Craig D. Wegner

The role of intercellular adhesion molecule-1 in chronic airway inflammation

We have examined the role of intercellular adhesion molecule‐1 (ICAM‐1) in chronic airway inflammation and airway hyperresponsiveness in a primate model of asthma. Airway cellular composition was assessed by bronchoalveolar lavage (BAL) and airway responsiveness was measured as the bronchoconstrictor response to inhaled methacholine. In animals with chronic airway inflammation (increased BAL eosinophils) and sustained airway hyperresponsiveness, a 7 day dosing scheme with a murine anti‐human ICAM‐1 monoclonal antibody (R6.5, 2 mg/kg/day; i.v.) did not reduce the existing airway inflammation or airway hyperresponsiveness. In contrast, a similar dosing scheme with dexamethasone (0.2 mg/kg/day, i.m.) was found to significantly reduce both the airway eosinophilia and hyperresponsiveness. However, one week after cessation of dexamethasone treatment, the airway inflammation and hyperresponsiveness returned to pre‐treatment levels. In further experiments where animals were first treated with dexamethasone (7 days) followed by a 7 day treatment with R6.5, the reoccurrence of airway inflammation and subsequent increase in airway responsiveness was prevented. We conclude that the efficacy of ICAM‐1 is primarily associated with inhibition of the influx of inflammatory cells into the airways and subsequent reduction in airway responsiveness. These data suggest that in lungs with pre‐existing inflammation the modulation of ICAM‐1 following treatment with glucocorticoids may be a novel and more selective long‐term treatment for control of the chronic airway inflammation and hyperresponsiveness associated with bronchial asthma.

Intercellular adhesion molecule-1 contributes to pulmonary oxygen toxicity in mice: Role of leukocytes revised

In immature or injured lungs, impaired alveolar gas exchange forces the use of elevated levels of inhaled oxygen to maintain life. But, at high concentrations oxygen induces lung injury, edema, and bronchopulmonary dysplasia, probably by stimulating the generation of reactive oxygen radicals and subsequent neutrophil infiltration. In addition to regulating neutrophil diapedesis, intercellular adhesion molecule-1 (ICAM-1) expression is marked on inflamed alveolar epithelium, suggesting a role for ICAM-1 in oxygen-induced, neutrophil-mediated parenchymal damage. To test this, we evaluated the rat anti-mouse ICAM-1 monoclonal antibody YN 1/1.7 in 2 protocols of oxygen-induced toxicity in adult, male Balb-c mice: ≥95% O2 for 84 hr and ≥95% O2 for 60 hr followed by 48 hr at 21% (ambient) O2. YN1/1.7 treatment partially attenuated the neutrophil infiltration, lung damage (lavage lactate dehydrogenase [LDH] activity) and dysfunction (reductions in respiratory system compliance [Crs] and diffusion capacity of the lungs for carbon monoxide [DLco] in the 84 hr exposure protocol. In the milder 60 hr exposure protocol, YN1/1.7 completely blocked the oxygen-induced lung dysfunction (reductions in Crs and DLco). These results confirm the contribution of leukocytes in the pathogenesis of pulmonary oxygen toxicity and indicate that antagonism of ICAM-1 may provide a therapeutic approach to reducing hyperoxic lung injury and dysfunction.

Neutrophils enhance clearance of necrotic epithelial cells in ozone-induced lung injury in rhesus monkeys

To test the hypothesis that neutrophil influx is important for the removal of necrotic airway epithelial cells, rhesus monkeys were treated with a function-blocking monoclonal antibody (MAb) against CD18 followed by exposure to ozone or filtered air. CD18 MAb-treated, ozone-exposed monkeys showed a significant inhibition of neutrophil emigration and an accumulation of necrotic airway epithelial cells. In a subsequent experiment, monkeys were given CD18 MAb or an isotype control immunoglobulin before ozone or filtered-air exposure. Complement 5a was instilled into lobes of the right lung at the end of the exposure. Lavage neutrophils were significantly elevated in the right lobes compared with those in the contralateral left lobes; consequently, there were significantly fewer necrotic cells in the airways of the right lung, whereas large aggregations of necrotic cells were observed in the contralateral airways of the left lung. These data indicate that neutrophil influx in ozone-induced injury in primates is CD18 dependent and that neutrophils contribute to the repair of airway epithelium by removal of injured epithelial cells.

