Correlation of Secretory Activity of Neutrophils With Genotype in Patients With Familial Mediterranean Fever

Epigenetic, transcriptional, and functional characterization of myeloid cells in familial Mediterranean fever

Familial Mediterranean fever (FMF) is a periodic fever syndrome caused by variation in MEFV. FMF is known for IL-1β dysregulation, but the innate immune landscape of this disease has not been comprehensively described. Therefore, we studied circulating inflammatory proteins, and the function of monocytes and (albeit less extensively) neutrophils in treated FMF patients in remission. We found that monocyte IL-1β and IL-6 production was enhanced upon stimulation, in concordance with alterations in the plasma inflammatory proteome. We did not observe changes in neutrophil functional assays. Subtle differences in chromatin accessibility and transcriptomics in our small patient cohort further argued for monocyte dysregulation. Together, these observations suggest that the MEFV-mutation-mediated primary immune dysregulation in monocytes leads to chronic inflammation that is subsequently associated with counterregulatory epigenetic/transcriptional changes reminiscent of tolerance. These data increase our understanding of the innate immune changes in FMF, aiding future management of chronic inflammation in these patients.

Experimental models in Familial Mediterranean Fever (FMF): Insights into pathophysiology and therapeutic strategies

Familial Mediterranean Fever (FMF) is a recurrent polyserositis characterized by self-limiting episodes or attacks of fever along with serosal inflammation. It mainly impacts people of the Mediterranean and Middle Eastern basin. FMF is a recessive autoinflammatory condition caused by mutation in the MEFV gene located on chromosome 16p13. MEFV mutations lead to the activation of the pyrin inflammasome resulting in an uncontrolled release of IL-1β. Various in vitro, in vivo and ex vivo experimental models have been developed to further comprehend the etiology and pathogenesis of FMF. These models have been proven to be clinically relevant to human FMF and can provide significant information about biological systems with respect to this condition. Additionally, these models have provided pertinent contributions to the development of potent therapeutic strategies against FMF. In this review, we describe the different experimental models utilized in FMF and we focus primarily on the most widely used models that have produced prominent insights into the pathophysiology of the disease.

Treat-to-target strategies for the management of familial Mediterranean Fever in children

BACKGROUND

The objective of this initiative was to develop a treat-to-target (T2T) approach for the management of patients with Familial Mediterranean Fever (FMF), including the definition of a complex treatment target, and establish strategies that improve patient care and long-term outcome.

METHODS

An initial set of statements as well as a flow chart visualising the proposed concept was developed. To adapt the preliminary statements to the current state of knowledge, a systematic literature search was performed and the modified statements were subject to a Delphi approach. To ensure the applicability of the statements in daily practice, an online survey was conducted among paediatric rheumatologists in Germany. In addition, data from the national AID-NET registry were analysed with respect to therapeutic response.

RESULTS

This T2T initiative yielded a total of 26 statements guiding FMF management with respect to diagnosis, treatment targets, treatment strategies and monitoring. The online survey identified cut-off values for inflammatory markers indicating treatment intensification and appropriate measures in case of colchicine intolerance or non-adherence. The analysis of data derived from the national AID-NET showed that colchicine therapy was successfully terminated in 61% of patients (27 out of 44) with heterozygous MEFV mutations. Multidimensional treatment targets incorporating objective and subjective reported outcome measures were developed. These provide the basis for stratifying patients into the following treatment paths: continue colchicine, persisting attacks / inflammation, colchicine intolerance, persisting arthritis, colchicine reduction and adjustment/reduction of biologics.

CONCLUSIONS

The proposed consensus treatment plan for the management of FMF incorporates multidimensional targets allowing transparent treatment decisions, which will promote personalised disease management and increase adherence to therapy.

Genotype-Phenotype Associations of Children With Familial Mediterranean Fever in a Cohort Consisting of M694V Mutation and Implications for Colchicine-Resistant Disease

OBJECTIVES

The aim of this study was to investigate the clinical associations of the second allele mutations and the effect of genotype and presenting features on colchicine resistance in children with familial Mediterranean fever (FMF), carrying at least one M694V variant.

