Disabled homolog 2 controls macrophage phenotypic polarization and adipose tissue inflammation
Samantha E. Adamson, … , Thurl E. Harris, Norbert Leitinger
Samantha E. Adamson, … , Thurl E. Harris, Norbert Leitinger
Published April 1, 2016; First published February 29, 2016
Citation Information: J Clin Invest. 2016;126(4):1311-1322. https://doi.org/10.1172/JCI79590.
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Research Article Immunology

Disabled homolog 2 controls macrophage phenotypic polarization and adipose tissue inflammation

Abstract

Acute and chronic tissue injury results in the generation of a myriad of environmental cues that macrophages respond to by changing their phenotype and function. This phenotypic regulation is critical for controlling tissue inflammation and resolution. Here, we have identified the adaptor protein disabled homolog 2 (DAB2) as a regulator of phenotypic switching in macrophages. Dab2 expression was upregulated in M2 macrophages and suppressed in M1 macrophages isolated from both mice and humans, and genetic deletion of Dab2 predisposed macrophages to adopt a proinflammatory M1 phenotype. In mice with myeloid cell–specific deletion of Dab2 (Dab2fl/fl Lysm-Cre), treatment with sublethal doses of LPS resulted in increased proinflammatory gene expression and macrophage activation. Moreover, chronic high-fat feeding exacerbated adipose tissue inflammation, M1 polarization of adipose tissue macrophages, and the development of insulin resistance in DAB2-deficient animals compared with controls. Mutational analyses revealed that DAB2 interacts with TNF receptor–associated factor 6 (TRAF6) and attenuates IκB kinase β–dependent (IKKβ-dependent) phosphorylation of Ser536 in the transactivation domain of NF-κB p65. Together, these findings reveal that DAB2 is critical for controlling inflammatory signaling during phenotypic polarization of macrophages and suggest that manipulation of DAB2 expression and function may hold therapeutic potential for the treatment of acute and chronic inflammatory disorders.

Authors

Samantha E. Adamson, Rachael Griffiths, Radim Moravec, Subramanian Senthivinayagam, Garren Montgomery, Wenshu Chen, Jenny Han, Poonam R. Sharma, Garrett R. Mullins, Stacey A. Gorski, Jonathan A. Cooper, Alexandra Kadl, Kyle Enfield, Thomas J. Braciale, Thurl E. Harris, Norbert Leitinger

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Figure 1

Dab2 expression is differentially regulated in M1 and M2 macrophages.

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Dab2 expression is differentially regulated in M1 and M2 macrophages. m...
mRNA expression of total Dab2 and p67 and p96 Dab2 splice variants was determined by qPCR of BMDMs (A) and RAW 264.7 macrophages (B). For A and B, cells were treated with control media (M0), 1 μg/ml LPS and 10 U/ml IFN-γ (M1), or 10 ng/ml IL-4 (M2) for 3 hours. Results were normalized to B2m (encoding β-2-microglobulin) mRNA and are presented as fold change relative to M0. (A and B) Data are representative of 3 independent experiments. *P < 0.0001, by 2-way ANOVA with Dunnett’s multiple comparisons test. (C) Western blot analysis of p96-DAB2 and p67-DAB2 protein in RAW 264.7 macrophages treated for 24 hours with control media, 10 ng/ml IL-4, 10 ng/ml IL-13, 10 ng/ml IL-10, or 5 ng/ml TGF-β. GAPDH was used as a loading control. (D) qPCR analysis of total Dab2 mRNA expression in RAW 264.7 macrophages treated for 3 hours with control media (M0), 10 ng/ml IL-4, 10 ng/ml IL-10, 10 ng/ml IL-13, 10 μM 9-cis-retinoic acid (RA), 5 ng/ml TGF-β, 10 U/ml IFN-γ, 1 μg/ml LPS, or 1 μg/ml LTA. Results are normalized to B2m mRNA and are presented relative to M0. Data were compiled from 2 independent experiments and are presented as the mean ± SEM of quadruplicate treatments. *P < 0.05, by Student’s t test or Mann-Whitney U test. (E) DAB2 was preferentially expressed in M2-like human macrophages that expressed CD163. BAL fluid obtained from critically ill patients was analyzed by flow cytometry for CD14 and the macrophage M2 marker CD163. DAB2 MFI was determined for CD14+CD163– and CD14+CD163+ cells (bar graph shows the mean ± SEM, n = 6). *P < 0.02, by 2-tailed, paired Student’s t test.