By the en face method, aortic atherosclerosis, expressed as % of total aortic surface area, does not differ between chow-fed Ldlr−/− (open bar) or chow-fed Tlr4−/−Ldlr−/− (grey bar) mice (A). However, in Ldlr−/− mice fed DD, aortic lesion area is significantly reduced in the Tlr4−/− group (black bar) as compared to Tlr4+/+ mice (hatched bar). (n=10–15, **P<0.01 vs DD or chow groups); For DD-fed mice Ldlr−/− (open circles) and Tlr4−/−Ldlr−/− (filled circles), en face atherosclerotic lesion area correlated with plasma total cholesterol level (B).