Resp100_a4 fr fin

APPLICATION NOTE R100
Respiratory:
EOSINOPHIL - ADHESION ASSAY - ASTHMA
To determine novel anti-inflammatory effects of MLK on MLK (10 nM and 100 nM) gave partial (~40%) but significant resting and GM-CSF-stimulated eosinophils using the Cellix (P<0.05) inhibition of unstimulated eosinophil adhesion to VenaFluxTM platform to mimic physiological adhesion to rhVCAM-1 at 2 dyne cm-2 (Figure 1 and Figure 2). GM-CSF- stimulated eosinophil adhesion under flow was characterised by greater cell flattening with significant (P<0.05) inhibition of adherent cell numbers by 100 nM MLK observed (Figure 2). This effect appeared specific for MLK as the analogue MK571 had no significant effect on eosinophil adhesion to VCAM-1 Asthma is one of the most common chronic respiratory (Figure 3). LTC4 released from unstimulated or GM-CSF- diseases in developed countries. For the majority of asthmatics treated eosinophils did not contribute to their adhesion to their symptoms are satisfactorily controlled by the regular use VCAM-1 as the leukotriene biosynthesis inhibitor MK886 had of inhaled glucocorticoids (GC). However, these drugs are not no inhibitory effect (Figure 3) while exogenously added LTC4 without side effects and some asthmatic patients derive only did not enhance eosinophil adhesion (Table 1). In contrast, partial and in some cases no relief of their symptoms even LTD4, enhanced eosinophil adhesion to VCAM-1; an effect when using high doses of GC. Clearly we need more effective blocked by MLK (Table 1). Comparable observations were also made at 1 dyne cm-2 (data not shown).
Eosinophils are key pro-inflammatory cells in the asthmatic lung where their cytotoxic products cause damage to the airway epithelium, tissue inflammation and airflow obstruction. Eosinophil adhesion to and transmigration through theendothelial cells lining the post-capillary venules are key events in their accumulation in the asthmatic lung .
Understanding these mechanisms may lead to the identification of compounds that can blunt eosinophil accumulation.
Activation of the cysteinyl leukotriene cysLT1 receptor (cysLT1R) results in eosinophil migration and damage to the mucus layer in the lung. Montelukast (MLK) is part of a new class of anti-asthma drugs that are antagonists to cysLT1R reducing eosinophil migration. Evidence is accumulatingthat MLK may have additional anti-inflammatory effectson eosinophil function which were further investigated inthis study.
Refer to Application Note R200 for eosinophil isolation and flow assay details. Concentrations of adhesion proteins, mediators and drugs used were rhVCAM-1; 10 µg mL-1, BSA; 10 µg mL-1, GM-CSF; 10 ng mL-, LTC4/D4; 100 nM, MLK; 0.1 nM – 100 nM, MK571; 100 nM, MK886; 100 Figure 1: Representative experiment illustrating unstimulated eosinophil nM, Anti-α4β1; 10 µg ml-1, anti-cysLT1R; 10 µg ml-1, adhesion at 2 dyne cm-2 to rhVCAM-1 together with the inhibitory effects of APPLICATION NOTE R100
Respiratory: EOSINOPHIL - ADHESION ASSAY - ASTHMA
Non-& GM-CSF-Stimulated Eosinophil Adhesion to VCAM-1 at 2 dyne cm-2 * denotes significance (p<0.005), compared to Nil ** denotes significance (p<0.005), compared to LTD4 Table 1: The effect of MLK and an anti-CysLT1R antibody on non-stimulated and LTC4/D4-stimulated eosinophil adhesion to rhVCAM-1 at dyne cm-2. Figure 2: Dose response of the effect of MLK on non-stimulated and GM- CSF-stimulated eosinophil adhesion to rhVCAM-1 under flow conditions of2 dyne cm-2 (n=4, *P<0.05). Physiological y relevant concentrations of MLK inhibited resting and GM-CSF-stimulated eosinophil adhesion to VCAM-1 in an in vitro model of the post-capillary venules. Non-& GM-CSF-Stimulated Eosinophil Adhesion to VCAM-1 at 2 dyne cm-2 Inhibitory effects by MLK appeared independent of cysLT1R Our study confirms a previous report that MLK inhibited transmigration of eosinophils across human umbilical vein endothelial cells under static conditions2.
These findings may provide important clues for developing novel therapy aimed at blunting eosinophil-induced inflammation Robinson A.J., Kashanin D, O’Dowd F, Williams V. and Walsh G.M. (2008) Montelukast inhibition of resting and GM-CSF -stimulated eosinophil adhesion to VCAM-1 under flow conditions appears independent of CysLT1 antagonism Journal of Leukocyte Biology (in press).
2 Virchow Jr., J.C., Faehndrich, S., Nassenstein, C., Bock, S., Matthys, H., & Luttman, W. (2001). Effect of a specific cysteinyl leukotriene receptor antagonist (montelukast) on the transmigration of eosinophils across Figure 3: Effect of MLK, the montelukast an MK571 and the leukotriene human umbilical vein endothelial cells. Clin. Exp. Allergy, 31, 836-844.
biosynthesis inhibitor MK886, on unstimulated or GM-CSF-stimulated eosinophil adhesion to rhVCAM-1. Data expressed as a percentage of non-stimulated eosinophil adhesion at 2 dyne cm-2 (n=4, *P<0.05).
2008 Cellix Limited. All rights reserved.

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