Steroid-resistant inflammation in a rat model of chronic obstructive pulmonary disease is associated with a lack of nuclear factor-kappaB pathway activation.
BACKGROUND
Emphysema is one component of chronic obstructive pulmonary disease (COPD), a respiratory disease currently increasing in prevalence worldwide. The mainstay therapy adopted to treat patients with COPD is glucocorticoids; unfortunately, this treatment has limited impact on disease symptoms or underlying airway inflammation.


OBJECTIVE
There is an urgent need to develop therapies that modify both the underlying inflammation, thought to be involved in disease progression, and the structural changes in the emphysematous lung.


METHODS
We have characterized an elastase-driven model of experimental emphysema in the rat that demonstrates COPD-like airway inflammation and determined the impact of a clinically relevant glucocorticoid.


RESULTS
We observed an increase in lung neutrophils, lymphomononuclear cells, mucus production, and inflammatory cytokines. Also present were increases in average air space area, which are associated with emphysema-like changes in lung function, such as increased residual volume and decreased flow; these increases in area were maintained for up to 10 weeks. In addition, we observed that elastase-induced airway neutrophilia is steroid resistant. Interestingly, the inflammation observed after elastase administration was found to be temporally associated with a lack of nuclear factor-kappaB pathway activation. This apparent nuclear factor-kappaB-independent inflammation may explain why treatment with a glucocorticoid was ineffective in this preclinical model and could suggest parallels in the steroid-resistant human disease.


CONCLUSIONS
We believe that this model, in addition to its suitability for testing therapies that may modify existing emphysema, could be useful in the search for new therapies to reduce the steroid-resistant airway inflammation evident in COPD.
Birrell
Mark A
MA
Respiratory Pharmacology Group, Faculty of Medicine, National Heart and Lung Institute, Imperial College, Dovehouse Street, London SW3 6LY, UK.
Wong
Sissie
S
Hele
David J
DJ
McCluskie
Kerryn
K
Hardaker
Elizabeth
E
Belvisi
Maria G
MG
D000465:Algorithms; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology* / Q000627:therapeutic use; D019819:Budesonide / Q000494:pharmacology* / Q000627:therapeutic use; D004195:Disease Models, Animal; D018450:Disease Progression; D004351:Drug Resistance; D004646:Emphysema / Q000378:metabolism; D008297:Male; D016328:NF-kappa B / Q000378:metabolism*; D010196:Pancreatic Elastase; D011014:Pneumonia / Q000139:chemically induced / Q000188:drug therapy / Q000378:metabolism*; D029424:Pulmonary Disease, Chronic Obstructive / Q000139:chemically induced / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction
D000893:Anti-Inflammatory Agents; D016328:NF-kappa B; D019819:Budesonide; D010196:Pancreatic Elastase