Metabolic Induction of Trained Immunity through the Mevalonate Pathway.

Innate immune cells can develop long-term memory after stimulation by microbial products during infections or vaccinations. Here, we report that metabolic signals can induce trained immunity. Pharmacological and genetic experiments reveal that activation of the cholesterol synthesis pathway, but not the synthesis of cholesterol itself, is essential for training of myeloid cells. Rather, the metabolite mevalonate is the mediator of training via activation of IGF1-R and mTOR and subsequent histone modifications in inflammatory pathways. Statins, which block mevalonate generation, prevent trained immunity induction. Furthermore, monocytes of patients with hyper immunoglobulin D syndrome (HIDS), who are mevalonate kinase deficient and accumulate mevalonate, have a constitutive trained immunity phenotype at both immunological and epigenetic levels, which could explain the attacks of sterile inflammation that these patients experience. Unraveling the role of mevalonate in trained immunity contributes to our understanding of the pathophysiology of HIDS and identifies novel therapeutic targets for clinical conditions with excessive activation of trained immunity.

Immunoglobulin D enhances immune surveillance by activating antimicrobial, proinflammatory and B cell-stimulating programs in basophils.

Immunoglobulin D (IgD) is an enigmatic antibody isotype that mature B cells express together with IgM through alternative RNA splicing. Here we report active T cell-dependent and T cell-independent IgM-to-IgD class switching in B cells of the human upper respiratory mucosa. This process required activation-induced cytidine deaminase (AID) and generated local and circulating IgD-producing plasmablasts reactive to respiratory bacteria. Circulating IgD bound to basophils through a calcium-mobilizing receptor that induced antimicrobial, opsonizing, inflammatory and B cell-stimulating factors, including cathelicidin, interleukin 1 (IL-1), IL-4 and B cell-activating factor (BAFF), after IgD crosslinking. By showing dysregulation of IgD class-switched B cells and 'IgD-armed' basophils in autoinflammatory syndromes with periodic fever, our data indicate that IgD orchestrates an ancestral surveillance system at the interface between immunity and inflammation.

Unveiling the Efficacy, Safety, and Tolerability of Anti-Interleukin-1 Treatment in Monogenic and Multifactorial Autoinflammatory Diseases.

Autoinflammatory diseases (AIDs) are heterogeneous disorders characterized by dysregulation in the inflammasome, a large intracellular multiprotein platform, leading to overproduction of interleukin-1(IL-1)ß that plays a predominant pathogenic role in such diseases. Appropriate treatment is crucial, also considering that AIDs may persist into adulthood with negative consequences on patients' quality of life. IL-1ß blockade results in a sustained reduction of disease severity in most AIDs. A growing experience with the human IL-1 receptor antagonist, Anakinra (ANA), and the monoclonal anti IL-1ß antibody, Canakinumab (CANA), has also been engendered, highlighting their efficacy upon protean clinical manifestations of AIDs. Safety and tolerability have been confirmed by several clinical trials and observational studies on both large and small cohorts of AID patients. The same treatment has been proposed in refractory Kawasaki disease, an acute inflammatory vasculitis occurring in children before 5 years, which has been postulated to be autoinflammatory for its phenotypical and immunological similarity with systemic juvenile idiopathic arthritis. Nevertheless, minor concerns about IL-1 antagonists have been raised regarding their employment in children, and the development of novel pharmacological formulations is aimed at minimizing side effects that may affect adherence to treatment. The present review summarizes current findings on the efficacy, safety, and tolerability of ANA and CANA for treatment of AIDs and Kawasaki vasculitis with a specific focus on the pediatric setting.

Hyperimmunoglobulinemia D syndrome with recurrent perianal abscess successfully treated with canakinumab.

