Genetics of monogenic autoinflammatory diseases: past successes, future challenges

IL-1 signaling pathway, an important target for inflammation surrounding in myocardial infarction

Acute myocardial infarction is an important cardiovascular disease worldwide. Although the mortality rate of myocardial infarction (MI) has improved dramatically in recent years due to timely treatment, adverse remodeling of the left ventricle continues to affect cardiac function. Various immune cells are involved in this process to induce inflammation and amplification. The infiltration of inflammatory cells in the infarcted myocardium is induced by various cytokines and chemokines, and the recruitment of leukocytes further amplifies the inflammatory response. As an increasing number of clinical anti-inflammatory therapies have achieved significant success in recent years, treating myocardial infarction by targeting inflammation may become a novel therapeutic option. In particular, successful clinical trials of canakinumab have demonstrated the important role of the inflammatory factor interleukin-1 (IL-1) in atherosclerosis. Targeted IL-1 therapy may decrease inflammation levels and improve cardiac function in patients after myocardial infarction. This article reviews the complex series of responses after myocardial infarction, including the involvement of inflammatory cells and the role of cytokines and chemokines, focusing on the progression of the IL-1 family in myocardial infarction as well as the performance of current targeted therapy drugs in experiments.

IL-1 Inhibitors in the Treatment of Familial Mediterranean Fever: Treatment Indications and Clinical Features in a Large Real-World Cohort

Background: The accruing evidence about the efficacy of anti-IL-1 agents in Familial Mediterranean Fever (FMF) patients led to their widespread off-label use. Therefore, identifying precise indications and clinical characteristics of IL-1i-warranting patients are important. This study investigated the clinical characteristics and treatment indications of patients with FMF requiring interleukin 1 inhibition therapy (IL-1i). Methods: Hospital records of FMF patients attending a tertiary care center at the Department of Rheumatology, University of Health Sciences, Basaksehir Cam and Sakura City Hospital were retrospectively analyzed. Data on symptoms and disease manifestations, age of symptom onset, time to diagnosis, MEFV variants, type of treatment, and their indications were collected. Results: Between June 2020 and March 2023, 312 FMF patients were identified. The mean age at the onset of symptoms was 14.0, and the mean time to diagnosis was 11.9 years. In total, 87.1% of patients were receiving colchicine monotherapy, while the remaining 11.8% warranted IL-1i. Clinical symptoms and flare manifestations did not show a significant difference between the two groups. However, patients receiving IL-1i started having symptoms at younger age (11.5 vs. 14.5, p = 0.042) and time to diagnosis was longer (18.2 vs. 11.0, p < 0.01). M694V homozygosity was more common in patients receiving IL-1i. Indications for patients receiving IL-1i were colchicine resistance (8.0%), secondary amyloidosis (5.1%), and colchicine intolerance (2.2%). Conclusions: This study shows that a subset of FMF patients, particularly those with a more severe phenotype with an earlier disease onset and M694V homozygosity, require IL-1i treatment despite the overall good efficacy and tolerability of colchicine, primarily due to colchicine resistance, intolerance, or complications such as amyloidosis.

Adherence to colchicine prophylaxis among patients with familial Mediterranean fever treated with interleukin-1 inhibitors

OBJECTIVE

Interleukin-1 (IL-1) inhibitors are approved for treating familial Mediterranean fever (FMF) that is resistant to colchicine. However, continued concomitant treatment with colchicine is imperative, as it is the only drug proven to prevent secondary amyloidosis. We aimed to compare the adherence to colchicine between patients with colchicine-resistant FMF (crFMF) who were treated with IL-1 inhibitors and patients with colchicine-sensitive FMF (csFMF) who were treated only with colchicine.

METHODS

The databases of Maccabi Health Services, a 2.6-million-member state-mandated health provider in Israel were searched for patients with FMF diagnosis. The medication possession ratio (MPR), calculated from the day of the first colchicine purchase (index date) until the last colchicine purchase was the main outcome measure. Patients with crFMF were matched in a 1:4 ratio to patients with csFMF.

RESULTS

The final cohort included 4526 patients. Of them, 108 (2.4%) were with crFMF, and were matched to 432 with csFMF. The total mean MPR in each of the matched groups was similar (78.9 ± 41.4 and 82.5 ± 80.6, respectively, P = 0.5). Statistically significant differences in MPR were not found between the groups according to age or duration of colchicine use. However, adherence to colchicine was insufficient (MPR<80%) among more than 50% of the patients in both groups.

CONCLUSION

In contrast to initial concerns, adherence to colchicine was similar between patients with crFMF and csFMF. However, in both groups, adherence to colchicine was poor. Education of both caregivers and patients is essential to increase adherence.

Palmitoylation prevents sustained inflammation by limiting NLRP3 inflammasome activation through chaperone-mediated autophagy

As a key component of the inflammasome, NLRP3 is a critical intracellular danger sensor emerging as an important clinical target in inflammatory diseases. However, little is known about the mechanisms that determine the kinetics of NLRP3 inflammasome stability and activity to ensure effective and controllable inflammatory responses. Here, we show that S-palmitoylation acts as a brake to turn NLRP3 inflammasome off. zDHHC12 is identified as the S-acyltransferase for NLRP3 palmitoylation, which promotes its degradation through the chaperone-mediated autophagy pathway. Zdhhc12 deficiency in mice enhances inflammatory symptoms and lethality following alum-induced peritonitis and LPS-induced endotoxic shock. Notably, several disease-associated mutations in NLRP3 are associated with defective palmitoylation, resulting in overt NLRP3 inflammasome activation. Thus, our findings identify zDHHC12 as a repressor of NLRP3 inflammasome activation and uncover a previously unknown regulatory mechanism by which the inflammasome pathway is tightly controlled by the dynamic palmitoylation of NLRP3.

Systematic Review of Safety and Efficacy of IL-1-Targeted Biologics in Treating Immune-Mediated Disorders

Background

The cytokine interleukin (IL)-1 plays a pivotal role in immune-mediated disorders, particularly in autoinflammatory diseases. Targeting this cytokine proved to be efficacious in treating numerous IL-1-mediated pathologies. Currently, three IL-1 blockers are approved, namely anakinra, canakinumab and rilonacept, and two additional ones are expected to receive approval, namely gevokizumab and bermekimab. However, there is no systematic review on the safety and efficacy of these biologics in treating immune-mediated diseases.

Objective

To evaluate safety and efficacy of anakinra, canakinumab, rilonacept, gevokizumab, and bermekimab for the treatment of immune-mediated disorders compared to placebo, standard-of-care treatment or other biologics.

Methods

The PRISMA checklist guided the reporting of the data. We searched the PubMed database between 1 January 1984 and 31 December 2020 focusing on immune-mediated disorders. Our PubMed literature search identified 7363 articles. After screening titles and abstracts for the inclusion and exclusion criteria and assessing full texts, 75 articles were included in a narrative synthesis.

