Introduction: Chronic rhinosinusitis is characterized by persistent inflammation and remodeling in the sinonasal mucosa. Fibroblast activation plays an important role in this remodeling process. The intracellular chloride channel 4 (CLIC4) is known to mediate the activation of cancer-associated fibroblasts. In this study we investigated the effect of CLIC4 on remodeling of the sinonasal mucosa.
Methods: CLIC4 expression in mRNA or protein level was investigated in the sinonasal mucosa of chronic rhinosinusitis patients and controls. Sinonasal fibroblasts were incubated and treated with TGF-1. The expression of CLIC4, -SMA, collagen type I, and fibronectin was determined by a real-time PCR, or western blotting. The reactive oxygen species (ROS) expression was determined using 2’,7’-dichlorofluorescein-diacetate or Mitosox Red fluorescence. Fibroblast migration was evaluated using the Transwell migration assay and the contractile activity was measured by using the collagen contraction assay.
Results: CLIC4 expression level was significantly increased in the sinonasal mucosa compared to the control. TGF-β treatment significantly induced CICL4, myofibroblast differentiation (-SMA) and extracellular matrix (collagen type I, fibronectin) production in the fibroblasts. Blocking of CICL4 expression with siRNA reduced the myofibroblast differentiation and ECM production, migration, and contractile activity. TGF-β1 also increased the amount of ROS production, whereas pretreatment with ROS scavenger significantly decreased the level of CICL4 expression, myofibroblast differentiation and ECM production, migration, and collagen contraction.
Conclusions: CLIC4 plays an important role in TGF-β1-induced myofibroblast differentiation, extracellular matrix production, migration, and contractile activity through the ROS signaling pathway, which contributes to tissue remodeling in chronic rhinosinusitis.
