Plasma levels of TNF-α and MMP-9 in patients with silicosis.

Silicosis is usually recognized at later stages of the disease, and early biomarkers for silicosis will be useful for timely diagnosis. We aimed at examining plasma levels of TNF-α and MMP-9, and correlation between these, in patients with different stages of silicosis in order to test suitability of these inflammatory factors as early biomarkers for silicosis.TNF-α and MMP-9 were quantified by ELISA in plasma specimens from 30 healthy individuals (control group), 28 individuals exposed to silica dust but without clinical disease, and 30 patients with silicosis.Plasma levels of TNF-α and MMP-9 were increased in individuals exposed to silica dust (p < 0.05 vs. control individuals) and were further elevated in patients with silicosis (p < 0.05 vs. control individuals and individuals exposed to silica dust). There was a significant correlation between plasma levels of TNF-α and MMP-9 both in individuals exposed to silica dust (r = 0.696, p < 0.01) and patients with silicosis (r = 0.768, p < 0.01).Plasma levels of TNF-α and MMP-9 are increased prior to development of clinically recognized silicosis, suggesting that these biomarkers are involved in the onset and development of silicosis. Combined detection of TNF-α and MMP-9 may be useful for early diagnosis of silicosis.