The Impact of Tissue Sialylation on Macrophage Polarization and Function

总结 组织中的巨噬细胞在维持组织内环境稳定中起着重要作用。它们大致分为两类 类别：经典活化和促炎性巨噬细胞（M1）和交替活化和抗 炎性巨噬细胞（M2）。在免疫特权组织中，如肺和肝，巨噬细胞， 例如肝枯否细胞，通常被描述为M2。我们的初步数据表明，M2表型 至少部分取决于周围实质的糖组，特别是 肝细胞我们发现肝细胞表面聚糖上的α 2，6-连接唾液酸促进正常的M2 但是这种唾液酸化的丧失驱动M1极化和随后的异常T细胞活化 这导致炎性疾病易感性增加。在本建议中，我们寻求确定 肝脏中α 2，6-唾液酸化聚糖驱动常驻巨噬细胞表型变化的机制， T细胞活化。拟议的研究分为三个目标，前两个重点是影响 α 2，6-唾液酸化聚糖对巨噬细胞功能和信号传导的影响，第三个集中在机制 在没有唾液酸化的情况下，潜在的增加的T细胞活化和疾病。我们相信这些研究 将引入一种新的免疫检查点受体，其结合唾液酸化聚糖，抑制信号转导， 促进M2极化，并导致免疫稳态。

Summary Tissue-resident macrophages play important roles in maintain tissue homeostasis. They broadly fall into two categories: classically-activated and pro-inflammatory macrophages (M1) and alternatively-activated and anti- inflammatory macrophages (M2). Within immune privileged tissues, such as the lung and liver, macrophages, such as liver Kupffer cells, are typically described as M2. Our preliminary data suggests that the M2 phenotype in the liver depends at least in part upon the glycome of the surrounding parenchyma, particularly the hepatocytes. We have found that α2,6-linked sialic acids upon hepatocyte surface glycans promotes normal M2 polarization, but that loss of this sialylation drives M1 polarization and subsequent aberrant T cell activation which leads to increased inflammatory disease susceptibility. In this proposal, we seek to determine the mechanism by which α2,6-sialylated glycans in the liver drives changes in resident macrophage phenotype and T cell activation. The proposed studies are broken into three aims, with the first two focused upon the influence of α2,6-sialylated glycans on macrophage function and signaling, and the third focused upon the mechanism underlying increased T cell activation and disease in the absence of sialylation. We believe that these studies will introduce a novel immune checkpoint receptor which binds sialylated glycans, inhibits signal transduction, promotes M2 polarization, and leads to immune homeostasis.