Human T2R38 Bitter Taste Receptor Expression and COVID-19: From Immunity to Prognosis

Background: Bitter taste-sensing type 2 receptor (T2Rs or TAS2Rs) found on ciliated epithelial cells and solitary chemosensory cells have a role in respiratory tract immunity. T2Rs have shown protection against SARS-CoV-2 by enhancing the innate immune response. The purpose of this review is to outline the current sphere of knowledge regarding this association. Methods: A narrative review of the literature was done by searching (T2R38 OR bitter taste receptor) AND (COVID-19 OR SARS-CoV-2) keywords in PubMed and google scholar. Results: T2R38, an isoform of T2Rs encoded by the TAS2R38 gene, may have a potential association between phenotypic expression of T2R38 and prognosis of COVID-19. Current studies suggest that due to different genotypes and widespread distributions of T2Rs within the respiratory tract and their role in innate immunity, treatment protocols for COVID-19 and other respiratory diseases may change accordingly. Based on the phenotypic expression of T2R38, it varies in innate immunity and host response to respiratory infection, systemic symptoms and hospitalization. Conclusion: This review reveals that patients' innate immune response to SARS-COV-2 could be influenced by T2R38 receptor allelic variations.