The Function And Regulation Mechanism Of B Cell Autophagy In Allergic Asthma

Allergic asthma is a common airway inflammatory disease.Airway allergic inflammatory response is the pathophysiologic basis of asthma.Large numbers of different types of inflammatory immune cells are recruited into pulmonary parenchyma,which produce biological molecules,such as histamine,cytokines and antibody to promote inflammatory response.Recent studies showed that SNPs of ATG5 or ATG7 were associated with human asthma.Furthermore,increased autophagosomes were observed in bronchi epithelial cells of asthma patients.Theses studies indicate that autophagy may play important roles in allergic asthma.In the project,we explored the potential roles of B cell autophagy in allergic asthma and the possible regulation mechanism.Part I The role and regulation of B cell autophagy in allergic asthmaImmune cells are important for the pathogenesis of allergic asthma.At the early stages of airway inflammation,neurophils,esophils and innate lymphocytes(ILCs)are recruited into lungs,these cells secrete pro-inflammation materials,such as prostaglandins,cytokines and chemokines,which further enhance vascular permeability and leukocytes recruitment,and promote the infiltration of macorphages,dendritic cells,T cells and B cells and the development of inflammation response.Innate cells(such as macrophages and dendritic cells)uptake and process allergic antigen,and present antigen pepetide to antigen specific T cells,which promotes T cells proliferation and cytokines production.B cells are activated after interacting with antigen and other immune cells.Activated B cells either differentiate into antibody-secreting plasma cells,or act as antigen presenting cells to activate T cells.Previous studies have demonstrated that autophagy regulates the function ofinmune cells.Autophagy sustains cell survival,promotes intracellular pathogen clear and enhances antigen processing and presentation in macrophages and dendritic cells;In lymphocytes such as T cells and B cells,autophagy regulates cell survival,development,differentiation and the formation of immunological memory.Recent studies have showed that autophagy may participate in human asthma,but the potential roles of autophagy in asthma and possible mechanism remain unclear up to date.In this part of the study,we generated asthma models with wild-type mice as well as mice with B cell conditional knockout of autophagy genes.We performed our research with immunoblot,enzyme-linked immunosorbent assay,flow cytometry,immunohistostaining,in-vitro cell co-culture,confocal microscopy and transmission electron microscopy.Our data showed that B cell autophagy was increased in pulmonary B cells of asthma mice,which indicated that B cell autophagy may involved in the pathogenesis of allergic asthma.The data also showed that autophagy-specific deletion in B cells attenuated immunophathologic symptoms of asthma mice.Furthermore,we demonstrated that IL4 was the key inducer of B cell autophagy in allergic condition.Part ? The biological functions of IL4-induced B cell autophagy and related possible mechanismPrevous studies showed that IL4 is essential for B cell functions.Briefly,IL4 promotes the survivalof B cells,enhanced MHC class? and CD23 expression on B cells,promotes class switch of Ig heavy chain in B cells.It is demonstrated that IL4 activates JAKs signalling,and further downstream pathways such as AKT signalling,PI3K class Isignalling,mTOR signalling,and promotes the transcription and translation of anti-apoptosis genes.Published studies have demonstrated that autophagy plays essential roles in B cells,autophagy regulates the transition from pro-B cells to pre-B cells,promotes Bla cell survival,modulates plasma cell differentiation,sustains humoral immunological memory,and enhances antigen processing and presentation.In the part of the study,we adopted the strategy of the combination of in-vitro experiments and in-vivo experiments as well as mouse samples and human samples.We used research techniques such as flow cytometry,co-immunoprecipitation,immunoblot and confocal microscopy.Our data showed that autophagy involved in IL4-induced anti-apoptosis effect,also autophagy participated in IL4-induced antigen processing and presentation.Furthermore,the data showed that IL4-induced autophagy depended on the activation of JAKs signalling,and IL4 promoted the formation and activation of autophagy-specific PI3-Kinase class ?.The data suggested that classical cytokines may bring out their biological effects through novel mechanisms.Moreover,these findings confirmed that the regulation of autophagy by Th2 cytokines depends on cell-type.