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Key Points Our understanding of the pathogenesis of systemic lupus erythematosus (SLE) has changed rapidly over the past decade Refinements in our understanding over the past 3 years have led to the potential for precision targeting of therapeutic strategies Advances in epigenetic therapeutic agents and the manipulation of cells ex vivo have the potential to further improve patient care In this Review, Tsokos et al . describe recent advances in our understanding of systemic lupus erythematosus (SLE) that are driving repurposing of existing drugs as well as development of new treatments. Cytokines, tolerance pathways, local tissue mediators, and epigenetic mechanisms all show promise as novel targeted therapies that could lead to individualized care in SLE. The aetiology of systemic lupus erythematosus (SLE) is multifactorial, and includes contributions from the environment, stochastic factors, and genetic susceptibility. Great gains have been made in understanding SLE through the use of genetic variant identification, mouse models, gene expression studies, and epigenetic analyses. Collectively, these studies support the concept that defective clearance of immune complexes and biological waste (such as apoptotic cells), neutrophil extracellular traps, nucleic acid sensing, lymphocyte signalling, and interferon production pathways are all central to loss of tolerance and tissue damage. Increased understanding of the pathogenesis of SLE is driving a renewed interest in targeted therapy, and researchers are now on the verge of developing targeted immunotherapy directed at treating either specific organ system involvement or specific subsets of patients with SLE. Accordingly, this Review places these insights within the context of our current understanding of the pathogenesis of SLE and highlights pathways that are ripe for therapeutic targeting.

Systemic autoinflammatory diseases (SAID) are characterized by inappropriate activation of the innate immune system and include not only monogenic periodic fever syndromes but also multifactorial conditions. As SAID are rare and represent a diagnostic challenge, a multidisciplinary approach is important to ensure successful diagnosis and adequate follow-up of these patients. To describe the organization of our multidisciplinary SAID clinic and to characterize our clinical experience, highlighting the benefits of multidisciplinary team management. Our SAID clinic takes place monthly and is managed by pediatric rheumatologists closely collaborating with pediatricians specialized in infectious diseases and immunodeficiencies and one medical geneticist. Patients' data are systematically incorporated in the Rheumatic Diseases Portuguese Register (Reuma.pt). Biological samples are stored in a biobank. We describe our clinical experience based on SAID patients registered into Reuma.pt/SAID between July 2011 and June 2020. We have registered 176 patients, with a median age of disease onset of 3.1 ± 4.4 years and median age at disease diagnosis of 4.7 ± 4.0 years. Most patients were diagnosed with periodic fever, aphthous stomatitis, pharyngitis, adenitis syndrome (PFAPA) (n=133), 20 with undefined SAID (uSAID) and 13 with monogenic SAID, including familial Mediterranean fever (FMF) (n=5), tumor necrosis factor receptor-associated periodic syndrome (TRAPS) (n=1), cryopyrin-associated periodic disease (CAPS) (n=1), and hyperimmunoglobulin D syndrome/mevalonate kinase deficiency (HIDS/MKD) (n=2). A genetic test was performed in 31 patients (18%), and in 26% of these a mutation responsible for the phenotype was found. Thirty-four patients (19%) achieved remission. FMF was the most common monogenic SAID and the percentage of patients with an identified causal mutation was low. A structured electronic clinical record coupled with a biobank and a multidisciplinary approach are crucial to ensure successful diagnosis and adequate follow-up of these patients.

ObjectivesThe main goal of this study was to characterise the frequency and phenotype of B, T follicular helper (Tfh) and T follicular regulatory (Tfr) cells in peripheral blood and the cytokine environment present in circulation in children with extended oligoarticular juvenile idiopathic arthritis (extended oligo JIA) and polyarticular JIA (poly JIA) when compared with healthy controls, children with persistent oligoarticular JIA (persistent oligo JIA) and adult JIA patients.MethodsBlood samples were collected from 105 JIA patients (children and adults) and 50 age-matched healthy individuals. The frequency and phenotype of B, Tfh and Tfr cells were evaluated by flow cytometry. Serum levels of APRIL, BAFF, IL-1β, IL-2, IL-4, IL-6, IL-10, IL-17A, IL-21, IL-22, IFN-γ, PD-1, PD-L1, sCD40L, CXCL13 and TNF were measured by multiplex bead-based immunoassay and/or ELISA in all groups included.ResultsThe frequency of B, Tfh and Tfr cells was similar between JIA patients and controls. Children with extended oligo JIA and poly JIA, but not persistent oligo JIA, had significantly lower frequencies of plasmablasts, regulatory T cells and higher levels of Th17-like Tfh cells in circulation when compared with controls. Furthermore, APRIL, BAFF, IL-6 and IL-17A serum levels were significantly higher in paediatric extended oligo JIA and poly JIA patients when compared with controls. These immunological alterations were not found in adult JIA patients in comparison to controls.ConclusionsOur results suggest a potential role and/or activation profile of B and Th17-like Tfh cells in the pathogenesis of extended oligo JIA and poly JIA, but not persistent oligo JIA.

