Revisiting TNF Receptor-Associated Periodic Syndrome (TRAPS): Current Perspectives

A rare case of uncharacterized autoinflammatory disease: Patient carrying variations in NLRP3 and TNFRSF1A genes

Tumor necrosis factor type 1A receptor-associated periodic syndrome (TRAPS) and cryopyrin-associated autoinflammatory syndrome (CAPS) are rare monogenic autoinflammatory diseases (AIDs) mainly caused by pathogenic variations in the TNFRSF1A and NLRP3 genes, respectively. Here, we describe a unique patient presenting with symptoms overlapping both TRAPS and CAPS, without known pathogenic variants in the respective genes. The patient harbored the p.Val200Met variation in NLRP3 and the p.Ser226Cys variation in TNFRSF1A, prompting us to delve deeper into the functional analysis due to conflicting or inconclusive pathogenicity interpretations of the variants across various databases. Molecular dynamics analysis of the p.Val200Met variation in NLRP3 revealed a rigid conformation in the helical domain 2 subdomain of the NACHT domain. This increased rigidity suggests a potential mechanism by which this variation supports the assembly of the NLRP3 inflammasome. Notably, the patient's peripheral mononuclear blood cells demonstrated an elevated IL-1β response upon lipopolysaccharides (LPS) induction. Subsequent initiation of anti-IL-1β therapy resulted in a significant alleviation of the patient's symptoms, further supporting our hypothesis. We interpret these findings as suggestive of a potential pathophysiological role for the NLPR3 p.Val200Met variation in shaping the patient's clinical phenotype, which was also supported by clinical and genetic analysis of the family. This case underscores the complexity of the genetic landscape in AIDs and highlights the value of combining family genetic and functional data to refine the understanding and management of such challenging cases.

The First Case of a Korean Patient with a Mutation-Confirmed Tumor Necrosis Factor Receptor-Associated Periodic Syndrome

Tumor necrosis factor receptor-associated periodic syndrome (TRAPS, OMIM: #142680) is a rare autoinflammatory disease (AID) with recurrent febrile episodes. To our knowledge, we report herein the first case of a patient with TRAPS in South Korea whose symptoms included fever, arthralgia, abdominal pain, rash, myalgia, cough, and lymphadenopathy. A pathogenic de novo mutation, c.175T>C (p.Cys59Arg), in the tumor necrosis factor receptor superfamily member 1A (TNFRSF1A) gene, was confirmed by gene sequencing. The patient has been with tocilizumab (an interleukin-6 inhibitor); tocilizumab administration every other week has completely alleviated the patient's symptoms. Our report further expands the clinical spectrum of patients with TRAPS and reaffirms the use of tocilizumab as a viable alternative treatment option for those patients who are unsatisfactorily responsive to other commonly used biologics, such as canakinumab, anakinra, infliximab, and etanercept. Furthermore, our report may aid in increasing awareness about the existence of mutation-confirmed TRAPS in South Korea in addition to emphasizing the importance of actively pursuing genetic testing to correctly diagnose rare AID.

Proteasome disorders and inborn errors of immunity

Inborn errors of immunity (IEI) or primary immune deficiencies (PIDD) are caused by variants in genes encoding for molecules that are relevant to the innate or adaptive immune response. To date, defects in more than 450 different genes have been identified as causes of IEI, causing a constellation of heterogeneous clinical manifestations ranging from increased susceptibility to infection, to autoimmunity or autoinflammation. IEI that are mainly characterized by autoinflammation are broadly classified according to the inflammatory pathway that they predominantly perturb. Among autoinflammatory IEI are those characterized by the transcriptional upregulation of type I interferon genes and are referred to as interferonopathies. Within the spectrum of interferonopathies, genetic defects that affect the proteasome have been described to cause autoinflammatory disease and represent a growing area of investigation. This review is focused on describing the clinical, genetic, and molecular aspects of IEI associated with mutations that affect the proteasome and how the study of these diseases has contributed to delineate therapeutic interventions.

Practical Approach to Diagnosis and Management of IL-1-Mediated Autoinflammatory Diseases (CAPS, TRAPS, MKD, and DIRA)

Systemic autoinflammatory diseases (SAIDs) are a group of rare genetic and nongenetic immune dysregulatory disorders associated with high morbidity and mortality if left untreated. Therefore, early diagnosis and initiation of targeted treatment is vital in SAID patients to control the disease activity and prevent long-term immune-mediated damage. A specific group of genetically defined SAIDs is associated with increased inflammasome-mediated production of active interleukin (IL)-1. Even though progress in immunobiology and genetics has brought forth diagnostic tools and novel treatments that have been described in the literature extensively, many challenges remain in the clinical setting. Some challenges that health care providers may face on a day-to-day basis include the requirement of a multidisciplinary approach due to the complexity of these diseases, limited evidence-based treatment options, and barriers to access available therapies. Primarily, IL-1 inhibitors anakinra, canakinumab, and rilonacept are used to control the inflammation in these patients, with the goal of achieving sustainable remission. Recently published provisional points to consider from the European Alliance of Associations for Rheumatology (EULAR) and American College of Rheumatology (ACR) provide diagnosis, management, and monitoring recommendations for four IL-1-mediated autoinflammatory diseases: cryopyrin-associated periodic syndromes (CAPS), tumour necrosis factor receptor-associated periodic syndrome (TRAPS), mevalonate kinase deficiency (MKD), and deficiency of the IL-1 receptor antagonist (DIRA). The goal of this paper is to aid health care professionals by providing a practical approach to diagnosis and management of these four IL-1 mediated SAIDs on the basis of the recent EULAR/ACR recommendations.

"Deficiency in ELF4, X-Linked": a Monogenic Disease Entity Resembling Behçet's Syndrome and Inflammatory Bowel Disease

Defining monogenic drivers of autoinflammatory syndromes elucidates mechanisms of disease in patients with these inborn errors of immunity and can facilitate targeted therapeutic interventions. Here, we describe a cohort of patients with a Behçet's- and inflammatory bowel disease (IBD)-like disorder termed "deficiency in ELF4, X-linked" (DEX) affecting males with loss-of-function variants in the ELF4 transcription factor gene located on the X chromosome. An international cohort of fourteen DEX patients was assessed to identify unifying clinical manifestations and diagnostic criteria as well as collate findings informing therapeutic responses. DEX patients exhibit a heterogeneous clinical phenotype including weight loss, oral and gastrointestinal aphthous ulcers, fevers, skin inflammation, gastrointestinal symptoms, arthritis, arthralgia, and myalgia, with findings of increased inflammatory markers, anemia, neutrophilic leukocytosis, thrombocytosis, intermittently low natural killer and class-switched memory B cells, and increased inflammatory cytokines in the serum. Patients have been predominantly treated with anti-inflammatory agents, with the majority of DEX patients treated with biologics targeting TNFα.

