Epipharyngeal Abrasive Therapy Down-regulates the Expression of SARS-CoV-2 Entry Factors ACE2 and TMPRSS2

Abstract

Background: The epipharynx, with its high expression of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) entry factors angiotensin-converting enzyme 2 (ACE2) and transmembrane protease, serine 2 (TMPRSS2), is a primary target for SARS-CoV-2 replication in the early stage of Coronavirus Disease 19 (COVID-19). Epipharyngeal abrasive therapy (EAT) is a treatment for epipharyngitis in Japan which involves applying zinc chloride to the epipharyngeal mucosa. In this study, we evaluated the expression patterns of ACE2 and TMPRSS2 in tissue samples from patients before and after EAT.

Patients and methods: The study subjects were seven patients that had not been treated with EAT and 11 patients that had. For immunohistochemical assessment of the epipharyngeal mucosa, the staining intensity of ACE2 and TMPRSS2 was described as an immunohistochemical score (IHC score).

Results: The IHC scores for ACE2 and TEMPRSS2 in the EAT-treated group were 3.40-fold and 1.81-fold lower, respectively, than those in the non-treated group (p=0.0208 and p=0.0244, respectively).

Conclusion: EAT down-regulates the expression of SARS-CoV-2 entry factors ACE2 and TMPRSS2. Thus, EAT has potential as a novel COVID-19 preventative method.

Keywords: ACE2; EAT; Epipharyngeal abrasive therapy; SARS-CoV-2; TMPRSS2.

Figure 1. Epipharyngeal abrasive therapy (EAT). A: Cotton swabs for EAT. B: EAT procedure. Left panel shows the method of endoscopic EAT. Right panel shows the method of transoral EAT. C: Transnasal endoscopic photographs of the epipharynx in a patient. Left panel shows transnasal endoscopic photographs of the epipharynx pre-EAT treatment. Right panel shows transnasal endoscopic photographs of the epipharynx following 3 months of treatment with EAT. The arrowhead indicates the temporal whitening phenomenon. D: Hematoxylin and eosin (HE) staining of the epipharynx mucosa of a patient. Upper panel shows HE staining of the epipharynx pre-EAT treatment. Lower panel shows HE staining of the epipharynx following 3 months of EAT treatment. The arrowhead indicates cilia on the surface of epithelial cells.

Figure 2. mRNA and protein expression patterns of angiotensinconverting enzyme 2 (ACE2) and transmembrane protease, serine 2 (TMPRSS2) in patient tissue samples without and with epipharyngeal abrasive therapy (EAT). A: ACE2 and TMPRSS2 expression in the epipharynx of the EAT-treated and non-treated groups. The upper and middle panels show the protein expression patterns. The lower panels show the mRNA expression patterns. Arrowheads indicate the mRNA expression of ACE2. B: Immunohistochemical (IHC) scores for ACE2 and TMPRSS2 expression on the epipharyngeal mucosa of the EATtreated (n=11) and non-treated groups (n=7). *Significantly different at p<0.05.