title: Changes in murine jejunal morphology evoked by the bacterial superantigen Staphylococcus aureus enterotoxin B are mediated by CD4+ T cells.
abstract: Bacterial superantigens (SAgs) are potent T-cell stimuli that have been implicated in the pathophysiology of autoimmune and inflammatory disease. We used Staphylococcus aureus enterotoxin B (SEB) as a model SAg to assess the effects of SAg exposure on gut form and cellularity. BALB/c, SCID (lacking T cells) and T-cell-reconstituted SCID mice were treated with SEB (5 or 100 microg intraperitoneally), and segments of the mid-jejunum were removed 4, 12, or 48 h later and processed for histochemical or immunocytochemical analysis of gut morphology and major histocompatibility complex class II (MHC II) expression and the enumeration of CD3+ T cells and goblet cells. Control mice received saline only. SEB treatment of BALB/c mice caused a time- and dose-dependent enteropathy that was characterized by reduced villus height, increased crypt depth, and a significant increase in MHC II expression. An increase in the number of CD3+ T cells was observed 48 h after exposure to 100 microg of SEB. Enteric structural alterations were not apparent in SEB-treated SCID mice compared to saline-treated SCID mice. In contrast, SEB challenge of SCID mice reconstituted with a mixed lymphocyte population or purified murine CD4+ T cells resulted in enteric histopathological changes reminiscent of those observed in SEB-treated BALB/c mice. These findings implicate CD4+ T cells in this SEB-induced enteropathy. Our results show that SAg immune activation causes significant changes in jejunal villus-crypt architecture and cellularity that are likely to impact on normal physiological processes. We speculate that the elevated MHC II expression and increased number of T cells could allow for enhanced immune responsiveness to other SAgs or environmental antigens.
authors.affiliation: Intestinal Disease Research Programme, McMaster University, Hamilton, Ontario, Canada.
authors.forename: M A
authors.initials: MA
authors.lastname: Benjamin
authors.forename: J
authors.initials: J
authors.lastname: Lu
authors.forename: G
authors.initials: G
authors.lastname: Donnelly
authors.forename: P
authors.initials: P
authors.lastname: Dureja
authors.forename: D M
authors.initials: DM
authors.lastname: McKay
mesh_terms: D000818:Animals; D017252:CD3 Complex / Q000032:analysis; D015496:CD4-Positive T-Lymphocytes / Q000502:physiology*; D004768:Enterotoxins / Q000633:toxicity*; D000949:Histocompatibility Antigens Class II / Q000032:analysis; D007583:Jejunum / Q000473:pathology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D016513:Mice, SCID; D013211:Staphylococcus aureus / Q000276:immunology*; D018089:Superantigens / Q000633:toxicity*
chemical_list: D017252:CD3 Complex; D004768:Enterotoxins; D000949:Histocompatibility Antigens Class II; D018089:Superantigens; C031818:enterotoxin B, staphylococcal