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

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

The online version of this article (doi:10.1186/s12977-015-0225-x) contains supplementary material, which is available to authorized users.

Immunostimulation by OX40 Ligand Transgenic Ewing Sarcoma Cells

Interleukin-2 (IL-2) transgenic Ewing sarcoma cells can induce tumor specific T and NK cell responses and reduce tumor growth in vivo and in vitro. Nevertheless, the efficiency of this stimulation is not high enough to inhibit tumor growth completely. In addition to recognition of the cognate antigen, optimal T-cell stimulation requires signals from so-called co-stimulatory molecules. Several members of the tumor necrosis factor superfamily have been identified as co-stimulatory molecules that can augment antitumor immune responses. OX40 (CD134) and OX40 ligand (OX40L = CD252; also known as tumor necrosis factor ligand family member 4) is one example of such receptor/ligand pair with co-stimulatory function. In the present investigation, we generated OX40L transgenic Ewing sarcoma cells and tested their immunostimulatory activity in vitro. OX40L transgenic Ewing sarcoma cells showed preserved expression of Ewing sarcoma-associated (anti)gens including lipase member I, cyclin D1 (CCND1), cytochrome P450 family member 26B1 (CYP26B1), and the Ewing sarcoma breakpoint region 1-friend leukemia virus integration 1 (EWSR1-FLI1) oncogene. OX40L-expressing tumor cells showed a trend for enhanced immune stimulation against Ewing sarcoma cells in combination with IL-2 and stimulation of CD137. Our data suggest that inclusion of the OX40/OX40L pathway of co-stimulation might improve immunotherapy strategies for the treatment of Ewing sarcoma.

OX40 ligand expressed in glioblastoma modulates adaptive immunity depending on the microenvironment: a clue for successful immunotherapy

Background

Glioblastoma is the most malignant human brain tumor and has a dismal prognosis; however, some patients show long-term survival. The interaction between the costimulatory molecule OX40 and its ligand OX40L generates key signals for T-cell activation. The augmentation of this interaction enhances antitumor immunity. In this present study, we explored whether OX40 signaling is responsible for antitumor adaptive immunity against glioblastoma and also established therapeutic antiglioma vaccination therapy.

Methods

Tumor specimens were obtained from patients with primary glioblastoma (n = 110) and grade III glioma (n = 34). Quantitative polymerase chain reaction (PCR), flow cytometry, and immunohistochemistry were used to analyze OX40L expression in human glioblastoma specimens. Functional consequences of OX40 signaling were studied using glioblastoma cell lines, mouse models of glioma, and T cells isolated from human subjects and mice. Cytokine production assay with mouse regulatory T cells was conducted under hypoxic conditions (1.5% O₂).

Results

OX40L mRNA was expressed in glioblastoma specimens and higher levels were associated with prolonged progression-free survival of patients with glioblastoma, who had undergone gross total resection. In this regard, OX40L protein was expressed in A172 human glioblastoma cells and its expression was induced under hypoxia, which mimics the microenvironment of glioblastoma. Notably, human CD4 T cells were activated when cocultured in anti-CD3-coated plates with A172 cells expressing OX40L, as judged by the increased production of interferon-γ. To confirm the survival advantage of OX40L expression, we then used mouse glioma models. Mice bearing glioma cells forced to express OX40L did not die during the observed period after intracranial transplantation, whereas all mice bearing glioma cells lacking OX40L died. Such a survival benefit of OX40L was not detected in nude mice with an impaired immune system. Moreover, compared with systemic intraperitoneal injection, the subcutaneous injection of the OX40 agonist antibody together with glioma cell lysates elicited stronger antitumor immunity and prolonged the survival of mice bearing glioma or glioma-initiating cell-like cells. Finally, OX40 triggering activated regulatory T cells cultured under hypoxia led to the induction of the immunosuppressive cytokine IL10.

Conclusion

Glioblastoma directs immunostimulation or immunosuppression through OX40 signaling, depending on its microenvironment.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0307-3) contains supplementary material, which is available to authorized users.

The New Era of Cancer Immunotherapy: Manipulating T-Cell Activity to Overcome Malignancy

Using the immune system to control cancer has been investigated for over a century. Yet it is only over the last several years that therapeutic agents acting directly on the immune system have demonstrated improved overall survival for cancer patients in phase III clinical trials. Furthermore, it appears that some patients treated with such agents have been cured of metastatic cancer. This has led to increased interest and acceleration in the rate of progress in cancer immunotherapy. Most of the current immunotherapeutic success in cancer treatment is based on the use of immune-modulating antibodies targeting critical checkpoints (CTLA-4 and PD-1/PD-L1). Several other immune-modulating molecules targeting inhibitory or stimulatory pathways are being developed. The combined use of these medicines is the subject of intense investigation and holds important promise. Combination regimens include those that incorporate targeted therapies that act on growth signaling pathways, as well as standard chemotherapy and radiation therapy. In fact, these standard therapies have intrinsic immune-modulating properties that can support antitumor immunity. In the years ahead, adoptive T-cell therapy will also be an important part of treatment for some cancer patients. Other areas which are regaining interest are the use of oncolytic viruses that immunize patients against their own tumors and the use of vaccines against tumor antigens. Immunotherapy has demonstrated unprecedented durability in controlling multiple types of cancer and we expect its use to continue expanding rapidly.

T cells in vascular inflammatory diseases

Inflammation of the human vasculature is a manifestation of many different diseases ranging from systemic autoimmune diseases to chronic inflammatory diseases, in which multiple types of immune cells are involved. For both autoimmune diseases and chronic inflammatory diseases several observations support a key role for T lymphocytes in these disease pathologies, but the underlying mechanisms are poorly understood. Previous studies in several autoimmune diseases have demonstrated a significant role for a specific subset of CD4⁺ T cells termed effector memory T (T_EM) cells. This expanded population of T_EM cells may contribute to tissue injury and disease progression. These cells exert multiple pro-inflammatory functions through the release of effector cytokines. Many of these cytokines have been detected in the inflammatory lesions and participate in the vasculitic reaction, contributing to recruitment of macrophages, neutrophils, dendritic cells, natural killer cells, B cells, and T cells. In addition, functional impairment of regulatory T cells paralyzes anti-inflammatory effects in vasculitic disorders. Interestingly, activation of T_EM cells is uniquely dependent on the voltage-gated potassium Kv1.3 channel providing an anchor for specific drug targeting. In this review, we focus on the CD4⁺ T cells in the context of vascular inflammation and describe the evidence supporting the role of different T cell subsets in vascular inflammation. Selective targeting of pathogenic T_EM cells might enable a more tailored therapeutic approach that avoids unwanted adverse side effects of generalized immunosuppression by modulating the effector functions of T cell responses to inhibit the development of vascular inflammation.

