Monogenic lupus: it's all new!

Could tolerance to DNA be broken in the gut in systemic lupus erythematosus?

The bacteria in the human colon outnumber the total number of nucleated cells in the human body by approximately 10:1. The DNA that the bacteria contain is enriched around 20-fold in immune stimulatory CpG motifs compared to the DNA of host cells. In addition, this DNA can have alternative more immunogeneic DNA structures and it may be presented to the immune system alongside other proinflammatory bacterial innate ligands such as LPS. To ensure that this immunostimulatory combination is not pathogenic, the luminal boundary of host tissues in the human gastrointestinal tract is protected by cells secreting bactericides together with the secreted enzyme DNASE1L3 that can break down bacterial DNA. Cells with RNA encoding DNASE1L3 are particularly abundant in the gut-associated lymphoid tissue where bacteria are specifically sampled into the body, alongside B cells noted for their T independent function. Importantly, individuals with loss of function mutations in DNASE1L3 develop anti-DNA antibodies and lupus symptoms. In this review, we explore the possibility that a perfect storm might break tolerance to DNA: when bacterial DNA from microbiota that is not digested by DNASE1L3 directly encounters B cells that are not necessarily restricted by T cell dependence.

The mosaic of systemic lupus erythematosus: From autoimmunity to autoinflammation and immunodeficiency and back

The concept of an "immunological continuum model," introduced by McGonagle and McDermott in 2006, redefines the traditional dichotomy between autoimmunity and autoinflammation, proposing a spectrum where innate and adaptive immune dysregulation can co-occur, reflecting a more nuanced understanding of immune disorders. Systemic lupus erythematosus (SLE) exemplifies the complexity of this continuum, often displaying manifestations of autoimmunity, autoinflammation, and immunodeficiency. The interplay between genetic, epigenetic, hormonal, psychological, and environmental factors contributes to its distinctive immunopathological signatures. Historically recognized as a systemic disease with diverse clinical manifestations, SLE is primarily a polygenic autoimmune condition but can, however, present in monogenic forms. Examining SLE through the lens of the immunological continuum model allows for emphasis on the contributions of both innate and adaptive immunity. SLE and primary immunodeficiencies share genetic susceptibilities and clinical manifestations. Additionally, autoinflammatory mechanisms, such as inflammasome activation and interferonopathies, can play a role in SLE pathogenesis, illustrating the disease's position at the crossroads of immune dysregulation. Recognizing the diverse clinical expressions of SLE and its mimickers is critical for accurate diagnosis and targeted therapy. In conclusion, the immunological continuum model provides a comprehensive framework for understanding SLE, acknowledging its multifaceted nature and guiding future research and clinical practice toward more effective and individualized treatments. After the Mosaic of Autoimmunity, it is now the time to focus and attempt to solve the intricate mosaic of SLE.

LASSO-derived nomogram for early identification of pediatric monogenic lupus

BACKGROUND

Monogenic lupus is defined as systemic lupus erythematosus (SLE)/SLE-like patients with either dominantly or recessively inherited pathogenic variants in a single gene with high penetrance. However, because the clinical phenotype of monogenic SLE is extensive and overlaps with that of classical SLE, it causes a delay in diagnosis and treatment. Currently, there is a lack of early identification models for clinical practitioners to provide early clues for recognition. Our goal was to create a clinical model for the early identification of pediatric monogenic lupus, thereby facilitating early and precise diagnosis and treatment for patients.

METHODS

This retrospective cohort study consisted of 41 cases of monogenic lupus treated at the Department of Pediatrics at Peking Union Medical College Hospital from June 2012 to December 2022. The control group consisted of classical SLE patients recruited at a 1:2 ratio. Patients were randomly divided into a training group and a validation group at a 7:3 ratio. A logistic regression model was established based on the least absolute shrinkage and selection operator to generate the coefficient plot. The predictive ability of the model was evaluated using receiver operator characteristic curves and the area under the curve (AUC) index.

RESULTS

A total of 41 cases of monogenic lupus patients and 82 cases of classical SLE patients were included. Among the monogenic lupus cases (with a male-to-female ratio of 1:1.05 and ages of onset ranging from birth to 15 years), a total of 18 gene mutations were identified. The variables included in the coefficient plot were age of onset, recurrent infections, intracranial calcifications, growth and developmental delay, abnormal muscle tone, lymphadenopathy/hepatosplenomegaly, and chilblain-like skin rash. Our model demonstrated satisfactory diagnostic performance through internal validation, with an AUC value of 0.97 (95% confidence interval = 0.92-0.97).

CONCLUSIONS

We summarized and analyzed the clinical characteristics of pediatric monogenic lupus and developed a predictive model for early identification by clinicians. Clinicians should exercise high vigilance for monogenic lupus when the score exceeds - 9.032299.

[Rare Autoimmune Diseases Role of Genetics - Example of Systemic Lupus Erythematosus]

Systemic lupus erythematosus (SLE) presents a complex clinical landscape with diverse manifestations, suggesting a multifactorial etiology. However, the identification of rare monogenic forms of the disease has shed light on specific genetic defects underlying SLE pathogenesis, offering valuable insights into its underlying mechanisms and clinical heterogeneity. By categorizing these monogenic forms based on the implicated signaling pathways, such as apoptotic body clearance, type I interferon signaling, JAK-STAT pathway dysregulation, innate immune receptor dysfunction and lymphocytic abnormalities, a more nuanced understanding of SLE's molecular basis emerges. Particularly in pediatric populations, where monogenic forms are more prevalent, routine genetic testing becomes increasingly important, with a diagnostic yield of approximately 10% depending on the demographic and methodological factors involved. This approach not only enhances diagnostic accuracy but also informs personalized treatment strategies tailored to the specific molecular defects driving the disease phenotype.