Results

Anakinra was both efficacious and safe in treating cryopyrin-associated periodic syndromes (CAPS), familial Mediterranean fever (FMF), gout, macrophage activation syndrome, recurrent pericarditis, rheumatoid arthritis (RA), and systemic juvenile idiopathic arthritis (sJIA). Conversely, anakinra failed to show efficacy in graft-versus-host disease, Sjögren’s syndrome, and type 1 diabetes mellitus (T1DM). Canakinumab showed efficacy in treating CAPS, FMF, gout, hyper-IgD syndrome, RA, Schnitzler’s syndrome, sJIA, and TNF receptor-associated periodic syndrome. However, use of canakinumab in the treatment of adult-onset Still’s disease and T1DM revealed negative results. Rilonacept was efficacious and safe for the treatment of CAPS, FMF, recurrent pericarditis, and sJIA. Contrarily, Rilonacept did not reach superiority compared to placebo in the treatment of T1DM. Gevokizumab showed mixed results in treating Behçet’s disease-associated uveitis and no benefit when assessed in T1DM. Bermekimab achieved promising results in the treatment of hidradenitis suppurativa.

Conclusions

This systematic review of IL-1-targeting biologics summarizes the current state of research, safety, and clinical efficacy of anakinra, bermekimab, canakinumab, gevokizumab, and rilonacept in treating immune-mediated disorders.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42021228547.

Twists and turns of the genetic story of mevalonate kinase-associated diseases: A review

Mevalonate kinase (MK)-associated diseases encompass a broad spectrum of rare auto-inflammatory conditions, all resulting from pathogenic variants in the mevalonate kinase gene (MVK). Their clinical manifestations are highly variable, ranging from more or less serious systemic disorders, such as hereditary recurrent fevers, to purely localized pathologies such as porokeratosis. The oldest condition identified as linked to this gene is a metabolic disease called mevalonic aciduria, and the most recent is disseminated superficial actinic porokeratosis, a disease limited to the skin. The modes of inheritance of MK-associated diseases also diverge among the different subtypes: recessive for the systemic subtypes and dominant with a post-zygotic somatic genetic alteration for MVK-associated porokeratosis. This review quickly retraces the historical steps that led to the description of the various MK-associated disease phenotypes and to a better understanding of their pathophysiology, then summarizes and compares the different genetic mechanisms involved in this group of disorders, and finally discusses the diverse causes that could underlie this phenotypic heterogeneity.

Mevalonate Kinase-Associated Diseases: Hunting for Phenotype-Genotype Correlation

Mevalonate kinase-associated diseases (MKAD) are caused by pathogenic mutations in the mevalonate kinase gene (MVK) and encompass several phenotypically different rare and hereditary autoinflammatory conditions. The most serious is a recessive systemic metabolic disease called mevalonic aciduria, and the most recently recognized is disseminated superficial actinic porokeratosis, a dominant disease limited to the skin. To evaluate a possible correlation between genotypes and (1) the different MKAD clinical subtypes or (2) the occurrence of severe manifestations, data were reviewed for all patients with MVK variants described in the literature (N = 346), as well as those referred to our center (N = 51). The genotypes including p.(Val377Ile) (homozygous or compound heterozygous) were more frequent in mild systemic forms but were also sometimes encountered with severe disease. We confirmed that amyloidosis was more prevalent in patients compound heterozygous for p.(Ile268Thr) and p.(Val377Ile) than in others and revealed new associations. Patients homozygous for p.(Leu264Phe), p.(Ala334Thr) or compound heterozygous for p.(His20Pro) and p.(Ala334Thr) had increased risk of severe neurological or ocular symptoms. All patients homozygous for p.(Leu264Phe) had a cataract. The variants associated with porokeratosis were relatively specific and more frequently caused a frameshift than in patients with other clinical forms (26% vs. 6%). We provide practical recommendations focusing on phenotype-genotype correlation in MKAD that could be helpful for prophylactic management.

Familial Mediterranean fever-related miR-197-3p targets IL1R1 gene and modulates inflammation in monocytes and synovial fibroblasts

Familial Mediterranean fever (FMF); is an autosomal recessively inherited autoinflammatory disease caused by the mutations in the Mediterranean Fever (MEFV) gene. Recent studies have shown that epigenetic control mechanisms, particularly non-coding RNAs, may play a role in the pathogenesis of autoinflammation. microRNAs (miRNAs) are small non-coding RNAs that play critical roles in regulating host gene expression at the post-transcriptional level. The phenotypic heterogeneity of FMF disease suggests that FMF may not be a monogenic disease, suggesting that epigenetic factors may affect phenotypic presentation. Here we examined the potential anti-inflammatory effect of miR-197-3p, which is a differentially expressed miRNA in FMF patients, by using inflammation related functional assays. We monitored gene expression levels of important cytokines, as well as performed functional studies on IL-1β secretion, caspase-1 activation, apoptosis assay, and cell migration assay. These experiments were used to evaluate the different stages of inflammation following pre-miR-197 transfection. Anti-miR-197 transfections were performed to test the opposite effect. 3′UTR luciferase activity assay was used for target gene studies. Our results obtained by inflammation-related functional assays demonstrated an anti-inflammatory effect of miR-197-3p in different cell types (synovial fibroblasts, monocytes, macrophages). 3′UTR luciferase activity assay showed that miR-197-3p directly binds to the interleukin-1beta (IL-1β) receptor, type I (IL1R1) gene, which is one of the key molecules of the inflammatory pathways. This study may contribute to understand the role of miR-197-3p in autoinflammation process. Defining the critical miRNAs may guide the medical community in a more personalized medicine in autoinflammatory diseases.

Distinct Roles of IL-1β and IL-18 in NLRC4-Induced Autoinflammation

The NLRC4 inflammasome assembles in response to detection of bacterial invasion, and NLRC4 activation leads to the production of IL-1β and IL-18 together with pyroptosis-mediated cell death. Missense activating mutations in NLRC4 cause autoinflammatory disorders whose symptoms are distinctly dependent on the site of mutation and other aspects of the genetic background. To determine the involvement of IL-1β and IL-18 in the inflammation induced by NLRC4 mutation, we depleted IL-1β, IL-18, or both cytokines in Nlrc4-transgenic mice in which mutant Nlrc4 is expressed under the MHC class II promoter (Nlrc4-H443P-Tg mice). The deletion of the Il1b or Il18 gene in Nlrc4-H443P-Tg mice reduced the neutrophil numbers in the spleen, and mice with deletion of both genes had an equivalent number of neutrophils compared to wild-type mice. Deletion of Il1b ameliorated but did not eliminate bone marrow hyperplasia, while mice deficient in Il18 showed no bone marrow hyperplasia. In contrast, tail bone deformity remained in the presence of Il18 deficiency, but Il1b deficiency completely abolished bone deformity. The decreased bone density in Nlrc4-H443P-Tg mice was counteracted by Il1b but not Il18 deficiency. Our results demonstrate the distinct effects of IL-1β and IL-18 on NLRC4-induced inflammation among tissues, which suggests that blockers for each cytokine should be utilized depending on the site of inflammation.

Excessive deubiquitination of NLRP3-R779C variant contributes to very-early-onset inflammatory bowel disease development

BACKGROUND

Very-early-onset inflammatory bowel disease (VEOIBD) is a chronic inflammatory disease of the gastrointestinal tract occurring during infancy or early childhood. NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome has emerged as a crucial regulator of intestinal homeostasis; however, whether NLRP3 variants may modify VEOIBD risk is unknown.

OBJECTIVE

We sought to investigate whether and how a rare NLRP3 variant, found in 3 patients with gastrointestinal symptoms, contributes to VEOIBD development.

