Global climate change can influence organismic interactions like those between hosts and parasites. Rising temperatures may exacerbate the exploitation of hosts by parasites, especially in ectothermic systems. The metabolic activity of ectotherms is strongly linked to temperature and generally increases when temperatures rise. We hypothesized that temperature change in combination with parasite infection interferes with the host's immunometabolism. We used a parasite, the avian cestode Schistocephalus solidus, which taps most of its resources from the metabolism of an ectothermic intermediate host, the three‐spined stickleback. We experimentally exposed sticklebacks to this parasite, and studied liver transcriptomes 50 days after infection at 13°C and 24°C, to assess their immunometabolic responses. Furthermore, we monitored fitness parameters of the parasite and examined immunity and body condition of the sticklebacks at 13°C, 18°C and 24°C after 36, 50 and 64 days of infection. At low temperatures (13°C), S. solidus growth was constrained, presumably also by the more active stickleback's immune system, thus delaying its infectivity for the final host to 64 days. Warmer temperature (18°C and 24°C) enhanced S. solidus growth, and it became infective to the final host already after 36 days. Overall, S. solidus produced many more viable offspring after development at elevated temperatures. In contrast, stickleback hosts had lower body conditions, and their immune system was less active at warm temperature. The stickleback's liver transcriptome revealed that mainly metabolic processes were differentially regulated between temperatures, whereas immune genes were not strongly affected. Temperature effects on gene expression were strongly enhanced in infected sticklebacks, and even in exposed‐but‐not‐infected hosts. These data suggest that the parasite exposure in concert with rising temperature, as to be expected with global climate change, shifted the host's immunometabolism, thus providing nutrients for the enormous growth of the parasite and, at the same time suppressing immune defence.

中文翻译：

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气候变化通过温度介导的免疫代谢过程促进了寄生虫的宿主利用

全球气候变化会影响宿主和寄生虫之间的生物相互作用。温度升高可能会加剧寄生虫对宿主的利用，尤其是在吸热系统中。等温线的代谢活性与温度密切相关，通常在温度升高时增加。我们假设温度变化与寄生虫感染相结合会干扰宿主的免疫代谢。我们使用了一种寄生虫，即家禽尾est血吸虫，它的大部分资源都来自结温的中间宿主三棘刺背的代谢。我们通过实验将棘背back暴露于该寄生虫，并在感染后于13°C和24°C的第50天研究了肝转录组，以评估其免疫代谢反应。此外，我们监测了寄生虫的适应性参数，并在感染36、50和64天后在13°C，18°C和24°C下检查了the的免疫力和身体状况。在低温（13°C）下，固相链球菌的生长受到了限制，可能还受到了更活跃的棘背鸟的免疫系统的限制，从而将其对最终宿主的感染性延迟了64天。较暖的温度（18°C和24°C）增强了固相线生长，并且在36天后已经感染了最终宿主。总体而言，固结线虫在高温下发育后产生了更多的存活后代。相比之下，hosts背宿主的身体条件较低，在温暖的温度下其免疫系统活动性较低。棘背动物的肝脏转录组显示，主要的代谢过程在不同温度之间受到差异调节，而免疫基因并未受到强烈影响。温度对基因表达的影响在受感染的棘背，甚至暴露但未感染的宿主中均得到了显着增强。这些数据表明，正如全球气候变化所预期的那样，寄生虫暴露与温度升高相协调，改变了宿主的免疫代谢，从而为寄生虫的大量生长提供了营养，同时抑制了免疫防御。