Type I Interferonopathies in Children: An Overview

Nonverbal Cognitive Skills in Children With Aicardi Goutières Syndrome

BACKGROUND AND OBJECTIVES

Aicardi Goutières syndrome (AGS) is type I interferonopathy characterized by severe neurologic impairment. Although many children with AGS demonstrate motor and expressive language deficits, the magnitude of receptive language impairment is uncharacterized. We sought to characterize cognitive function in AGS-affected children using assessment tools with reduced dependence on motor abilities and compare cognitive testing outcomes with overall severity and parental assessment of adaptive behavior.

METHODS

We performed a cross-sectional study. Children were recruited as part of the Myelin Disorders Biorepository Project at the Children's Hospital of Philadelphia. We included individuals with a confirmed diagnosis of AGS. We administered the Leiter International Performance Scale, third edition (Leiter-3), and the Vineland Adaptive Behavior Scale, third edition (VABS-3), in the context of research encounters. Motor skills were categorized by AGS Severity Scale mobility levels. Descriptive statistics and Spearman's rank correlation were used to compare assessments. Mann-Whitney and Kruskal-Wallis tests with correction with Dunn's multiple comparison test were used to compare test performance between mobility groups.

RESULTS

Cognitive and adaptive behavior performance was captured in 57 children. The mean age at encounters was 8.51 (SD 5.15) years. The median (IQR) Leiter-3 score was 51 (interquartile range [IQR] 60), with administration failure in 20 of 57 (35%) individuals. On the VABS-3, the Motor Domain (median 29, IQR 36.25) was more impacted than the Communication (median 50, IQR 52), Daily Living Skills (median 52, IQR 31), and Socialization (median 54, IQR 40) Domains (p < 0.0001). The AGS Scale correlated with VABS-3 (r = 0.86, p < 0.0001) and Leiter-3 (r = 0.87, p < 0.0001). There was correlation between VABS-3 Domains and Leiter-3 (r-range 0.83-0.97). Gross motor and fine motor categories, respectively, correlated with VABS-3 (H = 39.37, p < 0.0001; U = 63, p < 0.0001) and Leiter-3 (H = 40.43, p < 0.0001; U = 66, p < 0.0001). Within each gross motor and fine motor category of the AGS Scale, a subset of children scored within normal IQ range.

DISCUSSION

Parental assessment of function by the VABS-3 correlated with directly assessed performance measures. Our data underscore the potential value of VABS-3 and Leiter-3 as tools to assess psychometric function in AGS. With a deeper understanding of our patients' abilities, we can better guide clinicians and families to provide appropriate support and personalized interventions to empower children with leukodystrophies to maximize their communication and educational potential.

Type I interferon pathway in pediatric systemic lupus erythematosus

BACKGROUND

The role of type I interferon (IFN-I) signaling in systemic lupus erythematosus (SLE) has been well established. However, unanswered questions remain regarding the applicability of these findings to pediatric-onset SLE. The aim of this review is to provide an overview of the novel discoveries on IFN-I signaling in pediatric-onset SLE.

DATA SOURCES

A literature search was conducted in the PubMed database using the following keywords: "pediatric systemic lupus erythematosus" and "type I interferon".

RESULTS

IFN-I signaling is increased in pediatric SLE, largely due to the presence of plasmacytoid dendritic cells and pathways such as cyclic GMP-AMP synthase-stimulator of interferon genes-TANK-binding kinase 1 and Toll-like receptor (TLR)4/TLR9. Neutrophil extracellular traps and oxidative DNA damage further stimulate IFN-I production. Genetic variants in IFN-I-related genes, such as IFN-regulatory factor 5 and tyrosine kinase 2, are linked to SLE susceptibility in pediatric patients. In addition, type I interferonopathies, characterized by sustained IFN-I activation, can mimic SLE symptoms and are thus important to distinguish. Studies on interferonopathies also contribute to exploring the pathogenesis of SLE. Measuring IFN-I activation is crucial for SLE diagnosis and stratification. Both IFN-stimulated gene expression and serum IFN-α2 levels are common indicators. Flow cytometry markers such as CD169 and galectin-9 are promising alternatives. Anti-IFN therapies, such as sifalimumab and anifrolumab, show promise in adult patients with SLE, but their efficacy in pediatric patients requires further investigation. Janus kinase inhibitors are another treatment option for severe pediatric SLE patients.

CONCLUSIONS

This review presents an overview of the IFN-I pathway in pediatric SLE. Understanding the intricate relationship between IFN-I and pediatric SLE may help to identify potential diagnostic markers and targeted therapies, paving the way for improved patient care and outcomes.

Elucidating the function of STING in systemic lupus erythematosus through the STING Goldenticket mouse mutant

The complexity of systemic lupus erythematosus (SLE) arises from intricate genetic and environmental interactions, with STING playing a pivotal role. This study aims to comprehend the function of STING using the pristane-induced lupus (PIL) model in Sting missense mutant mice (Goldenticket or StingGt), which contrasts with previous research using Sting knockout mice. Investigating two-month-old StingGt mice over six months post-PIL induction, we observed a profound reduction in autoimmune markers, including antinuclear and anti-dsDNA antibodies, germinal center B cells, and plasma cells, compared to their wild-type counterparts. A pivotal finding was the marked decrease in IL-17-producing T cells. Notably, the severity of lupus nephritis and pulmonary hemorrhages was significantly diminished in StingGt mice. These findings demonstrate that different genetic approaches to interfere with STING signaling can lead to contrasting outcomes in SLE pathogenesis, which highlights the need for a nuanced understanding of the role of STING in drug development for SLE. In summary, the loss of Sting function in Goldenticket mutant mice rescued autoimmune phenotypes in PIL. This study reveals the critical nature of STING in SLE, suggesting that the method of STING modulation significantly influences disease phenotypes and should be a key consideration in developing targeted therapies.

IFN-I Score and Rare Genetic Variants in Children with Systemic Lupus Erythematosus

Introduction: Interferon I (IFN I) signaling hyperactivation is considered one of the most important pathogenetic mechanisms in systemic lupus erythematosus (SLE). Early manifestation and more severe SLE courses in children suggest a stronger genetic influence in childhood-onset SLE (cSLE). Aim: To evaluate IFN-I score and SLE-associated genetic variants in cSLE. Material and Methods: 80 patients with cSLE were included in the study. IFN I-score was assessed by real-time PCR quantitation of 5 IFN I-regulated transcripts (IFI44L, IFI44, IFIT3, LY6E, MXA1) in 60 patients. Clinical exome sequencing (CES) was performed in 51 patients. Whole-exome sequencing was performed in 32 patients with negative results of CES. Results: 46/60 patients (77%) had elevated IFN-I scores. Leucopenia and skin involvement were associated with over-expression of IFI44 and IFI44L, while hypocomplementemia-with hyperactivation of IFIT3, LY6E, and MX1. No correlation of IFN-I score with disease activity was found. At least one rare genetic variant, potentially associated with SLE, was found in 29 (56.9%) patients. The frequency of any SLE-genetic variants in patients with increased IFN scores was 84%, in patients with normal IFN scores-33%, and in the group whose IFN score was not assessed was 65% (p = 0.040). The majority of genetic variants (74%) are functionally related to nucleic acid sensing and IFN-signaling. The highest frequency of genetic variants was observed in Sakha patients (9/14; 64.3%); three and two unrelated patients had identical variants in PTPN22 and TREX1 genes, respectively. Conclusions: More than half of patients with childhood-onset SLE have rare variants in SLE-associated genes. The IFN-I score could be considered a tool for the selection of patients for further genetic assessment in whom monogenic lupus is suspected.

