COVID-19 in patients with chronic rhinosinusitis with polyps. Are they at risk?
Reviewed by Hassan Mohammed

COVID-19 entry factors are highly present in nasal epithelial cells. These factors include ACE2 and TMPRSS2. Their presence in patients with chronic rhinosinusitis with nasal polyps (CRSwNP) was not investigated before. Authors investigated expression of ACE2 and TMPRSS2 in two subgroups of CRSwNP patents including eosinophilic CRSwNP (ECRSwNP) and non-eosinophilic CRSwNP (nonECRSwNP). They also investigated the regulation of these entry factors by steroids and cytokines in addition to the correlation between their expression and the inflammatory indices. Authors showed that there were noticeable differences between the two COVID-19 entry factors. ACE2 expression was significantly higher in nonECRSwNP; it was positively correlated with IFN-gamma and negatively correlated with presence of eosinophils. IFN-gamma was reported to up-regulate ACE2 while steroids were shown to down-regulate it. ACE2 expression in ECRSwNP patients and TMPRSS were not affected with steroids. Authors concluded that ACE2 expression is increased in nasal tissues of nonECRSwNP patients. The implications of this study are not clear. The increase of ACE2 expression in nonECRwNP patients could be balanced by the reported decrease in TMPRSS expression in this patient group. However, it could be concluded that ECRSwNP patients have less expressed COVID-19 entry factors.

Distinct expression of SARS-CoV-2 receptor ACE2 correlates with endotypes of chronic rhinosinusitis with nasal polyps.
Wang M, Bu X, Fang G, et al.
ALLERGY
2021;76(3):789-803.