Oxidative stress induces unfolding protein response and inflammation in nasal polyposis.

BACKGROUND: Nasal polyposis, a chronic inflammatory disease affecting the upper airways, is a valuable and accessible model to investigate the mechanisms underlying chronic inflammation. The main objective of this study was to investigate a potential involvement of the unfolded protein response (UPR) in the context of oxidative stress and inflammation in nasal epithelial cells from nasal polyps (NP). METHODS: Epithelial cells from NP (n = 20) and normal mucosa (Controls, n = 15) in primary culture were analyzed by global proteomic approach and cell biology techniques for the glucose-regulated protein 78 (GRP78), the spliced X-box-binding protein 1 (sXBP-1), the glucose-regulated protein 94 (GRP94), and the calreticulin (immunoblot, mass spectrometry, immunocytochemistry). RESULTS: Proteomics analysis of human nasal epithelial cells in culture revealed the activation of the unfolded protein response in NP. Systematic cell biology and biochemical analysis of two markers (GRP78, sXBP-1) in the presence and absence of oxidative stress in NP showed a susceptibility of the unfolded protein response to oxidative stress compared to controls at least partially linked to an abnormal redox state of the protein disulfide-isomerase 4. This unfolded protein response was correlated with mitochondrial depolarization and secretion of interleukin 8 (IL-8) and leukotriene B4 (LTB4) and was prevented by mitochondrial antioxidant. CONCLUSIONS: We show the existence of UPR in nasal epithelial cells that is linked to oxidative stress leading to IL-8 and LTB4 secretions. These mechanisms may participate in chronic inflammation in nasal polyposis.

Controlled transgene expression by E1-E4-defective adenovirus vectors harbouring a "tet-on" switch system.

BACKGROUND: The "tet switch system" was originally described under the tet-off configuration with its components encoded by two separate plasmids. Since then, many virus vectors harbouring tet-off components have been designed and their regulation by tetracycline is widely reported. On the contrary, tet-on regulation by viral vectors is poorly documented. METHODS: E1-E4-defective adenoviruses harbouring either rtTA or the luciferase gene under a minimal inducible promoter (TK* or CMV*) or both components in a single genome were produced. Using either a double or a single virus strategy, induction of luciferase expression was investigated in various cell lines, in mice muscle and in rat brain. RESULTS: Over 400-fold induction can be reached with PC12 and NHA cells using a double virus strategy. Comparison of the background activity of different minimal inducible promoters revealed a significant difference between TK* and CMV* promoters both with the cell culture and the in vivo experiments. Interestingly, a single virus strategy permitted an induction exceeding 600-fold with human astrocyte primary cells. Moreover, the E1-E4-defective adenovirus-mediated tet-on system can be quickly switched off and turned back on again. Depending on the cell line, the level of rtTA derived by the single virus strategy differed, resulting in different efficiencies. Experiments performed in rat striatum and mouse muscle confirmed the importance of rtTA expression and minimal promoter used on both doxycycline-independent expression and induction efficiency. Under appropriated rtTA expression, a 32-fold induction is observed in mouse muscle. CONCLUSIONS: In the recombinant adenovirus context, the CMV* but not the TK* promoter is sensitive to transcriptional interference resulting in high doxycycline-independent expression. By paying attention to the rtTA expression, moderate and high induction can be obtained in vivo and in vitro accordingly.

Synthesis and HIV-1 integrase inhibitory activities of catechol and bis-catechol derivatives.

Fourteen catechol and bis-catechol derivatives have been synthesised and tested for their HIV-1 inhibitory activities. The six more active molecules have been tested for their antiviral activity and cytotoxicity. We have found that bis-catechols 1 and 2 are the most active HIV-1 integrase inhibitor whereas the best antiviral compound is 4.