Investigation On The Mechanisms Of IL-33 In Allergic Asthma Induced By The Major Group 1 Allergen From Dermatophagoides Farinae

Objective: To investigate the mechanisms of IL-33 in allergic asthma induced by the major group 1 allergen from Dermatophagoides farinae(Der f 1).Methods: Der f1 protein was initially expressed after induction with small dose of IPTG,and then expressed in large dose and purified for optimal concentration;40female BALB/c mice(SPF grade)of asthma models were induced by the Der f 1protein,and then randomized into 4 groups,namely: PBS group,asthma group(sensitized by Der f 1 allergen),SIT group(specific immunotherapy with Der f 1)and inhibitor group(n=10 for each).Mice in the asthma group,SIT group and inhibitor group were intraperitoneally administered with the dust mite extract at day 0,7 and14,and inhibitor group with PPADS.From day 21,mice in asthma group,SIT group and inhibitor group were sensitized with aerosol inhalation of the extract,and PBS group were challenged with PBS,30 min a day for consecutive 7 days.Twenty-four hour after the final challenge,mice in each group were sacrificed to collect the bronchoalveolar lavage fluid(BALF)and sera,in which the total white blood cells and eosinophils were determined.Pulmonary tissues were also obtained from each group of mice for preparing the histopathological sections.ELISA was performed to measure the levels of cytokines,including IFN-?,IL-5,IL-13 and IL-33 in the BALF,as well as serum antibodies of Ig E and Ig G2a;3)Homogenate of the lung tissues was obtained and subjected to Western blotting assay for examining the signaling pathway changes.Results: 1)SDS-PAGE and Western blot verification demonstrated that Der f 1 protein as successfully purified and expressed;2)Microscopic findings for the lung tissue sections indicated significant alleviation of the inflammation and reduced inflammatory cell infiltration in mice from the SIT and inhibitor groups compared to the asthma group.Mice in the inhibitor and SIT groups had significantly lower count of eosinophiles and levels of IL-5,IL-13 and IL-33 cytokines in the BALF than those in the asthma group(P<0.01),whereas SIT group had higher IFN-? level than the asthma group(P<0.01);3)Serum Ig E was markedly lower in SIT and inhibitor groups than that in asthma group(P<0.01),yet SIT group had significantly higher Ig G2 a level than the asthma group(P<0.01);4)Mice in the asthma group had obviously higher expression of IL-33 in the lung tissues compared to other groups.Conclusion: Der f 1 protein was successfully expressed and purified,and our experiment with this extract in mouse models suggest that IL-33 may play an important role in allergic asthma induced by Der f 1 allergen.