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2‐Arachidonoyl‐glycerol suppresses interferon‐γ production in phorbol ester/ionomycin‐activated mouse splenocytes independent of CB1 or CB2
Author(s) -
Kaplan Barbara L. F.,
Ouyang Yanli,
Rockwell Cheryl E.,
Rao Gautham K.,
Kaminski Norbert E.
Publication year - 2005
Publication title -
journal of leukocyte biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.819
H-Index - 191
eISSN - 1938-3673
pISSN - 0741-5400
DOI - 10.1189/jlb.1104652
Subject(s) - ionomycin , nfat , splenocyte , biology , microbiology and biotechnology , endocrinology , medicine , immune system , biochemistry , immunology , transcription factor , stimulation , gene
2‐Arachidonoyl‐glycerol (2‐AG), an endogenous ligand for cannabinoid receptor types 1 and 2 (CB1 and CB2), has previously been demonstrated to modulate immune functions including suppression of interleukin‐2 expression and nuclear factor of activated T cells (NFAT) activity. The objective of the present studies was to investigate the effect of 2‐AG on interferon‐γ (IFN‐γ) expression and associated upstream signaling events. Pretreatment of splenocytes with 2‐AG markedly suppressed phorbol 12‐myristate 13‐acetate plus calcium ionophore (PMA/Io)‐induced IFN‐γ secretion. In addition, 2‐AG suppressed IFN‐γ steady‐state mRNA expression in a concentration‐dependent manner. To unequivocally determine the putative involvement of CB1 and CB2, splenocytes derived from CB1 −/− /CB2 −/− knockout mice were used. No difference in the magnitude of IFN‐γ suppression by 2‐AG in wild‐type versus CB1/CB2 null mice was observed. Time‐of‐addition studies revealed that 2‐AG treatment up to 12 h post‐cellular activation resulted in suppression of IFN‐γ, which was consistent with a time course conducted with cyclosporin A, an inhibitor of NFAT activity. Coincidentally, 2‐AG perturbed the nuclear translocation of NFAT protein and blocked thapsigargin‐induced elevation in intracellular calcium, suggesting that altered calcium regulation might partly explain the suppression of NFAT nuclear translocation and subsequent IFN‐γ production. Indeed, Io partially attenuated the 2‐AG‐induced suppression of PMA/Io‐stimulated IFN‐γ production. Taken together, these data demonstrate that 2‐AG suppresses IFN‐γ expression in murine splenocytes in a CB receptor‐independent manner and that the mechanism partially involves suppression of intracellular calcium signaling and perturbation of NFAT nuclear translocation.