METHODS

The medical records of the patients diagnosed with FMF, in whom at least one allele M694V mutation was detected, were reviewed. Patients were grouped according to the genotype as M694V homozygotes, compound heterozygote M694V with an exon 10 mutation, compound heterozygote M694V with a variant of unknown significance (VUS), and M694V heterozygotes. Disease severity was assessed with the International Severity Scoring System for FMF.

RESULTS

Among the 141 patients included, homozygote M694V (43.3%) was the most frequent MEFV genotype. Clinical manifestations of FMF at diagnosis were not significantly different according to genotypic alterations except homozygote M694V. Besides, homozygous M694V was associated with a more severe disease, with more frequent comorbidities and colchicine-resistant disease. A lower disease severity score was observed in compound heterozygotes with VUS than in M694V heterozygotes (median 1 vs 2, p = 0.006). Regression analysis revealed that homozygous M694V, arthritis, and frequency of attacks were associated with an increased risk of colchicine-resistant disease.

CONCLUSIONS

Clinical manifestations of FMF at diagnosis with a M694V allele were predominantly influenced by the M694V rather than the second allele mutations. Although homozygous M694V was associated with the most severe form, the presence of compound heterozygosity with a VUS did not affect disease severity or clinical features. Homozygous M694V confers the highest risk of colchicine-resistant disease.

The role of S100A12 and Toll-like receptor 4 in assessment of disease activity in familial Mediterranean fever and juvenile idiopathic arthritis

OBJECTIVE

Our aim was to investigate the possible relationship between the serum S100A12 and Toll-like receptor 4 (TLR4) levels, and the activity of familial Mediterranean fever (FMF) and juvenile idiopathic arthritis (JIA) in accordance with the routine biochemical parameters. Furthermore, the effectiveness of these 2 biomarkers in distinguishing FMF from JIA has been evaluated.

METHOD

Sixty-nine children with FMF, 68 children with JIA, and 35 healthy children were included in this study. S100A12 and TLR4 levels were measured by the sandwich enzyme-linked immunosorbent assay technique.

RESULTS

In the FMF patient group, serum S100A12 level was found to be significantly higher than in both the JIA and control groups (P = .000 and P = .000, respectively). Although S100A12 levels were higher in the attack period compared to the attack-free period, this increase was not statistically significant (P > .05). TLR4 levels were statistically significantly higher in the attack period compared to the attack-free period in children with FMF (P < .05). Although there was no relationship between S100A12 levels and disease activity, there is a clear correlation between S100A12 and the Auto-Inflammatory Disease Activity Index in attack-free FMF patients (r = 0.612 P = .000).

CONCLUSION

Serum S100A12 levels were not found to be a potentially valuable biomarker for assessing disease activity in either FMF or JIA. However, TLR4 levels were found to be a valuable biomarker for assessing disease activity in children with FMF. Further research which includes serial monitoring of S100A12 and TLR4 levels in a large cohort will provide detailed information about accuracy of these 2 potential biomarkers in both patients group.

Haemophagocytic lymphohistiocytosis in a patient with familial Mediterranean fever and miliary tuberculosis: a case report

Haemophagocytic lymphohistiocytosis (HLH) is a lethal complication of several infections, especially viral origin. Mycobacterium tuberculosis infection can also lead to HLH, yet it is an uncommon trigger. Considering the role of increased cytokines in HLH, autoinflammatory conditions, such as familial Mediterranean fever (FMF), might contribute to its development. Nevertheless, the possible relationship between FMF and HLH has been suggested only in some case reports. We present a case of FMF who admitted to the hospital with consitutional symptoms and chest pain regarding to recurrent pericarditis. On a blood test, pancytopenia and elevated acute phase reactants were seen. Fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography demonstrated positive FDG uptake sites on both the right and left surrenal glands, the visceral layer of pericard, and reactive lymphadenomegalies at multiple mediastinal regions. Bone marrow biopsy revealed haemophagocytosis. Methylprednisolone treatment was initiated. Despite immunosuppressive treatment, clinical and biochemical parameters deteriorated; thus, a thorax computed tomography was executed. Findings were consistent with miliary tuberculosis infection. M. tuberculosis was detected in blood culture and bronchoalveolar lavage culture material. Also, bone marrow and surrenal biopsy material revealed necrotising caseating granuloma.

