Effect Of Three Lactobacillus On Immunoregulation And Intestinal Flora In ?-lactoglobulin Induced Allergic Mouse Model

Allergic colitis and allergic eczema caused by food allergy seriously influence the health of infants.Some probiotics have been demonstrated the ability to regulate the host immune system balance,maintain the gut microbiota balance and alleviate the allergic symptoms.However,the underlying mechanisms were not fully understood,and different probiotics have different capacity of immunomodulatory and regulating intestinal microflora.In this study,we select three Lactobacilli to investigated their immunomodulatory properties against ?-lactoglobulin-induced allergies by in vitro and in vivo approaches.Furthermore,the influence on intestinal barrier function and intestinal microflora by the three strains were also explored.The results showed that TGF-? was significantly increased in ?-lactoglobulin-induced splenic lymphocyte model after treatment with Lactobacillus rhamnosus GG(P < 0.05)or Lactobacillus plantarum ZDY2013(P < 0.01).However,Lactobacillus plantarum WLPL04(P > 0.05)had no significant effect on the secretion of various cytokines.The results indicated that Lactobacillus rhamnosus GG and Lactobacillus plantarum ZDY2013 could regulate the immune balance in vitro.In order to further study the impact of Lactobacillus in immunomodulatory in vivo,we investigated the intervention effects of the three strains of Lactobacillus on ?-lactoglobulin allergic mouse model,and found that serum IgE levels was significantly reduced(P < 0.01)and TGF-?(P < 0.01)were increased after orally administered with Lactobacillus plantarum ZDY2013 and Lactobacillus rhamnosus GG,meanwhile IFN-? and TGF-? were increased and IL-4 secretion level(P < 0.05)was decreased after orally administered with Lactobacillus rhamnosus GG,and the level of serum IFN-? was significantly increased after orally administered with Lactobacillus plantarum WLPL04(P < 0.05).Q-PCR was used to analyse the relative expression of immunoregulatory factors in the colon tissue.The results showed that GATA-3/T-bet(Th1/Th2)(P < 0.001)was significantly reduced after the treatment by three Lactobacilli.Foxp-3/ROR-?t(Treg/Th17)was significantly increased after the treatment with Lactobacillus plantarum WLPL04 and ZDY2013(P < 0.05).At the same time,IFN-?(P < 0.05)was significantly increased after the administration with Lactobacillus plantarum ZDY2013,IFN-?(P < 0.01),IL-12(P < 0.05)and IL-10(P < 0.01)were significantly increased after oral administration with Lactobacillus rhamnosus GG,while IL-4 was decreased after oral administration with Lactobacillus rhamnosus GG(P < 0.001)and Lactobacillus plantarum WLPL04(P < 0.01).Comprehensive analysis found that three strains of lactobacillus have different immunomodulatory effects.So it was suggested that T cells were induced to differentiate into Th1 and Treg by Lactobacillus rhamnosus GG and Lactobacillus plantarum ZDY2013.The differentiation of Th2 was suppressed after oral administration with Lactobacillus plantarum WLPL04 and Lactobacillus rhamnosus GG.The immune balance of Th1/Th2 which regulating intestinal immunity can be maintained by three strains of Lactobacillus.The increase of intestinal permeability and the destrucyion of intestinal barrier function have been kown as risk factors for the development of food allergy.In this study,Quantitative real-time PCR(Q-PCR)was employed to examine the relative expression of tight junction protein in colonic of ?-lactoglobulin-induced mices.The results showed that tight junction protein(e.g.Claudin-1 and Occludin-1)was significantly increased(P < 0.001)after the treatment with Lactobacillus plantarum ZDY2013.The expression of Occludin-1 was significantly increased(P < 0.001)in Lactobacillus rhamnosus GG group.The results suggested that the administration with Lactobacillus plantarum ZDY2013 or Lactobacillus rhamnosus GG can protect the intestinal barrier function.According to the hygiene hypothesis,the occurrence of allergic disease is related to the decrease of early microbial exposure and changes of the microecological balance of the host's inteatinal tract.Therefore,the gut microbiota alteration was explored by high-throughput 16 S rRNA gene amplicon sequencing.Lactobacillus treatment did not significantly affect the intestinal microflora diversity,but changed the structure of the intestinal flora in mice.Weighted UniFrac principal coordinate analysis(PCoA)showed that Lactobacillus plantarum ZDY2013 treatment prevented the alteration in gastric microbiota of ?-lactoglobulin allergy mice.Meanwhile,the UPGMA cluster analysis also found that the cluster in the three Lactobacillus treatment group were similar to that of the blank group,and different with the ?-lactoglobulin allergy group.T.test analysis showed the bacteria abundance of Rikenella,Ruminiclostridium,Lachnospiraceae UCG-006,unidentified Rininococcaceae,unidentified Lachnospiraceae were significantly increased after treated with ?-lactoglobulin while significantly reduced after treated with the three Lactobacillus strains.In conclusion,oral administration with the three Lactobacillus could regulate the immune balance of host,which treated with Lactobacillus plantarum ZDY2013 and Lactobacillus rhamnosus GG could improve the host intestinal mucosal barrier function and inhibit allergen penetration.At the same time,Lactobacillus plantarum ZDY2013 and WLPL04 played an important role in regulating gut microbiota homeostasis in allergic mice.