AGING REGULATES VIRUS-TRIGGERED ASTHMATIC AIRWAY PATHOLOGY

To understand why asthma remit with aging, we exposed mice across a range of ages to viral and allergic triggers of asthma exacerbations and inflammatory airway pathology. We found that pathology induced by Sendai virus (SeV) or influenza A virus (IAV) occurred selectively in juvenile mice in a microbiome-independent manner, while the same phenotypes induced by allergens were relatively insensitive to age. Age-specific responses to SeV included a juvenile bias towards type-2 airway inflammation that emerged early in infection and was lost with maturation. With aging, we observed progressive transcriptional changes to alveolar macrophages (AMs) including the acquisition of high-level MHC-II expression. Importantly, depleting AMs before SeV infection canceled the protective effects of maturity on post-viral airway pathology. Thus, age-related changes to the lung immune micro-environment alter host responses to viruses and may drive childhood asthma remission. Overall design: We induced asthmatic airway phenotypes in mice across a span of ages using viral and allergic triggers of inflammatory airway pathology. We compared data of airway mechanics, airway inflammation, whole lung mass cytometry, single cell RNA seq and bulk RNA extracted from mice bronchoalveolar lavage.