Jagged2-γδT17 is Regulated by Mycobacterium Vaccae in Asthmatic Mice

Abstract

Background: Mycobacterium vaccae nebulization imparted protective effect against asthma in a mouse model. The Jagged2-γδT17 signal transduction pathway plays an important role in bronchial asthma. However, the effect of M. vaccae nebulization on the Jagged2-γδT17 signal transduction pathway in mouse models of asthma remains unclear. Methods: In total, 30 female C57 mice were randomized to normal control (group a), asthma control (group b), M. vaccae nebulization prevention,and M. vaccae nebulization treatment (group d) groups. Asthma mice models were created using ovalbumin (OVA). The Notch signaling pathway was blocked by DAPT inhibitors. Airway hyperreactivity (AHR) was measured by noninvasive lung function tests. Histopathological analyses using blue-periodic acid Schiff along with hematoxylin and eosin were performed. Immunohistochemistry, immunofluorescence, and a Western blotting assay allowed for the detection of lung protein expressions, while spleen expressions of IL-17+γδT+ cytokines were assessed with FLOW cytometry. One-way analysis of variance for within-group comparisons, the least significant difference t-test or Student-Newman-Keuls test for intergroup comparisons, and the nonparametric rank sum test for analysis of airway inflammation scores were used in the study. Results: Asthmatic mice models demonstrated downregulated Notch signaling pathway activation and decreased γδT cells and IL-17 cytokine secretion. There was also increased Jagged2 protein expression which correlated positively with γδT+IL-17+ secretion. In asthmatic mice, the expressions of Jagged2 and γδT17, along with airway inflammation and airway reactivity, were all decreased after M. vaccae exposure (p<0.05). Conclusion: The Notch signaling pathway contributed towards asthma initiation and progression by facilitating γδT cells and IL-17 cytokines production. Inhaled M. vaccae led to a significant decrease in Jagged2 and γδT17 expressions in asthmatic mice, indicating its utility in asthma prevention.