Molecular and cellular consequences of mevalonate kinase deficiency.

Mevalonate kinase deficiency (MKD) is an autosomal recessive metabolic disorder associated with recurrent autoinflammatory episodes. The disorder is caused by bi-allelic loss-of-function variants in the MVK gene, which encodes mevalonate kinase (MK), an early enzyme in the isoprenoid biosynthesis pathway. To identify molecular and cellular consequences of MKD, we studied primary fibroblasts from severely affected patients with mevalonic aciduria (MKD-MA) and more mildly affected patients with hyper IgD and periodic fever syndrome (MKD-HIDS). As previous findings indicated that the deficient MK activity in MKD impacts protein prenylation in a temperature-sensitive manner, we compared the subcellular localization and activation of the small Rho GTPases RhoA, Rac1 and Cdc42 in control, MKD-HIDS and MKD-MA fibroblasts cultured at physiological and elevated temperatures. This revealed a temperature-induced altered subcellular localization and activation in the MKD cells. To study if and how the temperature-induced ectopic activation of these signalling proteins affects cellular processes, we performed comparative transcriptome analysis of control and MKD-MA fibroblasts cultured at 37 °C or 40 °C. This identified cell cycle and actin cytoskeleton organization as respectively most down- and upregulated gene clusters. Further studies confirmed that these processes were affected in fibroblasts from both patients with MKD-MA and MKD-HIDS. Finally, we found that, similar to immune cells, the MK deficiency causes metabolic reprogramming in MKD fibroblasts resulting in increased expression of genes involved in glycolysis and the PI3K/Akt/mTOR pathway. We postulate that the ectopic activation of small GTPases causes inappropriate signalling contributing to the molecular and cellular aberrations observed in MKD.

Canakinumab treatment real world evidence in 3 monogenic periodic fever syndromes in 2009-2022: an interim analysis using the French JIR cohort database.

BACKGROUND: Our study aimed to provide real-world evidence on the treatment patterns, effectiveness and safety of canakinumab in France in Familial Mediterranean Fever (FMF), Mevalonate Kinase Deficiency (MKD), and Tumor necrosis factor Receptor Associated Periodic Syndrome (TRAPS). METHODS: This study used the JIR cohort, a multicentre international registry created in 2013 to collect data on patients with juvenile inflammatory rheumatic diseases. French patients diagnosed with FMF, MKD or TRAPS and treated with canakinumab were included in this study. RESULTS: 31 FMF, 26 MKD and 7 TRAPS patients received canakinumab during the study period. Most of them initiated canakinumab at the recommended dose of 2 mg/kg or 150 mg, but less than half of FMF and MKD patients initiated it at the recommended frequency (every 4 weeks). Two years after initiation, the rate of patients still on treatment was 78.1% in FMF, 73.7% in MKD, and 85.7% in TRAPS patients. While the dose per injection remained globally the same over the course of the treatment, some adjustments of the dose intervals were observed. Six patients had a severe adverse event reported. Of those, three were possibly related to canakinumab. CONCLUSION: This interim analysis showed a good maintenance of canakinumab treatment 2 years after initiation and confirmed its safety profile in real-life practice in France in patients diagnosed with FMF, MKD and TRAPS. The high variety of dose and interval combinations observed in canakinumab treated patients let suppose that physicians adapt the posology to individual situations rather than a fixed treatment plan.

Mevalonate kinase-deficient THP-1 cells show a disease-characteristic pro-inflammatory phenotype.

Objective: Bi-allelic pathogenic variants in the MVK gene, which encodes mevalonate kinase (MK), an essential enzyme in isoprenoid biosynthesis, cause the autoinflammatory metabolic disorder mevalonate kinase deficiency (MKD). We generated and characterized MK-deficient monocytic THP-1 cells to identify molecular and cellular mechanisms that contribute to the pro-inflammatory phenotype of MKD. Methods: Using CRISPR/Cas9 genome editing, we generated THP-1 cells with different MK deficiencies mimicking the severe (MKD-MA) and mild end (MKD-HIDS) of the MKD disease spectrum. Following confirmation of previously established disease-specific biochemical hallmarks, we studied the consequences of the different MK deficiencies on LPS-stimulated cytokine release, glycolysis versus oxidative phosphorylation rates, cellular chemotaxis and protein kinase activity. Results: Similar to MKD patients' cells, MK deficiency in the THP-1 cells caused a pro-inflammatory phenotype with a severity correlating with the residual MK protein levels. In the MKD-MA THP-1 cells, MK protein levels were barely detectable, which affected protein prenylation and was accompanied by a profound pro-inflammatory phenotype. This included a markedly increased LPS-stimulated release of pro-inflammatory cytokines and a metabolic switch from oxidative phosphorylation towards glycolysis. We also observed increased activity of protein kinases that are involved in cell migration and proliferation, and in innate and adaptive immune responses. The MKD-HIDS THP-1 cells had approximately 20% residual MK activity and showed a milder phenotype, which manifested mainly upon LPS stimulation or exposure to elevated temperatures. Conclusion: MK-deficient THP-1 cells show the biochemical and pro-inflammatory phenotype of MKD and are a good model to study underlying disease mechanisms and therapeutic options of this autoinflammatory disorder.

