Collagen inhibitory peptide R1R2 mediates vascular remodeling by decreasing inflammation and smooth muscle cell activation.

The extracellular matrix (ECM) is a major constituent of the vessel wall. In addition to providing a structural scaffold, the ECM controls numerous cellular functions in both physiologic and pathologic settings. Vascular remodeling occurs after injury and is characterized by endothelial cell activation, inflammatory cell infiltration, phenotypic modulation of smooth muscle cells (SMCs), and augmented deposition of collagen-rich ECM. R1R2, a peptide derived from the bacterial adhesin SFS, with sequence homology to collagen, is known to inhibit collagen type I deposition in vitro by inhibiting the binding of fibronectin to collagen. However, the inhibitory effects of R1R2 during vascular remodeling have not been explored. We periadventitially delivered R1R2 to carotid arteries using pluronic gel in a vascular remodeling mouse model induced by blood flow cessation, and evaluated its effects on intima-media thickening, ECM deposition, SMC activation, and inflammatory cell infiltration. Morphometric analysis demonstrated that R1R2 reduced intima-media thickening compared to the control groups. R1R2 treatment also decreased collagen type I deposition in the vessel wall, and maintained SMC in the contractile phenotype. Interestingly, R1R2 dramatically reduced inflammatory cell infiltration into the vessel by ∼ 78%. This decrease was accompanied by decreased VCAM-1 and ICAM-1 expression. Our in vitro studies revealed that R1R2 attenuated SMC proliferation and migration, and also decreased monocyte adhesion and transendothelial migration through endothelial cells. Together, these data suggest that R1R2 attenuates vascular remodeling responses by decreasing inflammation and by modulating SMC proliferation and migration, and suggest that the R1R2 peptide may have therapeutic potential in treating occlusive vascular diseases.