Proximate and ultimate causes of immune/behavioural interactions

压力(急性和慢性)降低了人类和动物对疾病的抵抗力。免疫细胞已经进化出压力荷尔蒙的受体，这表明压力诱导的免疫功能变化提供了一些好处。然而，这些好处往往是不清楚的，部分原因是脊椎动物的免疫系统很难研究。我们的实验室在一个更简单的昆虫系统中研究这个问题。一个更简单的系统是有帮助的，因为回答这个问题需要跨越多个层次的分析(例如，从分子到行为)的实验，以及对生理机制及其进化意义的检查。和哺乳动物一样，昆虫也有一种应激激素(即章鱼胺)。它还会抑制抗病能力。在这项研究中，我们测试了压力反应是否选择性地抑制了与之冲突的免疫功能。例如，压力和免疫反应都会产生氧化应激。如果这两种功能都被完全激活，导致的组织损伤可能会导致比应激导致的疾病抵抗力下降更大的存活率下降。我预测，压力荷尔蒙会重新调整免疫反应，从而减少对组织损伤机制的依赖。这一假说可以帮助解释为什么压力荷尔蒙既能增强抗病能力，又能抑制抗病能力。这项研究有可能为为什么应激激素改变免疫功能以及为什么长期应激降低疾病抵抗力这一长期问题提供新的见解。了解为什么压力荷尔蒙会降低免疫力也有实际原因。有人建议，这些作用应该被药物阻断。在不了解其功能的情况下，阻止这些古老的保守反应的表达可能会带来意想不到的负面后果。这项研究还研究了气候变化将如何改变长期应激对昆虫抗病能力的影响。我预测，气温升高将加剧慢性应激导致的抗病能力下降。昆虫对疾病抵抗力的降低将对陆地生态系统和人类健康产生深远影响(例如，如果这增加了昆虫感染西尼罗河病毒等疾病的机会)。

Stress (both acute and chronic) decreases the resistance of humans and animals to disease. Immune cells have evolved receptors for stress hormones, suggesting that stress-induced changes in immune function provide some benefit. However, these benefits are often unclear, in part because the vertebrate immune system is difficult to study. Our lab examines this question in a simpler insect system. A simpler system is helpful, because answering this question requires experiments spanning multiple levels of analysis (e.g. molecular to behavioural), and an examination of both the physiological mechanisms and their evolutionary significance. As in mammals, insects have a stress hormone (i.e. octopamine). It also depresses disease resistance. In this study, we test whether the stress response selectively depresses immune functions that conflict with it. For example, both the stress and immune responses generate oxidative stress. If both functions were fully activated, the resulting tissue damage may cause even greater declines in survival than stress-induced reductions in disease resistance. I predict that stress hormones reconfigure the immune response so that it relies less on tissue damaging mechanisms. This hypothesis could help explain why stress hormones can both enhance and depress disease resistance. This study has the potential to offer fresh insights into the perennial issue of why stress hormones alter immune function and why chronic stress reduces disease resistance. There are also practical reasons for knowing why stress hormones reduce immunity. It has been suggested that these effects should be blocked by drugs. Without knowing their function, preventing the expression of these ancient conserved responses may bring unintended negative consequences. This study also examines how climate change will alter the impact of chronic stress on disease resistance in insects. I predict that increased temperature will exacerbate the decline in disease resistance caused by chronic stress. Reduced disease resistance in insects will have profound effects on the terrestrial ecosystem and human health (e.g. if it increases the chance that insects will become infected with diseases like West Nile Virus).