Similarities and differences in kinetic characteristics of airways inflammation, formation of inducible bronchial-associated lymphoid tissue and remodeling between young and old murine asthma surrogates induced with house dust mite.

ABSTRACT

Elderly asthmatics have higher morbidity and mortality compared with those of youngers. It has been shown that there are also some differences in clinic phenomena between young and elderly asthmatics, however, there is lack of the kinetic comparisons of the changes in the development of asthma between two populations. To better understand the specific pathophysiological manifestations in older patients with asthma, we dynamically and parallelly compared pathophysiological changes in the airways and lung tissues between young and old murine asthma surrogates based on sensitization and challenge with house dust mite (HDM). Murine models were established in young (6-8-week-old) and old (16-17-month-old) female wild-type C57BL/6 mice. Our data showed that repetitive HDM exposure induced relatively low type 2 immune responses (airway hyperresponsiveness, eosinophils recruitment, expression of type 2 cytokines, mucus secretion, serum HDM specific immunoglobulin E (IgE) and IgG) in old mice. However, the type 3 immune responses (neutrophils infiltration and IL-17A expression) were enhanced in old HDM exposed mice, which sustained longer and higher than that of young mice. Notably, the relatively weakened allergic inflammation characteristics might be associated with lower numbers of CD20+ B cells and IgE+ cells in the iBALTs in old mice compared with those in young mice. Our data suggest that aging might compromise the ability to induce type 2 immune responses, but enhance type 3 immune responses upon repetitive HDM challenge, which might cause relevant phenomena in old experimental mice and might even be applicable to elderly patients with asthma in the clinic.