METHODS

Whole-exome sequencing and bioinformatic analysis were performed to screen disease-associated NLRP3 variants from a cohort of children with VEOIBD. Inflammasome activation was determined in reconstituted HEK293T human embryonic kidney cells with NLRP3 inflammasome components, doxycycline-inducible NLRP3 macrophages, as well as PBMCs and biopsies from patients with NLRP3 variants. Pathogenesis of the variants was determined using a dextran sulfate sodium-induced acute colitis model.

RESULTS

We identified a dominant gain-of-function missense variant of NLRP3, encoded by rs772009059 (R779C), in 3 patients with gastrointestinal symptoms. Functional analysis revealed that R779C increased NLRP3 inflammasome activation and pyroptosis in macrophages. This was mediated by enhanced deubiquitination of NLRP3 via binding with deubiquitinases BRCC3 and JOSD2, which are highly expressed in myeloid cells. In a dextran sulfate sodium-induced acute colitis model, NLRP3-R779C in hematopoietic cells resulted in more severe colitis, which can be ameliorated via knockdown of BRCC3 or JOSD2.

CONCLUSIONS

BRCC3 and JOSD2 mediate NLRP3-R779C deubiquitination, which promotes NLRP3 inflammasome activation and the risk of developing VEOIBD.

Autoinflammatory Diseases in Childhood

Autoinflammatory diseases are characterized by recurrent fevers and clinical findings of impaired natural immunity and can involve various organ systems. The concept of autoinflammatory disease emerged after the definition of familial Mediterranean fever and tumor necrosis factor receptor-associated periodic syndrome. This new disease group was considered to differ from the standard concept of autoimmune diseases, which is relatively better known in terms of basic features, such as defects in innate immunity and the absence of antibodies. A better understanding has been achieved regarding the genetic and pathogenetic mechanisms of this relatively new disease group over the past 20 years since they were first diagnosed, which have led to some changes in the concept of autoinflammatory diseases. The recent definition classifies autoinflammatory disease to be a wide range of diseases with different clinical features, mainly accompanied by changes in innate immune and rarely in humoral immunity. The spectrum of autoinflammatory diseases is rapidly expanding owing to recent developments in molecular sciences and genetics. This review article discusses the clinical features, classification criteria, treatment options, and long-term prognosis of periodic fever, aphthous stomatitis, pharyngitis, adenitis syndrome, and other common autoinflammatory diseases in the light of current literature.

RIP-roaring inflammation: RIPK1 and RIPK3 driven NLRP3 inflammasome activation and autoinflammatory disease

Autoinflammatory syndromes comprise a spectrum of clinical disorders characterised by recurrent, inflammatory episodes, many of which result from the release of the pro-inflammatory cytokine, interleukin-1β (IL-1β). Inflammation and programmed cell death are tightly linked, and lytic forms of cell death, such as necroptosis and pyroptosis, are considered to be inflammatory due to the release of damage-associated molecular patterns (DAMPs). In contrast, apoptosis is traditionally regarded as immunologically silent. Recent studies, however, have uncovered a high degree of crosstalk between cell death and inflammatory signalling pathways, and effectively consolidated them into one interconnected network that converges on NLRP3 inflammasome-mediated activation of IL-1β. The receptor-interacting protein kinases (RIPK) 1 and 3 are central to this network, as highlighted by the fact that mutations in genes encoding repressors of RIPK1 and/or RIPK3 activity can lead to heightened inflammation, particularly via NLRP3 inflammasome activation. In this review, we give an overview of extrinsic cell death and inflammatory signalling pathways, and then highlight the growing number of autoinflammatory diseases that are associated with aberrant cell death and inflammasome activation.

The NLRP1 Inflammasome in Human Skin and Beyond

Inflammasomes represent a group of protein complexes that contribute to host defense against pathogens and repair processes upon the induction of inflammation. However, aberrant and chronic inflammasome activation underlies the pathology of numerous common inflammatory diseases. Inflammasome assembly causes activation of the protease caspase-1 which in turn activates proinflammatory cytokines and induces a lytic type of cell death termed pyroptosis. Although NLRP1 (NACHT, leucine-rich repeat and pyrin domain containing 1) was the first inflammasome sensor, described almost 20 years ago, the molecular mechanisms underlying its activation and the resulting downstream events are incompletely understood. This is partially a consequence of the poor conservation of the NLRP1 pathway between human and mice. Moreover, recent evidence demonstrates a complex and multi-stage mechanism of NLRP1 inflammasome activation. In contrast to other inflammasome sensors, NLRP1 possesses protease activity required for proteolytic self-cleavage and activation mediated by the function-to-find domain (FIIND). CARD8 is a second FIIND protein and is expressed in humans but not in mice. In immune cells and AML (acute myeloid leukemia) cells, the anti-cancer drug talabostat induces CARD8 activation and causes caspase-1-dependent pyroptosis. In contrast, in human keratinocytes talabostat induces NLRP1 activation and massive proinflammatory cytokine activation. NLRP1 is regarded as the principal inflammasome sensor in human keratinocytes and UVB radiation induces its activation, which is believed to underlie the induction of sunburn. Moreover, gain-of-function mutations of NLRP1 cause inflammatory skin syndromes and a predisposition for the development of skin cancer. SNPs (single nucleotide polymorphisms) of NLRP1 are associated with several (auto)inflammatory diseases with a major skin phenotype, such as psoriasis or vitiligo. Here, we summarize knowledge about NLRP1 with emphasis on its role in human keratinocytes and skin. Due to its accessibility, pharmacological targeting of NLRP1 activation in epidermal keratinocytes represents a promising strategy for the treatment of the numerous patients suffering from NLRP1-dependent inflammatory skin conditions and cancer.

Multiple roles of caspase-8 in cell death, inflammation, and innate immunity

Caspase-8 is an apical caspase involved in the programmed form of cell death called apoptosis that is critically important for mammalian development and immunity. Apoptosis was historically described as immunologically silent in contrast to other types of programmed cell death such as necroptosis or pyroptosis. Recent reports suggest considerable crosstalk between these different forms of cell death. It is becoming increasingly clear that caspase-8 has many non-apoptotic roles, participating in multiple processes including regulation of necroptosis (mediated by receptor-interacting serine/threonine kinases, RIPK1-RIPK3), inflammatory cytokine expression, inflammasome activation, and cleavage of IL-1β and gasdermin D, and protection against shock and microbial infection. In this review, we discuss the involvement of caspase-8 in cell death and inflammation and highlight its role in innate immune responses and in the relationship between different forms of cell death. Caspase-8 is one of the central components in this type of crosstalk.

Consensus protocols for the diagnosis and management of the hereditary autoinflammatory syndromes CAPS, TRAPS and MKD/HIDS: a German PRO-KIND initiative

BACKGROUND

Rare autoinflammatory diseases (AIDs) including Cryopyrin-Associated Periodic Syndrome (CAPS), Tumor Necrosis Receptor-Associated Periodic Syndrome (TRAPS) and Mevalonate Kinase Deficiency Syndrome (MKD)/ Hyper-IgD Syndrome (HIDS) are genetically defined and characterized by recurrent fever episodes and inflammatory organ manifestations. Early diagnosis and early start of effective therapies control the inflammation and prevent organ damage. The PRO-KIND initiative of the German Society of Pediatric Rheumatology (GKJR) aims to harmonize the diagnosis and management of children with rheumatic diseases nationally. The task of the PRO-KIND CAPS/TRAPS/MKD/HIDS working group was to develop evidence-based, consensus diagnosis and management protocols including the first AID treat-to-target strategies.