Systemic Sclerosis is a Complex Disease Associated Mainly with Immune Regulatory and Inflammatory Genes

Systemic sclerosis (SSc) is a fibrotic and autoimmune disease characterized clinically by skin and internal organ fibrosis and vascular damage, and serologically by the presence of circulating autoantibodies. Although etiopathogenesis is not yet well understood, the results of numerous genetic association studies support genetic contributions as an important factor to SSc. In this paper, the major genes of SSc are reviewed. The most recent genome-wide association studies (GWAS) are taken into account along with robust candidate gene studies. The literature search was performed on genetic association studies of SSc in PubMed between January 2000 and March 2014 while eligible studies generally had over 600 total participants with replication. A few genetic association studies with related functional changes in SSc patients were also included. A total of forty seven genes or specific genetic regions were reported to be associated with SSc, although some are controversial. These genes include HLA genes, STAT4, CD247, TBX21, PTPN22, TNFSF4, IL23R, IL2RA, IL-21, SCHIP1/IL12A, CD226, BANK1, C8orf13-BLK, PLD4, TLR-2, NLRP1, ATG5, IRF5, IRF8, TNFAIP3, IRAK1, NFKB1, TNIP1, FAS, MIF, HGF, OPN, IL-6, CXCL8, CCR6, CTGF, ITGAM, CAV1, MECP2, SOX5, JAZF1, DNASEIL3, XRCC1, XRCC4, PXK, CSK, GRB10, NOTCH4, RHOB, KIAA0319, PSD3 and PSOR1C1. These genes encode proteins mainly involved in immune regulation and inflammation, and some of them function in transcription, kinase activity, DNA cleavage and repair. The discovery of various SSc-associated genes is important in understanding the genetics of SSc and potential pathogenesis that contribute to the development of this disease.

Absence of association between atherosclerotic cerebral infarction and TNFSF4/TNFRSF4 single nucleotide polymorphisms rs1234313, rs1234314 and rs17568 in a Chinese population

OBJECTIVE

To clarify the association between atherosclerotic cerebral infarction (ACI) and the single nucleotide polymorphisms (SNP) rs1234313 and rs1234314 (in TNFSF4) and rs17568 (in TNFRSF4).

METHODS

Genomic DNA was extracted from peripheral blood of patients with ACI and healthy control subjects. The presence of carotid plaque was determined. Rs1234313, rs1234314 and rs17568 were characterized via SNP genotyping assay and verified by DNA sequencing.

RESULTS

Genotype distributions were in Hardy-Weinberg equilibrium. There were no significant differences in the allele and genotype distributions of rs1234313, rs1234314 and rs17568 between patients with ACI (n = 450) and healthy control subjects (n = 378), or between patients with ACI and carotid plaque (n = 342) and controls.

CONCLUSIONS

There were no significant associations between rs1234313, rs1234314 and rs17568 and ACI risk in a Han Chinese population.

Eosinophilic inflammation of chronic rhinosinusitis with nasal polyps is related to OX40 ligand expression

The aims of this study were to investigate OX40 ligand expression in sinus tissue from patients with nasal polyposis compared with patients with chronic rhinosinusitis without nasal polyps (NPs), and to determine if OX40 ligand expression is related to eosinophilic sinus infiltration. Twenty patients with chronic rhinosinusitis (11 with and nine without NPs) and seven controls were enrolled in the study. The mRNA expression of OX40 ligand and thymic stromal lymphopoietin and its receptor were analyzed. The immunoreactivity score for OX40 ligand and the eosinophil count were obtained. The mRNA expression and immunoreactivity score of OX40 ligand were higher in patients with nasal polyposis than in patients without NPs, as well as healthy controls. The mRNA expression of thymic stromal lymphopoietin and its receptor was significantly higher in nasal polyposis than in the control, but not significantly higher than in chronic rhinosinusitis without NPs. A correlation between the number of OX40 ligand-positive cells and the number of eosinophils in sinus biopsies was found only in patients with nasal polyposis. In conclusion, the thymic stromal lymphopoietin/OX40 ligand axis is up-regulated in nasal polyposis and is related to the intensity of eosinophilic inflammation.

Manipulation of costimulatory pathways in autoimmune diseases

Abstract There has recently been an increased understanding of the role of costimulatory pathways in the activation of the immune system and the maintenance of self-tolerance. It has been suggested that the absence of costimulatory molecules on normal tissue cells could serve to induce self-tolerance, and that inappropriate expression of costimulatory molecules on antigen-presenting cells (APCs) could activate self-reactive T cells, resulting in autoimmunity. Among several costimulatory molecules characterized, the interaction of CD28/CTLA4 on T cells with B7 (CD80 and CD86) on APC appears to be of primary importance. In fact, inhibition of the CD28-B7 interaction ameliorates several autoimmune diseases in experimental animal models. However, differential roles for CD80 and CD86 have been reported in certain conditions, and CTLA4 has been shown to play a negative role in T cell activation, suggesting that the actual regulatory mechanisms of this pathway in autoimmunity is much more complex. While the CD28-B7 interaction constitutes a predominant pathway of T cell costimulation, some intact T cell responses in CD28-deficient mice have suggested the presence of alternative pathways. T cell-dependent immunity is also critically regulated not only by other immunoglobulin superfamilies such as B7RP-1/ICOS, but also by tumor necrosis factor (TNF) and TNF-receptor superfamilies, which control immune responses in both a positive and a negative fashion. Therefore, further investigation of the physiological function of these costimulatory pathways in vivo may help in developing rational therapeutic approaches for autoimmune diseases.

Natural OX40L expressed on human T cell leukemia virus type-I-immortalized T cell lines interferes with infection of activated peripheral blood mononuclear cells by CCR5-utilizing human immunodeficiency virus

BACKGROUND

OX40 ligand (OX40L) co-stimulates and differentiates T cells via ligation of OX40 that is transiently induced on T cells upon activation, resulting in prolonged T cell survival and enhanced cytokine production by T cells. This view has led to the targeting of OX40 as a strategy to boost antigen specific T cells in the context of vaccination. In addition, the ligation of OX40 has also been shown to inhibit infection by CCR5-utilizing (R5) but not CXCR4-utilizing (X4) human immunodeficiency virus type-1 (HIV-1) via enhancement of production of CCR5-binding β-chemokines. It was reasoned that human T cell leukemia virus type-I (HTLV-1) immortalized T cell lines that express high levels of OX40L could serve as an unique source of physiologically functional OX40L. The fact that HTLV-1+ T cell lines simultaneously also express high levels of OX40 suggested a potential limitation.

RESULTS

Results of our studies showed that HTLV-1+ T cell lines bound exogenous OX40 but not OX40L, indicating that HTLV-1+ T cell lines express an active form of OX40L but an inactive form of OX40. Anti-OX40 non-blocking monoclonal antibody (mAb), but not blocking mAb, stained HTLV-1+ T cell lines, suggesting that the OX40 might be saturated with endogenous OX40L. Functionality of the OX40L was confirmed by the fact that a paraformaldehyde (PFA)-fixed HTLV-1+ T cell lines inhibited the infection of autologous activated peripheral blood mononuclear cells (PBMCs) with R5 HIV-1 which was reversed by either anti-OX40L blocking mAb or a mixture of neutralizing mAbs against CCR5-binding β-chemokines.

CONCLUSIONS

Altogether, these results demonstrated that autologous T cell lines immortalized by HTLV-1 can be utilized as a conventional source of physiologically functional OX40L.

A diametric role for OX40 in the response of effector/memory CD4+ T cells and regulatory T cells to alloantigen

OX40 is a member of the TNFR superfamily that has potent costimulatory properties. Although the impact of blockade of the OX40-OX40 ligand (OX40L) pathway has been well documented in models of autoimmune disease, its effect on the rejection of allografts is less well defined. In this article, we show that the alloantigen-mediated activation of naive and memory CD4(+) T cells results in the induction of OX40 expression and that blockade of OX40-OX40L interactions prevents skin allograft rejection mediated by either subset of T cells. Moreover, a blocking anti-OX40 had no effect on the activation and proliferation of T cells; rather, effector T cells failed to accumulate in peripheral lymph nodes and subsequently migrate to skin allografts. This was found to be the result of an enhanced degree of cell death among proliferating effector cells. In clear contrast, blockade of OX40-OX40L interactions at the time of exposure to alloantigen enhanced the ability of regulatory T cells to suppress T cell responses to alloantigen by supporting, rather than diminishing, regulatory T cell survival. These data show that OX40-OX40L signaling contributes to the evolution of the adaptive immune response to an allograft via the differential control of alloreactive effector and regulatory T cell survival. Moreover, these data serve to further highlight OX40 and OX40L as therapeutic targets to assist the induction of tolerance to allografts and self-Ags.

