴定出大量带有核组蛋白的 EETs。体外研究表明，烟曲霉通过一种不依赖于活性氧的机制诱导 EETs 的释放，该机制与嗜酸性粒细胞死亡、组蛋白瓜氨酸化、CD11b 和 Syk 酪氨酸激酶途径有关。EETs 缺乏对烟曲霉的杀伤或抑菌活性。
本研究结果可能有助于理解嗜酸性粒细胞如何识别并作为免疫细胞对烟曲霉作出反应，这可能为 ABPA 患者的治疗提供新的见解。
