Interleukin-8 binds to syndecan-2 on human endothelial cells.

Application of reverse transcription-PCR to total RNA prepared from TNF-alpha (tumour necrosis factor-alpha)-stimulated HUVECs (human umbilical vein endothelial cells) revealed that the syndecan-2 mRNA was up-regulated by this inflammatory stimulus. By immunoprecipitation using an anti-syndecan-2 antibody on TNF-alpha-stimulated HUVEC lysates, inflammation-induced interleukin-8 was found to be an interaction partner of this HS (heparan sulphate) proteoglycan, but not of any other syndecan on these cells. The glycosylated [Syn2(ect)(+HS)] and non-glycosylated [Syn2(ect)(-HS)] forms of Syn2(ect) (the syndecan-2 ectodomain) were purified from a stably transfected human cell line and from a bacterial expression system respectively.

Different affinities of glycosaminoglycan oligosaccharides for monomeric and dimeric interleukin-8: a model for chemokine regulation at inflammatory sites.

The binding of interleukin-8 (IL-8) to heparan sulfate (HS) proteoglycans on the surface of endothelial cells is crucial for the recruitment of neutrophils to an inflammatory site. Fluorescence anisotropy measurements yielded an IL-8 dimerization constant of 120 nM. The binding affinities, obtained by isothermal fluorescence titration, of size-defined heparin and HS oligosaccharides to the chemokine were found to depend on the oligomerization state of IL-8: high affinity was detected for monomeric and low affinity was detected for dimeric IL-8, referring to a self-regulatory mechanism for its chemoattractant effect.