We report two siblings with hematopoietic protein 1 (HEM1), also named Nck-associated protein 1-like (NCKAP1L), deficiency and varying clinical phenotype and the first case of successful hematopoietic stem cell transplantation for recurrent infections and EBV-induced hemophagocytic lymphohistiocytosis, showing curative potential.

ABSTRACT Juvenile dermatomyositis (JDM) is characterized by a type I interferon (IFN-I) signature associated with disease activity. We previously identified a link between SARS-CoV-2 infection and the onset or relapse of JDM. Here, we show that newly diagnosed JDM patients display an overexpression of IFIH1 (encoding MDA5 protein) at baseline, coupled with an altered response to dsRNA stimulation at proteomic and transcriptomic levels, indicating abnormal activation of this antiviral sensing pathway. Single-cell transcriptomic and chromatin accessibility profiling of peripheral blood mononuclear cells (PBMCs) further revealed myeloid-specific enrichment of interferon-stimulated genes (ISGs) and preferential disruption of this pathway at disease onset, supporting a dysregulated IFN-I state in this cell type. We identified SARS-CoV-2 RNA in muscle biopsies of two Covid-19 pandemic-onset JDM patients, strongly implicating viral infection as a potential trigger of the dysregulated MDA5 immune response. To extend these observations beyond SARS-CoV-2, we screened two independent retrospective cohorts for antibodies against 27 common childhood infections. In our discovery cohort JDM patients showed significantly increased exposure to 4 RNA viruses in line with our immunological findings. Increased exposure to RSV B was confirmed in an independent replication cohort supporting a robust association with JDM pathophysiology. Together, these findings integrate systemic, single-cell, and tissue-level analyses implicating RNA viral infection and biased antiviral sensing in shaping IFN-I responses at JDM onset, providing mechanistic insight into environmentally triggered pathogenesis. One sentence summary Type I interferon dysregulation at juvenile dermatomyositis onset implicates altered dsRNA sensing and RNA viral exposure as potential disease triggers.

Thalhammer et al. report two siblings with hematopoietic protein 1 (HEM1), also named Nck-associated protein 1-like (NCKAP1L), deficiency and varying clinical phenotype and the first case of successful hematopoietic stem cell transplantation for recurrent infections and EBV-induced hemophagocytic lymphohistiocytosis, showing curative potential.

Mucointegration is as important as osseointegration to ensure the survival of implant-supported prosthesis. Indeed, effective soft tissue integration (STI) prevents the appearance of complication through bacterial dissemination. To optimize STI, electrochemical anodization can be used to nanostructure the trans-gingival part of the prosthetic component. Moreover, Selective Laser Melting (SLM) is a new 3D-manufacturing technique that enables the production of customized implant-supported prosthesis with complex geometry. Objective The aim of this study is to evaluate the effect of a SLM manufactured and anodized Ti6Al4V surface on the behaviour of both, human gingival fibroblasts and oral bacteria. Method SLM-Ti6Al4V discs were polished and anodized with defined parameters to obtain nanotubes (NTs) with specific morphology. Surface characterization was assessed through surface topography and wettability. Human gingival Fibroblasts were cultured, and cell morphology was observed by SEM at day 7. Proliferation, viability (day 1,4,7) and adhesion (6 h and 36 h) were analyzed. Then immunofluorescence and RT-qPCR were used to detect the distribution and the gene expression of vinculin at 48 h. An early colonizer (Streptococcus gordonii) was used for a parallel evaluation of bacteriological adhesion. Results SLM-ANO-Ti6Al4V showed similar performances in terms of cytotoxicity, compared with a machined and polished titanium surface currently used in clinics. Interestingly, cell adhesion was enhanced on anodized SLM surfaces, with a difference in the distribution of focal adhesion plaques in HGFs, while biofilm formation of S. gordonii was not affected by anodization. Significance SLM anodized surface showed promising ability to promote STI while controlling bacterial adhesion.

