The human OX40/gp34 system directly mediates adhesion of activated T cells to vascular endothelial cells

Regulatory T cell and endothelial cell crosstalk

Regulatory T (Treg) cells have a central role in the maintenance of immune surveillance and tolerance. They can migrate from lymphoid organs to blood and then into tissues and egress from tissues into draining lymph nodes. Specialized endothelial cells of blood and lymphatic vessels are the key gatekeepers for these processes. Treg cells that transmigrate across single-cell layers of endothelial cells engage in bidirectional crosstalk with these cells and regulate vascular permeability by promoting structural modifications of blood and lymphatic endothelial cells. In turn, blood and lymphatic endothelial cells can modulate Treg cell recirculation and residency. Here, we discuss recent insights into the cellular and molecular mechanisms of the crosstalk between Treg cells and endothelial cells and explore potential therapeutic strategies to target these interactions in autoimmunity, transplantation and cancer.

The Role of OX40-OX40L Axis in the Pathogenesis of Atopic Dermatitis

OX40 is a co-stimulatory immune checkpoint molecule that promotes the activation and the effector function of T lymphocytes through interaction with its ligand (OX40L) on antigen-presenting cells. OX40-OX40L axis plays a crucial role in Th1 and Th2 cell expansion, particularly during the late phases or long-lasting response. Atopic dermatitis is characterized by an immune dysregulation of Th2 activity and by an overproduction of proinflammatory cytokines such as interleukin (IL)-4 and IL-13. Other molecules involved in its pathogenesis include thymic stromal lymphopoietin, IL-33, and IL-25, which contribute to the promotion of OX40L expression on dendritic cells. Lesional skin in atopic dermatitis exhibits a higher level of OX40L+-presenting cells compared with other dermatologic diseases or normal skin. Recent clinical trials using antagonizing anti-OX40 or anti-OX40L antibodies have shown symptom improvement and cutaneous manifestation alleviation in patients with atopic dermatitis. These findings suggest the relevance of the OX40-OX40L axis in atopic dermatitis pathogenesis.

Monoclonal antibodies for moderate-to-severe atopic dermatitis: a look at phase III and beyond

INTRODUCTION

The understanding of atopic dermatitis (AD) pathogenesis has rapidly expanded in recent years, catalyzing the development of new targeted monoclonal antibody treatments for AD.

AREAS COVERED

This review aims to summarize the latest clinical and molecular data about monoclonal antibodies that are in later stages of development for AD, either in Phase 3 trials or in the pharmacopoeia for up to 5 years, highlighting the biologic underpinning of each drug's mechanism of action and the potential modulation of the AD immune profile.

EXPERT OPINION

The therapeutic pipeline of AD treatments is speedily progressing, introducing the potential for a personalized medical approach in the near future. Understanding how targeting pathogenic players in AD modifies disease progression and symptomatology is key in improving therapeutic choices for patients and identifying ideal patient candidates.

An OX-Tra'Ordinary Tale: The Role of OX40 and OX40L in Atopic Dermatitis

The transmembrane glycoprotein OX40 receptor (OX40) and its ligand, OX40L, are instrumental modulators of the adaptive immune response in humans. OX40 functions as a costimulatory molecule that promotes T cell activation, differentiation, and survival through ligation with OX40L. T cells play an integral role in the pathogenesis of several inflammatory skin conditions, including atopic dermatitis (AD). In particular, T helper 2 (TH2) cells strongly contribute to AD pathogenesis via the production of cytokines associated with type 2 inflammation (e.g., IL-4, IL-5, IL-13, and IL-31) that lead to skin barrier dysfunction and pruritus. The OX40-OX40L interaction also promotes the activation and proliferation of other T helper cell populations (e.g., TH1, TH22, and TH17), and AD patients have demonstrated higher levels of OX40 expression on peripheral blood mononuclear cells than healthy controls. As such, the OX40-OX40L pathway is a potential target for AD treatment. Novel therapies targeting the OX40 pathway are currently in development, several of which have demonstrated promising safety and efficacy results in patients with moderate-to-severe AD. Herein, we review the function of OX40 and the OX40-OX40L signaling pathway, their role in AD pathogenesis, and emerging therapies targeting OX40-OX40L that may offer insights into the future of AD management.

Engaging stimulatory immune checkpoint interactions in the tumour immune microenvironment of primary liver cancers - how to push the gas after having released the brake

Hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA) are the first and second most common primary liver cancer (PLC). For decades, systemic therapies consisting of tyrosine kinase inhibitors (TKIs) or chemotherapy have formed the cornerstone of treating advanced-stage HCC and CCA, respectively. More recently, immunotherapy using immune checkpoint inhibition (ICI) has shown anti-tumour reactivity in some patients. The combination regimen of anti-PD-L1 and anti-VEGF antibodies has been approved as new first-line treatment of advanced-stage HCC. Furthermore, gemcibatine plus cisplatin (GEMCIS) with an anti-PD-L1 antibody is awaiting global approval for the treatment of advanced-stage CCA. As effective anti-tumour reactivity using ICI is achieved in a minor subset of both HCC and CCA patients only, alternative immune strategies to sensitise the tumour microenvironment of PLC are waited for. Here we discuss immune checkpoint stimulation (ICS) as additional tool to enhance anti-tumour reactivity. Up-to-date information on the clinical application of ICS in onco-immunology is provided. This review provides a rationale of the application of next-generation ICS either alone or in combination regimen to potentially enhance anti-tumour reactivity in PLC patients.

OX40 (CD134) Expression on T Regulatory Cells Is Related to Serious Hypertensive Disorders in Pregnancy

Hypertension is one of the leading causes of morbidity and mortality among women related to pregnancy, childbirth and the postpartum period. The pathogenesis of gestational hypertension is complex and still not fully understood. The aim of this study was to assess the population of circulating CD4+CD25+FoxP3+ cells and its differentiation in terms of OX40 expression in two forms of hypertension: isolated hypertension developing after the 20th week of pregnancy and pre-eclampsia. The study included a group of 60 patients with hypertension and 48 healthy controls. The analysis of the percentage of Tregs was performed by flow cytometry. There was no difference in the percentage of peripheral lymphocytes between the groups. In the group of women with preeclampsia compared to the group with gestational hypertension, significantly higher percentages of CD4+CD25+FoxP3+ cells (p = 0.03) and percentages of CD4+CD25+FoxP3+ cells expressing the OX40 antigen (p = 0.001) were observed. OX40 expression on Tregs seems to be related to more serious type of hypertensive disorders in pregnant women.

Comparison of OX40 expression in patients with multiple sclerosis and neuromyelitis optica as an approach to diagnosis

BACKGROUND

Previous studies have shown that CD134 (OX40) co-stimulation is involved in the pathogenesis of experimental autoimmune encephalomyelitis (EAE) models and the antigen is expressed within multiple sclerosis lesions in humans. OX40 (CD134) is thought to be a secondary co-stimulatory immune checkpoint molecule that is expressed by T cells. This study aimed to evaluate the mRNA expression of OX40 and its serum levels in the peripheral blood of patients with Multiple Sclerosis (MS) or Neuromyelitis Optica (NMO).

METHODS

Patients with MS (n = 60), NMO (n = 20), and 20 healthy subjects were recruited from Sina Hospital, Tehran, Iran. The diagnoses were confirmed by a specialist in clinical neurology. Peripheral venous blood was obtained from all subjects, and mRNA quantification of OX40 was conducted using real-time PCR. Serum samples were also obtained and the concentration of OX40 was determined using an enzyme-linked immunosorbent assay (ELISA).

RESULTS

There was a significant correlation between the mRNA expression and serum levels of OX40 and disability as assessed using the expanded disability status scale (EDSS) in the patients with MS, but not in the patients with NMO. Expression of OX40 mRNA was significantly higher in the peripheral blood of MS patients compared to healthy individuals and NMO patients (*P < 0.05). In addition, serum OX40 concentrations were also significantly higher in patients with MS patients compared with healthy subjects (9.08 ± 2.48 vs. 1.49 ± 0.54 ng/ml; P = 0.041).

CONCLUSIONS

It appears that an increased expression of OX40 may be associated with the hyperactivation of T cells in patients with MS, and this may play a role in the pathogenesis of the disease.

