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Updated: May 15, 2026
Isolation of Macrophage Subsets and Stromal Cells from Human and Mouse Myocardial Specimens
Published on: December 17, 2019
Macrophages derived from septic mice modulate nitric oxide synthase and angiogenic mediators in the heart
Eulalia de la Torre1, Eugenia Hovsepian, Federico N Penas
1Centro de Estudios Farmacológicos y Botánicos-CONICET, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.
Abstract:
Macrophages (Mps) can exert the defense against invading pathogens. During sepsis, bacterial lipopolisaccharide (LPS) activates the production of inflammatory mediators by Mps. Nitric oxide synthase (NOS) derived-nitric oxide (NO) is one of them. Besides, Mps may produce pro-angiogenic molecules such as vascular endothelial growth factor-A (VEGF-A) and metalloproteinases (MMPs). The mechanisms involved in the cardiac neovascular response by Mps during sepsis are not completely known. We investigated the ability of LPS-treated Mps from septic mice to modulate the behavior of cardiac cells as producers of NO and angiogenic molecules. In vivo LPS treatment (0.1 mg/mouse) increased NO production more than fourfold and induced de novo NOS2 expression in Mps. Immunoblotting assays also showed an induction in VEGF-A and MMP-9 expression in lysates obtained from LPS-treated Mps, and MMP-9 activity was detected by zymography in cell supernatants. LPS-activated Mps co-cultured with normal heart induced the expression of CD31 and VEGF-A in heart homogenates and increased MMP-9 activity in the supernatants. By immunohistochemistry, we detected new blood vessel formation in hearts cultured with LPS treated Mps. When LPS-stimulated Mps were co-cultured with isolated cardiomyocytes in a transwell assay, the expression of NOS2, VEGF-A and MMP-9 was induced in cardiac cells. In addition, MMP-9 activity was up-regulated in the supernatant of cardiomyocytes. The latter was due to NOS2 induction in Mps from in vivo LPS-treated mice. In conclusion LPS-treated Mps are inducers of inflammatory/angiogenic mediators in cardiac cells, which could be triggering neovascularization, as an attempt to improve cardiac performance in sepsis.
Insights
Lipopolysaccharide (LPS)-activated macrophages induce inflammatory and angiogenic factors in cardiac cells, promoting new blood vessel formation to potentially improve heart function during sepsis.
Area of Science:
- Immunology
- Cardiovascular Biology
- Sepsis Pathophysiology
Background:
- Macrophages play a key role in host defense and inflammation.
- Sepsis involves bacterial lipopolysaccharide (LPS) activating macrophages to produce inflammatory mediators like nitric oxide (NO).
- Macrophages may also produce pro-angiogenic factors, including vascular endothelial growth factor-A (VEGF-A) and matrix metalloproteinases (MMPs), but their role in cardiac neovascularization during sepsis is unclear.
Purpose of the Study:
- To investigate how LPS-treated macrophages from septic mice influence cardiac cells to produce NO and angiogenic molecules.
- To elucidate the mechanisms behind macrophage-mediated cardiac neovascularization in sepsis.
Main Methods:
- In vivo LPS administration to mice.
- Analysis of nitric oxide synthase 2 (NOS2), VEGF-A, and MMP-9 expression and activity in macrophages.
- Co-culture experiments of LPS-treated macrophages with cardiac cells (whole heart and isolated cardiomyocytes).
- Assessment of CD31 expression, VEGF-A, and MMP-9 activity in cardiac tissues and supernatants.
- Immunohistochemistry to detect neovascularization.
Main Results:
- In vivo LPS treatment significantly increased NO production and NOS2 expression in macrophages.
- LPS-activated macrophages showed induced expression of VEGF-A and MMP-9, with detectable MMP-9 activity.
- Co-culture with LPS-activated macrophages induced CD31 and VEGF-A expression and increased MMP-9 activity in cardiac homogenates, leading to new blood vessel formation.
- Co-culture with isolated cardiomyocytes induced NOS2, VEGF-A, and MMP-9 expression in cardiac cells, with up-regulated MMP-9 activity in cardiomyocyte supernatants, driven by NOS2 induction in macrophages.
Conclusions:
- LPS-treated macrophages act as inducers of inflammatory and angiogenic mediators in cardiac cells during sepsis.
- These induced mediators may trigger cardiac neovascularization.
- This process could represent an adaptive response to enhance cardiac performance in sepsis.