Neuroimaging Features of Cytokine-related Diseases

Cytokines are small secreted proteins that have specific effects on cellular interactions and are crucial for functioning of the immune system. Cytokines are involved in almost all diseases, but as microscopic chemical compounds they cannot be visualized at imaging for obvious reasons. Several imaging manifestations have been well recognized owing to the development of cytokine therapies such as those with bevacizumab (antibody against vascular endothelial growth factor) and chimeric antigen receptor (CAR) T cells and the establishment of new disease concepts such as interferonopathy and cytokine release syndrome. For example, immune effector cell-associated neurotoxicity is the second most common form of toxicity after CAR T-cell therapy toxicity, and imaging is recommended to evaluate the severity. The emergence of COVID-19, which causes a cytokine storm, has profoundly impacted neuroimaging. The central nervous system is one of the systems that is most susceptible to cytokine storms, which are induced by the positive feedback of inflammatory cytokines. Cytokine storms cause several neurologic complications, including acute infarction, acute leukoencephalopathy, and catastrophic hemorrhage, leading to devastating neurologic outcomes. Imaging can be used to detect these abnormalities and describe their severity, and it may help distinguish mimics such as metabolic encephalopathy and cerebrovascular disease. Familiarity with the neuroimaging abnormalities caused by cytokine storms is beneficial for diagnosing such diseases and subsequently planning and initiating early treatment strategies. The authors outline the neuroimaging features of cytokine-related diseases, focusing on cytokine storms, neuroinflammatory and neurodegenerative diseases, cytokine-related tumors, and cytokine-related therapies, and describe an approach to diagnosing cytokine-related disease processes and their differentials. ©RSNA, 2024 Supplemental material is available for this article.

Type I interferon regulates interleukin-1beta and IL-18 production and secretion in human macrophages

Inflammasomes are immune complexes whose activation leads to the release of pro-inflammatory cytokines IL-18 and IL-1β. Type I IFNs play a role in fighting infection and stimulate the expression of IFN-stimulated genes (ISGs) involved in inflammation. Despite the importance of these cytokines in inflammation, the regulation of inflammasomes by type I IFNs remains poorly understood. Here, we analysed RNA-sequencing data from patients with monogenic interferonopathies and found an up-regulation of several inflammasome-related genes. To investigate the effect of type I IFN on the inflammasome, we treated human monocyte-derived macrophages with IFN-α and observed an increase in CASP1 and GSDMD mRNA levels over time, whereas IL1B and NLRP3 were not directly correlated to IFN-α exposure time. IFN-α treatment reduced the release of mature IL-1β and IL-18, but not caspase-1, in response to ATP-mediated NLRP3 inflammasome activation, suggesting regulation occurs at cytokine expression levels and not the inflammasome itself. However, more studies are required to investigate how regulation by IFN-α occurs and impacts NLRP3 and other inflammasomes at both transcriptional and post-translational levels.

Macrocephaly and Finger Changes: A Narrative Review

Macrocephaly, characterized by an abnormally large head circumference, often co-occurs with distinctive finger changes, presenting a diagnostic challenge for clinicians. This review aims to provide a current synthetic overview of the main acquired and genetic etiologies associated with macrocephaly and finger changes. The genetic cause encompasses several categories of diseases, including bone marrow expansion disorders, skeletal dysplasias, ciliopathies, inherited metabolic diseases, RASopathies, and overgrowth syndromes. Furthermore, autoimmune and autoinflammatory diseases are also explored for their potential involvement in macrocephaly and finger changes. The intricate genetic mechanisms involved in the formation of cranial bones and extremities are multifaceted. An excess in growth may stem from disruptions in the intricate interplays among the genetic, epigenetic, and hormonal factors that regulate human growth. Understanding the underlying cellular and molecular mechanisms is important for elucidating the developmental pathways and biological processes that contribute to the observed clinical phenotypes. The review provides a practical approach to delineate causes of macrocephaly and finger changes, facilitate differential diagnosis and guide for the appropriate etiological framework. Early recognition contributes to timely intervention and improved outcomes for affected individuals.

Detection of genetic mutations underlying early-onset systemic lupus erythematosus

OBJECTIVE

We aimed to investigate the presence of monogenic causes of systemic lupus erythematosus (SLE) in our early-onset SLE patients.

METHODS

Fifteen pediatric SLE cases who had early disease onset (≤6 years) were enrolled in this study. All patients fulfilled the Systemic Lupus International Collaborating Clinics (SLICC) criteria. Genomic DNA was used for whole exome sequencing (WES). Pathogenic variants were confirmed by Sanger sequencing.

RESULTS

The median age at diagnosis of 15 early-onset SLE patients included in the study was 4 (2-6) years (F/M = 12/3). Significant gene mutations were detected in five of these patients (33.3%). Patients 1 and 2 with homozygous DNASE1L3 mutations [c.320+4_320+7del and G188 A (c.563 G>C) variants] had skin involvement and oral ulcers. One of them (patient 1) had arthritis and nephritis, and another (patient 2) had nonscarring alopecia and thrombocytopenia. They are currently clinically inactive but have positive serological findings. Patient 3 with homozygous pathogenic ACP5 mutation [G109 R (c.325 G>A) variant] had arthritis, nephritis, short stature, and skeletal dysplasia. Patient 4 with a heterozygote novel IFIH1 mutation [L809 F (c.2425 C>T) variant] had skin findings and leukopenia. Patient 5 with novel C1S variant [homozygous C147 W (c.441 C>G) variant] had marked skin findings, oral ulcers, nonscarring alopecia, pancytopenia, and low total hemolytic complement CH50 level. All patients have responded to the treatments and have low Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) scores, on therapy.

CONCLUSION

Genetic causes should be investigated in early-onset SLE, for better management and genetic counseling. On the other hand, multicenter studies may help to further define genotype-phenotype associations.

STING-associated vasculopathy with onset in infancy (SAVI) presenting with skin lesions

STING-associated vasculopathy with onset in infancy (SAVI) is caused by pathogenic gain-of-function variants in the gene TMEM173 (also named stimulator of interferon genes, STING1). This report details the case of an 11-year-old girl with SAVI who presented with skin-limited symptoms and discusses the phenotype-genotype correlations of the TMEM173 variant present in our patient. Treatment of SAVI focuses on preventing the development or progression of organ damage by reducing systemic inflammation. We summarize the available treatments for this syndrome.