Hyperimmunoglobulinaemia D syndrome is an autoinflammatory disease usually representing recurrent episodes of fever, arthralgia/arthritis, cervical lymphadenopathy, vomiting, diarrhoea, abdominal pain and skin rashes lasting 3-7 days every 4-8 weeks since their infancy. Recent reports suggested a link between perianal fistulae/abscess and severe colitis with hyperimmunoglobulinaemia D syndrome resembling an inflammatory bowel disease phenotype. Herein, we report an 18-month-old patient with recurrent attacks of fever and pharyngitis lasting 2-3 days every 10-15 days since the first two weeks of life. Inflammatory attacks were accompanied by diarrhoea, oral aphthous ulcers, cervical lymphadenopathy, maculopapular rash, severe leukocytosis and perianal fistulae/abscess. After the initiation of canakinumab, the patient was clinically improved with complete healing of perianal fistulas/abscesses. In conclusion, hyperimmunoglobulinaemia D syndrome should be considered in differential diagnosis of inflammatory bowel disease and recurrent perianal abscess/fistula in a patient with inflammatory attacks.

Analysis of NLRP3, MVK and TNFRSF1A variants in adult Greek patients with autoinflammatory symptoms.

OBJECTIVES: Autoinflammatory diseases are characterised by abnormal hyperactivity of the innate immune system, causing systemic inflammation. The cryopyrin associated periodic syndrome (CAPS), the hyper IgD syndrome (HIDS) and the TNF receptor-associated periodic syndrome (TRAPS), are autoinflammatory conditions associated with mutations in the NLRP3, MVK and TNFRSF1A genes, respectively. We present the experience of our Department with these rare syndromes analysing genetic and clinical data of adult patients encountered between January 2011 and September 2017. METHODS: Eighty-eight adult patients with clinical suspicion of CAPS, HIDS and TRAPS were sequentially recruited and genetically tested for specific mutations in NLRP3, MVK and TNFRSF1A using Sanger sequencing. Clinical picture of mutation carriers was reviewed. Allele frequencies were compared to those described for the normal population by the 1000 Genomes project. RESULTS: Seventy-two of the 88 adult patients were found to be positive for mutations or polymorphisms. One patient carried two pathogenic MVK mutations (pV377I/c.1129G>A and c.850delG) and another one carried a pathogenic heterozygous pΑ439V/c.1316C>T NLRP3 mutation. Seventeen patients carried variants of uncertain significance. The pS434S/c.1302C>T NLRP3 mutation is slightly increased in our patients compared to the reference population and seems to correlate with severe symptom presentation. CONCLUSIONS: In rare cases, periodic fever and inflammatory symptoms in adults can be attributed to mutations in NLRP3, MVK and TNFRSF1A. Clinical assessment and genetic analysis are critical for proper diagnosis and treatment of autoinflammatory diseases.

Cholesterol metabolism and immunity.

A study in mice implicates a cholesterol derivative in damping down the inflammatory response mediated by interleukin-1ß and explaining, at least in part, the immunosuppressive effect of type I interferon, which is used in the treatment of multiple sclerosis.

Other autoinflammatory disease genes in an FMF-prevalent population: a homozygous MVK mutation and a novel heterozygous TNFRSF1A mutation in two different Turkish families with clinical FMF.

OBJECTIVES: No MEFV mutations are detected in approximately 10% of the patients with clinical FMF in populations where the disease is highly prevalent. Causative mutations were searched in other genes in two such families with "MEFV negative clinical FMF". METHODS: Father and daughter of family A had attacks of fever, abdominal pain and AA amyloidosis. The two sibs of family B complained of febrile episodes with abdominal pain and arthritis. The patients were clinically investigated. Exome analysis in the daughter in family A and linkage analysis and candidate gene sequencing for the members of family B were performed. All patients were re-evaluated in the light of the genetic findings. RESULTS: In the daughter in family A, filtering of the exome file for variants in 25 autoimmune/inflammatory disease-related genes revealed two heterozygous missense variants in TNFRSF1A, novel p.Cys72Phe and frequent p.Arg121Gln. In family B, novel, homozygous missense p.Cys161Arg in MVK was identified. A clinical re-evaluation of the patients revealed a phenotype consistent with FMF rather than TRAPS in family A and an overlap of FMF with HIDS in family B. CONCLUSIONS: In high risk populations of FMF a proportion of patients without MEFV mutations may carry causative mutations in other genes, and the clinical findings may not be fully consistent with the phenotype expected of the mutation identified but rather resemble FMF or an overlap syndrome.