Blau syndrome is a rare autoinflammatory disorder caused by NOD2 mutations, characterized by granulomatous arthritis, uveitis, and dermatitis. While type I interferon signatures are biomarkers in several autoinflammatory diseases, their role in Blau syndrome remains unclear. We assessed the interferon score in 11 patients with Blau syndrome and correlated it with disease activity. Our results demonstrate that type I interferon signatures were detected in only a minority of patients and showed no significant correlation with clinical disease activity, inflammatory markers, or treatment response. These findings suggest that type I interferon signatures are not useful biomarkers for disease monitoring in Blau syndrome, highlighting the need to identify alternative biomarkers reflecting NOD2-mediated inflammatory pathways.

OBJECTIVES:Severe forms of systemic JIA (sJIA), also called paediatric-onset Still's disease are associated with two major life-threatening complications: macrophage activation syndrome (MAS) and severe lung disease. Patients are usually resistant to conventional synthetic (cs) DMARDs, biologic (b) DMARDs, and targeted synthetic (ts) DMARDs. Recently, allogeneic haematopoietic stem cell transplantation (HSCT) has been performed in a small number of patients with refractory and life-threatening disease. We aimed to report outcomes and complications of allogeneic HSCT in patients with severe, refractory sJIA treated at our centre. METHODS:We conducted a retrospective, observational, single-centre study in a tertiary paediatric immunology care centre (Necker Hospital, Paris, France). RESULTS:We report three sJIA patients who underwent allogeneic HSCT at a median age of 3.5 years. All had recurrent MAS; two had lung disease and the HLA-DRB1*15 haplotype, associated with severe delayed hypersensitivity to IL-1/IL-6 inhibitors. Donors were matched sibling donors for the first and third patient, and matched unrelated donor for the second patient. They presented multiple post-graft complications: graft-vs-host disease, infections, thrombotic microangiopathy and severe inflammatory complications on previously affected organs, such as skin and lungs. At a median follow-up of 22 months (20-33) after transplantation, they were all in remission with full-donor chimerism and were off immunosuppressive treatment. CONCLUSION:Allogeneic HSCT can be an effective salvage therapy in patients with refractory sJIA. However, the risk of post-transplant endothelial complications and severe inflammation in previously affected organs, such as joints, skin and lungs deserves particular attention.

Life-threatening hypereosinophilic syndrome (HES) is a rare medical emergency with limited therapeutic options in corticosteroid-refractory cases. Preliminary reports suggest that Janus kinase inhibitors may be beneficial in eosinophil-associated disorders, including HES. We conducted a nationwide multicenter retrospective study to assess ruxolitinib. Thirteen patients with severe acute HES and organ- or life-threatening involvement were included, most requiring intensive care, with massive baseline absolute eosinophil counts (AEC, median 45 × 109/L) and major involvement including eosinophilic myocarditis, ischemic strokes, and vascular thromboses. Ruxolitinib was initiated after a median of 7 days of corticosteroids. A rapid decline in absolute eosinophil counts was observed after initiation of ruxolitinib, with hematologic response rates of 54%, 85%, and 92% at Days 7, 14, and 30. Clinical improvement was observed across organ systems. Adverse events were manageable, although three deaths occurred during follow-up, only one of which occurred on ruxolitinib.

Epstein-Barr virus (EBV) infects the vast majority of humans and establishes lifelong latency, yet causes disease in only a minority of individuals, underscoring the critical role of host determinants. This review examines the recent advances in how host genetics and immunological variation shape susceptibility to EBV across three major disease contexts. First, inborn errors of immunity have revealed essential CD8+ T-cell pathways governing control of EBV-driven B-cell lymphoproliferative disorders, through antigen recognition, co-stimulation, and cytokine signaling. EBVpositive T- and natural killer-cell lymphoproliferative disorders represent a second, more complex disease spectrum that arises through a multistep pathogenesis involving atypical viral entry, impaired immune control and homeostasis, and acquisition of somatic genetic alterations. Finally, we review new mechanistic evidence linking EBV to the development of autoimmune diseases, in particular multiple sclerosis and systemic lupus erythematosus, highlighting how EBV-mediated cell reprogramming amplifies immune dysregulation and selfreactivity. Together, these conditions establish EBV-associated diseases as powerful models for uncovering the complex genetic and immunological principles governing antiviral immunity and immune dysregulation.

