TITLE:
Colonization by Superantigen Producing Staphylococcus aureus in Mice Enhances the Capacity to Develop Oral Tolerance
AUTHORS:
Anna Stern, Erika Lindberg, Forough L. Nowrouzian, Agnes E. Wold, Sofia Östman
KEYWORDS:
Oral Tolerance, Superantigen, Staphylococcus aureus
JOURNAL NAME:
Open Journal of Immunology,
Vol.6 No.3,
August
16,
2016
ABSTRACT: Microbial stimulation in early childhood may be necessary for proper maturation of the immune
system. Infants colonized with Staphylococcus aureus have low risk of developing food allergy.
Neonatal exposure to staphylococcal superantigen improves oral tolerance and enhances protection
in experimental allergy models. Here, we used three wild-type strains of S. aureus, naturally
harboring genes for different superantigens (SElM/SElO alone, or in combination with SEA or
TSST-1). We first investigated their in vitro stimulatory capacity of splenocytes from germ-free
mice. Secondly, germ-free mice were colonized with the strains and their capacity to develop oral
tolerance was tested in a food allergy model. In vitro, S. aureus with only SElM/SElO genes promoted
the strongest B-cell stimulation. S. aureus carrying gene for SEA induced the highest proportion
of CD4+FoxP3+ T cells. The proportion of regulatory T cells was inversely correlated to
B-cell proliferation, indicating suppressive ability of these cells. All strains were equally able to
colonize the germ-free gut, initially achieving 1010CFU/g faeces, which decreased to 105 over a period
of six weeks. Mice colonized with S. aureus carrying genes for SEA or TSST-1 had improved
capacity to develop tolerance compared to germ-free mice. These results suggest that colonization
by S. aureus producing superantigens may improve active tolerance to gut allergens.