Atypical chemokine receptor 1 deficiency reduces atherogenesis in ApoE-knockout mice

Abstract

Aims: Atypical chemokine receptor 1 (Ackr1; previously known as the Duffy antigen receptor for chemokines or Darc) is thought to regulate acute inflammatory responses in part by scavenging inflammatory CC and CXC chemokines; however, evidence for a role in chronic inflammation has been lacking. Here we investigated the role of Ackr1 in chronic inflammation, in particular in the setting of atherogenesis, using the apolipoprotein E-deficient (ApoE-/-) mouse model. Methods and results: Ackr1-/-ApoE-/- and Ackr1+/+ApoE-/- littermates were obtained by crossing ApoE-/- mice and Ackr1-/- mice on a C57BL/6J background. Ackr1 +/+ApoE-/-mice fed a Western diet up-regulated Ackr1 expression in the aorta and had markedly increased atherosclerotic lesion size compared with Ackr1-/-ApoE-/- mice. This difference was observed in both the whole aorta and the aortic root in both early and late stages of the model. Ackr1 deficiency did not affect serum cholesterol levels or macrophage, collagen or smooth muscle cell content in atherosclerotic plaques, but significantly reduced the expression of Ccl2 and Cxcl1 in the whole aorta of ApoE-/- mice. In addition, Ackr1 deficiency resulted in a modest decrease in T cell subset frequency and inflammatory mononuclear phagocyte content in aorta and blood in the model. Conclusions: Ackr1 deficiency appears to be protective in the ApoE knockout model of atherogenesis, but it is associated with only modest changes in cytokine and chemokine expression as well as T-cell subset frequency and inflammatory macrophage content.