AUTHOR=Huang Shimeng , Rong Xiaoping , Liu Meiling , Liang Zhongjun , Geng Yanqiang , Wang Xinyue , Zhang Jianyun , Ji Cheng , Zhao Lihong , Ma Qiugang 

TITLE=Intestinal Mucosal Immunity-Mediated Modulation of the Gut Microbiome by Oral Delivery of Enterococcus faecium Against Salmonella Enteritidis Pathogenesis in a Laying Hen Model

JOURNAL=Frontiers in Immunology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2022.853954

DOI=10.3389/fimmu.2022.853954

ISSN=1664-3224

ABSTRACT=<p><italic>Enterococcus faecium</italic> (<italic>E. faecium</italic>) is a protective role that has crucial beneficial functions on intestinal homeostasis. This study aimed to investigate the effects of <italic>E. faecium</italic> on the laying performance, egg quality, host metabolism, intestinal mucosal immunity, and gut microbiota of laying hens under the <italic>Salmonella Enteritidis</italic> (<italic>S. Enteritidis</italic>) challenge. A total of 400 45-week-old laying hens were randomly divided into four treatments (CON, EF, SCON, and SEF groups) with five replicates for each group and 20 hens per replicate and fed with a basal diet or a basal diet supplemented with <italic>E. faecium</italic> (2.5 × 10<sup>8</sup> cfu/g feed). The experiment comprised two phases, consisting of the pre-salmonella challenged phase (from day 14 to day 21) and the post-salmonella challenged phase (from day 21 to day 42). At day 21 and day 22, the hens in SCON and SEF groups were orally challenged with 1.0 ml suspension of 10<sup>9</sup> cfu/ml <italic>S. Enteritidis</italic> (CVCC3377) daily, whereas the hens in CON and EF groups received the same volume of sterile PBS. Herein, our results showed that <italic>E. faecium</italic> administration significantly improved egg production and shell thickness during salmonella infection. Also, <italic>E. faecium</italic> affected host lipid metabolism parameters <italic>via</italic> downregulating the concentration of serum triglycerides, inhibited oxidative stress, and enhanced immune functions by downregulating the level of serum malondialdehyde and upregulating the level of serum immunoglobulin G. Of note, <italic>E. faecium</italic> supplementation dramatically alleviated intestinal villi structure injury and crypt atrophy, and improved intestinal mucosal barrier injuries caused by <italic>S. Enteritidis</italic> challenge. Moreover, our data revealed that <italic>E. faecium</italic> supplementation ameliorated <italic>S. Enteritidis</italic> infection-induced gut microbial dysbiosis by altering the gut microbial composition (reducing <italic>Bacteroides</italic>, <italic>Desulfovibrio</italic>, <italic>Synergistes</italic>, and <italic>Sutterella</italic>, and increasing <italic>Barnesiella</italic>, <italic>Butyricimonas</italic>, <italic>Bilophila</italic>, and <italic>Candidatus_Soleaferrea</italic>), and modulating the gut microbial function, such as cysteine and methionine metabolism, pyruvate metabolism, fatty acid metabolism, tryptophan metabolism, salmonella infection, and the PI3K-Akt signaling pathway. Taken together, <italic>E. faecium</italic> has a strong capacity to inhibit the <italic>S. Enteritidis</italic> colonization of hens. The results highlight the potential of <italic>E. faecium</italic> supplementation as a dietary supplement to combat <italic>S. Enteritidis</italic> infection in animal production and to promote food safety.</p>