Effects Of Inhaled Glucocortioids On The Transcription Factor T-bet/GATA-3 Inducing Airway Remodeling In Asthma Murine Model

Objectives:Asthma is one of common diseases of respiratory system and its mechanism remains to be unclear. It is believed that asthma is related with inheritance. T helper lymphocytes differentiate into two subsests,Thl and Th2 cells,with the research in asthma, more and more evidences show imbalance of Thl/Th2 maybe contributes to asthma. The two newly found transcription factors, T-bet and GATA-3, were believed to play a key role in the course. There are low level expression of T-bet and high level expression of GATA-3 in asthma,this can deduce that T-bet and GATA-3 determine the differentiated direction of Th0 cell,and lead to the imblance of ratio and function of Th lineage.Credible evidence has confirmed that the low level T-bet mice and the high level GATA-3 mice display the similar allergy and the airway remodeling. Therefore, T-bet/ GATA-3 ratio imblanced theory is regard as one of the major cause in the airway remodeling. Airway remodeling is the course of injure and respiration on the basis of inflammation. Many factors participate airway remodeling,such as growth factors,cellular factors, inflammatory mediators and enzymes. Glucocorticoid is used to treat asthma,at the same time it can inhibit airway remodeling by many kinds of mechanisms.we examine the role of T-bet/GATA-3 ratio mRNA and protein in asthma model, then focus on the a- smooth muscle actin (α-SMA) of pulmonary branchi and type 1 collagen in the lung fibroblast (LF) which are the mainly signature index of airway remodeling. Therefore, we find the balance point of T-bet/GATA-3 ratio to reverse the imbalance of Th1/Th2 and interrupt the advancement of airway remodeling in earlier, eventually provide more effective methods for the treatment of patients. Meanwhile we examine the effects of inhaled glucocorticoid on the transcription factor T-bet/GATA-3 inducing airway remodeling in asthma murine model, and explore the intervention of glucocorticoid into molecular mechanism. It will provide further theoretical foundation in the treatment.Methods:Pathogen-free 30 rats were were divided into 3 groups: blank group,OVA group and BUD group and matched for age,sex and weight for studies.The concentration of T-bet mRNA and the GATA3 mRNA in the lung were measured by the Quantitative Real-time PCR,the T-bet and GATA3 protein were measured by western blotting. Lung fibroblast of each group were isolated as deseribed above,the expression of type 1 collagen in the LF were determined by ELISA. Theα-SMA expression level were measured by immunohistochemistry. Meanwhile, comparing the relationship among T-bet mRNA and protein/the GATA-3 mRNA and protein,α-SMA and type I collagen.Data were analysed using the Statistical Package of the SPSS 10.0, Discriptive data were given as means±SD. The relations between the variables were tested by linear correlation. The p-values are two-tailed and a p-value of less than 0.05 being considered to be significant. The p-values are two-tailed and a P-value of less than 0.01 being considered to be more significant.Results:1. The T-bet mRNA and protein expression in OVA group was significantly attenuated than those in blank group (P < 0.05);meanwhile the GATA-3 mRNA and protein expression was significantly enhanced respectively(P< 0.05);The ratio of T-bet/ GATA-3 mRNA and protein in OVA group was significantly lower than those in blank group (P < 0.05). There was no difference of T-bet mRNA and protein among BUD group and OVA group (P < 0.05), but the GATA-3 mRNA and protein expression in BUD group was significantly attenuated than those in OVA group {P < 0.05), The ratio of T-bet/ GATA-3 mRNA and protein in BUD group was signifieantly enhanced than those in OVA group (P<0.05).2. Theα-SMA expression in OVA group was signifieantly enhanced than those in blank group (P < 0.05),and it in BUD group was signifieantly attenuated than those in OVA group (P < 0.05).3. The expression of the type I collagen in LF in OVA group was signifieantly enhanced than those blank group,and it in BUD group was signifieantly attenuated than those in OVA group (P < 0.05).4. The ratio of T-bet/GATA-3 mRNA and protein has negative correlations withα-SMA and typeI collagen (P < 0.05) in OVA group.Contusions:1. In asthma model, the imbalanced T cell specific trnascription factors T-bet/ GATA-3 contributes to both high expression of GATA-3 and low expression of T-bet, and the ratios of mRNA and protein epxression of T-bet and GATA-3 were low, and the ratios may evaluate the immune disbalance of asthma objectively.2. The T-bet/ GATA-3 ratio has the negative correlations withα-SMA and type I collagen, T-bet/ GATA-3 imbalance plays a crucial role in early airway remodeling.3. Budesonide could influence the ratio of T-bet/GATA-3 by downregulating the GATA-3 mRNA experssion, so that could be to reverse the imbalance of Thl/Th2 cells. Budesonide also could downregulating theα-SMA and type I collagen experssion,so treated early with Budesonide could inhibit the airway inflammation and delay the course of airway remodeling.