Effect Of Pharyngeal Microflora Disruption Caused By Antibiotics On Airway Response After RSV Infection

PART ONE EFFECT OF PHARYGEAL MICROFLORA DISRUPTION CAUSED BY ANTIBIOTICS ON AIRWAY INFLAMMATION AND HYPERRESPONSIVENESS AFTER RSV INFECTIONObject:To explore the effect of pharyngeal microfloradisruption on airway inflammation and airway hyperresponsiveness after RSV infection.Method:3-week-old female BALB/c mice were divided into4groups: Mock group, Antibiotics group, RSV group and RSV+Antibiotics group. At4d post infection (pi), mice were chosen randomly to verify RSV infection. At8d pi, PCR test was used to verify the disruption of pharyngeal microflora in mice. Counting of inflammatory cells in bronchoalveolar lavage fluid (BALF), histopathological injury and airway hyperresponsiveness (AHR) were tested at8d pi and15d pi.Result:Model in our study was built successfully. At8d pi, increase of inflammatory cells in BALF, aggravation of pulmonary injury and AHR were found in RSV group. At15d pi, airway inflammation and AHR relived compared with those at8d pi. Disruption of pharyngeal microflora cause by antibiotic treatment after RSV infection induced AHR at15d pi, but not8d pi. Only antibiotic treatment did not obviously affect airway inflammation or AHR compared with mock at these time points.Conclusion:Disruption of pharyngeal microflora caused by antibiotic treatment can induce AHR after RSV infection.PART TWO EFFECT OF PHARYNGEAL MICROFLORA DISRUPTION CAUSED BY ANTIBIOTICS ON PULMONARY TREGS AFTER RSV INFECTIONObject:To explore the effect of pharyngeal microflora disruption on pulmonary Tregs after RSV infection.Method:3-week-old female BALB/c mice were divided into4groups: Mock group, Antibiotics group, RSV group and RSV+Antibiotics group. Pulmonary Tregs responses were tested at8d pi and15d pi. IL-10and TGF-β in BALF and pulmonary Foxp3mRNA expression were investigated by ELISA and RT-PCR separately at15d pi.Result:RSV infection induced the rise of pulmonary Tregs frequency at8d pi and15d pi. Disruption of pharyngeal microflora cause by antibiotic treatment after RSV infection inhibits the increase of pulmonary Tregs frequency at15d pi. RSV infection induced the higher expression of pulmonary Foxp3mRNA at15d pi, whereas disruption of pharyngeal microflora cause by antibiotic treatment after RSV infection inhibits the expression of pulmonary Foxp3mRNA at15d pi. Increase of IL-10level in BALF could be induced after RSV infection at15d pi, and more significant Increase of IL-10level in BALF could be found in RSV+Antibiotics group. TGF-P level in BALF did not show any difference among all groups.Conclusion:RSV infection increases pulmonary Tregs, but disruption of pharyngeal microflora caused by antibiotic treatment after RSV infection inhibits the increase of pulmonary Tregs.PART THREE EFFECT OF PHARYNGEAL MICROFLORA DISRUPTION CAUSED BY ANTIBIOTICS ON PULMONARY CD11C+CELLS AFTER RSV INFECTION Object:To explore the effect of pharyngeal microfloradisruption on pulmonary CD11c+cells after RSV infection.Method:3-week-old female BALB/c mice were divided into3groups: Mock group, RSV group and RSV+Antibiotics group. Expression of MHC-II, CD80, CD86and CD40on CDllc+cells were tested by flow cytometry (FCM) at8d pi.Result:After RSV infection, frequency of MHC-Ⅱ+cells, CD80+cells, CD86+cells and CD40+cells rose at8d pi. Expression of MHC-II and CD80on single CDllc+cell also rose at8d pi. Disruption of pharyngeal microflora cause by antibiotic treatment after RSV infection induced a high frequency of MHC-Ⅱ+cells, CD80+cells, CD86+cells and CD40+cells, but inhibited the expression of MHC-II and CD80on single CD11c+cell.Conclusion:RSV infection induces the maturation of pulmonary CD11c+cells, but disruption of pharyngeal microflora caused by antibiotic treatment after RSV infection inhibits the maturation of pulmonary CD11c+cells.