ADENOVIRUS-MEDIATED GENE TRANSFER OF ADIPONECTIN REDUCES THE SEVERITY OF COLLAGEN-INDUCED ARTHRITIS IN MICE

Background: Adiponectin (APN) is a hormone released by adipose tissue with antidiabetic, antiatherogenic, and anti-inflammatory properties. It has been reported that serum and synovial APN levels are elevated in patients with rheumatoid arthritis (RA), but its effect in RA remains unclear. Objectives: The purpose of this study is to examine the effects of systemic delivery of APN in murine arthritis model. Methods: Collagen-induced arthritis (CIA) was induced in male DBA1/J mice by injection of chicken type II collagen (CII) in complete Freunds adjuvant twice with a 21-day interval. Adenoviral vectors encoding human APN (Ad-APN) or beta-galactosidase (Ad-β-gal) as control were injected either before (19 days after initial injection) or during (27 days after initial injection) arthritis progression. Clinical disease activity scores were assessed by the swelling of each limb (maximum score 12 per mouse). Mice were sacrificed, and tissue samples were obtained on day 35 or day 39. Joint sections were examined by hematoxylin and eosin staining and immunohistochemical staining. Serum anti-CII IgG, IgG2a, and IgG1 titers and C1q and C3 levels were examined by ELISA. Proliferation and pro-inflammatory cytokines (IL-1β, IFN-γ, and TNF-α) production from splenocytes were examined by Bromodeoxyuridine (BrdU) assay and ELISA respectively in vitro. Results: Injection of Ad-APN before arthritis progression resulted in about 5-fold increase on day 21 (2 days after adenovirus injection) and about 30-fold increase on day 35 (16 days after adenovirus injection) in serum APN levels compared to control group. When the virus was injected on day 19 (before arthritis progression), the disease activity on day 35 were significantly suppressed by Ad-APN treatment (arthritis score: Ad-APN-infected mice: 1.76±0.63, Ad-β-gal-infected mice: 8.68±1.06; P<0.001). In addition, when the virus was injected on day 27 (during arthritis progression), disease activity was also significantly suppressed on day 39 by Ad-APN treatment (arthritis score: Ad-APN-infected mice: 5.17±1.25, Ad-β-gal-infected mice: 9.17±1.15; P<0.05). APN treatment significantly decreased histological scores of inflammation, cartilage damage, and pannnus formation and mRNA levels of pro-inflammatory cytokines (IL-1β, IL-6, IFN-γ, and TNF-α) and complement (C1q, C3, and factor B) in the joints. In addition, APN treatment marginally inhibited proliferation and significantly inhibited IL-1β, TNF-α, and IFN-γ production from splenocytes. Interestingly, APN treatment markedly suppressed complement C1q and C3 deposition on the cartilage surface, although did not significantly alter serum anti-CII IgG, IgG2a, and IgG1 titers and C1q and C3 levels. Recombinant APN did not directly alter C1q and C3 activation by adherent immunocomplex in vitro (examined by both classical and alternative pathway). Conclusion: These results indicate that systemic APN delivery inhibits complement activation indirectly through several anti-inflammatory mechanisms in the joints. The present study demonstrates for the first time that systemic APN delivery provides protection against the development of inflammatory arthritis in a murine model, and the results provide new insights on the role of APN in inflammatory arthritis and new strategies for the treatment. Disclosure of Interest: None declaredCitation: Annals of the Rheumatic Diseases, volume 68, supplement 3, year 2009, page 384Session: Arthritis etiology, pathogenesis and animal models (Poster Presentations )