ACE2 and rheumatoid arthritis: RA is a high-risk factor for SARS-CoV-2 infection, and COVID-19 and RA share a common mechanistic pathway of immunopathogenesis mediated through aberrant angiotensin-converting enzyme (ACE)/ACE2 activity and a common mechanistic pathway of immunopathogenesis driven by the activity of macrophage clusters [39, 40].