Effect of oral administration of Lactobacillus paracasei L9 on mouse systemic immunity and the immune response in the intestine

Yuanbo Zhu,Huiyuan Guo,Fazheng Ren,Liang Zhao,Jun Zhu,Ming Zhang

doi:10.2298/abs150216021z

Yuanbo Zhu, Huiyuan Guo + Show 4 more

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https://doi.org/10.2298/abs150216021z

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Abstract

A probiotic strain Lactobacillus paracasei L9,which was isolated from human intestine, was investigated for its immunomodulatory activity in vivo. Results showed that L9 improved systemic immunity by enhancing the phagocytic activity of peritoneal macrophages, the proliferation ratio of splenocytes, the IgG level in the serum and the level of IgA in the mucosa. Further, L9induced theTh1-polarized immune response by elevating the IFN-?/IL-4 ratio in the mucosa. This effect was confirmed by the enhanced IL-12-inducing activity of macrophages after in vitro stimulation of L9. Also detected was increased expression of TLR-2mRNA in the mucosa. We predict that L9 could enhance innate immunity by activating TLR-2 in the mucosa, and enhance acquired immunity by promoting Th1 polarization through induced production of IL-12 by macrophages.

Highlights

Immunomodulatory activity is an important criterion for selecting and evaluating probiotics as it is thought to be responsible for many probiotic effects, such as their anti-inflammatory, anti-infection and antitumor activities [1]
Our results show that L9 enhanced innate immunity by elevating phagocytosis of macrophages, strengthening the acquired immunity by improving splenic lymphocyte proliferation and increasing the serum IgG concentration and the concentration of Secretory IgA (sIgA) in the mucus
It was suggested that strains of lactic acid bacteria (LAB) that are capable of affecting a wider array of immune functions are likely to be more beneficial to human health [6]

Summary

Introduction

Immunomodulatory activity is an important criterion for selecting and evaluating probiotics as it is thought to be responsible for many probiotic effects, such as their anti-inflammatory, anti-infection and antitumor activities [1]. Systemic immunity, consisting of innate immunity (macrophage phagocytosis, etc.) and acquired immunity, have been widely used to evaluate the immunomodulatory effect of probiotics [1,4,5,6]. T helper cells are key components of acquired immunity responses [9], which can be polarized into T helper type-1 (Th1), T helper type-2 (Th2) or regular T (Treg) cells by specific lactic acid bacteria (LAB) strains [10]. Some LAB strains have been demonstrated to induce interleukin (IL)-12 production from dendritic cells (DCs) and macrophages, converting a Th2 response into a Th1-dominated response and suppressing antigen-specific IgE production in mice [11,12], whereas some strains are capable of controlling inflammatory diseases by inducing the development of CD4+ Forkhead box P3 (Foxp3)+ Tregs cells [13]

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