Failure of anti-TNF therapy in TNF Receptor 1-Associated Periodic Syndrome (TRAPS)

Inflammasome activation: from molecular mechanisms to autoinflammation

Inflammasomes are assembled by innate immune sensors that cells employ to detect a range of danger signals and respond with pro-inflammatory signalling. Inflammasomes activate inflammatory caspases, which trigger a cascade of molecular events with the potential to compromise cellular integrity and release the IL-1β and IL-18 pro-inflammatory cytokines. Several molecular mechanisms, working in concert, ensure that inflammasome activation is tightly regulated; these include NLRP3 post-translational modifications, ubiquitination and phosphorylation, as well as single-domain proteins that competitively bind to key inflammasome components, such as the CARD-only proteins (COPs) and PYD-only proteins (POPs). These diverse regulatory systems ensure that a suitable level of inflammation is initiated to counteract any cellular insult, while simultaneously preserving tissue architecture. When inflammasomes are aberrantly activated can drive excessive production of pro-inflammatory cytokines and cell death, leading to tissue damage. In several autoinflammatory conditions, inflammasomes are aberrantly activated with subsequent development of clinical features that reflect the degree of underlying tissue and organ damage. Several of the resulting disease complications may be successfully controlled by anti-inflammatory drugs and/or specific cytokine inhibitors, in addition to more recently developed small-molecule inhibitors. In this review, we will explore the molecular processes underlying the activation of several inflammasomes and highlight their role during health and disease. We also describe the detrimental effects of these inflammasome complexes, in some pathological conditions, and review current therapeutic approaches as well as future prospective treatments.

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.

Monogenic autoinflammatory disorders: beyond the periodic fever

The past two decades have seen an exponential increase in the number of monogenic autoinflammatory disorders described, coinciding with improved genetic sequencing techniques. This group of disorders has evolved to be heterogeneous and certainly more complex than the original four 'periodic fever syndromes' caused by innate immune over-activation. This review aims to provide an update on the classic periodic fever syndromes as well as introducing the broadening spectrum of clinical features seen in more recently described conditions.

Periodic fever syndromes and the autoinflammatory diseases (AIDs)

Innate immune system represents the ancestral defense against infectious agents preserved along the evolution and species; it is phylogenetically older than the adaptive immune system, which exists only in the vertebrates. Cells with phagocytic activity such as neutrophils, macrophages, and natural killer (NK) cells play a key role in innate immunity. In 1999 Kastner et al. first introduced the term “autoinflammation” describing two diseases characterized by recurrent episodes of systemic inflammation without any identifiable infectious trigger: Familial Mediterranean Fever (FMF) and TNF Receptor Associated Periodic Syndrome (TRAPS). Autoinflammatory diseases (AIDs) are caused by self-directed inflammation due to an alteration of innate immunity leading to systemic inflammatory attacks typically in an on/off mode. In addition to inflammasomopathies, nuclear factor (NF)-κB-mediated disorders (also known as Rhelopathies) and type 1 interferonopathies are subjects of more recent studies.

This review aims to provide an overview of the field with the most recent updates (see “Most recent developments in..” paragraphs) and a description of the newly identified AIDs.

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Autoinflammatory diseases are caused by self-directed inflammation.

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Alteration of innate immunity leads to systemic inflammation attacks.

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The autoinflammatory field is exponentially expanding.

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The advances in AIDs have led to new insights into immune system understanding.

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Autoimmunity and autoinflammation features may be simultaneously present.

Somatic mosaicism in adult-onset TNF receptor-associated periodic syndrome (TRAPS)

BACKGROUND

Somatic mosaicism is to date an uncommon finding in genetic autoinflammatory syndromes such as Cryopyrin-associated periodic syndrome, Blau syndrome, and TNF receptor-associated periodic syndrome (TRAPS). However, somatic mosaicism may be particularly important in adult-onset or atypical phenotypes of these conditions. Herein, we report a unique adult-onset TRAPS patient presenting with intermittent daily fever for 3 weeks, rash, peritonitis, and lymphadenopathy, who was found with hematopoietic mosaicism involving different white blood cell populations.

METHODS

Patient's lymphocyte genomic DNA was initially analyzed by periodic fever seven-gene next-generation sequencing panel. Genomic DNAs extracted from patient's hair roots, buccal swab, and subpopulations of white blood cells were subsequently examined on the identified TNFRSF1A variant using Sanger sequencing.

RESULTS

A de novo mosaic missense variant, c.265 T>C(p.Phe89Leu), in the TNFRSF1A gene was found in the patient's buccal swab, B cells, neutrophils, and NK cells but not detected in monocytes, T cells, and hair roots.

