Rheumatology 2001; 40: 1013-1021
© 2001 British Society for Rheumatology
Original Papers |
The
-opioid agonist, asimadoline, alters cytokine gene expression in adjuvant arthritis
School of Physiology and Pharmacology, University of New South Wales and
1 Department of Rheumatology, St George Hospital, New South Wales, Australia
Objective. We have previously found that the
-opioid agonist, asimadoline, attenuates adjuvant arthritis in a dose-dependent, antagonist-reversible manner. To elucidate possible mechanisms, we investigated the effects of asimadoline (5 mg/kg/day i.p.) or vehicle on in vivo cytokine expression and T-cell recruitment in adjuvant arthritis.
Methods. Arthritis severity was assessed every 34 days for 21 days. Rats were killed on days 0, 13 and 21 post-induction and synovial membrane and inguinal lymph nodes were removed for mRNA extraction. Changes in cytokine mRNA expression were measured using reverse transcriptionpolymerase chain reaction (RTPCR) and densitometry. T cells in joints were quantified by immunohistochemistry.
Results. Asimadoline significantly decreased arthritis severity at day 13, with a concomitant decrease in synovial membrane expression of cytokines interleukin-17 and transforming growth factor-ß (TGF-ß) mRNA at day 13, and no change in T cell numbers in the joints of arthritic rats. By contrast, in the inguinal lymph nodes, expression of tumour necrosis factor was increased at day 13 and TGF-ß mRNA was increased throughout.
Conclusion. An altered balance, therefore, in the pro- and anti-inflammatory effects of TGF-ß by asimadoline might explain its striking anti-arthritic actions.
KEY WORDS: Cytokines, Opioids, Asimadoline, Adjuvant arthritis,
-Opioid agonist, Inflammation.
Correspondence to: J. Walker, School of Physiology and Pharmacology, Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia, 2052