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In psoriatic arthritis (PsA), predisposing class I HLA alleles, the presence of synovial clonally proliferated CD8 + T cells and autoantibodies all point towards the loss of immune tolerance. However, the key mechanisms that lead to immune dysregulation are not fully understood. In other types of inflammatory arthritis, T regulatory cell (Treg) dysfunction and plasticity at sites of inflammation were suggested to negatively affect peripheral tolerance. We here addressed if Treg variances associate with psoriatic disease. We collected clinical data, sera and peripheral blood mononuclear cells from 13 healthy controls, 21 psoriasis and 21 PsA patients. In addition, we obtained synovial fluid mononuclear cells from 6 PsA patients. We studied characteristics of CD4 + CD25 + CD127loFoxp3 + Tregs by flow cytometry and used ELISA to quantify antibodies against ADAMTSL5, a recently discovered autoantigen in psoriatic disease. In comparison with their circulating counterparts, Tregs from inflamed joints express increased levels of ICOS, CTLA-4 and TIGIT. Furthermore, synovial fluid-derived Tregs have a distinct phenotype, characterized by IL-17A production and upregulation of CD161 and RORγt. We identified a subset of Tregs with intermediate Foxp3 expression as the major cytokine producer. Furthermore, ICOS + Tregs associate with PsA disease activity as measured by PASDAS. Lastly, we observed that presence of the Foxp3int Tregs associates with an increased abundance of anti-ADAMTSL5 autoantibodies. Tregs derived from the inflammatory environment of inflamed PsA joints exhibit a distinct phenotype, which associates with loss of peripheral immune tolerance in psoriatic disease. [ABSTRACT FROM AUTHOR]

Classic regulatory T (T reg ) cells expressing CD4 and the hallmark transcription factor FOXP3 are integral to the prevention of multi-system autoimmunity. However, immune-mediated arthritis is often associated with increased numbers of T reg cells in the inflamed joints. To understand these seemingly conflicting observations, which we collectively describe as 'the T reg paradox', we provide an overview of T reg cell biology with a focus on T reg cell heterogeneity, function and dysfunction in arthritis. We discuss how the inflamed environment constrains the immunosuppressive activity of T reg cells while also promoting the differentiation of T H 17-like T reg  cell, exT reg cell (effector T cells that were formerly T reg cells), and osteoclastogenic T reg cell subsets that mediate tissue injury. We present a new framework to understand T reg cells in joint inflammation and define potential strategies for T reg cell-directed interventions in human inflammatory arthritis., Competing Interests: Competing interests: L.A.H. has received salary support from the Childhood Arthritis and Rheumatology Research Alliance (CARRA); investigator-initiated research grants from BMS; and consulting fees from Sobi, Pfizer and Adaptive Biotechnologies. F.v.W. has previously served as a speaker and/or consultant for Janssen, Johnson & Johnson and Takeda, and has received grants from Regeneron Pharmaceuticals, LEO Pharma, Sanofi, BMS, Galapagos and Takeda. P.A.N. declares consulting relationships with Alkermes, Apollo, BMS, Exo Therapeutics, Fresh Tracks Therapeutics, Merck, Novartis, Pfizer, Qiagen and Sobi; equity in Edelweiss Immune Inc.; investigator-initiated research grants from BMS and Pfizer; and authorship and editorial income from UpToDate, the American Academy of Paediatrics and Arthritis & Rheumatology. All other authors declare no competing interests., (© 2024. Springer Nature Limited.)

Introduction and Objectives: Tralokinumab-a biological that specifically targets interleukin-13-is one of the newer advanced systemic treatments for patients with moderate-to-severe atopic dermatitis (AD). Although safety and efficacy have been shown in phase-III clinical trials, daily practice data are needed. Therefore, the aim of this study was to evaluate 28-week safety and effectiveness, serum proteins and total IgE levels in adult AD patients treated with tralokinumab in daily practice., Materials and Methods: Data of all adult AD patients who started treatment with tralokinumab and participated in the BioDay registry were collected at baseline, and after 4,16 and 28 weeks of treatment. Clinical efficacy was evaluated by clinical outcome measures, such as the Eczema Area and Severity Index (EASI) as well as patient-reported outcome measures, such as the numerical rating scale (NRS) for pruritus. Adverse events were evaluated. In a subgroup of patients, 18 proteins as well as total IgE levels were measured in serum., Results: A total of 84 patients were included, of whom 39 were dupilumab-naïve (D-naïve) and 45 were dupilumab non-naïve (D-non-naïve) patients. All primary outcomes significantly improved during 28 weeks of tralokinumab treatment and the probability of achieving EASI ≤ 7 and NRS-pruritis ≤ 4 was 75.8% (56.9-88.2) and 51.4% (28.0-74.2), respectively. The disease severity-associated proteins TARC/CCL17 and PARC/CCL18 decreased during treatment, and total IgE levels significantly decreased in the D-naïve patients. The most reported adverse events were eye disorders (n = 24, 28.6%). A total of 23 patients (27.4%) discontinued treatment due to adverse events and/or ineffectiveness, with hair loss being the most common adverse event leading to treatment discontinuation (n = 6)., Conclusion: Tralokinumab is an effective treatment for moderate-to-severe AD in adult patients, in both dupilumab-naïve patients and patients who previously failed on dupilumab treatment. The clinical effect is supported by the biological data., (© 2024 The Author(s). Allergy published by European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd.)

