Studies Of Kechuanning Decoction On Signal Transducer And Activator Of Transcription6(STAT6) And Its Gene Expression In The Rat Model Of Asthma Induced By RSV

This article demonstrated the mechanism of kechuanning decoction on the rat model of asthma induced by RSV with experimental techniques such as molecular biology,Organization immunology and virology. The results were as follows:Objective:To Study Kechuanning Decoction on Signal Transducer and Activator of Transcription6(STAT6) and its Gene Expression in the Rat Model of Asthma Induced by RSV.Methods:The asthmatic model was established by OVA-sensitization of intraperitoneal injection and repeated inhalation of OVA combination of several times of intranasal inoculation with RSV (1.010O6PFU/ml in50ul).Asthma Symptoms were observed. The change of airway responsiveness (represented by lung resistance RL) and function of lung (represented by PEF and the ratio of FEV0.4/FVC) were determined. Lung tissue sections were stained with Hematoxylin and eosin (H&E) for general morphology. Sixty young male SD rats were randomly divided into four groups:PBS control group with twenty rats; asthma model group with twenty rats; group treated with Dexamethasone and Salbutamol with ten rats and group treated with kechuanning decoction with ten rats respectively. In the experiment, the rat asthma model was established by the ovalbumin (OVA) challenge methods and stimulated with Respiratory syncytial virus.The protein expressions of STAT6were detected by immunohistochemistry techniques; the mRNA expressions of STAT6were detected by hybridization in situ. Cells in bronchoalvoelar lavage fluid (BALF) were counted and classified. And the supernatants of the BALF were used of detection of IL-4,IL-12. The correlation analysis of IL-4,IL-12and STAT6protein and its mRNA were compared. When the model was finished, isolated the PBMC from the peripheral blood, separated CD4+T,CD8+T lymphocyte with immunomagnetic beads. The purity and activity of CD4+T and CD8+T were measured by using flow cytometry trypan-blue dye exclusion test,etc.The protein expression of STAT6were detected by fluorescence-activated cell sorting.Results:Asthma symptoms were more severe in OVA/RSV group, compared with that of OVA group. RL increased and PEF,ratio of FEV0.4/FVC decreased in OVA/RSV group compared with those of OVA group (P<0.01).The bronchoconstriction and more inflammatory cells infiltration surrounding bronchi in the OVA/RSV group were found. Marked and extensive airway goblet cell hyperplasia and mucus retention in airway lumen in the OVA/RSV group were also observed. Immunohistochemistry and in situ hybridization showed that the expression of the protein content of STAT6and its mRNA around the bronchus of asthma group was significantly higher than that of the control PBS group and the treated group with kechuanning decoction and with Dexamethasone and Salbutamol (P<0.01), the epithelial cells were the chief expression cells; the expression of the protein content of STAT6and its mRNA of the treated group with kechuanning decoction was lower than the model asthma group (P<0.01) while a little higher than that of the treated group with Dexamethasone and Salbutamol, but it was no significance in statitics (P>0.05).Total BALF cells and more eosinophils in BALF from OVA/RSV group and the treated group with kechuanning decoction and with Dexamethasone and Salbutamol than those in PBS group were found (P<0.01). Total BALF cells were decreased in BALF from the treated group with kechuanning decoction and with Dexamethasone and Salbutamol than those in the asthma model group (P<0.01), but there were no differences in statistics between the treated group with kechuanning decoction and with Dexamethasone and Salbutamol. IL-4levels in BALF from the asthma model group increased greatly compared with the PBS group while IL-12levels were decreased (P<0.01), however IL-4levels in BALF from the treated group with kechuanning decoction decreased, compared with the PBS group, there were no significances in statistics (P>0.05)meanwhile the IL-12levels from the treated group with kechuanning decoction were increased compared with the asthma model group (P<0.01).There were positive correlation between IL-4,IL-12levels and the protein and the mRNA of STAT6(r=0.941,0.703respectively P<0.01),however negative correlation between IL-4,IL-12levels and the protein and the mRNA of STAT6(r=-0.906,-0.866respectively, P<0.01).The expression of the protein and the mRNA of STAT6were increased in the asthma model group, but it decreased in the treated group with kechuanning decoction. CD4+T lymphocyte in the asthma model group were increased however the hypertention of CD8+T lymphocyte were not significant (P>0.05),the expression of the protein of STAT6in the treated group with kechuanning decoction were decreased than it in the asthma model group (P<0.01)Conclusions:Kechuanning decoction could decrease the expression of the protein and the mRNA of STAT6in the bronchus and decrease the expression of the protein of STAT6in CD4+T,CD8+T lymphocyte, thereby it could regulate the disorder of Th1/Th2, it aimed to control the asthmatic attack.