Parker Jamie, Marten Silke-Mareike, Ó Corcora Tadhg C, Rajkov Jelena, Dubin Arseny, Roth Olivia
Marine Evolutionary Biology, Christian-Albrechts-University, D-24118, Kiel, Germany.
Marine Evolutionary Biology, Christian-Albrechts-University, D-24118, Kiel, Germany.
Dev Comp Immunol. 2024 Apr;153:105136. doi: 10.1016/j.dci.2024.105136. Epub 2024 Jan 5.
Evolutionary adaptations in the Syngnathidae teleost family (seahorses, pipefish and seadragons) culminated in an array of spectacular morphologies, key immune gene losses, and the enigmatic male pregnancy. In seahorses, genome modifications associated with immunoglobulins, complement, and major histocompatibility complex (MHC II) pathway components raise questions concerning their immunological efficiency and the evolution of compensatory measures that may act in their place. In this investigation heat-killed bacteria (Vibrio aestuarianus and Tenacibaculum maritimum) were used in a two-phased experiment to assess the immune response dynamics of Hippocampus erectus. Gill transcriptomes from double and single-exposed individuals were analysed in order to determine the differentially expressed genes contributing to immune system responses towards immune priming. Double-exposed individuals exhibited a greater adaptive immune response when compared with single-exposed individuals, while single-exposed individuals, particularly with V. aestuarianus replicates, associated more with the innate branch of the immune system. T. maritimum double-exposed replicates exhibited the strongest immune reaction, likely due to their immunological naivety towards the bacterium, while there are also potential signs of innate trained immunity. MHC II upregulated expression was identified in selected V. aestuarianus-exposed seahorses, in the absence of other pathway constituents suggesting a possible alternative or non-classical MHC II immune function in seahorses. Gene Ontology (GO) enrichment analysis highlighted prominent angiogenesis activity following secondary exposure, which could be linked to an adaptive immune process in seahorses. This investigation highlights the prominent role of T-cell mediated adaptive immune responses in seahorses when exposed to sequential foreign bacteria exposures. If classical MHC II pathway function has been lost, innate trained immunity in syngnathids could be a potential compensatory mechanism.
海龙科硬骨鱼家族（海马、管口鱼和叶形海龙）的进化适应性最终形成了一系列引人注目的形态、关键免疫基因的缺失以及神秘的雄性怀孕现象。在海马中，与免疫球蛋白、补体和主要组织相容性复合体（MHC II）通路成分相关的基因组修饰引发了关于其免疫效率以及可能替代它们发挥作用的补偿措施进化的问题。在这项研究中，热灭活细菌（河口弧菌和海生枝动杆菌）被用于一个两阶段实验，以评估直立海马的免疫反应动态。分析了双次暴露和单次暴露个体的鳃转录组，以确定对免疫启动产生免疫系统反应有贡献的差异表达基因。与单次暴露个体相比，双次暴露个体表现出更强的适应性免疫反应，而单次暴露个体，特别是河口弧菌重复暴露的个体，更多地与免疫系统的先天分支相关。海生枝动杆菌双次暴露重复组表现出最强的免疫反应，这可能是由于它们对该细菌缺乏免疫经验，同时也有先天训练免疫的潜在迹象。在选定的暴露于河口弧菌的海马中，在没有其他通路成分的情况下，MHC II表达上调，这表明海马中可能存在替代或非经典的MHC II免疫功能。基因本体（GO）富集分析突出了二次暴露后显著的血管生成活性，这可能与海马的适应性免疫过程有关。这项研究突出了T细胞介导的适应性免疫反应在海马暴露于连续外来细菌时所起的重要作用。如果经典的MHC II通路功能已经丧失，海龙科动物的先天训练免疫可能是一种潜在的补偿机制。
