Galectin-3 in regulation of allergic skin inflammation

描述（由申请人提供）：特应性皮炎是一种常见的慢性炎症性皮肤病。这是一个严重的医学问题，在工业化国家，多达15-20%的儿童受到这种疾病的影响。特应性皮炎的治疗仍然是一个挑战。目前的模型表明，特应性皮炎是由于Th 2介导的炎症反应和T细胞，树突状细胞和肥大细胞发挥重要作用。该提案旨在确定半乳糖凝集素家族成员在特应性皮炎中的作用，长期目标是开发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一员，由其对2-半乳糖苷和共有序列的亲和力定义。它由许多细胞类型表达，包括上皮细胞和各种白细胞。已经通过使用外源添加的半乳糖凝集素-3证明了许多细胞外功能，这些功能与其结合和交联细胞表面聚糖有关。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各种细胞功能。通过研究来自半乳糖凝集素-3缺陷小鼠的T细胞，我们已经证明半乳糖凝集素-3是Th 1细胞中的抑制性调节剂，并且通过促进TCR下调来抑制T细胞受体（TCR）介导的Th 1应答。半乳糖凝集素-3位于细胞内由TCR接合激活的T细胞中的免疫突触处。我们还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，我们发现阿利克斯作为半乳糖凝集素-3结合伴侣，这是已知的内体分选复合物所需的运输（ESCRT）和多泡体（MVB）的组成部分。我们还有其他信息表明半乳糖凝集素-3与MVB和外来体相关。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Th 2应答并抑制Th 1应答，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。在该提案中，我们计划测试以下假设：半乳糖凝集素-3 1）通过在IS处起作用而抑制TCR介导的Th 1应答; 2）通过抑制IL-12产生并作为外泌体相关蛋白起作用而对树突状细胞的抗原呈递功能至关重要; 3）通过树突状细胞和肥大细胞（除了T细胞之外）促进过敏性皮肤炎症。 公共卫生相关性：特应性皮炎是一种常见的慢性炎症性皮肤病。在过去三十年中，在工业化国家，这种疾病的流行率增加了两到三倍，目前儿童的流行率估计为15- 20%。这种疾病的治疗仍然是一个挑战。阐明这种疾病的细胞和分子基础对于开发新的治疗策略是重要的。 半乳糖凝集素-3是结合碳水化合物的蛋白质家族的成员，称为凝集素。半乳糖凝集素家族通过其2-半乳糖苷的结合和共享相似的氨基酸序列来定义。当半乳糖凝集素-3被添加到各种细胞中时，它可以结合细胞表面蛋白，这些蛋白具有可被凝集素识别的附着碳水化合物。然而，有大量的证据表明，存在于细胞内的半乳糖凝集素-3通过细胞内作用调节各种细胞功能（而不分泌蛋白质）。 我们通过研究我们产生的缺乏半乳糖凝集素-3的基因工程小鼠，获得了关于半乳糖凝集素-3功能的重要信息。最近，我们发现半乳糖凝集素-3在T细胞的反应中起着重要的作用。我们发现半乳糖凝集素-3聚集在细胞内对T细胞反应很重要的区域，称为免疫突触。我们还发现半乳糖凝集素-3在另一种称为树突状细胞的细胞类型中具有重要功能。 我们以前已经证明，半乳糖凝集素-3促进过敏性气道炎症。我们现在有大量的数据支持这种蛋白质在特应性皮炎小鼠模型中的作用。需要更多的工作来了解半乳糖凝集素-3如何调节这些炎症过程，并推进开发半乳糖凝集素-3靶向疗法的策略。 在这项提案中，我们计划建立半乳糖凝集素-3调节T细胞和树突状细胞反应的机制，这两种细胞类型都是与特应性皮炎相关的过敏性皮肤炎症发展中的关键细胞。我们还计划阐明半乳糖凝集素-3在小鼠特应性皮炎模型中的调节作用的细胞基础。

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.