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OBJECTIVE: To study the phenotype characteristics of the largest to date cohort of patients with pediatric granulomatous arthritis (PGA) and documented mutations in the NOD2 gene. METHODS: We analyzed merged data from 2 prospective cohorts of PGA patients, the International PGA Registry and a Spanish cohort. A systematic review of the medical records of interest was performed to identify phenotype characteristics. RESULTS: Forty-five patients with PGA (23 sporadic cases and 22 from familial pedigrees) and documented NOD2 mutations were identified and formed the basis of the study. Of these 45 patients, 18 had the R334W-encoding mutation, 18 had R334Q, 4 had E383K, 3 had R587C, 1 had C495Y, and 1 had W490L. The majority of patients manifested the typical triad of dermatitis, uveitis, and arthritis. In contrast, in 13 patients, the following 'atypical' manifestations were noted: fever, sialadenitis, lymphadenopathy, erythema nodosum, leukocytoclastic vasculitis, transient neuropathy, granulomatous glomerular and interstitial nephritis, interstitial lung disease, arterial hypertension, hypertrophic cardiomyopathy, pericarditis, pulmonary embolism, hepatic granulomatous infiltration, splenic involvement, and chronic renal failure. In addition, 4 individuals who were asymptomatic carriers of a disease-causing mutation were documented. CONCLUSION: NOD2-associated PGA can be a multisystem disorder with significant visceral involvement. Treating physicians should be aware of the systemic nature of this condition, since some of these manifestations may entail long-term morbidity. [ABSTRACT FROM AUTHOR]

Pediatric granulomatous arthritis (PGA) has been associated with 12 different substitutions in the NOD2 gene thus far. We report a case of PGA in a 6-year-old girl with the NOD2 E383K gene substitution. Genotype analysis of the patient's family members revealed that her affected paternal aunt, as well as her asymptomatic father and 3 younger siblings, were heterozygous for the E383K substitution. The patient's mother did not have a NOD2 mutation. This is the first report of a pedigree in which 4 asymptomatic members carry the E383K substitution in NOD2, as well as the first observation of an asymptomatic carrier state for any of the NOD2 'Blau mutations.' [ABSTRACT FROM AUTHOR]

Mevalonate kinase deficiency (MKD), a rare auto-inflammatory disorder, arises from mutations in the MVK gene, disrupting isoprenoid biosynthesis, and affecting cellular processes. This comprehensive review provides an updated perspective on MKD, including its aetiology, pathogenesis, diagnostic modalities, and therapeutic strategies. Based on recent research and clinical advances, our objective is to bridge the knowledge gaps in the 2015 SHARE guidelines. By describing molecular mechanisms, diagnostic dilemmas, and emerging therapies, this article should serve as a resource for clinicians and researchers, promoting a deeper understanding of MKD and guiding optimal patient care., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Lengvári, Takács, Lengyel, Pálinkás, Wouters, Koné-Paut, Kuemmerle-Deschner, Jeyaratnam, Anton, Lachmann, Gattorno, Hofer, Toplak, Weiser, Kallinich, Ozen, Hentgen, Uziel, Horváth, Szabados, Brogan, Constantin and Frenkel.)

Hemophagocytic lymphohistiocytosis (HLH) comprises a broad spectrum of life-threatening cytokine storm syndromes, classified into primary (genetic) or secondary (acquired) HLH. The latter occurs in a variety of medical conditions, including infections, malignancies, autoimmune and autoinflammatory diseases, acquired immunodeficiency, and metabolic disorders. Despite recent advances in the field, the pathogenesis of secondary HLH remains incompletely understood. Considering the heterogeneity of triggering factors and underlying diseases in secondary HLH, a large diversity of animal models has been developed to explore pivotal disease mechanisms. To date, over 20 animal models have been described that each recapitulates certain aspects of secondary HLH. This review provides a comprehensive overview of the existing models, highlighting relevant findings, discussing the involvement of different cell types and cytokines in disease development and progression, and considering points of interest toward future therapeutic strategies., (© 2024. The Author(s), under exclusive license to Springer Nature Switzerland AG.)

Monocytes and macrophages are innate immune cells with diverse functions ranging from phagocytosis of microorganisms to forming a bridge with the adaptive immune system. A lesser-known attribute of macrophages is their ability to fuse with each other to form multinucleated giant cells. Based on their morphology and functional characteristics, there are in general three types of multinucleated giant cells including osteoclasts, foreign body giant cells and Langhans giant cells. Osteoclasts are bone resorbing cells and under physiological conditions they participate in bone remodeling. However, under pathological conditions such as rheumatoid arthritis and osteoporosis, osteoclasts are responsible for bone destruction and bone loss. Foreign body giant cells and Langhans giant cells appear only under pathological conditions. While foreign body giant cells are found in immune reactions against foreign material, including implants, Langhans giant cells are associated with granulomas in infectious and non-infectious diseases. The functionality and fusion mechanism of osteoclasts are being elucidated, however, our knowledge on the functions of foreign body giant cells and Langhans giant cells is limited. In this review, we describe and compare the phenotypic aspects, biological and functional activities of the three types of multinucleated giant cells. Furthermore, we provide an overview of the multinucleation process and highlight key molecules in the different phases of macrophage fusion., Competing Interests: CW obtained unrestricted grants to KU Leuven from Novartis, Roche, GSK immuno-inflammation and Pfizer. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Ahmadzadeh, Vanoppen, Rose, Matthys and Wouters.)

