Membrane type-matrix metalloproteinases in idiopathic pulmonary fibrosis.
BACKGROUND
Idiopathic pulmonary fibrosis (IPF) is characterized by fibroblast expansion and extracellular matrix accumulation. Some secreted matrix metalloproteinases (MMPs) as MMP2 are highly upregulated in IPF lungs. Membrane-type (MT)-MMPs participate in the activation of pro-MMP2. However, they have not been examined in IPF.


METHODS
Type I transmembrane MT-MMPs, MT1, MT2, MT3, and MT5-MMP were analyzed by real-time PCR and immunohistochemistry in IPF and normal lungs. MMP-2 was also immunolocalized and evaluated by gelatin zymography in BAL fluids. Additionally, the MT-MMPs were examined by real time PCR in lung fibroblasts stimulated with TGF-beta1 and IFN-gamma.


RESULTS
MT1-MMP, was the most highly expressed followed by MT2- and MT5-MMP, and by a moderate expression of MT3-MMP. Regarding their localization, MT1- and MT2-MMPs were found in alveolar epithelial cells, MT3-MMP in fibroblasts from fibroblastic foci and alveolar epithelial cells and MT5-MMP in basal bronchiolar epithelial cells and in areas of squamous metaplasia. MMP2 was localized in alveolar and basal bronchiolar epithelial cells and fibroblasts, and increased active enzyme was observed in BAL fluids. In lung fibroblasts, TGF-beta1 induced a strong upregulation of MT3-MMP, both at the gene and protein level. This effect was blocked by genistein, a protein tyrosin kinase inhibitor and partially repressed by SB203580 a p38 MAP kinase inhibitor. IFN-gamma had no effect.


CONCLUSIONS
MT-MMPs are expressed in IPF, in the same cell types as MMP2. Mostly by different types of epithelial cells a pivotal component in the aberrant remodeling of the lung microenvironment. Interestingly MT3-MMP that was found in fibroblastic foci was upregulated in vitro by TGF-beta1 a potent profibrotic mediator.
García-Alvarez
Jorge
J
Facultad de Ciencias, Universidad Nacional Autónoma de México.
Ramirez
Remedios
R
Sampieri
Clara L
CL
Nuttall
Robert K
RK
Edwards
Dylan R
DR
Selman
Moises
M
Pardo
Annie
A
D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D016022:Case-Control Studies; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000378:metabolism; D005347:Fibroblasts / Q000187:drug effects; D006801:Humans; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D053504:Matrix Metalloproteinases, Membrane-Associated / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D011658:Pulmonary Fibrosis / Q000201:enzymology* / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology
D007527:Isoenzymes; D053773:Transforming Growth Factor beta1; D053504:Matrix Metalloproteinases, Membrane-Associated