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Release of chemoattractants for human monocytes from endothelial cells by interaction with neutrophils
P Schratzberger1, S Dunzendorfer, N Reinisch
1Department of Internal Medicine, Medical Faculty, University of Innsbruck, Austria.
Objective:
The release of monocyte chemoattractant protein-1 (MCP-1) in the vessel wall may lead to accumulation of monocytes in the subendothelial space. The role of neutrophils (PMNL) in the initiation of this process is unknown. We tested whether PMNL are able to induce the production and release of MCP-1 in endothelial cells.
Methods:
PMNL were allowed to interact with human umbilical vein endothelial cell (HUVEC) monolayers in culture. Culture media were collected and assessed for chemotactic activity on mononuclear leukocytes (MNC) or purified monocytes in a modified Boyden chamber assay. Additionally, MCP-1 levels in supernatants were quantified by ELISA.
Results:
Media from unstimulated HUVEC culture supernatants induced a slight increase (1.2-fold) of MNC and purified monocyte chemotaxis, which was significantly augmented by addition of PMNL for 1 h (1.4-fold; P < 0.05). The increase in chemotaxis was time- and dose-dependent and could be blocked by an anti-MCP-1 monoclonal antibody. Media obtained after coculture of PMNL and HUVEC for 1-5 h contained increased amounts of MCP-1 as measured by ELISA; addition of cycloheximide abolished this response.
Conclusions:
Interaction of PMNL with endothelium induces the release of functionally active MCP-1 suggesting that in the vascular wall, PMNL may play a role in the recruitment of MNC.
Insights
Neutrophils (PMNL) interacting with endothelial cells induce the release of monocyte chemoattractant protein-1 (MCP-1). This suggests PMNL may initiate monocyte recruitment in the vascular wall.
Area of Science:
- Immunology
- Vascular Biology
- Cell Biology
Background:
- Monocyte chemoattractant protein-1 (MCP-1) release in the vessel wall can cause monocyte accumulation.
- The role of neutrophils (PMNL) in initiating this process is not well understood.
Purpose of the Study:
- To investigate if neutrophils (PMNL) can induce the production and release of MCP-1 in endothelial cells.
Main Methods:
- Human umbilical vein endothelial cells (HUVEC) were cultured with PMNL.
- Culture media were analyzed for chemotactic activity on mononuclear leukocytes (MNC) and monocytes.
- MCP-1 levels were quantified using ELISA.
Main Results:
- PMNL significantly augmented MNC and monocyte chemotaxis induced by HUVEC.
- This effect was dose- and time-dependent and blocked by an anti-MCP-1 antibody.
- Co-culture of PMNL and HUVEC increased MCP-1 levels in supernatants.
Conclusions:
- Endothelial cell interaction with PMNL stimulates the release of active MCP-1.
- PMNL may play a role in recruiting MNC within the vascular wall.