Factor VII activating protease (FSAP) regulates the expression of inflammatory genes in vascular smooth muscle and endothelial cells.

OBJECTIVE

The factor VII activating protease (FSAP) knockout mice have a bigger neointima after vascular injury and a larger infarct volume after stroke. The Marburg I (MI) single nucleotide polymorphism (SNP) in the FSAP-encoding gene is associated with an increased risk of stroke and carotid stenosis in humans. We hypothesize that the regulation of gene expression by FSAP in vascular cells accounts for its vasculo-regulatory properties.

METHODS

Vascular smooth muscle cells (VSMC) and endothelial cells (EC) were stimulated with FSAP and a microarray-based expression analysis was performed. Selected genes were further investigated by qPCR. Receptor- and pathway-inhibitors were used to elucidate the mechanisms involved.

RESULTS

Pathways significantly activated by FSAP include those related to inflammation, apoptosis and cell growth in VSMC and inflammation in EC. The key upregulated genes in VSMC were AREG, PTGS2 and IL6; and in EC these were SELE, VCAM1, and IL8. Secretion of IL6 in VSMC and IL8 in EC was also stimulated by FSAP. Recombinant wild type protease domain of FSAP, but not the MI-isoform, could recapitulate most of these effects. In VSMC, but not EC, gene expression by FSAP was impaired by PAR1 (protease-activated receptor1) receptor antagonists. In VSMC, FSAP-induced expression of AREG and IL6 was blocked by cAMP and MAPK pathway inhibitors indicating that multiple signalling pathways are likely to be involved.

CONCLUSIONS

The stimulation of inflammation- and proliferative/apoptosis-related genes in VSMC and EC provides a comprehensive basis for understanding the role of FSAP in vascular diseases.