Attenuation of murine antigen-induced arthritis by treatment with a decoy oligodeoxynucleotide inhibiting signal transducer and activator of transcription-1 (STAT-1)

Marion Hückel,Klaus Thoss,Steffen Henzgen,Andreas H Wagner,Mieczyslaw Gajda,Rolf Bräuer,Peter K Petrow,Uta Schurigt,Renate Stöckigt,Markus Hecker

doi:10.1186/ar1869

Abstract

The transcription factor STAT-1 (signal transducer and activator of transcription-1) plays a pivotal role in the expression of inflammatory gene products involved in the pathogenesis of arthritis such as various cytokines and the CD40/CD40 ligand (CD40/CD40L) receptor-ligand dyad. The therapeutic efficacy of a synthetic decoy oligodeoxynucleotide (ODN) binding and neutralizing STAT-1 was tested in murine antigen-induced arthritis (AIA) as a model for human rheumatoid arthritis (RA). The STAT-1 decoy ODN was injected intra-articularly in methylated bovine serum albumin (mBSA)-immunized mice 4 h before arthritis induction. Arthritis was evaluated by joint swelling measurement and histological evaluation and compared to treatment with mutant control ODN. Serum levels of pro-inflammatory cytokines, mBSA-specific antibodies and auto-antibodies against matrix constituents were assessed by enzyme-linked immunosorbent assay (ELISA). The transcription factor neutralizing efficacy of the STAT-1 decoy ODN was verified in vitro in cultured synoviocytes and macrophages. Single administration of STAT-1 decoy ODN dose-dependently suppressed joint swelling and histological signs of acute and chronic arthritis. Delayed-type hypersensitivity (DTH) reaction, serum levels of interleukin-6 (IL-6) and anti-proteoglycan IgG titres were significantly reduced in STAT-1 decoy ODN-treated mice, whereas mBSA, collagen type I and type II specific immunoglobulins were not significantly affected. Intra-articular administration of an anti-CD40L (anti-CD154) antibody was similarly effective. Electrophoretic mobility shift analysis (EMSA) of nuclear extracts from synoviocytes incubated with the STAT-1 decoy ODN in vitro revealed an inhibitory effect on STAT-1. Furthermore, the STAT-1 decoy ODN inhibited the expression of CD40 mRNA in stimulated macrophages. The beneficial effects of the STAT-1 decoy ODN in experimental arthritis presumably mediated in part by affecting CD40 signalling in macrophages may provide the basis for a novel treatment of human RA.

Highlights

Human rheumatoid arthritis (RA) is a chronic systemic disorder of unknown aetiology, characterized by intimal lining layer hyperplasia, infiltration of the sublining area by macrophages, T and B lymphocytes, plasma cells and other inflammatory cells as well as progressive destruction of joint structures [1,2]
Besides the pro-inflammatory cytokines tumour necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6, which mainly derive from macrophages, a dominant T-helper (Th)1-response is associated with the disease, which is characterized by an imbalance of interferon (IFN)-γ over IL-4 [3,4]
Collagen type I and type II specific IgGs were not changed, proteoglycan-specific IgGs were significantly diminished by treatment with the STAT-1 decoy ODN (Figure 3b)

Summary

Introduction

Human rheumatoid arthritis (RA) is a chronic systemic disorder of unknown aetiology, characterized by intimal lining layer hyperplasia, infiltration of the sublining area by macrophages, T and B lymphocytes, plasma cells and other inflammatory cells as well as progressive destruction of joint structures [1,2]. IFN-γ as well as many other cytokines from Th cells regulate gene expression and cellular activation, proliferation and differentiation by means of the janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway [5,6] The binding of these cytokines to their receptors activates a distinct pair of JAK molecules, which are responsible for the phosphorylation and activation of latent cytoplasmic STAT molecules. Elevated levels of STAT-1 protein in phosphorylated and unphosphorylated forms were detected in the synovial tissue of RA patients [10] and the increased expression of STAT-1-dependent genes correlates with the high inflammatory activity of RA patients [8] These include lymphocyte and antigen-presenting cell genes as well as genes encoding activation markers, transcription factors, signalling molecules, chemokines and chemokine/cytokine receptors. We used murine antigen-induced arthritis (AIA), as a Th1-mediated experimental arthritis model [19], which is characterized by local and systemic activation of macrophages, [20] as well as synovial fibroblasts [21]

Methods

Results

Conclusion