金葡菌肠毒素B在烫伤脓毒症大鼠早期肠损害中的作用及意义

目的：探讨金黄色葡萄球菌肠毒素B(SEB)在烫伤脓毒症大鼠早期肠损害中的作用。方法：雄性Wistar大鼠86只，随机分为正常对照组（n=10）、烫伤对照组（n=10）、烫伤后金葡菌感染组（n=50）和SEB单克隆抗体（单抗）拮抗组（n=16）。留取血样品测定SEB、内毒素、肿瘤坏死因子-α（TNF-α）和干扰素-γ（IFN-γ）水平；同时测定组织内毒素水平及小肠组织二胺氧化酶（DAO）活性。结果：烫伤后金葡菌感染动物血浆SEB、TNF-α和IFN-γ水平均显著高于正常对照组，并于2 h、6 h达峰值（P<0.05或P<0.01），此后降低；而小肠组织DAO活性则持续低于对照组（P<0.05）。相关分析显示，小肠组织DAO活性与血浆SEB水平呈显著负相关（r=-0.4398，P<0.05）。此外，金葡菌攻击后动物血浆及心、肝、肺、肾等组织中内毒素含量亦明显高于正常和烫伤对照组水平（P<0.05）；SEB单抗干预可不同程度抑制血浆及组织内毒素水平的变化，其中伤后2 h肾脏改变显著（P<0.05）。结论：在严重烫伤后金葡菌感染时，金葡菌的重要致病因子－SEB可加重动物小肠粘膜屏障功能损害，促进肠源性内毒素移位并蓄积于局部组织，后者可能与金葡菌致病因子协同作用导致脓毒症的病理生理过程进一步恶化。

The potential role of staphylococcal enterotoxin B in the early intestinal injury in postburn Staphylococcus aureus sepsis

AIM: To investigate the role of staphylococcal enterotoxin B (SEB) in early intestinal injury in scald rats with Staphylococcus aureus sepsis. METHODS: 86 male Wistar rats were randomly divided into four groups as folows: normal controls (n=10), scald control group(n=10), postburn sepsis group (n=50) and SEB monoclonal antibody (MAb) treatment group (n=16). Plasma samples were collected to determine SEB, endotoxin, tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ). RESULTS: After scald injury followed by Staphylococcus aureus challenge, the levels of SEB, TNF-α and IFN-γ in plasma were significantly higher than those of normal controls, peaking at 2-6 h (P<0.05 or P<0.01), while the intestinal diamine oxidase (DAO) activity declined constantly (P<0.05). It was shown that plasma SEB levels were significant negatively correlated with intestinal DAO activity (r=-0.4398, P=0.0170), and SEB MAb pretreatment could ameliorate the intestinal injury to certain extent. Moreover, Staphylococcus aureus challenge could increase the endotoxin levels in plasma and various tissues, which were attenuated by SEB MAb pretreatment. CONCLUSION: In postburn sepsis, SEB might be involved in the development of intestinal barrier dysfunction, which in turn resulting in gut-derived endotoxin translocation and aggravating the pathophysiologic changes caused by Staphylococcus aureus challenge.