Opposite effects of TGF-beta1 and IFN-gamma on transdifferentiation of myofibroblast in human gingival cell cultures.
OBJECTIVE
Previously, we have shown that myofibroblasts, the main cell type associated with interstitial fibrosis, may be implicated with the gingival overgrowth observed in hereditary gingival fibromatosis (HGF) patients. The goal of this study was to determine whether transforming growth factor-beta1 (TGF-beta1) stimulates myofibroblast generation in gingival fibroblast cultures. Moreover, we analysed how interferon-gamma (IFN-gamma) interferes in this process.


METHODS
Fibroblast cultures from normal gingiva and myofibroblast cells from HGF were included in this study. To determine the effects of TGF-beta1 and IFN-gamma stimulation in these cells, the expression of the specific myofibroblast marker smooth muscle isoform of alpha-actin (alpha-SMA) was examined by semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), Western blot and immunofluorescence. Enzyme-linked immunosorbent assay (ELISA) for type I collagen was performed to measure the myofibroblast activity.


RESULTS
Our results demonstrated that TGF-beta1 promotes a dose- and time-dependent increase in the expression of alpha-SMA, whereas IFN-gamma blocks it and markedly prevents the fibroblast-myofibroblast switch induced by TGF-beta1 on normal gingiva cultures. IFN-gamma altered HGF myofibroblasts metabolism with a decrease of both alpha-SMA and type I collagen expression. Additionally, IFN-gamma treatment stimulated SMAD7 expression and inhibited connective tissue growth factor, which has been considered a key molecule to promote the transdifferentiation of myofibroblasts via TGF-beta1 activation.


CONCLUSIONS
These findings demonstrate that TGF-beta1 induces gingival fibroblast-myofibroblast transdifferentiation, whereas IFN-gamma blocks this process. More importantly, this study suggests that IFN-gamma may be clinically effective in attenuating excessive accumulation of extracellular matrix produced by myofibroblasts in HGF.
Sobral
Lays M
LM
Department of Oral Diagnosis, University of Campinas Dental School, Piracicaba, São Paulo, Brazil.
Montan
Patrick F
PF
Martelli-Junior
Hercílio
H
Graner
Edgard
E
Coletta
Ricardo D
RD
D000199:Actins / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D024042:Collagen Type I / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D055513:Connective Tissue Growth Factor; D015536:Down-Regulation; D005347:Fibroblasts; D005351:Fibromatosis, Gingival / Q000378:metabolism / Q000473:pathology*; D005881:Gingiva / Q000166:cytology*; D006801:Humans; D017874:Immediate-Early Proteins / Q000096:biosynthesis; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis; D007371:Interferon-gamma / Q000494:pharmacology / Q000502:physiology*; D009130:Muscle, Smooth / Q000166:cytology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051906:Smad7 Protein / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000037:antagonists & inhibitors / Q000502:physiology*; D015854:Up-Regulation
D000199:Actins; C526317:CCN2 protein, human; D024042:Collagen Type I; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; C497806:SMAD7 protein, human; D051906:Smad7 Protein; D053773:Transforming Growth Factor beta1; D055513:Connective Tissue Growth Factor; D007371:Interferon-gamma