Natural killer (NK) cells are innate immune lymphocytes with potent cytolytic and immune-regulatory activities. NK cells are well-known for their ability to kill infected and malignant cells in a fast and non-specific way without prior sensitization. For this purpose, NK cells are equipped with a set of cytotoxic molecules such as perforin and apoptosis-inducing proteins. NK cells also have the capacity to produce large amounts of cytokines and chemokines that synergize with their cytotoxic function and that ensure interaction with other immune cells. A less known feature of NK cells is their capacity to kill non-infected autologous cells, such as immature dendritic cells and activated T cells and monocytes. Via the release of large amounts of TNF-α and IFN-γ, NK cells may contribute to disease pathology. Conversely they may exert a regulatory role through secretion of immuno-regulatory cytokines such as GM-CSF, IL-13, and IL-10. Thus, NK cells may be important target and effector cells in the pathogenesis of autoinflammatory diseases, in particular in those disorders associated with a cytokine storm or in conditions where immune cells are highly activated. Key examples of such diseases are systemic juvenile idiopathic arthritis (sJIA) and its well-associated complication, macrophage activation syndrome (MAS). sJIA is a chronic childhood immune disorder of unknown etiology, characterized by arthritis and systemic inflammation, including a daily spiking fever and evanescent rash. MAS is a potentially fatal complication of autoimmune and autoinflammatory diseases, and most prevalently associated with sJIA. MAS is considered as a subtype of hemophagocytic lymphohistiocytosis (HLH), a systemic hyperinflammatory disorder characterized by defective cytotoxic pathways of cytotoxic T and NK cells. In this review, we describe the established features of NK cells and provide the results of a literature survey on the reported NK cell abnormalities in monogenic and multifactorial autoinflammatory disorders. Finally, we discuss the role of NK cells in the pathogenesis of sJIA and MAS., (Copyright © 2020 Vandenhaute, Wouters and Matthys.)

Background: Postzygotic de novo mutations lead to the phenomenon of gene mosaicism. The 3 main types are called somatic, gonadal, and gonosomal mosaicism, which differ in terms of the body distribution of postzygotic mutations. Mosaicism has been reported occasionally in patients with primary immunodeficiency diseases (PIDs) since the early 1990s, but its real involvement has not been systematically addressed., Objective: We sought to investigate the incidence of gene mosaicism in patients with PIDs., Methods: The amplicon-based deep sequencing method was used in the 3 parts of the study that establish (1) the allele frequency of germline variants (n = 100), (2) the incidence of parental gonosomal mosaicism in families with PIDs with de novo mutations (n = 92), and (3) the incidence of mosaicism in families with PIDs with moderate-to-high suspicion of gene mosaicism (n = 36). Additional investigations evaluated body distribution of postzygotic mutations, their stability over time, and their characteristics., Results: The range of allele frequency (44.1% to 55.6%) was established for germline variants. Those with minor allele frequencies of less than 44.1% were assumed to be postzygotic. Mosaicism was detected in 30 (23.4%) of 128 families with PIDs, with a variable minor allele frequency (0.8% to 40.5%). Parental gonosomal mosaicism was detected in 6 (6.5%) of 92 families with de novo mutations, and a high incidence of mosaicism (63.9%) was detected among families with moderate-to-high suspicion of gene mosaicism. In most analyzed cases mosaicism was found to be both uniformly distributed and stable over time., Conclusion: This study represents the largest performed to date to investigate mosaicism in patients with PIDs, revealing that it affects approximately 25% of enrolled families. Our results might have serious consequences regarding treatment and genetic counseling and reinforce the use of next-generation sequencing-based methods in the routine analyses of PIDs., (Copyright © 2018 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Objective: To identify biomarkers of articular and ocular disease activity in patients with Blau syndrome (BS)., Methods: Multiplex plasma protein arrays were performed in five BS patients and eight normal healthy volunteers (NHVs). Plasma S100A12 and S100A8/9 were subsequently measured by ELISA at baseline and 1-year follow-up in all patients from a prospective multicentre cohort study. CRP was measured using Meso Scale Discovery immunoassay. Active joint counts, standardization uveitis nomenclature for anterior uveitis cells and vitreous haze by Nussenblatt scale were the clinical parameters., Results: Multiplex Luminex arrays identified S100A12 as the most significantly elevated protein in five selected BS vs eight NHVs and this was confirmed by ELISA on additional samples from the same five BS patients. In the patient cohort, S100A12 (n = 39) and S100A8/9 (n = 33) were significantly higher compared with NHVs (n = 44 for S100A12, n = 40 for S100A8/9) (P = 0.0000004 and P = 0.0003, respectively). Positive correlations between active joint counts and S100 levels were significant for S100A12 (P = 0.0008) and S100A8/9 (P = 0.015). CRP levels did not correlate with active joint count. Subgroup analysis showed significant association of S100 proteins with active arthritis (S100A12 P = 0.01, S100A8/9 P = 0.008). Active uveitis was not associated with increased S100 levels., Conclusion: S100 proteins are biomarkers of articular disease activity in BS and potential outcome measures in future clinical trials. As secreted neutrophil and macrophage products, S100 proteins may reflect the burden of granulomatous tissue in BS., (© The Author(s) 2018. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Purpose: Provide baseline and preliminary follow-up results in a 5-year longitudinal study of Blau syndrome., Design: Multicenter, prospective interventional case series., Methods: Baseline data from 50 patients from 25 centers worldwide, and follow-up data for patients followed 1, 2, or 3 years at the end of study enrollment. Ophthalmic data were collected at baseline and yearly visits by means of a standardized collection form., Results: Median age at onset of eye disease was 60 months and duration of eye disease at baseline 145 months. At baseline 38 patients (78%) had uveitis, which was bilateral in 37 (97%). Eight patients (21%) had moderate to severe visual impairment. Panuveitis was found in 38 eyes (51%), with characteristic multifocal choroidal infiltrates in 29 eyes (39%). Optic disc pallor in 9 eyes (12%) and peripapillary nodules in 9 eyes (12%) were the commonest signs of optic nerve involvement. Active anterior chamber inflammation was noted in 30 eyes (40%) at baseline and in 16 (34%), 17 (57%), and 11 (61%) eyes at 1, 2, and 3 years, respectively. Panuveitis was associated with longer disease duration. At baseline, 56 eyes (75%) were on topical corticosteroids. Twenty-six patients (68%) received a combination of systemic corticosteroids and immunomodulatory therapy., Conclusions: Blau uveitis is characterized by progressive panuveitis with multifocal choroiditis, resulting in severe ocular morbidity despite continuous systemic and local immunomodulatory therapy. The frequency and severity of Blau uveitis highlight the need for close ophthalmologic surveillance as well as a search for more effective therapies., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: Hemophagocytic lymphohistiocytosis (HLH) is a rare immunological disorder caused by unbridled activation of T cells and macrophages, culminating in a life-threatening cytokine storm. A genetic and acquired subtype are distinguished, termed primary and secondary HLH, respectively. Clinical manifestations of both forms are frequently preceded by a viral infection, predominantly with herpesviruses. The exact role of the viral infection in the development of the hemophagocytic syndrome remains to be further elucidated., Methods: We utilized a recently developed murine model of cytomegalovirus-associated secondary HLH and dissected the respective contributions of lytic viral replication and immunopathology in its pathogenesis., Results: HLH-like disease only developed in cytomegalovirus-susceptible mouse strains unable to clear the virus, but the severity of symptoms was not correlated to the infectious viral titer. Lytic viral replication and sustained viremia played an essential part in the pathogenesis since abortive viral infection was insufficient to induce a full-blown HLH-like syndrome. Nonetheless, a limited set of symptoms, in particular anemia, thrombocytopenia and elevated levels of soluble CD25, appeared less dependent of the viral replication but rather mediated by the host's immune response, as corroborated by immunosuppressive treatment of infected mice with dexamethasone., Conclusion: Both virus-mediated pathology and immunopathology cooperate in the pathogenesis of full-blown virus-associated secondary HLH and are closely entangled. A certain level of viremia appears necessary to elicit the characteristic HLH-like symptoms in the model.