CD14 down-modulation as a real-time biomarker in Kawasaki disease

Objectives

The objectives of this study were to investigate the pathophysiology of Kawasaki disease (KD) from immunological and oxidative stress perspectives, and to identify real-time biomarkers linked to innate immunity and oxidative stress in KD.

Methods

We prospectively enrolled 85 patients with KD and 135 patients with diverse conditions including immune, infectious and non-infectious diseases for this investigation. Flow cytometry was used to analyse the surface expression of CD14, CD38 and CD62L on monocytes, along with a quantitative assessment of CD14 down-modulation. Additionally, oxidative stress levels were evaluated using derivatives of reactive oxygen metabolites (d-ROMs) and antioxidant capacity measured by a free radical elective evaluator system.

Results

During the acute phase of KD, we observed a prominent CD14 down-modulation on monocytes, reflecting the indirect detection of circulating innate immune molecular patterns. Moreover, patients with KD showed a significantly higher CD14 down-modulation compared with infectious and non-infectious disease controls. Notably, the surface expression of CD14 on monocytes was restored concurrently with responses to intravenous immunoglobulin and infliximab treatment in KD. Furthermore, d-ROM levels in patients with KD were significantly elevated compared with patients with infectious and non-infectious diseases. Following intravenous immunoglobulin treatment, oxidative stress levels decreased in patients with KD.

Conclusion

Monitoring CD14 down-modulation on monocytes in real-time is a valuable strategy for assessing treatment response, distinguishing KD relapse from concomitant infections and selecting second-line therapy after IVIG treatment in KD patients. The interplay between inflammation and oxidative stress likely plays a crucial role in the development of KD.

Tumor necrosis factor receptor-associated cycle syndrome: a case report and literature review

Recurring episodes of fever characterize tumor necrosis factor receptor-associated periodic syndrome (TRAPS) which is autosomal dominant. The primary symptoms of patients with TRAPS include prolonged fever, abdominal pain, muscle pain, and skin rashes. The prevalence of TRAPS appeared higher in Western countries than in Asian countries. Herein, we present the case of a 13-year-old girl who experienced intermittent fever for 8 years, with episodes that occur every 2 years. The patient demonstrated periodic fever, headache, vomiting, rash, and elevated inflammatory marker levels during the disease course. A heterozygous C55Y mutation was identified via a direct DNA sequencing of her genomic DNA. This mutation is located in exon 4 of TNFRSF1A. Genetic studies of her sister and mother revealed that they possessed the C55Y heterozygous mutation without demonstrating any clinical signs, while the father did not. Further, we conducted a thorough assessment of the literature and compiled the information from the eight TRAPS case series.

Uveitis Associated with Monogenic Autoinflammatory Syndromes in Children

Monogenic autoinflammatory syndromes (MAISs), are caused by pathogenic genetic variants in the innate immune system, leading to dysregulation and aberrant inflammasome activation spontaneously or with minimal triggering. The diagnosis and treatment of MAISs can be intricate, relying on an increased recognition of potential differential diagnoses. This review examines the clinical features of MAIS, with a special focus on uveitis. It also evaluates treatment options and assesses the effects of activating molecular and cytokine pathways.

The many faces of pediatric urticaria

Urticaria is a common disease that can affect individuals of all age groups, with approximately one-quarter of the population experiencing it at least once in their lifetime. Lesions characterized by erythema and itchy hives can appear anywhere on the body. These can vary in size ranging from millimeters to centimeters, and typically clear within 24 h. About 40% of patients with urticaria have accompanying angioedema, which involves localized deep tissue swelling. Urticaria usually occurs spontaneously and is classified into acute and chronic forms, with the latter referring to a condition that lasts for more than 6 weeks. The prevalence of chronic urticaria in the general population ranges from 0.5% to 5%, and it can either be inducible or spontaneous. The most common form of pediatric urticaria is acute and is usually self-limiting. However, a broad differential diagnosis should be considered in children with urticaria, particularly if they also have accompanying systemic complaints. Differential diagnoses of pediatric urticaria include chronic spontaneous urticaria, chronic inducible urticaria, serum sickness-like reaction, urticarial vasculitis, and mast cell disorders. Conditions that can mimic urticaria, including but not limited to cryopyrinopathies, hyper IgD syndrome, Periodic Fever, Aphthous Stomatitis, Pharyngitis and Adenitis (PFAPA), Tumor Necrosis Factor Receptor Associated Periodic Syndrome (TRAPs), and Schnitzler syndrome should also be considered. The many faces of pediatric urticaria can be both easy and confusing. A pragmatic approach relies on clinical foresight and understanding the various forms of urticaria and their potential mimickers. This approach can pave the way for an accurate and optimized diagnostic approach in children with urticaria.

Targeted Treatment of Diseases of Immune Dysregulation

Increasing molecular knowledge of autoinflammatory and autoimmune disorders has enabled more targeted treatment of these conditions. Treatment of inflammasomopathies is often aimed at interleukin-1 (IL-1) blockade, with potential use of other inhibitors targeting cytokines such as IL-18 and IL-6. Interferonopathies and some disorders with overlap features of autoimmunity and autoinflammation may improve with Janus kinase inhibition. Autoimmune conditions may also respond to inhibition of different cytokines, as well as to inhibition of T and B lymphocytes. Effective treatment is increasingly possible through targeted/precision medicine approaches.

A novel TNFRSF1A mutation associated with TNF-receptor-associated periodic syndrome and its metabolic signature

OBJECTIVE

We describe a family with a novel mutation in the TNF Receptor Superfamily Member 1A (TNFRSF1A) gene causing TNF receptor-associated periodic syndrome (TRAPS) with renal AA amyloidosis.

