Tregs are impaired in human systemic lupus erythematosus (SLE) and contribute to effector T cell activation. However, the mechanisms responsible for the Treg deficiency in SLE remain unclear. We hypothesized that the OX40L/OX40 axis is implicated in Treg and regulatory follicular helper T (Tfr) cell dysfunction in human SLE. OX40L/OX40 axis engagement on Tregs and Tfr cells not only specifically impaired their ability to regulate effector T cell proliferation, but also their ability to suppress T follicular helper (Tfh) cell–dependent B cell activation and immunoglobulin secretion. Antigen-presenting cells from patients with active SLE mediated Treg dysfunction in an OX40L-dependent manner, and OX40L-expressing cells colocalized with Foxp3+ cells in active SLE skin lesions. Engagement of the OX40L/OX40 axis resulted in Foxp3 downregulation in Tregs, and expression in SLE Tregs correlated with the proportion of circulating OX40L-expressing myeloid DCs. These data support that OX40L/OX40 signals are implicated in Treg dysfunction in human SLE. Thus, blocking the OX40L/OX40 axis appears to be a promising therapeutic strategy.
Clément Jacquemin, Jean-François Augusto, Marc Scherlinger, Noémie Gensous, Edouard Forcade, Isabelle Douchet, Emeline Levionnois, Christophe Richez, Estibaliz Lazaro, Pierre Duffau, Marie-Elise Truchetet, Julien Seneschal, Lionel Couzi, Jean-Luc Pellegrin, Jean-François Viallard, Thierry Schaeverbeke, Virginia Pascual, Cécile Contin-Bordes, Patrick Blanco
CD141+ DC are implicated in antiviral and antitumor immunity. However, mechanistic studies in autoimmune disease are limited. This is the first study to our knowledge examining CD141+ DC in autoimmune disease, specifically inflammatory arthritis (IA). We identified significant enrichment of CD141+ DC in the inflamed synovial joint, which were transcriptionally distinct from IA and healthy control (HC) blood CD141+ DC and significantly more activated, and they exhibited increased responsiveness to TLR3. Synovial CD141+ DC represent a bone fide CD141+ DC population that is distinct from CD1c+ DC. Synovial CD141+ DC induced higher levels of CD4+ and CD8+ T cell activation compared with their peripheral blood counterparts, as made evident by expression of IFN-γ, TNF-α, and granulocyte-macrophage CSF (GMCSF). Autologous synovial CD141+ DC cocultures also induce higher levels of these cytokines, further highlighting their contribution to synovial inflammation. Synovial CD141+ DC–T cell interactions had the ability to further activate synovial fibroblasts, inducing adhesive and invasive pathogenic mechanisms. Furthermore, we identify a mechanism in which synovial CD141+ DC are activated, via ligation of the hypoxia-inducible immune-amplification receptor TREM-1, which increased synovial CD141+ DC activation, migratory capacity, and proinflammatory cytokines. Thus, synovial CD141+ DC display unique mechanistic and transcriptomic signatures, which are distinguishable from blood CD141+ DC and can contribute to synovial joint inflammation.
Mary Canavan, Alice M. Walsh, Vipul Bhargava, Sarah M. Wade, Trudy McGarry, Viviana Marzaioli, Barry Moran, Monika Biniecka, Hannah Convery, Siobhan Wade, Carl Orr, Ronan Mullan, Jean M. Fletcher, Sunil Nagpal, Douglas J. Veale, Ursula Fearon
The peptidylarginine deiminases PAD2 and PAD4 are implicated in the pathogenesis of several autoimmune diseases. PAD4 may be pathogenic in systemic lupus erythematosus (SLE) through its role in neutrophil extracellular trap (NET) formation that promotes autoantigen externalization, immune dysregulation, and organ damage. The role of this enzyme in mouse models of autoimmunity remains unclear, as pan-PAD chemical inhibitors improve clinical phenotype, whereas PAD4-KO models have given conflicting results. The role of PAD2 in SLE has not been investigated. The differential roles of PAD2 and PAD4 in TLR-7–dependent lupus autoimmunity were examined. Padi4–/– displayed decreased autoantibodies, type I IFN responses, immune cell activation, vascular dysfunction, and NET immunogenicity. Padi2–/– mice showed abrogation of Th subset polarization, with some disease manifestations reduced compared with WT but to a lesser extent than Padi4–/– mice. RNA sequencing analysis revealed distinct modulation of immune-related pathways in PAD-KO lymphoid organs. Human T cells express both PADs and, when exposed to either PAD2 or PAD4 inhibitors, displayed abrogation of Th1 polarization. These results suggest that targeting PAD2 and/or PAD4 activity modulates dysregulated TLR-7–dependent immune responses in lupus through differential effects of innate and adaptive immunity. Compounds that target PADs may have potential therapeutic roles in T cell–mediated diseases.