METHODS

The national CAPS/TRAPS/MKD/HIDS expert working group was established, defined its aims and conducted a comprehensive literature review synthesising the recent (2013 to 2018) published evidence including all available recommendations for diagnosis and management. General and disease-specific statements were anchored in the 2015 SHARE recommendations. An iterative expert review process discussed, adapted and refined these statements. Ultimately the GKJR membership vetted the proposed consensus statements, agreement of 80% was mandatory for inclusion. The approved statements were integrated into three disease specific consensus treatment plans (CTPs). These were developed to enable the implementation of evidence-based, standardized care into clinical practice.

RESULTS

The CAPS/TRAPS/MKD/HIDS expert working group of 12 German and Austrian paediatric rheumatologists completed the evidence synthesis and modified a total of 38 statements based on the SHARE recommendation framework. In iterative reviews 36 reached the mandatory agreement threshold of 80% in the final GKJR member survey. These included 9 overarching principles and 27 disease-specific statements (7 for CAPS, 11 TRAPS, 9 MKD/HIDS). A diagnostic algorithm was established based on the synthesized evidence. Statements were integrated into diagnosis- and disease activity specific treat-to-target CTPs for CAPS, TRAPS and MKD/HIDS.

CONCLUSIONS

The PRO-KIND CAPS/TRAPS/MKD/HIDS working group established the first evidence-based, actionable treat-to-target consensus treatment plans for three rare hereditary autoinflammatory diseases. These provide a path to a rapid evaluation, effective control of disease activity and tailored adjustment of therapies. Their implementation will decrease variation in care and optimize health outcomes for children with AID.

Inflammasomes in the pathophysiology of autoinflammatory syndromes

Inflammasomes are a specialized group of intracellular sensors that are key components of the host innate immune system. Autoinflammatory diseases are disorders of the innate immune system that are characterized by recurrent inflammation and serious complications. Dysregulation of the inflammasome is associated with the onset and progression of several autoinflammatory and autoimmune diseases, including cryopyrin-associated periodic fever syndrome, familial Mediterranean fever, rheumatoid arthritis, and systemic lupus erythematosus. In this review, we discuss the involvement of various inflammasome components in the regulation of autoinflammatory disorders and describe the manifestations of these autoinflammatory diseases caused by inflammasome activation.

HSC70 regulates cold-induced caspase-1 hyperactivation by an autoinflammation-causing mutant of cytoplasmic immune receptor NLRC4

NLRC4 [nucleotide-binding domain and leucine-rich repeat (NLR) family, caspase recruitment domain (CARD) containing 4] is an innate immune receptor, which, upon detection of certain pathogens or internal distress signals, initiates caspase-1-mediated interleukin-1β maturation and an inflammatory response. A gain-of-function mutation, H443P in NLRC4, causes familial cold autoinflammatory syndrome (FCAS) characterized by cold-induced hyperactivation of caspase-1, enhanced interleukin-1β maturation, and inflammation. Although the H443P mutant shows constitutive activity, the mechanism involved in hyperactivation of caspase-1 by NLRC4-H443P upon exposure of cells to lower temperature is not known. Here, we show that heat shock cognate protein 70 (HSC70) complexes with NLRC4 and negatively regulates caspase-1 activation by NLRC4-H443P in human cells. Compared with NLRC4, the structurally altered NLRC4-H443P shows enhanced interaction with HSC70. Nucleotide binding- and leucine-rich repeat domains of NLRC4, but not its CARD, can engage in complex formation with HSC70. Knockdown of HSC70 enhances apoptosis-associated speck-like protein containing a CARD (ASC)-speck formation and caspase-1 activation by NLRC4-H443P. Exposure to subnormal temperature results in reduced interaction of NLRC4-H443P with HSC70, and an increase in its ability to form ASC specks and activate caspase-1. Unlike the NLRC4-H443P mutant, another constitutively active mutant (NLRC4-V341A) associated with autoinflammatory diseases, but not FCAS, showed neither enhanced interaction with HSC70 nor an increase in inflammasome formation upon exposure to subnormal temperature. Our results identify HSC70 as a negative regulator of caspase-1 activation by the temperature-sensitive NLRC4-H443P mutant. We also show that low-temperature-induced hyperactivation of caspase-1 by NLRC4-H443P is due to loss of inhibition by HSC70.

Dysregulation of immunoproteasomes in autoinflammatory syndromes

Immunoproteasomes degrade ubiquitin-coupled proteins and play a role in creating peptides for presentation by MHC class I proteins. Studies of gene-deficient mice, in which each immunoproteasomal subunit was affected, have demonstrated that dysfunction of immunoproteasomes leads to immunodeficiency, i.e. reduced expression of MHC class I and attenuation of CD8 T-cell responses. Recent studies, however, have uncovered a new type of autoinflammatory syndrome characterized by fever, nodular erythema and progressive partial lipodystrophy that is caused by genetic mutations in immunoproteasome subunits. These mutations disturbed the assembly of immunoproteasomes, which led to reduced proteasomal activity and thus accumulation of ubiquitin-coupled proteins. Those findings suggest that immunoproteasomes function as anti-inflammatory machinery in humans. The discovery of a new type of autoinflammatory syndrome caused by dysregulated immunoproteasomes provides novel insights into the important roles of immunoproteasomes in inflammation as well as the spectrum of autoinflammatory diseases.

SUMO-mediated regulation of NLRP3 modulates inflammasome activity

The NLRP3 inflammasome responds to infection and tissue damage, and rapidly escalates the intensity of inflammation by activating interleukin (IL)-1β, IL-18 and cell death by pyroptosis. How the NLRP3 inflammasome is negatively regulated is poorly understood. Here we show that NLRP3 inflammasome activation is suppressed by sumoylation. NLRP3 is sumoylated by the SUMO E3-ligase MAPL, and stimulation-dependent NLRP3 desumoylation by the SUMO-specific proteases SENP6 and SENP7 promotes NLRP3 activation. Defective NLRP3 sumoylation, either by NLRP3 mutation of SUMO acceptor lysines or depletion of MAPL, results in enhanced caspase-1 activation and IL-1β release. Conversely, depletion of SENP7 suppresses NLRP3-dependent ASC oligomerisation, caspase-1 activation and IL-1β release. These data indicate that sumoylation of NLRP3 restrains inflammasome activation, and identify SUMO proteases as potential drug targets for the treatment of inflammatory diseases.

Eating Disorders, Autoimmune, and Autoinflammatory Disease

OBJECTIVES

Identifying factors associated with risk for eating disorders is important for clarifying etiology and for enhancing early detection of eating disorders in primary care. We hypothesized that autoimmune and autoinflammatory diseases would be associated with eating disorders in children and adolescents and that family history of these illnesses would be associated with eating disorders in probands.

METHODS

In this large, nationwide, population-based cohort study of all children and adolescents born in Denmark between 1989 and 2006 and managed until 2012, Danish medical registers captured all inpatient and outpatient diagnoses of eating disorders and autoimmune and autoinflammatory diseases. The study population included 930 977 individuals (48.7% girls). Cox proportional hazards regression models and logistic regression were applied to evaluate associations.