Characterization of Fine Motor and Visual Motor Skills in Aicardi-Goutières Syndrome

Aicardi-Goutières syndrome is a genetic inflammatory disorder resulting in dispersed neurologic dysfunction. Despite a recognition of overall motor impairment, fine and visual motor skills are undercharacterized. We hypothesize that there is a spectrum of fine and visual motor skills in the Aicardi-Goutières syndrome population as captured by a standard outcome measure, the Peabody Developmental Motor Scales (PDMS-2), which will be proportional to overall disease severity.In a cohort of 74 subjects, the Peabody Developmental Motor Scales-2 grasping and visual-motor integration subtests were administered concurrently with the Aicardi-Goutières syndrome Severity Scale (severe [range 0-3], moderate [range 4-8], and attenuated [range 9-11]). The cohort was also compared by genotype and performance as defined by raw scores. The distribution of Peabody Developmental Motor Scales-2 scores within a genotype was assessed by interquartile ranges (IQRs).Peabody Developmental Motor Scales-2 grasping and visual-motor integration performance was the least variable in the TREX1-cohort (IQR: 10.00-12.00) versus the SAMHD1 and IFIH1 cohorts (IQR: 51.00-132.00 and 48.50-134.00, respectively). Neurologic severity highly correlated with both fine and visual motor skills (Spearman correlation: r = 0.87, 0.91, respectively). A floor effect (lowest 10% of possible scores) was observed within the severe cohort (n = 32/35), whereas a ceiling effect (top 10%) was observed in the attenuated cohort (n = 13/17).This study characterized the spectrum of fine and visual motor function in the Aicardi-Goutières syndrome population, which correlated with overall neurologic dysfunction. The Peabody Developmental Motor Scales-2 grasping and visual-motor integration showed promise as potential assessment tools in moderate and attenuated Aicardi-Goutières syndrome cohorts. A better understanding of fine and visual motor function in this population will benefit clinical care and clinical trial design.

Inborn errors of immunity: an expanding universe of disease and genetic architecture

Inborn errors of immunity (IEIs) are generally considered to be rare monogenic disorders of the immune system that cause immunodeficiency, autoinflammation, autoimmunity, allergy and/or cancer. Here, we discuss evidence that IEIs need not be rare disorders or exclusively affect the immune system. Namely, an increasing number of patients with IEIs present with severe dysregulations of the central nervous, digestive, renal or pulmonary systems. Current challenges in the diagnosis of IEIs that result from the segregated practice of specialized medicine could thus be mitigated, in part, by immunogenetic approaches. Starting with a brief historical overview of IEIs, we then discuss the technological advances that are facilitating the immunogenetic study of IEIs, progress in understanding disease penetrance in IEIs, the expanding universe of IEIs affecting distal organ systems and the future of genetic, biochemical and medical discoveries in this field.

Aicardi-Goutières Syndrome with Congenital Glaucoma Caused by Novel TREX1 Mutation

BACKGROUND

Aicardi-Goutières syndrome (AGS) is a rare genetic disorder characterized by microcephaly, white matter lesions, numerous intracranial calcifications, chilblain skin lesions and high levels of interferon-α (IFN-α) in the cerebrospinal fluid (CSF). However, ocular involvement is reported significantly less frequently.

CASE PRESENTATION

We present a case of a neonate with hypotrophy, microcephaly, frostbite-like skin lesions, thrombocytopenia, elevated liver enzymes and hepatosplenomegaly. Magnetic resonance imaging (MRI) of the brain showed multiple foci of calcification, white matter changes, cerebral atrophy, and atrophic dilatation of the ventricular system. The inflammatory parameters were not elevated, and the infectious etiology was excluded. Instead, elevated levels of IFN-α in the serum were detected. Based on the related clinical symptoms, imaging and test findings, the diagnosis of AGS was suspected. Genetic testing revealed two pathogenic mutations, c.490C>T and c.222del (novel mutation), in the three prime repair exonuclease 1 (TREX1) gene, confirming AGS type 1 (AGS1). An ophthalmologic examination of the child at 10 months of age revealed an impaired pupillary response to light, a corneal haze with Haab lines in the right eye (RE), pale optic nerve discs and neuropathy in both eyes (OU). The intraocular pressure (IOP) was 51 mmHg in the RE and 49 in the left eye (LE). The flash visual evoked potential (FVEP) showed prolonged P2 latencies of up to 125% in the LE and reduced amplitudes of up to approximately 10% OU. This girl was diagnosed with congenital glaucoma, and it was managed with a trabeculectomy with a basal iridectomy of OU, resulting in a reduction and stabilization in the IOP to 12 mmHg in the RE and 10 mmHg in the LE without any hypotensive eyedrops.

CONCLUSIONS

We present the clinical characteristics, electrophysiological and imaging findings, as well as the genetic test results of a patient with AGS1. Our case contributes to the extended ophthalmic involvement of the pathogenic c.490C>T and c.222del mutations in TREX1.

Type I Interferonopathies: A Clinical Review

This review will discuss when clinicians should consider evaluating for Type I interferonopathies, review clinical phenotypes and molecular defects of Type I interferonopathies, and discuss current treatments.

Aicardi-Goutières syndrome: A monogenic type I interferonopathy

Aicardi-Goutières syndrome (AGS) is a rare monogenic autoimmune disease that primarily affects the brains of children patients. Its main clinical features include encephalatrophy, basal ganglia calcification, leukoencephalopathy, lymphocytosis and increased interferon-α (IFN-α) levels in the patient's cerebrospinal fluid (CSF) and serum. AGS may be caused by mutations in any one of nine genes (TREX1, RNASEH2A, RNASEH2B, RNASEH2C, SAMHD1, ADAR1, IFIH1, LSM11 and RNU7-1) that result in accumulation of self-nucleic acids in the cytoplasm or aberrant sensing of self-nucleic acids. This triggers overproduction of type I interferons (IFNs) and subsequently causes AGS, the prototype of type I interferonopathies. This review describes the discovery history of AGS with various genotypes and provides the latest knowledge of clinical manifestations and causative genes of AGS. The relationship between AGS and type I interferonopathy and potential therapeutic methods for AGS are also discussed in this review.

Endothelial type I interferon response and brain diseases: identifying STING as a therapeutic target

The endothelium layer lining the inner surface of blood vessels serves relevant physiological functions in all body systems, including the exchanges between blood and extravascular space. However, endothelial cells also participate in innate and adaptive immune response that contribute to the pathophysiology of inflammatory disorders. Type I Interferon (IFN) signaling is an inflammatory response triggered by a variety of pathogens, but it can also be induced by misplaced DNA in the cytosol caused by cell stress or gene mutations. Type I IFN produced by blood leukocytes or by the endothelium itself is well-known to activate the interferon receptor (IFNAR) in endothelial cells. Here, we discuss the induction of type I IFN secretion and signaling in the endothelium, specifically in the brain microvasculature where endothelial cells participate in the tight blood-brain barrier (BBB). This barrier is targeted during neuroinflammatory disorders such as infection, multiple sclerosis, Alzheimer's disease and traumatic brain injury. We focus on type I IFN induction through the cGAS-STING activation pathway in endothelial cells in context of autoinflammatory type I interferonopathies, inflammation and infection. By comparing the pathophysiology of two separate infectious diseases-cerebral malaria induced by Plasmodium infection and COVID-19 caused by SARS-CoV-2 infection-we emphasize the relevance of type I IFN and STING-induced vasculopathy in organ dysfunction. Investigating the role of endothelial cells as active type I IFN producers and responders in disease pathogenesis could lead to new therapeutic targets. Namely, endothelial dysfunction and brain inflammation may be avoided with strategies that target excessive STING activation in endothelial cells.

