Iain B. McInnes

The Pathogenesis of Rheumatoid Arthritis

The increased understanding of the immune mechanisms of rheumatoid arthritis has led to the development of a considerable number of new therapeutic agents that alter the natural history of the disease and reduce mortality.

Treating rheumatoid arthritis to target: recommendations of an international task force

Background Aiming at therapeutic targets has reduced the risk of organ failure in many diseases such as diabetes or hypertension. Such targets have not been defined for rheumatoid arthritis (RA). Objective To develop recommendations for achieving optimal therapeutic outcomes in RA. Methods A task force of rheumatologists and a patient developed a set of recommendations on the basis of evidence derived from a systematic literature review and expert opinion; these were subsequently discussed, amended and voted upon by >60 experts from various regions of the world in a Delphi-like procedure. Levels of evidence, strength of recommendations and levels of agreement were derived. Results The treat-to-target activity resulted in 10 recommendations. The treatment aim was defined as remission with low disease activity being an alternative goal in patients with long-standing disease. Regular follow-up (every 1–3 months during active disease) with appropriate therapeutic adaptation to reach the desired state within 3 to a maximum of 6 months was recommended. Follow-up examinations ought to employ composite measures of disease activity which include joint counts. Additional items provide further details for particular aspects of the disease. Levels of agreement were very high for many of these recommendations (≥9/10). Conclusion The 10 recommendations are supposed to inform patients, rheumatologists and other stakeholders about strategies to reach optimal outcomes of RA based on evidence and expert opinion.

Cytokines in the pathogenesis of rheumatoid arthritis

Cytokines regulate a broad range of inflammatory processes that are implicated in the pathogenesis of rheumatoid arthritis. In rheumatoid joints, it is well known that an imbalance between pro- and anti-inflammatory cytokine activities favours the induction of autoimmunity, chronic inflammation and thereby joint damage. However, it remains less clear how cytokines are organized within a hierarchical regulatory network, and therefore which cytokines may be the best targets for clinical intervention a priori. Here, we discuss the crucial effector function of cytokines in the immunological processes that are central to the pathogenesis of rheumatoid arthritis.

EULAR evidence-based recommendations for cardiovascular risk management in patients with rheumatoid arthritis and other forms of inflammatory arthritis

Objectives: To develop evidence-based EULAR recommendations for cardiovascular (CV) risk management in patients with rheumatoid arthritis (RA), ankylosing spondylitis (AS) and psoriatic arthritis (PsA). Methods: A multidisciplinary expert committee was convened as a task force of the EULAR Standing Committee for Clinical Affairs (ESCCA), comprising 18 members including rheumatologists, cardiologists, internists and epidemiologists, representing nine European countries. Problem areas and related keywords for systematic literature research were identified. A systematic literature research was performed using MedLine, Embase and the Cochrane library through to May 2008. Based on this literature review and in accordance with the EULAR’s “standardised operating procedures”, the multidisciplinary steering committee formulated evidence-based and expert opinion-based recommendations for CV risk screening and management in patients with inflammatory arthritis. Results: Annual CV risk assessment using national guidelines is recommended for all patients with RA and should be considered for all patients with AS and PsA. Any CV risk factors identified should be managed according to local guidelines. If no local guidelines are available, CV risk management should be carried out according to the SCORE function. In addition to appropriate CV risk management, aggressive suppression of the inflammatory process is recommended to further lower the CV risk. Conclusions: Ten recommendations were made for CV risk management in patients with RA, AS and PsA. The strength of the recommendations differed between RA on the one hand, and AS and PsA, on the other, as evidence for an increased CV risk is most compelling for RA.

Explaining How “High-Grade” Systemic Inflammation Accelerates Vascular Risk in Rheumatoid Arthritis

There is intense interest in mechanisms whereby low-grade inflammation could interact with conventional and novel vascular risk factors to promote the atheromatous lesion. Patients with rheumatoid arthritis (RA), who by definition manifest persistent high levels of inflammation, are at greater risk of developing cardiovascular disease. Mechanisms mediating this enhanced risk are ill defined. On the basis of available evidence, we argue here that the systemic inflammatory response in RA is critical to accelerated atherogenesis operating via accentuation of established and novel risk factor pathways. By implication, long-term suppression of the systemic inflammatory response in RA should be effective in reducing risk of coronary heart disease. Early epidemiological observational and clinical studies are commensurate with this hypothesis. By contrast, risk factor modulation with conventional agents, such as statins, may provide unpredictable clinical benefit in the context of uncontrolled systemic inflammatory parameters. Unraveling such complex relationships in which exaggerated inflammation-risk factor interactions are prevalent may elicit novel insights to effector mechanisms in vascular disease generally.

