Hyper-IgD syndrome/mevalonate kinase deficiency: what is new?

Oral Diseases as a Manifestation of Inborn Errors of Immunity

Oral findings such as inflammation, ulcerations, or lesions can indicate serious systemic diseases and should prompt suspicion of acquired chronic conditions or inborn errors of immunity (IEIs). Currently, there are approximately 500 disease entities classified as IEIs, with the list expanding annually. The awareness of the existence of such conditions is of paramount importance, as patients with these disorders frequently necessitate the utilization of enhanced diagnostic techniques. This is exemplified by patients with impaired antibody production, in whom conventional serological methods may prove to be undiagnostic. Patients with IEI may require distinct therapeutic approaches or antimicrobial prophylaxis throughout their lives. An accurate diagnosis and, more importantly, early identification of patients with immune deficiencies is crucial to ensure the quality and longevity of their lives. It is important to note that the failure to establish a proper diagnosis or to provide adequate treatment could also have legal implications for medical professionals. The article presents IEIs, which may manifest in the oral cavity, and their diagnosis alongside therapeutic procedures.

Autoinflammatory Keratinization Diseases-The Concept, Pathophysiology, and Clinical Implications

Recent advances in medical genetics elucidated the background of diseases characterized by superficial dermal and epidermal inflammation with resultant aberrant keratosis. This led to introducing the term autoinflammatory keratinization diseases encompassing entities in which monogenic mutations cause spontaneous activation of the innate immunity and subsequent disruption of the keratinization process. Originally, autoinflammatory keratinization diseases were attributed to pathogenic variants of CARD14 (generalized pustular psoriasis with concomitant psoriasis vulgaris, palmoplantar pustulosis, type V pityriasis rubra pilaris), IL36RN (generalized pustular psoriasis without concomitant psoriasis vulgaris, impetigo herpetiformis, acrodermatitis continua of Hallopeau), NLRP1 (familial forms of keratosis lichenoides chronica), and genes of the mevalonate pathway, i.e., MVK, PMVK, MVD, and FDPS (porokeratosis). Since then, endotypes underlying novel entities matching the concept of autoinflammatory keratinization diseases have been discovered (mutations of JAK1, POMP, and EGFR). This review describes the concept and pathophysiology of autoinflammatory keratinization diseases and outlines the characteristic clinical features of the associated entities. Furthermore, a novel term for NLRP1-associated autoinflammatory disease with epithelial dyskeratosis (NADED) describing the spectrum of autoinflammatory keratinization diseases secondary to NLRP1 mutations is proposed.

Efficacy of Anakinra Treatment in two Moroccan Patients With Mevalonate Kinase Deficiency

Mevalonate kinase deficiency (MKD) is a rare hereditary autoinflammatory disease, with a widely variable clinical spectrum. It is characterized by febrile recurrent episodes and systemic inflammation. Data on therapeutic options for MKD are still limited and remain unknown in our country. We report Moroccan cases with MKD referred in our unit and treated with Anakinra, an interleukin-1 receptor antagonist. Through this study, we evaluate the efficacy of this bioagent, in our 2 MKD patients, in whom Anakinra has shown a complete clinical remission, with a remaining mild inflammation for one case, and normalization of growth with rare episodes of cervical adenopathies for the second case. Our experience provides an additional argument supporting the efficacy of Anakinra treatment, demonstrated previously but still lacks of objective data.

What General Neurologists Should Know about Autoinflammatory Syndromes?

Autoinflammatory disorders encompass a wide range of conditions with systemic and neurological symptoms, which can be acquired or inherited. These diseases are characterized by an abnormal response of the innate immune system, leading to an excessive inflammatory reaction. On the other hand, autoimmune diseases result from dysregulation of the adaptive immune response. Disease flares are characterized by systemic inflammation affecting the skin, muscles, joints, serosa, and eyes, accompanied by unexplained fever and elevated acute phase reactants. Autoinflammatory syndromes can present with various neurological manifestations, such as aseptic meningitis, meningoencephalitis, sensorineural hearing loss, and others. Early recognition of these manifestations by general neurologists can have a significant impact on the prognosis of patients. Timely and targeted therapy can prevent long-term disability by reducing chronic inflammation. This review provides an overview of recently reported neuroinflammatory phenotypes, with a specific focus on genetic factors, clinical manifestations, and treatment options. General neurologists should have a good understanding of these important diseases.

