A novel homozygous variant in PMVK is associated with enhanced IL1β secretion and a hyper-IgD syndrome-like phenotype

The evolutionarily conserved mevalonate pathway plays an important role in the synthesis of cholesterol and isoprenoid compounds. Mevalonate kinase (MVK) and phosphomevalonate kinase (PMVK) enzymes regulate key rate-limiting steps in this pathway by sequentially phosphorylating mevalonic acid to yield downstream metabolites that regulate protein prenylation and cell signaling. Biallelic pathogenic variants in MVK cause a spectrum of rare autoinflammatory disorders that encompass milder forms of hyper-IgD syndrome (HIDS) at one end and the more severe mevalonic aciduria on the other. In contrast, pathogenic variants reported in PMVK are heterozygous and associated with porokeratosis, a skin disorder with no systemic manifestations. Recently, biallelic variants in PMVK were reported as a cause for an autoinflammatory disorder for the first time in two unrelated patients. In this study, we describe a child with recurrent arthritis and a HIDS-like phenotype harboring a novel homozygous variant c.398 C>T (p.Ala133Val) in PMVK. Mononuclear cells isolated from the patient showed significantly elevated production of interleukin 1β, a key cytokine that shapes the inflammatory response in HIDS. Protein modeling studies suggested potential defects in PMVK enzyme activity. These results posit a further expanding of the genotypic spectrum of autoinflammatory disease to include biallelic PMVK variants.

A Hybrid Lightweight System for Early Attack Detection in the IoMT Fog

Cyber-attack detection via on-gadget embedded models and cloud systems are widely used for the Internet of Medical Things (IoMT). The former has a limited computation ability, whereas the latter has a long detection time. Fog-based attack detection is alternatively used to overcome these problems. However, the current fog-based systems cannot handle the ever-increasing IoMT’s big data. Moreover, they are not lightweight and are designed for network attack detection only. In this work, a hybrid (for host and network) lightweight system is proposed for early attack detection in the IoMT fog. In an adaptive online setting, six different incremental classifiers were implemented, namely a novel Weighted Hoeffding Tree Ensemble (WHTE), Incremental K-Nearest Neighbors (IKNN), Incremental Naïve Bayes (INB), Hoeffding Tree Majority Class (HTMC), Hoeffding Tree Naïve Bayes (HTNB), and Hoeffding Tree Naïve Bayes Adaptive (HTNBA). The system was benchmarked with seven heterogeneous sensors and a NetFlow data infected with nine types of recent attack. The results showed that the proposed system worked well on the lightweight fog devices with ~100% accuracy, a low detection time, and a low memory usage of less than 6 MiB. The single-criteria comparative analysis showed that the WHTE ensemble was more accurate and was less sensitive to the concept drift.

Phenotypic diversity, disease progression, and pathogenicity of MVK missense variants in mevalonic aciduria

Mevalonic aciduria (MVA) and hyperimmunoglobulinemia D syndrome (MKD/HIDS) are disorders of cholesterol biosynthesis caused by variants in the MVK gene and characterized by increased urinary excretion of mevalonic acid. So far, 30 MVA patients have been reported, suffering from recurrent febrile crises and neurologic impairment. Here, we present an in-depth analysis of the phenotypic spectrum of MVA and provide an in-silico pathogenicity model analysis of MVK missense variants. The phenotypic spectrum of 11 MVA patients (age range 0-51 years) registered in the Unified European Registry for Inherited Metabolic Disorders database was systematically analyzed using terms of the Human Phenotype Ontology. Biochemical, radiological as well as genetic characteristics were investigated. Six of eleven patients have reached adulthood and four have reached adolescence. One of the adolescent patients died at the age of 16 years and one patient died shortly after birth. Symptoms started within the first year of life, including episodic fever, developmental delay, ataxia, and ocular involvement. We also describe a case with absence of symptoms despite massive excretion of mevalonic acid. Pathogenic variants causing MVA cluster within highly conserved regions, which are involved in mevalonate and ATP binding. The phenotype of adult and adolescent MVA patients is more heterogeneous than previously assumed. Outcome varies from an asymptomatic course to early death. MVK variants cluster in functionally important and highly conserved protein domains and show high concordance regarding their expected pathogenicity.

Dynamics of Strontium and geochemically correlated elements in soil during washing remediation with eco-complaint chelators

In the study, the dynamics of Sr²⁺ and geochemically correlated elements (Ca²⁺, Ba²⁺, and Y³⁺) in soil with chelators in the mix (soil to chelator ratio, 1:10; matrix, H₂O) were assessed to understand chemical-induced washing remediation of radiogenic waste solids. Specifically, EDTA (2,2',2″,2‴-(ethane-1,2-diyldinitrilo)tetraacetic acid), EDDS (2-[2-(1,2-dicarboxyethylamino)ethylamino]butanedioic acid), GLDA (2-[bis(carboxymethyl)amino]pentanedioic acid), and HIDS (2-(1,2-dicarboxyethylamino)-3-hydroxy-butanedioic acid) are chelators that are used as extractants. The effect of solution pH on chelator-induced extractions of the target elements (t-Es: Sr²⁺, Ca²⁺, Ba²⁺, or Y³⁺) from soil and stability constants of the t-Es complexes with chelators were used to explain the trends and magnitudes in interactions. Pre- and post-extractive solid-phase speciation was used to define the extent of the competence of each chelator in persuading dissolution of t-Es in the soil. The effects of ultrasonic energy, admixtures of biodegradable chelators, and excess chelators in solution (1:20) were also analyzed on the extractive removal of t-Es from soil. The results indicate that the Sr²⁺ removal with biodegradable chelators significantly exceeded (approximately 70%) when compared to that of environmentally-persistent EDTA at lower solution pHs and a higher soil to chelator ratio (GLDA > HIDS > EDDS ≈ EDTA). However, the extraction of the geochemically related element was significantly lower.