Yudong Liu, Yaíma L. Lightfoot, Nickie Seto, Carmelo Carmona-Rivera, Erica Moore, Rishi Goel, Liam O’Neil, Pragnesh Mistry, Victoria Hoffmann, Santanu Mondal, Padmavathy Nandha Premnath, Katherine Gribbons, Stefania Dell’Orso, Kan Jiang, Paul R. Thompson, Hong-Wei Sun, Scott A. Coonrod, Mariana J. Kaplan
We describe a protective effect on autoimmune diabetes and reduced destructive insulitis in NOD.scid recipients following splenocyte injections from diabetic NOD donors and sorted CD19+ cells compared with NOD.scid recipients receiving splenocytes alone. This protective effect was age specific (only CD19+ cells from young NOD donors exerted this effect; P < 0.001). We found that the CD19+IgM+ cell is the primary subpopulation of B cells that delayed transfer of diabetes mediated by diabetogenic T cells from NOD mice (P = 0.002). Removal of IgM+ cells from the CD19+ pool did not result in protection. Notably, protection conferred by CD19+IgM+ cotransfers were not dependent on the presence of Tregs, as their depletion did not affect their ability to delay onset of diabetes. Blockade of IL-10 with neutralizing antibodies at the time of CD19+ cell cotransfers also abrogated the therapeutic effect, suggesting that IL-10 secretion was an important component of protection. These results were strengthened by ex vivo incubation of CD19+ cells with IL-5, resulting in enhanced proliferation and IL-10 production and equivalently delayed diabetes progression (P = 0.0005). The potential to expand CD19+IgM+ cells, especially in response to IL-5 stimulation or by pharmacologic agents, may be a new therapeutic option for type 1 diabetes.
Andrew D. Vonberg, Maria Acevedo-Calado, Aaron R. Cox, Susan L. Pietropaolo, Roberto Gianani, Steven K. Lundy, Massimo Pietropaolo
Juvenile dermatomyositis (JDM) is a debilitating pediatric autoimmune disease manifesting with characteristic rash and muscle weakness. To delineate signaling abnormalities in JDM, mass cytometry was performed with PBMCs from treatment-naive JDM patients and controls. NK cell percentages were lower while frequencies of naive B cells and naive CD4+ T cells were higher in JDM patients than in controls. These cell frequency differences were attenuated with cessation of active disease. A large number of signaling differences were identified in treatment-naive JDM patients compared with controls. Classification models incorporating feature selection demonstrated that differences in phospholipase Cγ2 (PLCγ2) phosphorylation comprised 10 of 12 features (i.e., phosphoprotein in a specific immune cell subset) distinguishing the 2 groups. Because NK cells represented 5 of these 12 features, further studies focused on the PLCγ2 pathway in NK cells, which is responsible for stimulating calcium flux and cytotoxic granule movement. No differences were detected in upstream signaling or total PLCγ2 protein levels. Hypophosphorylation of PLCγ2 and downstream mitogen-activated protein kinase-activated protein kinase 2 were partially attenuated with cessation of active disease. PLCγ2 hypophosphorylation in treatment-naive JDM patients resulted in decreased calcium flux. The identification of dysregulation of PLCγ2 phosphorylation and decreased calcium flux in NK cells provides potential mechanistic insight into JDM pathogenesis.
