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Cytokine production by peripheral blood mononuclear cells (PBMCs) stimulated by Bifidobacteria spp. or galactooligosaccharide

Published online by Cambridge University Press:  04 June 2010

M. Baran
Affiliation:
University of Reading, Food Biosciences, PO Box 226, Whiteknights, Reading RG6 6AP
S. Kolida
Affiliation:
University of Reading, Food Biosciences, PO Box 226, Whiteknights, Reading RG6 6AP
C. Childs
Affiliation:
University of Reading, Food Biosciences, PO Box 226, Whiteknights, Reading RG6 6AP
P. Yaqoob
Affiliation:
University of Reading, Food Biosciences, PO Box 226, Whiteknights, Reading RG6 6AP
G. Tzortzis
Affiliation:
Clasado Ltd, 5 Canon Harnett Court, Milton Keynes MK12 5NF, UK
R. Rastall
Affiliation:
University of Reading, Food Biosciences, PO Box 226, Whiteknights, Reading RG6 6AP
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Abstract

Type
Abstract
Copyright
Copyright © The Authors 2009

The relationship between gut microbiota and intestinal immune response has been intensively studied. Several studies showed that bifidobacteria enhance many aspects of immune function(Reference Foligne, Nutten and Grangette1Reference Medina, Izquierdo and Ennahar3). It is suggested that probiotic strains can be screened in vitro for their immunomodulatory potential using peripheral blood mononuclear cells (PBMCs), before clinical (in vivo) investigations(Reference Foligne, Nutten and Grangette1). Galactooligosaccharides (GOS) are one of the best established prebiotic compounds; however, immunomodulatory properties of prebiotics are not yet fully understood.

In vitro studies to date have employed either live(Reference Foligne, Nutten and Grangette1, Reference Medina, Izquierdo and Ennahar3) or heat-killed bacterial cells(Reference Shida, Suzuki and Kiyoshima-Shibata4), but rarely both. This study compares cytokine production in response to live and heat-killed bifidobacteria by human PBMC. Furthermore, it investigates different concentrations of GOS, which will induce TNF-α production by PBMCs.

In this study live and heat-killed Bifidobacterium lactis HOWARU and Bifidobacterium bifidum NCIMB 41171 were co-cultured with human PBMC isolated from the blood of healthy donors (n=4). Their effects on pro- and anti-inflammatory cytokine production were investigated.

In order to determine the effect of GOS, PBMCs were incubated in the presence of different concentrations of GOS with or without LPS (0.001 μg/l).

Regardless of whether bacteria were live or heat-killed, both B. lactis and B. bifidum stimulated cytokine production by PBMC. B. lactis induced a significant increase in the production of IL-1β (P⩽0.01) and TNF-α (P<0.05) compared to the unstimulated control, and B. bifidum NCIMB41171 showed a similar trend. No significant change in IL-10 production was observed. There was no effect of heat killing on cytokine production, or on the ratio between pro-inflammatory and anti-inflammatory cytokines for either bacterial strain.

7 and 5.5 g/l of GOS stimulate significantly PBMCs to produce TNF-α. In the presence of LPS, GOS stimulate the TNF-α level significantly higher than in the absence of LPS thus LPS have additive effect.

In conclusion, both species of bifidobacteria induced production of IL-1β and TNF-α but not on IL-10, regardless of whether the cells were live or heat-killed. High concentration of GOS is also able to induce PBMCs to produce cytokines.

References

1.Foligne, B, Nutten, S, Grangette, C et al. (2007) World J Gastroenterol 13, 236243.CrossRefGoogle Scholar
2.Hatcher, et al. . (1993) J Dairy Sci 76, 2485.CrossRefGoogle Scholar
3.Medina, M, Izquierdo, E, Ennahar, S et al. (2007) Clin Exp Immunol 150, 531538.CrossRefGoogle Scholar
4.Shida, K, Suzuki, T & Kiyoshima-Shibata, J (2006) Clin Vaccine Immunol 13, 9971003.CrossRefGoogle Scholar