MPO and Atherosclerotic lesion: Interestingly, despite reductions in necrotic core area, changes in macrophage content in the aortic root lesions were not observed (Fig 3), and although there was reduced leukocyte homing to the aorta in early atherosclerotic lesions, MPO inhibition did not alter leukocyte homing to aorta or aortic root plaques in more advanced lesions (Fig 3).