Nitric Oxide-Mediated Lacrimal Gland Damage in Sjogren's Syndrome

一氧化氮介导的干燥综合征泪腺损伤

• 批准号: 7126135
• 负责人: PAUL C BRANDT
• 金额: $ 21.83万
• 依托单位: TEXAS A&M UNIVERSITY HEALTH SCIENCE CTR
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2008-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7126135
• 关键词: Sjogren' s syndrome; acinar cell; apoptosis; keratoconjunctivitis sicca; lead; nitric oxide; peroxynitrites

DESCRIPTION (provided by applicant): Sjogren's syndrome is an autoimmune disorder of poorly understood etiology that affects over 4,000,000 Americans every year. One of its hallmark symptoms is lacrimal gland dysfunction leading to dry eye. Aqueous tear production from the lacrimal gland occurs via acini which secret components of the fluids into the ducts of the glands. The acini are organized structures that contain specialized acinar epithelial cells. Acinar cells in the lacrimal glands from Sjogren's syndrome patients undergo apoptosis, while those from individuals with non-Sjogren's dry eye do not. This suggests that in Sjogren's Syndrome selective apoptosis of the acinar cells would reduce tear formation. The underlying mechanism for selective acinar cell apoptosis is not known. However, in the MRL/lpr mouse, a frequent model for Sjogren's Syndrome, lacrimal gland damage begins in the first month after birth. During this period, infiltration by Tlymphocytes occurs and interleukin (IL)-1beta production increases. It has been observed that lymphocytic infiltration of the lacrimal gland of MRL/lpr mice triggers acinar cells to start IL-1beta production and this production was limited to the acinar cells. We have previously shown that IL-1beta can stimulate nitric oxide (NO) production in lacrimal gland acinar cells and this production could be blocked with the specific inducible nitric oxide synthase (iNOS) inhibitors. Excessive NO production could be toxic to the lacrimal gland. NO biosynthesis can lead to production of peroxynitrite which has been coupled to apoptosis. These observations allow us to propose the following Central Hypothesis: In Sjogren's Syndrome, pro-inflammatory cytokines from the lymphocytic infiltrate of the lacrimal gland stimulates supranormal IL-1beta production in the acinar cells which leads to elevated NO levels with concomitantly increased peroxynitrite formation. Excessive peroxynitrite initiates apoptosis in the acinar cells. To test this hypothesis we will undertake the following three Aims. 1. Levels of IL-1beta, iNOS and peroxynitrite-modified proteins will be quantified in lacrimal glands from MRL/lpr mice and controls as a function of disease development. This Aim will test for correlations between IL-1beta, iNOS and peroxynitrite levels and apoptosis in lacrimal glands of MRL/lpr mice that are not found in controls. 2. The ability of NO synthesis antagonists and peroxynitrite decomposition catalysts to prevent apoptotic lacrimal gland damage will be assessed. This Aim will test whether NO and/or peroxynitrite are necessary for lacrimal gland acinar cell apoptosis or other lacrimal gland damage. 3. MRL/lpr mice will be bred with mice containing homozygous knockouts of the IL-1beta or iNOS genes to produce lines that do not produce these proteins and still have a defect in Fas. These hybrid animals will be tested for age-dependent damage to the lacrimal gland. This will test the Central hypothesis by genetically removing proteins we hypothesize to be necessary for lacrimal gland damage in Sjogren's Syndrome. This research is very significant because the outcome of these studies will lead the way to development of new methods for preventing or diminishing the development of dry eye in individuals afflicted Sjogren's Syndrome and perhaps related autoimmune disorders such as Systemic Lupus Erythematosus.

描述（由申请人提供）：干燥综合征是一种病因学知之甚少的自身免疫性疾病，每年影响超过 4,000,000 名美国人。其标志症状之一是导致干眼的泪腺功能障碍。泪腺通过腺泡产生水性泪液，腺泡将液体成分分泌到腺管中。腺泡是含有特殊腺泡上皮细胞的组织结构。干燥综合征患者泪腺中的腺泡细胞会发生凋亡，而非干燥综合征患者的泪腺腺泡细胞不会发生凋亡。这表明在干燥综合症中，腺泡细胞的选择性凋亡会减少泪液形成。 选择性腺泡细胞凋亡的潜在机制尚不清楚。然而，在 MRL/lpr 小鼠（干燥综合征的常见模型）中，泪腺损伤在出生后第一个月就开始了。在此期间，T 淋巴细胞发生浸润，白细胞介素 (IL)-1β 产量增加。据观察，MRL/lpr小鼠泪腺的淋巴细胞浸润触发腺泡细胞开始产生IL-1β，并且这种产生仅限于腺泡细胞。 我们之前已经证明，IL-1β 可以刺激泪腺腺泡细胞中一氧化氮 (NO) 的产生，并且可以用特定的诱导型一氧化氮合酶 (iNOS) 抑制剂来阻断这种产生。过量的一氧化氮产生可能对泪腺有毒。 NO 生物合成可导致过氧亚硝酸盐的产生，过氧亚硝酸盐与细胞凋亡相关。这些观察结果使我们能够提出以下中心假设：在干燥综合征中，来自泪腺淋巴细胞浸润的促炎细胞因子刺激腺泡细胞中超正常的 IL-1β 产生，导致 NO 水平升高，同时过氧亚硝酸盐形成增加。过量的过氧亚硝酸盐会引发腺泡细胞凋亡。 为了检验这一假设，我们将实现以下三个目标。 1. 对 MRL/lpr 小鼠和对照的泪腺中 IL-1β、iNOS 和过氧亚硝酸盐修饰蛋白的水平进行定量，作为疾病发展的函数。该目标将测试 MRL/lpr 小鼠泪腺中 IL-1β、iNOS 和过氧亚硝酸盐水平与细胞凋亡之间的相关性，而在对照中未发现这种相关性。 2.评估NO合成拮抗剂和过氧亚硝酸盐分解催化剂防止泪腺凋亡损伤的能力。该目的将测试一氧化氮和/或过氧亚硝酸盐是否是泪腺腺泡细胞凋亡或其他泪腺损伤所必需的。 3. MRL/lpr 小鼠将与含有 IL-1beta 或 iNOS 基因纯合敲除的小鼠交配，产生不产生这些蛋白质但仍具有 Fas 缺陷的品系。这些杂交动物将接受年龄相关的泪腺损伤测试。这将通过基因去除我们假设的干燥综合征泪腺损伤所必需的蛋白质来测试中心假设。 这项研究非常重要，因为这些研究的结果将引导开发新方法来预防或减少患有干燥综合症和可能相关的自身免疫性疾病（例如系统性红斑狼疮）的个体干眼症的发展。