Objectives: Novel biomarkers are needed to guide therapy in idiopathic inflammatory myopathies (IIM). Expression of Siglec-1, a type I interferon biomarker, was examined in adult patients with IIM in relation to disease activity and treatment response., Methods: We analysed PBMC samples from 19 newly diagnosed adult IIM patients who participated in a phase-2 pilot study on efficacy of intravenous immunoglobulin (IVIG) monotherapy, and from 9 healthy controls. Siglec-1 expression on monocytes was measured by flow cytometry before and after treatment, and was evaluated in relation to IIM subtype, physician global activity (PhGA) scores, manual muscle strength (MMT) and the Total Improvement Score (TIS)., Results: Diagnoses included dermatomyositis (DM; n = 9), immune-mediated necrotizing myopathy (IMNM; n = 5), non-specific/overlap myositis (NSM/OM; n = 4), and antisynthetase syndrome (ASyS; n = 1). All patients showed increased Siglec-1 expression at baseline. Relative median fluorescence intensity of Siglec-1 was highest in patients with DM. After 9 weeks, follow-up samples were available for 15 patients of whom 10 patients showed a decline in Siglec-1 expression. In DM, Siglec-1 correlated with disease activity (MMT; rs = -0.603, p= 0.013 and PhGA; rs = 0.783, p< 0.001) and with the TIS (rs = -0.786, p= 0.036)., Conclusion: Siglec-1 was increased in treatment-naive IIM patients and showed a decline after IVIG monotherapy. In DM, Siglec-1 expression correlated with relevant clinical measures. This underlines the dynamic role of type I IFN in IIM and the biomarker potential of Siglec-1, in particular in DM. These findings should be further validated in larger cohorts with longer follow-up., (© The Author(s) 2024. Published by Oxford University Press on behalf of the British Society for Rheumatology.)

Thymic involution is a key factor in human immune aging, leading to reduced thymic output and a decline in recent thymic emigrant (RTE) naive T cells in circulation. Currently, the precise definition of human RTEs and their corresponding cell surface markers lacks clarity. Analysis of single-cell RNA-seq/ATAC-seq data distinguished RTEs by the expression of SOX4, IKZF2, and TOX and CD38 protein, whereby surface CD38 hi expression universally identified CD8 + and CD4 + RTEs. We further determined the dynamics of RTEs and mature cells in a cohort of 158 individuals, including age-associated transcriptional reprogramming and shifts in cytokine production. Spectral cytometry profiling revealed two axes of aging common to naive CD8 + and CD4 + T cells: (1) a decrease in CD38 ++ cells (RTEs) and (2) an increase in CXCR3 hi cells. Identification of RTEs enables direct assessment of thymic health. Furthermore, resolving the dynamics of naive T cell remodeling yields insight into vaccination and infection responsiveness throughout aging., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Breastfeeding provides important immunological benefits to the neonate, but how the different immunoactive components in breastmilk contribute to immunity remains poorly understood. Here, we characterized human breastmilk T cells using single-cell RNA-Seq and flow cytometry. Breastmilk contained predominantly memory T cells, with expression of immune signaling genes, high proliferation, and an effector Th1/cytotoxic profile with high cytokine production capacities. Elevated activation was balanced by an enriched Treg population and immune regulatory markers in conventional memory T cells. Gene and surface expression of tissue-residency markers indicate that breastmilk T cells represented tissue-adapted rather than circulatory T cells. In addition, breastmilk T cells had a broad homing profile and higher activation markers in these migratory subsets. The partly overlapping transcriptome profile between breastmilk and breast tissue T cells, particularly cytotoxic T cells, might support a role in local immune defense in the mammary gland. However, unique features of breastmilk, such as Tregs, might imply an additional role in neonatal immune support. We found some correlations between the breastmilk T cell profile and clinical parameters, most notably with maternal and household factors. Together, our data suggest that breastmilk contains an adapted T cell population that exerts their function in specific tissue sites.

Juvenile dermatomyositis is characterized by childhood-onset chronic inflammation of the muscles and skin, with potential involvement of other organs. Patients are at risk for long-term morbidity due to insufficient disease control and steroid-related toxicity. Personalised treatment is challenged by a lack of validated tools that can reliably predict treatment response and monitor ongoing (subclinical) inflammation, and by a lack of evidence regarding the best choice of medication for individual patients. A better understanding of the involved disease mechanisms could reveal potential biomarkers and novel therapeutic targets. In this review, we highlight the most relevant immune and non-immune mechanisms, elucidating the effects of interferon overexpression on tissue alongside the interplay between the interferon signature, mitochondrial function, and immune cells. We review mechanism-based biomarkers that are promising for clinical implementation, and the latest advances in targeted therapy development. Finally, we discuss key steps needed for translating these discoveries into clinical practice., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Saskia R. Veldkamp reports financial support was provided by Prinses Beatrix Spierfonds, the Dutch (neuro)muscular disease foundation, the Netherlands. Saskia R. Veldkamp reports financial support was provided by BAS stichting. Saskia R. Veldkamp reports a relationship with JDM Working Party (Basic Science Lead) of the Pediatric Rheumatology European Society that includes: board membership. Annet van Royen-Kerkhof reports a relationship with Global Conference on Myositis 2024 (Scientific Committee) that includes: board membership. Marc H.A. Jansen reports a relationship with Dutch Association for Pediatrics, Myositis guideline Working Group that includes: board membership. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Severe uveitis is a rare complication of interleukin-4 receptor alpha blocking by dupilumab in topic dermatitis (AD) patients. The aim of this study was to describe five moderate-to-severe AD patients who developed uveitis during dupilumab treatment and to compare the proteomic profile of aqueous humor (AqH) of dupilumab-associated uveitis (n=3/5 available samples) with non-infectious uveitis (n=27) and cataract controls (n=11). Included patients were treated at the University Medical Center Utrecht (the Netherlands). Active dupilumab-associated uveitis complicated by serous detachment, cystoid macular edema, or secondary glaucoma developed within a median of 6.0 months (interquartile range 2.3-16.5 months) after starting dupilumab. Uveitis resolved after discontinuation of dupilumab and/or treatment with local or systemic corticosteroids. Proteomic profiling of AqH revealed that the molecular profile of dupilumab-associated uveitis resembled that of non-infectious uveitis. In conclusion, dupilumab-associated uveitis is a severe adverse event of dupilumab therapy, requiring urgent referral to an ophthalmologist.