RESULTS

We found significantly higher hazards of eating disorders for children and adolescents with autoimmune or autoinflammatory diseases: 36% higher hazard for anorexia nervosa, 73% for bulimia nervosa, and 72% for an eating disorder not otherwise specified. The association was particularly strong in boys. Parental autoimmune or autoinflammatory disease history was associated with significantly increased odds for anorexia nervosa (odds ratio [OR] = 1.13, confidence interval [CI] = 1.01-1.25), bulimia nervosa (OR = 1.29; CI = 1.08-1.55) and for an eating disorder not otherwise specified (OR = 1.27; CI = 1.13-1.44).

CONCLUSIONS

Autoimmune and autoinflammatory diseases are associated with increased risk for eating disorders. Ultimately, understanding the role of immune system disturbance for the etiology and pathogenesis of eating disorders could point toward novel treatment targets.

Novel NLRC4 Mutation Causes a Syndrome of Perinatal Autoinflammation With Hemophagocytic Lymphohistiocytosis, Hepatosplenomegaly, Fetal Thrombotic Vasculopathy, and Congenital Anemia and Ascites

Autoinflammatory diseases are caused by pathologic activation of the innate immune system. Primary hemophagocytic lymphohistiocytosis (HLH) is an aggressive syndrome of excessive immune activation caused by monogenic mutations resulting in cytotoxic cell defects and subsequent failure to eliminate activated macrophages. Secondary HLH is often diagnosed in cases without a known Mendelian inheritance. However, some cases of "secondary" HLH have been shown to harbor mutations with partial dysfunction of the cytotoxic system. Recently, macrophage intrinsic abnormalities caused by NLRC4 inflammasome mutations have been linked to autoinflammation and recurrent macrophage activation syndromes resembling a primary HLH. We report a case of a former 28-week preterm infant with congenital anemia, ascites, and a heavy edematous placenta with fetal thrombotic vasculopathy, who developed hepatosplenomegaly and unexplained systemic inflammation with laboratory features of HLH in the early postnatal course and died at 2 months of age. Postmortem examination confirmed the hepatosplenomegaly with marked sinusoidal hemophagocytosis, along with striking hemophagocytosis in the bone marrow and lymph nodes. There was extensive acute and chronic ischemic bowel disease with matted bowel loops, fibrous adhesions, and patchy necrotizing enterocolitis features. Whole exome sequencing analysis demonstrated a novel mosaic heterozygous NLRC4 512 C> T (p.Ser171Phe) de novo mutation predicated to cause a dominant, gain-of-function mutation resulting in a constitutively active protein. The assembly of NLRC4-containing inflammasomes via an induced self-propagation mechanism likely enables a perpetuating process of systemic macrophage activation, presumed to be initiated in utero in this patient.

Mechanism-Based Strategies for the Management of Autoimmunity and Immune Dysregulation in Primary Immunodeficiencies

A broad spectrum of autoimmunity is now well described in patients with primary immunodeficiencies (PIDs). Management of autoimmune disease in the background of PID is particularly challenging given the seemingly discordant goals of immune support and immune suppression. Our growing ability to define the molecular underpinnings of immune dysregulation has facilitated novel targeted therapeutics. This review focuses on mechanism-based treatment strategies for the most common autoimmune and inflammatory complications of PID including autoimmune cytopenias, rheumatologic disease, and gastrointestinal disease. We aim to provide guidance regarding the rational use of these agents in the complex PID patient population.

Genomics and epigenomics in rheumatic diseases: what do they provide in terms of diagnosis and disease management?

Most rheumatic diseases are complex or multifactorial entities with pathogeneses that interact with both multiple genetic factors and a high number of diverse environmental factors. Knowledge of the human genome sequence and its diversity among populations has provided a crucial step forward in our understanding of genetic diseases, identifying many genetic loci or genes associated with diverse phenotypes. In general, susceptibility to autoimmunity is associated with multiple risk factors, but the mechanism of the environmental component influence is poorly understood. Studies in twins have demonstrated that genetics do not explain the totality of the pathogenesis of rheumatic diseases. One method of modulating gene expression through environmental effects is via epigenetic modifications. These techniques open a new field for identifying useful new biomarkers and therapeutic targets. In this context, the development of "-omics" techniques is an opportunity to progress in our knowledge of complex diseases, impacting the discovery of new potential biomarkers suitable for their introduction into clinical practice. In this review, we focus on the recent advances in the fields of genomics and epigenomics in rheumatic diseases and their potential to be useful for the diagnosis, follow-up, and treatment of these diseases. The ultimate aim of genomic studies in any human disease is to understand its pathogenesis, thereby enabling the prediction of the evolution of the disease to establish new treatments and address the development of personalized therapies.

Small molecules to the rescue: Inhibition of cytokine signaling in immune-mediated diseases

Cytokines are small, secreted proteins associated with the maintenance of immune homeostasis but also implicated with the pathogenesis of several autoimmune and inflammatory diseases. Biologic agents blocking cytokines or their receptors have revolutionized the treatment of such pathologies. Nonetheless, some patients fail to respond to these drugs or do not achieve complete remission. The signal transduction originating from membrane-bound cytokine receptors is an intricate network of events that lead to gene expression and ultimately regulate cellular functionality. Our understanding of the intracellular actions that molecules such as interleukins, interferons (IFNs) and tumor necrosis factor (TNF) set into motion has greatly increased in the past few years, making it possible to interfere with cytokines' signaling cascades. The Janus kinase (JAK)/signal transducer and activator of transcription (STAT), the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB), the mitogen activated protein kinase (MAPK) and the Phosphatidylinositol-3'-kinases (PI3K) pathways have all been intensively studied and key steps as well as molecules have been identified. These research efforts have led to the development of a new generation of small molecule inhibitors. Drugs capable of blocking JAK enzymatic activity or interfering with the proteasome-mediated degradation of intermediates in the NF-kB pathway have already entered the clinical arena confirming the validity of this approach. In this review, we have recapitulated the biochemical events downstream of cytokine receptors and discussed some of the drugs which have already been successfully utilized in the clinic. Moreover, we have highlighted some of the new molecules that are currently being developed for the treatment of immune-mediated pathologies and malignancies.

The challenge of autoinflammatory syndromes: with an emphasis on hyper-IgD syndrome

Autoinflammatory syndromes are disorders with an exaggerated inflammatory response, mostly in the absence of an appropriate trigger. Prototypic autoinflammatory syndromes are FMF, hyper-IgD syndrome (also known as mevalonate kinase deficiency), TNF receptor-associated periodic syndrome and cryopyrin-associated periodic syndrome. The clinical phenotypes partly overlap (with fever and acute phase response), but also differ between the various syndromes (e.g. regarding fever pattern, episodic vs chronic inflammation and accompanying clinical signs). In recent years, the genetic basis of quite a number of these relatively rare and mostly hereditary disorders has been elucidated. These genetic defects lead to either enhanced production of inflammatory mediators or to a lack of inhibition of these components of the innate immune system. Among these dysregulated inflammatory mediators, the pro-inflammatory cytokine IL-1β stands out. Hence, targeted treatment with blockers of IL-1 action, such as recombinant IL-1 receptor antagonist (IL-1Ra, anakinra) and mAb against IL-1β has met with impressive clinical results. In this article, hyper-IgD syndrome is discussed in more detail, based on 30 years of experience with this syndrome.

When to Suspect Autoinflammatory/Recurrent Fever Syndromes

Autoinflammatory disorders are disorders characterized by rash, arthritis, fever, and systemic inflammation. These disorders are caused by mutations in genes important in innate immune system sensors. This review highlights the workup of an individual with recurrent episodes of inflammation, features of these disorders, the genetic defects that cause these disorders, and the specific treatments available.