The role of 5-lipoxygenase products in preclinical models of asthma

BACKGROUND The action of 5-lipoxygenase on arachidonic acid generates potent inflammatory mediators that may contribute to the pathophysiology of asthma. METHODS Using the potent and selective 5-lipoxygenase inhibitor BI-L-239, we have examined the role of 5-lipoxygenase products in three animal models of asthma. RESULTS In vitro BI-L-239 inhibited 5-lipoxygenase product generation from human lung mast cells, alveolar macrophages, and peripheral blood leukocytes with a concentration that would provide 50% inhibition values of 28 to 340 nmol/L. A 36-fold selectivity for immunoreactive leukotriene C4 versus immunoreactive prostaglandin D2 inhibition was demonstrated in mast cells. In anesthetized cynomolgus monkeys, inhaled BI-L-239 provided dose-dependent inhibition of the inhaled Ascaris-induced immunoreactive leukotriene C4 release (maximum, 73%; bronchoalveolar lavage [BAL], 20 minutes), late-phase bronchoconstriction (maximum, 41%; +6 to 8 hours), and neutrophil infiltration (maximum, 63%; BAL, +8 hours). In conscious sheep, inhaled BI-L-239 provided dose-dependent inhibition of the inhaled Ascaris-induced late-phase bronchoconstriction (maximum, 66%; +6 to 8 hours) and increase in airway responsiveness (maximum, 82%; carbachol, +24 hours). The acute bronchoconstriction was shortened, and neutrophil infiltration diminished (maximum, 61%; BAL, +8 hours) in this model. Finally in conscious actively sensitized guinea pigs pretreated with pyrilamine and indomethacin, inhaled BI-L-239 attenuated acute bronchoconstriction (maximum, 80%; +5 to 15 minutes), leukocyte infiltration (58%; BAL, +3 days) and increase in airway responsiveness (100%; methacholine, +3 days) induced by three alternate-day ovalbumin inhalations. CONCLUSIONS In conclusion, results in these three animal models indicate that 5-lipoxygenase products may be major contributors to the bronchoconstriction (especially late phase), leukocyte infiltration, and airway hyperresponsiveness that characterize asthma.

Effects of single and multiple inhalations of antigen on airway responsiveness in monkeys

Airway hyperresponsiveness is an important and characteristic feature of asthma. In monkeys, we have reported that antigen (Ag) inhalation induces a prolonged airway eosinophilia, that chronic airway eosinophilia is associated with marked airway hyperresponsiveness, and that chronic Ag inhalations induce airway eosinophilia and hyperresponsiveness. In this study we have determined the effects of acute Ag inhalation(s) on airway responsiveness to obtain a protocol for the study of the mechanisms involved. Anesthetized and intubated adult male cynomolgus monkeys with a naturally occurring sensitivity to Ascaris suum extract were studied. Airway responsiveness (provocative concentration of nebulized and inhaled methacholine that induced a 100% increase in respiratory system resistance [Rrs] [PC100]; twofold decrease regarded as significant) and airway cell composition (bronchoalveolar lavage [BAL]) were determined 1 day before and 20 hours after a single inhalation of Ascaris extract, or 3 days before and 3 days after three alternate-day inhalations of Ascaris extract. The single inhalation of Ag (N = 7) caused an acute increase in Rrs (307% +/- 62%), an increase in BAL leukocytes, and a decrease in PC100 in three animals that was moderate (more than eightfold) in two animals. The mean +/- SE change in log PC100 was only -0.25 +/- 0.24. The multiple inhalations of Ag in the same animals caused acute increases in Rrs (178% +/- 48%, 380% +/- 83%, and 331% +/- 63%, respectively), an increase in BAL granulocytes, and a decrease in PC100 in six of seven animals (mean +/- SE change in log PC100 was -1.36 +/- 0.34) that was moderate in two and severe (more than 80-fold) in three animals.(ABSTRACT TRUNCATED AT 250 WORDS)

The onset and recovery from airway hyperresponsiveness: relationship with inflammatory cell infiltrates and release of cytotoxic granule proteins

Previous studies from our laboratory have demonstrated a temporal relationship between eosinophil influx into the airways and the onset of airway hyperresponsiveness to inhaled methacholine. The purpose of the present study was to extend this observation by evaluating changes in airway cellular composition and measuring the levels of granulocyte‐derived mediators recovered in BAL fluid during the onset and recovery from antigen‐induced airway hyperresponsiveness. Airway cellular composition, airway responsiveness to inhaled methacholine and the levels of BAL fluid EPO and MPO were monitored over a 32 day study in eight adult male Ascaris suum sensitive cynomolgus monkeys. Repeated Ascaris suum inhalation (nine challenges during days 0–21) resulted in a selective, sustained airway eosinophilia that was temporally related with the onset and maintenance of airway hyperresponsiveness (r= 0.67, P < 0.001). The level of BAL eosinophil‐derived EPO was increased and remained elevated concurrent with the increase in airway eosinophils and airway responsiveness. During the recovery phase (days 22–32) the actual number of eosinophils remained elevated, while BAL EPO levels were significantly decreased. The recovery phase was also associated with a transient increase in the number of BAL neutrophils and MPO concentration. We conclude that the number and state of activation of airway eosinophils directly correlate with the onset and maintenance of airway hyperresponsiveness. Recovery from airway hyperresponsiveness is associated with a decrease in eosinophil activation and a transient increase in the number of activated neutrophils.

Preischemic and postischemic administration of AEOL10113 reduces infarct size in a rat model of myocardial ischemia and reperfusion.

