The myeloid-related proteins 8 and 14 complex, a novel ligand of toll-like receptor 4, and interleukin-1beta form a positive feedback mechanism in systemic-onset juvenile idiopathic arthritis

Systemic juvenile idiopathic arthritis and adult-onset Still's disease are the same disease: evidence from systematic reviews and meta-analyses informing the 2023 EULAR/PReS recommendations for the diagnosis and management of Still's disease

OBJECTIVES

To analyse the similarity in clinical manifestations and laboratory findings between systemic juvenile idiopathic arthritis (sJIA) and adult-onset Still's disease (AOSD).

METHODS

Three systematic reviews (SR) were performed. One included cohort studies comparing sJIA versus AOSD that described clinical and biological manifestations with at least 20 patients in each group (SR1). The second identified studies of biomarkers in both diseases and their diagnostic performance (SR2). The last focused on diagnostic biomarkers for macrophage activation syndrome (MAS, SR3). Medline (PubMed), Embase and Cochrane Library were systematically searched. The risk of bias was assessed with an adapted form of the Hoy scale for prevalence studies in SR1 and the Quality Assessment of Diagnostic Accuracy Studies-2 in SR2 and SR3. We performed meta-analyses of proportions for the qualitative descriptors.

RESULTS

Eight studies were included in SR1 (n=1010 participants), 33 in SR2 and 10 in SR3. The pooled prevalence of clinical manifestations did not differ between sJIA and AOSD, except for myalgia, sore throat and weight loss, which were more frequent in AOSD than sJIA because they are likely ascertained incompletely in sJIA, especially in young children. Except for AA amyloidosis, more frequent in sJIA than AOSD, the prevalence of complications did not differ, nor did the prevalence of biological findings. Ferritin, S100 proteins and interleukin-18 (IL-18) were the most frequently used diagnostic biomarkers, with similar diagnostic performance. For MAS diagnosis, novel biomarkers such as IL-18, C-X-C motif ligand 9, adenosine deaminase 2 activity and activated T cells seemed promising.

CONCLUSION

Our results argue for a continuum between sJIA and AOSD.

PROSPERO REGISTRATION NUMBER

CRD42022374240 and CRD42024534021.

Inflammatory biomarkers predicting long-term remission and active disease in juvenile idiopathic arthritis: a population-based study of the Nordic JIA cohort

OBJECTIVES

To assess the ability of baseline serum biomarkers to predict disease activity and remission status in juvenile idiopathic arthritis (JIA) at 18-year follow-up (FU) in a population-based setting.

METHODS

Clinical data and serum levels of inflammatory biomarkers were assessed in the longitudinal population-based Nordic JIA cohort study at baseline and at 18-year FU. A panel of 16 inflammatory biomarkers was determined by multiplexed bead array assay. We estimated both univariate and multivariate logistic regression models on binary outcomes of disease activity and remission with baseline variables as explanatory variables.

RESULTS

Out of 349 patients eligible for the Nordic JIA cohort study, 236 (68%) had available serum samples at baseline. We measured significantly higher serum levels of interleukin 1β (IL-1β), IL-6, IL-12p70, IL-13, MMP-3, S100A9 and S100A12 at baseline in patients with active disease at 18-year FU than in patients with inactive disease. Computing receiver operating characteristics illustrating the area under the curve (AUC), we compared a conventional prediction model (gender, age, joint counts, erythrocyte sedimentation rate, C reactive protein) with an extended model that also incorporated the 16 baseline biomarkers. Biomarker addition significantly improved the ability of the model to predict activity/inactivity at the 18-year FU, as evidenced by an increase in the AUC from 0.59 to 0.80 (p=0.02). Multiple regression analysis revealed that S100A9 was the strongest predictor of inactive disease 18 years after disease onset.

CONCLUSION

Biomarkers indicating inflammation at baseline have the potential to improve evaluation of disease activity and prediction of long-term outcomes.

Role of serum calprotectin in identifying familial Mediterranean fever attacks

BACKGROUND/AIM

The aim of the study was to evaluate serum calprotectin (CLP) levels in familial Mediterranean fever (FMF) patients and to investigate the utility of CLP in distinguishing patients with attack from patients without attack.

MATERIAL AND METHOD

FMF patients, rheumatoid arthritis (RA) patients, and healthy controls were included. Serum calprotectin levels were quantified utilizing the enzyme-linked immunosorbent assay (ELISA) method. Receiver operating characteristic (ROC) curve analysis was used to identify the cut-off value of serum CLP level to differentiate FMF patients with attack from those without. Logistic regression analysis was performed to identify predictors.

RESULTS

Significant differences were observed among the three groups concerning white blood cell (WBC), neutrophil, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and serum CLP levels (p = 0.003, p = 0.004, p < 0.001, p < 0.001, and p = 0.002, respectively). Higher ESR, CRP, and serum CLP levels were observed in FMF patients with attacks than those without (all, p < 0.001). Serum CLP was significantly higher in RA patients than in FMF patients in remission (p < 0.001). ROC analysis identified a threshold CLP concentration in FMF with an attack to be 47.1 pg/mL (83.3% sensitivity, 60.6% specificity, AUC = 0.74, 95% CI = 0.63-0.85, p < 0.001). In univariate logistic regression analysis, CLP (β = 1.045, 95% CI = 1.017-1.073, p = 0.001) was predictive of FMF patients experiencing an attack.

CONCLUSION

Serum CLP proves to be as productive as ESR in illustrating inflammation and demonstrating the existence of attacks in FMF patients.

Serum Calprotectin Levels in Different Subtypes of Juvenile Idiopathic Arthritis (JIA) and Its Correlation with Quantitative CRP and JADAS-27

OBJECTIVE

To study the serum calprotectin levels in children with juvenile idiopathic arthritis (JIA) and correlate it with C-reactive protein (CRP) and the Juvenile Arthritis Disease Activity Score-27 (JADAS-27).

METHODS

This was a cross-sectional observational study done between November 2017 and March 2019. Fifty treatment-naive children, aged 1 to 18 y with the diagnosis of JIA as per the International League of Associations of Rheumatology (ILAR) criteria were enrolled. Assessment of disease activity was done according to the Juvenile Arthritis Disease Activity Score (JADAS-27). Determination of serum calprotectin and CRP levels was done by immunoassay. The correlation between calprotectin levels with CRP and JADAS-27 was calculated.

RESULTS

Of the 50 patients with JIA included in the study, there were 18 female and 32 male children. The median age of presentation to the hospital was 9 y (IQR 5.82-13). The median JADAS-27 was 14 (IQR 6, 20.25). The median serum calprotectin level was 45,375 ng/mL (IQR 30,725, 52,270; range 8,560-63,160 ng/mL). The median CRP was 35.4 mg/L (IQR 3.48, 80.3; range 0.02 and 107.4 mg/L). The levels of calprotectin in different JIA subtypes were not statistically different using Kruskal-Wallis test. The study also demonstrated a positive correlation between serum calprotectin with CRP and the JADAS-27 (r = 0.418).

CONCLUSION

The calprotectin levels in JIA were significantly higher than those reported in the literature irrespective of the subtype. Serum calprotectin positively correlated with CRP and JADAS-27 in children with JIA.

