Laboratory of Ascidian Biology, Department of Biology, University of Padova, Padova, Italy.
Laboratory of Ascidian Biology, Department of Biology, University of Padova, Padova, Italy.
J Invertebr Pathol. 2018 Nov;159:28-40. doi: 10.1016/j.jip.2018.10.012. Epub 2018 Oct 22.
Thaliaceans are pelagic tunicates that play a key role in trophic chains of the oceans. In the field of tunicate immunity, a notable gap is the lack of data on their inflammatory response. The common salp, Thalia democratica, possesses scant immunocytes, represented by a phagocytic line (hyaline amebocytes) and a mast cell-like line (granular cells). We aimed to provide the first investigation of defense reactions upon exposure to a large amount of bacteria (Bacillus clausii). We detected (i) bacterial phagocytosis by hyaline amebocytes, (ii) degradation of phagocytizing hyaline amebocytes in the tunic after transcellular diapedesis from the hemocoel, and (iii) release of heparin, histamine, and TNF-α by granular cells. Cell degranulation and phagocytosis occurred in epidermal cells lining the hemocoel, and an excess of mucus was observed in the post-branchial gut, causing a functional inhibition of cilia and microvilli. These findings indicate multi-step events comparable to an inflammation involving responses at both tissue and organismal levels.
短尾下口鲇是一种远洋被囊动物，在海洋食物链中起着关键作用。在被囊动物免疫领域，一个显著的空白是缺乏关于其炎症反应的数据。普通海鞘（Thalia democratica）拥有少量的免疫细胞，由吞噬细胞（透明阿米巴细胞）和肥大细胞样细胞（颗粒细胞）组成。我们旨在首次研究在大量细菌（枯草芽孢杆菌）暴露下的防御反应。我们检测到（i）透明阿米巴细胞吞噬细菌，（ii）吞噬透明阿米巴细胞从血腔穿过细胞层在被囊内降解，和（iii）颗粒细胞释放肝素、组织胺和 TNF-α。细胞脱颗粒和吞噬作用发生在包绕血腔的表皮细胞中，并且在后鳃裂肠中观察到过量的黏液，导致纤毛和微绒毛的功能抑制。这些发现表明涉及组织和机体水平反应的类似炎症的多步事件。
