Antibacterial action of catechin on the cell invasive bacteria S.Enteritidis

儿茶素对细胞侵袭性肠炎沙门氏菌的抗菌作用

• 批准号: 11670273
• 负责人: OKUBO Sachie
• 金额: $ 1.98万
• 依托单位: Showa University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11670273/
• 关键词: S.Enteritidis; catechin; EGCg; THP-1; streptomycin; bactericidal activity; epithelial cell; macropage; Senteritidis

One of the major causative agents for bacterial food poisoning is Salmanella, the pathogenicity of which is mainly caused by the cell invasive ability in the intestinal canal. Green tea extracts and catechin are known to have antibacterial action against Salmonella Enteritidis (SE). To elucidate the effects of catechin on the bacteria-host cell interaction, we investigated such a relationship using various cultured cell lines and macrophages (M φ) collected form the intraperitoneal cells of BALB/c mice.1. Cultured cells were exposed to SE that was treated with less than the MIC of catechin (12.5-100μg/ml, epigallocatechin gallate : EGCg) for 1-2 hours. There were no differences in intracellular invation and proliferation between treated and untreated THP-1 cells (human monocyte cell line). However, the intracellular proliferation of SE was suppressed using peritoneal macrophage (resident M φ).2. Cultured cells pretreated with catechin (25-50μg/ml) for a certain length of time were expo … More sed to SE.There was a clear increase in phagocytosis for THP-1 cells, but the intracellular proliferation of SE in these cells could not be suppressed.3. Peritoneal macrophages from mice pre-treated with catechin (P-100 500μg/mouse×3ip) were exposed to SE.Phagocytic and bactericidal activity were observed to increase.4. GSM 06 cell (mouse mucosal epithelial cell line) per-treated with exposed to SE.Changes in the number of intracellular viable cell counts determined by CFU were compared with those of untreated GSM 06 cells. The results showed that the intracellular invasion and proliferation of SE could not be prevented.As a result, epithelial cells (Hep-2 and intestine 407) were pretreated with EGCg (0.5-50μg/ml) for a certain length of time and then exposed to SE for 1-2 hours. After there incubation under 5% CO, at 37℃, the cells were stained using either a Giemsa or Gram stain before being examined under a microscope ot determine intracellular invasion and proliferation. The results showed that SE invaded these cells and proliferated in the cytoplasm of many of these. The above findings suggest that catechin directly and indirectly stimulates the activation of macrophages. However, catechin did not inhibit the intracellular invation and proliferation of SE in mucosal epithelial cells, which are non-phagocytic cells.Furthermore, the direct bactericidal activity of catechin on highly streptomycin (SM)-resistant SE (clinical isolates : MIC>50μg/ml) was weaker than that on SE-sensitive strains. Less

细菌性食物中毒的主要病原之一是沙门氏菌，其致病机制主要是由于肠道内的细胞侵袭能力所致。已知绿茶提取物和儿茶素对肠炎沙门氏菌(SE)有抗菌作用。为了阐明儿茶素对细菌-宿主细胞相互作用的影响，我们使用从BALB/c小鼠腹膜细胞中收集的不同培养细胞系和巨噬细胞(Mφ)来研究这种关系。将培养的细胞置于低于儿茶素最低抑菌浓度(12.5~10 0μg/ml，表没食子儿茶素没食子酸酯：EGCG)的SE中处理1~2小时。THP-1细胞(人单核细胞系)在细胞内侵袭和增殖方面与未经处理的THP-1细胞无差异。然而，腹膜巨噬细胞(常驻Mφ)抑制了SE的细胞内增殖。培养的细胞经儿茶素(25-50μg/ml)处理一定时间后，即可检测到…THP-1细胞吞噬功能明显增强，但不能抑制细胞内SE的增殖。将经儿茶素(P-100,500μg/只×3ip)处理的小鼠腹腔巨噬细胞暴露于SE后，其吞噬功能和杀菌活性均增强。细胞内活细胞数的变化由CFU测定，并与未处理的GSM 06细胞进行比较。结果表明，SE的细胞内侵袭和增殖不能被阻止，其结果是用EGCG0.5~50μg/ml预先处理一段时间后，再暴露于SE中1~2小时。在37℃、5%CO下孵育后，对细胞进行Giemsa或Gram染色，然后在显微镜下观察细胞内侵袭和增殖情况。结果表明，SE侵袭了这些细胞，并在其中许多细胞的胞浆中增殖。以上研究结果提示，儿茶素可直接或间接刺激巨噬细胞的活化。然而，儿茶素不能抑制非吞噬细胞--粘膜上皮细胞中SE的细胞内侵入和增殖，而且儿茶素对链霉素高度耐药的SE(临床分离株：MIC和GT；50μg/ml)的直接杀菌活性弱于对SE敏感的菌株。较少