Engineering the pulmonary epithelium "on a chip" to investigate immune responses to the inhaled external environmental stimuli

“在芯片上”改造肺上皮，以研究对吸入的外部环境刺激的免疫反应

• 批准号: 2366286
• 金额: --
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2366286
• 关键词: Engineering; pulmonary; epithelium; chip; investigate

According to the World Health Organisation (WHO), it was estimated that 90% of the worldwide population breathes polluted air and can contributed to 4.2 million premature deaths worldwide in 2016 (WHO, 2018). The pulmonary epithelium, being the first line of defence against the external insults, are subjected to mechanical forces and contact with the inhaled agents thus can be frequently injured (Whitsett & Alenghat, 2015). The pulmonary epithelium is well known to participate in the clearance of some foreign particles by trapping them in the mucus produced by mucous cells (mainly goblet cells) and concerted movement of mucus out of the lungs by a group of ciliated cells (Davies & Moores, 2010; Knight & Holgate, 2003). Together with the help of basal cells, the pulmonary epithelium is also able to engage in immune surveillance, initiate an innate immune response and regulate lung fluids and the proximate connective tissue (Deckers et al., 2017; Knight & Holgate, 2003; Loxham, Davies & Blume, 2014). Upon damage or stimulation, the bronchial epithelium can undergo remodelling such as goblet cell hyperplasia, mucus hypersecretion, airway thickening. In addition, an inflammatory response can be initiated by the secretion of proinflammatory cytokines, chemokines specific for innate immune cells and proteases (Knight & Holgate, 2003). In chronic respiratory diseases, chronic or repeated inflammation and chronic airway remodelling are associated with the progression of various respiratory diseases such as asthma and COPD. However, the exact physiological and pathological mechanisms induced by contact of these environmental stimuli in the context of airflow shear stress in human are largely underexplored.Due to the limitations of the available experimental models, a robust model with features mimicking the airflow in the airway lumen is required. Previously, Benam and others (2016) have developed a small airway-on-a-chip which consists of a differentiated alveoli epithelium exposed to flow of air as well as a layer of endothelium and a current of media representing the blood flow. Along with other publications by other groups (not listed here), their predominant research focuses on studying the basal side of the epithelium (e.g. interactions with endothelium to promote neutrophil adherence). But the research on the apical side of the epithelium has been largely ignored. In this project, a pulmonary bronchial epithelium-on-chip model with controlled airflow-based shear stress will be developed to assist in studying the effect of environmental stimuli on the pulmonary epithelium at the tissue level in vitro. The microfluid chip will consist of a differentiated bronchial epithelium supported on a membrane with a 'breathing' or oscillating airflow on its apical side and a media flow on the basal side (Benam et al., 2016). Once successfully established, this model can reliably examine the effect of different levels of shear stress in the airway channel and the effects of individual or combinations of inhaled environmental stimuli. This will provide novel mechanistic insights in the physiological and pathophysiological responses of the airway cells to stimuli such as pollutants. This will be assessed in terms of epithelial barrier permeability, mucus production, cilia function and immunological responses, such as receptor expression as well as cytokine and chemokine production. The design of the microfluidic chips also allows direct imaging to visualise any structural changes of the epithelium as well as real-time cytokine measurements. By closely mimicking the environment that the epithelium cells are exposed to in vivo. This micro-engineered model will hopefully reduce the use of animal models in this field, shed light into organ-level responses to environmental stimuli and contribute to our understanding of the development of chronic respiratory diseases.

据世界卫生组织（WHO）估计，全球90%的人口呼吸受污染的空气，2016年可能导致全球420万人过早死亡（WHO，2018）。肺上皮是抵抗外部侵害的第一道防线，其受到机械力并与吸入剂接触，因此可能经常受伤（惠特塞特& Alenghat，2015）。众所周知，肺上皮通过将一些外来颗粒捕获在由粘液细胞（主要是杯状细胞）产生的粘液中并通过一组纤毛细胞将粘液协同运动出肺来参与一些外来颗粒的清除（Davies & Moores，2010; Knight & Holgate，2003）。在基底细胞的帮助下，肺上皮还能够参与免疫监视，启动先天免疫应答并调节肺液和邻近结缔组织（Deckers等人，2017; Knight & Holgate，2003; Loxham，Davies & Blume，2014）。在损伤或刺激时，支气管上皮可经历重塑，例如杯状细胞增生、粘液分泌过多、气道增厚。此外，炎症反应可以通过分泌促炎细胞因子、对先天免疫细胞特异性的趋化因子和蛋白酶来引发（Knight & Holgate，2003）。在慢性呼吸道疾病中，慢性或反复炎症和慢性气道重塑与各种呼吸道疾病如哮喘和COPD的进展相关。然而，由于现有实验模型的局限性，需要一个具有模拟气道腔中气流特征的鲁棒模型来模拟人体在气流切应力作用下与这些环境刺激接触所引起的生理和病理机制。此前，Benam等人（2016年）开发了一种小型气道芯片，由暴露于气流的分化肺泡上皮以及内皮层和代表血流的介质流组成。沿着其他小组的其他出版物（此处未列出），他们的主要研究集中在研究上皮的基底侧（例如，与内皮的相互作用以促进中性粒细胞粘附）。但对上皮细胞顶侧的研究却被忽视了。在本项目中，将开发一种基于气流剪切应力的肺支气管上皮细胞芯片模型，以协助研究环境刺激对体外组织水平肺上皮细胞的影响。微流体芯片将由支撑在膜上的分化的支气管上皮组成，在其顶侧具有“呼吸”或振荡气流，在基底侧具有介质流（Benam等人，2016年）。一旦成功建立，该模型可以可靠地检查气道通道中不同水平的剪切应力的影响以及吸入环境刺激的单独或组合的影响。这将为气道细胞对污染物等刺激的生理和病理生理反应提供新的机制见解。这将根据上皮屏障渗透性、粘液产生、纤毛功能和免疫应答（如受体表达以及细胞因子和趋化因子产生）进行评估。微流控芯片的设计还允许直接成像以可视化上皮的任何结构变化以及实时细胞因子测量。通过密切模仿上皮细胞在体内暴露的环境。这种微工程模型有望减少该领域中动物模型的使用，揭示器官对环境刺激的反应，并有助于我们了解慢性呼吸道疾病的发展。