Limosilactobacillus Reuteri FN041 Prevents Eczema In Mice By Regulating Ileal Flora And Inducing Immune Tolerance

ObjectiveLimosilactobacillus reuteri FN041 is a potential probiotic bacterium isolated from breast milk in traditional farming and pastoral areas of China.The aim of this study was to investigate the optimal intervention mode and potential mechanism of FN041 to prevent eczema(AD)in mice.MethodsAnimal experiment 1: The severe AD model was established and divided into two FN041 intervention modes.Intervention mode I: FN041 was supplemented to dams during the late trimester and lactation and pups after weaning;Intervention mode II,FN041 was supplemented after pups were weaned.The modeling method is to use capotriol ethanol solution(MC903)and ovalbumin(OVA)to induce severe AD on the ears of weaned pups.Animal experiment 2: The mild AD model was established and divided into three FN041 intervention modes.Intervention mode III: FN041 was supplemented to dams during the late trimester and lactation and pups after weaning;Intervention mode IV:FN041 was supplemented to dams during the late trimester and lactation;Intervention mode V: FN041 was supplemented to pups from the 4th day after birth to the end of lactation.The modeling method is to use MC903 to induce mild AD on the ears of weaned pups.ResultsIn animal experiment 1,it was found that the intervention of FN041 significantly improved severe AD symptoms in mice,and the effect of intervention mode I is significantly better than that of intervention mode II.Compared with the model group,the inflammatory response of the pup’s ears,the proportion of spleen regulatory T cells and the plasma Ig E were significantly decreased in mice in intervention mode I.Furthermore,the intestinal mucosal barrier was enhanced,and the Shannon index of the ileal microbiota was significantly increased.The microbiota structure deviated from the AD controls and shifted toward the healthy controls according to the PCo A of unweighted Uni Frac.The relative abundances of Limosilactobacillus,Faecalibacterium,Bifidobacterium and Akkermansia in the ileum were significantly increased compared to the AD group.Based on RNA-seq analysis of pups’ Peyer’s patches,intervention mode I inhibits autoimmune pathways such as asthma and systemic lupus erythematosus and activates retinol metabolism and PPAR signaling pathways to reduce inflammatory responses.In intervention mode II,FN041 significantly reduced the AD severity score,but the decrease was approximately 64.8% of intervention mode I.Intervention mode II increased Ig E levels by 5.1% compared to intervention mode I,and activated retinol metabolism and PPAR signaling pathways.In addition,in intervention mode II,the severity score of AD in the ear is 116.2% lower than that of Lactobacillus rhamnosus GG(LGG)and 44.1% lower than that of Lactobacillus reuteri DSM17938.In animal experiment 2,it was found that the intervention of FN041 could significantly reduce the symptoms of mild AD in mice,but there was no significant difference in the improvement of the three FN041 intervention methods.Compared with the model group,the ear AD symptoms of FN041 intervention group were significantly reduced.Shannon index of ileal microflora of mice in intervention mode III was significantly increased.The PCo A of weighted Uni Frac showed that there was no significant difference in the diversity of mouse flora among the three intervention methods,but it was significantly separated from the AD group.Compared with the AD group,the height and integrity of the ileum villi were significantly increased.ConclusionsCompared with the direct supplement of FN041 to the pups,FN041 can effectively prevent mild and severe AD in the late pregnancy and lactation of dams and weaned pups.Direct supplementation of FN041 to weaned pups can prevent severe AD,and the effect is better than that of DSM17938 and LGG.FN041 supplementation in dams and pups or FN041 supplementation in dams and pups respectively can prevent mild AD.FN041 supplementation can regulate the ileal microbiota,strengthen the intestinal mucosal barrier,increase the number of spleen Treg,activate the retinol metabolism and PPAR signal pathway and inhibit inflammatory pathways in Peyer’s patehes.