title: The effects of cigarette smoke on airway inflammation in asthma and COPD: therapeutic implications.
abstract: Asthma and COPD are two chronic inflammatory disorders of the airway characterized by airflow limitation. While many similarities exist between these two diseases, they are pathologically distinct due to the involvement of different inflammatory cells; predominantly neutrophils, CD8 lymphocytes in COPD and eosinophils and CD4 lymphocytes in asthma. Cigarette smoking is associated with accelerated decline of lung function, increased mortality, and worsening of symptoms in both asthma and COPD. Furthermore, exposure to cigarette smoke can alter the inflammatory mechanisms in asthma to become similar to that seen in COPD with increasing CD8 cells and neutrophils and may therefore alter the response to therapy. Cigarette smoke exposure has been associated with a poor response to inhaled corticosteroids which are recommended as first line anti-inflammatory medications in asthma and as an add-on therapy in patients with severe COPD with history of exacerbations. While the main proposed mechanism for this altered response is the reduction of the histone deacetylase 2 (HDAC2) enzyme system, other possible mechanisms include the overexpression of GR-β, activation of p38 MAPK pathway and increased production of inflammatory cytokines such as IL-2, 4, 8, TNF-α and NF-Kß. Few clinical trials suggest that leukotriene modifiers may be an alternative to corticosteroids in smokers with asthma but there are currently no drugs which effectively reduce the progression of inflammation in smokers with COPD. However, several HDAC2 enhancers including low dose theophylline and other potential anti-inflammatory therapies including PDE4 inhibitors and p38 MAPK inhibitors are being evaluated.
authors.affiliation: Clinical Sciences, Primary Care Business Unit, Pfizer Inc, Ramsgate Road, Sandwich CT13 9NJ, UK.
authors.forename: Asad
authors.initials: A
authors.lastname: Tamimi
authors.forename: Dzelal
authors.initials: D
authors.lastname: Serdarevic
authors.forename: Nicola A
authors.initials: NA
authors.lastname: Hanania
mesh_terms: D001249:Asthma / Q000188:drug therapy* / Q000276:immunology; D001991:Bronchitis / Q000139:chemically induced; D001993:Bronchodilator Agents / Q000627:therapeutic use; D004351:Drug Resistance; D005541:Forced Expiratory Volume; D005938:Glucocorticoids / Q000627:therapeutic use; D056464:Histone Deacetylase 2 / Q000378:metabolism; D006801:Humans; D020024:Leukotriene Antagonists / Q000627:therapeutic use; D047492:Peroxisome Proliferator-Activated Receptors / Q000819:agonists; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy* / Q000276:immunology; D012907:Smoking / Q000009:adverse effects*
chemical_list: D001993:Bronchodilator Agents; D005938:Glucocorticoids; D020024:Leukotriene Antagonists; D047492:Peroxisome Proliferator-Activated Receptors; C533423:HDAC2 protein, human; D056464:Histone Deacetylase 2