Interferonopathies masquerading as non-Mendelian autoimmune diseases: pattern recognition for early diagnosis

Type I interferonopathies are a broad category of conditions associated with increased type I interferon gene expression and include monogenic autoinflammatory diseases and non-Mendelian autoimmune diseases such as dermatomyositis and systemic lupus erythematosus. While a wide range of clinical presentations among type I interferonopathies exists, these conditions often share several clinical manifestations and implications for treatment. Presenting symptoms may mimic non-Mendelian autoimmune diseases, including vasculitis and systemic lupus erythematosus, leading to delayed or missed diagnosis. This review aims to raise awareness about the varied presentations of monogenic interferonopathies to provide early recognition and appropriate treatment to prevent irreversible damage and improve quality of life and outcomes in this unique patient population.

Exploration of Gross Motor Function in Aicardi-Goutières Syndrome

Background: Aicardi-Goutières syndrome (AGS) is a rare genetic disorder characterized by a spectrum of motor abilities. While the Aicardi-Goutières syndrome severity score favors severely impacted individuals, there is an unmet need to define tools measuring function across the Aicardi-Goutières syndrome spectrum as potential outcome assessments for future clinical trials. Methods: Gross Motor Function Measure-88 (GMFM-88) and AGS Severity Scale were administered in individuals affected by Aicardi-Goutières syndrome (n = 71). We characterized the performance variability by genotype. Derived versions of the GMFM-88, including the GMFM-66, GMFM-66 item set (GMFM-66IS), and GMFM-66 Basal&Ceiling (GMFM-66BC) were calculated. The Aicardi-Goutières syndrome cohort was divided into severe (AGS Severity Scale score <4) or attenuated (≥4). Performance on the AGS Severity Scale highly correlated with total GMFM-88 scores (Spearman Correlation: R = 0.91). To assess variability of the GMFM-88 within genotypic subcohorts, interquartile ranges (IQRs) were compared. Results: GMFM-88 performance in the TREX1 cohort had least variability while the SAMHD1 cohort had the largest IQR (4.23 vs 81.8). Floor effect was prominent, with most evaluations scoring below 20% (n = 46, 64.79%), particularly in TREX1- and RNASEH2-cohorts. Performance by the GMFM-66, GMFM-66IS, and GMFM-66BC highly correlated with the full GMFM-88. The Aicardi-Goutières syndrome population represents a broad range of gross motor skills. Conclusions: This work identified the GMFM-88 as a potential clinical outcome assessment in subsets of the Aicardi-Goutières syndrome population but underscores the need for additional validation of outcome measures reflective of the diverse gross motor function observed in this population, including low motor function. When time is limited by resources or patient endurance, shorter versions of the GMFM-88 may be a reasonable alternative.

PSMC3 proteasome subunit variants are associated with neurodevelopmental delay and type I interferon production

A critical step in preserving protein homeostasis is the recognition, binding, unfolding, and translocation of protein substrates by six AAA-ATPase proteasome subunits (ATPase-associated with various cellular activities) termed PSMC1-6, which are required for degradation of proteins by 26S proteasomes. Here, we identified 15 de novo missense variants in the PSMC3 gene encoding the AAA-ATPase proteasome subunit PSMC3/Rpt5 in 23 unrelated heterozygous patients with an autosomal dominant form of neurodevelopmental delay and intellectual disability. Expression of PSMC3 variants in mouse neuronal cultures led to altered dendrite development, and deletion of the PSMC3 fly ortholog Rpt5 impaired reversal learning capabilities in fruit flies. Structural modeling as well as proteomic and transcriptomic analyses of T cells derived from patients with PSMC3 variants implicated the PSMC3 variants in proteasome dysfunction through disruption of substrate translocation, induction of proteotoxic stress, and alterations in proteins controlling developmental and innate immune programs. The proteostatic perturbations in T cells from patients with PSMC3 variants correlated with a dysregulation in type I interferon (IFN) signaling in these T cells, which could be blocked by inhibition of the intracellular stress sensor protein kinase R (PKR). These results suggest that proteotoxic stress activated PKR in patient-derived T cells, resulting in a type I IFN response. The potential relationship among proteosome dysfunction, type I IFN production, and neurodevelopment suggests new directions in our understanding of pathogenesis in some neurodevelopmental disorders.

Renal involvement in monogenic autoinflammatory diseases: A narrative review

Autoinflammatory diseases (AIDs) are mostly caused by dysfunctions in single genes encoding for proteins with a prominent role in the regulation of innate immunity, such as complement factors, inflammasome components, tumour necrosis factor (TNF)-α, and proteins belonging to type I-interferon (IFN) signalling pathways. Due to the deposition of amyloid A (AA) fibrils in the glomeruli, unprovoked inflammation in AIDs frequently affects renal health. In fact, secondary AA amyloidosis is the most common form of amyloidosis in children. It is caused by the extracellular deposition of fibrillar low-molecular weight protein subunits resulting from the degradation and accumulation of serum amyloid A (SAA) in numerous tissues and organs, primarily the kidneys. The molecular mechanisms underlying AA amyloidosis in AIDs are the elevated levels of SAA, produced by the liver in response to pro-inflammatory cytokines, and a genetic predisposition due to specific SAA isoforms. Despite the prevalence of amyloid kidney disease, non-amyloid kidney diseases may also be responsible for chronic renal damage in children with AIDs, albeit with distinct characteristics. Glomerular damage can result in various forms of glomerulonephritis with distinct histologic characteristics and a different underlying pathophysiology. This review aims to describe the potential renal implications in patients with inflammasomopathies, type-I interferonopathies, and other rare AIDs in an effort to improve the clinical course and quality of life in paediatric patients with renal involvement.

The link between rheumatic disorders and inborn errors of immunity

Inborn errors of immunity (IEIs) are immunological disorders characterized by variable susceptibility to infections, immune dysregulation and/or malignancies, as a consequence of damaging germline variants in single genes. Though initially identified among patients with unusual, severe or recurrent infections, non-infectious manifestations and especially immune dysregulation in the form of autoimmunity or autoinflammation can be the first or dominant phenotypic aspect of IEIs. An increasing number of IEIs causing autoimmunity or autoinflammation, including rheumatic disease have been reported over the last decade. Despite their rarity, identification of those disorders provided insight into the pathomechanisms of immune dysregulation, which may be relevant for understanding the pathogenesis of systemic rheumatic disorders. In this review, we present novel IEIs primarily causing autoimmunity or autoinflammation along with their pathogenic mechanisms. In addition, we explore the likely pathophysiological and clinical relevance of IEIs in systemic rheumatic disorders.