CONCLUSION

These data provide additional information about somatic mosaicism in autoinflammatory conditions and provide new insights regarding cellular players that are indispensable for the phenotypic expression of TRAPS.

Autoinflammatory Disorders: A Review and Update on Pathogenesis and Treatment

The autoinflammatory diseases comprise a broad spectrum of disorders characterized by unchecked activation of the innate immune system. Whereas aberrations in adaptive immunity have long been identified in 'autoimmune' disorders, the concept of 'autoinflammation' emerged relatively recently, first describing a group of clinical disorders characterized by spontaneous episodes of systemic inflammation without manifestations typical of autoimmune disorders. Improved knowledge of innate immune mechanisms, coupled with remarkable progress in genomics and an expanding number of clinical cases, has since led to an increasing number of disorders classified as autoinflammatory or containing an autoinflammatory component. Biologic therapies targeting specific components of the innate immune system have provided immense clinical benefit, and have further elucidated the role of innate immunity in autoinflammatory disorders. This article reviews the basic mechanisms of autoinflammation, followed by an update on the pathophysiology and treatment of the monogenic and multifactorial autoinflammatory diseases, and the common dermatologic conditions in which autoinflammation plays a major role.

Inflammasome-Dependent Cytokines at the Crossroads of Health and Autoinflammatory Disease

As key regulators of both innate and adaptive immunity, it is unsurprising that the activity of interleukin (IL)-1 cytokine family members is tightly controlled by decoy receptors, antagonists, and a variety of other mechanisms. Additionally, inflammasome-mediated proteolytic maturation is a prominent and distinguishing feature of two important members of this cytokine family, IL-1β and IL-18, because their full-length gene products are biologically inert. Although vital in antimicrobial host defense, deregulated inflammasome signaling is linked with a growing number of autoimmune and autoinflammatory diseases. Here, we focus on introducing the diverse inflammasome types and discussing their causal roles in periodic fever syndromes. Therapies targeting IL-1 or IL-18 show great efficacy in some of these autoinflammatory diseases, although further understanding of the molecular mechanisms leading to unregulated production of these key cytokines is required to benefit more patients.

The TNF Family of Ligands and Receptors: Communication Modules in the Immune System and Beyond

The tumor necrosis factor (TNF) and TNF receptor (TNFR) superfamilies (TNFSF/TNFRSF) include 19 ligands and 29 receptors that play important roles in the modulation of cellular functions. The communication pathways mediated by TNFSF/TNFRSF are essential for numerous developmental, homeostatic, and stimulus-responsive processes in vivo. TNFSF/TNFRSF members regulate cellular differentiation, survival, and programmed death, but their most critical functions pertain to the immune system. Both innate and adaptive immune cells are controlled by TNFSF/TNFRSF members in a manner that is crucial for the coordination of various mechanisms driving either co-stimulation or co-inhibition of the immune response. Dysregulation of these same signaling pathways has been implicated in inflammatory and autoimmune diseases, highlighting the importance of their tight regulation. Investigation of the control of TNFSF/TNFRSF activities has led to the development of therapeutics with the potential to reduce chronic inflammation or promote anti-tumor immunity. The study of TNFSF/TNFRSF proteins has exploded over the last 30 yr, but there remains a need to better understand the fundamental mechanisms underlying the molecular pathways they mediate to design more effective anti-inflammatory and anti-cancer therapies.

Targeting cytokines to treat autoinflammatory diseases

Autoinflammatory diseases are rare group of conditions manifested by recurrent fevers, systemic inflammation, and dysfunctions of the innate immune system. These conditions are characterized by overproduction or lack of inhibition of various cytokines, and the advent of biologic drugs that block specific cytokines involved in these conditions has revolutionized their treatment. In this review, I will discuss the most common autoinflammatory conditions of adulthood including familial Mediterranean fever (FMF), cryopyrin-associated periodic syndrome (CAPS), mevalonate kinase deficiency/hyperimmunoglobulinemia D Syndrome (MKD/HIDS), TNF receptor-associated autoinflammatory syndrome (TRAPS), and systemic juvenile idiopathic arthritis/adult-onset Still's disease (SJIA/AOSD). I will discuss how IL-1, IL-6, IL-18, and TNF play pathogenic roles in these conditions and will review the evidence behind cytokine blockade for these diseases. Throughout the paper, I will reflect on gaps in knowledge of autoinflammatory diseases and will highlight the latest advances and newest drugs in development.

Dysregulated IL-1β Secretion in Autoinflammatory Diseases: A Matter of Stress?