Diffusing Alpha-Emitters Radiation Therapy Promotes a Proimmunogenic Tumor Microenvironment and Synergizes With Programmed Cell Death Protein 1 Blockade

PURPOSE

Diffusing alpha-emitters Radiation Therapy (DaRT) releases alpha-emitting atoms into the tumor microenvironment. The treatment effectively ablates human and mice xenografts and shows 100% response rates in skin or head and neck squamous cell carcinoma patients. DaRT induces specific and systemic antitumor immune activation and synergizes with immune stimulation and modulation in mice. Here, the transcriptional profile activated by DaRT, and its potential to enhance responsiveness to immune checkpoint inhibition by programmed cell death protein 1 (PD-1) blockade were studied.

METHODS AND MATERIALS

Squamous cell carcinoma tumor- bearing BALB/C mice were treated with DaRT or inert seeds in combination with anti-PD-1 (aPD-1) or IgG control antibody. Sixteen days after seed insertion, tumors and spleens were subjected to immunophenotyping and immunohistochemical staining. Combination of DaRT and aPD-1 was tested for efficacy. Gene expression analysis was performed on mRNA extracted from tumors 7 days after DaRT or inert insertion using Nanostring PanCancer-IO-360 panel, and tumors and spleens were subjected to flow cytometry analysis.

RESULTS

DaRT in combination with aPD-1 delayed tumor development, induced CD3 and CD8 lymphocytes infiltration more efficiently than either monotherapy. The combined treatment reduced splenic polymorphonuclear myeloid derived suppressor cells more than aPD-1 therapy or control. Granzyme B release in the tumor was increased only in the combinational treatment and was correlated with T-lymphocyte infiltration. Gene expression and gene set enrichment analysis of mRNA levels 7 days after DaRT insertion indicated that DaRT upregulated apoptosis, p53 signaling, G1/S-related arrest, interferon signaling and myeloid related transcription, while downregulating DNA repair, cell proliferation, and notch-related transcription. Flow cytometry showed that DaRT increased dendritic cells activation and led to changes in MDSCs distribution.

CONCLUSIONS

DaRT promotes a "hot" tumor microenvironment and changes in immune suppression that lead to a potentiation of aPD-1 blockade induced effector T cell function and improved treatment efficacy. This study provides rationale for investigating DaRT and aPD-1 combination in patients with squamous cell carcinoma.

Targeting immune checkpoints in anti-neutrophil cytoplasmic antibodies associated vasculitis: the potential therapeutic targets in the future

Anti-neutrophil cytoplasmic autoantibodies (ANCA) associated vasculitis (AAV) is a necrotizing vasculitis mainly involving small blood vessels. It is demonstrated that T cells are important in the pathogenesis of AAV, including regulatory T cells (Treg) and helper T cells (Th), especially Th2, Th17, and follicular Th cells (Tfh). In addition, the exhaustion of T cells predicted the favorable prognosis of AAV. The immune checkpoints (ICs) consist of a group of co-stimulatory and co-inhibitory molecules expressed on the surface of T cells, which maintains a balance between the activation and exhaustion of T cells. CD28, inducible T-cell co-stimulator (ICOS), OX40, CD40L, glucocorticoid induced tumor necrosis factor receptor (GITR), and CD137 are the common co-stimulatory molecules, while the programmed cell death 1 (PD-1), cytotoxic T lymphocyte-associated molecule 4 (CTLA-4), T cell immunoglobulin (Ig) and mucin domain-containing protein 3 (TIM-3), B and T lymphocyte attenuator (BTLA), V-domain Ig suppressor of T cell activation (VISTA), T-cell Ig and ITIM domain (TIGIT), CD200, and lymphocyte activation gene 3 (LAG-3) belong to co-inhibitory molecules. If this balance was disrupted and the activation of T cells was increased, autoimmune diseases (AIDs) might be induced. Even in the treatment of malignant tumors, activation of T cells by immune checkpoint inhibitors (ICIs) may result in AIDs known as rheumatic immune-related adverse events (Rh-irAEs), suggesting the importance of ICs in AIDs. In this review, we summarized the features of AAV induced by immunotherapy using ICIs in patients with malignant tumors, and then reviewed the biological characteristics of different ICs. Our aim was to explore potential targets in ICs for future treatment of AAV.

Emerging Trends in Immunotherapy for Cancer

Recent advances in cancer immunology have enabled the discovery of promising immunotherapies for various malignancies that have shifted the cancer treatment paradigm. The innovative research and clinical advancements of immunotherapy approaches have prolonged the survival of patients with relapsed or refractory metastatic cancers. Since the U.S. FDA approved the first immune checkpoint inhibitor in 2011, the field of cancer immunotherapy has grown exponentially. Multiple therapeutic approaches or agents to manipulate different aspects of the immune system are currently in development. These include cancer vaccines, adoptive cell therapies (such as CAR-T or NK cell therapy), monoclonal antibodies, cytokine therapies, oncolytic viruses, and inhibitors targeting immune checkpoints that have demonstrated promising clinical efficacy. Multiple immunotherapeutic approaches have been approved for specific cancer treatments, while others are currently in preclinical and clinical trial stages. Given the success of immunotherapy, there has been a tremendous thrust to improve the clinical efficacy of various agents and strategies implemented so far. Here, we present a comprehensive overview of the development and clinical implementation of various immunotherapy approaches currently being used to treat cancer. We also highlight the latest developments, emerging trends, limitations, and future promises of cancer immunotherapy.

Fasting renders immunotherapy effective against low-immunogenic breast cancer while reducing side effects

Immunotherapy is improving the prognosis and survival of cancer patients, but despite encouraging outcomes in different cancers, the majority of tumors are resistant to it, and the immunotherapy combinations are often accompanied by severe side effects. Here, we show that a periodic fasting-mimicking diet (FMD) can act on the tumor microenvironment and increase the efficacy of immunotherapy (anti-PD-L1 and anti-OX40) against the poorly immunogenic triple-negative breast tumors (TNBCs) by expanding early exhausted effector T cells, switching the cancer metabolism from glycolytic to respiratory, and reducing collagen deposition. Furthermore, FMD reduces the occurrence of immune-related adverse events (irAEs) by preventing the hyperactivation of the immune response. These results indicate that FMD cycles have the potential to enhance the efficacy of anti-cancer immune responses, expand the portion of tumors sensitive to immunotherapy, and reduce its side effects.

Current Clinical Trial Landscape of OX40 Agonists

PURPOSE OF REVIEW

Despite the efficacy of immune checkpoint blockade (ICB) immunotherapy, most cancer patients still develop progressive disease necessitating additional treatment options. One approach is ligation of the OX40 (CD134) costimulatory receptor which promotes T cell activation, effector function, and the generation of long-lived memory cells.

RECENT FINDINGS

Numerous preclinical studies have demonstrated that OX40 agonists alone or in combination with ICB (e.g., anti-PD-1, anti-PD-L1, and anti-CTLA-4) augment anti-tumor immunity. In this review, we discuss the impact of OX40 agonists on T cell function and the therapeutic potential of OX40 agonists alone or in conjunction with ICB for patients with advanced malignancies.

OX40L Inhibition Suppresses KLH‐driven Immune Responses in Healthy Volunteers: A Randomized Controlled Trial Demonstrating Proof‐of‐Pharmacology for KY1005

The safety, tolerability, immunogenicity, and pharmacokinetic (PK) profile of an anti‐OX40L monoclonal antibody (KY1005, currently amlitelimab) were evaluated. Pharmacodynamic (PD) effects were explored using keyhole limpet hemocyanin (KLH) and tetanus toxoid (TT) immunizations. Sixty‐four healthy male subjects (26.5 ± 6.0 years) were randomized to single doses of 0.006, 0.018, or 0.05 mg/kg, or multiple doses of 0.15, 0.45, 1.35, 4, or 12 mg/kg KY1005, or placebo (6:2). Serum KY1005 concentrations were measured. Antibody responses upon KLH and TT immunizations and skin response upon intradermal KLH administration were performed. PD data were analyzed using repeated measures analysis of covariances (ANCOVAs) and post hoc exposure‐response modeling. No serious adverse events occurred and all adverse events were temporary and of mild or moderate severity. A nonlinear increase in mean serum KY1005 concentrations was observed (median time to maximum concentration (T_max) ~ 4 hours, geometric mean terminal half‐life (t½) ~ 24 days). Cutaneous blood perfusion (estimated difference (ED) −13.4 arbitrary unit (AU), 95% confidence interval (CI) −23.0 AU to −3.8 AU) and erythema quantified as average redness (ED −0.23 AU, 95% CI −0.35 AU to −0.11 AU) decreased after KY1005 treatment at doses of 0.45 mg/kg and above. Exposure‐response analysis displayed a statistically significant treatment effect on anti‐KLH antibody titers (IgG maximum effect (E_max) −0.58 AU, 95% CI −1.10 AU to −0.06 AU) and skin response (erythema E_max −0.20 AU, 95% CI −0.29 AU to −0.11 AU). Administration of KY1005 demonstrated an acceptable safety and tolerability profile and PK analyses displayed a nonlinear profile of KY1005. Despite the observed variability, skin challenge response after KY1005 treatment indicated pharmacological activity of KY1005. Therefore, KY1005 shows potential as a novel pharmacological treatment in immune‐mediated disorders.

