Essential role of TNF receptor superfamily 25 (TNFRSF25) in the development of allergic lung inflammation

Targeting TL1A and DR3: the new frontier of anti-cytokine therapy in IBD

TNF-like cytokine 1A (TL1A) and its functional receptor, death-domain receptor 3 (DR3), are members of the TNF and TNFR superfamilies, respectively, with recognised roles in regulating innate and adaptive immune responses; additional existence of a decoy receptor, DcR3, indicates a tightly regulated cytokine system. The significance of TL1A:DR3 signalling in the pathogenesis of inflammatory bowel disease (IBD) is supported by several converging lines of evidence. Herein, we aim to provide a comprehensive understanding of what is currently known regarding the TL1A/DR3 system in the context of IBD. TL1A and DR3 are expressed by cellular subsets with important roles for the initiation and maintenance of intestinal inflammation, serving as potent universal costimulators of effector immune responses, indicating their participation in the pathogenesis of IBD. Recent evidence also supports a homoeostatic role for TL1A:DR3 via regulation of Tregs and innate lymphoid cells. TL1A and DR3 are also expressed by stromal cells and may contribute to inflammation-induced or inflammation-independent intestinal fibrogenesis. Finally, discovery of genetic polymorphisms with functional consequences may allow for patient stratification, including differential responses to TL1A-targeted therapeutics. In conclusion, TL1A:DR3 signalling plays a central and multifaceted role in the immunological pathways that underlie intestinal inflammation, such as that observed in IBD. Such evidence provides the foundation for developing pharmaceutical approaches targeting this ligand-receptor pair in IBD.

Targeting TNFRSF25 by agonistic antibodies and multimeric TL1A proteins co-stimulated CD8+ T cells and inhibited tumor growth

BACKGROUND

Tumor necrosis factor receptor superfamily 25 (TNFRSF25) is a T-cell co-stimulatory receptor. Expression of its ligand, TNF-like cytokine 1A (TL1A), on mouse tumor cells has been shown to promote tumor regression. This study aimed to develop TNFRSF25 agonists (both antibodies (Abs) and TL1A proteins) and to investigate their potential antitumor effects.

METHODS

Anti-mouse TNFRSF25 (mTNFRSF25) Abs and multimeric TL1A proteins were generated as TNFRSF25 agonists. Their agonism was assessed in luciferase reporter and T-cell co-stimulation assays, and their antitumor effects were evaluated in syngeneic mouse tumor models. TNFRSF25 expression within the tumor microenvironment and the effects of an anti-mTNFRSF25 agonistic Ab on tumor-infiltrating T cells were evaluated by flow cytometry. Cell depletion assays were used to identify the immune cell types that contribute to the antitumor effect of the anti-mTNFRSF25 Ab. The Fc gamma receptor (FcγR) dependence of TNFRSF25 agonists was assessed in an in vivo T-cell expansion model and a mouse tumor model using Fc variants and FcγR-deficient mice.

RESULTS

TNFRSF25 agonists exhibited antitumor effects in syngeneic mouse tumor models without causing observed side effects. We identified an anti-mTNFRSF25 agonistic Ab, 1A6-m1, which exhibited greater antitumor activity than a higher affinity anti-TNFRSF25 Ab which engages an overlapping epitope with 1A6-m1. 1A6-m1 activated CD8+ T cells and antigen-specific T cells, leading to tumor regression; it also induced long-term antitumor immune memory. Although activating TNFRSF25 by 1A6-m1 expanded splenic regulatory T (Treg) cells, it did not influence intratumoral Treg cells. Moreover, 1A6-m1's antitumor effects required the engagement of both inhibitory FcγRIIB and activating FcγRIII. Replacing 1A6-m1's CH1-hinge region with that of human IgG2 (h2) conferred enhanced antitumor effects. Finally, we also generated multimeric human and mouse TL1A fusion proteins as TNFRSF25 agonists, and they co-stimulated CD8+ T cells and reduced tumor growth, even in the absence of Fc-FcγR interactions.

CONCLUSION

Our data demonstrates the potential of activating TNFRSF25 by Abs and multimeric TL1A proteins for cancer immunotherapy and provides insights into their development astherapeutics.

TL1A priming induces a multi-cytokine Th9 cell phenotype that promotes robust allergic inflammation in murine models of asthma

Multi-cytokine-producing Th9 cells secrete IL-9 and type 2 cytokines and mediate mouse and human allergic inflammation. However, the cytokines that promote a multi-cytokine secreting phenotype have not been defined. Tumor necrosis factor superfamily member TL1A signals through its receptor DR3 to increase IL-9. Here we demonstrate that TL1A increases expression of IL-9 and IL-13 co-expressing cells in murine Th9 cell cultures, inducing a multi-cytokine phenotype. Mechanistically, this is linked to histone modifications allowing for increased accessibility at the Il9 and Il13 loci. We further show that TL1A alters the transcription factor network underlying expression of IL-9 and IL-13 in Th9 cells and increases binding of transcription factors to Il9 and Il13 loci. TL1A-priming enhances the pathogenicity of Th9 cells in murine models of allergic airway disease through the increased expression of IL-9 and IL-13. Lastly, in both chronic and memory-recall models of allergic airway disease, blockade of TL1A signaling decreases the multi-cytokine Th9 cell population and attenuates the allergic phenotype. Taken together, these data demonstrate that TL1A promotes the development of multi-cytokine Th9 cells that drive allergic airway diseases and that targeting pathogenic T helper cell-promoting cytokines could be an effective approach for modifying disease.

Necroptosis plays a role in TL1A-induced airway inflammation and barrier damage in asthma

BACKGROUND

Airway epithelial cell (AEC) necroptosis contributes to airway allergic inflammation and asthma exacerbation. Targeting the tumor necrosis factor-like ligand 1 A (TL1A)/death receptor 3 (DR3) axis has a therapeutic effect on asthmatic airway inflammation. The role of TL1A in mediating necroptosis of AECs challenged with ovalbumin (OVA) and its contribution to airway inflammation remains unclear.

METHODS

We evaluated the expression of the receptor-interacting serine/threonine-protein kinase 3(RIPK3) and the mixed lineage kinase domain-like protein (MLKL) in human serum and lung, and histologically verified the level of MLKL phosphorylation in lung tissue from asthmatics and OVA-induced mice. Next, using MLKL knockout mice and the RIPK3 inhibitor GSK872, we investigated the effects of TL1A on airway inflammation and airway barrier function through the activation of necroptosis in experimental asthma.

RESULTS

High expression of necroptosis marker proteins was observed in the serum of asthmatics, and necroptosis was activated in the airway epithelium of both asthmatics and OVA-induced mice. Blocking necroptosis through MLKL knockout or RIPK3 inhibition effectively attenuated parabronchial inflammation, mucus hypersecretion, and airway collagen fiber accumulation, while also suppressing type 2 inflammatory factors secretion. In addition, TL1A/ DR3 was shown to act as a death trigger for necroptosis in the absence of caspases by silencing or overexpressing TL1A in HBE cells. Furthermore, the recombinant TL1A protein was found to induce necroptosis in vivo, and knockout of MLKL partially reversed the pathological changes induced by TL1A. The necroptosis induced by TL1A disrupted the airway barrier function by decreasing the expression of tight junction proteins zonula occludens-1 (ZO-1) and occludin, possibly through the activation of the NF-κB signaling pathway.

CONCLUSIONS

TL1A-induced airway epithelial necroptosis plays a significant role in promoting airway inflammation and barrier dysfunction in asthma. Inhibition of the TL1A-induced necroptosis pathway could be a promising therapeutic strategy.

TL1A is an epithelial alarmin that cooperates with IL-33 for initiation of allergic airway inflammation

Epithelium-derived cytokines or alarmins, such as interleukin-33 (IL-33) and thymic stromal lymphopoietin (TSLP), are major players in type 2 immunity and asthma. Here, we demonstrate that TNF-like ligand 1A (TL1A) is an epithelial alarmin, constitutively expressed in alveolar epithelium at steady state in both mice and humans, which cooperates with IL-33 for early induction of IL-9high ILC2s during the initiation of allergic airway inflammation. Upon synergistic activation by IL-33 and TL1A, lung ILC2s acquire a transient IL-9highGATA3low "ILC9" phenotype and produce prodigious amounts of IL-9. A combination of large-scale proteomic analyses, lung intravital microscopy, and adoptive transfer of ILC9 cells revealed that high IL-9 expression distinguishes a multicytokine-producing state-of-activated ILC2s with an increased capacity to initiate IL-5-dependent allergic airway inflammation. Similar to IL-33 and TSLP, TL1A is expressed in airway basal cells in healthy and asthmatic human lungs. Together, these results indicate that TL1A is an epithelium-derived cytokine and an important cofactor of IL-33 in the airways.

