Gaëlle Clavel

Recent data on the role for angiogenesis in rheumatoid arthritis

Angiogenesis is central to the development and perpetuation of rheumatoid synovitis. Vascular endothelial growth factor (VEGF), the main mediator of angiogenesis, is found in the synovial fluid and serum of patients with rheumatoid arthritis (RA), and its expression is correlated with disease severity. Compelling evidence that VEGF is involved in synovitis has been obtained from experimental models of RA. In particular, VEGF inhibition by synthetic compounds (e.g. TNP-470) or by naturally occurring factors (e.g., the soluble VEGF receptor) produce therapeutic effects. Angiopoietin-1, a recently discovered growth factor specific for neovascularization, is expressed within the rheumatoid synovium and may be stimulated by TNF-alpha. Other compounds, including integrins, fibroblast growth factor, and proinflammatory cytokines contribute to joint angiogenesis and, therefore, to the development of rheumatoid synovitis. Assessing vascularity may prove useful for evaluating or even predicting bone destruction. Furthermore, inhibition of angiogenesis may prove useful as an adjunct to current anti-inflammatory treatments.

Musculoskeletal Ultrasonography in Healthy Subjects and Ultrasound Criteria for Early Arthritis (The ESPOIR Cohort)

Objective. To confirm the occurrence of bone erosions and synovitis in healthy subjects detectable by ultrasound (US) and to establish US criteria for early arthritis. Methods. Our study involved 127 healthy subjects matched with a cohort of patients with early arthritis (the ESPOIR cohort). The second and fifth metacarpophalangeal (MCP) joints and the fifth metatarsophalangeal (MTP) joint of both hands and feet were assessed with US to detect bone erosion; and the second, third, fourth, and fifth MCP and the fifth MTP were evaluated for synovial thickening in B-mode US and synovial vascularity in power Doppler. Bone erosion and synovitis were defined according to the Outcome Measures in Rheumatology Clinical Trials consensus. Results. Bone erosion and grade 2–3 synovial thickening in B-mode were detected in 11% and 9% of healthy subjects. To consider the diagnosis of early arthritis, a cutoff at 1 case of synovial thickening in B-mode enabled discrimination between patients with early arthritis and healthy subjects, with a good sensitivity of 74.8% (95% CI 67.2%–82.3%) and a high specificity of 90.5% (95% CI 85.4%–95.6%). If higher specificity is required to confirm the diagnosis of early arthritis, cutoff at 2 cases of synovial thickening in B-mode or at 2 cases of bone erosion gave optimal results, with specificity of 98.4% (95% CI 96.2%–100%) and 100%, respectively, and lower sensitivity of 59.8% (95% CI 51.2%–68.3%) and 17% (95% CI 10.5%–23.5%) (area under the curve = 0.85 for synovitis and 0.63 for bone erosion). Neither the combination of power Doppler signal plus bone erosion, nor bone erosions plus synovial thickening on the same joint, were seen in healthy subjects. Conclusion. A single case of bone erosion or synovial thickening in B-mode is common in healthy subjects. However, more than 1 case of synovial thickening in B-mode or bone erosion is a strong argument for the diagnosis of early inflammatory arthritis.

Blood vessels, a potential therapeutic target in rheumatoid arthritis?

New micro-vessels formation within synovium and macro-vessels endothelial damage with atheroma are two major features of rheumatoid arthritis, the former related to the articular involvement of the disease, the latter to its main systemic complication. The similarities between pannus development and solid tumors growth, and the efficacy of anti-angiogenic treatments in oncology, opened the perspective of directly targeting angiogenesis in arthritis. Nevertheless, despite the success of different anti-angiogenic therapeutic strategies in many arthritis experimental models, the application in human disease is still lacking. Recent data suggest that synovial neoangiogenesis and macro-vessels endothelial damage might be two linked phenomena. While synovial angiogenesis seems to be detrimental to endothelial damage repair, even anti-angiogenic treatments might paradoxically aggravate macro-vascular disease, especially in the context of uncontrolled inflammation. These elements induce to further explore the interconnections between inflammation and angiogenesis on one side and between micro- and macro-vascular diseases on the other, in order to establish the proper way to therapeutically target blood vessels in rheumatoid arthritis.

