Evolutionary Ecology, Max Planck Institute for Evolutionary Biology, Plön, Germany.
Marine Evolutionary Ecology, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.
Mol Ecol. 2019 May;28(10):2668-2680. doi: 10.1111/mec.15106. Epub 2019 May 17.
Parasites are one of the strongest selective agents in nature. They select for hosts that evolve counter-adaptive strategies to cope with infection. Helminth parasites are special because they can modulate their hosts' immune responses. This phenomenon is important in epidemiological contexts, where coinfections may be affected. How different types of hosts and helminths interact with each other is insufficiently investigated. We used the three-spined stickleback (Gasterosteus aculeatus) - Schistocephalus solidus model to study mechanisms and temporal components of helminth immune modulation. Sticklebacks from two contrasting populations with either high resistance (HR) or low resistance (LR) against S. solidus, were individually exposed to S. solidus strains with characteristically high growth (HG) or low growth (LG) in G. aculeatus. We determined the susceptibility to another parasite, the eye fluke Diplostomum pseudospathaceum, and the expression of 23 key immune genes at three time points after S. solidus infection. D. pseudospathaceum infection rates and the gene expression responses depended on host and S. solidus type and changed over time. Whereas the effect of S. solidus type was not significant after three weeks, T regulatory responses and complement components were upregulated at later time points if hosts were infected with HG S. solidus. HR hosts showed a well orchestrated immune response, which was absent in LR hosts. Our results emphasize the role of regulatory T cells and the timing of specific immune responses during helminth infections. This study elucidates the importance to consider different coevolutionary trajectories and ecologies when studying host-parasite interactions.
寄生虫是自然界中最强的选择因素之一。它们选择宿主进化出对抗感染的适应性策略。寄生虫特别之处在于它们可以调节宿主的免疫反应。这种现象在流行病学背景下很重要，因为可能会影响共感染。不同类型的宿主和寄生虫之间如何相互作用的研究还不够充分。我们使用三刺鱼（Gasterosteus aculeatus）-棘隙吸虫（Schistocephalus solidus）模型来研究寄生虫免疫调节的机制和时间组成。来自两个具有高抵抗力（HR）或低抵抗力（LR）的棘隙吸虫的三刺鱼个体分别暴露于棘隙吸虫菌株中，这些菌株在 G. aculeatus 中具有高生长（HG）或低生长（LG）特性。我们确定了对另一种寄生虫，眼吸虫（Diplostomum pseudospathaceum）的易感性，以及在 S. solidus 感染后三个时间点的 23 个关键免疫基因的表达。D. pseudospathaceum 感染率和基因表达反应取决于宿主和 S. solidus 类型，并随时间而变化。尽管在三周后 S. solidus 类型的影响不显著，但如果宿主感染了 HG S. solidus，则 T 调节反应和补体成分在后期时间点上调。HR 宿主表现出协调良好的免疫反应，而 LR 宿主则没有。我们的结果强调了调节性 T 细胞的作用以及在寄生虫感染期间特定免疫反应的时间。这项研究阐明了在研究宿主-寄生虫相互作用时考虑不同的共同进化轨迹和生态的重要性。
