Different regulatory effect of Astragalus membranaceus and dexamethasone on imbalanced T cell-specific transcription factors T-bet and GATA-3 in asthma

Objective To investigate imbalanced T cell-specific transcription factors T-bet and GATA-3 in asthmatic rats.and to identify the difierent effects of astragalus and dexamethasone ou them.Methods Forty male SD rats were randomly divided into a control group,an asthmatic group,a dexamethasone group,and an astragalus group,and were observed the change of airway histology.Two weeks after immunization,CD4+ T cells were obtalned from singled-cell suspension of spleen(after lysis of RBCs).The concentrations of IL-4,IL-5,IFN-γ in sernm were measured by ELISA.The mRNA expressions of IL-4,IL-5,IFN-γ,T-bet and GATA-3 in the lungs and CD4+ T cells were detected by RT-PCR.and the protein expressions of T-bet and GATA-3 in the lungs and CD4+ T cells were detected by Western blot respectively.Results In the asthmatic group,the numbers of eosinophils and lymphocytes.the thicknesses of WA/Pi and ASM/Pi were(25.70±2.50)/mm2,(44.80±5.69)/mm2,(12.15±1.47)mm,(6.82±0.91)mm,and those of the control group were(2.40±1.27)/mm2,(8.90±1.97)/mm2,(6.49±1.57)mm,(2.75±0.62)mm,and thore of the dexamethasone group were(6.70±1.89)/mm2,(15.80±3.12)/mm2,(8.02±1.35)mm,(3.38±0.65)mm,and those ofthe astragalus group were(11.20±2.97)/mm2,(19.80±4.59)/mm2,(8.86±0.96)mm,(3.96±0.61)mm.There were significant differences between the asthmatic group and the control group.the asthmatic group and the dexamethasone group,and the astragalus group (P 0.05).In the astragalas group,the expressions of T-bet mRNA and protein were increased compared with those of the asthmatic group (P 0.05).In the asthmatic group,the levels of IL-4 and IL-5 mRNA,GATA-3 mRNA and protein expressions were significantly increased compared with those of the control group (P 0.05).In the control group,the ratios of protein expressions of T-bet and GATA-3 were 0.80±0.53,significantly increased compared with the asthmatic group(0.07±0.05,P 0.05).In the astragalus group,the ratios of protein expressions of T-bet and GATA-3 were 0.58±0.29,significantly increased compared with those of the asthmatic group(P 0.05).Conclusion Astragalus membranaceus treatment inhibits OVA-induced airway inflammation by modulating key master switches GATA-3 and T-bet that results in committing in T helper cell to a Th1 phenotype.Dexamethasone inhibits the asthmatic airway inflammation without lating the balance of transcription factors T-bet and GATA-3.\r\n\r\nKey words: \r\nAsthma; Transcription factors; T lymphocyte; Astragalus mernbranaceus; Dexamethasone