Anti-allergic effects of the probiotic preparations of enterococcus on experimental allergic rhinitis in mice

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The aim of this study was to investigate the anti-allergic effects of lysozyme/heat-treated Enterococcus faecalis FK-23 (LFK) and heat-treated Enterococcus faecium sp. TN-3 (TN) on experimental allergic rhinitis (AR). A total of twenty-four BALB/c mice were divided into four groups randomly: (1) positive control group, (2) LFK-fed group, (3) TN-fed group, and (4) negative control group. To establish the murine AR model, intraperitoneal injection and nasal drip with ovalbumin (OVA) were performed. Saline was used instead of OVA for negative control. Probiotic preparations of LFK and TN were orally administrated for 42 days [60 mg (0.5 ml)/d] in LFK-fed and TN-fed mice, respectively. The positive and negative control mice received saline orally for 42 days. Nasal rubbing and sneezing were monitored on d 21, d 27, and d 35. After the final challenge, mice were sacrificed on d 42, and eosinophilic infiltration into the nasal mucosa was quantified (H&E stain). IFN-gamma, IL4 and OVA-specific IgE levels in the sera and splenocyte culture supernatants were determined by ELISA kits. Nasal rubbing of LFK-fed mice was significantly reduced compared to the positive control group on day 27 (t = 2.95, P = 0.028). Both in the LFK-fed and TN-fed mice, nasal rubbing (t value was 3.75 and 3.06, P value was 0.005 and 0.011, respectively) and sneezing (t value was 2.56 and 3.35, P value was 0.038 and 0. 01, respectively) were significantly decreased compared to the positive control group on d 35. The H&E strain section of nasal tissue showed that eosinophil influx into the nasal mucosa decreased significantly both in the LFK-fed and TN-fed mice compared to the positive control group on day 42 (t value was 3.44 and 2.97, P value was 0.014 and 0.025, respectively); however, the LFK-fed mice and TN-fed mice had significant eosinophil influx into the nasal mucosa than that in the negative control group (t value was 2.54 and 3.39, P value was 0.044 and 0.015, respectively). There were no significant differences in the serum levels of IL-4 and OVA-specific IgE, as well as the levels of IFN-gamma and IL-4 in splenocyte culture supernatants between the LFK-fed group and positive control group on d 42 (all P > 0.05). Interestingly, the TN-fed mice had significantly higher serum levels of IFN-gamma compared to the LFK-fed mice [TN-fed mice: (27.07 +/- 3.83) pg/ml, LFK-fed mice: (14.83 +/- 0.99) pg/ml; Z = 2.49, P = 0.016], but not the negative control group [negative control group: (37.12 +/- 1.65) pg/ml; Z = 1.18, P = 0.343] on day 42. The serum levels of IL-4 were significantly lower in the TN-fed mice than those in the positive control group [TN-fed mice: (34.48 +/- 7.53) pg/ml, positive control group: (58.68 +/- 6.59) pg/ml; Z = 2.11, P = 0.035]; however, the levels were significantly higher in the TN-fed mice than those in the negative control group [negative control group: (20.22 +/- 1.75) pg/ml; Z = 2. 31, P = 0.021]. The TN-fed mice had significantly higher levels of IFN-gamma in splenocyte culture supernatants compared to the LFK-fed mice (Z = 2.72, P = 0.03) and the positive control group (Z = 2.30, P = 0.029), whilst the splenocyte culture supernatant levels of IL-4 (Z = 2.12, P = 0.034) and the serum levels of OVA-specific IgE (Z = 2.31, P = 0.021) were significantly lower in the TN-fed mice compared to the positive control mice. It is suggested that oral administration of probiotic LFK or TN may alleviate nasal symptoms and reduce nasal eosinophilia in the murine AR model. TN supplementation has obviously regulatory effects on the cytokine levels of IFN-gamma and IL-4, and significantly inhibitory effects on antigen-specific IgE levels.