IMPROVED CRITERIA FOR PROBIOTIC STRAIN SELECTION.

MEDINA MARCELA; IZQUIERDO ESTHER; ENNAHAR SAID; SANZ YOLANDA

Chigado USA

Conferencia; American Society of Microbiology (ASM): Conference on Gastrointestinal Function; 2007

American Society of Microbiology (ASM)

The objective of this study was to asses a comparative in Vitro evaluation of the biological propierties of different Bifidobacterium longum strains could lead to a better definition of the probiotic concept linked to the in vivo functionality of the so-called probiotic strains. Different B. longum strains including currently commercialized probiotics, human commensals and reference strains were studied. The ability of these strains to interact with the host was comparatively evaluated by assaying their adhesion to mucin and their immunomodulatory properties on peripheral blood mononuclear cells (PBMC). The studied B. longum strains showed significantly different adhesion ability to mucin. The percentage of adhesion of these strains ranged from 2 to 11%. The studied probiotic strains were not those showing the highest adhesion ability, although this has been considered to be a positive trait of probiotics to ensure their residence and interaction with the human host. The mechanisms of adhesion of these strains were studied, and the results point for a role of proteins associated to cell-envelope of bifidobacteria. The studied B. longum strains also showed differences in their ability to stimulate cytokine production by PBMC. This leaded to differential increases in inflammatory (TNF-alpha) and regulatory (IL-10) cytokines that could have opposite effects on the host in healthy and disease situations. This could be particularly important for the administration of probiotics to population group’s immunocompromised or prone inflammatory biased immune responses. Overall, Bifidobacterium strains belonging to the same species showed remarkable differences in the biological properties related to their interaction with the host epithelial surface and immune system. The properties of particular probiotic strains were not always those desired according to the criteria generally accepted for their selection (FAO/WHO:2001). The establishment of soundest lnks between the in vitro and in vivo evaluation tests of probiotic strains as well as the identification of biological markers of their functional traits will be of pivotal importance for their rational selection and use, particularly for risk population groups. Keywords: Bifidobacterium, probiotics, adhesion, immunomodulation