Increase in pediatric recurrent fever evaluations during the first year of the COVID-19 pandemic in North America

The impact of the COVID-19 pandemic on new diagnoses of recurrent fevers and autoinflammatory diseases is largely unknown. The Childhood Arthritis and Rheumatology Research Alliance (CARRA) PFAPA/AID Working Group aimed to investigate the impact of the COVID-19 pandemic on the number of pediatric patients evaluated for recurrent fevers and autoinflammatory diseases in North America. The absolute number of new outpatient visits and the proportion of these visits attributed to recurrent fever diagnoses during the pre-pandemic period (1 March 2019-29 February 2020) and the first year of the COVID-19 pandemic (1 March 2020-28 February 2021) were examined. Data were collected from 27 sites in the United States and Canada. Our results showed an increase in the absolute number of new visits for recurrent fever evaluations in 21 of 27 sites during the COVID-19 pandemic compared to the pre-pandemic period. The increase was observed across different geographic regions in North America. Additionally, the proportion of new visits to these centers for recurrent fever in relation to all new patient evaluations was significantly higher during the first year of the pandemic, increasing from 7.8% before the pandemic to 10.9% during the pandemic year (p < 0.001). Our findings showed that the first year of the COVID-19 pandemic was associated with a higher number of evaluations by pediatric subspecialists for recurrent fevers. Further research is needed to understand the reasons behind these findings and to explore non-infectious triggers for recurrent fevers in children.

Functional Hallmarks of Healthy Macrophage Responses: Their Regulatory Basis and Disease Relevance

Macrophages are first responders for the immune system. In this role, they have both effector functions for neutralizing pathogens and sentinel functions for alerting other immune cells of diverse pathologic threats, thereby initiating and coordinating a multipronged immune response. Macrophages are distributed throughout the body-they circulate in the blood, line the mucosal membranes, reside within organs, and survey the connective tissue. Several reviews have summarized their diverse roles in different physiological scenarios and in the initiation or amplification of different pathologies. In this review, we propose that both the effector and the sentinel functions of healthy macrophages rely on three hallmark properties: response specificity, context dependence, and stimulus memory. When these hallmark properties are diminished, the macrophage's biological functions are impaired, which in turn results in increased risk for immune dysregulation, manifested by immune deficiency or autoimmunity. We review the evidence and the molecular mechanisms supporting these functional hallmarks.

An Atypical Presentation of Mevalonate Kinase Deficiency in Response to Colchicine Treatment

Mevalonate kinase deficiency (MKD) is a periodic fever syndrome. Nonsteroidal anti-inflammatory drugs, corticosteroids, and anakinra are the most common treatments. However, colchicine is considered insufficient in disease control. In this case report, we present an 8-month-old infant with an atypical presentation of MKD. She had recurrent fever episodes, diarrhea, and lethargy. Elevated mevalonic acid was not detected in the urine. However, the genetic investigation showed a novel pathogenic heterozygous c.925G&#x3e;C (p.Gly309Arg) variant and a heterozygous c.1129G&#x3e;A (p.Val377Ile) mutation in the <i>MVK</i> gene. The patient was treated with colchicine for 8 months. During treatment, no further fever episode had been observed. It should be kept in mind that mevalonic acid excretion may not be present in the urine with mild MKD. Colchicine may be a reasonable option in mild MKD patients for a longer duration of treatment due to favorable adverse event profiles.

