The Role of CTGF in Inflammatory Responses Induced by Silica Particles in Human Bronchial Epithelial Cells
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Prolonged exposure to crystalline silica leads to persistent pulmonary inflammation and progressive fibrosis. Connective tissue growth factor (CTGF) has emerged as a potent proinflammatory and profibrotic regulator to participate in a variety of chronic inflammatory diseases. However, the role of CTGF in silica-induced pulmonary inflammation remains poorly understood.
To explore the effect of CTGF on inflammatory responses caused by silica particles, human bronchial epithelial cells (16HBE) were transfected with CTGF siRNA and exposed to silica particles at concentrations of 0, 12.5, 25, 50, 100 μg/ml for 48 h. Intracellular CTGF mRNA and protein expressions were determined by RT-PCR and Western blotting, respectively. The levels of inflammatory cytokines including IL-8, TNF-α, IL-6, IL-1β, IL-17A and TGF-β1 were measured by ELISA kits.
Silica particles induce significantly elevated intracellular CTGF mRNA expression in 16HBE cells in a dose-dependent manner when compared with blank control group (P < 0.05). The secretions of IL-8, TNF-α, IL-6 and IL-17A were also significantly increased by silica particles (P < 0.05). After exposure to 25 or 50 μg/ml silica particles, the expression of intracellular CTGF mRNA was significantly inhibited in 16HBE cells when transfected with CTGF siRNA (P < 0.05). The secreted levels of IL-8, TNF-α, IL-6 and IL-17A induced by silica particles were also significantly lower from CTGF siRNA-transfected cells than that from normal 16HBE cells (P < 0.05).
Inhibition of CTGF gene attenuates silica-induced inflammatory responses in bronchial epithelial cells, suggesting that CTGF could be a pivotal regulator in the development of silica-induced inflammation.
KeywordsSilica particles CTGF Inflammatory cytokines Bronchial epithelial cells
This work was financially supported by grants from the National Natural Scientific Foundation of China (81402659), the China Scholarship Council Fund (201808420128), the Natural Scientific Foundation of Hubei Province (2014CFB811, 2016CFB520) and the Outstanding Project of Young and Middle-aged Team in Wuhan University of Science and Technology (2018TDZ03).
Compliance with Ethical Standards
Conflict of interest
The authors declare that they have no conflict of interest.
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