Effects of lysedEnterococcus faecalis FK-23 on experimental allergic rhinitis in a murine model

In the current study,we sought to investigate whether lysed Enterococcus faecalis FK-23(LFK),a heat-killed probiotic preparation,attenuated eosinophil influx into the upper airway and had immunomodulatory activity in a murine allergic rhinitis model.Eighteen BALB/c mice were divided into three groups;the ovalbumin(OVA)-sensitized/challenged group,which received saline orally for 6 weeks(OVA group),the OVA-sensitized/challenged group,which received LFK orally for 6 weeks(LFK-fed group),and the non-sensitized group,which received saline for 6 weeks(saline control group).Nasal rubbing and sneezing were monitored during the study.After the final challenge,interleukin(IL)-4,interferon(IFN)-γ,and OVA-specific IgE levels in the sera and splenocyte culture supernatants were determined,eosinophilic infiltrate into the upper airway was quantified,and splenic CD4+CD25+ regulatory T cells(Tregs) were examined by flow cytometry.We found that nasal rubbing was significantly reduced in LFK-fed mice compared to the OVA group on d 27 and 35,and sneezing was significantly inhibited by LFK administration for 35 d.LFK-fed mice had significantly less eosinophil influx into the nasal mucosa than the OVA group.There were no significant differences between the LFK-fed group and OVA group in the serum and splenocyte culture supernatant levels of IL-4,IFN-γ,and OVA-specific IgE.Interestingly,the LFK-fed mice had a significantly greater percentage of splenic CD4+CD25+ Tregs than OVA group.Our results indicate that oral administration of LFK may alleviate nasal symptoms,reduce nasal eosinophilia,and increase the percentage of CD4+CD25+ Tregs in experimental allergic rhinitis.