Mitochondrial Nucleic Acid as a Driver of Pathogenic Type I Interferon Induction in Mendelian Disease

The immune response to viral infection involves the recognition of pathogen-derived nucleic acids by intracellular sensors, leading to type I interferon (IFN), and downstream IFN-stimulated gene, induction. Ineffective discrimination of self from non-self nucleic acid can lead to autoinflammation, a phenomenon implicated in an increasing number of disease states, and well highlighted by the group of rare genetic disorders referred to as the type I interferonopathies. To understand the pathogenesis of these monogenic disorders, and polyfactorial diseases associated with pathogenic IFN upregulation, such as systemic lupus erythematosus and dermatomyositis, it is important to define the self-derived nucleic acid species responsible for such abnormal IFN induction. Recently, attention has focused on mitochondria as a novel source of immunogenic self nucleic acid. Best appreciated for their function in oxidative phosphorylation, metabolism and apoptosis, mitochondria are double membrane-bound organelles that represent vestigial bacteria in the cytosol of eukaryotic cells, containing their own DNA and RNA enclosed within the inner mitochondrial membrane. There is increasing recognition that a loss of mitochondrial integrity and compartmentalization can allow the release of mitochondrial nucleic acid into the cytosol, leading to IFN induction. Here, we provide recent insights into the potential of mitochondrial-derived DNA and RNA to drive IFN production in Mendelian disease. Specifically, we summarize current understanding of how nucleic acids are detected as foreign when released into the cytosol, and then consider the findings implicating mitochondrial nucleic acid in type I interferonopathy disease states. Finally, we discuss the potential for IFN-driven pathology in primary mitochondrial disorders.

Intestinal immunoregulation: lessons from human mendelian diseases

The mechanisms that maintain intestinal homeostasis despite constant exposure of the gut surface to multiple environmental antigens and to billions of microbes have been scrutinized over the past 20 years with the goals to gain basic knowledge, but also to elucidate the pathogenesis of inflammatory bowel diseases (IBD) and to identify therapeutic targets for these severe diseases. Considerable insight has been obtained from studies based on gene inactivation in mice as well as from genome wide screens for genetic variants predisposing to human IBD. These studies are, however, not sufficient to delineate which pathways play key nonredundant role in the human intestinal barrier and to hierarchize their respective contribution. Here, we intend to illustrate how such insight can be derived from the study of human Mendelian diseases, in which severe intestinal pathology results from single gene defects that impair epithelial and or hematopoietic immune cell functions. We suggest that these diseases offer the unique opportunity to study in depth the pathogenic mechanisms leading to perturbation of intestinal homeostasis in humans. Furthermore, molecular dissection of monogenic intestinal diseases highlights key pathways that might be druggable and therapeutically targeted in common forms of IBD.

Spectrum of clinical features and genetic variants in mevalonate kinase (MVK) gene of South Indian families suffering from Hyperimmunoglobulin D Syndrome

Hyper-IgD syndrome (HIDS, OMIM #260920) is a rare autosomal recessive autoinflammatory disorder caused by pathogenic variants in the mevalonate kinase (MVK) gene. HIDS has an incidence of 1:50,000 to 1:5,000, and is thought to be prevalent mainly in northern Europe. Here, we report a case series of HIDS from India, which includes ten patients from six families who presented with a wide spectrum of clinical features such as recurrent fever, oral ulcers, rash, arthritis, recurrent diarrhea, hepatosplenomegaly, and high immunoglobulin levels. Using whole exome sequencing (WES) and/or Sanger capillary sequencing, we identified five distinct genetic variants in the MVK gene from nine patients belonging to six families. The variants were classified as pathogenic or likely pathogenic as per the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG-AMP) guidelines for annotation of sequence variants. Over 70% of patients in the present study had two recurrent mutations in MVK gene i.e. a nonsynonymous variant p.V377I, popularly known as the ‘Dutch mutation’, along with a splicing variant c.226+2delT in a compound heterozygous form. Identity by descent analysis in two patients with the recurrent variants identified a 6.7 MB long haplotype suggesting a founder effect in the South Indian population. Our analysis suggests that a limited number of variants account for the majority of the patients with HIDS in South India. This has implications in clinical diagnosis, as well as in the development of cost-effective approaches for genetic diagnosis and screening. To our best knowledge, this is the first and most comprehensive case series of clinically and genetically characterized patients with HIDS from India.

