| Part 1.Studies of the effects of antibiotics use on Thl/Th2 balance in rats' early lifeObjective:To study the effects of antibiotics use at different days in rat's early life on Thl/Th2 balance.Methods:24 new-born SD rats were randomly divided into 3 groups,the second day after birthantibiotic group(2dCef,n = 8),the seventh day afer birth antibiotic group(7dCef,n =8),control group(Control,n=8).According to the tag days,the antibiotic group intraperitoneal injected with Cefotaxime sodium(0.33 mg/g,bid)for 3 days,the control group injected with the same volume of PBS at same time.The total cell count in BALF was determined using a hemacytometer and the cell population was distinguished using cytospin preparations,stained with the Wright-Giemsa method,and inflammatory cells infiltration was observed by histologic detection.The levels of interleukin-12(IL-12),interferon-y(IFN-y),IL-4,IL-5 of BALF and blood were detected by enzyme-linked immunosorbent assay(ELISA).IL-12p40 mRNA,IFN-? mRNA,IL-4 mRNA,IL-5 mRNA expressions of lung tissue were detected by quantitative real-time PCR.Expressions of CD4+IFN-?+Thl and CD4+IL-4+Th2 of spleencytes were detected by flow cytometry.Results:1.After three days antibiotic injection,all rats become depressed,and diarrhead.Weight gain in 2dCef and 7dCef group both more slowly than control group(P<0.05).2.No pathologic changes were found in three groups.There was no inflammatory infiltration in the lung tissues in three groups.3.The numbers of total cells,neutrophils,and lymphocyte in 2dCef was significantly higher than those in control group(P<0.05),but no significant difference found in 7dCef(P>0.05).No macrophages and eosinophils were found.4.The Th1 cytokines:the IL-12 level in BALF and serum,mRNA expression in lung tissue of two antibiotic groups were lower than those in control group(P<0.05),espicailly obvious in 2dCef(P<0.05);the IFN-y levels of BALF expression in lung tissue of two antibiotic groups was lower than those in control group(P<0.05),espicailly obvious in 2dCef(P<0.05).But there were no significant difference in the INF-y level in serum and mRNA expression in lung tissue(P>0.05).The Th2 cytokines:the IL-4 levels of BALF and serum,mRNA expression in lung tissue of two antibiotic groups were higher than those in control group(P<0.05),espicailly obvious in 2dCef(P<0.05).The IL-5 mRNA expression levels of BALF and serum,mRNA expression in lung tissue of three groups showed no significant difference(P>0.05).5.There were no statistical significance in CD4+IFN-y+Thl,CD4+IL-4+Th2 expression of spleencytes among diffrent groups(P>0.05).Conclusion:1.Antibiotics use in early life could affect the rats weight growth.2.Antibiotics use in early life could surppress inflammatory cell infiltration in lung tissue but no airway inflammation response.3.Antibiotic used in early life could inhibit the expression of Thl cytokines(IL-12)and promote the expression of Th2 cytonkines(IL-4).Part 2.Studies of the effects of antibiotics use on Thl/Th2 balance in early life of sensitized ratsObjective:To analyze the Thl/Th2 imbalance of the early life antibiotics use in rats exposured to allergens in the futureMethods:24 new-born SD rats were randomly divided into 3 groups,the second day after birth antibiotic sensitized group(2dCef+OVA,n = 8),the seventh day afer birth antibiotic sensitized group(7dCef+OVA,n = 8),only OVA sensitized group(OVA,n=8),inject antibiotics in the same way as the part one.At the 21 and 28 day afer birth all groups were sensitized OVA.Results:1.No pathologic changes were found in three groups.There were no inflammatory infiltrations in the lung tissues in three groups.2.The numbers of total cells,neutrophils,and lymphocyte expression in 2dCef+OVA were significantly higher than those in control group(P<0.05),but there was no significant difference between 7dCef +OVA and OVA(P>0.05).No macrophages and eosinophils were found.3.The Th1 cytokines:the IL-12 levels of BALF,serum and mRNA expression in lung tissue of 2dCef+OVA and 7dCef+OVA were lower than those in OVA group(P<0.05),espicailly obvious in 2dCef+OVA(P<0.05).There were no significant difference in the IFN-y level in BALF,serum and mRNA expression in lung tissue among different groups(P>0.05).The Th2 cytokines:The IL-4 levels of BALF,serum and mRNA expression in lung tissue of two antibiotic groups were higher than those in control group(P<0.05),espicailly obvious in 2dCef(P<0.05).The IL-5 levels of BALF,serum and mRNA expression in lung tissue of three groups showed no significant difference(P>0.05).4.For CD4+IFN-?+ Th1,CD4+IL-4+ Th2 expression of spleencytes there were no statistical significance among diffrent groups(P>0.05).Conclusion:Antibiotics use in early life can not aggravate the imbalance of Thl/Th2 immune response in sensitizated rats. |
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