Evaluation of destruction in a collagen-induced arthritis rat model: Bony spur formation

Pathogenesis of Collagen-Induced Arthritis: Role of Immune Cells with Associated Cytokines and Antibodies, Comparison with Rheumatoid Arthritis

Collagen-induced arthritis is the most com-mon in vivo model of rheumatoid arthritis used for investigation of new potential therapies in preclinical research. Rheumatoid arthritis is a systemic inflammatory and autoimmune disease affecting joints, accompanied by significant extra-articular symptoms. The pathogenesis of rheumatoid arthritis and collagen-induced arthritis involves a so far properly unexplored network of immune cells, cytokines, antibodies and other factors. These agents trigger the autoimmune response leading to polyarthritis with cell infiltration, bone and cartilage degeneration and synovial cell proliferation. Our review covers the knowledge about cytokines present in the rat collagen-induced arthritis model and the factors affecting them. In addition, we provide a comparison with rheumatoid arthritis and a description of their important effects on the development of both diseases. We discuss the crucial roles of various immune cells (subtypes of T and B lymphocytes, dendritic cells, monocytes, macrophages), fibroblast-like synoviocy-tes, and their related cytokines (TNF-α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, IL-17, IL-23, GM-CSF, TGF-β). Finally, we also focus on key antibodies (rheu-matoid factor, anti-citrullinated protein antibodies, anti-collagen II antibodies) and tissue-degrading enzymes (matrix metalloproteinases).

Target modulation and pharmacokinetics/pharmacodynamics translation of the BTK inhibitor poseltinib for model-informed phase II dose selection

The selective Bruton tyrosine kinase (BTK) inhibitor poseltinib has been shown to inhibit the BCR signal transduction pathway and cytokine production in B cells (Park et al.Arthritis Res. Ther.18, 91, 10.1186/s13075-016-0988-z, 2016). This study describes the translation of nonclinical research studies to a phase I clinical trial in healthy volunteers in which pharmacokinetics (PKs) and pharmacodynamics (PDs) were evaluated for dose determination. The BTK protein kinase inhibitory effects of poseltinib in human peripheral blood mononuclear cells (PBMCs) and in rats with collagen-induced arthritis (CIA) were evaluated. High-dimensional phosphorylation analysis was conducted on human immune cells such as B cells, CD8 + memory cells, CD4 + memory cells, NK cells, neutrophils, and monocytes, to map the impact of poseltinib on BTK/PLC and AKT signaling pathways. PK and PD profiles were evaluated in a first-in-human study in healthy donors, and a PK/PD model was established based on BTK occupancy. Poseltinib bound to the BTK protein and modulated BTK phosphorylation in human PBMCs. High-dimensional phosphorylation analysis of 94 nodes showed that poseltinib had the highest impact on anti-IgM + CD40L stimulated B cells, however, lower impacts on anti-CD3/CD-28 stimulated T cells, IL-2 stimulated CD4 + T cells and NK cells, M-CSF stimulated monocytes, or LPS-induced granulocytes. In anti-IgM + CD40L stimulated B cells, poseltinib inhibited the phosphorylation of BTK, AKT, and PLCγ2. Moreover, poseltinib dose dependently improved arthritis disease severity in CIA rat model. In a clinical phase I trial for healthy volunteers, poseltinib exhibited dose-dependent and persistent BTK occupancy in PBMCs of all poseltinib-administrated patients in the study. More than 80% of BTK occupancy at 40 mg dosing was maintained for up to 48 h after the first dose. A first-in-human healthy volunteer study of poseltinib established target engagement with circulating BTK protein. Desirable PK and PD properties were observed, and a modeling approach was used for rational dose selection for subsequent trials. Poseltinib was confirmed as a potential BTK inhibitor for the treatment of autoimmune diseases.

Trial registration: This article includes the results of a clinical intervention on human participants [NCT01765478].

