title: Green tea extract and (-)-epigallocatechin-3-gallate inhibit mast cell-stimulated type I collagen expression in keloid fibroblasts via blocking PI-3K/AkT signaling pathways.
abstract: Keloid, a chronic fibro-proliferative disease, exhibits distinctive histological features characterized by an abundant extracellular matrix stroma, a local infiltration of inflammatory cells including mast cells (MCs), and a milieu of enriched cytokines. Previous studies have demonstrated that co-culture with MCs stimulate type I collagen synthesis in fibroblasts, but the signaling mechanisms remain largely unknown. In this study, we investigated the signaling pathways involved in MC-stimulated type I collagen synthesis and the effects of green tea extract (GTE) and its major catechin, (-)-epigallocatechin-3-gallate (EGCG), on collagen homeostasis in keloid fibroblasts. Our results showed that MCs significantly stimulated type I collagen expression in keloid fibroblasts, and the upregulation of type I collagen was significantly attenuated by blockade of phosphatidylinositol-3-kinase (PI-3K), mammalian target of rapamycin (mTOR), and p38 MAPK signaling pathways, but not by blockade of ERK1/2 pathway. Furthermore, GTE and EGCG dramatically inhibited type I collagen production possibly by interfering with the PI-3K/Akt/mTOR signaling pathway. Our findings suggest that interaction between MCs and keloid fibroblasts may contribute to excessive collagen accumulation in keloids and imply a therapeutic potential of green tea for the intervention and prevention of keloids and other fibrotic diseases.
authors.affiliation: Center for Craniofacial Molecular Biology, University of Southern California, School of Dentistry, Los Angeles, California 90033, USA.
authors.forename: Qunzhou
authors.initials: Q
authors.lastname: Zhang
authors.forename: A Paul
authors.initials: AP
authors.lastname: Kelly
authors.forename: Lina
authors.initials: L
authors.lastname: Wang
authors.forename: Samuel W
authors.initials: SW
authors.lastname: French
authors.forename: Xudong
authors.initials: X
authors.lastname: Tang
authors.forename: Hai S
authors.initials: HS
authors.lastname: Duong
authors.forename: Diana V
authors.initials: DV
authors.lastname: Messadi
authors.forename: Anh D
authors.initials: AD
authors.lastname: Le
mesh_terms: D028241:Camellia sinensis / Q000737:chemistry*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002478:Cells, Cultured; D018920:Coculture Techniques; D024042:Collagen Type I / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism*; D006801:Humans; D007627:Keloid / Q000378:metabolism* / Q000473:pathology; D008407:Mast Cells / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010936:Plant Extracts / Q000494:pharmacology*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D024042:Collagen Type I; D010936:Plant Extracts; D002392:Catechin; C045651:epigallocatechin gallate; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt