Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS, Canada, B3H 4R2.
J Exp Biol. 2023 Jul 1;226(14). doi: 10.1242/jeb.245861. Epub 2023 Jul 25.
Although skeletal muscle is a specialized tissue that provides the motor for movement, it also participates in other functions, including the immune response. However, little is known about the effects of this multitasking on muscle. We show that muscle loses some of its capacity while it is participating in the immune response. Caterpillars (Manduca sexta) were exposed to an immune challenge, predator stress or a combination of immune challenge and predator stress. The expression of immune genes (toll-1, domeless, cactus, tube and attacin) increased in body wall muscle after exposure to an immune challenge. Muscle also showed a reduction in the amount of the energy storage molecule glycogen. During an immune challenge, the force of the defensive strike, an important anti-predator behaviour in M. sexta, was reduced. Caterpillars were also less able to defend themselves against a common enemy, the wasp Cotesia congregata, suggesting that the effect on muscle is biologically significant. Our results support the concept of an integrated defence system in which life-threatening events activate organism-wide responses. We suggest that increased mortality from predation is a non-immunological cost of infection in M. sexta. Our study also suggests that one reason non-immunological costs of infection exist is because of the participation of diverse organs, such as muscle, in immunity.
虽然骨骼肌是一种提供运动动力的专门组织，但它也参与其他功能，包括免疫反应。然而，人们对这种多任务处理对肌肉的影响知之甚少。我们表明，肌肉在参与免疫反应时会丧失部分功能。我们将毛毛虫（Manduca sexta）暴露于免疫挑战、捕食者压力或免疫挑战和捕食者压力的组合中。暴露于免疫挑战后，体壁肌肉中的免疫基因（toll-1、domeless、cactus、tube 和 attacin）表达增加。肌肉中储能分子糖原的含量也减少了。在免疫挑战期间，毛毛虫防御性攻击的力度（Manduca sexta 的一种重要防御行为）降低。毛毛虫也更难抵御常见的敌人，即黄蜂 Cotesia congregata，这表明对肌肉的影响具有生物学意义。我们的结果支持了一个综合防御系统的概念，即在危及生命的事件中，激活全身反应。我们认为，捕食导致的死亡率增加是 M. sexta 感染的非免疫代价。我们的研究还表明，感染的非免疫代价存在的一个原因是，肌肉等多种器官参与了免疫反应。
