Extrapulmonary manifestations of chronic obstructive pulmonary disease in a mouse model of chronic cigarette smoke exposure

Am J Respir Cell Mol Biol. 2009 Jun;40(6):710-6. doi: 10.1165/rcmb.2008-0312OC. Epub 2008 Nov 6.

Abstract

Cigarette smoking is the most commonly encountered risk factor for chronic obstructive pulmonary disease (COPD), reflected by irreversible airflow limitation, frequently associated with airspace enlargement and pulmonary inflammation. In addition, COPD has systemic consequences, including systemic inflammation, muscle wasting, and loss of muscle oxidative phenotype. However, the role of smoking in the development of these extrapulmonary manifestations remains rather unexplored. Mice were exposed to cigarette smoke or control air for 6 months. Subsequently, emphysema was assessed by morphometry of lung tissue, and blood cytokine and chemokine levels were determined by a multiplex assay. Soleus, plantaris, gastrocnemius, and tibialis muscles were dissected and weighed. Muscle fiber typing was performed based on I, IIA, IIB, and IIX myosin heavy-chain isoform composition. Lungs of the smoke-exposed animals showed pulmonary inflammation and emphysema. Moreover, circulating levels of primarily proinflammatory proteins, especially TNF-alpha, were elevated after smoke exposure. Despite an attenuated body weight gain, only the soleus showed a tendency toward lower muscle weight after smoke exposure. Oxidative fiber type IIA proportion was significantly reduced in the soleus. Muscle oxidative enzyme activity was slightly reduced after smoke exposure, being most prominent for citrate synthase in the soleus and tibialis. In this mouse model, chronic cigarette smoke exposure resulted in systemic features that closely resemble the early signs of the extrapulmonary manifestations observed in patients with COPD.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bronchoalveolar Lavage
  • Chemokines / metabolism
  • Cytokines / metabolism
  • Disease Models, Animal
  • Inflammation
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Myosin Heavy Chains / metabolism
  • Protein Isoforms
  • Pulmonary Disease, Chronic Obstructive / metabolism*
  • Pulmonary Emphysema / metabolism
  • Smoke / adverse effects
  • Smoking

Substances

  • Chemokines
  • Cytokines
  • Protein Isoforms
  • Smoke
  • Myosin Heavy Chains