Inherited human OX40 deficiency underlying classic Kaposi sarcoma of childhood

Human OX40 is necessary for robust CD4⁺ T cell memory and confers selective protective immunity against HHV-8 infection in endothelial cells.

Kaposi sarcoma (KS), a human herpes virus 8 (HHV-8; also called KSHV)–induced endothelial tumor, develops only in a small fraction of individuals infected with HHV-8. We hypothesized that inborn errors of immunity to HHV-8 might underlie the exceedingly rare development of classic KS in childhood. We report here autosomal recessive OX40 deficiency in an otherwise healthy adult with childhood-onset classic KS. OX40 is a co-stimulatory receptor expressed on activated T cells. Its ligand, OX40L, is expressed on various cell types, including endothelial cells. We found OX40L was abundantly expressed in KS lesions. The mutant OX40 protein was poorly expressed on the cell surface and failed to bind OX40L, resulting in complete functional OX40 deficiency. The patient had a low proportion of effector memory CD4⁺ T cells in the peripheral blood, consistent with impaired CD4⁺ T cell responses to recall antigens in vitro. The proportion of effector memory CD8⁺ T cells was less diminished. The proportion of circulating memory B cells was low, but the antibody response in vivo was intact, including the response to a vaccine boost. Together, these findings suggest that human OX40 is necessary for robust CD4⁺ T cell memory and confers apparently selective protective immunity against HHV-8 infection in endothelial cells.

Increased expression of OX40 is associated with progressive disease in patients with HTLV-1-associated myelopathy/tropical spastic paraparesis

Background

OX40 is a member of the tumor necrosis factor receptor family that is expressed primarily on activated CD4⁺ T cells and promotes the development of effector and memory T cells. Although OX40 has been reported to be a target gene of human T-cell leukemia virus type-1 (HTLV-1) viral transactivator Tax and is overexpressed in vivo in adult T-cell leukemia (ATL) cells, an association between OX40 and HTLV-1-associated inflammatory disorders, such as HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), has not yet been established. Moreover, because abrogation of OX40 signals ameliorates chronic inflammation in animal models of autoimmune disease, novel monoclonal antibodies against OX40 may offer a potential treatment for HTLV-1-associated diseases such as ATL and HAM/TSP.

Results

In this study, we showed that OX40 was specifically expressed in CD4⁺ T cells naturally infected with HTLV-1 that have the potential to produce pro-inflammatory cytokines along with Tax expression. We also showed that OX40 was overexpressed in spinal cord infiltrating mononuclear cells in a clinically progressive HAM/TSP patient with a short duration of illness. The levels of the soluble form of OX40 (sOX40) in the cerebrospinal fluid (CSF) from chronic progressive HAM/TSP patients or from patients with other inflammatory neurological diseases (OINDs) were not different. In contrast, sOX40 levels in the CSF of rapidly progressing HAM/TSP patients were higher than those in the CSF from patients with OINDs, and these patients showed higher sOX40 levels in the CSF than in the plasma. When our newly produced monoclonal antibody against OX40 was added to peripheral blood mononuclear cells in culture, HTLV-1-infected T cells were specifically removed by a mechanism that depends on antibody-dependent cellular cytotoxicity.

Conclusions

Our study identified OX40 as a key molecule and biomarker for rapid progression of HAM/TSP. Furthermore, blocking OX40 may have potential in therapeutic intervention for HAM/TSP.

Costimulatory molecules on immunogenic versus tolerogenic human dendritic cells

Dendritic cells (DC) are sentinels of immunity, essential for homeostasis of T cell-dependent immune responses. Both functions of DC, initiation of antigen-specific T cell immunity and maintenance of tissue-specific tolerance originate from distinct stages of differentiation, immunogenic versus tolerogenic. Dependent on local micro milieu and inflammatory stimuli, tissue resident immature DC with functional plasticity differentiate into tolerogenic or immunogenic DC with stable phenotypes. They efficiently link innate and adaptive immunity and are ideally positioned to modify T cell-mediated immune responses. Since the T cell stimulatory properties of DC are significantly influenced by their expression of signal II ligands, it is critical to understand the impact of distinct costimulatory pathways on DC function. This review gives an overview of functional different human DC subsets with unique profiles of costimulatory molecules and outlines how different costimulatory pathways together with the immunosuppressive cytokine IL-10 bias immunogenic versus tolerogenic DC functions. Furthermore, we exemplarily describe protocols for the generation of two well-defined monocyte-derived DC subsets for their clinical use, immunogenic versus tolerogenic.

OX40 ligand expression abrogates the immunosuppressive function of retinal pigment epithelium

Background

This study aims to investigate the role of OX40 ligand (OX40L) in ocular inflammation via abrogation of retinal pigment epithelium (RPE)-mediated immunosuppression using an in vitro expression approach. OX40L cDNA was polymerase chain reaction-amplified and cloned into an eYFP fusion vector. Cultured retinal pigment epithelial cells (ARPE-19) were transfected with the vector. Total RNA from unstimulated or inflammatory cytokine-stimulated ARPE cells were isolated and analyzed for OX40L expression by reverse transcription-polymerase chain reaction. Peripheral blood mononuclear cells (PBMCs) were isolated from healthy human donors. Human ARPE cells (±OX40L ± GITR ligand (GITRL) expression) and PBMCs were co-cultured for in vitro proliferation studies.

Results

Polymerase chain reaction confirmed the insertion of the OX40L gene into the fusion vector. Flow cytometry and fluorescence microscopy further confirmed surface expression of OX40L on ARPE cells after transfection. OX40L expression was induced in the RPE cells stimulated with pro-inflammatory cytokines. In the co-culture studies, there was a significant reversal (20% to 30%) of the RPE-induced suppression of activated PBMCs when the ARPE cells were transfected with OX40L. When both OX40L and GITRL were concomitantly transfected into ARPE cells, there was an additive reversal of RPE-mediated T cell suppression, when compared to the reversal caused by RPE cells expressing either OX40L alone or GITRL alone.

Conclusions

Using an in vitro approach, we found that OX40L causes an abrogation of the RPE-mediated immunosuppression. OX40L appears to be regulated in the ARPE-19 cell line and may play an important role in the pathogenesis of various ocular inflammatory conditions.

