Type I interferon pathway in pediatric systemic lupus erythematosus.

BACKGROUND: The role of type I interferon (IFN-I) signaling in systemic lupus erythematosus (SLE) has been well established. However, unanswered questions remain regarding the applicability of these findings to pediatric-onset SLE. The aim of this review is to provide an overview of the novel discoveries on IFN-I signaling in pediatric-onset SLE. DATA SOURCES: A literature search was conducted in the PubMed database using the following keywords: "pediatric systemic lupus erythematosus" and "type I interferon". RESULTS: IFN-I signaling is increased in pediatric SLE, largely due to the presence of plasmacytoid dendritic cells and pathways such as cyclic GMP-AMP synthase-stimulator of interferon genes-TANK-binding kinase 1 and Toll-like receptor (TLR)4/TLR9. Neutrophil extracellular traps and oxidative DNA damage further stimulate IFN-I production. Genetic variants in IFN-I-related genes, such as IFN-regulatory factor 5 and tyrosine kinase 2, are linked to SLE susceptibility in pediatric patients. In addition, type I interferonopathies, characterized by sustained IFN-I activation, can mimic SLE symptoms and are thus important to distinguish. Studies on interferonopathies also contribute to exploring the pathogenesis of SLE. Measuring IFN-I activation is crucial for SLE diagnosis and stratification. Both IFN-stimulated gene expression and serum IFN-α2 levels are common indicators. Flow cytometry markers such as CD169 and galectin-9 are promising alternatives. Anti-IFN therapies, such as sifalimumab and anifrolumab, show promise in adult patients with SLE, but their efficacy in pediatric patients requires further investigation. Janus kinase inhibitors are another treatment option for severe pediatric SLE patients. CONCLUSIONS: This review presents an overview of the IFN-I pathway in pediatric SLE. Understanding the intricate relationship between IFN-I and pediatric SLE may help to identify potential diagnostic markers and targeted therapies, paving the way for improved patient care and outcomes.

The role of vitamin D in pediatric systemic lupus erythematosus - a double pawn in the immune and microbial balance.

Having increased popularity during the Covid-19 pandemic, vitamin D3 is currently impressing thanks to the numerous researches aimed at its interactions with the body's homeostasis. At the same time, there is a peak in terms of recommendations for supplementation with it. Some of the studies focus on the link between autoimmune diseases and nutritional deficiencies, especially vitamin D3. Since the specialized literature aimed at children (patients between 0-18 years old) is far from equal to the informational diversity of the adult-centered branch, this review aims to bring up to date the relationship between the microbial and nutritional balance and the activity of pediatric systemic lupus erythematosus (pSLE). The desired practical purpose resides in a better understanding and an adequate, individualized management of the affected persons to reduce morbidity. The center of the summary is to establish the impact of hypovitaminosis D in the development and evolution of pediatric lupus erythematosus. We will address aspects related to the two entities of the impact played by vitamin D3 in the pathophysiological cascade of lupus, but also the risk of toxicity and its effects when the deficiency is over supplemented (hypervitaminosis D). We will debate the relationship of hypovitaminosis D with the modulation of immune function, the potentiation of inflammatory processes, the increase of oxidative stress, the perfusion of cognitive brain areas, the seasonal incidence of SLE and its severity. Finally, we review current knowledge, post-pandemic, regarding the hypovitaminosis D - pSLE relationship.

Glucocorticoid reduction induced chorea in pediatric-onset systemic lupus erythematosus: A case report.

BACKGROUND: Pediatric-onset systemic lupus erythematosus (SLE) is typically more severe than adult-onset SLE, with a higher incidence of nervous system involvement. Chorea is a relatively rare neurological complication reported in 2.4%-7% of SLE patients. In particular, chorea induced by glucocorticoid dose reduction is even rarer. Herein, we report the case of a girl with SLE, who developed chorea during the process of glucocorticoid therapy reduction. CASE SUMMARY: We describe a 14-year-old girl who was diagnosed with SLE. She was treated with methylprednisolone and rituximab, and her symptoms improved. On the second day after the methylprednisolone dose was reduced according to the treatment guidelines, the patient developed chorea. Her condition improved after adjusting her glucocorticoid regimen. CONCLUSION: This case is a reminder that extra attention to chorea is required in SLE patients during glucocorticoid dose reduction.

