Trans-kingdom cross-talks in the Giardia-infected gut and regulatory effects of the diet

我的NSERC DG项目使用肠道寄生虫贾第虫来更好地了解基本的肠道生理学。贾第虫是一种人畜共患的肠道寄生虫，引起宠物腹泻，并造成牲畜的重大损失。目的：评估贾第虫细胞外囊泡（EV）如何改变肠道微生物群细菌和劫持宿主上皮受体的行为，以破坏肠道内稳态。然后，研究将确定膳食脂肪如何影响这些途径，这与我了解肠道生物学在现实生活中的复杂性的长期目标一致。具体目标：1.贾第虫EV的表征：研究将使用最先进的纳米粒子跟踪，透射电子显微镜，蛋白质组学和小RNA测序来表征贾第虫EV及其内容物。我们将评估贾第虫EV如何影响微生物群细菌的生长和运动，以促进细菌入侵。2.贾第虫和EV对宿主细胞受体的影响：我们将确定贾第虫诱导的肠道粘液破坏如何可能涉及寄生虫对杯状细胞上蛋白酶激活受体2（PAR-2）的激活。研究将表征粘蛋白质响应贾第虫的糖基化。聚糖（半乳糖、岩藻糖、唾液酸）在肠道粘液与微生物群的相互作用中起关键作用。然后，研究将评估贾第虫EV如何与这些影响有关。3.贾第虫-簇状细胞相互作用：我们将确定新发现的肠道簇状细胞响应贾第虫的动力学和信号机制（受体激活和免疫激活），对寄生虫负荷和微生物群破坏的后果，并确定这些相互作用如何影响肠道稳态。4.高脂肪饮食的影响：使用小鼠贾第虫感染模型，研究将比较低脂或高脂肪“西方”饮食（富含脂肪酸）对感染，炎症，上皮完整性，杯状细胞生物学，肠道运动和粪便水含量（作为腹泻的标志物）以及肠道微生物群完整性的影响。研究将评估膳食脂肪酸（棕榈酸和油酸）对肠道上皮细胞的影响。我们将确定这些膳食脂肪酸如何改变贾第虫EV的产生和特征。研究将比较男性和女性的影响，以更好地了解感染后肠易激综合征等现象的性别依赖性。这些发现将有助于设计新的基于饮食的贾第鞭毛虫病缓解策略。重要性：使用贾第虫模型系统，这些研究将揭示肠道内稳态的新的跨王国生理和微生物调节剂。该补助金将为HQP提供大量的培训机会，使其能够在研究，政府和行业中发展，这与我的培训记录一致。这些发现将有助于推动加拿大及其他地区的胃肠道研究，并为农业部门和加拿大人带来重大利益。

My NSERC DG program uses the intestinal parasite Giardia to better understand basic gut physiology. Giardia is a zoonotic intestinal parasite, causes diarrhea in pets, and is responsible for significant losses in livestock. Objective: To assess how Giardia extracellular vesicles (EVs) alter the behaviour of gut microbiota bacteria and highjack host epithelial receptors to disrupt intestinal homeostasis. Studies will then determine how dietary fat may affect these pathways, consistent with my long-term goal of understanding gut biology in its real-life complexity. Specific objectives: 1. Characterization of Giardia EVs: Studies will characterize Giardia EVs and their contents, using state-of-the art nanoparticle tracking, transmission electron microscopy, proteomics, and small RNA sequencing. We will assess how Giardia EVs affect the growth and motility of microbiota bacteria to facilitate bacterial invasion. 2. Effects of Giardia and EVs on host cell receptors: We will determine how Giardia-induced gut mucus disruptions may implicate activation of Proteinase-Activated Receptor 2 (PAR-2) on goblet cells by the parasite. Studies will characterize glycosylation of mucin proteins in response to Giardia. Glycans (galactose, fucose, sialic acid) play key roles in the interactions of gut mucus with microbiota. Studies will then assess how Giardia EVs may be implicated in the effects. 3. Giardia - tuft cells interactions: We will determine the kinetics and signalling mechanisms (receptor activation and immune activation) of newly discovered intestinal tuft cells in response to Giardia, the consequences on parasite burden and on microbiota disruptions, and determine how these interactions may affect intestinal homeostasis. 4. Effects of a high fat diet: Using models of Giardia infection in mice, studies will compare effects of Low Fat or High Fat "Western" diets (rich in fatty acids) on infection, inflammation, epithelial integrity, goblet cell biology, intestinal motility and fecal water contents as markers of diarrhea, and gut microbiota integrity. Studies will assess effects of dietary fatty acids (palmitic and oleic) on gut epithelia. We will determine how these dietary fatty acids may alter the production and characteristics of Giardia EVs. Studies will compare effects in males and females to better understand the sex-dependence of phenomena such as post-infectious Irritable Bowel Syndrome. The findings will help devise new diet-based mitigation strategies for giardiasis, and beyond. Significance: Using Giardia model systems, the studies will unravel novel trans-kingdom physiological and microbial regulators of intestinal homeostasis. The grant will provide numerous opportunities for HQP training towards careers in research, government, and industry, consistent with my training record. The findings will help advance gastrointestinal research in Canada and beyond, and yield significant benefits to the agricultural sector and to Canadians.