Figure 1.

Mechanisms of fibrosis. Aging, injury, infection, and inflammation can promote epithelial cells to myofibroblast transition, regulate ECM formation and remodelling, and ultimately lead to tissue fibrosis or efficient repair. Activated epithelial cells secrete many inflammatory mediators, such as TGF-β1 and interleukin-1β, which recruit immune cells such as mast cells, B cells, T cells, and macrophages. These invasive immune cells release TGF-β, interleukin-1β, interleukin-6, interleukin-13, and other mediators, enhancing profibrotic reactions.