title: Visualization of Probiotic-Mediated Ca2+Signaling in Intestinal Epithelial CellsIn Vivo.
abstract: Probiotics, such as lactic acid bacteria (LAB) andBacillus subtilisvar.natto, have been shown to modulate immune responses. It is important to understand how probiotic bacteria impact intestinal epithelial cells (IECs), because IECs are the first line of defense at the mucosal surface barrier and their activities substantially affect the gut microenvironment and immunity. However, to date, their precise mechanism remains unknown due to a lack of analytical systems available for live animal models. Recently, we generated a conditional Ca2+biosensor Yellow Cameleon (YC3.60) transgenic mouse line and established 5D (x, y, z, time, and Ca2+) intravital imaging systems of lymphoid tissues including those in Peyer's patches and bone marrow. In the present study, we further advance our intravital imaging system for intestinal tracts to visualize IEC responses against orally administrated food compounds in real time. Using this system, heat-killedB. subtilis natto, a probiotic TTCC012 strain, is shown to directly induce Ca2+signaling in IECs in mice housed under specific pathogen-free conditions. In contrast, this activation is not observed in theLactococcus lactisstrain C60; however, when we generate germ-free YC3.60 mice and observe the LAB stimulation of IECs in the absence of gut microbiota, C60 is capable of inducing Ca2+signaling. This is the first study to successfully visualize the direct effect of probiotics on IECs in live animals. These data strongly suggest that probiotic strains stimulate IECs under physiological conditions and that their activity is affected by the microenvironment of the small intestine, such as commensal bacteria.
authors.affiliation: Department of Immunology, Medical Research Institute, Tokyo Medical and Dental University , Tokyo , Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Adachi
authors.affiliation: Department of Biomedical Science, Graduate School of Agricultural and Life Sciences, The University of Tokyo , Tokyo , Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kakuta
authors.affiliation: Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University , Kobe , Japan.
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Aihara
authors.affiliation: Biomedical Research Institute, National Institute for Advanced Industrial Science and Technology (AIST) , Tsukuba , Japan.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Kamiya
authors.affiliation: Biomedical Research Institute, National Institute for Advanced Industrial Science and Technology (AIST) , Tsukuba , Japan.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Watanabe
authors.affiliation: Department of Bio-science and Engineering, Shibaura Institute of Technology , Saitama , Japan.
authors.forename: Naomi
authors.initials: N
authors.lastname: Osakabe
authors.affiliation: Department of Bio-science and Engineering, Shibaura Institute of Technology , Saitama , Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Hazato
authors.affiliation: Laboratory for Cell Function and Dynamics, Advanced Technology Development Group, Brain Science Institute, RIKEN , Saitama , Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Miyawaki
authors.affiliation: Department of Immune Regulation, Tokyo Medical and Dental University , Tokyo , Japan.
authors.forename: Soichiro
authors.initials: S
authors.lastname: Yoshikawa
authors.affiliation: Laboratory of Recombinant Animals, Medical Research Institute, Tokyo Medical and Dental University , Tokyo , Japan.
authors.forename: Takako
authors.initials: T
authors.lastname: Usami
authors.affiliation: Department of Immune Regulation, Tokyo Medical and Dental University , Tokyo , Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Karasuyama
authors.affiliation: NARO Institute of Livestock and Grassland Science, National Agriculture and Food Research Organization, Tsukuba , Ibaraki , Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Kimoto-Nira
authors.affiliation: Laboratory of Veterinary Public Health, Graduate School of Agricultural and Life Sciences, The University of Tokyo , Tokyo , Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Hirayama
authors.affiliation: Biomedical Research Institute, National Institute for Advanced Industrial Science and Technology (AIST) , Tsukuba , Japan.
authors.forename: Noriko M
authors.initials: NM
authors.lastname: Tsuji
keywords: Bacillus subtilis; Ca2+ signaling; Lactococcus; germ-free mouse; intestinal epithelial cell; intravital imaging; probiotic; small intestine