Caspase-8: not so silently deadly

Apoptosis is a caspase-dependent programmed form of cell death, which is commonly believed to be an immunologically silent process, required for mammalian development and maintenance of cellular homoeostasis. In contrast, lytic forms of cell death, such as RIPK3- and MLKL-driven necroptosis, and caspase-1/11-dependent pyroptosis, are postulated to be inflammatory via the release of damage associated molecular patterns (DAMPs). Recently, the function of apoptotic caspase-8 has been extended to the negative regulation of necroptosis, the cleavage of inflammatory interleukin-1β (IL-1β) to its mature bioactive form, either directly or via the NLRP3 inflammasome, and the regulation of cytokine transcriptional responses. In view of these recent advances, human autoinflammatory diseases that are caused by mutations in cell death regulatory machinery are now associated with inappropriate inflammasome activation. In this review, we discuss the emerging crosstalk between cell death and innate immune cell inflammatory signalling, particularly focusing on novel non-apoptotic functions of caspase-8. We also highlight the growing number of autoinflammatory diseases that are associated with enhanced inflammasome function.

Familial Mediterranean fever presenting as fever of unknown origin in Korea

Familial Mediterranean fever (FMF) is the most common Mendelian autoinflammatory disease, characterized by uncontrolled activation of the innate immune system that manifests as recurrent brief fever and polyserositis (e.g., peritonitis, pleuritic, and arthritis). FMF is caused by autosomal recessive mutations of the Mediterranean fever gene, MEFV which encodes the pyrin protein. Although FMF predominantly affects people from Mediterranean and Middle Eastern ethnic origins, 3 cases of FMF have been reported in Korea since 2012. We report another case of FMF in Korea in which the patient presented with a month-long fever without serositis. After treatment with colchicine was initiated, the patient’s symptoms quickly subsided. The response to colchicine was helpful for diagnosis. We compare the FMF genotypes in Korea with in other countries. Studying FMF cases in Korea will help establish the best MEFV exons to use for screening and diagnosis of Korean FMF.

AP1S3 Mutations Cause Skin Autoinflammation by Disrupting Keratinocyte Autophagy and Up-Regulating IL-36 Production

Prominent skin involvement is a defining characteristic of autoinflammatory disorders caused by abnormal IL-1 signaling. However, the pathways and cell types that drive cutaneous autoinflammatory features remain poorly understood. We sought to address this issue by investigating the pathogenesis of pustular psoriasis, a model of autoinflammatory disorders with predominant cutaneous manifestations. We specifically characterized the impact of mutations affecting AP1S3, a disease gene previously identified by our group and validated here in a newly ascertained patient resource. We first showed that AP1S3 expression is distinctively elevated in keratinocytes. Because AP1S3 encodes a protein implicated in autophagosome formation, we next investigated the effects of gene silencing on this pathway. We found that AP1S3 knockout disrupts keratinocyte autophagy, causing abnormal accumulation of p62, an adaptor protein mediating NF-κB activation. We showed that as a consequence, AP1S3-deficient cells up-regulate IL-1 signaling and overexpress IL-36α, a cytokine that is emerging as an important mediator of skin inflammation. These abnormal immune profiles were recapitulated by pharmacological inhibition of autophagy and verified in patient keratinocytes, where they were reversed by IL-36 blockade. These findings show that keratinocytes play a key role in skin autoinflammation and identify autophagy modulation of IL-36 signaling as a therapeutic target.

Early Onset of Periodic Fever Syndrome in a Patient Carrying Both Tumor Necrosis Factor Receptor Superfamily 1A and Mediterranean Fever Mutations

In this article, we report a nine-month-old male patient with a history of three unexplained, prolonged attacks of high fever, including one in the neonatal period, accompanied by an erythematosus, migratory rash. There was no family history that might have suggested a hereditary periodic fever syndrome, but the overall clinical picture was in accordance with tumor necrosis factor receptor-associated disease. Genetic analysis revealed two heterozygous mutations: C30Y in the tumor necrosis factor receptor superfamily 1A gene and K695R in the Mediterranean fever gene. This case shows that diagnosis of an autoinflammatory syndrome should be considered even in the youngest infants with incomplete presentation and no family history of recurrent fever.

Dysfunctional immunoproteasomes in autoinflammatory diseases

Recent progress in DNA sequencing technology has made it possible to identify specific genetic mutations in familial disorders. For example, autoinflammatory syndromes are caused by mutations in gene coding for immunoproteasomes. These diseases include Japanese autoinflammatory syndrome with lipodystrophy, Nakajo-Nishimura syndrome, joint contractures, muscular atrophy, microcytic anemia, panniculitis-associated lipodystrophy syndrome, and chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature syndrome. Causal mutations of these syndromes are present in gene coding for subunits of the immunoproteasome. Importantly, a genetically modified mouse that lacks the catalytic subunit of immunoproteasomes does not always develop an autoinflammatory syndrome. Analysis of causal gene mutations, assessment of patients’ phenotypic changes, and appropriate animal models will be indispensable for clarifying the underlying mechanisms responsible for the development of autoinflammatory syndromes and establishing curative approaches.

Identification of novel mutations in CD2BP1 gene in clinically proven rheumatoid arthritis patients of south India

Pyogenic Arthritis, Pyoderma gangrenosum, and Acne (PAPA syndrome) is a rare autosomal dominant, auto-inflammatory disease that affects joints and skin. The disease results due to mutations in the cluster of differentiation 2 binding protein 1 (CD2BP1) gene on chromosome 15q24.3. Rheumatoid arthritis (RA) is a common, genetically complex disease that affects the joints with occasional skin manifestations. Studies related to the pathophysiology of inflammation in these two disorders show a certain degree of overlap at genetic level. The present study was done to confirm the existence of such a genetic overlap between PAPA syndrome and RA in south Indian population. In the present study 100 patients who were clinically diagnosed rheumatoid arthritis and 100 apparently healthy controls were chosen and the 15 exons of CD2BP1 gene were PCR-amplified and sequenced. The sequence analysis showed that in exon 3 thirty eight patients revealed presence of novel heterozygous missense mutations p.Glu51Asp, p.Leu57Arg and p.Ala64Thr. In exons 6, 10 and 14 eight patients showed 44 novel missense mutations and two patients showed novel frame shift mutations p.(Met123_Leu416delinsThr) and p.(Thr337Profs*52) leading to truncated protein formation. Such mutations were not seen in controls. Further, the in silico analysis revealed the mutant CD2BP1 structure showed deletion of Cdc15 and SH3 domains when superimposed with the wild type CD2BP1 structure with variable RMSD values. Therefore, these structural variations in CD2BP1 gene due to the mutations could be one of the strongest reasons to demonstrate the involvement of these gene variations in the patients with rheumatoid arthritis.

Familial Mediterranean fever: current perspectives

Familial Mediterranean fever (FMF) is the most frequent monogenic autoinflammatory disease, and it is characterized by recurrent attacks of fever and polyserositis. The disease is associated with mutations in the MEFV gene encoding pyrin, which causes exaggerated inflammatory response through uncontrolled production of interleukin 1. The major long-term complication of FMF is amyloidosis. Colchicine remains the principle therapy, and the aim of treatment is to prevent acute attacks and the consequences of chronic inflammation. With the evolution in the concepts about the etiopathogenesis and genetics of the disease, we have understood that FMF is more complicated than an ordinary autosomal recessive monogenic disorder. Recently, recommendation sets have been generated for interpretation of genetic testing and genetic diagnosis of FMF. Here, we have reviewed the current perspectives in FMF in light of recent recommendations.

