Department of Occupational and Environmental Health, School of Public Health, Medical College, Wuhan University of Science and Technology, Wuhan, 430065, Hubei, China.
Hubei Province Key Laboratory of Occupational Hazard Identification and Control, Wuhan University of Science and Technology, Wuhan, 430065, Hubei, China.
Lung. 2019 Dec;197(6):783-791. doi: 10.1007/s00408-019-00272-x. Epub 2019 Sep 13.
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-β 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.
长期暴露于结晶二氧化硅会导致持续性肺部炎症和进行性纤维化。结缔组织生长因子（CTGF）已成为一种有效的促炎和促纤维化调节剂，参与多种慢性炎症性疾病。然而，CTGF 在二氧化硅诱导的肺部炎症中的作用仍知之甚少。
为了探讨 CTGF 对二氧化硅颗粒引起的炎症反应的影响，用 CTGF siRNA 转染人支气管上皮细胞（16HBE），然后将其暴露于浓度为 0、12.5、25、50、100μg/ml 的二氧化硅颗粒中 48h。分别通过 RT-PCR 和 Western blot 测定细胞内 CTGF mRNA 和蛋白表达。通过 ELISA 试剂盒测定炎症细胞因子（包括 IL-8、TNF-α、IL-6、IL-1β、IL-17A 和 TGF-β）的水平。
与空白对照组相比，二氧化硅颗粒以剂量依赖性方式显著诱导 16HBE 细胞内 CTGF mRNA 表达升高（P<0.05）。IL-8、TNF-α、IL-6 和 IL-17A 的分泌也显著增加（P<0.05）。用 CTGF siRNA 转染后，暴露于 25 或 50μg/ml 二氧化硅颗粒时，16HBE 细胞内 CTGF mRNA 的表达明显受到抑制（P<0.05）。由二氧化硅颗粒诱导的 IL-8、TNF-α、IL-6 和 IL-17A 的分泌水平也明显低于正常 16HBE 细胞的分泌水平（P<0.05）。
抑制 CTGF 基因可减弱二氧化硅诱导的支气管上皮细胞炎症反应，提示 CTGF 可能是二氧化硅诱导炎症发生的关键调节因子。
