Epithelial stem cells in Meibomian gland development and homeostasis

上皮干细胞在睑板腺发育和稳态中的作用

• 批准号: 10341666
• 负责人: Lu Le
• 金额: $ 41万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-30 至 2026-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10341666
• 关键词: Ablation; Acinus organ component; Address; Adult; Affect; Aging; Atrophic; Biological Process; Blindness; Capsid Proteins; Cells; Congenital Disorders; Contact Lenses; Cornea; Corneal Abrasion; Data; Development; Disease; Dropout; Dry Eye Syndromes; Duct (organ) structure; EGR2 gene; Embryo; Epithelial; Epithelial Cells; Excessive tearing; Eye; Eyelid structure; Genes; Genetic; Genetic Transcription; Gland; Hair; Hair follicle structure; Hair shaft structure; Homeostasis; Human; Inflammation; Knowledge; Label; Laboratories; Lead; Left; Life; Lipids; Lubrication; Mesenchyme; Modeling; Molecular; Morphogenesis; Morphology; Mus; Mutant Strains Mice; Oils; Pathway interactions; Persons; Pharmacotherapy; Physiological; Population; Pre-Clinical Model; Prevalence; Process; Proteins; Reporting; Research; Risk Factors; Role; Sebaceous Glands; Secondary to; Structural defect; System; Testing; base; clinical application; epithelial stem cell; evaporation; exhaustion; follow-up; gland development; in vivo; innovation; insight; keratinization; meibomian gland; meibomian gland dysfunction; mouse model; novel; ocular surface; postnatal; prevent; screening; stem cell biology; stem cell differentiation; stem cell population; stem cells; tool; transcription factor

Project Summary Dry eye disease (DED), which occurs when there is inadequate lubrication of the eyes due to insufficient tears or excessive tear evaporation, affects over 16 million adults in the U.S., and the prevalence continues to increase. If left untreated, DED can lead to serious problems including inflammation of the eye, corneal abrasions, and even vision loss. While DED can be due to a variety of causes, ~90% of cases are due to Meibomian gland dysfunction (MGD). The Meibomian glands (MGs) are holocrine sebaceous glands located in the eyelids. Differentiated meibocytes within the MGs secrete meibum, a mixture of lipids and proteins that coats the ocular surface and prevents tear evaporation. MGD can be due to reduced meibum secretion, resulting from abnormal MG activity, blockage of the MG orifice due to hyper-keratinization, or structural defects such as MG atrophy or dropout. Another possible cause of MGD is stem cell exhaustion, in which MG resident stem cells are unable to replenish meibocytes due to dysregulated stem cell differentiation. MG development is well-conserved in mice and humans. In mice, MGs begin to develop at embryonic day 18.5 from the ectodermal epithelium; the MG anlage grows out of the eyelid mesenchyme, elongates, branches, and differentiates into ductules that form the acini; one MG contains clusters of these secretory acini which contain the meibocytes. MGs are fully formed by postnatal day 15. Throughout life, meibocytes are replenished from a stem cell population within the acini. While MG morphological development has been well described, the identity of the stem cell population(s) that gives rise to the MG remains controversial. Additionally, the resident stem cell population responsible for replenishing meibocytes after holocrine secretion in mature MG has not been definitively identified. Previous studies indicate there is a limited number of precursor meibocytes, which may be the cause of stem cell exhaustion that can occur with aging. Thus, the stem cell origin(s) and molecular mechanisms underlying MG development and homeostasis, i.e. replacement of acinar meibocytes throughout life, remain major knowledge gaps in the field. A recent study from our laboratory identified Krox20 as a marker of a stem cell population in the hair follicle that differentiates into hair shaft progenitor cells in the hair matrix, and ultimately constitutes the structural component of the hair shaft (Liao, G&D, 2017). Follow-up preliminary studies revealed that a population of Krox20+ cells also gives rise to the MG and depletion of these Krox20+ cells or the KROX20 protein results in lack of MGs. These data highlight a critical role for Krox20 in MG development. We hypothesize that Krox20 marks a novel stem cell population that gives rise to the MG. Our objectives in this proposal are to investigate the role of these Krox20+ cells in MG morphogenesis and homeostasis, and delineate the mechanisms by which KROX20 exerts its biological function in MG. The identification, isolation, and study of this previously unidentified MG stem cell will provide insights that will advance the field, filling a current knowledge gap, as well as providing a novel murine model of MGD-based DED that offers a platform for testing potential therapies for DED.

项目摘要 干眼症（DED），由于泪液不足导致眼睛润滑不足时发生 或者说过度的眼泪蒸发，影响着美国超过1600万的成年人，并且患病率继续增加。 如果不及时治疗，DED会导致严重的问题，包括眼睛炎症，角膜擦伤， 甚至失明虽然DED可能是由于各种原因，但约90%的病例是由于睑板腺 功能障碍（MGD）。睑板腺（MG）是位于眼睑中的全分泌皮脂腺。 MG内的分化的睑板细胞分泌睑脂，其是覆盖眼周的脂质和蛋白质的混合物。 表面和防止眼泪蒸发。MGD可由于睑脂分泌减少，导致异常 MG活动，由于过度角化导致的MG孔堵塞，或结构缺陷，如MG萎缩或 辍学生MGD的另一个可能的原因是干细胞衰竭，其中MG驻留干细胞无法 由于干细胞分化失调而补充痣细胞。MG的发展在小鼠中是非常保守的 还有人类在小鼠中，MG开始在胚胎第18.5天从外胚层上皮发育; MG 原基从眼睑间充质中生长出来，伸长，分支，并分化成小管， 腺泡;一个MG含有这些分泌腺泡的簇，其含有睑板细胞。MG完全由 产后第15天。在整个生命过程中，睑板细胞从腺泡内的干细胞群补充。而 MG的形态学发育已经被很好地描述，提供MG的干细胞群体的身份是已知的。 MG的崛起仍有争议。此外，负责补充的常驻干细胞群 成熟MG中全分泌分泌后的睑板细胞尚未明确鉴定。先前的研究表明 存在有限数量的前体睑板细胞，这可能是干细胞耗尽的原因， 随着年龄的增长而发生。因此，干细胞起源和MG发展的分子机制以及 体内平衡，即整个生命中腺泡睑板细胞的替换，仍然是该领域的主要知识空白。 我们实验室最近的一项研究将Krox 20确定为毛囊干细胞群的标志物 分化成毛干祖细胞在头发基质，并最终构成结构 毛干的组成部分（廖，G&D，2017）。后续初步研究显示， Krox 20+细胞也产生MG，这些Krox 20+细胞或KROX 20蛋白的消耗导致MG的产生。 缺少MG。这些数据突出了Krox 20在MG开发中的关键作用。我们假设Krox 20 标志着一个新的干细胞群，引起MG。我们的目标是调查 这些Krox 20+细胞在MG形态发生和稳态中的作用，并描述了其机制， KROX 20在MG中发挥其生物学功能。对这种以前未被发现的 MG干细胞将提供见解，将推动该领域，填补目前的知识空白，以及提供 一种新的基于MGD的DED小鼠模型，为测试DED的潜在疗法提供了平台。