Long-term safety and effectiveness of canakinumab in patients with monogenic autoinflammatory diseases: results from the interim analysis of the RELIANCE registry.

OBJECTIVE: Interim analysis of the RELIANCE registry, an on-going, non-interventional, open-label, multicentre, prospective study evaluating the long-term safety, dosing regimens and effectiveness of canakinumab in patients with cryopyrin-associated periodic syndromes (CAPS), familial Mediterranean fever (FMF), tumour-necrosis factor receptor-associated periodic syndrome (TRAPS) or mevalonate-kinase deficiency (MKD)/hyperimmunoglobulin-D syndrome (HIDS). METHODS: From September 2017 for patients with CAPS, and June 2018 for patients with FMF, TRAPS or MKD/HIDS, the registry enrolled paediatric (aged ≥2 years) and adult patients (aged ≥18 years) receiving canakinumab as part of their routine medical care. Safety, canakinumab dose, disease activity and quality of life outcome measures were evaluated at baseline and every 6 months until end of study visit. RESULTS: At the analysis cut-off date (December 2020), 168 patients (91 CAPS, 54 FMF, 16 TRAPS and 7 MKD/HIDS) were enrolled. 85 (50.9%) patients were female and 72 (43.1%) were children (<18 years). The median patient age was 20.0 years (range 2.0-79.0 years). In the CAPS cohort, serious infections and serious adverse drug-reactions were more common in patients receiving higher than the recommended starting dose (SD) of canakinumab. A trend to receive >SD of canakinumab was observed in the pooled population. The majority of patients were reported as having either absent or mild/moderate disease activity (physician's global assessment) from baseline to Month 30, with a stable proportion of patients (~70%) in remission under canakinumab treatment. Patient-reported disease activity (Visual Analogue Scale (VAS), Autoinflammatory Disease Activity Index), fatigue (VAS); markers of inflammation (C-reactive protein, serum amyloid A and erythrocyte sedimentation rate) remained well-controlled throughout. CONCLUSION: Data from this analysis confirm the long-term safety and effectiveness of canakinumab for the treatment of CAPS, FMF, TRAPS and MKD/HIDS.

Practical Approach to Diagnosis and Management of IL-1-Mediated Autoinflammatory Diseases (CAPS, TRAPS, MKD, and DIRA).

Systemic autoinflammatory diseases (SAIDs) are a group of rare genetic and nongenetic immune dysregulatory disorders associated with high morbidity and mortality if left untreated. Therefore, early diagnosis and initiation of targeted treatment is vital in SAID patients to control the disease activity and prevent long-term immune-mediated damage. A specific group of genetically defined SAIDs is associated with increased inflammasome-mediated production of active interleukin (IL)-1. Even though progress in immunobiology and genetics has brought forth diagnostic tools and novel treatments that have been described in the literature extensively, many challenges remain in the clinical setting. Some challenges that health care providers may face on a day-to-day basis include the requirement of a multidisciplinary approach due to the complexity of these diseases, limited evidence-based treatment options, and barriers to access available therapies. Primarily, IL-1 inhibitors anakinra, canakinumab, and rilonacept are used to control the inflammation in these patients, with the goal of achieving sustainable remission. Recently published provisional points to consider from the European Alliance of Associations for Rheumatology (EULAR) and American College of Rheumatology (ACR) provide diagnosis, management, and monitoring recommendations for four IL-1-mediated autoinflammatory diseases: cryopyrin-associated periodic syndromes (CAPS), tumour necrosis factor receptor-associated periodic syndrome (TRAPS), mevalonate kinase deficiency (MKD), and deficiency of the IL-1 receptor antagonist (DIRA). The goal of this paper is to aid health care professionals by providing a practical approach to diagnosis and management of these four IL-1 mediated SAIDs on the basis of the recent EULAR/ACR recommendations.

