Waterpipe Smoke Exposure Triggers Lung Injury and Functional Decline in Mice: Protective Effect of Gum Arabic

Abstract

The prevalence of waterpipe (shisha) tobacco smoking has recently seen a substantial increase worldwide and is becoming a public health problem. Both human and animal studies have established that waterpipe smoke (WPS) increases airway reactivity and inflammation. Gum Arabic (GA) is a prebiotic agent that possesses antioxidant and anti-inflammatory properties. However, its effects on lung toxicity induced by WPS exposure are unknown. Thus, the aim of this study was to investigate the possible salutary effects and underlying mechanisms of GA on WPS-induced pulmonary pathophysiologic effects. C57BL/6 mice were exposed to air or WPS (30 minutes/day for one month) with or without GA treatment in drinking water (15%, w/v). Exposure to WPS induced an influx of neutrophil polymorphs in the peribronchiolar and interstitial spaces and an increase of tumor necrosis factor-α and 8-isoprostane, a marker of lipid peroxidation, concentrations in lung homogenates. The latter effects were significantly mitigated by GA treatment. Likewise, the lung DNA damage induced by WPS exposure was prevented by GA administration. Western blot analysis of the lung showed that GA inhibited nuclear factor kappa-B (NF-κB) expression caused by WPS and augmented that of nuclear factor erythroid 2-related factor 2 (Nrf2). Similarly, immunohistochemical analysis of bronchial epithelial cells and alveolar cells showed a parallel and significant increase in the nuclear expression of Nrf2 and cytoplasmic expression of glutathione in mice treated with GA and exposed to WPS. Moreover, GA administration has significantly prevented airway hyperreactivity to methacholine induced by WPS. We conclude that GA administration significantly declined the physiological, histological, biochemical, and molecular indices of lung toxicity caused by WPS exposure, indicating its beneficial respiratory impact. Considering that GA is a safe agent with health benefits in humans, our data suggest its potential usage in waterpipe smokers.

Comparative Study on Pulmonary Toxicity in Mice Induced by Exposure to Unflavoured and Apple- and Strawberry-Flavoured Tobacco Waterpipe Smoke

“…The WPS inhalation protocol has been performed according to recently described methods [9][10][11]. Mice were exposed using a nose-only exposure system (InExpose System, Scireq, Canada) to mainstream WPS generated by commercially available P-or AF-or SF-tobacco (Al Fakher Tobacco Trading, Ajman, UAE).…”

“…Control mice were exposed to air only. The duration of the session was 30 min/day and 5 days/wk for 1 mo [9][10][11]. The inhalation procedure was monitored by a computerized system.…”

“…Airway hyperreactivity responses were evaluated in the air, P-WPS, AF-WPS, and SF-WPS groups using a forced oscillation technique (flexiVent, SCIREQ, Montreal, Canada). Airway resistance (R) was assessed after increasing exposures to methacholine aerosol produced with an inline nebulizer and given directly via the ventilator (0-40 g/ml), according to recently described techniques [10,11].…”

“…After fixation of lung tissue in neutral buffered formalin (10% w/v) for a day, the tissue was gradually dehydrated in increasing concentrations of ethanol, cleared of alcohol residue in xylene, and lastly embedded in paraffin. Sections of 5 μm (7 sections per lung) were cut with a microtome (RM2125 RTS, Leica Biosystems, Nussloch, Germany) and stained with hematoxylin and eosin [11,12]. The stained sections were mounted on slides and evaluated blindly under a light microscope with a 40× objective lens by the histopathologist (SA) who contributed in this study.…”

“…The obtained measurements were expressed as optical density using a microplate reader with a 450 nm filter (OD 450nm ). Moreover, the expression of NF-κB levels was also quantified by the Western blot analysis as described before [10,11].…”