First report of macrophage activation syndrome in hyperimmunoglobulinemia D with periodic fever syndrome

Hemophagocytic lymphohistiocytosis and macrophage activation syndrome: two rare sides of the same devastating coin

Hemophagocytic lymphohistiocytosis (HLH) is a rare genetic hyperinflammatory syndrome that occurs early in life. Macrophage activation syndrome (MAS) usually refers to a secondary form of HLH associated with autoimmunity, although there are other causes of secondary HLH, such as infections and malignancy. In this article, we reviewed the concepts, epidemiology, clinical and laboratory features, diagnosis, differential diagnosis, prognosis, and treatment of HLH and MAS. We also reviewed the presence of MAS in the most common autoimmune diseases that affect children. Both are severe diseases that require prompt diagnosis and treatment to avoid morbidity and mortality.

Recurrent macrophage activation syndrome due to hyperimmunoglobulin D syndrome: a case-based review

Hyperimmunoglobulin D syndrome (HIDS) is a hereditary autoinflammatory disease characterized by recurrent inflammatory attacks with fever, abdominal pain, lymphadenopathy, aphthous stomatitis, and skin lesions. There are few reports on HIDS patients complicated with macrophage activation syndrome (MAS); however, to our knowledge, there is no case of HIDS with recurrent MAS attacks. We report two pediatric patients initially diagnosed as Kawasaki disease and systemic juvenile idiopathic arthritis presented with recurrent MAS episodes with prolonged fever, skin rash, hepatosplenomegaly, cervical lymphadenopathy, aphthous stomatitis, headache, pancytopenia, hyperferritinemia, and hypofibrinogenemia, finally diagnosed as HIDS with a documented homozygous MVK gene mutation. This is the first report on recurrent MAS attacks due to HIDS in pediatric patients who were successful treated with corticosteroids and anti-IL-1 therapies. Thus, clinicians should be vigilantly investigated signs of autoinflammatory diseases in patients with recurrent MAS attacks during their disease course, and HIDS should be considered an underlying disease for triggering recurrent MAS attacks. We have also reviewed the current literature regarding HIDS cases complicated with a MAS attack and summarized their demographic, treatment, and outcome characteristics. Key points • Hyperimmunoglobulin D syndrome should be considered in differential diagnosis in patients who experienced recurrent macrophage activation syndrome attacks.

The Clinical Chameleon of Autoinflammatory Diseases in Children

The very first line of defense in humans is innate immunity, serving as a critical strongpoint in the regulation of inflammation. Abnormalities of the innate immunity machinery make up a motley group of rare diseases, named ‘autoinflammatory’, which are caused by mutations in genes involved in different immune pathways. Self-limited inflammatory bouts involving skin, serosal membranes, joints, gut and other districts of the human body burst and recur with variable periodicity in most autoinflammatory diseases (ADs), often leading to secondary amyloidosis as a long-term complication. Dysregulated inflammasome activity, overproduction of interleukin (IL)-1 or other IL-1-related cytokines and delayed shutdown of inflammation are pivotal keys in the majority of ADs. The recent progress of cellular biology has clarified many molecular mechanisms behind monogenic ADs, such as familial Mediterranean fever, tumor necrosis factor receptor-associated periodic syndrome (or ‘autosomal dominant familial periodic fever’), cryopyrin-associated periodic syndrome, mevalonate kinase deficiency, hereditary pyogenic diseases, idiopathic granulomatous diseases and defects of the ubiquitin-proteasome pathway. A long-lasting history of recurrent fevers should require the ruling out of chronic infections and malignancies before considering ADs in children. Little is known about the potential origin of polygenic ADs, in which sterile cytokine-mediated inflammation results from the activation of the innate immunity network, without familial recurrency, such as periodic fever/aphthous stomatitis/pharyngitis/cervical adenopathy (PFAPA) syndrome. The puzzle of febrile attacks recurring over time with chameleonic multi-inflammatory symptoms in children demands the inspection of the mixture of clinical data, inflammation parameters in the different disease phases, assessment of therapeutic efficacy of a handful of drugs such as corticosteroids, colchicine or IL-1 antagonists, and genotype analysis to exclude or confirm a monogenic origin.

Case Report: Hemophagocytic Lymphocytosis in a Patient With Glutaric Aciduria Type IIC

Hemophagocytic lymphocytosis (HLH) is a rare disease caused by inborn errors of immunity (IEI), secondary to infection, lymphoma or autoimmune disorders, but we often overlook the fact that HLH can be secondary to inborn errors of metabolism (IEM). Here, we describe a patient who was diagnosed with glutaric aciduria type IIC complicated by features suggestive of possible HLH. The diagnosis of glutaric aciduria type IIC, a IEM, was confirmed by whole exome sequencing. The patient was treated with coenzyme Q10 and riboflavin which effectively improved her liver function. During treatment, the patient developed severe anemia and thrombocytopenia. Persistent fever, splenomegaly, cytopenias, increased ferritin, hypertriglyceridemia, hypofibrinogenemia, and hemophagocytosis in the bone marrow pointed to the diagnosis of HLH; however, the patient eventually died of gastrointestinal bleeding. After other potential causes were ruled out, the patient was diagnosed with glutaric aciduria type IIC complicated by features suggestive of possible HLH. When cytopenias occurs in IEM patients, HLH is a possible complication that cannot be ignored. This case suggests a possible relationship between IEM and risk for immune dysregulation.

Real-Life Indications of Interleukin-1 Blocking Agents in Hereditary Recurrent Fevers: Data From the JIRcohort and a Literature Review

Background

Interleukin (IL)-1 inhibitors represent the main treatment in patients with colchicine-resistant/intolerant familial Mediterranean fever (crFMF), mevalonate kinase deficiency (MKD), and tumor necrosis factor receptor-associated periodic syndrome (TRAPS). However, the reasons for the use of IL-1 inhibitors in these diseases are still not completely clarified.

Objective

Identify real-life situations that led to initiating anakinra or canakinumab treatment in hereditary recurrent fevers (HRFs), combining data from an international registry and an up-to-date literature review.

Patients and Methods

Data were extracted from the JIRcohort, in which clinical information (demographic data, treatment, disease activity, and quality of life) on patients with FMF, MKD, and TRAPS was retrospectively collected. A literature search was conducted using Medline, EMBASE, and Cochrane databases.