Gene expression studies of peripheral blood mononuclear cells from patients with systemic lupus erythematosus (SLE) have demonstrated a type I interferon signature and increased expression of inflammatory cytokine genes. Studies of patients with Aicardi Goutières syndrome, commonly cited as a single gene model for SLE, have suggested that accumulation of non-coding RNAs may drive some of the pathologic gene expression, however, no RNA sequencing studies of SLE patients have been performed. This study was designed to define altered expression of coding and non-coding RNAs and to detect globally altered RNA processing in SLE. Purified monocytes from eight healthy age/gender matched controls and nine SLE patients (with low-moderate disease activity and lack of biologic drug use or immune suppressive treatment) were studied using RNA-seq. Quantitative RT-PCR was used to validate findings. Serum levels of endotoxin were measured by ELISA. We found that SLE patients had diminished expression of most endogenous retroviruses and small nucleolar RNAs, but exhibited increased expression of pri-miRNAs. Splicing patterns and polyadenylation were significantly altered. In addition, SLE monocytes expressed novel transcripts, an effect that was replicated by LPS treatment of control monocytes. We further identified increased circulating endotoxin in SLE patients. Monocytes from SLE patients exhibit globally dysregulated gene expression. The transcriptome is not simply altered by the transcriptional activation of a set of genes, but is qualitatively different in SLE. The identification of novel loci, inducible by LPS, suggests that chronic microbial translocation could contribute to the immunologic dysregulation in SLE, a new potential disease mechanism.

This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101095084. This work was supported by the Swiss State Secretariat for Education, Research and Innovation (SERI) under contract number 22.00462. This project has also received funding from Fundação para a Ciência e a Tecnologia (FCT–Grant 2022.07462).

Background The gut microbiota has been implicated in the onset and progression of Rheumatoid Arthritis (RA). It has been proposed that gut dysbiosis impairs gut barrier function, leading to alterations in mucosal integrity and immunity. This disruption allows bacterial translocation, contributing to the perpetuation of the inflammatory process. Since diet is recognised as a key environmental factor influencing the gut microbiota, nutritional interventions targeting RA activity are currently being explored. This study aims to investigate whether a dietary intervention based on a typical Mediterranean Diet enriched with fermented foods (MedDiet +) can impact the gut microbiota, intestinal permeability, and RA-related outcomes. Methods One hundred RA patients are being recruited at Unidade Local de Saúde (ULS) Santa Maria in Lisbon, Portugal, and randomly assigned to either the intervention (MedDiet +) or the control group. The 12-week nutritional intervention includes a personalised dietary plan following the MedDiet + pattern, along with educational resources, food basket deliveries, and clinical culinary workshops, all developed and monitored weekly by registered dietitians. The control group receives standardised general healthy diet recommendations at baseline. The intervention's effects will be assessed by evaluating disease activity, functional status, quality of life, intestinal permeability, endotoxemia, inflammatory biomarkers, intestinal and oral microbiota, serum proteomics, and serum glycome profile characterisation. Discussion We anticipate obtaining integrative insights into the interplay between diet, the gut, and RA, while also exploring the underlying mechanisms driving these changes. This study, conducted by a multidisciplinary research team of registered dietitians, rheumatologists, biologists, and immunologists, aims to bridge the current gap between nutrition-related knowledge and RA. Trial registration Registered in ClinicalTrials.gov (NCT06758817; date of registry: January 6th 2025).

