Flashlamp Pulsed-dye Laser Suppressed TGF-beta1 Expression and Proliferation in Cultured Keloid Fibroblasts is Mediated by MAPK Pathway

Background And Objectives: Our previous clinical study indicated that transforming growth factor-beta1 (TGF-beta1) and mitogen-activated protein kinases (MAPK) are both involved in keloid regression following flashlamp pulsed-dye laser (PDL). To further characterize of this involvement, this work examined whether PDL suppression of TGF-beta1 expression was mediated through MAPK pathway in cultured keloid fibroblasts (KF).

Study Design/materials And Methods: Primary culture of KF harvested from keloid patients received various dosages of PDL treatment in 585-nm wavelength. TGF-beta1 expressions in KF following various dosages of PDL were assessed. Additionally, MAPK pathway activities were studied using the PD98059 (an ERK inhibitor), SB203580 (a p38 kinase inhibitor), and SP600125 (a JNK inhibitor), to determine the role in keloid following PDL treatment. Activator protein-1 (AP-1), a transcription factor of TGF-beta, was analyzed by electrophoretic mobility shift assay (EMSA). Phosphorylated c-Jun, one of the components of AP-1, was also detected.

Results: The observation results demonstrated that optimal dosages of PDL significantly suppressed KF proliferation and TGF-beta1 expression. EMSA study identified PDL downregulation of super-shift of AP-1. Three subtypes of MAPK cascades were augmented between 30 minutes and 4 hours following PDL treatment, particularly phosphorylation of ERK1/2 and p38. Pre-treatment with PD98059, SB203580, but not SP600125, markedly inhibited the downregulating effects of TGF-beta1 and phosphorylated c-Jun expression following PDL treatment.

Conclusion: PDL induced keloid regression is mediated by triggering MAPK cascades and blockade of AP-1 transcription and TGF-beta expression. Modulation of TGF-beta and MAPK interaction in keloids may provide specific targets for therapeutic intervention.