Reactive oxygen species (ROS) have been implicated as important mediators of cellular damage during ischemia/reperfusion. AEOL10113 is a low-molecular-weight superoxide dismutase mimetic that has dismutase activity against ROS. The objective of this study was to test the cardioprotective efficacy of postischemic administration of AEOL10113 in a rat model of left ventricular ischemia and reperfusion. Left ventricular infarction was produced by 25 min of left coronary artery occlusion followed by 3 h of reperfusion. Infarct size (IS) is reported as IS/area at risk (AAR). The control group had an IS/AAR of 67.5 ± 2.6%. Postischemic administration of AEOL10113 beginning 5 min prior to reperfusion at doses of 0.03, 0.1, and 0.3 mg/kg resulted in an IS/AAR of 69.3 ± 3.4%, 57.8 ± 3.3% (P < 0.05), and 55.0 ± 2.9% (P < 0.05), respectively. Preischemic administration of AEOL10113 beginning 5 min prior to occlusion at a dose of 0.3 mg/kg resulted in an IS/AAR of 44.2 ± 5.9% (P < 0.0125). AAR as a percentage of the left ventricle and rate-pressure product were unaffected by any dose tested. The data from this study demonstrate that pre- and postischemic administration of AEOL10113 reduces IS in a rat model of myocardial ischemia and reperfusion.

Adhesion molecules in a primate model of allergic asthma: clinical implications for respiratory care

ConclusionPrompted by the realization of the importance of chronic airway inflammation in allergic asthma, recent interest has focused on defining the role of adhesion glycoproteins in the development of airway inflammation and subsequent changes in airway function. Many studies in vitro and in vivo have demonstrated an increased expression of certain adhesion molecules on vascular endothelium, airway epithelium and circulating leukocytes associated with the inflammatory response to allergen. Studies with animal models of allergic asthma have shown the effectiveness of antagonists of adhesion molecules in blocking the development of airway inflammation and changes in airways function. These studies suggest that inhibitors of cellular adhesion molecules may represent a novel form of treatment directed specifically at the chronic airway inflammation characteristic of bronchial asthma.

Immunolocalization of Inhaled Recombinant Human Manganese Superoxide Dismutase Reveals a Prolonged Retention in Lung Surface Lining Fluids

AbstractOxygen-derived radicals play critical roles in many types of lung injuries involving environmental pollutants. Recently, intranasal insufflation of recombinant human manganese superoxide dismutase (rh-MnSOD) was reported to be efficacious against a hyperoxia model of oxidant lung injury in mice. We employed immunocytochemistry to examine the distribution, retention, and location of rh-MnSOD given to mice by intranasal insufflation. Mice were given a single dose (20 mg/kg) of either rh-MnSOD or bovine serum albumin and killed at 0.25, 4, 24, 48, or 120 h after treatment. Lungs were fixed by vascular perfusion. Lung sections from animals in the different time points and treatment groups were labeled with rabbit anti-rh-MnSOD antibody and studied at both light and electron microscopic levels. rh-MnSOD labeling was patchy but widely disseminated at the early time points and mainly localized in surface lining fluids and to a lesser extent on epithelial cell surfaces. The intensity of the labeling dropp...

Effects of single and multiple inhalations of platelet‐activating factor on airway cell composition and responsiveness in monkeys

Platelet‐activating factor (PAF) is a potent pro‐inflammatory mediator that may play a role in the pathogenesis of airway hyper‐responsiveness and asthma. In man, a single inhalation of PAF induces a small but prolonged increase in airway responsiveness in some individuals. The purpose of this study was to determine the effects of single and multiple inhalations of PAF on airway cell composition and responsiveness in monkeys. Anaesthetized and intubated adult male cynomolgus monkeys were studied. Airway cell composition was measured by bronchoalveolar lavage (BAL). Airway responsiveness was measured by determining the concentration (PC100) of inhaled methacholine that caused a 100% increase in respiratory system resistance (Rrs). Airway cell composition (BAL) and responsiveness (PC100) were determined 1 day before and 20 hr after a single inhalation of PAF (∼200 μg) or 3 days before (Day 0) and 3 days after (Day 10) 3‐alternate‐day (Days 3, 5 and 7) inhalations of PAF (each ∼600 μg). The single inhalation of PAF (n= 8) caused an acute increase in Rrs (147±69%), an increase in BAL granulocytes, and a decrease in PC100 in four of eight animals that was moderate (>eight fold) in only one animal. The mean ±s.e. change in log PC100 was −0.29±0.18. The multiple inhalations of PAF (n=8) caused acute increases in Rrs (143±38%, 175±44% and 156±39%, respectively), an increase in BAL granulocytes, and a decrease in PC100 in four of eight animals that was moderate in two animals. The mean±s.e. change in log PC100 was −0.43±0.22. In summary, single and multiple inhalations of PAF in monkeys induce a granulocyte airway infiltration and, in some animals, an increase (usually small) in airway responsiveness.