A delta2-opioid agonist inhibits p38 MAPK and suppresses activation of murine macrophages.
BACKGROUND
delta-Opioid agonists have been shown to attenuate ischemic organ injury in multiple models. The purpose of the present study was to determine if delta-opioid agonists could inhibit proinflammatory cytokine production by macrophages.


METHODS
Murine macrophages (RAW 264.7) were pretreated for 4 h with media, a dose range (10(-4) to 10(-7) M) of DADLE ([D-Ala2], D-Leu5]-enkephalin, a nonspecific delta-opioid receptor agonist), a dose range (10(-4) to 10(-7) M) of DPDPE ([D2,5Pen]-enkephalin, a specific delta1-opioid receptor agonist), or a dose range (10(-4) to 10(-7) M) of Deltorphin-Dvariant (a specific delta2 opioid receptor agonist) and then incubated with 0.1 microg/ml lipopolysaccharide (LPS) for 1 or 4 h. Cytokine levels were measured by enzyme-linked immunosorbent assay. Activation of NF-kappaB, AP-1, and p38 MAPK were determined by mobility shift assays and Western blot.


RESULTS
LPS induced significant increases in TNFalpha and MIP-2 production. Deltorphin-Dvariant, but not DADLE or DPDPE, dose-dependently reduced both TNFalpha and MIP-2 production. Deltorphin-Dvariant did not alter activation of the transcription factors NF-kappaB or AP-1, but greatly reduced activation of p38 MAPK.


CONCLUSIONS
The data show that delta2- but not delta1-opioid agonists suppress LPS-induced p38 MAPK activation and expression of TNFalpha and MIP-2.
Husted
Thomas L
TL
Laboratory of Trauma, Sepsis, and Inflammation Research, Department of Surgery, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0558, USA.
Govindaswami
Meera
M
Oeltgen
Peter R
PR
Rudich
Steven M
SM
Lentsch
Alex B
AB
D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D002460:Cell Line; D054426:Chemokine CXCL2; D018925:Chemokines / Q000096:biosynthesis; D016207:Cytokines / Q000096:biosynthesis; D020881:Enkephalin, D-Penicillamine (2,5)- / Q000494:pharmacology*; D016308:Enkephalin, Leucine-2-Alanine / Q000494:pharmacology*; D008070:Lipopolysaccharides; D008262:Macrophage Activation / Q000187:drug effects* / Q000276:immunology; D008264:Macrophages / Q000187:drug effects / Q000276:immunology; D051379:Mice; D009842:Oligopeptides / Q000494:pharmacology*; D017465:Receptors, Opioid, delta / Q000819:agonists; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis; D048051:p38 Mitogen-Activated Protein Kinases / Q000276:immunology
D000701:Analgesics, Opioid; D054426:Chemokine CXCL2; D018925:Chemokines; C404915:Cxcl2 protein, mouse; D016207:Cytokines; D008070:Lipopolysaccharides; D009842:Oligopeptides; D017465:Receptors, Opioid, delta; D014409:Tumor Necrosis Factor-alpha; C059567:deltorphin; D016308:Enkephalin, Leucine-2-Alanine; D020881:Enkephalin, D-Penicillamine (2,5)-; D048051:p38 Mitogen-Activated Protein Kinases