Deciphering Tumor Cell Evolution in Cutaneous T-Cell Lymphomas: Distinct Differentiation Trajectories in Mycosis Fungoides and Sézary Syndrome

Cutaneous T-cell lymphomas are a heterogeneous group of neoplasms originating in the skin, with mycosis fungoides (MF) and Sézary syndrome (SS) representing the most common variants. The cellular origin of cutaneous lymphomas has remained controversial owing to their immense phenotypic heterogeneity that obfuscates lineage reconstruction on the basis of classical surface biomarkers. To overcome this heterogeneity and reconstruct the differentiation trajectory of malignant cells in MF and SS, TCR sequencing was performed in parallel with targeted transcriptomics at the single-cell resolution among cutaneous samples in MF and SS. Unsupervised lineage reconstruction showed that Sézary cells exist as a population of CD4+ T cells distinct from those in patch, plaque, and tumor MF. Further investigation of malignant cell heterogeneity in SS showed that Sézary cells phenotypically comprised at least 3 subsets on the basis of differential proliferation potentials and expression of exhaustion markers. A T helper 1-polarized cell type, intermediate cell type, and exhausted T helper 2-polarized cell type were identified, with T helper 1- and T helper 2-polarized cells displaying divergent proliferation potentials. Collectively, these findings provide evidence to clarify the relationship between MF and SS and reveal cell subsets in SS that suggest a possible mechanism for therapeutic resistance.

Inflammatory bowel disease and allergic diseases: A Mendelian randomization study

BACKGROUND

Inflammatory bowel disease (IBD) and allergic diseases possess similar genetic backgrounds and pathogenesis. Observational studies have shown a correlation, but the exact direction of cause and effect remains unclear. The aim of this Mendelian randomization (MR) study is to assess bidirectional causality between inflammatory bowel disease and allergic diseases.

METHOD

We comprehensively analyzed the causal relationship between inflammatory bowel disease (IBD), Crohn's disease (CD), ulcerative colitis (UC) and allergic disease (asthma, Hay fever, and eczema) as a whole, allergic conjunctivitis (AC), atopic dermatitis (AD), allergic asthma (AAS), and allergic rhinitis (AR) by performing a bidirectional Mendelian randomization study using summary-level data from genome-wide association studies. The analysis results mainly came from the random-effects model of inverse variance weighted (IVW-RE). In addition, multivariate Mendelian randomization (MVMR) analysis was conducted to adjust the effect of body mass index (BMI) on the instrumental variables.

RESULTS

The IVW-RE method revealed that IBD genetically increased the risk of allergic disease as a whole (OR = 1.03, 95% CI = 1.01-1.04, fdr.p = .015), AC (OR = 1.04, 95% CI = 1.01-1.06, fdr.p = .011), and AD (OR = 1.06, 95% CI = 1.02-1.09, fdr.p = .004). Subgroup analysis further confirmed that CD increased the risk of allergic disease as a whole (OR = 1.02, 95% CI = 1.00-1.03, fdr.p = .031), AC (OR = 1.03, 95% CI = 1.01-1.05, fdr.p = .012), AD (OR = 1.06, 95% CI = 1.02-1.09, fdr.p = 2E-05), AAS (OR = 1.05, 95% CI = 1.02-1.08, fdr.p = .002) and AR (OR = 1.03, 95% CI = 1.00-1.07, fdr.p = .025), UC increased the risk of AAS (OR = 1.02, 95% CI = 0.98-1.07, fdr.p = .038). MVMR results showed that after taking BMI as secondary exposure, the causal effects of IBD on AC, IBD on AD, CD on allergic disease as a whole, CD on AC, CD on AD, CD on AAS, and CD on AR were still statistically significant. No significant association was observed in the reverse MR analysis.

CONCLUSION

This Mendelian randomized study demonstrated that IBD is a risk factor for allergic diseases, which is largely attributed to its subtype CD increasing the risk of AC, AD, ASS, and AR. Further investigations are needed to explore the causal relationship between allergic diseases and IBD.

The ever-expanding role of cytokine receptor DR3 in T cells

Death Receptor 3 (DR3) is a cytokine receptor of the Tumor Necrosis Factor receptor superfamily that plays a multifaceted role in both innate and adaptive immunity. Based on the death domain motif in its cytosolic tail, DR3 had been proposed and functionally affirmed as a trigger of apoptosis. Further studies, however, also revealed roles of DR3 in other cellular pathways, including inflammation, survival, and proliferation. DR3 is expressed in various cell types, including T cells, B cells, innate lymphocytes, myeloid cells, fibroblasts, and even outside the immune system. Because DR3 is mainly expressed on T cells, DR3-mediated immune perturbations leading to autoimmunity and other diseases were mostly attributed to DR3 activation of T cells. However, which T cell subset and what T effector functions are controlled by DR3 to drive these processes remain incompletely understood. DR3 engagement was previously found to alter CD4 T helper subset differentiation, expand the Foxp3+ Treg cell pool, and maintain intraepithelial γδ T cells in the gut. Recent studies further unveiled a previously unacknowledged aspect of DR3 in regulating innate-like invariant NKT (iNKT) cell activation, expanding the scope of DR3-mediated immunity in T lineage cells. Importantly, in the context of iNKT cells, DR3 ligation exerted costimulatory effects in agonistic TCR signaling, unveiling a new regulatory framework in T cell activation and proliferation. The current review is aimed at summarizing such recent findings on the role of DR3 on conventional T cells and innate-like T cells and discussing them in the context of immunopathogenesis.

COL3A1: Potential prognostic predictor for head and neck cancer based on immune-microenvironment alternative splicing

We aimed to identify a novel prognostic biomarker for head and neck squamous cell carcinoma (HNSCC) based on tumor immunology-related alternative splicing (AS). Data for 502 HNSCC and 44 normal samples were obtained from the TCGA database and used to establish an AS-related risk model through univariate, least absolute shrinkage, and selection operator Cox regression analyses. Fresh HNSCC and normal oral tissues were surgically obtained from 44 HNSCC patients. Western blotting and quantitative reverse transcription-PCR were used to assess gene expression levels. Kaplan-Meier was performed to evaluate patients' overall survival (OS) rate. The CIBERSORT algorithm, single-sample gene set enrichment analysis, and immune checkpoint analyses were performed to compare immune activities between subgroups. The risk model was established using 10 pivotal AS events first. Collagen Type III Alpha 1 Chain (COL3A1) were screened based on |log2FC| ≥ 1 and FDR < 0.05 criteria. COL3A1 expression levels in HNSCC tissues were elevated relative to normal tissues (p < 0.001). Moreover, COL3A1 was a reliable biomarker for HNSCC patients' prognostic prediction in both cohorts (p < 0.001, p = 0.0085, respectively). COL3A1 protein (p = 0.0054) and mRNA (p < 0.0001) levels were correlated with HNSCC differentiation. Furthermore, the T stage was correlated with COL3A1 expression (p = 0.043), and COL3A1 expression was an independent prognostic predictor for HNSCC patients (p = 0.006). Compared with the risk model, COL3A1 was better at evaluating immune cell infiltrations, immune activities, and immune checkpoint gene expressions of HNSCC lesions.

Costimulatory molecule expression profile as a biomarker to predict prognosis and chemotherapy response for patients with small cell lung cancer

Owing to the paucity of specimens, progress in identifying prognostic and therapeutic biomarkers for small cell lung cancer (SCLC) has been stagnant for decades. Considering that the costimulatory molecules are essential elements in modulating immune responses and determining therapeutic response, we systematically revealed the expression landscape and identified a costimulatory molecule-based signature (CMS) to predict prognosis and chemotherapy response for SCLCs for the first time. We found T cell activation was restrained in SCLCs, and costimulatory molecules exhibited widespread abnormal genetic alterations and expression. Using a LASSO Cox regression model, the CMS was built with a training cohort of 77 cases, which successfully divided patients into high- or low-risk groups with significantly different prognosis and chemotherapy benefit (both P < 0.001). The CMS was well validated in an independent cohort containing 131 samples with qPCR data. ROC and C-index analysis confirmed the superior predictive performance of the CMS in comparison with other clinicopathological parameters from different cohorts. Importantly, the CMS was confirmed as a significantly independent prognosticator for clinical outcomes and chemotherapy response in SCLCs through multivariate Cox analysis. Further analysis revealed that low-risk patients were characteristic by an activated immune phenotype with distinct expression of immune checkpoints. In summary, we firstly uncovered the expression heterogeneity of costimulatory molecules in SCLC and successfully constructed a novel predictive CMS. The identified signature contributed to more accurate patient stratification and provided robust prognostic value in estimating survival and the clinical response to chemotherapy, allowing optimization of treatment and prognosis management for patients with SCLC.

