Introduction:
Evidence suggests that hypertension involves underlying inflammation, however whether atherosclerosis - a chronic inflammatory condition - can cause hypertension is unknown. We tested whether blood pressure (BP) is higher in high-fat fed ApoE-/- vs chow-fed wild-type (WT) mice, and whether advanced atherosclerosis is associated with systemic and end-organ inflammation, oxidative stress and endothelial dysfunction.
Methods:
Male ApoE-/- and WT mice were placed on high fat and chow diets, respectively, from 5-56 weeks. To clarify the effects of ageing alone, aged WT mice were compared to young chow-fed WT mice (8-12 week old). We measured systolic BP, plasma cytokine levels, mRNA expression of inflammatory markers, vascular superoxide and endothelial function.
Results:
There was no difference in BP of aged ApoE-/- (104.2 ± 2.9 mmHg) and age-matched WT mice (113.2 ± 1.3 mmHg) (n=13-18, P>0.05). However, plasma IL-6, TNF-α and IFN-γ were elevated in ApoE-/- by more than 2-fold vs age-matched WT (n=9-10, all P<0.05), as was brain expression of IL-1β, IL-6, TNF-α, IFN-γ, TGFβ1, CCR2, CCL2, CCL7, CCL8, CCL12 and IL-10 (n=9-10, all P<0.05), and aortic expression of IL-6, CCR2, CCL8 and CCL12 (n=6-8, all P<0.05). Ageing, but not atherosclerosis, increased renal expression of IL-1β, IL-6, TNF-α, CCR2, CCL2, CCL7, CCL8, CCL12 and Foxp3, and aortic expression of CCL2, IL-10 and Foxp3 by at least 2-fold (n=6-10, all P<0.05). In ApoE-/- aorta, Nox2-dependent superoxide production was 4-fold greater than in WT (n=5-6, P<0.05), and endothelium-dependent vasorelaxation to carbachol was markedly reduced by more than half (n=5-7, P<0.05). Ageing alone had no effect on BP, systemic inflammation or endothelial function.
Conclusions:
Despite the systemic and end-organ inflammation, oxidative stress and endothelial dysfunction, advanced atherosclerosis does not result in elevated BP.
Rapeseed Protein in a High-Fat Mixed Meal Alleviates Postprandial Systemic and Vascular Oxidative Stress and Prevents Vascular Endothelial Dysfunction in Healthy Rats
