AUTHOR=Zhang Rongling , Li Zhengguang , Gu Xinyi , Zhao Jiancun , Guo Tingting , Kong Jian 

TITLE=Probiotic Bacillus subtilis LF11 Protects Intestinal Epithelium Against Salmonella Infection

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=12

YEAR=2022

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2022.837886

DOI=10.3389/fcimb.2022.837886

ISSN=2235-2988

ABSTRACT=<p>Enteric diseases caused by <italic>Salmonella</italic> are prevalent in poultry farming. With the forbiddance of antibiotics in feedstuff industry, <italic>Bacillus subtilis</italic> (<italic>B. subtilis</italic>) preparation as antibiotic alternatives against <italic>Salmonella</italic> infection has gained increasing attention recently. However, the protection modes of <italic>B. subtilis</italic> against <italic>Salmonella</italic> infection in broilers are strain-specific. In this study, probiotic <italic>B. subtilis</italic> LF11 significantly reduced diarrhea and mortality of broilers caused by <italic>Salmonella braenderup</italic> (<italic>S. braenderup</italic>) in spite of no inhibition effect on it <italic>in vitro</italic>. Here, the intestinal epithelial cells NCM460 were incubated to explore the protection of <italic>B. subtilis</italic> LF11 on intestinal epithelium against <italic>Salmonella</italic>. The results revealed that <italic>B. subtilis</italic> LF11 showed obvious exclusion activity with the decrease of adhesion and invasion of <italic>S. braenderup</italic> to NCM460 cells, accordingly with the increase of NCM460 cell survival compared with <italic>S. braenderup</italic> challenge alone. Meanwhile, RT-PCR and Western blot proved that the gene transcription and expression levels of four tight junction proteins in NCM 460 cells were upregulated, which was further confirmed by immunofluorescence observation. Besides, <italic>B. subtilis</italic> LF11 downregulated the gene transcription levels of the proinflammatory cytokines IL-6, IL-8, and TNF-α induced by <italic>S. braenderup</italic> H9812. ELISA analysis also verified that <italic>B. subtilis</italic> LF11 reduced the IL-8 production significantly. In general, <italic>B. subtilis</italic> LF11 has the ability to protect the intestinal epithelium against <italic>Salmonella</italic> infection by reducing the <italic>Salmonella</italic> adhesion and invasion, enhancing the intestinal barrier and attenuating the enterocyte inflammatory responses, and has the potential as probiotics to prevent enteric diseases in broilers.</p>