Deficiency of cathepsin S reduces atherosclerosis in LDL receptor–deficient mice
Galina K. Sukhova, … , Peter Libby, Guo-Ping Shi
Galina K. Sukhova, … , Peter Libby, Guo-Ping Shi
Published March 15, 2003
Citation Information: J Clin Invest. 2003;111(6):897-906. https://doi.org/10.1172/JCI14915.
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Article Vascular biology

Deficiency of cathepsin S reduces atherosclerosis in LDL receptor–deficient mice

Abstract

Human atherosclerotic lesions overexpress the lysosomal cysteine protease cathepsin S (Cat S), one of the most potent mammalian elastases known. In contrast, atheromata have low levels of the endogenous Cat S inhibitor cystatin C compared with normal arteries, suggesting involvement of this protease in atherogenesis. The present study tested this hypothesis directly by crossing Cat S–deficient (CatS–/–) mice with LDL receptor–deficient (LDLR–/–) mice that develop atherosclerosis on a high-cholesterol diet. Compared with LDLR–/– mice, double-knockout mice (CatS–/–LDLR–/–) developed significantly less atherosclerosis, as indicated by plaque size (plaque area and intimal thickening) and stage of development. These mice also had markedly reduced content of intimal macrophages, lipids, smooth muscle cells, collagen, CD4+ T lymphocytes, and levels of IFN-γ. CatS–/–LDLR–/– monocytes showed impaired subendothelial basement membrane transmigration, and aortas from CatS–/–LDLR–/– mice had preserved elastic laminae. These findings establish a pivotal role for Cat S in atherogenesis.

Authors

Galina K. Sukhova, Yaou Zhang, Jie-Hong Pan, Youichiro Wada, Takashi Yamamoto, Makoto Naito, Tatsuhiko Kodama, Sotirios Tsimikas, Joseph L. Witztum, Michael L. Lu, Yasuhiko Sakara, Michael T. Chin, Peter Libby, Guo-Ping Shi

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Figure 3

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Preserved elastin in CatS–/–LDLR–/– mice. (a) Verhoeff–van Gieson staini...
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.