Results

Complete data of 93 patients with HRF (53.8% FMF, 31.2% MKD, and 15.1% TRAPS) were analyzed. Data from both the registry and the literature review confirmed that the main reasons for use of IL-1 blockers were the following: failure of previous treatment (n = 57, 61.3% and n = 964, 75.3%, respectively), persistence of disease activity with frequent attacks (n = 44, 47.3% and n = 1,023, 79.9%) and/or uncontrolled inflammatory syndrome (n = 46, 49.5% and n = 398, 31.1%), severe disease complication or associated comorbidities (n = 38, 40.9% and n = 390, 30.4%), and worsening of patients' quality of life (n = 36, 38.7% and n = 100, 7,8%). No reasons were specified for 12 (16.4%) JIRcohort patients and 154 (12%) patients in the literature.

Conclusion

In the absence of standardized indications for IL-1 inhibitors in crFMF, MKD, and TRAPS, these results could serve as a basis for developing a treat-to-target strategy that would help clinicians codify the therapeutic escalation with IL-1 inhibitors.

The everchanging framework of autoinflammation

The innate immunity works as a defence bullwark that safeguards healthy tissues with the power of detecting infectious agents in the human body: errors in the context of innate immunity identify autoinflammatory disorders (AIDs), which arise as bouts of aberrant inflammation with little or no involvement of T and B cells and neither recognized infections, nor associated autoimmune phenomena. Hereditary AIDs tend to have a pediatric-onset heralded by stereotyped inflammatory symptoms and fever, while AIDs without an ascertained cause, such as systemic juvenile idiopathic arthritis, derive from the interaction of genetic factors with environmental noxae and are unevenly defined. A dysregulated inflammasome activation promotes the best-known family of AIDs, as well as several degenerative and metabolic disorders, but also nuclear factor κB- and interferon-mediated conditions have been framed as AIDs: the zenith of inflammatory flares marks different phenotypes, but diagnosis may go unnoticed until adulthood due to downplayed symptoms and complex kaleidoscopic presentations. This review summarizes the main AIDs encountered in childhood with special emphasis on the clinical stigmata that may help establish a correct framework and blueprints to empower young scientists in the recognition of AIDs. The description focuses inflammasomopathies as paradigms of interleukinopathies, nuclear factor-κB -related disorders and interferonopathies. The challenges in the management of AIDs during childhood have been recently boosted by numerous therapeutic options derived from genomically-based approaches, which have led to identify targeted biologic agents as rationalized treatments and achieve more tangible perspectives of disease control.

Overview of the rarest causes of fever in newborns: handy hints for the neonatologist

Neonatal causes of fever are a major source of concern for clinicians. If fever is combined with organ-specific sterile inflammatory manifestations the suspicion of autoinflammatory disorders should be considered, and the list of such conditions starting in the neonatal period includes chronic infantile neurological cutaneous articular syndrome, mevalonate kinase deficiency, deficiency of the interleukin-1 receptor antagonist, otulipenia, STING-associated vasculopathy with onset in infancy and Blau syndrome. Other causes of noninfectious fever that can rarely occur in newborns are Kawasaki disease, Behçet's disease, and hemophagocytic lymphohistiocytosis. Diagnosis of these exceptionally rare disorders is challenging for neonatologists. An early recognition of these complex diseases might lead to use more specific or rational drugs preventing permanent consequences. This review focuses on the rarest causes of fever occurring in the neonatal age with the aim of portraying many protean clinical pictures associated with fever and reviewing the potential available treatments.

COVID-19 in Autoinflammatory Diseases with Immunosuppressive Treatment

COVID-19 disease increases interleukin (IL)-1β release. Anti-IL-1-treatment is effective in IL-1-mediated autoinflammatory diseases (AID). This case series presents COVID-19 in patients with IL-1-mediated and unclassified AID with immunosuppressive therapy (IT). Patient 1 is a 34-year-old woman with an unclassified AID and methotrexate. Patients 2 and 3 (14-year-old girl and 12-year-old boy, respectively) have a Cryopyrin-Associated Periodic Syndrome (NLRP3 p.Q703K heterozygous, CAPS) treated with canakinumab 150 mg/month since three and five years, respectively. Patient 4 is a 15-year-old girl who has had familial Mediterranean fever (MEFV p.M694V homozygous) for 3 years treated with canakinumab 150 mg/month and colchicine. All patients had a mild acute COVID-19 course, particularly the adolescent patients. A few weeks after COVID-19 recovery, both CAPS patients developed increased AID activity, necessitating anti-IL-1-treatment intensification in one patient. At day 100, one out of four patients (25%) showed positive antibody response to SARS-CoV-2. This is one of the first reports providing follow-up data about COVID-19 in AID. The risk for severe acute COVID-19 disease was mild/moderate, but increased AID activity post-COVID-19 was detected. Follow-up data and data combination are needed to expand understanding of COVID-19 and SARS-CoV-2 immunity in AID and the role of IT.

Children and Adults with PFAPA Syndrome: Similarities and Divergences in a Real-Life Clinical Setting

INTRODUCTION

Analogies or differences of periodic fever, aphthous stomatitis, pharyngitis, and adenitis (PFAPA) syndrome in children and adults are barely known. The aim of our study was to compare the overall characteristics of a large cohort of patients, both children and adults, diagnosed with PFAPA syndrome.

METHODS

In the last decade, we identified 120 children and 63 adults with periodically recurring fevers, who fulfilled the criteria for PFAPA diagnosis. The two subcohorts were analyzed according to demographic features, clinical manifestations, laboratory data, and responses to therapies.

RESULTS

The mean age of onset was 2.4 ± 1.5 and 19.7 ± 10.3 years, respectively, in children and adults, while attacks occurred every 3.8 ± 0.8 and every 4.3 ± 2.3 weeks, respectively, in children and adults. A higher prevalence of exudative pharyngitis was observed in children (58.8%), and the majority of children had only two cardinal signs during flares. In adults, there was a higher interpersonal variability of the intercritical periods. Inflammatory markers measured during non-febrile periods were normal in children but altered in the totality of adults during febrile periods. A strong efficacy of corticosteroids in controlling the pediatric syndrome was observed, but response rates to steroids were less brilliant in adults. Colchicine and interleukin-1 inhibitors were used in the management of the steroid-resistant adult syndrome. Conversely, tonsillectomy was performed in a very low number of children, but was effective in 60.7% of adults when treated after 16 years. The mean age of disappearance of PFAPA symptoms has been 6.4 ± 2.4 years in children, while only 27% of adults have shown a complete drug-free symptom regression.

