Pediatric antiphospholipid syndrome.

Antiphospholipid syndrome (APS) is a multisystem autoimmune condition characterized by vascular thromboses associated with persistently positive antiphospholipid antibodies. There is currently a paucity of data (incidence, prevalence, thrombosis risk, and effective treatment) in pediatric APS. The purpose of this report is to review the current literature on APS in children and neonates, identify the gaps in current knowledge, and suggest avenues for studies to fill those gaps.

Catch-up growth during tocilizumab therapy for systemic juvenile idiopathic arthritis: results from a phase III trial.

OBJECTIVE: To investigate the impact of tocilizumab treatment on growth and growth-related laboratory parameters in patients with systemic juvenile idiopathic arthritis (JIA) enrolled in a phase III clinical trial. METHODS: Patients with systemic JIA ages 2-17 years (n = 112) received tocilizumab in a 12-week, randomized, placebo-controlled period and a long-term open-label extension. Height velocity and standard deviation (SD) score; levels of insulin-like growth factor 1 (IGF-1), osteocalcin (OC), and C-telopeptide of type I collagen (CTX-I); and Juvenile Arthritis Disease Activity Score in 71 joints (JADAS-71) were measured in a post hoc analysis of 83 patients who never received growth hormone and did not reach Tanner stage 5 by the end of the first year of treatment. RESULTS: Patients had stunted growth at baseline (mean height SD score -2.2). During tocilizumab treatment, males (73%) and females (83%) experienced above-normal mean height velocities of 6.6 cm/year (P < 0.0001 versus World Health Organization norms). Mean height SD score increases during year 1 (0.29) and year 2 (0.31) were significant (both P < 0.0001). The mean SD score for IGF-1 levels increased significantly (-0.2 for year 1 and -0.1 for year 2 versus -1.0 at baseline; both P < 0.0001). Mean OC and CTX-I levels (both P < 0.0001) and the OC:CTX-I ratio (P = 0.014) significantly increased from baseline to year 2. In multiple regression analysis, first-year height velocity had a significant inverse relationship to JADAS-71 at year 1, age, mean glucocorticoid dosage during the year, and height SD score at baseline. CONCLUSION: Our findings indicate that during treatment with tocilizumab, patients with systemic JIA experience significant catch-up growth, normalization of IGF-1 levels, and bone balance improvement favoring bone formation.

Variability in delivery of care and echocardiogram surveillance of Kawasaki disease.

OBJECTIVE: The objective of this study is to characterize variability in the acute management of Kawasaki disease and compliance of echocardiogram surveillance with published American Heart Association recommendations. DESIGN: Retrospective review. SETTING: Tertiary care children's hospital. PATIENTS: All patients discharged from our institution with Kawasaki Disease between 1999 and 2007 were identified. Patients meeting any of the following were excluded: presence of a comorbidity that necessitated echocardiogram follow-up independent of Kawasaki disease diagnosis, previous history of Kawasaki disease, or magnetic resonance imaging of the coronary arteries performed in place of echocardiography. Preexisting or comorbid conditions resulting in study exclusion included structural heart disease, arrhythmia, and concomitant severe multiorgan disease at presentation (e.g., sepsis). OUTCOME MEASURES: The time course of echocardiogram surveillance among those with a normal echocardiogram at diagnosis was evaluated for compliance with published American Heart Association recommendations. Coronary artery involvement at presentation was characterized using standardized values. Additional characterization of national care practices for children with Kawasaki disease was obtained via distribution of an internet-based survey to pediatric hospitalists. RESULTS: Overall, only 11 (4%) of 302 patients with a normal study at diagnosis received a total of three studies at recommended intervals. Using standardized values for coronary artery dimensions in place of Japanese Ministry of Health aneurysm criteria, 59 (13%) of patients with Kawasaki disease experienced coronary artery involvement at diagnosis. The majority of the early coronary artery abnormalities detected in these patients using standardized definitions persisted on short-term follow-up. Pediatric hospitalist survey results revealed significant interinstitutional variability in the management of these patients. CONCLUSIONS: Lack of optimal surveillance after a diagnosis of Kawasaki disease may result in the underdiagnosis of coronary artery pathology or other complications. Considerable variability in surveillance and acute management exists, and additional research is needed to determine optimal screening and care delivery models for this population.