Childhood Interstitial Lung Disease

Childhood interstitial lung disease (chILD) is a heterogeneous group of diseases with various clinical and imaging findings. The incidence and prevalence have increased in recent years, probably due to better comprehension of these rare diseases and increased awareness among physicians. chILDs present with nonspecific pulmonary symptoms, such as tachypnea, hypoxemia, cough, rales, and failure to thrive. Unnecessary invasive procedures can be avoided if specific mutations are detected through genetic examinations or if typical imaging patterns are recognized on computed tomography. Disease knowledge and targeted therapies are improving through international collaboration. Pulmonary involvement in systemic diseases is not uncommon. Pulmonary involvement may be the first finding in connective tissue diseases. This review aims to present a systematic patient-targeted approach to the diagnosis of chILD.

Zika virus alters osteogenic lineage progression of human mesenchymal stromal cells

Arboviruses target bone forming osteoblasts and perturb bone remodeling via paracrine factors. We previously reported that Zika virus (ZIKV) infection of early-stage human mesenchymal stromal cells (MSCs) inhibited the osteogenic lineage commitment of MSCs. To understand the physiological interplay between bone development and ZIKV pathogenesis, we employed a primary in vitro model to examine the biological responses of MSCs to ZIKV infection at different stages of osteogenesis. Precommitted MSCs were infected at the late stage of osteogenic stimulation (Day 7) with ZIKV (multiplicity of infection of 5). We observe that MSCs infected at the late stage of differentiation are highly susceptible to ZIKV infection similar to previous observations with early stage infected MSCs (Day 0). However, in contrast to ZIKV infection at the early stage of differentiation, infection at a later stage significantly elevates the key osteogenic markers and calcium content. Comparative RNA sequencing (RNA-seq) of early and late stage infected MSCs reveals that ZIKV infection alters the mRNA transcriptome during osteogenic induction of MSCs (1251 genes). ZIKV infection provokes a robust antiviral response at both stages of osteogenic differentiation as reflected by the upregulation of interferon responsive genes (n > 140). ZIKV infection enhances the expression of immune-related genes in early stage MSCs while increasing cell cycle genes in late stage MSCs. Remarkably, ZIKA infection in early stage MSCs also activates lipid metabolism-related pathways. In conclusion, ZIKV infection has differentiation stage-dependent effects on MSCs and this mechanistic understanding may permit the development of new therapeutic or preventative measures for bone-related effects of ZIKV infection.

Interstitial lung disease in autoinflammatory disease in childhood: A systematic review of the literature

BACKGROUND/OBJECTIVES

The lung is one of the target organs in the systemic involvement of autoinflammatory disease (AID), and interstitial lung disease (ILD) is the primary phenotype of lung involvement in AID. In this review, we aimed to conduct a systematic review of the available literature to highlight ILD in AID.

METHODS

We conducted a systematic literature search in PubMed/MEDLINE and Scopus from the inception of the databases to January 2022. References were first screened by title and then by abstract by two authors. Eighteen original papers were selected for full-text review.

RESULTS

During the literature search, we identified 18 relevant articles describing 52 cases of AID and ILD. Of those, 44 patients had stimulator of interferon genes-associated vasculopathy with onset in infancy (SAVI), six had coatomer protein complex (COPA) syndrome, one had haploinsufficiency of A20, and one had mevalonate kinase deficiency. Pulmonary fibrosis, cyst formation, and ground glass areas were the most common findings in chest tomography of patients with COPA syndrome and SAVI. Janus kinase inhibitors were used to treat most of the patients with SAVI, which stabilized ILD.

CONCLUSIONS

ILD should be considered carefully in children with AID, especially those with interferonopathy.

Rituximab in Idiopathic Pulmonary Hemosiderosis in Children: A Novel and Less Toxic Treatment Option

Idiopathic pulmonary hemosiderosis (IPH) is a rare, potentially life-threatening chronic disease. Steroids are the cornerstone of treatment, even though toxicity and side-effects are very common. Recently, rituximab (RTX) has been suggested as a treatment option, although evidence for its efficacy and long-term safety is lacking. We describe the disease course of two pediatric patients with IPH that were treated with RTX for over 4 years. Demographics, treatments, and clinical variables such as growth, infections, imaging follow-up by CT, and data from pulmonary function tests were retrospectively described. These are the first two cases described with a long-term follow-up of pediatric IPH patients treated with RTX. RTX was well-tolerated and prevented outbreaks of bleeding. In addition, RTX had a robust steroid-sparing effect resulting in the improvement of growth, pulmonary function, and CT abnormalities.

Precision medicine: The use of tailored therapy in primary immunodeficiencies

Primary immunodeficiencies (PID) are rare, complex diseases that can be characterised by a spectrum of phenotypes, from increased susceptibility to infections to autoimmunity, allergy, auto-inflammatory diseases and predisposition to malignancy. With the introduction of genetic testing in these patients and wider use of next-Generation sequencing techniques, a higher number of pathogenic genetic variants and conditions have been identified, allowing the development of new, targeted treatments in PID. The concept of precision medicine, that aims to tailor the medical interventions to each patient, allows to perform more precise diagnosis and more importantly the use of treatments directed to a specific defect, with the objective to cure or achieve long-term remission, minimising the number and type of side effects. This approach takes particular importance in PID, considering the nature of causative defects, disease severity, short- and long-term complications of disease but also of the available treatments, with impact in life-expectancy and quality of life. In this review we revisit how this approach can or is already being implemented in PID and provide a summary of the most relevant treatments applied to specific diseases.

Use of Tofacitinib for infant-onset STING-associated vasculopathy: A case report from China

BACKGROUND

Stimulator of interferon gene (STING)-associated vasculopathy with onset in infancy (SAVI), caused by gain-of-function mutations in human transmembrane protein 173 (TMEM173), is characterized by widespread chronic inflammation primarily affecting the skin and lungs. Although SAVI is an inflammatory disease, typical anti-inflammatory agents have limited or no effect.

METHODS AND RESULTS

A 1-year-old boy presented with recurrent facial rashes since he was 8 months. Moreover, he suffered from recurrent oral ulcers, chronic cough, and failure to thrive. Laboratory parameters showed elevated erythrocyte sedimentation rate (ESR) and immunoglobulin levels. Chest high-resolution computed tomography (HRCT) showed interstitial lung disease (ILD). Whole-exome sequencing revealed a heterozygous mutation in the TMEM173 gene (c.463G > A, p.V155M). Ultimately, the patient was diagnosed with SAVI. Tofacitinib was initiated at the age of 19 months, resulting in the alleviation of facial rashes and improvement of ILD within 3 months.

CONCLUSION

SAVI is a difficult-to-treat type I interferonopathy. We hope that JAKi treatment will prove valuable for SAVI patients.