IL-10 and IFN-γ as markers for early recognition of pediatric systemic lupus erythematosus complicated with macrophage activation syndrome.

OBJECTIVES: To compare the clinical and laboratory characteristics of pediatric-onset systemic lupus erythematosus (pSLE), pSLE with macrophage activation syndrome (MAS), and pSLE with recurrent MAS, and to find biomarkers for the differential diagnosis of these diseases. METHODS: Demographic, clinical, laboratory and radiological data were analyzed for three groups of patients: 18 cases of pSLE with MAS, 48 age- and sex-matched cases of active pSLE without MAS and 40 age- and sex-matched cases of pSLE with inactive disease. One case of a 9-year-old girl with recurrent MAS as the primary manifestation of SLE also was recorded. RESULTS: IL-10 and IFN-γ levels were significantly higher in pSLE patients with MAS than in pSLE patients without MAS, and were significantly correlated with SLE and MAS laboratory features. Levels of IL-10 > 7.25 pg/ml had a high sensitivity and levels of IFN-γ > 6.7 pg/ml had a high specificity for predicting MAS in pSLE. Constitutional symptoms were evident in the case of recurrent MAS in pSLE, and traditional immunosuppressive therapies were unable to prevent the next MAS episode. CONCLUSION: Compared with pSLE and pSLE-MAS with a single episode, pSLE with recurrent MAS has different clinical manifestations and responses to treatment, requiring intensive studies to elucidate the underlying pathogenic mechanisms. Elevated serum levels of IL-10 and IFN-γ may be correlated with pSLE with MAS, and can serve as serum biomarkers for pSLE with MAS.

Pediatric Lupus Retinopathy: A Rare Manifestation of a Grave Systemic Disorder.

We describe a rare case of pediatric systemic lupus erythematosus (pSLE) and its successful management. A nine-year-old female presented with bilateral diminution of vision, fever, and rash in the malar region, chest, abdomen, back, and arms for three months. Clinical examination and multimodal imaging revealed bilateral extensive retinal vasculitis with macular edema. Laboratory investigations revealed anemia, leucopenia, positive serum antinuclear antibody (ANA), and anti-extractable nuclear antigen (ENA) antibodies. A diagnosis of pediatric lupus retinopathy was made. Ocular and systemic manifestations responded well to intense systemic immunosuppression (pulse intravenous {IV} methylprednisolone, oral prednisolone and hydroxychloroquine {HCQ}, six cycles of IV cyclophosphamide, and oral azathioprine) along with topical steroids and laser photocoagulation, over the next 10 months. Though ocular manifestations are not a part of the diagnostic criteria for SLE, they may be markers of active systemic disease. Ophthalmologists and rheumatologists must treat this complex disease in tandem in order to provide optimum patient care.

Cognitive dysfunction in pediatric systemic lupus erythematosus: current knowledge and future directions.

Cognitive dysfunction (CD) is a neurologic complication of pediatric systemic lupus erythematosus (SLE) that remains poorly understood and understudied, despite the potential negative effects of CD on long-term socioeconomic status and quality of life. Data regarding the prevalence and risk factors for CD in pediatric SLE as well as the optimal screening, treatment, and long-term outcomes for CD are lacking. In this review, we present current knowledge on CD in pediatric SLE with a focus on the application to clinical practice. We discuss the challenges in diagnosis, clinical screening methods, potential impacts, and interventions for this complication. Finally, we discuss the remaining gaps in our knowledge of CD in pediatric SLE, and avenues for future research efforts.

The correlation between trajectories of serum C3 variability and clinical course in Pediatric-onset systemic lupus erythematosus.