Double-negative B cells and DNASE1L3 colocalise with microbiota in gut-associated lymphoid tissue

Intestinal homeostasis is maintained by the response of gut-associated lymphoid tissue to bacteria transported across the follicle associated epithelium into the subepithelial dome. The initial response to antigens and how bacteria are handled is incompletely understood. By iterative application of spatial transcriptomics and multiplexed single-cell technologies, we identify that the double negative 2 subset of B cells, previously associated with autoimmune diseases, is present in the subepithelial dome in health. We show that in this location double negative 2 B cells interact with dendritic cells co-expressing the lupus autoantigens DNASE1L3 and C1q and microbicides. We observe that in humans, but not in mice, dendritic cells expressing DNASE1L3 are associated with sampled bacteria but not DNA derived from apoptotic cells. We propose that fundamental features of autoimmune diseases are microbiota-associated, interacting components of normal intestinal immunity.

Monogenic lupus: insights into disease pathogenesis and therapeutic opportunities

PURPOSE OF REVIEW

This review aims to provide an overview of the genes and molecular pathways involved in monogenic lupus, the implications for genome diagnosis, and the potential therapies targeting these molecular mechanisms.

RECENT FINDINGS

To date, more than 30 genes have been identified as contributors to monogenic lupus. These genes are primarily related to complement deficiency, activation of the type I interferon (IFN) pathway, disruption of B-cell and T-cell tolerance and metabolic pathways, which reveal the multifaceted nature of systemic lupus erythematosus (SLE) pathogenesis.

SUMMARY

In-depth study of the causes of monogenic lupus can provide valuable insights into of pathogenic mechanisms of SLE, facilitate the identification of effective biomarkers, and aid in developing therapeutic strategies.

Genetic interrogation for sequence and copy number variants in systemic lupus erythematosus

Early-onset systemic lupus erythematosus presents with a more severe disease and is associated with a greater genetic burden, especially in patients from Black, Asian or Hispanic ancestries. Next-generation sequencing techniques, notably whole exome sequencing, have been extensively used in genomic interrogation studies to identify causal disease variants that are increasingly implicated in the development of autoimmunity. This Review discusses the known casual variants of polygenic and monogenic systemic lupus erythematosus and its implications under certain genetic disparities while suggesting an age-based sequencing strategy to aid in clinical diagnostics and patient management for improved patient care.

Lupus Nephritis in Children: Novel Perspectives

Childhood-onset systemic lupus erythematosus is an inflammatory and autoimmune condition characterized by heterogeneous multisystem involvement and a chronic course with unpredictable flares. Kidney involvement, commonly called lupus nephritis, mainly presents with immune complex-mediated glomerulonephritis and is more frequent and severe in adults. Despite a considerable improvement in long-term renal prognosis, children and adolescents with lupus nephritis still experience significant morbidity and mortality. Moreover, current literature often lacks pediatric-specific data, leading clinicians to rely exclusively on adult therapeutic approaches. This review aims to describe pediatric lupus nephritis and provide an overview of the novel perspectives on the pathogenetic mechanisms, histopathological classification, therapeutic approach, novel biomarkers, and follow-up targets in children and adolescents with lupus nephritis.

Clinical characteristics of early-onset paediatric systemic lupus erythematosus in a single centre in China

OBJECTIVES

We sought to investigate the sex distribution, clinical presentations, disease outcomes and genetic background of early-onset paediatric SLE (eo-pSLE) in a single centre in China to help enable early diagnosis and timely treatment.

METHODS

The clinical data of children aged less than 5 years old with SLE (n = 19) from January 2012 to December 2021 were reviewed and analysed. We performed DNA sequencing in 11 out of 19 patients to survey the genetic aetiologies.

RESULTS

Our study included 6 males and 13 females. The mean age at onset was 3.73 years. The median diagnostic delay was 9 months and was longer in male patients (P = 0.02). Four patients had an SLE-relevant family history. The most common clinical manifestations at diagnosis were fever, rash and hepatosplenomegaly. ANA positivity and low C3 were identified in all children. The renal (94.74%), mucocutaneous (94.74%), haematological (89.47%), respiratory (89.47%), digestive (84.21%), cardiovascular (57.89%) and neuropsychiatric (52.63%) systems were involved to varying degrees. We identified 13 SLE-associated gene mutations in 9 out of 11 patients: TREX1, PIK3CD, LRBA, KRAS, STAT4, C3, ITGAM, CYBB, TLR5, RIPK1, BACH2, CFHR5 and SYK. One male patient showed a 47, XXY chromosomal abnormality.

CONCLUSION

Early-onset (<5 years) pSLE is characterized by an insidious onset, typical immunological patterns, and the involvement of multiple organs. Immunological screening and genetic testing should be performed as soon as feasible in patients with an early onset of multisystemic autoimmune diseases to confirm the diagnosis.

Monogenic lupus: Tracing the therapeutic implications from single gene mutations

Monogenic lupus, a distinctive variant of systemic lupus erythematosus (SLE), is characterized by early onset, family-centric clustering, and heightened disease severity. So far, over thirty genetic variations have been identified as single-gene etiology of SLE and lupus-like phenotypes. The critical role of these gene mutations in disrupting various immune pathways is increasingly recognized. In particular, single gene mutation-driven dysfunction within the innate immunity, notably deficiencies in the complement system, impedes the degradation of free nucleic acid and immune complexes, thereby promoting activation of innate immune cells. The accumulation of these components in various tissues and organs creates a pro-inflammatory microenvironment, characterized by a surge in pro-inflammatory cytokines, chemokines, reactive oxygen species, and type I interferons. Concurrently, single gene mutation-associated defects in the adaptive immune system give rise to the emergence of autoreactive T cells, hyperactivated B cells and plasma cells. The ensuing spectrum of cytokines and autoimmune antibodies drives systemic disease manifestations, primarily including kidney, skin and central nervous system-related phenotypes. This review provides a thorough overview of the single gene mutations and potential consequent immune dysregulations in monogenic lupus, elucidating the pathogenic mechanisms of monogenic lupus. Furthermore, it discusses the recent advances made in the therapeutic interventions for monogenic lupus.