Radiation Augments the Local Anti-Tumor Effect of In Situ Vaccine With CpG-Oligodeoxynucleotides and Anti-OX40 in Immunologically Cold Tumor Models

Introduction

Combining CpG oligodeoxynucleotides with anti-OX40 agonist antibody (CpG+OX40) is able to generate an effective in situ vaccine in some tumor models, including the A20 lymphoma model. Immunologically "cold" tumors, which are typically less responsive to immunotherapy, are characterized by few tumor infiltrating lymphocytes (TILs), low mutation burden, and limited neoantigen expression. Radiation therapy (RT) can change the tumor microenvironment (TME) of an immunologically "cold" tumor. This study investigated the effect of combining RT with the in situ vaccine CpG+OX40 in immunologically "cold" tumor models.

Methods

Mice bearing flank tumors (A20 lymphoma, B78 melanoma or 4T1 breast cancer) were treated with combinations of local RT, CpG, and/or OX40, and response to treatment was monitored. Flow cytometry and quantitative polymerase chain reaction (qPCR) experiments were conducted to study differences in the TME, secondary lymphoid organs, and immune activation after treatment.

Results

An in situ vaccine regimen of CpG+OX40, which was effective in the A20 model, did not significantly improve tumor response or survival in the "cold" B78 and 4T1 models, as tested here. In both models, treatment with RT prior to CpG+OX40 enabled a local response to this in situ vaccine, significantly improving the anti-tumor response and survival compared to RT alone or CpG+OX40 alone. RT increased OX40 expression on tumor infiltrating CD4+ non-regulatory T cells. RT+CpG+OX40 increased the ratio of tumor-infiltrating effector T cells to T regulatory cells and significantly increased CD4+ and CD8+ T cell activation in the tumor draining lymph node (TDLN) and spleen.

Conclusion

RT significantly improves the local anti-tumor effect of the in situ vaccine CpG+OX40 in immunologically "cold", solid, murine tumor models where RT or CpG+OX40 alone fail to stimulate tumor regression.

Resolving the intertwining of inflammation and fibrosis in human heart failure at single-cell level

Inflammation and fibrosis are intertwined mechanisms fundamentally involved in heart failure. Detailed deciphering gene expression perturbations and cell-cell interactions of leukocytes and non-myocytes is required to understand cell-type-specific pathology in the failing human myocardium. To this end, we performed single-cell RNA sequencing and single T cell receptor sequencing of 200,615 cells in both human dilated cardiomyopathy (DCM) and ischemic cardiomyopathy (ICM) hearts. We sampled both lesion and mild-lesion tissues from each heart to sequentially capture cellular and molecular alterations to different extents of cardiac fibrosis. By which, left (lesion) and right ventricle (mild-lesion) for DCM hearts were harvest while infarcted (lesion) and non-infarcted area (mild-lesion) were dissected from ICM hearts. A novel transcription factor AEBP1 was identified as a crucial cardiac fibrosis regulator in ACTA2⁺ myofibroblasts. Within fibrotic myocardium, an infiltration of a considerable number of leukocytes was witnessed, especially cytotoxic and exhausted CD8⁺ T cells and pro-inflammatory CD4⁺ T cells. Furthermore, a subset of tissue-resident macrophage, CXCL8^hiCCR2⁺HLA-DR^hi macrophage was particularly identified in severely fibrotic area, which interacted with activated endothelial cell via DARC, that potentially facilitate leukocyte recruitment and infiltration in human heart failure.

Immune checkpoint inhibitors: a new landscape for extensive stage small cell lung cancer treatment

Introduction: Landscape of Extensive Stage (ES)-SCLC treatment has been unchanged over the years. Chemotherapy, mostly based on cisplatin and etoposide, remained the standard-of-care for patients with ES-SCLC for almost 40 years. Recently, immune check points inhibitors have emerged marking a turning point for ES-SCLC treatmentAreas covered: Aim of the paper is to discuss ICIs impact on ES-SCLC treatment algorithms, review current clinical trials, and explore future perspectives.Expert opinion: A growing body of evidence supports ICI-containing regimens as a new mainstay of ES-SCLC treatment. Whether subgroups of SCLC patients may have greater survival benefits from ICIs treatment needs to be better defined. Understanding the impact of tumor microenvironment and identifying reliable predictive and/or prognostic biomarkers will be fundamental to move toward a personalized treatment approach leading to improved survival.

Merkel Cell Carcinoma from Molecular Pathology to Novel Therapies

Merkel cell carcinoma (MCC) is an uncommon and highly aggressive skin cancer. It develops mostly within chronically sun-exposed areas of the skin. MCPyV is detected in 60-80% of MCC cases as integrated within the genome and is considered a major risk factor for MCC. Viral negative MCCs have a high mutation burden with a UV damage signature. Aberrations occur in RB1, TP53, and NOTCH genes as well as in the PI3K-AKT-mTOR pathway. MCC is highly immunogenic, but MCC cells are known to evade the host's immune response. Despite the characteristic immunohistological profile of MCC, the diagnosis is challenging, and it should be confirmed by an experienced pathologist. Sentinel lymph node biopsy is considered the most reliable staging tool to identify subclinical nodal disease. Subclinical node metastases are present in about 30-50% of patients with primary MCC. The basis of MCC treatment is surgical excision. MCC is highly radiosensitive. It becomes chemoresistant within a few months. MCC is prone to recurrence. The outcomes in patients with metastatic disease are poor, with a historical 5-year survival of 13.5%. The median progression-free survival is 3-5 months, and the median overall survival is ten months. Currently, immunotherapy has become a standard of care first-line therapy for advanced MCC.

Proteomic profiling of HTLV-1 carriers and ATL patients reveals sTNFR2 as a novel diagnostic biomarker for acute ATL

Adult T-cell leukemia/lymphoma (ATL) is a human T-cell leukemia virus type 1 (HTLV-1)-associated T-cell malignancy with generally poor prognosis. Although only ∼5% of HTLV-1 carriers progress to ATL, early diagnosis is challenging because of the lack of ATL biomarkers. In this study, we analyzed blood plasma profiles of asymptomatic HTLV-1 carriers (ACs); untreated ATL patients, including acute, lymphoma, smoldering, and chronic types; and ATL patients in remission. Through SOMAscan, expression levels of 1305 plasma proteins were analyzed in 85 samples (AC, n = 40; ATL, n = 40; remission, n = 5). Using gene set enrichment analysis and gene ontology, overrepresented pathways in ATL vs AC included angiogenesis, inflammation by cytokines and chemokines, interleukin-6 (IL-6)/JAK/STAT3, and notch signaling. In selecting candidate biomarkers, we focused on soluble tumor necrosis factor 2 (sTNFR2) because of its active role in enriched pathways, extreme significance (Welch's t test P < .00001), high discrimination capacity (area under the curve >0.90), and novelty in ATL research. Quantification of sTNFR2 in 102 plasma samples (AC, n = 30; ATL, n = 68; remission, n = 4) using enzyme-linked immunosorbent assay showed remarkable elevations in acute ATL, at least 10 times those of AC samples, and return of sTNFR2 to AC state levels after achieving remission. Flow cytometry and immunostaining validated the expression of TNFR2 in ATL cells. No correlation between sIL-2 and sTNFR2 levels in acute ATL was found, suggesting the possibility of sTNFR2 as an independent biomarker. Our findings represent the first extensive blood-based proteomic analysis of ATL, suggesting the potential clinical utility of sTNFR2 in diagnosing acute ATL.