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.

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.

Evaluation of S100A12 protein levels in children with familial Mediterranean fever

Background/aim

Familial Mediterranean fever (FMF), the most common autoinflammatory disease in children, is characterized by recurrent febrile episodes. FMF is known to progress with chronic inflammation, particularly during attack periods. This study aimed to investigate the relationship of S100A12, an inflammatory marker, with attacks and inflammatory events in FMF patients.

Materials and methods

The study included 57 patients diagnosed with FMF, 43 in an attack-free period and 14 in an attack period, and 31 healthy children as the control group. Only white blood cell (WBC) count, C-reactive protein (CRP) level, erythrocyte sedimentation rate (ESR), and S100A12 level were analyzed in the control group. In addition, serum amyloid A (SAA), and fibrinogen levels were measured, and a mutation analysis was performed in the patient group. The results were compared among the attack-free period, acute attack FMF and control groups.

Results

The mean age of patients and control group was 10 (2.5–18) and 9.5 (2.5–16) years, respectively. The CRP (p = 0.001), S100A12 (p = 0.003) and ESR (p= 0.001) values differed significantly between the FMF and control groups. S100A12 level (p = 0.027), WBC count (p = 0.003), CRP level (p = 0.0001), ESR (p = 0.004), and fibrinogen level (p = 0.001) differed significantly between the acute attack and attack-free period groups. SAA level (p = 0.05), ESR (p = 0.001), fibrinogen level (p = 0.001), WBC count (p = 0.001), and S100A12 level (p = 0.027) were higher in M694V homozygous FMF patients than in other FMF patients.

Conclusion

Patients with FMF had higher S100A12 levels than the control group, while the mean S100A12 concentration was higher in acute attack period patients than in attack-free period patients. S100A12 level might be an important indicator in the monitoring of chronic inflammation in patients with FMF.

Clinical Implications of S100A12 and Resolvin D1 Serum Levels, and Related Genes in Children with Familial Mediterranean Fever

The aim of this article was to study the role of S100A12 and resolvin D1-related genes and serum levels in the diagnosis and detection of subclinical inflammation in children with familial Mediterranean fever (FMF) during the quiescent stage of the disease. Seventy-eight children with FMF during the silent state and 60 healthy control were studied. Serum S100A12 and resolvin D1 were quantitatively measured using enzyme-linked immunosorbent assay. In addition, the levels of C-reactive protein, erythrocyte sedimentation rate, and hemoglobin were determined. The clinical severity was evaluated. The link between the Mediterranean fever (MEFV) gene and the genes related to the two studied biomarkers was also assessed. Correlation between S100A12 and resolvin D1 and the clinical severity was assessed. The mean serum levels of S100A12 and resolvin D1 were 847.4 and 793.3, respectively, which were highly significantly increased (p = 0.001) compared with the controls (324.3 and 235.1, respectively). The receiver operating characteristic curve test showed that S100A12 had a sensitivity of 97.4% and specificity of 80% with cutoff value of 529.5, while resolvin D1 showed a sensitivity of 100% and specificity of 50% with cutoff value of 231.2. A correlation was detected between the clinical severity and S100A12 and resolvin D1. This study delineated that S100A12 and resolvin D1 are sensitive biomarkers to detect the degree of inflammation in children with FMF during the silent period. Consequently, we recommend adjusting the colchicine dose to ameliorate the disease's symptoms and to improve the quality of life in these patients.

