Exercise Training Mitigates Water Pipe Smoke Exposure-Induced Pulmonary Impairment via Inhibiting NF-κB and Activating Nrf2 Signalling Pathways

Pathophysiologic effects of waterpipe (shisha) smoke inhalation on liver morphology and function in mice

AIMS

The global prevalence of waterpipe tobacco smoking is increasing. Although the cardiorespiratory, renal, and reproductive effects of waterpipe smoking (WPS) are well-documented, there is limited knowledge regarding its adverse impact on the liver. Therefore, our study aimed to assess the effects and potential mechanisms of WPS inhalation for one or four weeks on the liver.

MAIN METHODS

Mice were exposed to WPS for 30 min per day, five days per week, while control mice were exposed to clean air.

KEY FINDINGS

Analysis using light microscopy revealed the infiltration of immune cells (neutrophils and lymphocytes) accompanied by vacuolar hepatic degeneration upon WPS inhalation. At the four-week timepoint, electron microscopy analysis demonstrated an increased number of mitochondria with a concomitant pinching-off of hepatocyte plasma membranes. WPS exposure led to a significant rise in the activities of liver enzymes alanine aminotransferase and aspartate aminotransferase in the bloodstream. Additionally, WPS inhalation elevated lipid peroxidation and reactive oxygen species levels and disrupted the levels of the antioxidant glutathione in liver tissue homogenates. The concentration of proinflammatory cytokines, including tumor necrosis factor α, interleukin (IL)-6, and IL-1β, was significantly increased in the WPS-exposed group. Furthermore, WPS inhalation induced DNA damage and a significant increase in the levels of cleaved caspase-3, cytochrome C and hypoxia-inducible factor 1α along with alterations in the activity of mitochondrial complexes I, II, III and IV.

SIGNIFICANCE

Our findings provide evidence that WPS inhalation triggers changes in liver morphology, oxidative stress, inflammation, DNA damage, apoptosis, and alterations in mitochondrial activity.

Respiratory issues in patients with multiple sclerosis as a risk factor during SARS-CoV-2 infection: a potential role for exercise

Coronavirus disease-2019 (COVID-19) is associated with cytokine storm and is characterized by acute respiratory distress syndrome (ARDS) and pneumonia problems. The respiratory system is a place of inappropriate activation of the immune system in people with multiple sclerosis (MS), and this may cause damage to the lung and worsen both MS and infections.The concerns for patients with multiple sclerosis are because of an enhance risk of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The MS patients pose challenges in this pandemic situation, because of the regulatory defect of autoreactivity of the immune system and neurological and respiratory tract symptoms. In this review, we first indicate respiratory issues associated with both diseases. Then, the main mechanisms inducing lung damages and also impairing the respiratory muscles in individuals with both diseases is discussed. At the end, the leading role of physical exercise on mitigating respiratory issues inducing mechanisms is meticulously evaluated.

Treadmill training improves respiratory function in rats after spinal cord injury by inhibiting the HMGB1/TLR-4/NF-κB signaling pathway

OBJECTIVE

To investigate the effects of treadmill training on lung injury and HMGB1/TLR4/NF-κB after spinal cord injury (SCI) in rats.

METHODS

A total of 108 female SD rats were randomly divided into three groups: sham operation group, SCI brake group, and SCI exercise group. The rats in the SCI exercise group began treadmill running training on the 3rd day after the operation. The rats in the SCI brake group underwent braking treatment. The lung tissues were obtained on the 3rd, 7th, and 14th days after exercise. Locomotor functional recovery was determined using the BBB scores and inclined plane test. Respiratory function was determined via abdominal aortic blood gas analysis. HE staining was used to detect pathological changes in rat lung tissue. RNA sequencing was used to identify differentially expressed genes at different phases in each group of lung tissues. HMGB1, TLR4, and NF-κB in lung tissue were detected using immunohistochemistry and immunofluorescence. Detection of HMGB1 levels in serum, spinal cord tissues and lung tissues by ELISA. HMGB1, TLR4, NF-κB, IL-1β, IL-6, TNF-α mRNA, and protein expression levels were detected via qRT PCR and western blot.

