Department of Biology & Evolution, University of Ferrara, St. Borsari 46, 44100 Ferrara, Italy.
Fish Shellfish Immunol. 2010 Mar;28(3):476-82. doi: 10.1016/j.fsi.2009.12.012. Epub 2009 Dec 24.
Annual losses of approximately 5-10% of the juvenile stock of European seabass, Dicentrarchus labrax (L.) in the northern coast of the Adriatic Sea has been attributed to heavy infections of the gill monogenean Diplectanum aequans. Immunocytochemical, light and ultrastructural studies were carried out on seabass naturally parasitized with this monogenean. The site of the worm's attachment was marked by the common presence of haemorrhages and white mucoid exudate. In histological sections, infected gills showed hyperplasia, as well as proliferation of mucous cells and rodlet cells. Disruption and fusion of the secondary lamellae were common in all infected seabass, with several specimens also showing marked inflammation and erosion of the primary and secondary lamellar epithelium. Immunostaining of primary and secondary gill filaments with an antibody against the antimicrobial peptide piscidin 3 (anti-piscidin 3 antibody, anti-HAGR) revealed a subpopulation of mast cells that were positive. Mast cells were both within and outside the blood vessels of the primary and secondary lamellae, and often made intimate contact with vascular endothelial cells. Mast cells were irregular in shape with a cytoplasm filled by numerous electron-dense, membrane-bound granules. Our data provide evidence showing the presence of piscidin 3 in the cytoplasmic granules of an important group of fish inflammatory cells, the mast cells resident in seabass gill tissue. There was no significant difference in the number of HAGR-positive mast cells between infected and uninfected fish (ANOVA, p > 0.05). However, mast cells in parasitized gills usually showed much stronger immunostaining intensity compared to those in unparasitized gills. These data are the first to document a response of piscidins or any other antimicrobial peptide of fish to parasite infection and suggest that mast cells may play a role in certain inflammatory responses without a detectable increase in their numbers.
每年约有 5-10%的欧洲海鲈（Dicentrarchus labrax (L.)）幼鱼在亚得里亚海北部海岸因严重感染鳃片单殖吸虫（Diplectanum aequans）而死亡。对受这种单殖吸虫自然感染的海鲈进行了免疫细胞化学、光镜和超微结构研究。蠕虫附着的部位通常有出血和白色粘脓性渗出物。在组织学切片中，受感染的鳃显示出增生，以及粘液细胞和棒状细胞的增殖。所有受感染的海鲈的次级鳃片都有明显的分裂和融合，一些标本还显示出初级和次级鳃片上皮的明显炎症和侵蚀。用针对抗菌肽海鳞肽 3（抗海鳞肽 3 抗体，抗-HAGR）的抗体对初级和次级鳃丝进行免疫染色，显示出一个阳性的肥大细胞亚群。肥大细胞位于初级和次级鳃片的血管内和血管外，并且经常与血管内皮细胞密切接触。肥大细胞形状不规则，细胞质内充满许多电子致密、膜结合的颗粒。我们的数据提供了证据，表明海鳞肽 3 存在于鱼体内重要的一组炎症细胞——肥大细胞的细胞质颗粒中，这些肥大细胞存在于海鲈鳃组织中。感染和未感染鱼之间的 HAGR 阳性肥大细胞数量没有显著差异（ANOVA，p > 0.05）。然而，受寄生虫感染的鳃中的肥大细胞通常比未受感染的鳃中的肥大细胞显示出更强的免疫染色强度。这些数据首次记录了鱼类抗菌肽或任何其他抗菌肽对寄生虫感染的反应，并表明肥大细胞可能在某些炎症反应中发挥作用，而其数量没有明显增加。