Experiences with IL-1 blockade in systemic juvenile idiopathic arthritis - data from the German AID-registry

BACKGROUND

Systemic juvenile idiopathic arthritis (sJIA) is a complex disease with dysregulation of the innate immune system driven by cytokines. A major role is ascribed to interleukin-1β (IL-1β), supporting the autoinflammatory character of the disease and offering an effective blocking mechanism for treatment. Here we present clinical practice data from the German AID-registry for patients treated with IL-1 inhibition (IL-1i).

METHODS

In 2009 a clinical and research consortium (AID-Net) was established, including an online AID-registry. Patients with documented sJIA diagnosis were identified. Data for this retrospective IL-1i study were recorded by 17 centers. Response to treatment was evaluated according to Wallace criteria and additionally by an own classifying clinical response system.

RESULTS

In 6 years, 202 patients with confirmed sJIA were recorded in the AID-registry. Out of these, 111 children received therapy with Anakinra (ANA) (n = 84, 39 f) and/or Canakinumab (CANA) (n = 27, 15 f) at a median age of 8.7 y (range 0.6-19.1). During the first 12 months 75/111 (ANA 55, CANA 20) patients were evaluated according to Wallace criteria (achievement of inactive disease 28/55 and 17/20, remission over 6 months under medication 13/55 and 7/20 cases). Over the whole period of time, clinical response was preserved in the majority of patients (ANA 54/80, CANA 20/27). Arthritis mostly persisted in polyarticular (PA) courses. During treatment with IL-1i concomitant medication could be tapered in about 15%. IL-1i was discontinued in 59/111 patients. 45 (15) adverse events (AE)s in ANA (CANA) treated patients (19.7 (26.6) AE/100 ANA (CANA) exposure years, 95%CI: 14.4-26.4 (14.9-43.9)) were reported.

CONCLUSION

In a large cohort of sJIA patients from Germany, we can confirm an overall favorable clinical response to both available IL-1 blocking agents. IL-1i was well tolerated with acceptable safety and effectiveness in a real-life clinical setting.

Familial Mediterranean fever, from pathogenesis to treatment: a contemporary review

Familial Mediterranean fever (FMF) (OMIM #249100) is the most common hereditary autoinflammatory disease in the world. FMF is caused by gain of function mutations of MEFV gene which encodes an immune regulatory protein, pyrin. Over the last few years, we have witnessed several new developments in the pathogenesis, genetic testing, diagnosis, comorbidities, disease related damage and treatment approaches to FMF. Elucidation of some of the pathogenic mechanisms has led to the discovery of pathways involved in inflammatory, metabolic, cardiovascular and degenerative diseases. The use of next generation sequencing in FMF has revealed many new gene variants whose clinical significance may be clarified by developing functional assays and biomarkers. Clinically, although FMF is considered an episodic disease characterized by brief attacks, recent systematic studies have defined several associated chronic inflammatory conditions. Colchicine is the mainstay of FMF treatment, and interleukin (IL)-1 antagonists are the treatment of choice in refractory or intolerant cases. Experience of IL-1 antagonists, anakinra and canakinumab, is now available in thousands of colchicine resistant or intolerant FMF patients. In this contemporary review, we surveyed current FMF knowledge in the light of these recent advances.

Gene-Dose Effect of MEFV Gain-of-Function Mutations Determines ex vivo Neutrophil Activation in Familial Mediterranean Fever