OBJECTIVE: The aim of this study is to investigate the usefulness which 2-year trajectories of C3 variability have in predicting clinical remission and systemic corticosteroids (SCS) use in pediatric patients with systemic lupus erythematosus (pSLE). METHODS: We recruited 189 confirmed pSLE patients from the electronic database of our hospital, all had undergone SCS treatment. The follow up period was 4.17-14.83 years. We used Group-Based Trajectory modeling to divide the patients into four different trajectory groups by their initial 2-year C3 variability. We divided the patients into groups A, B or C by their clinical course and SCS use. Statistical methods included Kruskal-Wallis and Chi-square tests and logic regression test. RESULTS: There were 4 separate trajectories. The distribution of groups A, B and C in these 4 trajectories showed a significant difference (p = 0.005). Initial C3 and C4 levels in these 4 revealed significant differences (p â‰¦ 0.001, p â‰¦ 0.016). When compared to other trajectories, trajectory1 showed a higher risk for persistent SCS use (p < 0.05). The distributions of severe clinical manifestations, including proteinuria, hematuria, CNS involvement and thrombocytopenia were different in these 4 trajectories (p = 0.003). Nevertheless, none of the above manifestations contributed to the risk of persistent SCS use. CONCLUSIONS: We have found 4 distinct C3 trajectories in pSLE patients. Distributions of clinical outcome groups were different in these 4 trajectories. Patients with trajectory1 displayed a higher risk for persistent SCS use, thus an earlier institution of immunosuppressant(s) and biological agents can be considered for these children.

Does kidney biopsy in pediatric lupus patients "complement" the management and outcomes of silent lupus nephritis? Lessons learned from a pediatric cohort.

BACKGROUND: Silent lupus nephritis (SLN) is systemic lupus erythematosus (SLE) without clinical and laboratory features of kidney involvement but with biopsy-proven nephritis. This study aims to describe and compare the baseline characteristics and outcomes of pediatric SLN with overt LN (OLN) and to identify associated risk factors and biochemical markers. METHODS: In this retrospective, observational study, multivariate logistic regression and receiver operating characteristic (ROC) analyses studied age, sex, race, serum complements, anti-double-stranded-DNA antibody, anti-Smith antibody, eGFR, and proliferative nephritis. RESULTS: In our cohort of 69 patients, 47 were OLN, and 22 were SLN. OLN (OR = 4.9, p = 0.03) and non-African Americans (AA) (OR = 13.0, p < 0.01) had higher odds, and increasing C3 and C4 were associated with lower odds of proliferative nephritis (OR 0.95 and 0.65 per one unit increase in C3 and C4, respectively, p < 0.01). They demonstrated a good discriminative ability to detect proliferative nephritis as assessed by the area under the ROC curve (C3 = 0.78, C4 = 0.78). C3 and C4 in proliferative SLN and OLN were comparable and significantly lower than their non-proliferative counterparts. No association was observed between age, sex, anti-double-stranded-DNA antibody, anti-Smith antibody, eGFR, and proliferative nephritis. Proliferative SLN and OLN patients received similar treatments. Adverse events were identified in the proliferative OLN only. CONCLUSIONS: Lower complement levels are associated with proliferative lesions in pediatric LN-both SLN and OLN. The non-AA population had higher odds of having proliferative nephritis than the AA. Prospective, randomized, long-term follow-up of proliferative SLN patients is needed to ascertain the beneficial effect of early diagnosis and treatment. A higher resolution version of the Graphical abstract is available as Supplementary information.

Periorbital Edema as the Initial Manifestation of Pediatric Systemic Lupus Erythematosus.

Periorbital edema as a sole initial manifestation, without any evidence of other significant cutaneous or systemic involvement, is rare in systemic lupus erythematosus (SLE). We report a 16 year-old female who presented with bilateral periorbital edema as the sole initial manifestation of SLE. As the disease progressed, a kidney biopsy was performed demonstrating lupus nephritis stage II. This report emphasizes the importance of the index of suspicion of SLE as one of the differential diagnosis of patients with periorbital edema in the relevant clinical context.

Simultaneous Onset of Pediatric Systemic Lupus Erythematosus in Twin Brothers: Case Report.