Treatment of systemic juvenile idiopathic arthritis

Systemic juvenile idiopathic arthritis (sJIA) is an inflammatory disease with hallmarks of severe systemic inflammation, which can be accompanied by arthritis. Contemporary scientific insights set this paediatric disorder on a continuum with its counterpart, adult-onset Still disease (AOSD). Patients with sJIA are prone to complications, including life-threatening hyperinflammation (macrophage activation syndrome (sJIA-MAS)) and sJIA-associated lung disease (sJIA-LD). Meanwhile, the treatment arsenal in sJIA has expanded markedly. State-of-the-art therapeutic approaches include biologic agents that target the IL-1 and IL-6 pathways. Beyond these, a range of novel agents are on the horizon, some of them already being used on a compassionate use basis, including JAK inhibitors and biologic agents that target IL-18, IFNγ, or IL-1β and IL-18 simultaneously. However, sJIA, sJIA-MAS and sJIA-LD still pose challenging conundrums to rheumatologists treating paediatric and adult patients worldwide. Although national and international consensus treatment plans exist for the treatment of 'classic' sJIA, the treatment approaches for early sJIA without arthritis, and for refractory or complicated sJIA, are not well defined. Therefore, in this Review we outline current approaches for the treatment of sJIA and provide an outlook on knowledge gaps.

Molecular Pathways in the Pathogenesis of Systemic Juvenile Idiopathic Arthritis

Systemic juvenile idiopathic arthritis (sJIA) is a rare childhood chronic inflammatory disorder with risk for life-threatening complications including macrophage activation syndrome and lung disease. At onset, sJIA pathogenesis resembles that of the autoinflammatory periodic fever syndromes with marked innate immune activation, expansion of neutrophils and monocytes, and high levels of interleukin-18. Here, we review the current conceptual understanding of sJIA pathogenesis with a focus on both innate and adaptive immune pathways. Finally, we consider how recent progress toward understanding the immunologic basis of sJIA may support new therapies for refractory disease courses.

A novel serum calprotectin (MRP8/14) particle-enhanced immuno-turbidimetric assay (sCAL turbo) helps to differentiate systemic juvenile idiopathic arthritis from other diseases in routine clinical laboratory settings

BACKGROUND

Differential diagnosis in children with signs of unprovoked inflammation can be challenging. In particular, differentiating systemic juvenile idiopathic arthritis (SJIA) from other diagnoses is difficult. We have recently validated the complex of myeloid-related proteins 8/14 (MRP8/14, also known as S100A8/A9 complex or serum calprotectin) as a helpful biomarker supporting the diagnosis of SJIA. The results were subsequently confirmed with a commercial ELISA. However, further optimization of the analytical technology is important to ensure its feasibility for large-scale use in routine laboratory settings.

METHODS

To evaluate the accuracy in identifying children with SJIA, the performance of a particle-enhanced immuno-turbidimetric assay for serum calprotectin (sCAL turbo) on an automated laboratory instrument was analyzed. Samples from 615 children were available with the diagnoses SJIA (n = 99), non-systemic JIA (n = 169), infections (n = 51), other inflammatory diseases (n = 126), and acute lymphoblastic leukemia (ALL, n = 147). In addition, samples from 23 healthy controls were included.

RESULTS

The sCAL turbo assay correlated well with the MRP8/14 ELISA used in previous validation studies (r = 0.99, p < 0.001). It could reliably differentiate SJIA from all other diagnoses with significant accuracy (cutoff at 10,500 ng/ml, sensitivity 84%, specificity 94%, ROC area under curve 0.960, p < 0.001).

CONCLUSIONS

Serum calprotectin analyses are a helpful tool supporting the diagnosis of SJIA in children with prolonged fever or inflammatory disease. Here, we show that an immuno-turbidimetric assay for detection of serum calprotectin on an automated laboratory instrument can be implemented in clinical laboratory settings to facilitate its use as a diagnostic routine test in clinical practice.

S100A8 and S100A9 are associated with endometrial shedding during menstruation

Matrix metalloproteinases (MMPs) and their major source, endometrial stromal cells (ESCs), play important roles in menstruation. However, other mechanisms in endometrial shedding may be unexplored. This study focused on four proteins: S100A8 and S100A9 (alarmins) are binding partners and induce MMPs, MMP-3 cycle-dependently plays a key role in the proteolytic cascade, and CD147, which has S100A9 as its ligand, induces MMPs. Immunostaining for these proteins was performed on 118 resected specimens. The percentage and location of each positive reaction in ESCs were measured and compared using Image J. The influence of leukocytes on S100A8 or S100A9 immunopositivity was also examined. From the premenstrual phase, S100A8 and MMP-3 began to have overlapping expressions in ESCs of the superficial layer, and ESC detachment was found within these sites. S100A9 was expressed from the late secretory phase and CD147 already from earlier. Later, the expression sites of S100A9 and CD147 included those of S100A8. Before menstruation, S100A8 or S100A9 expression was not affected by leukocytes. These results suggest that the local formation of S100A8/S100A9 complex, which occurs specifically in ESCs upon progesterone withdrawal, induces the local expression of MMP-3 and serves as a switch to the lysis phase.

Inflammatory Biomarkers Can Differentiate Acute Lymphoblastic Leukemia with Arthropathy from Juvenile Idiopathic Arthritis Better Than Standard Blood Tests

OBJECTIVE

To evaluate the predictive value of biomarkers of inflammation like phagocyte-related S100 proteins and a panel of inflammatory cytokines in order to differentiate the child with acute lymphoblastic leukemia (ALL) from juvenile idiopathic arthritis (JIA).

STUDY DESIGN

In this cross-sectional study, we measured S100A9, S100A12, and 14 cytokines in serum from children with ALL (n = 150, including 27 with arthropathy) and JIA (n = 236). We constructed predictive models computing areas under the curve (AUC) as well as predicted probabilities in order to differentiate ALL from JIA. Logistic regression was used for predictions of ALL risk, considering the markers as the respective exposures. We performed internal validation using repeated 10-fold cross-validation and recalibration, adjusted for age.

RESULTS

In ALL, the levels of S100A9, S100A12, interleukin (IL)-1 beta, IL-4, IL-13, IL-17, matrix metalloproteinase-3, and myeloperoxidase were low compared with JIA (P < .001). IL-13 had an AUC of 100% (95% CI 100%-100%) due to no overlap between the serum levels in the 2 groups. Further, IL-4 and S100A9 had high predictive performance with AUCs of 99% (95% CI 97%-100%) and 98% (95% CI 94%-99%), respectively, exceeding both hemoglobin, platelets, C-reactive protein, and erythrocyte sedimentation rate.

CONCLUSIONS

The biomarkers S100A9, IL-4, and IL-13 might be valuable markers to differentiate ALL from JIA.

Phagocyte-related S100 proteins and cytokines in acute lymphoblastic leukemia and their prognostic value

In this retrospective cohort study, we evaluated the level of biomarkers of inflammation like phagocyte-related S100 proteins and a panel of cytokines in 128 children with pre-B ALL and 22 with T-ALL. The biomarkers were evaluated at diagnosis and during antileukemic therapy (day 29 and after six months) and we evaluated their correlation with basic laboratory values. Further, for the children with pre-B ALL, we evaluated whether the biomarkers could predict the outcome of ALL expressed as minimal residual disease (MRD), relapse, and death.The levels of S100A9, S100A12, IL-1beta, IL-12p70, IL-13, IL-17, IL-18, and MPO serum levels increased significantly as chemotherapy was initiated. The difference was most pronounced for S100A9 and S100A12, which had strong positive correlations with the neutrophil counts. In contrast, TNF-alpha, IL-6, IL-10, CCL-2, MMP-3, and CD25 serum levels decreased after chemotherapy. Although none of these biomarkers appear to be an independent predictor of outcomes, in predictive models with MRD as the outcome, AUC increased from 76% (95% CI 68-84%) when using initial risk group stratification alone to 83% (95% CI 73-91%) in a multivariate predictive model including initial risk group stratification and the biomarkers S100A12, TNF-alpha, and IL-10.

