The role of commensal microflora in the inane immune response during infection

在实验性小鼠脓毒症模型中，我们研究了消化共生细菌在先天免疫反应中的作用。实验小鼠用含有多种抗生素(链霉素和头孢噻肟)的水喂养3周。试验组的共生细菌数量显著减少，肠道有机酸谱也发生了变化。通过流式细胞仪检测，巨噬细胞TLR-4和TLR-2受体的表达明显下调。模拟临床脓毒症，注射脂多糖后，血浆肿瘤坏死因子-α水平的升高已经减弱。这种下降伴随着死亡率的增加。这些数据表明，消化道中的共生细菌菌群可能在调节先天免疫系统方面发挥重要作用。在脓毒症的治疗中，应考虑抗菌药物通过改变共生菌群的免疫调节作用。

We investigated the role of digestive commensal bacteria in the innate immune response in experimental mouse sepsis model. Experimental mice were fed by water including multiple antibiotics (streptomycin and cefotaxime) for three weeks. Significant decreases in the amount of commensal bacterial flora, as well as the changes in intestinal organic acid profiles were noted in the experimental group. The expressions of TLR-4 and TLR-2 receptors in the peritoneal macrophages assessed by flow-cytometry, have been significantly downregulated. The increase in plasma TNF-α level after lipopolysaccharide injection, mimicking clinical sepsis, has been attenuated. This attenuation was accompanied with the increases in the mortality. Those data suggests that commensal bacterial flora in the digestive tract might confer a significant role in modulating innate immune system. The immunomodulating effect of antimicrobials via the changes in commensal microflora should be considered in the sepsis treatment.