Kinetics of the development and recovery of the lung from IgE-mediated inflammation: dissociation of pulmonary eosinophilia, lung injury, and eosinophil-active cytokines

Granulocyte macrophage colony-stimulating factor augments ICAM-1 and VCAM-1 activation of eosinophil function

Intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) are members of the immunoglobulin superfamily adhesion molecules on vascular endothelium and important in the development of eosinophil (EOS) accumulation in allergic inflammation. To define the role of these adhesion proteins in EOS inflammation, peripheral blood EOS from allergic donors were incubated in either buffer (control)-, recombinant human (rh)-VCAM-1-, or rh-ICAM-1-coated plates, and the effects of these adhesion proteins on EOS effector functions were determined. VCAM-1 induced spontaneous EOS adhesion whereas EOS adhesion to ICAM-1 required a second signal, such as granulocyte macrophage colony-stimulating factor (GM-CSF). Although only VCAM-1 stimulated EOS superoxide anion (O2-) generation, the addition of GM-CSF (100 pM) to the reactions resulted in a greater and equivalent production of O2- with VCAM-1 and ICAM-1. In the presence of GM-CSF, ICAM-1 and VCAM-1 caused significant release of EOS-derived neurotoxin (EDN). Moreover, only ICAM-1 (no GM-CSF) promoted calcium ionophore A23187 (0.2 microM)-induced EOS leukotriene C4 (LTC4). Enhanced O2- generation, EDN release, and LTC4 generation observed with ICAM-1 and VCAM-1 were significantly inhibited by anti-beta2-integrin antibody. These results suggest that ICAM-1 and VCAM-1 are important in determining the eventual function of airway EOS.

Investigative use of bronchoscopy in asthma

The incorporation of bronchoscopy and bronchoscopic procedures into the investigation of asthma mechanisms, treatment, and in particular, the role of airway inflammation has contributed significantly to the enhanced understanding of this disease. Carefully drafted guidelines have allowed the gradual inclusion of subjects with more severe disease in studies utilizing bronchoscopic investigative tools. Many more questions remained unanswered, including the importance of persistence of airway inflammation in asymptomatic asthma, the specific antiinflammatory effects of new (and old) asthma therapies, the contribution of airway structural changes (subepithelial fibrosis) to nonreversible obstruction, the role of antiinflammatory versus proinflammatory cytokines in the pathogenesis of airway inflammation and the heterogeneity of disease expression in various groups of subjects. We are confident that current and future meticulously designed and executed research studies utilizing bronchoscopic techniques will significantly add to our knowledge of disease mechanisms and lead us to new and improved treatments for asthma.