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening, hyperinflammatory syndrome, characterized by the uncontrolled activation of macrophages and T cells, eliciting key symptoms such as persistent fever, hepatosplenomegaly, pancytopenia, hemophagocytosis, hyperferritinemia, and coagulopathy. Viral infections are frequently implicated in the onset of active HLH episodes, both in primary, genetic HLH as in the secondary, acquired form. Infections with herpesviruses such as Epstein-Barr virus and cytomegalovirus are the most common. In autoimmune diseases, a link between viral infections and autoreactive immune responses has been recognized for a considerable time. However, the mechanisms by which viruses contribute to HLH pathogenesis remain to be clarified. In this viewpoint, different factors that may come into play are discussed. Viruses, particularly larger DNA viruses such as herpesviruses, are potent modulators of the immune response. By evading immune recognition, interfering with cytokine balances and inhibiting apoptotic pathways, viruses may increase the host's susceptibility to HLH development. In particular cases, a direct connection between the viral infection and inhibition of natural killer cell or T cell cytotoxicity was reported, indicating that viruses may create immunological deficiencies reminiscent of primary HLH.

Objective: Systemic juvenile idiopathic arthritis (JIA) is an immunoinflammatory disease characterized by arthritis and systemic manifestations. The role of natural killer (NK) cells in the pathogenesis of systemic JIA remains unclear. The purpose of this study was to perform a comprehensive analysis of NK cell phenotype and functionality in patients with systemic JIA., Methods: Transcriptional alterations specific to NK cells were investigated by RNA sequencing of highly purified NK cells from 6 patients with active systemic JIA and 6 age-matched healthy controls. Cytokines (NK cell-stimulating and others) were quantified in plasma samples (n = 18). NK cell phenotype and cytotoxic activity against tumor cells were determined (n = 10), together with their interferon-γ (IFNγ)-producing function (n = 8)., Results: NK cells from the systemic JIA patients showed an altered gene expression profile compared to cells from the healthy controls, with enrichment of immunoinflammatory pathways, increased expression of innate genes including TLR4 and S100A9, and decreased expression of immune-regulating genes such as IL10RA and GZMK. In the patients' plasma, interleukin-18 (IL-18) levels were increased, and a decreased ratio of IFNγ to IL-18 was observed. NK cells from the patients exhibited specific alterations in the balance of inhibitory and activating receptors, with decreased killer cell lectin-like receptor G1 and increased NKp44 expression. Although NK cells from the patients showed increased granzyme B expression, consistent with intact cytotoxicity and degranulation against a tumor cell line, decreased granzyme K expression in CD56 bright NK cells and defective IL-18-induced IFNγ production and signaling were demonstrated., Conclusion: NK cells are active players in the inflammatory environment typical of systemic JIA. Although their cytotoxic function is globally intact, subtle defects in NK-related pathways, such as granzyme K expression and IL-18-driven IFNγ production, may contribute to the immunoinflammatory dysregulation in this disease., (© 2016, American College of Rheumatology.)

Haemophagocytic lymphohistiocytosis (HLH) comprises a heterogeneous spectrum of hyperinflammatory conditions that are inherited (primary HLH) or acquired in a context of infections, malignancies or autoimmune/autoinflammatory disorders (secondary HLH). Genetic defects in the cytotoxic machinery of natural killer and CD8(+) T cells underlie primary HLH, with residual cytotoxicity determining disease severity. Improved sequencing techniques have expanded the range of causal mutations and have redefined many cases of secondary HLH as primary HLH and vice versa, blurring the distinction between both subtypes. These insights allow HLH to be conceptualized as a threshold disease, in which interplay between various genetic and environmental factors causes progressive inflammation into a critical point, beyond which uncontrolled activation of immune cells and excessive cytokine production give rise to the cardinal symptoms of HLH. Various pathogenic pathways may thus converge to a common end stage of fulminant HLH., (© 2016 John Wiley & Sons Ltd.)

