Mucus hypersecretion and ciliary impairment in conducting airway may be associated with progressive alveolar injuries in patients with idiopathic pulmonary fibrosis (IPF), according to the results of a new study published in Frontiers in Cell Developmental Biology.

Scanning electron microscope analysis confirmed excessive mucus production by submucosal glands, hyperplasia of secretory cells, and reduced number of ciliated cells in the surface epithelium of IPF conducting airway.

The authors observed increased secretion of mucin 5B+ (MUC5B+) mucus in the conducting airway lumens of patients with IPF, with 93.55% of the patients showing MUC5B+ mucus plugs in alveolar regions surrounded by fibrosis.

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“Targeting secretory cells and ciliated cells might represent a promising strategy in the management of IPF, which warrants further investigations,” they said.

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Patients with IPF showed larger areas of mucus glands (MUC5B+) than control subjects. Both MUC5B and mucin 5AC (MUC5AC) were upregulated in the surface epithelium of the bronchi, proximal bronchioles, and distal bronchioles of patients with IPF when compared to control subjects.

Moreover, patients with IPF had lower amounts of CC10+ secretory cells in the surface epithelium of distal bronchioles than control subjects, but similar amounts in the bronchi and proximal bronchioles. “The major secretory cell type of CC10+MUC5B−MUC5AC− in the distal bronchioles of control subjects has been commonly replaced by MUC5B+CC10−MUC5AC− cells in honeycomb cysts of IPF patients,” the authors said.

The number of ciliated cells per 1 mm basement membrane was decreased in the surface epithelium of IPF airways, while the ciliary length of all airway compartments was increased when compared to observations from control subjects’ surface epitheliums.

The study enrolled a Chinese cohort of 31 patients with IPF (47.97±10.73 years, 25 females) and 39 control subjects (60.90±9.95 years, 27 males). About half (54.8%) of the patients with IPF were smokers, while control subjects were all nonsmokers.


Peng Y, Wang Z-N, Xu A-R, et al. Mucus hypersecretion and ciliary impairment in conducting airway contribute to alveolar mucus plugging in idiopathic pulmonary fibrosis. Front Cell Dev Biol. 2022;9. doi:10.3389/fcell.2021.810842