Atopic dermatitis (AD) is a chronic inflammatory skin disease for which new targeted therapies are currently available. Due to the increased rates of ocular surface disease (OSD) reported during treatment with these new targeted treatments, more insight into the occurrence and pathomechanism of OSD in moderate-to-severe AD patients is needed. Therefore, this review's first part highlights that most patients with moderate-to-severe AD already have characteristics of OSD before starting targeted treatment. Remarkably, not all AD patients with OSD report ocular symptoms. OSD in AD is associated with less conjunctival goblet cells (GC) compared to healthy controls. In addition, OSD severity in AD patients is associated with high AD activity, the presence of eyelid and/or facial eczema, and high levels of AD-related severity biomarkers in tear fluid. The second part of this review highlights that pre-existing ocular pathology (e.g. in combination with the use of ophthalmic medication or eyelid eczema) may be associated with the development of dupilumab-associated ocular surface disease (DAOSD). During dupilumab treatment, DAOSD (which can be new-onset OSD or worsening of pre-existing OSD) is observed in approximately one-third of the dupilumab-treated AD patients. Anti-inflammatory ophthalmic treatment improves DAOSD, and dose reduction of dupilumab may also be an effective treatment option. The pathomechanism of DAOSD is still not fully elucidated. In a prospective study low, but stable conjunctival GC numbers were observed in moderate-to-severe AD patients, before and during dupilumab treatment. However, the Mucin 5 AC (MUC5AC) expression of GCs decreased during dupilumab treatment, suggesting an impairment of the GC function by dupilumab treatment. In addition, higher dupilumab tear fluid levels were found in dupilumab-treated AD patients with moderate-to-severe OSD compared to patients with no or mild OSD, whereas the dupilumab serum levels are similar. Clinicians should be aware of the frequent occurrence of OSD in moderate-to-severe AD patients, and a low-threshold referral to an ophthalmologist is recommended., (© 2024 The Authors. Clinical & Experimental Allergy published by John Wiley & Sons Ltd.)

With immune checkpoint inhibitors (ICIs) becoming the mainstay of treatment for many cancers, managing their immune-related adverse events (irAEs) has become an important part of oncological care. This Review covers the clinical presentation of irAEs and crucial aspects of reversibility, fatality and long-term sequelae, with special attention to irAEs in specific patient populations, such as those with autoimmune diseases. In addition, the genetic basis of irAEs, along with cellular and humoral responses to ICI therapy, are discussed. Detrimental effects of empirically used high-dose steroids and second-line immunosuppression, including impaired ICI effectiveness, call for more tailored irAE-treatment strategies. We discuss open therapeutic challenges and propose potential avenues to accelerate personalized management strategies and optimize outcomes., (© 2024. Springer Nature America, Inc.)

The mucosal immune system is implicated in the etiology and progression of inflammatory bowel diseases. The lamina propria and epithelium of the gut mucosa constitute two separate compartments, containing distinct T-cell populations. Human CD4 T-cell programming and regulation of lamina propria and epithelium CD4 T cells, especially during inflammation, remain incompletely understood. We performed flow cytometry, bulk, and single-cell RNA-sequencing to profile ileal lamina propria and intraepithelial CD4 T cells (CD4CD8αα, regulatory T cells (Tregs), CD69- and CD69high Trm T cells) in controls and Crohn's disease (CD) patients (paired non-inflamed and inflamed). Inflammation results in alterations of the CD4 T-cell population with a pronounced increase in Tregs and migrating/infiltrating cells. On a transcriptional level, inflammation within the epithelium induced T-cell activation, increased IFNγ responses, and an effector Treg profile. Conversely, few transcriptional changes within the lamina propria were observed. Key regulators including the chromatin remodelers ARID4B and SATB1 were found to drive compartment-specific transcriptional programming of CD4 T(reg) cells. In summary, inflammation in CD patients primarily induces changes within the epithelium and not the lamina propria. Additionally, there is compartment-specific CD4 T-cell imprinting, driven by shared regulators, between the lamina propria and the epithelium. The main consequence of intraepithelial adaptation, irrespective of inflammation, seems to be an overall dampening of broad (pro-inflammatory) responses and tight regulation of lifespan. These data suggest differential regulation of the lamina propria and epithelium, with a specific regulatory role in the inflamed epithelium., (© The Author(s) 2023. Published by Oxford University Press on behalf of the British Society for Immunology.)