The cytokine storm syndrome 'haemophagocytic lymphohistiocytosis' (HLH) is an under-recognized hyperinflammatory disorder, causing high morbidity and mortality risk in children and adults. It can be subdivided into a primary, genetic form and a secondary, acquired form that complicates diverse infections, malignancies and autoimmune or autoinflammatory disorders. Both subtypes present with the same spectrum of non-specific symptoms, making accurate diagnosis and rapid treatment initiation challenging. In the last decade, increased awareness and international collaborative efforts fuelled a marked progress in diagnostic protocols and novel treatment strategies for HLH and new diagnostic guidelines are being tailored to specific secondary HLH subtypes. Therapy is gradually shifting its focus from overall immunosuppression towards targeting specific cytokines, cell types or signalling pathways underlying pathophysiology. Nevertheless, continued research efforts remain indispensable to customize therapy to individual patient needs., (© 2016 John Wiley & Sons Ltd.)

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening immunological disorder that is characterized by systemic inflammation, widespread organ damage, and hypercytokinemia. Primary HLH is caused by mutations in granule-mediated cytotoxicity, whereas secondary HLH occurs, without a known genetic background, in a context of infections, malignancies, or autoimmune and autoinflammatory disorders. Clinical manifestations of both HLH subtypes are often precipitated by a viral infection, predominantly with Herpesviridae. Exploiting this knowledge, we established an animal model of virus-associated secondary HLH by infecting immunocompetent wild-type mice with the β-herpesvirus murine CMV. C57BL/6 mice developed a mild inflammatory phenotype, whereas BALB/c mice displayed the clinicopathologic features of HLH, as set forth in the Histiocyte Society diagnostic guidelines: fever, cytopenia, hemophagocytosis, hyperferritinemia, and elevated serum levels of soluble CD25. BALB/c mice also developed lymphadenopathy, liver dysfunction, and decreased NK cell numbers. Lymphoid and myeloid cells were in a hyperactivated state. Nonetheless, depletion of CD8(+) T cells could not inhibit or cure the HLH-like syndrome, highlighting a first dissimilarity from mouse models of primary HLH. Immune cell hyperactivation in BALB/c mice was accompanied by a cytokine storm. Notably, plasma levels of IFN-γ, a key pathogenic cytokine in models of primary HLH, were the highest. Nevertheless, murine CMV-infected IFN-γ-deficient mice still developed the aforementioned HLH-like symptoms. In fact, IFN-γ-deficient mice displayed a more complete spectrum of HLH, including splenomegaly, coagulopathy, and decreased NK cell cytotoxicity, indicating a regulatory role for IFN-γ in the pathogenesis of virus-associated secondary HLH as opposed to its central pathogenic role in primary HLH., (Copyright © 2016 by The American Association of Immunologists, Inc.)

Objectives: Indoleamine 2,3-dioxygenase-1 (IDO1) is an immune-modulatory enzyme that catalyzes the degradation of tryptophan (Trp) to kynurenine (Kyn) and is strongly induced by interferon (IFN)-γ. We previously reported highly increased levels of IFN-γ and corresponding IDO activity in patients with hemophagocytic lymphohistiocytosis (HLH), a hyper-inflammatory syndrome. On the other hand, IFN-γ and IDO were low in patients with systemic juvenile idiopathic arthritis (sJIA), an autoinflammatory syndrome. As HLH can occur as a complication of sJIA, the opposing levels of both IFN-γ and IDO are remarkable. In animal models for sJIA and HLH, the role of IFN-γ differs from being protective to pathogenic. In this study, we aimed to unravel the role of IDO1 in the pathogenesis of sJIA and HLH., Methods: Wild-type and IDO1-knockout (IDO1-KO) mice were used in 3 models of sJIA or HLH: complete Freund's adjuvant (CFA)-injected mice developed an sJIA-like syndrome and secondary HLH (sHLH) was evoked by either repeated injection of unmethylated CpG oligonucleotide or by primary infection with mouse cytomegalovirus (MCMV). An anti-CD3-induced cytokine release syndrome was used as a non-sJIA/HLH control model., Results: No differences were found in clinical, laboratory and hematological features of sJIA/HLH between wild-type and IDO1-KO mice. As IDO modulates the immune response via induction of regulatory T cells and inhibition of T cell proliferation, we investigated both features in a T cell-triggered cytokine release syndrome. Again, no differences were observed in serum cytokine levels, percentages of regulatory T cells, nor of proliferating or apoptotic thymocytes and lymph node cells., Conclusions: Our data demonstrate that IDO1 deficiency does not affect inflammation in sJIA, sHLH and a T cell-triggered cytokine release model. We hypothesize that other tryptophan-catabolizing enzymes like IDO2 and tryptophan 2,3-dioxygenase (TDO) might compensate for the lack of IDO1.