Familial Mediterranean fever (FMF) is caused by mutations within the Mediterranean fever (MEFV) gene. Disease severity depends on genotype and gene dose with most serious clinical courses observed in patients with M694V homozygosity. Neutrophils are thought to play an important role in the initiation and perpetuation of inflammatory processes in FMF, but little is known about the specific characteristics of these cells in FMF patients. To further characterize neutrophilic inflammatory responses in FMF and to delineate gene–dose effects on a cellular level, we analyzed cytokine production and activation levels of isolated neutrophils derived from patients and subjects with distinct MEFV genotypes, as well as healthy and disease controls. Serum levels of interleukin-18 (IL-18) (median 11,485 pg/ml), S100A12 (median 9,726 ng/ml), and caspase-1 (median 394 pg/ml) were significantly increased in patients with homozygous M694V mutations. Spontaneous release of S100A12, caspase-1, proteinase 3, and myeloperoxidase (MPO) was restricted to ex vivo cultured neutrophils derived from patients with two pathogenic MEFV mutations. IL-18 secretion was highest in patients with two mutations but also increased in neutrophils from healthy heterozygous MEFV mutation carriers, exhibiting an ex vivo gene–dose effect, which was formerly described by us in patients' serum. CD62L (l-selectin) was spontaneously shed from the surface of ex vivo cultured neutrophils [median of geometric mean fluorescence intensity (gMFI) after 5 h: 28.8% of the initial level]. While neutrophils derived from healthy heterozygous mutation carriers again showed a gene–dose effect (median gMFI: 67.1%), healthy and disease controls had significant lower shedding rates (median gMFI: 83.6 and 82.9%, respectively). Co-culture with colchicine and/or stimulation with adenosine triphosphate (ATP) and lipopolysaccharide (LPS) led to a significant increase in receptor shedding. Neutrophils were not prevented from spontaneous shedding by blocking IL-1 or the NLRP3 inflammasome. In summary, the data demonstrate that ex vivo cultured neutrophils derived from FMF patients display a unique phenotype with spontaneous release of high amounts of IL-18, S100A12, MPO, caspase-1, and proteinase 3 and spontaneous activation as demonstrated by the loss of CD62L. Neutrophilic activation seems to be independent from IL-1 activation and displays a gene–dose effect that may be responsible for genotype-dependent phenotypes.

Cord Blood Low-Density Granulocytes Correspond to an Immature Granulocytic Subset with Low Expression of S100A12

Although substantial progress has been achieved concerning neonatal sepsis, its lethality remains considerably high, and further insights into peculiarities and malfunctions of neonatal immunity are needed. This study aims to contribute to a better understanding of the role of human neonatal granulocyte subpopulations and calgranulin C (S100A12). For this purpose, we gathered 136 human cord blood (CB) samples. CD66b⁺ CB low-density granulocytes (LDG) and CB normal-density granulocytes were isolated and functionally and phenotypically compared with healthy adult control granulocytes. We could identify CB-LDG as CD66b^bright CD64^high CD16^low CD35^low CD10^low S100A12^med-low and, based on these markers, recovered in whole CB stainings. Consistent with flow cytometric findings, microscopic imaging supported an immature phenotype of CB-LDG with decreased S100A12 expression. In CB serum of healthy neonates, S100A12 was found to be higher in female newborns when compared with males. Additionally, S100A12 levels correlated positively with gestational age independently from sex. We could solidify functional deficits of CB-LDG concerning phagocytosis and generation of neutrophil extracellular traps. Our study reveals that previously described suppressive effects of CB-LDG on CD4⁺ T cell proliferation are exclusively due to phagocytosis of stimulation beads used in cocultures and absent when using soluble or coated Abs. In conclusion, we characterize CB-LDG as immature neutrophils with functional deficits and decreased expression and storage of S100A12. Concerning their cross-talk with the adaptive immunity, we found no direct inhibitory effect of LDG. Neonatal LDG may thus represent a distinct population that differs from LDG populations found in adults.

Synergistic Signaling of TLR and IFNα/β Facilitates Escape of IL-18 Expression from Endotoxin Tolerance

Rationale: IL-18 is a member of the IL-1 cytokine family, and elevated blood IL-18 concentrations associate with disease activity in macrophage activation syndrome (MAS) and poor clinical outcomes in severe inflammatory and septic conditions.

Objectives: Although recent investigations provide mechanistic evidence for a contribution of IL-18 to inflammation and hyperinflammation in sepsis and MAS, we sought to study regulatory mechanisms underlying human IL-18 expression.

