CCL17 and atherosclerosis: Given the crucial role of the CCL22–CCR4 axis in mediating the Treg suppressive function described above (Rapp et al., 2019), we propose that the CCL22–CCR4 axis plays a dominant role in the prevention of atherosclerosis by promoting Treg function, which may be inhibited by stimulating the CCL17–CCR4 axis.