Background. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes a novel infectious respiratory disease called COVID-19, which is threatening public health worldwide. SARS-CoV-2 spike proteins connect to the angiotensin converting enzyme 2 (ACE2) receptor through the receptor binding domain and are then activated by the transmembrane protease serine subtype 2 (TMPRSS2). The ACE2 receptor is highly expressed in human nasal epithelial cells. Nasal ciliated cells are primary targets for SARS-CoV-2 replication. However, the effect of SARS-CoV-2 on the upper respiratory tract remains unknown, thus leading to the purpose of our study. We investigate the effects of SARS-CoV-2 on cytokines and mucin expression in human nasal epithelial cells. Methods. We investigated the effects of the SARS-CoV-2 spike protein receptor binding domain (RBD) on cytokines (IL-1β, IL-6, and IL-8) and MUC5AC/5B expression via real-time PCR, ELISA, periodic acid-Schiff (PAS) staining, and immunofluorescence staining in cultured human nasal epithelial cells. Results. The mRNA expression and protein production of cytokines (IL-1β, IL-6, and IL-8) and MUC5AC/5B were increased by SARS-CoV-2 spike protein RBD. ACE2 receptor inhibitor suppressed the expression of cytokines (IL-1β, IL-6, and IL-8) and MUC5AC/5B induced by SARS-CoV-2 spike protein RBD. Conclusions. SARS-CoV-2 induced cytokines (IL-1β, IL-6, and IL-8) and MUC5AC/5B expression through the ACE 2 receptor in human nasal epithelial cells. Therefore, ACE2 receptor inhibitors can be an effective therapeutic option for SARS-CoV-2 infection.

Post-acute coronavirus disease (COVID-19) syndrome is defined as persistent symptoms or delayed complications after COVID-19. Several cases of cranial nerve invasion related to COVID-19 have been reported. However, to our knowledge, no cases of solitary unilateral hypoglossal nerve paralysis after mild COVID-19 without intubation have been reported to date. Herein, we report the case of a 64-year-old man with unilateral hypoglossal nerve palsy as a complication of COVID-19. He complained of dysarthria and tongue discomfort 2 weeks after COVID-19 onset. Brain and neck computed tomography, magnetic resonance imaging, ultrasonography, and blood tests ruled out other possible causes. The patient’s nerve palsy was rapidly diagnosed and improved with early rehabilitation. Understanding of the pathology of COVID-19 is still limited. Physicians should focus on patients’ symptoms and their relationship to COVID-19, and investigate complications immediately. This case highlights the importance of early detection and rehabilitation of post-acute COVID-19 syndrome.