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Regulation of endothelial production of C-type natriuretic peptide by interaction between endothelial cells and
1Department of Medicine and Clinical Science, Kyoto University Graduate School of Medicine, Japan.
Insights
Endothelial cells produce C-type natriuretic peptide (CNP), regulated by tumor necrosis factor-alpha (TNF alpha). Macrophages significantly increase CNP secretion, suggesting a role in vascular tone and atherosclerosis.
Area of Science:
- Cardiovascular Biology
- Immunology
- Endocrinology
Background:
- C-type natriuretic peptide (CNP) is an endothelium-derived peptide with potential roles in vascular tone and growth.
- Tumor necrosis factor-alpha (TNF alpha) is a key cytokine in inflammatory conditions like septic shock and atherosclerosis.
- The interaction between endothelial cells (EC) and macrophages is crucial in the pathogenesis of atherosclerosis.
Purpose of the Study:
- To investigate the effect of coculturing endothelial cells (EC) with macrophages on endothelial CNP production.
- To elucidate the role of TNF alpha in regulating EC production of CNP.
- To assess the functional significance of EC-derived CNP in vascular smooth muscle cells.
Main Methods:
- Coculture of human monocytic leukemia cell line (THP-1) differentiated into macrophages with human umbilical vein endothelial cells (HUVECs).
- Measurement of CNP secretion and messenger RNA (mRNA) expression.
- Detection of TNF alpha in conditioned media and inhibition studies using anti-TNF alpha antibody.
- Assessment of cyclic guanosine monophosphate (cGMP) production in response to CNP.
Main Results:
- Coculture of EC and THP-1-derived macrophages enhanced CNP secretion by over 10-fold compared to single cultures.
- CNP mRNA expression was upregulated in EC during coculture.
- TNF alpha detected in conditioned medium from cocultures; anti-TNF alpha antibody inhibited CNP secretion.
- CNP significantly elevated cGMP production in vascular smooth muscle cells but not in EC or macrophages.
Conclusions:
- Endothelial CNP production is significantly stimulated by TNF alpha released from macrophages.
- Enhanced endothelial CNP may act as a local mediator of vascular tone and growth via cGMP production in vascular smooth muscle cells.
- These findings suggest a potential role for endothelial CNP in the pathogenesis of atherosclerosis.
Abstract:
We demonstrated endothelial production of C-type natriuretic peptide (CNP), the third member of the natriuretic peptide family, and its regulation by cytokines, including tumor necrosis factor-alpha (TNF alpha). We thus proposed that CNP can control vascular tone and growth as an endothelium-derived relaxing peptide. We also revealed the marked elevation of plasma CNP concentration in patients with septic shock, in which TNF alpha plays a significant part. As the interaction between endothelial cells (EC) and monocytes-macrophages plays a pivotal role in the pathogenesis of atherosclerosis, we investigated the effect of coculture of EC and macrophages on endothelial production of CNP. We used a human monocytic leukemia cell line, THP-1, which differentiates into macrophages when treated with phorbol 12-myristate 13-acetate. The coculture of EC and THP-1-derived macrophages enhanced CNP secretion by more than 10-fold compared with the single culture of EC or the coculture of EC and THP-1 without phorbol 12-myristate 13-acetate treatment. Prevention of direct contact between EC and THP-1-derived macrophages did not attenuate the increase in CNP secretion. Northern blotting revealed the augmentation of CNP messenger RNA expression in EC in the coculture. We detected TNF alpha in the conditioned medium from the coculture of EC and THP-1-derived macrophages. Furthermore, anti-TNF alpha antibody inhibited the stimulation of CNP secretion in the coculture. CNP at a concentration of 1 nM did not stimulate cGMP production in EC or THP-1-derived macrophages, but it elevated cGMP production significantly in vascular smooth muscle cells. These results indicate that endothelial production of CNP is stimulated mainly by TNF alpha released from THP-1-derived macrophages in the coculture. Endothelial CNP at the enhanced level may be one of the vascular mediators to regulate local vascular tone and growth through cGMP production by vascular smooth muscle cells, suggesting the potential significance of endothelial CNP in atherosclerosis.