OBJECTIVE:This study aimed to establish the role of myositis-specific antibodies (MSAs) in the association between type I interferon (IFN-I) plasma levels and disease activity in juvenile dermatomyositis (JDM). METHODS:We prospectively obtained 400 samples from 101 JDM patients from two independent cohorts. Autoantibody levels were determined for all patients. Muscle activity was assessed using the Childhood-Myositis Assessment Scale (CMAS). Two characterized homebrew digital ELISAs measuring, respectively, all 12 IFN-α subtype protein and IFN-β were used to quantify IFN-I in patient plasma. Receiver operating characteristic (ROC) curve analysis was used to identify IFN-I thresholds associated with CMAS changes. Correlations between IFN-I levels and CMAS were assessed at recruitment using Spearman's test, and longitudinally using mixed-effects models to account for repeated measures. RESULTS:IFN-α levels were higher in melanoma differentiation-associated gene 5 (MDA5)-positive patients while IFN-β levels were comparable across MSA subgroups. IFN-β was found to be more effective than IFN-α in distinguishing between active and inactive muscle disease, and between severe and non-severe disease status. Over the disease course, we identified IFN-β as a reliable biomarker of muscle disease activity regardless of MSA expression. In contrast, IFN-α levels showed a specific association with CMAS only in MDA5-positive patients. CONCLUSION:The exclusive association of IFN-α levels with muscle clinical score in anti-MDA5-positive patients suggests a subgroup-specific pathophysiological mechanism. These findings underscore potentially distinct roles for IFN-I subtypes (IFN-α and IFN-β) as circulating biomarkers of muscle disease activity in JDM according to MSA expression.

Objectives Proteasome-associated autoinflammatory syndromes (PRAAS) include a group of autoinflammatory interferonopathies caused by 20S proteasome dysfunction. We characterised pathomechanisms and treatment responses of patients with a de novo, dominant-negative (DN)-proteasome subunit beta type-8 (PSMB8) variant. Methods Patients with the DN-PSMB8 p.G209R variant encoding a mutant β5i subunit of the 20S immunoproteasome were evaluated. Interferon biomarkers, proteasome activity, structural modelling, and proteotoxic stress responses were assessed. Patients’ T cells underwent integrated transcriptomic and proteomic profiling to characterise immune dysregulation, proteotoxic stress responses, mitochondrial function, and type I interferon (IFN-I) associated stress signalling. Results Patients with DN-PRAAS presented with early-onset systemic inflammation, panniculitis, cytopenias, infections, and porto-sinusoidal vascular liver disease (PSVD), indicating broader immune dysfunction that partially responds to Janus kinase inhibition and/or interferon-α/β receptor blockade (anifrolumab). Mechanistically, the PSMB8 p.G209R variant caused steric hindrance that impaired β5i propeptide processing and final 20S proteasome formation, resulting in intracellular protein aggregation, impaired mitochondrial metabolism, and altered neutral lipid processing. The IFN-I signature of patients’ T cells was reduced by blockade of 2 integrated stress response (ISR)-regulating kinases, protein kinase R (PKR) and general control nonderepressible 2 (GCN2), and by Janus kinase signalling. Conclusions The DN-PSMB8 p.G209R variant broadens the clinical and mechanistic PRAAS spectrum by causing 20S proteasome maturation arrest and uncovering a convergence between mitochondrial dysfunction and the ISR. Our findings implicate cytopenia in a pattern of vascular pathology, including PSVD of the liver. We further identify PKR and GCN2 as key mediators of maladaptive IFN-I responses and potential therapeutic targets.