Immune checkpoint inhibitors (ICI) have revolutionized the treatment landscape of advanced malignancies, but come with a diverse spectrum of immune-related adverse events (irAEs). Mechanistic studies can aid the transition from expert-opinion to evidence-based irAE treatment strategies. We aimed to longitudinally characterize peripheral blood T and B cell dynamics in ICI-treated patients by multicolor flow cytometry and serum multiplex immunoassay at baseline, ± 3 weeks and ± 6 weeks or upon clinically relevant irAEs. We analyzed samples from 44 ICI-treated patients (24 anti-PD-1 monotherapy, 20 combined anti-PD-1/anti-CTLA-4; cICI), of whom 21 developed irAEs, and 10 healthy donors. IrAEs after cICI were characterized by significantly enhanced proliferation of Th1-associated, mainly (CD4 + ) CD27 - effector memory T cells, as well as Th17-associated immune responses and germinal center activation (reflected by CXCL13 and IL-21 increases). We observed no changes in CD21 lo , memory, class-switched or newly activated B cell subsets. Particularly double-positive PD-1 + LAG-3 + CD8 + T cells showed enhanced cytotoxic capacity in patients with irAEs after cICI. Within anti-PD-1 monotherapy, irAEs were associated with modestly enhanced Th1-associated responses reflected by increased serum CXCL9 and CXCL10. In conclusion, ICI-induced toxicity is dominated by enhanced Th1-associated responses, but in cICI we also found evidence for Th17-associated responses and germinal center activation. Together, our data add to the growing body of evidence that irAEs may be driven by newly activated CD4 + helper T cells, specifically after cICI. This study also supports tailored irAE treatment, based on ICI regimen, and to deploy specific strategies such as Th17 inhibition especially in cICI-associated irAEs., (© 2023. The Author(s).)

Colitis is a prevalent adverse event associated with immune checkpoint inhibitor (ICI) therapy with similarities to inflammatory bowel disease. Incomplete mechanistic understanding of ICI colitis curtails evidence-based treatment. Given the often-overlooked connection between tissue architecture and mucosal immune cell function, we here applied imaging mass cytometry (IMC) to gain spatial proteomic insight in ICI colitis in comparison to ulcerative colitis (UC). Using a cell segmentation pipeline that simultaneously utilizes high-resolution nuclear imaging and high-multiplexity IMC, we show that intra-epithelial CD8 + T cells are significantly more abundant (and numerically dominant) in anti-PD-1 ± anti-CTLA-4-induced colitis compared to anti-CTLA-4-induced colitis and UC. We identified activated, cycling CD8 + tissue-resident memory T (RM) cells at the lamina propria-epithelial interface as drivers of cytotoxicity in ICI colitis and UC. Moreover, we found that combined ICI-induced colitis featured highest granzyme B levels both in tissue and serum. Together, these data reinforce CD8 + T RM cells as potentially targetable drivers of ICI colitis., Competing Interests: E.B. received research funding from Pfizer and is supported by the Alexandre Suerman stipend for MD/PhD candidates of the UMC Utrecht. Y.V. has received speaker fees from Johnson & Johnson, research funding from Galapagos, and a Public Private Partnership grant from Health Holland (#TKI2017), with TigaTx B.V. K.S. has advisory relationships with Bristol Myers Squibb, Novartis, MSD, Pierre Fabre, and AbbVie, and received honoraria from Novartis, MSD, and Roche and research funding from BMS, Philips, and TigaTx. All paid to institution. F.W. has received advisory/speaker fees from Takeda and Johnson & Johnson and research funding from BMS, Takeda, Sanofi, Pfizer, Galapagos, and Leo Pharma., (© 2023 The Author(s).)

Background: Dupilumab-associated ocular surface disease (DAOSD) is frequently reported as side effect in atopic dermatitis (AD) patients. Therefore, the aim of this study was to investigate the frequency and severity of DAOSD, ophthalmic treatment response and to learn more about the effect of dupilumab on conjunctival goblet cells (GC)., Methods: This prospective study included dupilumab-treated AD patients between February 2020 and June 2022 from the University Medical Centre Utrecht. Patients were examined by an ophthalmologist and a dermatologist before start (baseline), and after 4 and 28 weeks of dupilumab treatment. Ophthalmological examination was assessed by the Utrecht Ophthalmic Inflammatory and Allergic disease (UTOPIA) score. DAOSD was defined as an increase in UTOPIA score of ≥3 points from baseline. To quantify conjunctival GCs and to investigate the percentage of Cytokeratin 19 (CK19)-CD45-Mucin 5 AC (MUC5AC)+ cells, conjunctival impression cytology samples were analysed., Results: Ocular surface disease (OSD) was present in 91.3% (n = 63/69) patients at baseline. DAOSD was observed in 28.9% (n = 20/69) patients, in whom GC numbers remained stable and the percentage of CK19-CD45-MUC5AC+ cells decreased at onset of DAOSD compared with baseline. After 28 weeks of dupilumab treatment, DAOSD was seen in 14.5% (n = 10/69) patients. Of the 85.5% (n = 59/69) patients without DAOSD or with controlled DAOSD at Week 28, 40.7% (n = 24/59) patients received anti-inflammatory ophthalmic drugs., Conclusions: Ocular surface disease is common in moderate-to-severe AD patients before starting dupilumab. During treatment with dupilumab DAOSD severity improves with early ophthalmic treatment. The decrease in percentage of CK19-CD45-MUC5AC+ cells during dupilumab treatment suggests an impairment of the GC function due to dupilumab treatment., (© 2023 The Authors. Allergy published by European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd.)

