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. 2003 Mar 15;111(6):897–906. doi: 10.1172/JCI14915

Figure 3.

Figure 3

Preserved elastin in CatS–/–LDLR–/– mice. (a) Verhoeff–van Gieson staining for elastin shows aortic arch elastic laminae. The graph shows the number of discontinuities in the elastic lamina enumerated in the 3-mm aortic arch sections. Significant differences in elastin preservation between CatS–/–LDLR–/– and LDLR–/– mice occurred at both the 12-week and 26-week timepoints. (b) Cat S–positive medial SMCs colocalized with sites of elastin degradation in LDLR–/– mice. Serial sections of aortic arches were stained for α-actin (top left) and Cat S (bottom left). Verhoeff–van Gieson staining for elastin performed after Cat S staining showed Cat S expression to be colocalized with elastin fragmentation; arrows indicate elastin breaks (right). (c) SMC elastase assay. IFN-γ–stimulated SMCs from CatS–/– mouse aortas showed significantly weaker elastase activity than was found in wild-type cells (P < 0.0001). Three independent experiments yielded similar observations. (d and e) Reduction of intimal SMCs, collagen content, and fibrous cap thickness in CatS–/–LDLR–/– mice. Longitudinal sections of aortic arch were immunostained for α-actin (SMC content) and for collagen content with picrosirius red. CatS–/–LDLR–/– mice had significantly less SMC and collagen in intima than did LDLR–/– mice. Percentages of positively stained areas were calculated using computer-assisted image quantification as described (27). Values represent mean ± SD, P values ≤ 0.05 were considered significant. (f) The thickness of the fibrous cap of an aortic atheroma of each mouse was measured using sections stained with oil red O as described in Methods. Few if any fibrous caps formed at earlier timepoints.