Department of Aquatic Life Medicine, College of Fisheries Sciences, Pukyong National University, 45, Yongso-ro, Nam-Gu, Busan, Republic of Korea.
Department of Aquatic Life Medicine, College of Ocean Science and Technology, Kunsan National University, 558 Daehak-ro, Gunsan, 54150, Republic of Korea.
Dev Comp Immunol. 2022 Oct;135:104475. doi: 10.1016/j.dci.2022.104475. Epub 2022 Jun 19.
Hemopexin is a vital glycoprotein for processing excessive iron in blood and functions as an iron scavenger in mammals. Teleosts however, unlike mammals, have two known hemopexin paralogs called warm temperature acclimation-related 65 kDa protein (Wap65-1 and Wap65-2, collectively termed Wap65s). Although Wap65s in rainbow trout have been considered notable biomarkers with significantly higher and/or lower expression under conditions of stress or disease, the individual roles, similarities and differences between the two paralogs are not well known. The aim of this study was to gain an understanding of the characteristics and functions of trout Wap65s from the perspective of iron-metabolism, physiological roles, and relevant immunological responses. The expression of Wap65-1 and -2 in this study was determined in the face of challenges by Aeromonas salmonicida, infectious hematopoietic necrosis virus (IHNV), and iron-dextran. Immuno-histochemistry (IHC) was employed to localize the major cell types for Wap65-2 expression, and trout leukocytes were isolated and incubated with LPS and OxLDL for comprehending the immunological characteristics of Wap65-2. We demonstrate that Wap65-1 is expressed only in the liver but Wap65-2 is systemically expressed in most organs and tissues. Interestingly, Wap65-1 expression was not significantly changed under A. salmonicida and iron-dextran administration, but was significantly decreased under IHNV. In contrast, Wap65-2 was up-regulated in all challenged groups, however with different expression patterns in the blood and liver. These results suggested that the two paralogs may participate in different biological roles. IHC showed that Wap65-2 antibody had high affinity for leukocyte-like cells, and macrophages but not lymphocytes significantly increased expression under LPS and OxLDL stimulation. These results support the conclusion that trout Wap65-2, not Wap65-1 may have conventional hemopexin functions such as reported in mammals including effects on iron metabolism, inflammation, and acute-phase protein.
血清铁蛋白是一种重要的糖蛋白，可处理血液中过多的铁，并在哺乳动物中充当铁清除剂。然而，与哺乳动物不同的是，鱼类有两种已知的血清铁蛋白同源物，称为温适应相关 65kDa 蛋白（Wap65-1 和 Wap65-2，统称为 Wap65s）。尽管虹鳟鱼中的 Wap65s 已被认为是显著的生物标志物，在应激或疾病条件下表达水平显著升高或降低，但这两个同源物的个体作用、相似性和差异性尚不清楚。本研究旨在从铁代谢、生理作用和相关免疫反应的角度，了解鳜鱼 Wap65s 的特性和功能。本研究中，通过检测鳜鱼在受到嗜水气单胞菌、传染性造血坏死病毒（IHNV）和铁葡聚糖的挑战时 Wap65-1 和 -2 的表达，来确定它们的表达。采用免疫组织化学（IHC）技术定位 Wap65-2 表达的主要细胞类型，并分离鳜鱼白细胞，用 LPS 和 OxLDL 孵育，以了解 Wap65-2 的免疫学特性。结果表明，Wap65-1 仅在肝脏中表达，而 Wap65-2 则在大多数器官和组织中系统性表达。有趣的是，在 A. salmonicida 和铁葡聚糖处理下，Wap65-1 的表达没有明显变化，但在 IHNV 处理下明显下降。相比之下，Wap65-2 在所有受挑战的组中均上调，但在血液和肝脏中的表达模式不同。这些结果表明这两个同源物可能参与不同的生物学作用。免疫组化显示，Wap65-2 抗体与白细胞样细胞和巨噬细胞具有高亲和力，但与淋巴细胞不同，在 LPS 和 OxLDL 刺激下，其表达显著增加。这些结果支持这样的结论，即鳜鱼 Wap65-2 而不是 Wap65-1 可能具有哺乳动物中报道的传统血清铁蛋白功能，包括对铁代谢、炎症和急性期蛋白的影响。
