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Neutrophil elastase enhances macrophage production of chemokines in receptor-mediated reaction
K Ishihara1, Y Yamaguchi, K Okabe
1Department of Surgery II, Kumamoto University Medical School, Japan.
Abstract:
Proteases influence various leukocyte effector functions. We investigated the specific binding activity of neutrophil elastase (NE) on rat peritoneal macrophages to stimulate chemokine production in vitro. NE enhanced macrophage production of monocyte chemo-attractant protein-1 (MCP-1) (CC-chemokine) and cytokine-induced neutrophil chemo-attractant (CINC) (CXC-chemokine). However, the serine protease inhibitor, phenylmethylsulfonyl fluoride (PMSF), significantly reduced these chemokine productions by macrophages stimulated with NE. 125I-NE was significantly bound to macrophages, but 125I-NE binding was inhibited by addition of unlabeled NE. In addition, NE significantly stimulated [3H]thymidine incorporation into DNA on 3T3 fibroblasts in a dose-dependent manner. These results suggest that NE stimulates chemokine production by macrophages. This may be a receptor-mediated reaction. Thus, NE not only degrades extra-cellular matrix but also stimulates chemokine production by macrophages.
Insights
Neutrophil elastase (NE) stimulates macrophages to produce chemokines like MCP-1 and CINC. This binding reaction suggests NE has roles beyond matrix degradation, influencing immune cell communication.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Proteases play a role in leukocyte functions.
- Neutrophil elastase (NE) is a protease involved in inflammation.
Purpose of the Study:
- To investigate the binding activity of NE on rat peritoneal macrophages.
- To determine if NE stimulates chemokine production in macrophages.
- To explore the mechanism of NE-induced chemokine production.
Main Methods:
- In vitro stimulation of rat peritoneal macrophages with NE.
- Measurement of chemokine production (MCP-1 and CINC) using ELISA.
- Inhibition studies using phenylmethylsulfonyl fluoride (PMSF).
- Binding assays with radiolabeled NE (125I-NE).
- Assessment of [3H]thymidine incorporation into DNA in 3T3 fibroblasts.
Main Results:
- NE significantly enhanced the production of monocyte chemo-attractant protein-1 (MCP-1) and cytokine-induced neutrophil chemo-attractant (CINC) by macrophages.
- PMSF significantly inhibited NE-stimulated chemokine production.
- 125I-NE showed significant binding to macrophages, which was inhibited by unlabeled NE, suggesting a specific receptor-mediated interaction.
- NE stimulated DNA synthesis in 3T3 fibroblasts in a dose-dependent manner.
Conclusions:
- NE stimulates chemokine production by macrophages, likely through a receptor-mediated mechanism.
- NE's functions extend beyond extracellular matrix degradation to include modulation of immune cell signaling.
- These findings highlight NE as a potential target for therapeutic intervention in inflammatory conditions.