A key challenge in using melt electrowriting (MEW) technology is incorporating large amounts of bioactive inorganic materials, such as hydroxyapatite (HA). In the present study, following optimization of the fabrication parameters, 40 %-HA (HA40) nanoparticles were pre-mixed into medical-grade polycaprolactone (PCL) and processed using the MEW (MEW) technique to mimic the structure and function of the natural extracellular matrix (ECM) for bone regeneration. The HA40 fibrous composite scaffolds showed continuous writing and obtained a well-connected and orderly stacked fibre with a small diameter size (67 ± 8.5 µm). A major result of the present study was the successful enrichment and accumulation of the HA particles, which mostly occurred on the MEW fibre external surfaces. This design allows for direct interfacial interaction with human periodontal ligament cells (hPDLCs). We systematically investigated the behaviour and function of hPDLCs on the HA40 composite scaffold, alongside parameters related to mineralization. The HA40 scaffold demonstrated significantly higher metabolic activity and enhanced expression of osteopontin compared to PCL-only scaffolds, as well as increased levels of ALP and COL1. The study's findings demonstrate that bioactive composite scaffolds, incorporating 40 % HA into m-PCL via MEW, effectively enhance the biological response of the ECM and are promising for potential applications in bone regeneration.

Periodontal ligament stem cells (hPDLSCs) are mechanosensing cells responding to mechanical forces. This study investigates the impact of decellularised extracellular matrix (dECM) derived from intermittent compressive force (ICF)-treated hPDLSCs on osteogenic differentiation. hPDSCLs were subjected to ICF loading at 1.5 g/cm2 for 24 h and then maintained with normal medium (N) or osteogenic induction medium (OM) followed by a decellularisation process. dECMs derived from ICF (dECM-ICF) were characterised using a scanning electron microscope, energy-dispersive X-ray spectroscopy, and proteomic analysis. hPDLSCs were re-seeded on dECM-ICF. Cell proliferation and viability were examined by resazurin and LIVE/DEAD assays. Mineralisation was determined by Alizarin Red S staining. Results demonstrated that dECM-ICF-derived from OM (dECM-ICF-OM) exhibited a fibrillar network structure and showed no cellular component while preserving fibronectin and type I collagen. dECM-ICF exhibited biocompatibility, as indicated by the absence of cytotoxic effects and the ability of hPDLSCs to attach, spread, and proliferate. dECM-ICF-OM significantly enhanced mineral deposition compared to dECM-ICF from normal conditions (dECM-ICF-N). Proteomic analysis of dECM-ICF demonstrated the upregulated proteins in the PI3K-Akt, Ras, MAPK, mTOR, ErbB, TNF, and VEGF signallings. In conclusion, dECM-ICF supports hPDLSCs growth and osteogenic differentiation. dECM-ICF is a promising cell-free natural scaffold to promote periodontal regeneration.

OBJECTIVES:To evaluate the efficacy and safety of Janus kinase inhibitors (JAKi) in a monocentric series of patients with JDM and to identify factors associated with the achievement of clinically inactive disease (CID). METHODS:Single-centre retrospective study of 39 JDM patients treated with JAKi for at least 6 months. The proportion of patients achieving CID within 6 months after initiation of JAKi was assessed using the PRINTO criteria and the Skin Disease Activity Score. Type 1 IFN gene signature, serum IFN-α and IFN-β protein titres were measured as potential response biomarkers. RESULTS:Thirty-nine patients with JDM were included. Partial or complete CID was achieved in 32/39 (82%) patients after 6 months of treatment. In responders, the mean steroid dose decreased from 1 to 0 mg/kg/day (P = 0.001) and all other medications were withdrawn. In multivariable analysis, the presence of anti-transcriptional intermediary factor 1 gamma (anti-TIF1γ) Abs was the only factor at JDM onset associated with the absence of CID (P < 0.001). A significant decrease in the median Type 1 IFN score and serum IFN-α from the diagnosis of JDM to the 6-month follow-up was observed only in patients with CID. JAKi-related adverse events consisted of infections in nine patients (including five herpes zoster infections) and weight gain in three patients. CONCLUSIONS:JAKi induced CID in the majority of new-onset and refractory JDM patients, except in a subset of patients with refractory TIF1γ-positive JDM. Overall tolerance was acceptable. These results need to be validated in a larger prospective international cohort study.