CONCLUSIONS

A linear conformity of the PFAPA syndrome has been observed between pediatric and adult patients. PFAPA symptoms tended to disappear with no sequelae in 94.1% of children, while the disease was still active in almost 3/4 of adults at the time of our assessment.

The off-label use of anakinra in pediatric systemic autoinflammatory diseases

Interleukin 1 (IL-1), a central mediator of innate immunity, is considered a master cytokine of local and systemic inflammation. IL-1 has emerged as pivotal in the pathogenesis of autoinflammatory diseases (AIDs), and blockade of its pathway has become a crucial target for therapy. Anakinra (ANA), a recombinant IL-1β receptor antagonist, was the first anti-IL-1 agent employed in clinical practice. ANA is currently approved for the treatment of rheumatoid arthritis, systemic juvenile idiopathic arthritis, adult-onset Still’s disease, and cryopyrin-associated autoinflammatory syndrome. It has also been successfully used for off-label treatment of various monogenic, polygenic, or undefined etiology systemic AIDs.

This review describes currently available evidence for the off-label use of ANA in pediatric rheumatologic diseases. Specifically, the use of ANA in Kawasaki disease, idiopathic recurrent pericarditis, Behçet disease, monogenic AIDs, undifferentiated AIDs, chronic non-bacterial osteomyelitis, macrophage activation syndrome, and febrile infection-related epilepsy, in terms of its safety and efficacy. In selected pediatric rheumatic disorders, the off-label administration of ANA appears to be effective and safe. In order to control severe and/or relapsing disease, ANA should be considered as a valuable treatment option in children suffering from rare inflammatory diseases. However, currently available data consist of retrospective studies and short case series; thus, randomized controlled trials and larger series with long-term follow up are mandatory to better assess the efficacy and cost effectiveness of ANA in these challenging patients.

Phenotype variability of autoinflammatory disorders in the pediatric patient: A pictorial overview

Disruption of innate immunity leading to systemic inflammation and multi-organ dysfunction is the basilar footprint of autoinflammatory disorders (AIDs), ranging from rare hereditary monogenic diseases to a large number of common chronic inflammatory conditions in which there is a simultaneous participation of multiple genetic components and environmental factors, sometimes combined with autoimmune phenomena and immunodeficiency. Whatever their molecular mechanism, hereditary AIDs are caused by mutations in regulatory molecules or sensors proteins leading to dysregulated production of proinflammatory cytokines or cytokine-inducing transcription factors, fever, elevation of acute phase reactants, and a portfolio of manifold inflammatory signs which might occur in a stereotyped manner, mostly with overactivity or misactivation of different inflammasomes. Symptoms might overlap in the pediatric patient, obscuring the final diagnosis of AIDs and delaying the most appropriate treatment. Actually, the fast-paced evolution of scientific knowledge has led to recognize or reclassify an overgrowing number of multifactorial diseases, which share the basic pathogenetic mechanisms with AIDs. The wide framework of classic hereditary periodic fevers, AIDs with prominent skin involvement, disorders of the ubiquitin-proteasome system, defects of actin cytoskeleton dynamics, and also idiopathic nonhereditary febrile syndromes occurring in children is herein presented. Interleukin-1 dependence of these diseases or involvement of other predominating molecules is also discussed.

National survey of Japanese patients with mevalonate kinase deficiency reveals distinctive genetic and clinical characteristics

OBJECTIVES

Mevalonate kinase deficiency (MKD), a rare autosomal recessive autoinflammatory syndrome, is caused by disease-causing variants of the mevalonate kinase (MVK) gene. A national survey was undertaken to investigate clinical and genetic features of MKD patients in Japan.

METHODS

The survey identified ten patients with MKD. Clinical information and laboratory data were collected from medical records and by direct interviews with patients, their families, and their attending physicians. Genetic analysis and measurement of MVK activity and urinary excretion of mevalonic acid were performed.

RESULTS

None of the 10 patients harbored MVK disease-causing variants that are common in European patients. However, overall symptoms were in line with previous European reports. Continuous fever was observed in half of the patients. Elevated transaminase was observed in four of the 10 patients, two of whom fulfilled the diagnostic criteria for hemophagocytic lymphohistiocytosis. About half of the patients responded to temporary administration of glucocorticoids and NSAIDs; the others required biologics such as anti-IL-1 drugs.

CONCLUSION

This is the first national survey of MKD patients in a non-European country. Although clinical symptoms were similar to those reported in Europe, the incidence of continuous fever and elevated transaminase was higher, probably due to differences in disease-causing variants.

The Phenotype and Genotype of Mevalonate Kinase Deficiency: A Series of 114 Cases From the Eurofever Registry

OBJECTIVE

Mevalonate kinase deficiency (MKD) is a rare metabolic disease characterized by recurrent inflammatory episodes. This study was undertaken to describe the genotype, phenotype, and response to treatment in an international cohort of MKD patients.

METHODS

All MKD cases were extracted from the Eurofever registry (Executive Agency for Health and Consumers project no. 2007332), an international, multicenter registry that retrospectively collects data on children and adults with autoinflammatory diseases.

RESULTS

The study included 114 MKD patients. The median age at onset was 0.5 years. Patients had on average 12 episodes per year. Most patients had gastrointestinal symptoms (n = 112), mucocutaneous involvement (n = 99), lymphadenopathy (n = 102), or musculoskeletal symptoms (n = 89). Neurologic symptoms included headache (n = 43), cerebellar syndrome (n = 2), and mental retardation (n = 4). AA amyloidosis was noted in 5 patients, almost twice as many as expected from findings in previous cohorts. Macrophage activation syndrome occurred in 1 patient. Patients were generally well between attacks, but 10-20% of the patients had constitutional symptoms, such as fatigue, between fever episodes. Patients with p.V377I/p.I268T compound heterozygosity had AA amyloidosis significantly more often. Patients without a p.V377I mutation more often had severe musculoskeletal involvement. Treatment with nonsteroidal antiinflammatory drugs relieved symptoms. Steroids given during attacks, anakinra, and etanercept appeared to improve symptoms and could induce complete remission in patients with MKD.

CONCLUSION

We describe the clinical and genetic characteristics of 114 MKD patients, which is the largest cohort studied so far. The clinical manifestations confirm earlier reports. However, the prevalence of AA amyloidosis is far higher than expected.

