Both transient and continuous corticosterone excess inhibit atherosclerotic plaque formation in APOE*3-leiden.CETP mice

Abstract

Introduction: The role of glucocorticoids in atherosclerosis development is not clearly established. Human studies show a clear association between glucocorticoid excess and cardiovascular disease, whereas most animal models indicate an inhibitory effect of glucocorticoids on atherosclerosis development. These animal models, however, neither reflect long-term glucocorticoid overexposure nor display human-like lipoprotein metabolism.

Aim: To investigate the effects of transient and continuous glucocorticoid excess on atherosclerosis development in a mouse model with human-like lipoprotein metabolism upon feeding a Western-type diet.

Methods: Pair-housed female APOE*3-Leiden.CETP (E3L.CETP) mice fed a Western-type containing 0.1% cholesterol for 20 weeks were given corticosterone (50 µg/ml) for either 5 (transient group) or 17 weeks (continuous group), or vehicle (control group) in the drinking water. At the end of the study, atherosclerosis severity, lesion area in the aortic root, the number of monocytes adhering to the endothelial wall and macrophage content of the plaque were measured.

Results: Corticosterone treatment increased body weight and food intake for the duration of the treatment and increased gonadal and subcutaneous white adipose tissue weight in transient group by +35% and +31%, and in the continuous group by +140% and 110%. Strikingly, both transient and continuous corticosterone treatment decreased total atherosclerotic lesion area by -39% without lowering plasma cholesterol levels. In addition, there was a decrease of -56% in macrophage content of the plaque with continuous corticosterone treatment, and a similar trend was present with the transient treatment.

Conclusion: Increased corticosterone exposure in mice with human-like lipoprotein metabolism has beneficial, long-lasting effects on atherosclerosis, but negatively affects body fat distribution by promoting fat accumulation in the long-term. This indicates that the increased atherosclerosis observed in humans in states of glucocorticoid excess may not be related to cortisol per se, but might be the result of complex indirect effects of cortisol.

Figure 1. Effect of transient and continuous CORT treatment on circadian plasma CORT levels in female E3L.CETP mice at baseline (A), week 5 (B) and week 17 (C), as well as on thymus weight (D) and adrenal weight (E) at week 17 (Control group: white bars, transient group: grey bars and continuous group: black bars).

Data are means ± SEM (n = 17–21), *^{, #} P<0.05, **^{, ##} P<0.01, ^### P<0.0001, *versus control group and ^#transient group.

Figure 2. Effect of transient and continuous CORT treatment on food intake (A), body weight (B) (Control group: white circles, transient group: grey squares and continuous group: black triangles), gonadal fat (C) and subcutaneous fat (D) as % of the body weight, mRNA expression of F4/80 (E), CD68 (F), Tnfα (G) and Il-6 (H) in the gonadal fat (Control group: white bars, transient group: grey bars and continuous group: black bars).

Data are means±SEM (n = 17–21), Anova with Tukey’s post-hoc test, *^{, #} P<0.05, **^{, ##} P<0.01, ***^{, ###} P<0.001, *versus control group and ^#versus transient group.

Figure 3. Effect of transient and continuous CORT treatment on cholesterol distribution over lipoproteins fractioned by FPLC at baseline (A), week 5 (B) and 17 (C) (Control group: white circles, transient group: grey squares and continuous group: black triangles) and on plasma insulin (D), plasma glucose (E), HOMA-IR (F), (Control group: white bars, transient group: grey bars and continuous group: black bars) on week 17.

Data are means ± SEM (n = 17–21), Anova with Tukey’s post-hoc test, **^{, ###} P<0.001, *versus control group and ^#versus transient group.

Figure 4. Effect of transient and continuous CORT treatment on atherosclerosis development: representative HPS-stained pictures of lesions (A), lesion area (B), lesion type as % of the total lesion (C), representative pictures of monocyte/macrophage staining (adhering monocytes shown by arrows) (D), adhering monocytes per segment (E), macrophage content of the plaque (F) and macrophages as % of the lesion area (G).

Serum anti-ox-LDL specific antibodies (H) and serum M-CSF (I) were measured on week 17. (Control group: white bars, transient group: grey bars and continuous group: black bars). Data are means ± SEM (n = 17–21), Anova with Tukey’s post-hoc test, ^*# P<0.05, **P<0.01, *versus control group and ^#versus transient group.