Inflammatory bone marrow signaling in pediatric acute myeloid leukemia distinguishes patients with poor outcomes

High levels of the inflammatory cytokine IL-6 in the bone marrow are associated with poor outcomes in pediatric acute myeloid leukemia (pAML), but its etiology remains unknown. Using RNA-seq data from pre-treatment bone marrows of 1489 children with pAML, we show that > 20% of patients have concurrent IL-6, IL-1, IFNα/β, and TNFα signaling activity and poorer outcomes. Targeted sequencing of pre-treatment bone marrow samples from affected patients (n = 181) revealed 5 highly recurrent patterns of somatic mutation. Using differential expression analyses of the most common genomic subtypes (~60% of total), we identify high expression of multiple potential drivers of inflammation-related treatment resistance. Regardless of genomic subtype, we show that JAK1/2 inhibition reduces receptor-mediated inflammatory signaling by leukemic cells in-vitro. The large number of high-risk pAML genomic subtypes presents an obstacle to the development of mutation-specific therapies. Our findings suggest that therapies targeting inflammatory signaling may be effective across multiple genomic subtypes of pAML.

Biomarkers in Systemic Juvenile Idiopathic Arthritis, Macrophage Activation Syndrome and Their Importance in COVID Era

Systemic juvenile idiopathic arthritis (sJIA) and its complication, macrophage activation syndrome (sJIA-MAS), are rare but sometimes very serious or even critical diseases of childhood that can occasionally be characterized by nonspecific clinical signs and symptoms at onset-such as non-remitting high fever, headache, rash, or arthralgia-and are biologically accompanied by an increase in acute-phase reactants. For a correct positive diagnosis, it is necessary to rule out bacterial or viral infections, neoplasia, and other immune-mediated inflammatory diseases. Delays in diagnosis will result in late initiation of targeted therapy. A set of biomarkers is useful to distinguish sJIA or sJIA-MAS from similar clinical entities, especially when arthritis is absent. Biomarkers should be accessible to many patients, with convenient production and acquisition prices for pediatric medical laboratories, as well as being easy to determine, having high sensitivity and specificity, and correlating with pathophysiological disease pathways. The aim of this review was to identify the newest and most powerful biomarkers and their synergistic interaction for easy and accurate recognition of sJIA and sJIA-MAS, so as to immediately guide clinicians in correct diagnosis and in predicting disease outcomes, the response to treatment, and the risk of relapses. Biomarkers constitute an exciting field of research, especially due to the heterogeneous nature of cytokine storm syndromes (CSSs) in the COVID era. They must be selected with utmost care-a fact supported by the increasingly improved genetic and pathophysiological comprehension of sJIA, but also of CSS-so that new classification systems may soon be developed to define homogeneous groups of patients, although each with a distinct disease.

Improving Diagnosis and Clinical Management of Acquired Systemic Autoinflammatory Diseases

Systemic autoinflammatory diseases (SAID) are conditions caused by dysregulation or disturbance of the innate immune system, with neutrophils and macrophages the main effector cells. Although there are now more than 40 distinct, genetically defined SAIDs, the genetic/molecular diagnosis remains unknown for a significant proportion of patients with the disease onset in adulthood. This review focuses on new developments related to acquired/late onset SAID, including phenocopies of monogenic disorders, Schnitzler's syndrome, Adult onset Still's disease, VEXAS syndrome, and autoinflammatory complications associated with myelodysplastic syndrome.

The Good and the Bad: Monocytes' and Macrophages' Diverse Functions in Inflammation

Monocytes and macrophages are central players of the innate immune response and play a pivotal role in the regulation of inflammation. Thereby, they actively participate in all phases of the immune response, from initiating inflammation and triggering the adaptive immune response, through to the clearance of cell debris and resolution of inflammation. In this review, we described the mechanisms of monocyte and macrophage adaptation to rapidly changing microenvironmental conditions and discussed different forms of macrophage polarization depending on the environmental cues or pathophysiological condition. Therefore, special focus was placed on the tight regulation of the pro- and anti-inflammatory immune response, and the diverse functions of S100A8/S100A9 proteins and the scavenger receptor CD163 were highlighted, respectively. We paid special attention to the function of pro- and anti-inflammatory macrophages under pathological conditions.

Neutrophil Homeostasis and Emergency Granulopoiesis: The Example of Systemic Juvenile Idiopathic Arthritis

Neutrophils are key pathogen exterminators of the innate immune system endowed with oxidative and non-oxidative defense mechanisms. More recently, a more complex role for neutrophils as decision shaping cells that instruct other leukocytes to fine-tune innate and adaptive immune responses has come into view. Under homeostatic conditions, neutrophils are short-lived cells that are continuously released from the bone marrow. Their development starts with undifferentiated hematopoietic stem cells that pass through different immature subtypes to eventually become fully equipped, mature neutrophils capable of launching fast and robust immune responses. During severe (systemic) inflammation, there is an increased need for neutrophils. The hematopoietic system rapidly adapts to this increased demand by switching from steady-state blood cell production to emergency granulopoiesis. During emergency granulopoiesis, the de novo production of neutrophils by the bone marrow and at extramedullary sites is augmented, while additional mature neutrophils are rapidly released from the marginated pools. Although neutrophils are indispensable for host protection against microorganisms, excessive activation causes tissue damage in neutrophil-rich diseases. Therefore, tight regulation of neutrophil homeostasis is imperative. In this review, we discuss the kinetics of neutrophil ontogenesis in homeostatic conditions and during emergency myelopoiesis and provide an overview of the different molecular players involved in this regulation. We substantiate this review with the example of an autoinflammatory disease, i.e. systemic juvenile idiopathic arthritis.

Evaluation of Serum Calprotectin Levels in Patients with Inflammatory Bowel Disease

BACKGROUND

Fecal calprotectin has been proposed as a useful biomarker of disease activity in inflammatory bowel disease (IBD). However, the role of calprotectin in systemic circulation is not well established. Thus, this study aimed to quantify serum calprotectin levels to identify a potential inflammatory marker for IBD.

METHODS

Ninety-eight patients with ulcerative colitis (UC) and 105 patients with Crohn's disease (CD) were prospectively enrolled and clinically scored. Ninety-two healthy, age-matched subjects served as controls. Blood samples from UC and CD patients and controls were analyzed for serum calprotectin levels and routine laboratory parameters. Disease activity was assessed by partial Mayo score and Harvey-Bradshaw index for UC and CD, respectively.

RESULTS

Serum calprotectin levels were higher in CD and UC patients than in controls and were higher during active disease than during inactive disease in CD but not in UC. In UC, serum calprotectin levels were correlated with C-reactive protein (CRP) but not with other laboratory parameters or disease activity. In CD, serum calprotectin levels were positively correlated with disease activity, serum CRP, and platelet count. In UC and CD, serum calprotectin and CRP levels increased during the acute phase and decreased towards remission.

CONCLUSIONS

Serum calprotectin is an inflammatory marker in IBD but might be more effective in evaluating patients with CD than those with UC. Further studies are needed to confirm these findings and to better determine the specific uses of serum calprotectin in routine practice.

