OX40: targeted immunotherapy--implications for tempering autoimmunity and enhancing vaccines

Pathogenic roles of follicular helper T cells in IgG4-related disease and implications for potential therapy

IgG4-related disease (IgG4-RD) is a recently described autoimmune disorder characterized by elevated serum IgG4 levels and tissue infiltration of IgG4+ plasma cells in multiple organ systems. Recent advancements have significantly enhanced our understanding of the pathological mechanism underlying this immune-mediated disease. T cell immunity plays a crucial role in the pathogenesis of IgG4-RD, and follicular helper T cells (Tfh) are particularly important in germinal center (GC) formation, plasmablast differentiation, and IgG4 class-switching. Apart from serum IgG4 concentrations, the expansion of circulating Tfh2 cells and plasmablasts may also serve as novel biomarkers for disease diagnosis and activity monitoring in IgG4-RD. Further exploration into the pathogenic roles of Tfh in IgG4-RD could potentially lead to identifying new therapeutic targets that offer more effective alternatives for treating this condition. In this review, we will focus on the current knowledge regarding the pathogenic roles Tfh cells play in IgG4-RD and outline potential therapeutic targets for future clinical intervention.

Recent Advances in the Role of Arid5a in Immune Diseases and Cancer

AT-rich interactive domain 5a (Arid5a) is a nucleic acid binding protein. In this review, we highlight recent advances in the association of Arid5a with inflammation and human diseases. Arid5a is known as a protein that performs dual functions. In in vitro and in vivo studies, it was found that an inflammation-dependent increase in Arid5a expression mediates both transcriptional and post-transcriptional regulatory effects that are implicated in immune regulation and cellular homeostasis. A series of publications demonstrated that inhibiting Arid5a augmented several processes, such as preventing septic shock, experimental autoimmune encephalomyelitis, acute lung injury, invasion and metastasis, immune evasion, epithelial-to-mesenchymal transition, and the M1-like tumor-associated macrophage (TAM) to M2-like TAM transition. In addition, Arid5a controls adipogenesis and obesity in mice to maintain metabolic homeostasis. Taken together, recent progress indicates that Arid5a exhibits multifaceted, both beneficial and detrimental, roles in health and disease and suggest the relevance of Arid5a as a potential therapeutic target.

OX40L blockade cellular nanovesicles for autoimmune diseases therapy

Current clinical agents for autoimmunity disorders treatment often cause substantial adverse effects and safety concerns, owing to non-specific immune modulation. Due to the prominent contribution of effector T cells in pathogenesis of rheumatoid arthritis (RA) and inflammatory bowel disease (IBD), and preferential location of co-stimulatory receptor-ligand pair OX40-OX40L at the inflamed sites, selectively targeting autoaggressive T cells by blockade OX40-OX40L, might represent an alternative strategy. Herein, we developed a new strategy to antagonize OX40-OX40L interaction by engineering a cell membrane derived nanovesicles (NVs) expressing OX40 receptors (OX40 NVs), and explored their potential for autoimmune disorders therapy. OX40 NVs showed specific binding capability to inflamed HUVECs in vitro, it also possessed distinct arthritic-targeting capacity in RA inflamed joints, and preferential accumulation in IBD inflamed colon. OX40 NVs efficiently suppressed the progression of both RA and IBD diseases through reducing CD4⁺OX40⁺ T cells population, and proinflammatory cytokines (i.e., TNF-α and IL-1β), while reinforcing Tregs immune-suppressive effect, with superior therapeutic efficacy than anti-OX40L. Additionally, dexamethasone (DEX) loading can further enhance the potential of OX40 NVs for RA treatment. Owing to their preferential localization to inflamed sites, and potent immune-suppression ability, targeting OX40-OX40L blockade by OX40 NVs for autoimmune therapy is highly promising.