Lupus-associated causal mutation in neutrophil cytosolic factor 2 (NCF2) brings unique insights to the structure and function of NADPH oxidase.

Systemic lupus erythematosus (SLE), the prototypic systemic autoimmune disease, is a debilitating multisystem autoimmune disorder characterized by chronic inflammation and extensive immune dysregulation in multiple organ systems, resulting in significant morbidity and mortality. Here, we present a multidisciplinary approach resulting in the identification of neutrophil cytosolic factor 2 (NCF2) as an important risk factor for SLE and the detailed characterization of its causal variant. We show that NCF2 is strongly associated with increased SLE risk in two independent populations: childhood-onset SLE and adult-onset SLE. The association between NCF2 and SLE can be attributed to a single nonsynonymous coding mutation in exon 12, the effect of which is the substitution of histidine-389 with glutamine (H389Q) in the PB1 domain of the NCF2 protein, with glutamine being the risk allele. Computational modeling suggests that the NCF2 H389Q mutation reduces the binding efficiency of NCF2 with the guanine nucleotide exchange factor Vav1. The model predicts that NCF2/H389 residue interacts with Vav1 residues E509, N510, E556, and G559 in the ZF domain of Vav1. Furthermore, replacing H389 with Q results in 1.5 kcal/mol weaker binding. To examine the effect of the NCF2 H389Q mutation on NADPH oxidase function, site-specific mutations at the 389 position in NCF2 were tested. Results show that an H389Q mutation causes a twofold decrease in reactive oxygen species production induced by the activation of the Vav-dependent Fcγ receptor-elicited NADPH oxidase activity. Our study completes the chain of evidence from genetic association to specific molecular function.

Thrombotic microangiopathic hemolytic anemia with reduction of ADAMTS13 activity: initial manifestation of childhood-onset systemic lupus erythematosus.

Severe manifestations of systemic lupus erythematosus (SLE), antiphospholipid syndrome (APS), and thrombotic thrombocytopenic purpura (TTP) are characterized by multiorgan thrombotic microangiopathy. We describe reduction of ADAMTS13 activity and the development of systemic autoimmunity in all 8 children initially diagnosed with acquired noncongenital TTP during an 8.5-year period. Median age at diagnosis was 12.0 years (range, 2.6-17.3 years). ADAMTS13 activity was absent (<5%) in 6 patients; 3 patients had a detected inhibitor. SLE was diagnosed concurrently in 3 patients, and 4 patients were diagnosed within 5 years. Six of the children diagnosed with SLE had absent ADAMTS13 activity at diagnosis. In 6 patients with SLE, immune-mediated nephritis developed by 46 months. All surviving patients with SLE developed antiphospholipid antibodies, including some with a lupus anticoagulant. Patients with SLE did not have TTP recurrences once daily immunosuppressive regimens were started. An evaluation for SLE/APS is warranted in children and adolescents with reduced ADAMTS13 activity and thrombotic microangiopathy.

Update on antiphospholipid syndrome in children.

Thrombotic events that occur in children are relatively rare and are mostly associated with indwelling catheters, infectious processes, surgical procedures, or genetic defects or deficiencies. However, case reports, case series, and registries continue to report children who exhibit the clinical features often associated with the antiphospholipid syndrome. Many of these cases are well-documented and also meet the published research criteria for the antiphospholipid syndrome. Children with antiphospholipid antibodies generally do not experience a high rate of thrombotic events. This is in part related to developmental differences in levels of coagulation proteins and to the relative health of the vascular endothelium compared with that of adults. Therapeutic issues in children may be oriented more toward identifying risk factors and providing preventive health, as well as more short-term treatment of transient events.

