Neuropeptides and inflammation. A somatostatin analog as a selective antagonist of neutrophil activation by substance P.
OBJECTIVE
Substance P and somatostatin are neuropeptides found in peripheral sensory nerves. In vitro, these have opposing effects on inflammatory cells. We compared the effects of these peptides on the activation of neutrophils.


METHODS
Neutrophils were isolated from healthy volunteers, and chemotaxis, superoxide anion generation, aggregation, and changes in cytosolic calcium and GTPase activity were measured in the presence of substance P, somatostatin, and the chemoattractant FMLP.


RESULTS
Substance P was an effective chemoattractant, 20% as potent as FMLP at equimolar concentrations. Substance P also stimulated GTPase activity in neutrophil plasma membranes. Somatostatin did not activate neutrophils; however, it effectively inhibited neutrophil chemotaxis and GTPase activity provoked by substance P, but not by FMLP.


CONCLUSIONS
These studies demonstrate that substance P can effectively stimulate chemotaxis, possibly via effects on a GTP-binding protein distinct from that triggered by FMLP, and that somatostatin is a selective antagonist of substance P. The biochemical specificities of these peptides on cells may modulate neurogenic inflammation at the local level.
Kolasinski
S L
SL
Department of Medicine, New York University Medical Center, New York.
Haines
K A
KA
Siegel
E L
EL
Cronstein
B N
BN
Abramson
S B
SB
D000838:Anions / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002449:Cell Aggregation / Q000187:drug effects; D002634:Chemotaxis, Leukocyte; D003600:Cytosol / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000378:metabolism; D006801:Humans; D007249:Inflammation / Q000473:pathology*; D009479:Neuropeptides / Q000502:physiology*; D009504:Neutrophils / Q000187:drug effects / Q000502:physiology*; D015282:Octreotide / Q000494:pharmacology; D013373:Substance P / Q000494:pharmacology*; D013481:Superoxides / Q000378:metabolism
D000838:Anions; D009479:Neuropeptides; D013481:Superoxides; D013373:Substance P; D020558:GTP Phosphohydrolases; D015282:Octreotide; D002118:Calcium