The Role of Genetic Risk Factors in Pathogenesis of Childhood-Onset Systemic Lupus Erythematosus

The pathogenesis of childhood-onset systemic lupus erythematosus (cSLE) is complex and not fully understood. It involves three key factors: genetic risk factors, epigenetic mechanisms, and environmental triggers. Genetic factors play a significant role in the development of the disease, particularly in younger individuals. While cSLE has traditionally been considered a polygenic disease, it is now recognized that in rare cases, a single gene mutation can lead to the disease. Although these cases are uncommon, they provide valuable insights into the disease mechanism, enhance our understanding of pathogenesis and immune tolerance, and facilitate the development of targeted treatment strategies. This review aims to provide a comprehensive overview of both monogenic and polygenic SLE, emphasizing the implications of specific genes in disease pathogenesis. By conducting a thorough analysis of the genetic factors involved in SLE, we can improve our understanding of the underlying mechanisms of the disease. Furthermore, this knowledge may contribute to the identification of effective biomarkers and the selection of appropriate therapies for individuals with SLE.

Potential Therapeutic Value of the STING Inhibitors

The stimulator of interferon genes (STING) is a critical protein in the activation of the immune system in response to DNA. It can participate the inflammatory response process by modulating the inflammation-preferred translation program through the STING-PKR-like endoplasmic reticulum kinase (PERK)-eIF2α pathway or by inducing the secretion of type I interferons (IFNs) and a variety of proinflammatory factors through the recruitment of TANK-binding kinase 1 (TBK1) and interferon regulatory factor 3 (IRF3) or the regulation of the nuclear factor kappa-B (NF-κB) pathway. Based on the structure, location, function, genotype, and regulatory mechanism of STING, this review summarizes the potential value of STING inhibitors in the prevention and treatment of infectious diseases, psoriasis, systemic lupus erythematosus, non-alcoholic fatty liver disease, and other inflammatory and autoimmune diseases.

Panel sequencing links rare, likely damaging gene variants with distinct clinical phenotypes and outcomes in juvenile-onset SLE

OBJECTIVES

Juvenile-onset systemic lupus erythematosus (jSLE) affects 15-20% of lupus patients. Clinical heterogeneity between racial groups, age groups and individual patients suggests variable pathophysiology. This study aimed to identify highly penetrant damaging mutations in genes associated with SLE/SLE-like disease in a large national cohort (UK JSLE Cohort Study) and compare demographic, clinical and laboratory features in patient sub-cohorts with 'genetic' SLE vs remaining SLE patients.

METHODS

Based on a sequencing panel designed in 2018, target enrichment and next-generation sequencing were performed in 348 patients to identify damaging gene variants. Findings were integrated with demographic, clinical and treatment related datasets.

RESULTS

Damaging gene variants were identified in ∼3.5% of jSLE patients. When compared with the remaining cohort, 'genetic' SLE affected younger children and more Black African/Caribbean patients. 'Genetic' SLE patients exhibited less organ involvement and damage, and neuropsychiatric involvement developed over time. Less aggressive first line treatment was chosen in 'genetic' SLE patients, but more second and third line agents were used. 'Genetic' SLE associated with anti-dsDNA antibody positivity at diagnosis and reduced ANA, anti-LA and anti-Sm antibody positivity at last visit.

CONCLUSION

Approximately 3.5% of jSLE patients present damaging gene variants associated with younger age at onset, and distinct clinical features. As less commonly observed after treatment induction, in 'genetic' SLE, autoantibody positivity may be the result of tissue damage and explain reduced immune complex-mediated renal and haematological involvement. Routine sequencing could allow for patient stratification, risk assessment and target-directed treatment, thereby increasing efficacy and reducing toxicity.

Contribution of genetic variants associated with primary immunodeficiencies to childhood-onset systemic lupus erythematous

BACKGROUND

A dysregulated immune response is a hallmark of autoimmune disorders. Evidence suggests that systemic autoimmune diseases and primary immunodeficiency disorders (PIDs) may be similar diseases with different clinical phenotypes.

OBJECTIVE

This study aimed to investigate the burden of PID-associated genetic variants in patients with childhood-onset systemic lupus erythematosus (cSLE).

METHODS

We enrolled 118 cSLE patients regularly followed at Chang Gung Memorial Hospital. Targeted next-generation sequencing identified PID genetic variants in patients versus 1475 unrelated healthy individuals, which were further filtered by allelic frequency and various functional scores. Customized immune assays tested the functions of the identified variants.

RESULTS

On filtration, 36 patients (30.5%) harbored rare variants in PID-associated genes predicted to be damaging. One homozygous TREX1 (c.294dupA) mutation and 4 heterozygous variants with possible dominant PID traits, including BCL11B (c.G1040T), NFKB1 (c.T695G), and NFKB2 (c.G1210A, c.G1651A), were discovered. With recessive traits, variants were found across all PID types; one fifth involved phagocyte number or function defects. Predicted pathogenic PID variants were more predominant in those with a family history of lupus, regardless of infection susceptibility. Moreover, mutation loads were greater among cSLE patients than controls despite sex or age at disease onset. While greater mutation loads were observed among cSLE patients with peripubertal disease onset, no significant differences in sex or phenotype were noted among cSLE patients.

CONCLUSION

cSLE is mostly not monogenic. Gene-specific analysis and mutation load investigations suggested that rare and predicted damaging variants in PID-related genes can potentially contribute to cSLE susceptibility.

Genetic component of autoimmune rheumatological diseases

The purpose of this review is to present the main aspects of the genetic component of autoimmune rheumatic diseases, including the characteristics of the multifactorial or polygenic inheritance model, and its monogenic forms, as well as the main associated genes in both cases. The epigenetic changes involved, and the influence of the environment and sex that confer greater risk to women suffering from any of these diseases. Finally, to make known the advances that the study of omic sciences has allowed, opening the way to a new molecular classification of these diseases, aimed at personalized medicine. A review of the literature of the last 5 years, of English-language publications, in the PubMed database was performed and 28 review articles, and 19 original articles were included. Knowledge of the genetic factors involved in the aetiology of autoimmune rheumatic diseases, thanks to the availability of molecular studies, allows a better understanding of their pathophysiology and the possibility of diagnosis and treatment based on molecular markers in the future.