METHODS

Case series of affected family members. We further investigated the plasma metabolome of these patients in comparison with healthy controls using mass spectrometry.

RESULTS

In all symptomatic family members, we detected the previously undescribed variant c.332A>G (p.Q111R) in the TNFRSF1A gene. Canakinumab proved an effective treatment option leading to remission in all treated patients. One patient with suspected renal amyloidosis showed near normalization of proteinuria under treatment. Analysis of the metabolome revealed 31 metabolic compounds to be upregulated and 35 compounds to be downregulated compared with healthy controls. The most dysregulated metabolites belonged to pathways identified as arginine biosynthesis, phenylalanine, tyrosine and tryptophan biosynthesis, and cysteine and methionine metabolism. Interestingly, the metabolic changes observed in all three TRAPS patients seemed independent of treatment with canakinumab and subsequent remission.

CONCLUSION

We present a novel mutation in the TNFRSF1A gene associated with amyloidosis. Canakinumab is an effective treatment for individuals with this new likely pathogenic variant. Alterations in the metabolome were most prominent in the pathways related to arginine biosynthesis, tryptophan metabolism, and metabolism of cysteine and methionine, and seemed to be unaffected by treatment with canakinumab. Further investigation is needed to determine the role of these metabolomic changes in the pathophysiology of TRAPS.

Macrophage autophagy contributes to immune liver injury in trichloroethylene sensitized mice: Critical role of TNF-α mediating mTOR pathway

Trichloroethylene (TCE) induces occupational medicamentosa-like dermatitis due to TCE (OMDT) with immune liver injury, and TNF-α plays an important role in macrophage polarization and liver injury. However, TNF-α regulating macrophage polarization in liver injury induced by TCE is still unknown. Thus, on the basis of our previous research, we established the TCE-sensitized BALB/c mouse model with R7050, a specific inhibitor of TNFR1. Then, we observed significant decreases in autophagy related protein and gene levels in M1 macrophage in TCE positive group, and R7050 can relieve M1 macrophage autophagy. We also found the phosphorylated form of mammalian target of Rapamycin (mTOR) was activated and the expression of p-mTOR protein increased induce by TCE. In vitro, we found TNFR1 and CD11c were increased in RAW264.7 cell line with TNF-α. And then we use Zafirlukast (Zaf), an TNFR1 antagonist, CD11c and TNFR1 reduced significantly, we also found p-mTOR expression increased after TNF-α treatment, but decreased in TNF-α + Zaf group. Further, we used Rapamycin (RAP), a mTOR-specific inhibitor, to establish a TCE-sensitized mice model and found the expression levels of p62 and p-mTOR proteins increased and LC3B decreased in the TCE positive group, while RAP treatment reversed the trends of all of these proteins. Rapamycin prevented the TNF-α-induced p-mTOR increase and dramatically downregulated IL-1β expression in the RAW264.7 cell line with TNF-α treatment. The results uncover a novel role for TNF-α/TNFR1, which promotes M1 polarization of macrophage and suppresses macrophage autophagy via the mTOR pathway.

A patient with tumor necrosis factor receptor-associated periodic syndrome misdiagnosed as Kawasaki disease: A case report and literature review

This article reports a case of tumor necrosis factor receptor-associated periodic syndrome (TRAPS) misdiagnosed as Kawasaki disease and summarizes the clinical features and therapeutic progress of TRAPS and the relationship between its clinical manifestations and gene mutations. We retrospectively analyzed a patient with tumor necrosis factor receptor superfamily member 1A (TNFRSF1A) -mutated auto-inflammatory disease who was misdiagnosed with Kawasaki disease in another hospital. The clinical features and therapeutic progress of TRAPS were analyzed by combining clinical features and gene reports of this case and literature review. TRAPS onset occurred in a female pediatric patient at the age of 4 months. The child and in his father at the age of 6 years, both of whom manifested periodic fever, and recurrent rash, as well as elevated leukocytes, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) during episodes but normal between episodes. This child carried a heterozygous mutation in TNFRSF1A located in the region 6442923-6442931 on chromosome 12. The nucleic acid alteration was: c.298 (exon3) _c.306 (exon3) 291 delCTCAGCTGC, resulting in a 3 amino acid deletion p.L100_C 102del 292 (p.Leu100_Cys102del) (NM_001065). After etanercept treatment, the symptoms of fever and rash disappeared, and the levels of ESR, CRP, interleukin (IL)-1, IL-6, and TNF-α levels were normal. Subsequently, no liver, kidney, or cardiac amyloidosis and severe etanercept-related adverse events were observed at 1-year follow-up. TRAPS pathogenesis is associated with TNFRSF1A mutation, which is characterized by periodic episodes of fever, mostly accompanied by recurrent rashes, periorbital edema, abdominal pain, and serious complications of organ amyloidosis. Moreover, etanercept can effectively alleviate the clinical symptoms and high inflammation level of TRAPS.

Monogenic autoinflammatory disease-associated cardiac damage

INTRODUCTION

Autoinflammatory diseases (AIDs) constitute several disorders that are characterized by the presence of recurrent episodes of unprovoked inflammation due to dysregulated innate immune system in the absence of autoantibodies or infections. Most of them have a strong genetic background, with mutations in single genes involved in inflammation referred to monogenic AIDs. In this article, we will review the cardiac manifestations in various monogenic AIDs.

AREAS COVERED

Various cardiac manifestations can be seen in various monogenic AIDs, including pericarditis, valvular diseases, coronary diseases, cardiomyopathies, and pulmonary hypertension, especially in Familial Mediterranean fever (FMF).

EXPERT COMMENTARY

Monogenic AIDs can manifest a variety of cardiac lesions, the most common of which is pericardial effusion, which may be local pericardial inflammation secondary to systemic inflammatory responses. While, the pathogenesis and incidence are still unclear. More research is still needed to explore the relationship between monogenic AIDs and cardiac damage for better understanding these diseases.

