CD36 modulates migration of mouse and human macrophages in response to oxidized LDL and may contribute to macrophage trapping in the arterial intima
Young Mi Park, … , Maria Febbraio, Roy L. Silverstein
Young Mi Park, … , Maria Febbraio, Roy L. Silverstein
Published December 8, 2008
Citation Information: J Clin Invest. 2009;119(1):136-145. https://doi.org/10.1172/JCI35535.
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Research Article Cardiology

CD36 modulates migration of mouse and human macrophages in response to oxidized LDL and may contribute to macrophage trapping in the arterial intima

Abstract

The trapping of lipid-laden macrophages in the arterial intima is a critical but reversible step in atherogenesis. However, the mechanism by which this occurs is not clearly defined. Here, we tested in mice the hypothesis that CD36, a class B scavenger receptor expressed on macrophages, has a role in this process. Using both in vivo and in vitro migration assays, we found that oxidized LDL (oxLDL), but not native LDL, inhibited migration of WT mouse macrophages but not CD36-deficient cells. We further observed a crucial role for CD36 in modulating the in vitro migratory response of human peripheral blood monocyte–derived macrophages to oxLDL. oxLDL also induced rapid spreading and actin polymerization in CD36-sufficient but not CD36-deficient mouse macrophages in vitro. The underlying mechanism was dependent on oxLDL-mediated CD36 signaling, which resulted in sustained activation of focal adhesion kinase (FAK) and inactivation of Src homology 2–containing phosphotyrosine phosphatase (SHP-2). The latter was due to NADPH oxidase–mediated ROS generation, resulting in oxidative inactivation of critical cysteine residues in the SHP-2–active site. Macrophage migration in the presence of oxLDL was restored by both antioxidants and NADPH oxidase inhibitors, which restored the dynamic activation of FAK. We conclude therefore that CD36 signaling in response to oxLDL alters cytoskeletal dynamics to enhance macrophage spreading, inhibiting migration. This may induce trapping of macrophages in the arterial intima and promote atherosclerosis.

Authors

Young Mi Park, Maria Febbraio, Roy L. Silverstein

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Figure 4

NO2LDL induces phosphorylation of macrophage FAK in a CD36- and Src kinase–dependent manner, and FAK mediates macrophage spreading in response to NO2LDL.

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NO2LDL induces phosphorylation of macrophage FAK in a CD36- and Src kina...
(A) WT and Cd36-null mouse peritoneal macrophages were exposed to 50 μg/ml NO2LDL for the indicated times at 37°C, and then lysates were subjected to Western blot analysis to detect levels of FAK Tyr576/577 phosphorylation using an antibody specific for the phosphorylated form. Immunoblotting with anti-FAK antibody was used for loading control, and fold changes were calculated from scanned images. (B) WT mouse peritoneal macrophages were exposed to NO2LDL or NO2–LDL (50 μg/ml) at 0°C or 37°C and examined as in A. (C) Peritoneal macrophages were preincubated with Src kinase inhibitor 4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP2; 10 μM) or vehicle control along with 50 μg/ml NO2LDL for the indicated times. Cells were then lysed and subjected to immunoblotting to detect FAK Tyr576/577 phosphorylation and Src kinase Tyr416 phosphorylation. (D) Peritoneal macrophages were immunoprecipitated with anti-CD36 antibody or nonimmune IgA, and the precipitates were then analyzed by immunoblot using anti-FAK (top), anti-CD36 (middle), and anti–SHP-2 antibodies (bottom). (E) Comparison of FAK Tyr576/577 phosphorylation kinetics in NO2LDL- (solid line) and TSP-1–treated cells (dashed line).