[Effect of SiO2 on the expression of MMP-9 and TIMP-1 in human alveolar macrophages in vitro].
OBJECTIVE
To study the effect of SiO(2) on the expression of matrix metalloproteinase (MMP) and tissue inhibitor of metalloproteinase (TIMP) in human alveolar macrophages (AMs) associated with the pathogenesis of silicotic fibrosis.


METHODS
AMs were collected from a silicotic patient by bronchoalveolar lavage, and exposed to SiO(2) (50 microg/ml), and cultured in DMEM without serum for different time (2, 6, 12, 18, 24, 36 h). Immunocytochemical method was used to detect the level of expression of MMP-9 and TIMP-1 in AMs.


RESULTS
The expression of MMP-9 in AMs exposed to silica was up-regulated, and reached the peak at 18 h [average optical density: (0.440 +/- 0.021) vs (0.390 +/- 0.011), P < 0.05]. After that, the expression reduced markedly. However, the expression of TIMP-1 of AMs were not significantly different from the control group [average optical density: (0.175 +/- 0.019) vs (0.162 +/- 0.044), P > 0.05].


CONCLUSIONS
SiO(2) could induce up-expression of MMP-9 in AMs. Degradation of basement membrane by MMP-9 produced by AMs at early stage of lung injury may associate with the immigration of various cells including lung fibroblasts into the injured region.
Ma
Xiao-bing
XB
Department of Pathology of North China Coal Medical College, Tangshan, Hebei Province 063000, China.
Li
Xiu-ling
XL
Sun
Shu-xun
SX
Yang
Fang
F
D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D002478:Cells, Cultured; D006801:Humans; D007150:Immunohistochemistry; D016676:Macrophages, Alveolar / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000096:biosynthesis*; D008875:Middle Aged; D012822:Silicon Dioxide / Q000494:pharmacology*; D012829:Silicosis / Q000473:pathology*; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000096:biosynthesis*
D019715:Tissue Inhibitor of Metalloproteinase-1; D012822:Silicon Dioxide; D020780:Matrix Metalloproteinase 9