Differential binding of chemokines to macrophages and neutrophils in the human inflamed synovium.
In chronic inflammatory foci, such as the rheumatoid joint, there is enhanced recruitment of phagocytes from the blood into the tissues. Chemokines are strongly implicated in directing the migration of these cells, although little is known regarding the chemokine receptors that could mediate their chemotaxis into the joint tissue. Therefore the objective of the study was to identify chemokine binding sites on macrophages and neutrophils within the rheumatoid synovium using radiolabeled ligand binding and in situ autoradiography. Specific binding sites for CCL3 (macrophage inflammatory protein-1alpha), CCL5 (RANTES), CCL2 (monocyte chemoattractant protein-1) and CXCL8 (IL-8) were demonstrated on CD68+ macrophages in the subintimal and intimal layers. The number and percentage of intimal cells that bound chemokines were greater in inflamed regions compared to noninflamed regions. The intensity of intimal binding varied between chemokines with the rank order, CCL3 > CCL5 > CCL2 > CXCL8. Neutrophils throughout the synovium bound CXCL8 but did not show any signal for binding CCL2, CCL3 or CCL5. Immunohistochemistry showed that both CXCR1 and CXCR2 are expressed by macrophages and neutrophils in the rheumatoid and nonrheumatoid synovia, suggesting that both of these receptors are responsible for the CXCL8 binding. The chemokine binding sites described on phagocytes may be involved in the migration of these cells into the inflamed joint.
Patterson
Angela M
AM
Leopold Muller Arthritis Research Centre, Centre for Science and Technology in Medicine, Keele University at Robert Jones, Oswestry, Shropshire, UK.
Schmutz
Caroline
C
Davis
Scott
S
Gardner
Lucy
L
Ashton
Brian A
BA
Middleton
Jim
J
D015703:Antigens, CD / Q000032:analysis; D015214:Antigens, Differentiation, Myelomonocytic / Q000032:analysis; D001345:Autoradiography; D001665:Binding Sites; D018932:Chemokine CCL2 / Q000378:metabolism; D054405:Chemokine CCL3; D054407:Chemokine CCL4; D018946:Chemokine CCL5 / Q000378:metabolism; D018925:Chemokines / Q000378:metabolism*; D006801:Humans; D007124:Immunoenzyme Techniques; D016209:Interleukin-8 / Q000378:metabolism; D019402:Macrophage Inflammatory Proteins / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism* / Q000473:pathology; D009504:Neutrophils / Q000378:metabolism* / Q000473:pathology; D011869:Radioligand Assay; D013585:Synovitis / Q000378:metabolism* / Q000473:pathology; D000097382:CD68 Molecule
D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D018932:Chemokine CCL2; D054405:Chemokine CCL3; D054407:Chemokine CCL4; D018946:Chemokine CCL5; D018925:Chemokines; D016209:Interleukin-8; D019402:Macrophage Inflammatory Proteins; C067980:CD68 antigen, human; D000097382:CD68 Molecule