Frontline Science: OX40 agonistic antibody reverses immune suppression and improves survival in sepsis

A defining feature of protracted sepsis is development of immunosuppression that is thought to be a major driving force in the morbidity and mortality associated with the syndrome. The immunosuppression that occurs in sepsis is characterized by profound apoptosis-induced depletion of CD4 and CD8 T cells and severely impaired T cell function. OX40, a member of the TNF receptor superfamily, is a positive co-stimulatory molecule expressed on activated T cells. When engaged by OX40 ligand, OX40 stimulates T cell proliferation and shifts the cellular immune phenotype toward TH1 with increased production of cytokines that are essential for control of invading pathogens. The purpose of the present study was to determine if administration of agonistic Ab to OX40 could reverse sepsis-induced immunosuppression, restore T cell function, and improve survival in a clinically relevant animal model of sepsis. The present study demonstrates that OX40 agonistic Ab reversed sepsis-induced impairment of T cell function, increased T cell IFN-γ production, increased the number of immune effector cells, and improved survival in the mouse cecal ligation and puncture model of sepsis. Importantly, OX40 agonistic Ab was not only effective in murine sepsis but also improved T effector cell function in PBMCs from patients with sepsis. The present results provide support for the use of immune adjuvants that target T cell depletion and T cell dysfunction in the therapy of sepsis-induced immunosuppression. In addition to the checkpoint inhibitors anti-PD-1 and anti-PD-L1, OX40 agonistic Ab may be a new therapeutic approach to the treatment of this highly lethal disorder.

Immune Checkpoints: Novel Therapeutic Targets to Attenuate Sepsis-Induced Immunosuppression

Sepsis is a leading cause of death in intensive care units and survivors develop prolonged immunosuppression and a high incidence of recurrent infections. No definitive therapy exists to treat sepsis and physicians rely on supportive care including antibiotics, intravenous fluids, and vasopressors. With the rising incidence of antibiotic resistant microbes, it is becoming increasingly critical to discover novel therapeutics. Sepsis-induced leukocyte dysfunction and immunosuppression is recognized as an important contributor towards increased morbidity and mortality. Pre-clinical and clinical studies show that specific cell surface inhibitory immune checkpoint receptors and ligands including PD-1, PD-L1, CTLA4, BTLA, TIM3, OX40, and 2B4 play important roles in the pathophysiology of sepsis by mediating a fine balance between host immune competency and immunosuppression. Pre-clinical studies targeting the inhibitory effects of these immune checkpoints have demonstrated reversal of leukocyte dysfunction and improved host resistance of infection. Measurement of immune checkpoint expression on peripheral blood leukocytes may serve as a means of stratifying patients to direct individualized therapy. This review focuses on advances in our understanding of the role of immune checkpoints in the host response to infections, and the potential clinical application of therapeutics targeting the inhibitory immune checkpoint pathways for the management of septic patients.

Head-to-head study of oxelumab and adalimumab in a mouse model of ulcerative colitis based on NOD/Scid IL2Rγnull mice reconstituted with human peripheral blood mononuclear cells

This study's aim was to demonstrate that the combination of patient immune profiling and testing in a humanized mouse model of ulcerative colitis (UC) might lead to patient stratification for treatment with oxelumab. First, immunological profiles of UC patients and non-UC donors were analyzed for CD4⁺ T cells expressing OX40 (CD134; also known as TNFRSF4) and CD14⁺ monocytes expressing OX40L (CD252; also known as TNFSF4) by flow cytometric analysis. A significant difference was observed between the groups for CD14⁺ OX40L⁺ (UC: n=11, 85.44±21.17, mean±s.d.; non-UC: n=5, 30.7±34.92; P=0.02), whereas no significant difference was detected for CD4⁺ OX40⁺. CD14⁺ OX40L⁺ monocytes were correlated significantly with T helper 1 and 2 cells. Second, NOD/Scid IL2Rγ null mice were reconstituted with peripheral blood mononuclear cells from UC donors exhibiting elevated levels of OX40L, and the efficacy of oxelumab was compared with that of adalimumab. The clinical, colon and histological scores and the serum concentrations of IL-6, IL-1β and glutamic acid were assessed. Treatment with oxelumab or adalimumab resulted in significantly reduced clinical, colon and histological scores, reduced serum concentrations of IL-6 and reduced frequencies of splenic human effector memory T cells and switched B cells. Comparison of the efficacy of adalimumab and oxelumab by orthogonal partial least squares discrimination analysis revealed that oxelumab was slightly superior to adalimumab; however, elevated serum concentrations of glutamic acid suggested ongoing inflammation. These results suggest that oxelumab addresses the pro-inflammatory arm of inflammation while promoting the remodeling arm and that patients exhibiting elevated levels of OX40L might benefit from treatment with oxelumab.

Summary: The combination of patient profiling and testing in a NOD/Scid IL2Rγ^null mouse model of ulcerative colitis (UC) validates oxelumab as a potential therapeutic in UC.

Cluster Analysis of Early Postnatal Biochemical Markers May Predict Development of Retinopathy of Prematurity

Purpose

Growth factors and inflammatory and angiogenetic proteins are involved in the development of retinopathy of prematurity (ROP). However, no early biochemical markers are in clinical use to predict ROP. By performing cluster analysis of multiple biomarkers, we aimed to determine patient groups with high and low risk for developing ROP.

Methods

In total, 202 protein markers in plasma were quantified by proximity extension assay from 35 extremely preterm infants on day 2 of life. Infants were sorted in groups by automated two-dimensional hierarchical clustering of all biomarkers. ROP was classified as stages I to III with or without surgical treatment. Predictive biomarkers were evaluated by analysis of variance and detected differences by two-sided paired t-test with Bonferroni corrections for multiple comparisons.

Results

Differences in 39 biochemical markers divided infants without ROP into two control groups (control 1, n = 7; control 2, n = 5; P < 0.05). Sixty-six biochemical markers defined differences between the control groups (n = 13) and all ROP infants (n = 23; P < 0.05). PARK7, VIM, MPO, CD69, and NEMO were markedly increased in control 1 compared to all ROP infants (P < 0.001). Lower TNFRSF4 and higher HER2 and GAL appeared in infants with ROP as compared to control 1 and/or 2 (P < 0.05, respectively).

Conclusions

Our data suggest that early elevated levels of PARK7, VIM, MPO, CD69, and NEMO may be associated with lower risk of developing ROP. Lower levels of TNFRSF4 with higher levels of HER2 and GAL may predict ROP development.

Translational Relevance

Cluster analysis of early postnatal biomarkers may help to identify infants with low or high risk of developing ROP.

Interaction between regulatory T cells and mast cells via IL-9 and TGF-β production

Research on the immunosuppression of cancer cells has attracted much attention in recent years. The present study sought to provide a new strategy for tumor immunotherapy targeting mast cells by studying the mechanisms underlying mast cell function in cancer immunosuppression. Between January 2015 and December 2017, the tumor tissues of 40 patients with gastric cancer (GC) were collected and grouped in Lihuili Hospital of Ningbo City, China. Pathological sections were prepared and an immunofluorescence assay was performed to analyze the expression of forkhead Box Protein P3 (FOXP3), tryptase, TGFβ1, TGF-βR, IL-9, IL-9R and Oxford 40 ligand (OX40L). Then, the correlations between FOXP3 and tryptase, TGFβ1 and tryptase expression, and the expression of OX40L in patients with GC with different stages were analyzed. The results revealed that high levels of mast cells were present in patients GC, and tryptase and FOXP3 expressions were positively correlated. Mast cells regulate T regulatory (reg) cells in the gastric tumor microenvironment by secreting TGFβ1. Tregs, in turn, promote the survival of mast cells in the tumor microenvironment by producing IL-9. Furthermore, OX40L expression in mast cells was significantly associated with Tumor-Node-Metastasis staging of GC. Overall, the present study reported a positive feedback system that functions through TGFβ1 and IL-9 to allow cross-talk between Tregs and mast cells. Moreover, OX40L may be a potential target for the diagnosis and treatment of GC. These results may provide a new strategy for tumor immunotherapy targeting mast cells.

TNFSF4 is a risk factor to systemic lupus erythematosus in a Latin American population

OBJECTIVE

The aim of this study was to examine the association of three TNFSF4 single nucleotide variants (SNVs) with systemic lupus erythematosus (SLE) susceptibility in Mexican patients.

METHODS

Genotypes of the TNFSF4 rs1234315T/C, rs2205960G/T, and rs704840T/G SNVs were determined using a TaqMan assay. In our study, we included 395 patients with SLE and 500 controls.

RESULTS

Our information shows a significant difference in the allelic and genotypic frequency of the three TNFSF4 SNVs between cases and controls. Thus, our data showed an association between TNFSF4 rs1234315T/C (T vs. C, OR 1.40, p = 0.00087), rs2205960G/T (G vs. T, OR 1.32, p = 0.0037), and rs704840T/G (T vs. G, OR 1.41, p = 0.0003) and SLE susceptibility in Mexican subjects. Besides, we conducted a meta-analysis to determine the role of TNFSF4 rs2205960G/T and SLE susceptibility; our results showed that this variant is a risk factor for SLE in Latin Americans and Asians.

