Blockade of keratinocyte-derived chemokine inhibits endothelial recovery and enhances plaque formation after arterial injury in ApoE-deficient mice

Objective - We evaluated the involvement of keratinocyte-derived chemokine ( KC) in neointimal hyperplasia and endothelial repair after arterial injury. Methods and Results - Expression of KC was detected by immunohistochemistry in carotid arteries of apolipoprotein E - deficient (apoE-/-) mice not earlier than 2 weeks after wire-injury. Double immunofluorescence staining revealed a colocalization of KC with Mac-2-positive macrophages. Immunoreactivity for KC and its receptor CXCR2 was detectable in regenerating CD31-positive endothelial cells. Treatment of apoE-/- mice with a blocking monoclonal antibody (mAb) to KC after carotid injury for 3 weeks substantially increased neointimal plaque area compared with isotype control-treated or untreated mice. As assessed by luminal CD31 or VE-cadherin and Evans blue staining, neutralization of KC inhibited endothelial recovery in injured arteries, whereas macrophage and smooth muscle cell content were unaffected. In vitro, treatment with KC mAb, a blocking CXCR2 mAb, or the CXCR2 antagonist (8-73)GRO-alpha delayed KC-mediated endothelial cell chemotaxis and wound repair of endothelial monolayers after scratch injury. Conversely, addition of exogenous KC accelerated wound repair in a CXCR2-dependent manner. Conclusions - Neutralization of KC increased plaque formation and delayed endothelial recovery after arterial injury, without affecting neointimal monocyte infiltration. As an underlying mechanism, KC was involved in promoting CXCR2-mediated endothelial chemotaxis and wound repair.