Hemophagocytic lymphohistiocytosis (HLH) comprises a group of life-threatening immune disorders classified into primary or secondary HLH. The former is caused by mutations in genes involved in granule-mediated cytotoxicity, the latter occurs in a context of infections, malignancies or autoimmune/autoinflammatory disorders. Both are characterized by systemic inflammation, severe cytokine storms and immune-mediated organ damage. Despite recent advances, the pathogenesis of HLH remains incompletely understood. Animal models resembling different subtypes of HLH are therefore of great value to study this disease and to uncover novel treatment strategies. In this review, all known animal models of HLH will be discussed, highlighting findings on cell types, cytokines and signaling pathways involved in disease pathogenesis and extrapolating therapeutic implications for the human situation., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Objective: To report baseline articular, functional and ocular findings of the first international prospective cohort study of Blau syndrome (BS)., Methods: Three-year, multicentre, observational study on articular, functional (HAQ, Childhood HAQ and VAS global and pain), ophthalmological, therapeutic and radiological data in BS patients., Results: Baseline data on the first 31 recruited patients (12 females and 19 males) from 18 centres in 11 countries are presented. Of the 31 patients, 11 carried the p.R334W NOD2 mutation, 9 the p.R334Q and 11 various other NOD2 missense mutations; 20 patients were sporadic and 11 from five BS pedigrees. Median disease duration was 12.8 years (1.1-57). Arthritis, documented in all but one patient, was oligoarticular in 7, polyarticular in 23. The median active joint count was 21. Functional capacity was normal in 41%, mildly impaired in 31% and moderate-severe in 28% of patients. The most frequently involved joints at presentation were wrists, ankles, knees and PIPs. On radiographs, a symmetrical non-erosive arthropathy was shown. Previously unknown dysplastic bony changes were found in two-thirds of patients. Ocular disease was documented in 25 of 31 patients, with vitreous inflammation in 64% and moderate-severe visual loss in 33%. Expanded manifestations (visceral, vascular) beyond the classic clinical triad were seen in 52%., Conclusion: BS is associated with severe ocular and articular morbidity. Visceral involvement is common and may be life-threatening. Bone dysplastic changes may show diagnostic value and suggest a previously unknown role of NOD2 in bone morphogenesis. BS is resistant to current drugs, suggesting the need for novel targeted therapies., (© The Author 2014. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Systemic juvenile idiopathic arthritis (sJIA) is a severe inflammatory childhood disorder, characterized by a specific pattern of systemic features and a typical cytokine profile. Patients are at risk to develop macrophage activation syndrome (MAS), an acute life-threatening condition defined by excessive proliferation and activation of macrophages and T cells. Defects of unknown cause in the natural killer (NK) cell cytotoxic capacity are presumed to underlie the pathogenesis of MAS and have been detected in sJIA patients. Here, we provide an overview of the cytokine profiles in sJIA and related mouse models. We discuss the influence of cytokines on NK cell function, and hypothesize that NK cell dysfunction in sJIA is caused by altered cytokine profiles., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Blau syndrome is a monogenic disease resulting from mutations in the pattern recognition receptor NOD2, and is phenotypically characterized by the triad of granulomatous polyarthritis, dermatitis and uveitis. This paper reviews briefly the classical clinical features of the disease, as well as more recently described extra-triad symptoms. From an ongoing prospective multicenter study, we provide new data on the natural history of Blau syndrome, focusing on functional status and visual outcome. We also present an update of the range of different NOD2 mutations found in Blau syndrome as well as recent data on morphologic and immunohistochemical characteristics of the Blau granuloma. Finally, emerging insights into pathogenic mechanisms including activation of NOD2 signal transduction, and potential biomarkers of disease activity are discussed.

Objective: Systemic juvenile idiopathic arthritis (JIA) is unique among the rheumatic diseases of childhood, given its distinctive systemic inflammatory character. Inappropriate control of innate immune responses following an initially harmless trigger is thought to account for the excessive inflammatory reaction. The aim of this study was to generate a similar systemic inflammatory syndrome in mice by injecting a relatively innocuous, yet persistent, immune system trigger: Freund's complete adjuvant (CFA), containing heat-killed mycobacteria., Methods: Given the central role of interferon-γ (IFNγ) in immune regulation, we challenged wild-type (WT) and IFNγ-knockout (KO) BALB/c mice with CFA, and analyzed their clinical symptoms and biologic characteristics. The production of cytokines and the effects of anticytokine antibodies were investigated., Results: In WT mice, CFA injection resulted in splenomegaly, lymphadenopathy, neutrophilia, thrombocytosis, and increased cytokine expression. In the absence of IFNγ, these symptoms were more pronounced and were accompanied by weight loss, arthritis, anemia, hemophagocytosis, abundance of immature blood cells, and increased levels of interleukin-6 (IL-6), all of which are reminiscent of the symptoms of systemic JIA. CFA-challenged IFNγ-KO mice showed increased expression of IL-17 by CD4+ T cells and by innate γ/δ T cells. Inflammatory and hematologic changes were prevented by treatment with anti-IL-12/IL-23p40 and anti-IL-17 antibodies., Conclusion: Immune stimulation of IFNγ-KO mice with CFA produces a systemic inflammatory syndrome reflecting the clinical, biologic, and histopathologic picture of systemic JIA. The protective function of IFNγ in preventing anemia and overall systemic inflammation is a striking observation. The finding that both adaptive and innate T cells are important sources of IL-17 may be of relevance in the pathogenesis of systemic JIA., (Copyright © 2014 by the American College of Rheumatology.)

Genome-wide studies may lead to the discovery of genetic variants of potential clinical importance beyond the aims of the study. We performed single nucleotide polymorphism array analysis in a boy with oculocutaneous albinism to identify copy-neutral regions of homozygosity harboring genes involved in melanin biosynthesis. An unanticipated homozygous deletion of chromosome 5p13.3 was discovered, encompassing not only the OCA gene SLC45A2, but also four additional genes. This led to an unexpected presymptomatic diagnosis of alpha-methylacyl-CoA racemase deficiency in the same patient., (Copyright © 2012 Wiley Periodicals, Inc.)

Objective: To put forward a new concept--Blau arteritis, a form of large-vessel vasculitis phenotypically related to Takayasu disease but genetically and clinically part of an expanded phenotype of Blau syndrome., Methods: We provide a clinical description of a new case and summarize previously published cases of arteritis associated with Blau syndrome. Genetic testing was performed by direct sequencing of exon 4 of the NOD2 gene., Results: The case described and those reviewed from the literature demonstrate the emerging phenotype of Takayasu-like arteritis in patients with Blau syndrome. Although most patients described to date depict an otherwise classic Blau syndrome phenotype, the current case was atypical in that the predominant features were arteritic. A novel substitution, G464W, in a highly conserved position near the nucleotide oligomerization domain of the NOD2 protein is also described., Conclusion: Blau arteritis can be observed in the context of both typical and atypical (incomplete) Blau syndrome. The associated mutation in the NOD2 gene raises the question of the potential importance of this gene among patients with "primary" forms of Takayasu arteritis.