Infectious and sterile inflammation is induced by activation of innate immune cells. Triggering of toll-like receptors by pathogen-associated molecular pattern or damage-associated molecular pattern (PAMP or DAMP) molecules generates reactive oxygen species that in turn induce production and activation of pro-inflammatory cytokines such as IL-1β. Recent evidence indicates that cell stress due to common events, like starvation, enhanced metabolic demand, cold or heat, not only potentiates inflammation but may also directly trigger it in the absence of PAMPs or DAMPs. Stress-mediated inflammation is also a common feature of many hereditary disorders, due to the proteotoxic effects of mutant proteins. We propose that harmful mutant proteins can induce dysregulated IL-1β production and inflammation through different pathways depending on the cell type involved. When expressed in professional inflammatory cells, stress induced by the mutant protein activates in a cell-autonomous way the onset of inflammation and mediates its aberrant development, resulting in the explosive responses that hallmark autoinflammatory diseases. When expressed in non-immune cells, the mutant protein may cause the release of transcellular stress signals that trigger and propagate inflammation.

An Up-to-date Approach to a Patient with a Suspected Autoinflammatory Disease

Autoinflammatory diseases (AID) are characterized by seemingly unprovoked self-limited attacks of fever and systemic inflammation potentially leading to amyloidosis. Familial Mediterranean fever (FMF) is the most common AID and therefore the most studied. Besides FMF, the other main hereditary AID are tumor necrosis factor-associated periodic fever syndrome (TRAPS), mevalonate kinase deficiency (MKD), and cryopyrin-associated periodic fever syndrome (CAPS). These hereditary diseases result from a mutant gene that is involved in the regulation of inflammation, resulting in a characteristic clinical phenotype. The differential diagnosis of AID can be challenging due to a wide overlap in clinical manifestations. Moreover, a considerable proportion of patients present with autoinflammatory symptoms but without a pathogenetic variant on genetic analysis. Furthermore, non-hereditary AID, such as the periodic fever, aphthous stomatitis, pharyngitis, adenitis (PFAPA) syndrome, which is the most common AID in children worldwide, must be excluded in certain circumstances. Herein we shall review the main AID and describe a practical approach to diagnosis in a patient with a clinical suspicion of AID.

Canakinumab treatment for patients with active recurrent or chronic TNF receptor-associated periodic syndrome (TRAPS): an open-label, phase II study

Objective

To evaluate the efficacy of canakinumab, a high-affinity human monoclonal anti-interleukin-1β antibody, in inducing complete or almost complete responses in patients with active tumour necrosis factor receptor-associated periodic syndrome (TRAPS).

Methods

Twenty patients (aged 7–78 years) with active recurrent or chronic TRAPS were treated with canakinumab 150 mg every 4 weeks for 4 months (2 mg/kg for those ≤40 kg) in this open-label, proof-of-concept, phase II study. Canakinumab was then withdrawn for up to 5 months, with reintroduction on relapse, and 4 weekly administration (subsequently increased to every 8 weeks) for 24 months. The primary efficacy variable was the proportion of patients achieving complete or almost complete response at day 15, defined as clinical remission (Physician's Global Assessment score ≤1) and full or partial serological remission.

Results

Nineteen patients (19/20, 95%; 95% CI 75.1% to 99.9%) achieved the primary efficacy variable. Responses to canakinumab occurred rapidly; median time to clinical remission 4 days (95% CI 3 to 8 days). All patients relapsed after canakinumab was withdrawn; median time to relapse 91.5 days (95% CI 65 to 117 days). On reintroduction of canakinumab, clinical and serological responses were similar to those seen during the first phase, and were sustained throughout treatment. Canakinumab was well tolerated and clinical responses were accompanied by rapid and sustained improvement in health-related quality of life. Weight normalised pharmacokinetics of canakinumab, although limited, appeared to be consistent with historical canakinumab data.

Conclusions

Canakinumab induces rapid disease control in patients with active TRAPS, and clinical benefits are sustained during long-term treatment.

Trial registration number

NCT01242813; Results.