Macrophage activation syndrome triggered by coeliac disease: a unique case report

BACKGROUND

Macrophage activation syndrome is described as a "clinical syndrome of hyperinflammation resulting in an uncontrolled and ineffective immune response" in the context of an autoinflammatory or rheumatic disease. Current associations of macrophage activation syndrome with autoimmune disease most notably include a host of rheumatological conditions and inflammatory bowel disease. Epidemiological studies have shown that macrophage activation syndrome is precipitated by autoimmune disease more commonly than previously thought. Diagnosing the precipitating factor is essential for effective treatment and prognosis.

CASE PRESENTATION

We report a case of a six year old girl with coeliac disease diagnosed after two episodes of secondary haemophagocytic lymphohistiocytosis. Her condition only responded to treatment once the patient was placed on a gluten free diet. Further immunological testing confirmed anti-transglutaminase and anti-endomysial antibodies, however histological biopsy was deemed inappropriate due to the severity of her condition. She has remained stable with no further episodes of macrophage activation syndrome since commencing a gluten free diet.

CONCLUSION

This case report is the first literature that links macrophage activation syndrome to coeliac disease and highlights the challenge of diagnosing coeliac disease with unusual features such as associated prolonged fever. Clinicians should have a low threshold for screening children with other autoimmune diseases for coeliac disease.

Mevalonate kinase deficiency: current perspectives

Mevalonate kinase deficiency (MKD) is a recessively inherited autoinflammatory disorder with a spectrum of manifestations, including the well-defined clinical phenotypes of hyperimmunoglobulinemia D and periodic fever syndrome and mevalonic aciduria. Patients with MKD have recurrent attacks of hyperinflammation associated with fever, abdominal pain, arthralgias, and mucocutaneous lesions, and more severely affected patients also have dysmorphisms and central nervous system anomalies. MKD is caused by mutations in the gene encoding mevalonate kinase, with the degree of residual enzyme activity largely determining disease severity. Mevalonate kinase is essential for the biosynthesis of nonsterol isoprenoids, which mediate protein prenylation. Although the precise pathogenesis of MKD remains unclear, increasing evidence suggests that deficiency in protein prenylation leads to innate immune activation and systemic hyperinflammation. Given the emerging understanding of MKD as an autoinflammatory disorder, recent treatment approaches have largely focused on cytokine-directed biologic therapy. Herein, we review the current genetic and pathologic understanding of MKD, its various clinical phenotypes, and the evolving treatment approach for this multifaceted disorder.

Review: Macrophage activation syndrome in juvenile systemic lupus erythematosus: an under-recognized complication?

Macrophage activation syndrome (MAS) is a life-threatening complication of rheumatic diseases that is thought to be caused by the activation and uncontrolled proliferation of T lymphocytes and macrophages, leading to widespread haemophagocytosis and cytokine overproduction. It is seen most commonly in systemic juvenile idiopathic arthritis, but is increasingly recognized also in juvenile systemic lupus erythematosus (J-SLE). Recognition of MAS in patients with J-SLE is often challenging because it may mimic the clinical features of the underlying disease or be confused with an infectious complication. This review summarizes the characteristics of patients with J-SLEassociated MAS reported in the literature or seen by the authors and analyses the distinctive clinical, diagnostic and therapeutic issues that the occurrence of MAS may raise in patients with J-SLE. Lupus (2007) 16, 587—592.

2016 Classification Criteria for Macrophage Activation Syndrome Complicating Systemic Juvenile Idiopathic Arthritis: A European League Against Rheumatism/American College of Rheumatology/Paediatric Rheumatology International Trials Organisation Collaborative Initiative

To develop criteria for the classification of macrophage activation syndrome (MAS) in patients with systemic juvenile idiopathic arthritis (JIA). A multistep process, based on a combination of expert consensus and analysis of real patient data, was conducted. A panel of 28 experts was first asked to classify 428 patient profiles as having or not having MAS, based on clinical and laboratory features at the time of disease onset. The 428 profiles comprised 161 patients with systemic JIA-associated MAS and 267 patients with a condition that could potentially be confused with MAS (active systemic JIA without evidence of MAS, or systemic infection). Next, the ability of candidate criteria to classify individual patients as having MAS or not having MAS was assessed by evaluating the agreement between the classification yielded using the criteria and the consensus classification of the experts. The final criteria were selected in a consensus conference. Experts achieved consensus on the classification of 391 of the 428 patient profiles (91.4%). A total of 982 candidate criteria were tested statistically. The 37 best-performing criteria and 8 criteria obtained from the literature were evaluated at the consensus conference. During the conference, 82% consensus among experts was reached on the final MAS classification criteria. In validation analyses, these criteria had a sensitivity of 0.73 and a specificity of 0.99. Agreement between the classification (MAS or not MAS) obtained using the criteria and the original diagnosis made by the treating physician was high (κ=0.76). We have developed a set of classification criteria for MAS complicating systemic JIA and provided preliminary evidence of its validity. Use of these criteria will potentially improve understanding of MAS in systemic JIA and enhance efforts to discover effective therapies, by ensuring appropriate patient enrollment in studies.

2016 Classification Criteria for Macrophage Activation Syndrome Complicating Systemic Juvenile Idiopathic Arthritis: A European League Against Rheumatism/American College of Rheumatology/Paediatric Rheumatology International Trials Organisation Collaborative Initiative

OBJECTIVE

To develop criteria for the classification of macrophage activation syndrome (MAS) in patients with systemic juvenile idiopathic arthritis (JIA).

METHODS

A multistep process, based on a combination of expert consensus and analysis of real patient data, was conducted. A panel of 28 experts was first asked to classify 428 patient profiles as having or not having MAS, based on clinical and laboratory features at the time of disease onset. The 428 profiles comprised 161 patients with systemic JIA-associated MAS and 267 patients with a condition that could potentially be confused with MAS (active systemic JIA without evidence of MAS, or systemic infection). Next, the ability of candidate criteria to classify individual patients as having MAS or not having MAS was assessed by evaluating the agreement between the classification yielded using the criteria and the consensus classification of the experts. The final criteria were selected in a consensus conference.

RESULTS

Experts achieved consensus on the classification of 391 of the 428 patient profiles (91.4%). A total of 982 candidate criteria were tested statistically. The 37 best-performing criteria and 8 criteria obtained from the literature were evaluated at the consensus conference. During the conference, 82% consensus among experts was reached on the final MAS classification criteria. In validation analyses, these criteria had a sensitivity of 0.73 and a specificity of 0.99. Agreement between the classification (MAS or not MAS) obtained using the criteria and the original diagnosis made by the treating physician was high (κ = 0.76).