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-1ß 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-1ß 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.

Current advances in the understanding and treatment of mevalonate kinase deficiency.

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

Mevalonate kinase deficiency, a metabolic autoinflammatory disease.

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

Mouse model of mevalonate kinase deficiency: comparison of cytokine and chemokine profile with that of human patients.

BACKGROUND: Mevalonate kinase deficiency (MKD) is a rare genetic autoinflammatory disease caused by blocking of the enzyme mevalonate kinase in the pathway of cholesterol and isoprenoids. The pathogenic mechanism originating an immune response in MKD patients has not been clearly understood. METHODS: We investigated the dysregulation of expression of selected cytokines and chemokines in the serum of MKD patients. The results have been compared with those observed in an MKD mouse model obtained by treating the mice with aminobisphosphonate, a molecule that is able to inhibit the cholesterol pathway, mimicking the genetic block characteristic of the disease. RESULTS: Interleukin (IL)-1ß, IL-5, IL-6, IL-9, IL-17, granulocyte colony-stimulating factor, monocyte chemotactic protein-1, tumor necrosis factor-α, and IL-4 expression were dysregulated in sera from MKD patients and mice. Moreover, geraniol, an exogenous isoprenoid, when administered to MKD mice, restored cytokines and chemokines levels with values similar to those of untreated mice. CONCLUSION: Our findings, which were obtained in patients and a mouse model mimicking the human disease, suggest that these cytokines and chemokines could be MKD specific and that isoprenoids could be considered as potential therapeutic molecules. The mouse model, even if with some limitations, was robust and suitable for routine testing of potential MKD drugs.

Mevalonate kinase genotype in children with recurrent fevers and high serum IgD level.

In selected cases, childhood's recurrent fevers of unknown origin can be referred to systemic autoinflammatory diseases as mevalonate kinase deficiency (MKD), caused by mutations in the mevalonate kinase gene (MVK), previously named "hyper-IgD syndrome" due to its characteristic increase in serum IgD level. There is no clear evidence for studying MVK genotype in these patients. From a cohort of 305 children evaluated for recurrent fevers in our outpatient clinic during the decade 2001-2011, we have retrospectively selected 10 unrelated Italian children displaying febrile episodes, associated with recurrent inflammatory signs (variably involving gastrointestinal tube, joints, lymph nodes, and skin) and persistently increased serum IgD levels. All these patients were examined for MVK genotype: only 2 presented bonafide MVK mutations, 5 showed the same S52N MVK polymorphism, while the remaining 3 had a wild-type MVK sequence. Clinical details of these patients have been reviewed through the critical analysis of their medical charts. Our report underscores the pitfalls of MKD diagnosis based on clinical grounds and IgD levels, emphasizing the uncertain contribution of MVK polymorphisms in the diagnostic assessment of the syndrome.

Hyper-IgD syndrome or mevalonate kinase deficiency.

PURPOSE OF REVIEW: The hyper-IgD and periodic fever syndrome (HIDS) is one of the classical monogenetic hereditary autoinflammatory disorders, and together with the more severe mevalonic aciduria it is also known as 'mevalonate kinase deficiency' (MKD). In this study, we will give an overview of the primary research on mevalonate kinase deficiency published in the past 2 years. RECENT FINDINGS: Besides an inventory of a number of recent case reports, literature review shows there are several interesting developments in the basic field of research. First, a group of articles was recently published on chemically instead of genetically induced MKD mouse and cell models, investigating the effects of several isoprenoid pathway intermediates. Second, another study confirms a role for small GTPases and their isoprenylation in the inflammatory response in mevalonate kinase deficiency. Lastly, there are now, finally, modest new indications about the role of IgD. SUMMARY: Both pathophysiological studies and clinical observations in the last 2 years have supported the central role of IL-1 in HIDS. There are some intriguing results and hypotheses about the link between isoprenoid metabolism and the IL-1 pathway through geranylgeranylation that deserve to be further examined.