Methods: Samples from in vivo and in vitro endotoxin rechallenge experiments, patients with inflammatory disease, and isolated human monocytes treated with various stimulants and drugs were tested for cytokine gene and protein expression. Serum IL-18 expression with or without JAK/STAT inhibition was analyzed in two MAS mouse models and in a patient with recurrent MAS.

Measurements and Main Results: Peripheral blood and monocytic IL-18 expression escaped LPS-induced immunoparalysis. LPS-stimulated primary human monocytes revealed specific IL-18 expression kinetics controlled by IFNα/β signaling. JAK/STAT inhibition or IFNβ neutralization during LPS stimulation blunted cytokine expression. Similarly, microtubule-destabilizing drugs abrogated LPS-induced IL18 expression, but this effect could be fully reversed by addition of IFNα/β. Ex vivo analysis of inflammatory disease patients’ whole blood revealed strong correlation of type I IFN score and IL18 expression, whereas JAK/STAT inhibition strongly reduced IL-18 serum levels in two MAS mouse models and in a patient with recurrent MAS.

Conclusions: Our data indicate that IL-18 (but not IL-1β) production from human monocytes requires cooperative Toll-like receptor and IFNα/β signaling. Interference with IFNα/β expression or signaling following JAK/STAT inhibition may control catastrophic hyperinflammation in MAS.

Systemic autoinflammatory diseases

Systemic autoinflammatory diseases (SAIDs) are a growing group of disorders caused by a dysregulation of the innate immune system leading to episodes of systemic inflammation. In 1997, MEFV was the first gene identified as disease causing for Familial Mediterranean Fever, the most common hereditary SAID. In most cases, autoinflammatory diseases have a strong genetic background with mutations in single genes. Since 1997 more than 30 new genes associated with autoinflammatory diseases have been identified, affecting different parts of the innate immune system. Nevertheless, for at least 40-60% of patients with phenotypes typical for SAIDs, a distinct diagnosis cannot be met, leading to undefined SAIDs (uSAIDs). However, SAIDs can also be of polygenic or multifactorial origin, with environmental influence modulating the phenotype. The implementation of a disease continuum model combining the adaptive and the innate immune system with autoinflammatory and autoimmune diseases shows the complexity of SAIDs and the importance of new methods to elucidate molecular changes and causative factors in SAIDs. Diagnosis is often based on clinical presentation and genetic testing. The timeline from onset to diagnosis takes up to 7.3 years, highlighting the indisputable need to identify new treatment and diagnostic targets. Recently, other factors are under investigation as additional contributors to the pathogenesis of SAIDs. This review gives an overview of pathogenesis and etiology of SAIDs, and summarizes recent diagnosis and treatment options.

[Evidence-based treatment recommendations for familial Mediterranean fever : A joint statement by the Society for Pediatric and Adolescent Rheumatology and the German Society for Rheumatology]

BACKGROUND

Familial Mediterranean fever (FMF) in Germany is a rare, genetically linked disease of childhood and adolescence, which is characterized by recurrent febrile episodes and clinical signs of peritonitis, pleuritis and arthritis. Treatment with colchicine is effective and well-tolerated in the majority of patients; however, some patients do not sufficiently respond to this treatment or are intolerant to colchicine. For these patients first-line treatment with biologics which block interleukin-1 can be used.

OBJECTIVE

The aim was to formulate evidence-based treatment recommendations for patients with an insufficient response and intolerance to colchicine treatment.

METHODS

Based on a literature search and the European League Against Rheumatism (EULAR) recommendations on FMF from 2016 the appointed members of the Society for Pediatric and Adolescent Rheumatology (GKJR) and the German Society for Rheumatology (DGRh) convened to work out and form a consensus in a joint statement on evidence-based treatment recommendations on FMF.

RESULTS

After intensive discussions all decisions were in concordance. A total of 5 superordinate principles and 10 recommendations were agreed upon.

