OBJECTIVETo study the effect of culture supernatant of alveolar macrophage alveolar macrophages (AM) stimulated by SiO2 on the expression of matrix metalloproteinases (MMP-1), tissue inhibitor of metalloproteinase-1 (TIMP-1) and collagen of fibroblast human embryonic lung fibroblasts (HELF) in the development of silicosis fibrosis.

METHODSAMs were collected from a silicotic patient by bronchoalveolar lavage and exposed to SiO2, cultured human embryo lung fibroblast were allocated into a treated group, a control group, a positive group, and a blank group. HELF was incubated with the cultured supernatant of AMs for 6, 12, 18, 24, 36, 48 h. Immunocytochemical and Western blot technology were used to detect MMP-1 and TIMP-1 expressions in HELF and collagen expression in supernatant of HELF respectively.

RESULTSThe supernatant of AM exposed to SiO2 significantly decreased the expressions of MMP-1 (0.0605 +/- 0.0201, 0.0519 +/- 0.0117, 0.0412 +/- 0.0105 and 0.0213 +/- 0.0106 in the treated group at 18, 24, 36 and 48 h) compared with the control group and the blank group (P < 0.05, P < 0.01) but stimulated expressions of TIMP-1 and collagen (P < 0.05, P < 0.01). The ratio of TIMP-1 to MMP-1 increased. The ratio of TIMP-1 to MMP-1 was positively correlated with the expression of collagen III (r = 0.88, P < 0.01).

CONCLUSIONThrough AM mediation SiO2 can accelerate the expression of TIMP-1 and collagen, and inhibit the expression of MMP-1. The imbalance between the expression of TIMP-1 and that of MMP-1 is related with the abnormal increase in collagen III.