Characteristics and genetic analysis of patients suspected with early-onset systemic lupus erythematosus

BACKGROUND

Systemic lupus erythematosus (SLE) is rarely diagnosed before 5-years-old. Those with disease onset at a very young age are predicted by a higher genetic risk and a more severe phenotype. We performed whole-exome sequencing to survey the genetic etiologies and clinical manifestations in patients fulfilling 2012 SLICC SLE classification criteria before the age of 5.

CASE PRESENTATION

Among the 184 childhood-onset SLE patients regularly followed in a tertiary medical center in Taiwan, 7 cases (3.8%) of which onset ≦ 5 years of age were identified for characteristic review and genetic analysis. Compared to those onset at elder age, cases onset before the age of 5 are more likely to suffer from proliferative glomerulonephritis, renal thrombotic microangiopathy, neuropsychiatric disorder and failure to thrive. Causative genetic etiologies were identified in 3. In addition to the abundance of autoantibodies, patient with homozygous TREX1 (c.292_293 ins A) mutation presented with chilblain-like skin lesions, peripheral spasticity, endocrinopathy and experienced multiple invasive infections. Patient with SLC7A7 (c.625 + 1 G > A) mutation suffered from profound glomerulonephritis with full-house glomerular deposits as well as hyperammonemia, metabolic acidosis and episodic conscious disturbance. Two other cases harbored variants in lupus associating genes C1s, C2, DNASE1 and DNASE1L3 and another with CFHR4. Despite fulfilling the classification criteria for lupus, many of the patients required treatments beyond conventional therapy.

CONCLUSIONS

Genetic etiologies and lupus mimickers were found among a substantial proportion of patients suspected with early-onset SLE. Detail clinical evaluation and genetic testing are important for tailored care and personalized treatment.

Belimumab in childhood systemic lupus erythematosus: A review of available data

Introduction

Childhood systemic lupus erythematosus (cSLE) is a complex multisystem autoimmune disease. In 2019, belimumab was approved for the clinical treatment for cSLE, making it the only biological agent approved for cSLE children aged 5 and older in 60 years.

Objective

To review emerging evidence on belimumab in cSLE published up to April 2022, so as to provide information for clinical decision-making.

Method

A comprehensive search of relevant publications up to the date of April 2022 in PUBMED, EMBASE, WOS, COCHRANE, ClinicalTrials.gov, CBM, CNKI and WANFANG was performed using the following criteria: (a) English and Chinese language studies; (b) RCT studies, cohort studies, or case-control studies; (c) patients with age &lt;18; (d) Observational studies or case series studies contain more than 5 patients. All relevant literature was independently screened and reviewed by at least two reviewers and the obtained literature data were extracted and reviewed by two authors.

Results

Five publications met the inclusion/exclusion criteria for cSLE: one randomized controlled trial, one retrospective cohort study, and three case series. There was a high degree of heterogeneity among several studies, and the availability of baseline and outcome data provided was uneven.

Conclusion

At present, there is a lack of high-quality clinical trials of belimumab in the treatment of cSLE. Based on the current research, it is believed that the use of belimumab can inhibit cSLE activity, reduce the dose of corticosteroids and immunosuppressants, and delay kidney damage. Also it shows clinical benefit in alleviating symptoms of monogenic cSLE refractory to standard therapy. More studies are urgently needed to validate the clinical efficacy of belimumab in cSLE and to evaluate its long-term safety in pediatric populations to promote evidence-based practice.

Inborn Errors of Immunity Associated with Elevated IgE

OBJECTIVE

To review the characteristic clinical and laboratory features of inborn errors of immunity that are associated with elevated IgE levels DATA SOURCE: Primary peer-reviewed literature.

STUDY SELECTION

Original research articles reviewed include interventional studies, retrospective studies, case-control studies, cohort studies and review articles related to the subject matter.

RESULTS

An extensive literature review was completed to allow for comprehensive evaluation of several monogenic inborn errors of immunity. This review includes a description of the classic clinical features, common infections, characteristic laboratory findings, specific diagnostic methods (when applicable), and genetic basis of disease of each syndrome. A comprehensive flow diagram was created to assist them in the diagnosis and evaluation of patients with elevated IgE levels who may require evaluation for an IEI.

CONCLUSION

IEI should be considered in patients with elevated IgE levels, especially if they have recurrent infections, eczematous dermatitis, malignancy, lymphoproliferation, autoimmunity, and/or connective tissue abnormalities.

Prolidase deficiency, a rare inborn error of immunity, clinical phenotypes, immunological features, and proposed treatments in twins

Background

Prolidase deficiency (PD) is an autosomal recessive inborn multisystemic disease caused by mutations in the PEPD gene encoding the enzyme prolidase D, leading to defects in turnover of proline-containing proteins, such as collagen. PD is categorized as a metabolic disease, but also as an inborn error of immunity. PD presents with a range of findings including dysmorphic features, intellectual disabilities, recurrent infections, intractable skin ulceration, autoimmunity, and splenomegaly. Despite symptoms of immune dysregulation, only very limited immunologic assessments have been reported and standard therapies for PD have not been described. We report twin females with PD, including comprehensive immunologic profiles and treatment modalities used.

Case presentation

Patient 1 had recurrent infections in childhood. At age 13, she presented with telangiectasia, followed by painful, refractory skin ulcerations on her lower limbs, where skin biopsy excluded vasculitis. She had typical dysmorphic features of PD. Next-generation sequencing revealed pathogenic compound heterozygous mutations (premature stop codons) in the PEPD gene. Patient 2 had the same mutations, typical PD facial features, atopy, and telangiectasias, but no skin ulceration. Both patients had imidodipeptiduria. Lymphocyte subset analysis revealed low-normal frequency of T_reg cells and decreased frequency of expression of the checkpoint molecule CTLA-4 in CD4⁺ T_EM cells. Analysis of Th1, Th2, and Th17 profiles revealed increased inflammatory IL-17⁺ CD8⁺ T_EM cells in both patients and overexpression of the activation marker HLA-DR on CD4⁺ T_EM cells, reflecting a highly activated proinflammatory state. Neither PD patient had specific antibody deficiencies despite low CD4⁺CXCR5⁺ T_fh cells and low class-switched memory B cells. Plasma IL-18 levels were exceptionally high.

