Centre de recherche, Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, QC, Canada.
Rady Faculty of Health Sciences, Department of Immunology, Max Rady College of Medicine, University of Manitoba, Winnipeg, MB, Canada.
Allergy. 2018 Jan;73(1):178-186. doi: 10.1111/all.13234. Epub 2017 Jul 20.
Bronchial fibroblasts play a key role in airway remodelling in asthma. They regulate epithelial cell functions such as proliferation through growth factors, cytokines, chemokines and exosomes. The role of exosomes in the communication between epithelial cells and fibroblasts by vehiculing these mediators in asthma remains to be determined.
To evaluate the role of exosomes released by bronchial fibroblasts on epithelial cell proliferation in severe asthma.
Exosomes were obtained from culture media of primary bronchial fibroblasts and characterized using Western blot, electron microscopy and flow cytometry. Uptake profile of fluorescent-labelled exosomes in epithelial cells was assessed by flow cytometry. Exosome cytokine content was analysed by Cytokine Arrays. Bronchial epithelial cell proliferation was evaluated by BrdU incorporation test. Exosome biogenesis/release was blocked using sphingomyelinase inhibitor. Plasmid transfection was used to modulate transforming growth factor beta 2 (TGF-β2) gene expression.
We showed that bronchial fibroblasts secreted exosomes, which were internalized by bronchial epithelial cells. Exosomes of severe asthmatic subjects' fibroblasts showed a lower level of TGF-β2 and significantly increased the epithelial cell proliferation of both healthy and severe asthmatic subjects compared to healthy controls' exosomes. Overexpression of TGF-β2 in severe asthmatics' fibroblasts induced enhanced TGF-β2 in exosomes leading to a reduced proliferation of epithelial cells, whereas knockdown of TGF-β2 enhanced epithelial cell proliferation.
Our study shows that exosomes are involved in fine-tuning intercellular communication in asthma. Exosomes of severe eosinophilic asthmatics' fibroblasts can contribute to airway remodelling, at least in part, by modulating epithelial cell proliferation observed in severe asthma.
支气管成纤维细胞在哮喘的气道重塑中起着关键作用。它们通过生长因子、细胞因子、趋化因子和外泌体调节上皮细胞功能，如增殖。外泌体通过运载这些介质在哮喘中上皮细胞和成纤维细胞之间的通讯中的作用仍有待确定。
评估支气管成纤维细胞释放的外泌体对严重哮喘中上皮细胞增殖的作用。
从原代支气管成纤维细胞的培养物中获取外泌体，并通过 Western blot、电子显微镜和流式细胞术进行表征。通过流式细胞术评估荧光标记的外泌体在上皮细胞中的摄取情况。通过细胞因子阵列分析外泌体细胞因子含量。通过 BrdU 掺入试验评估支气管上皮细胞增殖。使用鞘磷脂酶抑制剂阻断外泌体的生物发生/释放。使用质粒转染来调节转化生长因子β 2（TGF-β2）基因表达。
我们表明，支气管成纤维细胞分泌的外泌体被支气管上皮细胞内化。与健康对照组的外泌体相比，严重哮喘患者成纤维细胞的外泌体显示 TGF-β2 水平较低，并且显著增加了健康和严重哮喘患者的上皮细胞增殖。严重哮喘患者成纤维细胞中 TGF-β2 的过表达诱导外泌体中 TGF-β2 的增加，导致上皮细胞增殖减少，而 TGF-β2 的敲低则增强了上皮细胞的增殖。
我们的研究表明，外泌体参与哮喘中细胞间通讯的微调。严重嗜酸性粒细胞性哮喘患者的成纤维细胞的外泌体可通过调节严重哮喘中观察到的上皮细胞增殖，至少部分参与气道重塑。
