Reduced macrophage apoptosis is associated with accelerated atherosclerosis in low-density lipoprotein receptor-null mice

June Liu, Douglas P. Thewke, Yan Ru Su, MacRae F. Linton, Sergio Fazio, Michael S. Sinensky

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    156 Scopus citations

    Abstract

    Objective - The majority of apoptotic cells in atherosclerotic lesions are macrophages. However, the pathogenic role of macrophage apoptosis in the development of atherosclerosis remains unclear. Elevated expression of Bax, one of the pivotal proapoptotic proteins of the Bcl-2 family, has been found in human atherosclerotic plaques. Activation of Bax also occurs in free cholesterol-loaded and oxysterol-treated mouse macrophages. In this study, we examined the effect of Bax deficiency in bone marrow-derived leukocytes on the development of atherosclerosis in low-density lipoprotein receptor-null (LDLR-/-) mice. Methods and Results - Fourteen 8-week-old male LDLR-/- mice were lethally irradiated and reconstituted with either wild-type (WT) C57BL6 or Bax-null (Bax-/-) bone marrow. Three weeks later, the mice were challenged with a Western diet for 10 weeks. No differences were found in the plasma cholesterol level between the WT and Bax-/- group. However, quantitation of cross sections from proximal aorta revealed a 49.2% increase (P=0.0259) in the mean lesion area of the Bax-/- group compared with the WT group. A 53% decrease in apoptotic macrophages in the Bax-/- group was found by TUNEL staining (P<0.05). Conclusions - The reduction of apoptotic activity in macrophages stimulates atherosclerosis in LDLR-/- mice, which is consistent with the hypothesis that macrophage apoptosis suppresses the development of atherosclerosis.

    Original languageEnglish (US)
    Pages (from-to)174-179
    Number of pages6
    JournalArteriosclerosis, thrombosis, and vascular biology
    Volume25
    Issue number1
    DOIs
    StatePublished - Jan 1 2005

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    Keywords

    • Apoptosis
    • Atherosclerosis
    • Bax
    • Macrophage
    • Smooth muscle cell

    ASJC Scopus subject areas

    • Cardiology and Cardiovascular Medicine

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