CONCLUSION

Our results show that TNFSF4 rs1234315T/C, rs2205960G/T, and rs704840T/G are risk factors to SLE in Mexicans. This is the first study to document an association between TNFSF4 rs704840T/G and SLE in a Latin American population. In addition, our meta-analysis showed that TNFSF4 rs2205960G/T is a risk factor for Asians and Latin Americans. Key Point • The TNFSF4 rs1234315T/C, rs2205960G/T, and rs704849T/G SNVs are risk factors to SLE in patients from Mexico.

Th1 responses in vivo require cell-specific provision of OX40L dictated by environmental cues

The OX40-OX40L pathway provides crucial co-stimulatory signals for CD4 T cell responses, however the precise cellular interactions critical for OX40L provision in vivo and when these occur, remains unclear. Here, we demonstrate that provision of OX40L by dendritic cells (DCs), but not T cells, B cells nor group 3 innate lymphoid cells (ILC3s), is critical specifically for the effector Th1 response to an acute systemic infection with Listeria monocytogenes (Lm). OX40L expression by DCs is regulated by cross-talk with NK cells, with IFNγ signalling to the DC to enhance OX40L in a mechanism conserved in both mouse and human DCs. Strikingly, DC expression of OX40L is redundant in a chronic intestinal Th1 response and expression by ILC3s is necessary. Collectively these data reveal tissue specific compartmentalisation of the cellular provision of OX40L and define a mechanism controlling DC expression of OX40L in vivo.

The OX40-OX40L axis is a crucial component of the costimulatory requirement of CD4 T cell responses. Here, the authors show context and cell type specific expression of OX40L for driving Th1 cell generation during acute and chronic models of infection.

Associations between TNFSF4 gene polymorphisms (rs2205960 G > A, rs704840 T > G and rs844648 G > A) and susceptibility to autoimmune diseases in Asians: a meta-analysis

BACKGROUND

Tumor necrosis factor superfamily member 4 (TNFSF4) has significant role in modulating autoimmune diseases (ADs) and single nucleotide polymorphism (SNP) is also related with the susceptibility to some diseases. So a meta-analysis aimed at systematically assessing the associations between TNFSF4 polymorphisms (rs2205960 G > A, rs704840 T > G and rs844648 G > A) and ADs risk was performed in Asians.

METHODS

Total 14 eligible articles published before March 2019 involving 35 studies, of which 21 studies (16,109 cases and 26,378 controls) for rs2205960 G > A, 8 studies (2,424 cases and 3,692 controls) for rs704840 T > G, and 6 studies (3,839 cases and 5,867 controls) for rs844648 G > A were included. Effects of the three respective polymorphisms on the susceptibility to ADs were estimated by pooling the odds ratios (ORs) with their corresponding 95% confidence interval (95% CI) in allelic, dominant, recessive, heterozygous and homozygous models.

RESULTS

The overall analysis revealed that all the rs2205960 G > A, rs704840 T > G and rs844648 G > A polymorphisms could increase the risk of ADs in allelic, dominant, recessive, heterozygous and homozygous models. Furthermore, subgroup analysis showed that both rs2205960 G > A and rs704840 T > G were significantly associated with the susceptibility to systemic lupus erythematosus (SLE). What's more, statistically significant association between rs2205960 G > A polymorphism and primary Sjögren's syndrome (pSS) susceptibility was also observed in allelic, dominant and heterozygous models.

CONCLUSIONS

This current meta-analysis suggested that all of the three TNFSF4 polymorphisms may be associated with ADs susceptibility in Asians.

New pathways in immune stimulation: targeting OX40

Immune checkpoint blockers (ICB) reinvigorate the immune system by removing the molecular brakes responsible for the scarce activity of immune phenotypes against malignant cells. After having proven their remarkable role as monotherapy, combinations of anti-Programmed cell death 1 (PD-1)/Programmed death-ligand 1 (PD-L1) agents with cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) antibodies, chemotherapy and/or anti-angiogenic compounds provide unprecedented results and durable responses across a variety of tumour types. Nevertheless, the main drawbacks of ICB are represented by primary and acquired resistance, translating into disease progression, as well as by immune-related toxicities. In this sense, novel strategies to foster the immune system through its direct stimulation are being tested in order to provide additional clinical improvements in patients with cancer. In this scenario, the co-stimulatory molecule OX40 (CD134) belongs to the next generation of immune therapeutic targets. Preliminary results of early clinical trials evaluating OX40 stimulation by means of different agents are encouraging. Here we review the rationale of OX40 targeting, highlighting the combination of OX40-directed therapies with different anticancer agents as a potential strategy to foster the immune system against malignant phenotypes.

An update on potentials and promises of T cell co-signaling molecules in transplantation

The promising outcomes of immune-checkpoint based immunotherapies in cancer have provided a proportional perspective ahead of exploiting similar approaches in allotransplantation. Belatacept (CTLA-4-Ig) is an example of costimulation blockers successfully exploited in renal transplantation. Due to the wide range of regulatory molecules characterized in the past decades, some of these molecules might be candidates as immunomodulators in the case of tolerance induction in transplantation. Although there are numerous attempts on the apprehension of the effects of co-signaling molecules on immune response, the necessity for a better understanding is evident. By increasing the knowledge on the biology of co-signaling pathways, some pitfalls are recognized and improved approaches are proposed. The blockage of CD80/CD28 axis is an instance of evolution toward more efficacy. It is now evident that anti-CD28 antibodies are more effective than CD80 blockers in animal models of transplantation. Other co-signaling axes such as PD-1/PD-L1, CD40/CD154, 2B4/CD48, and others discussed in the present review are examples of critical immunomodulatory molecules in allogeneic transplantation. We review here the outcomes of recent experiences with co-signaling molecules in preclinical studies of solid organ transplantation.

Genistein alleviates atherosclerosis in apolipoprotein E-deficient mice by interrupting the OX40/OX40L pathway

More and more evidence shows that the OX40/OX40L interaction plays a critical role in the development of atherosclerosis. However, it is not known whether genistein, a natural phytoestrogen with anti-inflammatory effects found in soybean extract, can prevent experimental atherosclerosis by regulating the OX40/OX40L pathway. This study aims to explore the effect and the underlying mechanisms of genistein on the development of atherosclerosis in apolipoprotein E gene knockout (ApoE^-/-) mice. ApoE^-/- mice, fed an atherogenic diet, were treated with genistein (15 and 45 mg kg^-1 day^-1). In vitro studies were carried out in oxidized LDL (oxLDL)-stimulated SMCs. Our results show that genistein treatment remarkably reduced atherosclerotic plaque formation and reduced the serum levels of pro-inflammatory cytokines in ApoE^-/- mice. Also, genistein promotes plaque stability in ApoE^-/- mice, characterized by smaller necrotic core areas of atherosclerotic plaques and reduced MMP-9 protein expression in primary smooth muscle cells (SMCs). Furthermore, when mRNA expression and the protein expression of OX40 were significantly increased, they were inhibited by genistein in response to an atherogenic diet. Notably, ApoE^-/- mice with an anti-OX40L antibody presented a significant decrease in atherosclerotic lesion formation, which has no further beneficial effects when combined with genistein. These results suggest that genistein potentially has atheroprotective effects that involve the inhibition of the OX40/OX40L pathway, which could be used to prevent and treat atherosclerosis.

Relative Expression of OX40, OX40L mRNA, and OX40L Serum Levels in Women with Recurrent Spontaneous Abortion

This study determined the roles of OX40 and OX40L in women with recurrent spontaneous abortion (RSA). We compared the expression of OX40 and OX40L genes in peripheral blood mRNA levels and serum levels of OX40L in women with a history of RSA to the control group. In this case-control study, 40 women with a history of RSA (case group), and 40 others with no history of abortion (control group) were investigated. The expressions of OX40 mRNA and OX40L mRNA were determined in the two groups using the quantitative polymerase chain reaction. Also, the enzyme-linked immunosorbent assay was used to determine the levels of serum OX40L in the two groups. There were no significant differences in the maternal age of women in the two groups (30.1 ± 4.28 years in the case vs. 30.03 ± 4.23 years in the control group). There was no difference in terms of the levels of OX40 and OX40L mRNA between the groups (p = 0.08 and p = 0.56, respectively). In addition, there was no significant correlation between the expression of OX40 and OX40L mRNA levels with age or the number of abortions. The correlation between OX40 and OX40L mRNA levels was not significant. RSA history group turned to show a higher level of serum OX40L than the control group (p = 0.03). In conclusion, our findings demonstrated that the expression of OX40 mRNA and OX40L mRNA was similar between women with a history of RSA and the control group. The elevation of serum OX40L level may be considered as a risk factor for RSA.

