Profiling ACE2 and TMPRSS2 expression in sinonasal mucosa

Abstract

Rhinologists may be one of the highest-risk subspecialties in otolaryngology for exposure to SARS-CoV-2 as the sinonasal passage seems to be a reservoir for the virus. Previous data indicate nasal epithelial cells express the primary receptor for SARS-CoV-2, Angiotensin-Converting Enzyme-2 (ACE2). However, no data exist profiling the regional expression of ACE2 or the expression of transmembrane serine protease 2 (TMPRSS2), an additional protease necessary for SARS-CoV-2 viral entry, within the sinonasal cavity. We sought to assess for anatomic expression of ACE2 and TMPRSS2 throughout the nasal cavity and paranasal sinuses. We hypothesize that ACE2 and TMPRSS2 are expressed throughout the nasal cavity and paranasal sinuses. To test this hypothesis, we sampled various regions of the sinonasal cavity from patients undergoing rhinology procedures and used immunohistochemical staining to profile ACE2, compare ACE2 expression between regions, and compare ACE2 expression between patients and patient characteristics. We found ACE2 and TMPRSS2 are present throughout the sinonasal cavity without a regional pattern among anatomic regions in our patients. We found no statistically significant correlation in ACE2 expression with patient characteristics such as age, sex, or BMI. We also did not find a statistically significant correlation between ACE2 and TMPRSS2 quantitative expression. ACE2 expression trended higher in males compared to females for six out of seven regions excluding the nasal floor. In conclusion, ACE2 and TMPRSS2 are expressed ubiquitously throughout the sinonasal cavity. ACE2 expression may be higher in the sinonasal cavity in males compared to females. These data implicate that SARS-CoV-2 is unlikely to discriminate between anatomic regions as a point of entry and that anatomic regions likely are similar in viral load. Thus, all rhinology and skull base surgeries, independent of encounter of the anatomic region in the sinonasal cavity, predicate screening for SARS-CoV-2, and necessary personal protective equipment.