Peanut allergen induces more serious allergic reactions than other allergens involving MAPK signaling pathways

There is no universally accepted uniform research to classify the severity of allergic reactions triggered by different food allergens. We established a food allergy model based on repeated intragastric administrations of proteins from peanut, egg, milk, or soybean mixed with cholera toxin followed by oral food challenges with a high dose of the sensitizing proteins. Increased specific IgE, specific IgG1, allergic symptom scores, histamine, murine mast cell proteases-1, vascular leakage, Th2 cytokines, and mast cell infiltration in the lungs and intestine were found in the allergic groups via enzyme-linked immunosorbent assay, hematoxylin-eosin, and toluidine blue staining. Each sensitized group showed a decrease in body temperature and Th1 cytokines after oral food challenge. The increased levels of Th2 cytokines, IL-25, IL-33, and TSLP, and related asthma genes ARG1, DCN, LTB4R1 and NFKBIA as well as the activation of MAPK signaling pathways were also revealed by quantitative real-time PCR and western blotting. In terms of the severity of food allergies, peanut allergy was the most serious followed by egg and milk, and soybean allergy was the least severe. Compared to other allergic groups, asthma genes were regulated through the MAPK signaling pathways to produce related Th2 cytokines in peanut allergy; consequently, mice in the peanut group exhibited more severe allergic reactions. Comparison of the severity of food allergies is required for the development of milder prevention for severe food allergies.

Role of TL1A in Inflammatory Autoimmune Diseases: A Comprehensive Review

TL1A, also called TNFSF15, is a member of tumor necrosis factor family. It is expressed in different immune cell, such as monocyte, macrophage, dendritic cell, T cell and non-immune cell, for example, synovial fibroblast, endothelial cell. TL1A competitively binds to death receptor 3 or decoy receptor 3, providing stimulatory signal for downstream signaling pathways, and then regulates proliferation, activation, apoptosis of and cytokine, chemokine production in effector cells. Recent findings showed that TL1A was abnormally expressed in autoimmune diseases, including rheumatoid arthritis, inflammatory bowel disease, psoriasis, primary biliary cirrhosis, systemic lupus erythematosus and ankylosing spondylitis. In vivo and in vitro studies further demonstrated that TL1A was involved in development and pathogenesis of these diseases. In this study, we comprehensively discussed the complex immunological function of TL1A and focused on recent findings of the pleiotropic activity conducted by TL1A in inflammatory autoimmune disease. Finish of the study will provide new ideas for developing therapeutic strategies for these diseases by targeting TL1A.

Tumor necrosis factor receptor superfamily member 25 (TNFRSF25) agonists in islet transplantation: Endogenous in vivo regulatory T cell expansion promotes prolonged allograft survival

Regulatory T cells (Tregs) modulate alloimmune responses and may facilitate minimization or withdrawal of immunosuppression posttransplant. Current approaches, however, rely on complex ex vivo Treg expansion protocols. Herein, we explore endogenous in vivo Treg expansion through antibody-mediated agonistic stimulation of the tumor necrosis factor receptor superfamily member 25 (TNFRSF25) pathway and its potential to prolong graft survival in a mouse model of islet allotransplantation. C57BL/6 male mice were treated with a single dose of TNFRSF25 agonistic antibodies (4C12 or mPTX-35) or IgG control. Diabetes was induced using streptozotocin. Four days later, flow cytometry was completed to corroborate Treg expansion, and 500 islets (CBA/J male mice) were transplanted. Glycemia was assessed thrice weekly until rejection/endpoint. Early intra-graft Treg infiltration was assessed 36 h posttransplant. TNFRSF25 antibodies enabled pronounced Treg expansion and treated mice had significantly prolonged graft survival compared with controls (p < .001). Additionally, the degree of Treg expansion significantly correlated with graft survival (p < .001). Immunohistochemistry demonstrated marked Treg infiltration in long-term surviving grafts; intra-graft Treg infiltration occurred early posttransplant. In conclusion, a single dose of TNFRSF25 antibodies enabled in vivo Treg expansion, which promotes prolonged graft survival. TNFRSF25-mediated in vivo Treg expansion could contribute to achieving lasting immunological tolerance in organ transplantation.

Espin overexpression causes stereocilia defects and provides an anti-capping effect on actin polymerization

Stereocilia are actin-based projections of hair cells that are arranged in a step like array, in rows of increasing height, and that constitute the mechanosensory organelle used for the senses of hearing and balance. In order to function properly, stereocilia must attain precise sizes in different hair cell types and must coordinately form distinct rows with varying lengths. Espins are actin-bundling proteins that have a well-characterized role in stereocilia formation; loss of function mutations in Espin result in shorter stereocilia and deafness in the jerker mouse. Here we describe the generation of an Espin overexpressing transgenic mouse line that results in longer first row stereocilia and discoordination of second-row stereocilia length. Furthermore, Espin overexpression results in the misregulation of other stereocilia factors including GNAI3, GPSM2, EPS8, WHRN, and MYO15A, revealing that GNAI3 and GPSM2 are dispensable for stereocilia overgrowth. Finally, using an in vitro actin polymerization assay we show that espin provides an anti-capping function that requires both the G-actin binding WH2 domain as well as either the C-terminal F-actin binding domain or the internal xAB actin-binding domain. Our results provide a novel function for Espins at the barbed ends of actin filaments distinct from its previous known function of actin bundling that may account for their effects on stereocilia growth.

Mapping Rora expression in resting and activated CD4+ T cells

The transcription factor Rora has been shown to be important for the development of ILC2 and the regulation of ILC3, macrophages and Treg cells. Here we investigate the role of Rora across CD4+ T cells in general, but with an emphasis on Th2 cells, both in vitro as well as in the context of several in vivo type 2 infection models. We dissect the function of Rora using overexpression and a CD4-conditional Rora-knockout mouse, as well as a RORA-reporter mouse. We establish the importance of Rora in CD4+ T cells for controlling lung inflammation induced by Nippostrongylus brasiliensis infection, and have measured the effect on downstream genes using RNA-seq. Using a systematic stimulation screen of CD4+ T cells, coupled with RNA-seq, we identify upstream regulators of Rora, most importantly IL-33 and CCL7. Our data suggest that Rora is a negative regulator of the immune system, possibly through several downstream pathways, and is under control of the local microenvironment.

Analysis of therapeutic potential of preclinical models based on DR3/TL1A pathway modulation (Review)

Death receptor 3 (DR3) and its corresponding ligand, tumor necrosis factor-like ligand 1A (TL1A), belong to the tumor necrosis factor superfamily. Signaling via this receptor-ligand pair results in pro-inflammatory and anti-inflammatory effects. Effector lymphocytes can be activated to exert pro-inflammatory activity by triggering the DR3/TL1A pathway. By contrast, DR3/TL1A signaling also induces expansion of the suppressive function of regulatory T cells, which serve an important role in exerting anti-inflammatory functions and maintaining immune homeostasis. Preclinical evidence indicates that neutralizing and agonistic antibodies, as well as ligand-based approaches targeting the DR3/TL1A pathway, may be used to treat diseases, including inflammatory and immune-mediated diseases. Accumulating evidence has suggested that modulating the DR3/TL1A pathway is a promising therapeutic approach for patients with these diseases. This review discusses preclinical models to gauge the progress of therapeutic strategies for diseases involving the DR3/TL1A pathway to aid in drug development.

Use of Post-transplant Cyclophosphamide Treatment to Build a Tolerance Platform to Prevent Liquid and Solid Organ Allograft Rejection

Corneal transplantation (CT) is the most frequent type of solid organ transplant (SOT) performed worldwide. Unfortunately, immunological rejection is the primary cause of graft failure for CT and therefore advances in immune regulation to induce tolerance remains an unmet medical need. Recently, our work and others in pre-clinical studies found that cyclophosphamide (Cy) administered after (“post-transplant,” PTCy) hematopoietic stem cell transplantation (HSCT), i.e., liquid transplants is effective for graft vs. host disease prophylaxis and enhances overall survival. Importantly, within the past 10 years, PTCy has been widely adopted for clinical HSCT and the results at many centers have been extremely encouraging. The present studies found that Cy can be effectively employed to prolong the survival of SOT, specifically mouse corneal allografts. The results demonstrated that the timing of PTCy administration is critical for these CT and distinct from the kinetics employed following allogeneic HSCT. PTCy was observed to interfere with neovascularization, a process critically associated with immune rejection of corneal tissue that ensues following the loss of ocular “immune privilege.” PTCy has the potential to delete or directly suppress allo-reactive T cells and treatment here was shown to diminish T cell rejection responses. These PTCy doses were observed to spare significant levels of CD4⁺ FoxP3⁺ (Tregs) which were found to be functional and could readily receive stimulating signals leading to their in vivo expansion via TNFRSF25 and CD25 agonists. In total, we posit future studies can take advantage of Cy based platforms to generate combinatorial strategies for long-term tolerance induction.

