RESUMO
OBJECTIVE: To observe the expression of acidic mammalian chitinase(AMCase) in lung tissue of silicosis model rats, and bronchoalveolar lavage fluid(BALF) and serum of patients with occupational pneumoconiosis, and to evaluate the value of AMCase in the early diagnosis of pneumoconiosis. METHODS: i) The specific pathogen free adult male Wistar rats were randomly divided into control group and model group, with 15 rats in each group. The rats in the silicosis model group was exposed to free silica dust with a concentration of 2 000.0 mg/m~3 by dynamic inhalation for three hours a day, while the rats in control group were not exposed to dust. Five rats in the two groups were sacrificed at 4, 12 and 24 weeks after dust exposure. ii) By random number table method, a total of 191 patients with occupational pneumoconiosis who received large capacity lung lavage were selected as the pneumoconiosis group, 12 dust-exposed workers who received large capacity lung lavage were selected as the dust control group, and 200 healthy coal miners exposed to dust were selected as healthy control group. iii) Western blotting was used to detect the relative protein expression of AMCase, type Ⅰ collagen(COLⅠ), α-smooth muscle actin(α-SMA) in lung tissues of the rats and the relative protein expression of AMCase in human BALF. Enzyme linked immunosorbent assay was used to detect the level of AMCase protein in human serum. Receiver operating characteristic(ROC) curve was used to evaluate the value of AMCase protein level in human serum for early diagnosis of pneumoconiosis. RESULTS: The relative expression of AMCase, COLⅠand α-SMA protein in lung tissue of rats in the silicosis model group were higher than that of control group(all P<0.01). The relative expression of AMCase protein in BALF of pneumoconiosis group and pneumoconiosis stage Ⅰ, Ⅱ and Ⅲ subgroups were higher than that of dust control group(all P<0.05). The level of AMCase protein in serum of pneumoconiosis group and pneumoconiosis stage Ⅰ, Ⅱ and Ⅲ subgroups were higher than that of healthy control group(all P<0.05). The results of ROC curve analysis showed that the area under ROC curve was 0.78(95% confidence interval: 0.74-0.82).When the cut-off value of serum AMCase protein level was 466.0 ng/L, the sensitivity was 73.8%, and the specificity was 72.6%. CONCLUSION: AMCase protein in human serum has value for early diagnosis of pneumoconiosis and it could be a potential biomarker for early diagnosis of pneumoconiosis.