Hematopoietic Interferon Regulatory Factor 8-Deficiency Accelerates Atherosclerosis in Mice
Objective—Inflammatory leukocyte accumulation drives atherosclerosis. Although monocytes/macrophages and polymorphonuclear neutrophilic leukocytes (PMN) contribute to lesion formation, sequelae of myeloproliferative disease remain to be elucidated.
Methods and Results—We used mice deficient in interferon regulatory factor 8 (IRF8−/−) in hematopoietic cells that develop a chronic myelogenous leukemia-like phenotype. Apolipoprotein E-deficient mice reconstituted with IRF8−/− or IRF8−/− apolipoprotein E-deficient bone marrow displayed an exacerbated atherosclerotic lesion formation compared with controls. The chronic myelogenous leukemia-like phenotype in mice with IRF8−/− bone marrow, reflected by an expansion of PMN in the circulation, was associated with an increased lesional accumulation and apoptosis of PMN, and enlarged necrotic cores. IRF8−/− compared with IRF8+/+ PMN displayed unaffected reactive oxygen species formation and discharge of PMN granule components. In contrast, accumulating in equal numbers at sites of inflammation, IRF8−/− macrophages were defective in efferocytosis, lipid uptake, and interleukin-10 cytokine production. Importantly, depletion of PMN in low-density lipoprotein receptor or apolipoprotein E-deficient mice with IRF8−/− or IRF8−/− apolipoprotein E-deficient bone marrow abrogated increased lesion formation.
Conclusion—These findings indicate that a chronic myelogenous leukemia-like phenotype contributes to accelerated atherosclerosis in mice. Among proatherosclerotic effects of other cell types, this, in part, is linked to an expansion of functionally intact PMN.
- Received August 10, 2011.
- Accepted August 19, 2012.
- © 2012 American Heart Association, Inc.