Renal involvement in monogenic autoinflammatory diseases: A narrative review

Autoinflammatory diseases (AIDs) are mostly caused by dysfunctions in single genes encoding for proteins with a prominent role in the regulation of innate immunity, such as complement factors, inflammasome components, tumour necrosis factor (TNF)-α, and proteins belonging to type I-interferon (IFN) signalling pathways. Due to the deposition of amyloid A (AA) fibrils in the glomeruli, unprovoked inflammation in AIDs frequently affects renal health. In fact, secondary AA amyloidosis is the most common form of amyloidosis in children. It is caused by the extracellular deposition of fibrillar low-molecular weight protein subunits resulting from the degradation and accumulation of serum amyloid A (SAA) in numerous tissues and organs, primarily the kidneys. The molecular mechanisms underlying AA amyloidosis in AIDs are the elevated levels of SAA, produced by the liver in response to pro-inflammatory cytokines, and a genetic predisposition due to specific SAA isoforms. Despite the prevalence of amyloid kidney disease, non-amyloid kidney diseases may also be responsible for chronic renal damage in children with AIDs, albeit with distinct characteristics. Glomerular damage can result in various forms of glomerulonephritis with distinct histologic characteristics and a different underlying pathophysiology. This review aims to describe the potential renal implications in patients with inflammasomopathies, type-I interferonopathies, and other rare AIDs in an effort to improve the clinical course and quality of life in paediatric patients with renal involvement.

Biologics and JAK inhibitors for the treatment of monogenic systemic autoinflammatory diseases in children

Systemic autoinflammatory diseases (SAIDs) are caused by aberrant activation of 1 or more inflammatory pathways in an antigen-independent manner. Monogenic forms of SAIDs typically manifest during childhood, and early treatment is essential to minimize morbidity and mortality. On the basis of the mechanism of disease and the dominant cytokine(s) that propagates inflammation, monogenic SAIDs can be grouped into major categories including inflammasomopathies/disorders of IL-1, interferonopathies, and disorders of nuclear factor-κB and/or aberrant TNF activity. This classification scheme has direct therapeutic relevance given the availability of biologic agents and small-molecule inhibitors that specifically target these pathways. Here, we review the experience of using biologics that target IL-1 and TNF as well as using Janus kinase inhibitors for the treatment of monogenic SAIDs in pediatric patients. We provide an evidence-based guide for the use of these medications and discuss their mechanism of action, safety profile, and strategies for therapeutic monitoring.

The assessment of autoinflammatory disease classification criteria (Eurofever/PRINTO) in a real-life cohort

OBJECTIVE

The aim of the study was to determine the sensitivity and specificity rates of Eurofever/PRINTO autoinflammatory recurrent fever classification criteria with real-life data in patients with an autoinflammatory disease.

METHODS

A total of 119 patients were included in the study. Based on clinical symptoms, they were divided into four subgroups: cryopyrin-associated periodic syndromes (CAPS), TNF receptor-associated periodic syndrome (TRAPS), mevalonate kinase deficiency (MKD), and syndrome of undifferentiated recurrent fever (SURF) using the Eurofever/PRINTO clinical classification criteria. In the last step, the patients were re-evaluated in the light of genetic results and their final diagnosis was reached.

RESULTS

A total of 119 patients, including 37 CAPS, 13 TRAPS, 8 MKD, 39 SURF, 14 NLRP12-related autoinflammatory disease (NLRP12-AID), and 8 familial Mediterranean fever (FMF) patients were evaluated in the study. While the sensitivity of the new clinical Eurofever/PRINTO criteria was 48% for CAPS, 77% for TRAPS, 87.5%for MKD, and the specificity of the clinical criteria was 86% for CAPS, 85% for TRAPS, and 60% for MKD. The sensitivity of the new mixed (genetic plus clinical variables) Eurofever/PRINTO criteria was 27% for CAPS, 61% forTRAPS, 85% for MKD, and the specificity of the mixed criteria for each group was 100%.

CONCLUSION

We found the sensitivity of the Eurofever/PRINTO classification criteria to be low as genotypic changes between populations cause phenotypic differences. For this reason, we think that patient-based evaluation is correct rather than standard classification criteria in real life. Key-points • In systemic autoinflammatory diseases, common variants in the populations may alter the phenotype, and making it difficult to classify some patients with the current classification criteria. • In populations with common genetic variants, the classification criteria should be modified according to the clinical phenotype.

Interstitial Lung Disease in Immunocompromised Children

BACKGROUND

The range of pulmonary complications beyond infections in pediatric immunocompromised patients is broad but not well characterized. Our goal was to assess the spectrum of disorders with a focus on interstitial lung diseases (ILD) in immunodeficient patients.

METHODS

We reviewed 217 immunocompromised children attending a specialized pneumology service during a period of 23 years. We assigned molecular diagnoses where possible and categorized the underlying immunological conditions into inborn errors of immunity or secondary immunodeficiencies according to the IUIS and the pulmonary conditions according to the chILD-EU classification system.

RESULTS

Among a wide array of conditions, opportunistic and chronic infections were the most frequent. ILD had a 40% prevalence. Of these children, 89% had a CT available, and 66% had a lung biopsy, which supported the diagnosis of ILD in 95% of cases. Histology was often lymphocyte predominant with the histo-pattern of granulomatous and lymphocytic interstitial lung disease (GLILD), follicular bronchiolitis or lymphocytic interstitial pneumonitis. Of interest, DIP, PAP and NSIP were also diagnosed. ILD was detected in several immunological disorders not yet associated with ILD.

CONCLUSIONS

Specialized pneumological expertise is necessary to manage the full spectrum of respiratory complications in pediatric immunocompromised patients.

Pathophysiology, clinical manifestations and current management of IL-1 mediated monogenic systemic autoinflammatory diseases, a literature review

BACKGROUND

Systemic autoinflammatory diseases (SAIDs) are hyperinflammatory and immune-dysregulation conditions that present in childhood. This kind of disease is a rare disease with early-onset, severe condition and difficult diagnosis, which seriously affects the growth and development of children. Most children need a genetic diagnosis. However, with the limitation of access to genetic testing and the detection of somatic mutations, the diagnosis of SAIDs remains challenging. IL-1 is one of the important cytokines involved in the pathogenesis of SAIDs. Here we briefly review monogenic SAIDs mediated by aberrant IL-1 production, with the aim to further understand the pathogenesis, clinical manifestations and treatments of IL-1 mediated SAIDs.

METHODS

Literature reviews were performed using "PubMed" and "Web of Science" by searching for the terms "autoinflammatory diseases" and "IL-1".