Conclusions

Immunologic abnormalities including skewed frequencies of activated inflammatory CD4⁺ and CD8⁺ T_EM cells, decreased CTLA-4 expression, and defects in memory B cells may be a feature of immune dysregulation associated with PD; however, a larger sample size is required to validate these findings. The high IL-18 plasma levels suggest underlying autoinflammatory processes.

Simultaneous Onset of Pediatric Systemic Lupus Erythematosus in Twin Brothers: Case Report

There are hundreds of twin adult patients with systemic lupus erythematosus (SLE), but male children with SLE are rarely affected. Two monozygotic twin brothers developed SLE at the age of 11 years during 1 month. The index brother manifested with Henoch-Shonlein purpura, accompanied by ANA positivity, and later developed critical left femoral arterial stenosis with high levels of anti-dsDNA, antiphospholipid antibodies, hypocomplementemia, and Coombs-positive hemolytic anemia. At that time his twin brother had only identical autoimmune findings and developed clinical manifestation (myositis and fasciitis) a month later. Both twins had increased IFN-score and shared a heterozygous variant in the RNASEL gene. Index patients developed scalp rash and nephritis 6 months after their parents refused the treatment which has been lasted for 1 year after disease diagnostics.

CONCLUSION

The simultaneous onset of the pediatric SLE in the male twin is a very rare situation suspected monogenic origin of the disease. Further functional studies are required to confirm the causative role of the mutation.

Impaired respiratory burst contributes to infections in PKCδ-deficient patients

Patients with autosomal recessive protein kinase C δ (PKCδ) deficiency suffer from childhood-onset autoimmunity, including systemic lupus erythematosus. They also suffer from recurrent infections that overlap with those seen in patients with chronic granulomatous disease (CGD), a disease caused by defects of the phagocyte NADPH oxidase and a lack of reactive oxygen species (ROS) production. We studied an international cohort of 17 PKCδ-deficient patients and found that their EBV-B cells and monocyte-derived phagocytes produced only small amounts of ROS and did not phosphorylate p40phox normally after PMA or opsonized Staphylococcus aureus stimulation. Moreover, the patients' circulating phagocytes displayed abnormally low levels of ROS production and markedly reduced neutrophil extracellular trap formation, altogether suggesting a role for PKCδ in activation of the NADPH oxidase complex. Our findings thus show that patients with PKCδ deficiency have impaired NADPH oxidase activity in various myeloid subsets, which may contribute to their CGD-like infectious phenotype.

Interferons in Systemic Lupus Erythematosus

Skewing of type I interferon (IFN) production and responses is a hallmark of systemic lupus erythematosus (SLE). Genetic and environmental contributions to IFN production lead to aberrant innate and adaptive immune activation even before clinical development of disease. Basic and translational research in this arena continues to identify contributions of IFNs to disease pathogenesis, and several promising therapeutic options for targeting of type I IFNs and their signaling pathways are in development for treatment of SLE patients.

An Update on the Management of Childhood-Onset Systemic Lupus Erythematosus

Childhood-onset systemic lupus erythematosus (cSLE) is a prototype of a multisystemic, inflammatory, heterogeneous autoimmune condition. This disease is characterized by simultaneous or sequential organ and system involvement, with unpredictable flare and high levels of morbidity and mortality. Racial/ethnic background, socioeconomic status, cost of medications, difficulty accessing health care, and poor adherence seem to impact lupus outcomes and treatment response. In this article, the management of cSLE patients is updated. Regarding pathogenesis, a number of potential targets for drugs have been studied. However, most treatments in pediatric patients are off-label drugs with recommendations based on inadequately powered studies, therapeutic consensus guidelines, or case series. Management practices for cSLE patients include evaluations of disease activity and cumulative damage scores, routine non-live vaccinations, physical activity, and addressing mental health issues. Antimalarials and glucocorticoids are still the most common drugs used to treat cSLE, and hydroxychloroquine is recommended for nearly all cSLE patients. Disease-modifying antirheumatic drugs (DMARDs) should be standardized for each patient, based on disease flare and cSLE severity. Mycophenolate mofetil or intravenous cyclophosphamide is suggested as induction therapy for lupus nephritis classes III and IV. Calcineurin inhibitors (cyclosporine, tacrolimus, voclosporin) appear to be another good option for cSLE patients with lupus nephritis. Regarding B-cell-targeting biologic agents, rituximab may be used for refractory lupus nephritis patients in combination with another DMARD, and belimumab was recently approved by the US Food and Drug Administration for cSLE treatment in children aged > 5 years. New therapies targeting CD20, such as atacicept and telitacicept, seem to be promising drugs for SLE patients. Anti-interferon therapies (sifalimumab and anifrolumab) have shown beneficial results in phase II randomized control trials in adult SLE patients, as have some Janus kinase inhibitors, and these could be alternative treatments for pediatric patients with severe interferon-mediated inflammatory disease in the future. In addition, strict control of proteinuria and blood pressure is required in cSLE, especially with angiotensin-converting enzyme inhibitor and angiotensin receptor blocker use.

Type I Interferons in the Pathogenesis and Treatment of Autoimmune Diseases

Type I interferons (IFN-Is) are a very important group of cytokines that are produced by innate immune cells but also act on adaptive immune cells. IFN-Is possess antiviral, antitumor, and anti-proliferative effects, as well are associated with the initiation and maintenance of autoimmune disorders. Studies have shown that aberrantly expressed IFN-Is and/or type I IFN-inducible gene signatures in the serum or tissues of patients with autoimmune disorders are linked to their pathogenesis, clinical manifestations, and disease activity. Type I interferonopathies with mutations in genes impacting the type I IFN signaling pathway have shown symptoms and characteristics similar to those of systemic lupus erythematosus (SLE). Furthermore, both interventions in animal models and clinical trials of therapies targeting the type I IFN signaling pathway have shown efficacy in the treatment of autoimmune diseases. Our review aims to summarize the functions and targeted therapies (as well as clinical trials) of IFN-Is in both adult and pediatric autoimmune diseases, such as SLE, pediatric SLE (pSLE), rheumatoid arthritis (RA), juvenile idiopathic arthritis (JIA), juvenile dermatomyositis (JDM), Sjögren syndrome (SjS), and systemic sclerosis (SSc), discussing the potential abnormal regulation of transcription factors and epigenetic modifications and providing a potential mechanism for pathogenesis and therapeutic strategies for future clinical use.

