Division of Dry-Eye and Ocular GVHD, Department of Ophthalmology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany.
Division of Dry-Eye and Ocular GVHD, Department of Ophthalmology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany; ImmunEyez LLC, Irvine, CA, USA.
Ocul Surf. 2022 Jan;23:131-139. doi: 10.1016/j.jtos.2021.12.008. Epub 2021 Dec 16.
Dry eye disease (DED) is a multifactorial disease, with limitations regarding efficacy and tolerability of applied substances. Among several candidates, the endocannabinoid system with its receptors (CB1R and CB2R) were reported to modulate inflammation, wound healing and pain, which are also core DED pathomechanisms. This study is to investigate the therapeutic responses of Δ-9 tetrahydrocannabinol (a non-selective agonist) and two selective antagonists, SR141716A (CB1R antagonist) and SR144528 (CB2R antagonist), as a topical application using a DED mouse model.
Experimental DED was induced in naïve C57BL/6 mice. Expression of CBR at the ocular surface of naïve and DED mice was determined by qPCR and in-situ hybridization. Either THC or CBR antagonists were compounded in an aqueous solution and dosed during the induction of DED. Tear production, cornea sensitivity, and cornea fluorescence staining were tested. At the end of each experiment, corneas were stained with β3-tubulin for analysis of corneal nerve morphology. Conjunctiva was analyzed for CD4 and CD8 infiltration.
CB1R and CB2R are present at the ocular surface, and desiccating stress increased CBR expressions (p < 0.05). After 10 days of DED induction, treated groups demonstrated a reduced CBR expression in the cornea, which was concurrent with improvements in the DED phenotype including fluorescence staining & inflammation. Applying THC protected corneal nerve morphology, thus maintained corneal sensitivity and reduced CD4 T-cell infiltration. The CB1R antagonist maintained cornea sensitivity without changing nerve morphology.
Endocannabinoid receptor modulation presents a potential multi-functional therapeutic approach for DED.
干眼症（DED）是一种多因素疾病，应用物质的疗效和耐受性存在局限性。在几种候选药物中，内源性大麻素系统及其受体（CB1R 和 CB2R）被报道可调节炎症、伤口愈合和疼痛，这些也是 DED 发病机制的核心。本研究旨在通过 DED 小鼠模型研究 Δ-9 四氢大麻酚（非选择性激动剂）和两种选择性拮抗剂，即 SR141716A（CB1R 拮抗剂）和 SR144528（CB2R 拮抗剂）作为局部应用的治疗反应。
在未处理的 C57BL/6 小鼠中诱导实验性 DED。通过 qPCR 和原位杂交确定未处理和 DED 小鼠眼表 CBR 的表达。将 THC 或 CBR 拮抗剂复合在水溶液中，并在 DED 诱导期间给药。测试泪液产生、角膜敏感性和角膜荧光染色。在每个实验结束时，用 β3-微管蛋白对角膜神经形态进行染色分析。分析结膜中 CD4 和 CD8 的浸润。
CB1R 和 CB2R 存在于眼表面，干燥应激增加了 CBR 的表达（p<0.05）。在 DED 诱导 10 天后，治疗组在角膜中显示出降低的 CBR 表达，这与 DED 表型的改善同时发生，包括荧光染色和炎症。应用 THC 保护角膜神经形态，从而维持角膜敏感性并减少 CD4 T 细胞浸润。CB1R 拮抗剂维持角膜敏感性而不改变神经形态。
内源性大麻素受体调节为 DED 提供了一种潜在的多功能治疗方法。
