Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, 430070, China; Guangzhou Key Laboratory of Aquatic Animal Diseases and Waterfowl Breeding, Guangdong Provincial Key Laboratory of Waterfowl Healthy Breeding, College of Animal Sciences and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, Guangdong, 510225, China.
Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, 430070, China; Huaihai Institute of Technology, Lianyungang, 222000, China.
Fish Shellfish Immunol. 2018 Jul;78:52-59. doi: 10.1016/j.fsi.2018.03.049. Epub 2018 Apr 6.
The mannose receptor (MR) is a type I transmembrane protein. Its ectodomain has eight C-type lectin-like domains, which are able to recognize and mediate the phagocytosis of a wide range of pathogens. Comprehensive studies have revealed that mammalian MR is widely distributed in the mononuclear phagocyte system (MPS, previously known as the reticuloendothelial system) and play a key role both in the physiological clearance and cell activation. Hitherto, neither the MR distribution, nor the function of clearance and cell activation has been investigated in fish. In the previous study, we have reported the full-length cDNA of blunt snout bream MR, analyzed its structure and relative mRNA expression during embryogenesis and in the liver, head kidney, spleen and intestine of fish after stimulation with killed Aeromonas hydrophila. In the present study, we developed a rabbit polyclonal antibody against MR and undertook a systematic survey of the expression of MR at the protein level by immunohistochemistry. To get more information about MR function, the mRNA expression of MR, pro-inflammatory factor TNF-α and anti-inflammatory factor ARG2 genes was measured by qRT-PCR in the liver, head kidney, and spleen after A. hydrophila challenge. We first observed MR expression in the yolk sac at the fertilized egg stage and possibly MR was expressed by early macrophages. We also showed the MR distribution in head kidney, body kidney, spleen, liver, intestine, muscle, brain, heart, and gills. Following A. hydrophila challenge the MR immunoreactive cells became more widespread in head kidney and spleen, which are the major reticuloendothelial systems of fish. The quantitative studies at mRNA levels showed that there exists a high correlation between MR expression and immune cytokine expressions after bacteria challenge.
甘露糖受体（MR）是一种 I 型跨膜蛋白。其胞外域具有 8 个 C 型凝集素样结构域，能够识别和介导广泛的病原体的吞噬作用。综合研究表明，哺乳动物 MR 广泛分布于单核吞噬细胞系统（MPS，以前称为网状内皮系统），在生理清除和细胞激活中发挥关键作用。迄今为止，鱼类的 MR 分布及其清除和细胞激活功能尚未得到研究。在之前的研究中，我们报道了鲳鲹 MR 的全长 cDNA，分析了其结构以及在胚胎发生过程中和在鱼的肝脏、头肾、脾脏和肠中受到灭活嗜水气单胞菌刺激后的相对 mRNA 表达。在本研究中，我们开发了针对 MR 的兔多克隆抗体，并通过免疫组织化学系统地调查了蛋白质水平的 MR 表达。为了获得有关 MR 功能的更多信息，通过 qRT-PCR 测量了 A. hydrophila 攻毒后肝脏、头肾和脾脏中 MR、促炎因子 TNF-α和抗炎因子 ARG2 基因的 mRNA 表达。我们首先在受精卵阶段的卵黄囊中观察到 MR 表达，并且可能由早期巨噬细胞表达。我们还显示了头肾、体肾、脾脏、肝脏、肠、肌肉、脑、心脏和鳃中的 MR 分布。在受到 A. hydrophila 攻击后，MR 免疫反应性细胞在头肾和脾脏中变得更加广泛，这是鱼类的主要网状内皮系统。mRNA 水平的定量研究表明，在细菌攻击后，MR 表达与免疫细胞因子表达之间存在高度相关性。
