Abstract
Influenza remains a major threat to human health, especially for the elderly. Aging leads to substantial changes to lung function, gut microbiota, and white adipose tissue (WAT)-a key endocrine organ regulating energy balance and lipid metabolism. In the current study, we performed a multi-omics analysis to investigate how influenza impacts the gut-lung-adipose tissue axis differently with age at days 2, 4, 7, 14, and 28 post-infection (dpi). Compared to young-adult mice, aged mice experienced worse disease outcomes following infection, along with distinct WAT alterations, including impaired browning, heightened inflammation, and reduced innate immune cell recruitment. Age-related differences were also evidenced in infection-driven shifts in gut microbiota. Akkermansia levels rose only in young mice from 4 dpi, while Faecalibaculum and Muribaculum expanded exclusively in aged mice at 7 dpi, the only timepoint at which their abundance correlated with lung pathology. Serum metabolomics at 7 dpi also revealed age-dependent metabolic responses to infection. Compared to their non-infected counterparts, young mice had lower levels of p-Cresol-sulfate and Indoxyl-sulfate alongside higher triglycerides, whereas aged mice showed disrupted glycerophospholipid metabolism. By pinpointing specific gut bacteria as potential probiotics and identifying lipid pathways associated with disease progression, these findings could lead to the development of targeted, age-specific strategies to mitigate influenza severity in the elderly.