Short-Term Cigarette Smoke Exposure Enhances Allergic Airway Inflammation in Mice

Rationale: Epidemiologic studies hint that tobacco smoke contributes to the prevalence and proceeding of exacerbations in asthma. The result of active smoking in adolescents with atopy is poorly understood. Objectives: We bring outed an experimental model to investigate the influence of smoking forward antigen-induced airway inflammation and airway responsiveness in mice that were previously sensitized. Methods: Ovalbumin (OVA)-sensitized BALB/c mice were expos to air or mainstream exhalation (5 days/week) and to phosphate-buffered saline (PBS) or OVA aerosol (3 times/week) for 2 weeks (n = 8 for each group) Results: Airway responsiveness to intravenously injected carbachol was increased (p

Keywords: additive; asthma; cytokines; hyperresponsiveness; severity

Epidemiologic studies indicate that airway pollutants, of that kind as tobacco smoke, contribute to the progressive growth and the increase in the severity of asthma. Active as well as passive smoking is positively associated with asthma severity (1-9) in all senses to cigarette smoke results in more oft-repeated asthma attacks, more asthma symptoms (1) a lower lung function (2) an accelerated decline in lung function (2 3) and higher asthma severity scores (4) Moreover, active cigarette smoking impairs the efficacy of short-term inhaled corticosteroid treatment in steroid-naive patients with asthma (5) and the efficacy of oral corticosteroids in patients with chronic stable asthma (6) The severity of asthma is earnestly correlated with current smoking (7) and a certain studies suggest that there is an increased risk for bronchial asthma in individuals who have smoked for 3 years or more (8) Adolescents who start smoking might thus be at increased risk for the exhibition of asthma. Little is known about the consequence of active smoking in adolescents already sensitized to an allergen. In about epidemiologic studies that assessed the weight of the interaction between smoking and atopy forward asthmalike symptoms (9-11), atopy and smoking were institute to be independent risk factors for the evolution of asthma during adolescence. To understand the inflammatory mechanisms involved in young adults with atopy who start smoking, we bring to maturityed an experimental model. In this original the influence of smoking upon airway inflammation and airway responsiveness in BALB/c mice that were previously sensitized was investigated.

Some of the follows of these studies have been previously reported in the form of an abstract (12)

METHODS

Animals

Male inbred BALB/c mice of about 8 weeks advanced in years were obtained from Harlan CBP (Zeist, the Netherlands).

Immunization

All mice were immunized by means of an intraperitoneal injection of 10 ??g ovalbumin (OVA) adsorbed to 1 mg aluminum hydroxide upon Day O and boosted in succession Day 7.

In Vivo Tobacco exhalation Exposure

Mainstream cigarette smoke position s were performed four times a day, 5 days a week, with five Kentucky concern cigarettes (1R3) per five mice by exposure. Details are provided in the online supplement

OVA exposing and Experimental Protocol

Air or mist exposures took place 5 days a week from Day 14 until Day 24 At Days 14 16 18 21 and 24 (30 minutes after air or vapor exposure) mice were exposed to OVA (1%) (details provided online) or phosphate-buffered saline (PBS) aerosol during 30 minutes (n = 8 in each group)

Assessment of Airway Responsiveness

Airway responsiveness to carbachol was measured 24 hours after the final allergen frontage More details are provided in the online complement Lung resistance, induced by increasing doses of carbachol, was evaluated with a computerized pulmonary mechanics analyzer (Mum lung function recording scheme version 5.0; Mumed Systems Ltd London, UK) The concentration of carbachol causing a 50% increase of baseline resistance was calculated.

Bronchoalveolar Lavage and Lung Digest

Immediately after the assessment of airway responsiveness, bronchoalveolar lavage (BAL) was performed via intratracheal instillation of 1 ml Hank's balanced salt solution (Pasteur, Brussels, Belgium) plus 1% bovine serum albumin for cytokine measurements. Three instillations with 1 ml of Hank's balanced salt solution were performed to garner up cells for total and differential (cytospin analysis) enclosed space counts. The remaining cells and confined apartments from lung digest were analyzed by dint of fluorescence activated cell sorter. (See online correlative for details.)

Measurement of Total and OVA-specific IgE

Blood was drawn from the heart for measurement of total and OVA-specific IgE with ELISA. (See online postscript for details.)

Immunofluorescent Labeling and come Cytometry

Flow cytometry data were acquired onward a FACSVantage SE flow cytometer running CELLQuest 30 software (Becton Dickinson, San Jose CA). FlowJo software (Treestar, San Carlos, CA) was used for data analysis. (See online appendix for details.)

Cytokine and Chemokine Measurements

Measurements have been performed upon supernatant of lavage fluid. Interleukin 5 (IL-5) was measured with a sensitive bioassay with a detection limit at approximately 5 pg/ml as previously described (13) Eotaxin (sensitivity, 3 pg/ml) IFN-?? (sensitivity, 2 pg/ml) thymus- and activation-regulated chemokine (TARC; sensitivity,