BACKGROUND The multifaceted interactions between gastrointestinal (GI) helminth parasites, host gut microbiota and immune system are emerging as a key area of research within the field of host-parasite relationships. In spite of the plethora of data available on the impact that GI helminths exert on the composition of the gut microflora, whether alterations of microbial profiles are caused by direct parasite-bacteria interactions or, indirectly, by alterations of the GI environment (e.g. mucosal immunity) remains to be determined. Furthermore, no data is thus far available on the downstream roles that qualitative and quantitative changes in gut microbial composition play in the overall pathophysiology of parasite infection and disease. RESULTS In this study, we investigated the fluctuations in microbiota composition and local immune microenvironment of sheep vaccinated against, and experimentally infected with, the 'brown stomach worm' Teladorsagia circumcincta, a parasite of worldwide socio-economic significance. We compared the faecal microbial profiles of vaccinated and subsequently infected sheep with those obtained from groups of unvaccinated/infected and unvaccinated/uninfected animals. We show that alterations of gut microbial composition are associated mainly with parasite infection, and that this involves the expansion of populations of bacteria with known pro-inflammatory properties that may contribute to the immunopathology of helminth disease. Using novel quantitative approaches for the analysis of confocal microscopy-derived images, we also show that gastric tissue infiltration of T cells is driven by parasitic infection rather than anti-helminth vaccination. CONCLUSIONS Teladorsagia circumcincta infection leads to an expansion of potentially pro-inflammatory gut microbial species and abomasal T cells. This data paves the way for future experiments aimed to determine the contribution of the gut flora to the pathophysiology of parasitic disease, with the ultimate aim to design and develop novel treatment/control strategies focused on preventing and/or restricting bacterial-mediated inflammation upon infection by GI helminths. Video Abstract.

中文翻译：

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绵羊胃肠道线虫 Teladorsagiacircincta 的感染会增加管腔病原体。

背景胃肠道（GI）蠕虫寄生虫、宿主肠道微生物群和免疫系统之间的多方面相互作用正在成为宿主-寄生虫关系领域内的一个关键研究领域。尽管关于胃肠道蠕虫对肠道菌群组成的影响有大量数据，但微生物谱的改变是由直接寄生虫-细菌相互作用引起的，还是间接由胃肠道环境的改变（例如粘膜免疫）引起的。 ）仍有待确定。此外，迄今为止还没有关于肠道微生物组成的定性和定量变化在寄生虫感染和疾病的整体病理生理学中所起的下游作用的数据。结果在这项研究中，我们调查了接种“棕胃虫”Teladorsagiacircincta（一种具有全球社会经济意义的寄生虫）并进行实验感染的绵羊的微生物群组成和局部免疫微环境的波动。我们将接种疫苗和随后感染的绵羊的粪便微生物特征与从未接种/感染和未接种/未感染的动物组中获得的粪便微生物特征进行了比较。我们表明，肠道微生物组成的改变主要与寄生虫感染有关，这涉及具有已知促炎特性的细菌种群的扩张，这可能有助于蠕虫病的免疫病理学。使用新的定量方法来分析共聚焦显微镜衍生的图像，我们还表明 T 细胞的胃组织浸润是由寄生虫感染驱动的，而不是抗蠕虫疫苗接种。结论 Teladorsagiacircumcincta 感染导致潜在促炎性肠道微生物种类和皱胃 T 细胞的扩增。这些数据为未来的实验铺平了道路，旨在确定肠道菌群对寄生虫病病理生理学的贡献，最终目标是设计和开发新的治疗/控制策略，重点是预防和/或限制感染时细菌介导的炎症由胃肠道蠕虫引起。视频摘要。