The long-range goal of this protocol is to more completely understand the risks and the pathophysiology of asthma exacerbations, in order to develop prevention strategies and/or expedite a return to complete control of baseline asthma symptoms.
Theinvestigators and others have shown that airway epithelial cell infection with human rhinovirus (HRV) is a major risk factor for subsequent exacerbation. Additionally, the investigators have shown that the nucleotide receptor, P2X7, is an important host factor in the prevention of exacerbations, and have data to suggest that this may occur at the level of the alveolar macrophage. Alveolar macrophages facilitate the resolution of inflammation in part by generating eicosanoid metabolites of arachidonic acid including prostaglandin E2 (PGE2) and lipoxin A4 (LXA4). Patients with severe asthma have a reduced capacity to generate PGE2 and LXA4 when compared to those with non-severe asthma, despite alveolar macrophage expression of two of the key enzymes involved in their production. These and other data suggest that pro-resolving eicosanoid metabolism is most efficient when airway epithelial cells are in communication with alveolar macrophages, and that these pathways may be defective in patients with severe asthma. Moreover, inoculation experiments with human rhinovirus (HRV) demonstrate that alveolar macrophages express cox-2 during resolution. These and other data have led to the central hypothesis that transcellular generation of PGE2 and lipoxins is regulated by P2X7-induced cox-2 expression in alveolar macrophages, and that this process facilitates resolution of an HRV-triggered exacerbation.
Study Type
OBSERVATIONAL
Enrollment
44
UW Madison
Madison, Wisconsin, United States
Cox2 expression
P2X7 agonist-induced fold stimulation (over the media control) of cox2 expression (assessed by densitometry) in alveolar macrophages primed with conditioned medium from minor group HRV-infected epithelial cells.
Time frame: One day
BzATP-induced PGE2
The amount of BzATP-induced PGE2 in the culture supernatants of alveolar macrophages primed with HRV-infected epithelial conditioned media
Time frame: One day
LXA4 produced by BzATP
The amount of LXA4 produced by BzATP co-treatment of HRV infected of epithelial-macrophage co-cultures.
Time frame: One day
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