Systemic autoinflammatory diseases

Systemic autoinflammatory diseases (SAIDs) are a growing group of disorders caused by a dysregulation of the innate immune system leading to episodes of systemic inflammation. In 1997, MEFV was the first gene identified as disease causing for Familial Mediterranean Fever, the most common hereditary SAID. In most cases, autoinflammatory diseases have a strong genetic background with mutations in single genes. Since 1997 more than 30 new genes associated with autoinflammatory diseases have been identified, affecting different parts of the innate immune system. Nevertheless, for at least 40-60% of patients with phenotypes typical for SAIDs, a distinct diagnosis cannot be met, leading to undefined SAIDs (uSAIDs). However, SAIDs can also be of polygenic or multifactorial origin, with environmental influence modulating the phenotype. The implementation of a disease continuum model combining the adaptive and the innate immune system with autoinflammatory and autoimmune diseases shows the complexity of SAIDs and the importance of new methods to elucidate molecular changes and causative factors in SAIDs. Diagnosis is often based on clinical presentation and genetic testing. The timeline from onset to diagnosis takes up to 7.3 years, highlighting the indisputable need to identify new treatment and diagnostic targets. Recently, other factors are under investigation as additional contributors to the pathogenesis of SAIDs. This review gives an overview of pathogenesis and etiology of SAIDs, and summarizes recent diagnosis and treatment options.

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.

A case report of mevalonate kinase deficiency in a 14-month-old female with fevers and lower extremity weakness

Background

This case follows a 14-month-old female, who despite multiple presentations to several physicians, continued to have recurrent febrile episodes with gross motor delay. Her case revealed an often missed diagnosis of Mevalonate Kinase Deficiency, that now has an FDA approved treatment that both reduces recurrence and produces remission.

Case presentation

A 14-month-old female with a history of gross motor delay, frequent Upper Respiratory Tract infections, and otitis media presented to an urgent care for inconsolability and refusal to bear weight on her right leg. She had recently been treated with amoxicillin for acute otitis media and had developed a diffuse maculopapular rash, without any associated respiratory or gastrointestinal distress that persisted beyond cessation of the antibiotics. The patient presented multiple times to an urgent care over the subsequent week for fussiness, fever, anorexia, lymphadenopathy, with labs concerning for worsening anemia and elevated inflammatory markers. Subsequently, the patient was admitted to the hospital for suspected osteomyelitis versus oncologic process. X-Ray imaging of the patient’s lower extremities showed osseous abnormalities inconsistent with infection. A metabolic work-up showed elevated urine mevalonic acid, and follow-up genetic testing was positive for mutations in both copies of her mevalonate kinase gene. This led to the diagnosis of MKD.

Conclusions

Often, episodic presentations require multiple perspectives to reveal the underlying cause. This case illustrates how apparent simple febrile episodes has the potential for more complexity upon further evaluation.

Determination of antibodies in everyday rheumatological practice

Antibody determination is routinely used in everyday rheumatological practice. Its result repeatedly determines the diagnosis or exclusion of a particular disease. Antibodies are immunoglobulins, i.e. some of the most important proteins in the immune system, and have specific properties that we should know. In addition, there are a number of factors that can affect their concentration, including drugs commonly used in the treatment of rheumatic diseases. There are definite indications, when the total concentrations of individual classes of immunoglobulins should be initially determined and it should be evaluated whether the patient produces them at all or their production is impaired. In some cases, we should evaluate the levels of specific antibodies along with the total protein concentration and the γ-globulin fraction, in which the antibodies are contained. The article presents information on the most common mistakes made when performing these tests.

Hereditary Autoinflammatory Disorders: Recognition and Treatment

The autoinflammatory diseases encompass approximately 30 monogenic disorders in which inborn errors in the innate immune system lead to episodic systemic inflammation. Largely mediated by dysregulation of myeloid cells, interleukin (IL)-1β, type I interferon, and NF-κB, these disorders have rapidly expanded over the past several years, and increasing numbers of patients identified. Crossover disorders, bridging autoinflammation and immunodeficiency, have recently been described. This article focuses on the clinical presentation of IL-1 and interferon-driven autoinflammatory disorders, and discusses novel diseases with features of immunodeficiency. Approaches to the clinical diagnosis, genetic testing, and treatment of these disorders are addressed.