Hemophagocytic lymphohistocytosis in trisomy 21: successful treatment with interferon inhibition

BACKGROUND

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening condition of immune dysregulation primarily driven by the cytokine interferon gamma. It can be either a genetic or acquired disorder associated with infection, malignancy, and rheumatologic disorders. Trisomy 21 can express a wide range of phenotypes which include immune dysregulation and shares inherent pathophysiology with a group of disorders termed interferonopathies. Knowledge of this overlap in seemingly unrelated conditions could provide a basis for future research, and most importantly, alternative therapeutic interventions in acute life threatening clinical scenarios. Herein, we describe two patients with trisomy 21 presenting with HLH that was refractory to conventional treatment. Both patients were successfully managed with novel interventions targeting the interferon pathway.

CASE PRESENTATION

We describe a 17-month-old male and 15-month-old female with trisomy 21 presenting with a myriad of signs and symptoms including fever, rash, cytopenias, and hyperferritinemia, both ultimately diagnosed with HLH. Each had relapsing, refractory HLH over time requiring several admissions to the hospital receiving conventional high dose corticosteroids and interleukin-1 inhibition therapy. Successful steroid-free remission was achieved after targeting interferon inhibition with emapalumab induction followed by long-term maintenance on baricitinib.

CONCLUSION

To our knowledge, these are the first reported cases of relapsed, refractory HLH in patients with trisomy 21 successfully treated with emapalumab and transitioned to a steroid-sparing regimen with oral baricitinib for maintenance therapy. Trisomy 21 autoimmunity and HLH are both thought to be driven by interferon gamma. Targeting therapy toward interferon signaling in both HLH and autoimmunity in trisomy 21 may have potential therapeutic benefits. Further investigation is needed to determine if trisomy 21 may predispose to the development of HLH given this common pathway.

The role of type I IFN in autoimmune and autoinflammatory diseases with CNS involvement

Type I interferons (IFNs) are major mediators of innate immunity, with well-known antiviral, antiproliferative, and immunomodulatory properties. A growing body of evidence suggests the involvement of type I IFNs in the pathogenesis of central nervous system (CNS) manifestations in the setting of chronic autoimmune and autoinflammatory disorders, while IFN-β has been for years, a well-established therapeutic modality for multiple sclerosis (MS). In the present review, we summarize the current evidence on the mechanisms of type I IFN production by CNS cellular populations as well as its local effects on the CNS. Additionally, the beneficial effects of IFN-β in the pathophysiology of MS are discussed, along with the contributory role of type I IFNs in the pathogenesis of neuropsychiatric lupus erythematosus and type I interferonopathies.

Assessment of type I interferon signatures in undifferentiated inflammatory diseases: A Japanese multicenter experience

Purpose

Upregulation of type I interferon (IFN) signaling has been increasingly detected in inflammatory diseases. Recently, upregulation of the IFN signature has been suggested as a potential biomarker of IFN-driven inflammatory diseases. Yet, it remains unclear to what extent type I IFN is involved in the pathogenesis of undifferentiated inflammatory diseases. This study aimed to quantify the type I IFN signature in clinically undiagnosed patients and assess clinical characteristics in those with a high IFN signature.

Methods

The type I IFN signature was measured in patients’ whole blood cells. Clinical and biological data were collected retrospectively, and an intensive genetic analysis was performed in undiagnosed patients with a high IFN signature.

Results

A total of 117 samples from 94 patients with inflammatory diseases, including 37 undiagnosed cases, were analyzed. Increased IFN signaling was observed in 19 undiagnosed patients, with 10 exhibiting clinical features commonly found in type I interferonopathies. Skin manifestations, observed in eight patients, were macroscopically and histologically similar to those found in proteasome-associated autoinflammatory syndrome. Genetic analysis identified novel mutations in the PSMB8 gene of one patient, and rare variants of unknown significance in genes linked to type I IFN signaling in four patients. A JAK inhibitor effectively treated the patient with the PSMB8 mutations. Patients with clinically quiescent idiopathic pulmonary hemosiderosis and A20 haploinsufficiency showed enhanced IFN signaling.

Conclusions

Half of the patients examined in this study, with undifferentiated inflammatory diseases, clinically quiescent A20 haploinsufficiency, or idiopathic pulmonary hemosiderosis, had an elevated type I IFN signature.

Disorders of ubiquitylation: unchained inflammation

Ubiquitylation is an essential post-translational modification that regulates intracellular signalling networks by triggering proteasomal substrate degradation, changing the activity of substrates or mediating changes in proteins that interact with substrates. Hundreds of enzymes participate in reversible ubiquitylation of proteins, some acting globally and others targeting specific proteins. Ubiquitylation is essential for innate immune responses, as it facilitates rapid regulation of inflammatory pathways, thereby ensuring sufficient but not excessive responses. A growing number of inborn errors of immunity are attributed to dysregulated ubiquitylation. These genetic disorders exhibit broad clinical manifestations, ranging from susceptibility to infection to autoinflammatory and/or autoimmune features, lymphoproliferation and propensity to malignancy. Many autoinflammatory disorders result from disruption of components of the ubiquitylation machinery and lead to overactivation of innate immune cells. An understanding of the disorders of ubiquitylation in autoinflammatory diseases could enable the development of novel management strategies.

Janus Kinase Inhibitors in the Treatment of Type I Interferonopathies: A Case Series From a Single Center in China

Objective

This study aimed to assess the efficacy and safety of 2 Janus kinase (JAK) inhibitors (jakinibs) tofacitinib and ruxolitinib in the treatment of type I interferonopathies patients including STING-associated vasculopathy with onset in infancy (SAVI), Aicardi-Goutières syndrome (AGS), and spondyloenchondrodysplasia with immune dysregulation (SPENCD).

Methods

A total of 6 patients were considered in this study: 2 patients with SAVI, 1 patient with AGS1, 1 patient with AGS7, and 2 patients with SPENCD. Clinical manifestations, laboratory investigations, radiology examinations, treatment, and outcomes were collected between November 2017 and November 2021 in Peking Union Medical College Hospital. The disease score for patients with SAVI and AGS scale for patients with AGS were documented. The expression of 6 interferon-stimulated genes (ISGs) was assessed by real-time PCR.

Results

Three patients (1 patient with SAVI, 2 patients with AGS) were treated with ruxolitinib and 3 patients (1 patient with SAVI, 2 patients with SPENCD) were treated with tofacitinib. The mean duration of the treatment was 2.5 years (1.25-4 years). Upon treatment, cutaneous lesions and febrile attacks subsided in all affected patients. Two patients discontinued the corticoid treatment. Two patients with SAVI showed an improvement in the disease scores (p < 0.05). The erythrocyte sedimentation rate normalized in 2 patients with AGS. The interferon score (IS) was remarkably decreased in 2 patients with SPENCD (p < 0.01). Catch-ups with growth and weight gain were observed in 3 and 2 patients, respectively. Lung lesions improved in 1 patient with SAVI and remained stable in 3 patients. Lymphopenia was found in 3 patients during the treatment without severe infections.

