关键词: 嗜酸乳酸杆菌, 自主活动受限, 应激, 肠道黏膜免疫

Abstract:

Objective: To assess the influence of Lactobacillus acidophilus on intestinal mucosal immunity in a mouse
model of stress induced by auto-activity restriction. Methods: Male health BALB/c mice were divided into 4 groups. In
normal control group (NC), the mice received balanced diet and water and were left undisturbed in their cages. In NC
plus Lactobacillus acidophilus (NC + LA) group, the mice were given a suspension of LA with 108 CFU/d per mouse
through intragastric administration under normal control condition. In stress group (S), the mice were subjected to stress
induced by auto-activity restriction for 3 h per day. In stress plus LA (S+LA) group, the mice were given a suspension of
LA with 108 CFU/d per mouse through intragastric administration under stress condition. After 15 days, mice from each
group were sacrificed. CD4+T, CD8+T and CD11c+ dendritic cells (CD11c+ DCs) in mesenteric lymph nodes (MLN),
interleukin-10 (IL-10) and interleukin-17 (IL-17) levels in colon tissue, total secretory immunoglobulin A (sIgA) level in
small intestine were analyzed by flow cytometry and enzyme-linked immunosorbent assay (ELISA). Results: Under NC
condition, the proportions of CD4+T cells and CD11c+ DCs in MLN (CD4+T cell: P < 0.01, CD11c+ DC: P < 0.05), small
intestinal sIgA level and IL-10 level in colon tissue (sIgA, IL-10: P < 0.05) were enhanced by LA and IL-17 level in colon
tissue was decreased (P < 0.05), but the proportion of CD8+T cells in MLN was not significantly varied (P > 0.05). After
auto-activity restriction, the proportions of CD4+T cells, CD8+T cells and CD11c+ DCs, and the levels of IL-10 and small
intestinal sIgA were decreased (CD4+T cell, CD11c+ DC, IL-10, sIgA: P < 0.01, CD8+T cell: P < 0.05). Interestingly, the
proportion of CD4+T cells and CD11c+ DCs, the levels of IL-10 and small intestinal sIgA were increased, and the level of
IL-17 was decreased by LA under stress condition (P < 0.05), but the proportion of CD8+T cells was not significantly affected
(P > 0.05). Conclusion: LA administered to mice subjected to auto-activity restriction enhances the proportions of
CD4+T cells and CD11c+ DCs in MLN, up-regulates the levels of IL-10 in colon and total small intestinal sIgA, and downregulates
the level of IL-17 in colon, thereby modulating their intestinal mucosal immunity under stress condition.

Key words: Lactobacillus acidophilus, auto-activity restriction, stress, intestinal mucosal immunity