There are hundreds of twin adult patients with systemic lupus erythematosus (SLE), but male children with SLE are rarely affected. Two monozygotic twin brothers developed SLE at the age of 11 years during 1 month. The index brother manifested with Henoch-Shonlein purpura, accompanied by ANA positivity, and later developed critical left femoral arterial stenosis with high levels of anti-dsDNA, antiphospholipid antibodies, hypocomplementemia, and Coombs-positive hemolytic anemia. At that time his twin brother had only identical autoimmune findings and developed clinical manifestation (myositis and fasciitis) a month later. Both twins had increased IFN-score and shared a heterozygous variant in the RNASEL gene. Index patients developed scalp rash and nephritis 6 months after their parents refused the treatment which has been lasted for 1 year after disease diagnostics. Conclusion: The simultaneous onset of the pediatric SLE in the male twin is a very rare situation suspected monogenic origin of the disease. Further functional studies are required to confirm the causative role of the mutation.

Bone remodeling serum markers in children with systemic lupus erythematosus.

INDRODUCTION: SLE is an autoimmune multisystem disease. Glucocorticoid is an irreplaceable medication for SLE. Glucocorticoid and inflammatory mediators impact bone remodeling by OPG/RANKL/RANK signal system, which could lead to osteoporosis. Our aim is to detect the expression of RANKL/OPG in children with SLE, and to preliminarily explore the changes of bone remodeling serum markers in children with SLE. METHODS: Serum RANKL and OPG of 40 children with SLE and healthy children were detected by ELISA, while 25(OH)VitD3 was detected routinely. Clinical data of children with SLE were recorded, including gender, age, height, weight, BMI, SLEDAI, duration of the disease, cumulative dose of glucocorticoid, and correlation analysis was conducted with RANKL, OPG and 25(OH)VitD3. RESULTS: Serum RANKL concentrations in SLE group were significantly higher than health group (9.82 ± 7.20 vs. 6.80 ± 4.35 pg/ml and 0.081 ± 0.072 vs. 0.042 ± 0.034, P < 0.05) respectively, and the concentrations of OPG and 25(OH)VitD3 in serum were significantly lower than health group (156.34 ± 57.33 vs. 189.16 ± 68.70 pg/ml and 43.66 ± 31.27 vs. 59.04 ± 21.56 mmol/L, P < 0.05). Serum RANKL in children with SLE was positively correlated with the duration of SLE, cumulative dose of GC(r = 0.593, 0.727, P < 0.05). And it was negatively correlated with serum OPG and 25(OH)VitD3 (r = -0.601, -0.469, P < 0.05). In addition, serum OPG and 25(OH)VitD3 concentrations were inversely correlated with cumulative dose of GC (r = -0.66, -0.508, P < 0.05). CONCLUSION: Low levels of vitamin D3 and bone metabolic abnormalities still persist in children with SLE even if the disease is in remission, while serum RANKL level was elevated, OPG expression was reduced. In the case of disease remission, GC is involved in the occurrence and development of abnormal bone remodeling through RANKL/OPG.

Hemophagocytic Lymphohistiocytosis Gene Variants in Childhood-Onset Systemic Lupus Erythematosus With Macrophage Activation Syndrome.

OBJECTIVE: Macrophage activation syndrome (MAS), a life-threatening complication of systemic lupus erythematosus (SLE), resembles familial hemophagocytic lymphohistiocytosis (HLH), an inherited disorder of hyperinflammation. We compared the proportion of patients with childhood-onset SLE (cSLE) with and without MAS who carried low-frequency HLH nonsynonymous variants. METHODS: We enrolled patients from the Lupus Clinic at SickKids, Toronto. Demographic and clinical features were extracted from the SLE database and ancestry was genetically inferred using multiethnic genotyping array data. Patients with MAS (based on expert diagnosis) underwent either paired-end whole-exome sequencing (WES; read depth: 70-118X) or whole-genome sequencing (WGS). Patients without MAS had WGS (read depth: 37-40X). In 16 HLH genes, we prioritized low-frequency (minor allele frequency [MAF] < 0.05) exonic nonsynonymous variants. We compared the proportion of patients with and without MAS carrying HLH variants (Fisher exact test, P < 0.05). MAFs were compared to an ancestrally matched general population (Trans-Omics for Precision Medicine [TOPMed] and Genome Aggregation Database [gnomAD]). RESULTS: The study included 81 patients with cSLE, 19 of whom had MAS. We identified 47 unique low-frequency nonsynonymous HLH variants. There was no difference in the proportion of patients with and without MAS carrying ≥ 1 HLH variants (37% vs 47%, P = 0.44). The MAS cohort did not carry more HLH variants when compared to an ancestrally matched general population. CONCLUSION: In a single-center multiethnic cSLE cohort, we found no difference in the proportion of patients with MAS carrying nonsynonymous HLH genetic variants compared to patients without MAS. To our knowledge, this is the first study to examine the frequency of HLH genetic variants in relation to MAS among patients with cSLE. Future studies are required to validate our findings.

