Cryopyrin-associated Periodic Fever Syndrome Research Articles

Cryopyrin-associated periodic fever syndrome (CAPS) presenting as early-onset dementia, lacking typical recurrent fever or skin rash: a case report

A 54-year-old man with a university degree was admitted to our hospital because of a two-year history of progressive dementia. He had familial sensorineural hearing loss and had been treated for epilepsy since his 30s. On admission, he showed severe dementia and parkinsonism without fever or skin rash. Systemic inflammation was evident, and the CSF cell count and IL-6 level were elevated to 53/μl and 307 ‍pg/ml, respectively. Brain MRI demonstrated diffuse brain atrophy. More detailed anamnesis revealed a history of rheumatoid arthritis in childhood and aseptic meningitis in his 20s. Genetic examination for autoinflammatory diseases demonstrated compound heterozygotic mutations in the NLRP3 gene, causing cryopyrin-associated periodic fever syndrome (CAPS). This case was atypical CAPS presenting as early-onset progressive dementia, without recurrent fever or urticaria-like eruption which are usually seen in this disease.

Complex regulation of alarmins S100A8/A9 and secretion via gasdermin D pores exacerbates autoinflammation in familial Mediterranean fever

Familial Mediterranean fever (FMF), caused by mutations in the pyrin-encoding MEFV gene, is characterized by uncontrolled caspase-1 activation and IL-1β secretion. Asimilar mechanism drives inflammation in cryopyrin-associated periodic fever syndrome (CAPS) caused by mutations in NLRP3. CAPS and FMF, however, result in largely different clinical manifestations, pointing to additional, autoinflammatory pathways involved in FMF. Another hallmark of FMF is extraordinarily high expression of S100A8 and S100A9. These alarmins are ligands of Toll-like receptor 4 and amplifiers of inflammation. However, the relevance of this inflammatory pathway for the pathogenesis of FMF is unknown. This study investigated whether mutations in pyrin result in specific secretion of S100A8/A9 alarmins through gasdermin D pores' amplifying FMF pathology. S100A8/A9 levels in FMF patients were quantified by enzyme-linked immunosorbent assay. Invitro models with knockout cell lines and specific protein inhibitors were used to unravel the S100A8/A9 secretion mechanism. The impact of S100A8/A9 to the pathophysiology of FMF was analyzed with FMF (MEFVV726A/V726A) and S100A9-/- mouse models. Pyrin-S100A8/A9 interaction was investigated by coimmunoprecipitation, immunofluorescence, and enzyme-linked immunosorbent assay studies. The S100A8/A9 complexes directly interacted with pyrin. Knocking out pyrin, caspase-1, or gasdermin D inhibited the secretion of these S100 alarmins. Inflammatory S100A8/A9 dimers were inactivated by tetramer formation. Blocking this inactivation by targeted S100A9 deletion in a murine FMF model demonstrated the relevance of this novel autoinflammatory pathway in FMF. This is the first proof that members of the S100 alarmin family are released in a pyrin/caspase-1/gasdermin D-dependent pathway and directly drive autoinflammation invivo.

Evaluation of common NLRP3 Q703K variant in pediatric patients with autoinflammatory disease: CAPS and PFAPA.

Gain-of-function mutations of the NLR family pyrin domain containing 3 (NLRP3) gene have been implicated in autoinflammatory diseases. The NLRP3 Q703K variant is a common variant associated with Cryopyrin-associated periodic syndromes (CAPS) and periodic fever, aphthous stomatitis, pharyngitis and cervical adenitis (PFAPA) syndrome. However, the genotype-phenotype correlation between NLRP3 Q703K variant, CAPS and PFAPA is unclear. In this study, we aimed to investigate the frequency of the NLRP3 Q703K variant in patients with and without autoinflammatory disease and characterize the phenotype in only Q703K variant positive patients. A retrospective analysis of 639 patients with autoinflammatory symptoms was conducted. Patients underwent next-generation sequencing (NGS) panel analysis of 16 genes, including NLRP3. For the 68 patients carrying the only Q703K variant, their clinical and demographic information was evaluated. Genetic data from 1461 patients without autoinflammatory symptoms were used as the control group. Of our 639 autoinflammatory symptomatic patients, the Q703K mutation was detected in 68 (5.3% allele frequency). Heterozygous mutations were detected in 141 patients without autoinflammatory symptoms (4.8% allele frequency, p=0.4887). Of the patients with variant in Q703K, 10 patients were diagnosed with CAPS , 7 patients were diagnosed with PFAPA and the remaining 39 were diagnosed with undefined systemic autoinflammatory disease (uSAID) Conclusions. The Q703K variant, which is seen with similar frequency in the control and autoinflammatory groups, is also of higher prevalence in patients with mild CAPS symptoms and PFAPA syndrome. This variant, together with other undetected genetic variants or epigenetic modifications, may be responsible for the corresponding phenotype. As such, it is essential for clinicians to evaluate their patients using both genetic and clinical evaluations.

