Gene expression in murine alveolar macrophage: effect of aging and influenza infection

Alveolar macrophages maintain lung homeostasis and are critical for host defense to respiratory pathogens, including influenza virus. Yet how aging impacts alveolar macrophages remains unclear. Here, we found that aging reduces the proliferation and concentration of alveolar macrophages under basal conditions in mice. Transcriptomic analysis revealed that aging induces a down regulation in cell cycling pathways in alveolar macrophages. Functionally, aging impaired the capacity of alveolar macrophages to phagocytose in vivo, and also increased influenza virus-induced lung damage, morbidity and mortality. Depleting alveolar macrophages indicated that these cells were critical for accelerated mortality during influenza viral lung infection with aging. Adoptive transfer experiments demonstrated that aging impaired the ability of alveolar macrophages to reduce lung damage after influenza viral infection. Thus, our study has revealed that aging impairs alveolar macrophages to resolve damageand increases mortality after influenza viral infection. Six replicated lung alveolar macrophage samples isolated from single-cell suspension using FACS from either young or advanced-aged C57BL/6 mice lungs after intranasal challenge with influenza virus or control PBS.