Small Molecule Cyclotriazadisulfonamide Abrogates the Upregulation of the Human Receptors CD4 and 4-1BB and Suppresses In Vitro Activation and Proliferation of T Lymphocytes

The small molecule cyclotriazadisulfonamide (CADA) down-modulates the human CD4 receptor, an important factor in T cell activation. Here, we addressed the immunosuppressive potential of CADA using different activation models. CADA inhibited lymphocyte proliferation with low cellular toxicity in a mixed lymphocyte reaction, and when human PBMCs were stimulated with CD3/CD28 beads, phytohemagglutinin or anti-CD3 antibodies. The immunosuppressive effect of CADA involved both CD4⁺ and CD8⁺ T cells but was, surprisingly, most prominent in the CD8⁺ T cell subpopulation where it inhibited cell-mediated lympholysis. Immunosuppression by CADA was characterized by suppressed secretion of various cytokines, and reduced CD25, phosphoSTAT5 and CTPS-1 levels. We discovered a direct down-modulatory effect of CADA on 4-1BB (CD137) expression, a survival factor for activated CD8⁺ T cells. More specifically, CADA blocked 4‑1BB protein biosynthesis by inhibition of its co-translational translocation into the ER in a signal peptide-dependent way. Taken together, this study demonstrates that CADA, as potent down-modulator of human CD4 and 4‑1BB receptor, has promising immunomodulatory characteristics. This would open up new avenues toward chemotherapeutics that act as selective protein down-modulators to treat various human immunological disorders.

Arid5a, an RNA-Binding Protein in Immune Regulation: RNA Stability, Inflammation, and Autoimmunity

AT-rich interactive domain 5A (ARID5A/Arid5a) is a known cofactor of transcription factors (TFs) that contributes to cell growth and differentiation. It has recently been recognized for its unique function in the stabilization of mRNA, which is associated with inflammatory autoimmune diseases. Studies have revolutionized our understanding of the post-transcriptional regulation of inflammatory genes by revealing the fundamental events underpinning novel functions and activities of Arid5a. We review current research on Arid5a, which has focused our attention towards the therapeutic potential of this factor in the putative treatment of inflammatory and autoimmune disorders, including experimental autoimmune encephalomyelitis and sepsis in mice.

Arid5a Regulation and the Roles of Arid5a in the Inflammatory Response and Disease

Abnormal gene expression patterns underlie many diseases that represent major public health concerns and robust therapeutic challenges. Posttranscriptional gene regulation by RNA-binding proteins (RBPs) is well-recognized, and the biological functions of RBPs have been implicated in many diseases, such as autoimmune diseases, inflammatory diseases, and cancer. However, a complete understanding of the regulation mediated by several RBPs is lacking. During the past few years, a novel role of AT-rich interactive domain-containing protein 5a (Arid5a) as an RBP is being investigated in the field of immunology owing to binding of Arid5a protein to the 3' untranslated region (UTR) of Il-6 mRNA. Indeed, Arid5a is a dynamic molecule because upon inflammation, it translocates to the cytoplasm and stabilizes a variety of inflammatory mRNA transcripts, including Il-6, Stat3, Ox40, T-bet, and IL-17-induced targets, and contributes to the inflammatory response and a variety of diseases. TLR4-activated NF-κB and MAPK pathways are involved in regulating Arid5a expression from synthesis to degradation, and even a slight alteration in these pathways can lead to intense production of inflammatory molecules, such as IL-6, which may further contribute to the development of inflammatory diseases such as sepsis and experimental autoimmune encephalomyelitis. This review highlights the regulation of the Arid5a expression and function. Additionally, recent findings on Arid5a are discussed to further our understanding of this molecule, which may be a promising therapeutic target for inflammatory diseases.

Arid5a stabilizes OX40 mRNA in murine CD4+ T cells by recognizing a stem-loop structure in its 3'UTR

AT-rich interactive domain-containing protein 5a (Arid5a) is an RNA-binding protein (RBP) required for autoimmunity via stabilization of interleukin-6 (Il6) and signal transducer and activator of transcription 3 (STAT3) mRNAs. However, the roles of Arid5a in Th17 cells and its association with autoimmunity remain unknown. Here, we show that the levels of Arid5a and OX40 are correlated in CD4⁺ T cells under Th17 conditions in an IL-6-dependent manner. Lack of Arid5a in T cells reduced OX40 expression levels and repressed IL-17 production in response to OX40 ligation. Arid5a stabilized OX40 mRNA by recognizing the alternative decay element (ADE)-like stem-loop (SL) in the 3' untranslated region (3'UTR). Interestingly, Arid5a impaired the RNA-destabilizing functions of Regnase-1 and Roquin-1 on OX40 ADE-like SL. In EAE, Arid5a-deficient mice exhibited resistance to EAE, with reduced OX40 expression in CD4⁺ T cells, and the number of CD4⁺ CD45⁺ T cells was decreased in CNS. Furthermore, ameliorated EAE was induced by adoptive transfer of Arid5a^-/- encephalitogenic CD4⁺ T cells expressing less OX40 mRNA and producing less IL-17. In conclusion, our findings indicate that the Arid5a/OX40 axis in CD4⁺ T cells may have important implications in pathogenesis of autoimmune diseases such as EAE.