DISCUSSION

The joint activities of the GKJR and the DGRh were successfully concluded in a timely manner. The recommendations form a good basis for optimal treatment of all age groups of patients with FMF.

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.

Neutrophils From Children With Systemic Juvenile Idiopathic Arthritis Exhibit Persistent Proinflammatory Activation Despite Long-Standing Clinically Inactive Disease

Background: Systemic juvenile idiopathic arthritis (SJIA) is a chronic childhood arthropathy with features of autoinflammation. Early inflammatory SJIA is associated with expansion and activation of neutrophils with a sepsis-like phenotype, but neutrophil phenotypes present in longstanding and clinically inactive disease (CID) are unknown. The objective of this study was to examine activated neutrophil subsets, S100 alarmin release, and gene expression signatures in children with a spectrum of SJIA disease activity.

Methods: Highly-purified neutrophils were isolated using a two-step procedure of density-gradient centrifugation followed by magnetic-bead based negative selection prior to flow cytometry or cell culture to quantify S100 protein release. Whole transcriptome gene expression profiles were compared in neutrophils from children with both active SJIA and CID.

Results: Patients with SJIA and active systemic features demonstrated a higher proportion of CD16⁺CD62L^lo neutrophil population compared to controls. This neutrophil subset was not seen in patients with CID or patients with active arthritis not exhibiting systemic features. Using imaging flow cytometry, CD16⁺CD62L^lo neutrophils from patients with active SJIA and features of macrophage activation syndrome (MAS) had increased nuclear hypersegmentation compared to CD16⁺CD62L⁺ neutrophils. Serum levels of S100A8/A9 and S100A12 were strongly correlated with peripheral blood neutrophil counts. Neutrophils from active SJIA patients did not show enhanced resting S100 protein release; however, regardless of disease activity, neutrophils from SJIA patients did show enhanced S100A8/A9 release upon PMA stimulation compared to control neutrophils. Furthermore, whole transcriptome analysis of highly purified neutrophils from children with active SJIA identified 214 differentially expressed genes (DEG) compared to neutrophils from healthy controls. The most significantly upregulated gene pathway was Immune System Process, including AIM2, IL18RAP, and NLRC4. Interestingly, this gene set showed intermediate levels of expression in neutrophils from patients with long-standing CID yet persistent serum IL-18 elevation. Indeed, all patient samples regardless of disease activity demonstrated elevated inflammatory gene expression, including inflammasome components and S100A8.

Conclusion: We identify features of neutrophil activation in SJIA patients with both active disease and CID, including a proinflammatory gene expression signature, reflecting persistent innate immune activation. Taken together, these studies expand understanding of neutrophil function in chronic autoinflammatory disorders such as SJIA.

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.

Calgranulin C (S100A12) Is Differentially Expressed in Subtypes of Chronic Rhinosinusitis

Background Calgranulin C (S100A12) is an innate immune peptide at the air-mucosal interface associated with neutrophil involvement, which when overexpressed has been implicated as a biomarker of inflammatory diseases. Decreased epithelial expression of certain innate immune peptides has been reported in chronic rhinosinusitis (CRS). We hypothesized that S100A12 is differentially expressed in the sinonasal mucosa of patients with CRS compared to controls and that S100A12 is a potential biomarker of CRS-specific quality of life (QOL) and disease severity. Methods A prospective observational study was conducted which included 70 patients: 17 controls, 28 having CRS without (CRSsNP), and 25 with (CRSwNP) nasal polyps. The expression of S100A12 and human neutrophil elastase (HNE) was assessed in the anterior ethmoid tissues from all patients using enzyme-linked immunosorbent assay (ELISA) and immunohistochemical (IHC) analyses. Disease-specific QOL (Rhinosinusitis Disability Index) and disease severity (computed tomography [CT] and endoscopy) were evaluated and correlated to the expression levels of S100A12. Results S100A12 and HNE were significantly elevated in patients with CRSsNP compared to normal controls ( P < .05 and P < .001, respectively) and patients with CRSwNP ( P < .05 and P < .001, respectively), as measured by ELISA and IHC analyses. Patients with CRS exhibited worse CRS-specific disease severity compared to normal controls ( P < .05), and the increased protein levels of S100A12 were significantly correlated to disease severity, represented by CT scores ( P < .05). Conclusions S100A12 is differentially expressed in CRS subtypes and is significantly elevated in patients with CRSsNP and associated with CRS-specific disease severity.