Infliximab prevents systemic bone loss and suppresses tendon inflammation in a collagen-induced arthritis rat model

Reduced Bone Mineral Density (BMD) and tendon abnormalities, such as tenosynovitis and enthesitis, are prevalent comorbidities in patients with rheumatoid arthritis (RA). The aim of the present study was to investigate the effect of chronic treatment with infliximab on BMD and tendon inflammation in an animal model of inflammatory arthritis. Collagen-Induced Arthritis (CIA) was induced in rats, followed by long-term intraperitoneal administration of infliximab. Two additional groups of animals received methotrexate either as a monotherapy or as a co-treatment to infliximab. BMD was evaluated by Micro-Computed Tomography (Micro-CT) and bone histological examination. Tendon inflammation was assessed histologically and by quantitative ELISA analysis of pro-inflammatory cytokines in tendon tissues. Both methotrexate and infliximab treatment alleviated joint inflammation and reduced paw edema. Infliximab-treated animals exhibited an improved trabecular microarchitecture on micro-CT and histological analysis compared to both non-treated and methotrexate-treated animals. Infliximab almost reversed the pathological changes in tendons induced by CIA. Finally, we observed statistically significant declines in tendon TNF-a and IL-23 levels after infliximab treatment. Our study provides evidence that infliximab prevents arthritis-related osteoporosis and suppresses tendon inflammation in an animal model of inflammatory arthritis, in addition to controlling disease activity. These findings offer perspectives for the management of osteoporosis and enthesitis in RA.

Anti-Inflammatory and Antiarrhythmic Effects of Beta Blocker in a Rat Model of Rheumatoid Arthritis

Background

Patients with rheumatoid arthritis are at twice the risk of ventricular arrhythmia and sudden cardiac death as the general population. We hypothesize that β‐blocker treatment of rheumatoid arthritis is antiarrhythmic by producing synergistic anticatecholaminergic and anti‐inflammatory effects.

Methods and Results

Collagen‐induced arthritis (CIA) was induced in Lewis rats by immunization with type II collagen in Freund's incomplete adjuvant. The treatment with propranolol (4 mg/kg) started on the first day of immunization. We evaluated the ventricular vulnerability to ventricular arrhythmia using in vivo programmed stimulation and performed ex vivo optical mapping to measure the electrical remodeling of the heart. The ventricular tissue was further processed for immunohistochemical staining and protein array analysis. The assessment of ventricular vulnerability showed that the number and duration of the induced ventricular arrhythmia episodes were increased in CIA rats, which were improved with propranolol treatment. The sympathovagal index and the plasma level of catecholamines significantly increased in CIA rats, whereas the use of propranolol attenuated sympathetic hyperactivity. In the optical mapping study, electrical remodeling, characterized by prolonged action potential duration, slow conduction velocity, and steepened action‐potential duration restitution, were noted in CIA rats and reversed in the propranolol‐treatment group. The propranolol treatment was associated with decreases in paw thickness, fewer inflammatory cell infiltrations in the heart, reduced levels of cardiac inflammatory cytokines, and less cardiac fibrosis as compared with the CIA group.

Conclusions

CIA increased ventricular arrhythmia vulnerability through sympathetic hyperinnervation and proarrhythmic ventricular electrophysiological remodeling. Treatment with propranolol in CIA rats was both anti‐inflammatory and antiarrhythmic.

Investigation of the curative effects of palm vitamin E tocotrienols on autoimmune arthritis disease in vivo

The tocotrienol-rich fraction (TRF) from palm oil contains vitamin E, which possesses potent antioxidant and anti-inflammatory activities. Rheumatoid arthritis (RA) is a chronic joint inflammatory disease characterised by severe joint pain, cartilage destruction, and bone erosion owing to the effects of various pro-inflammatory mediators and cytokines. Here, we investigated the therapeutic effects of TRF in a rat model of collagen-induced arthritis (CIA). Arthritis was induced by a single intradermal injection of collagen type II in Dark Agouti (DA) rats. Rats were then treated with or without TRF by oral gavage from day 28 after the first collagen injection. Arthritic rats supplemented with TRF showed decreased articular index scores, ankle circumferences, paw volumes, and radiographic scores when compared with untreated rats. The untreated arthritic rats showed higher plasma C-reactive protein levels (p < 0.05) and production of pro-inflammatory cytokines than arthritic rats fed TRF. Moreover, there was a marked reduction in the severity of histopathological changes observed in arthritic rats treated with TRF compared with that in untreated arthritic rats. Overall, the results show that TRF had beneficial effects in this rat model of RA.