[show abstract][hide abstract] ABSTRACT: Changes in the density of bronchial vessels have been proposed as a part of airway remodeling that occurs in chronic asthma.
Using an established nonhuman primate model of chronic allergic asthma, we evaluated changes in vascular density as well as the contribution of bronchial epithelium to produce vascular endothelial growth factor (VEGF).
Eight juvenile rhesus macaques were divided into two groups of four. One group was exposed to 11 cycles of aerosolized house dust mite allergen (HDMA), whereas the other was exposed to filtered air. Bronchial wall vasculature was identified using an immunohistochemical approach, and vascular density was quantified stereologically. A semiquantitative polymerase chain reaction approach was used to estimate VEGF splice variant gene expression at discrete airway generations. Cell culture of primary tracheal epithelial cells with varying concentrations of HDMA was used to quantify the direct contribution of the epithelium to VEGF production.
Bronchial vascular density was increased at mid- to lower airway generations, which was independent of changes in the interstitial compartment. The VEGF121 splice variant was significantly increased at lower airway generations. VEGF protein increased in a dose-dependant fashion in vitro primarily by an increase in VEGF121 gene expression.
This study highlights that increased vascular density in an animal model of chronic allergic asthma is airway generation specific and associated with a unique increase of VEGF splice variant gene expression. Airway epithelium is the likely source for increased VEGF.
American Journal of Respiratory and Critical Care Medicine 12/2006; 174(10):1069-76. · 11.04 Impact Factor
[show abstract][hide abstract] ABSTRACT: We tested the hypothesis that oxidant-injured cells upregulate thioredoxin, whereas oxidant-stressed, but not injured, cells upregulate interleukin (IL)-8 after injury. We exposed primary human tracheobronchial epithelial cells and transformed human bronchial epithelial cells (BEAS-2B S.6) to 0, 200, 400, or 600 microM H(2)O(2) for 1 h followed by an additional 7 h of incubation. Subsequently, the cells were double-labeled with markers of injury (either Ethidium Homodimer-1 for cellular injury or MitoTracker dye for functional mitochondria) or oxidant stress (5-[and 6]-chloromethyl-2',7'-dicholorodihydrofluorescein diacetate) and antibodies specific for the chemoattractants IL-8 or thioredoxin. We found significant inverse relationships between numbers and stained chemoattractant volumes of IL-8 and thioredoxin-positive cells with increasing H(2)O(2) dose. Cells with mitochondrial injury produced thioredoxin but not IL-8, and oxidant-stressed cells were more likely to produce thioredoxin than IL-8. Isolated human neutrophils were more likely to colocalize with thioredoxin-positive BEAS-2B S.6 cells than thioredoxin-negative cells. The H(2)O(2) injury did not induce significant apoptosis in the BEAS-2B S.6 cells as measured by caspase 3 activation. We conclude that oxidant-injured and stressed airway epithelial cells upregulate thioredoxin, but produce little IL-8, which may be important in airway epithelial cell-mediated multistep navigation of neutrophils to sites of oxidant injury.
American Journal of Respiratory Cell and Molecular Biology 06/2004; 30(5):597-604. · 4.15 Impact Factor
[show abstract][hide abstract] ABSTRACT: Leukocyte recruitment from the circulation into the airways is a multi-step process, involving both chemotactic and adhesive mechanisms. Using an in vitro model of leukocyte transepithelial trafficking, we show that movement of human peripheral blood neutrophils (PMN) across airway epithelium in the optimal basolateral-to-apical surface direction is partially blocked by pertussis toxin, an inhibitor of G(alphai)-protein-linked receptors. A neutralizing monoclonal antibody against interleukin-8 (IL-8; constitutively expressed by airway epithelium) did not inhibit PMN transepithelial migration, suggesting that alternative pertussis toxin-sensitive signaling mechanisms are involved in this process. However, a neutralizing antibody against thioredoxin, a redox enzyme with pertussis toxin-insensitive chemoattractant activity, did reduce PMN migration across airway epithelium. We conclude that trafficking of PMN across airway epithelium is mediated by both thioredoxin- and pertussis toxin-sensitive signaling mechanisms that are independent of IL-8.
Journal of Leukocyte Biology 09/2000; 68(2):201-8. · 4.57 Impact Factor
[show abstract][hide abstract] ABSTRACT: ABSTRACT We tested the hypothesis that oxidant-injured cells upregulate thioredoxin, while oxidant-stressed, but not injured, cells upregulate IL-8 after injury. We exposed primary human,tracheobronchialepithelial cells and transformed human,bronchial epithelial cells (BEAS-2B S.6) to 0, 200, 400, or 600 μM H202for 1 hour followed by an additional 7 hours of incubation. Subsequently, the cells were double labeled with markers of injury (either Ethidium Homodimer-1 for cellular injury or MitoTracker dye for functional mitochondria) or oxidant stress (5-(and 6)-chloromethyl-2’,7’- dicholorodihydrofluorescein diacetate) and antibodies specific for the chemoattractants IL-8 or thioredoxin. We found significant inverse relationships between numbers,and stained chemoattractant volumes of IL-8 and thioredoxin positive cells with increasing H202dose. Cells with mitochondrial injury produced thioredoxin but not IL-8, and oxidant-stressedcells were more likely to produce thioredoxin than IL-8. Isolated