Galectin-3 in regulation of allergic skin inflammation

描述（申请人提供）：特应性皮炎是一种常见的慢性炎症性皮肤病。这是一个重大的医疗问题，在工业化国家，多达15-20%的儿童受到这种疾病的影响。治疗特应性皮炎仍然是一个挑战。目前的模型表明，特应性皮炎可归因于th2介导的炎症反应，T细胞、树突状细胞和肥大细胞起重要作用。该提案旨在建立集素家族成员在特应性皮炎中的作用，并长期目标是开发一种治疗这种疾病的新疗法。半乳糖凝集素-3是动物凝集素家族的成员，由它们对2-半乳糖苷的亲和力和一致的序列定义。它由多种细胞类型表达，包括上皮细胞和各种白细胞。使用外源性半乳糖凝集素-3已经证明了许多细胞外功能，这些功能与它与细胞表面聚糖的结合和交联有关。然而，有大量证据表明内源性半乳糖凝集素-3通过细胞内作用调节多种细胞功能。通过研究半乳糖凝集素-3缺陷小鼠的T细胞，我们已经证明半乳糖凝集素-3是Th1细胞的抑制调节剂，并通过促进TCR下调来抑制T细胞受体（TCR）介导的Th1反应。半乳糖凝集素-3在TCR激活的T细胞中定位于细胞内的免疫突触。我们也证明了半乳糖凝集素-3抑制树突状细胞产生IL-12。此外，我们已经证明了半乳糖凝集素-3在肥大细胞中的重要作用。通过酵母双杂交筛选，我们发现Alix是一种半乳糖凝集素-3结合伙伴，已知它是运输（ESCRT）和多泡体（MVB）所需的内体分选复合体的组成部分。我们也有其他信息表明半乳糖凝集素-3与MVBs和外泌体有关。在特应性皮炎的小鼠模型中，我们发现半乳糖凝集素-3促进Th2反应并抑制Th1反应，这部分是通过蛋白质在T细胞和树突状细胞中的功能实现的。在本提案中，我们计划验证半乳糖凝集素-3通过在IS中发挥作用来抑制tcr介导的Th1反应的假设；2)通过抑制IL-12的产生对树突状细胞的抗原呈递功能至关重要，并作为外泌体相关蛋白发挥作用；3)通过树突状细胞和肥大细胞（除了T细胞）促进过敏性皮肤炎症。

DESCRIPTION (provided by applicant): Atopic dermatitis is a common chronic inflammatory skin disease. It is a significant medical problem and as much as 15-20% of children are affected by this disease in industrialized countries. Treatment of atopic dermatitis continues to be a challenge. The current model suggests that atopic dermatitis is attributable to a Th2-mediated inflammatory response and T cells, dendritic cells, and mast cells play important roles. This proposal aims at the establishment of the role of a member of the galectin family in atopic dermatitis with the long-term goal of developing a novel therapy for treatment of this disease. Galectin-3 is a member of a family of animal lectins defined by their affinity for 2-galactosides and consensus sequences. It is expressed by a number of cell types, including epithelial cells and various leukocytes. A number of extracellular functions have been demonstrated by using exogenously added galectin-3 and these are associated with its binding to and crosslinking cell surface glycans. However, there is a great deal of evidence that endogenous galectin-3 regulates various cellular functions through intracellular actions. By studying T cells from galectin-3-deficient mice, we have demonstrated that galectin-3 is an inhibitory regulator in Th1 cells and suppresses the T cell receptor (TCR)-mediated Th1 response by promoting TCR downregulation. Galectin-3 is localized intracellularly at the immunological synapse in T cells activated by TCR engagement. We have also demonstrated that galectin-3 suppresses the production of IL-12 by dendritic cells. In addition, we have demonstrated an important role of galectin-3 in mast cells. By yeast two-hybrid screening, we found Alix as a galectin-3-binding partner, which is known to be a component of the endosomal sorting complex required for transport (ESCRT) and the multivesicular body (MVB). We also have other information suggesting that galectin-3 is associated with MVBs and exosomes. In a mouse model of atopic dermatitis, we found that galectin-3 promotes the Th2 response and suppresses the Th1 response and this is in part through the protein's function in T cells and dendritic cells. In this proposal, we plan to test the hypothesis that galectin-3 1) suppresses the TCR-mediated Th1 response by functioning at the IS; 2) is critical for the antigen-presenting function of dendritic cells by suppressing IL-12 production and functions as an exosome-associated protein; 3) promotes allergic skin inflammation through dendritic cells and mast cells (in addition to T cells). PUBLIC HEALTH RELEVANCE: Atopic dermatitis is a common chronic inflammatory skin disease. The prevalence of this disease has increased by two- to three-fold during the past three decades in industrialized countries, where the current prevalence in children is estimated to be 15-20%. The treatment of this disease continues to be a challenge. Elucidation of the cellular and molecular bases of this disease is important for development of novel therapeutic strategies. Galectin-3 is a member of a family of proteins that bind carbohydrates, called lectins. The galectin family defined by their binding of 2-galactosides and sharing of similar amino acid sequences. When galectin-3 is added to various cells, it can bind to cell surface proteins that have attached carbohydrates recognizable by the lectin. However, there is a great deal of evidence that galectin-3 that is present inside the cells regulates various cellular functions through intracellular actions (without the protein being secreted). We have obtained important information on the functions of galectin-3 by studying genetically engineered mice we generated that lack galectin-3. Most recently, we found that galectin-3 plays an important function in the response of T cells. We found that galectin-3 is clustered inside the cells in the area that is important for the T cell response called the immunological synapse. We also found that galectin-3 has an important function in another cell type called dendritic cells. We have previously demonstrated that galectin-3 promotes allergic airway inflammation. We now have a significant amount of data supporting the role of this protein in a mouse model of atopic dermatitis. Additional work is required for understanding how galectin-3 regulates these inflammatory processes and for advancing strategies for developing galectin-3-targeting therapies. In this proposal, we plan to establish the mechanism by which galectin-3 regulates the responses of T cell and dendritic cell, which are both key cell types in the development of allergic skin inflammation associated with atopic dermatitis. We also plan to elucidate the cellular basis for galectin-3's regulatory role in a mouse model of atopic dermatitis.