Moredun Research Institute, Pentlands Science Park, Edinburgh, EH26 0PZ, UK.
Parasit Vectors. 2019 Jul 10;12(1):339. doi: 10.1186/s13071-019-3593-6.
The primary cause of parasitic gastroenteritis in small ruminants in temperate regions is the brown stomach worm, Teladorsagia circumcincta. Host immunity to this parasite is slow to develop, consistent with the ability of T. circumcincta to suppress the host immune response. Previous studies have shown that infective fourth-stage T. circumcincta larvae produce excretory-secretory products that are able to modulate the host immune response. The objective of this study was to identify immune modulatory excretory-secretory proteins from populations of fourth-stage T. circumcincta larvae present in two different host-niches: those associated with the gastric glands (mucosal-dwelling larvae) and those either loosely associated with the mucosa or free-living in the lumen (lumen-dwelling larvae).
In this study excretory-secretory proteins from mucosal-dwelling and lumen-dwelling T. circumcincta fourth stage larvae were analysed using comparative 2-dimensional gel electrophoresis. A total of 17 proteins were identified as differentially expressed, with 14 proteins unique to, or enriched in, the excretory-secretory proteins of mucosal-dwelling larvae. One of the identified proteins, unique to mucosal-dwelling larvae, was a putative peroxiredoxin (T. circumcincta peroxiredoxin 1, Tci-Prx1). Peroxiredoxin orthologs from the trematode parasites Schistosoma mansoni and Fasciola hepatica have previously been shown to alternatively activate macrophages and play a key role in promoting parasite induced Th2 type immunity. Here we demonstrate that Tci-Prx1 is expressed in all infective T. circumcincta life-stages and, when produced as a recombinant protein, has peroxidase activity, whereby hydrogen peroxide (HO) is reduced and detoxified. Furthermore, we use an in vitro macrophage stimulation assay to demonstrate that, unlike peroxiredoxins from trematode parasites Schistosoma mansoni and Fasciola hepatica, Tci-Prx1 is unable to alternatively activate murine macrophage cells.
In this study, we identified differences in the excretory-secretory proteome of mucosal-dwelling and lumen-dwelling infective fourth-stage T. circumcincta larvae, and demonstrated the utility of this comparative proteomic approach to identify excretory-secretory proteins of potential importance for parasite survival and/or host immune modulation.
温带地区小反刍动物寄生性胃肠炎的主要原因是棕色胃蠕虫，即细颈线虫。宿主对这种寄生虫的免疫反应发展缓慢，这与细颈线虫抑制宿主免疫反应的能力一致。先前的研究表明，感染性第四期细颈线虫幼虫产生的排泄-分泌产物能够调节宿主的免疫反应。本研究的目的是从存在于两种不同宿主小生境的第四期细颈线虫幼虫群体中鉴定出免疫调节的排泄-分泌蛋白：与胃腺相关的（黏膜栖息幼虫）和与黏膜松散相关或自由生活在腔中的（腔栖息幼虫）。
在这项研究中，使用比较 2 维凝胶电泳分析了黏膜栖息和腔栖息的细颈线虫第四期幼虫的排泄-分泌蛋白。共鉴定出 17 种差异表达蛋白，其中 14 种蛋白仅存在于或富集于黏膜栖息幼虫的排泄-分泌蛋白中。鉴定出的一种蛋白是一种假定的过氧化物酶（细颈线虫过氧化物酶 1，Tci-Prx1），仅存在于黏膜栖息幼虫中。先前已经表明，来自吸虫寄生虫曼氏血吸虫和肝片吸虫的过氧化物酶同源物可以选择性地激活巨噬细胞，并在促进寄生虫诱导的 Th2 型免疫中发挥关键作用。在这里，我们证明 Tci-Prx1 在所有感染性细颈线虫生命阶段都有表达，并且当作为重组蛋白产生时，具有过氧化物酶活性，从而还原和解毒过氧化氢（HO）。此外，我们使用体外巨噬细胞刺激试验证明，与吸虫寄生虫曼氏血吸虫和肝片吸虫的过氧化物酶不同，Tci-Prx1 无法选择性地激活鼠巨噬细胞。
在这项研究中，我们鉴定了黏膜栖息和腔栖息感染性第四期细颈线虫幼虫的排泄-分泌蛋白组的差异，并证明了这种比较蛋白质组学方法用于鉴定对寄生虫生存和/或宿主免疫调节具有潜在重要性的排泄-分泌蛋白的有效性。