Tocilizumab for treating mevalonate kinase deficiency and TNF receptor-associated periodic syndrome: a case series and literature review.

BACKGROUND: Mevalonate kinase deficiency (MKD) and TNF receptor-associated periodic syndrome (TRAPS) are categorized as systemic autoinflammatory diseases (SAIDs), which are rare diseases characterized by early onset, severe conditions, and challenging diagnosis and treatment. Although different SAIDs have varying standard treatments, some SAIDs are poorly controlled after routine treatment, seriously affecting the growth and development of children and their quality of life. This study aims to provide more treatment strategies for SAIDs. CASE PRESENTATION: We present two Chinese patients with MKD and TRAPS who were resistant to TNF- (tumor necrosis factor-) α blockade. After using etanercept, baricitinib, and glucocorticoid, patients with MKD and TRAPS still had periodic fever and rash. Due to the unavailability of IL-1 antagonists in the Chinese Mainland, we started administering intravenous tocilizumab (TCZ) at a dosage of 240 mg every three weeks. They had not experienced fever or rash after receiving one or two doses of TCZ. Before treatment with TCZ in the MKD patient, white blood cell (WBC) count, and TNF-α level were normal, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) increased significantly, and IL-6 increased slightly. After treatment with TCZ, ESR and CRP levels returned to normal; however, IL-6 increased occasionally. In the TRAPS patient, ESR, CRP, WBC, IL-6, and TNF-α levels were increased significantly. After TCZ treatment, ESR, CRP, WBC, IL-6, and TNF-α levels returned to normal. The two patients were treated with TCZ for more than six months and achieved clinical and serological remission. Furthermore, they had no adverse reactions after injection of TCZ. CONCLUSION: In the absence of IL-1 antagonists in mainland China, tocilizumab emerges as an alternative drug in SAIDs that are resistant to TNF-α blockade.

Long-term efficacy of canakinumab in hyperimmunoglobulin D syndrome.

Hyperimmunoglobulin D syndrome (HIDS) is a rare autoinflammatory disorder with autosomal recessive inheritance. It is caused by specific mutations in the mevalonate kinase gene (MVK). No treatment specific to HIDS has been approved to date; however, nonsteroidal anti-inflammatory drugs, steroids, colchicine, tumor necrosis factor-α inhibitors, and anti-interleukin-1 treatments are used, based on case reports and observational studies. Herein, we report a case with recurrent fever and arthritis attacks who did not respond to anakinra and was successfully treated with canakinumab. Long-term remission was achieved without any side effects with 300 mg canakinumab treatment every 4 weeks for 5 years.

A case of mevalonate kinase deficiency, neonatal Sweet syndrome, and inflammatory bowel disease.

Mevalonate kinase deficiency is a group of rare metabolic autoinflammatory disorders that present with recurrent fevers, abdominal pain, arthralgias, adenopathy, and a variety of cutaneous manifestations. The skin findings may mimic cellulitis, erythema elevatum diutinum, IgA vasculitis, and Sweet syndrome, and there is often a morbilliform or urticarial rash and aphthous stomatitis. Mevalonate kinase deficiency is one of the identified monogenic variants that can cause very early onset inflammatory bowel disease (IBD). We present a rare case of a patient with mevalonate kinase deficiency, neonatal Sweet syndrome, and infantile-onset IBD, who has been successfully treated with canakinumab therapy.

A novel homozygous variant in PMVK is associated with enhanced IL1ß 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 1ß, 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.

Identification of FDA-approved drugs that increase mevalonate kinase in hyper IgD syndrome.

