Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China; University of Chinese Academy of Sciences, Beijing, China.
Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China.
Exp Cell Res. 2018 Sep 15;370(2):237-244. doi: 10.1016/j.yexcr.2018.06.024. Epub 2018 Jun 27.
As a kind of superantigen, staphylococcal enterotoxin C2 (SEC2) is well known as a powerful immunomodulator. However, most previous studies about SEC2 focus on its T cell activating characters. But the direct effect of SEC2 on antigen-presenting cells (APCs) which are important for the T cell activation is not clearly. In this study, we investigated the effect of SEC2 on murine bone marrow-derived dendritic cells (BMDCs) which are known as the specialized professional APCs. Contrary to its effects on T cells, SEC2 could not induce proliferation or cytotoxicity to BMDCs even in high concentrations. While SEC2 could promote the mature of BMDCs with increased expression of co-stimulatory molecules on cell membrane such as CD80, CD86, and MHC II. The production of pro-inflammatory cytokines such as TNF-α, IFN-γ and IL-6 were also increased in BMDCs treated with SEC2. We also found that SEC2 enhanced the genes expression of pattern recognition receptors including toll-like receptors 2 (TLR2) and TLR4 in BMDCs, and up-regulated the key signal molecule MyD88 in both mRNA and protein levels. In addition, SEC2 also caused IκBα degradating and NFκB p65 translocating from the cytoplasm to the nucleus in BMDCs. The siRNAs for both TLR2 and TLR4, as well as NFκB specific inhibitor BAY 11-7085 could inhibit the co-stimulatory molecules expression and pro-inflammatory cytokines releasing induced by SEC2. Moreover, TLR2/4 specific siRNAs inhibited p65 and MyD88 upregulation induced by SEC2. In summary, all our results indicated that SEC2 could stimulate BMDCs maturation through TLR-NFκB signaling pathways.
作为一种超抗原,葡萄球菌肠毒素 C2(SEC2)是一种强大的免疫调节剂,这是众所周知的。然而,大多数先前关于 SEC2 的研究都集中在其 T 细胞激活特性上。但是 SEC2 对 T 细胞活化所必需的抗原呈递细胞(APC)的直接作用尚不清楚。在这项研究中,我们研究了 SEC2 对已知是专门的专业 APC 的鼠骨髓来源树突状细胞(BMDC)的影响。与它对 T 细胞的作用相反,即使在高浓度下,SEC2 也不能诱导 BMDC 增殖或细胞毒性。虽然 SEC2 不能诱导 BMDC 增殖或细胞毒性,但它可以促进 BMDC 的成熟,增加细胞膜上共刺激分子的表达,如 CD80、CD86 和 MHC II。用 SEC2 处理的 BMDC 中促炎细胞因子如 TNF-α、IFN-γ和 IL-6 的产生也增加。我们还发现 SEC2 增强了 BMDC 中模式识别受体(包括 TLR2 和 TLR4)的基因表达,并在 mRNA 和蛋白质水平上调了关键信号分子 MyD88。此外,SEC2 还导致 BMDC 中的 IκBα降解和 NFκB p65从细胞质转移到细胞核。TLR2 和 TLR4 的 siRNAs 以及 NFκB 特异性抑制剂 BAY 11-7085 均可抑制 SEC2 诱导的共刺激分子表达和促炎细胞因子释放。此外,TLR2/4 特异性 siRNAs 抑制了 SEC2 诱导的 p65和 MyD88 上调。总之,我们的所有结果表明 SEC2 可以通过 TLR-NFκB 信号通路刺激 BMDC 成熟。