Soluble interleukin-1 receptor accessory protein ameliorates collagen-induced arthritis by a different mode of action from that of interleukin-1 receptor antagonist

OBJECTIVE

To discern the mode of interleukin-1 (IL-1) inhibition of soluble IL-1 receptor accessory protein (sIL-1RAcP) by comparison with IL-1 receptor antagonist (IL-1Ra) in arthritis.

METHODS

Adenoviral vectors encoding either sIL-1RAcP or IL-1Ra were administered systemically before onset of collagen-induced arthritis in DBA/1 mice. Anti-bovine type II collagen IgG and IL-6 were quantified in serum. Proliferative response of splenic T cells was determined in the presence of sIL-1RAcP or IL-1Ra. The effect on IL-1 inhibition of recombinant sIL-1RAcP and IL-1Ra was further examined in vitro, using NF-kappaB luciferase reporter cell lines. Quantitative polymerase chain reaction was used to determine the relative messenger RNA expression of the IL-1 receptors.

RESULTS

Adenoviral overexpression of both sIL-1RAcP and IL-1Ra resulted in amelioration of the collagen-induced arthritis. Both IL-1 antagonists reduced the circulating levels of antigen-specific IgG2a antibodies, but only IL-1Ra was able to inhibit lymphocyte proliferation. By using purified lymphocyte populations derived from NF-kappaB reporter mice, we showed that sIL-1RAcP inhibits IL-1-induced NF-kappaB activity in B cells but not T cells, whereas IL-1Ra inhibited IL-1 on both cell types. A study in a panel of NF-kappaB luciferase reporter cells showed that the sIL-1RAcP inhibits IL-1 signaling on cells expressing either low levels of membrane IL-1RAcP or high levels of IL-1RII.

CONCLUSION

We show that the sIL-1RAcP ameliorated experimental arthritis without affecting T cell immunity, in contrast to IL-1Ra. Our results provide data in support of receptor competition by sIL-1RAcP as an explanation for the different mode of IL-1 antagonism in comparison with IL-1Ra.

An inflammation-inducible adenoviral expression system for local treatment of the arthritic joint

To achieve a disease-regulated transgene expression for physiologically responsive gene therapy of arthritis, a hybrid promoter was constructed. The human IL-1 beta enhancer region (-3690 to -2720) upstream of the human IL-6 promoter region (-163 to +12) was essential in mounting a robust response in HIG-82 synovial fibroblasts and in RAW 264,7 macrophages. A replication-deficient adenovirus was engineered with luciferase (Luc) controlled by the IL-1/IL-6 promoter (Ad5.IL-1/IL-6-Luc). LPS caused a 23- and 4.6-fold induction of Luc. activity in RAW cells infected with Ad5.IL-1/IL-6-Luc or the conventional Ad5.CMV-Luc construct, respectively. Next, adenoviruses (10(6) ffu) were injected into the knees of C57Bl/6 mice. An intra-articular injection of zymosan, 3 days after Ad5.IL-1/IL-6-Luc, increased Luc. activity by 39-fold but had no effect in the Ad5.CMV-Luc joints. The constitutive CMV promoter was rapidly silenced and could not be reactivated in vivo. In contrast, the IL-1/IL-6 promoter could be reactivated by Streptococcal cell wall (SCW)-induced arthritis up to 21 days after infection. Next the IL-1/IL-6 promoter was compared to the C3-Tat/HIV-LTR two-component system in wild-type, IL-6(-/-) and IL-1(-/-) gene knockout mice. Both systems responded well to LPS-, zymosan- and SCW-induced arthritis. However, the basal activity of the IL-1/IL-6 promoter was lower and IL-6 independent. This study showed that the IL-1/IL-6 promoter is feasible to achieve disease-regulated transgene expression for treatment of arthritis.

Effectiveness of the soluble form of the interleukin-1 receptor accessory protein as an inhibitor of interleukin-1 in collagen-induced arthritis

OBJECTIVE

To investigate whether the soluble form of interleukin-1 (IL-1) receptor accessory protein (sIL-1RAcP), whose physiologic function remains to be established, can serve as a specific inhibitor of IL-1 signaling in vitro, and to evaluate its applicability in collagen-induced arthritis (CIA).

METHODS

Soluble IL-1RAcP was cloned from murine liver complementary DNA and expressed by the use of either an adenoviral vector (AdRGD) for sIL-1RAcP or a stable-transfected NIH3T3 fibroblast cell line. The ability of affinity-purified sIL-1RAcP to inhibit IL-1 signaling was tested on NF-kappaB luciferase reporter fibroblasts and quantified by luminometer. To investigate therapeutic efficacy, sIL-1RAcP was both locally (knee joint) and systemically overexpressed in collagen-immunized male DBA/1 mice. Severity of arthritis was monitored visually, and the pathologic process in the joint was examined histologically. Serum was obtained from mice to quantify IL-6 and anti-bovine type II collagen (BCII) antibody levels.

