Cigarette Smoke and Nicotine-Containing Electronic-Cigarette Vapor Downregulate Lung WWOX Expression, Which Is Associated with Increased Severity of Murine Acute Respiratory Distress Syndrome

Abstract

RATIONALE: A history of chronic cigarette smoking is known to increase risk for ARDS, but the corresponding risks associated with chronic e-cigarette use are largely unknown. The chromosomal fragile site gene, WWOX, is highly susceptible to genotoxic stress from environmental exposures, and thus an interesting candidate gene for the study of exposure-related lung disease. METHODS AND RESULTS: Lungs harvested from current versus former/never smokers exhibited a 47% decrease in WWOX mRNA levels. Exposure to nicotine-containing e-cigarette vapor resulted in an average 57% decrease in WWOX mRNA levels relative to vehicle treated controls. In separate studies, endothelial (EC)specific WWOX KO versus wild type mice were examined under ARDS-producing conditions. EC WWOX KO mice exhibited significantly greater levels of vascular leak and histologic lung injury. ECs were isolated from digested lungs of untreated EC WWOX KO mice using sorting by flow cytometry for CD31+CD45-cells. These were grown in culture, confirmed to be WWOX-deficient by RT-PCR and Western blotting, and analyzed by electric cell impedance sensing (ECIS) as well as a FITC dextran transwell assay for their barrier properties during MRSA or LPS exposure. WWOX KO ECs demonstrated significantly greater declines in barrier function relative to wild type cells during either MRSA or LPS treatment as measured by both ECIS and the transwell assay.CONCLUSION: The increased risk for ARDS observed in chronic smokers may be mechanistically linked, at least in part, to lung WWOX downregulation, and this phenomenon may also manifest in the near future in chronic users of e-cigarettes.

Endothelial knockdown of the tumor suppressor, WWOX, increases inflammation in ventilator-induced lung injury

“…Previous observations in humans indeed suggest significant downregulation of gene and protein expression of Wwox in the lung following chronic cigarette smoke exposure [3].…”

“…Endothelial cells were isolated from ECWX Flox (control) and ECWX-KO mice as described previously [3]. Flow cytometry for CD31+CD45-cells was performed, and these endothelial cells were then cultured on gel coated plates.…”

“…Intratracheal instillation of Wwox-targeting siRNA in mice was observed to result in further potentiation of neutrophilic inflammation in a lipopolysaccharide (LPS)-induced murine model of lung injury [4]. Endothelial cell specific Wwox knockout (EC-Wwox KO) mice stimulated by intratracheal LPS or methicillin-resistant Staphylococcus aureus (MRSA) exhibited significantly greater level of vascular leak and histologic lung injury [3].…”

Cortactin Modulates Lung Endothelial Apoptosis Induced by Cigarette Smoke

“…As an alternative to traditional cigarettes, e-cigarettes are gaining popularity, especially among youth. However, inhalation of e-cigarette vapors may also damage the lung tissue [ 16 , 17 ], and in 2019, the CDC/FDA declared an e-cigarette epidemic due to a national outbreak of e-cigarette-induced acute lung injury cases [E-cigarette or Vaping product use-associated lung injury (EVALI)] [ 18 ]. In addition, e-cigarette use is associated with an increased risk for the development of other pulmonary diseases such as COPD [ 19 ].…”