Eosinophil vla-4 binding to fibronectin causes augmented narrowing
of human bronchial explants through 5-lipoxygenase activation.
Munoz, Nilda M., Klaus F. Rabe, Scott P. Neeley, Anja Herrnreiter,
Xiangdong Zhu, Kyron McAllister, Diane Mayer, Helgo Magnussen,
Stephen Galens, and Alan R. Leff.
Sections of Pulmonary and Critical Care Medicine, Department of
Medicine, Department of Pharmacological and Physiological Sciences,
and the Committees on Clinical Pharmacology and Cell Physiology,
Division of the Biological Sciences, The University of Chicago,
Chicago, IL 60637 and the Krankenhaus Gro[beta]hansdorf, Zentrum
f[umlaut]ur Pneumologie und Thoraxchirurgie, LVA Hamburg,
W[diaeresis]ohrendamm 80, D-22927 Gro[beta]hansdorf, Germany
APStracts 2:0203L, 1995.
We examined the effect of ligation of human eosinophils activated by
platelet activating factor (PAF) to soluble human fibronectin (FN) on
the augmented contractile response of human bronchial explants.
Styrene microplate wells were FN-coated and eosinophils were allowed
to adhere in the presence of: a) buffer control, b) 20 [mu]g/ml
monoclonal antibody (HP2/1) to the a4[beta]1 ligand (VLA-4) on the
eosinophils, c) 20 [mu]g/ml anti-CD18, R15.7, d) 20 [mu]g/ml anti
-CD16, 3G8 or e) 10-6 M A63162, a 5-lipoxygenase inhibitor. Sixty min
later, treated cells were activated with either buffer or 10-6 M PAF.
Airway lumenal diameter was assessed by computerized videomicrometry
as a function of pixel number, and activation of eosinophils was
confirmed by measurement of LTC4 secretion. Ligation with FN caused
an increase in PAF-stimulated LTC4 secretion from 276 +/- 75.6 pg/106
cell at baseline to 606 +/- 90.2 pg/106 cell (P < 0.01). This
corresponded to augmented lumenal narrowing of human bronchial
explants from 25.3 +/- 9.39% (PAF activation alone) to 42.9 +/- 8.0%
(PAF-activated eosinophils + FN) (P < 0.01). Both augmented
airway lumenal narrowing and increased LTC4 secretion caused by PAF
-activated cells after FN-ligation were blocked completely by anti
-VLA-4 mAb (P < 0.05 vs control). Pretreatment with 10-6 M A63162
inhibited completely the PAF-stimulated LTC4 secretion to baseline
level (P < 0.001). Inhibition of 5-lipoxygenase similarly
blocked lumenal narrowing caused by eosinophils stimulated by PAF by
> 95% (P < 0.001).We demonstrate that the binding of human
eosinophils to the matrix protein, FN, causes augmented secretion of
LTC4 which, in turn, causes augmented lumenal narrowing of explanted
human bronchi in vitro. We also demonstrate that the augmented
activity is blocked selectively by pretreatment with specific mAb
against VLA-4 and blockade of eosinophil 5-lipoxygenase inhibits both
LTC4 secretion and airway narrowing after PAF stimulation.
Received 20 March 1995; accepted in final form 19 October 1995.
APS Manuscript Number L87-5.
Article publication pending Am. J. Physiol. (Lung Cell. Mol.
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 November 95