ANCA induces beta2 integrin and CXC chemokine-dependent neutrophil-endothelial cell interactions that mimic those of highly cytokine-activated endothelium.
Antineutrophil cytoplasm antibodies (ANCA) activate neutrophils to undergo a series of coordinated interactions, leading to transendothelial migration, eventually culminating in vascular destruction. The molecular events underlying neutrophil recruitment in ANCA-associated vasculitis need to be defined to enable effective therapeutic manipulation. A flow-based adhesion assay was used to investigate the role of beta2 integrins (CD11a/CD18 and CD11b/CD18) and chemokine receptors [CXC chemokine receptor (CXCR)1 and CXCR2] in neutrophil migration through the endothelium. Two endothelial models were used: a highly activated model stimulated with 100 U/ml tumor necrosis factor alpha (TNF-alpha) and a minimally activated model stimulated with 2 U/ml TNF-alpha and in which ANCA was present as a secondary neutrophil stimulus. CD11a/CD18, CD11b/CD18, and CXCR2 contributed to adhesion and transendothelial migration in both models. However, when the endothelium was minimally activated with TNF-alpha, CD11b/CD18 played an important role in stabilizing adhesion induced by ANCA immunoglobulin G (IgG). Analysis of beta2 integrins and chemokine receptors demonstrated that ANCA IgG had no effect on expression levels at the neutrophil surface but enabled an active conformational change of CD11b/CD18. Similar molecular mechanisms control neutrophil adhesion and migration through highly or minimally TNF-alpha-activated endothelium. However, the direct ANCA-mediated neutrophil stimulation is needed to drive migration through minimally activated endothelium, and CD11b/CD18 is recruited for greater stability of adhesion during this process and can undergo an activatory, conformational change in response to ANCA IgG.
Division of Medical Sciences, The School of Medicine, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
Judith W
JW
Calderwood
Julie M
JM
Williams
Matthew D
MD
Morgan
Gerard B
GB
Nash
Caroline O S
CO
Savage
D019268:Antibodies, Antineutrophil Cytoplasmic / Q000494:pharmacology*; D018821:CD18 Antigens / Q000378:metabolism*; D002448:Cell Adhesion; D002465:Cell Movement; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000378:metabolism*; D006801:Humans; D009504:Neutrophils / Q000378:metabolism*; D023062:Receptors, Interleukin-8A / Q000378:metabolism*; D023063:Receptors, Interleukin-8B / Q000378:metabolism*
D019268:Antibodies, Antineutrophil Cytoplasmic; D018821:CD18 Antigens; D016207:Cytokines; D023062:Receptors, Interleukin-8A; D023063:Receptors, Interleukin-8B