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Impaired sensitivity to beta 2 integrin-blocking in ICAM-1-mediated neutrophil migration in ulcerative colitis
B Vainer1, J Brimnes, M H Claesson
1Dept. of Medicine M, Division of Gastroenterology, Glostrup Hospital, Nordre Ringvej, DK-2600 Glostrup, Denmark. ben.vainer@dadlnet.dk
Insights
Ulcerative colitis neutrophils show reduced dependence on CD11/ICAM-1 for migration. This study investigated ICAM-1
Area of Science:
- Immunology
- Cell Biology
- Gastroenterology
Background:
- Neutrophil migration into colonic tissue in ulcerative colitis (UC) is not well understood.
- Intercellular Adhesion Molecule-1 (ICAM-1) exhibits chemotactic properties.
- This study investigates the role of beta 2 integrins in ICAM-1-mediated neutrophil migration in UC.
Purpose of the Study:
- To evaluate the involvement of beta 2 integrins in ICAM-1-mediated neutrophil migration.
- To compare ICAM-1-induced neutrophil migration in ulcerative colitis patients and healthy controls.
Main Methods:
- Neutrophils from 13 UC patients and 17 healthy volunteers were isolated.
- Microchemotaxis chambers were used to assess ICAM-1 chemotaxis.
- Beta 2 integrins (CD11a, CD11b, CD11c, CD18) were blocked with antibodies to examine migration.
Main Results:
- ICAM-1 induced a dose-dependent migration in neutrophils from both UC patients and controls, with peak migration at 5 pM ICAM-1.
- Blocking CD11 subunits reduced ICAM-1-mediated migration by 43.6%-58.0% in controls, but only by 20% in UC neutrophils (P < 0.01).
- No quantitative differences in beta 2 integrin expression were observed between UC and control neutrophils.
Conclusions:
- ICAM-1-mediated neutrophil chemotaxis is dependent on CD11 subunits.
- Neutrophils from UC patients exhibit reduced dependence on CD11/ICAM-1 for migration compared to control neutrophils.
Background:
Factors influencing the directed migration of neutrophils into colonic tissue in ulcerative colitis (UC) are poorly described. ICAM-1 has recently been shown to possess chemotactic properties, and the aim of this study was to evaluate the involvement of beta 2 integrins in this ICAM-1-mediated migration.
Methods:
The chemotactic effect of ICAM-1 on neutrophils isolated from 13 UC patients and 17 healthy volunteers was studied in microchemotaxis chambers. Physiological concentrations of ICAM-1 (0.05-500 pM) were separated from neutrophils by nitrocellulose filters, and cell migration was evaluated using the leading front technique. beta 2 integrins on neutrophils were blocked with antibodies to CD11a, CD11b, CD11c and CD18, and migration towards ICAM-1 was examined.
Results:
Migration towards ICAM-1 was equal for UC and control neutrophils, showing a bell-shaped ICAM-1 dosemigratory response curve with peak migration at 5 pM ICAM-1 (30.0 microns; interquartile range 22.9-35.7; P < 0.001). Blockade of the CD11 subunits on control cells inhibited the chemoattractant effect of ICAM-1 by 43.6%-58.0%, whereas the migration was decreased by only 20% in UC under similar blocking conditions (P < 0.01). Anti-CD18 mAbs had no effect. Inhibition of protein kinases with staurosporin only slightly decreased the ICAM-1-mediated migration, whereas incubation with staurosporin and CD11 antibodies showed additive effects on UC neutrophils and synergistic effects on control cells. No quantitative differences in beta 2 integrin expression were detected between control and UC neutrophils.
Conclusions:
The chemotactic property of ICAM-1 was shown to be CD11-dependent and UC neutrophils were found to be less dependent on CD11/ICAM-1-mediated migration than were control neutrophils.