RESULTS

Motor and respiratory functions significantly decreased after SCI (P<0.05). However, locomotion and respiratory functions were significantly improved after treadmill training intervention (P < 0.05). HE staining showed that interstitial thickening, inflammatory cells, and erythrocyte infiltration occurred in lung tissue of rats after SCI (P<0.05). Moreover, inflammatory reaction in lung tissue was significantly reduced after treadmill training intervention (P<0.05). A total of 428 differentially expressed mRNAs [(|log2(FC)| > 2, P < 0.05)] were identified in the intersection of the three groups. KEGG analysis identified five enriched signal pathways, including NF-kappa B. ELISA results showed that treadmill training could significantly reduce the levels of HMGB1 in serum, spinal cord tissue and lung tissue that were elevated after SCI (P < 0.05). Immunohistochemistry, immunofluorescence, qRT PCR, and Western blot showed that HMGB1, TLR4, IL-1β, IL-6, TNF-α, and NF-κB expressions were significantly up-regulated at the 3rd, 7th and 14th days after SCI, compared with the sham operation group. Besides, inflammatory cytokines were significantly lower in the SCI exercise group than in the SCI brake group at all time points after intervention (P < 0.05).

CONCLUSION

Treadmill training alleviates lung tissue inflammation and promotes recovery of motor and respiratory functions by inhibiting the HMGB1/TLR4/NF-κB signaling pathway after SCI in rats.

Waterpipe tobacco smoke and health: What we have learned from rodent models?

AIMS

Waterpipe smoking (WPS) is a popular form of tobacco smoking. This is due to the misperception that WPS is less detrimental than cigarette smoking. This review aimed to present the adverse effects of WPS on health outcomes through utilizing animal models.

MAIN METHODS

The design of the current study is systematic review. PubMed, HINARI, Google, and SCOPUS databases were searched for the adverse effects of WPS on general health in rodents. Certain key information was extracted and collected from the included studies.

KEY FINDINGS

After screening different databases and removal of duplicates, 43 papers were included in this review. It was found that WPS was able to negatively affect the oxidative stress and inflammatory biomarkers in mice. Furthermore, WPS increased the levels of Tumor necrosis factor-α and 8-isoprostane, and DNA damage in mice lung homogenates. Additionally, chronic exposure to WPS increased the serum levels of creatinine and blood urea nitrogen in mice; indicating injury to renal tissues. The negative effect of WPS extends to affect offspring rats following prenatal WPS, in which WPS in utero lead to remarkable increase in the levels of testosterone, estrogen and follicle-stimulating hormones in WPS exposed animals.

SIGNIFICANCE

This systematic review highlighted the adverse effects of WPS on health outcomes at cellular and biochemical levels in different tissues and organs of rodents. The current reviews' findings highlighted the great hazards presented by WPS in the selected rodents' model and the essential necessity for future improved management of WPS indoor consumption.

Arsenic exposure and its joint effects with cigarette smoking and physical exercise on lung function impairment: Evidence from an occupational cohort study

BACKGROUND

Arsenic (As) is an established toxic metal, but its effect on longitudinal lung function change among occupational workers is less conclusive.

METHODS

1243 participants were recruited in a coke-oven plant and followed up from 2010 to 2014. Each individual provided 20 mL morning urine sample at baseline, which was then used for urinary levels of As (U-As) and polycyclic aromatic hydrocarbon (PAH) metabolites detecting. Lung function levels at both baseline and the end of follow-up were determined. Multiple linear regression models were used to analyze the associations between U-As with annual lung function changes, and to evaluate the joint effects of U-As with cigarette smoking and regular physical exercise.

RESULTS

Among all participants, each 2-fold increase in U-As was associated with -12.09 (95%CI: -19.37, -4.81) mL, -0.32% (95%CI: -0.54%, -0.10%), -15.04 (95%CI: -24.62, -5.46) mL, and -0.36% (95%CI: -0.64%, -0.08%) annual changes in reduced forced expiratory volume in 1 second (FEV1), percent predicted FEV1 (ppFEV1), forced vital capacity (FVC), and percent predicted FVC (ppFVC), respectively. These effects were more pronounced among coke-oven workers with smoking (especially heavy smoking with pack-years≥15) and without regular physical exercise. Compared to low-As-exposed (≤4.70 μg/mmol creatinine) non-smokers with regular physical exercise, the high-As-exposed (>4.70 μg/mmol creatinine) smokers without regular physical exercise had the worst annual declines in FEV1 [β (95%CI) = -69.01 (-106.67, -31.34) mL], ppFEV1 [β (95%CI) = -1.94% (-3.02%, -0.87%)], FVC [β (95%CI) = -78.66 (95%CI: -129.46, -27.86) mL], and ppFVC [β (95%CI) = -1.80% (-3.23%, -0.37%)].

