This study provides Class IV evidence that in pediatric autoimmune and inflammatory CNS disorders, rituximab improves neurologic outcomes with a 7.6% risk of adverse infections.

Kawasaki disease (KD) is an acute self-limiting inflammatory disorder, associated with vasculitis, affecting predominantly medium-sized arteries, particularly the coronary arteries. In developed countries KD is the commonest cause of acquired heart disease in childhood. The aetiology of KD remains unknown, and it is currently believed that one or more as yet unidentified infectious agents induce an intense inflammatory host response in genetically susceptible individuals. Genetic studies have identified several susceptibility genes for KD and its sequelae in different ethnic populations, including FCGR2A, CD40, ITPKC, FAM167A-BLK and CASP3, as well as genes influencing response to intravenous immunoglobulin (IVIG) and aneurysm formation such as FCGR3B, and transforming growth factor (TGF) β pathway genes. IVIG and aspirin are effective therapeutically, but recent clinical trials and meta-analyses have demonstrated that the addition of corticosteroids to IVIG is beneficial for the prevention of coronary artery aneurysms (CAA) in severe cases with highest risk of IVIG resistance. Outside of Japan, however, clinical scores to predict IVIG resistance perform suboptimally. Furthermore, the evidence base does not provide clear guidance on which corticosteroid regimen is most effective. Other therapies, including anti-TNFα, could also have a role for IVIG-resistant KD. Irrespective of these caveats, it is clear that therapy that reduces inflammation in acute KD, improves outcome. This paper summarises recent advances in the understanding of KD pathogenesis and therapeutics, and provides an approach for managing KD patients in the UK in the light of these advances.

The mechanisms by which anti-neutrophil cytoplasmic antibodies (ANCAs) may contribute to the pathogenesis of ANCA-associated vasculitis are not well understood. In this study, both polyclonal ANCAs isolated from patients and chimeric proteinase 3-ANCA induced the release of neutrophil microparticles from primed neutrophils. These microparticles expressed a variety of markers, including the ANCA autoantigens proteinase 3 and myeloperoxidase. They bound endothelial cells via a CD18-mediated mechanism and induced an increase in endothelial intercellular adhesion molecule-1 expression, production of endothelial reactive oxygen species, and release of endothelial IL-6 and IL-8. Removal of the neutrophil microparticles by filtration or inhibition of reactive oxygen species production with antioxidants abolished microparticle-mediated endothelial activation. In addition, these microparticles promoted the generation of thrombin. In vivo, we detected more neutrophil microparticles in the plasma of children with ANCAassociated vasculitis compared with that in healthy controls or those with inactive vasculitis. Taken together, these results support a role for neutrophil microparticles in the pathogenesis of ANCA-associated vasculitis, potentially providing a target for future therapeutics.

Objective. To describe the clinical features, genotype, and treatment in a series of subjects with confirmed adenosine deaminase 2 (ADA2) deficiency.Methods. All symptomatic subjects were referred for genetic testing for suspected ADA2 deficiency; relatives of index cases were also screened. Demographic, clinical, and laboratory characteristics and treatments were recorded. Genetic analyses included whole-exome sequencing in 4 subjects and Sanger sequencing of CECR1 (the gene for cat eye syndrome chromosome region candidate 1) in all subjects. Assays for ADA2 enzyme activity and quantitative polymerase chain reaction analysis of CECR1 messenger RNA (mRNA) were also performed.Results. We identified 15 subjects with ADA2 deficiency, 5 of whom were asymptomatic (relatives of index cases; ages 5-42 years). Homozygous or compound heterozygous mutations in CECR1 were identified in all subjects. Phenotypic manifestations in the patients with symptomatic ADA2 deficiency included livedo racemosa (73.3%), neurologic involvement (53.3%), and immunodeficiency (46.7%). CECR1 mRNA expression in 8 subjects, including 5 who were presymptomatic, was significantly lower than in healthy controls (P 5 0.0016). Subjects with ADA2 deficiency (with or without symptoms) also had lower ADA2 enzyme activity compared to healthy pediatric controls (P < 0.0001) and patients with sporadic (nonfamilial) childhood polyarteritis nodosa (PAN) without CECR1 mutation (P 5 0.0108). Anti2tumor necrosis factor therapy was required in 9 of the 10 symptomatic subjects.Conclusion. The clinical manifestations of ADA2 deficiency ranged in severity from limited cutaneous involvement to severe multisystemic vasculitis; one-third of our cases (5 of 15) were currently asymptomatic, and required close monitoring. We recommend CECR1 screening for unaffected siblings of index cases, cases of familial vasculitis, and cases of PAN that is resistant to standard treatment.

