Chapter 16 - Preclinical data support the strong specificity and advertising ability to control the immune reactions at mucosal sites

Abstract

Our results of in vitro, in vivo, and ex vivo experiments on different mice models demonstrated that (1) prophylactic usage of probiotics (Schaedler’s Escherichia coli) has a significant protective effect against dissemination of bacteria; (2) the same strain of Schaedler’s E. coli (additionally to segmented filamentous bacteria) induced in a specific manner the expression of RegIIIβ, RegIIIγ, and IFN-γ genes by chronic monoassociation of germ-free severe combined immune deficient mice; (3) we have found evidence for specific antigen (Ag) selection and local stimulation of IgA anti-PC-producing cells of the B1 lineage by a type 1, thymus-independent Ag in the tissue fragment cultures taken from nasal and respiratory-associated lymphoid tissue versus gastrointestinal tissue; (4) we have demonstrated that the specific activity of probiotics strains and their immune-modulating efficacy depend of their morphology, particularly on the elasticity of their cells walls. We have detected by our ex vivo techniques that different commensals induced different amounts or levels of specific IgA, and we report that monocyte-derived dendritic cells are able to mediate robust Th1 and Th17 responses upon stimulation by gram-negative commensal strains or Morganella morganii, while the probiotic gram-positive strain of Bacillus subtilis limits this effect.