Celiac Disease in Juvenile Idiopathic Arthritis and Other Pediatric Rheumatic Disorders.

Celiac Disease (CD) is an immune-mediated and gluten-related disorder whose prevalence is higher in children affected with other autoimmune disorders, including diabetes mellitus type 1, autoimmune thyroiditis, and others. As regards Juvenile Idiopathic Arthritis (JIA) and other pediatric rheumatic disorders, there is no clear recommendation for CD serological screening. In this review, we analyze all the available clinical studies investigating CD among children with JIA (and other rheumatic diseases), in order to provide objective data to better understand the necessity of CD serological screening during the follow-up. Based on the present literature review and analysis, >2.5% patients with JIA were diagnosed with CD; however, the CD prevalence in JIA patients may be even higher (>3-3.5%) due to several study limitations that could have underestimated CD diagnosis to a variable extent. Therefore, serological screening for CD in children affected with JIA could be recommended due to the increased CD prevalence in these patients (compared to the general pediatric population), and because these JIA patients diagnosed with CD were mostly asymptomatic. However, further research is needed to establish a cost-effective approach in terms of CD screening frequency and modalities during the follow-up for JIA patients. Conversely, at the moment, there is no evidence supporting a periodical CD screening in children affected with other rheumatic diseases (including pediatric systemic lupus erythematosus, juvenile dermatomyositis, and systemic sclerosis).

Reliability and reproducibility of antinuclear antibody testing in pediatric rheumatology practice.

Antinuclear antibody (ANA) testing is common practice among health care practitioners when evaluating children and adolescents with non-specific symptoms including fatigue and aches and pains. When positive, ANA results often lead to referrals to pediatric rheumatologists as these antibodies may be key indicators for specific pediatric rheumatologic diagnoses. The reliability and reproducibility of ANA tests varies with assay techniques and validation and interpretation of results. In the following article, review of ANA testing in pediatrics is provided along with case examples that demonstrate the reliability and reproducibility of these results in specific scenarios common in the practice of pediatric rheumatology. Guidelines for more accurate utilization of ANA testing are presented with the aim to improve testing and interpretation by ordering clinicians.

Macrophage Activation Syndrome in Pediatric Systemic Lupus Erythematosus: A Systematic Review of the Diagnostic Aspects.

Macrophage Activation Syndrome (MAS) is a very severe complication of different rheumatic diseases, including pediatric Systemic Lupus Erythematosus (pSLE). MAS is not considered as a frequent complication of pSLE; however, its occurrence could be under-estimated and the diagnosis can be challenging. In order to address this issue, we performed a systematic review of the available medical literature, aiming to retrieve all those papers providing diagnostic (clinical/laboratory) data on patients with pSLE-related MAS, in individual or aggregated form. The selected case reports and series provided a pool of 46 patients, accounting for 48 episodes of MAS in total. We re-analyzed these patients in light of the diagnostic criteria for MAS validated in systemic Juvenile Idiopathic Arthritis (sJIA) patients and the preliminary diagnostic criteria for MAS in pSLE, respectively. Five clinical studies were also selected and used to support this analysis. This systematic review confirms that MAS diagnosis in pSLE patients is characterized by several diagnostic challenges, which could lead to delayed diagnosis and/or under-estimation of this complication. Specific criteria should be considered to diagnose MAS in different rheumatic diseases; as regards pSLE, the aforementioned preliminary criteria for MAS in pSLE seem to perform better than the sJIA-related MAS criteria, because of a lower ferritin cut-off.