Interleukin newcomers creating new numbers in rheumatology: IL-34 to IL-38.

The development of innovative technologies is steadily increasing the body of knowledge on molecules involved in physiological functions. Thus, several interleukins (ILs) have been identified and characterized in the past few years. Here, we detail the structural and functional characteristics of IL-34 to IL-38 with special attention to their involvement in inflammatory joint disease. IL-34 chiefly increases osteoclast activation and proliferation and therefore, it plays a direct role in bone destruction as seen in rheumatoid arthritis (RA). Regulatory T-cells (Tregs) express IL-35, which therefore exerts anti-inflammatory effects by restoring Treg suppressive capabilities and by inhibiting the Th17 pathway. IL-37 has anti-inflammatory effects mediated by a negative feedback loop that decreases the release of pro-inflammatory cytokines. IL-36 belongs to the IL-1 family and has three different forms. Although this cytokine has been chiefly studied in psoriasis and psoriatic arthritis, it also exerts pro-inflammatory effects in RA. The specific IL-36 antagonist, IL-36Ra binds to the IL-36 receptor, thereby, preventing signal transduction. Finally, IL-38 is a recently identified cytokine whose effect may resemble that of IL-36Ra as it binds to the IL-36 receptor and inhibits its effects, particularly the Th17-response. Although the exact roles for these cytokines awaits elucidation, the current improvements in our knowledge of the mechanisms that regulate chronic inflammatory conditions, such as RA may lead to the identification of new treatment targets.

Targeting IL-6 for the treatment of rheumatoid arthritis: Phase II investigational drugs

Introduction: IL-6 is a key cytokine in the pathogenesis of rheumatoid arthritis (RA). The clinical efficacy of tocilizumab (TCZ), a humanized anti-IL6-receptor mAb, confirmed the value of IL-6 blockade in this disease. A number of new anti-IL-6 biologics are currently in Phase I – III of clinical development for RA. Areas covered: This article reviews the available results from Phase II trials of investigational anti-IL-6 agents in RA. The authors discuss the potential relevance of alternative IL-6-blocking agents, with regard to their specific molecular targets in IL-6 signaling pathways and to the main open questions in the clinical research agenda for anti-IL-6 biologics. Expert opinion: The results of Phase II trials of new anti-IL-6 biologics show promising results in terms of efficacy. The most frequently reported adverse events were not unexpected based on previous experience with TCZ. Further evidence is needed to appraise whether the difference in molecular structure or in the specific target of new anti-IL-6 biologics might result in added therapeutic value over TCZ. New data from Phase III trials that provides a head-to-head comparison against TCZ and anti-TNF agents with or without methotrexate background treatment are expected in the future.

Ultrasound and Doppler micro-imaging in a model of rheumatoid arthritis in mice

Objectives: The evaluation of joints in arthritis using conventional ultrasonography is not really feasible in mice because of the small size of the animal. However, compared with classical analysis (clinical and histological examination) it is a non-invasive method that allows follow-up of the same animal throughout the whole experiment. Moreover, power Doppler allows the study of blood flow that reflects inflammatory activity within the synovium of arthritic joints. Our aim was to determine whether ultrasonography analysis could accurately detect arthritis lesions in a mouse model of rheumatoid arthritis, namely collagen-induced arthritis. Methods: Collagen-induced arthritis was induced in 28 mice by immunising with collagen type II. Every week for 8 weeks, ultrasonography and Doppler analysis were performed on knees and ankles of all mice using the ultrasound biomicroscope (UBM), which is particularly dedicated to studying the mouse. Clinical and histological evaluations were performed as usual. Results: We established a semiquantitative analysis by setting an UBM scoring. UBM grades were correlated to clinical and histological scores of arthritis. Vascularisation within the synovium could be estimated by power Doppler analysis and a semiquantitative vascularisation scale was established, which allowed us to show a good correlation between vascularisation scores and histological or clinical scores of arthritis. Conclusions: This is one of the first studies that shows it is possible to visualise a selected set of joints in a small animal using UBM analysis. It provides new perspectives in evaluating experimental models of rheumatoid arthritis and other joint diseases.