CONCLUSION

We have developed a set of classification criteria for MAS complicating systemic JIA and provided preliminary evidence of its validity. Use of these criteria will potentially improve understanding of MAS in systemic JIA and enhance efforts to discover effective therapies, by ensuring appropriate patient enrollment in studies.

Dynamic Changes, Cut-Off Points, Sensitivity, and Specificity of Laboratory Data to Differentiate Macrophage Activation Syndrome from Active Disease

PURPOSE

To compare the laboratory data and changes in these data between patients with MAS and patients with flare-up of the autoimmune diseases.

METHODS

In a prospective study, the static laboratory data and dynamic changes in the selected data in 17 consecutive patients with MAS and 53 patients with active disease of SJIA, PJIA, Kawasaki disease, and SLE were compared. The ROC curve analysis was used to evaluate cut-off points, sensitivity, and specificity of the static and dynamic laboratory data to differentiate between MAS and active disease.

RESULTS

In the MAS group, the mean CRP3, ALT, AST, total bilirubin, ferritin, LDH, PT, PTT, and INR were significantly higher and the mean WBC2, PMN2, Lymph2, Hgb1, 2, 3, ESR2, serum albumin, and sodium were significantly lower than in control group. Some of the important cut-off points were PLT2 < 209000/microliter, AST > 38.5, ALT > 38, WBC < 8200 × 103/UL, ferritin > 5277 ng/mL.

CONCLUSION

The dynamic changes in some laboratory data, especially PLT, can differentiate between MAS and active disease. The changes in WBC, PMN, and ESR and the levels of the liver enzymes may also be helpful in the early differentiation. Very high levels of ferritin may also help the diagnosis along with other clinical and laboratory signs.

Macrophage activation syndrome in the course of monogenic autoinflammatory disorders

An overwhelming activation of cytotoxic T cells and well-differentiated macrophages leading to systemic overload of inflammatory mediators characterizes the so-called macrophage activation syndrome (MAS); this potentially life-threatening clinical entity may derive from several genetic defects involved in granule-mediated cytotoxicity but has been largely observed in patients with juvenile idiopathic arthritis, many rheumatologic diseases, infections, and malignancies. The occurrence of MAS in the natural history or as the revealing clue of monogenic autoinflammatory disorders (AIDs), rare conditions caused by disrupted innate immunity pathways with overblown release of proinflammatory cytokines, has been only reported in few isolated patients with cryopyrin-associated periodic syndrome, mevalonate kinase deficiency, familial Mediterranean fever, and tumor necrosis factor receptor-associated periodic syndrome since 2001. All these patients displayed various clinical, laboratory, and histopathologic features of MAS and have often required intensive care support. Only one patient has died due to MAS. Defective cytotoxic cell function was documented in a minority of patients. Corticosteroids were the first-line treatment, but anakinra was clinically effective in three refractory cases. Even if MAS and AIDs share multiple clinical features as well as heterogeneous pathogenetic scenes and a potential response to anti-interleukin-1 targeted therapies, MAS requires a prompt specific recognition in the course of AIDs due to its profound severity and high mortality rate.

Complications of systemic juvenile idiopathic arthritis: risk factors and management recommendations

Systemic juvenile idiopathic arthritis (SJIA) is an inflammatory condition characterized by fever, lymphadenopathy, arthritis, rash and serositis. Systemic inflammation has been associated with dysregulation of the innate immune system, suggesting that SJIA is an autoinflammatory disorder. IL-1 and IL-6 play a major role in the pathogenesis of SJIA, and treatment with IL-1 and IL-6 inhibitors has shown to be highly effective. However, complications of SJIA, including macrophage activation syndrome, limitations in functional outcome by arthritis and long-term damage from chronic inflammation, continue to be a major issue in SJIA patients' care. Translational research leading to a profound understanding of the cytokine crosstalk in SJIA and the identification of risk factors for SJIA complications will help to improve long-term outcome.

Current advances in the understanding and treatment of mevalonate kinase deficiency

Mevalonate kinase deficiency (MKD) is a rare autosomal recessive autoinflammatory metabolic disease that is caused by mutations in the MVK gene. Patients with MKD typically have an early onset in infancy. MKD is characterized by recurrent episodes of high fever, abdominal distress, diffuse joint pain, and skin rashes. In a subset of patients, MKD is also associated with elevated serum immunoglobulin D (IgD) levels (hyperimmunoglobulinemia D syndrome, HIDS). The clinical phenotype of MKD varies widely and depends on the severity of the impaired mevalonate kinase activity. Complete impairment results in the severe metabolic disease, mevalonic aciduria, while a partial deficiency results in a broad spectrum of clinical presentation, including HIDS. The precise molecular mechanisms behind the elevated serum IgD levels and inflammation that occurs in MKD remain unknown. Children who exhibit symptoms of MKD should be tested for mutations in the MKD gene. However, the complexity of MKD often results in delays in its definitive diagnosis and the outcome in adult age is not completely known. Therapeutic options for MKD are based on limited data and include non-steroidal anti-inflammatory drugs, corticosteroids, and biological agents that target specific cytokine pathways. In recent years, some studies have reported promising results for new biological drugs; however, these cases have failed to achieve satisfactory remission. Therefore, further studies are needed to understand the pathogenesis of MKD and identify innovative therapeutic tools for its management.

A restrospective survey of patients's journey before the diagnosis of mevalonate kinase deficiency

Mevalonate kinase deficiency (MKD) is an autosomic recessive auto-inflammatory disease caused by mutations of the MVK gene. MKD being a very rare disease, numerous misdiagnoses and medical referrals may precede the right diagnosis, amplifying the burden of the disease.

OBJECTIVES

To evaluate the patient's medical referrals between the first symptom and the diagnosis of MKD and the diagnosis delay.

METHODS

A questionnaire was sent to French paediatric and adult rheumatologists to retrospectively collect information from genetically confirmed patients with MKD regarding the first symptoms of the disease, the different diagnoses made previously, the treatments received, and the disease burden evaluated mainly by the number of hospitalizations.

