Endothelial inflammation: the role of differential expression of N-deacetylase/N-sulphotransferase enzymes in alteration of the immunological properties of heparan sulphate

Abstract

Heparan sulphate N-deacetylase/N-sulphotransferase (NDST) enzymes catalyse the reaction that initiates sulphation and subsequent modification of the oligosaccharide, heparan sulphate (HS). The extent and distribution of sulphate substitution on HS plays a vital role in regulation of the binding of a range of proteins, including IFN-γ, several interleukins and most chemokines. In this study, the expression of NDST transcripts was found to be non-uniform between a range of cell types, suggesting that different cells produce characteristic HS species. It was found that stimulation of the HMEC-1 microvascular endothelial cell line with the pro-inflammatory cytokines IFN-γ and TNF-α caused a transient decrease in the level of NDST-1 and -2 transcripts after 4 hours (P<0.05 and P<0.01 respectively), but the expression of NDST-1 increased above control levels after 16 hours (P<0.01). The change in NDST expression was concurrent with an increase in the abundance of sulphated HS epitopes on the cell surface; this was not caused by variation in the expression of proteoglycans or by changes in the rate of GAG turnover. Cytokine-stimulated endothelial cells also showed an increase in their potential to bind RANTES(CCL5); this was abrogated by chlorate blockade of sulphotransferase activity or by heparitinase cleavage of cell surface HS. Monolayers of cytokine-stimulated HMEC-1 also supported an enhanced leukocyte chemotactic response towards RANTES. This study demonstrated that pro-inflammatory cytokines can increase NDST expression leading to increased sulphation of HS and a corresponding increase in sequestration of functional RANTES at the apical surface of endothelial cells. This may enhance leukocyte extravasation at sites of inflammation.

Induction of a CXCL8 binding site on endothelial syndecan‐3 in rheumatoid synovium

“…One reason for the induction of CXCL8 binding to HSPGs could involve soluble mediators, such as tumor necrosis factor. This cytokine, which is present in the RA joint (54), is known to increase HS sulfation and enhance binding of the chemokine CCL5 to cultured human microvascular endothelial cells (55).…”

Examination of MCP-1 (CCL2) partitioning and presentation during transendothelial leukocyte migration

“…5 Recent work from our group has shown that the availability of chemokine-binding motifs can depend on changes in the expression of sulfotransferase enzymes, such as N-deacetylase/Nsulfotransferase-1. 52 Hence, chemical microheterogeneity within the cell surface heparan sulfate population provides a possible explanation for the focal accumulation of MCP-1.…”

Is human placenta proteoglycan remodeling involved in pre-eclampsia?

“…Thus, we turned our attention to the analysis of GAG fine structure and selected biosynthetic enzymes responsible for this fine structure. The failure of Northern blotting to detect different GAG synthesizing enzymes [31], suggests that the messages encoding these biosynthetic enzymes are either expressed at low levels or are rapidly turned over. RT-PCR has proven to be a powerful method for the sensitive detection of mRNA levels [28,29,30].…”

“…These enzymes are encoded by two genes and afford the first blocks of N-sulfation upon which other enzymes act. Thus, the content of N-sulfo groups profoundly impact subsequent downstream modification of HS by Osulfotransferases [10,31]. NDST-1 mRNA expression increases during pre-eclampsia, a possible sign of inflammation.…”