Developments with investigational Janus kinase inhibitors for rheumatoid arthritis

The evolving therapeutic landscape for rheumatoid arthritis has seen three major breakthroughs over the last decades, each corresponding to a step in the comprehension of the disease [1]. First, understanding of the immunological basis of the disease has led to the systematic and precocious use of immunosuppressants, called conventional disease-modifyingdrugs (csDMARDs), like methotrexate (MTX), that are still the cornerstone of RA treatment. Second, deeper comprehension of disease pathophysiology led to the development of targeted biological treatments (bDMARDs), monoclonal antibodies or soluble receptors, that block pro-inflammatory cytokines like TNF or IL-6, cellular populations, like mature B cells, or cellular interactions that are critical to T-cell activation. The development of orally available small molecules that inhibit intracellular signaling of cytokines and growth factors is the third major advance in the treatment of RA. These compounds are referred to as targeted synthetic DMARDs (tsDMARDs). The jakinibs are a novel family of inhibitors of the Janusassociated kinase (JAK) signaling pathway. The JAK/STAT (signal transducer and activators of transcription) system is a highly evolutionary conserved system that signals downstream type I and type II cytokine receptors (Figure 1) [2]. Tofacitinib, the first developed jakinib, was approved by the FDA in 2012 at the dose of 5 mg twice daily. Originally designed to be a JAK3-selective inhibitor, tofacitinib is considered a pan-JAK inhibitor that inhibits, in descending order of potency, JAK3, 1 and 2. Tofacitinib was developed in a wide phase 3 program, in which it was administered at 5 or 10 mg twice daily. In patients with established RA that were insufficient responders to csDMARDs [3–6] or bDMARds [6,7], tofactinib showed higher rates of clinical response vs. placebo both as monotherapy [6] and as add-on therapy to MTX or other csDMARDs [3–5]. In the latter setting showed similar efficacy to adalimumab as add-on therapy in MTX insufficient responders (to note, the study was not designed to formally test the noninferiority of tofacitinib vs. adalimumab tofacitinib) [3]. Tofacitinib is now approved for clinical use in over 40 countries worldwide, including USA, Japan, Russia, and Switzerland, while it failed to obtain marketing license in the European Union. The reasons for license refusal were unresolved safety concerns, mainly infections, which were dose-dependent, and the fact that the dose of 5 mg did not provide sufficient benefit in terms reduction of structural progression [5]. Nevertheless, a subsequent trial in early csDMARDs naïve RA showed that even at the dose of 5 mg, tofacitinib monotherapy was superior to MTX in preventing radiological progression [8]. In USA, tofacitinib was approved with a warning highlighting the risk of serious infections in particular tuberculosis and malignancy. Pooled analyses of phases 2, 3, and open-label extension studies confirmed the dose-dependency of the infectious risk but suggested that overall risk was comparable to that of RA patients on bDMARDs [9]. Additionally, it was shown that the rates and types of malignancies observed in clinical trials remained stable over time with increasing tofacitinib exposure and were within the expected range of patients with moderate-to-severe RA [10]. There was an increase in the rate of varicella–zoster virus (VZV) infections across the studies, consistent with inhibition of interferon IFN type I and II signaling (Figure 1). Other frequent events like dysplidemia and liver enzyme elevation are reminiscent of those seen on anti-IL-6 treatments [11] and are consistent with JAK1 inhibition. Increased rates of anemia and cytopenia, notably neutropenia, ascribed to inhibition of JAK2 signaling were also observed. To overcome potential limitations of generalized blockade of JAK signaling, other jakinibs with more restricted JAK specificities have been developed. There are currently five jakinibs between phases 2 and 3 of clinical development.