Association of OX40L polymorphisms with sporadic breast cancer in northeast Chinese Han population

OX40L is an important costimulatory molecule that plays a crucial role in the regulation of T-cell-mediated immunity. The interaction of OX40-OX40L is involved in the pathogenesis of multiple autoimmune and inflammatory diseases such as systemic lupus erythematosus (SLE), carotid artery disease and cancer. The genetic variants of OX40L can increase the risk of SLE, atherosclerosis, systemic sclerosis and show gender-specific effects in some studies. Accordingly, we performed a case-control study including 557 breast cancer patients and 580 age- and sex-matched healthy controls to investigate whether single nucleotide polymorphisms (SNPs) in the OX40L gene are associated with sporadic breast cancer susceptibility and progression in Chinese Han women. Seven SNPs of OX40L (rs6661173, rs1234313, rs3850641, rs1234315, rs12039904, rs844648 and rs10912580) were genotyped with the method of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The results indicated that rs3850641G allele could increase the susceptibility to breast cancer (P = 0.009662), even in the validation study (P = 0.0001515). A significant association between rs3850641 and breast cancer risk was observed under the additive model and dominant model (P = 0.01042 and 0.01942, respectively). The haplotype analysis showed that haplotype A(rs844648)A(rs10912580) was significantly associated with breast cancer, even after 10,000 permutations for haplotypes in block only (P = 0.0003). In clinicopathologic features analysis, the association between rs1234315 and C-erbB2 status was significant (P = 0.02541). Our data primarily indicates that rs3850641 of OX40L gene contributes to sporadic breast carcinogenesis in a northeast Chinese Han population.

Association of TNFSF4 polymorphisms with systemic lupus erythematosus: a meta-analysis

INTRODUCTION

To more precisely estimate the association between the tumor necrosis factor ligand superfamily member 4 (TNFSF4) gene polymorphisms and systemic lupus erythematosus (SLE) risk, we surveyed studies on the association of the TNFSF4 rs2205960, rs1234315, rs844644, and rs844648 polymorphisms with SLE.

METHODS

A literature-based search was conducted to identify all relevant studies. A total of eight independent studies were identified and subsequently reviewed in the meta-analysis.

RESULTS

The meta-analysis showed an association between the TNFSF4 rs2205960 polymorphism and SLE in all subjects [ odds ratio (OR) 1.327, 95% confidence interval (CI) 1.227-1.436, P < 0.001]. In a subgroup analysis by ethnicity, a significantly increased risk for SLE was associated with TNFSF4 rs2205960 T allele among patients of European (OR 1.254, 95% CI 1.185-1.328, P < 0.001) and Asian ethnicity (OR 1.425, 95% CI 1.352-1.501, P < 0.001). The meta-analysis of the rs1234315 polymorphism revealed no association between SLE and the rs1234315 T allele in all subjects (OR 1.167, 95% CI 0.874-1.558, P = 0.296), but the results of the subgroup analysis revealed significant association in subjects of Asian ethnicity (OR 1.386, 95% CI 1.318-1.458, P < 0.001). No association was found between the rs844644 and rs844648 polymorphisms and SLE.

CONCLUSION

The results of our meta-analysis suggest that the TNFSF4 rs2205960 polymorphism may confer susceptibility to SLE in different populations and that the TNFSF4 rs1234315 polymorphism is associated with susceptibility to SLE in Asians.

Altered expression of TNFSF4 and TRAF2 mRNAs in peripheral blood mononuclear cells in patients with systemic lupus erythematosus: association with atherosclerotic symptoms and lupus nephritis

OBJECTIVES

This study compares the expression levels of tumor necrosis factor ligand superfamily member 4 (TNFSF4) and TNF-R-associated factor 2 (TRAF2) mRNAs in peripheral blood mononuclear cells (PBMCs) of patients with systemic lupus erythematosus (SLE) against healthy controls. The association of SLE disease activity index (SLEDAI) and clinical features of SLE with altered expression levels of TNFSF4 and TRAF2 mRNAs were also evaluated.

DESIGN

We used real-time reverse transcription polymerase chain reaction to measure TNFSF4 and TRAF2 mRNAs expression levels in peripheral blood mononuclear cells of 57 SLE patients and 57 healthy controls.

RESULTS

The expression level of TNFSF4 mRNA was significantly higher in SLE patients than in the control group. Overexpression of TNFSF4 was correlated with arthritis, atherosclerosis and lupus nephritis. TRAF2 mRNA was underexpressed in PBMCs of SLE patients, and its lower expression was associated with atherosclerosis and lupus nephritis. The altered expression levels of TNFSF4 and TRAF2 mRNAs was significantly correlated with SLEDAI.

CONCLUSION

Our results suggest that changes in the expression levels of TNFSF4 and TRAF2 mRNAs may significantly correlate with the pathogenesis of SLE, the disease activity and different clinical features of lupus, particularly lupus nephritis, atherosclerosis and arthritis.

The role of positive costimulatory molecules in transplantation and tolerance

PURPOSE OF REVIEW

The manipulation of costimulatory pathways holds tremendous potential for treating immunologically mediated diseases. In this article, we review the role of molecules that deliver a positive second signal that, together with an antigen-specific signal from the T-cell receptor, is necessary to promote complete T-cell activation, differentiation and development of effector function.

RECENT FINDINGS

Numerous positive costimulatory molecules have been identified: CD28/B7, induced costimulatory/induced costimulatory ligand, CD40/CD154, OX40/OX40L, CD27/CD70, 4-1BB/4-1BBL, LIGHT/herpes virus entry mediator, glucosyltransferase R and T-cell immunoglobulin mucin molecules. Many of these have been only recently discovered and remain incompletely studied. Recent work has demonstrated that some costimulatory molecules bind ligands expressed by nonprofessional activated protein C, some modulate regulatory T cells and some sustain rather than initiate immune responses. Emerging data suggest that the costimulatory pathways are redundant and that the various costimulatory molecules affect different T-cell populations and act at different times during the course of the immune response.

SUMMARY

These observations suggest that the therapeutic exploitation of strategies targeting costimulatory molecules will require carefully timed interventions directed against multiple pathways.

The role of costimulatory receptors of the tumour necrosis factor receptor family in atherosclerosis

Atherosclerosis is a chronic inflammatory disease that is mediated by both the innate and adaptive immune responses. T lymphocytes, that together with B cells are the cellular effectors of the adaptive immune system, are currently endowed with crucial roles in the development and progression of atherosclerosis. Costimulatory receptors are a class of molecules expressed by T lymphocytes that regulate the activation of T cells and the generation of effector T-cell responses. In this review we present the roles of costimulatory receptors of the tumour necrosis factor receptor (TNFR) superfamily in atherosclerosis and discuss the implications for future therapies that could be used to specifically modulate the immune response of pathogenic T cells in this disease.

T-helper cells as new players in ANCA-associated vasculitides

In anti-neutrophil cytoplasmic autoantibody-associated vasculitides (AAV), several observations support a key role of T-helper cells (CD4(+) T cells) in disease pathophysiology. An expanded population of effector memory CD4(+) T cells in AAV patients may contribute to tissue injury and disease progression. In addition, functional impairment of regulatory T cells (T(Regs)) is reported in AAV patients. A fraction of T(Regs) have the capacity to differentiate into Th17 cells in the context of a proinflammatory environment. Therefore, nonfunctionality of T(Regs) described in AAV patients may be caused by their conversion into IL-17-producing cells that may contribute to granulomatous vasculitis. Further investigations directed at the plasticity of T(Regs) in AAV patients are warranted.

Nasal cardiac myosin peptide treatment and OX40 blockade protect mice from acute and chronic virally-induced myocarditis

Myocarditis poses a severe health problem, can lead to dilated cardiomyopathy (DCM) and death, and is thought to be triggered by infections. Enteroviruses such as Coxsackie virus B3 (CVB3) have been implicated as a culprit, since they can cause acute and chronic heart disease in susceptible mice. CVB was detected in human cardiac myocytes in some cases, whereas acute CVB infection was thought to have caused death. Here we studied, whether nasal administration of cardiac myosin (CM) major histocompatibility class (MHC) II peptides CM₉₄₇-₉₆₀ and CM₇₃₅-₇₄₇ and OX40 blockade would be able to ameliorate immunopathology and heart disease in BALB/C mice infected with CVB3. We found that nasal CM-peptide prophylactic treatment significantly reduced myocarditis and mortality by enhancing Treg and IL-10 induction and that blockade of OX40 signaling could reduce heart inflammation when administered late during pathogenesis. Altogether, these results chart the way for novel prevention and intervention strategies for viral myocarditis.

