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Updated: Jun 26, 2026
Quantification of Atherosclerosis in Mice
Published on: June 12, 2019
G2A deficiency in mice promotes macrophage activation and atherosclerosis
David T Bolick1, Marcus D Skaflen, Laura E Johnson
1Cardiovascular Research Center, University of Charlottesville, Charlottesville, Virginia 22908, USA.
Abstract:
G2A is a stress-inducible G protein-coupled receptor that is expressed on several cell types within atherosclerotic lesions. We demonstrated previously that G2A deficiency in mice increased aortic monocyte recruitment and increased monocyte:endothelial interactions. To investigate the impact of G2A deficiency in macrophages, we isolated peritoneal macrophages from G2A(+/+)ApoE(-/-) and G2A(-/-)ApoE(-/-) mice. G2A(-/-)ApoE(-/-) macrophages had significantly lower apoptosis than control macrophages. The prosurvival genes BCL-2, BCL-xL, and cFLIP were increased in G2A(-/-)ApoE(-/-) macrophages. Macrophages from G2A(-/-)ApoE(-/-) mice also had increased proinflammatory status that was indicative of a M1 macrophage phenotype. This was indicated by significantly increased nuclear translocation of nuclear factor kappaB, as well as production of interleukin-12p40, tumor necrosis factor alpha, and interleukin-6, and reduced expression of arginase-I. Moreover, G2A(-/-)ApoE(-/-) macrophages had reduced ability to engulf apoptotic cells in vitro. We examined atherosclerosis in mice fed a Western diet for 10 weeks and found that G2A deficiency increased lesion size in the aortic root by 50%. Plasma lipid levels were not changed in G2A(-/-)ApoE(-/-) mice. However, we found that absence of G2A increased the number of aortic macrophages and attenuated apoptosis in this cell type. Moreover, bone marrow transplantation studies indicated that deficiency of G2A in marrow-derived cells significantly contributed to atherosclerosis development. In the absence of G2A, increased macrophage activation and decreased apoptosis is associated with accumulation of macrophages in the aorta and increased atherosclerosis.
Insights
G2A deficiency in mice leads to increased macrophage activation and reduced apoptosis, promoting atherosclerosis development. This study highlights G2A
Area of Science:
- Immunology
- Cardiovascular Biology
- Cell Biology
Background:
- G protein-coupled receptor G2A is stress-inducible and present in atherosclerotic lesions.
- Previous studies showed G2A deficiency increases monocyte recruitment and interactions in mouse aortas.
Purpose of the Study:
- To investigate the specific impact of G2A deficiency on macrophage function and atherosclerosis.
- To determine if G2A-deficient macrophages exhibit altered apoptosis, inflammatory status, and phagocytic capacity.
Main Methods:
- Isolated peritoneal macrophages from G2A(+/+)ApoE(-/-) and G2A(-/-)ApoE(-/-) mice.
- Assessed macrophage apoptosis, gene expression (BCL-2, BCL-xL, cFLIP, arginase-I), nuclear factor-kappaB translocation, and cytokine production (IL-12p40, TNF-alpha, IL-6).
- Evaluated macrophage efferocytosis in vitro and analyzed atherosclerosis progression in mice fed a Western diet, including bone marrow transplantation studies.
Main Results:
- G2A(-/-)ApoE(-/-) macrophages exhibited significantly reduced apoptosis, with increased prosurvival gene expression.
- These macrophages displayed an M1-like proinflammatory phenotype, characterized by increased NF-kappaB activation and pro-inflammatory cytokine production.
- G2A deficiency impaired macrophage efferocytosis and led to a 50% increase in aortic root lesion size in mice, without altering plasma lipid levels.
Conclusions:
- G2A deficiency in macrophages promotes a pro-atherosclerotic phenotype by increasing inflammation and inhibiting apoptosis.
- The absence of G2A leads to macrophage accumulation in the aorta, significantly contributing to atherosclerosis development.
- Targeting G2A may offer a therapeutic strategy for managing atherosclerosis by modulating macrophage behavior.
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