The Potential Role of Trained Immunity in Autoimmune and Autoinflammatory Disorders

During induction of trained immunity, monocytes and macrophages undergo a functional and transcriptional reprogramming toward increased activation. Important rewiring of cellular metabolism of the myeloid cells takes place during induction of trained immunity, including a shift toward glycolysis induced through the mTOR pathway, as well as glutaminolysis and cholesterol synthesis. Subsequently, this leads to modulation of the function of epigenetic enzymes, resulting in important changes in chromatin architecture that enables increased gene transcription. However, in addition to the beneficial effects of trained immunity as a host defense mechanism, we hypothesize that trained immunity also plays a deleterious role in the induction and/or maintenance of autoimmune and autoinflammatory diseases if inappropriately activated.

Autoimmunity and autoinflammation: A systems view on signaling pathway dysregulation profiles

INTRODUCTION

Autoinflammatory and autoimmune disorders are characterized by aberrant changes in innate and adaptive immunity that may lead from an initial inflammatory state to an organ specific damage. These disorders possess heterogeneity in terms of affected organs and clinical phenotypes. However, despite the differences in etiology and phenotypic variations, they share genetic associations, treatment responses and clinical manifestations. The mechanisms involved in their initiation and development remain poorly understood, however the existence of some clear similarities between autoimmune and autoinflammatory disorders indicates variable degrees of interaction between immune-related mechanisms.

METHODS

Our study aims at contributing to a holistic, pathway-centered view on the inflammatory condition of autoimmune and autoinflammatory diseases. We have evaluated similarities and specificities of pathway activity changes in twelve autoimmune and autoinflammatory disorders by performing meta-analysis of publicly available gene expression datasets generated from peripheral blood mononuclear cells, using a bioinformatics pipeline that integrates Self Organizing Maps and Pathway Signal Flow algorithms along with KEGG pathway topologies.

RESULTS AND CONCLUSIONS

The results reveal that clinically divergent disease groups share common pathway perturbation profiles. We identified pathways, similarly perturbed in all the studied diseases, such as PI3K-Akt, Toll-like receptor, and NF-kappa B signaling, that serve as integrators of signals guiding immune cell polarization, migration, growth, survival and differentiation. Further, two clusters of diseases were identified based on specifically dysregulated pathways: one gathering mostly autoimmune and the other mainly autoinflammatory diseases. Cluster separation was driven not only by apparent involvement of pathways implicated in adaptive immunity in one case, and inflammation in the other, but also by processes not explicitly related to immune response, but rather representing various events related to the formation of specific pathophysiological environment. Thus, our data suggest that while all of the studied diseases are affected by activation of common inflammatory processes, disease-specific variations in their relative balance are also identified.

Cell size control - a mechanism for maintaining fitness and function

The maintenance of cell size homeostasis has been studied for years in different cellular systems. With the focus on 'what regulates cell size', the question 'why cell size needs to be maintained' has been largely overlooked. Recent evidence indicates that animal cells exhibit nonlinear cell size dependent growth rates and mitochondrial metabolism, which are maximal in intermediate sized cells within each cell population. Increases in intracellular distances and changes in the relative cell surface area impose biophysical limitations on cells, which can explain why growth and metabolic rates are maximal in a specific cell size range. Consistently, aberrant increases in cell size, for example through polyploidy, are typically disadvantageous to cellular metabolism, fitness and functionality. Accordingly, cellular hypertrophy can potentially predispose to or worsen metabolic diseases. We propose that cell size control may have emerged as a guardian of cellular fitness and metabolic activity.

Autoinflammatory diseases in adults. Clinical characteristics and prognostic implications

Autoinflammatory diseases are clinical conditions with inflammatory manifestations that present in a periodic or persistent manner and are caused by acquired or hereditary disorders of the innate immune response. In general, these diseases are more common in childhood, but cases have been reported in adults and are therefore important for all specialists. There are few references on these diseases in adults due to their low prevalence and underdiagnosis. The aim of this study is to review the scientific literature on these disorders to systematise their clinical, prognostic and treatment response characteristics in adults.

