ABSTRACT
BACKGROUND: To investigate whether methotrexate treatment may affect the susceptibility to infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). METHODS: Clinical assessment of symptoms, SARS-CoV-2 RNA, and anti-SARS-CoV-2 IgG in an initial case series of four families and confirmatory case series of seven families, within which one family member developed coronavirus disease 19 (COVID-19) and exposed another family member receiving methotrexate treatment; experimental part with methotrexate treatment of mice and organoids followed by the assessment of mRNA and protein expression of the SARS-CoV-2 receptor angiotensin-converting enzyme (ACE)-2. RESULTS: In the initial case series, three of four women on a joint ski trip developed COVID-19, while the fourth woman, under treatment with methotrexate, remained virus-free. Two of the three diseased women infected their husbands, while the third husband treated with methotrexate remained virus-free. In addition, 7 other families were identified in a follow-up case series, in which one member developed COVID-19, while the other, receiving methotrexate, remained healthy. Experimentally, when mice were treated with methotrexate, ACE2 expression significantly decreased in the lung, in the intestinal epithelium, and in intestinal organoids. CONCLUSION: These clinical and experimental data indicate that methotrexate has certain protective effects on SARS-CoV-2 infection via downregulating ACE2.