Leukocyte Adhesion in Allergic Inflammation

描述（由申请人提供）：过敏性炎症是一种复杂的疾病，涉及多种白细胞的运输和动员，包括嗜酸性粒细胞和t细胞，到炎症部位。在气道变应性炎症中，Th2细胞因子、趋化因子、血管粘附分子和生长因子的表达增加，导致炎症反应加剧，包括气道多动（AHR）、气道重塑和肺血管生成的增加。由于嗜酸性粒细胞在过敏性炎症的发病机制中起着重要作用，在过去的十年中，我们将注意力集中在这种细胞类型的产生机制，它如何与血管内皮相互作用以及它如何被募集到炎症部位。这些研究已经确定了嗜酸性粒细胞在不同血管床（如腹膜和肺血管床）隔离的关键分子。我们的初步研究表明，除了细胞表面选择素和整合素外，凝集素-3 (Gal-3)，一种碳水化合物结合凝集素，可以识别由MgatS表达的n-聚糖，可以(i)作为一种新的血管和细胞粘附分子，支持嗜酸性粒细胞运输，（ii）参与Th2细胞因子的产生，（iii）诱导小鼠AHR。在这个竞争性的延续中，我们假设Gal-3以及MgatS表达的n -聚糖在急性和慢性气道变应性炎症（包括哮喘）的发病机制中发挥重要作用。为此，我们提出了三个具体目标。在第一个目标中，我们将使用活体显微镜检查Gal-3作为一种新型粘附分子的功能，它通过结合多种配体来支持细胞粘附，包括含有聚N-乙酰乳胺残基的N-聚糖、VCAM-1和α 4整合素，以支持嗜酸性粒细胞在不同血管床流动条件下的运输。在接下来的目标中，我们将使用Gal-3-/-和Mgat5 -/-小鼠，确定Gal-3和Mgat5在介导免疫反应中的作用，包括AHR、粘附分子和趋化因子的表达、Th1/Th2细胞因子的释放、肥大细胞活化和慢性过敏性炎症期间炎性白细胞的存活。最后，基于我们的观察，Gal-3在慢性过敏原挑战小鼠的气道和肺组织中表达，与气道重塑相关，我们建议利用Gal-3-/-和Mgat-5-/-小鼠研究Gal-3及其含n-聚糖配体表达的mgat促进气道重塑和与过敏性炎症相关的肺血管生成的机制。总的来说，拟议的研究将描述Gal-3及其配体在气道变应性炎症的急性和慢性阶段的重要性。了解凝集素-碳水化合物相互作用在过敏性炎症中的作用有可能导致以聚糖为基础的治疗（或其模拟物）的发展，用于治疗过敏性疾病。

DESCRIPTION (provided by applicant): Allergic inflammation is a complex disease that involves the trafficking and mobilization of multiple leukocytes, including eosinophils and T-cells, to sites of inflammation. Increased expression of Th2 cytokines, chemokines, vascular adhesion molecules and growth factors leading to exacerbation of the inflammatory response, including increased airway hyperactivity (AHR), airway remodeling and pulmonary angiogenesis are observed during airway allergic inflammation. Since eosinophils play an important role in the pathogenesis of allergic inflammation, in the last decade we have focused our attention on the mechanisms by which this cell type is generated, how it interacts with the vascular endothelium and how it is recruited to sites of inflammation. These studies have resulted in the identification of key molecules involved in the sequestration of eosinophils to different vascular beds such as the peritoneum and the pulmonary vascular bed. Our preliminary studies suggest that in addition to cell surface selectins and integrins, galectin- 3 (Gal-3), a carbohydrate-binding lectin that recognizes N-glycans expressed by MgatS, can (i) function as a novel vascular and cell adhesion molecule to support eosinophil trafficking, (ii) participate in the generation of Th2 cytokines and (iii) induce AHR in mice. In this competing continuation, we hypothesize that Gal-3 as well as N-glycans expressed by MgatS play an important role in the pathogenesis of acute and chronic airway allergic inflammation including asthma. To examine this, we have proposed three specific aims. In the first aim, using intravital microscopy, we will examine the function of Gal-3 as a novel adhesion molecule that supports cell adhesion by binding to multiple ligands, including N-glycans containing poly N- acetyllactosamine residues, VCAM-1 and alpha4 integrins, to support trafficking of eosinophils under conditions of flow in different vascular beds. In the next aim, using Gal-3-/- and Mgat-5-/- mice, we will determine the role of Gal-3 and Mgat5 in mediating immune responses including, AHR, expression of adhesion molecules and chemokines, Th1/Th2 cytokine release, mast cell activation and survival of inflammatory leukocytes during chronic allergic inflammation. Finally, based on our observation that Gal-3 is expressed in the airways and lung tissue associated with airway remodeling in chronically allergen-challenged mice, we propose to examine the mechanisms by which Gal-3 and its N-glycan-containing ligands expressed by MgatS promote airway remodeling and pulmonary angiogenesis associated with allergic inflammation utilizing Gal-3-/- and Mgat-5-/- mice. Overall, the proposed studies will delineate the importance of Gal-3 and its ligands in acute and chronic phases of airway allergic inflammation. Understanding the role of lectin-carbohydrate interactions in allergic inflammation has the potential to lead to the development of glycan-based therapies (or their mimetics) for the treatment of allergic diseases.