Down-regulation of chemokine Ccl5 gene expression in the NTS of SHR may be pro-hypertensive

OBJECTIVES

Recent studies have demonstrated that pro-inflammatory molecules such as junctional adhesion molecules-1 are highly expressed in the nucleus tractus solitarii (NTS) of the spontaneously hypertensive rat (SHR), compared to normotensive rats (Wistar-Kyoto rats: WKY), suggesting that the NTS of SHR may exhibit an abnormal inflammatory state. In the present study, we tested whether gene expression of inflammatory markers such as cytokines and chemokines is altered in the NTS of SHR and whether this contributes to the hypertensive phenotype in the SHR.

METHODS

We have performed RT Profiler PCR arrays in the NTS of SHR and WKY, which were designed to specifically target major cytokines/chemokines and their receptors. To validate PCR array results quantitative RT-PCR was performed. Microinjection studies using anesthetized rats were also carried out to examine whether validated inflammatory molecules exhibit functional roles on cardiovascular regulation at the level of the NTS.

RESULTS

Five inter-related transcripts were identified to be differentially expressed between the NTS of SHR and WKY. They include chemokine (C-C motif) ligand 5 (Ccl5), and its receptors, chemokine (C-C motif) receptor 1 and 3. All of them were down-regulated in the NTS of SHR compared to WKY. Moreover, we found that the protein Ccl5 microinjected into the NTS significantly decreased baseline arterial pressure and that the response was greater in the SHR compared to the WKY (-33.2±3.2 vs. -8.8±1.6 mmHg, P<0.001), demonstrating that its down-regulation in the NTS may contribute to hypertension in the SHR.

CONCLUSION

We suggest that gene expression of specific chemokines may be down-regulated to protect further inflammatory reactions in the NTS of SHR at the expense of arterial hypertension.

Combination of antibodies inhibits accelerated rejection mediated by memory T cells in xenoantigen-primed mice

BACKGROUND

Donor-reactive memory T cells are known to accelerate allograft rejection; in our previous study, we reported that combined monoclonal antibodies (mAbs) could prolong islet allograft survival in alloantigen-primed mice. In this study, we examine the effects of donor-reactive memory T cells on the xenograft survival and methods to prolong the islet graft survival.

METHODS

To collect donor-reactive T cells, we performed full-thickness rat skin xenografting on BALB/c mice and isolated the T cells from the mice after 6-8 weeks. These cells were then adoptively transferred to syngenic mice 1 day before rat-to-mouse islet transplantation. Three experimental groups were established in the adoptive transfer model: recipient mice treated with isotype mAbs (isotype group); mice treated with anti-CD40L mAb (anti-CD40L group); and mice treated with anti-CD40L, anti-OX40L, and anti-CD122 mAbs (3-combined group).

RESULTS

Lewis rat islet xenografts transplanted in naïve mice showed a mean survival time (MST) of 12.8 days, while the graft rejection was accelerated if the recipient mice were treated with adoptively transferred donor-reactive T cells (MST, 8.67 days). Treatment with anti-CD40L mb could not reverse the accelerated rejection (MST, 9.3 days). However, when anti-CD40L mb was combined with anti-OX40L and anti-CD122 mAbs, there was a considerable increase in the MST, which was 72.2 days. Compared to the isotype group, the 3-combined group had significantly lesser proportion of memory T cells and greater proportion of regulatory T cells (Tregs) in the spleen. Meanwhile, in the 3-combined group, the production of anti-rat antibodies was markedly inhibited.

CONCLUSION

  Treatment with a combination of antibodies could significantly reverse the accelerated rejection mediated by donor-reactive memory T cells by inhibiting cellular and humoral immune responses.

A common polymorphism in the promoter region of the TNFSF4 gene is associated with lower allele-specific expression and risk of myocardial infarction

Background

The TNFSF4/TNFRSF4 system, along with several other receptor-ligand pairs, is involved in the recruitment and activation of T-cells and is therefore tentatively implicated in atherosclerosis and acute coronary syndromes. We have previously shown that genetic variants in TNFSF4 are associated with myocardial infarction (MI) in women. This prompted functional studies of TNFSF4 expression.

Methods and Results

Based on a screening of the TNFSF4 genomic region, a promoter polymorphism (rs45454293) and a haplotype were identified, conceivably involved in gene regulation. The rs45454293T-allele, in agreement with the linked rs3850641G-allele, proved to be associated with increased risk of MI in women. Haplotype-specific chromatin immunoprecipitation of activated polymerase II, as a measure of transcriptional activity in vivo, suggested that the haplotype including the rs45454293 and rs3850641 polymorphisms is functionally important, the rs45454293T- and rs3850641G-alleles being associated with lower transcriptional activity in cells heterozygous for both polymorphisms. The functional role of rs45454293 on transcriptional levels of TNFSF4 was clarified by luciferase reporter assays, where the rs45454293T-allele decreased gene expression when compared with the rs45454293C-allele, while the rs3850641 SNP did not have any effect on TNFSF4 promoter activity. Electromobility shift assay showed that the rs45454293 polymorphism, but not rs3850641, affects the binding of nuclear factors, thus suggesting that the lower transcriptional activity is attributed to binding of one or more transcriptional repressor(s) to the T-allele.

Conclusions

Our data indicate that the TNFSF4 rs45454293T-allele is associated with lower TNFSF4 expression and increased risk of MI.

Increased OX40 and soluble OX40 ligands in children with Henoch-Schonlein purpura: association with renal involvement

Henoch-Schonlein purpura (HSP) is one of the most common types of vasculitis disorders in childhood and is characterized by a rash, arthritis, abdominal pain, and renal involvement. T-lymphocyte activation is considered to play a critical role in vasculitis. However, the regulation of the T cells in HSP remains poorly understood. In this study, OX40/OX40L (CD134/CD252) costimulatory pathway, which could promote T-cell activation and long survival, was investigated. Results from 32 HSP patients and 25 healthy donors revealed that the freshly isolated CD4(+) T cells from patients with HSP expressed higher OX40 than that of the cells from healthy individuals. The levels of soluble OX40L (sOX40L) in the sera of patients with HSP were also much higher than the controls. Importantly, significantly elevated levels of OX40 on CD4(+) T cells and sOX40L in sera were detected in patients with HSP with nephritis compared to patients without nephritis, indicating both OX40 upregulation and sOX40L increase were closely associated with disease activity of the patients. Thus, circulating sOX40L could provide excessive costimulatory signal for CD4(+) OX40(+) T-cell activation, and OX40/OX40L signal might contribute to the development of HSP disease.

Anti-OX40 prevents effector T-cell accumulation and CD8+ T-cell mediated skin allograft rejection

BACKGROUND

OX40 is a member of the tumor necrosis factor receptor superfamily and is a potent T-cell costimulatory molecule. Although the impact of blockade of the OX40-OX40L pathway has been documented in models of autoimmune disease, the effect on allograft rejection is less well defined.