An Update on the Pathogenic Role of Neutrophils in Systemic Juvenile Idiopathic Arthritis and Adult-Onset Still's Disease

Neutrophils are innate immune phagocytes that play a key role in immune defense against invading pathogens. The main offensive mechanisms of neutrophils are the phagocytosis of pathogens, release of granules, and production of cytokines. The formation of neutrophil extracellular traps (NETs) has been described as a novel defense mechanism in the literature. NETs are a network of fibers assembled from chromatin deoxyribonucleic acid, histones, and neutrophil granule proteins that have the ability to kill pathogens, while they can also cause toxic effects in hosts. Activated neutrophils with NET formation stimulate autoimmune responses related to a wide range of inflammatory autoimmune diseases by exposing autoantigens in susceptible individuals. The association between increased NET formation and autoimmunity was first reported in antineutrophil cytoplasmic antibody-related vasculitis, and the role of NETs in various diseases, including systemic lupus erythematosus, rheumatoid arthritis, and psoriasis, has since been elucidated in research. Herein, we discuss the mechanistic role of neutrophils, including NETs, in the pathogenesis of systemic juvenile idiopathic arthritis (SJIA) and adult-onset Still’s disease (AOSD), and provide their clinical values as biomarkers for monitoring and prognosis.

Role of Serum MRP8/14 in Predicting Response to Methotrexate in Children With Juvenile Idiopathic Arthritis

OBJECTIVE

Nearly 40% of children with juvenile idiopathic arthritis (JIA) might not respond to first-line disease-modifying antirheumatic drugs (DMARDs) including methotrexate (MTX). Hence, there is a need for a biomarker that can predict MTX response and help in tailoring initial therapy. Our objective was to study the role of serum myeloid-related protein (MRP) 8/14, and other inflammatory cytokines, as predictors of response to MTX among children with JIA.

METHODS

We did a longitudinal follow-up study among children diagnosed with JIA at our institute. All MTX-naive children with JIA requiring DMARDs were eligible for this study; those who either took corticosteroids or DMARDs for more than 6 weeks at time of presentation were excluded. The demographic and clinical information was collected using a pretested semistructured questionnaire, and selected biomarkers were collected at baseline and again at 3 months. Response at 3 months was assessed using the American College of Rheumatology (ACR) criteria; responders were children who achieved ACR50, whereas those failing to achieve ACR30 were classified as nonresponders. Multivariate binary logistic regression was done to assess determinants of being a responder.

RESULTS

We enrolled 69 children (36 boys) with JIA, of which 48 (69.5%) were responders. The baseline value of serum MRP8/14 was significantly higher in responders (median, 144.34 [interquartile range, 88.54-188.34] ng/mL) compared with the nonresponders (median, 95.34 [interquartile range, 76.54-130.28] ng/mL), p = 0.047. Being a responder was significantly associated with baseline serum MRP8/14 with adjusted odds ratio of 1.01 (95% confidence interval, 1.00-1.02).

CONCLUSIONS

The baseline levels of MRP8/14 were significantly raised in children meeting ACR50 at follow-up and suggest a prognostic value in predicting response to MTX.

Loss-of-function mutation in IKZF2 leads to immunodeficiency with dysregulated germinal center reactions and reduction of MAIT cells

[Figure: see text].

A dysregulated interleukin-18-interferon-γ-CXCL9 axis impacts treatment response to canakinumab in systemic juvenile idiopathic arthritis

OBJECTIVES

The monoclonal IL-1β antibody canakinumab is approved for the treatment of systemic juvenile idiopathic arthritis (SJIA). Its efficacy has been proven in several trials, but not all patients show a complete and sustained response to therapy. We aimed to analyse the association of baseline serum biomarkers with treatment outcome in patients with SJIA treated with canakinumab.

METHODS

Serum samples from 54 patients with active SJIA without recent macrophage activation syndrome (MAS) treated with canakinumab in an open-label response characterization study were subjected to a multiplexed bead array assay. Interesting targets from these analyses were validated by ELISA. Clinical treatment outcomes included modified paediatric ACR (pACR) 30 and 90 responses, clinically inactive disease (CID) within 15 days of treatment and sustained complete response, defined as pACR100 or CID within 15 days of treatment plus no future flare or MAS.

RESULTS

In canakinumab-naïve patients most biomarkers were elevated when compared with healthy controls at baseline and some rapidly decreased by day 15 [IL-1 receptor antagonist (IL-1RA), IL-6, IL-18 and S100A12]. Responders had higher IL-18 and IFN-γ levels and lower chemokine (C-X-C motif) ligand 9 (CXCL9) levels at baseline, emphasized by the IL-18: CXCL9 and IFN-γ: CXCL9 ratios. These ratios had significant accuracy in predicting treatment responses.

CONCLUSION

Differential regulation of the IL-18-IFN-γ-CXCL9 axis is observed in patients with SJIA. Higher IL-18: CXCL9 and IFN-γ: CXCL9 ratios at baseline are associated with a better clinical response to canakinumab treatment in SJIA. Future studies are needed to validate these findings and determine their generalizability to patients with recent MAS.

MRP8/14 serum levels as diagnostic markers for systemic juvenile idiopathic arthritis in children with prolonged fever

OBJECTIVES

Differential diagnosis in children with prolonged fever is challenging. In particular, differentiating systemic-onset juvenile idiopathic arthritis (SJIA) from infectious diseases is difficult. Biomarkers are needed supporting the diagnostic work-up. The aim of this study was to validate the usefulness of MRP8/14 measurements in the diagnostic wok-up of febrile children and transfer it to clinical practice.

METHODS

Data of 1,110 paediatric patients were included and divided into two cohorts: (A) For validation of MRP8/14 test performance with 3 different testing systems: the experimental enzyme-linked immunosorbent sandwich assay (ELISA), commercial ELISA and an innovative (POCT) lateral flow immunoassay (LFIA); (B) to validate the diagnostic accuracy with the two latter assays.

RESULTS

In cohort A (n = 940), MRP8/14 was elevated in SJIA (12110±2650 ng/ml mean ± 95% CI) compared to other diagnoses (including infections and autoinflammatory diseases; 2980±510 ng/ml) irrespective of fever and anti-inflammatory treatment (p < 0.001). In untreated patients with fever (n = 195) MRP8/14 levels in SJIA (19740±5080 ng/ml) were even higher compared to other diagnoses (4590±1160 ng/ml) (p < 0.001, sensitivity 73%, specificity 90%). In cohort B1, the performance of the tests was confirmed in untreated patients with fever (n = 170): commercial ELISA (sensitivity 79%, specificity 89%) and LFIA (sensitivity 84%, specificity 81%). Compared with ferritin, IL-18, ESR, sIL2-R, and procalcitonin, MRP8/14 showed the best accuracy.

CONCLUSION

MRP8/14 serum analyses have been validated as a helpful tool supporting the diagnosis of SJIA in febrile children. The results could be confirmed with commercial ELISA and LFIA enabling a rapid diagnostic point-of-care screening test.

Serum calprotectin (S100A8/A9): a promising biomarker in diagnosis and follow-up in different subgroups of juvenile idiopathic arthritis

Introduction

In the management of juvenile idiopathic arthritis (JIA), there is a lack of diagnostic and prognostic biomarkers. This study assesses the use of serum calprotectin (sCal) as a marker to monitor disease activity, and as a classification and prognosis tool of response to treatment or risk of flares in patients with JIA.