RESULTS

Incubation of the NF-kappaB reporter fibroblast with purified sIL-1RAcP protein showed a marked reduction of IL-1-induced, but not tumor necrosis factor-induced, NF-kappaB activation. This showed a novel role for sIL-1RAcP as a specific inhibitor of IL-1 signaling. Local transplantation of sIL-1RAcP-producing NIH3T3 fibroblasts into the knee before onset of CIA had little or no effect on general disease severity in these mice. Histologic evaluation of the knee joints receiving sIL-1RAcP cell transplantation showed a marked reduction in both joint inflammation and bone and cartilage erosion. Local treatment with sIL-1RAcP had no profound effect on serum levels of IL-6 and anti-BCII antibodies, which is indicative of the ongoing presence of arthritis in distal joints. In contrast to local treatment, systemic treatment with the AdRGD for sIL-1RAcP markedly ameliorated CIA in all joints.

CONCLUSION

In this study we demonstrated that sIL-1RAcP is a biologically active and innovative inhibitor of IL-1, and treatment of mice with sIL-1RAcP had a profound prophylactic effect on collagen-induced arthritis.

Adenoviral delivery of IL-18 binding protein C ameliorates collagen-induced arthritis in mice

Elevated concentrations of interleukin-18 (IL-18) are found in both serum and synovial fluid of patients suffering from rheumatoid arthritis (RA) and this cytokine has recently been implicated in the development of experimental arthritis. In this present study, we developed an IL-18 neutralizing intervention and examined its efficacy for local intra-articular treatment of experimental arthritis. To this end we constructed an adenoviral vector containing the murine IL-18 binding protein isoform c gene (AdCMVIL-18BPc). The constructed adenoviral vector was validated on replication deficiency, transfection efficacy and ability to express biological functional IL-18BPc. Intra-articular overexpression of IL-18BPc significantly reduced incidence of collagen-induced arthritis (CIA) in treated kneejoints. Affected kneejoints of IL-18BPc-treated mice showed less severe arthritis, characterized by reduction of inflammation and destruction of bone and cartilage. Local intra-articular IL-1BPc treatment in both knees provided additional protection against CIA incidence and severity in distal paws. Measurement of serum levels of specific collagen type (CII) Abs revealed a moderate reduction of circulating IgG2a anti-CII Abs, while IgG1 anti-CII Abs remained at similar level. The present study underlines the involvement of IL-18 as an important proinflammatory cytokine in onset of experimental arthritis. Furthermore, it shows that endogenous IL-18 can be blocked efficiently through local adenoviral overexpression of IL-18BPc, indicating that treatment with IL-18BPc might contribute to joint protection in RA.

Increased expression of Fcgamma receptors II and III on macrophages of rheumatoid arthritis patients results in higher production of tumor necrosis factor alpha and matrix metalloproteinase

OBJECTIVE

To evaluate Fcgamma receptor (FcgammaR) expression on synovial macrophages from rheumatoid arthritis (RA) patients and to determine whether this expression correlates with the production of the proinflammatory cytokines tumor necrosis factor alpha (TNFalpha), interleukin-1beta (IL-1beta), IL-12, and matrix metalloproteinase 1 (MMP-1). We also sought to determine whether mature macrophages from RA patients express aberrant levels of FcgammaRI, FcgammaRII, and FcgammaRIII, and to determine the production of inflammatory mediators after immune complex (IC) stimulation.

METHODS

Immunohistochemistry was performed on cryostat sections of synovial biopsy specimens obtained from 27 RA patients and 5 controls. FcgammaR I, II, and III were detected, as well as the proinflammatory mediators IL-1, TNFalpha, IL-12, and MMP-1. Monocytes were isolated from the blood of 10 RA patients and 10 healthy controls and cultured for 7 days with macrophage colony-stimulating factor to obtain macrophages. Using fluorescence-activated cell sorting, the expression of FcgammaRI, FcgammaRII, and FcgammaRIII was determined. On day 7, macrophages were stimulated with heat-aggregated gamma globulins (HAGGs) for 24 hours. Production of cytokines was measured using enzyme-linked immunosorbent assay, and production of gelatinases/collagenases was measured by degradation of fluorescent gelatin.

RESULTS

Immunohistochemistry showed higher FcgammaRII and FcgammaRIII expression in RA synovium than in controls. FcgammaRII and FcgammaRIII, but not FcgammaRI, were highly correlated with the number of synovial macrophages. Consistent with this, TNFalpha expression correlated positively with FcgammaRIII expression. Moreover, MMP-1 expression strongly correlated with FcgammaR I, II, and III expression. Mature macrophages from RA patients showed significantly enhanced expression of FcgammaRII and FcgammaRIII compared with controls. Twenty-four hours after stimulation of RA macrophages with HAGGs, significantly higher production of TNFalpha and gelatinase/collagenase was measured.