Lesson of the month 1: Autoinflammatory syndromes - an unusual cause of pyrexia of unknown origin

Autoinflammatory diseases are disorders of innate immunity and are characterised by recurring and unprovoked episodes of inflammation. We present a case of episodic pyrexia, associated with a significant inflammatory response, in a young man in whom the cause had remained unexplained since infancy. He was eventually diagnosed with hyperimmunoglobulinaemia D syndrome (HIDS); one of the autoinflammatory syndromes.

C13orf31 (FAMIN) is a central regulator of immunometabolic function

Single-nucleotide variations in C13orf31 (LACC1) that encode p.C284R and p.I254V in a protein of unknown function (called 'FAMIN' here) are associated with increased risk for systemic juvenile idiopathic arthritis, leprosy and Crohn's disease. Here we set out to identify the biological mechanism affected by these coding variations. FAMIN formed a complex with fatty acid synthase (FASN) on peroxisomes and promoted flux through de novo lipogenesis to concomitantly drive high levels of fatty-acid oxidation (FAO) and glycolysis and, consequently, ATP regeneration. FAMIN-dependent FAO controlled inflammasome activation, mitochondrial and NADPH-oxidase-dependent production of reactive oxygen species (ROS), and the bactericidal activity of macrophages. As p.I254V and p.C284R resulted in diminished function and loss of function, respectively, FAMIN determined resilience to endotoxin shock. Thus, we have identified a central regulator of the metabolic function and bioenergetic state of macrophages that is under evolutionary selection and determines the risk of inflammatory and infectious disease.

Hyperimmunoglobulinaemia D syndrome: a rare cause of prolonged fever and treatment with anti-interleukin 1 agent

Hyperimmunoglobulinaemia D syndrome (HIDS) is an autosomal recessive, autoinflammatory disease that is characterised with intermittent febrile episodes, cervical lymphadenopathy, rashes, arthritis and gastrointestinal symptoms associated with synovial or serosal inflammation. HIDS is caused by mutations in the gene encoding mevalonate kinase enzyme. The febrile attacks usually start in early childhood and triggered by stress or vaccinations. We report a case of 16-month-old boy who had episodes of recurrent fever accompanied by maculopapular rash and lymphadenopathy. He was diagnosed as HIDS and he had heterozygote mutation of mevalonate kinase gene.

Perinatal manifestation of mevalonate kinase deficiency and efficacy of anakinra

BACKGROUND

Mevalonate kinase deficiency is a metabolic autoinflammatory syndrome caused by mutations in the MVK gene, mevalonate kinase, the key enzyme in the non-sterol isoprenoid biosynthesis pathway. Two phenotypes of mevalonate kinase deficiency are known based on the level of enzymatic deficiency, mevalonic aciduria and hyperimmunoglobulinemia D syndrome, but a wide spectrum of intermediate phenotypes has been reported. Currently one of the most effective treatments is biological therapy (with interleukin-1 antagonist anakinra or tumour necrosis factor-α inhibitor etanercept).

CASE PRESENTATION

The patient in this case has a phenotype contributing to a severe disease that caused the symptoms to manifest very early, in the prenatal period. Mevalonate kinase deficiency was suspected on the basis of clinical (hydrops fetalis, hepatosplenomegaly, hypotonia) and laboratory signs (anaemia, intense acute phase reaction, increased urinary excretion of mevalonic acid). Mutation analysis of the MVK gene confirmed the biochemical diagnosis. Treatment with the interleukin-1 antagonist anakinra was started (minimal dose of 1 mg/kg/day) and revealed its efficacy after three days.

CONCLUSIONS

Our case highlights the need for a very detailed clinical and laboratory assessment in new-borns with any suggestion of autoinflammatory disorders. It is important that patients are diagnosed as early as possible to provide better multidisciplinary follow-up and therapy when needed.