CONCLUSIONS

The findings in our prospective cohort study suggested the positively linear dose-response relationship of U-As with annual lung function decline. The adverse effects of As could be enhanced by cigarette smoking and attenuated by regular physical exercise. Specific emphasizes on tobacco control and physical exercise were suggested to prevent As exposure induced pulmonary impairment.

The Chronic Effects of Narghile Use on Males' Cardiovascular Response During Exercise: A Systematic Review

Narghile use has regained popularity throughout the world. Public opinion misjudges its chronic harmful effects on health, especially on the cardiovascular system. This systematic review aimed to evaluate the chronic effects of narghile use on cardiovascular response during exercise. It followed the preferred reporting items for systematic reviews guidelines. Original articles from PubMed and Scopus published until January 31, 2020, written in English, and tackling the chronic effects of narghile use on human cardiovascular response during exercise were considered. Five studies met the inclusion criteria. Only males were included in these studies. They were published between 2014 and 2017 by teams from Tunisia (n = 4) and Jordan (n = 1). One study applied the 6-min walk test, and four studies opted for the cardiopulmonary exercise test. Narghile use was associated with reduced submaximal (e.g., lower 6-min walk distance) and maximal aerobic capacities (e.g., lower maximal oxygen uptake) with abnormal cardiovascular status at rest (e.g., increase in heart rate and blood pressures), at the end of the exercise (e.g., lower heart rate, tendency to chronotropic insufficiency) and during the recovery period (e.g., lower recovery index). To conclude, chronic narghile use has negative effects on cardiovascular response to exercise with reduced submaximal and maximal exercise capacities.

Effect of smoking cessation on chronic waterpipe smoke inhalation-induced airway hyperresponsiveness, inflammation, and oxidative stress

Waterpipe smoking (WPS) prevalence is increasing globally. Clinical and laboratory investigations reported that WPS triggers impairment of pulmonary function, inflammation, and oxidative stress. However, little is known if smoking cessation (SC) would reverse the adverse pulmonary effects induced by WPS. Therefore, we evaluated the impact of WPS inhalation for 3 mo followed by 3 mo of SC (air exposure) compared with those exposed for either 3 or 6 mo to WPS or air (control) in C57BL/6 mice. To this end, various physiological, biochemical, and histological endpoints were evaluated in the lung tissue. Exposure to WPS caused focal areas of dilated alveolar spaces and foci of widening of interalveolar spaces with peribronchiolar moderate mixed inflammatory cells consisting of lymphocytes, macrophages, and neutrophil polymorphs. The latter effects were mitigated by SC. Likewise, SC reversed the increase of airway resistance and reduced the increase in the levels of myeloperoxidase, matrix metalloproteinase 9, granulocyte-macrophage colony-stimulating factor, tumor necrosis factor-α, interleukin (IL)-6, and IL-1β in lung tissue induced by WPS. In addition, SC attenuated the increase of oxidative stress markers including 8-isoprostane, glutathione, and catalase induced by WPS. Similarly, DNA damage, apoptosis, and the expression of NF-κB in the lung induced by WPS inhalation were alleviated by CS. In conclusion, our data demonstrated, for the first time, to our knowledge, that SC-mitigated WPS inhalation induced an increase in airway resistance, inflammation, oxidative stress, DNA injury, and apoptosis, illustrating the benefits of SC on lung physiology.

The Ameliorative Role of Acacia senegal Gum against the Oxidative Stress and Genotoxicity Induced by the Radiographic Contrast Medium (Ioxitalamate) in Albino Rats

Arabic gum (Acacia senegal, AG) is proven effective antioxidant and cytoprotective agent. The present study was designed to test this notion by investigating the possible role of AG against the radiographic contrast medium (Ioxitalamate, Telebrix-35^®, TBX)-induced oxidative stress and genotoxicity. Albino rats were divided into four groups and supplied with either; distilled water, daily 10% (w/v) AG, an intravenous dose of TBX (1600 mg I/kg b.wt) and co-administration of TBX and AG. Rats were sacrificed and blood samples were collected to assess the genotoxicity employing the peripheral blood leucocytes fluorescent double staining; namely the acridine orange/ethidium bromide (AO/EB) staining and alkaline comet assay. Further, chromosomal analyses were done in bone marrow cells. Serum urea and creatinine levels, in addition to malondialdehyde (MDA), nitric oxide (NO), catalase (CAT) and glutathione (GSH) levels in kidney tissues were measured. Liquid chromatography-mass spectrophotometry (LC-MS-MS) was performed to identify the chemical composition of AG extract. Kidney functions, single/double-stranded DNA damage, chromosomal aberrations, mitotic index, MDA and NO levels were significantly (p < 0.001) increased in TBX-treated group compared to the control and AG-treated one. Meanwhile, CAT and GSH activities were significantly diminished and the AG supplementation significantly (p < 0.001) ameliorated these effects compared with the control and AG-treated groups. Five compounds have been identified using GNPS networking including 7,3′,4′-Trihydroxyisoflavone, Noscapine, Tetrahydropapaveroline, Costunolide, Hesperidin. In conclusion, results of the present study suggest that AG exerted a protective role against TBX-induced oxidative stress and genotoxicity which may be attributed to the active metabolites in the gum.

Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and exercise

Chronic metabolic health diseases are increasing worldwide placing strain on healthcare systems and importantly, impacting individuals' quality of life. It is well established that many chronic diseases are associated with inflammation and oxidative stress. Exercise is a known strategy to manage and treat inflammation in animals and humans. Understanding the mechanisms which cause acute and chronic changes to systems via various exercise protocols may provide insights into how we can better clinically manage patients with inflammatory and oxidative stress associated diseases. Nrf2 is a basic leucine transcription factor which regulates the expression of antioxidant proteins to protect against damage caused by electrophilic or oxidative stress. The aim of this narrative review is to provide an overview of the literature which has investigated the relationship between acute and chronic exercise training and Nrf2 protein, mRNA and Nrf2-ARE binding activity. This narrative review presents analysis of twenty-nine articles presenting studies using animals and humans. Findings from animal models suggest that exercise increases all molecular aspects of the Nrf2-ARE pathway in all tissues studied. It was noted that there seems to be an age-related decline in Nrf2 protein upregulation with exercise training. In humans, however, there is a lack of evidence to support this claim.

Exercise Improves Lung Inflammation, but Not Lung Remodeling and Mechanics in a Model of Bleomycin-Induced Lung Fibrosis

Introduction

Moderate aerobic exercise training accelerates the resolution of lung fibrosis in a model of bleomycin-induced pulmonary fibrosis. However, whether it can inhibit the development of lung fibrosis is unknown.

Materials and Methods

C57Bl/6 mice were distributed into four groups: Control (Co), Exercise (Exe), Bleomycin (Bleo), and Bleomycin+Exercise (Bleo+Exe). A single bleomycin dose (1.5 UI/kg) was administered orotracheally and treadmill exercise started in the same day, enduring for 4 weeks, 5x/week, 60 minutes/session, at moderate intensity. Lung mechanics, systemic and pulmonary inflammation, and lung remodeling were evaluated. Lung homogenates were used to evaluate the antioxidant status.

Results

Total cells, macrophages, lymphocytes, and neutrophils numbers, in agreement with IL-6 levels, were higher in the BAL and serum of Bleo group, compared to other groups. In addition, lung levels of LTB4 in Bleo were higher than other groups, whereas SOD activity and nitric oxide levels in exercised groups (Exe and Exe+Bleo) compared to the Bleo group. Lung GPX activity was lower in Bleo and Exe+Bleo groups compared to others. Exe and Exe+Bleo groups also showed higher IL-10 expression by lung macrophages than other groups, whereas TGF-β expression was higher in Exe, Bleo, and Exe+Bleo groups compared to control. CCR7 expression was induced only in the Exe group. However, exercise did not improve lung remodeling and mechanics, or serum and pulmonary levels of VEGF, IGF-1, and TGF-β.

Conclusion

Aerobic exercise training initiated concomitantly with induction of pulmonary fibrosis reduces lung and systemic inflammation but fails to inhibit lung fibrosis and mechanics impairment.

Oxidative Stress and Inflammation Induced by Waterpipe Tobacco Smoking Despite Possible Protective Effects of Exercise Training: A Review of the Literature

The prevalence of waterpipe tobacco smoking (WTS), which is also known as ghalyan, shisha or hookah, is increasing rapidly around the world, especially among youth. Growing interest in this form of tobacco smoking can be traced, in part, to the use of flavored tobacco products, social acceptability as a safer option than cigarettes, and its consideration as a relaxation method or entertainment. However, there is a well-established association between WTS and oxidative stress that causes irreversible chronic pathological conditions such as cardiovascular and respiratory problems, as well as different types of cancers, and thus increases the risk of mortality. Clearly, induction of inflammation status through increased reactive oxygen species (ROS), which in turn leads to oxidative stress and harm to lipids, DNA, and proteins, is the most plausible mechanism to explain the potential harmful effects of WTS. Unlike WTS, well-designed exercise training programs increase ROS to the extent that it is beneficial to the body. In this study, we aimed to review available evidence on the impact of exercise training on oxidative stress and inflammation status. We also summarize the effect of acute and chronic WTS on different exercise capacities.