RESULTS

Thirteen patients were analyzed. The mean age at onset was 9.5months (birth to 36months). The average diagnosis delay was 7.1years. Eleven of them were hospitalized at least 5 times before the establishment of the diagnosis. A wide variety of diseases had been suspected: systemic juvenile idiopathic arthritis, periodic fever aphtous stomatitis pharyngitis adenitis syndrome, other hereditary recurrent fever, vasculitis, connective tissue disease, inflammatory bowel disease, gastritis, infections and immunodeficiency. Before the right diagnosis, 9 patients received corticosteroids and 6 patients received non-steroidal-anti-inflammatory drugs. Half patients had received repeated antibiotics, one third had received intravenous immunoglobulin, and the others were treated with immunosuppressive drugs or hydroxychloroquine.

CONCLUSIONS

MKD is a serious disease still difficult to treat, however earlier accurate medical referral and care, by increasing physicians' awareness, is critical to improve both the disease course and quality of life.

Identification of the best cutoff points and clinical signs specific for early recognition of macrophage activation syndrome in active systemic juvenile idiopathic arthritis

OBJECTIVES

The purpose of our study was to detect early clinical and laboratory signs that help to discriminate macrophage activation syndrome (MAS) from active systemic juvenile idiopathic arthritis (SJIA) without MAS.

METHODS

Our retrospective study was based on reviewing the medical charts of the children admitted to the rheumatology department with active SJIA and definite MAS (n = 18) and without MAS (n = 40). We evaluated the data related to SJIA and MAS at the moment of the patient׳s admission. If the patient had signs of MAS since admission or developed definite MAS later during this flare, he was referred to the main group. The children who did not have MAS during the flare episode and did not have MAS in the past medical history were in the control group. We calculated the cutoff points for MAS parameters, performed the analysis of sensitivity and specificity, identified the predictors, and provided the preliminary diagnostic rule through "the-number-of-criteria-present" approach.

RESULTS

The clinical signs were relevant to MAS in SJIA: oligoarticular disease course (OR = 5.6), splenomegaly (OR = 67.6), hemorrhages (OR = 33.0), and respiratory failure (OR = 11.3). The involvement of wrist (OR = 0.2), MCP (OR = 0.1), and PIP joints (OR = 0.1) was protective against MAS development. The best cutoffs for laboratory parameters were PLT ≤ 211 × 10(9)/l, WBC ≤ 9.9 × 10(9)/l, AST > 59.7U/l, LDH > 882U/l, albumin ≤ 2.9g/dl, ferritin > 400μg/l, fibrinogen ≤ 1.8g/l, and proteinuria. The laboratory variables were more precise in the discrimination of early MAS than clinical: any 3 or more laboratory criteria provided the highest specificity (1.0) and sensitivity (1.0) and OR = 2997.

CONCLUSIONS

We detected clinical and laboratory markers and created preliminary diagnostic (laboratory) guidelines for early discrimination of MAS in active SJIA.

The hereditary autoinflammatory disorders uncovered

There is a thriving interest in the field of hereditary autoinflammatory disorders (HAID), a gamut of heterogeneous conditions deriving from an aberrant orchestration of innate immunity, unified by the common feature of seemingly unprovoked inflammation, which might be systemic or occur in localized niches of the organism. Recurrent fever and episodic inflammation in the joints, serosal membranes, skin, gut, and other organs are the common denominator of HAID. Mutations in the inflammasome-related genes have been associated with different HAID, showing the intimate link existing between interleukin-1 (IL-1)-structured inflammasome and their pathogenesis. Differential diagnosis of HAID can be challenging, as there are no universally accepted diagnostic protocols, and near half of patients may remain without any genetic abnormality identified. The use of IL-1-antagonists has been associated with beneficial effects in a large number of HAID associated with excessive IL-1 signalling, such as cryopyrin-associated periodic syndromes, familial Mediterranean fever, and deficiency of IL-1 receptor antagonist. This review will discuss about the key-clues of HAID which might guide for an early recognition and drive decisions for treatment.

Update on research and clinical translation on specific clinical areas: From bench to bedside: How insight in immune pathogenesis can lead to precision medicine of severe juvenile idiopathic arthritis

Despite the enormous progress in the treatment of juvenile idiopathic arthritis (JIA), innovations based on true bench-to-bedside research, performed in JIA patients, are still scarce. This chapter describes novel developments in which clinical innovations go hand in hand with basic discoveries. For the purpose of this review, we will mainly focus on developments in severe forms of JIA, most notably systemic JIA and polyarticular JIA. However, also in less severe forms of JIA, such as oligoarticular JIA, better insight will help to improve diagnosis and treatment. Facilitating the transition from bench to bedside will prove crucial for addressing the major challenges in JIA management. If successful, it will set new standards for a safe, targeted and personalized therapeutic approach for children with JIA.

Untangling the web of systemic autoinflammatory diseases

The innate immune system is involved in the pathophysiology of systemic autoinflammatory diseases (SAIDs), an enlarging group of disorders caused by dysregulated production of proinflammatory cytokines, such as interleukin-1β and tumor necrosis factor-α, in which autoreactive T-lymphocytes and autoantibodies are indeed absent. A widely deranged innate immunity leads to overactivity of proinflammatory cytokines and subsequent multisite inflammatory symptoms depicting various conditions, such as hereditary periodic fevers, granulomatous disorders, and pyogenic diseases, collectively described in this review. Further research should enhance our understanding of the genetics behind SAIDs, unearth triggers of inflammatory attacks, and result in improvement for their diagnosis and treatment.

MEFV gene polymorphisms and TNFRSF1A mutation in patients with inflammatory myopathy with abundant macrophages

Inflammatory myopathy with abundant macrophages (IMAM) has recently been proposed as a new clinical condition. Although IMAM shares certain similarities with other inflammatory myopathies, the mechanisms responsible for this condition remain unknown. Patients with familial Mediterranean fever (FMF) and tumour necrosis factor receptor-associated periodic syndrome (TRAPS) also often develop myalgia. We therefore investigated the polymorphisms or mutations of MEFV and TNFRSF1A genes in patients with IMAM to identify their potential role in this condition. We analysed the clinical features of nine patients with IMAM and sequenced exons of the MEFV and TNFRSF1A genes. The patients with IMAM had clinical symptoms such as myalgia, muscle weakness, erythema, fever and arthralgia. Although none of the patients were diagnosed with FMF or TRAPS, seven demonstrated MEFV polymorphisms (G304R, R202R, E148Q, E148Q-L110P and P369S-R408Q), and one demonstrated a TNFRSF1A mutation (C43R). These results suggest that MEFV gene polymorphisms and TNFRSF1A mutation are susceptibility and modifier genes in IMAM.