Reverse Signaling of Tumor Necrosis Factor Superfamily Proteins in Macrophages and Microglia: Superfamily Portrait in the Neuroimmune Interface

The tumor necrosis factor (TNF) superfamily (TNFSF) is a protein superfamily of type II transmembrane proteins commonly containing the TNF homology domain. The superfamily contains more than 20 protein members, which can be released from the cell membrane by proteolytic cleavage. Members of the TNFSF function as cytokines and regulate diverse biological processes, including immune responses, proliferation, differentiation, apoptosis, and embryogenesis, by binding to TNFSF receptors. Many TNFSF proteins are also known to be responsible for the regulation of innate immunity and inflammation. Both receptor-mediated forward signaling and ligand-mediated reverse signaling play important roles in these processes. In this review, we discuss the functional expression and roles of various reverse signaling molecules and pathways of TNFSF members in macrophages and microglia in the central nervous system (CNS). A thorough understanding of the roles of TNFSF ligands and receptors in the activation of macrophages and microglia may improve the treatment of inflammatory diseases in the brain and periphery. In particular, TNFSF reverse signaling in microglia can be exploited to gain further insights into the functions of the neuroimmune interface in physiological and pathological processes in the CNS.

Association of high levels of plasma OX40 with acute adult T-cell leukemia

OX40, a member of the tumor necrosis factor receptor (TNFR) superfamily, co-stimulates activated T cells following interaction with its own ligand OX40L. Human T-cell leukemia virus type-1 (HTLV-1) is an etiological agent of adult T-cell leukemia (ATL). ATL cells are known to express cell surface OX40; however, the level of soluble OX40 (sOX40) in blood samples from ATL patients is unknown. Quantitative enzyme-linked immune-sorbent assay (ELISA) showed that sOX40 levels were significantly higher in plasma from acute ATL patients than those from asymptomatic HTLV-1 carriers and healthy donors, and correlated with sCD25 levels and HTLV-1 proviral loads in peripheral blood mononuclear cells (PBMCs). Fresh PBMCs from acute ATL patients showed a higher percentage of OX40-positive cells compared with those from carriers, and shed sOX40 into culture supernatants. Shedding of sOX40 was partially inhibited by a matrix metalloproteinase (MMP) inhibitor, GM6001. A fraction of sOX40 was capable of binding to OX40L. These results suggest that high levels of sOX40 are shed into blood from a large number of ATL cells in acute ATL patients. Thus, abnormally elevated plasma sOX40 levels may be useful as an additional diagnostic marker of acute ATL.

Preparation, characterization and application of anti-human OX40 ligand (OX40L) monoclonal antibodies and establishment of a sandwich ELISA for autoimmune diseases detection

OX40L (CD252, TNFSF4), a type II transmembrane protein which like other tumor necrosis factor ligands, involved in the costimulation and differentiation of T cells, functions as a positive signal in immune response. To investigate the biological function of soluble OX40L (sOX40L), three functional anti-OX40L monoclonal antibodies (mAbs) 3D2, 3F7 and 2H3 were obtained by hybridoma technology. Besides, specificity of the mAbs was further demonstrated by ELISA, Western blot and Immunofluorescence experiments. We also developed a novel enzyme-linked immunosorbent assay (ELISA) based on two anti-human OX40L antibodies 3D2 and 3F7 with different epitopes. Using the ELISA system, we found that sOX40L in the sera of healthy donors increases in an age-dependent manner and that enhanced sOX40L expression in some autoimmune diseases especially in rheumatoid arthritis (RA) patients, suggesting the potential diagnostic significance of sOX40L in the autoimmune diseases. Together, these data demonstrate that the existence of circulating sOX40L in human sera might play an important role in immunoregulation.

Identification of a Novel OX40L+ Dendritic Cell Subset That Selectively Expands Regulatory T cells

We have previously shown GM-CSF derived bone-marrow dendritic cells (G-BMDCs) can induce the selective expansion of Tregs through the surface-bound molecule OX40L; however, the physiological role of this ex vivo derived DC subset remained to be elucidated. We determined GM-CSF administration to mice induced the generation of in vivo derived OX40L⁺ DCs, phenotypically similar to ex vivo OX40L⁺G-BMDCs, in the spleen, brachial lymph nodes and liver. The generation of OX40L⁺ DCs correlated with increased percentages of functionally suppressive Tregs in the spleen, brachial lymph nodes, and liver of GM-CSF treated mice. DCs from GM-CSF treated mice expanded Tregs in CD4⁺ T-cell co-cultures in an OX40L dependent manner, suggesting OX40L⁺ DCs may play a role in peripheral Treg homeostasis. Furthermore, comparing the transcriptome data of OX40L⁺ DCs to that of all immune cell types revealed OX40L⁺ DCs to be distinct from steady-state immune cells and, microarray analysis of OX40L⁺G-BMDCs and OX40L⁻G-BMDCs revealed higher expression of molecules that are associated with tolerogenic phenotype and could play important roles in the function of OX40L⁺ DCs. These findings suggest that OX40L⁺ DCs may represent a unique DC subset induced under inflammatory conditions that may play an essential role in maintaining Treg homeostasis.

Expression of the Immune Checkpoint Modulator OX40 in Acute Lymphoblastic Leukemia Is Associated with BCR-ABL Positivity

OX40 and its ligand are members of the TNF/TNF receptor superfamily, which includes various molecules influencing cellular signaling and function of both tumor and immune cells. The ability of OX40 to promote proliferation and differentiation of activated T cells fueled present attempts to modulate this immune checkpoint to reinforce antitumor immunity. While we recently found evidence for the involvement of OX40 in pathophysiology of acute myeloid leukemia including natural killer (NK) cell immunosurveillance, less is known on its role in acute lymphoblastic leukemia (ALL). In the present study, OX40 expression on ALL cells was significantly associated with positivity for the adverse risk factor BCR-ABL. In line, signaling via OX40 increased metabolic activity of primary ALL cells and resulted in release of cytokines involved in disease pathophysiology. Furthermore, interaction of ALL-expressed OX40 with its cognate ligand on NK cells stimulated ALL cell lysis. The data presented thus not only identify the yet unknown involvement of OX40/OX40L in ALL pathophysiology and NK cell immunosurveillance but also point to the necessity to thoroughly consider the consequences of modulating the OX40/OX40L molecule system beyond its effects on T cells when developing OX40-targeting approaches for cancer immunotherapy.

Crucial role of OX40/OX40L signaling in a murine model of asthma

The aim of the present study was to explore the roles of OX40/OX40 ligand (OX40L) signaling and OX40⁺ T cells in ovalbumin (OVA)-induced mouse asthma model. Asthma was induced by OVA exposure and subsequent co-treatment with OX40L protein, neutralizing anti-OX40L blocking antibody, OX40⁺ T cells or PBS. The protein expression levels of interleukin (IL)-4, IL-6, IL-13, IL-17, tumor necrosis factor (TNF)-α and interferon (IFN)-γ in bronchoalveolar lavage fluid (BALF) were examined using murine cytokine-specific ELISA. Eosinophil accumulation as well as proliferation and apoptosis of T cells in BALF were detected by Cell Counting kit-8 and flow cytometric assays. Expression of the apoptosis-related protein cleaved caspase-3 was examined in OX40⁺ T cells using western blot assay. Flow cytometric analysis revealed that OVA-treated mice that were co-treated with OX40L or OX40⁺ T cells exhibited higher eosinophil infiltration compared with control mice treated only with OVA, whereas neutralizing anti-OX40L blocking antibody inhibited eosinophil infiltration. ELISA assays demonstrated that the expression of IL-4, IL-6, IL-13, IL-17, TNF-α and IFN-γ in BALF in OX40L-treated and OX40⁺ T cell-treated mice was increased compared with expression levels in control mice. Treatment with OX40L protein effectively reduced apoptosis of T cells and the expression of cleaved caspase-3 in T cells. OX40L-treated and OX40⁺ T cell-treated mice exhibited increased asthma through OX40/OX40L signaling, which probably promoted inflammatory factor expression, eosinophil infiltration and T cell proliferation.