Novel dominant PSMB10 variants cause severe combined immunodeficiency and life-threatening liver disease in three pediatric patients. These mutations impair immunoproteasome assembly through a dominant-negative effect on PSMB9, likely disrupting lymphocyte survival and endothelial function, and are associated with poor outcomes after hematopoietic stem cell transplantation.

Introduction : Alternative donor Hematopoietic Stem Cell Transplantation (HSCT) is often associated with delayed immune reconstitution compared to matched donors, especially in recipients of CD34+-selected haploidentical transplants. We previously demonstrated in preclinical models that the administration of CD7+ T cell progenitors, produced ex vivo, promotes thymic regeneration and accelerates polyclonal T-cell production. These findings supported the clinical development of human allogenic T lymphoid progenitors (HTLP) to accelerate post-HSCT immune reconstitution in transplanted patients for Severe Combined Immune Deficiencies (SCID). Here, we present the final results of the HTLP-Necker study. Method : We conducted a first-in-human, open-label clinical trial (EudraCT 2019-004883-23) to evaluate the safety and efficacy of HTLP administered after haplo CD34+-selected allogeneic HSCT in patients with SCID. Fresh HTLP were infused between days +7 or after cryopreservation at +14 post-HSCT, following ATG clearance. The Investigational Medicinal Product was manufactured under GMP-conditions from donor CD34+ cells and consisted of CD7+ CD3– lymphoid progenitors. Key outcomes included safety, engraftment, T-cell recovery, thymic activity, and infection rates. Results: Four SCID patients received HTLP following CD34+-selected HSCT. HTLP products showed robust differentiation (median 79.7% CD7+ CD3–) and expansion (median 14.7-fold). Infused doses ranged from 0.1 to 0.3 ×10⁶ CD7+CD3-cells/kg, with minimal residual CD3+ cells (<11.2/kg). After a median follow-up of 63 months (range, 1.5-156 months), no infusion-related toxicity or chromosomal instability was observed. One patient died from severe veno-occlusive disease (VOD) on day 53, unrelated to HTLP. Two out of three patients achieved successful primary engraftment, no grade ≥2 acute Graft Versus Host Disease (GVHD) occurred, and CD3+ CD4+ TCRαβ+ T cells exceeded 50/μL by month four. One patient with residual maternal T-cells experienced a temporary skin flare linked to maternal T-cell alloreactivity, as confirmed by chimerism studies. The progressive acquisition of allogeneic T chimerism is associated with the resolution of maternal-fetal GVH symptoms. We performed short and long-term analysis of intrathymic activity (TREC, RTE quantification, and thymic ultrasound). Both patients experienced effective long-term T cell reconstitution, with 1185 and 1672 T-CD4/mm³, respectively, and 65% of RTE at M24. No viral reactivations or disease relapses were reported. To contextualize these results, we performed a Bayesian comparative analysis of CD4+ T-cell reconstitution against age- and genotype-matched SCID patients receiving standard haploidentical CD34+-selected HSCT. HTLP-treated patients showed earlier and stronger CD4+ recovery. In addition, TCRβ repertoire analysis revealed greater diversity compared to historical controls. Conclusion : HTLP infusion post-HSCT is feasible and safe, with no infusion-related toxicity or severe GVHD. Longitudinal data demonstrate early, robust, and sustained T-cell reconstitution, supported by intrathymic activity. HTLPs may represent a promising strategy to enhance immune recovery in patients undergoing alternative donor transplantation.