The Houston Methodist Research Institute, Transplant Immunology, Houston, TX 77030, USA.
Department of Surgery, The Houston Methodist Hospital, Houston, TX 77030, USA.
Int J Mol Sci. 2022 Dec 20;24(1):38. doi: 10.3390/ijms24010038.
Immunological memory is a crucial part of the immune defense that allows organisms to respond against previously encountered pathogens or other harmful factors. Immunological memory is based on the establishment of epigenetic modifications of the genome. The ability to memorize encounters with pathogens and other harmful factors and mount enhanced defense upon subsequent encounters is an evolutionarily ancient mechanism operating in all animals and plants. However, the term immunological memory is usually restricted to the organisms (invertebrates and vertebrates) possessing the immune system. The mammalian immune system, with innate and adaptive branches, is the most sophisticated among vertebrates. The concept of innate memory and memory macrophages is relatively new and thus understudied. We introduce the concept of immunological memory and describe types of memory in different species and their evolutionary status. We discuss why the traditional view of innate immune cells as the first-line defenders is too restrictive and how the innate immune cells can accumulate and retain immunologic memory. We describe how the initial priming leads to chromatin remodeling and epigenetic changes, which allow memory macrophage formation. We also summarize what is currently known about the mechanisms underlying development of memory macrophages; their molecular and metabolic signature and surface markers; and how they may contribute to immune defense, diseases, and organ transplantation.
免疫记忆是免疫防御的重要组成部分，使生物体能够针对先前遇到的病原体或其他有害因素做出反应。免疫记忆基于基因组的表观遗传修饰的建立。能够记住与病原体和其他有害因素的接触，并在随后的接触中增强防御能力，是一种在所有动物和植物中都存在的古老的进化机制。然而，免疫记忆这个术语通常仅限于具有免疫系统的生物体（无脊椎动物和脊椎动物）。哺乳动物的免疫系统，包括先天免疫和适应性分支，是脊椎动物中最复杂的。先天记忆和记忆巨噬细胞的概念相对较新，因此研究较少。我们介绍了免疫记忆的概念，并描述了不同物种中的记忆类型及其进化地位。我们讨论了为什么将先天免疫细胞视为第一道防线的传统观点过于局限，以及先天免疫细胞如何积累和保留免疫记忆。我们描述了初始启动如何导致染色质重塑和表观遗传变化，从而允许记忆巨噬细胞的形成。我们还总结了目前已知的记忆巨噬细胞形成的机制；它们的分子和代谢特征以及表面标记；以及它们如何有助于免疫防御、疾病和器官移植。