METHODS

The expression of OX40 and impact of OX40 blockade on BM3 T cells (H2Kb-reactive, T-cell receptor-transgenic) after stimulation with alloantigen were assessed in vitro by the incorporation of 3H-thymidine and flow cytometry. In vivo, naïve BM3 or polyclonal CD8+ T cells were transferred into syngeneic recombinase-activating gene(-/-) mice, which received an H2b+ skin allograft with and without anti-OX40. Skin allograft survival was monitored, and the proliferation, number, and phenotype of BM3 T cells were determined using flow cytometry.

RESULTS

In vitro allogeneic stimulation of CD8+ T cells resulted in OX40 expression, the blockade of which was found to partially inhibit 3H-thymidine incorporation as a result of increased cell death among activated T cells. Similarly, in vivo, anti-OX40 prevented skin allograft rejection mediated by CD8+ T cells. However, after cessation of anti-OX40 therapy, skin allografts were eventually rejected indicating that tolerance had not been induced. Correlating with the in vitro data, analysis of lymph nodes draining skin allografts revealed that OX40 blockade had no effect on the activation and proliferation of BM3 T cells but rather resulted in diminished effector T-cell accumulation.

CONCLUSION

Taken together, these data demonstrate that anti-OX40 attenuates CD8+ T-cell responses to alloantigen by reducing the pool of effector T cells, suggesting that this may be a worthwhile adjunct to preexisting costimulatory molecule-blocking regimens.

Signaling through OX40 enhances antitumor immunity

The existence of tumor-specific T cells, as well as their ability to be primed in cancer patients, confirms that the immune response can be deployed to combat cancer. However, there are obstacles that must be overcome to convert the ineffective immune response commonly found in the tumor environment to one that leads to sustained destruction of tumor. Members of the tumor necrosis factor (TNF) superfamily direct diverse immune functions. OX40 and its ligand, OX40L, are key TNF members that augment T-cell expansion, cytokine production, and survival. OX40 signaling also controls regulatory T-cell differentiation and suppressive function. Studies over the past decade have demonstrated that OX40 agonists enhance antitumor immunity in preclinical models using immunogenic tumors; however, treatment of poorly immunogenic tumors has been less successful. Combining strategies that prime tumor-specific T cells together with OX40 signaling could generate and maintain a therapeutic antitumor immune response.

Suppression of CCR5-tropic HIV type 1 infection by OX40 stimulation via enhanced production of β-chemokines

To elucidate the immunological role for the costimulatory molecule OX40 against the early stage of HIV-1 infection, fresh peripheral blood mononuclear cells (PBMCs) from normal donors were stimulated with immobilized anti-CD3 monoclonal antibody (mAb) together with soluble anti-CD28 mAb for 24 h, infected with CCR5-tropic (R5) HIV-1, and then cocultured in the presence or absence of OX40 ligand (OX40L). Results of these studied showed that OX40 stimulation led to a marked reduction in levels of p24, the frequency of intracellular p24(+) cells, as well as HIV-1-mediated syncytium formation. The suppression was reversed by anti-OX40L mAb. The mechanism underlying the R5 HIV-1 suppression was shown to be mediated in part by the CCR5-binding β-chemokines RANTES, MIP-1α, and MIP-1β, since the effect of the OX40 stimulation was reversed by a neutralizing antibody mixture against these three β-chemokines. Thus, OX40 stimulation enhanced the production of these CCR5-binding β-chemokines by the activated PBMCs and subsequently down-modulated CCR5 expression on the activated CD4(+) T cells. Taken together, the present data revealed a new role for OX40 in HIV-1 infection and documents the fact that OX40 stimulation suppresses the infection of primary activated PBMCs with R5 HIV-1 via enhanced production of R5 HIV-1 suppressing β-chemokines.

The role of OX40 (CD134) in T-cell memory generation

Memory T-cell generation is limited by activation-induced cell death during the effector T-cell stage. Cell surface proteins are known to transmit signals that either accentuate or limit T-cell death after activation. This chapter will focus on the TNF-receptor family member OX40, which is expressed on effector T cells and when engaged greatly enhances survival of T cells leading to increased memory T-cell generation. Targeting OX40 in vivo can alter the fate ofT-cell survival. Enhancing OX40 signaling during Ag priming through agonists increases memory T-cell development, while blocking OX40 signaling decreases the memory T-cell pool. These two opposing outcomes provide therapeutic tools for blocking inflammation in autoimmune conditions and enhancing immunity in hosts harboring cancer or chronic pathogens. OX40 agonists and antagonists are in the first stages of human clinical trials and their therapeutic potential will soon be realized.

OX40 ligand regulates inflammation and mortality in the innate immune response to sepsis

The initial phase of sepsis is characterized by massive inflammatory cytokine production that contributes to multisystem organ failure and death. Costimulatory molecules are a class of receptors capable of regulating cytokine production in adaptive immunity. Recent studies described their presence on neutrophils and monocytes, suggesting a potential role in the regulation of cytokine production in innate immunity. The purpose of this study was to determine the role for OX40-OX40 ligand (OX40L) interaction in the innate immune response to polymicrobial sepsis. Humans with sepsis demonstrated upregulation of OX40L on monocytes and neutrophils, with mortality and intensive care unit stay correlating with expression levels. In an animal model of polymicrobial sepsis, a direct role for OX40L in regulating inflammation was indicated by improved survival, decreased cytokine production, and a decrease in remote organ damage in OX40L(-/-) mice. The finding of similar results with an OX40L Ab suggests a potential therapeutic role for OX40L blockade in sepsis. The inability of anti-OX40L to provide significant protection in macrophage-depleted mice establishes macrophages as an indispensable cell type within the OX40/OX40L axis that helps to mediate the clinical signs of disease in sepsis. Conversely, the protective effect of anti-OX40L Ab in RAG1(-/-) mice further confirms a T cell-independent role for OX40L stimulation in sepsis. In conclusion, our data provide an in vivo role for the OX40/OX40L system in the innate immune response during polymicrobial sepsis and suggests a potential beneficial role for therapeutic blockade of OX40L in this devastating disorder.

Pharmacotherapy: concepts of pathogenesis and emerging treatments. Co-stimulation and T cells as therapeutic targets

Full activation and differentiation of resting T cells into effector T cells requires at least two signals, the first through engagement of the T cell antigen receptor (TCR) by the antigen-major histocompatibility complex (MHC) on antigen-presenting cells (APCs), and the second by engagement of co-stimulatory molecules such as CD28, on T cells by ligands such as CD80/86 on APCs. Effector T cell differentiation is associated with proliferation, secretion of cytokines and expression of additional surface molecules. These inducible structures may have stimulatory (ICOS, OX40 and 4-1BB) or inhibitory (cytotoxic T-lymphocyte antigen (CTLA)-4) potential. To the extent that T cells have a role in particular immune-mediated diseases, interruption of T cell co-stimulation is a potentially worthwhile approach to the treatment of those conditions. This article summarises the experience in treating rheumatological disease by perturbation of T cell co-stimulation, and also describes structures that could be future targets for this type of therapeutic approach.

