Role of Primary Cilia-mediated Signaling in Development and Regeneration of the Meibomian Glands

干眼病(DED)是一种常见的多因素疾病，全球患病率从5%到50%不等。 睑板腺功能障碍(MGD)被认为是DED的主要原因。眉板腺(MG)是 修饰的皮脂腺，排列在眼睑边缘，在眼表和眼表分泌脂类 参与增加泪膜的稳定性。MG是全分泌腺，这意味着它们是 自从它们通过细胞凋亡产生被称为meiban的分泌产物以来，它们就一直在更新。因此，监管 MG干细胞是保证MG正常功能的关键。目前，有效发展的一个重大障碍 治愈MGD的治疗方法是支持发育和干细胞的基本细胞机制- 人们对MG的依赖维护知之甚少。有趣的是，MG开发与 毛囊单位的发育，其中初级纤毛和刺猬(HH)途径起着重要作用 在毛囊(HF)发育和维持干细胞生态位中的作用。 我们的初步数据，使用鼠标作为模型系统，为老鼠的纤毛和 HH通路在MG的正常发育过程中起着不同的作用。我们发现HH活性很高 在MG的早期发育阶段。然而，MG内HH反应细胞的数量减少 随着发展的进步。在成人的腺泡和MG的分离细胞中检测到HH活性 排泄管。此外，我们发现，当通过SMO缺失使HH途径失活时，或 阻碍MG的形成，阻止纤毛形成的IFT88缺失导致肥厚性MG。 本研究的目的是阐明初级纤毛和HH信号的功能。 MG发展和更新过程中的途径，长期目标是寻找新的治疗方法 旨在促进MG更新换代。为了解决这些问题，我们已经开发了特定的遗传工具和 开发了一种3D成像分析方法，使我们能够：a)研究纤毛和HH的定位 在眉毛腺发育和内稳态的背景下的反应细胞。B)阐明 MG发育和动态平衡过程中的HH途径和初级纤毛。这项工作的成果将是 揭示初级纤毛信号对实现正常MG形态发生所必需的整合作用。重要的是 纤毛相关信号级联的描绘将有助于确定新的治疗策略 治疗DED。

Dry eye disease (DED) is a common, multifactorial disease with a global prevalence ranging from 5 to 50%. Meibomian gland dysfunction (MGD) is considered the leading cause of DED. Meibomian glands (MG) are modified sebaceous glands which line the margin of the eyelid and secrete lipids at the ocular surface and participate to increase the stability of the tear film. MG are holocrine glands, which implies that they are continually renewed since they deliver their secretory product, called meibum, by apoptosis. Thus, regulation of MG stem cells is crucial to ensure proper function of MG. Currently, a significant hurdle in developing effective treatments to cure MGD is that the basic cellular mechanisms underlying the development and the stem cell- dependent maintenance of the MG are poorly understood. Interestingly, MG development shares similarities with the development of the pilosebaceous unit where primary cilia, and the hedgehog (HH) pathway play essential roles in hair follicle (HF) development and in maintaining a stem cell niche. Our preliminary data, using the mouse as a model system, mouse provide strong evidence that the cilium and the HH pathway play distinct roles during normal development of the MG. We found that the HH activity is high during early developmental stages of the MG. However, the number of HH responsive cells in the MG decreases as development progresses. In the adult, HH activity was detected in isolated cells of the acini and in the MG excretory duct. Moreover, we found that while inactivation of the HH pathway via SMO deletion abolishes or impairs the formation of MG, the deletion of IFT88, which prevents cilia formation, leads to hypertrophic MG. The objective of the proposed study is to elucidate the function of the primary cilium and the HH signaling pathway during the development and renewal of the MG with the long-term goal to identify new therapeutic targets to promote MG renewal. To address these issues, we have generated specific genetic tools and developed a 3D imaging analysis approach that will allow us to: a) To study the localization of ciliated and HH responsive cells in the context of Meibomian gland development and homeostasis. b) To elucidate the role of the HH pathway and the primary cilium during MG development and homeostasis. The outcome of this work will reveal the integrative role of primary cilia signaling necessary to achieve normal MG morphogenesis. Importantly, delineation of the cilia-related signaling cascades will enable the identification of new therapeutic strategies to treat DED.