Real-world safety and effectiveness of canakinumab in patients with cryopyrin-associated periodic fever syndrome: a long-term observational study in Japan.

A post-marketing all-patient surveillance program was conducted to evaluate the safety and effectiveness of canakinumab, a monoclonal anti-interleukin-1β antibody, in patients in Japan with cryopyrin-associated periodic fever syndrome (CAPS), including familial cold auto-inflammatory syndrome, Muckle-Wells syndrome, and neonatal onset multisystem inflammatory disease. All patients with CAPS who received canakinumab treatment after drug approval in Japan were registered in this non-interventional, observational study. The observation period per patient was two years. Patients newly treated with canakinumab (New patients; NP) and those continuously treated with canakinumab following clinical trials (Roll-over patients; RP) were included. Data collection of clinical symptoms affecting physical function and prognosis was not mandated but assessed where available. Here, the interim results are reported. Of 87 patients in the safety set, the proportion of patients with any adverse drug reactions (ADRs) and any serious ADRs was 31.03% and 3.45%, respectively. The most common ADRs reported under system organ class were infections and infestations (20.69%). Of 84 patients in the effectiveness set, 75.76% and 83.33% of NP and RP, respectively, were responders at Week 24, achieving complete response without relapse. Responder rates were maintained up to Week 104. Clinical symptoms affecting physical function and prognosis remained unchanged in over half of those patients. Interim results provided the safety profile of canakinumab in a real-world setting, and identified no new safety concerns. Treatment with canakinumab has suggested sustained remission in the majority of patients in the real-world setting.

When All Is Not as It Seems: Recurrent Fever and New-onset Joint Pain in a 17-Month-old Girl.

When All Is Not as It Seems: Recurrent Fever and New-onset Joint Pain in a 17-Month-old Girl.

Rare Autoinflammatory Diseases: A Single Center Experience of 47 Patients

Autoinflammatory diseases include a group disease characterized by recurrent systemic inflammatory attacks due to failure in the regulation of the innate immune system. The beginning time of autoinflammatory disease are the most commonly in childhood. Autoinflammatory disease which having different clinical forms are rare, therefore diagnosis is often delayed. To determine the clinical, laboratory and radiological characteristics of children with rare autoinflammatory diseases and in which patients to consider autoinflammatory disease. Forty seven patients diagnosed with rare autoinflammatory diseases between 2010 and 2020 were analyzed retrospectively. Demographic characteristics, clinical courses, laboratory and imaging findings of the patients were recorded. Forty-seven with rare autoinflammatory patients evaluated. Twenty-three patients had Chronic Nonbacterial Osteomyelitis (CNO), seven patients had Mevalonate Kinase Deficiency (MKD), six patients had Blau Syndrome / Early-Onset Sarcoidosis (BS/EOS) Syndrome, three patients had Cryopyrin-associated periodic fever syndrome (CAPS), three patients had Autoinflammatory Vasculitis, one patient had Sideroblastic anemia with B-cell immunodeficiency, periodic fevers, and developmental delay (SIFD) syndrome, one patient had Neonatal Onset Pancytopenia, Autoinflammation, Rash and Episodic HLH (NOARCH) syndrome. Three of our patients were being followed up with a diagnosis of undiferantiated systemic autoinflammatory disease (uSAID).Autoinflammatory diseases may have different presentations. Steril and recurrent inflammation should be warning clinicians.

IL-1 Inhibitors in the Treatment of Monogenic Periodic Fever Syndromes: From the Past to the Future Perspectives.

