Kordon Adef O, Abdelhamed Hossam, Ahmed Hamada, Park Joo Y, Karsi Attila, Pinchuk Lesya M
Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States.
Department of Nutrition and Veterinary Clinical Nutrition, Faculty of Veterinary Medicine, Damanhour University, Damanhour, Egypt.
Front Microbiol. 2018 Jan 9;8:2638. doi: 10.3389/fmicb.2017.02638. eCollection 2017.
(), a Gram-negative, intracellular, facultative bacterium, is the causative agent of enteric septicemia of catfish (ESC), which is one of the most significant diseases of farmed channel catfish. Macrophages have a critical role in major defense mechanisms against bacterial infections by migrating to the site of infection, engulfing and killing pathogens, and priming adaptive immune responses. Vaccination of catfish with live attenuated vaccine (LAV) strains increased the efficiency of phagocytosis and bacterial killing in catfish peritoneal macrophages compared with macrophages from non-vaccinated fish. Recently, our group developed several protective LAV strains from . However, their effects on the antigen uptake and bacterial killing in catfish macrophages have not been evaluated. In this study, we assessed the phagocytic and bactericidal activity of peritoneal macrophages in the uptake of wild-type (WT) and two LAV strains. We found that phagocytosis of LAV strains was significantly higher compared to their WT counterpart in peritoneal macrophages. Moreover, the uptake of opsonized with sera from vaccinated catfish was more efficient than when opsonized with sera from sham-vaccinated fish. Notably, catfish macrophages did not lose their phagocytic properties at 4°C, as described previously in mammalian and zebrafish models. Also, opsonization of with inactivated sera from vaccinated and sham-vaccinated catfish decreased significantly phagocytic uptake of bacteria at 32°C, and virtually suppressed endocytosis at 4°C, suggesting the important role of complement-dependent mechanisms in catfish macrophage phagocytosis. In conclusion, our data on enhanced phagocytic capacity and effective killing ability in macrophages of vaccine strains suggested the LAVs' advantage if processed and presented in the form of peptides to specific lymphocytes of an adaptive immune system and emphasize the importance of macrophage-mediated immunity against ESC. Furthermore, we showed the role of complement-dependent mechanisms in the phagocytic uptakes of in catfish peritoneal macrophages at 4 and 32°C. Finally, LAV vaccine-induced bacterial phagocytosis and killing properties of peritoneal macrophages emphasized the importance of the innate immune responses in ESC.
（某细菌名称）是一种革兰氏阴性、胞内兼性细菌，是鲶鱼肠道败血症（ESC）的病原体，而鲶鱼肠道败血症是养殖沟鲶最重要的疾病之一。巨噬细胞在抵御细菌感染的主要防御机制中发挥关键作用，它们迁移到感染部位，吞噬并杀死病原体，启动适应性免疫反应。与未接种疫苗的鱼的巨噬细胞相比，用减毒活疫苗（LAV）菌株给鲶鱼接种疫苗可提高鲶鱼腹腔巨噬细胞的吞噬效率和细菌杀伤能力。最近，我们的团队从（某细菌名称）中开发了几种保护性LAV菌株。然而，它们对鲶鱼巨噬细胞中抗原摄取和细菌杀伤的影响尚未得到评估。在本研究中，我们评估了腹腔巨噬细胞对野生型（WT）和两种LAV菌株的吞噬和杀菌活性。我们发现，与野生型相比，腹腔巨噬细胞对LAV菌株的吞噬作用显著更高。此外，用接种疫苗的鲶鱼血清调理后的（某细菌名称）摄取效率高于用假接种鱼血清调理后的情况。值得注意的是，鲶鱼巨噬细胞在4°C时不会丧失其吞噬特性，这与之前在哺乳动物和斑马鱼模型中所描述的情况相同。同样，用接种疫苗和假接种鲶鱼的灭活血清调理（某细菌名称）后，在32°C时细菌的吞噬摄取显著降低，而在4°C时几乎抑制了内吞作用，这表明补体依赖性机制在鲶鱼巨噬细胞吞噬作用中起重要作用。总之，我们关于疫苗菌株巨噬细胞中吞噬能力增强和有效杀伤能力的数据表明，如果以肽的形式加工并呈递给适应性免疫系统的特定淋巴细胞，减毒活疫苗具有优势，并强调了巨噬细胞介导的抗ESC免疫的重要性。此外，我们展示了补体依赖性机制在4°C和32°C时鲶鱼腹腔巨噬细胞对（某细菌名称）的吞噬摄取中的作用。最后，LAV疫苗诱导的腹腔巨噬细胞对细菌的吞噬和杀伤特性强调了先天性免疫反应在ESC中的重要性。
