Ell [31]. Considerably increased production of IL-10 was observed in mice neonatallyinfected with 108 CFU E. coli, compared to AAD model group (p,0.05 for NALF, and p,0.01 for BALF).E. coli Administration Up-regulates Production of IL-10secreting Tregs in PTLNTo better investigate whether E. coli treatment induced production of Tregs and to evaluate the role of Tregs in the suppression of AAD, we assayed the accurate percentages of CD4+CD25+Foxp3+ Tregs in PTLN at time that mice were sacrificed after 24 h of the final challenge (Fig. 8). Percentages of Tregs in CD4+ cells were comparable between AAD model group and the control group (p,0.01). Interestingly, in comparison with AAD model group, mice infected with E. coli before AAD phase possessed more significant potential for upregulation of numbers of Tregs (all p,0.01), which had a potent suppressive capacity through secretion of IL-10. Moreover, numbers of Tregs in mice neonatally infected with 108 CFU E. coli were higher than 
that in mice infected with 106 CFU or adultly infected (p,0.05). Above data indicated that certain dose- and age-sensitivity of E. coli exposure was critical for establishing adequate Tregs to regulate our immune system in terms of preventing AAD.Escherichia coli on Allergic Airway InflammationFigure 4. Eosinophil inflammation assessed on hematoxylin and eosin (HE) stained tissue sections of the nasal mucosa and lung. Original magnification was 6400 for nose and 6200 for lung (A). Numbers of eosinophils in the nasal mucosa (B) and inflammation scores of the lung (C) were counted to verify the inflammation changes among groups. Eosinophil infiltration was significantly higher in AAD model group than in the control group. Interestingly, E. coli infection before AAD phase drastically suppressed the eosinophil inflammation. In addition, numbers of eosinophils in the (108infN+OVA) group were lower than the (106infN+OVA) and (108infA+OVA) group. Data is expressed as mean 6SEM, n = 10. * p,0.05, **p,0.01 as conducted. doi:10.1371/journal.pone.0059174.gDiscussionAn increasing LED-209 web number of evidence has proclaimed that the upper and the lower ML 264 airways share most common pathologies and mechanisms [3,4]. In our study, we succeeded in developing a new mouse model of allergic airway inflammation in both the nasal mucosa and the lung induced by OVA according to previous reports with minor modification [25,26], which exhibited frequent nasal rubbing and sneezing, abundant eosinophil infiltration 15755315 and goblet cell metaplasia into the airway mucosa, excessive specific IgE levels, and Th2 skewing of the immune response. Allergic rhinitis and asthma have been increasing worldwide leading to global financial and substantial medical burdens [1?], as yet, there has still been no effective pattern of therapy so far. Nevertheless, reams of evidence currently being investigated have demonstrated that certain environmental factors could attenuate the allergic responses in allergic rhinitis and/or asthma [32]. Numbers of microorganisms that colonize on mammalian body surfaces have a highly close relationship with the immune system. The resident microbiota, such as certain bacteria, helminthes andso forth [33?6], has profoundly shaped mammalian immunity, the immunomodulatory potential of which has made them promising candidates for allergic disease therapy. More recently, there is still a gap for a body evidence to elucidate the immunomodulatory function of our main and most common gut microflor.Ell [31]. Considerably increased production of IL-10 was observed in mice neonatallyinfected with 108 CFU E. coli, compared to AAD model group (p,0.05 for NALF, and p,0.01 for BALF).E. coli Administration Up-regulates Production of IL-10secreting Tregs in PTLNTo better investigate whether E. coli treatment induced production of Tregs and to evaluate the role of Tregs in the suppression of AAD, we assayed the accurate percentages of CD4+CD25+Foxp3+ Tregs in PTLN at time that mice were sacrificed after 24 h of the final challenge (Fig. 8). Percentages of Tregs in CD4+ cells were comparable between AAD model group and the control group (p,0.01). Interestingly, in comparison with AAD model group, mice infected with E. coli before AAD phase possessed more significant potential for upregulation of numbers of Tregs (all p,0.01), which had a potent suppressive capacity through secretion of IL-10. Moreover, numbers of Tregs in mice neonatally infected with 108 CFU E. coli were higher than that in mice infected with 106 CFU or adultly infected (p,0.05). Above data indicated that certain dose- and age-sensitivity of E. coli exposure was critical for establishing adequate Tregs to regulate our immune system in terms of preventing AAD.Escherichia coli on Allergic Airway InflammationFigure 4. Eosinophil inflammation assessed on hematoxylin and eosin (HE) stained tissue sections of the nasal mucosa and lung. Original magnification was 6400 for nose and 6200 for lung (A). Numbers of eosinophils in the nasal mucosa (B) and inflammation scores of the lung (C) were counted to verify the inflammation changes among groups. Eosinophil infiltration was significantly higher in AAD model group than in the control group. Interestingly, E. coli infection before AAD phase drastically suppressed the eosinophil inflammation. In addition, numbers of eosinophils in the (108infN+OVA) group were lower than the (106infN+OVA) and (108infA+OVA) group. Data is expressed as mean 6SEM, n = 10. * p,0.05, **p,0.01 as conducted. doi:10.1371/journal.pone.0059174.gDiscussionAn increasing number of evidence has proclaimed that the upper and the lower airways share most common pathologies and mechanisms [3,4]. In our study, we succeeded in developing a new mouse model of allergic airway inflammation in both the nasal mucosa and the lung induced by OVA according to previous reports with minor modification [25,26], which exhibited frequent nasal rubbing and sneezing, abundant eosinophil infiltration 15755315 and goblet cell metaplasia into the airway mucosa, excessive specific IgE levels, and Th2 skewing of the immune response. Allergic rhinitis and asthma have been increasing worldwide leading to global financial and substantial medical burdens [1?], as yet, there has still been no effective pattern of therapy so far. Nevertheless, reams of evidence currently being investigated have demonstrated that certain environmental factors could attenuate the allergic responses in allergic rhinitis and/or asthma [32]. Numbers of 
microorganisms that colonize on mammalian body surfaces have a highly close relationship with the immune system. The resident microbiota, such as certain bacteria, helminthes andso forth [33?6], has profoundly shaped mammalian immunity, the immunomodulatory potential of which has made them promising candidates for allergic disease therapy. More recently, there is still a gap for a body evidence to elucidate the immunomodulatory function of our main and most common gut microflor.
