Stimulus-Secretion Coupling in Diseased Lacrimal Gland

描述(申请人提供)：泪腺的炎症性疾病，如干燥综合征、结节病和慢性移植物抗宿主病，或仅仅发生在高龄时，会导致泪膜水层分泌不足，这是干性角结膜炎(KCS)或干眼综合征的主要原因。这些疾病的共同特征是泪腺慢性炎症(损伤)的表型迹象，实质组织(分泌泪液的腺泡和导管上皮细胞)丢失，腺体无法自我修复。到目前为止，干眼症还没有治愈方法。我们最近发现泪腺含有保留慢周期祖细胞的标记，这些细胞参与了实验性损伤后的修复。我们还发现，在修复阶段，具有间充质干细胞(MSC)表型的细胞是通过诱导上皮向间充质转化(EMT)而产生的。MSCs积极参与泪腺修复，生成腺泡和导管上皮细胞，恢复足够的泪液产量。在目前的提案中，我们利用这些发现，假设：1)在自身免疫驱动的泪腺缺陷动物模型中，泪腺修复机制受到损害，主要是因为它们的细胞外基质被破坏，2)操纵基质金属蛋白酶(MMPs)，特别是MMP2和/或9的表达/活性可以促进泪腺再生，3)外源干细胞的输送将加速炎症的泪腺的愈合过程。为了验证这些假设，我们提出了以下具体目标：1-研究慢性炎症泪腺中细胞外基质、细胞黏附分子和基质修饰酶的变化；2-测试操纵MMP2和9的表达和/或活性将促进慢性炎症泪腺愈合的假设；3-使用遗传细胞谱系追踪来进一步表征在实验诱导的泪腺损伤期间参与启动EMT和间充质-上皮转化(MET)的细胞的表型；以及4-测试体外培养的MSCs在体内移植到自身免疫性泪腺缺陷动物模型中加速病变泪腺修复的潜力。由于泪腺产生水分的细胞丧失，目前还没有治愈严重干眼症的方法。这里描述的研究，如果成功，将导致阻止，甚至逆转这些细胞的丧失的新策略，这将恢复正常的泪液产生，并缓解与干眼综合征相关的眼表不适。

DESCRIPTION (provided by applicant): Inflammatory diseases of the lacrimal gland such as Sj¿gren's syndrome, sarcoidosis, and chronic graft versus-host disease or simply as occurs with advanced age, lead to inadequate secretion of the aqueous layer of the tear film, which is a leading cause of keratoconjunctivitis sicca (KCS) or dry eye syndromes. Common denominators for these diseases are the phenotypic signs of chronic inflammation (injury) of the lacrimal gland with loss of parenchymal tissue (the tear secreting acinar and ductal epithelial cells) and the inability of the gland to repair itself. To date there are no cures for dry eye syndromes. We recently discovered that the lacrimal gland contains label retaining slow cycling progenitor cells that are involved in repair following experimentally induced injury. We also discovered that during the repair phase, cells with a mesenchymal stem cell (MSC) phenotype are generated through induction of epithelial-to-mesenchymal transition (EMT). MSCs actively participate in lacrimal gland repair to generate acinar and ductal epithelial cells and restore adequate tear production. In the present proposal, we are capitalizing on these discoveries by hypothesizing that: 1) lacrimal gland repair mechanisms are compromised in animal models of autoimmune-driven lacrimal gland deficiencies largely because their extracellular matrix is disrupted, 2) manipulation of matrix metalloproteinases (MMPs), especially MMP2 and/or 9 expression/activity may improve lacrimal gland regeneration, and 3) that delivery of exogenous stem cells will accelerate the healing process of inflamed lacrimal glands. To test these hypotheses, we propose the following specific aims: 1-Iinvestigate changes in the extracellular matrix, cell adhesion molecules and matrix modifying enzymes in chronically inflamed lacrimal glands; 2-Test the hypothesis that manipulation of MMP2 and 9 expression and/or activity would improve healing of chronically inflamed lacrimal glands; 3-To use genetic cell lineage tracing to further characterize the phenotype of the cells involved in initiation of EMT and mesenchymal-epithelial transition (MET) during experimentally induced injury to the lacrimal gland; and 4-Test the potential of cultured MSCs to accelerate repair of diseased lacrimal glands when delivered in vivo to animal models of autoimmune lacrimal gland deficiency. There are currently no cures for severe dry eye resulting from loss of the moisture producing cells of the lacrimal glands. The studies described here, if successful, will lead to new strategies to halt, and maybe reverse, the loss of these cells which will restore normal tear production and alleviate the ocular surface discomfort associated with dry eye syndromes.