Combined vitamin C and vitamin E deficiency worsens early atherosclerosis in apolipoprotein E-deficient mice

Abstract

Objective: To assess the role of combined deficiencies of vitamins C and E on the earliest stages of atherosclerosis (an inflammatory condition associated with oxidative stress), 4 combinations of vitamin supplementation (low C/low E, low C/high E, high C/low E, and high C/high E) were studied in atherosclerosis-prone apolipoprotein E-deficient mice also unable to synthesize their own vitamin C (gulonolactone oxidase(-/-)); and to evaluate the effect of a more severe depletion of vitamin C alone in a second experiment using gulonolactone oxidase(-/-) mice carrying the hemizygous deletion of SVCT2 (the vitamin C transporter).

Methods and results: After 8 weeks of a high-fat diet (16% lard and 0.2% cholesterol), atherosclerosis developed in the aortic sinus areas of mice in all diet groups. Each vitamin-deficient diet significantly decreased liver and brain contents of the corresponding vitamin. Combined deficiency of both vitamins increased lipid peroxidation, doubled plaque size, and increased plaque macrophage content by 2- to 3-fold in male mice, although only plaque macrophage content was increased in female mice. A more severe deficiency of vitamin C in gulonolactone oxidase(-/-) mice with defective cellular uptake of vitamin C increased both oxidative stress and atherosclerosis in apolipoprotein E(-/-) mice compared with littermates receiving a diet replete in vitamin C, again most clearly in males.

Conclusions: Combined deficiencies of vitamins E and C are required to worsen early atherosclerosis in an apolipoprotein E-deficient mouse model. However, a more severe cellular deficiency of vitamin C alone promotes atherosclerosis when vitamin E is replete.

Figure 1

Liver F₂-isoprostanes (Panel A) and heart malondialdehyde (Panel B) contents of hearts of mice on the various diets. The bar plot shows mean + standard deviation, with the number of mice noted in the bars. Statistical differences are indicated by the small letters above the data, such that treatments with no letters in common were different.

Figure 2

Atherosclerosis in the aortic sinus area of mice on different diet treatments. Panel A shows results in males and Panel B in females. Bar plots show mean + standard deviation, with the number of mice noted in the bars. An asterisk (*) indicates p < 0.05 compared to the LowE/LowC diet.

Figure 3

Aortic sinus atherosclerosis in mice on different intakes of vitamin C. Panel A shows results in males and Panel B in females as mean + standard deviation, with the number of mice noted in the bars. An asterisk (*) indicates p < 0.05 compared to the group with a low vitamin C intake.