Lactobacillus gasseri SBT2055 induces TGF-β expression in dendritic cells and activates TLR2 signal to produce IgA in the small intestine.

Fumihiko Sakai,Yukio Kadooka,Tomohiro Hosoya,Aiko Ono-Ohmachi,Akihiro Ogawa,Ken Ukibe,Takuya Shiozaki,Tomohiro Moriya,Yosuke Nakayama,Hisako Nakagawa,Tadaaki Miyazaki,Emiko Mizoguchi

doi:10.1371/journal.pone.0105370

Fumihiko Sakai, Yukio Kadooka + Show 10 more

Open Access

https://doi.org/10.1371/journal.pone.0105370

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Journal: PloS one	Publication Date: Aug 21, 2014
Citations: 101	License type: CC BY 4.0

Affiliation: Megmilk Snow Brand (Japan), Hokkaido University

Abstract

Probiotic bacteria provide benefits in enhancing host immune responses and protecting against infection. Induction of IgA production by oral administration of probiotic bacteria in the intestine has been considered to be one reason for this beneficial effect, but the mechanisms of the effect are poorly understood. Lactobacillus gasseri SBT2055 (LG2055) is a probiotic bacterium with properties such as bile tolerance, ability to improve the intestinal environment, and it has preventive effects related to abdominal adiposity. In this study, we have found that oral administration of LG2055 induced IgA production and increased the rate of IgA+ cell population in Peyer's patch and in the lamina propria of the mouse small intestine. The LG2055 markedly increased the amount of IgA in a co-culture of B cells and bone marrow derived dendritic cells (BMDC), and TLR2 signal is critical for it. In addition, it is demonstrated that LG2055 stimulates BMDC to promote the production of TGF-β, BAFF, IL-6, and IL-10, all critical for IgA production from B cells. Combined stimulation of B cells with BAFF and LG2055 enhanced the induction of IgA production. Further, TGF-β signal was shown to be critical for LG2055-induced IgA production in the B cell and BMDC co-culture system, but TGF-β did not induce IgA production in a culture of only B cells stimulated with LG2055. Furthermore, TGF-β was critical for the production of BAFF, IL-6, IL-10, and TGF-β itself from LG2055-stimulated BMDC. These results demonstrate that TGF-β was produced by BMDC stimulated with LG2055 and it has an autocrine/paracrine function essential for BMDC to induce the production of BAFF, IL-6, and IL-10.

Highlights

Probiotics are live microorganisms which when they are administered in adequate amounts confer health benefits to the host [1]
When mice were fed the control diet or the diet supplemented with Lactobacillus gasseri SBT2055 (LG2055) for 10 days, the amount of total IgA in the intestine of the LG2055 fed group were slightly higher in the jejunum and significantly higher in the colon compared with the control group (Figure S2), suggesting that oral administration of LG2055 for at least 10 days is required to induce the IgA production in the intestine
These results suggest that there are multiple factors that are critical for IgA production and are induced in the bone marrow derived dendritic cells (BMDC) stimulated with LG2055, and that these factors promote the secretion of IgA from B cells

Summary

Introduction

Probiotics are live microorganisms which when they are administered in adequate amounts confer health benefits to the host [1]. Lactobacilli are characterized by the production of lactic acid and are commonly applied to many vegetable, meat, and dairy fermentations. These bacteria can influence the composition and activity of the gut microbiota. There is a general consensus that orally administered probiotic bacteria contribute to immune homeostasis by altering the microbial balance or by interacting with the host immune system [2,3,4]. The interplay between the mucosaassociated immune system and microbiota certainly plays a pivotal role in mucosal tissue homeostasis as well as in protection against infectious and inflammatory diseases occurring at mucosal sites [5]

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