Costimulatory molecule OX40/OX40L expression in ductal carcinoma in situ and invasive ductal carcinoma of breast: an immunohistochemistry-based pilot study

OX40, a membrane-bound member of the tumor-necrosis-factor-receptor (TNFR) superfamily, plays an important role in proliferation, survival and infiltration of activated T cells via binding to OX40L. Recent studies indicate that OX40/OX40L system mediates the adhesion and infiltration of adult T cell leukemia (ATL). Previously, we detected OX40 expression in breast carcinoma cell lines and tissues. The correlation of expression of OX40 and OX40L and clinical features in breast carcinogenesis, however, has not been well characterized. The expression of OX40 and OX40L in 107 invasive ductal carcinomas (IDCa), 9 ductal carcinomas in situ (DCIS), and 31 fibroadenomas from breast tissues and its relationship with the clinical features were determined using immunohistochemistry (peroxidase-conjugated polymer method, ChemMate™ Envision™ Detection kit). The positive immunostaining rates for OX40 in IDCa, DCIS and fibroadenomas from breast tissues were 85.0%, 66.7% and 38.7% respectively, showing a significant difference in OX40 expression among IDCa, DCIS and fibroadenoma of breast (z=5.206, P=0.001). Increased staining intensity of OX40 was associated with TNM stages (z=2.112, P=0.017). Meanwhile, a relation of OX40 expression with lymph node metastatic status in IDCa was found (P=0.041). The expression of OX40L did not show any obvious difference among IDCa, DCIS and fibroadenomas from breast tissues. OX40L expression was also not related to histopathological parameters in IDCa except for progesterone receptor (PR) being positive (P=0.005). However, a high coincidental positive rate for OX40 and OX40L was observed in biopsy samples with IDCa (P=0.017, Kappa=0.231). The present results suggest that high OX40 expression may be associated with malignant transformation, progression, invasion and metastasis in breast cancer biology.

The mandatory role of IL-10-producing and OX40 ligand-expressing mature Langerhans cells in local UVB-induced immunosuppression

The mechanism underlying the local UVB-induced immunosuppression is a central issue to be clarified in photoimmunology. There have been reported a considerable number of cells and factors that participate in the sensitization phase-dependent suppression, including Langerhans cells (LCs), regulatory T cells, IL-10, and TNF-alpha. The recent important finding that LC-depleted mice rather exhibit enhanced contact hypersensitivity responses urged us to re-evaluate the role of LCs along with dermal dendritic cells (dDCs) in the mechanism of UVB-induced immunosuppression. We studied the surface expression of OX40 ligand (OX40L) and the intracellular expression of IL-10 in LCs and dDCs from UVB-irradiated (300 mJ/cm(2)) skin of BALB/c mice and those migrating to the regional lymph nodes from UVB-irradiated, hapten-painted mice. In epidermal and dermal cell suspensions prepared from the UVB-irradiated skin, LCs expressed OX40L as well as CD86 and produced IL-10 at a higher level than Langerin(-) dDCs. The UVB-induced immunosuppression was attenuated by the administration of IL-10-neutralizing or OX40L-blocking Abs. In mice whose UVB-irradiated, hapten-painted skin was dissected 1 d after hapten application, the contact hypersensitivity response was restored, because this treatment allowed dDCs but not LCs to migrate to the draining lymph nodes. Moreover, LC-depleted mice by using Langerin-diphtheria toxin receptor-knocked-in mice showed impaired UVB-induced immunosuppression. These results suggest that IL-10-producing and OX40L-expressing LCs in the UVB-exposed skin are mandatory for the induction of Ag-specific regulatory T cells.

T cells in ANCA-associated vasculitis: what can we learn from lesional versus circulating T cells?

Anti-neutrophil cytoplasmic antibody (ANCA) - associated vasculitis (AAV) is a life-threatening autoimmune disease characterized by an antibody-mediated glomerulonephritis and necrotizing vasculitis. Apart from antibodies, T cells are also involved in disease pathogenesis. This review stresses the hallmarks of T cell-mediated pathology in AAV and highlights the characteristics of lesional and circulating T cells in the immune response in AAV. Circulating effector T-cell populations are expanded and are in a persistent state of activation. Circulating regulatory T-cell subsets are less well characterized but seem to be impaired in function. Lesional effector T cells are present in granulomas, vasculitic lesions, and nephritis. Lesional T cells usually show pro-inflammatory properties and promote granuloma formation. Apart from T cells, dendritic cells are abundantly present at the sites of inflammation and locally orchestrate the immune response. Targeting the above-mentioned T cell-mediated disease mechanisms will potentially provide powerful therapeutic tools for AAV.

Control of immunity by the TNFR-related molecule OX40 (CD134)

TNFR/TNF superfamily members can control diverse aspects of immune function. Research over the past 10 years has shown that one of the most important and prominent interactions in this family is that between OX40 (CD134) and its partner OX40L (CD252). These molecules strongly regulate conventional CD4 and CD8 T cells, and more recent data are highlighting their ability to modulate NKT cell and NK cell function as well as to mediate cross-talk with professional antigen-presenting cells and diverse cell types such as mast cells, smooth muscle cells, and endothelial cells. Additionally, OX40-OX40L interactions alter the differentiation and activity of regulatory T cells. Blocking OX40L has produced strong therapeutic effects in multiple animal models of autoimmune and inflammatory disease, and, in line with a prospective clinical future, reagents that stimulate OX40 signaling are showing promise as adjuvants for vaccination as well as for treatment of cancer.

OX40-OX40 ligand interaction in T-cell-mediated immunity and immunopathology

T-cell activation is mediated not only by antigen stimulation through T-cell receptors but also by costimulatory signals through costimulatory molecules. Among several costimulatory molecules, the tumor necrosis factor (TNF) receptor family member OX40 plays a key role in the survival and homeostasis of effector and memory T cells. According to the conventional understanding of OX40 costimulation, an interaction between OX40 and OX40 ligand (OX40L) occurs when activated T cells bind to professional antigen-presenting cells (APCs). The T-cell functions, including cytokine production, expansion, and survival, are then enhanced by the OX40 costimulatory signals. Over the last half-decade, evidence has accumulated that OX40 signals are critical for controlling the function and differentiation of Foxp3(+) regulatory T cells, indicating a new aspect of OX40-mediated autoimmunity. Furthermore, the expression of OX40L by mast cells was shown to be important for controlling inflammation through regulatory T-cell function. Besides the essential role played by OX40 signaling in generating memory CD4 T cells, recent reports show that it also has a unique role in generating memory CD8 T cells. In addition, recent genome-wide association studies have identified single-nucleotide polymorphisms of the OX40L and OX40 genes that are related to cardiovascular diseases and SLE, providing direct evidence for the involvement of the OX40-OX40L interaction in human diseases. Here, we review recent progress on how the OX40-OX40L interaction regulates T-cell tolerance, peripheral T-cell homeostasis, and T-cell-mediated inflammatory diseases.

Control of immunity by the TNFR-related molecule OX40 (CD134)

TNFR/TNF superfamily members can control diverse aspects of immune function. Research over the past 10 years has shown that one of the most important and prominent interactions in this family is that between OX40 (CD134) and its partner OX40L (CD252). These molecules strongly regulate conventional CD4 and CD8 T cells, and more recent data are highlighting their ability to modulate NKT cell and NK cell function as well as to mediate cross-talk with professional antigen-presenting cells and diverse cell types such as mast cells, smooth muscle cells, and endothelial cells. Additionally, OX40-OX40L interactions alter the differentiation and activity of regulatory T cells. Blocking OX40L has produced strong therapeutic effects in multiple animal models of autoimmune and inflammatory disease, and, in line with a prospective clinical future, reagents that stimulate OX40 signaling are showing promise as adjuvants for vaccination as well as for treatment of cancer.