Tumor antigen specific iTreg accumulate in the tumor microenvironment and suppress therapeutic vaccination

Tumor specific antigens (TSA) provide an opportunity to mobilize therapeutic immune responses against cancer. To evade such responses, tumor development in immunocompetent hosts is accompanied by acquisition of both active and passive mechanisms of immune suppression, including recruitment of CD4+FoxP3+ regulatory T cells (Treg). Thymic derived Treg (nTreg) may recognize self-antigens in the tumor microenvironment, while peripherally induced Treg (iTreg) may preferentially recognize the same TSA which provide an opportunity for therapeutic immunity from peripheral T cells. In this study we provide a systematic analysis of nTreg and iTreg accumulation in the tumor microenvironment (TME) at the cellular level. iTreg accumulation to the TME was influenced by the abundance of a known TSA, and in the absence of a known TSA intratumoral Treg displayed a unique TCR repertoire from peripheral Treg. In vivo suppression assays demonstrate that cognate-antigen matched iTreg are more potent suppressors of CD4+ than are polyclonal iTreg or nTreg, but were unable to suppress CD8+ T cell proliferation. Suppression occurred only locally at the site of immunization, and correlated with decreased expression of CD80 and CD86 on CD11c positive cells. Although established tumors facilitated the induction of TSA-specific iTreg, these iTreg suppressed CD4+ T cell accumulation only locally to the TME. Tumor mediated suppression of CD8+ T cell immunity appeared independent of TSA-specific iTreg.

Treatment options in type-2 low asthma

Monoclonal antibodies targeting IgE or the type-2 cytokines interleukin (IL)-4, IL-5 and IL-13 are proving highly effective in reducing exacerbations and symptoms in people with severe allergic and eosinophilic asthma, respectively. However, these therapies are not appropriate for 30-50% of patients in severe asthma clinics who present with non-allergic, non-eosinophilic, "type-2 low" asthma. These patients constitute an important and common clinical asthma phenotype, driven by distinct, yet poorly understood pathobiological mechanisms. In this review we describe the heterogeneity and clinical characteristics of type-2 low asthma and summarise current knowledge on the underlying pathobiological mechanisms, which includes neutrophilic airway inflammation often associated with smoking, obesity and occupational exposures and may be driven by persistent bacterial infections and by activation of a recently described IL-6 pathway. We review the evidence base underlying existing treatment options for specific treatable traits that can be identified and addressed. We focus particularly on severe asthma as opposed to difficult-to-treat asthma, on emerging data on the identification of airway bacterial infection, on the increasing evidence base for the use of long-term low-dose macrolides, a critical appraisal of bronchial thermoplasty, and evidence for the use of biologics in type-2 low disease. Finally, we review ongoing research into other pathways including tumour necrosis factor, IL-17, resolvins, apolipoproteins, type I interferons, IL-6 and mast cells. We suggest that type-2 low disease frequently presents opportunities for identification and treatment of tractable clinical problems; it is currently a rapidly evolving field with potential for the development of novel targeted therapeutics.

A TRAIL-TL1A Paracrine Network Involving Adipocytes, Macrophages, and Lymphocytes Induces Adipose Tissue Dysfunction Downstream of E2F1 in Human Obesity

Elevated expression of E2F1 in adipocyte fraction of human visceral adipose tissue (hVAT) associates with a poor cardiometabolic profile. We hypothesized that beyond directly activating autophagy and MAP3K5 (ASK)-MAP kinase signaling, E2F1 governs a distinct transcriptome that contributes to adipose tissue and metabolic dysfunction in obesity. We performed RNA sequencing of hVAT samples from age-, sex-, and BMI-matched patients, all obese, whose visceral E2F1 protein expression was either high (E2F1^high) or low (E2F1^low). Tumor necrosis factor superfamily (TNFSF) members, including TRAIL (TNFSF10), TL1A (TNFSF15), and their receptors, were enriched in E2F1^high While TRAIL was equally expressed in adipocytes and stromal vascular fraction (SVF), TL1A was mainly expressed in SVF, and TRAIL-induced TL1A was attributed to CD4⁺ and CD8⁺ subclasses of hVAT T cells. In human adipocytes, TL1A enhanced basal and impaired insulin-inhibitable lipolysis and altered adipokine secretion, and in human macrophages it induced foam cell biogenesis and M1 polarization. Two independent human cohorts confirmed associations between TL1A and TRAIL expression in hVAT and higher leptin and IL6 serum concentrations, diabetes status, and hVAT-macrophage lipid content. Jointly, we propose an intra-adipose tissue E2F1-associated TNFSF paracrine loop engaging lymphocytes, macrophages, and adipocytes, ultimately contributing to adipose tissue dysfunction in obesity.

Association between prenatal bisphenol a exposure and promoter hypermethylation of CAPS2, TNFRSF25, and HKR1 genes in cord blood

In utero exposure to bisphenol A (BPA) in early stages of development has been reported to exert adverse health effects on offspring later in life. Epigenetic alterations, particularly DNA methylation, may be one plausible biological mechanism involved. We examined the association between maternal BPA exposure and DNA methylation in cord blood. We randomly selected 96 paired samples of maternal urine and infant cord blood collected from the Shanghai-Minhang Birth Cohort. BPA levels in maternal urine were measured using high-performance liquid chromatography (HPLC). Three cord blood samples with maternal BPA levels >2.0 μg/g Cr and three samples with undetected BPA were randomly selected for genome-wide methylation analysis using methylated DNA binding domain sequencing (MBD-Seq). The genes with hypermethylated promoter regions were chosen for validation using quantitative methylation-specific polymerase chain reaction (Q-MSP). Based on MBD-seq results, we observed that maternal BPA exposure was primarily associated with hypermethylation of genes involved in signal transduction in the nervous system. Using Q-MSP, we further validated the association between maternal BPA exposure and promoter hypermethylation of three genes in multiple linear regression models: a log unit increase in BPA was associated with 12.63% (95%CI: 7.99, 17.26), 11.17%, (95%CI: 3.31, 19.02), and 16.57% (95% CI: 10.59, 22.56) increase in promoter of CAPS2, TNFRSF25, and HKR1 methylation, respectively. Our findings provide evidence that in utero exposure to BPA could alter the offspring's epigenome by altering DNA methylation pattern.

TNFSF15 Promotes Antimicrobial Pathways in Human Macrophages and These Are Modulated by TNFSF15 Disease-Risk Variants

BACKGROUND & AIMS

TNFSF15 genetic variants leading to increased TNF superfamily member 15 (TNFSF15) expression confer risk for inflammatory bowel disease (IBD), and TNFSF15 is being explored as a therapeutic target in IBD patients. Although the focus for TNFSF15-mediated inflammatory outcomes has been predominantly on its action on T cells, TNFSF15 also promotes inflammatory outcomes in human macrophages. Given the critical role for macrophages in bacterial clearance, we hypothesized that TNFSF15 promotes antimicrobial pathways in human macrophages and that macrophages from TNFSF15 IBD risk carriers with higher TNFSF15 expression have an advantage in these antimicrobial outcomes.

METHODS

We analyzed protein expression, signaling, bacterial uptake, and intracellular bacterial clearance in human monocyte-derived macrophages through flow cytometry, enzyme-linked immunosorbent assay, and gentamicin protection.

RESULTS

Autocrine/paracrine TNFSF15 interactions with death receptor 3 (DR3) were required for optimal levels of pattern-recognition-receptor (PRR)-induced bacterial clearance in human macrophages. TNFSF15 induced pyruvate dehydrogenase kinase 1-dependent bacterial uptake and promoted intracellular bacterial clearance through reactive oxygen species, nitric oxide synthase 2, and autophagy up-regulation. The TNFSF15-initiated TNF receptor-associated factor 2/receptor-interacting protein kinase 1/RIP3 pathway was required for mitogen-activated protein kinase and nuclear factor-κB activation, and, in turn, induction of each of the antimicrobial pathways; the TNFSF15-initiated Fas-associated protein with death domain/mucosa-associated lymphoid tissue lymphoma translocation protein 1/caspase-8 pathway played a less prominent role in antimicrobial functions, despite its key role in TNFSF15-induced cytokine secretion. Complementation of signaling pathways or antimicrobial pathways restored bacterial uptake and clearance in PRR-stimulated macrophages where TNFSF15:DR3 interactions were inhibited. Monocyte-derived macrophages from high TNFSF15-expressing rs6478108 TT IBD risk carriers in the TNFSF15 region showed increased levels of the identified antimicrobial pathways.

CONCLUSIONS

We identify that autocrine/paracrine TNFSF15 is required for optimal PRR-enhanced antimicrobial pathways in macrophages, define mechanisms regulating TNFSF15-dependent bacterial clearance, and determine how the TNFSF15 IBD risk genotype modulates these outcomes.

