Our aim was to evaluate a potential role for the lacrimal drainage system (LDS) as a portal of entry and conduit for SARS-CoV-2 in human infection. We also investigate the mucosal surface area. The relatively long tear contact time in a closed system raises the possibility that this pathway may contribute to the initiation of systemic infection. We looked for expression of ACE2, the main receptor for SARS-CoV-2, as well as cofactors such as TMPRSS2 and other enzymes such as cathepsinB, CD147, elastase1, furin, neuropilin1, neuropilin2, TMPRSS11D and trypsin which also play a role in SARS-CoV-2 infection, in this system. Human tissue samples of the draining tear ducts from body donors were analyzed by RT-PCR, Western blot and immunohistochemistry. It is not known whether the respective body donors were Sars-Cov-2 positive at any time; they were negative when they entered the institute. Besides, the draining LDS of body donors were measured to determine the mucosal surface in the lacrimal system. The expression of the main receptor studied, ACE2, cofactors such as TMPRSS2 and other enzymes such as cathepsinB, CD147, elastase1, furin, neuropilin1, neuropilin2, TMPRSS11D and trypsin were all detected at the gene and protein level. The average mucosal surface area of the lacrimal sac and nasolacrimal duct was calculated to be 110 mm. The results show the presence of all analyzed receptors in the efferent LDS. With an average tear passage time of 3 min and a relatively large mucosal surface area, the LDS could therefore be considered as a portal of entry and conduit for SARS-CoV-2. In addition, it represents a surface that should be taken into consideration in the administration of topically applied medication to the ocular surface.

中文翻译：

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检测 SARS-CoV-2 结合受体和其他靶标以及人类泪道引流系统的粘膜表面积


我们的目的是评估泪道引流系统 (LDS) 作为人类感染 SARS-CoV-2 的入口和管道的潜在作用。我们还研究了粘膜表面积。封闭系统中相对较长的泪液接触时间增加了该途径可能导致全身感染启动的可能性。我们寻找 ACE2（SARS-CoV-2 的主要受体）以及辅助因子（如 TMPRSS2）和其他酶（如组织蛋白酶 B、CD147、弹性蛋白酶1、弗林蛋白酶、神经毡蛋白 1、神经毡蛋白 2、TMPRSS11D 和胰蛋白酶）的表达，这些酶也在在这个系统中，SARS-CoV-2 感染。通过 RT-PCR、蛋白质印迹和免疫组织化学分析来自捐献者的泪管引流的人体组织样本。目前尚不清楚各自的遗体捐献者是否在任何时候都呈 Sars-Cov-2 阳性；当他们进入该研究所时，他们的检测结果呈阴性。此外，还测量了遗体捐献者的引流LDS以确定泪道系统的粘膜表面。研究的主要受体ACE2、辅助因子如TMPRSS2以及其他酶如组织蛋白酶B、CD147、弹性蛋白酶1、弗林蛋白酶、神经毡蛋白1、神经毡蛋白2、TMPRSS11D和胰蛋白酶的表达均在基因和蛋白水平上进行检测。计算泪囊和鼻泪管的平均粘膜表面积为110mm2。结果显示传出 LDS 中存在所有分析的受体。 LDS 的平均泪液通过时间为 3 分钟且粘膜表面积相对较大，因此可以被视为 SARS-CoV-2 的进入门户和导管。此外，它代表了在眼表面局部施用药物时应考虑的表面。