Objectives: How the local inflammatory environment regulates epigenetic changes in the context of inflammatory arthritis remains unclear. Here we assessed the transcriptional and active enhancer profile of monocytes derived from the inflamed joints of JIA patients, a model well-suited for studying inflammatory arthritis., Methods: RNA sequencing and H3K27me3 chromatin immunoprecipitation sequencing (ChIP-seq) were used to analyse the transcriptional and epigenetic profile, respectively, of JIA synovial fluid-derived monocytes., Results: Synovial-derived monocytes display an activated phenotype, which is regulated on the epigenetic level. IFN signalling-associated genes are increased and epigenetically altered in synovial monocytes, indicating a driving role for IFN in establishing the local inflammatory phenotype. Treatment of synovial monocytes with the Janus-associated kinase (JAK) inhibitor ruxolitinib, which inhibits IFN signalling, transformed the activated enhancer landscape and reduced disease-associated gene expression, thereby inhibiting the inflammatory phenotype., Conclusion: This study provides novel insights into epigenetic regulation of inflammatory arthritis patient-derived monocytes and highlights the therapeutic potential of epigenetic modulation for the treatment of inflammatory rheumatic diseases., (© The Author(s) 2023. Published by Oxford University Press on behalf of the British Society for Rheumatology.)

Immune checkpoint inhibitors (ICIs) have changed perspectives for patients with cancer, but come with severe immune-related adverse events (irAEs). To prevent fatality or chronicity, these irAEs are often promptly treated with high-dose immunosuppressants. Until recently, evidence on the effects of irAE management on ICI efficacy has been sparse. As a result, algorithms for irAE management are mostly expert-opinion based and barely consider possible detrimental effects of immunosuppressants on ICI efficacy. However, recent growing evidence suggests that vigorous immunosuppressive management of irAEs comes with unfavourable effects on ICI efficacy and survival. With expansion of the indications of ICIs, evidence-based treatment of irAEs without hampering tumour control becomes more and more important. In this review, we discuss novel evidence from pre-clinical and clinical studies on the effects of different irAE management regimens including corticosteroids, TNF inhibition and tocilizumab on cancer control and survival. We provide recommendations for pre-clinical research, cohort studies and clinical trials that can help clinicians in tailored irAE management, minimising patients' burden while maintaining ICI efficacy., (© 2023. The Author(s).)

Atopic dermatitis (AD) is a complex and highly heterogeneous inflammatory skin disease. Given the highly heterogeneous character of AD, it is unlikely that every patient will respond equally to a particular treatment. The recent introduction of novel targeted therapies for AD has driven the need for patient stratification based on immunologic biomarkers. We have reviewed the use of different types of biomarkers as potential tools in the movement toward personalized medicine in AD, comprising different ways of endotyping patients with AD based on immunologic profiles and predictive biomarkers. The application of biomarkers will result in better characterization and stratification of patients and allow better comparison of current and new treatments. The ultimate goal will be to switch from the current generalized "one-drug-fits-all" management to more personalized "patient endotype-specific" management., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

It has been shown that innate immune responses can adopt adaptive properties such as memory. Whether T cells utilize innate immune signaling pathways to diversify their repertoire of effector functions is unknown. Gasdermin E (GSDME) is a membrane pore-forming molecule that has been shown to execute pyroptotic cell death and thus to serve as a potential cancer checkpoint. In the present study, we show that human T cells express GSDME and, surprisingly, that this expression is associated with durable viability and repurposed for the release of the alarmin interleukin (IL)-1α. This property was restricted to a subset of human helper type 17 T cells with specificity for Candida albicans and regulated by a T cell-intrinsic NLRP3 inflammasome, and its engagement of a proteolytic cascade of successive caspase-8, caspase-3 and GSDME cleavage after T cell receptor stimulation and calcium-licensed calpain maturation of the pro-IL-1α form. Our results indicate that GSDME pore formation in T cells is a mechanism of unconventional cytokine release. This finding diversifies our understanding of the functional repertoire and mechanistic equipment of T cells and has implications for antifungal immunity., (© 2023. The Author(s).)

Autoimmune inflammation is characterized by tissue infiltration and expansion of antigen-specific T cells. Although this inflammation is often limited to specific target tissues, it remains yet to be explored whether distinct affected sites are infiltrated with the same, persistent T cell clones. Here, we performed CyTOF analysis and T cell receptor (TCR) sequencing to study immune cell composition and (hyper-)expansion of circulating and joint-derived Tregs and non-Tregs in juvenile idiopathic arthritis (JIA). We studied different joints affected at the same time, as well as over the course of relapsing-remitting disease. We found that the composition and functional characteristics of immune infiltrates are strikingly similar between joints within one patient, and observed a strong overlap between dominant T cell clones, especially Treg, of which some could also be detected in circulation and persisted over the course of relapsing-remitting disease. Moreover, these T cell clones were characterized by a high degree of sequence similarity, indicating the presence of TCR clusters responding to the same antigens. These data suggest that in localized autoimmune disease, there is autoantigen-driven expansion of both Teffector and Treg clones that are highly persistent and are (re)circulating. These dominant clones might represent interesting therapeutic targets., Competing Interests: GM, NS, JL, AB, ES, PC, LL, AP, SV, Rd, SA, AP, Fv No competing interests declared, (© 2023, Mijnheer, Servaas et al.)

Neddylation has been implicated in various cellular pathways and in the pathophysiology of numerous diseases. We identified four individuals with bi-allelic variants in NAE1, which encodes the neddylation E1 enzyme. Pathogenicity was supported by decreased NAE1 abundance and overlapping clinical and cellular phenotypes. To delineate how cellular consequences of NAE1 deficiency would lead to the clinical phenotype, we focused primarily on the rarest phenotypic features, based on the assumption that these would best reflect the pathophysiology at stake. Two of the rarest features, neuronal loss and lymphopenia worsening during infections, suggest that NAE1 is required during cellular stress caused by infections to protect against cell death. In support, we found that stressing the proteasome system with MG132-requiring upregulation of neddylation to restore proteasomal function and proteasomal stress-led to increased cell death in fibroblasts of individuals with NAE1 genetic variants. Additionally, we found decreased lymphocyte counts after CD3/CD28 stimulation and decreased NF-κB translocation in individuals with NAE1 variants. The rarest phenotypic feature-delayed closure of the ischiopubic rami-correlated with significant downregulation of RUN2X and SOX9 expression in transcriptomic data of fibroblasts. Both genes are involved in the pathophysiology of ischiopubic hypoplasia. Thus, we show that NAE1 plays a major role in (skeletal) development and cellular homeostasis during stress. Our approach suggests that a focus on rare phenotypic features is able to provide significant pathophysiological insights in diseases caused by mutations in genes with pleiotropic effects., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2022 American Society of Human Genetics. All rights reserved.)