The farnesyltransferase inhibitors tipifarnib and lonafarnib inhibit cytokines secretion in a cellular model of mevalonate kinase deficiency.

The shortage of geranylgeranyl-pyrophosphate (GGPP) was associated to an increased IL-1ß release in the autoinflammatory syndrome mevalonate kinase deficiency (MKD), a rare inherited disease that has no specific therapy. Farnesyltransferase inhibitors (FTIs) act at the end of mevalonate pathway. Two FTIs, tipifarnib (Tip) and lonafarnib (Lon), were therefore evaluated as possible therapeutical choices for the treatment of MKD. FTIs could lead to a redirection of the limited available number of mevalonate intermediates preferentially to GGPP synthesis, eventually preventing the uncontrolled inflammatory response. The effect of Tip and Lon on intracellular cholesterol level (ICL) and on proinflammatory cytokines secretion was evaluated in a cellular model of MKD, chemically obtained treating RAW 264.7 cells with lovastatin (Lova) and alendronate (Ald). The combination of FTIs with the isoprenoid geraniol (GOH) was also tested both in this model and in monocytes isolated from MKD patients. Tip and Lon proved to revert the ICL lowering and to significantly reduce the lipopolysaccharide-induced cytokines secretion in Ald-Lova -RAW 264.7 cells. This anti-inflammatory effect was amplified combining the use of GOH with FTIs. The effect of GOH and Tip was successfully replicated in MKD patients' monocytes. Tip and Lon showed a dramatic anti-inflammatory effect in monocytes where mevalonate pathway was chemically or genetically impaired.

[Autoinflammatory diseases as cause of wound healing defects]. / Autoinflammatorische Erkrankungen als Ursache von Wundheilungsstörungen.

Ulcerations of the skin and mucosal membranes are a common feature of autoinflammatory diseases. They can give raise to chronic wound healing defects and should be considered in the differential diagnosis of chronic skin ulcers. The increased activation of the innate immune system in the absence of an apparent provocation for inflammation is a hallmark of autoinflammatory diseases. Mutations and alterations of signaling pathways regulating the innate immune response to physical trauma/tissue damage result into an unrestrained activation of the inflammasome, which leads to increased activation of Interleukin-1. Uncontrolled recruitment and activation of myeloid effector cells within the wound site lead to the release of potent proteases that cause the degradation of structural components of the skin. The majority of these diseases respond well to immunosuppressive and immunomodulatory treatment regimes. Therapeutic resistance converts the acute inflammatory response into a chronic and non-resolving inflammatory process that leads to tissue degeneration. In this article we will focus on the review of those autoinflammatory diseases that often display ulcerative cutaneous and aphthous lesions including pyoderma gangrenosum, Behçet disease, PAPA syndrome and hyperimmunoglobulinemia D with periodic fever syndrome (HIDS). Furthermore, the article will be complemented by an overview of those inflammatory diseases that are associated with non-ulcerative cutaneous manifestations.

Targeting farnesyl-transferase as a novel therapeutic strategy for mevalonate kinase deficiency: in vitro and in vivo approaches.

Mevalonate kinase deficiency (MKD) is a rare inborn auto-inflammatory disease due to the impairment of the pathway for the biosynthesis of cholesterol and non-sterol isoprenoids. The shortage of isoprenoids compounds and in particular of geranylgeranylpyrophosphate (GGPP) was recently associated to the MKD characteristic inflammatory attacks. The aim of this study is to demonstrate that the normalization of the mevalonate pathway intermediates levels and in particular of GGPP, through the specific inhibition of farnesyl-transferase (FT) with Manumycin A could ameliorate the inflammatory phenotype of MKD patients. The effect of Manumycin A was first evaluated in MKD mouse and cellular models, chemically obtained using the aminobisphosphonate alendronate (ALD), and then in monocytes isolated from 2 MKD patients. Our findings were compared to those obtained by using natural exogenous isoprenoids (NEIs). Manumycin A was able to significantly reduce the inflammatory marker serum amyloid A in ALD-treated Balb/c mice, as well as IL-1 beta secretion in ALD-monocytes and in MKD patients. These results clearly showed that, through the inhibition of FT, an increased number of mevalonate pathway intermediates could be redirected towards the synthesis of GGPP diminishing the inflammatory response. The importance in limiting the shortage of GGPP was emphasized by the anti-inflammatory effect of NEIs that, due to their biochemical structure, can enter the MKD pathway. In conclusion, manumycin A, as well as NEIs, showed anti-inflammatory effect in MKD models and especially in MKD-monocytes, suggesting novel approaches in the treatment of MKD, an orphan disease without any efficacious treatment currently available.

