贝类血淋巴细胞及其增殖、分化和死亡

    The mollusc hemocytes and their proliferation, differentiation, and death

    • 摘要:
      目的 本文描述了贝类血淋巴细胞的结构和功能特征以及分类现状,总结了贝类血淋巴细胞增殖、分化和死亡的分子调控机制,旨在系统了解和认识贝类免疫细胞及其命运决定机制,推动贝类免疫学的发展。
      进展 血淋巴细胞是贝类主要的免疫细胞,在结构、功能、分类、增殖与分化途径以及死亡方式等方面展现出多样性和复杂性。不同贝类的血淋巴细胞在细胞整体形态和细胞内细胞器及颗粒含量上存在较大差异,这些差异反映了其功能上的多样性和适应性。血淋巴细胞在抵御病原微生物入侵方面发挥着关键作用。它们主要通过吞噬作用和合成免疫效应分子抵御病原微生物入侵。这一过程会产生呼吸爆发并催化产生多种活性氧中间体,对吞噬入细胞内的病原微生物进行杀伤。除了直接抵御病原入侵外,血淋巴细胞还参与组织损伤修复与免疫稳态维持。目前基于细胞形态与功能特征,贝类血淋巴细胞主要分为无粒细胞、半粒细胞和颗粒细胞三种类型。无粒细胞通常缺乏明显的颗粒结构,可参与伤口修复;半粒细胞含有少量颗粒,具有一定的吞噬和杀菌能力;颗粒细胞则含有丰富的颗粒,这些颗粒中储存着多种杀菌物质和酶类。这三种类型的血淋巴细胞协同作用,共同构成了贝类复杂的免疫防御体系。血淋巴细胞的增殖、分化和死亡是一个复杂的动态过程,涉及到多种分子间的相互作用及多条信号通路的协同调控。在增殖方面,血淋巴细胞受到多种转录因子、生长因子和细胞因子的调控;在分化方面,血淋巴细胞在特定的微环境和分子调控下,能够分化为不同类型的免疫细胞;在细胞死亡方面,血淋巴细胞存在凋亡、焦亡、自噬、铁死亡、铜死亡等多种死亡方式。血淋巴细胞的增殖、分化和死亡在贝类免疫防御和免疫稳态维持中发挥重要作用。
      展望 贝类血淋巴细胞的研究虽已取得了一定的进展,但仍存在诸多问题及挑战。在结构、功能及分类方面,借助新技术剖析其结构,建立科学统一的分类体系;在增殖与分化方面,可运用系统生物学方法整合多组学数据,构建调控网络;在细胞死亡方面,对比贝类不同细胞死亡的机制差异,明确不同细胞死亡的相互关系,在此基础上,结合血淋巴细胞分类体系和增殖分化调控网络,系统明确贝类不同类型免疫细胞的命运决定机制。这些基础理论研究不仅有助于理解贝类免疫细胞乃至免疫系统的演化规律与作用机制,也为养殖贝类病害防治提供理论支撑。

       

      Abstract:
      Objective This paper describes the structural and functional characteristics as well as current classification of mollusc hemocytes, and summarizes the molecular mechanisms governing their proliferation, differentiation, and death. These insights will enhance the systematic understanding of mollusc immune cells and their fate determination, offering valuable support for future research in mollusc immunology.
      Progress Hemocytes, as the primary immune cells in mollusks, exhibit considerable diversity and complexity in their morphology, function, classification, proliferation and differentiation pathways, as well as modes of cell death. Significant variations exist in the overall cellular morphology and the content of intracellular organelles and granules among hemocytes from different mollusks, reflecting their functional diversity and adaptability. Hemocytes are crucial in defending against pathogenic invasion, primarily through phagocytosis, the synthesis and secretion of immune active substances. During phagocytosis, a respiratory burst occurs, catalyzing the production of various reactive oxygen intermediates (ROIs) that kill pathogens engulfed within the cells. Beyond direct pathogen defense, hemocytes also participate in tissue repair and the maintenance of immune homeostasis. Based on cellular morphology and functional characteristics, mollusc hemocytes are mainly classified into three types: agranulocytes, semigranulocytes, and granulocytes. Agranulocytes typically lack distinct granular structures and can participate in wound repair; semigranulocytes contain a small number of granules and possess certain phagocytic and bactericidal capabilities; granulocytes, on the other hand, are rich in granules that store various bactericidal substances and enzymes. These three types of hemocytes collaborate to form a complex immune defense system in molluscs. The proliferation, differentiation and death of hemocytes represent a complex and dynamic process involving the interaction of multiple molecules and the regulation of various signaling pathways. Regarding proliferation, hemocytes are regulated by multiple transcription factors, growth factors, and cytokines. During differentiation, hemocytes can differentiate into various types of immune cells under specific microenvironments and molecular regulation to meet different immune demands. Hemocytes undergo various forms of programmed cell death, including apoptosis, pyroptosis, autophagy, ferroptosis, and cuproptosis. The proliferation, differentiation, and death of hemocytes play crucial roles in the immune defense and maintenance of immunological homeostasis in molluscs.
      Prospect Although significant progress has been made in the research on mollusc hemocytes, there still remain numerous challenges. To address the complexities of their structure, function and classification, advanced techniques are needed to establish a unified and scientific classification system. Furthermore, systems biology approaches integrating multi-omics data should be utilized to reconstruct the molecular regulatory networks governing hemocyte proliferation and differentiation. Regarding cell death, compare the mechanistic differences in various types of cell death in molluscs and clarify the interrelationships among different forms of cell death. Integrating these findings on cell death with the established hemocyte classification and regulatory networks will be instrumental in systematically elucidating the fate-determination mechanisms of various immune cells. These fundamental theoretical advances will not only enhance our understanding of the evolution and mechanisms of the mollusc immune system but also provide crucial theoretical support for the prevention and control of diseases in mollusc aquaculture.

       

    /

    返回文章
    返回