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MAP kinase mediates silica‐induced fibrotic nodule formation and collagen accumulation in fibroblasts
Author(s) -
Li Yunyuan,
Kilani Ruhangiz T.,
Hartwell Ryan,
Ghahary Aziz
Publication year - 2012
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.22739
Subject(s) - extracellular matrix , mapk/erk pathway , microbiology and biotechnology , kinase , fibronectin , fibrosis , p38 mitogen activated protein kinases , protein kinase a , chemistry , type i collagen , procollagen peptidase , fibroblast , matrix metalloproteinase , extracellular , signal transduction , biology , biochemistry , in vitro , pathology , medicine , endocrinology
It is well known that silica generates fibrosis around them in animals and human. However, the pathogenesis and mechanism of silica‐induced fibrosis are still poorly understood. Here, we established a new strategy through which the effects of silica on fibrotic nodule formation, key extracellular matrix accumulation, and the mechanism involved were explored. To achieve this, human dermal fibroblasts were directly exposed to silica gel for various durations. Fibrotic nodule formation was evaluated by their microscopic appearance, type‐1 procollagen, and fibronection expression in cell lysate and MMP‐1 and‐3 in conditioned media were analyzed by Western blotting. The results show an easily formation of nodule‐like structures around silica gel in an in vitro‐cultured system. The findings further revealed that silica gel stimulates collagen and fibronectin expression, while down‐regulates matrix metalloproteinase‐1 and ‐3 (MMP‐1 and MMP‐3) released in conditioned medium. To explore the mechanism involved, P38 and ERK1/2 Mitogen‐Activated Protein Kinase (MAPK) signaling pathways were evaluated. Result showed that silica inhibits P38 and extracellular signal‐regulated kinases (ERK1/2) MAP kinase phosphorylation. The addition of ERK1/2 inhibitor increases silica‐stimulated type‐1 collagen expression, reduces MMP‐1 release and further enhances silica‐induced nodule formation in dermal fibroblasts. These findings indicate that the inhibition of ERK1/2 MAPK signaling pathway may contribute to silica‐caused fibrosis. In summary, our findings suggest that silica can directly cause fibrotic phenotype when fibroblasts contact with silica particles independent of any inflammation and other factors may exist in an in vivo condition. J. Cell. Physiol. 227: 328–338, 2012. © 2011 Wiley Periodicals, Inc.