The proposed model of Treg-dependent thrombolysis by monocytes. (A) The formation of a thrombus in the blood vessel attracts monocytes and Tregs. (B) The Tregs express SPARC in an IL-18, IL-33, and TGF-β–dependent manner. SPARC stimulates the release of MMPs from the monocytes. (C) The MMPs degrade the thrombus and thus help with its removal.