RESULTS

Monogenic SAIDs mediated by IL-1 include MKD, FMF, TRAPS, PAAND, PAPA, CAPS, DIRA, Majeed syndrome, NAIAD, NLRC4-MAS, PFIT, APLAID. Monogenic SAIDs have early onset, various clinical manifestations and difficult diagnosis, so early recognition and early treatment can reduce the complications and enhance the quality of life.

CONCLUSIONS

There are many kinds of IL-1 mediated SAIDs. Pediatricians should be alert to SAIDs in the face of the patients with repeated fever, repeated rash and poor effect of routine treatment. The patients should be carried out with gene testing and treatment in time.

IL-1 and autoinflammatory disease: biology, pathogenesis and therapeutic targeting

Over 20 years ago, it was first proposed that autoinflammation underpins a handful of rare monogenic disorders characterized by recurrent fever and systemic inflammation. The subsequent identification of novel, causative genes directly led to a better understanding of how the innate immune system is regulated under normal conditions, as well as its dysregulation associated with pathogenic mutations. Early on, IL-1 emerged as a central mediator for these diseases, based on data derived from patient cells, mutant mouse models and definitive clinical responses to IL-1 targeted therapy. Since that time, our understanding of the mechanisms of autoinflammation has expanded beyond IL-1 to additional innate immune processes. However, the number and complexity of IL-1-mediated autoinflammatory diseases has also multiplied to include additional monogenic syndromes with expanded genotypes and phenotypes, as well as more common polygenic disorders seen frequently by the practising clinician. In order to increase physician awareness and update rheumatologists who are likely to encounter these patients, this review discusses the general pathophysiological concepts of IL-1-mediated autoinflammation, the epidemiological and clinical features of specific diseases, diagnostic challenges and approaches, and current and future perspectives for therapy.

Periodic Fever in Children: Etiology and Diagnostic Challenges

Periodic fever in children is an autoinflammatory illness with an unknown cause. Symptoms include frequent episodes of fever that are followed by an increase in inflammatory markers. A genetic background for periodic fever of unknown origin has been hypothesized, based on its family clustering and parallels to other autoinflammatory illnesses such as familial Mediterranean fever. Genome analysis has been used in studies to look for related gene variations in periodic fever of unknown origin in the pediatric population. 

Children with periodic fevers might be a diagnostic challenge. After ruling out the most prevalent causes, a wide variety of other possibilities are investigated. Infectious and noninfectious causes of periodic fever in children are discussed in this article.

Inflammasomes (intracellular proteins that activate interleukin (IL)-1b and IL-18) and genetic/hereditary variations are thought to be implicated in the pathogenesis of periodic fever. Evaluation and ruling out possible infective or noninfective causes is vital in the diagnosis of periodic fever in children. Investigations demonstrate that there isn't a single gene linked to it, suggesting that it may have a multifactorial or polygenic origin, with an environmental trigger causing inflammasome activation and fever flares. Treatment is usually symptomatic, with drugs such as colchicine and cimetidine having shown promising results in trials.

We explored the literature on periodic fever in children for its epidemiology, pathophysiology, the role of various genes and how they influence the disease and associated complications, and its various treatment modalities.

TRAPS mutations in Tnfrsf1a decrease the responsiveness to TNFα via reduced cell surface expression of TNFR1

Tumor necrosis factor (TNF) receptor-associated periodic syndrome (TRAPS) is an autoinflammatory periodic fever syndrome associated with heterozygous mutations in TNFRSF1A, which encodes TNF receptor type I (TNFR1). Although possible proinflammatory mechanisms have been proposed, most previous studies were performed using in vitro overexpression models, which could lead to undesirable inflammatory responses due to artificial overexpression. It is crucial to reproduce heterozygous mutations at physiological expression levels; however, such studies remain limited. In this study, we generated TRAPS mutant mice and analyzed their phenotypes. Three Tnfrsf1a mutant strains were generated by introducing T79M, G87V, or T90I mutation. T79M is a known mutation responsible for TRAPS, whereas G87V is a TRAPS mutation that we have reported, and T90I is a variant of unknown significance. Using these murine models, we investigated whether TRAPS mutations could affect the inflammatory responses in vivo and in vitro. We found that none of the mutant mice exhibited detectable inflammatory phenotypes under standard housing conditions for 1 year. Interestingly, TRAPS mutant (T79M and G87V) mice had reduced mortality rates after the administration of lipopolysaccharide (LPS) and D-galactosamine, which induce TNFα-dependent lethal hepatitis. Moreover, TRAPS mutations strongly suppressed the development of TNFα-mediated arthritis when crossed with human TNFα transgenic mice. In in vitro primary bone marrow-derived macrophage cultures, the T79M and G87V mutations attenuated the inflammatory responses to TNFα compared with the wild-type, whereas these mutations did not alter the responsiveness of these cells to LPS. The T90I mutant macrophages behaved similarly to wild type in response to LPS and TNFα. The TNFR1 levels were increased in whole-cell lysates of TRAPS mutant macrophages, whereas the cell surface expression of TNFR1 was significantly decreased in TRAPS mutant macrophages. Taken together, TRAPS mutations did not augment the inflammatory responses to TNFα and LPS; instead, they suppressed the response to TNFα via decreased cell surface expression of TNFR1. The stimulation of lymphotoxin-α, adenosine triphosphate, and norepinephrine in primary macrophages or various stimuli in murine splenocytes did not induce detectable inflammatory responses. In conclusion, TRAPS mutations suppressed responsiveness to TNFα, and TRAPS-associated inflammation is likely induced by unconfirmed disease-specific proinflammatory factors.

Mechanism of dexmedetomidine preconditioning on spinal cord analgesia in rats with functional chronic visceral pain

Purpose:

To analyze the effect and mechanism of dexmedetomidine (DEX) analgesia pretreatment on functional chronic visceral pain in rats.

Methods:

Rats were divided into six groups: W1, W2, W3, W4, W5, and W6. The behavioral changes and electrophysiological indexes of rats in each group before and after DEX treatment were detected.

