Mechanism of Anticancer Host Response Induced by OK-432, a Streptococcal Preparation, Mediated by Phagocytosis and Toll-Like Receptor 4 Signaling
Mechanism of Anticancer Host Response Induced by OK-432, a Streptococcal Preparation, Mediated by Phagocytosis and Toll-Like Receptor 4 Signaling
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DOI：
10.1097/01.cji.0000192106.32206.30
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发表时间：
2006-01
影响因子：
3.9
通讯作者：
M. Okamoto;T. Oshikawa;T. Tano;S. Ahmed;Shi-feng Kan;Akiko Sasai;S. Akashi;K. Miyake;Y. Moriya;Yoshiki Ryoma;M. Saito;Mitsunobu Sato
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文献类型：
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作者：
M. Okamoto;T. Oshikawa;T. Tano;S. Ahmed;Shi-feng Kan;Akiko Sasai;S. Akashi;K. Miyake;Y. Moriya;Yoshiki Ryoma;M. Saito;Mitsunobu Sato
本课题组曾报道Toll样受体(TLR)4参与了链球菌来源的免疫治疗剂OK-432诱导的抗癌免疫。然而，OK-432通过TLR4诱导免疫反应的详细机制仍不清楚，因为OK-432由完整的细菌组成，可能不可能直接与TLR4结合。在目前的研究中，我们进行了体外和体内实验，以探讨OK-432可能首先被吞噬细胞捕获和溶解，然后由细胞释放的活性成分可能通过TLR4诱导宿主反应的假设。本研究使用的是识别OK-432活性成分OK-PSA的TS-2单抗。首先，观察到OK-432诱导的树突状细胞(DC)和巨噬细胞产生的细胞因子在体外被吞噬抑制因子细胞松弛素B显著抑制。TS-2免疫荧光染色显示OK-432被吞噬细胞捕获并溶解。用TS-2酶联免疫吸附试验检测OK-432处理的DC培养上清液中OK-PSA的表达。经OK-432处理的DC培养上清液可增强表达TLR4的细胞的核因子(NF)-κB活性，TS-2抗体可抑制这一作用。OK-432本身不能激活这些细胞中的核因子-κB。在体内实验中，细胞松弛素B抑制了OK-432的吞噬活性，显著抑制了OK-432的抗癌作用。细胞松弛素B还降低了OK-432的活性成分OK-PSA的含量。这些结果阐明了OK-432的免疫作用是由吞噬作用和TLR4信号介导的。
It has previously been reported by our group that Toll-like receptor (TLR) 4 is involved in anticancer immunity induced by OK-432, a Streptococcus-derived immunotherapeutic agent. However the detailed mechanism of the OK-432-induced immune response via TLR4 remained uncertain, because it may not be possible for OK-432, which consists of whole bacterial bodies, to bind directly to TLR4. In the current study, we conducted in vitro and in vivo experiments to investigate the hypothesis that OK-432 may first be captured and dissolved by phagocytes and that the active components released by the cells may then induce host responses via TLR4. TS-2 monoclonal antibody, which recognizes an active component of OK-432 designated OK-PSA was used in the current study. First, it was observed that OK-432-induced cytokine production by dendritic cells (DCs) and macrophages was significantly inhibited in vitro by cytochalasin B, a phagocytosis inhibitor. Immunofluorescence staining using TS-2 demonstrated that OK-432 was captured and dissolved by phagocytes. OK-PSA was detected in the supernatants derived from OK-432-treated DC culture by enzyme-linked immunosorbent assay using TS-2. Supernatants from OK-432-treated DC culture increased nuclear factor (NF)-κB activity in TLR4-expressing cells, and the increased activity was inhibited by TS-2 antibody. OK-432 itself did not activate NF-κB in these cells. In in vivo experiments, the anticancer effect of OK-432 was significantly inhibited by suppression of phagocytosis activity by cytochalasin B. In this case, the amount of OK-PSA, an active component of OK-432, in the sera was also reduced by cytochalasin B. These findings elucidated the mechanism mediated by phagocytosis and TLR4 signaling in the immune effect of OK-432.