Influence of induced hypercholesterolemia on aneurysm enlargement and aortic pathologies. Male WT mice at age of 8 weeks were injected with phosphate-buffered saline (PBS) and immediately fed a high-fat diet (HFD), infected with PCSK9/AAV and immediately fed either normal laboratory chow (PCSK9) or HFD (PCSK9+HFD). Two weeks thereafter, mice underwent transient intra-aortic PPE infusion for AAA induction and continued on their pre-assigned diets. (A) Mean and 95% confidence interval (CI) of serum cholesterol concentrations measured via cholesterol strips (n = 7 mice in PCSK9 and HFD groups and 8 mice in PCSK9+HFD group). (B) Mean and 95% CI of infrarenal aortic luminal diameters prior to and indicated days after, PPE infusion imaged via ultrasonography. (C–E) Median and 95% CI for histological scores for elastin degradation (C), smooth muscle cell (SMC) depletion (D) and macrophage (E). Medial elastin degradation, SMC depletion and macrophage accumulation were graded as I (mild) to IV (severe). (F–I) Mean and 95% CI of CD4+ T cells (F), CD8+ T cells (G), B220+ B cells (H) and CD31+ neovessels (I) per aortic cross-section (ACS). Student’s t-test, ** p < 0.01 compared to PCSK9 and HFD groups (A). Two-way ANOVA followed by Newman–Keuls post hoc test, no difference was noted between the groups (B). Nonparametric Mann–Whitney test indicated no significant difference between two groups, test (B–I).