Jiangsu Key Laboratory of Immunity and Metabolism, Department of Pathogenic Biology and Immunology, Laboratory of Infection and Immunity, Xuzhou Medical University, Xuzhou, P. R. China.
National Experimental Demonstration Center for Basic Medicine Education, Department of Clinical Medicine, Xuzhou Medical University, Xuzhou, P. R. China.
PLoS Negl Trop Dis. 2020 Oct 12;14(10):e0008643. doi: 10.1371/journal.pntd.0008643. eCollection 2020 Oct.
Clonorchis sinensis, a fluke dwelling in the intrahepatic bile ducts causes clonorchiasis, which affect about 15 million people wide-distributed in eastern Asia. During C. sinensis infection, worm-host interaction results in activation of patterns recognition receptors (PRRs) such as Toll-like receptors (TLRs) and further triggers immune responses, which determines the outcome of the infection. However, the mechanisms by which pathogen-associated molecules patterns from C. sinensis interact with TLRs were poorly understood. In the present study, we assumed that the molecules from C. sinensis may regulate host immune responses via TLR2 signaling pathway.
METHODOLOGY/PRINCIPAL FINDINGS: In the present study, we have identified a ~34 kDa CsHscB from C. sinensis which physically bound with TLR2 as demonstrated by molecular docking and pull-down assay. We also found that recombinant CsHscB (rCsHscB) potently activates macrophage to express various proteins including TLR2, CD80, MHCII, and cytokines like IL-6, TNF-α, and IL-10, but rCsHscB failed to induce IL-10 in macrophages from Tlr2-/- mice. Moreover, ERK1/2 activation was required for rCsHscB-induced IL-10 production in macrophages. In vivo study revealed that rCsHscB triggered a high production of IL-10 in the wild-type (WT) but not in Tlr2-/- mice. Consistently, the phosphorylation of ERK1/2 was also attenuated in Tlr2-/- mice compared to the WT mice, after the treatment with rCsHscB.
CONCLUSIONS/SIGNIFICANCE: Our data thus demonstrate that rCsHscB from C. sinensis interacts with TLR2 to be endowed with immune regulatory activities, and may have some therapeutic implications in future beyond parasitology.
华支睾吸虫（Clonorchis sinensis）是一种寄生在肝胆管内的吸虫，可引起华支睾吸虫病，该病广泛分布于东亚地区，影响约 1500 万人。在华支睾吸虫感染过程中，虫体与宿主的相互作用导致模式识别受体（PRRs）如 Toll 样受体（TLRs）的激活，并进一步引发免疫反应，这决定了感染的结局。然而，华支睾吸虫相关分子与 TLRs 相互作用的机制尚不清楚。在本研究中，我们假设华支睾吸虫的分子可能通过 TLR2 信号通路调节宿主免疫反应。
方法/主要发现：在本研究中，我们从华支睾吸虫中鉴定出一个约 34 kDa 的 CsHscB，分子对接和下拉实验表明其与 TLR2 具有物理结合。我们还发现重组 CsHscB（rCsHscB）能有效地激活巨噬细胞表达各种蛋白，包括 TLR2、CD80、MHCII 和细胞因子如 IL-6、TNF-α 和 IL-10，但 rCsHscB 不能诱导 TLR2-/- 小鼠巨噬细胞表达 IL-10。此外，ERK1/2 的激活是 rCsHscB 诱导巨噬细胞产生 IL-10 所必需的。体内研究表明，rCsHscB 在野生型（WT）小鼠中引发高水平的 IL-10 产生，但在 TLR2-/- 小鼠中则没有。一致地，在用 rCsHscB 处理后，TLR2-/- 小鼠 ERK1/2 的磷酸化也比 WT 小鼠减弱。
结论/意义：我们的数据表明，华支睾吸虫的 rCsHscB 与 TLR2 相互作用具有免疫调节活性，这可能对华支睾吸虫病的治疗有一定的意义。