The Relationship between NALP3 and Autoinflammatory Syndromes

The nucleotide-binding domain, leucine-rich repeat/pyrin domain-containing-3 (NALP3) inflammasome, which is required for synthesis of interleukin-1β, has been implicated in the pathogenesis of several autoinflammatory syndromes. This review of the literature summarizes the interconnectedness of NALP3 inflammasome with some of these disorders. Familial Mediterranean fever results from a mutation in the Mediterranean fever (MEFV) gene, which encodes the pyrin protein. Previous study results suggest that pyrin suppresses caspase-1 activation, perhaps by competing for the adaptor protein, termed, pyrin domain of apoptosis/speck-like protein containing a caspase-recruitment domain (ACS) which therefore interferes with NALP3 inflammasome activation. The nucleotide-binding domain, leucine-rich repeat/pyrin domain-containing-3 (NALP3) inflammasome is constitutively activated in cryopyrin-associated periodic syndromes due to gain-of-function mutations resulting from point mutations within the neuronal apoptosis inhibitor protein/class 2 transcription factor/heterokaryon incompatibility/telomerase-associated protein-1 (NACHT) domain of the NALP3 protein. Pyogenic arthritis, pyoderma gangrenosum and acne (PAPA) syndrome is caused by mutations in the genes encoding proline-serine-threonine phosphatase interacting protein 1 (PSTPIP1). These PSTPIP1 mutants are thought to bind to pyrin causing an increase in the pyrin domain of apoptosis/speck-like protein containing a caspase-recruitment domain (ASC) pyroptosome assembly leading to procaspase-1 recruitment and therefore its activation. Hyperimmunoglublinemia D syndrome is caused by mevalonate kinase (MVK) deficiency, which may be affected by protein accumulation that leads to NALP3 inflammasome activation. Tumor necrosis factor receptor-associated periodic syndrome is associated with mutations in the tumor necrosis factor receptor superfamily, member 1A (TNFRSF1A) gene which decreases the level of soluble tumor necrosis factor receptor-1 (TNFR1) leading to neutralization of tumor necrosis factor (TNF)-α. In general, these autoinflammatory disorders have shown a clinical response to interleukin-1 (IL-1) antagonists, suggesting that the NALP3 inflammasome serves a critical role in their pathogenesis.

Genetically defined autoinflammatory diseases

Autoinflammatory diseases are hyperinflammatory, immune dysregulatory conditions that typically present in early childhood with fever and rashes and disease-specific patterns of organ inflammation. This review provides a historic background of autoinflammatory disease research, an overview of the currently genetically defined autoinflammatory diseases, and insights into treatment strategies derived from understanding of the disease pathogenesis. The integrative assessment of autoinflammatory conditions led to the identification of innate pro-inflammatory cytokine 'amplification loops' as the cause of the systemic and organ-specific disease manifestations, which initially centered around increased IL-1 production and signaling. More recently, additional innate pro-inflammatory cytokine amplification loops resulting in increased Type I IFN, IL-17, IL-18, or IL-36 signaling or production have led to the successful use of targeted therapies in some of these conditions. Clinical findings such as fever patterns, type of skin lesions, genetic mutation testing, and the prevalent cytokine abnormalities can be used to group autoinflammatory diseases.

Genetic variants associated with autoimmunity drive NFκB signaling and responses to inflammatory stimuli

The transcription factor nuclear factor κB (NFκB) is a central regulator of inflammation, and genome-wide association studies in subjects with autoimmune disease have identified a number of variants within the NFκB signaling cascade. In addition, causal variant fine-mapping has demonstrated that autoimmune disease susceptibility variants for multiple sclerosis (MS) and ulcerative colitis are strongly enriched within binding sites for NFκB. We report that MS-associated variants proximal to NFκB1 and in an intron of TNFRSF1A (TNFR1) are associated with increased NFκB signaling after tumor necrosis factor-α (TNFα) stimulation. Both variants result in increased degradation of inhibitor of NFκB α (IκBα), a negative regulator of NFκB, and nuclear translocation of p65 NFκB. The variant proximal to NFκB1 controls signaling responses by altering the expression of NFκB itself, with the GG risk genotype expressing 20-fold more p50 NFκB and diminished expression of the negative regulators of the NFκB pathway: TNFα-induced protein 3 (TNFAIP3), B cell leukemia 3 (BCL3), and cellular inhibitor of apoptosis 1 (CIAP1). Finally, naïve CD4 T cells from patients with MS express enhanced activation of p65 NFκB. These results demonstrate that genetic variants associated with risk of developing MS alter NFκB signaling pathways, resulting in enhanced NFκB activation and greater responsiveness to inflammatory stimuli. As such, this suggests that rapid genetic screening for variants associated with NFκB signaling may identify individuals amenable to NFκB or cytokine blockade.

Targeting the inflammasome in rheumatic diseases

Activation of the inflammasome, a protein complex responsible for many cellular functions, including the activation of the proinflammatory cytokines interleukin (IL)-1β and IL-18, has been identified as a key participant in many rheumatic diseases including autoimmune, inflammatory, and autoinflammatory syndromes. This review will discuss the recent advances in understanding the role of this complex in various rheumatic diseases. Furthermore, it will focus on available therapies, which directly and indirectly target the inflammasome and its downstream cytokines to quiet inflammation and possibly dampen autoimmune processes.