Methods

Eighty-one patients with JIA from the CAP48 multicentric cohort were included in this study, as well as 11 non-paediatric healthy controls. An ELISA method was used to quantify sCal with a commercial kit.

Results

Patients with an active disease compared with healthy controls and with patients with inactive disease showed an eightfold and a twofold increased level of sCal, respectively. sCal was found to be correlated with the C-reactive protein (CRP) and even more strongly with the erythrocyte sedimentation rate. Evolution of DAS28 scores correlated well with evolution of sCal, as opposed to evolution of CRP. With regard to CRP, sCal could differentiate forms with active oligoarthritis from polyarthritis and systemic forms. However, sCal brought an added value compared with the CRP as a prognosis marker. Indeed, patients with active disease and reaching minimal disease activity (according to Juvenile Arthritis Disease Activity Score) at 6 months following the test had higher sCal levels, while patients with inactive disease had higher sCal levels if a flare was observed up to 3–9 months following the test.

Conclusions

This study confirms the potential uses of sCal as a biomarker in the diagnosis and follow-up of JIA.

Definition and validation of serum biomarkers for optimal differentiation of hyperferritinaemic cytokine storm conditions in children: a retrospective cohort study

BACKGROUND

Cytokine storm syndromes are life-threatening complications that can occur in children with rheumatic conditions (macrophage activation syndrome [MAS]), inherited cytotoxicity defects (ie, primary haemophagocytic lymphohistiocytosis [HLH]), or as a result of infection or malignancies (ie, secondary HLH). To adequately steer treatment, an early and clear discrimination of these entities is essential. We aimed to define and validate serum biomarker profiles that can differentiate between primary HLH, secondary HLH (predominantly infection-associated), and MAS associated with systemic juvenile idiopathic arthritis (systemic JIA-MAS).

METHODS

In this multicentre, retrospective, cohort study, serum samples from patients (0-18 years) with a clinical diagnosis of primary HLH, secondary HLH, or systemic JIA-MAS were analysed by immunoassays for 55 cytokines and chemokines. Serum samples were collected from patients treated at seven clinical centres in Europe and North America. 15 serum biomarkers were validated using an independent commercial assay, and the diagnostic accuracy of the best performing biomarkers was tested in an independent validation cohort.

FINDINGS

Serum samples were collected between Dec 7, 2010, and Jan 26, 2018. In the discovery cohort of 43 patients (24 girls and 19 boys) multi-marker analyses revealed distinct serum biomarker profiles associated with primary or secondary HLH versus systemic JIA-MAS. Ten biomarkers were identified that were differentially elevated in either HLH or systemic JIA-MAS and distinguished between these clinical entities, six of which were tested in an independent validation cohort of 79 patients (34 girls and 45 boys). Serum concentrations of S100A12 and interleukin-18, as well as ratios of both S100A12 and IL-18 with chemokine (C-X-C motif) ligand (CXCL)9 and CXCL10 were identified as the most promising candidates for differential diagnostics.

INTERPRETATION

At initial presentation, when it is unclear whether a patient with excessive hyperferritinaemic inflammation has primary HLH, infection-associated secondary HLH, or MAS, high serum concentrations of S100A12 indicate an initial differential diagnosis of systemic JIA-MAS, thus helping to guide subsequent treatment decisions. We therefore suggest the inclusion of serum S100A12 and IL-18 in the diagnostic investigations for hyperferritinaemic syndromes; however, the definition and introduction of universially applicable cutoff values are still required.

FUNDING

German Research Foundation, the Center for Interdisciplinary Clinical Research at University Hospital Muenster, the EU's Horizon 2020 research and innovation programme, and the Deutsche Kinderkrebsstiftung.

Signals and Mechanisms Regulating Monocyte and Macrophage Activation in the Pathogenesis of Juvenile Idiopathic Arthritis

Monocytes (Mos) and macrophages (Mφs) are key players in the innate immune system and are critical in coordinating the initiation, expansion, and regression of many autoimmune diseases. In addition, they display immunoregulatory effects that impact inflammation and are essential in tissue repair and regeneration. Juvenile idiopathic arthritis (JIA) is an umbrella term describing inflammatory joint diseases in children. Accumulated evidence suggests a link between Mo and Mφ activation and JIA pathogenesis. Accordingly, topics regarding the signals and mechanisms regulating Mo and Mφ activation leading to pathologies in patients with JIA are of great interest. In this review, we critically summarize recent advances in the understanding of how Mo and Mφ activation is involved in JIA pathogenesis and focus on the signaling pathways and mechanisms participating in the related cell activation processes.

Novel biomarkers for prediction of outcome and therapeutic response in juvenile idiopathic arthritis

INTRODUCTION

The search for biomarkers in juvenile idiopathic arthritis (JIA) is a promising and rapidly expanding field of investigation. The biomarkers identified so far may help to dissect the clinical heterogeneity of the illness, measure the level of disease activity, predict clinical remission, relapse, response to medications, course over time, complications, and forestall disease flares.

AREAS COVERED

We provide a summary of the most recent advances in the development and application of biomarkers in JIA. We performed a PubMed search for significant articles combining predetermined keywords related to biomarkers in non-systemic and systemic JIA, chronic uveitis, and macrophage activation syndrome (MAS). The biomarkers available or under study are presented and discussed separately for non-systemic and systemic subtypes and for the two main disease complications, uveitis and MAS.

EXPERT OPINION

The incorporation of valid and reliable biomarkers in standard clinical care may help to design better patient-tailored treatment regimens and to improve the therapeutic strategies based on the treat-to-target approach. The establishment of biomarkers that predict the risk of disease flare may lead to define the optimal modalities for treatment discontinuation after the achievement of clinical remission.

Lipopolysaccharide stimulation test on cultured PBMCs assists the discrimination of cryopyrin-associated periodic syndrome from systemic juvenile idiopathic arthritis

Systemic juvenile idiopathic arthritis (sJIA) and cryopyrin-associated periodic syndrome (CAPS) share many common manifestations. We aim to identify an applicable method to assist disease discrimination. Inflammatory cytokines were measured in the plasma of patients with CAPS, sJIA with persistent disease course and healthy controls. Supernatants collected from non-stimulated peripheral blood mononuclear cells (PBMCs) and those undergone inflammasome stimulation tests utilizing lipopolysaccharide (LPS) with and without adenosine triphosphate (ATP) were investigated. Inflammatory cytokines in patient plasma fail to differentiate sJIA from CAPS. PBMCs from sJIA secrets higher amount of IL-1β and IL-18 while CAPS PBMCs produces more caspase-1 without stimulation. IL-1β, IL-18, and caspase-1 were significantly elevated among CAPS PBMCs (all p < 0.05) upon LPS stimulation, but not when additional ATPs were provided. Levels of cytokines and PBMC responses to the stimulation assays were similar among all sJIA patients regardless of their history of macrophage activation syndrome. Unstimulated PBMC activities and the LPS inflammasome stimulation assay without exogenic ATPs can assist the differentiation of CAPS from sJIA with persistent disease course.

