Figure 7. Schematic of injury sensing by MyD88 in pericytes.

Pericytes sense tissue injury through TLR2 and TLR4. Both MyD88 and IRAK4 are important in transducing this signal and activation of inflammatory responses. Injurious molecules also activate inflammasome and release of additional proinflammatory cytokines including IL-1β. Pericytes respond to IL-1β, and this generates an autocrine loop that amplifies the inflammatory response. In addition to inflammatory responses, activation of the TLR/MyD88/IRAK4 axis by tissue injury induces myofibroblast differentiation.