Tumour-associated macrophages as a novel target of VEGI-251 in cancer therapy

Tumour‐associated macrophages (TAMs), which possess M2‐like characters and are derived from immature monocytes in the circulatory system, represent a predominant population of inflammatory cells in solid tumours. TAM infiltration in tumour microenvironment can be used as an important prognostic marker in many cancer types and is a potential target for cancer prevention or treatment. VEGI‐251 not only is involved in the inhibition of tumour angiogenesis, but also participates in the regulation of host immunity. This work aimed to investigate the involvement of VEGI‐251 in the regulation of specific antitumour immunity. We found that recombinant human VEGI‐251(rhVEGI‐251) efficiently mediated the elimination of TAMs in tumour tissue in mice, and induced apoptosis of purified TAMs in vitro. During this process, caspase‐8 and caspase‐3 were activated, leading to PARP cleavage and apoptosis. Most importantly, we further elucidated the mechanism underlying VEGI‐251‐triggered TAM apoptosis, which suggests that ASK1, an intermediate component of the VEGI‐251, activates the JNK pathway via TRAF2 in a potentially DR3‐dependent manner in the process of TAM apoptosis. Collectively, our findings provide new insights into the basic mechanisms underlying the actions of VEGI‐251 that might lead to future development of antitumour therapeutic strategies using VEGI‐251 to target TAMs.

Circulating TNF-like protein 1A (TL1A) is elevated early in rheumatoid arthritis and depends on TNF

Background

The tumor necrosis factor (TNF) superfamily cytokine TNF-like protein 1A (TL1A) and its receptor DR3 are essential for diverse animal models of autoimmune disease and may be pathogenic in rheumatoid arthritis (RA). However, the relationship of TL1A to disease duration, activity, and response to anti-TNF and other therapies in RA is not clear.

Methods

We measured soluble TL1A in synovial fluid (SF), serum, or plasma from RA first-degree relatives (FDRs) and in early RA and established disease. We measured the effects of anti-TNF and methotrexate (MTX) therapy on circulating TL1A from multiple independent RA treatment trials. We also determined the ability of a blocking anti-TL1A antibody to inhibit clinical disease and articular bone destruction in the murine collagen-induced arthritis (CIA) model of human RA.

Results

Soluble TL1A was specifically elevated in the blood and SF of patients with RA compared to patients with other diseases and was elevated early in disease and in at-risk anti-cyclic citrullinated peptide (CCP) (+) first-degree relatives (FDRs). Therapeutic TNF inhibition reduced serum TL1A in both responders and non-responders, whereas TL1A declined following MTX treatment only in responders. In murine CIA, TL1A blockade was clinically efficacious and reduced bone erosions.

Conclusions

TL1A is specifically elevated in RA from early in the disease course and in at-risk FDRs. The decline in TL1A after TNF blockade suggests that TL1A levels may be a useful biomarker for TNF activity in RA. These results support the further investigation of the relationship between TL1A and TNF and TL1A blockade as a potential therapeutic strategy in RA.

T cell co-stimulation and co-inhibition in cardiovascular disease: a double-edged sword

The role of inflammation in cardiovascular disease (CVD) is now widely accepted. Immune cells, including T cells, are influenced by inflammatory signals and contribute to the onset and progression of CVD. T cell activation is modulated by T cell co-stimulation and co-inhibition pathways. Immune checkpoint inhibitors (ICIs) targeting T cell inhibition pathways have revolutionized cancer treatment and improved survival in patients with cancer. However, ICIs might induce cardiovascular toxicity via T cell re-invigoration. With the rising use of ICIs for cancer treatment, a timely overview of the role of T cell co-stimulation and inhibition molecules in CVD is desirable. In this Review, the importance of these molecules in the pathogenesis of CVD is highlighted in preclinical studies on models of CVD such as vein graft disease, myocarditis, graft arterial disease, post-ischaemic neovascularization and atherosclerosis. This Review also discusses the therapeutic potential of targeting T cell co-stimulation and inhibition pathways to treat CVD, as well as the possible cardiovascular benefits and adverse events after treatment. Finally, the Review emphasizes that patients with cancer who are treated with ICIs should be monitored for CVD given the reported association between the use of ICIs and the risk of cardiovascular toxicity.

Targeting of CD133+ Cancer Stem Cells by Mesenchymal Stem Cell Expressing TRAIL Reveals a Prospective Role of Apoptotic Gene Regulation in Non-Small Cell Lung Cancer

Mesenchymal stem cells (MSCs) are emerging as vehicles for anti-tumor cytotherapy; however, investigation on its efficacy to target a specific cancer stem cell (CSC) population in non-small cell lung cancer (NSCLC) is lacking. Using assays to evaluate cell proliferation, apoptosis, and gene expression, we investigated the efficacy of MSCs expressing tumour necrosis factor (TNF)-related apoptosis inducing ligand (MSC-TRAIL) to target and destroy CD133+ (prominin-1 positive) NSCLC-derived CSCs. Characterization of TRAIL death receptor 5 (DR5) revealed that it was highly expressed in the CD133+ CSCs of both H460 and H2170 cell lines. The human MSC-TRAIL generated in the study maintained its multipotent characteristics, and caused significant tumor cell inhibition in NSCLC-derived CSCs in a co-culture. The MSC-TRAIL induced an increase in annexin V expression, an indicator of apoptosis in H460 and H2170 derived CD133+ CSCs. Through investigation of mitochondria membrane potential, we found that MSC-TRAIL was capable of inducing intrinsic apoptosis to the CSCs. Using pathway-specific gene expression profiling, we uncovered candidate genes such as NFKB1, BAG3, MCL1, GADD45A, and HRK in CD133+ CSCs, which, if targeted, might increase the sensitivity of NSCLC to MSC-TRAIL-mediated inhibition. As such, our findings add credibility to the utilization of MSC-TRAIL for the treatment of NSCLC through targeting of CD133+ CSCs.

Activation of the DR3-TL1A Axis in Donor Mice Leads to Regulatory T Cell Expansion and Activation With Reduction in Graft-Versus-Host Disease

Death receptor 3 (DR3) is a tumor necrosis factor receptor superfamily member (TNFRSF25), which is minimally expressed on resting conventional T cells (though readily inducible upon cell activation), yet highly expressed on resting FoxP3⁺ regulatory T cells (Treg). We recently demonstrated that activation of DR3 with an agonistic antibody (4C12) leads to selective expansion and activation of Treg in healthy mice and suppression of graft-versus-host disease (GVHD) in recipient mice when donor mice are treated. However, given the long antibody half-life and concomitant safety concerns, along with the lack of a humanized agonistic antibody to DR3, both human and murine fusion proteins incorporating the natural DR3 ligand TL1A (TL1A-Ig) have been developed. Herein, we show that DR3 activation with 4C12 or with TL1A-Ig, with or without the addition of low dose IL-2 to the treatment regimen, led to a significant expansion of murine Treg in spleen, lymph nodes, and peripheral blood. Bioluminescent imaging revealed peak Treg expansion around day 7-8, with return to near baseline after 2-3 weeks. In addition to expansion, all DR3 agonist treatment regimens led to increased activation of Tregs, with significant upregulation of the activation markers ICOS, KLRG-1, PD-1, and CD103, and the proliferation marker Ki-67. The near absence of activated Treg populations in control treated spleens was also detected on tSNE analysis of flow cytometry data. Subtly different patterns of splenic Treg activation by the different DR3 agonists were noted in both tSNE analysis of flow cytometry data and RNA-sequencing analysis. However, upregulation of gene transcripts which play important roles in cell proliferation, trafficking, activation, and effector function were observed regardless of the DR3 agonist treatment regimen used. In the major MHC-mismatch model of hematopoietic cell transplantation, DR3 agonist-mediated expansion and activation of Tregs in donor mice led to a significant improvement in GVHD in recipient mice. These data provide important preclinical information regarding the outcome of DR3 activation with an agonistic antibody or natural ligand and provide insight into the therapeutic use of this approach to reduce GVHD in recipients and improve outcomes of hematopoietic cell transplantation.

Human gut derived-organoids provide model to study gluten response and effects of microbiota-derived molecules in celiac disease

Celiac disease (CD) is an immune-mediated disorder triggered by gluten exposure. The contribution of the adaptive immune response to CD pathogenesis has been extensively studied, but the absence of valid experimental models has hampered our understanding of the early steps leading to loss of gluten tolerance. Using intestinal organoids developed from duodenal biopsies from both non-celiac (NC) and celiac (CD) patients, we explored the contribution of gut epithelium to CD pathogenesis and the role of microbiota-derived molecules in modulating the epithelium’s response to gluten. When compared to NC, RNA sequencing of CD organoids revealed significantly altered expression of genes associated with gut barrier, innate immune response, and stem cell functions. Monolayers derived from CD organoids exposed to gliadin showed increased intestinal permeability and enhanced secretion of pro-inflammatory cytokines compared to NC controls. Microbiota-derived bioproducts butyrate, lactate, and polysaccharide A improved barrier function and reduced gliadin-induced cytokine secretion. We concluded that: (1) patient-derived organoids faithfully express established and newly identified molecular signatures characteristic of CD. (2) microbiota-derived bioproducts can be used to modulate the epithelial response to gluten. Finally, we validated the use of patient-derived organoids monolayers as a novel tool for the study of CD.