Mevalonate kinase deficiency (MKD) is an autoinflammatory metabolic disorder caused by bi-allelic loss-of-function variants in the MVK gene, resulting in decreased activity of the encoded mevalonate kinase (MK). Clinical presentation ranges from the severe early-lethal mevalonic aciduria to the milder hyper-IgD syndrome (MKD-HIDS), and is in the majority of patients associated with recurrent inflammatory episodes with often unclear cause. Previous studies with MKD-HIDS patient cells indicated that increased temperature, as caused by fever during an inflammatory episode, lowers the residual MK activity, which causes a temporary shortage of non-sterol isoprenoids that promotes the further development of inflammation. Because an increase of the residual MK activity is expected to make MKD-HIDS patients less sensitive to developing inflammatory episodes, we established a cell-based screen that can be used to identify compounds and/or therapeutic targets that promote this increase. Using a reporter HeLa cell line that stably expresses the most common MKD-HIDS variant, MK-V377I, C-terminally tagged with bioluminescent NanoLuc luciferase (nLuc), we screened the Prestwick Chemical Library®, which includes 1280 FDA-approved compounds. Multiple compounds increased MK-V377I-nLuc bioluminescence, including steroids (i.e., glucocorticoids, estrogens, and progestogens), statins and antineoplastic drugs. The glucocorticoids increased MK-V377I-nLuc bioluminescence through glucocorticoid receptor signaling. Subsequent studies in MKD-HIDS patient cells showed that the potent glucocorticoid clobetasol propionate increases gene transcription of MVK and other genes regulated by the transcription factor sterol regulatory element-binding protein 2 (SREBP-2). Our results suggest that increasing the flux through the isoprenoid biosynthesis pathway by targeting the glucocorticoid receptor or SREBP-2 could be a potential therapeutic strategy in MKD-HIDS.

Recent Insights in Pyrin Inflammasome Activation: Identifying Potential Novel Therapeutic Approaches in Pyrin-Associated Autoinflammatory Syndromes.

Pyrin is a cytosolic protein encoded by the MEFV gene, predominantly expressed in innate immune cells. Upon activation, it forms an inflammasome, a multimolecular complex that enables the activation and secretion of IL-1ß and IL-18. In addition, the Pyrin inflammasome activates Gasdermin D leading to pyroptosis, a highly pro-inflammatory cell death. Four autoinflammatory syndromes are associated with Pyrin inflammasome dysregulation: familial Mediterranean fever, hyper IgD syndrome/mevalonate kinase deficiency, pyrin-associated autoinflammation with neutrophilic dermatosis, and pyogenic arthritis, pyoderma gangrenosum, and acne syndrome. In this review, we discuss recent advances in understanding the molecular mechanisms regulating the two-step model of Pyrin inflammasome activation. Based on these insights, we discuss current pharmacological options and identify a series of existing molecules with therapeutic potential for the treatment of pyrin-associated autoinflammatory syndromes.

A case of neonatal sweet syndrome associated with mevalonate kinase deficiency.

BACKGROUND: Sweet syndrome (SS), also known as acute febrile neutrophilic dermatosis, is an immunologic syndrome characterized by widespread neutrophilic infiltration. Histiocytoid Sweet syndrome (H-SS) is a histopathologic variant of SS. While SS most commonly occurs in adults, this case report discusses an infant patient who presented with H-SS. CASE PRESENTATION: Through a multidisciplinary approach, this patient was also found to have very early onset inflammatory bowel disease (VEO-IBD) and Mevalonate kinase-associated disease (MKAD). While prior case studies have characterized an association between VEO-IBD and MKAD, there is no literature describing the association of all three diagnoses this case: H-SS, VEO-IBD and MKAD. Initiation of canakinumab in this patient resulted in successful control of the disease. CONCLUSIONS: This case highlights the importance of a multidisciplinary approach to rare diagnoses, and collaboration during cases with significant diagnostic uncertainty.

The assessment of autoinflammatory disease classification criteria (Eurofever/PRINTO) in a real-life cohort.

OBJECTIVE: The aim of the study was to determine the sensitivity and specificity rates of Eurofever/PRINTO autoinflammatory recurrent fever classification criteria with real-life data in patients with an autoinflammatory disease. METHODS: A total of 119 patients were included in the study. Based on clinical symptoms, they were divided into four subgroups: cryopyrin-associated periodic syndromes (CAPS), TNF receptor-associated periodic syndrome (TRAPS), mevalonate kinase deficiency (MKD), and syndrome of undifferentiated recurrent fever (SURF) using the Eurofever/PRINTO clinical classification criteria. In the last step, the patients were re-evaluated in the light of genetic results and their final diagnosis was reached. RESULTS: A total of 119 patients, including 37 CAPS, 13 TRAPS, 8 MKD, 39 SURF, 14 NLRP12-related autoinflammatory disease (NLRP12-AID), and 8 familial Mediterranean fever (FMF) patients were evaluated in the study. While the sensitivity of the new clinical Eurofever/PRINTO criteria was 48% for CAPS, 77% for TRAPS, 87.5%for MKD, and the specificity of the clinical criteria was 86% for CAPS, 85% for TRAPS, and 60% for MKD. The sensitivity of the new mixed (genetic plus clinical variables) Eurofever/PRINTO criteria was 27% for CAPS, 61% forTRAPS, 85% for MKD, and the specificity of the mixed criteria for each group was 100%. CONCLUSION: We found the sensitivity of the Eurofever/PRINTO classification criteria to be low as genotypic changes between populations cause phenotypic differences. For this reason, we think that patient-based evaluation is correct rather than standard classification criteria in real life. Key-points • In systemic autoinflammatory diseases, common variants in the populations may alter the phenotype, and making it difficult to classify some patients with the current classification criteria. • In populations with common genetic variants, the classification criteria should be modified according to the clinical phenotype.