Autoinflammatory diseases (AIDs) represent a rare and heterogeneous group of disorders characterized by recurrent episodes of inflammation and a broad range of clinical manifestations. The most common symptoms involve recurrent fevers, musculoskeletal symptoms, and serositis; however, AIDs can also lead to life-threatening complications, such as macrophage activation syndrome (MAS) and systemic AA amyloidosis. Typical monogenic periodic fever syndromes include cryopyrin-associated periodic fever syndrome (CAPS), tumor necrosis factor receptor-associated periodic syndrome (TRAPS), mevalonate kinase deficiency/hyper IgD syndrome (MKD/HIDS), and familial Mediterranean fever (FMF). However, a number of other clinical entities, such as systemic juvenile idiopathic arthritis (sJIA), adult-onset Still’s disease (AOSD), Kawasaki disease (KD) and idiopathic recurrent pericarditis (IRP), display similar phenotypical and immunological features to AIDs. All these diseases are pathophysiologicaly characterized by dysregulation of the innate immune system and the central pathogenic role is attributed to the IL-1 cytokine family (IL-1α, IL-1β, IL-1Ra, IL-18, IL-36Ra, IL-36α, IL-37, IL-36β, IL-36g, IL-38, and IL-33). Therefore, reasonable therapeutic approaches aim to inhibit these cytokines and their pathways. To date, several anti-IL-1 therapies have evolved. Each drug differs in structure, mechanism of action, efficacy for the treatment of selected diseases, and side effects. Most of the available data regarding the efficacy and safety of IL-1 inhibitors are related to anakinra, canakinumab, and rilonacept. Other promising therapeutics, such as gevokizumab, tadekinig alfa, and tranilast are currently undergoing clinical trials. In this review, we provide sophisticated and up-to-date insight into the therapeutic uses of different IL-1 inhibitors in monogenic periodic fever syndromes.

Systematic literature review of efficacy/effectiveness and safety of current therapies for the treatment of cryopyrin-associated periodic syndrome, hyperimmunoglobulin D syndrome and tumour necrosis factor receptor-associated periodic syndrome

ObjectivesSeveral therapies are used for the treatment of rareautoinflammatory conditions like cryopyrin-associated periodic fever syndromes (CAPS), hyperimmunoglobulin Dsyndrome (HIDS)/mevalonate kinase deficiency (MKD) and tumour necrosis factor receptor-associated periodic syndrome (TRAPS)....

Otoinflamatuar Periyodik Ateş Sendromları

Otoinflamatuar periyodik ateş sendromları, bulguları çoğunlukla çocukluk çağında başlayan, tekrarlayan ateş ve inflamasyon atakları ile karakterize doğal immün sistem bozukluğu sonucu ortaya çıkan hastalıklar grubudur. Ailevi Akdeniz ateşi (AAA) Türkiye gibi Akdeniz ülkelerinde en sık görülen periyodik ateş sendromudur. Diğer herediter otoinflamatuar periyodik ateş sendromları nadir hastalıklar olarak sınıflandırılmaktadır. Bu derlemede; AAA, tümör nekroz faktör (TNF) reseptörü ilişkili periyodik ateş sendromu (TRAPS), mevalonat kinaz (MVK) eksikliği, kriyopirin ilişkili periyodik ateş sendromu (CAPS) ve periyodik ateş, aftöz stomatit, farenjit ve adenit (PFAPA) sendromunun klinik özellikleri, önerilen sınıflandırma kriterleri ve tedavi seçenekleri değerlendirilmiştir.

Autoinflammatory diseases in childhood, part 1: monogenic syndromes.

Autoinflammatory diseases constitute a family of disorders defined by aberrant stimulation of inflammatory pathways without involving antigen-directed autoimmunity. They may be divided into monogenic and polygenic types. Monogenic autoinflammatory syndromes are those with identified genetic mutations, such as familial Mediterranean fever, tumor necrosis factor receptor-associated periodic fever syndrome (TRAPS), mevalonate kinase deficiency or hyperimmunoglobulin D syndrome, cryopyrin-associated periodic fever syndromes (CAPS), pyogenic arthritis pyoderma gangrenosum and acne (PAPA) syndrome, interleukin-10 and interleukin-10 receptor deficiencies, adenosine deaminase 2 deficiency and pediatric sarcoidosis. Those without an identified genetic mutation are known as polygenic and include systemic-onset juvenile idiopathic arthritis, idiopathic recurrent acute pericarditis, Behçet syndrome, chronic recurrent multifocal osteomyelitis and inflammatory bowel disease among others. Autoinflammatory disorders are defined by repeating episodes or persistent fever, rash, serositis, lymphadenopathy, arthritis and increased acute phase reactants, and thus may mimic infections clinically. Most monogenic autoinflammatory syndromes present in childhood. However, because of their infrequency, diverse and nonspecific presentation, and the relatively new genetic recognition, diagnosis is usually delayed. In this article, which is Part 1 of a two-part series, the authors update monogenic autoinflammatory diseases in children with special emphasis on imaging features that may help establish the correct diagnosis.

