Neuroendocrine-immune (NEI) system programming of zebrafish embryos and larva: Implications for stress resilience, disease resistance, and longevity

牲畜和水产养殖物种经常受到各种压力，如微生物感染。神经内分泌免疫（NEI）系统在启动和调节宿主对应激的反应中起着核心作用，并有助于在应激事件后恢复生理稳态。NEI系统对产前和围产期压力源敏感，当它们在发育的某些窗口期经历时，NEI系统的编程可能受到永久性影响；尽管父亲的压力可能同样重要，但研究人员历来关注的是母亲和新生儿的压力。有人提出，早期发育过程中的NEI可塑性是一种适应性机制，有助于新生动物为出生后的环境做好准备；然而，当发育规划与后代最终生活的环境不匹配时，它可能会对应激恢复能力、抗病能力和寿命产生负面影响，所有这些都是加拿大牲畜和水产养殖生产者重要的健康、经济和福利问题。人类研究表明，由营养限制、创伤经历和微生物感染等压力源引起的发育中的NEI系统的压力诱发程序可以跨代表现出来，性别差异很常见；应力诱导的规划对家畜和水产养殖物种的生态环境内生态系统的影响在很大程度上是未知的。应激诱导编程发生的作用机制（MOA）才刚刚开始被理解，似乎涉及基因调控的永久变化。家养动物研究的一个主要限制是，它们非常昂贵和耗时，特别是在调查代际、亲代和性别影响以及MOA时。我们相信，作为一种新兴的脊椎动物模型，斑马鱼（Zf）有可能极大地促进我们对应激如何影响家畜和水产养殖物种NEI编程的理解。在本研究中，我们计划利用先天免疫应激源（微生物相关分子模式；MAMPs）建立Zf幼虫和成虫的免疫应激模型，以研究应激诱导的NEI系统编程，研究植物化学物质提供的保护作用，并探索MOA。由于鱼类缺乏重要的哺乳动物模式识别受体（PRR）同源物toll样受体4 (TLR4)，因此鉴定其他有助于识别作为TLR4配体的MAMPs的PRR将是重要的；它们可以作为基于营养或疫苗导向的免疫刺激的替代靶点，并且它们可能在物种间具有多态性，这对于增强抗病能力的遗传选择将是重要的。这项研究将帮助我们更好地理解应激诱导的NEI系统编程对发育中的动物的长期影响，并使我们能够研究可能由植物化学物质调节的调节过程，从而在不依赖抗菌剂的情况下促进后代健康。

Livestock and aquaculture species are routinely subjected to a variety of stressors such as microbial infections. The neuroendocrine-immune (NEI) system plays a central role in initiating and regulating the host response to stress and helps restore physiological homeostasis after a stress event. The NEI system is sensitive to prenatal and perinatal stressors, and when they are experienced during certain windows of development, NEI system programming can be permanently affected; researchers have historically focused on maternal and neonatal stress, although paternal stress may be equally important. It has been proposed that NEI plasticity during early development is an adaptive mechanism that helps newborn animals prepare for their postnatal environment; however, when developmental programming is mismatched to the environment that offspring ultimately reside in, it may negatively impact stress resilience, disease resistance and longevity, all of which are important health, economic and welfare concerns for Canadian livestock and aquaculture producers. Human studies have shown stress-induced programming of the developing NEI system, by stressors such as nutrient restriction, traumatic experiences and microbial infection, can manifest across generations, and sex differences are common; the impact of stress-induced programming on the NEI systems of livestock and aquaculture species is largely unknown. The mechanisms of action (MOA) by which stress-induced programming occurs are just beginning to be understood and appear to involve permanent changes in gene regulation.   A major limitation of domestic animal studies is that they are extremely costly and time consuming to perform, especially when generational, parental and sex effects, and MOA are investigated. We believe the zebrafish (Zf), which is an emerging vertebrate model, has the potential to greatly advance our understanding of how stress impacts NEI programming in livestock and aquaculture species. In this proposal, we plan to develop larval and adult Zf immune stress models using innate immune stressors (microbial-associated molecular patterns; MAMPs) to study stress-induced programming of the NEI system, investigate protection provided by phytochemicals, and explore MOA. Since fish lack an important mammalian pattern-recognition receptor (PRR) orthologue, Toll-like receptor 4 (TLR4), it will be important to identify other PRR that facilitate recognition of MAMPs that are TLR4 ligands; these may serve as alternate targets for nutrition-based or vaccine-directed immune stimulation, and they may be polymorphic across species, which will be important for genetic selection to enhance disese resistance. This research will help us to better understand the long-term impact of stress-induced NEI system programming in developing animals and will allow us to investigate regulatory processes that may be modulated by phytochemicals to promote offspring health without relying on antimicrobials.