Canakinumab efficacy and long-term tocilizumab administration in tumor necrosis factor receptor-associated periodic syndrome (TRAPS)

Tumor necrosis factor receptor-associated periodic syndrome (TRAPS) is an autosomal dominantly inherited autoinflammatory disease caused by mutations in the TNFRSF1A gene. Treatment is aimed at preventing acute disease attacks, improving quality of life, and preventing long-term complications such as systemic reactive amyloidosis. Biologic agents have significantly improved TRAPS management. In particular, interleukin 1 (IL-1) inhibition either with the recombinant IL-1 receptor antagonist anakinra or with the human IgG1 anti-IL-1β monoclonal antibody canakinumab has recently shown to induce a prompt and stable disease remission. Conversely, the successful experience with IL-6 inhibition is nowadays limited to a single patient. Anyway, introduction of new treatment options for patients requiring a lifelong therapy is desirable. We describe two TRAPS patients (son and father) successfully treated with canakinumab and tocilizumab, respectively. In particular, we highlight the clinical and laboratory efficacy as well as the good safety profile of tocilizumab during a 42-month follow-up period.

The novel S59P mutation in the TNFRSF1A gene identified in an adult onset TNF receptor associated periodic syndrome (TRAPS) constitutively activates NF-κB pathway

Introduction

Mutations in the TNFRSF1A gene, encoding tumor necrosis factor receptor 1 (TNF-R1), are associated with the autosomal dominant autoinflammatory disorder, called TNF receptor associated periodic syndrome (TRAPS). TRAPS is clinically characterized by recurrent episodes of long-lasting fever and systemic inflammation. A novel mutation (c.262 T > C; S59P) in the TNFRSF1A gene at residue 88 of the mature protein was recently identified in our laboratory in an adult TRAPS patient. The aim of this study was to functionally characterize this novel TNFRSF1A mutation evaluating its effects on the TNF-R1-associated signaling pathways, firstly NF-κB, under particular conditions and comparing the results with suitable control mutations.

Methods

HEK-293 cell line was transfected with pCMV6-AC construct expressing wild-type (WT) or c.262 T > C (S59P), c.362G > A (R92Q), c.236C > T (T50M) TNFRSF1A mutants. Peripheral blood mononuclear cells (PBMCs) were instead isolated from two TRAPS patients carrying S59P and R92Q mutations and from five healthy subjects. Both transfected HEK-293 and PBMCs were stimulated with tumor necrosis factor (TNF) or interleukin 1β (IL-1β) to evaluate the expression of TNF-R1, the activation of TNF-R1-associated downstream pathways and the pro-inflammatory cytokines by means of immunofluorescent assay, array-based technique, immunoblotting and immunometric assay, respectively.

Results

TNF induced cytoplasmic accumulation of TNF-R1 in all mutant cells. Furthermore, all mutants presented a particular set of active TNF-R1 downstream pathways. S59P constitutively activated IL-1β, MAPK and SRC/JAK/STAT3 pathways and inhibited apoptosis. Also, NF-κB pathway involvement was demonstrated in vitro by the enhancement of p-IκB-α and p65 nuclear subunit of NF-κB expression in all mutants in the presence of TNF or IL-1β stimulation. These in vitro results correlated with patients’ data from PBMCs. Concerning the pro-inflammatory cytokines secretion, mainly IL-1β induced a significant and persistent enhancement of IL-6 and IL-8 in PBMCs carrying the S59P mutation.

Conclusions

The novel S59P mutation leads to defective cellular trafficking and to constitutive activation of TNF-R1. This mutation also determines constitutive activation of the IL-1R pathway, inhibition of apoptosis and enhanced and persistent NF-κB activation and cytokine secretion in response to IL-1β stimulation.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0604-7) contains supplementary material, which is available to authorized users.

A Case Presenting with the Clinical Characteristics of Tumor Necrosis Factor (TNF) Receptor-associated Periodic Syndrome (TRAPS) without TNFRSF1A Mutations Successfully Treated with Tocilizumab

A 30-year-old woman had suffered from recurrent and self-limiting fevers since childhood. Although she had no mutations in the exons or introns of the tumor necrosis factor (TNF) receptor superfamily member 1A gene, her clinical characteristics were consistent with those of TNF receptor-associated periodic syndrome (TRAPS). She did not respond to treatment with etanercept, although tocilizumab therapy was successful, subsequently ameliorating her symptoms and preventing further inflammatory attacks. Interleukin-6 blocking therapy should be considered as a new alternative treatment in patients with TRAPS who do not respond to etanercept.

