Role of Reactive Oxygen Spices in the Wood Smoke Extract Induces IL-8 Production in Human Bronchial Epithelial Cells
| Autor: | Chih-Chieh Lee, 李智傑 |
|---|---|
| Rok vydání: | 2010 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 98 Smoke and particle produced by fire contain toxic chemicals and reactive oxygen species (ROS). Inhalation of the toxic smoke causes severe pulmonary inflammation, which is life-threatening. Because their accessibility to toxic smoke, lung epithelial cells (LECs) play a critical role in the initiation and progression of pulmonary inflammation. Direct exposure of LECs to inflammatory stimuli other than toxic smoke has been shown to induce the increasing of various chemokines production, which including interleukin-8 (IL-8). Indeed, IL-8 has been recognized as the key chemokine for trafficking and recruitment of inflammatory cells such as neutrophil to the alveolar spaces. In LECs, the up-regulation of IL-8 induced by these stimuli involves signaling pathways through the AMP-activated protein kinase (AMPK) activation, mitogen-activated protein kinases (MAPKs) activation and nuclear factor-kappa B (NF-κB) translocation into nucleus. However, the signaling of toxic smoke stimulates LECs leading to up-regulation of IL-8 through AMPK remains unclear. Recent studies suggested AMPK is activated by elevated levels of ROS in the skeletal muscle cells. However, nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase) is a well-known ROS-generating enzyme in phgocytes, which activation through the translocation of p47phox from cytosol to plasma membrane. The activation of NADPH oxidase contributes the progression of inflammation in the cadiac disease is already known. Recently studies show the expression of NADPH oxidase in the salivary gland and airway epithelium is reported. Accordingly, using human brochial epithelial cells (HBECs) treated with wood smoke extract (SE) to simulate the inhalation of toxic smoke, the objectives of this study were to investigate 1.whether the ROS is involved in the signaling pathway of SE induced IL-8 expression through AMPK, ERK, JNK and transcriptional factor NF-κB 2.whether SE activates NADPH oxidase and involve in the signaling pathway of SE-induced IL-8 expression. We found that SE exposure increased IL-8 production and AMPK phophrylation in a dose- and time-dependant manner. Transfection of AMPK siRNA revealed the SE-induced up-regulation of IL-8 was mediated through AMPK. By using the ROS scavenger, N-Acetylcysteine (NAC), SE-induced AMPK activation and IL-8 up-regulation was inhibited. Further, SE-induced ERK (one major member of MAPKs), JNK (one major member of MAPKs) activation and p65 (subunit of NF-κB) translocation was also decreased by NAC pretreatment. The results revealed that ROS regulated the SE-induced AMPK activation and down stream signaling pathways responsible for IL-8 up-regulation. Further investigations through pharmacological inhibition of NADPH oxidase and results suggested that the SE-induced IL-8 up-regulation and AMPK activation is through the ROS production by NADPH oxidase. The elevated levels of ROS in HBEC by SE exposure also decreased after NADPH oxidase inhibition. The increased translocation of p47phox revealed the activation of NADPH oxidase by SE stimulation. Theses results suggest that NADPH oxidase is activated by SE and contributes to the increasing of ROS. The elevated levels of ROS mediated AMPK activation and IL-8 up-regulation through the p65 translocation to nucleus via ERK and JNK phosphorylation. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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