Experimental study on the effect of Si and P ion content in SiO2 exposure environment on the degree of pulmonary fibrosis.

Background: Silicosis is a public health issue in developing countries for long and cannot be completely cured.

Objective: To study the changes of ion content with TNF-α and TGF-β expression in alveolar lavage fluid (BALF) at different time points in rats exposed to silica and to investigate their correlation with pulmonary fibrosis.

Methods: 42 rats were randomly divided into control group (n = 12) and exposure group (n = 30). Tissues of right lower lungs were collected and fixed for further Hematoxylin-eosin (HE) and Masson staining. We collected the BALF to examine the inflammatory cytokines of TNF-α and TGF-β and measured the ion contents in BALF.

Results: The increase of TNF-α level was earlier than TGF-β. The content of silica in BALF was significantly increased after exposure and reached the maximum at 7 day, similar to the curve of cytokine TGF-β level. However, phosphorus ions increased quickly after gradual decline of silicon ion and roughly proportional to the curve of degree of fibrosis.

Conclusions: Crystalline silica exposure can cause changes in TGF-β and TNF-α in BALF and accompanied with fibrosis and ions content variation. The abnormal expression of phosphorus ion may have significance in the occurrence and development of silicosis.