Fig. 2.

Potential interactions between renin angiotensin system, bradykinin system and fibrinolysis in severe COVID-19. Arrows demonstrate interactions. Italic script depicts the function of the molecule/enzyme in a normal state. The color of the arrows demonstrate how SARS-CoV-2 may influence their function. Green solid arrow means that the process (in italics) is enhanced in COVID-19, while red dashed arrow means that the process (in italics) is suppressed in COVID-19. As an example, in COVID-19 decreased ACE2 increases AngII, which increases aldosterone, which augments ACE expression, causing increased breakdown of bradykinin, thereby preventing the normal bradykinin-mediated increase in tPA). ACE = angiotensin converting enzyme, ACE2 = angiotensin converting enzyme 2, AngI = angiotensin I, AngII = angiotensin II, Ang1-7 = angiotensin 1–7, AT1 = angiotensin II receptor type 1, MasR = Mas receptor, PAI-1 = plasminogen activator inhibitor-1, SARS-CoV-2 = severe acute respiratory syndrome coronavirus 2, tPA = tissue plasminogen activator. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)