A role for BATF3 in TH9 differentiation and T-cell-driven mucosal pathologies

T helper 9 (T_H9) cells are important for the development of inflammatory and allergic diseases. The T_H9 transcriptional network converges signals from cytokines and antigen presentation but is incompletely understood. Here, we identified TL1A, a member of the TNF superfamily, as a strong inducer of mouse and human T_H9 differentiation. Mechanistically, TL1A induced the expression of the transcription factors BATF and BATF3 and facilitated their binding to the Il9 promoter leading to enhanced secretion of IL-9. BATF- and BATF3-deficiencies impaired IL-9 secretion under T_H9 and T_H9-TL1A-polarizing conditions. In vivo, using a T-cell transfer model, we demonstrated that TL1A promoted IL-9-dependent, T_H9 cell-induced intestinal and lung inflammation. Neutralizing IL-9 antibodies attenuated TL1A-driven mucosal inflammation. Batf3^-/- T_H9-TL1A cells induced reduced inflammation and cytokine expression in vivo compared to WT cells. Our results demonstrate that TL1A promotes T_H9 cell differentiation and function and define a role for BATF3 in T-cell-driven mucosal inflammation.

TL1A (TNFSF15) and DR3 (TNFRSF25): A Co-stimulatory System of Cytokines With Diverse Functions in Gut Mucosal Immunity

TL1A and its functional receptor DR3 are members of the TNF/TNFR superfamilies of proteins. Binding of APC-derived TL1A to lymphocytic DR3 provides co-stimulatory signals for activated lymphocytes. DR3 signaling affects the proliferative activity of and cytokine production by effector lymphocytes, but also critically influences the development and suppressive function of regulatory T-cells. DR3 was also found to be highly expressed by innate lymphoid cells (ILCS), which respond to stimulation by TL1A. Several recent studies with transgenic and knockout mice as well as neutralizing or agonistic antibodies for these two proteins, have clearly shown that TL1A/DR3 are important mediators of several chronic immunological disorders, including Inflammatory Bowel Disease (IBD). TL1A and DR3 are abundantly localized at inflamed intestinal areas of patients with IBD and mice with experimental ileitis or colitis and actively participate in the immunological pathways that underlie mucosal homeostasis and intestinal inflammation. DR3 signaling has demonstrated a dichotomous role in mucosal immunity. On the one hand, during acute mucosal injury it exerts protective functions by ameliorating the severity of acute inflammatory responses and facilitating tissue repair. On the other hand, it critically participates in the pro-inflammatory pathways that underlie chronic inflammatory responses, such as those that take place in IBD. These effects are mediated through modulation of the relative mucosal abundance and function of Th1, Th2, Th17, Th9, and Treg lymphocytes, but also of all types of ILCs. Recently, an important role was demonstrated for TL1A/DR3 as potential mediators of intestinal fibrosis that is associated with the presence of gut inflammation. These accumulating data have raised the possibility that TL1A/DR3 pathways may represent a valid therapeutic target for chronic immunological diseases. Nevertheless, applicability of such a therapeutic approach will greatly rely on the net result of TL1A/DR3 manipulation on the various cell populations that will be affected by this approach.

Transcriptome Sequencing Identifies Novel Immune Response Genes Highly Related to the Severity of Human Adenovirus Type 55 Infection

Human adenovirus type 55 (HAdV-55) is considered a highly virulent pathogen causing severe and even deadly pneumonia in immunocompetent people. The mechanisms of HAdV-55-induced initiation and progression of severe pneumonia remain ambiguous. In the current study, we endeavored to identify novel immune response genes which are substantially involved in the pathogenesis of severe inflammation in HAdV-55-infected patients. HAdV-55-infected patients with upper respiratory tract symptoms (minor patients) and pneumonia (severe patients) were enrolled. Through transcriptome sequencing and quantitative real-time PCR, the peripheral blood mononuclear cells of the patients were analyzed. We found that the expression of eight genes, including Il18, Il36b, Il17rc, Tnfsf10, Tnfsf11, Tnfsf14, Tnfsf15, and Il1a, were closely correlated with the severity of HAdV-55 infection. Most of these genes belong to interleukin-1 family or tumor necrosis factor (TNF) superfamily, respectively. The changes in gene expression were confirmed by Western blot assay. Our data will be crucial for deepening the understanding of the pathogenic mechanisms of severe pneumonia in HAdV-55 infection.

Death-Domain-Receptor 3 Deletion Normalizes Inflammatory Gene Expression and Prevents Ileitis in Experimental Crohn's Disease

Background

TNF-like cytokine 1A (TL1A) and its functional receptor, death-domain-receptor-3 (DR3), are multifunctional mediators of effector and regulatory immunity. We aimed to evaluate the functional role and therapeutic potential of TL1A/DR3 signaling in Crohn's disease-like ileitis.

Methods

Ileitis-prone SAMP1/YitFc (SAMP) and TNFΔARE/+ mice were rendered deficient for DR3 or TL1A by microsatellite marker-assisted backcrossing. Pathological and immunological characteristics were compared between control and knockout mice, and mucosal immunophenotype was analyzed by Nanostring microarray assay. The therapeutic effect of pharmacological TL1A neutralization was also investigated.

Results

DR3 deficiency was associated with restoration of a homeostatic mucosal immunostat in SAMP mice through the regulation of several pro- and anti-inflammatory genes. This led to suppression of effector immunity, amelioration of ileitis severity, and compromised ability of either unfractionated CD4+ or CD4+CD45RBhi mucosal lymphocytes to transfer ileitis to severe combined immunodeficient mice recipients. TNF-driven ileitis was also prevented in TNFΔARE/+xDR3-/- mice, in association with decreased expression of the pro-inflammatory cytokines TNF and IFN-γ. In contrast to DR3, TL1A was dispensable for the development of ileitis although it affected the kinetics of inflammation, as TNFΔARE/+xTL1A-/- demonstrated delayed onset of inflammation, whereas administration of a neutralizing, anti-TL1A antibody ameliorated early but not late TNFΔARE/+ ileitis.

Conclusion

We found a prominent pro-inflammatory role of DR3 in chronic ileitis, which is only partially mediated via interaction with TL1A, raising the possibility for additional DR3 ligands. Death-domain-receptor-3 appears to be a master regulator of mucosal homeostasis and inflammation and may represent a candidate therapeutic target for chronic inflammatory conditions of the bowel.

Reduced monocyte and macrophage TNFSF15/TL1A expression is associated with susceptibility to inflammatory bowel disease

Chronic inflammation in inflammatory bowel disease (IBD) results from a breakdown of intestinal immune homeostasis and compromise of the intestinal barrier. Genome-wide association studies have identified over 200 genetic loci associated with risk for IBD, but the functional mechanisms of most of these genetic variants remain unknown. Polymorphisms at the TNFSF15 locus, which encodes the TNF superfamily cytokine commonly known as TL1A, are associated with susceptibility to IBD in multiple ethnic groups. In a wide variety of murine models of inflammation including models of IBD, TNFSF15 promotes immunopathology by signaling through its receptor DR3. Such evidence has led to the hypothesis that expression of this lymphocyte costimulatory cytokine increases risk for IBD. In contrast, here we show that the IBD-risk haplotype at TNFSF15 is associated with decreased expression of the gene by peripheral blood monocytes in both healthy volunteers and IBD patients. This association persists under various stimulation conditions at both the RNA and protein levels and is maintained after macrophage differentiation. Utilizing a "recall-by-genotype" bioresource for allele-specific expression measurements in a functional fine-mapping assay, we localize the polymorphism controlling TNFSF15 expression to the regulatory region upstream of the gene. Through a T cell costimulation assay, we demonstrate that genetically regulated TNFSF15 has functional relevance. These findings indicate that genetically enhanced expression of TNFSF15 in specific cell types may confer protection against the development of IBD.

The Marine Dinoflagellate Alexandrium andersoni Induces Cell Death in Lung and Colorectal Tumor Cell Lines

Dinoflagellates are one of the most important components in marine phytoplankton, second only to diatoms as primary producers. Dinoflagellates have also been reported to produce bioactive secondary metabolites such as polyethers and macrolides with potential applications as pharmaceuticals. Here, we tested the effect of the organic extract and its related enriched extracts from solid-phase extraction (SPE) of a strain of the dinoflagellate Alexandrium andersoni. We found that the SPE extracts induced high cytotoxicity towards two cancer cell lines (A549 lung cancer and HT29 colorectal cancer) without affecting normal cell viability. The SPE extracts activated two different cell death pathways in the two tumor cell lines at the gene expression level, with the involvement of the major mediators of the tumor necrosis factor (TNF) cell signaling cascade. In HT29 cells, in addition to TNF activation, a death signaling pathway in response to DNA damage was also induced. This is an interesting finding since the HT29 cell line is highly aggressive since it is p53 gene-defect and this DNA instability renders this type of cancer very resistant towards all chemotherapeutic agents. Another significant result is that two distinct chemical fractions were selectively able to induce different and specific responses on the two different tumor cells treated.