Progressive Multifocal Leukoencephalopathy and Rheumatoid Arthritis Treatments

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nervous system due to reactivation of the JC virus (JCV). PML is extremely uncommon despite the high prevalence of the virus in the general population. No specific treatment is available, and the prognosis is bleak. The diagnosis is based on brain imaging findings, detection of the JCV genome in cerebrospinal fluid samples and, in some cases, histological studies of the brain lesions. The pathophysiological mechanisms that drive the development of PML are incompletely understood. However, a consistent feature is the presence of a predisposing factor, most notably immunosuppression. The risk of developing PML varies with the underlying disease (e.g., HIV infection or autoimmune disease) and with the drugs used to treat them. Biologics have been ranked according to the risk of PML during their use. Natalizumab, a monoclonal antibody given to treat multiple sclerosis, is among the drugs associated with a high risk of PML. Patients given natalizumab are now closely monitored based on anti-JCV antibody titers and index values. In rheumatology, the expanding use of biologics has led to an increase in cases of PML, with rituximab being associated with the highest risk. Given the absence of specific recommendations, exhaustive registries and postmarketing observational studies are urgently needed to gauge the risk of PML according to the underlying disease and drug treatments, with the goal of defining optimal monitoring protocols.

Is it possible to identify early predictors of the future cost of chronic arthritis? The VErA project

This study was conducted to identify early predictors of the total cost of inflammatory arthritis (IA). One hundred and eighty patients affected by undifferentiated arthritis (UA) or rheumatoid arthritis (RA) were included in the French Very Early rheumatoid Arthritis (VErA) cohort between 1998 and 2001. Health economic data for 2003 were collected using a patient self‐questionnaire. Results were analysed in terms of direct, indirect and total costs in 2003 euros (2003€) for the population as a whole and in diagnostic subgroups. A payor perspective (the French National Health Insurance, in this case) was adopted. Multiple linear regression models were used to identify predictors of total cost from among the criteria assessed on recruitment. Results of the study showed that for the study population as a whole, the mean total cost was €4700 per patient. The costs attributable to the RA and UA sub‐groups were €5928 and €2424 per patient, respectively. In a univariate analysis, certain parameters were significantly correlated with a higher cost of illness. In the multivariate analysis, some of these parameters were further identified as being predictive of higher cost. Two strong significant, early predictors of total cost were identified: higher pain (P = 0.002) and the presence of rheumatoid factor (P = 0.004). In the RA sub‐group, lower grip strength of the dominant hand (P = 0.039) was another predictor of the illness’s subsequent economic impact. In conclusion, our data show that simple clinical and laboratory parameters can be used early in the course of IA to predict the condition’s impact on healthcare budgets.

A1.6 Vascular adhesion molecule VCAM-1 overexpression in collagen induced arthritis : a model for rheumatoid arthritis vascular dysfunction

Background and Objective Rheumatoid Arthritis (RA) patients are at risk of developing early coronary heart disease. Cardiovascular risk in RA is attributed to both traditional risk factors and to uncontrolled systemic in ammation over a long period. The aim of this study was to develop a model that would mimic both vascular dysfunction and articular inflammation in RA, using collagen induced arthritis (CIA). We mainly focused on VCAM-1 expression, early marker of vascular activation and dysfunction. Materials and Methods Arthritis was induced in 11 weeks old C57BL/6 mice with 2 injections (at day 0 and 21) of chicken type II collagen (cCII) emulsioned in complete Freund adjuvant (CFA). Half of mice were fed a fat-enriched diet (Western Diet (WD)) (n = 12) while the other half were fed a standard diet. Control mice (not immunised with cCII) were fed either WD (n = 12) or standard diet (n = 12). The aorta and synovial membrane were removed at day 105 after the first cCII immunisation. We analysed VCAM-1, IL-6 and IL-17 mRNA level in both the aorta and the synovium by real time quantitative PCR (qRT-PCR). VCAM-1 localisation in the aortic sinus layers (intima, media and adventitia) was determined by immunohistochemistry (IHC). Results Immunised mice fed either WD or standard diet had higher qRT-PCR VCAM-1 expression in aorta vs. non immunised mice (p<0.05). Although all mice groups, constitutively expressed VCAM-1 on aortic sinus endothelial cell monolayer, the whole intimal layer stained for VCAM-1 at IHC in both immunised mice (fed standard or western diet) as well as in non immunised mice fed WD. Conversely, the expression of IL-6 and IL-17 in the aorta was similar in all groups. Conclusion In CIA, C57BL6 mice display aortic inflammation characterised by VCAM-1 overexpression, independently from the diet (WD or standard diet). C57BL6 CIA might be a pertinent model to study the early mechanisms of large blood vessels vascular dysfunction in RA.