Bone morphogenetic protein (BMP)-4 and BMP-7 regulate differentially transforming growth factor (TGF)-beta1 in normal human lung fibroblasts (NHLF).
BACKGROUND
Airway remodelling is thought to be under the control of a complex group of molecules belonging to the transforming growth factor (TGF)-superfamily. The bone morphogenetic proteins (BMPs) belong to this family and have been shown to regulate fibrosis in kidney and liver diseases. However, the role of BMPs in lung remodelling remains unclear. BMPs may regulate tissue remodelling in asthma by controlling TGF-beta-induced profibrotic functions in lung fibroblasts.


METHODS
Cell cultures were exposed to TGF-beta1 alone or in the presence of BMP-4 or BMP-7; control cultures were exposed to medium only. Cell proliferation was assessed by quantification of the incorporation of [3H]-thymidine. The expression of the mRNA encoding collagen type I and IV, tenascin C and fibronectin in normal human lung fibroblasts (NHLF) was determined by real-time quantitative PCR and the main results were confirmed by ELISA. Cell differentiation was determined by the analysis of the expression of alpha-smooth muscle actin (alpha-SMA) by western blot and immunohistochemistry. The effect on matrix metalloproteinase (MMP) activity was assessed by zymography.


RESULTS
We have demonstrated TGF-beta1 induced upregulation of mRNAs encoding the extracellular matrix proteins, tenascin C, fibronectin and collagen type I and IV when compared to unstimulated NHLF, and confirmed these results at the protein level. BMP-4, but not BMP-7, reduced TGF-beta1-induced extracellular matrix protein production. TGF-beta1 induced an increase in the activity of the pro-form of MMP-2 which was inhibited by BMP-7 but not BMP-4. Both BMP-4 and BMP-7 downregulated TGF-beta1-induced MMP-13 release compared to untreated and TGF-beta1-treated cells. TGF-beta1 also induced a myofibroblast-like transformation which was partially inhibited by BMP-7 but not BMP-4.


CONCLUSIONS
Our study suggests that some regulatory properties of BMP-7 may be tissue or cell type specific and unveil a potential regulatory role for BMP-4 in the regulation of lung fibroblast function.
Pegorier
Sophie
S
Leukocyte Biology Section, Faculty of Medicine, MRC and Asthma UK Centre in Allergic Mechanisms of Asthma, National Heart and Lung Institute, Imperial College London, London, UK.
Campbell
Gaynor A
GA
Kay
A Barry
AB
Lloyd
Clare M
CM
D000199:Actins / Q000378:metabolism; D056151:Airway Remodeling; D015153:Blotting, Western; D055415:Bone Morphogenetic Protein 4 / Q000378:metabolism*; D055419:Bone Morphogenetic Protein 7 / Q000378:metabolism*; D052004:Bone Morphogenetic Protein Receptors / Q000378:metabolism; D002454:Cell Differentiation; D049109:Cell Proliferation; D002470:Cell Survival; D002478:Cells, Cultured; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism; D024141:Collagen Type IV / Q000235:genetics / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005347:Fibroblasts / Q000378:metabolism*; D005353:Fibronectins / Q000235:genetics / Q000378:metabolism; D005355:Fibrosis; D006801:Humans; D007150:Immunohistochemistry; D008168:Lung / Q000378:metabolism*; D053509:Matrix Metalloproteinase 13 / Q000378:metabolism; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019063:Tenascin / Q000235:genetics / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000378:metabolism*; D015854:Up-Regulation
D000199:Actins; C525809:BMP4 protein, human; C525819:BMP7 protein, human; D055415:Bone Morphogenetic Protein 4; D055419:Bone Morphogenetic Protein 7; D024042:Collagen Type I; D024141:Collagen Type IV; D005353:Fibronectins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D019063:Tenascin; D053773:Transforming Growth Factor beta1; D052004:Bone Morphogenetic Protein Receptors; C507079:MMP13 protein, human; D053509:Matrix Metalloproteinase 13; C522361:MMP2 protein, human; D020778:Matrix Metalloproteinase 2