SR-PSOX at sites predisposed to atherosclerotic lesion formation mediates monocyte-endothelial cell adhesion
2011
Hofnagel, Oliver | Engel, T. (Thomas) | Severs, Nicholas J. | Robenek, Horst | Buers, Insa
OBJECTIVE: : The scavenger receptor SR-PSOX/CXCL16, which is identical to the chemokine CXCL16, is thought to be involved in atherogenesis. However, the presence and function of SR-PSOX/CXCL16 in the endothelium of atherosclerotic arteries has not been substantiated. METHODS AND RESULTS: : In rabbit aorta immunocytochemistry revealed SR-PSOX/CXCL16 primarily in the endothelium at sites predisposed to lesion formation, in the endothelium of early atherosclerotic lesions, and mainly in intimal macrophages of more developed lesions, indicating that SR-PSOX/CXCL16-expression shifts during atherogenesis. In addition to its function as scavenger receptor and chemokine, SR-PSOX mediated the adhesion of THP-1 monocytes to endothelial cells in vitro. Both THP-1 monocytes and endothelial cells express SR-PSOX/CXCL16, and THP-1 monocytes express CXCR6, the specific receptor for SR-PSOX/CXCL16. Anti-SR-PSOX/CXCL16 and anti-CXCR6 antibody block monocyte adhesion, showing that SR-PSOX/CXCL16–CXCR6 interaction mediates monocyte-endothelial cell adhesion. SR-PSOX/CXCL16 expression of endothelial cells is upregulated by pro-inflammatory cytokines, and is reversed by incubation with ciglitazone and lovastatin. CONCLUSIONS: : We suggest that SR-PSOX/CXCL16 may promote the adhesion of monocytes to the endothelium during early atherogenesis and that accumulating cytokines enhance SR-PSOX/CXCL16-mediated adhesion by upregulating SR-PSOX/CXCL16 expression. Manipulation of SR-PSOX/CXCL16 expression with anti-inflammatory agents may be of therapeutic value.
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