Detection of a rare variant in PSTPIP1 through three generations in a family with an initial diagnosis of FMF/MKD-overlapping phenotype.

OBJECTIVE: The presence of FMF cases without MEFV (MEFV innate immunity regulator, pyrin) pathogenic variants led us to search for other genes' involvement in the disease development. Here, we describe the presence of genetic heterogeneity in a three-generation family with an FMF/mevalonate kinase deficiency (MKD)-overlapping phenotype without MEFV/MVK (mevalonate kinase) pathogenic variants. METHOD: Targeted sequencing revealed a rare, fully penetrant variant in PSTPIP1 (p.Arg228Cys, rs781341816). Computational stability analyses of PSTPIP1 protein were performed. PSTPIP1-pyrin protein interaction was examined by immunoprecipitation and immunoblotting in peripheral blood mononuclear cells (PBMCs) of patients and healthy controls. PBMCs were cultured, and inflammation was induced by LPS+ATP treatment, followed by protein level measurements of caspase-1, IL1ß, pyrin and PSTPIP1 in cell lysates and mature caspase-1 and mature IL1ß in supernatants. RESULTS: The conserved, rare (GnomAD, 0.000028) PSTPIP1 p.Arg228Cys variant, previously reported in ClinVar as a variant with uncertain significance, showed complete penetrance in the family presenting an autosomal dominant pattern. Computational analyses showed a potentially destabilizing effect of the variant on PSTPIP1 protein. Accordingly, PSTPIP1-pyrin interaction was increased in patients harboring the variant, which resulted in elevated levels of mature caspase-1 and IL1ß in the inflammation-induced patient samples. CONCLUSIONS: Unlike previously described cases with pyogenic arthritis, pyoderma gangrenosum, and acne (PAPA)-associated PSTPIP1 variants, our patients with the p.Arg228Cys variant presented with an FMF/MKD-overlapping phenotype. As additional data on the genetic heterogeneity in the variable clinical spectrum of autoinflammatory syndromes, we suggest that the p.Arg228Cys variant in PSTPIP1 is related to inflammation responses through strong PSTPIP1-pyrin interaction and pyrin inflammasome activation.

A possibly new autoinflammatory disease due to compound heterozygous phosphomevalonate kinase gene mutation.

BACKGROUND: Mevalonate kinase (MVK) plays a role in cholesterol and non-sterol isoprenoid biosynthesis and its deficiency-related diseases are caused by bi-allelic pathogenic mutations in the MVK gene, (MVK), which leads to rare hereditary autoinflammatory diseases. The disease may manifest different clinical phenotypes depending on the degree of the deficiency in the enzyme activity. The complete deficiency of the enzyme activity results in the severe metabolic disease called mevalonic aciduria, while a partial deficiency results in a broad spectrum of clinical presentations called hyper-immunoglobulin D syndrome (HIDS). Serum immunoglobulin (Ig) D and urine mevalonic acid levels may be increased during inflammatory attacks of HIDS. CASE PRESENTATION: Herein, for the first time in the literature, we present a 6-year-old male patient who suffered from recurrent episodes of fever, polyarthritis, skin rash, diarrhea, abdominal pain, and inflammatory bowel disease-like manifestations with elevated levels of serum IgD, and urine mevalonic acid. Eventually we detected compound heterozygous mutations in the phosphomevalonate kinase (PMVK) gene coding the second enzyme after mevalonate kinase in the mevalonate pathway. CONCLUSION: For patients presenting with HIDS-like findings, disease exacerbations and persistent chronic inflammation, and having high urinary mevalonic acid and serum IgD levels, raising suspicion in terms of MVK deficiency (MVKD), it is recommended to study all mevalonate pathway enzymes, even if there is no mutation in the MVK gene. It should be kept in mind that novel mutations might be seen such as PMVK gene.