An update on autoinflammatory diseases

Autoinflammatory diseases area group of clinical conditions other than autoimmune diseases, characterized by recurrent inflammatory episodes. From apathogenetic point of view they are determined by a dys regulation of innate immunity, without involvement of specific immunity (auto reactive T cells and auto antibodies). Recently, the increased knowledge in the field of auto inflammation highlighted shared immune mechanisms in the pathogenesis of both classical monogenetic and multifactorial auto inflammatory diseases and a broad spectrum of chronic age-related inflammatory pathologies. The current increase in the prevalence of chronic inflammatory diseases makes this subject of topical interest. In the light of these considerations, we propose an update of auto inflammatory diseases and a new interpretation of auto inflammation with both theoretical and clinical implications.

Key facts and hot spots on tumor necrosis factor receptor-associated periodic syndrome

Tumor necrosis factor receptor-associated periodic syndrome (TRAPS), formerly known as familial Hibernian fever, is the most common autosomal dominant autoinflammatory disease, resulting from mutations in the TNFRSF1A gene, encoding the 55-kD tumor necrosis factor receptor. The pathophysiologic mechanism of TRAPS remains ambiguous and only partially explained. The onset age of the syndrome is variable and the clinical scenery is characterized by recurrent episodes of high-grade fever that typically lasts 1-3 weeks, associated with migrating myalgia, pseudocellulitis, diffuse abdominal pain, appendicitis-like findings, ocular inflammatory signs, and risk of long-term amyloidosis. Fever episodes are responsive to high-dose corticosteroids, but different classes of drugs have been reported to be ineffective. The use of etanercept is unable to control systemic inflammation, while interleukin-1 blockade has been shown as effective in the control of disease activity in many patients reported so far.

Cytokines and chemokines: At the crossroads of cell signalling and inflammatory disease

Inflammation occurs as a result of exposure of tissues and organs to harmful stimuli such as microbial pathogens, irritants, or toxic cellular components. The primary physical manifestations of inflammation are redness, swelling, heat, pain, and loss of function to the affected area. These processes involve the major cells of the immune system, including monocytes, macrophages, neutrophils, basophils, dendritic cells, mast cells, T-cells, and B-cells. However, examination of a range of inflammatory lesions demonstrates the presence of specific leukocytes in any given lesion. That is, the inflammatory process is regulated in such a way as to ensure that the appropriate leukocytes are recruited. These events are in turn controlled by a host of extracellular molecular regulators, including members of the cytokine and chemokine families that mediate both immune cell recruitment and complex intracellular signalling control mechanisms that characterise inflammation. This review will focus on the role of the main cytokines, chemokines, and their receptors in the pathophysiology of auto-inflammatory disorders, pro-inflammatory disorders, and neurological disorders involving inflammation.

Regulation and dysregulation of tumor necrosis factor receptor-1

TNF is an essential regulator of the immune system. Dysregulation of TNF plays a role in the pathology of many auto-immune diseases. TNF-blocking agents have proven successful in the treatment of such diseases. Development of novel, safer or more effective drugs requires a deeper understanding of the regulation of the pro-inflammatory activities of TNF and its receptors. The ubiquitously expressed TNFR1 is responsible for most TNF effects, while TNFR2 has a limited expression pattern and performs immune-regulatory functions. Despite extensive knowledge of TNFR1 signaling, the regulation of TNFR1 expression, its modifications, localization and processing are less clear and the data are scattered. Here we review the current knowledge of TNFR1 regulation and discuss the impact this has on the host.

Modified regimen of etanercept for tumor necrosis factor receptor associated periodic syndrome (TRAPS) like illness

BACKGROUND

TRAPS, an autosomal dominant autoinflammatory disorder occurs due to mutations of the TNFRSF1A gene. Mutation negative TRAPS (TRAPS like illness) is also known. Anti TNF molecules (etanercept) is the mainstay of therapy.

CASE CHARACTERISTICS

A 11-year-old boy with a 5 year clinical profile indicative of a TRAPS like illness and with negative mutation studies is described. He has been followed up for nearly 2 years after starting etanercept.

OUTCOME

He had sustained response to etanercept which has subsequently been titrated (0.4 mg/kg subcutaneously every 23-24 days) to keep him symptom free.

MESSAGE

Mutation negative cases of TRAPS can be diagnosed with a high index of suspicion. Treatment with etanercept is expensive but possibly intervals between doses could be titrated to reduce cost.