Aims: Most patients (98%) with Friedreich's ataxia (FRDA) are homozygous for the GAA repeat expansion in FXN. Only a few compound heterozygous patients with an expanded repeat on one allele and a point mutation or an intragenic FXN deletion on the other allele are described. In a minority of the patients only a heterozygous pattern of the repeat expansion can be detected. Using array analysis after GAA repeat expansion testing, we identified a FRDA patient who is compound heterozygous for an expanded GAA repeat and a complete FXN deletion. Since not only repeat expansions and point mutations, but also large rearrangements can be the underlying cause of FRDA, a quantitative test should also be performed in case a patient shows only one allele with an expanded GAA repeat in FXN.

Objectives: To investigate the functional status of difficult-to-treat JIA patients, including patients receiving biotherapies, and to correlate functional status to disease activity., Methods: All JIA patients consecutively evaluated in a paediatric rheumatology referral centre (November 2008 to March 2009) were enrolled in an observational cross-sectional study. The Childhood HAQ (CHAQ), physician's assessment of overall disease activity, parent's assessment of well-being and pain, and active and limited joint numbers were measured., Results: We enrolled 95 patients [27% systemic, 29% polyarticular, 22% enthesitis-related arthritis (ERA) and 23% oligoarticular JIA]. Median disease duration was 3.5 years. Treatment included NSAIDs (56%), MTX (23%), CSs (21%) and biologics (45%). Of all patients, 31 and 56%, respectively, had inactive and minimally active disease. The median CHAQ score was 0.375 (range 0-3). Most patients had no or mild functional disability (61%), impaired well-being (63%) or pain (55%); 10% reported severely impaired function and well-being, 19% severe pain. ERA patients reported worse well-being and pain. CHAQ scores correlated with disease activity. Long-lasting disease and biologic treatment were associated with better well-being and pain scores., Conclusion: Despite the high proportion of severe JIA patients in this cohort, CHAQ values are within the lower range of recent reports, probably related to new therapeutic approaches. Impaired function and well-being remain a challenge for at least 10% of the patients. Impaired well-being and pain in ERA patients require further study. The strong correlation between functional status and well-being underlines the importance of improving function to optimize quality of life.

Background: Blau syndrome (BS) and Crohn disease (CD) are both characterized by granulomatous inflammation and related to nucleotide oligomerization domain 2 (NOD2) mutations., Objective: This study aimed to define the morphologic and immunohistochemical characteristics of granulomas in patients with NOD2-related BS and CD., Methods: Granuloma-containing biopsy specimens from 6 patients with BS and 7 pediatric patients with CD carrying NOD2 mutations or single nucleotide polymorphisms were studied for morphology, cellular composition, and cytokine expression by using hematoxylin and eosin staining and immunohistochemistry., Results: Biopsy specimens from patients with BS typically showed polycyclic granulomas with large lymphocytic coronas, extensive emperipolesis of lymphocytes within multinucleated giant cells (MGCs), MGC death, and fibrinoid necrosis and fibrosis. In contrast, biopsy specimens from patients with CD showed simple granulomas with subtle/absent lymphocytic coronas, sclerosis of the surrounding tissue, and polymorphonuclear cells. Findings found to be similar in all granulomas were as follows: CD68 and HLA-DR expression by epithelioid cells, monocyte-macrophage lineage cells and MGCs, increased lymphocytic HLA-DR expression, increased CD4(+)/CD8(+) T-cell ratio, and CD20(+) B lymphocytes evenly distributed within and around granulomas. In both patient groups prominent IFN-γ expression was found in and around granulomas, and TNF-α and IL-23 receptor expression was moderate. IL-6, IL-17, and TGF-β expression was prominent in granulomas from patients with BS but sporadic in granulomas from patients with CD. IL-10 expression was absent., Conclusion: Granulomas from patients with BS and granulomas from patients with NOD2-associated CD show distinct morphologic features and cytokine expression patterns, suggesting that the T(H)17 axis might be involved in the pathogenesis of BS, whereas T(H)1 is important in both patients with BS and patients with CD., (Copyright © 2012 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.)

'Apparent non-penetrance' occurs in several genetic disorders, including tuberous sclerosis complex and neurofibromatosis type 1: clinically unaffected parents may have multiple affected offspring. Germ line or somatic mosaicism in one of the parents of the index patient is the probable cause and results in an enhanced recurrence risk. Therefore, it is of great importance to use the most sensitive technology for testing DNA of the parents of the index patient for the presence/absence of the familial mutation. To detect large rearrangements multiplex ligation-depending probe amplification (MLPA) is often used. Here we show that MLPA is less sensitive in detecting low-grade somatic mosaicism than fluorescence in situ hybridization (FISH) or a mutation-specific PCR test. Therefore, we recommend FISH (if possible) or PCR analysis for the analysis of parental DNA.

Purpose of Review: Blau syndrome is a monogenic disease resulting from mutations in nucleotide oligomerization domain 2 (NOD2) and is phenotypically characterized by granulomatous polyarthritis and uveitis. Not only there has been significant progress in disease characterization but also the biological pathways associated with NOD2 and related proteins of the innate immunity are better understood., Recent Findings: The phenotype of Blau syndrome has proven to be more complex than initially thought. A discussion on those manifestations will be provided in the clinical sections of this review. As more patients and pedigrees are found new mutations in the NOD2 gene have emerged and we discuss them in some detail. Due to its importance in Crohn's disease NOD2 has become the focus of intense research. A brief review of more recent advances in relevant pathways is presented and published reviews referenced for the interested reader. The granulomatous character of Blau syndrome provides an opportunity to look at possible pathogenic effects of NOD2 'gain of function'. New immunohistochemical data are briefly reviewed as well., Summary: Elucidation of downstream effects of NOD2 mutations could provide valuable clues to mechanisms of arthritis and uveitis in general as well as granulomatous diseases in particular.