Fevers, genes, and innate immunity.

The characterization of patients with recurrent inflammatory syndromes into distinct clinical phenotypes provided early clues to the mode of inheritance of these conditions and facilitated the subsequent identification of causative gene mutations. The prototype autoinflammatory syndrome, familial Mediterranean fever, is characterized by self-limiting episodes of localized inflammation. Hallmarks of the classical autoimmune response are largely absent. The use of positional cloning techniques led to the identification of the causative gene, MEFV, and its product pyrin. This previously unrecognized protein plays an important role in modulating the innate immune response. Cryopyrin, the protein encoded by CIAS1, is mutated in a spectrum of autoinflammatory conditions, the cryopyrinopathies. In response to a wide range of potential pathogens, it forms a macromolecular complex termed the "inflammasome," resulting in caspase-1 activation and subsequent release of the active proinflammatory cytokine interleukin-1beta (IL-1beta). The role of an established biochemical pathway in regulating inflammation was uncovered by the discovery that the hyperimmunoglobulin D with periodic fever syndrome (HIDS) results from mutations in MVK, which encodes an enzyme in the isoprenoid pathway. The discovery that mutations in the gene encoding tumor necrosis factor (TNF) receptor 1 (TNFR1) cause a proinflammatory phenotype was unanticipated, as it seemed more likely that such mutations would instead have resulted in an immunodeficiency pattern. This review describes the clinical phenotypes of autoinflammatory syndromes, the underlying gene mutations, and current concepts regarding their pathophysiology.

Open-Label, Phase II Study to Assess the Efficacy and Safety of Canakinumab Treatment in Active Hyperimmunoglobulinemia D With Periodic Fever Syndrome.

OBJECTIVE: To evaluate the efficacy and safety of canakinumab treatment in active hyperimmunoglobulinemia D with periodic fever syndrome (HIDS). METHODS: This was a 3-part open-label study with an initial 6-month treatment period in which patients with HIDS (n = 9) received canakinumab subcutaneously at a dose of 300 mg (or 4 mg/kg for those weighing ≤40 kg) every 6 weeks (period 1 [P1]), followed by a 6-month withdrawal period (period 2 [P2]), and then a 24-month extension treatment period with canakinumab at the same dose (period 3 [P3]). The primary end point was reduction in the frequency of attacks during treatment periods as compared to the historical period (HP; defined as the period in which patients did not receive drugs other than nonsteroidal antiinflammatory drugs and/or steroids). RESULTS: All 9 patients completed P1 and P2, whereas only 8 patients completed P3. All patients achieved a complete response during P1, and only 2 required dose adjustments. The number of attacks per patient decreased from a median of 5 (range 3-12) during the HP to a median of 0 (range 0-2) during P1. During P2, 7 of 9 patients experienced a disease flare within a median of 110 days (range 62-196) after the last canakinumab dose. Laboratory findings were normalized by day 15 of treatment and remained at normal levels throughout the study. Analysis of blood transcriptome profiles, assessed during P1, showed up-regulated levels of interferon and myeloid-related inflammatory responses in untreated patients compared to healthy controls, and these rapidly decreased following canakinumab injection, reaching levels comparable to those of healthy controls. At least 1 adverse event (AE) was detected in all 9 patients. Most of the AEs were mild in intensity, with infections being the most frequent AE. Serious AEs were reported in 4 patients. CONCLUSION: The results of this study demonstrate the efficacy and safety of canakinumab treatment to control active HIDS and to suppress inflammation-related transcriptional responses.