Table 1.

Aging of the Lung

Lung functions that are changed with age	Reference
↓ Mucociliary escalator: reduced ability to clear microbes and debris from the airway	9,10
↑ Expression of proteins associated with bacteria attachment and infiltration in the pulmonary epithelial cells, including polymeric immunoglobulin receptor and platelet-activating factor receptor	11,12
↑ Expression of markers of cellular senescence	6,13
↓ Epithelial expression of anti-microbial peptides	14,15
↑ Levels of complement and surfactant proteins	15
↑ Proteostasis (and the loss of ability of cells from the aged to properly control protein abundance, proper folding and degradation)	16, 17
↑ Susceptibility to pulmonary infections	11,12,18–23
Dysbiosis (or the imbalance) of the pulmonary microbiome in the absence of infection and after infection	24–29