Previous works have described the activity of Bifidobacterium longum subsp. infantis CECT
7210 (also commercially named B. infantis IM-1®) against rotavirus in mice and intestinal pathogens in
piglets, as well as its diarrhea-reducing effect on healthy term infants. In the present work, we focused
on the intestinal immunomodulatory effects of B. infantis IM-1® and for this purpose we used the
epithelial cell line isolated from colorectal adenocarcinoma Caco-2 and a co-culture system of human
dendritic cells (DCs) from peripheral blood together with Caco-2 cells. Single Caco-2 cultures and
Caco-2: DC co-cultures were incubated with B. infantis IM-1® or its supernatant either in the presence
or absence of Escherichia coli CECT 515. The B. infantis IM-1® supernatant exerted a protective effect
against the cytotoxicity caused by Escherichia coli CECT 515 on single cultures of Caco-2 cells as
viability reached the values of untreated cells. B. infantis IM-1® and its supernatant also decreased the
secretion of pro-inflammatory cytokines by Caco-2 cells and the co-cultures incubated in the presence
of E. coli CECT 515, with the response being more modest in the latter, which suggests that DCs
modulate the activity of Caco-2 cells. Overall, the results obtained point to the immunomodulatory
activity of this probiotic strain, which might underlie its previously reported beneficial effects.Laboratorios Ordesa, S. L.Center for the Development of Industrial Technology (CDTI) of the Spanish Ministry of Science and Innovation (TOLERA project) 2017087