title: Role of viability of probiotic strains in their persistence in the gut and in mucosal immune stimulation.
abstract: OBJECTIVE
  To determine how probiotic bacteria contact with intestinal epithelial and immune cells and the conditions to induce a good mucosal immune stimulation.
  
  
  RESULTS
  Lactobacillus casei was studied by transmission electron microscopy (TEM) to determine its interaction with the gut. We compared the influence of viable and nonviable lactic acid bacteria on the intestinal mucosal immune system (IMIS) and their persistence in the gut of mice. TEM showed whole Lact. casei adhered to the villi; the bacterial antigen was found in the cytoplasm of the enterocytes. Viable bacteria stimulated the IMIS to a greater extent than nonviable bacteria with the exception of Lact. delbrueckii subsp. bulgaricus. For all the strains assayed at 72 h no antigenic particles were found in the intestine.
  
  
  CONCLUSIONS
  Antigenic particles but not the whole bacteria can enter to epithelial cells and contact with the immune cells. Bacterial viability is a condition for a better stimulation of the IMIS.
  
  
  CONCLUSIONS
  We demonstrated that only antigenic particle interact with the immune cells and their fast clearance from the gut agrees with those described for the particulate antigens. The regular consumption of probiotics should not adversely affect the host.
authors.affiliation: Centro de Referencias para Lactobacilos (CERELA), Chacabuco, Tucumán, Argentina, and Cátedra de Inmunología, Instituto de Microbiología, Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, Argentina.
authors.forename: C Maldonado
authors.initials: CM
authors.lastname: Galdeano
authors.forename: G
authors.initials: G
authors.lastname: Perdigón
mesh_terms: D000818:Animals; D000942:Antigens, Bacterial / Q000032:analysis; D016207:Cytokines / Q000032:analysis; D003593:Cytoplasm / Q000276:immunology / Q000382:microbiology; D020895:Enterocytes / Q000276:immunology / Q000382:microbiology; D005455:Fluorescent Antibody Technique / Q000379:methods; D007070:Immunoglobulin A / Q000032:analysis; D007413:Intestinal Mucosa / Q000276:immunology / Q000382:microbiology*; D007421:Intestine, Small / Q000276:immunology / Q000382:microbiology; D007779:Lactobacillus acidophilus / Q000276:immunology / Q000502:physiology / Q000648:ultrastructure; D007780:Lacticaseibacillus casei / Q000276:immunology / Q000502:physiology* / Q000648:ultrastructure; D048668:Lactobacillus delbrueckii / Q000276:immunology / Q000502:physiology / Q000648:ultrastructure; D051379:Mice; D008807:Mice, Inbred BALB C; D008854:Microscopy, Electron / Q000379:methods; D019936:Probiotics
chemical_list: D000942:Antigens, Bacterial; D016207:Cytokines; D007070:Immunoglobulin A