Figure 5.

Proposed Schematic of OPN Induction and Profibrotic Activity in SSc

Tissue macrophages activated by IC trigger inflammation and OPN secretion. Infiltrating monocytes are activated by IC and differentiate into macrophages, aided by autocrine and paracrine MCSF, amplified by IL-6, and further contribute to OPN production. OPN facilitates tissue remodeling, in part by sensitizing and mobilizing fibroblasts toward other fibrogenic growth factors, and thereby contribute to fibrosis progression.