Low molecular weight fractions of BiMuno® exert immunostimulatory properties in murine macrophages

Previous in vivo murine oral challenge studies have shown that the galactooligosaccharide containing product, BiMuno®, reduced colonisation of S. Typhimurium. To gain further insights into the mechanism of reduced colonisation, we wished to test the hypothesis that the low molecular weight fractions of BiMuno® or a specific low molecular weight fraction may have direct immuno-modulatory effects on murine macrophages. Cytokine responses of murine macrophages in response to the commercially available product, BiMuno®, a basal solution BiMuno® without GOS, purified low molecular weight fractions (referred to as GOS), and the individual fractions of GOS (DP2, 3 and ⩾4, with each fraction representing the increasing degree of complex polymerisation) were determined in vitro and ex vivo. These studies demonstrated that BiMuno®, significantly stimulated both pro- and anti-inflammatory cytokines in vitro (P ⩽ 0.0394). Furthermore, the data indicate that the low molecular weight fractions may be the primary stimulant of BiMuno® and specifically its tri (DP3) and ⩾tetra-saccharide (DP ⩾ 4) fractions (P ⩽ 0.0394).

► We model the immunogenic properties of Bimuno®; a GOS containing prebiotic mixture.
► The studies examine cytokine production by macrophages in vitro and ex vivo.
► Bimuno® stimulates pro and anti-inflammatory cytokine production.
► Data suggests the tri and tetrasaccharide fractions may be the primary stimulant.
► Low molecular weight fractions of Bimuno® may be directly immunogenic.