Atypical and Rare Forms of Cutaneous Lupus Erythematosus: The Importance of the Diagnosis for the Best Management of Patients

Lupus erythematosus (LE) is an autoimmune disease with a wide range of clinical and cutaneous manifestations. Along with the well-known typical cutaneous manifestations of LE, some cutaneous manifestations are rarer, but still characteristic, enabling the dermatologist and the general practitioner who know them to suspect cutaneous LE (CLE) and investigate a possible underlying systemic involvement. Indeed, not infrequently a skin manifestation is the first presentation of systemic LE (SLE), and >75% of SLE patients show signs of skin disease during the course of the illness. Especially, SLE involvement occurs in cases of acute CLE, while it is uncommon in subacute CLE and rare in chronic CLE. This review aims to concentrate especially on atypical cutaneous manifestations of LE to enable the clinician to diagnose even the rarest forms of CLE.

Primary Immunodeficiency in Children With Autoimmune Cytopenias: Retrospective 154-Patient Cohort

Background

Primary immunodeficiency is common among patients with autoimmune cytopenia.

Objective

The purpose of this study is to retrospectively identify key clinical features and biomarkers of primary immunodeficiency (PID) in pediatric patients with autoimmune cytopenias (AIC) so as to facilitate early diagnosis and targeted therapy.

Methods

Electronic medical records at a pediatric tertiary care center were reviewed. We selected 154 patients with both AIC and PID (n=17), or AIC alone (n=137) for inclusion in two cohorts. Immunoglobulin levels, vaccine titers, lymphocyte subsets (T, B and NK cells), autoantibodies, clinical characteristics, and response to treatment were recorded.

Results

Clinical features associated with AIC-PID included splenomegaly, short stature, and recurrent or chronic infections. PID patients were more likely to have autoimmune hemolytic anemia (AIHA) or Evans syndrome than AIC-only patients. The AIC-PID group was also distinguished by low T cells (CD3 and CD8), low immunoglobulins (IgG and IgA), and higher prevalence of autoantibodies to red blood cells, platelets or neutrophils. AIC diagnosis preceded PID diagnosis by 3 years on average, except among those with partial DiGeorge syndrome. AIC-PID patients were more likely to fail first-line treatment.

Conclusions

AIC patients, especially those with Evans syndrome or AIHA, should be evaluated for PID. Lymphocyte subsets and immune globulins serve as a rapid screen for underlying PID. Early detection of patients with comorbid PID and AIC may improve treatment outcomes. Prospective studies are needed to confirm the diagnostic clues identified and to guide targeted therapy.

Monogenic lupus due to spondyloenchondrodysplasia with spastic paraparesis and intracranial calcification: case-based review

Spondyloenchondrodysplasia (SPENCD) is a rare skeletal dysplasia characterized with platyspondyly and metaphyseal lesions of the long bones mimicking enchondromatosis, resulting in short stature. SPENCD often coexists with neurologic disorders and immune dysregulation. Spasticity, developmental delay and intracranial calcification are main neurologic abnormalities. Large spectrum of immunologic abnormalities may be seen in SPENCD, including immune deficiencies and autoimmune disorders with autoimmune thrombocytopenia and systemic lupus erythematosus as the most common phenotypes. SPENCD is caused by loss of tartrate-resistant acid phosphatase (TRAP) activity, due to homozygous mutations in ACP5, playing a role in non-nucleic acid-related stimulation/regulation of the type I interferon pathway. We present two siblings, 13-year-old girl and 25-year-old boy with SPENCD, from consanguineous parents. Both patients had short stature, platyspondyly, metaphyseal changes, spastic paraparesis, mild intellectual disability, and juvenile-onset SLE. The age at disease-onset was 2 years for girl and 19 years for boy. Both had skin and mucosa involvement. The age at diagnosis of SLE was 4 years for girl, and 19 years for boy. The clinical diagnosis of SPENCD was confirmed by sequencing of ACP5 gene, which revealed a homozygous c.155A > C (p.K52T), a variant reported before as pathogenic. Juvenile-onset SLE accounts for about 15-20% of all SLE cases. But, the onset of SLE before 5-years of age and also monogenic SLE are rare. Our case report and the literature review show the importance of multisystemic evaluation in the diagnosis of SPENCD and to remind the necessity of investigating the monogenic etiology in early-onset and familial SLE cases.

Contributions of de novo variants to systemic lupus erythematosus

By performing whole-genome sequencing in a Swedish cohort of 71 parent-offspring trios, in which the child in each family is affected by systemic lupus erythematosus (SLE, OMIM 152700), we investigated the contribution of de novo variants to risk of SLE. We found de novo single nucleotide variants (SNVs) to be significantly enriched in gene promoters in SLE patients compared with healthy controls at a level corresponding to 26 de novo promoter SNVs more in each patient than expected. We identified 12 de novo SNVs in promoter regions of genes that have been previously implicated in SLE, or that have functions that could be of relevance to SLE. Furthermore, we detected three missense de novo SNVs, five de novo insertion-deletions, and three de novo structural variants with potential to affect the expression of genes that are relevant for SLE. Based on enrichment analysis, disease-affecting de novo SNVs are expected to occur in one-third of SLE patients. This study shows that de novo variants in promoters commonly contribute to the genetic risk of SLE. The fact that de novo SNVs in SLE were enriched to promoter regions highlights the importance of using whole-genome sequencing for identification of de novo variants.