Neutrophil extracellular trap-associated molecules: a review on their immunophysiological and inflammatory roles

Neutrophil extracellular traps (NETs) are a defense mechanism against pathogens. They are composed of DNA and various proteins and have the ability to hinder microbial spreading and survival. However, NETs are not only related to infections but also participate in sterile inflammatory events. In addition to DNA, NETs contain histones, serine proteases, cytoskeletal proteins and antimicrobial peptides, all of which have immunomodulatory properties that can augment or decrease the inflammatory response. Extracellular localization of these molecules alerts the immune system of cellular damage, which is triggered by recognition of damage-associated molecular patterns (DAMPs) through specific pattern recognition receptors. However, not all of these molecules are DAMPs and may have other immunophysiological properties in the extracellular space. The release of NETs can lead to production of pro-inflammatory cytokines (due to TLR2/4/9 and inflammasome activation), the destruction of the extracellular matrix, activation of serine proteases and of matrix metallopeptidases (MMPs), modulation of cellular proliferation, induction of cellular migration and adhesion, promotion of thrombogenesis and angiogenesis and disruption of epithelial and endothelial permeability. Understanding the dynamics of NET-associated molecules, either individually or synergically, will help to unravel their role in inflammatory events and open novel perspectives for potential therapeutic targets. We here review molecules contained within NETS and their immunophysiological roles.

The Role of Plasma Calprotectin in Non-infectious Uveitis

PURPOSE

To investigate the role of plasma calprotectin in non-infectious uveitis.

METHODS

This is an observational both cross-sectional and prospective study. Patients with active non-infectious uveitis were recruited as well as nonuveitic controls. Plasma calprotectin was determined and an ophthalmological examination was performed for both patients and controls. Independent variables possibly influencing levels of plasma calprotectin were recorded and analyzed. Categorical variables were compared by chi-square test (applying correction by continuity if necessary). T-test (or Kruskal-Wallis when appropriate) was used to compare averages. Multiple linear regression analysis was used to assess relationship between plasma calprotectin levels and independent variables. Spearman coefficient was calculated in order to establish correlation between plasma calprotectin and anterior chamber cell grading. Changes in plasma calprotectin levels between the flare beginning and its resolution were determined with mixed model for repeated measures. R software (version 3.6.0) was used to perform the statistical analysis.

RESULTS

We included 74 patients and 40 controls in the cross-sectional study. Plasma calprotectin levels were higher in uveitis patients compared to those of controls (p = .003), being higher in younger patients and patients with posterior uveitis. No correlation between calprotectin and anterior chamber inflammation degree was found (p = .198). For the prospective study, we included 36 patients. We found no significant differences in calprotectin levels between active and inactive uveitis (p = .344).

CONCLUSIONS

Plasma calprotectin levels are elevated in uveitis patients and are influenced by age and anatomical location of uveitis. Further investigation is needed to assess the relationship between calprotectin and uveitis activity.

Roles of Interactions Between Toll-Like Receptors and Their Endogenous Ligands in the Pathogenesis of Systemic Juvenile Idiopathic Arthritis and Adult-Onset Still's Disease

Systemic juvenile idiopathic arthritis (JIA) and adult-onset Still’s disease (AOSD) are systemic inflammatory disorders that manifest as high-spiking fever, joint pain, evanescent skin rash, and organomegaly. Their pathogenesis is unclear, but inflammation is triggered by activation of the innate immune system with aberrant production of proinflammatory cytokines. Along with extrinsic factors, intrinsic pathways can trigger an unexpected immune response. Damage-associated molecular patterns (DAMPs) induce the activation of innate immune cells, leading to sterile inflammation in systemic JIA and AOSD. These endogenous proteins interact with Toll-like receptors (TLRs), which are pattern recognition receptors, and mediate immune signaling following stimulation by pathogen-associated molecular patterns and DAMPs. Several DAMPs, such as S100 proteins, play a role in the development or severity of systemic JIA and AOSD, in which their interactions with TLRs are altered. Also, the expression levels of genes encoding DAMPs contribute to the susceptibility to systemic JIA and AOSD. Herein, we review reports that TLR and DAMP signaling initiates and/or maintains the inflammatory response in systemic JIA and AOSD, and their correlations with the clinical characteristics of those diseases. In addition, we assess their utility as biomarkers or therapeutics for systemic JIA and AOSD.

How autoinflammation may turn into autoimmune inflammation: Insights from monogenetic and complex IL-1 mediated auto-inflammatory diseases

IL-1 mediated auto-inflammatory diseases are characterised by episodes of unexplained fever, generalized and localized inflammation. The characteristic symptoms predominantly result from exaggerated activation of innate immune pathways. However, in some patients with typical IL-1 mediated diseases, chronic disease manifestations develop in the absence of acute inflammation, suggesting the involvement of adaptive immune pathways. We discuss clinical observations as well as novel insights in how chronic activation of innate immune pathways can lead to auto-immune disease features in patients with auto-inflammatory diseases and how we need to better understand these sequelae in order to improve treatment strategies.

[Injuries in children and adolescents with inflammatory rheumatic diseases : Special risks and techniques for fracture treatment of the growing skeleton]

BACKGROUND

Inflammatory rheumatic diseases in childhood and adolescence are a special challenge in the treatment of acute trauma. The pharmaceutical treatment strategies for children and adolescents have been modified.

OBJECTIVE

Which special aspects must be considered in young patients suffering from rheumatism when a trauma necessitates an operative procedure?

MATERIAL AND METHOD

A literature search was carried out to elaborate recommendations for the practice.

RESULTS

The joint-related alterations in young patients suffering from rheumatism differ with respect to the differently altered inflammatory rheumatic destruction. The extent of these inflammatory destructive alterations dictates the operative approach. Consequences arise in paying attention to the concurrent medication with respect to avoidance of events triggering an exacerbation and tissue infections. The bone strength necessitates an individualized selection of implants and sometimes influences the duration of follow-up treatment. In the early stages of the inflammatory process the approach in cases of trauma is no different to that for healthy patients but in later stages (Larsen stage III) it does differ.

CONCLUSION

An interdisciplinary concept can help to avoid disadvantages in the treatment of the underlying disease. Due to the special dysplastic anatomy and tissue alterations, trauma in these patients is a particular challenge.

S100-Alarmins Are Essential Pilots of Postnatal Innate Immune Adaptation

The restricted capacity of newborn infants to mount inflammatory responses toward microbial challenges has traditionally been linked to the high risk of septic diseases during the neonatal period. In recent years, substantial evidence has been provided that this characteristic of the neonatal immune system is actually a meaningful physiologic state that is based on specific transiently active cellular and molecular mechanisms and required for a favorable course of postnatal immune adaptation. The identification of physiologically high amounts of S100-alarmins in neonates has been one of the crucial pieces in the puzzle that contributed to the change of concept. In this context, innate immune immaturity could be redefined and assigned to the epigenetic silence of adult-like cell-autonomous regulation at the beginning of life. S100-alarmins represent an alternative age-specific mechanism of immune regulation that protects neonates from hyperinflammatory immune responses. Here, we summarize how infants are provided with S100-alarmins and why these allow an uneventful clash between the innate immune system and the extrauterine world. The mode of action of S100-alarmins is highlighted including their tuning functions at multiple levels for establishing a state of homeostasis with the environment in the newborn individual.

Th17 reprogramming of T cells in systemic juvenile idiopathic arthritis

Systemic juvenile idiopathic arthritis (sJIA) begins with fever, rash, and high-grade systemic inflammation but commonly progresses to a persistent afebrile arthritis. The basis for this transition is unknown. To evaluate a role for lymphocyte polarization, we characterized T cells from patients with acute and chronic sJIA using flow cytometry, mass cytometry, and RNA sequencing. Acute and chronic sJIA each featured an expanded population of activated Tregs uncommon in healthy controls or in children with nonsystemic JIA. In acute sJIA, Tregs expressed IL-17A and a gene expression signature reflecting Th17 polarization. In chronic sJIA, the Th17 transcriptional signature was identified in T effector cells (Teffs), although expression of IL-17A at the protein level remained rare. Th17 polarization was abrogated in patients responding to IL-1 blockade. These findings identify evolving Th17 polarization in sJIA that begins in Tregs and progresses to Teffs, likely reflecting the impact of the cytokine milieu and consistent with a biphasic model of disease pathogenesis. The results support T cells as a potential treatment target in sJIA.