Trial of Atorvastatin in Rheumatoid Arthritis (TARA): double-blind, randomised placebo-controlled trial

BACKGROUND Rheumatoid arthritis is characterised by inflammatory synovitis, articular destruction, and accelerated atherogenesis. HMG-CoA (3-hydroxy-3-methylglutarylcoenzyme A) reductase inhibitors (statins) mediate clinically significant vascular risk reduction in patients without inflammatory disease and might have immunomodulatory function. We postulated that statins might reduce inflammatory factors in rheumatoid arthritis and modify surrogates for vascular risk. METHODS 116 patients with rheumatoid arthritis were randomised in a double-blind placebo-controlled trial to receive 40 mg atorvastatin or placebo as an adjunct to existing disease-modifying antirheumatic drug therapy. Patients were followed up over 6 months and disease activity variables and circulating vascular risk factors were measured. Coprimary outcomes were change in disease activity score (DAS28) and proportion meeting EULAR (European League Against Rheumatism) response criteria. Analysis was by intention to treat. FINDINGS At 6 months, DAS28 improved significantly on atorvastatin (-0.5, 95% CI -0.75 to -0.25) compared with placebo (0.03, -0.23 to 0.28; difference between groups -0.52, 95% CI -0.87 to -0.17, p=0.004). DAS28 EULAR response was achieved in 18 of 58 (31%) patients allocated atorvastatin compared with six of 58 (10%) allocated placebo (odds ratio 3.9, 95% CI 1.42-10.72, p=0.006). C-reactive protein and erythrocyte sedimentation rate declined by 50% and 28%, respectively, relative to placebo (p<0.0001, p=0.005, respectively). Swollen joint count also fell (-2.69 vs -0.53; mean difference -2.16, 95% CI -3.67 to -0.64, p=0.0058). Adverse events occurred with similar frequency in patients allocated atorvastatin and placebo. INTERPRETATION These data show that statins can mediate modest but clinically apparent anti-inflammatory effects with modification of vascular risk factors in the context of high-grade autoimmune inflammation.

Disease-associated functions of IL-33: the new kid in the IL-1 family

Interleukin-33 (IL-33), a newly described member of the IL-1 family, is expressed by many cell types following pro-inflammatory stimulation and is thought to be released on cell lysis. The IL-33 receptor, consisting of ST2 and IL-1 receptor accessory protein, is also widely expressed, particularly by T helper 2 (TH2) cells and mast cells. IL-33 is host-protective against helminth infection and reduces atherosclerosis by promoting TH2-type immune responses. However, IL-33 can also promote the pathogenesis of asthma by expanding TH2 cells and mediate joint inflammation, atopic dermatitis and anaphylaxis by mast cell activation. Thus IL-33 could be a new target for therapeutic intervention across a range of diseases.

Evidence that cytokines play a role in rheumatoid arthritis

A large number of cytokines are active in the joints of patients with rheumatoid arthritis (RA). It is now clear that these cytokines play a fundamental role in the processes that cause inflammation, articular destruction, and the comorbidities associated with RA. Following the success of TNF-alpha blockade as a treatment for RA, other cytokines now offer alternative targets for therapeutic intervention or might be useful as predictive biomarkers of disease. In this Review, we discuss the biologic contribution and therapeutic potential of the major cytokine families to RA pathology, focusing on molecules contained within the TNF-alpha, IL-1, IL-6, IL-23, and IL-2 families.

A proinflammatory role for IL-18 in rheumatoid arthritis

IL-18 is a novel cytokine with pleiotropic activities critical to the development of T-helper 1 (Th1) responses. We detected IL-18 mRNA and protein within rheumatoid arthritis (RA) synovial tissues in significantly higher levels than in osteoarthritis controls. Similarly, IL-18 receptor expression was detected on synovial lymphocytes and macrophages. Together with IL-12 or IL-15, IL-18 induced significant IFN-gamma production by synovial tissues in vitro. IL-18 independently promoted GM-CSF and nitric oxide production, and it induced significant TNF-alpha synthesis by CD14(+) macrophages in synovial cultures; the latter effect was potentiated by IL-12 or IL-15. TNF-alpha and IFN-gamma synthesis was suppressed by IL-10 and TGF-beta. IL-18 production in primary synovial cultures and purified synovial fibroblasts was, in turn, upregulated by TNF-alpha and IL-1beta, suggesting that monokine expression can feed back to promote Th1 cell development in synovial membrane. Finally, IL-18 administration to collagen/incomplete Freunds adjuvant-immunized DBA/1 mice facilitated the development of an erosive, inflammatory arthritis, suggesting that IL-18 can be proinflammatory in vivo. Together, these data indicate that synergistic combinations of IL-18, IL-12, and IL-15 may be of importance in sustaining both Th1 responses and monokine production in RA.

The role of interleukin-15 in T-cell migration and activation in rheumatoid arthritis.

Interleukin 15 (IL–15) is a novel cytokine with interleukin–2–like activity. It is also a potent T–lymphocyte chemoattractant. Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by the presence of activated T lymphocytes, macrophages and synoviocytes in the synovial membrane. The mechanisms of T–cell activation in RA are currently unclear. We report the presence of high concentrations of IL–15 in rheumatoid arthritis (RA) synovial fluid and have demonstrated its expression in the synovial membrane lining layer by immunohistochemistry. RA synovial fluids were found to contain chemotactic activity, which was attributable in part to the presence of IL–15. Moreover, in a murine model, injection of recombinant IL–15 was found to induce a local tissue inflammatory infiltrate consisting predominantly of T lymphocytes. Synovial fluid T lymphocytes proliferate in response to IL–15, demonstrating that continued responsiveness to IL–15 is a feature of T cells after entry into the synovial compartment. These data suggest that IL–15 can recruit and activate T lymphocytes into the synovial membrane, thereby contributing to RA pathogenesis.