Myofibroblasts are the major cellular source of collagen, and their accumulation – via differentiation from fibroblasts and resistance to apoptosis – is a hallmark of tissue fibrosis. Clearance of myofibroblasts by de-differentiation and restoration of apoptosis sensitivity has the potential to reverse fibrosis. Prostaglandin E2 (PGE2) and mitogens such as FGF2 have each been shown to de-differentiate myofibroblasts, but the resultant cellular phenotypes have neither been comprehensively characterized nor compared. Here we show that PGE2 elicited de-differentiation of human lung myofibroblasts via cAMP/PKA while FGF2 utilized MEK/ERK. The two mediators yielded transitional cells with distinct transcriptomes, with FGF2 promoting but PGE2 inhibiting proliferation and survival. The gene expression pattern in fibroblasts isolated from the lungs of mice undergoing resolution of experimental fibrosis resembled that of myofibroblasts treated with PGE2 in vitro. We conclude that myofibroblast de-differentiation can proceed via distinct programs exemplified by treatment with PGE2 and FGF2, with that occurring in vivo most closely resembling the former.
Sean M. Fortier, Loka R. Penke, Dana M. King, Tho X. Pham, Giovanni Ligresti, Marc Peters-Golden