Aerobic Exercise Attenuates Acute Lung Injury Through NET Inhibition

Introduction: Aerobic exercise improves lung inflammation in acute lung injury (ALI), but its mechanism remains unknown. Neutrophil extracellular traps (NETs) play an important role in LPS-induced ALI, and a positive correlation exists between NET formation and proinflammatory macrophage polarization. This study investigated whether aerobic exercise reduces the pro-inflammatory polarization of alveolar macrophages (AMs) by inhibiting the excessive release of NETs and then alleviating the inflammatory response of ALI. Methods: C57BL/6 male mice were randomly divided into four groups: sedentary group (CON), sedentary and extra-pulmonary LPS injection group (LPS), 5-weeks aerobic training intervention and LPS injection group (EXE+LPS), and DNase I plus LPS injection group (DNase+LPS). Twenty-four hours after drug injection, bronchoalveolar lavage fluid (BALF), AM, and lung tissues were obtained to detect inflammatory responses, NET formation, macrophage polarization, and protein activation. In the in vitro study, a murine AM cell line, designated MH-S, was stimulated with LPS, purified NETs, and NETs plus DNase I. Results: EXE+LPS and DNase+LPS mice exhibited reduced neutrophil infiltration, decreased NET release, and lower pro-inflammatory polarization of AM compared with LPS mice. Subsequently, Western blot showed inhibition of the phosphorylation of MAPK and NF-κB proteins of AMs in EXE+LPS and DNase+LPS mice compared with LPS mice. Lastly, stimulation of MH-S cells by NETs revealed a trend for pro-inflammatory cell polarization, with NF-κB protein activation at 8 h and ERK1/2 activation at 1, 2, and 8 h. Conclusions: Aerobic exercise alleviated ALI through NET-induced AM pro-inflammatory polarization involving ERK1/2 and NF-κB signaling.

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

The use of flavoured tobacco products in waterpipe smoking (WPS) has increased its attractiveness and consumption. Nonetheless, the influence of flavourings on pulmonary toxicity caused by WPS remains unclear. Here, the pulmonary toxicity induced by plain (P)-WPS, apple-flavoured (AF)-WPS, and strawberry-flavoured (SF)-WPS (30 minutes/day, 5 days/week for 1 month) was investigated in mice. Control mice were exposed to air. Exposure to P-WPS or AF-WPS or SF-WPS induced a dose-dependent increase of airway hyperreactivity to methacholine. The histological evaluation of the lungs in all the WPS groups revealed the presence focal areas of dilated alveolar spaces and foci of widening of interalveolar spaces with inflammatory cells. In the lung, the activity of neutrophil elastase and myeloperoxidase and the concentrations of tumor necrosis factor-α and glutathione were increased by the exposure to P-WPS, AF-WPS, or SF-WPS. However, the levels of interleukin-6 and catalase were only increased in the AF-WPS and SF-WPS groups, while nitric oxide activity was only increased in the SF-WPS group. DNA injury was increased in all the WPS groups, but the concentration of cleaved caspase-3 was only elevated in the SF-WPS group. The exposure to either P-WPS or AF-WPS or SF-WPS increased the expression of nuclear factor kappa-B (NF-κB) in the lung. In conclusion, the exposure to P-WPS or AF-WPS or SF-WPS induces alterations in lung function and morphology and causes oxidative stress and inflammation via mechanisms that include activation of NF-κB. Overall, the toxicity of flavoured tobacco WPS, in particular SF-WPS, was found to be greater than that of unflavoured WPS.