Monogenic autoinflammatory diseases

During the past 15 years, a growing number of monogenic inflammatory diseases have been described and their respective responsible genes identified. The proteins encoded by these genes are involved in the regulatory pathways of inflammation and are mostly expressed in cells of the innate immune system. Diagnosis remains clinical, with genetic confirmation where feasible. Although a group of patients exhibit episodic systemic inflammation (periodic fevers), these disorders are mediated by continuous overproduction and release of pro-inflammatory mediators, such as IL-1 and IL-6, and TNF and are best considered as autoinflammatory diseases rather than periodic fevers. Treatment with biologic agents that block these cytokines, particularly IL-1, has proved to be dramatically effective in some patients. Still, in many cases of autoinflammation no genetic abnormalities are detected and treatment remains suboptimal, raising the question of novel pathogenic mutations in unexplored genes and pathways.

Weekly oral alendronate in mevalonate kinase deficiency

Background

Mevalonate kinase deficiency (MKD) is caused by mutations in the MVK gene, encoding the second enzyme of mevalonate pathway, which results in subsequent shortage of downstream compounds, and starts in childhood with febrile attacks, skin, joint, and gastrointestinal symptoms, sometimes induced by vaccinations.

Methods

For a history of early-onset corticosteroid-induced reduction of bone mineral density in a 14-year-old boy with MKD, who also had presented three bone fractures, we administered weekly oral alendronate, a drug widely used in the management of osteoporosis and other high bone turnover diseases, which blocks mevalonate and halts the prenylation process.

Results

All of the patient’s MKD clinical and laboratory abnormalities were resolved after starting alendronate treatment.

Conclusions

This observation appears enigmatic, since alendronate should reinforce the metabolic block characterizing MKD, but is crucial because of the ultimate improvement shown by this patient. The anti-inflammatory properties of bisphosphonates are a new question for debate among physicians across various specialties, and requires further biochemical and clinical investigation.

Monogenic autoinflammatory syndromes: state of the art on genetic, clinical, and therapeutic issues

Monogenic autoinflammatory syndromes (MAISs) are caused by innate immune system dysregulation leading to aberrant inflammasome activation and episodes of fever and involvement of skin, serous membranes, eyes, joints, gastrointestinal tract, and nervous system, predominantly with a childhood onset. To date, there are twelve known MAISs: familial Mediterranean fever, tumor necrosis factor receptor-associated periodic syndrome, familial cold urticaria syndrome, Muckle-Wells syndrome, CINCA syndrome, mevalonate kinase deficiency, NLRP12-associated autoinflammatory disorder, Blau syndrome, early-onset sarcoidosis, PAPA syndrome, Majeed syndrome, and deficiency of the interleukin-1 receptor antagonist. Each of these conditions may manifest itself with more or less severe inflammatory symptoms of variable duration and frequency, associated with findings of increased inflammatory parameters in laboratory investigation. The purpose of this paper is to describe the main genetic, clinical, and therapeutic aspects of MAISs and their most recent classification with the ultimate goal of increasing awareness of autoinflammation among various internal medicine specialists.

Debate around infection-dependent hemophagocytic syndrome in paediatrics

Background

Hemophagocytic syndrome (HPS) is clinically defined as a combination of fever, liver dysfunction, coagulation abnormalities, pancytopenia, progressive macrophage proliferation throughout the reticuloendothelial system, and cytokine over-production, and may be primary or secondary to infectious, auto-immune, and tumoral diseases. The most consistent association is with viral infections but, as it is still debated whether any micro-organisms are involved in its pathogenesis, we critically appraised the literature concerning HPS and its relationship with infections.

Discussion

Infection-dependent HPS has been widely observed, but there are no data concerning its incidence in children. A better understanding of the pathophysiology of HPS may clarify the interactions between the immune system and the variously implicated potential infectious agents. Epstein-Barr virus (EBV) infection has been prominently associated with HPS, with clonal proliferation and the hyperactivation of EBV-infected T cells. However, a number of other viral, bacterial, fungal, and parasitic infections have been reported in association with HPS. In the case of low-risk HPS, corticosteroids and/or intravenous immunoglobulin or cyclosporine A may be sufficient to control the biological process, but etoposide is recommended as a means of reversing infection-dependent lymphohistiocytic dysregulation in high-risk cases.

Summary

HPS is a potential complication of various infections. A polymerase chain reaction search for infectious agents including EBV, cytomegalovirus and Leishmania is recommended in clinical settings characterised by non-remitting fever, organomegaly, cytopenia and hyperferritinemia.

Mevalonate kinase deficiency, a metabolic autoinflammatory disease

Mevalonate kinase deficiency is a rare autosomal recessive inborn error of metabolism with an autoinflammatory phenotype. In this review we discuss its pathogenesis, clinical presentation and treatment. Mutations in both copies of the MVK-gene lead to a block in the mevalonate pathway. Interleukin-1beta mediates the inflammatory phenotype. Shortage of a non-sterol isoprenoid product of the mevalonate pathway, Geranylgeranylpyrophosphate leads to aberrant activation of the small GTPase Rac1, and inflammasome activation. The clinical phenotype ranges widely, depending on the severity of the enzyme defect. All patients show recurrent fevers, lymphadenopathy and high acute phase proteins. Severely affected patients have antenatal disease onset, dysmorphic features, growth retardation, cognitive impairment and progressive ataxia. Diagnosis relies on mutation analysis of the MVK-gene. There is no evidence based therapy. IL-1 blockade is usually effective. Severe cases require allogeneic stem cell transplantation. Targeted therapies are needed.

Macrophage activation syndrome as part of systemic juvenile idiopathic arthritis: diagnosis, genetics, pathophysiology and treatment

Macrophage activation syndrome (MAS) is a severe, frequently fatal complication of systemic juvenile idiopathic arthritis (sJIA) with features of hemophagocytosis leading to coagulopathy, pancytopenia, and liver and central nervous system dysfunction. MAS is overt in 10% of children with sJIA but occurs subclinically in another 30-40%. It is difficult to distinguish sJIA disease flare from MAS. Development of criteria for establishing MAS as part of sJIA are under way and will hopefully prove sensitive and specific. Mutations in cytolytic pathway genes are increasingly being recognized in children who develop MAS as part of sJIA. Identification of these mutations may someday assist in MAS diagnosis. Defects in cytolytic genes have provided murine models of MAS to study pathophysiology and treatment. Recently, the first mouse model of MAS not requiring infection but rather dependent on repeated stimulation through Toll-like receptors was reported. This provides a model of MAS that may more accurately reflect MAS pathology in the setting of autoinflammation or autoimmunity. This model confirms the importance of a balance between pro- and anti-inflammatory cytokines. There has been remarkable progress in the use of anti-pro-inflammatory cytokine therapy, particularly against interleukin-1, in the treatment of secondary forms of MAS, such as in sJIA.