Autoinflammatory diseases

Autoinflammatory diseases represent an expanding spectrum of genetic and non-genetic inflammatory diseases characterized by recurrent episodes of fever and systemic inflammation affecting the eyes, joints, skin, and serosal surfaces. Thus, these syndromes are recognized as disorders of innate immunity. Confirming this view, most autoinflammatory diseases are uniquely responsive to IL-1β blockade. Although many autoinflammatory diseases have a genetic cause, increasing evidence indicates that the degree of cell stress concurs to the severity of the disease phenotype. In this mini-review, I will discuss the recent advances on pathogenesis, pathophysiology and therapeutic approaches in autoinflammatory syndromes.

First report of circulating microRNAs in tumour necrosis factor receptor-associated periodic syndrome (TRAPS)

Tumor necrosis factor-receptor associated periodic syndrome (TRAPS) is a rare autosomal dominant autoinflammatory disorder characterized by recurrent episodes of long-lasting fever and inflammation in different regions of the body, such as the musculo-skeletal system, skin, gastrointestinal tract, serosal membranes and eye. Our aims were to evaluate circulating microRNAs (miRNAs) levels in patients with TRAPS, in comparison to controls without inflammatory diseases, and to correlate their levels with parameters of disease activity and/or disease severity. Expression levels of circulating miRNAs were measured by Agilent microarrays in 29 serum samples from 15 TRAPS patients carrying mutations known to be associated with high disease penetrance and from 8 controls without inflammatory diseases. Differentially expressed and clinically relevant miRNAs were detected using GeneSpring GX software. We identified a 6 miRNAs signature able to discriminate TRAPS from controls. Moreover, 4 miRNAs were differentially expressed between patients treated with the interleukin (IL)-1 receptor antagonist, anakinra, and untreated patients. Of these, miR-92a-3p and miR-150-3p expression was found to be significantly reduced in untreated patients, while their expression levels were similar to controls in samples obtained during anakinra treatment. MiR-92b levels were inversely correlated with the number of fever attacks/year during the 1^st year from the index attack of TRAPS, while miR-377-5p levels were positively correlated with serum amyloid A (SAA) circulating levels. Our data suggest that serum miRNA levels show a baseline pattern in TRAPS, and may serve as potential markers of response to therapeutic intervention.

Biological treatments: new weapons in the management of monogenic autoinflammatory disorders

Treatment of monogenic autoinflammatory disorders, an expanding group of hereditary diseases characterized by apparently unprovoked recurrent episodes of inflammation, without high-titre autoantibodies or antigen-specific T cells, has been revolutionized by the discovery that several of these conditions are caused by mutations in proteins involved in the mechanisms of innate immune response, including components of the inflammasome, cytokine receptors, receptor antagonists, and oversecretion of a network of proinflammatory molecules. Aim of this review is to synthesize the current experience and the most recent evidences about the therapeutic approach with biologic drugs in pediatric and adult patients with monogenic autoinflammatory disorders.

A taste of periodic fever syndromes

Periodic fevers are acquired or inherited disorders of innate immunity, which were first described in the 1940s. The patients are typically young at onset and have regularly recurring fevers for a few days to a few weeks with systemic inflammatory symptoms that are interrupted by symptom-free periods. There is a variety of clinical manifestations including gastrointestinal complaints, myalgias, arthralgias, and rash. A differential diagnosis in these patients may include recurrent infections, other inflammatory disorders, and neoplastic disease. This clinical review focuses on a sample of autoinflammatory disorders including familial Mediterranean fever, tumor necrosis factor receptor 1-associated periodic syndrome, hyperimmunoglobulinemia D syndrome, the cryopyrin-associated periodic syndrome, and periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis syndrome. We review the basics, pertinent clinical and laboratory features, and management of each entity.

Monogenic autoinflammatory diseases: concept and clinical manifestations

The objective of this review is to describe the clinical manifestations of the growing spectrum of monogenic autoinflammatory diseases including recently described syndromes. The autoinflammatory diseases can be grouped based on clinical findings: 1. the three classic hereditary "periodic fever syndromes", familial Mediterranean Fever (FMF); TNF receptor associated periodic syndrome (TRAPS); and mevalonate kinase deficiency/hyperimmunoglobulinemia D and periodic fever syndrome (HIDS); 2. the cryopyrin associated periodic syndromes (CAPS), comprising familial cold autoinflammatory syndrome (FCAS), Muckle-Wells syndrome (MWS) and neonatal-onset multisystem inflammatory disease (NOMID) or CINCA, and; 3. pediatric granulomatous arthritis (PGA); 4. disorders presenting with skin pustules, including deficiency of interleukin 1 receptor antagonist (DIRA); Majeed syndrome; pyogenic arthritis, pyoderma gangrenosum and acne (PAPA) syndrome; deficiency of interleukin 36 receptor antagonist (DITRA); CARD14 mediated psoriasis (CAMPS), and early-onset inflammatory bowel diseases (EO-IBD); 5. inflammatory disorders caused by mutations in proteasome components, the proteasome associated autoinflammatory syndromes (PRAAS) and 6. very rare conditions presenting with autoinflammation and immunodeficiency.

