Rimonabant inhibits TNF-α-induced endothelial IL-6 secretion via CB1 receptor and cAMP-dependent protein kinase pathway.
OBJECTIVE
To investigate whether rimonabant, a cannabinoid receptor antagonist, had inhibitory effects on inflammatory reactions in human umbilical vein endothelial cells (HUVEC).


METHODS
TNF-α-induced IL-6 production was measured by ELISA and effects on related signaling pathways were investigated by immunoblot analysis. Cellular cAMP level was measured using kinase-coupled luciferase reaction.


RESULTS
Rimonabant at 1 and 10 μmol/L significantly inhibited TNF-α-induced IL-6 production when added 15, 30 and 60 minutes before TNF-α treatment. Rimonabant also inhibited TNF-α-induced phosphorylation of IκB kinase (IKK) α/β and IκB-α degradation. ACEA, a cannabinoid receptor subtype 1 (CB1) agonist, added before rimonabant abolished the former effects of rimonabant. H-89, an inhibitor of cAMP-dependent protein kinase (PKA), abolished the inhibitory effects of rimonabant on TNF-α induced IL-6 production. Rimonabant also increased the phosphorylation of PKA regulatory subunit II (PKA-RII), implying the essential role of PKA activation in the inhibitory effects of rimonabant. Treatment with the phosphatidylinositol 3-kinase (PI3K) inhibitor, wortmannin did not abolish the inhibitory effects of rimonabant on TNF-α induced IL-6 production.


CONCLUSIONS
Rimonabant had anti-inflammatory effects on endothelial cells and inhibited TNF-α-induced IKKα/β phosphorylation, IκB-α degradation and IL-6 production in HUVEC. This effect was related to CB1 antagonism and PKA activation.
Huang
Nan-lan
NL
Institute of Pharmacology, National Taiwan University, Taipei, China.
Juang
Jyh-ming
JM
Wang
Yi-ho
YH
Hsueh
Chia-hsiang
CH
Liang
Yao-jen
YJ
Lin
Jiunn-lee
JL
Tsai
Chia-ti
CT
Lai
Ling-ping
LP
D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D042783:Endothelial Cells / Q000187:drug effects / Q000276:immunology; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000201:enzymology / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D015151:Immunoblotting; D015850:Interleukin-6 / Q000096:biosynthesis / Q000378:metabolism*; D010766:Phosphorylation; D010880:Piperidines / Q000494:pharmacology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology*; D034741:RNA, Small Interfering / Q000494:pharmacology; D043884:Receptor, Cannabinoid, CB1 / Q000037:antagonists & inhibitors* / Q000235:genetics; D000077285:Rimonabant; D015398:Signal Transduction; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology / Q000502:physiology*
D000894:Anti-Inflammatory Agents, Non-Steroidal; D015850:Interleukin-6; D010880:Piperidines; D047428:Protein Kinase Inhibitors; D011720:Pyrazoles; D034741:RNA, Small Interfering; D043884:Receptor, Cannabinoid, CB1; D014409:Tumor Necrosis Factor-alpha; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D000077285:Rimonabant