Macrophage activation syndrome as part of systemic juvenile idiopathic arthritis: diagnosis, genetics, pathophysiology and treatment

Macrophage activation syndrome (MAS) is a severe, frequently fatal complication of systemic juvenile idiopathic arthritis (sJIA) with features of hemophagocytosis leading to coagulopathy, pancytopenia, and liver and central nervous system dysfunction. MAS is overt in 10% of children with sJIA but occurs subclinically in another 30-40%. It is difficult to distinguish sJIA disease flare from MAS. Development of criteria for establishing MAS as part of sJIA are under way and will hopefully prove sensitive and specific. Mutations in cytolytic pathway genes are increasingly being recognized in children who develop MAS as part of sJIA. Identification of these mutations may someday assist in MAS diagnosis. Defects in cytolytic genes have provided murine models of MAS to study pathophysiology and treatment. Recently, the first mouse model of MAS not requiring infection but rather dependent on repeated stimulation through Toll-like receptors was reported. This provides a model of MAS that may more accurately reflect MAS pathology in the setting of autoinflammation or autoimmunity. This model confirms the importance of a balance between pro- and anti-inflammatory cytokines. There has been remarkable progress in the use of anti-pro-inflammatory cytokine therapy, particularly against interleukin-1, in the treatment of secondary forms of MAS, such as in sJIA.

Glucocorticoids in paediatric rheumatology

Glucocorticoid (GC) drugs are the most potent anti-inflammatory agents available for the treatment of paediatric rheumatic diseases. These medications are used for the management of extra-articular features of systemic juvenile idiopathic arthritis and are the mainstay of therapy in children with juvenile systemic lupus erythematosus, juvenile dermatomyositis, and systemic vasculitis. The general objective of GC therapy is to limit the maximal dose and the exposure to the highest doses to what is needed to achieve disease control and, then, to gradually taper the dose until the minimum level sufficient to maintain disease quiescence over time is reached. High-dose intravenous 'pulse' methylprednisolone administration is sometimes chosen to treat the most severe or acute manifestations of systemic inflammatory diseases. The rationale that underlies this treatment modality is to achieve an immediate, profound anti-inflammatory effect and to lessen toxicity associated with long-term continuous therapy in moderate to high daily doses. Intra-articular corticosteroid (IAC) injection is a safe and rapidly effective treatment for synovitis in children with JIA. Triamcinolone hexacetonide is the optimal corticosteroid preparation. Local injection therapy is used most frequently to treat oligoarthritis, but the strategy of performing multiple IAC injections to induce disease remission, while simultaneously initiating therapy with second-line or biologic agents, has been proposed also for children with polyarticular JIA. Administration of GCs is associated with potentially deleterious adverse effects, some of which can be irreversible. This highlights the need of a judicious use of these medications and a careful monitoring of their toxicity.

EULAR recommendations for vaccination in paediatric patients with rheumatic diseases

Evidence-based recommendations for vaccination of paediatric patients with rheumatic diseases (PaedRD) were developed by following the EULAR standardised procedures for guideline development. The EULAR task force consisted of (paediatric) rheumatologists/immunologists, one expert in vaccine evaluation, one expert in public health and infectious disease control, and one epidemiologist. A systematic literature review was conducted in MEDLINE, EMBASE, and abstracts of the EULAR and American College of Rheumatology meetings of 2008/9. The level of evidence and strength of recommendation were based on customary scoring systems. Delphi voting was applied to assess the level of agreement between task force members. 107 papers and eight abstracts were used. The majority of papers considered seasonal influenza (41) or pneumococcal (23) vaccination. 26 studies were performed specifically in paediatric patients, and the majority in adult rheumatoid arthritis and systemic lupus erythematosus patients. Fifteen recommendations were developed with an overall agreement of 91.7%. More research is needed on the safety and immunogenicity of (live-attenuated) vaccination in PaedRD, particularly in those using biologicals, and the effect of vaccination on prevention of infections.

A reappraisal of intra-articular corticosteroid therapy in juvenile idiopathic arthritis

Intraarticular corticosteroid (IAC) injection is a safe and rapidly effective treatment for synovitis in children with juvenile idiopathic arthritis (JIA). This procedure can be performed in an ambulatory care setting using local anaesthesia, with or without conscious sedation. Younger children, or those candidate to multiple injections, require general anaesthesia. Triamcinolone hexacetonide is the optimal corticosteroid preparation. However, for smaller joints or joints that are not easy to assess clinically, use of a more soluble corticosteroid drug is advised. Imaging guidance may facilitate accurate placement of the needle within the joint space. Use of ultrasound for this purpose has gained increasing popularity in the recent years. IAC injections are used most frequently to treat oligoarthritis, but the strategy of performing multiple IAC injections to induce disease remission, while simultaneously initiating therapy with second-line or biologic agents, has been proposed also for children with polyarticular JIA. However, the current place of IAC therapy in the management of children with JIA is uncertain due to the lack of controlled studies. Furthermore, it is still unknown whether this therapy has a disease-modifying effect over the long-term. This review summarises the present information about the use of IAC therapy in children with JIA.