Cerebral and cerebellar volume loss in children and adolescents with systemic lupus erythematosus: a review of clinically acquired brain magnetic resonance imaging.

OBJECTIVE: Cerebral atrophy is a prominent feature in adults with systemic lupus erythematosus (SLE). We assessed cerebral and cerebellar volume loss on clinically acquired brain magnetic resonance imaging (MRI) scans of children and adolescents with SLE. METHODS: We abstracted information on disease course for patients who underwent clinical brain MRI during the period 2002-2008. We completed qualitative assessments of volume loss and measured corpus callosum thickness and ventricular enlargement for patients with lupus and controls. RESULTS: Forty-nine children underwent brain MRI during the review period due to clinical indications. The lupus cohort was predominantly female and ethnically diverse. Mean age at imaging was 15.3 +/- 2.6 years and mean disease duration was 30.6 +/- 33.3 months. Findings suggestive of cerebral and cerebellar volume loss were seen respectively in 89.8% and 91.8% of lupus patients. Cerebral volume loss was moderate or severe in 26.5% of children. Cerebellar volume loss was moderate in 20.4% of these patients. Linear measurement means reflected corpus callosum thinning and ventricular enlargement in lupus patients. Volume loss was observed in newly diagnosed patients prior to corticosteroid use. Disease duration and corticosteroid use did not predict the severity of volume loss. There were statistically significant differences in linear imaging measurements comparing lupus patients to 14 similar-age controls. CONCLUSION: Regional volume loss was observed in most adolescents with lupus undergoing clinical brain MRI scans. As in other pediatric conditions with inflammatory or vascular etiologies, these findings may be reflecting disease-associated neuronal loss and not solely the effects of corticosteroid.

MR imaging findings suggestive of posterior reversible encephalopathy syndrome in adolescents with systemic lupus erythematosus.

BACKGROUND: Endothelial damage, hypertension and cytotoxic medications may serve as risk factors for the posterior reversible encephalopathy syndrome (PRES) in systemic lupus erythematosus. There have been few case reports of these findings in pediatric lupus patients. OBJECTIVE: We describe clinical and neuroimaging findings in children and adolescents with lupus and a PRES diagnosis. MATERIALS AND METHODS: We identified all clinically acquired brain MRIs of lupus patients at a tertiary care pediatric hospital (2002-2008). We reviewed clinical features, conventional MRI and diffusion-weighted imaging (DWI) findings of patients with gray- and white-matter changes suggestive of vasogenic edema and PRES. RESULTS: Six pediatric lupus patients presenting with seizures and altered mental status had MRI findings suggestive of PRES. In five children clinical and imaging changes were seen in conjunction with hypertension and active renal disease. MRI abnormalities were diffuse and involved frontal regions in five children. DWI changes reflected increased apparent diffusivity coefficient (unrestricted diffusion in all patients). Clinical and imaging changes significantly improved with antihypertensive and fluid management. CONCLUSION: MRI changes suggestive of vasogenic edema and PRES may be seen in children with active lupus and hypertension. The differential diagnosis of seizures and altered mental status should include PRES in children, as it does in adults.

Damage extent and predictors in adult and juvenile dermatomyositis and polymyositis as determined with the myositis damage index.

