Bcg-psn Down-regulates Il-17 Of Cd4~+t Lymphocytes In Mice With Acute Asthma.

Background:The bronchial asthma is a chronic airway inflammatory disease in which eosinophils, mast cells and T lymphocytes and other inflammatory cells and cellular element play a role. Study confirmed that the incidence of bronchial asthma and the Th1/Th2 imbalance are closely related,But recently it has been suggested that TH17(IL 17) and its cytokines are involed in the pathogenesis of asthma in mouse model [1].BCG-polysaccharide-nucleie acid (BCG-PSN) as a non-specific immune response modifier, can suppress Th2 immune response and induce Thl immune response, reduce airway inflammatory response.. But it hasn't been reported that whether BCG-PSN can down regulates IL-17 to alleviate airway inflammation so far.Objectives:To evaluate the down regulating effect of BCG-PSN and dexamethasone (DXM) on IL 17 isolated from C.D4+T-lymphocytes from animal model of asthma.Methods:10 SPF female BALB/c mice were randomly divided into non-asthmatic group and asthmatic group. The asthmatic model was reproduced by sensitization with intraperitoneal injection of OVA, followed by repeated inhalation of OVA. The non-asthmatic group received only PBS in the same manner. After 24 hours of the last inhalation, asthmatic symptoms were observed. The changes in airway responseveness were determined by lung resistance(RL) stimulated by acetylcholine(Ach); the white cell count, neutrophils(%), eosinophils(%), lymphocytes(%) were measured from bronchoalveolar lavage fluid (BALF); Lung tissue sections were stained for general pathology. Spleenic mononuclear cells from acute asthmatic mouse model were removed red blood cells, followed by being isolated CD4+T cells using immuno-magnetic beads. Spleenic CD4+T cells were cultivated in RPMI-1640 with 10%Fetal Bovine Serum, stimulated by ConA and PMA. After 24 hours, the total spleenic CD4+T cells and ratio of positive Thl7 cells were detected; the levels of IL-17 concentration obtained from BALF and spleenic CD4+T culture supernatant were examined. IL-17 protein and IL-17 mRNA isolated by Western Blot (WB) and real-time Polymerase Chain Reaction. Asthmatic group was further divided into asthmatic control group (Con), asthmatic BCG-PSN group(ABCG) and asthmatic dexamethasone group (Adex). IL-17 protein and IL-17 mRNA isolated 24 hours after the addition of BCG-PSN and dexamethasone by Western Blot (WB) and Real-time Polymerase Chain Reaction (RT-PCR) from all the groups and analyzed.Results:(1) Asthmatic symptoms were more severe in asthmatic group as compared with controls;(2) Total Lung Resistance was obviously increased in asthmatic group as compared with controls (p<0.01);(3) More extensive inflammatory cells infiltrated around the bronchi and mucus deposition in airway lumen were found in asthmatic group as compared with controls (p<0.01);(4) White cell count, Neu(%), Eos (%) and Lym(%) in the BALF of asthmatic group were obviously increased in sthmatic group as compared with controls (respectively p<0.01);(5) IL-17 concentration in BALF was obviously increased in non-asthmatic group as compared with controls (p<0.01);(6) IL-17 concentration in BALF form asthmatic group positively correlated with Neu(%) (r=0.903,P<0.01);(7) Spleenic CD4+T cell count and the ratio of positive Th17 cells were obviously increased in asthmatic group as compared with controls (p<0.01);(8) IL-17 concentration were significantly elevated in BALF and spleenic CD4+T culture supernatant from asthmmtic group as compared with controls (respectively p<0.01);(9) The expression of IL-17 protein and IL-17 mRNA were higher (p<0.01) in spleenic CD4+T culture from asthmatic control group as compared to non-asthmatic (Con) group (respectively p<0.01). The expression of IL-17 protein and IL-17 mRNA were lower (p<0.01) in spleenic CD4+T culture from asthmatic BCG-PSN group and asthmatic dexamethasone group as compared to asthmatic control group (respectively p<0.01).but there was no significant diffence between the former (P>0.05)Conclusions(1).Acute asthmatic mouse model reproduces successfully according to modified evaluation criteria;(2).BCG-PSN and dexamethasone down-regulate IL-17 of CD4+T lymphocytes origining from spleen in mice with acute asthma.