Significant expression of FURIN and ACE2 on oral epithelial cells may facilitate the efficiency of 2019-nCov entry

Bing-peng Lin; Mei Zhong; Hong-bin Gao; Kai-bin Wu; Ming-xiao Liu; Chang Liu; Xin-hong Wang; Jian-ming Chen; Learn-han Lee; Cui-ling Qi; Lin-hu Ge; Li-jing Wang

Many studies have shown that ACE2 receptor was highly expressed in respiratory epithelium, kidney, cardiovascular system and testis [24] . Some scholars also found that ACE2 was expressed in oral tissues with bulk RNA sequencing data, which could not accurately reflect the expression of ACE2 on the single cell level [21, 25] . Chen et al. benefited from the single-cell sequencing data to further proved the expression of ACE2 receptor in tongue, buccal mucosa and gingiva [11] . However, these studies were based on public databases and were not analyzed together, and further validation of protein levels was lacking. In the current study, we firstly characterized the ACE2 protein expression profiles in five different oral tissues through immunohistochemical staining experiment. Results indicated that ACE2 was mainly present in epithelial cells in all included tissues, especially in buccal mucosa, lip and tongue. Previous study discovered the similar result [21] . Overall, these results demonstrated that, compared with other oral sites, buccal mucosa, lip and tongue might be more susceptible to SARS-CoV-2.