Figure 5.

The participation of orbital fibroblasts in orbital tissue remodeling. Orbital fibroblasts express TSHR, IGF-1R, and CD40. Infiltrated immune cells, antibodies, secreted cytokines, chemokines, growth factors, and also CD40-CD154 interactions activate orbital fibroblasts. Inflammatory mediators (Il-1β and IL-6) that enhance adipogenesis activate Thy1− orbital fibroblasts to differentiate into adipocytes. And Thy1+ orbital fibroblasts (with CD90 expression), activated by TGF-β, differentiate into myofibroblasts. Proliferative activity of orbital fibroblasts, their differentiation, and capacity to synthesize extracellular matrix contribute to orbital tissue expansion, remodeling, and fibrosis.