OBJECTIVE: We undertook this study to validate the Myositis Damage Index (MDI) in juvenile and adult myositis, to describe the degree and types of damage and to develop predictors of damage. METHODS: Retrospective MDI evaluations and prospective assessment of disease activity and illness features were conducted. Patients with juvenile-onset disease (n = 143) were evaluated a median of 18 months after diagnosis; 135 patients were assessed 7-9 months later, and 121 were last assessed a median of 82 months after diagnosis. Ninety-six patients with adult-onset dermatomyositis or polymyositis had a baseline assessment a median of 30 months after diagnosis; 77 patients had a 6-month followup evaluation, and 55 had a final assessment a median of 60 months after diagnosis. RESULTS: Damage was present in 79% of juvenile patients and in 97% of adult patients. In juveniles, scarring, contractures, persistent weakness, muscle dysfunction, and calcinosis were most frequent (23-30%) at the last evaluation. In adults, muscle atrophy, muscle dysfunction, and muscle weakness were most frequent (74-84%). MDI severity correlated with physician-assessed global damage, serum creatinine, and muscle atrophy on magnetic resonance imaging, and in juveniles also with functional disability and weakness. MDI damage scores and frequency were highest in patients with a chronic illness course and in adult patients who died. Predictors of damage included functional disability, duration of active disease, disease severity at diagnosis, physician-assessed global disease activity, and illness features, including ulcerations in children and pericarditis in adults. CONCLUSION: Damage is common in myositis after a median duration of 5 years in patients with adult-onset disease and 6.8 years in patients with juvenile-onset disease. The MDI has good content, construct, and predictive validity in juvenile and adult myositis.

High-density genotyping of STAT4 reveals multiple haplotypic associations with systemic lupus erythematosus in different racial groups.

OBJECTIVE: Systemic lupus erythematosus (SLE) is the prototypical systemic autoimmune disorder, with complex etiology and a strong genetic component. Recently, gene products involved in the interferon pathway have been under intense investigation in terms of the pathogenesis of SLE. STAT-1 and STAT-4 are transcription factors that play key roles in the interferon and Th1 signaling pathways, making them attractive candidates for involvement in SLE susceptibility. METHODS: Fifty-six single-nucleotide polymorphisms (SNPs) across STAT1 and STAT4 on chromosome 2 were genotyped using the Illumina platform, as part of an extensive association study in a large collection of 9,923 lupus patients and control subjects from different racial groups. DNA samples were obtained from the peripheral blood of patients with SLE and control subjects. Principal components analyses and population-based case-control association analyses were performed, and the P values, false discovery rate q values, and odds ratios with 95% confidence intervals were calculated. RESULTS: We observed strong genetic associations with SLE and multiple SNPs located within STAT4 in different ethnic groups (Fisher's combined P = 7.02 x 10(-25)). In addition to strongly confirming the previously reported association in the third intronic region of this gene, we identified additional haplotypic association across STAT4 and, in particular, a common risk haplotype that is found in multiple racial groups. In contrast, only a relatively weak suggestive association was observed with STAT1, probably due to its proximity to STAT4. CONCLUSION: Our findings indicate that STAT4 is likely to be a crucial component in SLE pathogenesis in multiple racial groups. Knowledge of the functional effects of this association, when they are revealed, might improve our understanding of the disease and provide new therapeutic targets.

Identification of IRAK1 as a risk gene with critical role in the pathogenesis of systemic lupus erythematosus.

A combined forward and reverse genetic approach was undertaken to test the candidacy of IRAK1 (interleukin-1 receptor associated kinase-1) as an X chromosome-encoded risk factor for systemic lupus erythematosus (SLE). In studying approximately 5,000 subjects and healthy controls, 5 SNPs spanning the IRAK1 gene showed disease association (P values reaching 10(-10), odds ratio >1.5) in both adult- and childhood-onset SLE, in 4 different ethnic groups, with a 4 SNP haplotype (GGGG) being strongly associated with the disease. The functional role of IRAK1 was next examined by using congenic mouse models bearing the disease loci: Sle1 or Sle3. IRAK1 deficiency abrogated all lupus-associated phenotypes, including IgM and IgG autoantibodies, lymphocytic activation, and renal disease in both models. In addition, the absence of IRAK1 reversed the dendritic cell "hyperactivity" associated with Sle3. Collectively, the forward genetic studies in human SLE and the mechanistic studies in mouse models establish IRAK1 as a disease gene in lupus, capable of modulating at least 2 key checkpoints in disease development. This demonstration of an X chromosome gene as a disease susceptibility factor in human SLE raises the possibility that the gender difference in SLE may in part be attributed to sex chromosome genes.

Identification of novel susceptibility genes in childhood-onset systemic lupus erythematosus using a uniquely designed candidate gene pathway platform.