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.

Low-frequency mosaicism in cryopyrin-associated periodic fever syndrome: mosaicism in systemic autoinflammatory diseases.

Autoinflammatory disease is an 'inborn error of immunity', resulting in systemic inflammation. Cryopyrin-associated periodic syndrome (CAPS) is a prototypical autoinflammatory disease caused by gain-of-function mutations in the NLRP3 (NLR family pyrin domain containing 3) gene; these mutations activate the NLRP3 inflammasome, resulting in overproduction of IL-1β. The first case of CAPS caused by somatic NLRP3 mosaicism was reported in 2005 after identification of variant small peaks by Sanger sequencing. An international collaborative study revealed that the majority of mutation-negative CAPS cases are due to low-level NLRP3 mosaicism, suggesting that central nervous system involvement in somatic mosaicism patients is milder than in genotype-matched heterozygous patients. Recent advances in next-generation sequencing have expanded the number of NLRP3 somatic mosaicism cases and identified a new entity called 'late-onset CAPS with myeloid-specific NLRP3 mosaicism'; however, no mosaic-specific clinical features have been identified/confirmed yet. With respect to NLRP3 mosaicism in CAPS, a prospective longitudinal study on the variant genotype, its allele frequency and its tissue distribution (along with a comprehensive clinical phenotype) would provide better understanding of NLRP3 mosaicism, resulting in more appropriate patient care and genetic counseling.

Differential role of the NLRP3 inflammasome in infection and tumorigenesis.

Dysregulated inflammation is one of the hallmarks of cancer initiation and progression. Emerging evidence indicates that inflammasomes play a central role in regulating immune cell functions in various infections and cancer. Inflammasomes are multimeric complexes consisting of nucleotide-binding oligomerization domain (NOD) -like receptors (NLRs). Among the NLRs, NOD1, NOD2 and NLRP3 respond to a variety of endogenous (i.e. damage-associated molecular patterns) and exogenous (i.e. pathogen-associated molecular patterns) stimuli. The NLRP3 inflammasome is associated with the onset and progression of autoinflammatory and autoimmune diseases, including metabolic disorders, multiple sclerosis, inflammatory bowel disease, and cryopyrin-associated periodic fever syndrome. NLRP3 is also associated with a wide variety of infections and tumorigenesis that are closely correlated with chemotherapy response and prognosis. In this review, we explore the rapidly expanding body of research on the expression and functions of NLRP3 in infections and cancers and outline novel inhibitors targeting the NLRP3 inflammasome that could be developed as therapeutic alternatives to current anticancer treatment.

Autoinflammatory diseases: State of the art

Autoinflammatory diseases are characterized by innate immunity abnormalities. In autoinflammatory diseases (AID), inflammatory blood biomarkers are elevated during crisis without infection and usually without autoantibodies. The first 4 described AID were familial Mediterranean fever, cryopyrin-associated periodic fever syndrome (CAPS) or NLRP3-associated autoinflammatory disease (NRLP3-AID), mevalonate kinase deficiency (MKD) and TNFRSF1A-receptor associated periodic fever syndrome (TRAPS). Since their description 20 years ago, and with the progresses of genetic analysis, many new diseases have been discovered; some with recurrent fever, others with predominant cutaneous symptoms or even immune deficiency. After describing the 4 historical recurrent fevers, some polygenic inflammatory diseases will also be shortly described such as Still disease and periodic fever with adenitis, pharyngitis and aphtous (PFAPA) syndrome. To better explore AID, some key anamnesis features are crucial such as the family tree, the age at onset, crisis length and organs involved in the clinical symptoms. An acute phase response is mandatory in crisis.

