Disruption of the 12/15-lipoxygenase gene diminishes atherosclerosis in apo E–deficient mice
Tillmann Cyrus, … , MacRae F. Linton, Colin D. Funk
Tillmann Cyrus, … , MacRae F. Linton, Colin D. Funk
Published June 1, 1999
Citation Information: J Clin Invest. 1999;103(11):1597-1604. https://doi.org/10.1172/JCI5897.
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Article

Disruption of the 12/15-lipoxygenase gene diminishes atherosclerosis in apo E–deficient mice

Abstract

Atherosclerosis may be viewed as an inflammatory disease process that includes early oxidative modification of LDLs, leading to foam cell formation. This “oxidation hypothesis” has gained general acceptance in recent years, and evidence for the role of lipoxygenases in initiation of, or participation in, the oxidative process is accumulating. However, the relative contribution of macrophage-expressed lipoxygenases to atherogenesis in vivo remains unknown. Here, we provide in vivo evidence for the role of 12/15-lipoxygenase in atherogenesis and demonstrate diminished plasma IgG autoantibodies to oxidized LDL epitopes in 12/15-lipoxygenase knockout mice crossbred with atherosclerosis-prone apo E–deficient mice (apo E–/–/L-12LO–/–). In chow-fed 15-week-old apo E–/–/L-12LO–/– mice, the extent of lesions in whole-aorta en face preparations (198 ± 60 μm2) was strongly reduced (P < 0.001, n = 12) when compared with 12/15-lipoxygenase–expressing controls (apo E–/–/L-12LO+/+), which showed areas of lipid deposition (15,700 ± 2,688 μm2) in the lesser curvature of the aortic arch, branch points, and in the abdominal aorta. These results were observed despite cholesterol, triglyceride, and lipoprotein levels that were similar to those in apo E–deficient mice. Evidence for reduced lesion development was observed even at 1 year of age in apo E–/–/L-12LO–/– mice. The combined data indicate a role for 12/15-lipoxygenase in the pathogenesis of atherosclerosis and suggest that inhibition of this enzyme may decrease disease progression.

Authors

Tillmann Cyrus, Joseph L. Witztum, Daniel J. Rader, Rajendra Tangirala, Sergio Fazio, MacRae F. Linton, Colin D. Funk

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12/15-lipoxygenase deficiency results in diminished fatty lesions in apo...
12/15-lipoxygenase deficiency results in diminished fatty lesions in apo E-deficient mice. (a) Representative Sudan IV–stained aortas of an apo E–/–/L-12LO–/– double-knockout mouse (left) and an apo E knockout mouse heterozygous for L-12LO (right). Mice were raised on a normal chow diet and sacrificed at 15 weeks of age (n = 12). Atheromatous plaques have already developed in the lesser curvature of the aortic arch (asterisk), at the ostia of the left common carotid artery, and the left subclavian artery (arrow), as well as in the abdominal aorta between the ostia of the left and right renal artery (double asterisk), whereas the aorta of the double-knockout mouse remains free of any lesion development at this age. (b and c) Atherosclerotic average lesion area in en face preparations (n = 12 per group) (b) and aortic sinus areas (n = 12 for L-12LO+/– and L-12LO–/–; n = 9 for L-12LO+/+) (c) in apo E–/– mice lacking L-12LO–/–, expressing 1 allele of L-12LO (L-12LO+/–), or expressing both alleles (L-12LO+/+). Mice fed a normal chow diet were sacrificed at 15 weeks of age. Values are mean ± SEM. **P < 0.0001 (t test). For comparison between groups in c: *P = 0.015 for L-12LO+/+ vs. L-12LO–/– (Mann-Whitney test), P = 0.10 for L-12LO+/– vs. L-12LO–/– (Mann-Whitney test), and P = 0.60 for L-12LO+/+ vs. L-12LO+/– (t test).