Introduction: Dendritic cells (DC) are crucial for initiating and shaping immune responses. So far, little is known about the functional specialization of human DC subsets in (local) inflammatory conditions. We profiled conventional (c)DC1, cDC2 and monocytes based on phenotype, transcriptome and function from a local inflammatory site, namely synovial fluid (SF) from patients suffering from a chronic inflammatory condition, Juvenile Idiopathic Arthritis (JIA) as well as patients with rheumatoid arthritis (RA)., Methods: Paired PB and SF samples from 32 JIA and 4 RA patients were collected for mononuclear cell isolation. Flow cytometry was done for definition of antigen presenting cell (APC) subsets. Cell sorting was done on the FACSAria II or III. RNA sequencing was done on SF APC subsets. Proliferation assays were done on co-cultures after CD3 magnetic activated cell sorting (MACS). APC Toll-like receptor (TLR) stimulation was done using Pam3CSK4, Poly(I:C), LPS, CpG-A and R848. Cytokine production was measured by Luminex., Results: cDC1, a relatively small DC subset in blood, are strongly enriched in SF, and showed a quiescent immune signature without a clear inflammatory profile, low expression of pathogen recognition receptors (PRRs), chemokine and cytokine receptors, and poor induction of T cell proliferation and cytokine production, but selective production of IFNλ upon polyinosinic:polycytidylic acid exposure. In stark contrast, cDC2 and monocytes from the same environment, showed a pro-inflammatory transcriptional profile, high levels of (spontaneous) pro-inflammatory cytokine production, and strong induction of T cell proliferation and cytokine production, including IL-17. Although the cDC2 and monocytes showed an overlapping transcriptional core profile, there were clear differences in the transcriptional landscape and functional features, indicating that these cell types retain their lineage identity in chronic inflammatory conditions., Discussion: Our findings suggest that at the site of inflammation, there is specific functional programming of human DCs, especially cDC2. In contrast, the enriched cDC1 remain relatively quiescent and seemingly unchanged under inflammatory conditions, pointing to a potentially more regulatory role., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Boltjes, Samat, Plantinga, Mokry, Castelijns, Swart, Vastert, Creyghton, Nierkens, van Loosdregt and van Wijk.)

Background: The patho-mechanism of ocular surface disease (OSD) in dupilumab-treated atopic dermatitis (AD) patients remains unclear. The aim of this study is to measure dupilumab levels in tear fluid and serum, and relate these findings to the severity of OSD during dupilumab treatment in AD patients., Methods: This prospective study included dupilumab-treated moderate-to-severe AD patients who were seen by a dermatologist and an ophthalmologist before the start of dupilumab (baseline), and after 4 and 28 weeks of dupilumab treatment. Dupilumab levels in tear fluid and serum were measured by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Additionally, a pilot study was conducted to measure dupilumab on conjunctival epithelial cells using flow cytometry and LC-MS/MS., Results: At baseline, 89.6% (n = 43/48) of the patients had OSD, with 50.0% having moderate-to-severe OSD. After 28 weeks of dupilumab treatment, the median dupilumab tear fluid levels were 0.55 mg/L (IQR 0.35-1.31) and 0.29 mg/L (IQR 0.16-0.60) in patients with moderate-to-severe OSD and patients with no or mild OSD, respectively (p = 0.02). Dupilumab levels could be detected on conjunctival epithelial cells of 5 AD patients treated with dupilumab for 4 weeks., Conclusion: Patients with moderate-to-severe OSD had higher dupilumab tear fluid levels compared to patients with no or mild OSD, indicating that dupilumab reaches the ocular surface. Dupilumab was also detected in conjunctival cell suspensions and was found to directly bind CD45-conjunctival epithelial cells. This suggests that AD-induced changes of the conjunctival epithelium may play a role in the development of OSD as well as increased local drug availability., (© 2023 The Authors. Clinical and Translational Allergy published by John Wiley & Sons Ltd on behalf of European Academy of Allergy and Clinical Immunology.)

