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A peptide derived from neutrophil inhibitory factor (NIF) blocks neutrophil adherence to endothelial cells
Objective And Design:
Peptides derived from neutrophil inhibitory factor (NIF), a known antagonist of Mac-1, were evaluated as inhibitors of neutrophil adherence.
Material:
In vitro assays of adherence employed: 1) human polymorphonuclear cells (PMN), 2) human umbilical vein endothelial cells (HUVEC), and 3) CHO cells expressing ICAM-1 (CHO-ICAM cells).
Treatment:
Cells, pretreated with NIF-derived peptides (0.1-100 microM) for 10 minutes, were permitted to adhere for 20 min in the continued presence of peptide.
Methods:
Cell-based assays: 1) PMN adherence to HUVEC, 2) PMN adhesion to immobilized human serum proteins, and 3) adherence of CHO-ICAM cells to immobilized Mac-1.
Results:
A NIF-derived peptide of 29 amino acids blocked PMN adherence to HUVEC, but behaved somewhat differently than the parent NIF protein. NIF specifically antagonized Mac-1 dependent adherence, but the peptide blocked neutrophil adherence that was dependent upon both Mac-1 and LFA-1 integrins. CHO-ICAM adherence to Mac-1 was blocked by NIF, but not by the peptide. Binding studies with NIF and the peptide indicate that the molecules bind to different sites.
Conclusions:
A peptide derived from NIF blocks PMN adherence but, unlike NIF, the mechanism of action is not mediated by direct antagonism Mac-1.
Insights
A novel peptide derived from neutrophil inhibitory factor (NIF) effectively inhibits neutrophil adherence to endothelial cells. However, its mechanism differs from NIF, as it targets both Mac-1 and LFA-1 integrins, not just Mac-1.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Neutrophil adherence to endothelial cells is a critical process in inflammation.
- Neutrophil inhibitory factor (NIF) is a known antagonist of Mac-1, a key adhesion molecule involved in neutrophil recruitment.
- Understanding the mechanisms of neutrophil adherence inhibition is crucial for developing anti-inflammatory therapies.
Purpose of the Study:
- To evaluate peptides derived from NIF as potential inhibitors of neutrophil adherence.
- To elucidate the mechanism of action of these NIF-derived peptides in blocking neutrophil adhesion.
Main Methods:
- In vitro assays using human polymorphonuclear cells (PMN), human umbilical vein endothelial cells (HUVEC), and CHO cells expressing ICAM-1 (CHO-ICAM).
- Cells were pretreated with NIF-derived peptides and allowed to adhere.
- Assays included PMN adherence to HUVEC, PMN adhesion to immobilized human serum proteins, and adherence of CHO-ICAM cells to immobilized Mac-1.
Main Results:
- A 29-amino acid NIF-derived peptide inhibited PMN adherence to HUVEC.
- The peptide blocked neutrophil adherence dependent on both Mac-1 and LFA-1 integrins, unlike the parent NIF protein which specifically antagonized Mac-1.
- NIF inhibited CHO-ICAM adherence to Mac-1, but the peptide did not, suggesting different binding sites.
Conclusions:
- A peptide derived from NIF effectively blocks polymorphonuclear cell (PMN) adherence.
- The mechanism of action of this peptide is not mediated by direct antagonism of Mac-1, distinguishing it from the parent NIF protein.
- These findings suggest a novel therapeutic target for modulating neutrophil adhesion in inflammatory conditions.