Increased C3–EV plasma concentrations have been described for several pathological conditions, such as multiple sclerosis, obesity, and rheumatoid arthritis.27, 28, 29 Moreover, in a cell model of pulmonary hypertension, C3–EVs were shown to drive a proinflammatory and metabolic reprogramming of macrophages.30 Here, C3 is linked to rheumatoid arthritis.