Objective To investigate the role of lipid metabolism in the fibrosis progression of silicosis through detecting cholesterol and oxidized low density lipoprotein (ox-LDL) levels in alveolar macrophages and bronchoalveolar lavage fluid (BALF) from patients in different silicosis stages.
Methods Fifty-nine male patients with silicosis were selected,among whom 18 cases were graded as stage Ⅰ,17 cases as stage Ⅱ,and 24 cases as stage Ⅲ;8 controls were recruited;another 12 healthy adults were selected as serum control group.HE staining and oil red O staining were used to observe macrophage morphology and lipid accumulation,and ELISA was used to detect cholesterol,ox-LDL,and connective tissue growth factor (CTGF) levels in alveolar macrophages and BALF.
Results Lipids existed in alveolar macrophages.Cholesterol levels increased in alveolar macrophages and BALF with higher silicosis stages,and the cholesterol level of stage Ⅲ group was significantly higher than that of the control,stage I,and stage Ⅱ groups (P<0.05).The ox-LDL level in alveolar macrophages increased with higher silicosis stages,whereas in the BALF it showed a declining trend (P<0.05).Compared with the serum control group,the CTGF level in serum was increasing with the advance of silicosis (P<0.05).Cholesterol in alveolar macrophages and BALF and ox-LDL in alveolar macrophages were positively correlated with CTGF (P<0.05),but ox-LDL in BALF was negatively correlated with CTGF (P<0.05).
Conclusion In the advance of silicosis fibrosis,cholesterol metabolism disorder in alveolar macrophages are identified in silicosis patients,which might be related to the macrophage foam cells caused by elevated ox-LDL level.
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