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Standing et al. report a novel autoinflammatory disease caused by a homozygous missense mutation in the actin-regulating protein WDR1. The disease is characterized by periodic fevers, immunodeficiency, and thrombocytopenia, with increased polymerized actin in immune cells and increased IL-18 secretion.

IntroductionTakayasu arteritis (TA) is an idiopathic large-vessel vasculitis affecting the aorta and its major branches. Although the disease rarely affects children, it does occur, even in infants. The objective of this study was to evaluate the clinical features, disease activity, treatment and outcome of childhood TA in a tertiary UK centre.MethodsWe analysed a retrospective case series of children fulfilling the TA classification criteria of the European League against Rheumatism, the Paediatric Rheumatology European Society and the Paediatric Rheumatology International Trials Organisation. Data regarding demographics, clinical features, treatments and outcomes were recorded. Descriptive statistics are expressed as median and range. Fisher’s exact test was used for group comparisons. The Paediatric Vasculitis Activity Score (PVAS), Paediatric Vasculitis Damage Index (PVDI), Disease Extent Index-Takayasu (DEI.Tak) and Indian Takayasu Arteritis Activity Score (ITAS2010) were calculated retrospectively.ResultsA total of 11 children (64% female) with age at diagnosis of 11.8 (1.3 to 17) years were identified over a 23-year period. The median time to diagnosis was 17 (0 to 132) months. The most common clinical features at presentation were arterial hypertension (72.7%), systemic features (36%) and cardiovascular (45%), neurological (36%), pulmonary (27%), skin (9%), renal (9%) and gastrointestinal (9%) involvement. At presentation, PVAS was 5/63 (1 to 13); DEI.Tak was 7/81 (2 to 12) and ITAS2010 was 9/57 (6 to 20). Treatment included corticosteroids (81.8%), combined with methotrexate in most cases (72.7%). Cyclophosphamide (36.4%) and biologic agents (45.5%) were reserved for severe and/or refractory cases. PVDI at latest follow-up was 5.5/72 (3 to 15). Mortality was 27%. Young age at disease onset (<5 years old) and permanent PVDI scores ≥3 were significantly associated with mortality risk (P = 0.024).ConclusionTA is a rare and potentially life-threatening large-vessel vasculitis. Improved awareness of TA is essential to secure a timely diagnosis. Although the evidence base for the treatment of TA in children is weak, we found that it is essential to treat it aggressively because our data emphasise that the mortality and morbidity in the paediatric population remains high.Electronic supplementary materialThe online version of this article (doi:10.1186/s13075-015-0545-1) contains supplementary material, which is available to authorized users.

Results. Sixty-nine children with PAN were identified; 55% were male, and their median age was 8.5 years (range 0.9-15.8 years). Their clinical features at presentation were fever (87%), myalgia (83%), skin (88%), renal (19%), severe gastrointestinal (GI) (10%), and neurologic (10%) involvement. The PVAS at presentation was 9 of 63 (range 4-24). Histopathologic analysis of the skin showed necrotizing vasculitis in biopsy samples from 40 of 50 children. Results of selective visceral arteriography suggested the presence of PAN in 96% of patients. Treatment included cyclophosphamide and corticosteroids (83%), plasma exchange (9%), and biologic agents (after 2002; 13%). The relapse rate was 35%, and the mortality rate was 4%. Severe GI involvement was associated with increased risk of relapse (P ‫؍‬ 0.031), while longer time to induce remission (P ‫؍‬ 0.022) and increased cumulative dose of cyclophosphamide (P ‫؍‬ 0.005) were associated with lower relapse risk.Conclusion. Childhood PAN is a severe inflammatory disease of insidious onset and variable clinical presentation. Relapses occurred more frequently in those with severe GI involvement. A higher cumulative dose of cyclophosphamide was associated with a lower risk of relapse.