Conclusion

The JAK inhibitors baricitinib and tofacitinib are promising therapeutic agents for patients with SAVI, AGS, and SPENCD, especially for the improvement of cutaneous lesions and febrile attacks. However, further cohort studies are needed to assess the efficacy and safety.

Regulation of IRF3 activation in Human Antiviral Signalling Pathways

The interferon regulatory factor (IRF) family of transcription factors play a vital role in the human innate antiviral immune responses with production of interferons (IFNs) as a hallmark outcome of activation. In recent years, IRF3 has been considered a principal early regulator of type I IFNs (TI-IFNs) directly downstream of intracellular virus sensing. Despite decades of research on IRF-activating pathways, many questions remain on the regulation of IRF3 activation. The kinases IκB kinase epsilon (IKKε) and TANK-binding kinase-1 (TBK1) and the scaffold proteins TRAF family member-associated NF-kappa-B activator (TANK), NF-kappa-B-activating kinase-associated protein 1 (NAP1) and TANK-binding kinase 1-binding protein 1 (TBKBP1)/similar to NAP1 TBK1 adaptor (SINTBAD) are believed to be core components of an IRF3-activation complex yet their contextual involvement and complex composition are still unclear. This review will give an overview of antiviral signaling pathways leading to the activation of IRF3 and discuss recent developments in our understanding of its proximal regulation.

Mechanisms of vascular inflammation in deficiency of adenosine deaminase 2 (DADA2)

Deficiency of adenosine deaminase 2 (DADA2) was first described as a monogenic form of systemic vasculitis that closely resembles polyarteritis nodosa (PAN). The phenotypic spectrum of DADA2 has vastly expanded in recent years and now includes pure red cell aplasia, bone marrow failure syndrome, lymphoproliferative disease, and humoral immunodeficiency. Vasculitis remains the most common presentation of DADA2, and treatment with tumor necrosis factor inhibitors (TNFi) has shown remarkable efficacy in preventing stroke and ameliorating features of systemic inflammation. The precise function of ADA2 has not been elucidated, and how absence of ADA2 ignites inflammation is an active area of research. In this review, we will discuss the current understanding of DADA2 from research and clinical perspectives. We will evaluate several proposed functions of ADA2, including polarization of monocyte phenotype, regulation of neutrophil extracellular trap formation, and modulation of innate immunity. We will also review the role of inflammatory cytokines including TNF and type I interferons. Lastly, we will provide future perspectives on understanding the phenotypic heterogeneity of DADA2 and discuss potential treatment options.

Acrofacial necrotic ulcers in an infant: An undiagnosed presentation

Acral necrotic ulcers in infancy are rare but have been described in type I interferonopathies. Herein, we present a case of an 8-year-old child who presented at the age of one month with severe ulceronecrotic lesions on the face and limbs with exacerbations following exposure to cold weather. Despite extensive investigation the case remains undiagnosed to this day. We hypothesize that this case represents a novel and yet unknown autoinflammatory disease.

Novel Mutations in ACP5 and SAMHD1 in a Patient With Pediatric Systemic Lupus Erythematosus

BACKGROUND

The study of genetic predisposition to pediatric systemic lupus erythematosus (pSLE) has brought new insights into the pathophysiology of SLE, as it is hypothesized that genetic predisposition is greater in children. Furthermore, identifying genetic variants and linking disrupted genes to abnormal immune pathways and clinical manifestations can be beneficial for both diagnosis and treatment. Here, we identified genetic alterations in a patient with childhood-onset SLE and analyzed the immunological mechanisms behind them to support future diagnosis, prognosis, and treatment.

METHODS

Whole exome sequencing (WES) was adopted for genetic analysis of a patient with childhood-onset SLE. Gene mutations were confirmed by Sanger sequencing. Clinical data of this patient were collected and summarized. Ingenuity Pathway Analysis was used to provide interacting genes of the perturbed genes. Online Enrichr tool and Cytoscape software were used to analysis the related pathways of these genes.

RESULTS

We present a case of a 2-year-old girl who was diagnosed with idiopathic thrombocytopenic purpura (ITP) and SLE. The patient was characterized by cutaneous bleeding spots on both lower extremities, thrombocytopenia, decreased serum complements levels, increased urinary red blood cells, and positive ANA and dsDNA. The patient was treated with methylprednisolone and mycophenolate, but clinical remission could not be achieved. The genomic analysis identified three novel mutations in this pSLE patient, a double-stranded missense mutation in ACP5 (c.1152G>T and c.420G>A) and a single-stranded mutation in SAMHD1 (c.1423G>A). Bioinformatic analysis showed that these two genes and their interacting genes are enriched in the regulation of multiple immune pathways associated with SLE, including cytokine signaling and immune cell activation or function. Analysis of the synergistic regulation of these two genes suggests that abnormalities in the type I interferon pathway caused by genetic variants may contribute to the pathogenesis of SLE.

CONCLUSION

The combined complexity of polymorphisms in the coding regions of ACP5 and SAMHD1 influences the susceptibility to SLE. Alterations in these genes may lead to abnormalities in the type I interferon pathway. Our study extends the spectrum of mutations in the ACP5 and SAMHD1 genes. The identification of these mutations could aid in the diagnosis of SLE with genetic counseling and suggest potential precise treatments for specific pathways.

Inborn Errors of Immunity With Fetal or Perinatal Clinical Manifestations

In this article we revised the literature on Inborn Errors of Immunity (IEI) keeping our focus on those diseases presenting with intrauterine or perinatal clinical manifestations. We opted to describe our findings according to the IEI categories established by the International Union of Immunological Societies, predominantly addressing the immunological features of each condition or group of diseases. The main finding is that such precocious manifestations are largely concentrated in the group of primary immune regulatory disorders (PIRDs) and not in the group of classical immunodeficiencies. The IEI categories with higher number of immunological manifestations in utero or in perinatal period are: (i) diseases of immune dysregulation (HLH, IPEX and other Tregopathies, autosomal recessive ALPS with complete lack of FAS protein expression) and (ii) autoinflammatory diseases (NOMID/CINCA, DIRA and some interferonopathies, such as Aicardi-Goutières syndrome, AGS, and USP18 deficiency). Regarding the other IEI categories, some patients with Omenn syndrome (an atypical form of SCID), and a few X-linked CGD patients present with clinical manifestations at birth associated to immune dysregulation. The most frequent clinical features were hydrops fetalis, intrauterine growth retardation leading to fetal loss, stillbirths, and prematurity, as in HLH and IPEX. Additionally, pseudo-TORCH syndrome was observed in AGS and in USP18 deficiency. The main goal of our review was to contribute to increasing the medical awareness of IEI with intrauterine and perinatal onset, which has obvious implications for diagnosis, treatment, and genetic counseling.

