Retracted: Pulmonary fibrosis of mice and its molecular mechanism following chronic inhaled exposure to TiO2 nanoparticles.

Abstract

Nanoparticulate titanium dioxide (nano-TiO2 ) has been widely used in industry, medicine and daily life. However, assessment of nano-TiO2 toxicity on health is an important occupational safety issue. Numerous studies have demonstrated that nano-TiO2 can induced sustained pulmonary inflammation, but whether chronic exposure to nano-TiO2 results in pulmonary fibrosis is unclear. In this study, therefore, nano-TiO2 was administered to the male mice by nasal administration for six consecutive months, the inflammatory and/or fibrogenic responses induced by nano-TiO2 were investigated. The results showed that chronic inhaled nano-TiO2 induced pulmonary inflammation and firosis, increased expression of inflammatory cytokines and fibrotic cytokines including nuclear factor-κB, interleukin-1β, tumor necrosis factor-α, monocyte chemotactic protein 1, macrophage inflammatory protein-2, intercellular adhesion molecule 1, vascular cell adhesion molecule 1, transform growth factor -β1, osteopontin, matrix metalloproteinase-1, -2, -3, and -9, tissue inhibitors of metalloproteinase-1, collagen, platelet derived growth factor, and connective tissue growth factor in mouse lung. Taken together, nano-TiO2 -induced pulmonary inflammation and fibrosis are closely associated with increased expression of inflammatory and/or fibrotic cytokines, an imbalanced production of MMPs and TIMP-1 that favors fibrosis in mice, implying that nano-TiO2 may lead to potential health effects.