CONCLUSION

RA synovium and mature RA macrophages express significantly elevated levels of FcgammaRII and FcgammaRIII, resulting in much higher production of TNFalpha and gelatinase/collagenase after IC stimulation. These data suggest that disturbed expression of FcgammaR on mature synovial macrophages is involved in the pathology of RA.

C3-Tat/HIV-regulated intraarticular human interleukin-1 receptor antagonist gene therapy results in efficient inhibition of collagen-induced arthritis superior to cytomegalovirus-regulated expression of the same transgene

OBJECTIVE

To achieve disease-inducible expression of recombinant antiinflammatory proteins in order to allow autoregulation of drug dose by natural homeostatic mechanisms.

METHODS

We compared the inducible 2-component expression system (C3-human immunodeficiency virus/transactivator of transcription [C3-Tat/HIV]) with the constitutive cytomegalovirus (CMV) promoter in the polyarticular collagen-induced arthritis (CIA) model in mice. DBA/1 mice were immunized with bovine type II collagen and were given boosters on day 21. On day 22, mice were injected intraarticularly with the adenoviral vectors AdCMVLuc, AdCMVhIL-1Ra, AdC3-Tat/HIV-Luc, or AdC3-Tat/HIV-hIL-1Ra. The injected knee joints and hind paws were then scored for signs of arthritis, and knee joint histology was compared.

RESULTS

The CMV-driven interleukin-1 receptor antagonist (IL-1Ra) expression resulted in a high constitutive expression and amelioration of CIA. C3-Tat/HIV-driven IL-1Ra expression could be detected only on days 24, 29, and 35. Fourteen days after injection of the vectors, CIA was significantly better inhibited by the C3-Tat/HIV-driven IL-1Ra expression compared with the CMV-driven IL-1Ra expression. Moreover, prevention of CIA in the knee joints also prevented CIA in the untreated hind paws.

CONCLUSION

Our data demonstrate for the first time the feasibility of an inducible expression system for local production of IL-1Ra for treatment of arthritis in the CIA model.

Long term anti-tumour necrosis factor alpha monotherapy in rheumatoid arthritis: effect on radiological course and prognostic value of markers of cartilage turnover and endothelial activation

OBJECTIVES

To investigate the effect of prolonged neutralisation of tumour necrosis factor alpha (TNFalpha) on the radiological course in rheumatoid arthritis (RA). To assess whether the radiological course can be predicted by clinical variables or biological markers of cartilage and synovium turnover and of endothelial activation.

PATIENTS AND METHODS

Forty seven patients with active RA enrolled at our centre in monotherapy trials with adalimumab (D2E7), a fully human anti-TNFalpha monoclonal antibody, were studied for two years. Radiographs of hands and feet obtained at baseline and after one and two years were scored in chronological order by a single, blinded observer using the modified Sharp method. Radiological course was classified as stable or progressive using the smallest detectable difference as cut off point. The relation between radiological course and serum markers of cartilage and synovium turnover (metalloproteinases (MMP-1 and MMP-3), cartilage oligomeric matrix protein (COMP), human cartilage glycoprotein-39 (HC gp-39)), endothelial activation (soluble E-selectin and intercellular adhesion molecule (ICAM-1)), and integrated measures of disease activity were assessed using univariate and multivariate analysis.

RESULTS

Radiological evaluation was performed in 36 patients with paired sets of radiographs at baseline and two years. After two years a total of 15/36 (42%) presented no radiological progression. More patients with stable radiological course were still receiving anti-TNFalpha treatment after two years (13/15 (87%) v 11/21 (52%); p=0.03) and had lower baseline COMP and sICAM-1 levels (p=0.01 and 0.04, respectively) than those in the group with progressive disease. In a logistic regression model the combination of sustained TNF neutralisation and baseline COMP and sICAM-1 levels was predictive for radiological outcome (p=0.03). C reactive protein and disease activity score area under the curve were significantly correlated with changes in radiological scores after two years (r=0.40 and 0.37, p<0.05). Long term TNFalpha neutralisation decreased the levels of COMP, sICAM, MMPs, and HC gp-39, but not sE-selectin.

CONCLUSION

The results suggest that long term monotherapy with anti-TNFalpha has a positive effect on radiological outcome and modulates cartilage and synovium turnover as measured by biological markers. Baseline serum sICAM-1 levels and COMP levels may be helpful to identify patients with progressive or non-progressive radiological outcome.