Patient experiences and strategies for coping with SLE: A qualitative study.

OBJECTIVE: This study explored challenges that patients with systemic lupus erythematosus (SLE) and childhood-onset SLE (cSLE) face to identify modifiable influences and coping strategies in patient experiences. METHODS: Participants were recruited from two academic medical centers through a Lupus Registry of individuals ≥18 years old and ≥4 1997 ACR classification criteria for SLE and a centralized data repository of cSLE patients, and participated in three focus groups. Transcripts were coded thematically and adjudicated by two independent reviewers. RESULTS: Thirteen adults, 7 (54%) with cSLE, participated in focus groups. Themes were categorized into two domains: (1) challenges with SLE diagnosis and management; and (2) patient coping strategies and modifiable factors of the SLE experience. Participants identified five primary challenges: diagnostic odyssey, public versus private face of SLE, SLE-related stresses, medication adherence, and transitioning from pediatric to adult care. Coping strategies and modifiable factors included social support, open communication about SLE, and strong patient-provider relationships. Several participants highlighted positive lessons learned through their experiences with SLE, including empathy, resilience, and self-care skills. CONCLUSIONS: Patients with cSLE and SLE identified common challenges, modifying influences and coping strategies based on personal experiences. A strong patient-provider relationship and trust in the medical team emerged as key modifiable factors. Deriving optimism from experiences with SLE was unique to several patients diagnosed as children or young adults. Leveraging factors that improved the participants' experiences living with SLE may be used in future studies to address vulnerabilities in care.

Is podocytopathy another image of renal affection in p-SLE?

BACKGROUND: Lupus podocytopathy (LP) is a renal affection described in systemic lupus erythematosus (SLE) patients with nephrotic range proteinuria, characterized by diffuse foot process effacement without immune deposits and glomerular proliferation. This study describes LP, its pathological features and outcomes of pediatric (p-SLE) patients in comparison to the usual lupus nephritis (LN) cases. METHODOLOGY: A retrospective cohort study conducted on a 10-year registration (2010-2019) of 140 p-SLE patients at the Pediatric Department, Tanta University. Histopathological analysis with light microscopy (LM) and immunofluorescence (IF) of all renal biopsies were evaluated according to the International Society of Nephrology Renal Pathology Society (ISN/RPS) grading system. In addition, some biopsies were examined with electron microscopy (EM). RESULTS: Eighty-six p-SLE cases (61.4%) had renal involvement; seventy-nine biopsies (91.86%) of them met the classification criteria of LN as defined by ISN/RPS system. Five biopsies were normal (MCD) and two showed focal segmental sclerosis (FSGN) that did not meet any known classification of LN. Hence, they were reevaluated using EM that revealed diffuse effaced podocytes without glomerular sub-epithelial, endocapillary or basement membrane immune deposits, and were classified as having lupus podocytopathy, representing (8.14%) of all LN biopsies. Those seven cases showed good response to steroids with a complete remission duration of 3.40 ± 1.95 weeks. However, some case had 1-3 relapses during the duration of follow up. CONCLUSIONS: LP is a spectrum of p-SLE, not an association as it is related to disease activity and its initial presentation.

Patterns of Healthcare Use and Medication Adherence among Youth with Systemic Lupus Erythematosus during Transfer from Pediatric to Adult Care.

