A 3D-based immunofluorescence platform for characterizing COPD pathology and evaluating treatments in whole airway tissue models

Chronic obstructive pulmonary disease (COPD) is a common respiratory disease characterized by an abnormal chronic inflammatory response of the distal airways, exposed to noxious particles and fumes, such as cigarette smoke and environmental pollutants. Ongoing inflammation results over time in functional alterations of airway epithelia leading to a progressive and irreversible airflow limitation. Goblet cell hyperplasia and MUC5AC mucin overproduction are hallmark features of the lung epithelium of COPD patients. Traditionally, the assessment of MUC5AC protein produced by goblet cells is conducted using an immunohistochemical (IHC) approach. This method involves sectioning tissue into thin slices, followed by selective protein staining and image-based quantification. Although powerful, IHC is tedious, time-consuming, and requires significant expertise. To overcome these challenges and avoid potential sample damage from mechanical steps, we propose a new approach that combines 3D confocal microscopic imaging of immunofluorescent-labeled whole tissue with image analysis based on an in-house algorithm. Our results indicate that in IL-13 induced COPD models, which exhibit typical overproduction of MUC5AC by metaplastic goblet cells, Lebrikizumab, an IL-13 receptor antagonist, can block the effects of IL-13. Additionally, tissue models derived from the lower airway (MucilAir™ bronchial and SmallAir™) better replicate the hyperplasia phenotype compared to nasal tissue (MucilAir™ Nasal). The described 3D-based immunofluorescence platform could complement or replace the IHC-based approach for characterizing MUC5AC-producing goblet cells.