| Summary: | 碩士 === 高雄醫學大學 === 生物醫學暨環境生物學研究所 === 100 === Pulmonary fibrosis is a progressive chronic inflammatory disease. It is also regarded as a result of wound healing. Differentiation of pulmonary fibroblast can be activated by many inflammatory mediators, such as cytokines and chemokines, which induce cell migration, proliferation, and differentiation, leading to pulmonary fibrosis. Aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor. It can be activated by binding with many environmental contaminants, such as Benzo[a]pyrene (B[a]P) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The activated AhR is known to alter gene transcription, induce immune responses and tumorigenesis. Therefore, the purpose of the present study is to investigate the effect of AhR ligands on pulmonary fibroblast differentiation and signaling pathway involved. Using western blot, immunofluorescent staining, boyden chamber migration assay, real-time PCR and AhR siRNA transfection, we found that, in human fetal lung fibroblasts (HFL-1 cell line), AhR ligands enhanced α-smooth muscle actin (α-SMA) protein expression and cell migration, and also increased cytochrome P450-1B1 (CYP1B1) mRNA expression and AhR nuclear translocation. α-SMA protein expression stimulated by AhR ligands was reduced by knockdown of AhR (siAhR). We also observed that, AhR ligands enhanced cyclooxygenase-2 (COX-2) and 5-Lipoxygenase (5-LOX) protein expression and increased prostaglandin E2 (PGE2) and Leukotriene B4 (LTB4) secretion. Using living cell calcium image study, we observed that, TCDD stimulation increased intracellular calcium concentration and cytosolic phospholipase A2 (cPLA2) protein expression; however, B[a]P stimulation did not cause any of these effects. According to these results, we suggested that, AhR ligands induce human pulmonary fibroblast migration, differentiation and inflammatory responses. Pulmonary fibroblast differentiation stimulated by AhR ligands may be mediated by the AhR signaling pathway. Moreover, TCDD may increase intracellular calcium concentration through the AhR signaling pathway, and then mediate the pulmonary fibroblast differentiation.
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