Geranylgeraniol and Neurological Impairment: Involvement of Apoptosis and Mitochondrial Morphology

Deregulation of the cholesterol pathway is an anomaly observed in human diseases, many of which have in common neurological involvement and unknown pathogenesis. In this study we have used Mevalonate Kinase Deficiency (MKD) as a disease-model in order to investigate the link between the deregulation of the mevalonate pathway and the consequent neurodegeneration. The blocking of the mevalonate pathway in a neuronal cell line (Daoy), using statins or mevalonate, induced an increase in the expression of the inflammasome gene (NLRP3) and programmed cell death related to mitochondrial dysfunction. The morphology of the mitochondria changed, clearly showing the damage induced by oxidative stress and the decreased membrane potential associated with the alterations of the mitochondrial function. The co-administration of geranylgeraniol (GGOH) reduced the inflammatory marker and the damage of the mitochondria, maintaining its shape and components. Our data allow us to speculate about the mechanism by which isoprenoids are able to rescue the inflammatory marker in neuronal cells, independently from the block of the mevalonate pathway, and about the fact that cell death is mitochondria-related.

Histopathologic features in a case of hyperimmunoglobulinemia D syndrome

We describe a case of Mevalonate Kinase Deficiency (MKD) also known as Hyperimmunoglobulinemia D Syndrome (HIDS) presenting as a Sweet-like syndrome in a 5-week-old with multiple erythematous plaques, fever, aseptic meningitis, and bronchiolitis. The locations of the predominant plaques were periumbilical and periocular, which originally prompted concern for omphalitis and preseptal cellulitis. Histopathology demonstrated a neutrophilic and histiocytic dermatitis with prominent squamous syringometaplasia and leukocytoclasis in the absence of a vasculitis. This case is reported here due to the unique findings of a prominent histiocytic component in addition to the typically described neutrophilic infiltrate.

Innovative Target Therapies Are Able to Block the Inflammation Associated with Dysfunction of the Cholesterol Biosynthesis Pathway

The cholesterol pathway is an essential biochemical process aimed at the synthesis of bioactive molecules involved in multiple crucial cellular functions. The end products of this pathway are sterols, such as cholesterol, which are essential components of cell membranes, precursors of steroid hormones, bile acids and other molecules such as ubiquinone. Several diseases are caused by defects in this metabolic pathway: the most severe forms of which cause neurological involvement (psychomotor retardation and cerebellar ataxia) as a result of a variety of cellular impairments, including mitochondrial dysfunction. These pathologies are induced by convergent mechanisms in which the mitochondrial unit plays a pivotal role contributing to defective apoptosis, autophagy and mitophagy processes. Unraveling these mechanisms would contribute to the development of effective drug treatments for these disorders. In addition, the development of biochemical models could have a substantial impact on the understanding of the mechanism of action of drugs that act on this pathway in multifactor disorders. In this review we will focus in particular on inhibitors of cholesterol synthesis, mitochondria-targeted drugs and inhibitors of the inflammasome.

To Extinguish the Fire from Outside the Cell or to Shutdown the Gas Valve Inside? Novel Trends in Anti-Inflammatory Therapies

Cytokines are the most important soluble mediators of inflammation. Rare pediatric diseases provided exemplar conditions to study the anti-inflammatory efficacy of new generation therapies (biologics/biopharmaceuticals) selectively targeting single cytokines. Monoclonal antibodies and recombinant proteins have revolutionized anti-inflammatory therapies in the last two decades, allowing the specific targeting of single cytokines. They are very effective in extinguishing inflammation from outside the cell, even with the risk of an excessive and prolonged immunosuppression. Small molecules can enter the cell and shutdown the valve of inflammation by directly targeting signal proteins involved in cytokine release or in response to cytokines. They are orally-administrable drugs whose dosage can be easily adjusted to obtain the desired anti-inflammatory effect. This could make these drugs more suitable for a wide range of diseases as stroke, gout, or neurological impairment, where inflammatory activation plays a pivotal role as trigger. Autoinflammatory diseases, which have previously put anti-cytokine proteins in the limelight, can again provide a valuable model to measure the real potential of small inhibitors as anti-inflammatory agents.