Mutations in the F-box only protein 7 gene (FBXO7) cause PARK15, an autosomal recessive neurodegenerative disease presenting with severe levodopa-responsive parkinsonism and pyramidal disturbances. Understanding the PARK15 pathogenesis might thus provide clues on the mechanisms of maintenance of brain dopaminergic neurons, the same which are lost in Parkinson's disease. The protein(s) encoded by FBXO7 remain very poorly characterized. Here, we show that two protein isoforms are expressed from the FBXO7 gene in normal human cells. The isoform 1 is more abundant, particularly in primary skin fibroblasts. Both isoforms are undetectable in cell lines from the PARK15 patient of an Italian family; the isoform 1 is undetectable and the isoform 2 is severely decreased in the patients from a Dutch PARK15 family. In human cell lines and mouse primary neurons, the endogenous or over-expressed, wild type FBXO7 isoform 1 displays mostly a diffuse nuclear localization. An intact N-terminus is needed for the nuclear FBXO7 localization, as N-terminal modification by PARK15-linked missense mutation, or N-terminus tag leads to cytoplasmic mislocalization. Furthermore, the N-terminus of wild type FBXO7 (but not of mutant FBXO7) is able to confer nuclear localization to profilin (a cytoplasmic protein). Our data also suggest that overexpressed mutant FBXO7 proteins (T22M, R378G and R498X) have decreased stability compared to their wild type counterpart. In human brain, FBXO7 immunoreactivity was highest in the nuclei of neurons throughout the cerebral cortex, intermediate in the globus pallidum and the substantia nigra, and lowest in the hippocampus and cerebellum. In conclusion, the common cellular abnormality found in the PARK15 patients from the Dutch and Italian families is the depletion of the FBXO7 isoform 1, which normally localizes in the cell nucleus. The activity of FBXO7 in the nucleus appears therefore crucial for the maintenance of brain neurons and the pathogenesis of PARK15.

Objectives: To identify juvenile idiopathic arthritis (JIA) patients who developed IBD during treatment with anti-TNF-alpha agents and better characterize the IBD clinical and pathological presentation., Methods: A retrospective French multicentre study included patients with a diagnosis of JIA according to the ILAR criteria who developed IBD while under anti-TNF-alpha therapy before 18 years of age. Intestinal biopsies were collected and reviewed by the same pathologist., Results: Eight patients were included. They had been treated with etanercept from 11 to 78 months before IBD onset. Gastro-intestinal symptoms included abdominal pain (six patients), diarrhoea (four patients), anorexia (four patients), anal abscess (three patients) and oral ulcers (one patient). Five patients presented with Crohn's disease (CD) and three with indeterminate IBD, of whom four had severe pancolitis. Clinical remission of IBD was obtained in all patients after discontinuation of etanercept and initiation of IBD-specific therapy, including infliximab in six patients., Conclusion: IBD must be suspected in JIA patients treated with etanercept who develop intestinal symptoms, including anal abscess. This series raises the possibility of a relationship between etanercept therapy and the occurrence of IBD in a subset of patients with JIA.

Objectives: Chronic inflammation in juvenile idiopathic arthritis interferes with linear growth and bone mass acquisition. We prospectively evaluated and compared linear growth and evolution of bone mass acquisition and body composition in MTX-resistant polyarticular-course JIA (polyJIA) patients started on etanercept and in recently diagnosed polyJIA patients started on MTX monotherapy., Methods: Sixteen MTX-resistant polyJIA patients were given add-on etanercept, eight recently diagnosed polyJIA patients were started on MTX. Patients were evaluated at baseline and at 1, 6, 12 and 18 months with respect to disease activity, linear growth, BMD and body composition., Results: Baseline patient and disease characteristics were similar in both groups. Clinical disease activity (Pediatric ACR30) was equally well controlled in both groups. Growth velocity increased significantly allowing catch-up growth in the etanercept + MTX group only. BMD (lumbar spine Z-score) improved significantly in both groups. A significant increase of bone mineral content and lean:fat mass ratio was seen in the etanercept + MTX group, but not in the MTX group., Conclusion: Clinical control of disease activity by etanercept in MTX-refractory polyJIA is associated with rapidly instituted catch-up growth and improvement of bone mineralization and body composition. In recently diagnosed polyJIA patients treated with MTX the relation between clinical response and these parameters was less evident. Preliminary data on serum IL-6 and osteoprotegerin levels indicate that the beneficial effects seen with etanercept therapy may be related to its control of systemic IL-6 production and enhancement of osteoblast activity.

Background: Carrier status of a structural balanced chromosome abnormality is associated with recurrent miscarriage. There is, at present, no evidence of the impact of the sequence of preceding pregnancies on the probability of carrier status. The aim of our study was therefore to examine whether the history of consecutive versus non-consecutive miscarriages in couples with two or more miscarriages has any impact on the probability of carrying a chromosome abnormality., Methods: A nested case-control study was performed in six centres for clinical genetics in the Netherlands. Couples referred for chromosome analysis after two or more miscarriages were included: 279 couples with a carrier of a structural chromosomal abnormality and 428 non-carrier couples who served as controls. Univariable and multivariable logistic regression analyses, corrected for known risk factors for carrier status, were performed. The main outcome measure was the probability of carrier status., Results: Two hundred and fifty-six of 279 (92%) carrier couples and 381 of 428 (89%) non-carrier couples had experienced consecutive miscarriages (P = 0.21). A history of two or three consecutive miscarriages did not alter the probability of carrier status when compared with two [odds ratio (OR) 0.90, 95% confidence interval (CI) 0.48-1.7] or three (OR 0.71, 95% CI 0.39-1.3) non-consecutive miscarriages., Conclusions: The sequence of preceding pregnancies is not a risk factor for carrier status. Therefore, couples with miscarriages interspersed with healthy child(ren) should be managed the same as couples with consecutive miscarriages regarding chromosome diagnosis.

