The Structure and Function of Dental Lymphatics (R21)

淋巴管(LV)系统是与现有血液循环系统平行的循环系统。 几乎在所有的组织中。LV系统的一个主要功能是将渗出的间质液体返回到 血管(BV)循环此外，LV还充当抗原运输和抗原呈递的管道。 细胞从周围组织部位转移到引流淋巴结，从而允许诱导获得性免疫。 LV在牙髓中的存在仍然是一个有争议的问题；对于LV是否存在还没有达成共识 在牙髓中的作用到目前为止已经达到了。此外，即使在那些支持存在 牙科LV，牙科LV系统的整体组织及其三维(3D)结构尚未被 演示了。此外，假想的牙科LV系统是否参与免疫炎症调节， 与LV在其他器官系统中的作用相似，这是一个尚未解决的重要问题。 我们最近使用Prox1-EGFP小鼠模型鉴定了牙髓中LV的3D网络 Prox1启动子驱动淋巴内皮细胞(LEC)特异性表达EGFP。如图所示 双光子显微镜，该网络由微毛细血管(直径≃3-5微米)组成，形成致密的神经丛。 主要用于牙髓室，连接到更大的血管(直径为10-15微米的≃)，这些血管作为 从牙髓室底部通过根管的束状物。此外，我们还发现牙髓感染 核梭杆菌可导致48小时内冠状微血管左室神经丛消失， 提示牙髓感染可导致牙髓中LEC的迅速死亡。 所识别的牙齿LV网络的组件彼此之间的结构和功能关系 而在其他器官中已发现的不同类型的LV尚不清楚。此外，该机制 感染引起的左心室丢失的原因尚未确定。对这些问题的回答预计将有助于 牙科LV在宿主对牙科病原体免疫中的作用 在这份提案中，组建的多学科团队将进一步调查该系统的结构、功能和 应用新型动物模型--双光子显微技术研究牙髓LV网络的病理生理变化 复制，牙科感染模型，和荧光颗粒跟踪分析，以确认已识别的LV网络 将牙髓物质输送到引流的淋巴结。具体目标如下： 目的1.鉴定小鼠牙髓中正常淋巴管的特征 目的2.检测牙髓淋巴管对牙髓感染的反应 成功完成拟议的目标将极大地促进我们对LV生物学的理解， 牙髓生物学，以及对牙齿感染的免疫反应，预计将导致重点关注后续项目 牙髓中宿主病原体的关系。

The lymphatic vessel (LV) system is a parallel circulatory system to the blood circulatory system present in almost all tissues. One major function of the LV system is the return of extravasated interstitial fluid to the blood vessel (BV) circulation. In addition, LV act as conduits for the traffic of antigens and antigen-presenting cells from peripheral tissue sites to draining lymph nodes, thereby permitting the induction of adaptive immunity. The existence of LV in dental pulp is still a controversial issue; no consensus as to whether LV are present in the dental pulp has hitherto been reached. In addition, even in those studies that support the existence of dental LV, the overall organization of the dental LV system and its three-dimensional (3D) structure has not been demonstrated. Furthermore, whether a putative dental LV system is involved in immune-inflammatory regulation, similar to the role of LV in other organ systems, is an important question that has not been addressed. We have recently identified a 3D network of LV in dental pulp using a Prox1-eGFP mouse model in which the Prox1 promoter drives expression of eGFP specifically in lymphatic endothelial cells (LEC). As imaged by Two-photon microscopy, the network comprises of microcapillaries (≃3-5 um in diameter) that form dense plex- uses mainly in the pulp chamber and which connect to larger vessels (≃10-15 um in diameter) that travel as a bundle from the pulp chamber floor through the root canals. In addition, we found that infection of dental pulp with Fusobacterium nucleatum resulted in disappearance of coronal microcapillary LV plexuses within 48 hours, suggesting that pulpal infection induces rapid death of LEC in the dental pulp. The structural and functional relationship of components of the identified dental LV network to each other and to the different types of LV that have been identified in other organs is unknown. In addition, the mechanism of infection-induced LV loss has not been determined. Answers to these questions are expected to inform upon the role of dental LV in host immunity to dental pathogens. In this proposal, the assembled multidisciplinary team will further investigate the structure, function, and pathophysiological changes of the dental pulp LV network using an innovative animal model, two-photon micros- copy, a dental infection model, and a fluorescent particle-tracking assay to confirm that the identified LV network conveys pulpal material to draining lymph nodes. There are two specific aims as follows: Aim 1. To characterize normal lymphatics in mouse dental pulp Aim 2. To examine the response of dental pulp lymphatics to pulpal infection Successful completion of the proposed aims will significantly advance our understanding of LV biology, pulp biology, and the immune response to dental infection and is expected to lead to follow-up projects that focus upon host pathogen relationships in the dental pulp.