Successful treatment of a patient with tumor necrosis factor receptor-associated periodic syndrome using a half-dose of etanercept

TNF receptor-associated periodic syndrome (TRAPS) is caused by mutations of TNFRSF1A gene and characterized by recurrent febrile episodes of prolonged duration and initial good response to steroids. Etanercept, a TNF blocker, has been used as a putative molecular-targeted agent for TRAPS, with some patients showing limited efficacy. Here, we report a patient with TRAPS who recovered from steroid dependency by etanercept and kept remission with a reduced dose of etanercept. The pathophysiology of TRAPS still remains to be elucidated and several hypotheses have been proposed. In the most recent hypothesis, the concerted action of wild-type and mutant TNF receptors plays an important role in provoking enhanced inflammation in TRAPS. The excellent response to etanercept in our patient suggested that there is heterogeneity in TRAPS patients in terms of the contribution of normal TNF signaling to autoinflammation.

Setting up TRAPS

Tumour necrosis factor (TNF) receptor-associated periodic syndrome (TRAPS) is a dominantly inherited autoinflammatory disease caused by heterozygous mutations in the TNFRSF1A gene encoding for the TNF receptor 1 (TNFR1). TRAPS is a multi-faceted and heterogeneous disease which commonly manifests as recurrent episodes of high fever accompanied by abdominal pain, pleurisy, migratory rash, and myalgia. Disease attacks occur spontaneously or may be elicited by minor triggers. Because of a vigorous and sustained acute-phase response it may be complicated by systemic AA amyloidosis. Therapeutically interleukin-1 blockade seems even more promising than TNF blockade. Studies on the pathogenesis of TRAPS have shown TNFα-dependent cellular signalling to be defective, an enigmatic finding considering the hyperinflammatory phenotype of the disease. Several studies indicate that most mutated receptors never reach the cell surface but are misfolded and trapped in the endoplasmic reticulum, where they may elicit an intracellular inflammatory response, and thus lead to constitutional expression of proinflammatory cytokines. The aim of this review is to describe the current understanding of the pathogenesis of TRAPS by integrating recent clinical and laboratory data.

Tumor necrosis factor receptor-associated periodic fever syndrome in a 58-year-old man: caution not to discount TRAPS as a diagnosis in older patients

Tumor necrosis factor receptor-associated periodic fever syndrome (TRAPS) is a rare systemic autoinflammatory disorder characterized by recurrent episodes of fever and localized inflammation of different organs. The disease is dominantly inherited, with an onset usually in early childhood. We describe a case of a 58-year-old patient with TRAPS caused by the low-penetrance R92Q mutation in TNFRSF1A gene. The patient responded well to anti-tumor necrosis factor α therapy. Although periodic fever syndromes, including TRAPS, mainly begin in early childhood, it is important to consider periodic fever syndrome also in patient presenting at an age older than the average reported case for TRAPS.

The emerging role of interleukin-1β in autoinflammatory diseases

The autoinflammatory syndromes are a group of multisystem disorders characterized by recurrent episodes of fever and systemic inflammation affecting the eyes, joints, skin, and serosal surfaces in the absence of an immune reaction. Recent advances have revealed the importance of interleukin-1β, not only in the pathogenesis of many of these rare inherited diseases, but also in acquired diseases. The development and availability of anti-interleukin-1β therapeutics have introduced the possibility of proof-of-concept studies, which are likely to further widen this field.

The Eurofever Project: towards better care for autoinflammatory diseases

Autoinflammatory diseases are a group of diseases characterized by inflammatory attacks. The monogenic forms of these diseases are also classified as the hereditary periodic fever syndromes. All are characterized by attacks of fever along with certain clinical features and high acute phase reactants. Most of these monogenic diseases are associated with hereditary disorders of the interleukin-1 pathway. The most common autoinflammatory disease is familial Mediterranean fever. The other rather common monogenic diseases are the tumor necrosis factor receptor-associated periodic syndrome, hyperimmunoglobulinemia D with periodic fever syndrome, and cryopyrin-associated periodic fever syndromes (CAPS). However, a number of multifactorial diseases such as Behçet disease are now also categorized under the topic of autoinflammatory diseases. The main features and management of these diseases will be reviewed. Finally, we introduce the "Eurofever" project, aimed to increase awareness and education for the aforementioned diseases. We conclude that the pediatrician should be aware of the features and management of autoinflammatory diseases since all present with fever-the most common symptom of pediatric practice.