Age-Related Meibomian Gland Dysfunction

项目总结/摘要 本项目的长期目标是了解年龄相关性睑板腺功能障碍的机制 (MGD)和蒸发性干眼EDED。我们实验室最近发表的使用受激拉曼的研究 评估睑板腺脂质质量（睑脂）的光谱（SRS）表明， 当正常睑脂从腺泡逐渐移动到 孔。这一发现表明正常的睑母细胞分化包括从睑脂中去除蛋白质 然后释放到泪膜上。此外，我们的实验室已经表明，小鼠暴露在低湿度， 已知诱导EDED体征的环境应激，显示出睑板腺的显著过度增殖， 在睑脂中保留蛋白质的腺体，表明环境应激诱导异常或 不完全的痣细胞分化。这些发现支持了两个可供选择的假设 MGD的发展：1）环境压力或老化导致不完整或异常的痣细胞 在某些实施方案中，脂质分化导致蛋白质在睑脂中的滞留、脂质流动性的丧失和脂肪化。（2） 衰老和/或反复的环境应激导致睑板细胞干细胞和睑板细胞的耗竭。 腺脱落这些假说强调了关于睑板腺的两个主要知识空白 功能：GAP 1，而睑脂的脂质组成和潜在的激素和其他危险因素的MGD 虽然已经进行了深入的研究，但关于睑板细胞分化以及细胞和分子生物学特性知之甚少。 控制这个过程的机制。GAP 2，虽然睑板腺泡细胞的周转率 虽然已经研究过，但睑板腺干细胞的存在仍然存在争议， 环境压力、老化和性别是未知的。以下具体目标将检验我们的假设， 探讨这些差距的知识：1）使用SRS表征蛋白质与脂质的比例（P/L）表达 来自表现出EDED的体征和症状的人类受试者的睑脂以及与EDED/MGD相关的P/L比率 临床研究中的严重程度。2)明确痣细胞分化的细胞和分子机制， 体外解体，并确定环境应力，年龄和性别对雄激素分泌细胞的影响 体内分化。3)通过谱系追踪确定睑板细胞和导管上皮更新的来源 并确定环境应激、年龄和性别对睑板腺导管上皮的影响， 使用Confetti和H2 B-GFP/K5 tTA小鼠的痣细胞更新和IT重建。

Project Summary/Abstract The long-term goal of this project is to understand the mechanism of age-related meibomian gland dysfunction (MGD) and evaporative Dry Eye EDED. Recent published studies from our laboratory using Stimulated Raman Spectroscopy (SRS) to evaluate meibomian gland lipid quality (meibum) indicate that there is a decrease in protein content of normal meibum within individual glands as it moves progressively from the acinus to the orifice. This finding suggests that normal meibocyte differentiation involves removal of protein from meibum prior to release onto the tear film. Additionally our laboratory has shown that mice exposed to low humidity environmental stress, known to induce signs of EDED, display marked hyperproliferation of the meibomian gland with retention of protein in the meibum lipid suggesting that environmental stress induces abnormal or incomplete meibocyte differentiation. These findings support two alternative HYPOTHESES for the development of MGD:1) Environmental stress or aging leads to incomplete or abnormal meibocyte differentiation causing retention of protein in meibum, loss of lipid fluidity and inspissation. And 2) Aging and/or repeated environmental stress leads to depletion of meibocyte stem cells and meibomian gland dropout. These hypotheses emphasize two MAJOR GAPS in knowledge regarding meibomian gland function: GAP1, while the lipid composition of meibum and potential hormonal and other risk factors for MGD has been intensively studied, little is known regarding meibocyte differentiation and the cellular and molecular mechanisms that control this process. GAP2, although the turnover rate for the meibomian gland acinar cells has been studied, the presence of meibomian gland stem cells remains controversial and the effects of environmental stress, aging and sex are unknown. The following Specific Aims will test our hypotheses and explore these GAPS in knowledge: 1) Characterize using SRS the protein to lipid ratio (P/L) in expressed meibum from human subjects exhibiting signs and symptoms of EDED and correlate P/L ratio to EDED/MGD severity in a clinical study. 2) Identify the cellular and molecular mechanism of meibocyte differentiation and disintegration in vitro and determine the effects of environmental stress, aging and sex on meibocyte differentiation in vivo. 3) Identify the source of meibocyte and ductal epithelial renewal through lineage tracing and determine the effects of environmental stress, age and sex on meibomian gland ductal epithelial and meibocyte renewal using Confetti and the H2B-GFP/K5tTA mice and IT reconstruction.