Results:

The levels of abdominal withdrawal reflex (AWR) in W5 and W6 groups were significantly lower than those in group W3, while the levels of thermal withdrawal latency (TWL) and mechanical withdrawal threshold (MWT) were significantly higher than those in group W3 (p < 0.05). The electromyographic signals of W1, W5, and W6 groups showed little fluctuation, while those of groups W2, W3, and W4 showed obvious fluctuation. TLR4 mRNA expression, IRF3, P65, and phosphorylation levels in W4, W5, and W6 groups were significantly lower than those in group W2 (p < 0.05).

Conclusions:

Dexmedetomidine epidural anesthesia pretreatment could significantly inhibit visceral pain response in rats with functional chronic visceral pain, and its mechanism was related to the activation of TLR4 in spinal dorsal horn tissue of rats and the activation inhibition of IRF3 and P65 in the downstream key signals.

The Interactions Between Autoinflammation and Type 2 Immunity: From Mechanistic Studies to Epidemiologic Associations

Autoinflammatory diseases are a group of clinical syndromes characterized by constitutive overactivation of innate immune pathways. This results in increased production of or responses to monocyte- and neutrophil-derived cytokines such as interleukin-1β (IL-1β), Tumor Necrosis Factor-α (TNF-α), and Type 1 interferon (IFN). By contrast, clinical allergy is caused by dysregulated type 2 immunity, which is characterized by expansion of T helper 2 (Th2) cells and eosinophils, as well as overproduction of the associated cytokines IL-4, IL-5, IL-9, and IL-13. Traditionally, type 2 immune cells and autoinflammatory effectors were thought to counter-regulate each other. However, an expanding body of evidence suggests that, in some contexts, autoinflammatory pathways and cytokines may potentiate type 2 immune responses. Conversely, type 2 immune cells and cytokines can regulate autoinflammatory responses in complex and context-dependent manners. Here, we introduce the concepts of autoinflammation and type 2 immunity. We proceed to review the mechanisms by which autoinflammatory and type 2 immune responses can modulate each other. Finally, we discuss the epidemiology of type 2 immunity and clinical allergy in several monogenic and complex autoinflammatory diseases. In the future, these interactions between type 2 immunity and autoinflammation may help to expand the spectrum of autoinflammation and to guide the management of patients with various autoinflammatory and allergic diseases.

Identification of Genes Linking Natural Killer Cells to Apoptosis in Acute Myocardial Infarction and Ischemic Stroke

Natural killer (NK) cells are a type of innate lymphoid cell that are involved in the progression of acute myocardial infarction and ischemic stroke. Although multiple forms of programmed cell death are known to play important roles in these diseases, the correlation between NK cells and apoptosis-related genes during acute myocardial infarction and ischemic stroke remains unclear. In this study, we explored the distinct patterns of NK cell infiltration and apoptosis during the pathological progression of acute myocardial infarction and ischemic stroke using mRNA expression microarrays from the Gene Expression Omnibus database. Since the abundance of NK cells correlated positively with apoptosis in both diseases, we further examined the correlation between NK cell abundance and the expression of apoptosis-related genes. Interestingly, APAF1 and IRAK3 expression correlated negatively with NK cell abundance in both acute myocardial infarction and ischemic stroke, whereas ATM, CAPN1, IL1B, IL1R1, PRKACA, PRKACB, and TNFRSF1A correlated negatively with NK cell abundance in acute myocardial infarction. Together, these findings suggest that these apoptosis-related genes may play important roles in the mechanisms underlying the patterns of NK cell abundance and apoptosis in acute myocardial infarction and ischemic stroke. Our study, therefore, provides novel insights for the further elucidation of the pathogenic mechanism of ischemic injury in both the heart and the brain, as well as potential useful therapeutic targets.

High Plasma sTNF-R1 Level Is Related to Loss of Natural HIV Control in Long-Term Elite Controllers

Human immunodeficiency virus-1 (HIV-1) elite controllers are heterogeneous due to different immunovirological features. We aimed to identify plasma biomarkers associated with loss of spontaneous HIV-1 control in long-term elite controllers (HIV-LTECs). We performed a retrospective study in 60 HIV-LTECs [36 true-LTECs and 24 LTECs losing control (LTECs-LC)]. We selected a plasma sample from true-LTECs (towards the middle of the follow-up period) and two samples from LTECs-LC (one far from the loss of control and another close to loss of control). Plasma biomarkers were evaluated using multiplex immunoassays. The partial least squares-discriminant analysis provided the variable importance in projection (VIP), and the adjusted Generalized Linear Model provided the adjusted arithmetic mean ratio (aAMR). At the moment of the first LTECs-LC samples, the only plasma biomarker with a VIP≥1.5 was sTNF-R1, which showed higher values in LTECs-LC than true-LTECs [aAMR=1.62 (95%CI=1.20-2.19); p=0.001]. After a median of 3.9 (IQR=4.5) years of follow-up from the first sample, we also had access to a second plasma sample from 10 LTECs-LC patients. At the moment of this second LTECs-LC sample, the only plasma biomarker with VIP≥1.5 was also sTNF-R1, which showed higher values in LTECs-LC than true-LTECs [aAMR=1.93 (95%CI=1.41-2.65); p<0.001]. The difference between the first and second samples of LTECs-LC was significant (Δx= 6.58 (95%=0.3; 12.88); p=0.040). In conclusion, high plasma values of sTNF-R1 appear to discriminate HIV-LTECs that lose the natural control of HIV-1, helping to define a specific phenotype that may be useful for the clinical management of these patients.

A Cysteine Variant at an Allosteric Site Alters MIF Dynamics and Biological Function in Homo- and Heterotrimeric Assemblies

Macrophage migration inhibitory factor (MIF) is an inflammatory protein with various non-overlapping functions. It is not only conserved in mammals, but it is found in parasites, fish, and plants. Human MIF is a homotrimer with an enzymatic cavity between two subunits with Pro1 as a catalytic base, activates the receptors CD74, CXCR2, and CXCR4, has functional interactions in the cytosol, and is reported to be a nuclease. There is a solvent channel down its 3-fold axis with a recently identified gating residue as an allosteric site important for regulating, to different extents, the enzymatic activity and CD74 binding and signaling. In this study we explore the consequence of converting the allosteric residue Tyr99 to cysteine (Y99C) and characterize its crystallographic structure, NMR dynamics, stability, CD74 function, and enzymatic activity. In addition to the homotrimeric variant, we develop strategies for expressing and purifying a heterotrimeric variant consisting of mixed wild type and Y99C for characterization of the allosteric site to provide more insight.