Genomic architecture of inflammatory bowel disease in five families with multiple affected individuals

Currently, the best clinical predictor for inflammatory bowel disease (IBD) is family history. Over 163 sequence variants have been associated with IBD in genome-wide association studies, but they have weak effects and explain only a fraction of the observed heritability. It is expected that additional variants contribute to the genomic architecture of IBD, possibly including rare variants with effect sizes larger than the identified common variants. Here we applied a family study design and sequenced 38 individuals from five families, under the hypothesis that families with multiple IBD-affected individuals harbor one or more risk variants that (i) are shared among affected family members, (ii) are rare and (iii) have substantial effect on disease development. Our analysis revealed not only novel candidate risk variants but also high polygenic risk scores for common known risk variants in four out of the five families. Functional analysis of our top novel variant in the remaining family, a rare missense mutation in the ubiquitin ligase TRIM11, suggests that it leads to increased nuclear factor of kappa light chain enhancer in B-cells (NF-κB) signaling. We conclude that an accumulation of common weak-effect variants accounts for the high incidence of IBD in most, but not all families we analyzed and that a family study design can identify novel rare variants conferring risk for IBD with potentially large effect size, such as the TRIM11 p.H414Y mutation.

Practice parameter for the diagnosis and management of primary immunodeficiency

The American Academy of Allergy, Asthma & Immunology (AAAAI) and the American College of Allergy, Asthma & Immunology (ACAAI) have jointly accepted responsibility for establishing the "Practice parameter for the diagnosis and management of primary immunodeficiency." This is a complete and comprehensive document at the current time. The medical environment is a changing environment, and not all recommendations will be appropriate for all patients. Because this document incorporated the efforts of many participants, no single individual, including those who served on the Joint Task Force, is authorized to provide an official AAAAI or ACAAI interpretation of these practice parameters. Any request for information about or an interpretation of these practice parameters by the AAAAI or ACAAI should be directed to the Executive Offices of the AAAAI, the ACAAI, and the Joint Council of Allergy, Asthma & Immunology. These parameters are not designed for use by pharmaceutical companies in drug promotion.

Dysregulated production of interleukin-1β upon activation of the NLRP3 inflammasome in patients with familial Mediterranean fever

Familial Mediterranean fever (FMF) is caused by mutations in pyrin, a protein expressed in innate immune cells that interacts with caspase-1 and other inflammasome components to regulate interleukin (IL)-1β maturation. Since NLRP3 inflammasome represents major source of IL-1β, we studied its protein expression and function in FMF. We isolated peripheral white blood cells (WBCs) from 20 symptoms-free FMF patients and 21 healthy individuals. Intracellular protein expression of NLRP3, caspase-1, IL-1β at baseline and after LPS/ATP sequential treatment for NLRP3 activation was assessed by immunoblotting. Secreted IL-1β was quantified by ELISA. THP-1 cells were transfected with wild-type or mutant pyrin and IL-1β secretion was measured. FMF WBCs exhibited lower NLRP3 and active caspase-1 protein expression compared to healthy individuals, and LPS/ATP treatment resulted in significantly lower intracellular IL-1β levels in FMF patients. Likewise, LPS/ATP induced caspase-1-dependent IL-1β release at significantly lower amounts in the FMF group (1182±192 versus 2134±245pg/mL in controls, p=0.004). Consistently, THP-1 cells transfected with FMF-associated M694V mutant pyrin displayed lower LPS/ATP-induced IL-1β compared with wild-type pyrin-transfected cells. FMF WBCs demonstrate reduced NLRP3-mediated IL-1β production. Additional studies are needed to define whether this finding represents a compensatory mechanism to control inflammation or is directly linked to disease pathogenesis.

A novel mutation in IL36RN underpins childhood pustular dermatosis

Background

Chronic pustular dermatoses are severe and debilitating autoinflammatory conditions that can have a monogenic basis. Their clinical features are, however, complex with considerable overlap. Null and missense mutations in the genes encoding interleukin (IL)‐1 family (IL‐1 and IL‐36) anti‐inflammatory receptor antagonist (Ra) cytokines can underlie the development of severe pustular dermatoses.

Objective

We present a clinical and genetic study of four children of Pakistani descent with similar clinical presentations and treatment course, each of whom suffers from a severe pustular dermatosis, initially described as a pustular variant of psoriasis. We use DNA sequencing to refine the diagnosis of two of the children studied.

Methods

Bidirectional Sanger sequencing was performed on the coding regions of the IL‐1Ra and IL‐36Ra genes (IL1RN and IL36RN, respectively), for the four affected children and their parents.

Results

We identified a novel homozygous missense mutation in IL36RN in two siblings, and showed the molecular basis of the condition to be both distinct from psoriasis and distinct between the two families studied.

Conclusions

We describe a novel mutation which underpins the diagnosis of childhood pustular dermatosis. Molecular diagnostics can be used to aid the clinical diagnosis and potential treatment of autoinflammatory conditions.

Evidence-based provisional clinical classification criteria for autoinflammatory periodic fevers

The objective of this work was to develop and validate a set of clinical criteria for the classification of patients affected by periodic fevers. Patients with inherited periodic fevers (familial Mediterranean fever (FMF); mevalonate kinase deficiency (MKD); tumour necrosis factor receptor-associated periodic fever syndrome (TRAPS); cryopyrin-associated periodic syndromes (CAPS)) enrolled in the Eurofever Registry up until March 2013 were evaluated. Patients with periodic fever, aphthosis, pharyngitis and adenitis (PFAPA) syndrome were used as negative controls. For each genetic disease, patients were considered to be 'gold standard' on the basis of the presence of a confirmatory genetic analysis. Clinical criteria were formulated on the basis of univariate and multivariate analysis in an initial group of patients (training set) and validated in an independent set of patients (validation set). A total of 1215 consecutive patients with periodic fevers were identified, and 518 gold standard patients (291 FMF, 74 MKD, 86 TRAPS, 67 CAPS) and 199 patients with PFAPA as disease controls were evaluated. The univariate and multivariate analyses identified a number of clinical variables that correlated independently with each disease, and four provisional classification scores were created. Cut-off values of the classification scores were chosen using receiver operating characteristic curve analysis as those giving the highest sensitivity and specificity. The classification scores were then tested in an independent set of patients (validation set) with an area under the curve of 0.98 for FMF, 0.95 for TRAPS, 0.96 for MKD, and 0.99 for CAPS. In conclusion, evidence-based provisional clinical criteria with high sensitivity and specificity for the clinical classification of patients with inherited periodic fevers have been developed.

Inflammasome-independent regulation of IL-1-family cytokines

Induction, production, and release of proinflammatory cytokines are essential steps to establish an effective host defense. Cytokines of the interleukin-1 (IL-1) family induce inflammation and regulate T lymphocyte responses while also displaying homeostatic and metabolic activities. With the exception of the IL-1 receptor antagonist, all IL-1 family cytokines lack a signal peptide and require proteolytic processing into an active molecule. One such unique protease is caspase-1, which is activated by protein platforms called the inflammasomes. However, increasing evidence suggests that inflammasomes and caspase-1 are not the only mechanism for processing IL-1 cytokines. IL-1 cytokines are often released as precursors and require extracellular processing for activity. Here we review the inflammasome-independent enzymatic processes that are able to activate IL-1 cytokines, paying special attention to neutrophil-derived serine proteases, which subsequently induce inflammation and modulate host defense. The inflammasome-independent processing of IL-1 cytokines has important consequences for understanding inflammatory diseases, and it impacts the design of IL-1-based modulatory therapies.

