Abstract 1157: Genetic Loss of N-sulfation of Heparan Sulfate Alters Post-Golgi Trafficking of MCP-1 and Remodeling of the Vessel Wall in Response to Injury
Background: Heparan sulfate proteoglycans act as co-receptors for a number of chemokines that are integral to the process of vascular remodeling in response to injury. Heparan sulfate sulfation plays a critical role in conferring specificity to chemokine binding and activity. Previous data from our laboratory demonstrated that wire injury in femoral artery of wild type mice induced a 20 fold increase at 14 days and 40 fold increase at 28 days in N-deactylase/N-sulfotransferase-1 (NDST1) transcript, an enzyme catalyzing the initial N-sulfation of HS side chains.
Hypothesis: Alterations in heparan sulfate sulfation would disrupt chemokine binding and influence vascular remodeling in the setting of injury. To test our hypothesis we established a genetic mouse model in which NDST1 was deleted in smooth muscle cells using a crelox approach (smMHCcre/eGFP/NDST1flox).
Results: Characterization of this model exhibited a significant decrease in NDST1 mRNA and in the ratio of mono-N-sulfated/unsulfated disaccharides (control 0.45 ± 0.02 vs smMHCcre/eGFP/NDST1flox 0.22 ± 0.02, n = 4, p< 0.05) as assessed by HPLC. The macrovasculature developed normally in these mice. Loss of NDST1 in smooth muscle cells resulted in decreased lesion formation in response to wire injury in femoral artery as assessed by intima/media ratio (control 2.22 ± 0.15 vs smMHCcre/eGFP/NDST1flox 1.61 ± 0.13, n = 5, p < 0.05). Deficiency of NDST1 induced a marked disruption in the temporal and spatial distribution of monocyte chemoattractant protein-1 (MCP-1) in response to injury. MCP-1 is a chemokine that requires heparan sulfate for binding and has been shown to play a critical role in vascular remodeling. In vitro immunofluorescence studies on vascular smooth muscle cells isolated from wild type and smMHCcre/eGFP/NDST1flox mice showed that loss of NDST1 results in altered post-golgi trafficking of MCP-1.
Conclusion: NDST1 insufficiency in vascular smooth muscle cells leads to reduction in neointimal lesion formation and disruption in MCP-1 trafficking in response to injury. These findings provide early genetic evidence that HS sulfation is critical for chemokine distribution in the vessel wall in response to injury.