Sessile Kupffer Cells in Liver Tolerance

 描述（由申请人提供）：枯否细胞是丰富的肝脏巨噬细胞，在抑制适应性免疫和保护肝脏免受损伤方面，在肝脏耐受中发挥重要作用。我们先前鉴定了一个“固着枯否细胞”亚群，其在骨髓嵌合体中具有放射抗性，在移植的肝脏中存活时间长，但不活动（因此得名）。然而这些细胞很难分离，所以很少有人知道它们与骨髓来源的Kupffer细胞的功能关系。这种探索性/发展性建议的意义在于，要了解枯否细胞及其在免疫和耐受中的作用，了解固着枯否细胞至关重要。如果它们从骨髓来源的库普弗细胞中快速起作用，将导致大量的知识空白，因为它们很难分离，并且尚未被研究。我们的方法的创新是使用一种新的转基因工具，RiboTag小鼠，其中可以使用Cre重组酶将HA标签原位转移到核糖体。通过将RiboTag小鼠与巨噬细胞特异性Cre转基因杂交，我们将原位记录枯否细胞基因表达，避免细胞分离和高选择性细胞回收的问题。将这种方法与我们对辐射骨髓嵌合体中无柄库普弗细胞行为的了解相结合，将使我们能够独立地测定无柄库普弗细胞与骨髓源库普弗细胞中的基因表达。具有生物信息学专业知识的合作者将使我们能够最好地客观利用这些信息。为了记录库普弗细胞的两个亚群在耐受性中的反应，我们将利用CD 8 + T细胞介导的肝损伤的模型，其中我们的初步数据显示库普弗细胞抑制肝损伤，并且其中我们已经知道骨髓来源的细胞在发炎的肝脏中显示基因表达的抗炎模式。在这种情况下，我们将使用（Cre x RiboTag）小鼠来确定枯否细胞的固着和骨髓来源的亚群是否以相同的方式抑制肝损伤。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似。如果它们是不同的，则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无柄库普弗细胞生物学。此外，固着枯否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，并且可能共享生物学。对固着枯否细胞的深入了解可能会引起其他非骨髓来源的组织驻留巨噬细胞的问题。

 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.