Monogenic lupus due to spondyloenchondrodysplasia with spastic paraparesis and intracranial calcification: case-based review

Spondyloenchondrodysplasia (SPENCD) is a rare skeletal dysplasia characterized with platyspondyly and metaphyseal lesions of the long bones mimicking enchondromatosis, resulting in short stature. SPENCD often coexists with neurologic disorders and immune dysregulation. Spasticity, developmental delay and intracranial calcification are main neurologic abnormalities. Large spectrum of immunologic abnormalities may be seen in SPENCD, including immune deficiencies and autoimmune disorders with autoimmune thrombocytopenia and systemic lupus erythematosus as the most common phenotypes. SPENCD is caused by loss of tartrate-resistant acid phosphatase (TRAP) activity, due to homozygous mutations in ACP5, playing a role in non-nucleic acid-related stimulation/regulation of the type I interferon pathway. We present two siblings, 13-year-old girl and 25-year-old boy with SPENCD, from consanguineous parents. Both patients had short stature, platyspondyly, metaphyseal changes, spastic paraparesis, mild intellectual disability, and juvenile-onset SLE. The age at disease-onset was 2 years for girl and 19 years for boy. Both had skin and mucosa involvement. The age at diagnosis of SLE was 4 years for girl, and 19 years for boy. The clinical diagnosis of SPENCD was confirmed by sequencing of ACP5 gene, which revealed a homozygous c.155A > C (p.K52T), a variant reported before as pathogenic. Juvenile-onset SLE accounts for about 15–20% of all SLE cases. But, the onset of SLE before 5-years of age and also monogenic SLE are rare. Our case report and the literature review show the importance of multisystemic evaluation in the diagnosis of SPENCD and to remind the necessity of investigating the monogenic etiology in early-onset and familial SLE cases.

A systematic review of the role of eculizumab in systemic lupus erythematosus-associated thrombotic microangiopathy

Background

Lupus nephritis (LN) is a severe consequence of systemic lupus erythematosus (SLE) that affects approximately 40% of patients. Pathogenic immune complexes that are characteristic of LN deposit in the kidney and activate immune mediated pathways including the complement system. Complete remission rates in LN are approximately 44% highlighting the need for new treatment strategies in these patients. Eculizumab is a fully humanised IgG2/IgG4 monoclonal antibody directed at C5 and thus prevents the formation of the terminal complement complex. Eculizumab is successfully used in atypical haemolytic uraemic syndrome (aHUS) and paroxysomal nocturnal haemoglobinuria (PNH) but it is not standardly used in LN. The aim of this project was to determine whether there is any role for eculizumab as adjunctive therapy in LN.

Methods

Using a predefined search strategy on Ovid MEDLINE and EMBASE the literature was reviewed systematically to identify studies in which eculizumab had been used to treat patients with SLE. All patients were included that were treated with complement inhibitors. Favourable outcome in this study was defined as resolution of symptoms that led to treatment, discharge from hospital or recovery of renal function. Patients were excluded if there was no outcome data or if complement inhibition was unrelated to their SLE.

Results

From 192 abstracts screened, 14 articles were identified, involving 30 patients. All SLE patients administered eculizumab were treated for thrombotic microangiopathy (TMA) secondary to LN diagnosed either histologically (66%) or as part of a diagnosis of aHUS (73%). 93% of patients had a favourable outcome in response to eculizumab treatment, of which 46% had a favourable outcome and successfully stopped treatment without relapse in symptoms during a median follow up of 7 months. Three patients (10%) reported adverse outcomes related to eculizumab therapy.

Conclusions

Scientific evidence supports the involvement of complement in the pathogenesis of LN however the role of complement inhibition in clinical practice is limited to those with TMA features. This systematic review showed that in cases of LN complicated with TMA, eculizumab seems to be a very efficacious therapy. Further evidence is required to determine whether patients with refractory LN may benefit from adjunctive complement inhibition.

Retroviruses in the pathogenesis of systemic lupus erythematosus: Are they potential therapeutic targets?

The pathogenesis of systemic lupus erythematosus (SLE) is characterised by the hyper-activation of immunologic pathways related to the antiviral response. Exogenous and endogenous retroviruses, by integrating their DNA templates in the host cell genome, may epigenetically control the transcription of genes involved in the immune response. Furthermore, their nucleic acids or neo-synthesized proteins could stimulate the sensor molecules placed upstream the inflammatory cascade. Exogenous retroviruses, like human immunodeficiency virus, have been associated to SLE-like manifestations or to a fair SLE diagnosis. In addition, there is some evidence confirming a pathogenic role of human endogenous retroviruses in SLE. In line with these data, the use of antiretroviral agents could represent an attractive opportunity in the future therapeutic algorithms of this disease, but studies are still missing.

New Horizons in the Genetic Etiology of Systemic Lupus Erythematosus and Lupus-Like Disease: Monogenic Lupus and Beyond

Systemic lupus erythematosus (SLE) is a clinically and genetically heterogeneous autoimmune disease. The etiology of lupus and the contribution of genetic, environmental, infectious and hormonal factors to this phenotype have yet to be elucidated. The most straightforward approach to unravel the molecular pathogenesis of lupus may rely on studies of patients who present with early-onset severe phenotypes. Typically, they have at least one of the following clinical features: childhood onset of severe disease (<5 years), parental consanguinity, and presence of family history for autoimmune diseases in a first-degree relative. These patients account for a small proportion of patients with lupus but they inform considerable knowledge about cellular pathways contributing to this inflammatory phenotype. In recent years with the aid of new sequencing technologies, novel or rare pathogenic variants have been reported in over 30 genes predisposing to SLE and SLE-like diseases. Future studies will likely discover many more genes with private variants associated to lupus-like phenotypes. In addition, genome-wide association studies (GWAS) have identified a number of common alleles (SNPs), which increase the risk of developing lupus in adult age. Discovery of a possible shared immune pathway in SLE patients, either with rare or common variants, can provide important clues to better understand this complex disorder, it's prognosis and can help guide new therapeutic approaches. The aim of this review is to summarize the current knowledge of the clinical presentation, genetic diagnosis and mechanisms of disease in patents with lupus and lupus-related phenotypes.