Epidemiology and clinical evolution of non-multisystem inflammatory syndrome (MIS-C) dermatological lesions in pediatric patients affected by SARS-CoV-2 infection: A systematic review of the literature

COVID-19 can present with a range of skin manifestations, some of which specific of the pediatric age. The aim of this systematic literature review was to determine the type, prevalence, time of onset, and evolution of cutaneous manifestations associated with COVID-19 in newborns, children, and adolescents, after excluding multisystem inflammatory syndrome in children (MIS-C). PubMed, Tripdatabase, ClinicalTrials, and Cochrane Library databases were searched using an ad hoc string for case reports/series and observational studies, published between December 2019 and February 2022. Study quality was assessed using the STROBE and CARE tools. Seventy-three (49 case reports/series and 24 studies) out of 26,545 identified articles were included in the analysis. Dermatological lesions were highly heterogeneous for clinical presentation, time of onset, and association with other COVID-19 manifestations. Overall, they mainly affected the acral portions, and typically presented a favorable outcome. Pseudo-chilblains were the most common.

CONCLUSIONS

Mucocutaneous manifestations could be the only/predominant and early manifestation of COVID-19 that could precede other more severe manifestations by days or weeks. Therefore, physicians of all disciplines should be familiar with them.

WHAT IS KNOWN

• A variety of cutaneous manifestations have been reported in association with COVID-19. • Urticaria, maculopapular, or vesicular rashes can occur at any age, while chilblains and erythema multiforme are more common in children and young patients.

WHAT IS NEW

• Skin lesions related to SARS-CoV-2 infection often show a peculiar acral distribution. • Mucocutaneous lesions of various type may be the only/predominant manifestation of COVID-19; they could present in paucisymptomatic and severely ill patients and occur at different stages of the disease.

Langfristentwicklungen in der Kinder- und Jugendrheumatologie

Im Gebiet der Kinderrheumatologie gab es in den letzten Jahrzehnten immense Fortschritte, die sowohl die Diagnostik, als auch die Therapie nachhaltig verbessert haben. Obwohl erst seit 2003 in Deutschland offiziell als Zusatzbezeichnung anerkannt, stehen heutzutage über 200 Kinder- und Jugendrheumatologen (d. h. 1,4 Kinderrheumatologen pro 100 000 Kinder) für die Erkennung und Behandlung von rheumatischen Erkrankungen bei Kindern und Jugendlichen bundesweit zur Verfügung. Neue Erkenntnisse in der Pathogenese rheumatischer Erkrankungen und die sich stetig weiterentwickelnde genetische Diagnostik haben das rheumatische Krankheitsspektrum und die Behandlungsmöglichkeiten dramatisch erweitert Internationale Forschungsnetzwerke und eine spezielle Gesetzgebung für die Entwicklung von pädiatrischen Medikamenten führten zur Zulassung von zahlreichen neuen Rheumamedikamenten, deren Sicherheit im klinischen Alltag seit der Jahrtausendwende systematisch in Deutschland untersucht wird. Maßnahmen zur Sicherung der Versorgungsqualität wurden implementiert, Standardinstrumente zur Bewertung der Krankheitsaktivität und Krankheitslast aus Patientensicht eingeführt sowie Initiativen zur Verbesserung der Versorgung Betroffener (z. B. die ProKind-Initiative) auf den Weg gebracht. Diese Veränderungen haben die Prognose und Lebensperspektive rheumakranker Kinder und Jugendlicher verbessert, wenngleich noch weiterer Optimierungsbedarf besteht.

An Aicardi-Goutières Syndrome-Causative Point Mutation in Adar1 Gene Invokes Multiorgan Inflammation and Late-Onset Encephalopathy in Mice

Aicardi-Goutières syndrome (AGS) is a congenital inflammatory disorder accompanied by overactivated type I IFN signaling and encephalopathy with leukodystrophy and intracranial calcification. To date, none of the mouse models carrying an AGS-causative mutation has mimicked such brain pathology. Here, we established a mutant mouse model carrying a K948N point mutation, corresponding to an AGS-causative K999N mutation, located in a deaminase domain of the Adar1 gene that encodes an RNA editing enzyme. Adar1^K948N/K948N mice displayed postnatal growth retardation. Hyperplasia of splenic white pulps with germinal centers and hepatic focal inflammation were observed from 2 mo of age. Inflammation developed in the lungs and heart with lymphocyte infiltration in an age-dependent manner. Furthermore, white matter abnormalities with astrocytosis and microgliosis were detected at 1 y of age. The increased expression of IFN-stimulated genes was detected in multiple organs, including the brain, from birth. In addition, single-nucleus RNA sequencing revealed that this elevated expression of IFN-stimulated genes was commonly observed in all neuronal subtypes, including neurons, oligodendrocytes, and astrocytes. We further showed that a K948N point mutation reduced the RNA editing activity of ADAR1 in vivo. The pathological abnormalities found in Adar1^K948N/K948N mice were ameliorated by either the concurrent deletion of MDA5, a cytosolic sensor of unedited transcripts, or the sole expression of active ADAR1 p150, an isoform of ADAR1. Collectively, such data suggest that although the degree is mild, Adar1^K948N/K948N mice mimic multiple AGS phenotypes, including encephalopathy, which is caused by reduced RNA editing activity of the ADAR1 p150 isoform.

Regulation of B Cell Responses in SLE by Three Classes of Interferons

There are three classes of interferons (type 1, 2, and 3) that can contribute to the development and maintenance of various autoimmune diseases, including systemic lupus erythematosus (SLE). Each class of interferons promotes the generation of autoreactive B cells and SLE-associated autoantibodies by distinct signaling mechanisms. SLE patients treated with various type 1 interferon-blocking biologics have diverse outcomes, suggesting that additional environmental and genetic factors may dictate how these cytokines contribute to the development of autoreactive B cells and SLE. Understanding how each class of interferons controls B cell responses in SLE is necessary for developing optimized B cell- and interferon-targeted therapeutics. In this review, we will discuss how each class of interferons differentially promotes the loss of peripheral B cell tolerance and leads to the development of autoreactive B cells, autoantibodies, and SLE.

Molecular and Cellular Bases of Lipodystrophy Syndromes

Lipodystrophy syndromes are rare diseases originating from a generalized or partial loss of adipose tissue. Adipose tissue dysfunction results from heterogeneous genetic or acquired causes, but leads to similar metabolic complications with insulin resistance, diabetes, hypertriglyceridemia, nonalcoholic fatty liver disease, dysfunctions of the gonadotropic axis and endocrine defects of adipose tissue with leptin and adiponectin deficiency. Diagnosis, based on clinical and metabolic investigations, and on genetic analyses, is of major importance to adapt medical care and genetic counseling. Molecular and cellular bases of these syndromes involve, among others, altered adipocyte differentiation, structure and/or regulation of the adipocyte lipid droplet, and/or premature cellular senescence. Lipodystrophy syndromes frequently present as systemic diseases with multi-tissue involvement. After an update on the main molecular bases and clinical forms of lipodystrophy, we will focus on topics that have recently emerged in the field. We will discuss the links between lipodystrophy and premature ageing and/or immuno-inflammatory aggressions of adipose tissue, as well as the relationships between lipomatosis and lipodystrophy. Finally, the indications of substitutive therapy with metreleptin, an analog of leptin, which is approved in Europe and USA, will be discussed.