The use of S100 proteins testing in juvenile idiopathic arthritis and autoinflammatory diseases in a pediatric clinical setting: a retrospective analysis

BACKGROUND

Serum phagocyte-derived alarmins S100A8/9 and S100A12 are considered useful for the assessment of inflammatory diseases. Our study evaluated the use of S100 proteins in a pediatric clinical setting for estimating disease activity and supporting diagnosis.

METHODS

Patients (n = 136) who had S100 proteins tested as part of clinical care were included in this study and relevant information obtained from the medical record: C-reactive protein (CRP), disease activity status (inactive: = 0 joint; active: > 0 active joint), systemic symptoms in systemic JIA (sJIA), and symptoms of flare of other autoinflammatory and fever syndromes. Patients were categorized as: sJIA, non-systemic JIA (nsJIA), other defined autoinflammatory syndromes (AID) and systemic undifferentiated recurring fever syndromes (SURFS).

RESULTS

Patients with sJIA (n = 21) had significantly higher levels of S100A8/9 and S100A12 compared to patients with nsJIA (n = 49), other AIDs (n = 8) or SURFS (n = 14) (all p < 0.0001). Compared to CRP [area under the receiver operating characteristics curve (AUC) = 0.7], S100 proteins were superior in differentiating sJIA from AID and SURFS [AUC = 0.9]. S100A8/9 and S100A12 levels were not associated with disease activity in nsJIA, AID or SURFS. S100A8/9 and S100A12 levels were significantly higher in active sJIA compared to inactive (p = 0.0002 and p = 0.0002 respectively).

CONCLUSION

Compared to other autoinflammatory and fever syndromes, sJIA patients have markedly higher levels of S100A8/9 and S100A12 proteins which may assist with diagnosis. S100 levels slightly outperformed CRP in distinguishing sJIA from other diagnoses and in sJIA disease activity. S100 proteins may aid in monitoring disease activity in sJIA patients.

Innately Adaptive or Truly Autoimmune: Is There Something Unique About Systemic Juvenile Idiopathic Arthritis?

Systemic juvenile idiopathic arthritis (JIA) is a form of arthritis in childhood that is initially dominated by innate immunity-driven systemic inflammation and is thus considered a polygenic autoinflammatory disease. However, systemic JIA can progress toward an adaptive immunity-driven afebrile arthritis. Based on this observation of biphasic disease progression, a "window of opportunity" for optimal, individualized and target-directed treatment has been proposed. This hypothesis requires testing, and in this review we summarize current evidence regarding molecular factors that may contribute to the progression from an initially predominantly autoinflammatory disease phenotype to autoimmune arthritis. We consider the involvement of innately adaptive γδ T cells and natural killer T cells that express γδ or αβ T cell receptors but cannot be classified as either purely innate or adaptive cells, versus classic B and T lymphocytes in this continuum. Finally, we discuss our understanding of how and why some primarily autoinflammatory conditions can progress toward autoimmune-mediated disorders over the disease course while others do not and how this knowledge may be used to offer individualized treatment.

The Role of Inflammation in the Endothelial Dysfunction in a Cohort of Pediatric Patients With Inflammatory Bowel Disease

OBJECTIVES

Chronic inflammation plays a central role in the etiology of endothelial damage. Endothelial dysfunction (ED) is the inability of the artery to dilate in response to an endothelial stimulus. We assessed the ED by measuring the reactive hyperaemia index (RHI) and the flow-mediated dilation (FMD) in a cohort of pediatric patients affected by inflammatory bowel disease (IBD) and comparing these parameters to a group of healthy controls (HC).

METHODS

Forty-one patients were consecutive enrolled. ED was evaluated by both the plethysmographic RHI method and the measurement of the FMD of brachial artery after occlusion of the blood flow. Differences between patients and controls were assessed by the Mann-Whitney test. In each patient with IBD, the main inflammation markers were detected and correlated to RHI and FMD by a linear regression test.

RESULTS

We enrolled 26 (59%) patients with IBD and 18 (41%) HC. When comparing FMD value at diagnosis it was significantly lower in IBD patients than in HC (P = 0.04). This result was confirmed at follow-up, when this difference became even more significant (P = 0.004). A significant indirect correlation was found between FMD and fecal calprotectin (r: 0.17; P = 0.04). No differences were found when comparing RHI.

CONCLUSIONS

Our results suggest that inflammation could lead to ED assessed by ultrasound FMD. These data were not confirmed by RHI; however, this could be due to the lack of a standardized pediatric cut-off. More studies are necessary to confirm our data.

Molecular signature characterisation of different inflammatory phenotypes of systemic juvenile idiopathic arthritis

Objectives

The International League of Associations for Rheumatology classification criteria define systemic juvenile idiopathic arthritis (SJIA) by the presence of fever, rash and chronic arthritis. Recent initiatives to revise current criteria recognise that a lack of arthritis complicates making the diagnosis early, while later a subgroup of patients develops aggressive joint disease. The proposed biphasic model of SJIA also implies a ‘window of opportunity’ to abrogate the development of chronic arthritis. We aimed to identify novel SJIA biomarkers during different disease phases.

Methods

Children with active SJIA were subgrouped clinically as systemic autoinflammatory disease with fever (SJIAsyst) or polyarticular disease (SJIApoly). A discovery cohort of n=10 patients per SJIA group, plus n=10 with infection, was subjected to unbiased label-free liquid chromatography mass spectrometry (LC-MS/MS) and immunoassay screens. In a separate verification cohort (SJIAsyst, n=45; SJIApoly, n=29; infection, n=32), candidate biomarkers were measured by multiple reaction monitoring MS (MRM-MS) and targeted immunoassays.

Results

Signatures differentiating the two phenotypes of SJIA could be identified. LC-MS/MS in the discovery cohort differentiated SJIAsyst from SJIApoly well, but less effectively from infection. Targeted MRM verified the discovery data and, combined with targeted immunoassays, correctly identified 91% (SJIAsyst vs SJIApoly) and 77% (SJIAsyst vs infection) of all cases.

Conclusions

Molecular signatures differentiating two phenotypes of SJIA were identified suggesting shifts in underlying immunological processes in this biphasic disease. Biomarker signatures separating SJIA in its initial autoinflammatory phase from the main differential diagnosis (ie, infection) could aid early-stage diagnostic decisions, while markers of a phenotype switch could inform treat-to-target strategies.

Impaired cellular energy metabolism in cord blood macrophages contributes to abortive response toward inflammatory threats

Neonatal sepsis is characterized by hyperinflammation causing enhanced morbidity and mortality compared to adults. This suggests differences in the response towards invading threats. Here we investigate activated cord blood macrophages (CBMΦ) in comparison to adult macrophages (PBMΦ), indicating incomplete interferon gamma (IFN-γ) and interleukin 10 (IL-10)-induced activation of CBMΦ. CBMΦ show reduced expression of phagocytosis receptors and cytokine expression in addition to altered energy metabolism. In particular, IFN-γ as well as IL-10-activated CBMΦ completely fail to increase glycolysis and furthermore show reduced activation of the mTOR pathway, which is important for survival in sepsis. MTOR inhibition by rapamycin equalizes cytokine production in CBMΦ and PBMΦ. Finally, incubation of PBMΦ with cord blood serum or S100A8/A9, which is highly expressed in neonates, suppresses mTOR activation, prevents glycolysis and the expression of an PBMΦ phenotype. Thus, a metabolic alteration is apparent in CBMΦ, which might be dependent on S100A8/A9 expression.

