Proteostasis and Energetics as Proteome Hallmarks of Aging and Influenza Challenge in Pulmonary Disease

Aging is associated with an increased risk for the development of many diseases. This is exemplified by the increased incidence of lung injury, muscle dysfunction and cognitive impairment in the elderly following influenza infection. Because the infectious cycle of flu is dependent upon the properties of the host, we examined the proteomeof alveolar macrophages (AM) and type 2 cells (AT2) obtained from young (3 months) and old (18 months) naïve mice and mice exposed to influenza A. Our proteomicsdata show that there is a maladaptive collapse of the proteostasisnetwork (PN) and changes in mitochondrial pathways in the aged naïve AM and AT2 proteomes. The mitochondrial imbalance and proteostatic collapse seen in agedcells placesan excessive folding burden on these cells, which is further exacerbated following exposure to influenza A. Specifically, we see an imbalance in Hsp70 co-chaperonesinvolved in protein folding and Hsp90 co-chaperonesimportant for stress signaling pathways that are essential for cellular protection during aging. The acute challenge of influenza A infection of young and aged AM and AT2 cells reveals that age-associated changes in the chaperome affect the ability of these cells to properly manage the infection and post-infection biology, contributing to cytotoxicity. We posit that proteomicprofiling of individual cell type specific responses provides a high impact approach to pinpoint fundamental molecular relationships that may contribute to the susceptibility to aging and environmental stress, providing a platform to identify new targets for therapeutic intervention to improve resiliency in the elderly.