Fig. 1

Extracellular miRNAs or mlRNAs activate macrophage intracellular TLR7/8 signaling and elicit inflammatory responses. Extracellular miRNA or mlRNAs in microvesicles (MV) or MV-free condition are first internalized into the recipient macrophages, and then subsequently transported to endosomes, in which the miRNAs or mlRNAs that contain GU-rich sequence, such as miR-21 and miR-29a, bind to endosomally localized TLR7/8. After the ligation of TLR7/8 by miRNA or mlRNAs, the adaptor molecule MyD88 is recruited and drives the production of proinflammatory cytokines such as TNF-α and IL-6