Alteration Of Gut Microecology And The Mechanism Of Th9Cells In Children With Acute Stage Of Wheezing

Objective: Wheezing is a common clinical manifestations in preschoolchildren with respiratory tract infection. If children with repeatedly continuedwheezing can not get good treatment before adolescence, the risk of persistentasthma will be higher. If the frequency of repeatedly attack wheezing coulddecrease during infancy, the incidence of asthma in children would reduce.The incidence of allergic diseases and bronchial asthma have increased in rencentyears, environmental factors maybe explain the reason. This view get support of"hygiene hypothesis". The "intestinal hypothesis" is that the commensalintestinal symbiotic bacteria plays an important role in inducing immunesystem development and promoting the immune system to balance and canreduce allergic diseases and asthma in future. The Th1/Th2balance theory isthe core of the immunological mechanism, which has been acceptable byplenty of scholars. However, therapeutic approaches targeting these Th2-typemediators failed to improve asthma symptoms and impressively showed thatasthma pathogenesis cannot be reduced by TH2cell functions. However,recent studies described a new subset of CD3⁺CD4⁺T cells distinct from TH2cells. These cells were named Th9cells because they produce IL-9in largeamounts. Lessons from human and animal studies demonstrated that IL-9isimplicated in asthma, in tuberculosis and in the protection against nematodeinfections. In this study, we try to detect the number of bifidobacteria and E.coli of faece and the level of IL-9in plasma of children with acute attackwheezing.Then we analysis the relationship between the number ofbifidobacteria and E. coli of faece and the level of IL-9in plasma.Respectively, we explore the role and significance of the intestinal flora andthe Th9cell in the respects of microecology and immunology in childrenwheezing pathogenesis. So it can provide a theoretical basis for early adjustment the balance of gut microecological to stop wheezing and preventoccurrence of bronchial asthma in the future.Methods: Forty-seven children with low respiratory tract infectionsaccompanied by wheezing （A group）, forty children with low respiratory tractinfections not accompanied by wheezing （B group） and thirty healthy children（C group） were selected in the study. Selected children with general conditionssuch as gender, age, weight, feeding patterns, living region was no significantdifference.1. The copy numbers of the bifidobacteria and E. coli DNA weredetected by the way of flurogenic quantitative polymerase chain reaction（FQ-PCR） and calculate the B/E ratio.2. The percentage of CD3⁺CD4⁺T cellin PBMC of peripheral blood was detected by the way of Flow cytometry（FCM）.3. The concentrations of IL-9and TGF-β₁were detected by the way ofenzyme linked immunosorbent assay （ELISA）. The obtained data werestatistically analyzed using SPSS13.0statistical analysis software.Homogeneity of variance and normality tests for all data, statistical methodsusing two independent samples mean, linear regression analysis, P<0.05wasconsidered statistically significant.Results:1The change of intestinal flora in each group1.1The quantity of bifidobacteria and B/E in A group is lower than that in Cgroup （P<0.05）. There were not different between A and B groups in quantityof E.coli.（P>0.05）.1.2The quantity of bifidobacteria and B/E in B group is lower than that in Cgroup （P<0.05）. There were not different between B and C groups in quantityof E.coli.（P>0.05）.1.3The quantity of bifidobacteria and B/E in A group is lower than that in Bgroup （P<0.05） There were not different between A and B groups in quantityof E.coli （P>0.05）.2The change of percentage of CD3⁺CD4⁺T cell in PBMC of peripheral bloodin each group2.1The percentage of CD3⁺CD4⁺T cell in A group was respectively higher than those in C group （P<0.05）.2.2The percentage of CD3⁺CD4⁺T cell in B and C groups were not different（P>0.05）.2.3The percentage of CD3⁺CD4⁺T cell in B group was respectively higherthan those in C group （P<0.05）.3The concentrations of IL-9and TGF-β₁in plasma in each group3.1The IL-9level in plasma in A group was respectively higher than those inC group （P<0.05）. The TGF-β₁level in plasma in A group was respectivelylower than those in C group （P<0.05）.3.2The IL-9level in plasma in B and C groups were not different （P>0.05）.The TGF-β₁level in plasma in B was respectively higher than those in C group（P<0.05）.3.3The IL-9level in plasma in A group was respectively higher than those inB group （P<0.05）. The TGF-β₁level in plasma in A group was respectivelylower than those in B group （P<0.05）.3.4The correlation analysis between TGF-β₁and IL-9in plasma in childrenwith acute stage of wheezing showed, TGF-β₁was negatively correlated withIL-9in plasma in A group （r=-0.467, P<0.05）.4The correlation analysis between CD3⁺CD4⁺T cells and IL-9in childrenwith acute stage of wheezing showed, CD3⁺CD4⁺T was positively correlatedwith IL-9in A group （r=0.601, P<0.05）.5The correlation analysis between B/E and IL-9in children with wheezingattack showed, B/E was negatively correlated with IL-9in A group （r=-0.319,P<0.05）.Conclusion:1The intestinal flora of children with acute stage of wheezing diordered,manifested as reduction in the quantity of bifidobacteria and B/E. So wheezingwith acute stage can effect the intestinal microecology habitats.2The level of IL-9in plasma and the percentage of CD3⁺CD4⁺T cell inperipheral blood in children with acute stage of wheezing were increased.There were positively correlated between the level of IL-9and the percentage of CD3⁺CD4⁺T cells. Then it indirectly evidence that CD3⁺CD4⁺T cellsproduces IL-9in large quantities and named “Th9cells”. It participated in theprocess of children with acute stage of wheezing, increased mucus production,and airway remodeling.3The correlation analysis between IL-9and TGF-β₁in plasma in thechildren with acute stage of wheezing shows that immune tolerance has beenbroken and Th9cells increased in acute stage of wheezing.4The B/E was decreased and the level of IL-9and TGF-β₁wereincreased in children with acute stage of wheezing. IL-9was negativelycorrelated with B/E.It maybe that the change of intestional ecological lead toimbalance of immune tolerance, increased of Th9cells and aggravated ofclinical symptoms.5The study concluded that there are closely contact between the gutbacteria and the imblance of CD3⁺CD4⁺T cells subsets and thus will provide atheoretical basis for early application of probiotics in clinical and containmentof immune imbalance.So it can reduce the incidence of childhood asthma.