Multi-response model for rheumatoid arthritis based on delay differential equations in collagen-induced arthritic mice treated with an anti-GM-CSF antibody.

Collagen-induced arthritis (CIA) in mice is an experimental model for rheumatoid arthritis, a human chronic inflammatory destructive disease. The therapeutic effect of neutralizing the cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) by an antibody was examined in the mouse disease in a view of deriving a pharmacokinetic/pharmacodynamic (PKPD) model. In CIA mice the development of disease is measured by a total arthritic score (TAS) and an ankylosis score (AKS). We present a multi-response PKPD model which describes the time course of the unperturbed and perturbed TAS and AKS. The antibody acts directly on GM-CSF by binding to it. Therefore, a compartment for the cytokine GM-CSF is an essential component of the mathematical model. This compartment drives the disease development in the PKPD model. Different known properties of arthritis development in the CIA model are included in the PKPD model. Firstly, the inflammation, driven by GM-CSF, dominates at the beginning of the disease and decreases after some time. Secondly, a destructive (ankylosis) part evolves in the TAS that is delayed in time. In order to model these two properties a delay differential equation was used. The PKPD model was applied to different experiments with doses ranging from 0.1 to 100 mg/kg. The influence of the drug was modeled by a non-linear approach. The final mathematical model consists of three differential equations representing the compartments for GM-CSF, inflammation and destruction. Our mathematical model described well all available dosing schedules by a simultaneous fit. We also present an equivalent and easy reformulation as ordinary differential equation which grants the use of standard PKPD software.

The interleukin-2 antagonizing antibody MT204 delays allogeneic skin graft rejection in non-human primates and is well tolerated.

MT204 is a humanized IgG1 antibody specific for interleukin-2 (IL-2) of human and rhesus monkey origin. It potently antagonizes IL-2 signaling in both CD25(+) and CD25(-) cells by a unique mode of action. MT204 can not only prevent soluble IL-2 from binding to the intermediate affinity IL-2 receptors but can also antagonize IL-2 that is already bound to the CD25 subunit of high affinity IL-2 receptors on the cell surface. As initial steps toward development of a therapeutic antibody, pharmacokinetics (PK) and tolerability of MT204, as well as efficacy were investigated in rhesus monkeys. MT204 was infused by single escalating (2, 10 and 50mg/kg) or repeat dose administrations (50mg/kg, 1 ×/week for 3 weeks). Over the course of the experiment, the animals were regularly observed for clinical adverse reaction and bled for laboratory investigations (PK, hematology, chemical chemistry and leukocyte subset analysis). For the efficacy study, six rhesus monkeys were grafted with MHC-mismatched rhesus skin and infused with MT204 (50mg/kg), on the day of transplantation and again on days 5 and 12 post grafting. Efficacy was determined by assessment of graft necrosis at different time-points. No obvious adverse effects were observed clinically after single infusion, or after three repeated infusions of 50mg/kg and no MT204-related toxic effects were revealed by hematology or clinical chemistry. In the efficacy study, MT204-treated animals showed a significant delay in graft rejection versus control animals (p=0.025 by Log-rank test). The characteristics of MT204, displaying linear pharmacokinetics, half-life in the range expected for a human IgG, benign safety profile and signs of efficacy, warrant further development of this antibody for therapy.

Lipopolysaccharide-induced lung inflammation is inhibited by neutralization of GM-CSF.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) plays an important role in the pathogenesis of acute and chronic lung disease as a major regulator governing the functions of granulocyte and macrophage lineage populations. Chronic obstructive pulmonary disease (COPD) is a disease characterized by lung inflammation with accumulation of neutrophils and increased levels of pro-inflammatory cytokines including GM-CSF in the patient's lungs. We used intranasal administration of lipopolysaccharide (LPS) to mice to induce a disease that resembles COPD with pulmonary inflammation, neutrophil recruitment and release of pro-inflammatory mediators in the bronchoalveolar lavage fluid of the diseased mice. 2 h prior to LPS administration, mice were systemically treated with the murine GM-CSF neutralizing antibody mAb 22E9 per intraperitoneal injection. Intranasal challenge with LPS-induced an increase of total cell number and of neutrophils in the bronchoalveolar lavage fluid. Elevated levels of tumor necrosis factor alpha (TNF-alpha), keratinocyte cytokine and macrophage inflammatory protein-2 (MIP-2) were also observed at this time point. GM-CSF was no longer detectable in bronchoalveolar lavage fluid at 24 h due to its early expression with a peak reached 6 h after LPS challenge. Pretreatment of mice with GM-CSF neutralizing antibody dose-dependently inhibited the accumulation of neutrophils and reduced TNF-alpha and MIP-2 protein levels in bronchoalveolar lavage fluid. These data suggest that neutralization of GM-CSF may represent a novel treatment modality for lung inflammation and in particular for COPD.

Treatment with recombinant interferon-beta reduces inflammation and slows cartilage destruction in the collagen-induced arthritis model of rheumatoid arthritis.

We investigated the therapeutic potential and mechanism of action of IFN-beta protein for the treatment of rheumatoid arthritis (RA). Collagen-induced arthritis was induced in DBA/1 mice. At the first clinical sign of disease, mice were given daily injections of recombinant mouse IFN-beta or saline for 7 days. Disease progression was monitored by visual clinical scoring and measurement of paw swelling. Inflammation and joint destruction were assessed histologically 8 days after the onset of arthritis. Proteoglycan depletion was determined by safranin O staining. Expression of cytokines, receptor activator of NF-kappaB ligand, and c-Fos was evaluated immunohistochemically. The IL-1-induced expression of IL-6, IL-8, and granulocyte/macrophage-colony-stimulating factor (GM-CSF) was studied by ELISA in supernatant of RA and osteoarthritis fibroblast-like synoviocytes incubated with IFN-beta. We also examined the effect of IFN-beta on NF-kappaB activity. IFN-beta, at 0.25 microg/injection and higher, significantly reduced disease severity in two experiments, each using 8-10 mice per treatment group. IFN-beta-treated animals displayed significantly less cartilage and bone destruction than controls, paralleled by a decreased number of positive cells of two gene products required for osteoclastogenesis, receptor activator of NF-kappaB ligand and c-Fos. Tumor necrosis factor alpha and IL-6 expression were significantly reduced, while IL-10 production was increased after IFN-beta treatment. IFN-beta reduced expression of IL-6, IL-8, and GM-CSF in RA and osteoarthritis fibroblast-like synoviocytes, correlating with reduced NF-kappaB activity. The data support the view that IFN-beta is a potential therapy for RA that might help to diminish both joint inflammation and destruction by cytokine modulation.

Interferon-beta for treatment of rheumatoid arthritis?

IFN-beta treatment is emerging as a potentially effective form of therapy in various immune-mediated conditions. The present review addresses the possible role of IFN-beta in immune-mediated diseases such as multiple sclerosis and rheumatoid arthritis. Several placebo-controlled trials are discussed, as are the available immunological data that are relevant to this field. Review of these data provides evidence that IFN-beta has some beneficial therapeutic effect in patients with relapsing-remitting multiple sclerosis and might also have antirheumatic potential. This notion is supported by recent studies showing a critical role for IFN-beta in bone homeostasis.