Protease Inhibitors: Candidate Drugs to Inhibit Severe Acute Respiratory Syndrome Coronavirus 2 Replication

Protease Inhibitors: Candidate Drugs to Inhibit Severe Acute Respiratory Syndrome Coronavirus 2 Replication

MUTSUO YAMAYA,^1,2,3 HIDEKAZU NISHIMURA,³ XUE DENG,^1,4 AKIKO KIKUCHI⁴ and RYOICHI NAGATOMI⁵

¹Department of Advanced Preventive Medicine for Infectious Disease, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
²Department of Respiratory Medicine, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
³Virus Research Center, Clinical Research Division, Sendai Medical Center, Sendai, Miyagi, Japan
⁴Department of Kampo and Integrative Medicine, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
⁵Laboratory of Health and Sports Science, Division of Biomedical Engineering for Health and Welfare, Tohoku University Graduate School of Biomedical Engineering, Sendai, Miyagi, Japan

The number of patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly increased, although the WHO declared a pandemic. However, drugs that function against SARS-CoV-2 have not been established. SARS-CoV-2 has been suggested to bind angiotensin-converting enzyme 2, the receptor of the SARS coronavirus. SARS coronavirus and coronavirus 229E, the cause of the common cold, replicate through cell-surface and endosomal pathways using a protease, the type II transmembrane protease. To examine the effects of protease inhibitors on the replication of coronavirus 229E, we pretreated primary cultures of human nasal epithelial (HNE) cells with camostat or nafamostat, each of which has been used for the treatment of pancreatitis and/or disseminated intravascular coagulation. HNE cells were then infected with coronavirus 229E, and viral titers in the airway surface liquid of the cells were examined. Pretreatment with camostat (0.1-10 μg/mL) or nafamostat (0.01-1 μg/ mL) reduced the titers of coronavirus 229E. Furthermore, a significant amount of type II transmembrane protease protein was detected in the airway surface liquid of HNE cells. Additionally, interferons have been reported to have antiviral effects against SARS coronavirus. The additive effects of interferons on the inhibitory effects of other candidate drugs to treat SARS-CoV-2 infection, such as lopinavir, ritonavir and favipiravir, have also been studied. These findings suggest that protease inhibitors of this type may inhibit coronavirus 229E replication in human airway epithelial cells at clinical concentrations. Protease inhibitors, interferons or the combination of these drugs may become candidate drugs to inhibit the replication of SARS-CoV-2.

Keywords —— camostat; coronavirus 229E; nafamostat; SARS-CoV-2; type II transmembrane protease

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Tohoku J. Exp. Med., 2020, 251, 27-30

Correspondence: Mutsuo Yamaya, M.D., Ph.D., Department of Respiratory Medicine, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan.

e-mail: myamaya@med.tohoku.ac.jp