APOE and atherosclerosis: To this end we investigate plaque progression and vasodilatory function in dyslipidemic and atherosclerosis prone apolipoprotein E knockout (ApoE-/-) mice exposed by intratracheal instillation (i.t.)to three physicochemically different TiO2 particles including nanometer-size coated rutile TiO2 (nTiO2; 20.6 nm), nanometer-size and highly photocatalytic anatase-rich TiO2 (pTiO2; 12 nm), and sub-micrometer-size coated rutile TiO2 (fTiO2; 288 nm).