Impact Of Neonatal Bcg Vaccination On IL-17and IFN-Γ In Murine Asthma Model

Part one:Effect of neonatal BCG vaccination on IL-17and IFN-y in murine asthma modelObjective:To determine the effect of IFN-y and IL-17cytokines in the anti-asthma effect of neonatal BCG vaccination in mouse model of asthma, neonatal BCG vaccination on OVA sensitized and challenged mices were treated with IFN-y ab or rIL-17.Methods:(1) Neonatal BALB/c mouse were divided into5groups: control, OVA, BCG/OVA, BCG/OVA/anti-IFN-y mAb, BCG/OVA/rIL-17. On day1, mouse in the BCG group were subcutaneously injected in the back with BCG. Except the control group, the mouse of the other four groups were sensitized at4-week and6-week and undergone OVA challenge at7-week for one week.(2) Cell count in bronchoalveolar lavage fluid (BALF) and cytokines in BALF by ELISA.(3) Score inflammatory characteristics of lung sections.(4) Airway hyper-responsiveness (AHR) in24h after the last OVA challenge was detected.Results:(1) The number of total cells, eosinophils, neutrophils, lymphocytes, score inflammatory characteristics of lung sections was increased in OVA group compared with those in control group, however, all of those were decreased in BCG/OVA group.(2) The airway hyperresponsiveness of the mice vaccinated with BCG plus sensitizations, and challenges with OVA was significantly decreased.(3) The levels of IFN-y were higher in BCG/OVA group than OVA group. However, the levels of IL-17were decreased in BCG/OVA group compared with those in OVA group.(4) The number of total cells, eosinophils, neutrophils, lymphocytes, scores inflammatory characteristics of lung sections and airway hyperresponsiveness was decreased in BCG/OVA/anti-IFN-γ mAb group compared with those in BCG/OVA group.(5) The neutrophils, lymphocytes, score inflammatory characteristics of lung sections and airway hyperresponsiveness was increased in BCG/OVA/rIL-17group compared with those in BCG/OVA group.Conclusion:(1) Neonatal BCG vaccination significantly reduced airway hyperresponsiveness and inflammatory of lung via inducing IFN-y and decreasing IL-17.(2) Airway hyperresponsiveness and inflammatory of lung could not be reduced completely after BCG vaccination, which was associated with the production of IFN-y. Moreover, the airway hyperresponsiveness and inflammatory reduced further after blocked IFN-y during OVA challenge after BCG vaccinated.(2) The anti-asthma effect of neonatal BCG vaccination is abrogated by co-administration of rIL-17. Part two:Mechanism of neonatal BCG vaccination on IL-17and IFN-y in murine asthma modelObjective:To investgate the mechanism of neonatal BCG vaccination on IL-17and IFN-γ in murine asthma model, IFN-γ-/-mice and IL-17-/-mice was applied in our experiment.Methods:(1) Neonatal C57mouse were divided into8groups:control, OVA, BCG/OVA, IL-17-/-control, IL-17-/-OVA, IL-17-/-"BCG/OVA, IFN-γ-/--control, IFN-γ-/-OVA. On day1, mouse in the BCG group were subcutaneously injected in the back with BCG. Except the control group, the mouse of the other four groups were sensitized at4-week and6-week and undergone OVA challenge at7-week for one week.(2) Cell count in bronchoalveolar lavage fluid (BALF) and cytokines in BALF by ELISA.(3) Score inflammatory characteristics of lung sections.(4) Airway hyper-responsiveness (AHR) in24h after the last OVA challenge was detected.Results:(1) The number of total cells, eosinophils, neutrophils, lymphocytes, score inflammatory characteristics of lung sections was increased in OVA groups compared with those in control groups, however, all of those were decreased in BCG/OVA group.(2) The airway hyperresponsiveness of the mice vaccinated with BCG plus sensitizations, and challenges with OVA was significantly decreased.(3) The number of lymphocytes, score inflammatory characteristics of lung sections and AHR was increased in IL-17-/-OVA group compared with those in IL-17-/-control group, however, all of those were decreased in IL-17-/-BCG/OVA group. Moreover, the levels of IFN-y were decreased in IL-17-/-BCG/O VA group compared with those in IL-17-/-OVA group.(4) The number of lymphocytes, score inflammatory characteristics of lung sections and AHR was decreased in IL-17-/-OVA group compared with those in OVA group.(5) There was no significant difference in airway inflammation and airway hyperresponsiveness between IFN-γ-/-control group and IFN-γ-/-OVA group.Conclusion:(1) Neonatal BCG vaccination significantly reduced airway hyperresponsiveness and inflammatory of lung via regulating the balance of IFN-y/IL-17.(2) IFN-y was involved in the pathogenesis of asthma. Airway hyperresponsiveness and inflammatory of lung could be reduced completely after blocked IFN-y.(3) IL-17was involved in the pathogenesis of asthma.