Importance: The registered dose of dupilumab for adult patients with atopic dermatitis (AD) is 300 mg every other week. At present, it is unknown whether serum dupilumab levels are associated with treatment response or adverse effects., Objectives: To evaluate serum dupilumab levels at 16 weeks of treatment and to explore the association of serum dupilumab levels with treatment response and adverse effects in patients with AD., Design, Setting, and Participants: This clinical, prospective, observational cohort study used data from the prospective BioDay Registry including adult patients with AD who started dupilumab treatment and for whom a serum sample was available at 16 weeks of treatment. All patients were treated according to the BioDay protocol in the University Medical Center Utrecht in the Netherlands. Patients received a loading dose of dupilumab 600 mg subcutaneously, followed by 300 mg every other week. Patients who had a dose adjustment or discontinued treatment before 16 weeks of treatment were excluded. Data analyses were performed from January to June 2022., Main Outcomes and Measures: Disease severity of AD was assessed at baseline and at weeks 16 and 52 using the Eczema Area and Severity Index (EASI). Treatment response was defined as the percent reduction in EASI score vs the baseline score (eg, EASI 90 indicated a 90% reduction) and as an absolute EASI cutoff score of 7 or lower (controlled AD). Adverse effects were recorded during the first year. At 16 weeks, dupilumab serum levels and treatment responses were measured and analyzed. Multivariate logistic regression modeling was used to determine the prediction of response (EASI 90; EASI ≤7) and adverse effects at 52 weeks, with serum dupilumab levels at 16 weeks in the presence of the covariates age and sex., Results: Among the total of 295 patients with AD (mean [SD] age, 41.5 [15.9] years; 170 [57.6%] men), the median (IQR [range]) drug level was 86.6 μg/mL (64.6-110.0 μg/mL [10.1-382.0 μg/mL]) at 16 weeks of treatment. No significant differences were found in serum dupilumab levels between responder statuses (EASI, <50, 50, 75, or 90) at week 16. Multivariate logistic regression analysis showed nonsignificant odds ratios (ORs) for serum dupilumab levels at 16 weeks regarding prediction of long-term response (EASI ≥90: OR, 0.96 [95% CI, 0.90-1.04; P = .34] and EASI ≤7: OR, 1.03 [95% CI, 0.93-1.14; P = .55]) and adverse effects (OR, 1.01 [95% CI, 0.95-1.07; P = .83])., Conclusion and Relevance: This prospective clinical cohort study found a broad range of serum dupilumab levels at 16 weeks of treatment and no association with treatment response and adverse effects during first year of treatment. Response may be dependent on target availability of the interleukin-4 receptor subunit α, with an interpatient variability producing heterogeneity in response.

Background: Dupilumab has proven to be an effective and safe treatment for atopic dermatitis (AD) in pediatric patients in clinical trials. However, few daily practice studies are available. The aim of this study is to evaluate the effect of 28 weeks dupilumab treatment on effectiveness, safety, and serum biomarkers in pediatric patients with moderate-to-severe AD in daily practice., Methods: Patients visited the outpatient clinic at baseline, 4, 16, and 28 weeks of treatment. Disease severity was assessed by the Eczema Area and Severity Index (EASI), Investigator Global Assessment (IGA), Numeric Rating Scale (NRS)-pruritus and -pain, and the Patient-Oriented Eczema Measure (POEM). Side effects were evaluated. Nineteen severity-associated serum biomarkers were measured. Predicted-EASI (p-EASI) was calculated., Results: Sixty-one patients were included. Respectively 75.4%, 49.2%, and 24.6% reached EASI-50, EASI-75, and EASI-90 and 36.1% achieved an IGA-score (almost) clear. Improvement of ≥4 points on POEM, NRS-pruritus, and NRS-pain was reached by 84.7%, 45.3%, and 77.4%, respectively. Most reported side effects were conjunctivitis (n = 10) and headache (n = 4). Biomarkers TARC, PARC, periostin, sIL-2Ra, and eotaxin-3 significantly decreased during treatment. The p-EASI showed a significant correlation with disease severity., Conclusion: Dupilumab treatment significantly improved disease severity and disease-associated symptoms and decreased severity-associated serum biomarkers in pediatric AD patients in daily practice., (© 2022 The Authors. Pediatric Allergy and Immunology published by European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd.)

Background: At present, no real-world studies are available on different dupilumab dosing regimens in controlled atopic dermatitis (AD). The aim of this study was to clinically evaluate a patient-centered dupilumab dosing regimen in patients with controlled AD and to relate this to serum drug levels and serum biomarkers., Methods: Ninety adult AD patients from the prospective BioDay registry were included based on their dupilumab administration interval according to a predefined patient-centered dosing regimen. Group A (n = 30) did not fulfill the criteria for interval prolongation and continued using the standard dupilumab dosage (300 mg/2 weeks), group B (n = 30) prolonged dupilumab interval with 50% (300 mg/4 weeks), and group C (n = 30) prolonged dupilumab interval with 66%-75% (300 mg/6-8 weeks). AD severity score, patient-reported outcomes, serum dupilumab levels, and serum biomarkers were analyzed over time., Results: Disease severity scores did not significantly change over time during the tapering period in any of the groups. In groups B and C, the Numeric Rating Scale (NRS)-pruritus temporarily significantly increased after interval prolongation but remained low (median NRS-pruritus≤4). Median dupilumab levels remained stable in group A (standard dosage), but significantly decreased in groups B and C (24.1 mg/L (IQR = 17.1-45.6); 12.5 mg/L (IQR = 1.7-22.3)) compared with the levels during the standard dosage (88.2 mg/L [IQR = 67.1-123.0, p < .001]). Disease severity biomarker levels (CCL17/CCL18) remained low in all study groups during the whole observation period., Conclusions: This study showed that dose reduction was successful in a subgroup of patients with controlled AD by using a patient-centered dosing regimen. These patients showed stable low disease activity and low severity biomarkers over time., (© 2022 The Authors. Allergy published by European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd.)

