Alterations in antibacterial peptide function, as well as the increased mucin expression and secretion (MUC 5AC and MUC 5B), are important biochemical factors responsible for the propensity for infection in CF airways.
In contrast, MUC5B D-domains were modified by neutrophil elastase, a protease commonly found in CF sputum, demonstrating that proteolytic degradation of MUC5B is an extracellular event in CF sputum.
Quantitative proteomics of BAL from CF and non-CF pairs demonstrated a mucoinflammatory signature in the CF lung dominated by Muc5B and neutrophil chemoattractants and products.
The authors demonstrated that IL-1α and IL-1β stimulated non-CF human bronchial epithelial (HBE) cells to upregulate and secrete both MUC5B and MUC5AC in a dose-dependent manner, an effect that was neutralized by the inhibition of the IL-1α/IL-1β receptor (IL-1R1).
We compared expression levels of three mucin genes, MUC1, MUC2, and MUC5/5AC, known to be expressed in the respiratory tract of CF, allergic rhinitis, and normal individuals.
In addition, while the number of goblet cells expressing MUC5AC was similar in CF and non-CF regenerated epithelia, the number of MUC5B-immunopositive goblet cells was lower in CF grafts.