title: Chronic Exposure to Water-Pipe Smoke Induces Alveolar Enlargement, DNA Damage and Impairment of Lung Function.
abstract: OBJECTIVE
  Epidemiological evidence indicates that water-pipe smoking (WPS) adversely affects the respiratory system. However, the mechanisms underlying its effects are not well understood. Recent experimental studies reported the occurrence of lung inflammation and oxidative stress following acute and subacute exposure to WPS. Here, we wanted to verify the extent of inflammation and oxidative stress in mice chronically-exposed to WPS and to evaluate, for the first time, its effect on alveolar injury and DNA damage and their association with impairment of lung function.
  
  
  METHODS
  Mice were nose-only exposed to mainstream WPS (30 min/day; 5 days/week for 6 consecutive months). Control mice were exposed using the same protocol to atmospheric air only. At the end of the exposure period, several respiratory parameters were assessed.
  
  
  RESULTS
  In bronchoalveolar lavage fluid, WPS increased neutrophil and lymphocyte numbers, lactate dehydrogenase, myeloperoxidase and matrix metallopeptidase 9 activities, as well as several proinflammatory cytokines. In lung tissue, lipid peroxidation, reactive oxygen species, superoxide dismutase activity and reduced glutathione were all increased by WPS exposure. Along with oxidative stress, WPS exposure significantly increased lung DNA damage index. Histologically the lungs of WPS-exposed mice had foci of mixed inflammatory cells infiltration in the interalveolar interstitium which consisted of neutrophils, lymphocytes and macrophages. Interestingly, we found dilated alveolar spaces and alveolar ducts with damaged interalveolar septae, and impairment of lung function following WPS exposure.
  
  
  CONCLUSIONS
  We show the persistence of lung inflammation and oxidative stress in mice chronically-exposed to WPS and demonstrate, for the first time, the occurrence of DNA damage and enlargement of alveolar spaces and ducts associated with impairment of lung function. Our findings provide novel mechanistic elucidation for the long-term effects of WPS on the respiratory system.
authors.affiliation: Department of Physiology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, UAE.
authors.forename: Abderrahim
authors.initials: A
authors.lastname: Nemmar
authors.forename: Suhail
authors.initials: S
authors.lastname: Al-Salam
authors.forename: Priya
authors.initials: P
authors.lastname: Yuvaraju
authors.forename: Sumaya
authors.initials: S
authors.lastname: Beegam
authors.forename: Javed
authors.initials: J
authors.lastname: Yasin
authors.forename: Badreldin H
authors.initials: BH
authors.lastname: Ali
mesh_terms: D000818:Animals; D001992:Bronchoalveolar Lavage Fluid; D049108:Cell Enlargement / Q000187:drug effects; D016207:Cytokines / Q000378:metabolism; D004249:DNA Damage; D005786:Gene Expression Regulation / Q000187:drug effects; D008297:Male; D051379:Mice; D011014:Pneumonia / Q000139:chemically induced* / Q000235:genetics / Q000473:pathology / Q000503:physiopathology*; D011650:Pulmonary Alveoli / Q000187:drug effects* / Q000473:pathology / Q000503:physiopathology; D017382:Reactive Oxygen Species / Q000378:metabolism; D012907:Smoking / Q000009:adverse effects*
chemical_list: D016207:Cytokines; D017382:Reactive Oxygen Species