The pathogenesis of systemic lupus erythematosus: Harnessing big data to understand the molecular basis of lupus

Systemic lupus erythematosus (SLE) is a chronic, systemic autoimmune disease that causes damage to multiple organ systems. Despite decades of research and available murine models that capture some aspects of the human disease, new treatments for SLE lag behind other autoimmune diseases such as Rheumatoid Arthritis and Crohn's disease. Big data genomic assays have transformed our understanding of SLE by providing important insights into the molecular heterogeneity of this multigenic disease. Gene wide association studies have demonstrated more than 100 risk loci, supporting a model of multiple genetic hits increasing SLE risk in a non-linear fashion, and providing evidence of ancestral diversity in susceptibility loci. Epigenetic studies to determine the role of methylation, acetylation and non-coding RNAs have provided new understanding of the modulation of gene expression in SLE patients and identified new drug targets and biomarkers for SLE. Gene expression profiling has led to a greater understanding of the role of myeloid cells in the pathogenesis of SLE, confirmed roles for T and B cells in SLE, promoted clinical trials based on the prominent interferon signature found in SLE patients, and identified candidate biomarkers and cellular signatures to further drug development and drug repurposing. Gene expression studies are advancing our understanding of the underlying molecular heterogeneity in SLE and providing hope that patient stratification will expedite new therapies based on personal molecular signatures. Although big data analyses present unique interpretation challenges, both computationally and biologically, advances in machine learning applications may facilitate the ability to predict changes in SLE disease activity and optimize therapeutic strategies.

Whole exome sequencing in childhood-onset lupus frequently detects single gene etiologies

BACKGROUND

Systemic lupus erythematosus (SLE) comprise a diverse range of clinical manifestations. To date, more than 30 single gene causes of lupus/lupus like syndromes in humans have been identified. In the clinical setting, identifying the underlying molecular diagnosis is challenging due to phenotypic and genetic heterogeneity.

METHODS

We employed whole exome sequencing (WES) in patients presenting with childhood-onset lupus with severe and/or atypical presentations to identify cases that are explained by a single-gene (monogenic) cause.

RESULTS

From January 2015 to June 2018 15 new cases of childhood-onset SLE were diagnosed in Edmond and Lily Safra Children's Hospital. By WES we identified causative mutations in four subjects in five different genes: C1QC, SLC7A7, MAN2B1, PTEN and STAT1. No molecular diagnoses were established on clinical grounds prior to genetic testing.

CONCLUSIONS

We identified a significant fraction of monogenic SLE etiologies using WES and confirm the genetic locus heterogeneity in childhood-onset lupus. These results highlight the importance of establishing a genetic diagnosis for children with severe or atypical lupus by providing accurate and early etiology-based diagnoses and improving subsequent clinical management.

Exome sequencing revealed C1Q homozygous mutation in Pediatric Systemic Lupus Erythematosus

INTRODUCTION AND OBJECTIVES

Pediatric Systemic Lupus Erythematosus (pSLE) is an autoimmune disorder of children. Early disease onset raises the probability of genetic etiology and it is more severe than adult SLE.

PATIENTS AND METHODS

Herein an eight-year-old girl with pSLE from consanguineous parents is reported.

RESULTS

Although she was diagnosed as pSLE since the age of two years, Whole Exome Sequencing (WES) revealed a rare stop-gained C>T mutation in C1QA gene. The variant was validated and segregated in patient and the family. Furthermore, serum levels of the C1q protein were measured and found to be much lower than normal ranges.

CONCLUSIONS

This study indicated that C1Q deficiency should be considered as a differential diagnosis of pSLE. Therefore, measurement of C1q should be recommended in all cases with pSLE.

Monogenic Lupus: A Developing Paradigm of Disease

Monogenic lupus is a form of systemic lupus erythematosus (SLE) that occurs in patients with a single gene defect. This rare variant of lupus generally presents with early onset severe disease, especially affecting the kidneys and central nervous system. To date, a significant number of genes have been implicated in monogenic lupus, providing valuable insights into a very complex disease process. Throughout this review, we will summarize the genes reported to be associated with monogenic lupus or lupus-like diseases, and the pathogenic mechanisms affected by the mutations involved upon inducing autoimmunity.

Successful use of ofatumumab in two cases of early-onset juvenile SLE with thrombocytopenia caused by a mutation in protein kinase C δ

BACKGROUND

We previously described an endogamous Pakistani kindred in whom we identified a novel homozygous missense mutation in the PRKCD gene encoding for protein kinase C δ (PKCδ) as a cause of monogenic systemic lupus erythematosus (SLE). PKCδ has a role in the negative regulation of B cells. Given the nature of the disease, a logical targeted therapeutic approach in these patients is B cell depletion. Indeed, the 3 siblings all had a marked clinical response and resolution of symptoms with rituximab, although 2 of the siblings had severe reactions to rituximab thus precluding further treatment with this. We therefore describe the first successful use of ofatumumab for this rare form of monogenic SLE.

CASE PRESENTATION

All three affected siblings presented with SLE before the age of 3-years with lethargy, intermittent fever, thrombocytopenia, cutaneous involvement, alopecia, and hepatosplenomegaly. Tubulointerstitial nephritis was also present in 1 of the siblings. Homozygosity mapping followed by whole exome sequencing identified a homozygous missense mutation in PRKCD (p.Gly432Trp), subsequently confirmed by Sanger sequencing to be present in all 3 siblings. All 3 patients were initially treated with rituximab, however 2 of the siblings developed severe infusion-related reactions. For subsequent disease flare in these individuals we therefore used an alternative B cell depleting agent, ofatumumab (300 mg/1.73m² on day 1; 700 mg/1.73m² on day 15). This resulted in marked clinical improvement in both patients. To the best of our knowledge, this is the first report describing the successful use of ofatumumab for PKCδ deficiency.

CONCLUSIONS

PKCδ deficiency causes a monogenic form of SLE which responds well to B cell depletion. Ofatumumab is also likely to have a therapeutic role for sporadic juvenile SLE (jSLE) patients intolerant of rituximab.