Mevalonate kinase deficiency: a survey of 50 patients

OBJECTIVE

The goal of this study was to describe the spectrum of clinical signs of mevalonate kinase deficiency (MKD).

METHODS

This was a retrospective French and Belgian study of patients identified on the basis of MKD gene mutations.

RESULTS

Fifty patients from 38 different families were identified, including 1 asymptomatic patient. Symptoms began during the first 6 months of life in 30 patients (60%) and before the age of 5 years in 46 patients (92%). Symptoms consisted of febrile diarrhea and/or rash in 23 of 35 patients (66%). Febrile attacks were mostly associated with lymphadenopathy (71%), diarrhea (69%), joint pain (67%), skin lesions (67%), abdominal pain (63%), and splenomegaly (63%). In addition to febrile attacks, 27 patients presented with inflammatory bowel disease, erosive polyarthritis, Sjögren syndrome, and other chronic neurologic, renal, pulmonary, endocrine, cutaneous, hematologic, or ocular symptoms. Recurrent and/or severe infections were observed in 13 patients, hypogammaglobulinemia in 3 patients, and renal angiomyolipoma in 3 patients. Twenty-nine genomic mutations were identified; the p.Val377Ile mutation was the most frequently found (29 of 38 families). Three patients died of causes related to MKD. The disease remained highly active in 17 of the 31 surviving symptomatic patients followed up for >5 years, whereas disease activity decreased over time in the other 14 patients. Interleukin 1 antagonists were the most effective biological agents tested, leading to complete or partial remission in 9 of 11 patients.

CONCLUSION

MKD is not only an autoinflammatory syndrome but also a multisystemic inflammatory disorder, a possible immunodeficiency disorder, and a condition that predisposes patients to the development of renal angiomyolipoma.

Pathogenesis of systemic juvenile idiopathic arthritis: some answers, more questions

Systemic juvenile idiopathic arthritis (sJIA) has long been recognized as unique among childhood arthritides, because of its distinctive clinical and epidemiological features, including an association with macrophage activation syndrome. Here, we summarize research into sJIA pathogenesis. The triggers of disease are unknown, although infections are suspects. Once initiated, sJIA seems to be driven by innate proinflammatory cytokines. Endogenous Toll-like receptor ligands, including S100 proteins, probably synergize with cytokines to perpetuate inflammation. These and other findings support the hypothesis that sJIA is an autoinflammatory condition. Indeed, IL-1 is implicated as a pivotal cytokine, but the source of excess IL-1 activity remains obscure and the role of IL-1 in chronic arthritis is less clear. Another hypothesis is that a form of hemophagocytic lymphohistiocytosis underlies sJIA, with varying degrees of its expression across the spectrum of disease. Alternatively, sJIA with MAS might be a genetically distinct subtype. Yet another hypothesis proposes that inadequate downregulation of immune activation is central to sJIA, supporting evidence for which includes 'alternative activation' of monocyte and macrophages and possible deficiencies in IL-10 and T regulatory cells. Some altered immune phenotypes persist during clinically inactive disease, which suggests that this stage might represent compensated inflammation. Despite much progress being made, many questions remain, providing fertile ground for future research.

The function and regulation of immunoglobulin D

Recent discoveries of IgD in ancient vertebrates suggest that IgD has been preserved in evolution from fish to human for important immunological functions. A non-canonical form of class switching from IgM to IgD occurs in the human upper respiratory mucosa to generate IgD-secreting B cells that bind respiratory bacteria and their products. In addition to enhancing mucosal immunity, IgD class-switched B cells enter the circulation to 'arm' basophils and other innate immune cells with secreted IgD. Although the nature of the IgD receptor remains elusive, cross-linking of IgD on basophils stimulates release of immunoactivating, proinflammatory and antimicrobial mediators. This pathway is dysregulated in autoinflammatory disorders such as hyper-IgD syndrome, indicating that IgD orchestrates an ancestral surveillance system at the interface between immunity and inflammation.

New insights into the enigma of immunoglobulin D

Immunoglobulin D (IgD) has remained a mysterious antibody class for almost half a century. IgD was initially thought to be a recently evolved Ig isotype expressed only by some mammalian species, but recent discoveries in fishes and amphibians demonstrate that IgD was present in the ancestor of all jawed vertebrates and has important immunological functions. The structure of IgD has been very dynamic throughout evolution. Mammals can express IgD through alternative splicing and class switch recombination. Active cell-dependent and T-cell-independent IgM-to-IgD class switching takes place in a unique subset of human B cells from the upper aerodigestive mucosa, which provides a layer of mucosal protection by interacting with many pathogens and their virulence factors. Circulating IgD can bind to myeloid cells such as basophils and induce antimicrobial, inflammatory, and B-cell-stimulating factors upon cross-linking, which contributes to not only immune surveillance but also inflammation and tissue damage when this pathway is overactivated under pathological conditions. Recent research shows that IgD is an important immunomodulator that orchestrates an ancestral surveillance system at the interface between immunity and inflammation.

The spectrum of autoinflammatory diseases: recent bench to bedside observations

PURPOSE OF REVIEW

The autoinflammatory diseases are a group of conditions that include the hereditary fever syndromes, and result from upregulated innate immune responses. The discovery of the genetic basis for these conditions led to the description of novel intracellular receptors for infectious and noninfectious danger signals. This article focuses on recent progress in our understanding of autoinflammatory syndromes, and how insights into these conditions have triggered the exploration of the role of innate immunity in common rheumatologic diseases.

RECENT FINDINGS

New models for the pathogenesis of several autoinflammatory syndromes have been proposed, including the role of pyrin and cryopyrin in regulating inflammation. Robust evidence has emerged that IL-1beta oversecretion is pivotal in cryopyrin-associated periodic syndromes, and that IL-1 inhibition ameliorates the clinical features of these syndromes. Monosodium urate crystals stimulate IL-1beta secretion via cryopyrin, which led to the addition of gout to the spectrum of autoinflammatory diseases.

SUMMARY

Advances in our understanding of the autoinflammatory diseases have led to renewed interest in the innate immune system, and its role in the pathogenesis of more common rheumatic diseases.