P860 Evaluation of the probiotic features of two different multi-strain probiotic preparations from two different manufacturers

The aim of this work was to compare the probiotic adhesion features and immunomodulatory properties of 2 probiotic products characterised by the same bacterial content but manufactured in different places (Italy and USA).

The multi-strain probiotic products under investigation were composed by a mixture of 8 different strains. The two products were manufactured in Italy (VSL#3 - Lot 710061 expiry date 10/2019) and in US (Vivomixx - Lot 1708702 expiry date 31/03/2019). The cell viability in each lot was assessed by flow cytometry. The adhesive abilities of probiotics were evaluated on three different eukaryotic intestinal cell lines (Caco-2, HT-29 and mucus-producing HT29-MTX).

For the evaluation of immune-modulatory activity, human Dendritic Cells (hDCs) obtained from blood mononuclear cells were exposed for 6 days to cytokines cocktail (IL-4 20 ng/ml + GM-CSF 50 ng/ml) and then to both probiotic mixtures for 2 h with MOI 1:10. A positive inflammatory condition was obtained by incubating washed hDCs in fresh medium containing Salmonella sp. for additional two h. Finally, hDCs were then cultured for 23 h in complete medium with antibiotics for the final analysis of soluble and surface molecules with ELISA or cytofluorimetric analysis method, respectively.

The two products showed a comparable amount of live cells, 2.2 1011 (FU/g) and 2.4 1011 (FU/g), respectively, for the VSL#3 and Vivomixx. The two tested products showed similar adhesive capacity to the 3 cell lines considered, with adhesion values in the range 67–71%. No significant differences were observed in the percentage of adhesiveness expressed by the two mixtures according to the type of cell line considered. Regarding the immune-modulatory ability of the two tested products, results showed that they have the same behaviours. The exposure of the probiotic mixtures to hDCs resulted in a meaningful reduction of the expression of IL-12 following Salmonella induction. We observed that both products slightly increase the proportion of HLA-DR+/CD11+ and CD80+/CD11+ hDCs. Moreover, both mixtures significantly reduce Salmonella-induced HLA-DR+/CD11+ and CD80+/CD11+ hDCs. Both probiotic products did not significantly induce TNF-α production by hDCs at basal condition, and they did not result in further TNF-α production if compared with that induced by Salmonella sp. alone even if the response of the two products was almost identical.

Investigative activities described in this work demonstrated a comparable adhesive performances and interesting immunomodulatory activity against inflammation induced by Salmonella sp. for both VSL#3 and Vivomixx showing same behaviours irrespective of the manufacturer.