Central and Peripheral Mechanisms of Corneal Pain

角膜是身体中神经支配最密集的组织，并且疼痛是由以下引起的主要体验： 角膜刺激虽然生理性角膜疼痛（伤害性疼痛）保护眼睛免受伤害， 炎症和/或神经损伤可导致长期或慢性角膜疼痛。角膜传入神经代表 一个多样化的神经元群体，具有与维持眼部健康相关的专门特性。充分 这些神经元的多样性及其对损伤的反应尚不清楚。第一组实验将 确定三叉神经节（TG）中小鼠角膜神经元的mRNA转录特征及其 角膜损伤的转录反应，并与细胞类型特异性转录和表观基因组比较 人类TG神经元的特征。已知角膜传入投射到脊髓中的两个主要区域 三叉神经核（VSP），每一个在伤害感受和维持角膜稳态中具有不同的作用。我们有 初步数据表明，额外的投影外侧臂旁核（lPBN），一个区域 在调节对厌恶刺激的复杂动机-情感反应中至关重要。其对角膜的贡献 疼痛是未知的。第二组实验将检查IPBN中角膜输入的中央处理。 我们将确定角膜->lPBN初级传入投射对角膜伤害性感受的贡献。 lPBN神经元在角膜伤害性和慢性痛行为中的反应和功能。额外 研究将进行单核转录组分析，以确定角膜激活的 脑干神经元，然后进行多重原位杂交，以提供空间分辨率的区域， 接受直接角膜传入输入。角膜也被赋予常驻角膜白细胞（RCL） 存在于角膜神经附近，这表明在角膜中存在神经免疫串扰的可能性。 角膜然而，目前的知识是有限的可能直接调节RCL通过角膜神经，或 RCL对角膜神经功能的影响。第三组实验将描述细胞的特征 参与神经免疫串扰的群体和分子机制导致周围神经 致敏作用。与小鼠角膜疼痛相关的角膜单细胞mRNA转录特征 模型将用于鉴定伤害感受器致敏的转录变化。穿越这些 免疫细胞转录本与角膜传入的转录本谱将为配体-受体结合提供证据。 对.体外研究将证实所鉴定的调节剂使TG神经元敏化的能力，以及所鉴定的调节剂对TG神经元敏化的能力。 将使用行为和离体电生理学评估功能显著性。采用 多学科的方法，这些实验将提供全面的分析细胞和分子 伤害性和慢性角膜疼痛的机制，导致识别新的途径， 治疗。

The cornea is the most densely innervated tissue in the body, and pain is the primary experience resulting from corneal stimulation. While physiological corneal pain (nociceptive pain) protects the eye from injury, inflammation and/or nerve damage can result in prolonged or chronic corneal pain. Corneal afferents represent a diverse population of neurons, with specialized properties related to maintaining ocular health. The full diversity of these neurons, and their responses to injury are unknown. The first set of experiments will determine the mRNA transcript signatures of mouse corneal neurons in the trigeminal ganglion (TG) and their transcriptional responses to corneal injury and compare with cell-type-specific transcriptional and epigenomic signatures of human TG neurons. Corneal afferents are known to project to two main regions in the spinal trigeminal nucleus (Vsp), each with distinct roles in nociception and maintaining corneal homeostasis. We have preliminary data demonstrating an additional projection to the lateral parabrachial nucleus (lPBN), a region critical in regulating complex motivational-affective responses to aversive stimuli. Its contribution to corneal pain is unknown. The second set of experiments will examine central processing of corneal input in the lPBN. We will determine the contribution of corneal->lPBN primary afferent projections to corneal nociceptive responses and the function of lPBN neurons in corneal nociceptive and chronic pain behaviors. Additional studies will perform single-nucleus transcriptome analysis to identify molecular profiles of corneal-activated brainstem neurons, followed by multiplex in situ hybridization to provide spatial resolution in regions that receive direct corneal afferent input. The cornea is also endowed with resident corneal leukocytes (RCLs) residing in close proximity to corneal nerves, suggesting the possibility of neuro-immune crosstalk in the cornea. However, current knowledge is limited on possible direct regulation of RCLs through corneal nerves, or the influence of RCLs on corneal nerve function. The third set of experiments will characterize the cell populations and molecular mechanisms involved in neuroimmune crosstalk resulting in peripheral nerve sensitization in the cornea. Corneal single cell mRNA transcript signatures associated in murine corneal pain models will be used to identify transcriptional changes that underly nociceptor sensitization. Crossing these immune cell transcripts with transcript profiles of corneal afferents will provide evidence for ligand-receptor pairs. In vitro studies will confirm the ability of the identified modulators to sensitize TG neurons, and the functional significance will be assessed using behavior and ex vivo electrophysiology. Employing a multidisciplinary approach, these experiments will provide a comprehensive analysis of cellular and molecular mechanisms of nociceptive and chronic corneal pain, leading to the identification novel pathways and treatments.