Proinflammatory Cytokine Environments Can Drive Interleukin-17 Overexpression by γ/δ T Cells in Systemic Juvenile Idiopathic Arthritis

OBJECTIVE

Systemic-onset juvenile idiopathic arthritis (JIA) is speculated to follow a biphasic course, with an initial systemic disease phase driven by innate immune mechanisms and interleukin-1β (IL-1β) as a key cytokine and a second chronic arthritic phase that may be dominated by adaptive immunity and cytokines such as IL-17A. Although a recent mouse model points to a critical role of IL-17-expressing γ/δ T cells in disease pathology, in humans, both the prevalence of IL-17 and the role of IL-17-producing cells are still unclear.

METHODS

Serum samples from systemic JIA patients and healthy pediatric controls were analyzed for the levels of IL-17A and related cytokines. Whole blood samples were studied for cellular expression of IL-17 and interferon-γ (IFNγ). CD4+ and γ/δ T cells isolated from the patients and controls were assayed for cytokine secretion in different culture systems.

RESULTS

IL-17A was prevalent in sera from patients with active systemic JIA, while both ex vivo and in vitro experiments revealed that γ/δ T cells overexpressed this cytokine. This was not seen with CD4+ T cells, which expressed strikingly low levels of IFNγ. Therapeutic IL-1 blockade was associated with partial normalization of both cytokine expression phenotypes. Furthermore, culturing healthy donor γ/δ T cells in serum from systemic JIA patients or in medium spiked with IL-1β, IL-18, and S100A12 induced IL-17 overexpression at levels similar to those observed in the patients' cells.

CONCLUSION

A systemic JIA cytokine environment may prime γ/δ T cells in particular for IL-17A overexpression. Thus, our observations in systemic JIA patients strongly support a pathophysiologic role of these cells, as proposed by the recent murine model.

Familial Mediterranean Fever: Recent Developments in Pathogenesis and New Recommendations for Management

Familial Mediterranean fever (FMF) is the most common monogenic autoinflammatory disease (AID) affecting mainly the ethnic groups originating from Mediterranean basin. The disease is characterized by self-limited inflammatory attacks of fever and polyserositis along with elevated acute phase reactants. FMF is inherited autosomal recessively; however, a significant proportion of heterozygotes also express the phenotype. FMF is caused by mutations in the MEFV gene coding for pyrin, which is a component of inflammasome functioning in inflammatory response and production of interleukin-1β (IL-1β). Recent studies have shown that pyrin recognizes bacterial modifications in Rho GTPases, which results in inflammasome activation and increase in IL-1β. Pyrin does not directly recognize Rho modification but probably affected by Rho effector kinase, which is a downstream event in the actin cytoskeleton pathway. Recently, an international group of experts has published the recommendations for the management of FMF. Colchicine is the mainstay of FMF treatment, and its regular use prevents attacks and controls subclinical inflammation in the majority of patients. Furthermore, it decreases the long-term risk of amyloidosis. However, a minority of FMF patients fail to response or tolerate colchicine treatment. Anti-interleukin-1 drugs could be considered in these patients. One should keep in mind the possibility of non-compliance in colchicine-non-responders. Although FMF is a relatively well-described AID and almost 20 years has passed since the discovery of the MEFV gene, there are still a number of unsolved problems about it such as the exact mechanism of the disease, symptomatic heterozygotes and their treatment, and the optimal management of colchicine resistance.