Periodic Fever and Neutrophilic Dermatosis: Is It Sweet's Syndrome?

A 7-year-old boy with high grade fever (39°C) and warm, erythematous, and indurated plaque above the left knee was referred. According to the previous records of this patient, these indurated plaques had been changed toward abscesses formation and then spontaneous drainage had occurred after about 6 to 7 days, and finally these lesions healed with scars. In multiple previous admissions, high grade fever, leukocytosis, and a noticeable increase in erythrocyte sedimentation rate and C-reactive protein were noted. After that, until 7th year of age, he had shoulder, gluteal, splenic, kidney, and left thigh lesions and pneumonia. The methylprednisolone pulse (30 mg/kg) was initiated with the diagnosis of Sweet's syndrome. After about 10-14 days, almost all of the laboratory data regressed to nearly normal limits. After about 5 months, he was admitted again with tachypnea and high grade fever and leukocytosis. After infusion of one methylprednisolone pulse, the fever and tachypnea resolved rapidly in about 24 hours. In this admission, colchicine (1 mg/kg) was added to the oral prednisolone after discharge. In the periodic fever and neutrophilic dermatosis, the rheumatologist should search for sterile abscesses in other organs.

Expression of cytokines, chemokines and other effector molecules in two prototypic autoinflammatory skin diseases, pyoderma gangrenosum and Sweet's syndrome

Pyoderma gangrenosum (PG) and Sweet's syndrome (SS) are two inflammatory skin diseases presenting with painful ulcers and erythematous plaques, respectively; both disorders have a debilitating clinical behaviour and PG is potentially life-threatening. Recently, PG and SS have been included among the autoinflammatory diseases, which are characterized by recurrent episodes of sterile inflammation, without circulating autoantibodies and autoreactive T cells. However, an autoinflammatory pattern clearly supporting this inclusion has never been demonstrated. We studied 16 patients with PG, six with SS and six controls, evaluating, using a sandwich-based protein antibody array method, the expression profile of inflammatory effector molecules in PG, SS and normal skin. The expressions of interleukin (IL)-1 beta and its receptor I were significantly higher in PG (P = 0·0001 for both) and SS (P = 0·004-0·040) than in controls. In PG, chemokines such as IL-8 (P = 0·0001), chemokine (C-X-C motif) ligand (CXCL) 1/2/3 (P = 0·002), CXCL 16 (P = 0·003) and regulated upon activation normal T cell expressed and secreted (RANTES) (P = 0·005) were over-expressed. In SS, IL-8 (P = 0·018), CXCL 1/2/3 (P = 0·006) and CXCL 16 (P = 0·036) but not RANTES were over-expressed, suggesting that chemokine-mediated signals are lower than in PG. Fas/Fas ligand and CD40/CD40 ligand systems were over-expressed in PG (P = 0·0001 for Fas, P = 0·009 for Fas ligand, P = 0·012 for CD40, P = 0·0001 for CD40 ligand), contributing to tissue damage and inflammation, while their role seems to be less significant in SS. Over-expression of cytokines/chemokines and molecules amplifying the inflammatory network supports the view that PG and SS are autoinflammatory diseases. The differences in expression profile of inflammatory effectors between these two disorders may explain the stronger local aggressiveness in PG than SS.

Association of pyoderma gangrenosum, acne, and suppurative hidradenitis (PASH) shares genetic and cytokine profiles with other autoinflammatory diseases

The association of pyoderma gangrenosum, acne, and suppurative hidradenitis (PASH) has recently been described and suggested to be a new entity within the spectrum of autoinflammatory syndromes, which are characterized by recurrent episodes of sterile inflammation, without circulating autoantibodies and autoreactive T-cells. We conducted an observational study on 5 patients with PASH syndrome, analyzing their clinical features, genetic profile of 10 genes already known to be involved in autoinflammatory diseases (AIDs), and cytokine expression pattern both in lesional skin and serum. In tissue skin samples, the expressions of interleukin (IL)-1β and its receptors I and II were significantly higher in PASH (P = 0.028, 0.047, and 0.050, respectively) than in controls. In PASH patients, chemokines such as IL-8 (P = 0.004), C-X-C motif ligand (CXCL) 1/2/3 (P = 0.028), CXCL 16 (P = 0.008), and regulated on activation, normal T cell expressed and secreted (RANTES) (P = 0.005) were overexpressed. Fas/Fas ligand and cluster of differentiation (CD)40/CD40 ligand systems were also overexpressed (P = 0.016 for Fas, P = 0.006 for Fas ligand, P = 0.005 for CD40, and P = 0.004 for CD40 ligand), contributing to tissue damage and inflammation. In peripheral blood, serum levels of the main proinflammatory cytokines, that is, IL-1β, tumor necrosis factor-α, and IL-17, were within the normal range, suggesting that in PASH syndrome, the inflammatory process is mainly localized into the skin. Four out of our 5 PASH patients presented genetic alterations typical of well-known AIDs, including inflammatory bowel diseases, and the only patient lacking genetic changes had clinically evident Crohn disease. In conclusion, overexpression of cytokines/chemokines and molecules amplifying the inflammatory network, along with the genetic changes, supports the view that PASH syndrome is autoinflammatory in origin.

Integrative genomics identifies 7p11.2 as a novel locus for fever and clinical stress response in humans

Fever predicts clinical outcomes in sepsis, trauma and during cardiovascular stress, yet the genetic determinants are poorly understood. We used an integrative genomics approach to identify novel genomic determinants of the febrile response to experimental endotoxemia. We highlight multiple integrated lines of evidence establishing the clinical relevance of this novel fever locus. Through genome-wide association study (GWAS) of evoked endotoxemia (lipopolysaccharide (LPS) 1 ng/kg IV) in healthy subjects of European ancestry we discovered a locus on chr7p11.2 significantly associated with the peak febrile response to LPS (top single nucleotide polymorphism (SNP) rs7805622, P = 2.4 × 10(-12)), as well as with temperature fluctuation over time. We replicated this association in a smaller independent LPS study (rs7805622, P = 0.03). In clinical translation, this locus was also associated with temperature and mortality in critically ill patients with trauma or severe sepsis. The top GWAS SNPs are not located within protein-coding genes, but have significant cis-expression quantitative trait loci (eQTL) associations with expression of a cluster of genes ∼400 kb upstream, several of which (SUMF2, CCT6A, GBAS) are regulated by LPS in vivo in blood cells. LPS- and cold-treatment of adipose stromal cells in vitro suggest genotype-specific modulation of eQTL candidate genes (PSPH). Several eQTL genes were up-regulated in brown and white adipose following cold exposure in mice, highlighting a potential role in thermogenesis. Thus, through genomic interrogation of experimental endotoxemia, we identified and replicated a novel fever locus on chr7p11.2 that modulates clinical responses in trauma and sepsis, and highlight integrated in vivo and in vitro evidence for possible novel cis candidate genes conserved across human and mouse.