Molecular mechanisms of acquired ciliary dysfunction in chronic inflammatory airway disease - PROJECT SUMMARY Loss and dysfunction of ciliated cells and expansion of mucous cells are hallmarks of the epithelial remodeling driving symptoms and disease progression in chronic inflammatory airway diseases such as cystic fibrosis, asthma, and chronic obstructive pulmonary disease. While mucous metaplasia is intensely investigated, mechanisms of ciliary dysfunction remain poorly understood and are not currently targeted by therapeutic interventions. This is a critical unmet need, as ciliated cells provide vital host defense to the lungs via mucociliary clearance. Ciliated cells are also the chief target cells for upper respiratory viruses that play a key role in pulmonary exacerbations in airway disease, thus a better understanding of ciliated cell dysfunction will have a broad impact. Epithelial remodeling, including ciliary dysfunction, is thought to arise through cycles of infection, injury, and inadequate repair under chronic inflammation. To uncover specific mechanisms, I used primary human airway epithelial cell cultures treated with IL-1beta, a dominant pro-inflammatory cytokine in a range of airway diseases. My preliminary data show that IL-1beta treatment leads to fewer ciliated cells that make short, immature, and functionally defective cilia, which suggests defects in both ciliated cell fate acquisition and motile ciliogenesis. Immunofluorescence analysis revealed a heterogenous expression of nuclear phospho-c-Jun/AP- 1 and nuclear NFkB in airway epithelial cells upon IL-1beta treatment, which raises the possibility that activation of one these pathways is responsible for specifically disrupting the ciliated lineage. Strikingly, my preliminary data show that the loss of ciliated cells by IL-1beta is rescued by concurrent treatment with a small molecule inhibitor of the Notch pathway, a critical negative regulator of ciliated cell fate. Therefore, I hypothesize that IL- 1beta signaling blocks proper ciliated cell fate acquisition and motile ciliogenesis, which promotes Human Rhinovirus C infection of the airway epithelium, but can be rescued by modulation of ciliogenic pathways. I will use human primary cultured epithelial cells, which faithfully model the in vivo mucosa and are highly amenable to the molecular, image-based, and functional investigation of ciliated cell dysfunction. In Aim 1, I will test mechanisms by which the ciliated cell fate acquisition and motile ciliogenesis pathways are disrupted downstream of IL-1beta signaling. In Aim 2, I will test if defective cilia and ciliated cells promote airway epithelial HRV-C infection and disrupt downstream immune signaling. In Aim 3, I will investigate if IL-1beta driven ciliated cell loss and ciliary dysfunction can be rescued by modulating the expression of ciliated cell fate and motile ciliogenesis regulators. These studies will improve our understanding of ciliary dysfunction, and may lead to novel therapeutic interventions that directly target epithelial remodeling in chronic lung diseases.
