New paradigm of staphylococcal food poisoning

在本研究中，我们建立了金黄色葡萄球菌肠毒素(SES)和葡萄球菌肠毒素样毒素(SEL)的敏感免疫学检测方法(化学发光夹心法)。用双抗体夹心ELISA法检测了几株金黄色葡萄球菌SES/SEL的产生，发现在低温(25℃)培养条件下，某些SES/SEL组(SEG、SEI、SELM、SELM和SELO)的产生水平高于常规培养条件(37℃)。这一现象可能对理解这些SE/SEL在食物中毒中的作用很重要。我们还利用家麝鼠(Suncus Murinus)在体内研究了SEA在胃肠道中的行为。GI切片的免疫荧光显示，口服SEA从管腔转移到胃肠道内部组织，并迅速聚集在某些粘膜下层细胞中。粘膜下层的SEA结合细胞均为类胰蛋白酶和FcRI阳性，提示这些SEA结合细胞为肥大细胞。SEA结合可诱导黏膜下肥大细胞脱颗粒和释放5-羟色胺。提示SEA的靶细胞是胃肠道粘膜下肥大细胞，粘膜下肥大细胞释放的5-羟色胺在SEA引起的呕吐中起重要作用。

In this study, we developed sensitive immunological detection method (chemi-luminescence sandwich ELISA) of staphylococcal enterotoxins (SEs) and staphylococcal enterotoxin-like toxins (SEls). Using sandwich ELISA, we examined production of SEs/SEls in several Staphylococcus aureus strains and found that production level of certain SEs/SEls group (SEG, SEI, SElM, SElM and SElO) enhanced in culture condition with low temperature (25℃) than conventional culture condition (37℃). This phenomenon may be important to understand the role of these SEs/SEls in food poisoning. We also investigated the behavior of SEA in the gastrointestinal (GI) tract in vivo using the house musk shrew (Suncus murinus). Immunofluorescence of GI sections showed that perorally administered SEA translocated from the lumen to the interior tissues of the GI tract and rapidly accumulated in certain submucosa cells. These SEA-binding cells in the submucosa were both tryptase- and FcRI-positive, suggesting these SEA-binding cells were mast cells. SEA binding induced degranulation and release of 5-HT from submucosal mast cells. These observations suggest that the target cells of SEA are submucosal mast cells in the GI tract and that 5-HT released from submucosal mast cells plays an important role in SEA-induced emesis.