Elucidation of Gene Expression Patterns in the Brain after Spinal Cord Injury

Spinal cord injury (SCI) is a devastating neurological disease. The pathophysiological mechanisms of SCI have been reported to be relevant to central nervous system injury such as brain injury. In this study, gene expression of the brain after SCI was elucidated using transcriptome analysis to characterize the temporal changes in global gene expression patterns in a SCI mouse model. Subjects were randomly classified into 3 groups: sham control, acute (3 h post-injury), and subacute (2 wk post-injury) groups. We sought to confirm the genes differentially expressed between post-injured groups and sham control group. Therefore, we performed transcriptome analysis to investigate the enriched pathways associated with pathophysiology of the brain after SCI using Database for Annotation Visualization, and Integrated Discovery (DAVID), which yielded Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway. Following enriched pathways were found in the brain: oxidative phosphorylation pathway; inflammatory response pathways—cytokine–cytokine receptor interaction and chemokine signaling pathway; and endoplasmic reticulum (ER) stress-related pathways—antigen processing and presentation and mitogen-activated protein kinase signaling pathway. Oxidative phosphorylation pathway was identified at acute phase, while inflammation response and ER stress-related pathways were identified at subacute phase. Since the following pathways—oxidative phosphorylation pathway, inflammatory response pathways, and ER stress-related pathways—have been well known in the SCI, we suggested a link between SCI and brain injury. These mechanisms provide valuable reference data for better understanding pathophysiological processes in the brain after SCI.

An anti-TL1A antibody for the treatment of asthma and inflammatory bowel disease

TL1A is an attractive therapeutic target for the treatment of mucosal inflammation associated with inflammatory bowel disease (IBD) and asthma. Blockade of the TL1A pathway has been shown to reduce inflammatory responses while leaving baseline immunity intact, and to be beneficial in animal models of colitis and asthma. Given the therapeutic potential of blocking this pathway in IBD and asthma, we developed C03V, a human antibody that binds with high affinity to soluble and membrane-bound TL1A. In an assay measuring apoptosis induced by exogenous TL1A, C03V was 43-fold more potent than the next most potent anti-TL1A antibody analyzed. C03V also potently inhibited endogenous TL1A activity in a primary cell-based assay. This potency was linked to the C03V-binding epitope on TL1A, encompassing the residue R32. This residue is critical for the binding of TL1A to its signaling receptor DR3 but not to its decoy receptor DcR3, and explains why C03V inhibited TL1A-DR3 binding to a much greater extent than TL1A-DcR3 binding. This characteristic may be advantageous to preserve some of the homeostatic functions of DcR3, such as TL1A antagonism. In colitis models, C03V significantly ameliorated microscopic, macroscopic and clinical aspects of disease pathology, and in an asthma model it significantly reduced airways inflammation. Notable in both types of disease model was the reduction in fibrosis observed after C03V treatment. C03V has the potential to address unmet medical needs in asthma and IBD.

Death Receptor 3 Signaling Controls the Balance between Regulatory and Effector Lymphocytes in SAMP1/YitFc Mice with Crohn's Disease-Like Ileitis

Death receptor 3 (DR3), a member of the tumor necrosis factor receptor (TNFR) superfamily, has been implicated in regulating T-helper type-1 (TH1), type-2 (TH2), and type-17 (TH17) responses as well as regulatory T cell (Treg) and innate lymphoid cell (ILC) functions during immune-mediated diseases. However, the role of DR3 in controlling lymphocyte functions in inflammatory bowel disease (IBD) is not fully understood. Recent studies have shown that activation of DR3 signaling modulates Treg expansion suggesting that stimulation of DR3 represents a potential therapeutic target in human inflammatory diseases, including Crohn's disease (CD). In this study, we tested a specific DR3 agonistic antibody (4C12) in SAMP1/YitFc (SAMP) mice with CD-like ileitis. Interestingly, treatment with 4C12 prior to disease manifestation markedly worsened the severity of ileitis in SAMP mice despite an increase in FoxP3+ lymphocytes in mesenteric lymph node (MLN) and small-intestinal lamina propria (LP) cells. Disease exacerbation was dominated by overproduction of both TH1 and TH2 cytokines and associated with expansion of dysfunctional CD25-FoxP3+ and ILC group 1 (ILC1) cells. These effects were accompanied by a reduction in CD25+FoxP3+ and ILC group 3 (ILC3) cells. By comparison, genetic deletion of DR3 effectively reversed the inflammatory phenotype in SAMP mice by promoting the expansion of CD25+FoxP3+ over CD25-FoxP3+ cells and the production of IL-10 protein. Collectively, our data demonstrate that DR3 signaling modulates a multicellular network, encompassing Tregs, T effectors, and ILCs, governing disease development and progression in SAMP mice with CD-like ileitis. Manipulating DR3 signaling toward the restoration of the balance between protective and inflammatory lymphocytes may represent a novel and targeted therapeutic modality for patients with CD.

A variant of death-receptor 3 associated with rheumatoid arthritis interferes with apoptosis-induction of T cell

Rheumatoid arthritis (RA) is a chronic polyarthritis of unknown etiology. To unravel the molecular mechanisms in RA, we performed targeted DNA sequencing analysis of patients with RA. This analysis identified a variant of the death receptor 3 (DR3) gene, a member of the family of apoptosis-inducing Fas genes, which contains four single-nucleotide polymorphisms (SNPs) and a 14-nucleotide deletion within exon 5 and intron 5. We found that the deletion causes the binding of splicing regulatory proteins to DR3 pre-mRNA intron 5, resulting in a portion of intron 5 becoming part of the coding sequence, thereby generating a premature stop codon. We also found that this truncated DR3 protein product lacks the death domain and forms a heterotrimer complex with wildtype DR3 that dominant-negatively inhibits ligand-induced apoptosis in lymphocytes. Myelocytes from transgenic mice expressing the human DR3 variant produced soluble truncated DR3, forming a complex with TNF-like ligand 1A (TL1A), which inhibited apoptosis induction. In summary, our results reveal that a DR3 splice variant that interferes with ligand-induced T cell responses and apoptosis may contribute to RA pathogenesis.

The TNF Receptor Superfamily in Co-stimulating and Co-inhibitory Responses

Cytokines related to tumor necrosis factor (TNF) provide a communication network essential for coordinating multiple cell types into an effective host defense system against pathogens and malignant cells. The pathways controlled by the TNF superfamily differentiate both innate and adaptive immune cells and modulate stromal cells into microenvironments conducive to host defenses. Members of the TNF receptor superfamily activate diverse cellular functions from the production of type 1 interferons to the modulation of survival of antigen-activated T cells. Here, we focus attention on the subset of TNF superfamily receptors encoded in the immune response locus in chromosomal region 1p36. Recent studies have revealed that these receptors use diverse mechanisms to either co-stimulate or restrict immune responses. Translation of the fundamental mechanisms of TNF superfamily is leading to the design of therapeutics that can alter pathogenic processes in several autoimmune diseases or promote immunity to tumors.

Death Receptor 3 regulates distinct pathological attributes of acute versus chronic murine allergic lung inflammation

The Death Receptor 3 (DR3)/Tumour Necrosis Factor-like cytokine 1A (TL1A) axis stimulates effector T cells and type 2 innate lymphocytes (ILC2) that trigger cytokine release and drive disease pathology in several inflammatory and autoimmune diseases, including murine models of acute allergic lung inflammation (ALI). The aim of this study was to elucidate the role of DR3 in chronic ALI compared to acute ALI, using mice genetically deficient in the DR3 gene (DR3^ko). Results showed DR3 expression in the lungs of wild-type mice was up-regulated following induction of acute ALI and this increased expression was maintained in chronic disease. DR3^ko mice were resistant to cellular accumulation within the alveolar passages in acute, but not chronic ALI. However, DR3^ko mice displayed reduced immuno-histopathology and goblet cell hyperplasia; hallmarks of the asthmatic phenotype; in chronic, but not acute ALI. These data suggest DR3 is a potential therapeutic target, involved in temporally distinct aspects of ALI progression and pathogenesis.

Increased Potency of a Bi-specific TL1A-ADAM17 (TACE) Inhibitor by Cell Surface Targeting

Inflammatory bowel disease (IBD) is a multifactorial disease characterized by the dysregulated activity of many pro-inflammatory factors. Thus, bi-specific inhibitors for the simultaneous inhibition of two pro-inflammatory factors can exhibit high therapeutic potential. Here, we developed a novel bi-specific inhibitor targeting the TL1A cytokine and ADAM17/TACE metalloprotease. Biochemical analysis of the bi-specific inhibitor revealed high TL1A binding and TACE inhibition that is similar to the two respective mono-specific inhibitors. Interestingly, cell based assays for TL1A inhibition revealed strong synergism between the inhibitory domains showing an up to 80-fold increase in potency of the bi-specific inhibitor. The dramatic increase in potency is associated with binding to cell membranes through the TACE inhibitory domain leading to increased concentration of the inhibitor on the cell surface. Our study highlights the high potential of the simultaneous targeting of cell surface metalloprotease (TACE) and soluble pro-inflammatory cytokine (TL1A) as a potential therapeutic approach in IBD.

