A chemotactic gradient sequestered on endothelial heparan sulfate induces directional intraluminal crawling of neutrophils.
During infection, chemokines sequestered on endothelium induce recruitment of circulating leukocytes into the tissue where they chemotax along chemokine gradients toward the afflicted site. The aim of this in vivo study was to determine whether a chemokine gradient was formed intravascularly and influenced intraluminal neutrophil crawling and transmigration. A chemokine gradient was induced by placing a macrophage inflammatory protein-2 (MIP-2)-containing (CXCL2) gel on the cremaster muscle of anesthetized wild-type mice or heparanase-overexpressing transgenic mice (hpa-tg) with truncated heparan sulfate (HS) side chains. Neutrophil-endothelial interactions were visualized by intravital microscopy and chemokine gradients detected by confocal microscopy. Localized extravascular chemokine release (MIP-2 gel) induced directed neutrophil crawling along a chemotactic gradient immobilized on the endothelium and accelerated their recruitment into the target tissue compared with homogeneous extravascular chemokine concentration (MIP-2 superfusion). Endothelial chemokine sequestration occurred exclusively in venules and was HS-dependent, and neutrophils in hpa-tg mice exhibited random crawling. Despite similar numbers of adherent neutrophils in hpa-tg and wild-type mice, the altered crawling in hpa-tg mice was translated into decreased number of emigrated neutrophils and ultimately decreased the ability to clear bacterial infections. In conclusion, an intravascular chemokine gradient sequestered by endothelial HS effectively directs crawling leukocytes toward transmigration loci close to the infection site.
Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden.
Sara
S
Massena
Gustaf
G
Christoffersson
Elina
E
Hjertström
Eyal
E
Zcharia
Israel
I
Vlodavsky
Nora
N
Ausmees
Charlotte
C
Rolny
Jin-Ping
JP
Li
Mia
M
Phillipson
D000818:Animals; D000073883:CX3C Chemokine Receptor 1; D002465:Cell Movement / Q000187:drug effects*; D054426:Chemokine CXCL2 / Q000378:metabolism*; D002634:Chemotaxis, Leukocyte / Q000187:drug effects; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006497:Heparan Sulfate / Q000494:pharmacology*; D036904:Leukocyte Rolling / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008856:Microscopy, Fluorescence / Q000379:methods; D018715:Microscopy, Video / Q000379:methods; D009132:Muscles / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism; D009504:Neutrophils / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D019707:Receptors, Chemokine / Q000235:genetics / Q000378:metabolism; D013203:Staphylococcal Infections / Q000378:metabolism / Q000382:microbiology / Q000517:prevention & control; D013211:Staphylococcus aureus / Q000187:drug effects / Q000378:metabolism; D000099175:Heparanase
D000073883:CX3C Chemokine Receptor 1; D054426:Chemokine CXCL2; D005966:Glucuronidase; D049452:Green Fluorescent Proteins; D006497:Heparan Sulfate; D019707:Receptors, Chemokine; D000099175:Heparanase; C471885:Cx3cr1 protein, mouse