CCR2 and aortic aneurysm: Pro-inflammatory Ccr2+ macrophages were particularly abundant in aortic aneurysm (59.6% of macrophages), while they were relatively rare in Jak2WT and Jak2V617FMyel with limited aortic dilation (Fig. 4F, G), consistent with our observation of infiltration of Lyve1- macrophages in the media of mutant mice with severe aortic aneurysm (Fig. 3G).