The Effect And Significance Of Montelukast On The Balance Of T Helper Cell 17/T Regulatory Cell In Asthmatic Rats

Background In recent years,it had been found that the classic T helper 1 cells (Thl)/T helper 2 cells (Th2) imbalance hypothesis was not the whole of asthma pathogenesis, and the emerging T helper 17 cells (Th17)/Regulatory T cells (Treg) imbalance may be an important supplement of it. combining with the relationship between the balance of Th17/Treg and the onset of asthma, and exploring the influence of some commonly used drugs to this balance may provide new ideas for the treatment of asthma. As an anti-allergic asthma medicine,Montelukast had been used in asthma for many years, and it had certain effects of anti-inflammatory and inhibition of airway remodeling.However,the mechanism had not been determined.Objectives To investigate the change of Thl7/Treg balance in asthmatic rats, to explore the effect and significance of montelukast on it, and to provide experimental basis for its clinic applying.Methods A total of 40 male healthy Sprauge-Dawley rats,6-8 weeks old,were randomly divided into 4 groups on average:the normal control group(group C),the asthma group(group A),the montelukast group(group M) and the dexamethasone group (group D).Each group contained 10 rats. The group A,D and M were injected the mixture of chicken ovalbumin (OVA) and Al(OH)3 for sensitization in the first day,so did the 8-th day,then the models of rat asthma were established with giving atomizing stimulation of OVA normal saline solution since 15th day,30 mintes once a day,for 8 weeks.The rats in the group M and group D were separately given montelukast or dexamethasone daily before atomizing challenged every time. The group C was used Al(OH) 3 normal saline suspension fluid.Bronchoalveolar lavage fluid(BALF) was harvested for testing the number of total cells and differential cell in each group 8 weeks later;the percentage of Thl7 cells and Treg cells in CD4+ T cells were evaluated by using flow cytometry in blood;the concentration of interleukin-17(IL-17) and IL-10 in plasma was measured by enzyme-linked immunosorbent assay;the lung tissue sections were stained with hematoxylin and eosin for pathologic changes,and parameters of air-way remodeling were determined by medical image analysis system.Results(1)The changes of general condition:Rats in the group A appeared symptoms such as tachypnea,irritability,incontinence among or after the atomizing stimulation. After repeated challenged, it showed that fur lost, depressed and responsed slowly, weight lost or growed slowly, then it prompted the model was successful. Compared with the group A,the symptom in the group M and D decreased obviously.The symptom in the group C was asymptomatic or mild.(2) The changes of Lung histopathology:rats in the group A demonstrated that inflammatory cells infiltrated around the bronchus and the vascular which were mainly lymphocytes,eosinophils,neutrophils and macrophagocytes with the bronchial spasm,epithelial shed,airway wall thickness,collagen deposition and the mucs production increased. Compared with the group A,the above-mentioned changes in the group M and D decreased obviously.These changes were not significant in group C.(3)The conditions of inflammation cells in BALF:Compared with the group C, the total celluar score in BALF,the number and percentage of polymorphonuclear neutrophils(PMN),the percentage of eosinophils(EOS), the percentage of lymphocytes(Ly) were elevated significantly in the group A,D and M(P<0.01); Compared with the group A, the total celluar score in BALF,the number and percentage of PMN,the percentage of EOS, the percentage of Ly were decreased significantly in the the group M and D (P<0.01); the total celluar score in BALF,the number and percentage of PMN,the percentage of EOS, the percentage of Ly in the group M and D had no significant difference(P>0.05).(4) The changes of the percentage of Thl7 cell and Treg cell to occupy CD4+ lymphocyte and the level of IL-17,IL-10 in serum: Compared with the group A, the percentage of Th17 cell to occupy CD4+ lymphocyte,the level of IL-17 were decreased significantly in the group C,D and M (P<0.01). Compared with the group C, the percentage of Treg cell to occupy CD4+ lymphocyte,the level of IL-10 were decreased significantly in the group D and M(P<0.01). The percentage of Thl7 and Treg cell to occupy CD4+ lymphocyte,the level of IL-17 and IL-10 in the group D and M had no significant difference(.P>0.05).(5)The parameters of airway remodeling: Compared with the group A,the Wat/Pbm and Wam/Pbm were decreased significantly in the group D and M; the Wat/Pbm and Wam/Pbm in the group D and M had no significant difference(P>0.05).(6) The results of correlation analysis: The percentage of Th17 and the level of IL-17 were positively correlated with the percentage of PMN, the percentage of EOS and the parameters of airwagy remodeling (P<0.01); The percentage of Treg and the level of IL-10 were negatively correlated with the percentage of PMN, the percentage of EOS and the parameters of airwagy remodeling (P<0.01)Conclusions(1) In asthmatic rats,there is an imbalance of Th17/Treg in which the Th17 is dominant, and this imbalance may be involved in the pathological process of airway inflammation and remodeling;(2)Montelukast makes a positive regulatory role to the imbalance of Thl7/Treg,and may reduce the airway inflammation, inhibit airway remodeling rely on this mechanism.