National Research Council (CNR), Institute of Biochemistry and Cell Biology (IBBC), Naples, Italy.
Biology and Evolution of Marine Organisms (BEOM), Stazione Zoologica Anton Dohrn, Naples, Italy.
Front Immunol. 2019 Aug 16;10:1977. doi: 10.3389/fimmu.2019.01977. eCollection 2019.
The immune defensive mechanisms active in the solitary ascidian include phagocytic and encapsulating activity, largely brought about by phagocytic cells within the haemocyte population, the presence of complement components, which have been molecularly and functionally identified, and expression of a number of immune-related genes and pathways, identified by genome-based homology with vertebrate counterparts. Since only displays highly conserved innate immune mechanisms, being devoid of an adaptive immune system, this organism is an excellent model for studying the features of innate memory, i.e., the capacity of the innate immune system to re-programming its responsiveness to potentially dangerous agents upon repeated exposure. In this study, we have developed an model for assessing the establishment and molecular/functional features of innate memory, by sequentially exposing to a priming stimulus (microbial molecules), followed by a period of resting to return to basal conditions, and a challenge with microbial agents in homologous or cross-stimulation. The endpoints of immune activation were a functional activity (phagocytosis) and the molecular profiles of immune-related gene expression. The results show that exposure of to microbial agents induces a reaction that primes animals for developing a different (expectedly more protective) response to subsequent challenges, showing the effective establishment of an immune memory. This immune memory relies on the modulation of a number of different mechanisms, some of which are priming-specific, others that are challenge-specific, and others that are non-specific, i.e., are common to all priming/challenge combinations (e.g., up-regulation of the and genes). Memory-dependent expression of the humoral immunity-related gene inversely correlates with memory-dependent variations of phagocytic rate, suggesting that complement activation and phagocytosis are alternative defensive mechanisms in . Conversely, memory-dependent expression of the cellular immunity-related gene directly correlates with variations of phagocytic rate, suggesting a direct involvement of this gene in the functional regulation of phagocytosis.
在孤立的海鞘中，主动的免疫防御机制包括吞噬和包埋作用，主要由血细胞群体中的吞噬细胞引起，存在补体成分，这些成分已经在分子和功能上得到了鉴定，并且表达了一些免疫相关的基因和途径，这些基因和途径通过与脊椎动物的同源性基于基因组被识别。由于 仅显示出高度保守的先天免疫机制，缺乏适应性免疫系统，因此该生物体是研究先天记忆特征（即先天免疫系统重新编程其对潜在危险物质的反应能力的能力）的理想模型。在这项研究中，我们通过顺序暴露 于启动刺激（微生物分子），然后休息一段时间使机体恢复到基础状态，然后用同源或交叉刺激的微生物剂进行挑战，建立了一种评估先天记忆建立和分子/功能特征的 模型。免疫激活的终点是功能活性（吞噬作用）和免疫相关基因表达的分子谱。结果表明，暴露于微生物剂会引起反应，使动物对随后的挑战产生不同（预期更具保护性）的反应，从而有效地建立了免疫记忆。这种免疫记忆依赖于许多不同机制的调节，其中一些是启动特异性的，另一些是挑战特异性的，还有一些是非特异性的，即它们是所有启动/挑战组合共有的（例如， 和 基因的上调）。体液免疫相关基因 的记忆依赖性表达与吞噬率的记忆依赖性变化呈负相关，表明补体激活和吞噬作用是 中的替代防御机制。相反，细胞免疫相关基因 的记忆依赖性表达与吞噬率的变化直接相关，表明该基因直接参与吞噬作用的功能调节。