The Role of Anti-IL-1 Medications in Autoinflammatory Disease

The interleukin (IL) -1 family of cytokines are involved in different aspects of inflammation with IL-1 beta being the best known and most powerful proinflammatory cytokine. Dysregulation of IL-1 beta and other family members results in autoinflammatory conditions such as systemic juvenile idiopathic arthritis and familial Mediterranean fever. The growing understanding and knowledge of the pathophysiology of many autoinflammatory diseases have led to the development and use of IL-1 blocking medications for many chronic and disabling diseases. In this article, we present the anti-IL-1 agents and their major indications in pediatric rheumatology. [Pediatr Ann. 2022;51(2):e72-e76.].

[Autoinflammation-differences between children and adults]

Autoinflammatory diseases present as multisystemic inflammation and often manifest in early childhood. In contrast, in a few diseases, e.g., the recently described VEXAS (vacuoles, E1 enzyme, X‑linked, autoinflammatory, somatic) syndrome, the first symptoms occur exclusively in adulthood. This article describes how the phenotypic expression and severity of individual autoinflammatory diseases differ depending on age. Furthermore, differences in the development of organ damage in children and adults are pointed out. In addition to the hereditary periodic fever syndromes, the clinical picture of deficiency of adenosine deaminase 2, the interferonopathies, periodic fever, aphthous stomatitis, pharyngitis, and adenitis syndrome as well as VEXAS and Schnitzler syndromes are highlighted.

Inherited Autoinflammatory Syndromes

Autoinflammation describes a collection of diverse diseases caused by indiscriminate activation of the immune system in an antigen-independent manner. The rapid advancement of genetic diagnostics has allowed for the identification of a wide array of monogenic causes of autoinflammation. While the clinical picture of these syndromes is diverse, it is possible to thematically group many of these diseases under broad categories that provide insight into the mechanisms of disease and therapeutic possibilities. This review covers archetypical examples of inherited autoinflammatory diseases in five major categories: inflammasomopathy, interferonopathy, unfolded protein/cellular stress response, relopathy, and uncategorized. This framework can suggest where future work is needed to identify other genetic causes of autoinflammation, what types of diagnostics need to be developed to care for this patient population, and which options might be considered for novel therapeutic targeting. Expected final online publication date for the Annual Review of Pathology: Mechanisms of Disease, Volume 17 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Infection and autoinflammation in inborn errors of immunity: brothers in arms

The binary view of inborn errors of immunity classified as either autoinflammatory conditions or primary immunodeficiency in the strict sense, that is, increased susceptibility to infection is challenged by the description of recent inborn errors of immunity (IEI) triggers leading to activation and disruption of cell death pathways, play a major part in the pathophysiology of infection and autoinflammation. In addition, molecules with a double role in the extracellular versus intracellular milieu add to the complexity. In all, in-depth study of human inborn errors of immunity will continue to instruct us on fundamental immunology and lead to novel therapeutic targets and approaches that can be used in other monogenic and polygenic/complex immune disorders.

Autoinflammation and autoimmunity across rheumatic and musculoskeletal diseases

Most rheumatic and musculoskeletal diseases (RMDs) can be placed along a spectrum of disorders, with autoinflammatory diseases (including monogenic systemic autoinflammatory diseases) and autoimmune diseases (such as systemic lupus erythematosus and antiphospholipid syndrome) representing the two ends of this spectrum. However, although most autoinflammatory diseases are characterized by the activation of innate immunity and inflammasomes and classical autoimmunity typically involves adaptive immune responses, there is some overlap in the features of autoimmunity and autoinflammation in RMDs. Indeed, some 'mixed-pattern' diseases such as spondyloarthritis and some forms of rheumatoid arthritis can also be delineated. A better understanding of the pathogenic pathways of autoinflammation and autoimmunity in RMDs, as well as the preferential cytokine patterns observed in these diseases, could help us to design targeted treatment strategies.

Biotechnological Agents for Patients With Tumor Necrosis Factor Receptor Associated Periodic Syndrome-Therapeutic Outcome and Predictors of Response: Real-Life Data From the AIDA Network

Objective: To describe the role of biotechnological therapies in patients with tumor necrosis factor receptor associated periodic syndrome (TRAPS) and to identify any predictor of complete response. Methods: Clinical, laboratory, and therapeutic data from 44 Caucasian TRAPS patients treated with biologic agents were retrospectively collected in 16 Italian tertiary Centers. Results: A total of 55 biological courses with anakinra (n = 26), canakinumab (n = 16), anti-TNF-α agents (n = 10), and tocilizumab (n = 3) were analyzed. A complete response was observed in 41 (74.5%) cases, a partial response in 9 (16.4%) cases and a treatment failure in 5 (9.1%) cases. The frequency of TRAPS exacerbations was 458.2 flare/100 patients-year during the 12 months prior to the start of biologic treatment and 65.7 flare/100 patients-years during the first 12 months of therapy (p < 0.0001). The median duration of attacks was 5.00 (IQR = 10.50) days at the start of biologics and 1.00 (IQR = 0.00) days at the 12-month assessment (p < 0.0001). Likewise, a significant reduction was observed in the Autoinflammatory Disease Activity Index during the study period (p < 0.0001). A significant corticosteroid sparing effect was observed as early as the first 12 months of treatment both in the number of patients requiring corticosteroids (p = 0.025) and in the dosages employed (p < 0.0001). A significant reduction was identified in the erythrocyte sedimentation rate (p < 0.0001), C reactive protein (p < 0.0001), serum amyloid A (p < 0.0001), and in the 24-h proteinuria dosage during follow-up (p = 0.001). A relapsing-remitting disease course (OR = 0.027, C.I. 0.001-0.841, p = 0.040) and the frequency of relapses at the start of biologics (OR = 0.363, C.I. 0.301-0.953, p = 0.034) were significantly associated with a complete response. No serious adverse events were observed. Conclusions: Treatment with biologic agents is highly effective in controlling clinical and laboratory TRAPS manifestations. Patients with a relapsing-remitting course and a lower frequency of flares at the start of treatment show more likely a complete response to biologic agents.