OBJECTIVE: Youth with systemic lupus erythematosus (SLE) transferring from pediatric to adult care are at risk for poor outcomes. We describe patterns of rheumatology/nephrology care and changes in healthcare use and medication adherence during transfer. METHODS: We identified youth ages 15-25 with SLE using US private insurance claims from Optum's deidentified Clinformatics Data Mart. Rheumatology/nephrology visit patterns were categorized as (1) unilateral transfers to adult care within 12 months, (2) overlapping pediatric and adult visits, (3) lost to followup, or (4) continuing pediatric care. We used negative binomial regression and paired t tests to estimate changes in healthcare use and medication possession ratios (MPR) after the last pediatric (index) visit. We compared MPR between youth who transferred and age-matched peers continuing pediatric care. RESULTS: Of the 184 youth transferred out of pediatric care, 41.8% transferred unilaterally, 31.5% had overlapping visits over a median of 12 months before final transfer, and 26.6% were lost to followup. We matched 107 youth continuing pediatric care. Overall, ambulatory care use decreased among those lost to followup. Acute care use decreased across all groups. MPR after the index date were lower in youth lost to followup (mean 0.24) compared to peers in pediatric care (mean 0.57, p < 0.001). CONCLUSION: Youth with SLE with continuous private insurance coverage do not use more acute care after transfer to adult care. However, a substantial proportion fail to see adult subspecialists within 12 months and have worse medication adherence, placing them at higher risk for adverse outcomes.

Predicting Macrophage Activation Syndrome in Childhood-onset Systemic Lupus Erythematosus Patients at Diagnosis.

OBJECTIVE: Macrophage activation syndrome (MAS), a life-threatening inflammatory complication, is increasingly recognized in childhood-onset systemic lupus erythematosus (cSLE). It can be a challenge to differentiate active cSLE from MAS. We generated decision rules for discriminating MAS from active cSLE in newly diagnosed patients. METHODS: We conducted a retrospective cohort study of consecutive, newly diagnosed, active cSLE patients with fever, requiring hospital admission to The Hospital for Sick Children from January 2003 to December 2007 (cohort 1) and January 2008 to December 2013 (cohort 2). All patients met ≥ 4 American College of Rheumatology or Systemic Lupus International Collaborating Clinics criteria, and were steroid-naïve and infection-free. MAS was diagnosed based on expert opinion. Recursive partitioning was applied to each cohort to derive a decision rule based on clinical and laboratory features, distinguishing MAS from non-MAS cSLE. Each decision rule was applied to the alternate, independent cohort. Sensitivity and specificity of these decision rules were compared to existing criteria. RESULTS: Cohort 1 (n = 34) and cohort 2 (n = 41) each had 10 patients with MAS. Recursive partitioning in cohort 1 identified ferritin ≥ 699 µg/L as the sole best discriminator between MAS and non-MAS patients (R2 = 0.48), and in cohort 2, ferritin ≥ 1107 µg/L was the best discriminator for MAS, followed by lymphocytes < 0.72 × 103/mm3 (R2 = 0.52). Cross-validation of our decision rules maintained 90-100% sensitivity and 65-85% specificity. CONCLUSION: Our decision rule demonstrated improved performance compared to preliminary guidelines for MAS in cSLE from the Lupus Working Group of the Paediatric Rheumatology European Society and familial hemophagocytic lymphohistiocytosis diagnostic criteria. Validation in independent cohorts is required.

Utilidad de la Determinación de CD25 Soluble en Pacientes con sospecha de Síndrome de Activación Macrofágica / Usefulness of the determination of soluble CD25 in patients with suspected macrophage activation syndrome

El síndrome de activación macrofágica (SAM) presenta criterios clínicos y de laboratorio establecidos. Presentamos el caso de un adolescente varón con debut de Lupus eritematoso generalizado pediátrico grave, donde su manifestación principal fue un SAM y el receptor de interleucina 2 soluble en suero (IL-2rs) o CD25 soluble (CD25s) aumentado resultó clave en la confirmación diagnóstica, en el tratamiento y pronóstico de su enfermedad. Sin embargo, este receptor de citocinas no se mide habitualmente en la práctica clínica.

Macrophage activation syndrome (MAS) presents established clinical and laboratory criteria. We present the case of a male adolescent with the onset of severe pediatric systemic Lupus erythematosus, manifested mainly by MAS and how a laboratory marker, serum soluble interleukin-2 receptor (IL-2rs) or altered soluble CD25(CD25s), played a key role in treatment and prognosis of the disease. However, this cytokine receptor is rarely measured in clinical practice.