We present a family with multiple cytogenetic abnormalities, identified through a girl with several dysmorphic features and cardiac problems, suspected for Jacobsen syndrome. Cytogenetic analysis showed a 46,XX,del(11)(qter) karyotype, which was confirmed by fluorescence in situ hybridization (FISH). Cytogenetic investigation of the parents showed a chromosome aberration in both: the father had a t(11;12)(p13;q22) translocation and the mother was carrier of an ins(4;11)(p14;q24q25). FISH analysis with an 11q-subtelomeric probe from the second-generation telomere clone set and BACs from 11q24-q25 suggested a complex maternal rearrangement. However, subsequent array analysis showed a single interstitial deletion in the proband, derived from the maternal insertion. The aberrant karyotypes in both parents implicated an increased risk of unbalanced fetal chromosome composition, thus high risk for a child with multiple congenital abnormalities. Therefore, during the next pregnancy, the couple opted for prenatal diagnosis by means of amniocentesis. An interphase FISH strategy for uncultured amniotic fluid cells predicted two possible unbalanced fetal chromosome constitutions. Karyotyping of cultured amniotic cells confirmed one of the predicted unbalanced cytogenetic options, demonstrating the value of a fast interphase strategy for parents who both are carriers of a chromosomal abnormality. In addition, we present an overview of patients with Jacobsen syndrome and an interstitial 11q deletion reported thus far in literature.

Background: The combination of early-onset, progressive parkinsonism with pyramidal tract signs has been known as pallido-pyramidal or parkinsonian-pyramidal syndrome since the first description by Davison in 1954. Very recently, a locus was mapped in a single family with an overlapping phenotype, and an FBXO7 gene mutation was nominated as the likely disease cause., Methods: We performed clinical and genetic studies in two families with early-onset, progressive parkinsonism and pyramidal tract signs., Results: An FBXO7 homozygous truncating mutation (Arg498Stop) was found in an Italian family, while compound heterozygous mutations (a splice-site IVS7 + 1G/T mutation and a missense Thr22Met mutation) were present in a Dutch family. We also found evidence of expression of novel normal splice-variants of FBXO7. The phenotype associated with FBXO7 mutations consisted of early-onset, progressive parkinsonism and pyramidal tract signs, thereby matching clinically the pallido-pyramidal syndrome of Davison. The parkinsonism exhibits varying degrees of levodopa responsiveness in different patients., Conclusions: We conclusively show that recessive FBXO7 mutations cause progressive neurodegeneration with extrapyramidal and pyramidal system involvement, delineating a novel genetically defined entity that we propose to designate as PARK15. Understanding how FBXO7 mutations cause disease will shed further light on the molecular mechanisms of neurodegeneration, with potential implications also for more common forms of parkinsonism, such as Parkinson disease and multiple system atrophy.

Although the diagnosis of spondyloenchondrodysplasia (SPENCD) can only be made in the presence of characteristic metaphyseal and vertebral lesions, a recent report has highlighted the pleiotropic manifestations of this disorder which include significant neurological involvement and variable immune dysfunction. Here we present two patients, one of whom was born to consanguineous parents, further illustrating the remarkable clinical spectrum of this disease. Although both patients demonstrated intracranial calcification, they were discordant for the presence of mental retardation, spasticity and white matter abnormalities. And whilst one patient had features consistent with diagnoses of Sjögren syndrome, polymyositis, hypothyroidism and severe scleroderma, the other patient had clinical manifestations and an autoantibody profile of systemic lupus erythematosus. These cases further illustrate the association of SPENCD with immune dysregulation and highlight the differential diagnosis with Aicardi-Goutières syndrome and other disorders associated with the presence of intracranial calcification. Undoubtedly, identification of the underlying molecular and pathological basis of SPENCD will provide important insights into immune and skeletal regulation., (Copyright 2008 Wiley-Liss, Inc.)

We report on 4 children with infantile-onset lobular panniculitis, high fever, uveitis, and systemic granulomatous inflammation, recruited through the International Registry of Pediatric Granulomatous Arthritis. Neither CARD15 nor CIAS1 mutations were found. Despite immunosuppressive therapy, disease course was progressive. Response to anti-tumor necrosis factor monoclonal antibody in 3 patients is of note.

Most people with Williams syndrome (WS) have a heterozygous 1.55 Mb deletion on chromosome 7q11.23. For diagnostic purposes, fluorescence in situ hybridisation (FISH) with commercial FISH probes is commonly used to detect this deletion. We investigated whether multiplex ligation-dependent probe amplification (MLPA) is a reliable alternative for FISH. The MLPA kit (SALSA P029) contains probes for eight genes in the WS critical region: FKBP6, FZD9, TBL2, STX1A, ELN, LIMK1, RFC2, and CYLN2. The experimental FISH assay that was used consists of four probes covering the WS critical region. A total number of 63 patients was tested; in 53 patients, a deletion was detected both with FISH and MLPA(P029), in 10 patients both techniques failed to demonstrate a deletion. In only one patient, a deletion was detected which was not previously detected by two commercial FISH probes. This patient appeared to carry a small, atypical deletion. We conclude that MLPA is a reliable technique to detect WS. Compared with FISH, MLPA is less time consuming and has the possibility to detect also smaller, atypical deletions and duplications in the WS critical region.