Lymphadenopathy at the crossroad between immunodeficiency and autoinflammation: An intriguing challenge

Lymphadenopathies can be part of the clinical spectrum of several primary immunodeficiencies, including diseases with immune dysregulation and autoinflammatory disorders, as the clinical expression of benign polyclonal lymphoproliferation, granulomatous disease or lymphoid malignancy. Lymphadenopathy poses a significant diagnostic dilemma when it represents the first sign of a disorder of the immune system, leading to a consequently delayed diagnosis. Additionally, the finding of lymphadenopathy in a patient with diagnosed immunodeficiency raises the question of the differential diagnosis between benign lymphoproliferation and malignancies. Lymphadenopathies are evidenced in 15–20% of the patients with common variable immunodeficiency, while in other antibody deficiencies the prevalence is lower. They are also evidenced in different combined immunodeficiency disorders, including Omenn syndrome, which presents in the first months of life. Interestingly, in the activated phosphoinositide 3‐kinase delta syndrome, autoimmune lymphoproliferative syndrome, Epstein–Barr virus (EBV)‐related lymphoproliferative disorders and regulatory T cell disorders, lymphadenopathy is one of the leading signs of the entire clinical picture. Among autoinflammatory diseases, the highest prevalence of lymphadenopathies is observed in patients with periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) and hyper‐immunoglobulin (Ig)D syndrome. The mechanisms underlying lymphoproliferation in the different disorders of the immune system are multiple and not completely elucidated. The advances in genetic techniques provide the opportunity of identifying new monogenic disorders, allowing genotype–phenotype correlations to be made and to provide adequate follow‐up and treatment in the single diseases. In this work, we provide an overview of the most relevant immune disorders associated with lymphadenopathy, focusing on their diagnostic and prognostic implications.

RIPK1-Associated Inborn Errors of Innate Immunity

RIPK1 (receptor-interacting serine/threonine-protein kinase 1) is a key molecule for mediating apoptosis, necroptosis, and inflammatory pathways downstream of death receptors (DRs) and pattern recognition receptors (PRRs). RIPK1 functions are regulated by multiple post-translational modifications (PTMs), including ubiquitination, phosphorylation, and the caspase-8-mediated cleavage. Dysregulation of these modifications leads to an immune deficiency or a hyperinflammatory disease in humans. Over the last decades, numerous studies on the RIPK1 function in model organisms have provided insights into the molecular mechanisms of RIPK1 role in the maintenance of immune homeostasis. However, the physiological role of RIPK1 in the regulation of cell survival and cell death signaling in humans remained elusive. Recently, RIPK1 loss-of-function (LoF) mutations and cleavage-deficient mutations have been identified in humans. This review discusses the molecular pathogenesis of RIPK1-deficiency and cleavage-resistant RIPK1 induced autoinflammatory (CRIA) disorders and summarizes the clinical manifestations of respective diseases to help with the identification of new patients.

Systemic autoinflammatory disease in adults

Systemic autoinflammatory disorders comprise an expanding group of rare conditions. They are mediated by dysfunction of the innate immune system and share a core of phenotypic manifestations including recurrent attacks of fever, cutaneous signs, chest or abdominal pain, lymphadenopathy, vasculopathy, and musculoskeletal symptoms. Diagnosis is often established in childhood, but a growing number of adult patients are being recognized with systemic autoinflammatory disorders, including adult-onset disease. In this review, we provide a concise update on the pathophysiology, clinical presentation, and diagnostic approach of systemic autoinflammatory disorders with an emphasis on the adult patient population. Despite the recent advances in genetic testing, the diagnosis of autoinflammatory disease in adult patients is often based on a thorough knowledge of the clinical phenotype. Becoming acquainted with the clinical features of these rare disorders may assist in developing a high index of suspicion for autoinflammatory disease in patients presenting with unexplained episodes of fever or inflammation.

Tumor Necrosis Factor Receptor-Associated Periodic Syndrome (TRAPS) with a New Pathogenic Variant in TNFRSF1A Gene in a Family of the Adult Male with Renal AA Amyloidosis-Diagnostic and Therapeutic Challenge for Clinicians

Tumor necrosis factor receptor-associated periodic syndrome (TRAPS) belongs to systemic autoinflammatory diseases (AIDs). Many of these syndromes are genetically conditioned and can be inherited. Diagnosis relies on clinical symptoms and should be confirmed by genetic testing. One of the most serious complications is AA amyloidosis. We present the diagnostic route of a 33-year-old male with AA amyloidosis and his children, leading to diagnosis of monogenic autoinflammatory syndrome, confirmed by genetic analysis. A novel variant of the in-frame insertion type in one allele of TNFRSF1A gene was found by whole exome sequencing and confirmed by Sanger sequencing, which allowed a diagnosis of TRAPS. Three-dimensional modeling was used to assess the structural changes introduced into TNFR1 molecule by the insertion. The analysis of the 3D model revealed that accommodation of the 4AA insert induces misalignment of three cysteine bridges (especially the C70-C96 bridge) in the extracellular domain, leading to putatively misfolded and improperly functioning TNFR1. Three of the patient's daughters inherited the same variant of the TNFRSF1A gene and presented TRAPS symptoms. TRAPS is a very rare disease, but in the presence of suggestive symptoms the genetic diagnostic workout should be undertaken. Early diagnosis followed by appropriate clinical management can prevent irreversible complications.

Tumor Necrosis Factor Receptors: Pleiotropic Signaling Complexes and Their Differential Effects

Since its discovery in 1975, TNFα has been a subject of intense study as it plays significant roles in both immunity and cancer. Such attention is well deserved as TNFα is unique in its engagement of pleiotropic signaling via its two receptors: TNFR1 and TNFR2. Extensive research has yielded mechanistic insights into how a single cytokine can provoke a disparate range of cellular responses, from proliferation and survival to apoptosis and necrosis. Understanding the intracellular signaling pathways induced by this single cytokine via its two receptors is key to further revelation of its exact functions in the many disease states and immune responses in which it plays a role. In this review, we describe the signaling complexes formed by TNFR1 and TNFR2 that lead to each potential cellular response, namely, canonical and non-canonical NF-κB activation, apoptosis and necrosis. This is followed by a discussion of data from in vivo mouse and human studies to examine the differential impacts of TNFR1 versus TNFR2 signaling.