Allison A. Throm, Joshua B. Alinger, Jeanette T. Pingel, Allyssa L. Daugherty, Lauren M. Pachman, Anthony R. French
BACKGROUND. Type 1 diabetes (T1D) results from loss of immune regulation, leading to the development of autoimmunity to pancreatic β cells, involving autoreactive T effector cells (Teffs). Tregs, which prevent autoimmunity, require IL-2 for maintenance of immunosuppressive functions. Using a response-adaptive design, we aimed to determine the optimal regimen of aldesleukin (recombinant human IL-2) to physiologically enhance Tregs while limiting expansion of Teffs. METHODS. DILfrequency is a nonrandomized, open-label, response-adaptive study of participants, aged 18–70 years, with T1D. The initial learning phase allocated 12 participants to 6 different predefined regimens. Then, 3 cohorts of 8 participants were sequentially allocated dose frequencies, based on repeated interim analyses of all accumulated trial data. The coprimary endpoints were percentage change in Tregs and Teffs and CD25 (α subunit of the IL-2 receptor) expression by Tregs, from baseline to steady state. RESULTS. Thirty-eight participants were enrolled, with thirty-six completing treatment. The optimal regimen to maintain a steady-state increase in Tregs of 30% and CD25 expression of 25% without Teff expansion is 0.26 × 106 IU/m2 (95% CI –0.007 to 0.485) every 3 days. Tregs and CD25 were dose-frequency responsive, Teffs were not. The commonest adverse event was injection site reaction (464 of 694 events). CONCLUSIONS. Using a response-adaptive design, aldesleukin treatment can be optimized. Our methodology can generally be employed to immediately access proof of mechanism, thereby leading to more efficient and safe drug development. TRIAL REGISTRATION. International Standard Randomised Controlled Trial Number Register, ISRCTN40319192; ClinicalTrials.gov, NCT02265809. FUNDING. Sir Jules Thorn Trust, the Swiss National Science Foundation, Wellcome, JDRF, and NIHR Cambridge Biomedical Research Centre.
Eleonora Seelig, James Howlett, Linsey Porter, Lucy Truman, James Heywood, Jane Kennet, Emma L. Arbon, Katerina Anselmiova, Neil M. Walker, Ravinder Atkar, Marcin L. Pekalski, Ed Rytina, Mark Evans, Linda S. Wicker, John A. Todd, Adrian P. Mander, Simon Bond, Frank Waldron-Lynch
Alopecia areata (AA) is an autoimmune disease in which cytotoxic T cells specifically target growing hair follicles. We used high-throughput TCR sequencing in the C3H/HeJ mouse model of AA and in human AA patients to gain insight into pathogenic T cell populations and their dynamics, which revealed clonal CD8+ T cell expansions in lesional skin. In the C3H/HeJ model, we observed interindividual sharing of TCRβ chain protein sequences, which strongly supports a model of antigenic drive in AA. The overlap between the lesional TCR repertoire and a population of CD8+NKG2D+ T cells in skin-draining lymph nodes identified this subset as pathogenic effectors. In AA patients, treatment with the oral JAK inhibitor tofacitinib resulted in a decrease in clonally expanded CD8+ T cells in the scalp but also revealed that many expanded lesional T cell clones do not completely disappear from either skin or blood during treatment with tofacitinib, which may explain in part the relapse of disease after stopping treatment.
Annemieke de Jong, Ali Jabbari, Zhenpeng Dai, Luzhou Xing, Dustin Lee, Mei Mei Li, Madeleine Duvic, Maria Hordinsky, David A. Norris, Vera Price, Julian Mackay-Wiggan, Raphael Clynes, Angela M. Christiano
IFN-inducible protein 16 (IFI16) is an innate immune sensor that forms filamentous oligomers when activated by double-stranded DNA (dsDNA). Anti-IFI16 autoantibodies occur in patients with Sjögren’s syndrome (SS) and associate with severe phenotypic features. We undertook this study to determine whether the structural and functional properties of IFI16 play a role in its status as an SS autoantigen. IFI16 immunostaining in labial salivary glands (LSGs) yielded striking evidence of filamentous IFI16 structures in the cytoplasm of ductal epithelial cells, representing the first microscopic description of IFI16 oligomerization in human tissues, to our knowledge. Transfection of cultured epithelial cells with dsDNA triggered the formation of cytoplasmic IFI16 filaments with similar morphology to those observed in LSGs. We found that a majority of SS anti-IFI16 autoantibodies immunoprecipitate IFI16 more effectively in the oligomeric dsDNA-bound state. Epitopes in the C-terminus of IFI16 are accessible to antibodies in the DNA-bound oligomer and are preferentially targeted by SS sera. Furthermore, cytotoxic lymphocyte granule pathways (highly enriched in the SS gland) induce striking release of IFI16•dsDNA complexes from cultured cells. Our studies reveal that IFI16 is present in a filamentous state in the target tissue of SS and suggest that this property of DNA-induced filament formation contributes to its status as an autoantigen in SS. These studies highlight the role that tissue-specific modifications and immune effector pathways might play in the selection of autoantigens in rheumatic diseases.