OBJECTIVE: Childhood-onset systemic lupus erythematosus (SLE) presents a unique subgroup of patients for genetic study. The present study was undertaken to identify susceptibility genes contributing to SLE, using a novel candidate gene pathway microarray platform to investigate gene expression in patients with childhood-onset SLE and both of their parents. METHODS: Utilizing bioinformatic tools, a platform of 9,412 single-nucleotide polymorphisms (SNPs) from 1,204 genes was designed and validated. Molecular inversion probes and high-throughput SNP technologies were used for assay development. Seven hundred fifty three subjects, corresponding to 251 full trios of childhood-onset SLE families, were genotyped and analyzed using transmission disequilibrium testing (TDT) and multitest corrections. RESULTS: Family-based TDT showed a significant association of SLE with a N673S polymorphism in the P-selectin gene (SELP) (P = 5.74 x 10(-6)) and a C203S polymorphism in the interleukin-1 receptor-associated kinase 1 gene (IRAK1) (P = 9.58 x 10(-6)). These 2 SNPs had a false discovery rate for multitest correction of <0.05, and therefore a >95% probability of being considered as proven. Furthermore, 7 additional SNPs showed q values of <0.5, suggesting association with SLE and providing a direction for followup studies. These additional genes notably included TNFRSF6 (Fas) and IRF5, supporting previous findings of their association with SLE pathogenesis. CONCLUSION: SELP and IRAK1 were identified as novel SLE-associated genes with a high degree of significance, suggesting new directions in understanding the pathogenesis of SLE. The overall design and results of this study demonstrate that the candidate gene pathway microarray platform used provides a novel and powerful approach that is generally applicable in identifying genetic foundations of complex diseases.

A randomized, placebo-controlled trial of infliximab plus methotrexate for the treatment of polyarticular-course juvenile rheumatoid arthritis.

OBJECTIVE: To evaluate the safety and efficacy of infliximab in the treatment of juvenile rheumatoid arthritis (JRA). METHODS: This was an international, multicenter, randomized, placebo-controlled, double-blind study. One hundred twenty-two children with persistent polyarticular JRA despite prior methotrexate (MTX) therapy were randomized to receive infliximab or placebo for 14 weeks, after which all children received infliximab through week 44. Patients received MTX plus infliximab 3 mg/kg through week 44, or MTX plus placebo for 14 weeks followed by MTX plus infliximab 6 mg/kg through week 44. RESULTS: Although a higher proportion of patients in the 3 mg/kg infliximab group than in the placebo group had achieved responses according to the American College of Rheumatology (ACR) Pediatric 30 (Pedi 30) criteria for improvement at week 14 (63.8% and 49.2%, respectively), the between-group difference in this primary efficacy end point was not statistically significant (P = 0.12). By week 16, after the crossover from placebo to infliximab 6 mg/kg when all patients were receiving infliximab, an ACR Pedi 30 response was achieved in 73.2% of all patients. By week 52, ACR Pedi 50 and ACR Pedi 70 responses had been reached in 69.6% and 51.8%, respectively, of patients. Infliximab was generally well tolerated, but the safety profile of infliximab 3 mg/kg appeared less favorable than that of infliximab 6 mg/kg, with more frequent occurrences of serious adverse events, infusion reactions, antibodies to infliximab, and newly induced antinuclear antibodies and antibodies to double-stranded DNA observed with the 3 mg/kg dose. CONCLUSION: While infliximab at 3 mg/kg and 6 mg/kg showed durable efficacy at 1 year, achievement of the primary efficacy end point at 3 months did not differ significantly between infliximab-treated and placebo-treated patients. Safety data indicated that the 6-mg/kg dose may provide a more favorable risk/benefit profile. These results warrant further investigation in children with JRA.

The role of autoantibodies in pediatric neuropsychiatric systemic lupus erythematosus.

