COPD lungs show an attached stratified mucus layer resembling the protective colonic mucus

Mucus accumulation is a key feature of respiratory diseases such as cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD). This is associated with goblet cell metaplasia and mucin overexpression, which can be induced by the increased activity of neutrophil elastase. The aim of the study was to characterization of mucus and epithelial cell proteomics in a porcine pancreatic elastase (PPE) mouse model of COPD/CF. The major proteins detected in mucus plugs obtained from PPE-treated mice included mucins Muc5ac and Muc5b, mucus-related proteins Clca1, Fcgbp, and Bpifb1. These proteins were upregulated in bronchoalveolar lavage (BAL) fluid and epithelial cells in mice exposed to elastase. Similar changes were found in BAL fluid of COPD patients.