What's new in autoinflammation?

The pathogenesis of autoinflammatory diseases has shed light on the concept of inflammation in general and on our understanding of the role of the innate immune system. The autoinflammatory diseases have a large spectrum with varying features of inflammation. The most common autoinflammatory diseases are those associated with periodic fevers. The delay in diagnosis of these four common diseases (familial Mediterranean fever, cryopyrin-associated periodic fever syndrome, mevalonate kinase deficiency, and TNF receptor-associated periodic fever syndrome) results in secondary amyloidosis of the kidney. The new work towards classification criteria for these diseases is presented. Recently a group of autoinflammatory diseases that are associated with vasculitis have also been identified. These are stimulators of interferon genes (STING)-associated vasculopathy of infancy (SAVI), which is a monogenic defect associated with excessive activity in interferon alpha and deficiency of adenosine deaminase 2, which is characterized by a polyarteritis nodosa-like picture. These monogenic diseases are now in our differential diagnosis of vasculitides. Secondary amyloidosis is a complication of autoinflammatory diseases. Understanding the inflammatory mechanisms in these diseases has led to the use of targeted biologics for this complication. It is hoped that enlightening the mechanisms underlying these monogenic autoinflammatory diseases will also teach us about the pathways in common diseases.

Vasculitis in Systemic Autoinflammatory Diseases.

Autoinflammatory diseases (AID) are diseases of the innate immune system, characterized by recurrent episodes of localized or systemic inflammation. Vasculitis may accompany AID. The causes of the association of vasculitis with monogenic AID are still debated. Among the monogenic AID, Familial Mediterranean Fever (FMF) is the most common. IgA-related vasculitis (IgAV) and Polyarteritis Nodosa (PAN) involving small and/or medium-sized vessels have an increased frequency among FMF patients. There are also case reports revealing vasculitic features in Cryopyrin-Associated Periodic Fever Syndrome (CAPS), Tumor Necrosis Factor Receptor-Associated Periodic Syndrome (TRAPS), Mevalonate Kinase Deficiency (MKD), also known as Hyper IgD syndrome (HIDS), Deficiency of IL-1 Receptor Antagonist (DIRA) and Pyogenic Arthritis, Pyoderma gangrenosum, and Acne (PAPA) patients. Central nervous system vasculitis and vasculopathy have been reported in DIRA and PAPA patients whereas small vessel involvement affecting skin has been reported in CAPS, TRAPS, and MKD patients. Alternatively, vasculitis can also be a leading feature especially in the recently defined monogenic AID (Otulipenia, Deficiency of Adenosine Deaminase 2-DADA2, Haploinsufficiency of A20) and interferonopathies (STING-associated vasculopathy with onset in infancy-SAVI). DADA2 often presents as a PAN-like disease. In otulipenia, patients have painful subcutaneous nodules caused by septal panniculitis with small and medium vessel vasculitis. Haploinsufficiency of A20 (also called Familial Behcet-like Autoinflammatory Syndrome) results in a phenotype very similar to the variable vessel vasculitis of Behcet's disease with recurrent oral-genital ulcers, in addition to, skin rash, uveitis, and polyarthritis. SAVI is an autoinflammatory vasculopathy with increased Interferon (IFN) signature, causing severe skin lesions resulting in ulceration, necrosis, and in some cases, amputation. Behcet's Disease (BD) is a multifactorial polygenic AID characterized by recurrent attacks of oral-genital ulcers, skin lesions, uveitis and a unique vasculitis affecting both arteries and veins of all sizes. Many clinical features overlap with other autoinflammatory diseases and overexpression of proinflammatory cytokines is an important feature of the disease.