Objective: Tregs are crucial for immune regulation, and environment-driven adaptation of effector (e)Tregs is essential for local functioning. However, the extent of human Treg heterogeneity in inflammatory settings is unclear., Methods: We combined single-cell RNA- and TCR-sequencing on Tregs derived from three to six patients with juvenile idiopathic arthritis (JIA) to investigate the functional heterogeneity of human synovial fluid (SF)-derived Tregs from inflamed joints. Confirmation and suppressive function of the identified Treg clusters was assessed by flow cytometry., Results: Four Treg clusters were identified; incoming, activated eTregs with either a dominant suppressive or cytotoxic profile, and GPR56 + CD161 + CXCL13 + Tregs. Pseudotime analysis showed differentiation towards either classical eTreg profiles or GPR56 + CD161 + CXCL13 + Tregs supported by TCR data. Despite its most differentiated phenotype, GPR56 + CD161 + CXCL13 + Tregs were shown to be suppressive. Furthermore, BATF was identified as an overarching eTreg regulator, with the novel Treg-associated regulon BHLHE40 driving differentiation towards GPR56 + CD161 + CXCL13 + Tregs, and JAZF1 towards classical eTregs., Conclusion: Our study reveals a heterogeneous population of Tregs at the site of inflammation in JIA. SF Treg differentiate to a classical eTreg profile with a more dominant suppressive or cytotoxic profile that share a similar TCR repertoire, or towards GPR56 + CD161 + CXCL13 + Tregs with a more distinct TCR repertoire. Genes characterising GPR56 + CD161 + CXCL13 + Tregs were also mirrored in other T-cell subsets in both the tumor and the autoimmune setting. Finally, the identified key regulators driving SF Treg adaptation may be interesting targets for autoimmunity or tumor interventions., Competing Interests: The authors declare no conflict of interest., (© 2022 The Authors. Clinical & Translational Immunology published by John Wiley & Sons Australia, Ltd on behalf of Australian and New Zealand Society for Immunology, Inc.)

Tissue-resident memory T cells (TRM) are suspected drivers of chronic inflammation, but their induction remains unclear. Since endothelial cells (EC) are obligate interaction partners for T cells trafficking into inflamed tissues, they may play a role in TRM development. Here, we used an in vitro co-culture system of human cytokine-activated EC and FACS-sorted T cells to study the effect of EC on T(RM) cell differentiation. T cell phenotypes were assessed by flow cytometry, including proliferation measured by CellTrace Violet dilution assay. Soluble mediators were analyzed by multiplex immunoassay. Co-culture of T cells with cytokine-activated, but not resting EC induced CD69 expression without activation (CD25, Ki67) or proliferation. The dynamic of CD69 expression induced by EC was distinct from that induced by TCR triggering, with rapid induction and stable expression over 7 days. CD69 induction by activated EC was higher in memory than naive T cells, and most pronounced in CD8 + effector memory T cells. Early CD69 induction was mostly mediated by IL-15, whereas later effects were also mediated by interactions with ICAM-1 and/or VCAM-1. CD69 + T cells displayed a phenotype associated with tissue-residency, with increased CD49a, CD103, CXCR6, PD-1 and CD57 expression, and decreased CD62L and S1PR1. EC-induced CD69 + T cells were poised for high production of pro-inflammatory cytokines and showed increased expression of T-helper 1 transcription factor T-bet. Our findings demonstrate that activated EC can induce functional specialization in T cells with sustained CD69 expression, increased cytokine response and a phenotypic profile reminiscent of TRM. Interaction with activated EC during transmigration into (inflamed) tissues thus contributes to TRM-residency priming., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Wienke, Veldkamp, Struijf, Yousef Yengej, van der Wal, van Royen-Kerkhof and van Wijk.)

Objective: JDM is a rare chronic immune-mediated inflammatory disease with a predominant role for type I IFN responses. We aimed to determine the potential of Siglec-1 expression on monocytes as a novel IFN-inducible biomarker for disease activity monitoring and prediction of treatment response in patients with JDM., Methods: Siglec-1 was measured by flow cytometry on circulating monocytes of 21 newly diagnosed JDM patients before start of treatment and, for 10 of these, also during follow-up. The expression levels of five type I IFN-stimulated genes, MX1, IFI44, IFI44L, LY6E and IFIT3, were measured by RT-qPCR to determine the IFN signature and calculate an IFN score. IFN-inducible plasma proteins CXCL10 and galectin-9 were measured by multiplex immunoassay., Results: Siglec-1 and IFN score were increased in JDM patients compared with controls and correlated with clinical disease activity. Stratification of patients by Siglec-1 expression at diagnosis identified those with high Siglec-1 expression as having a higher risk of requiring treatment intensification within the first 3 months after diagnosis (55% vs 0% of patients, P = 0.01). Siglec-1 expression strongly correlated with plasma levels of previously validated biomarkers CXCL10 (rs = 0.81, P < 0.0001) and galectin-9 (rs = 0.83, P < 0.0001), and was superior to the IFN score in predicting treatment response (area under the curve 0.87 vs 0.53, P = 0.01)., Conclusion: Siglec-1 on monocytes is a novel IFN-inducible biomarker in JDM that correlates with clinical disease activity and identifies patients at risk for a suboptimal treatment response. Further studies are required to validate these findings and their clinical potential., (© The Author(s) 2021. Published by Oxford University Press on behalf of the British Society for Rheumatology.)

T lymphocytes (T cells) are major players of the adaptive immune response. Naive T cells are primed in the presence of cytokines, leading to polarization into distinct T-cell subsets with specific functions. These subsets are classified based on their T-cell receptor profile, expression of transcription factors, surface cytokine and chemokine receptors, and their cytokine production, which together determine their specific function. This review provides an overview of the various T-cell subsets and their function in several inflammatory skin disorders ranging from allergic inflammation to skin tumors. Moreover, we highlight similarities of T-cell responses across different skin disorders, demonstrating the presence of similar and opposing functions for the different T-cell subsets. Finally, we discuss the effects of currently available and promising therapeutic approaches to harness T cells in inflammatory skin diseases for which efficacy next to unwanted side effects provide new insights into the pathophysiology of skin disorders., (© 2021 European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd.)