The Immune Checkpoint Modulator OX40 and Its Ligand OX40L in NK-Cell Immunosurveillance and Acute Myeloid Leukemia

The TNF receptor family member OX40 promotes activation and proliferation of T cells, which fuels efforts to modulate this immune checkpoint to reinforce antitumor immunity. Besides T cells, NK cells are a second cytotoxic lymphocyte subset that contributes to antitumor immunity, particularly in leukemia. Accordingly, these cells are being clinically evaluated for cancer treatment through multiple approaches, such as adoptive transfer of ex vivo expanded polyclonal NK cells (pNKC). Here, we analyzed whether and how OX40 and its ligand (OX40L) influence NK-cell function and antileukemia reactivity. We report that OX40 is expressed on leukemic blasts in a substantial percentage of patients with acute myeloid leukemia (AML) and that OX40 can, after stimulation with agonistic OX40 antibodies, mediate proliferation and release of cytokines that act as growth and survival factors for the leukemic cells. We also demonstrate that pNKC differentially express OX40L, depending on the protocol used for their generation. OX40L signaling promoted NK-cell activation, cytokine production, and cytotoxicity, and disruption of OX40-OX40L interaction impaired pNKC reactivity against primary AML cells. Together, our data implicate OX40/OX40L in disease pathophysiology of AML and in NK-cell immunosurveillance. Our findings indicate that effects of the OX40-OX40L receptor-ligand system in other immune cell subsets and also malignant cells should be taken into account when developing OX40-targeted approaches for cancer immunotherapy. Cancer Immunol Res; 6(2); 209-21. ©2018 AACR.

Establishment of cell lines from adult T-cell leukemia cells dependent on negatively charged polymers

Growing adult T-cell leukemia/lymphoma (ATLL) cells in vitro is difficult. Here, we examined the effects of static electricity in the culture medium on the proliferation of ATLL cells. Six out of 10 ATLL cells did not proliferate in vitro and thus had to be cultured in a medium containing negatively charged polymers. In the presence of poly-γ-glutamic acid (PGA) or chondroitin sulfate (CDR), cell lines (HKOX3-PGA, HKOX3-CDR) were established from the same single ATLL case using interleukin (IL)-2, IL-4, and feeder cells expressing OX40L (OX40L⁺HK). Dextran sulfate inhibited growth in both HKOX3 cell lines. Both PGA and OX40L⁺HK were indispensable for HKOX3-PGA growth, but HKOX3-CDR could proliferate in the presence of CDR or OX40L⁺HK alone. Thus, the specific action of each negatively charged polymer promoted the growth of specific ATLL cells in vitro.

Adult T-cell leukemia: molecular basis for clonal expansion and transformation of HTLV-1-infected T cells

Adult T-cell leukemia (ATL) is an aggressive T-cell malignancy caused by human T-cell leukemia virus type 1 (HTLV-1) that develops through a multistep carcinogenesis process involving 5 or more genetic events. We provide a comprehensive overview of recently uncovered information on the molecular basis of leukemogenesis in ATL. Broadly, the landscape of genetic abnormalities in ATL that include alterations highly enriched in genes for T-cell receptor-NF-κB signaling such as PLCG1, PRKCB, and CARD11 and gain-of function mutations in CCR4 and CCR7 Conversely, the epigenetic landscape of ATL can be summarized as polycomb repressive complex 2 hyperactivation with genome-wide H3K27 me3 accumulation as the basis of the unique transcriptome of ATL cells. Expression of H3K27 methyltransferase enhancer of zeste 2 was shown to be induced by HTLV-1 Tax and NF-κB. Furthermore, provirus integration site analysis with high-throughput sequencing enabled the analysis of clonal composition and cell number of each clone in vivo, whereas multicolor flow cytometric analysis with CD7 and cell adhesion molecule 1 enabled the identification of HTLV-1-infected CD4+ T cells in vivo. Sorted immortalized but untransformed cells displayed epigenetic changes closely overlapping those observed in terminally transformed ATL cells, suggesting that epigenetic abnormalities are likely earlier events in leukemogenesis. These new findings broaden the scope of conceptualization of the molecular mechanisms of leukemogenesis, dissecting them into immortalization and clonal progression. These recent findings also open a new direction of drug development for ATL prevention and treatment because epigenetic marks can be reprogrammed. Mechanisms underlying initial immortalization and progressive accumulation of these abnormalities remain to be elucidated.

OX40: Structure and function - What questions remain?

OX40 is a type 1 transmembrane glycoprotein, reported nearly 30 years ago as a cell surface antigen expressed on activated T cells. Since its discovery, it has been validated as a bone fide costimulatory molecule for T cells and member of the TNF receptor family. However, many questions still remain relating to its function on different T cell sub-sets and with recent interest in its utility as a target for antibody-mediated immunotherapy, there is a growing need to gain a better understanding of its biology. Here, we review the expression pattern of OX40 and its ligand, discuss the structure of the receptor:ligand interaction, the downstream signalling it can elicit, its function on different T cell subsets and how antibodies might engage with it to provide effective immunotherapy.

OX40, OX40L and Autoimmunity: a Comprehensive Review

The tumour necrosis factor receptor OX40 (CD134) is activated by its cognate ligand OX40L (CD134L, CD252) and functions as a T cell co-stimulatory molecule. OX40-OX40L interactions have been proposed as a potential therapeutic target for treating autoimmunity. OX40 is expressed on activated T cells, and in the mouse at rest on regulatory T cells (Treg). OX40L is found on antigen-presenting cells, activated T cells and others including lymphoid tissue inducer cells, some endothelia and mast cells. Expression of both molecules is increased after antigen presentation occurs and also in response to multiple other pro-inflammatory factors including CD28 ligation, CD40L ligation and interferon-gamma signaling. Their interactions promote T cell survival, promote an effector T cell phenotype, promote T cell memory, tend to reduce regulatory function, increase effector cytokine production and enhance cell mobility. In some circumstances, OX40 agonism may be associated with increased tolerance, although timing with respect to antigenic stimulus is important. Further, recent work has suggested that OX40L blockade may be more effective than OX40 blockade in reducing autoimmunity. This article reviews the expression of OX40 and OX40L in health, the effects of their interactions and insights from their under- or over-expression. We then review OX40 and OX40L expression in human autoimmune disease, identified associations of variations in their genes (TNFRSF4 and TNFSF4, respectively) with autoimmunity, and data from animal models of human diseases. A rationale for blocking OX40-OX40L interaction in human autoimmunity is then presented along with commentary on the one trial of OX40L blockade in human disease conducted to date. Finally, we discuss potential problems with clinical use of OX40-OX40L directed pharmacotherapy.

HTLV-1 bZIP Factor Enhances T-Cell Proliferation by Impeding the Suppressive Signaling of Co-inhibitory Receptors

Human T-cell leukemia virus type 1 (HTLV-1) causes adult T-cell leukemia-lymphoma (ATL) and inflammatory diseases. To enhance cell-to-cell transmission of HTLV-1, the virus increases the number of infected cells in vivo. HTLV-1 bZIP factor (HBZ) is constitutively expressed in HTLV-1 infected cells and ATL cells and promotes T-cell proliferation. However, the detailed mechanism by which it does so remains unknown. Here, we show that HBZ enhances the proliferation of expressing T cells after stimulation via the T-cell receptor. HBZ promotes this proliferation by influencing the expression and function of multiple co-inhibitory receptors. HBZ suppresses the expression of BTLA and LAIR-1 in HBZ expressing T cells and ATL cells. Expression of T cell immunoglobulin and ITIM domain (TIGIT) and Programmed cell death 1 (PD-1) was enhanced, but their suppressive effect on T-cell proliferation was functionally impaired. HBZ inhibits the co-localization of SHP-2 and PD-1 in T cells, thereby leading to impaired inhibition of T-cell proliferation and suppressed dephosphorylation of ZAP-70 and CD3ζ. HBZ does this by interacting with THEMIS, which associates with Grb2 and SHP-2. Thus, HBZ interacts with the SHP containing complex, impedes the suppressive signal from PD-1 and TIGIT, and enhances the proliferation of T cells. Although HBZ was present in both the nucleus and the cytoplasm of T cells, HBZ was localized largely in the nucleus by suppressed expression of THEMIS by shRNA. This indicates that THEMIS is responsible for cytoplasmic localization of HBZ in T cells. Since THEMIS is expressed only in T-lineage cells, HBZ mediated inhibition of the suppressive effects of co-inhibitory receptors accounts for how HTLV-1 induces proliferation only of T cells in vivo. This study reveals that HBZ targets co-inhibitory receptors to cause the proliferation of infected cells.

