| ObjectiveUrbanization leads to the"disappearance"of certain breast milk bacteria,which leads to delayed intestinal microbiota and immune development in infants and is associated with a high incidence of atopic dermatitis(AD)in urban infants.Lactobacillus reuteri Fn041and Lactobacillus gasseri Fn036 are beneficial bacteria from agricultural and pastoral areas and rural breast milk sources,respectively.The aim of this study was to investigate the effect and mechanism of these two potential probiotics administered to mother mice to prevent AD in offspring mice.MethodsBALB/C pregnant mice were divided into CON group(gavage of PBS),AD group(gavage of PBS),AD+Fn041 group(gavage of Fn041),AD+Fn036 group(gavage of Fn036),AD+LGG group(Lactobacillus rhamnosus GG,positive control)five groups were given free diet.From 1 week before birth to the end of lactation,the offspring continued to be intragastrically administered for 1 week after weaning,and the intragastric dose of probiotics was 1×10~9 CFU/day.After weaning at 3 weeks of age,calcipotriol was applied to the right ear of model mice to induce AD for 7 consecutive days.Mice were sacrificed on the 8th day after fasting for 12 hours,blood was collected,and tissues such as spleen,mesenteric lymph nodes,and ears were collected for further analysis and detection.ResultsAnalysis of phenotypic indicators shows,compared with AD group,the intervention of Fn041 and Fn036 could alleviate the ear thickness and redness of AD mice(p<0.001)and reduce the infiltration of mast cells and eosinophils(p<0.001).The effect of Fn041 was better than that of LGG.Fn036 and Fn041 intervention significantly decreased plasma IL-4(p<0.05)and increased IL-12(p<0.05),and significantly decreased ear thymic stromal lymphopoietin(TSLP,p<0.05).Fn041 intervention reduced plasma Ig E(p<0.05).Fn041intervention significantly increased ileal contents secreted immunoglobulin A(s Ig A,p<0.05),but LGG intervention significantly decreased ileal s Ig A(p<0.05).Flow cytometry analysis showed that Fn041 and Fn036 intervention significantly increased mesenteric lymph node regulatory T cells(p<0.05).Quantitative PCR analysis showed that the intervention of Fn041 and Fn036significantly up-regulated the expression of Clandin-2 m RNA in the colon,and down-regulated the m RNA expression of TSLP and IL-13 in the ear(p<0.05).Cecal 16S r RNA amplicon sequencing analysis showed that Fn041 intervention significantly altered the microbiota structure(β-diversity)and significantly increased the relative abundance of Lactobacillus and Akkermansia(p<0.05).Small intestinal Peyer’s junction transcriptome analysis showed that Fn041 intervention activated fat absorption and retinol(vitamin A)metabolism pathways,and deconvolution analysis showed increased regulatory T cell content(p<0.05).Plasma non-target metabolome analysis showed that the plasma retinol and tryptophan concentrations of the model group mice were decreased(p<0.05),and Fn041 treatment recovered to healthy levels and increased the level of kynurenine(p<0.05),LGG treatment increased the level of indole-3-lactic acid(p<0.05).The non-target metabolome analysis of cecal contents showed that compared with the CON group,the content of tryptophan in the model group was significantly reduced(p<0.05),but compared with the AD group,the content of tryptophan was significantly increased after Fn036 treatment(p<0.05),while the tryptophan content of Fn041 treatment the amino acid content did not change significantly.ConclusionsL.reuteri Fn041 and L.gasseri Fn036 have preventive effects on atopic dermatitis in mice,and the preventive effect of Fn041 is better than that of Fn036 and LGG.Its mechanism of action may be related to regulating the balance between Th1 and Th2immune responses,increasing the ratio of Tregs in mesenteric lymph nodes,improving Fat digestion and absorption,Retinol metabolism,inducing the proliferation of regulatory T cells,and enhancing immune tolerance.These findings provide a new basis for the prevention of atopic dermatitis. |
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