Deficiency in CCR5 but not CCR1 protects against neointima formation in atherosclerosis-prone mice: involvement of IL-10

The chemokine RANTES has been implicated in neointimal hyperplasia after arterial injury. We analyzed the differential role of the RANTES receptors CCR1 and CCR5 by genetic deletion in apolipoprotein E-deficient mice. Deficiency in CCR5 significantly reduced neointimal area after arterial wire injury, associated with a decrease in macrophages, CD3(+) T lymphocytes, and CCR2(+) cells. In contrast, CCR1 deficiency did not affect neointimal area or cell content. Deletion of CCR5 entailed an up-regulation of the anti-inflammatory cytokine interleukin 10 (IL-10) in neointimal smooth muscle cells, and its antibody blockade reversed effects in CCR5(-/-) mice. Conversely, proinflammatory interferon gamma was increased in the neointima of CCR1(-/-) mice, and its blockade unmasked a reduction in macrophage recruitment. Our data indicate that CCR5 is more crucial than CCR1 for neointimal plaque formation, and that its attenuation in CCR5(-/-) mice is due to an atheroprotective immune response involving IL-10. This harbors important implications for targeting chemokine receptors in vascular remodeling.