Low-Dose LPS Pre-Exposure Protect Asthma Model By Downregulating GITRL Through TRIF/IRF3/IFN? Pathway

PART? THE EFFECT OF DIFFERENT DOSAGE AND EXPOSURE TIME OF LPS ON ASTHMA MODELOBJECTIVE: To study the effects of different exposure time and dosage of lipopolysaccharide(LPS)in early childhood on asthma.METHODS: Balb/c mice were exposed to PBS,1ug LPS or100 ug LPS for 10 consecutive days by nasal inhalation from the 3rd day or2 nd week after birth.On the 6th week,asthma model was established to detect airway hyperresponsiveness,lung tissue pathological changes,the total number of cells and cell classification count in bronchoalveolar lavage fluid(BALF),and the number of Treg,Th1,Th2,Th17 cells and the related cytokines.RESULTS: 1.Compared with the asthma group(PBS/OVA),the airway hyperresponsive,tracheal and perivascular inflammation,the total cells number and classification in BALF,the serum IgE level was significantly decreased in the low-dose LPS pre-exposure asthma group(3d1?g LPS/OVA).2.Compared with the PBS/OVA group,the number of Treg cells and the related cytokines levels were significantly increased in the 3d1?g LPS/OVA group;the number of Th2 and Th17 cells and the related cytokines levels were significantly reduced.CONCLUSION: Low-dose LPS pre-exposure during infancy have a protective effect on asthma model.PART?MECHANISM OF LOW-DOSE LPS PRE-EXPOSURE ON REGULATION OF GITRLOBJECTIVE: To study the effect of low-dose LPS pre-exposure on the levels of GITRL in asthma models.METHODS: In vivo and in vitro,low-dose LPS was pre-exposed before OVA induced model,and the expression level of GITRL was detected.Then GITRL was over-expressed in the low-dose LPS pre-exposed model(3d1?g LPS/OVA)in vivo to detect its effects on airway inflammation,airway hyperresponsiveness and serum IgE levels.RESULTS: 1.Compared with the PBS/OVA asthma model,GITRL and GITR was significantly dereased in the 3d1?g LPS/OVA group.Primary DC and splenic T cells were co-cultured,and results showed that low-dose LPS pre-exposure cells(LPS/OVA)expressed significantly lower GITRL compared with the OVA stimulated cells(PBS/OVA).2.After over-expression of GITRL in 3d1?g LPS/OVA mice,airway hyperresponsiveness,tracheal and perivascular inflammation,serum IgE levels was significantly increased.CONCLUSION: Low-dose LPS pre-expresure during infancy can protect asthma by reducing the level of GITRL.Part ? LOW-DOSE PRE-EXPOSURE REGULATES GITRL ON ASTHMA THROUGH THE TRIF/IRF3/IFN? PATHWAYOBJECTIVE: To study the mechanism of how low-dose LPS pre-exposure in infancy on GITRL.METHODS: 1.The primary DC and splenic T cells were co-cultured in vitro,and low-dose LPS or PBS was given before OVA stimulation to detect the level of TRIF/IRF3/IFN? signaling pathway.2.Exogenous IFN? was added to compare GITRL in the low-dose LPS pre-exposed group(LPS/OVA)with the OVA stimulated group(PBS/OVA),and GITRL expression levels were detected by flow cytometry and western blotting.RESULTS:1.In vitro,and the TRIF/IRF3/IFN? signaling pathway was inhibited in the LPS/OVA group compared with the PBS/OVA group.2.GITRL was increased and showed no difference in both the LPS/OVA and PBS/OVA group after exogenous IFN? factors were added.CONCLUSION: GITRL was decresed in low-dose LPS pre-exposure through TRIF/IRF3/IFN? signaling pathway.