Abstract
Vasoactive intestinal peptide (VIP) plays an important role in the neuro-endocrine-immune system. Mast cells (MCs) are important immune effector cells. This study was conducted to investigate the protective effect of L. casei ATCC 393 on Enterotoxigenic Escherichia coli (ETEC) K88-induced intestinal mucosal immune barrier injury and its association with VIP/MC signaling by in vitro experiments in cultures of porcine mucosal mast cells (PMMCs) and in vivo experiments using VIP receptor antagonist (aVIP) drug. The results showed that compared with the ETEC K88 and lipopolysaccharides (LPS)-induced model groups, VIP pretreatment significantly inhibited the activation of MCs and the release of β-hexosaminidase (β-hex), histamine and tryptase. Pretreatment with aVIP abolished the protective effect of L. casei ATCC 393 on ETEC K88-induced intestinal mucosal immune barrier dysfunction in C57BL/6 mice. Also, with the blocking of VIP signal transduction, the ETEC K88 infection increased serum inflammatory cytokines, and the numbers of degranulated MCs in ileum, which were decreased by administration of L. casei ATCC 393. In addition, VIP mediated the regulatory effect of L. casei ATCC 393 on intestinal microbiota in mice. These findings suggested that VIP may mediate the protective effect of L.casei ATCC 393 on intestinal mucosal immune barrier dysfunction via MCs.
Highlights
The intestinal barrier is essential for maintaining intestinal homeostasis and health
This study was aimed to investigate the role of Vasoactive intestinal peptide (VIP) in the protective effect of L. casei ATCC 393 on intestinal barrier dysfunction in mice challenged by Enterotoxigenic Escherichia coli (ETEC) K88 and its association with mast cells (MCs)
AVIP had no effect on porcine mucosal mast cells (PMMCs)
Summary
The intestinal barrier is essential for maintaining intestinal homeostasis and health. It prevents the loss of water and electrolytes and the invasion of antigens and microorganisms [1, 2]. The integrity of the intestinal barrier is important for human and animal health. The intestinal mucosal immune barrier is mainly composed of intestinal mucosal epithelial cells and intestinal associated lymphoid tissues. The impact of L. casei on the cecal microbiome and innate immune system is strain specific [11], and dose and time-dependent [12]. L. casei ATCC 393 alleviated ETEC K88-induced intestinal barrier dysfunction via the toll-like receptors (TLRs)/ mast cells (MCs) pathway [14]
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