Distinct effects of different adjuvants in the mouse model of allergic airway inflammation

Background: Allergic asthma was typically considered as an inflammatory disease mediated by type 2 immunity. However, recent studies revealed that asthma is a complex disease displaying a variety of phenotypes and endotypes. Objective: We examined cellular phenotypes in the mouse model of allergic asthma sensitized with different adjuvants. The aim of our study was to determine immunologic cellular characteristics in mouse asthma models induced by ovalbumin (OVA) and a variety of adjuvants. Method: Mice were sensitized intraperitoneally with the admixture of OVA and various adjuvants such as Alhydrogel (alum), papain, lipopolysaccharide (LPS), or CpG, and subsequently challenged with OVA intranasally. The cells in bronchoalveolar lavage (BAL) fluid, lung, and mediastinal lymph node (mLN) were examined by flow cytometric analyses. Results: In the lung and BAL fluid, the highest eosinophil levels were observed in the alum group while the highest neutrophil levels were detected in the LPS group. Meanwhile, the LPS group exhibited the most elevated levels of both ROR gamma t(+) innate lymphoid cells (ILCs) and IL-17A(+) Th cells in the lung and mediastinal lymph node. In the lung, the number of T-bet(+) ILCs was highest in the papain group whereas the number of IFN-gamma(+) Th cells was highest in the CpG group. Conclusion: Notable variances are found in the composition of immune cells and expression of cytokines at the site of pathogenesis among the different mouse models of allergic asthma created by the sensitization with different adjuvants.