School of Life Sciences, Ludong University, Yantai, 264025, China.
The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong, China.
Fish Shellfish Immunol. 2020 Mar;98:391-400. doi: 10.1016/j.fsi.2020.01.049. Epub 2020 Jan 25.
Bacterial enteritis is an important deadly threat to farmed seahorses. However, its pathogenesis is obscure because of the paucity of reproducible experimental intestinal inflammation models. Herein, a strain of Edwardsiella tarda YT1 from farmed seahorse Hippocampus erectus was isolated and identified by morphological, phylogenetic, and biochemical analysis, and confirmed as a pathogen of enteritis for the first time by challenge experiment. Two E. tarda concentrations (1 × 10 and 1 × 10 colony forming units [cfu] ml) were confirmed suitable for an enteritis model by intraperitoneal injection. To develop and evaluate the experimental model, we challenged seahorses with E. tarda and found that (1) the infection inhibited body length increase, significantly decreased body weight (P < 0.05), and induced typical pathological features including anorexia, anal inflammation, and intestinal fluid retention; (2) 19 external (weight, height, anal inflammation, feeding status, and intestinal fluid retention), histological (goblet and inflammatory cell numbers and thickening of lamina propria and muscularis mucosae), and molecular (hepcidin, liver-expressed antimicrobial peptide, lysozyme, piscidin, interleukin [IL]-1β, IL-1β receptor, IL-2, IL-10, interferon1, tumor necrosis factor [TNF]-α, and toll-like receptor 5 [TLR5]) indicators were suitable for model evaluation, as they could sensitively respond and varied similarly throughout the experiment, indicating the high sensitivity of seahorses against pathogen invasion; (3) TLR5 may play an essential role in triggering host immune responses during E. tarda-induced chronic enteritis, and (4) the evaluating system could reflect the pattern and intensity of disease progression. Thus, we developed an experimental model and an evaluating system of bacterial enteritis in farmed seahorses, helping us to reveal the pathogenesis of bacterial enteritis, identify potential therapeutic drugs, and search suitable genetic markers for seahorse molecular breeding.
细菌性肠炎是养殖海马的重要致死威胁。然而，由于缺乏可复制的实验性肠道炎症模型，其发病机制尚不清楚。本研究通过形态学、系统发育和生化分析，从养殖海马（ Hippocampus erectus ）中分离鉴定出一株迟钝爱德华氏菌（ Edwardsiella tarda ）YT1，并通过攻毒实验首次证实其为肠炎的病原体。通过腹腔注射实验，确定了两种迟钝爱德华氏菌浓度（1×10 和 1×10 个菌落形成单位[cfu]ml）适用于肠炎模型。为了开发和评估实验模型，我们用迟钝爱德华氏菌感染海马，发现：（1）感染抑制了体长增加，显著降低了体重（P<0.05），并诱导了典型的病理特征，包括厌食、肛门炎症和肠道积液；（2）19 个外部（体重、体长、肛门炎症、摄食状态和肠道积液）、组织学（杯状细胞和炎性细胞数量以及固有层和黏膜肌层增厚）和分子（铁调素、肝表达抗菌肽、溶菌酶、鱼精蛋白、白细胞介素[IL]-1β、IL-1β受体、IL-2、IL-10、干扰素 1、肿瘤坏死因子[TNF]-α和 Toll 样受体 5[TLR5]）指标适合模型评估，因为它们能够敏感地响应并在整个实验中变化相似，表明海马对病原体入侵具有高度敏感性；（3）TLR5 可能在迟钝爱德华氏菌诱导的慢性肠炎中触发宿主免疫反应中发挥重要作用；（4）评估系统可以反映疾病进展的模式和强度。因此，我们建立了养殖海马细菌性肠炎的实验模型和评估系统，有助于揭示细菌性肠炎的发病机制，筛选潜在的治疗药物，并寻找适合海马分子育种的遗传标记。
