title: Montelukast inhibition of resting and GM-CSF-stimulated eosinophil adhesion to VCAM-1 under flow conditions appears independent of cysLT(1)R antagonism.
abstract: Montelukast (MLK) is a cysteinyl leukotriene receptor-1 (cysLT(1)R) antagonist with inhibitory effects on eosinophils, key proinflammatory cells in asthma. We assessed the effect of MLK on resting and GM-CSF-stimulated eosinophil adhesion to recombinant human (rh)VCAM-1 at different flow rates using our novel microflow system. At 1 or 2 dyn cm(-2), shear-stress unstimulated eosinophils tethered immediately to rhVCAM-1, "rolled" along part of the channel until they tethered, or rolled without tethering. At flow rates greater than 2 dyn cm(-2), adherent eosinophils began to be displaced from rhVCAM-1. MLK (10 nM and 100 nM) gave partial ( approximately 40%) but significant (P<0.05) inhibition of unstimulated eosinophil adhesion to rhVCAM-1 at 1 or 2 dyn cm(-2) shear stress. Once adhered, unstimulated eosinophils did not exhibit morphological changes, and GM-CSF-stimulated eosinophil adhesion under flow was characterized by greater cell flattening with significant (P<0.05) inhibition of adherent cell numbers by 100 nM MLK observed. This effect appeared specific for MLK, as the analog (E)-3-[[[3-[2-(7-chloro-2-quinolinyl)ethenyl]phenyl]-[[3-dimethylamino)-3-oxopropyl]thio]methyl]thio]-propanoic acid, sodium salt, had no significant effect on eosinophil adhesion to VCAM-1. The possibility that LTC(4), released from unstimulated or GM-CSF-treated eosinophils, contributed to their adhesion to VCAM-1 was excluded as the LT biosynthesis inhibitor 3-[1-(p-Chlorobenzyl)-5-(isopropyl)-3-t-butylthioindol-2-yl]-2,2-dimethylpropanoic acid had no inhibitory effect, and exogenously added LTC(4) did not enhance eosinophil adhesion. In contrast, LTD(4) enhanced eosinophil adhesion to VCAM-1, an effect blocked by MLK (10 and 100 nM). These findings demonstrate that MLK-mediated inhibition of unstimulated and GM-CSF-stimulated eosinophil adhesion to VCAM-1 under shear-stress conditions appears independent of cysLT(1)R antagonism.
authors.affiliation: School of Medicine, University of Aberdeen, Aberdeen, Scotland, UK.
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Robinson
authors.forename: Dmitry
authors.initials: D
authors.lastname: Kashanin
authors.forename: Frank
authors.initials: F
authors.lastname: O'Dowd
authors.forename: Vivienne
authors.initials: V
authors.lastname: Williams
authors.forename: Garry M
authors.initials: GM
authors.lastname: Walsh
mesh_terms: D000085:Acetates / Q000494:pharmacology*; D002448:Cell Adhesion / Q000187:drug effects; D003521:Cyclopropanes; D004804:Eosinophils / Q000187:drug effects* / Q000502:physiology; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D020024:Leukotriene Antagonists / Q000494:pharmacology*; D008565:Membrane Proteins / Q000037:antagonists & inhibitors* / Q000502:physiology; D011804:Quinolines / Q000494:pharmacology*; D018077:Receptors, Leukotriene / Q000502:physiology; D013440:Sulfides; D019010:Vascular Cell Adhesion Molecule-1 / Q000502:physiology*
chemical_list: D000085:Acetates; D003521:Cyclopropanes; D020024:Leukotriene Antagonists; D008565:Membrane Proteins; D011804:Quinolines; D018077:Receptors, Leukotriene; D013440:Sulfides; D019010:Vascular Cell Adhesion Molecule-1; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; C083169:leukotriene D4 receptor; C093875:montelukast