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

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

Nek7 is an essential mediator of NLRP3 activation downstream of potassium efflux

Abstract Inflammasomes are intracellular protein complexes that drive the activation of inflammatory caspases. The NLRP3 inflammasome has been implicated in the pathogenesis of several acquired inflammatory diseases as well as Cryopyrin-associated periodic fever syndromes (CAPS) caused by inherited NLRP3 mutations. Despite extensive investigation, the molecular mechanism leading to NLRP3 activation remains unknown. We have identified Nek7 as an NLRP3-binding protein that acts downstream of potassium efflux to regulate NLRP3 oligomerization and activation. In the absence of Nek7, caspase-1 activation and IL-1β release were abrogated in response to signals that activate NLRP3, but not NLRC4 or AIM2 inflammasome. NLRP3 associated with the catalytic domain of Nek7, but the catalytic activity of Nek7 was dispensable for activation of the NLRP3 inflammasome. Activated macrophages formed a high-molecular-mass NLRP3-Nek7 complex, which along with ASC oligomerization and ASC speck formation were abrogated in the absence of Nek7. Nek7 was required for macrophages harboring the CAPS-associated NLRP3R258W activating mutation to activate caspase-1. Mouse chimeras reconstituted with wild-type, Nek7−/− or Nlrp3−/− hematopoietic cells revealed that Nek7 was required for NLRP3 inflammasome activation in vivo. Our studies demonstrate that Nek7 is an essential protein that acts downstream of potassium efflux to mediate NLRP3 inflammasome assembly and activation.

Neurology of the cryopyrin-associated periodic fever syndrome.

The cryopyrin-associated periodic fever syndrome (CAPS) is an autosomal dominant autoinflammatory disorder caused by mutations in the NLRP3 gene and is typified by recurrent episodes of systemic inflammation resulting in fever, urticarial rash and arthralgia. In addition to these systemic aspects, CAPS has multiple neurological manifestations. The largest case series to date is presented focusing on the neurological features of this disorder. The case histories of a cohort of 38 UK patients with genetically proven CAPS who were treated with interleukin 1β (IL-1β) inhibition as part of a national treatment programme and underwent detailed neurological assessment were reviewed. Across the entire disease course neurological manifestations were present in 95% of patients; 84% had some form of headache; 66% sensorineural hearing loss; 60% myalgia; 34% papilloedema and 26% optic atrophy. Patients with the T348M mutation tended to have a more severe neurological phenotype with an earlier age of onset. Four patients had cerebrospinal fluid examination, three of whom had evidence of aseptic meningitis. There was a marked response to IL-1β inhibition, which has revolutionized management of these patients (29/32 patients with headache responding). Neurological symptoms are extremely common in CAPS and these results highlight the importance of increasing awareness amongst neurologists, particularly as highly effective therapies are available.

NEK7 is an essential mediator of NLRP3 activation downstream of potassium efflux.

Inflammasomes are intracellular protein complexes that drive the activation of inflammatory caspases1. To date, four inflammasomes involving NLRP1, NLRP3, NLRC4 and AIM2 have been described that recruit the common adaptor ASC to activate caspase-1, leading to the secretion of mature IL-1β and IL-182,3. The NLRP3 inflammasome has been implicated in the pathogenesis of several acquired inflammatory diseases4,5 as well as Cryopyrin-associated periodic fever syndromes (CAPS) caused by inherited NLRP3 mutations6,7. Potassium efflux is a common step that is essential for NLRP3 inflammasome activation induced by multiple stimuli8,9. Despite extensive investigation, the molecular mechanism leading to NLRP3 activation in response to potassium efflux remains unknown. We report here the identification of Nek7, a member of the family of mammalian NIMA-related kinases (Neks)10, as an NLRP3-binding protein that acts downstream of potassium efflux to regulate NLRP3 oligomerization and activation. In the absence of Nek7, caspase-1 activation and IL-1β release were abrogated in response to signals that activate NLRP3, but not NLRC4 or AIM2 inflammasome. NLRP3-activating stimuli promoted the NLRP3-Nek7 interaction in a process dependent on potassium efflux. NLRP3 associated with the catalytic domain of Nek7, but the catalytic activity of Nek7 was dispensable for activation of the NLRP3 inflammasome. Activated macrophages formed a high-molecular-mass NLRP3-Nek7 complex, which along with ASC oligomerization and ASC speck formation were abrogated in the absence of Nek7. Nek7 was required for macrophages harboring the CAPS-associated NLRP3R258W activating mutation to activate caspase-1. Mouse chimeras reconstituted with wild-type, Nek7−/− or Nlrp3−/− hematopoietic cells revealed that Nek7 was required for NLRP3 inflammasome activation in vivo. These studies demonstrate that Nek7 is an essential protein that acts downstream of potassium efflux to mediate NLRP3 inflammasome assembly and activation.