Toll-like receptor 3 upregulation in macrophages participates in the initiation and maintenance of pristane-induced arthritis in rats

Abstract

IntroductionToll-like receptors (TLRs) are involved in both innate and adaptive immune responses and are likely to play a complex role in the pathogenesis of human rheumatoid arthritis (RA) and experimental arthritis. The objective of this study was to identify the key TLR in pristane-induced arthritis (PIA), a rat model for RA, and to clarify its roles in the initiation and maintenance of arthritis.MethodsArthritis in DA rats was induced by pristane and the severity was evaluated by macroscopic and microscopic score systems. Spleen TLR and cytokine expression was detected at different time points by real-time polymerase chain reaction (PCR) and flow cytometry. Polyinosine-polycytidylic acid (polyI:C, a ligand of TLR3) or TLR3 specific short-hairpin RNA plasmid for RNA interference was administrated to PIA rats in vivo. Serum nitrogen oxide concentration was determined by Griess method, and tumor necrosis factor alpha (TNF-α) was determined by L929 biotest. In splenic macrophages, TLR3 expression was measured by flow cytometry. A rat macrophage cell line (NR8383) was stimulated by pristane, and anti-TLR3 antibody were used to block TLR3 pathway. TLR3 and cytokine expression in NR8383 were detected by real-time PCR.ResultsBy screening the TLR expression profile in spleen of DA rats after pristane injection, we found that TLR3 was the most early and prominently upregulated TLR. Both TLR3 mRNA and protein expression of spleen were upregulated at 6 and 26 days after pristane injection. Furthermore, administration of polyI:C exacerbated, whereas RNA interference targeting TLR3 ameliorated, the arthritis. Particularly, TLR3 expression was induced in splenic macrophages of PIA rats, and also in the NR8383 cell line after pristane stimulation in a dose- and time- dependent manner. Upregulation of interferon beta (IFN-β) and TNF-α by pristane stimulation was blocked by anti-TLR3 antibody in NR8383.ConclusionsTLR3 plays a pivotal role in the initiation and development of PIA which may dependent on macrophage. These findings are useful to understand the pathogenesis of RA and may provide an intriguing therapeutic opportunity for RA.

Methotrexate ameliorates pristane-induced arthritis by decreasing IFN-γ and IL-17A expressions

“…Synovial fluid nitrite concentration was significantly correlated with serum nitrite concentration in patients with RA (Farrell et al, 1992). Previously, we have found that the plasma NO level is also increased in PIA rat models (Meng et al, 2010). Fig.…”

“…We began to give the medicine one day before induction in the prevention groups, and started to administrate the medicine at 13 d after induction in the treatment groups, as our previous observations showed that the average onset of PIA was at 14 d after induction (Meng et al, 2010). Both groups were given the medicine continuously for 5 d. Two dose groups of BSO for both prevention and treatment were used, with 2.5 and 5 ml/kg BW for low and high doses, respectively.…”

The Role Of IL-6 In TMPD-Treated Lupus Arthritis Mice

“…It is predicted that the autophagy mechanism which is stated by Zhu [13] occurs, so the joint disorder develops without the equal increase of total IL-6. It might be a result of upregulation of TLR 3 on macrophages [16] causes the control of marker cells in rheumatoid diseases [17].…”

Targeting DAMP Activation of Toll-Like Receptors: Novel Pathways to Treat Rheumatoid Arthritis?

“…TLR3 was found to be the most significantly up-regulated TLR during pristine induced arthritis in rats, where it appeared in the spleen early after disease initiation. Stimulation of TLR3 with polyI:C also exacerbated disease severity and silencing TLR3 expression reduced disease severity in these animals (Meng et al, 2010). Despite evidence from human studies highlighting the contribution of TLR8 in synovial inflammation, the lack of activation of murine TLR8 by its cognate ligand suggests this PRR is not biologically active in mice (Heil et al, 2004).…”