Defective Protein Prenylation in a Spectrum of Patients With Mevalonate Kinase Deficiency

The rare autoinflammatory disease mevalonate kinase deficiency (MKD, which includes HIDS and mevalonic aciduria) is caused by recessive, pathogenic variants in the MVK gene encoding mevalonate kinase. Deficiency of this enzyme decreases the synthesis of isoprenoid lipids and thus prevents the normal post-translational prenylation of small GTPase proteins, which then accumulate in their unprenylated form. We recently optimized a sensitive assay capable of detecting unprenylated Rab GTPase proteins in peripheral blood mononuclear cells (PBMCs) and showed that this assay distinguished MKD from other autoinflammatory diseases. We have now analyzed PBMCs from an additional six patients with genetically-confirmed MKD (with different compound heterozygous MVK genotypes), and compared these with PBMCs from three healthy volunteers and four unaffected control individuals heterozygous for the commonest pathogenic variant, MVK^V377I. We detected a clear accumulation of unprenylated Rab proteins, as well as unprenylated Rap1A by western blotting, in all six genetically-confirmed MKD patients compared to heterozygous controls and healthy volunteers. Furthermore, in the three subjects for whom measurements of residual mevalonate kinase activity was available, enzymatic activity inversely correlated with the extent of the defect in protein prenylation. Finally, a heterozygous MVK^V377I patient presenting with autoinflammatory symptoms did not have defective prenylation, indicating a different cause of disease. These findings support the notion that the extent of loss of enzyme function caused by biallelic MVK variants determines the severity of defective protein prenylation, and the accumulation of unprenylated proteins in PBMCs may be a sensitive and consistent biomarker that could be used to aid, or help rule out, diagnosis of MKD.

Targeting cytokines to treat autoinflammatory diseases

Autoinflammatory diseases are rare group of conditions manifested by recurrent fevers, systemic inflammation, and dysfunctions of the innate immune system. These conditions are characterized by overproduction or lack of inhibition of various cytokines, and the advent of biologic drugs that block specific cytokines involved in these conditions has revolutionized their treatment. In this review, I will discuss the most common autoinflammatory conditions of adulthood including familial Mediterranean fever (FMF), cryopyrin-associated periodic syndrome (CAPS), mevalonate kinase deficiency/hyperimmunoglobulinemia D Syndrome (MKD/HIDS), TNF receptor-associated autoinflammatory syndrome (TRAPS), and systemic juvenile idiopathic arthritis/adult-onset Still's disease (SJIA/AOSD). I will discuss how IL-1, IL-6, IL-18, and TNF play pathogenic roles in these conditions and will review the evidence behind cytokine blockade for these diseases. Throughout the paper, I will reflect on gaps in knowledge of autoinflammatory diseases and will highlight the latest advances and newest drugs in development.

Comment to Santos et al., "hyper-IgD and periodic fever syndrome: a new MVK mutation (p.R277G) associated with a severe phenotype"

We performed molecular modeling analysis onto a novel mutation in the gene MVK, described by Santos et al., found to be causative of a severe form of Hyper-IgD/Mevalonate Kinase Deficiency. The mutation p.R277G, in our analysis, lowers the binding affinity for some enzyme's substrates. Interestingly, we found that p.R277G mutation inhibits binding of Isopentenyl Pyrophosphate (IPP) (binding free energy=0 kcal/mol), one of isoprenoids responsible for feedback-inhibition of MVK. IPP is known to be an activator of a specific class of T-cells and we can hypothesize that increased levels of this metabolite generate an aberrant immune system response. Indeed other experiments are needed to verify this hypothesis; however, this work demonstrates usefulness of molecular modeling in generating novel pathogenic hypothesis.

Treating inflammation by blocking interleukin-1 in humans

IL-1 is a master cytokine of local and systemic inflammation. With the availability of specific IL-1 targeting therapies, a broadening list of diseases has revealed the pathologic role of IL-1-mediated inflammation. Although IL-1, either IL-1α or IL-1β, was administered to patients in order to improve bone marrow function or increase host immune responses to cancer, these patients experienced unacceptable toxicity with fever, anorexia, myalgias, arthralgias, fatigue, gastrointestinal upset and sleep disturbances; frank hypotension occurred. Thus it was not unexpected that specific pharmacological blockade of IL-1 activity in inflammatory diseases would be beneficial. Monotherapy blocking IL-1 activity in a broad spectrum of inflammatory syndromes results in a rapid and sustained reduction in disease severity. In common conditions such as heart failure and gout arthritis, IL-1 blockade can be effective therapy. Three IL-1blockers have been approved: the IL-1 receptor antagonist, anakinra, blocks the IL-1 receptor and therefore reduces the activity of IL-1α and IL-1β. A soluble decoy receptor, rilonacept, and a neutralizing monoclonal anti-interleukin-1β antibody, canakinumab, are also approved. A monoclonal antibody directed against the IL-1 receptor and a neutralizing anti-IL-1α are in clinical trials. By specifically blocking IL-1, we have learned a great deal about the role of this cytokine in inflammation but equally important, reducing IL-1 activity has lifted the burden of disease for many patients.