First in-depth analysis of the novel Th2-type cytokines in salmonid fish reveals distinct patterns of expression and modulation but overlapping bioactivities.
First in-depth analysis of the novel Th2-type cytokines in salmonid fish reveals distinct patterns of expression and modulation but overlapping bioactivities.
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DOI：
10.18632/oncotarget.7295
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发表时间：
2016-03-08
期刊：
影响因子：
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通讯作者：
Secombes CJ
中科院分区：
文献类型：
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作者：
Wang T;Johansson P;Abós B;Holt A;Tafalla C;Jiang Y;Wang A;Xu Q;Qi Z;Huang W;Costa MM;Diaz-Rosales P;Holland JW;Secombes CJ
IL-4和IL-13是哺乳动物中密切相关的典型2型细胞因子，并通过共享受体具有重叠的生物活性。它们经常作为相同免疫应答的一部分一起被激活，并且是由T辅助（Th）2细胞和2型先天淋巴样细胞（ILC 2）产生的标志性细胞因子，介导针对细胞外病原体的免疫。关于2型反应的起源，以及它们是否是早期适应性免疫系统的重要组成部分，通过限制由后生动物寄生虫引起的附带损害来提供适应性优势，我们知之甚少。两个进化相关的2型细胞因子，IL-4/13 A和IL-4/13 B，最近已被确定在几个硬骨鱼，可能出现的祖先IL-4/13基因的复制作为一个结果，发生在该谱系的基础上的全基因组复制事件。然而，它们的比较表达水平的研究在很大程度上是缺失的，并且生物活性分析一直限于斑马鱼中的IL-4/13 A。通过询问最近公布的鲑鱼基因组，其中发生了额外的全基因组重复事件的物种，已经确定了四个基因组IL-4/13基因座，导致三个活性基因，IL-4/13 A，IL-4/13 B1和IL-4/13 B2，在虹鳟鱼和大西洋鲑鱼中的克隆。通过实时PCR的比较表达分析显示，虹鳟鱼IL-4/13 A的表达是广泛的，高组成，但较少响应病原体相关的分子模式（PAMPs）和病原体的挑战。相比之下，IL-4/13 B1和IL-4/13 B2的表达组成性低，但在体内由病毒性出血性败血症病毒（VHSH）感染和增殖性肾病（PKD）期间高度诱导，在体外由福尔马林杀死的细菌、PAMP、T细胞有丝分裂原PHA和T细胞细胞因子IL-2和IL-21高度诱导。此外，产生了IL-4/13 A和B的生物活性重组细胞因子，并发现它们具有共同但也不同的生物活性。这两种细胞因子都能快速诱导抗菌肽和急性时相蛋白的基因表达，为鱼类2型细胞因子的免疫效应机制提供了可能。它们通过上调IL-10和下调IL-1β和IFN-γ而抗炎。它们调节T细胞、巨噬细胞和B细胞的细胞标志物、IFN-γ受体、IL-6细胞因子家族及其自身的潜在受体的表达，表明鱼类2型细胞因子在鱼类细胞因子网络中具有多靶细胞和重要作用。此外，两种细胞因子均能增加分泌IgM的B细胞的数量，但对IgM+ B细胞的增殖无影响。总的来说，鱼IL-4/13 A可以提供基础水平的2型免疫，而IL-4/13 B在活化时提供增强的2型免疫，其在特异性细胞介导的免疫中可能具有重要作用。据我们所知，这是第一次深入分析的表达，调制和生物活性的2型细胞因子在同一鱼类物种，并在任何早期脊椎动物。它有助于更广泛地了解脊椎动物2型免疫的进化，并建立了一个框架，为进一步研究和操纵鱼类2型细胞因子。
IL-4 and IL-13 are closely related canonical type-2 cytokines in mammals and have overlapping bioactivities via shared receptors. They are frequently activated together as part of the same immune response and are the signature cytokines produced by T-helper (Th)2 cells and type-2 innate lymphoid cells (ILC2), mediating immunity against extracellular pathogens. Little is known about the origin of type-2 responses, and whether they were an essential component of the early adaptive immune system that gave a fitness advantage by limiting collateral damage caused by metazoan parasites. Two evolutionary related type-2 cytokines, IL-4/13A and IL-4/13B, have been identified recently in several teleost fish that likely arose by duplication of an ancestral IL-4/13 gene as a consequence of a whole genome duplication event that occurred at the base of this lineage. However, studies of their comparative expression levels are largely missing and bioactivity analysis has been limited to IL-4/13A in zebrafish. Through interrogation of the recently released salmonid genomes, species in which an additional whole genome duplication event has occurred, four genomic IL-4/13 loci have been identified leading to the cloning of three active genes, IL-4/13A, IL-4/13B1 and IL-4/13B2, in both rainbow trout and Atlantic salmon. Comparative expression analysis by real-time PCR in rainbow trout revealed that the IL-4/13A expression is broad and high constitutively but less responsive to pathogen-associated molecular patterns (PAMPs) and pathogen challenge. In contrast, the expression of IL-4/13B1 and IL-4/13B2 is low constitutively but is highly induced by viral haemorrhagic septicaemia virus (VHSH) infection and during proliferative kidney disease (PKD) in vivo, and by formalin-killed bacteria, PAMPs, the T cell mitogen PHA, and the T-cell cytokines IL-2 and IL-21 in vitro. Moreover, bioactive recombinant cytokines of both IL-4/13A and B were produced and found to have shared but also distinct bioactivities. Both cytokines rapidly induce the gene expression of antimicrobial peptides and acute phase proteins, providing an effector mechanism of fish type-2 cytokines in immunity. They are anti-inflammatory via up-regulation of IL-10 and down-regulation of IL-1β and IFN-γ. They modulate the expression of cellular markers of T cells, macrophages and B cells, the receptors of IFN-γ, the IL-6 cytokine family and their own potential receptors, suggesting multiple target cells and important roles of fish type-2 cytokines in the piscine cytokine network. Furthermore both cytokines increased the number of IgM secreting B cells but had no effects on the proliferation of IgM+ B cells in vitro. Taken as a whole, fish IL-4/13A may provide a basal level of type-2 immunity whilst IL-4/13B, when activated, provides an enhanced type-2 immunity, which may have an important role in specific cell-mediated immunity. To our knowledge this is the first in-depth analysis of the expression, modulation and bioactivities of type-2 cytokines in the same fish species, and in any early vertebrate. It contributes to a broader understanding of the evolution of type-2 immunity in vertebrates, and establishes a framework for further studies and manipulation of type-2 cytokines in fish.