Recent advances in our understanding of the mechanisms of lung alveolarization and bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is the most common cause of morbidity and mortality in preterm infants. A key histopathological feature of BPD is stunted late lung development, where the process of alveolarization-the generation of alveolar gas exchange units-is impeded, through mechanisms that remain largely unclear. As such, there is interest in the clarification both of the pathomechanisms at play in affected lungs, and the mechanisms of de novo alveoli generation in healthy, developing lungs. A better understanding of normal and pathological alveolarization might reveal opportunities for improved medical management of affected infants. Furthermore, disturbances to the alveolar architecture are a key histopathological feature of several adult chronic lung diseases, including emphysema and fibrosis, and it is envisaged that knowledge about the mechanisms of alveologenesis might facilitate regeneration of healthy lung parenchyma in affected patients. To this end, recent efforts have interrogated clinical data, developed new-and refined existing-in vivo and in vitro models of BPD, have applied new microscopic and radiographic approaches, and have developed advanced cell-culture approaches, including organoid generation. Advances have also been made in the development of other methodologies, including single-cell analysis, metabolomics, lipidomics, and proteomics, as well as the generation and use of complex mouse genetics tools. The objective of this review is to present advances made in our understanding of the mechanisms of lung alveolarization and BPD over the period 1 January 2017-30 June 2019, a period that spans the 50th anniversary of the original clinical description of BPD in preterm infants.

Testicular Toxicity of Water Pipe Smoke Exposure in Mice and the Effect of Treatment with Nootkatone Thereon

There is a worldwide increase in the popularity of water pipe (shisha) tobacco smoking including in Europe and North America. However, little is known about the effects of water pipe smoke (WPS) exposure on male reproductivity. We have recently demonstrated that WPS exposure in mice induces testicular toxicity including inflammation and oxidative stress. Nootkatone, a sesquiterpenoid found in grapefruit, has antioxidant and anti-inflammatory effects. However, the possible protective effect of nootkatone on WPS-induced testicular toxicity has not been reported before. Here, we tested the effects of treatment of mice with nootkatone on WPS-induced testicular toxicity. Mice were exposed to normal air or WPS (30 minutes/day, for 30 days). Nootkatone (90 mg/kg) was given orally to mice by gavage, 1 h before WPS or air exposure. Nootkatone treatment significantly ameliorated the WPS-induced increase in plasma levels of inhibin, uric acid, and lactate dehydrogenase activity. Nootkatone also significantly mitigated the decrease in testosterone, androgen-binding protein, and estradiol concentrations in the plasma induced by WPS. In testicular homogenates, WPS exposure caused a decrease in the total nitric oxide level and an increase in the proinflammatory cytokine interleukin-1β level and oxidative stress markers including malondialdehyde, cytochrome C, and 8-Oxo-2'-deoxyguanosine. All the latter effects were significantly alleviated by nootkatone treatment. Moreover, in testicular homogenate, nootkatone inhibited the expression of nuclear factor-kappaB induced by WPS. Likewise, histological examination of mouse testes showed that nootkatone treatment ameliorated the deterioration of spermatogenesis induced by WPS exposure. We conclude that nootkatone ameliorated the WPS-induced testicular inflammation and oxidative stress and hormonal and spermatogenesis alterations.

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

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.

Gum Arabic Ameliorates Impaired Coagulation and Cardiotoxicity Induced by Water-Pipe Smoke Exposure in Mice

Water-pipe smoking (WPS) is prevalent in the East and elsewhere. WPS exposure is known to induce thrombosis and cardiovascular toxicity involving inflammation and oxidative stress. Here, we have investigated the effect of Gum Arabic (GA), a prebiotic with anti-oxidant, anti-inflammatory and cytoprotective properties, on WPS exposure (30 min/day for 1 month) on coagulation and cardiac homeostasis, and their possible underlying mechanisms in mice. Animals received either GA in drinking water (15%, w/v) or water only for the entire duration of study. GA significantly mitigated thrombosis in pial microvessels in vivo, platelet aggregation in vitro, and the shortening of prothrombin time induced by WPS exposure. The increase in plasma concentrations of fibrinogen, plasminogen activator inhibitor-1 and markers of lipid peroxidation, 8-isoprostane and malondialdehyde, induced by WPS were significantly reduced by GA administration. Moreover, WPS exposure induced a significant increase in systolic blood pressure and the concentrations of the pro-inflammatory cytokines tumor necrosis factor-α and interleukin 1β in heart homogenates. GA significantly alleviated these effects, and prevented the decrease of reduced glutathione, catalase and total nitric oxide levels in heart homogenates. Immunohistochemical analysis of the hearts showed that WPS exposure increased nuclear factor erythroid-derived 2-like 2 (Nrf2) expressions by cardiac myocytes and endothelial cells, and these effects were potentiated by the combination of GA and WPS. WPS also increased DNA damage and cleaved caspase 3, and GA administration prevented these effects. Our data, obtained in experimental murine model of WPS exposure, show that GA ameliorates WPS-induced coagulation and cardiovascular inflammation, oxidative stress, DNA damage and apoptosis, through a mechanism involving Nrf2 activation.