Effect of IFN-gamma and dexamethasone on TGF-beta1-induced human fetal lung fibroblast-myofibroblast differentiation.
OBJECTIVE
To study whether Smads signaling pathway was involved in human fetal lung fibroblast-myofibroblast differentiation induced by transforming growth factor (TGF)-beta1 and the role of interferon (IFN)-gamma, dexamethasone (DEX) in the fibroblast-myofibroblast differentiation.


METHODS
Alpha-smooth muscle actin (alpha-SMA), Smad2/3, and Smad7 protein were assessed by Western blot. Collagen protein was analyzed by measuring hydroxyproline. Alpha-SMA and collagen III mRNA were assessed by RT-PCR. Myofibroblasts morphology and Smad2/3 nuclear translocation were assessed by immunohistochemistry. The overexpression of Smad7, a negative mediator of Smads signaling pathway, was acquired by transfection of Smad7 vector.


RESULTS
During fibroblast-myofibroblast differentiation induced by TGF-beta1, IFN-gamma 200 microg/L markedly blocked TGF-beta1-induced alpha-SMA protein expression (P<0.01), collagen protein (P<0.01) and mRNA (P<0.05) expression, and myofibroblasts morphological transformation, but DEX 10 micromol/L augmented TGF-beta1-induced alpha-SMA expression (P<0.01). For myofibroblasts, both IFN-gamma 200 microg/L and DEX 10 micromol/L did not inhibit alpha-SMA expression (P>0.05) and collagen protein (P>0.05) and mRNA expression (P>0.05) and did not change myofibroblasts morphology. Transient transfection of Smad7 vector resulted in significant inhibition of TGF-beta1-induced alpha-SMA expression (P<0.01). IFN-gamma 200 microg/L did not block TGF-beta1-stimulated Smad2/3 phosphorylation and their nuclear translocation.


CONCLUSIONS
TGF-beta1 induced fibroblast-myofibroblast differentiation in a Smad proteins-dependent manner. IFN-gamma could block this process but it was not mediated by interrupting smad2/3 phosphorylation and their nuclear translocation and DEX played a synergism with TGF-beta1. Differentiated myofibroblasts, however, were resistant to both IFN-gamma and DEX.
Gu
Li
L
Department of Pulmonary Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China.
Zhu
Yuan-jue
YJ
Guo
Zi-jian
ZJ
Xu
Xing-xiang
XX
Xu
Wen-bing
WB
D000199:Actins / Q000378:metabolism; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D003094:Collagen / Q000096:biosynthesis / Q000235:genetics; D003907:Dexamethasone / Q000494:pharmacology*; D005347:Fibroblasts / Q000166:cytology*; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D008168:Lung / Q000166:cytology*; D010766:Phosphorylation; D021381:Protein Transport; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D015398:Signal Transduction; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D053773:Transforming Growth Factor beta1
D000199:Actins; D000893:Anti-Inflammatory Agents; D012333:RNA, Messenger; C508960:TGFB1 protein, human; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D003907:Dexamethasone; D007371:Interferon-gamma; D003094:Collagen