Table 1.
Emetic response induced by SEs in common marmoset.
Fig 1.
Superantigenic activity of SEs.
PBMCs obtained from common marmosets were incubated with various concentrations of SEA, SEB, SEC, SEI, SEY or TSST-1 in 96-well round-bottomed tissue culture plates for 72 h and then uptake of [3H]-thymidine was measured. Data (in counts per min) are presented as the means ± SD of triplicate determinations.
Fig 2.
SEA binds with submucosal cells in the GI tract.
GI tissues (stomach, duodenum, jejunum, ileum, cecum and colon) were obtained from a common marmoset. Frozen tissues were sectioned (10 μm) and incubated with SEA (1.0 μg/ml) for 60 min at room temperature. After washing the sections with PBST, the sections were stained for SEA using rabbit anti-SEA antibody and Alexa 488-conjugated goat anti-rabbit IgG. Magnification, x20. Each scale bar is equal to 50 μm.
Fig 3.
SEA binds with mast cells in the submucosa of the GI tract.
Specimens of the intestinal tract were removed from a common marmoset. Frozen tissues were sectioned (10 μm) and incubated with SEA (1.0 μg/ml) for 60 min at room temperature. (A) GI sections were processed for double immunofluorescence staining using anti-SEA antibody (green) and anti-FcεRIα antibody (red), which detected the mast cell marker, IgE receptor. Each scale bar is equal to 20 μm.
Fig 4.
Characterization of SEA-binding mast cells.
Specimens of the intestinal tract were removed from a common marmoset. Frozen tissues were sectioned (10 μm) and incubated with SEA (1.0 μg/ml) for 60 min at room temperature. (A) Ileal sections were processed for double immunofluorescence staining using anti-SEA antibody (green) and anti-tryptase mAb (red), which recognizes the mast cell marker, tryptase. (B) Ileal sections were processed for double immunofluorescence staining using anti-FcεRIα antibody (green) and anti-5-HT antibody (red). (C) Ileal sections were processed for double immunofluorescence staining using anti-histamine antibody (green) and anti-FcεRIα antibody (red). Each scale bar is equal to 20 μm.
Fig 5.
SEA induces degranulation of mast cells.
Specimens of the intestinal tract were removed from a common marmoset at 2 h post-injection with 500 μg of SEA in the intestinal loop. (A) The number of metachromatic-staining cells in toluidine blue-stained jejunum sections was counted from 6 randomly selected areas. The number of submucosal metachromatic cells per square millimeter are presented as the mean ± SD, *P<0.05. (B) The jejunum sections in the intestine loop at 2 h after SEA or PBS injection were stained with toluidine blue. Mast cells are indicated as arrowheads in the SEA-injected loop and as arrows in the PBS-injected loop. The statistical analysis was performed using the Mann-Whitney U test.
Fig 6.
SEA induces the release of histamine from the GI tract.
Sections of common marmoset jejunum were incubated with or without SEA, and histamine and serotonin released from the jejunum were measured. (A) Jejunal sections were incubated with various concentrations of SEA for 2 h at 37°C in a CO2 incubator and histamine in the culture supernatant fluid was measured using ELISA. (B) Jejunal sections were incubated with 100μg of SEA and various concentrations of DSCG for 2 h and histamine in the culture supernatant fluid was measured using ELISA. (C) Jejunal sections were incubated with various concentrations of SEA for 2 h and 5-HT in the culture supernatant fluid was measured using ELISA. (D) Jejunal sections were incubated with 100 μg of SEA and various concentrations of DSCG for 2 h and 5-HT in the culture supernatant fluid was measured using ELISA. Each bar represents the mean ± SD from 8 jejunal pieces. The statistical analysis was performed using ANOVA followed by Tukey’s post hoc test, *P<0.05.
Fig 7.
Pharmacological effects on SEA-induced emesis.
Common marmosets were injected intraperitoneally with 200 mg/kg of DSCG (n = 6), 10 mg/kg of DPH (n = 6), 400 μg/kg of cetirizine (n = 6), 40 μg/kg of granisetron (n = 6), 200 μg/kg of granisetron (n = 6), 1000 μg/kg of granisetron (n = 6) or PBS (n = 11) and then administered 250 μg/kg of SEA 30 min later. To inhibit 5-HT synthesis, common marmosets were injected with PCPA (3500 mg/kg) over 2 consecutive days (n = 6) before SEA administration as described above. To deplete 5-HT in peripheral neurons without norepinephrine defects, common marmosets were pretreated with desipramine (25 mg/kg) for 60 min, then injected with 5 mg/kg of 5,7-DHT, followed by SEA administration as described above (n = 6). (A) The emetic response (percentage of vomited monkeys) and (B) its frequency were assessed as described in materials and methods. Each bar represents the mean ± SD. The statistical analysis was performed using Fisher’s exact test and Dunnett’s test, *P<0.05, **P<0.01, ***P<0.001.
Fig 8.
Stimulation of vomiting by SEA is transmitted via the vagus nerve.
Vagotomized (n = 6) and sham operated (n = 6) common marmosets were administered 40 mg/kg of copper sulfate (left panel). Alternatively, vagotomized (n = 6) and sham-operated (n = 8) common marmosets were administered 250 μg/kg of SEA (right panel). (A) The emetic response (percentage of vomited monkeys) and (B) its frequency were assessed as described in materials and methods. Each bar represents the mean ± SD. The statistical analysis was performed using Fisher’s exact test and the Mann-Whitney U test, *P<0.05.