Diazepam-binding inhibitor-derived peptides induce intracellular calcium changes and modulate human neutrophil...

Area of Science:

• Immunology
• Neuroscience
• Cell Biology

Background:

• Diazepam-binding inhibitor (DBI) and its derived peptides are implicated in various physiological processes.
• Human neutrophils play a critical role in innate immunity and inflammatory responses.
• Peripheral benzodiazepine receptors (pBRs) are expressed on neutrophils and may mediate peptide interactions.

Purpose of the Study:

• To investigate the effects of two DBI-derived peptides, triakontatetraneuropeptide (TTN) and eiksoneuropeptide (ENP), on human neutrophil functions.
• To elucidate the role of peripheral benzodiazepine receptors (pBRs) in mediating these peptide-induced effects.

Main Methods:

• Measurement of cytosolic free Ca2+ concentrations ([Ca2+]i) in neutrophils.
• Assessment of neutrophil chemotaxis, superoxide anion (O2-) generation, and phagocytosis.
• Utilized pBR ligand (RO 5-4864) and antagonist (PK-11195) to probe receptor involvement.

Main Results:

• Both TTN and ENP induced a rapid, transient rise in [Ca2+]i, with differential dependence on extracellular Ca2+.
• TTN enhanced neutrophil chemotaxis, O2- generation, and phagocytosis; ENP enhanced phagocytosis but not migration or O2- generation.
• Peptide effects on neutrophil functions were largely independent of pBRs, despite some modulation of [Ca2+]i by pBR ligands/antagonists.

Conclusions:

• DBI-derived peptides modulate human neutrophil functions, including calcium signaling and phagocytosis, through predominantly pBR-independent mechanisms.
• These findings suggest a potential role for DBI-derived peptides in neuroimmune interactions and the regulation of inflammatory processes.