CCL3 and MMP-9 are induced by TL1A during death receptor 3 (TNFRSF25)-dependent osteoclast function and systemic bone loss

Reduced bone density and secondary osteoporosis, resulting in increased risk of fracture, is a significant complicating factor in the inflammatory arthritides. While the exact etiology of systemic bone loss is not fully elucidated, recent insights into the tumor necrosis factor super family (TNFSF) revealed a potential role for death receptor 3 (DR3/TNFRSF25) and one of its ligands, TNF-like protein 1A (TL1A/TNFSF15). The mechanisms by which DR3/TL1A signalling modulates bone loss are unclear. We investigated the effect of DR3/TL1A signalling upon osteoclast-dependent chemokine and MMP production to unravel novel mechanisms whereby this pathway regulates OC formation and OC-dependent bone resorption. Collagen induced arthritis (CIA) was established in DR3^wt and DR3^ko mice, joints were sectioned and analysed histologically for bone damage while systemic trabecular bone loss distal to the affected joints was compared by micro-CT. Ablation of DR3 protected DBA/1 mice against the development and progression of CIA. In DR3^ko, joints of the ankle and mid-foot were almost free of bone erosions and long bones of mice with CIA were protected against systemic trabecular bone loss. In vitro, expression of DR3 was confirmed on primary human CD14⁺ osteoclast precursors by flow cytometry. These cells were treated with TL1A in osteoclast differentiation medium and TRAP⁺ osteoclasts, bone resorption, levels of osteoclast-associated chemokines (CCL3, CCL2 and CXCL8) and MMP-9 measured. TL1A intensified human osteoclast differentiation and bone resorption and increased osteoclast-associated production of CCL3 and MMP-9. Our data reveals the DR3 pathway as an attractive therapeutic target to combat adverse bone pathology associated with inflammatory arthritis. We demonstrate that DR3 is critical in the pathogenesis of murine CIA and associated secondary osteoporosis. Furthermore, we identify a novel mechanism by which the DR3/TL1A pathway directly enhances human OC formation and resorptive activity, controlling expression and activation of CCL3 and MMP-9.

Directed evolution of a soluble human DR3 receptor for the inhibition of TL1A induced cytokine secretion

TNF-like 1A (TL1A) is a cytokine belonging to the TNF superfamily that promotes inflammation in autoimmune diseases. Inhibiting the interaction of TL1A with the endogenous death-domain receptor 3 (DR3) offers a therapeutic approach for treating TL1A-induced autoimmune diseases. Here, we generated improved DR3 variants showing increased TL1A binding affinity and stability using a directed evolution approach. Given the high cysteine content and post-translational modification of DR3, we employed yeast surface display and expression in mammalian cell lines for screening, expression and characterization of improved DR3 variants. A cell-based assay performed with the human TF-1 cell line and CD4⁺ T cells showed that two improved DR3 mutants efficiently inhibited TL1A-induced cell death and secretion of IFN-γ, respectively. These DR3 mutants can be used as drug candidates for the treatment of inflammatory bowel diseases and for other autoimmune diseases, including rheumatic arthritis and asthma.

Beyond TNF: TNF superfamily cytokines as targets for the treatment of rheumatic diseases

TNF blockers are highly efficacious at dampening inflammation and reducing symptoms in rheumatic diseases such as rheumatoid arthritis, psoriatic arthritis and ankylosing spondylitis, and also in nonrheumatic syndromes such as inflammatory bowel disease. As TNF belongs to a superfamily of 19 structurally related proteins that have both proinflammatory and anti-inflammatory activity, reagents that disrupt the interaction between proinflammatory TNF family cytokines and their receptors, or agonize the anti-inflammatory receptors, are being considered for the treatment of rheumatic diseases. Biologic agents that block B cell activating factor (BAFF) and receptor activator of nuclear factor-κB ligand (RANKL) have been approved for the treatment of systemic lupus erythematosus and osteoporosis, respectively. In this Review, we focus on additional members of the TNF superfamily that could be relevant for the pathogenesis of rheumatic disease, including those that can strongly promote activity of immune cells or increase activity of tissue cells, as well as those that promote death pathways and might limit inflammation. We examine preclinical mouse and human data linking these molecules to the control of damage in the joints, muscle, bone or other tissues, and discuss their potential as targets for future therapy of rheumatic diseases.

The TNF family member TL1A induces IL-22 secretion in committed human Th17 cells via IL-9 induction

TL1A contributes to the pathogenesis of several chronic inflammatory diseases, including those of the bowel by enhancing TH1, TH17, and TH2 responses. TL1A mediates a strong costimulation of these TH subsets, particularly of mucosal CCR9+ T cells. However, the signaling pathways that TL1A induces in different TH subsets are incompletely understood. We investigated the function of TL1A on human TH17 cells. TL1A, together with TGF-β, IL-6, and IL-23, enhanced the secretion of IL-17 and IFN-γ from human CD4+ memory T cells. TL1A induced expression of the transcription factors BATF and T-bet that correlated with the secretion of IL-17 and IFN-γ. In contrast, TL1A alone induced high levels of IL-22 in memory CD4+ T cells and committed TH17 cells. However, TL1A did not enhance expression of IL-17A in TH17 cells. Expression of the transcription factor aryl hydrocarbon receptor, which regulates the expression of IL-22 was not affected by TL1A. Transcriptome analysis of TH17 cells revealed increased expression of IL-9 in response to TL1A. Blocking IL-9 receptor antibodies abrogated TL1A-induced IL-22 secretion. Furthermore, TL1A increased IL-9 production by peripheral TH17 cells isolated from patients with Crohn's disease. These data suggest that TL1A differentially induces expression of TH17 effector cytokines IL-17, -9, and -22 and provides a potential target for therapeutic intervention in TH17-driven chronic inflammatory diseases.

Effect of infusion of monoclonal antibodies to tumour necrosis factor-receptor super family 25 on graft rejection in allo-immune mice receiving autologous marrow transplantation

Significant barriers to transplantation exist for individuals who are pre-sensitized to donor antigen and have high titres of donor-reactive antibody. We report the effect of autologous bone marrow transplantation (BMTx) after myeloablation in pre-sensitized mice along with the use of monoclonal antibodies (mAbs) to tumour necrosis factor-receptor super family 25 (TNFRSF25), expressed on regulatory T (Treg) cells. C57BL/6 mice, which had been sensitized earlier with BALB/c skin allografts, received secondary BALB/c grafts after the primary grafts had been rejected. Subsequently, recipient mice underwent myeloablation with cyclophosphamide and busulphan and were injected with T-cell-depleted bone marrow from CD45.1 congenic donors (BMTx). Recipient mice underwent immunosuppressive treatment with rapamycin. A subgroup of mice was also treated with mAbs to TNFRSF25. Control mice were pre-sensitized mice that received cyclophosphamide and busulphan followed by rapamycin. BMTx-treated mice had significantly prolonged skin graft survival versus control mice. These mice also showed attenuated donor-specific mixed lymphocyte co-culture responses relative to controls, increased splenic Treg cells and markedly diminished serum anti-donor IgG. Infusion of anti-TNFRSF25 mAbs further augmented graft survival and increased graft-infiltrating Treg cells. These mAbs also expanded murine and human Treg cells in vitro with the capacity to attenuate mixed lymphocyte co-cultures using fresh peripheral blood mononuclear cells. Overall, this study delineates the roles of autologous BMTx and anti-TNFRSF25 mAbs in expanding Treg cells and attenuating alloimmune responses in pre-sensitized mice.

TNF superfamily cytokines in the promotion of Th9 differentiation and immunopathology

The tumor necrosis factor (TNF) receptors and their corresponding cytokine ligands have been implicated in many aspects of the biology of immune functions. TNF receptors have key roles during various stages of T cell homeostasis. Many of them can co-stimulate lymphocyte proliferation and cytokine production. Additionally, several TNF cytokines can regulate T cell differentiation, including promoting Th1, Th2, Th17, and more recently the newly described Th9 subset. Four TNF family cytokines have been identified as regulators for IL-9 production by T cells. OX40L, TL1A, and GITRL can promote Th9 formation but can also divert iTreg into Th9, while 4-1BBL seems to inhibit IL-9 production from iTreg and has not been studied for its ability to promote Th9 generation. Regulation of IL-9 production by TNF family cytokines has repercussions in vivo, including enhancement of anti-tumor immunity and immunopathology in allergic lung and ocular inflammation. Regulating T cell production of IL-9 through blockade or agonism of TNF family cytokine receptors may be a therapeutic strategy for autoimmune and allergic diseases and in tumor.