Neutrophil Heterogeneity as Therapeutic Opportunity in Immune-Mediated Disease

Neutrophils are versatile innate effector cells essential for immune defense but also responsible for pathologic inflammation. This dual role complicates therapeutic targeting. However, neither neutrophils themselves nor the mechanisms they employ in different forms of immune responses are homogeneous, offering possibilities for selective intervention. Here we review heterogeneity within the neutrophil population as well as in the pathways mediating neutrophil recruitment to inflamed tissues with a view to outlining opportunities for therapeutic manipulation in inflammatory disease.

Alarmins of the S100-Family in Juvenile Autoimmune and Auto-Inflammatory Diseases

Autoimmune and auto-inflammatory diseases in children are causing chronic inflammation, organ damage, and pain. Although several options for treatment are nowadays available a significant number of patients does not respond sufficiently to current therapies. In these diseases inflammatory processes are triggered by numerous exogenous and endogenous factors. There is now increasing evidence that especially a novel family of pro-inflammatory molecules, named alarmins, play a significant role in inflammatory processes underlying these diseases. Alarmins are endogenous proteins released during stress reactions that confer inflammatory signaling via Pattern Recognition Receptors (PRRs), like the Toll-like receptor 4 (TLR4). The most abundant alarmins in juvenile rheumatic diseases belong to the family of pro-inflammatory calcium-binding S100-proteins. In this review we will give a general introduction in S100-biology. We will demonstrate the functional relevance of these proteins in animal models of autoimmune and auto-inflammatory diseases. We will show the expression patterns of S100-alarmins and correlation to disease activity in different forms of juvenile idiopathic arthritis, auto-inflammatory diseases, and systemic autoimmune disorders. Finally, we will discuss the clinical use of S100-alarmins as biomarkers for diagnosis and monitoring of rheumatic diseases in children and will point out potential future therapeutic approaches targeting inflammatory effects mediated by S100-alarmins.

S100 Proteins in the Innate Immune Response to Pathogens

S100 proteins are distinct dimeric EF-hand Ca²⁺-binding proteins that can bind Zn²⁺, Mn²⁺, and other transition metals with high affinity at two sites in the dimer interface. Certain S100 proteins, including S100A7, S100A12, S100A8, and S100A9, play key roles in the innate immune response to pathogens. These proteins function via a "nutritional immunity" mechanism by depleting essential transition metals in the infection that are required for the invading organism to grow and thrive. They also act as damage-associated molecular pattern ligands, which activate pattern recognition receptors (e.g., Toll-like receptor 4, RAGE) that mediate inflammation. Here we present protocols for these S100 proteins for high-level production of recombinant protein, measurement of binding affinities using isothermal titration calorimetry, and an assay of antimicrobial activity.

The role of S100 proteins in the pathogenesis and monitoring of autoinflammatory diseases

S100A8/A9 and S100A12 are released from activated monocytes and granulocytes and act as proinflammatory endogenous toll-like receptor (TLR)4-ligands. S100 serum concentrations correlate with disease activity, both during local and systemic inflammatory processes. In some autoinflammatory diseases such as familial Mediterranean fever (FMF) or systemic juvenile idiopathic arthritis (SJIA), dysregulation of S100 release may be involved in the pathogenesis. Moreover, S100 serum levels are a valuable supportive tool in the diagnosis of SJIA in fever of unknown origin. Furthermore, S100 levels can be used to monitor disease activity to subclinical level, as their serum concentrations decrease with successful treatment.

Risk Factors and Biomarkers for the Occurrence of Uveitis in Juvenile Idiopathic Arthritis: Data From the Inception Cohort of Newly Diagnosed Patients With Juvenile Idiopathic Arthritis Study

Objective

To analyze the prognostic value of demographic, clinical, and therapeutic factors and laboratory biomarkers and to assess their role in predicting uveitis occurrence in patients with juvenile idiopathic arthritis (JIA).

Methods

Patients with JIA were enrolled within the first year after JIA diagnosis. Demographic and clinical parameters were documented. Serum samples were collected at study enrollment, at 3‐month follow‐up visits within the first year, and then every 6 months. A multivariable Cox regression analysis was performed to evaluate the impact of demographic, clinical, laboratory, and therapeutic parameters on uveitis onset.

Results

We included 954 JIA patients (67.2% female, 54.2% antinuclear antibody [ANA] positive, mean ± SD age at onset 7.1 ± 4.6 years). Uveitis occurred in 133 patients (observation period 44.5 months). Young age at JIA onset and ANA positivity were significantly associated with the onset of uveitis (both P < 0.001). Treatment of arthritis with methotrexate alone (hazard ratio [HR] 0.18 [95% confidence interval (95% CI) 0.12–0.29], P < 0.001) or combined with etanercept (HR 0.10 [95% CI 0.04–0.23], P < 0.001) or adalimumab (HR 0.09 [95% CI 0.01–0.61], P = 0.014) reduced the risk of uveitis onset and the occurrence of uveitis‐related complications. Predictors of uveitis onset included elevated erythrocyte sedimentation rate at baseline (HR 2.36 [95% CI 1.38–4.02], P = 0.002) and continuing moderate or high disease activity during follow‐up as measured by the 10‐joint clinical Juvenile Arthritis Disease Activity Score (HR 4.30 [95% CI 2.51–7.37], P < 0.001). Additionally, S100A12 levels ≥250 ng/ml at baseline were significantly associated with the risk of uveitis (HR 2.10 [95% CI 1.15–3.85], P = 0.016).

Conclusion

Apart from demographic risk factors and treatment modalities, JIA disease activity scores and laboratory biomarkers could be used to better define the group of JIA patients at high risk of uveitis onset.

Soluble CD163, a unique biomarker to evaluate the disease activity, exhibits macrophage activation in systemic juvenile idiopathic arthritis

This study aims to investigate the clinical significance of serum soluble CD163 (sCD163) levels as a predictor of the disease activity of systemic juvenile idiopathic arthritis (s-JIA). In this study, we examined 63 patients with s-JIA, four with Epstein-Barr virus-induced hemophagocytic lymphohistiocytosis (EBV-HLH), and seven with Kawasaki disease (KD), along with 14 healthy controls. We quantified serum cytokine levels (sCD163, neopterin, IL-18, IL-6) by enzyme-linked immunosorbent assay and compared the results with the clinical features of s-JIA. Serum sCD163 levels were significantly elevated in patients with s-JIA associated macrophage activation syndrome (MAS) and EBV-HLH compared to those in patients with acute-phase s-JIA and KD. In addition, serum sCD163 levels profoundly increased with the progress of MAS and correlated positively with the disease activity of s-JIA, even in patients receiving tocilizumab. Furthermore, serum sCD163 levels significantly decreased in the inactive phase compared to those in the active phase and normalized in remission. The correlation between macrophage activation and serum sCD163 levels might be a unique indicator of the disease activity and a potential diagnostic laboratory criterion for clinical remission in patients with s-JIA, including those receiving tocilizumab.