Brendan Antiochos, Mariusz Matyszewski, Jungsan Sohn, Livia Casciola-Rosen, Antony Rosen
BACKGROUND. Neutrophils and their inflammatory mediators are key pathogenic components in multiple autoimmune diseases, while their role in human type 1 diabetes (T1D), a disease that progresses sequentially through identifiable stages prior to the clinical onset, is not well understood. We previously reported that the number of circulating neutrophils is reduced in patients with T1D and in presymptomatic at-risk subjects. The aim of the present work was to identify possible changes in circulating and pancreas-residing neutrophils throughout the disease course to better elucidate neutrophil involvement in human T1D. METHODS. Data collected from 389 subjects at risk of developing T1D, and enrolled in 4 distinct studies performed by TrialNet, were analyzed with comprehensive statistical approaches to determine whether the number of circulating neutrophils correlates with pancreas function. To obtain a broad analysis of pancreas-infiltrating neutrophils throughout all disease stages, pancreas sections collected worldwide from 4 different cohorts (i.e., nPOD, DiViD, Siena, and Exeter) were analyzed by immunohistochemistry and immunofluorescence. Finally, circulating neutrophils were purified from unrelated nondiabetic subjects and donors at various T1D stages and their transcriptomic signature was determined by RNA sequencing. RESULTS. Here, we show that the decline in β cell function is greatest in individuals with the lowest peripheral neutrophil numbers. Neutrophils infiltrate the pancreas prior to the onset of symptoms and they continue to do so as the disease progresses. Of interest, a fraction of these pancreas-infiltrating neutrophils also extrudes neutrophil extracellular traps (NETs), suggesting a tissue-specific pathogenic role. Whole-transcriptome analysis of purified blood neutrophils revealed a unique molecular signature that is distinguished by an overabundance of IFN-associated genes; despite being healthy, said signature is already present in T1D-autoantibody-negative at-risk subjects. CONCLUSIONS. These results reveal an unexpected abnormality in neutrophil disposition both in the circulation and in the pancreas of presymptomatic and symptomatic T1D subjects, implying that targeting neutrophils might represent a previously unrecognized therapeutic modality. FUNDING. Juvenile Diabetes Research Foundation (JDRF), NIH, Diabetes UK.
Federica Vecchio, Nicola Lo Buono, Angela Stabilini, Laura Nigi, Matthew J. Dufort, Susan Geyer, Paola Maria Rancoita, Federica Cugnata, Alessandra Mandelli, Andrea Valle, Pia Leete, Francesca Mancarella, Peter S. Linsley, Lars Krogvold, Kevan C. Herold, Helena Elding Larsson, Sarah J. Richardson, Noel G. Morgan, Knut Dahl-Jørgensen, Guido Sebastiani, Francesco Dotta, Emanuele Bosi, the DRI_Biorepository Group, the Type 1 Diabetes TrialNet Study Group, Manuela Battaglia
Belimumab has therapeutic benefit in active systemic lupus erythematosus (SLE), especially in patients with high-titer anti-dsDNA antibodies. We asked whether the profound B cell loss in belimumab-treated SLE patients is accompanied by shifts in the immunoglobulin repertoire. We enrolled 15 patients who had been continuously treated with belimumab for more than 7 years, 17 matched controls, and 5 patients who were studied before and after drug initiation. VH genes of sort-purified mature B cells and plasmablasts were subjected to next-generation sequencing. We found that B cell–activating factor (BAFF) regulates the transitional B cell checkpoint, with conservation of transitional 1 (T1) cells and approximately 90% loss of T3 and naive B cells after chronic belimumab treatment. Class-switched memory B cells, B1 B cells, and plasmablasts were also substantially depleted. Next-generation sequencing revealed no redistribution of VH, DH, or JH family usage and no effect of belimumab on representation of the autoreactive VH4-34 gene or CDR3 composition in unmutated IgM sequences, suggesting a minimal effect on selection of the naive B cell repertoire. Interestingly, a significantly greater loss of VH4-34 was observed among mutated IgM and plasmablast sequences in chronic belimumab–treated subjects than in controls, suggesting that belimumab promotes negative selection of activated autoreactive B cells.
Weiqing Huang, Tam D. Quach, Cosmin Dascalu, Zheng Liu, Tungming Leung, Miranda Byrne-Steele, Wenjing Pan, Qunying Yang, Jian Han, Martin Lesser, Thomas L. Rothstein, Richard Furie, Meggan Mackay, Cynthia Aranow, Anne Davidson
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