| Bronchial asthma is a chronic airway inflammation with many sorts of inflammation cells and cytokines involved. Helper T cell play a central role in the pathogenesis of allergic asthma by releasing many sorts of cytokines. The important alteration of immunology is disbalance in their functions and proportion of Thl/Th2.Synthetic oligodeoxynucleotides containing a unmethylated CpG motifs (ODN-CpG)have many immunostimulatory roles. The efect of CpG-ODN is known to induce antigen-specific Thl responses and inhibit Th2 responses. Previous studies have reported that the administration of CpG-ODN during Ag sensitization of naive mice, or before antigen challenge of sensitized mice prevented the imbalance of Th1/Th2,Th2-directed airway allergic inflammation and AHR .These studies have demonstrated an important role for CpG-ODN to prevent asthma. In this study we established a mouse model of allergic asthma,in which Balb/c mice were sensitized and subsequently challenged with OVA,to discuss possible therapeutic effects for CpG-ODN on pulmonary allergic responses administed 24h after the first antigen challenge.Materials and Methods:32 BALB/c mice were divided into 4 groups, including control group, model group,CpG-ODN-treated group and ODN-treated control group. Model group,CpG-ODN-treated group and ODN-treated control group were sensitized i.p. with 200 mg OVA on days 0,7,14 and 21and were subsequently challenged intratracheally (i.t.) with 1%OVA on days 25(the first) and 31(the second). Control group was administed i.p. with Al(OH)3 on days 0,7,14 and 21and were subsequently challenged intratracheally (i.t.) with saline on days 25(the first) and 31(the second).CpG-ODN-treated group received 100ug of CpG-ODN i.p. 24h after the first Ag challenge(day 22); ODN-treated control group received 100ug of ODN;the others received 100ul salin.Mice were killed on day 32. 1. The lungs were lavaged and BALF was collected. The total cell number, the cell ratio between EOS and total cell numbers and the number of EOS were determined. Meanwhile,the concentrations of IL-4,IL-5 and IFN-r in BALF,were measured by ELISA kit.Lungs were fixed in neutral buffered formaldehyde, and were stained with hematoxylin and eosin for evaluation of pulmonary allergic responses.2. Splenocytes were isolated and suspended in RPMI 1640 containing 10%FBS. Cells (1.0×106/ml/well) were cultured in 24-well plates added with OVA(0.2mg/ml).Supernatants were collected 48h later.INF-r and IL-4 concentrations in spleen cell culture supernatants were determined by ELISA kit according to the instructions of manufacturer.Results1,Comparing with control group, HE-stained lungs of the mice of model group and ODN-treated control group showed inflammatory cells infiltrating around the bronchus and the vascular,which were mainly Eos,Neu and Lym; the total cell number, the cell ratio between Eos and total cell numbers, and the number of Eos were significantly higher;IL-4 and IL-5 concentrations in BALF and IL-4 in spleen cell culture supernatants were significantly increased, INF-r levels of both of them were significantly decreased,indicating the imbalance of Th1/Th2. The pathological alterations and the change of the cytokine concentrations indicated We have successfully established a mice asthma model with OVA. 2,Comparing with model group and ODN-treated control group, the pathological alterations of CpG-ODN-treated group were much lighter; the total cell number, the cell ratio between Eos and total cell numbers, and the number of Eos were significantly lower; IL-4 and IL-5 concentrations in BALF and IL-4 in spleen cell culture supernatants were significantly decreased, INF-r levels of both of them were significantly increased.These indicated that the imbalance of Th1/Th2 and ongoing allergic pulmonary inflammation in CpG-ODN-treated group were inhibited.3,The amount of EOS in BALF was positive correlation with the concentrations of IL-5 in BALF.CONCLUSIONS:Administed i.p. 24h after the first antigen challeng, CpG-ODN can inhibited antigen-induced airway inflammation and the imbalance of Th1/Th2, suggesting a potential approach for the treatment of allergic asthma. |
