We show that LPS from EC across the arterial wall and localizes in the atherosclerotic plaque but do not provide a direct evidence that LPS binds to TLR4 and activates macrophages in situ; however, our data provide a rationale to assess if lowering serum levels of EC-LPS from gut microbiota may be implicated in atherosclerosis progression. Here, TLR4 is linked to atherosclerosis.