Since HTLV-1 infects only through cell-to-cell transmission, increasing the number of infected cells is critical for transmission of HTLV-1. Proliferation of HTLV-1 infected cells is critical for development of leukemia and inflammatory diseases. In this study, we showed that HBZ promotes the proliferation of infected cells by targeting co-inhibitory receptors. Paradoxically, HBZ enhances the expression of the co-inhibitory receptors TIGIT and PD-1. We found that HBZ concurrently hampers the growth-inhibitory signal of TIGIT and PD-1, thereby leading to the enhanced proliferation of HTLV-1 infected cells in vivo. HBZ does this by interacting with THEMIS, which is expressed only in T cells. It is known that HTLV-1 infects different types of cells but increases only T cells. Functional impairment of co-inhibitory receptors by interaction of HBZ with THEMIS is a mechanism how HTLV-1 specifically induces proliferation of T cells.

Advances in immunotherapy for melanoma management

Melanoma remains a leading cause of death among young adults. Evidence that melanoma tumor cells are highly immunogenic and a better understanding of T-cell immune checkpoints have changed the therapeutic approach to advanced melanoma. Instead of targeting the tumor directly, immunotherapy targets and activates the immune response using checkpoint inhibitors, monoclonal antibodies, vaccines, and adoptive T cell therapy. This review focuses on the immune signaling and biological mechanisms of action of recent immune-based melanoma therapies as well as their clinical benefits.

Inflammatory bowel disease: exploring gut pathophysiology for novel therapeutic targets

Ulcerative colitis and Crohn's disease are the 2 major phenotypes of inflammatory bowel disease (IBD), which are influenced by a complex interplay of immunological and genetic elements, though the precise etiology still remains unknown. With IBD developing into a globally prevailing disease, there is a need to explore new targets and a thorough understanding of the pathophysiological differences between the healthy and diseased gut could unearth new therapeutic opportunities. In this review, we provide an overview of the major aspects of IBD pathogenesis and thereafter present a comprehensive analysis of the gut pathophysiology leading to a discussion on some of the most promising targets and biologic therapies currently being explored. These include various gut proteins (CXCL-10, GATA-3, NKG2D, CD98, microRNAs), immune cells recruited to the gut (mast cells, eosinophils, toll-like receptors 2, 4), dysregulated proinflammatory cytokines (interleukin-6, -13, -18, -21), and commensal microbiota (probiotics and fecal microbiota transplantation). We also evaluate some of the emerging nonconventional therapies being explored in IBD treatment focusing on the latest developments in stem cell research, oral targeting of the gut-associated lymphoid tissue, novel anti-inflammatory signaling pathway targeting, adenosine deaminase inhibition, and the beneficial effects of antioxidant and nutraceutical therapies. In addition, we highlight the growth of biologics and their targets in IBD by providing information on the preclinical and clinical development of over 60 biopharmaceuticals representing the state of the art in ulcerative colitis and Crohn's disease drug development.

Enhancement of CD4(+) T cell response and survival via coexpressed OX40/OX40L in Graves' disease

OX40/OX40L pathway plays a very important role in the antigen priming T cells and effector T cells. In the present study, we aimed to examine the involvement of OX40/OX40L pathway in the activation of autoreactive T cells in patients with Grave's disease (GD). We found that OX40 and OX40L were constitutively coexpressed on peripheral CD4(+) T cells from GD patients using flow cytometry analysis. The levels of OX40 and OX40L coexpression on CD4(+) T cells were shown to be correlated with TRAbs. Cell proliferation assay showed that blocking OX40/OX40L signal inhibited T cell proliferation and survival, which suggested that OX40/OX40L could enhance CD4(+) T cell proliferation and maintain their long-term survival in GD by self-enhancing loop of T cell activation independent of APCs. Confocal microscopy and coimmunoprecipitation analysis further revealed that OX40 and OX40L formed a functional complex, which may facilitate signal transduction from OX40L to OX40 and contribute to the pathogenesis of GD.

OX40 and 4-1BB downregulate Kaposi’s sarcoma-associated herpesvirus replication in lymphatic endothelial cells, but 4-1BB and not OX40 inhibits viral replication in B-cells

Kaposi’s sarcoma-associated herpesvirus (KSHV) belongs to the human gammaherpesvirus subfamily and is associated with malignancies of endothelial origin (Kaposi’s sarcoma, KS) and B-cell origin [primary effusion lymphoma (PEL) and multicentric Castleman’s disease (MCD)]. Viral lytic replication is known to be required for KS and MCD. As KSHV-related tumours mostly develop in human subjects when the immune system is compromised by immunosuppressive regimen, human immunodeficiency virus infection or some genetic deficiencies, KSHV-specific immune responses are believed to be important in the control of KSHV replication. However, analysis of the roles of immune cells in viral pathogenesis has been difficult due to the lack of an adequate animal model. Recently, congenital OX40 deficiency, as determined by genome-wide exome sequencing, was shown to be associated with aggressive childhood KS in a patient, suggesting that disrupted OX40–OX40L interactions might be implicated in disease development. Here, we report that interaction of recombinant OX40 protein with OX40L expressed on endothelial cells severely impaired KSHV lytic replication. Furthermore, 4-1BB–4-1BBL interactions were also capable of efficiently inhibiting viral replication in B-cells and endothelial cells. To the best of our knowledge, this is the first direct evidence that ligation of tumour necrosis factor superfamily members and their cognate receptors is important for the control of viral lytic replication. These data are likely to pave the way for the development of KSHV-specific therapies for KS and MCD, in which viral lytic replication is a disease-determining factor.

OX40 ligand newly expressed on bronchiolar progenitors mediates influenza infection and further exacerbates pneumonia

Influenza virus epidemics potentially cause pneumonia, which is responsible for much of the mortality due to the excessive immune responses. The role of costimulatory OX40-OX40 ligand (OX40L) interactions has been explored in the non-infectious pathology of influenza pneumonia. Here, we describe a critical contribution of OX40L to infectious pathology, with OX40L deficiency, but not OX40 deficiency, resulting in decreased susceptibility to influenza viral infection. Upon infection, bronchiolar progenitors increase in number for repairing the influenza-damaged epithelia. The OX40L expression is induced on the progenitors for the antiviral immunity during the infectious process. However, these defense-like host responses lead to more extensive infection owing to the induced OX40L with α-2,6 sialic acid modification, which augments the interaction with the viral hemagglutinin. In fact, the specific antibody against the sialylated site of OX40L exhibited therapeutic potency in mitigating the OX40L-mediated susceptibility to influenza. Our data illustrate that the influenza-induced expression of OX40L on bronchiolar progenitors has pathogenic value to develop a novel therapeutic approach against influenza.

Osteopontin-integrin interaction as a novel molecular target for antibody-mediated immunotherapy in adult T-cell leukemia

Background

Adult T-cell leukemia (ATL) is a CD4⁺ T-cell neoplasm with a poor prognosis. A previous study has shown that there is a strong correlation between the secreted matricellular protein osteopontin (OPN) level and disease severity in ATL patients. Here, we investigated the role of OPN in ATL pathogenesis and the possible application of anti-OPN monoclonal antibody (mAb) for ATL immunotherapy in NOD/Shi-scid,IL-2Rg^null (NOG) mice.

Results

Subcutaneous inoculation of ATL cell lines into NOG mice increased the plasma level of OPN, which significantly correlated with metastasis of the inoculated cells and survival time. Administration of an SVVYGLR motif-recognizing anti-OPN mAb resulted in inhibition not only of tumor growth but also of tumor invasion and metastasis. The number of fibroblast activating protein-positive fibroblasts was also reduced by this mAb. We then co-inoculated mouse embryonic fibroblasts (MEFs) isolated from wild-type (WT) or OPN knockout mice together with ATL-derived TL-OmI cells into the NOG mice. The mice co-inoculated with WT MEFs displayed a significant decrease in survival relative to those injected with TL-OmI cells alone and the absence of OPN in MEFs markedly improved the survival rate of TL-OmI-inoculated mice. In addition, tumor volume and metastasis were also reduced in the absence of OPN.

Conclusion

We showed that the xenograft NOG mice model can be a useful system for assessment of the physiological role of OPN in ATL pathogenesis. Using this xenograft model, we found that fibroblast-derived OPN was involved in tumor growth and metastasis, and that this tumor growth and metastasis was significantly suppressed by administration of the anti-OPN mAbs. Our findings will lead to a novel mAb-mediated immunotherapeutic strategy targeting against the interaction of OPN with integrins on the tumor of ATL patients.

Electronic supplementary material

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