| Allergic asthma is a bronchial disease which is characterized of a chronic inflammatory process in the airway of asthmatic individuals, and which is led by the immunologic response. Airway inflammation in asthma is associated with the local activation of T cells in the airway mucosa.In allergic asthma these activated T cells are predominantly of the T-helper 2 (Th2) cytokine phenotype. In recent years researches found a large number of DCs are present in the airways of asthmatic individuals , which are thought to play a leading role in the local T-cell activation observed in asthmatic individuals . they can convert locally deposited antigens into signals for local T-cell activation. For these functions, DC residing in nonlymphoid tissues need to be activated to initiate the differentiation process. DC maturation is characterized by profound changes in MHC class II distribution, antigen-processing capacity, and expression of costimulatory molecules, and by a marked rearrangement of adhesion molecules that is likely to allow DC migration to lymphoid organs. DC maturation is probably controlled by micro environmental signals. However, little is known about the factors and mechanisms regulating DC cell cycle, life span, and functional activity. Cytokines , chemotactic factors and chemistry mediators control DC movement, survival, and APC activity, but the fine biochemical mechanisms underlying these effects are unknown. Therefore, to thoroughly explore the role of Th1/Th2 cytokines and 1,25-Dihydroxyvitamin D3 for dendritic cells and in asthmatic airway inflammtion is of great significance to further elucidate the pathological mechanism of allergic asthma. In the first part of this study, the first step is to in vitro amplify dendritic cells from mouse bone marrow in the presence of GM-CSF and then to identify it with morphological changes and immunological phenotypes. Morphological changes are observed by scanning electronic microscope and surface molecules ,including CD11C?CD80?MHC Ⅱwere detected by FACS. Next, DC culture with different dose of IL-4 and IFN-γrespectively for 48 hours . Surface molecule ,including CD11C?CD80?MHC Ⅱwere detected by FACS. Thirdly , DCs stimulated by 80ng IL-4 or IFN-γculture with T cells isolated from spleen of ovalbumin-sensitized and challenged mouse plus 10ug/ml ovalbumin.Supernatant is collected and secretion of cytokines from activiated T cells and DCs ,such as IL-4, IFN-γand IL12 were detected by ELISA. The results demonstrate that typical immature dendritic cell can be obtained by above method and that.DCs surface molecular ,including CD80?MHC Ⅱsignificantly increased after IL-4 or IFN-γstimulation, and that secretion of IL-4 significantly increased, whereas IFN-γand IL12 significantly decreased in IL-4 stimulation group,and that secretion of IL-4, IFN-γand IL12 significantly increase in IFN-γstimulation group.Our present results suggested ①IL-4 and IFN-γcan activate DCs ,improve DCs maturation . ②DCs activated by IL-4 mostly prime type 2 T cell response ,whereas DCs activated by IFN-γprime type 1 and type 2 T cell response . Besides, DCs amplify as above protocol with or without 1,25-Dihydroxyvitamin D3 at the beginning of culture.At 10 days ,DCs was collected and its surface molecule, including CD11C?CD80?MHC Ⅱwere detected by FACS, and secretion of cytokines by DCs ,such as IL10 and IL12 was detected by ELISA. Through present study ,we found following results:in the treatment with 1,25-Dihydroxyvitamin D3 of dendritic cell group, surface molecules , CD80 and MHC Ⅱexpress significantly decreased and secrete of cytokines IL-10 significantly increased whereas IL-12 significantly decreased. Above results suggested that the express of surface molecules, CD80 and MHC Ⅱ,were inhibited by1, 25-Dihydroxyvitamin D3. The second part of this study was emphasized on the effects of dendritic cells treated with IL-4,or IFN-γor 1,25-Dihydroxyvitamin D3 in asthmatic airway inflammation .These treated DCs suspension, corresponding to 1 x 106 cells, was administered intratracheally through the opening vocal cords using a 23-gauge metal catheter connected to the outlet of a micropipette . The mouse was challenged with OVA for 30 min in future 6 days. Through present study ,we found following results :typical asthmatic pathological changes were seen in the lung tissue of IL-4 treatment group and IFN-γtreatment group,but in 1,25-Dihydroxyvitamin D3 treatment group were not seen. In BALF, the number of eosinohpils significantly increased in IL-4 treatment group and IFN-γtreatment group, whereas the number of eosinohpils in 1,25-Dihydroxyvitamin D3 treatment group is similarto blank control group. Above results suggested that ①treatment of dendritic cells with IL-4 or IFN-γiuduce immune respose, resulting in onset of asthma. ②treatment of dendritic cell with 1,25-Dihydroxyvitamin D3 induce immune tolerance, avoiding onset of asthma is related to increase of IL10 secretion and decrease of IL12 secretion . In summary,through present study ,we concluded ①IL-4 involve in development of asthamatic airway inflammation,via improving DC maturation and inducing Th2 immunity, ②IFN-γhas a role in DCs maturation, which is dose-dependent. IFN-γtreared with 1,25-Dihydroxyvitamin D3 not only prime Th1 immunity, but also Th2 immunity, and induce asthmatic airway inflammation, which suggest that IFN-γhas a complex role in asthma,③adoptive transfer of DCs treated with 1,25-Dihydroxyvitamin D3 into OVA-sensitized mouse can induce antigen-specific immune tolerance,avoiding onset of asthmatic airway inflammation, ④DCs play a key role in the induction of antigen-specific immune tolerance in asthma. Therapeutic strategies aimed at targeting DCs to change immune responses to allergens from allergic to tolerogenic may be a new method of asthma therapy.
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