Modest effect on plaque progression and vasodilatory function in atherosclerosis-prone mice exposed to nanosized...

There is growing evidence that exposure to small size particulate matter increases the risk of developing cardiovascular disease.

We investigated plaque progression and vasodilatory function in apolipoprotein E knockout (ApoE(-/-)) mice exposed to TiO(2). ApoE(-/-) mice were intratracheally instilled (0.5 mg/kg bodyweight) with rutile fine TiO2 (fTiO2, 288 nm), photocatalytic 92/8 anatase/rutile TiO(2) (pTiO(2), 12 nm), or rutile nano TiO(2) (nTiO(2), 21.6 nm) at 26 and 2 hours before measurement of vasodilatory function in aorta segments mounted in myographs. The progression of atherosclerotic plaques in aorta was assessed in mice exposed to nanosized TiO(2) (0.5 mg/kg bodyweight) once a week for 4 weeks. We measured mRNA levels of Mcp-1, Mip-2, Vcam-1, Icam-1 and Vegf in lung tissue to assess pulmonary inflammation and vascular function. TiO(2)-induced alterations in nitric oxide (NO) production were assessed in human umbilical vein endothelial cells (HUVECs).

The exposure to nTiO(2) was associated with a modest increase in plaque progression in aorta, whereas there were unaltered vasodilatory function and expression levels of Mcp-1, Mip-2, Vcam-1, Icam-1 and Vegf in lung tissue. The ApoE(-/-) mice exposed to fine and photocatalytic TiO(2) had unaltered vasodilatory function and lung tissue inflammatory gene expression. The unaltered NO-dependent vasodilatory function was supported by observations in HUVECs where the NO production was only increased by exposure to nTiO(2).

Repeated exposure to nanosized TiO(2) particles was associated with modest plaque progression in ApoE(-/-) mice. There were no associations between the pulmonary TiO(2) exposure and inflammation or vasodilatory dysfunction.