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A2471 - Cigarette Smoke Exposure Induces Loss of Lung WWOX Expression Which Is Associated with Increased Vascular Leak During ARDS
Author Block: S. Singla1, Z. Shakir1, M. T. Gomes2, N. M. Jones2, V. Natarajan3, R. F. Machado2; 1Medicine, University of Illinois, Chicago, IL, United States, 2Medicine, Indiana University, Indianapolis, IN, United States, 3Pharmacology, University of Illinois, Chicago, IL, United States.
RATIONALE: Smokers exhibit an increased susceptibility to severe Acute Respiratory Distress Syndrome (ARDS) relative to nonsmokers. The tumor suppressor gene, WWOX, resides at the second most active common chromosomal fragile site in the human genome, making it highly susceptible to genotoxic stress such as that which occurs during cigarette smoke exposure. We have previously shown that loss of lung WWOX expression causes neutrophilic inflammation. It may also exhibit ARDS-relevant effects on lung endothelial cell (EC) barrier function via its known interaction with the membrane-actin linker protein, ezrin. We hypothesize that cigarette smoke induced downregulation of lung WWOX expression plays a role in increased neutrophilic inflammation and lung vascular leak during ARDS. METHODS: Electric cell impedance sensing (ECIS) was used to study the effects of siRNA mediated silencing of WWOX during LPS-induced EC barrier dysfunction. EC-specific silencing of lung WWOX in mice was achieved using intratracheal instillation of lentivirus carrying a WWOX-specific miR RNAi under control of the VE-Cadherin promoter. These mice were assessed for differences in lung vascular leak compared to wild type during an LPS model of ARDS. Finally, WWOX expression was examined via Western blotting and RT-PCR in lung tissue from human smokers versus nonsmokers, lung tissue from mice treated with cigarette smoke condensate (CSC), ECs treated with LPS, CSC and/or 5-aza. RESULTS: WWOX-silenced ECs exhibited increased LPS-induced barrier disruption compared to controls. Vascular leak was significantly worse in LPS-treated animals subjected to EC WWOX-silencing compared to negative controls. Lung WWOX expression was on average 47% lower in tissue from current versus former or never smokers. Cigarette smoke condensate (CSC) was found to downregulate lung WWOX expression in mice and in human ECs. Additionally, CSC blunted LPS-induced increases in EC WWOX, an effect which was negated by pre-treatment with 5-Aza. CONCLUSION: Increased susceptibility for severe ARDS observed in smokers may be at least partly explained by the effects of cigarette smoke induced loss of lung WWOX expression.