Neuropsychiatric syndromes are prevalent in pediatric patients with systemic lupus erythematosus (SLE) and often manifest early in disease course and with significant associated morbidity. Postulated pathogenic mechanisms of peripheral and central nervous system events include vasculopathy, autoantibody effects and systemic inflammation. The pathogenic roles of anti-phospholipid, anti-ribosomal-P and anti-neuronal autoantibodies have been examined in both focal and diffuse adult neuropsychiatric syndromes. Few studies have probed associations between these autoantibodies and pediatric neuropsychiatric SLE (NP-SLE). Retrospective review of a large ethnically diverse pediatric SLE cohort revealed anti-phospholipid, anti-ribosomal P, and anti-neuronal antibodies to be more prevalent than in many adult studies. Rates of anti-phospholipid and anti-ribosomal P antibody positivity were similar to those of other pediatric reports. Association between anti-neuronal antibodies and NP-SLE events appeared statistically significant in this cohort. Prospective inception cohort studies will need to be undertaken to investigate the significance and utility of autoantibody testing in pediatric NP-SLE.

The molecular basis of complete complement C4A and C4B deficiencies in a systemic lupus erythematosus patient with homozygous C4A and C4B mutant genes.

The disease course of a complete C4-deficient patient in the U.S. was followed for 18 years. The patient experienced multiple episodes of infection, and he was diagnosed with systemic lupus erythematosus at age 9 years. The disease progressed to WHO class III mild lupus nephritis and to fatal CNS vasculitis at age 23 years. Immunochemical experiments showed that the patient and his sibling had complete absence of C4A and C4B proteins and were negative for the Rodgers and Chido blood group Ags. Segregation and definitive RFLP analyses demonstrated that the patient and his sibling inherited two identical haplotypes, HLA A2 B12 DR6, each of which carries a defective long C4A gene and a defective short C4B gene. PCR and DNA sequencing revealed that the mutant C4A contained a 2-bp insertion in exon 29 at the sequence for codon 1213. The identical mutation was absent in the mutant C4B. The C4B mutant gene was selectively amplified by long range PCR, and its 41 exons were completely sequenced. The C4B mutant had a novel single C nucleotide deletion at the sequence for codon 522 in exon 13, leading to frame-shift mutation and premature termination. Thus, a multiplex PCR is designed by which known mutations in C4A and C4B can be elucidated conveniently. Among the 28 individuals reported with complete C4 deficiency, 75-96% of the subjects (dependent on the inclusion criteria) were afflicted with autoimmune or immune complex disorders. Hence, complete C4 deficiency is one of the most penetrant genetic risk factors for human systemic lupus erythematosus.

Prevalence of superantigen-secreting bacteria in patients with Kawasaki disease.

OBJECTIVES: To assess the prevalence of superantigen secreting bacteria in children with acute Kawasaki disease (KD) relative to control patients. STUDY DESIGN: Bacterial cultures were obtained in a blinded fashion from the throat, rectum, and groin of 45 patients with untreated acute KD and 37 febrile control patients from 6 centers in the United States. Cultures were processed for the presence of superantigen-producing bacteria at a central laboratory. RESULTS: Staphylococci or streptococci that produced superantigens (TSST-1, SEB, SEC, SPEB, SPEC) were isolated from 25 of 45 patients with KD (56%) as compared with 13 of 37 (35%) control patients (P =.078). Because SEB- and SEC-producing Staphylococcus aureus have not been associated with KD and because they do not induce a Vbeta2+ T-lymphocyte response, we analyzed the difference between groups relative to superantigens TSST-1 or SPEB/SPEC production. TSST-1 secreting S aureus or SPEB/SPEC producing group A streptococci were isolated from 20 of 45 (44%) patients with KD compared with 7 of 37 (19%) control patients (P =.019). CONCLUSIONS: The overall isolation rates of superantigen (TSST-1, SPEB, SPEC, SEB, SEC) producing bacteria between patients with KD and febrile control patients were not statistically significant. However, future studies should further examine the potential role of Vbeta2-stimulatory superantigens (TSST-1 and SPEB/SPEC) in KD.