The role of OX40-mediated co-stimulation in T-cell activation and survival

The extent of T-cell activation, proliferation, and survival that follows T-cell receptor (TCR) ligation is controlled by several factors, including the strength of TCR stimulation, the availability of prosurvival cytokines, and the presence or absence of co-stimulatory signals. In addition to engagement of the CD28 co-stimulatory receptor by its natural ligands, B7.1 (CD80) and B7.2 (CD86), recent work has begun to elucidate the mechanisms by which signaling through the OX40 (CD134) co-stimulatory receptor, a member of the tumor necrosis factor receptor (TNFR) superfamily, affects T-cell responses. Importantly, OX40 ligation has been shown to augment CD4 and CD8 T-cell clonal expansion, effector differentiation, survival, and in some cases, abrogate the suppressive activity of regulatory FoxP3+CD25+CD4+ T cells. In this review, we focus on the mechanisms regulating OX40 expression on activated T cells as well as the role of OX40-mediated co-stimulation in boosting T-cell clonal expansion, effector differentiation, and survival.

Costimulatory and coinhibitory receptors in anti-tumor immunity

SUMMARY

Despite the expression of antigens by tumor cells, spontaneous immune-mediated rejection of cancer seems to be a rare event. T-cell receptor engagement by peptide/major histocompatibility complexes constitutes the main signal for the activation of naive T cells but is not sufficient to initiate a productive generation and maintenance of effector cells. Full activation of T cells requires additional signals driven by costimulatory molecules present on activated antigen-presenting cells but rarely on tumors. Following the discovery of B7-1 (CD80), several other costimulatory molecules have been shown to contribute to T-cell activation and have relevance for improving anti-tumor immunity. Moreover, increasing the understanding of coinhibitory receptors has highlighted key additional pathways that can dominantly inhibit anti-tumor T-cell function. Improving positive costimulation, and interfering with negative regulation, continues to represent an attractive immunotherapeutic approach for the treatment of cancer. This review focuses upon those pathways with the highest potential for clinical application in human cancer patients.

The significance of OX40 and OX40L to T-cell biology and immune disease

SUMMARY

OX40 (CD134) and its binding partner, OX40L (CD252), are members of the tumor necrosis factor receptor/tumor necrosis factor superfamily and are expressed on activated CD4(+) and CD8(+) T cells as well as on a number of other lymphoid and non-lymphoid cells. Costimulatory signals from OX40 to a conventional T cell promote division and survival, augmenting the clonal expansion of effector and memory populations as they are being generated to antigen. OX40 additionally suppresses the differentiation and activity of T-regulatory cells, further amplifying this process. OX40 and OX40L also regulate cytokine production from T cells, antigen-presenting cells, natural killer cells, and natural killer T cells, and modulate cytokine receptor signaling. In line with these important modulatory functions, OX40-OX40L interactions have been found to play a central role in the development of multiple inflammatory and autoimmune diseases, making them attractive candidates for intervention in the clinic. Conversely, stimulating OX40 has shown it to be a candidate for therapeutic immunization strategies for cancer and infectious disease. This review provides a broad overview of the biology of OX40 including the intracellular signals from OX40 that impact many aspects of immune function and have promoted OX40 as one of the most prominent costimulatory molecules known to control T cells.

OX40-enhanced tumor rejection and effector T cell differentiation decreases with age

OX40 agonists have potent immunotherapeutic effects against a variety of murine tumors, yet it is unclear the role that age-related immune senescence plays on their efficacy. We found that middle-aged and elderly tumor-bearing mice (12 and 20 mo old, respectively) treated with anti-OX40 were less responsive compared with young mice 6 mo or less of age. Decreased tumor-free survival was observed in both male and female mice, and was not due to changes in the surface expression of OX40 on T cells in older animals. Enumeration of cytokine-producing effector T cells in tumor-bearing mice revealed a significant decline in these cells in the older mice treated with anti-OX40 compared with their younger counterparts. The decrease of this critical T cell population in middle-aged mice was not a result of inherent T cell deficiencies, but was revealed to be T cell extrinsic. Finally, combining IL-12, an innate cytokine, with anti-OX40 boosted levels of differentiated effector T cells in the older anti-OX40-treated mice and partially restored the defective antitumor responses in the middle-aged mice. Our data show that the anti-OX40-enhancement of tumor immunity and effector T cell numbers is decreased in middle-aged mice and was partially reversed by coadministration of the proinflammatory cytokine IL-12.

OX40 (CD134) and OX40L

The interaction between OX40 and OX40L plays an important role in antigen-specific T-cell expansion and survival. While OX40 is expressed predominantly on T-lymphocytes early after antigen activation, OX40L is expressed on activated antigen presenting cells and endothelial cells within acute inflammatory environments. We discuss here how ligation of OX40 by OX40L leads to enhanced T-cell survival, along with local inflammatory responses that appear critical for both effective T-cell mediated responses and chronic immune pathologies. We describe how interventions that block or mimic the OX40-OX40L interaction can be applied to treat autoimmune diseases or enhance anti-tumor immune responses. The clinically relevant properties of these agents emphasize the importance of this particular TNFSF-TNFSF in health and disease.

OX40 costimulation prevents allograft acceptance induced by CD40-CD40L blockade

Disrupting the CD40-CD40L costimulation pathway promotes allograft acceptance in many settings. Herein, we demonstrate that stimulating OX40 overrides cardiac allograft acceptance induced by disrupting CD40-CD40L interactions. This effect of OX40 stimulation was dependent on CD4(+) T cells, which in turn provided help for CD8(+) T cells and B cells. Allograft rejection was associated with donor-reactive Th1 and Th2 responses and an unconventional granulocytic infiltrate and thrombosis of the arteries. Interestingly, OX40 stimulation induced a donor-reactive IgG class switch in the absence of CD40-CD40L interactions, and the timing of OX40 stimulation relative to transplantation affected the isotype of donor-reactive Ab produced. Inductive OX40 stimulation induced acute graft rejection, which correlated with both IgG1 and IgG2a deposition within the graft. Once graft acceptance was established following CD40-CD40L blockade, delayed OX40 stimulation did not induce acute allograft rejection despite priming of graft-reactive Th1 and Th2. Rather, chronic rejection was induced, which was characterized by IgG1 but not IgG2a deposition within the graft. These studies reveal both redundancy and key differences in function among costimulatory molecules that manifest in distinct pathologies of allograft rejection. These findings may help guide development of therapeutics aimed at promoting graft acceptance in transplant recipients.

Association of the co-stimulator OX40L with systemic lupus erythematosus

The archetypal systemic autoimmune disease systemic lupus erythematosus (SLE) has incompletely understood pathogenesis, although evidence suggests a strong genetic component. Unlike organ-specific autoimmune diseases such as type 1 diabetes, the genetics of lupus are not as dominated by the effect of a single locus. Undoubtedly, the major histocompatibility complex is the greatest and most consistent genetic risk factor in SLE susceptibility; however, recent candidate gene and whole genome association (WGA) studies have identified several other genes that are likely to advance our understanding of this complex disease. One of these, the TNF superfamily member OX40L, interacts with its unique receptor OX40, to maintain T cell memory by providing a late-stage co-stimulatory signal to sustain the survival of activated T cells. The precise immunological consequences are yet to be determined; however, signalling through OX40-OX40L is bidirectional and the reverse signalling pathway via OX40L may quantitatively enhance B cell proliferation to augment the B cell hyperactivity found in SLE. Like OX40L, several genes recently identified in WGA studies are components of B cell pathways. Collectively, these genes will help us to unravel the mechanisms by which aberrant B cell signalling results in lupus pathogenesis.