Sessile Kupffer Cells in Liver Tolerance

 描述(申请人提供)：Kupffer细胞是丰富的肝脏巨噬细胞，在肝脏耐受中发挥重要作用，无论是在抑制适应性免疫方面，还是在保护肝脏免受损伤方面。我们之前发现了一组“无梗枯否细胞”，这种细胞在骨髓嵌合体中是抗辐射的，在移植的肝脏中长期存活，但不能移动(由此得名)。然而，这些细胞很难分离，因此对它们与骨髓源性Kupffer细胞的功能关系知之甚少。这一探索性/发育性方案的意义在于，要了解库普弗细胞及其在免疫和耐受中的作用，关键是要了解固着库普弗细胞。如果它们的行为与骨髓来源的Kupffer细胞不同，就会导致巨大的知识鸿沟，因为它们很难分离，而且还没有被研究过。我们方法的创新之处在于使用了一种新的转基因工具--RiboTag小鼠，在该工具中，可以使用Cre重组酶将HA标签原位转移到核糖体上。通过将巨噬细胞特异性Cre转基因与RiboTag小鼠杂交，我们将原位记录Kupffer细胞的基因表达，从而避免细胞分离和高选择性细胞恢复的问题。将这种方法与我们对辐射骨髓嵌合体中固着的Kupffer细胞行为的了解结合起来，将使我们能够独立地检测固着的Kupffer细胞和骨髓来源的Kupffer细胞中的基因表达。拥有生物信息学专业知识的合作者将使我们能够最客观地利用这些信息。为了记录Kupffer细胞的两个亚群在耐受中的反应，我们将利用CD8+T细胞介导的肝损伤模型，在该模型中，我们的初步数据显示Kupffer细胞正在抑制肝脏损伤，并且我们已经知道骨髓来源的细胞在炎症肝脏中表现出抗炎的基因表达模式。在此背景下，我们将使用(Cre X RiboTag)小鼠来确定Kupffer细胞的固着和骨髓来源的亚群是否以相同的方式抑制肝脏损伤。重要的知识收获将是确定这两种库普弗细胞在免疫耐受中具有不同的功能，或者揭示它们的反应相同。如果它们不同，就必须解决它们在更复杂的生物学模型中的特殊作用，包括肝移植耐受和肝脏感染。我们还需要了解人类的固位型库普弗细胞生物学。此外，固着的Kupffer细胞可能与皮肤的朗格汉斯细胞和小胶质细胞共享个体发育，并可能在生物学上共享。对固着库普弗细胞的洞察可能会给其他非骨髓来源的组织驻留巨噬细胞带来问题。

 DESCRIPTION (provided by applicant): Kupffer cells are abundant liver macrophages that play an important role in liver tolerance, both in terms of suppressing adaptive immunity and in protecting the liver from injury. We previously identified a subset of "sessile Kupffer cells", whih are radio-resistant in a bone marrow chimera and long-lived in a transplanted liver, but non-motile (hence the name). However these cells are very difficult to isolate, so little is known abou their functional relationship with bone marrow-derived Kupffer cells. The significance of this exploratory/developmental proposal is that to understand Kupffer cells and their roles in immunity and tolerance, it is critical to understand the sessile Kupffer cells. If they act differetly from bone marrow-derived Kupffer cells, a substantial knowledge gap will result since they are so difficult to isolate, and have not been studied. The innovation of our approach is to use a novel transgenic tool, the RiboTag mouse, in which it is possible to transfer an HA tag to ribosomes in situ using the Cre recombinase. By crossing the RiboTag mouse with a macrophage-specific Cre transgene, we will document Kupffer cell gene expression in situ, avoiding cell isolation and the problem of highly-selective cell recovery. Coupling this approach with our knowledge of the behavior of sessile Kupffer cells in a radiation bone marrow chimera will allow us independently to assay gene expression in sessile, versus bone marrow-derived Kupffer cells. A collaborator with expertise in bioinformatics will allow us to make the best objective use of this information. To document the response of the two subsets of Kupffer cells in tolerance, we will exploit a model of CD8+ T cell- mediated liver injury in which our preliminary data show that Kupffer cells are suppressing liver injury, and in which we already know that the bone marrow-derived cells show an anti-inflammatory pattern of gene expression in the inflamed liver. In this context, we will use the (Cre x RiboTag) mice to determine whether sessile and bone marrow-derived subsets of Kupffer cells respond in the same way to suppress liver damage. The important knowledge gain will be to establish that these two kinds of Kupffer cells have distinct functions in immune tolerance, or alternatively to reveal that they respond alike. If they are different, it will be mandatory to address their special role in more biologicaly complex models, including liver transplantation tolerance and liver infection. We will need to understand sessile Kupffer cell biology in humans also. Furthermore, sessile Kupffer cells may share ontogeny, and possibly biology with Langerhans cells of the skin and with microglia. Insights into sessile Kupffer cells may raise issues for other non-bone marrow-derived tissue-resident macrophages.