Differential endothelial coverage, response to injury and neointimal integration of CX3CR1/smooth muscle-like cells after carotid or femoral arterial injury.

BACKGROUND

Previously, we established the importance of the CX3CL1/CX3CR1 axis in the promotion of myeloid cell differentiation into neointimal smooth muscle-like cells (SMLC).

METHODS

In this study, acute (24 h) endothelial coverage and CX3CL1 expression as well as chronic (2 weeks) vascular remodeling was examined with respect to whether myeloid CX3CR1(+) SMLC number in the neointima differed between carotid and femoral artery wire injury.

RESULTS AND CONCLUSION

Twenty-four hours after injury, CX3CL1 expression was significantly elevated in injured carotid compared to femoral arteries. In mice with CX3CR1 promoter-driven expression of green fluorescent protein, neointima formation was significantly greater (p < 0.05) 2 weeks after injury in femoral versus carotid arteries as determined by the intima/media ratio. Although the percentage of F4/80/CX3CR1(+) cell integration was similar in both models, the carotid lesion had greater proportions of cells coexpressing CX3CR1 and both α-smooth muscle actin and calponin (p < 0.05). Wire injury of carotid arteries was associated with greater CX3CL1 expression in the acute phase followed by greater CX3CR1 coexpressing SMLC content in later lesions as well as less neointima formation than in femoral arteries. This may, in part, explain the variability in lesion composition after carotid versus femoral wire injury.