Defining CAR-dependent mechanosensing in chronic lung inflammation

Chronic inflammation in the airway and active remodelling are pathological hallmarks of chronic asthma. An intact epithelial barrier is critical in maintaining normal homeostatic lung function, and disruption to cell junctions is a primary initiator of lung inflammation. The Coxsackie and Adenovirus Receptor (CAR) is a transmembrane receptor that homodimerises across cell junctions to stabilise the epithelium and is a critical mediator of epithelial responses to the aeroallergen house dust mite (HDM). Our previous data has shown that CAR plays a key role in lung epithelial homeostasis, potentially through both modulation of, and response to, the surrounding mechanical microenvironment. To study the role of CAR in mechanotransduction in a physiological context, we established primary human lung-derived ‘lumen-in’ tracheospheres embedded in collagen gels stiffened with ribose to mimic the change from homeostatic to pathological mechanical microenvironments. Our data reveals activation of CAR in the lumen of tracheospheres in stiffened microenvironments, correlating with a significant increase in nuclear YAP, and increased ACTA2 mRNA. Further analysis revealed a novel interaction between CAR and the mechanotransducer caveolin-1. Knockdown of caveolin-1 increased stress fibre formation and reduced CAR activation in response to HDM. Our data reveals CAR as a mechanoresponsive protein that mediates airway remodelling in response to biomechanical forces and allergens.