Systemic lupus erythematosus (SLE or lupus) is an immune-mediated disease associated with substantial medical burden. Notably, lupus exhibits a striking female bias, with women having significantly higher susceptibility compared to men, up to 14-fold higher in some ethnicities. Supernumerary X chromosome syndromes, like Klinefelter (XXY) and Triple X syndrome (XXX), also present higher SLE prevalence, whereas Turner syndrome (XO) displays lower prevalence. Taken together, SLE prevalence in different X chromosome dosage sceneries denotes a relationship between the number of X chromosomes and the risk of developing lupus. The dosage of X-linked genes, many of which play roles in the immune system, is compensated between males and females through the inactivation of one of the two X chromosomes in female cells. X-chromosome inactivation (XCI) initiates early in development with a random selection of which X chromosome to inactivate, a choice that is then epigenetically maintained in the daughter cells. This process is regulated by the X-Inactive-Specific Transcript ( XIST) , encoding for a long non-coding RNA, exclusively expressed from the inactive X chromosome (Xi). XIST interacts with various RNA binding proteins and chromatin modifiers to form a ribonucleoprotein (RNP) complex responsible for the transcriptional silencing and heterochromatinization of the Xi. This ensures stable silencing of most genes on the X chromosome, with only a few genes able to escape this process. Recent findings suggest that the molecular components involved in XCI, or their dysregulation, contribute to the pathogenesis of lupus. Indeed, nonrandom XCI, elevated gene escape from XCI, and the autoimmune potential of the XIST RNP complex have been suggested to contribute to auto-immune diseases, such as lupus. This review examines these current hypotheses concerning how this dosage compensation mechanism might impact the development of lupus, shedding light on potential mechanisms underlying the pathogenesis of the disease. Plain English summary Lupus is a disease where the immune system mistakenly attacks the body’s own tissues, leading to a range of complicated health issues. Interestingly, lupus is much more common in women (XX) than in men (XY), with women being up to 14 times more likely to develop the condition. Additionally, some genetic conditions involving extra or missing X chromosomes can also affect the chances of getting lupus: Klinefelter (XXY) and Triple X (XXX) syndromes show higher rates of lupus, while conditions like Turner syndrome (XO) have a lower risk. This suggests a link between the number of X chromosomes and the likelihood of developing the disease. In female cells, a process called X-chromosome inactivation (XCI) occurs, where one of the two X chromosomes in each cell is switched off to equalize X chromosome dosage with males. This process is regulated by a gene called XIST , which produces a long non-coding RNA. XIST helps to form a complex of RNA and proteins that silence the inactive X chromosome (Xi), ensuring stable gene expression patterns. Recent research suggests that molecular components or problems with this process might be linked to lupus. This review focuses on three hypotheses in which XCI or its dysregulation could impact lupus: nonrandom XCI, incomplete silencing of certain genes on the Xi, and the potential for the XIST ribonucleoprotein complex to activate the immune system. By investigating these mechanisms, researchers aim to better understand how variations in XCI mechanisms contribute to the development of lupus. Highlights Lupus is an immune-mediated disease with higher prevalence in women than men. Individuals with supernumerary X chromosomes have a higher lupus susceptibility and there is lower prevalence in individuals with Turner syndrome (X0), suggesting that X chromosome dosage may be implicated in lupus pathogenesis. The X chromosome harbors several genes involved in immune responses, some of which are implicated in lupus pathogenesis. The X-linked content between female and male genomes is balanced by a dosage compensation mechanism regulated by the XIST non-coding RNA, known as X-chromosome inactivation (XCI), which silences one of the two X chromosomes in female cells. The molecular components involved in XCI or their dysregulation may actively contribute to lupus pathogenesis in several ways: 1) through the preferential inactivation of one X chromosome (XCI skewing); 2) by increasing XCI escape of X-linked genes involved in immune responses, such as TLR7 , CXCR3 , and CXorf21 ; 3) by being preferential targets for autoimmune responses, as it might be the case for XIST and its protein interactors.

ObjectiveLupus nephritis is a key driver of morbidity and mortality in SLE. Detecting active nephritis on a background of pre-existing renal damage is difficult, leading to potential undertreatment and accumulating injury. An unmet need is a biomarker that distinguishes active lupus nephritis, particularly important in paediatrics where minimising invasive procedures is desirable.MethodsThis was a multicentre, prospective study of 113 paediatric patients with biopsy-proven lupus nephritis. Clinical data and urine were obtained every 3–4 months and patients averaged 2 years on study with seven time points. Urine was analysed for human epidermal growth factor receptor 2 (HER2), tumour necrosis factor-like weak inducer of apoptosis and vascular cell adhesion molecule-1 (VCAM-1) by ELISA. We defined active disease as either a rise in serum creatinine ≥0.3 mg/dL from baseline or a rise in renal Systemic Lupus Erythematosus Disease Activity Index score from the previous visit. These markers were also studied in patients with acute kidney injury, juvenile idiopathic arthritis (JIA), amplified pain syndrome and healthy controls.ResultsThe rate of active disease was 56% over an average of 2 years of follow-up. HER2 and VCAM-1 were significantly elevated at time points with active disease defined by increased serum creatinine compared with time points with inactive disease or patients who never flared. All three biomarkers were associated with new-onset proteinuria and VCAM-1 was elevated at time points preceding new-onset proteinuria. These biomarkers were not increased in acute kidney injury or JIA.ConclusionAll three biomarkers were associated with new onset proteinuria and increased VCAM-1 may predict impending proteinuria. These biomarkers provide potential non-invasive measures for monitoring that may be more sensitive to impending flare than conventional measures.

Chronic recurrent multifocal osteomyelitis is a rare auto-inflammatory condition that primarily affects children and adolescents. It presents with recurrent episodes of pain related to the presence of foci of sterile bone inflammation. The long bones of the lower extremities are more frequently affected and the spine can also be involved. Imaging studies, including whole-body magnetic resonance, are important for diagnosis and detection of asymptomatic lesions. Bone biopsies may be necessary to exclude other diseases, including malignancy and infections. Non-steroidal anti-inflammatory drugs cause relief of symptoms in the majority of cases. Bisphosphonates and TNF-α blockers are alternatives for patients who do not respond or who have spinal involvement.