Aptamers for CD Antigens: From Cell Profiling to Activity Modulation

Nucleic acid-based aptamers are considered to be a promising alternative to antibodies because of their strong and specific binding to diverse targets, fast and inexpensive chemical synthesis, and easy labeling with a fluorescent dye or therapeutic agent. Cluster of differentiation (CD) proteins are among the most popular antigens for aptamers on the cell surface. These anti-CD aptamers could be used in cell biology and biomedicine, from simple cell phenotyping by flow cytometry or fluorescent microscopy to diagnosis and treatment of HIV/AIDS to cancer and immune therapies. The unique feature of aptamers is that they can act simultaneously as an agonist and antagonist of CD receptors depending on a degree of aptamer oligomerization. Aptamers can also deliver small interfering RNA to silence vital genes in CD-positive cells. In this review, we summarize nucleic acid sequences of anti-CD aptamers and their use, which have been validated in multiple studies.

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.

Role of Tumor Necrosis Factor Superfamily in Neuroinflammation and Autoimmunity

Tumor necrosis factor superfamily (TNFSF) molecules play an important role in the activation, proliferation, differentiation, and migration of immune cells into the central nervous system (CNS). Several TNF superfamily molecules are known to control alloimmunity, autoimmunity, and immunity. Development of transgenic and gene knockout animals, and monoclonal antibodies against TNFSF molecules have increased our understanding of individual receptor-ligand interactions, and their intracellular signaling during homeostasis and neuroinflammation. A strong clinical association has been observed between TNFSF members and CNS autoimmunity such as multiple sclerosis and also in its animal model experimental autoimmune encephalomyelitis. Therefore, they are promising targets for alternative therapeutic options to control autoimmunity. Although, TNFSF ligands are widely distributed and have diverse functions, we have restricted the discussions in this review to TNFSF receptor-ligand interactions and their role in the pathogenesis of neuroinflammation and CNS autoimmunity.

Targeting the adaptive immune system: new strategies in the treatment of atherosclerosis

Atherosclerosis is a lipid-driven chronic inflammatory disease of the arterial wall. Current treatment of atherosclerosis is focused on limiting its risk factors, such as hyperlipidemia or hypertension. However, treatments that target the inflammatory nature of atherosclerosis are still under development. Discovery of novel targets involved in the inflammation of the arterial wall creates opportunities to design new therapeutics that successfully modulate atherosclerosis. Here, we review drug targets that have proven to play pivotal roles in the adaptive immune system in atherosclerosis, and we discuss their potential as novel therapeutics.

K562-Derived Whole-Cell Vaccine Enhances Antitumor Responses of CAR-Redirected Virus-Specific Cytotoxic T Lymphocytes In Vivo

PURPOSE

Adoptive transfer of Epstein-Barr virus (EBV)-specific and cytomegalovirus (CMV)-specific cytotoxic T cells (CTL) genetically modified to express a chimeric antigen receptor (CAR) induces objective tumor responses in clinical trials. In vivo expansion and persistence of these cells are crucial to achieve sustained clinical responses. We aimed to develop an off-the-shelf whole-cell vaccine to boost CAR-redirected virus-specific CTLs in vivo after adoptive transfer. As proof of principle, we validated our vaccine approach by boosting CMV-specific CTLs (CMV-CTLs) engineered with a CAR that targets the GD2 antigen.

EXPERIMENTAL DESIGN

We generated the whole-cell vaccine by engineering the K562 cell line to express the CMV-pp65 protein and the immune stimulatory molecules CD40L and OX40L. Single-cell-derived clones were used to stimulate CMV-CTLs in vitro and in vivo in a xenograft model. We also assessed whether the in vivo boosting of CAR-redirected CMV-CTLs with the whole-cell vaccine enhances the antitumor responses. Finally, we addressed potential safety concerns by including the inducible safety switch caspase9 (iC9) gene in the whole-cell vaccine.

RESULTS

We found that K562-expressing CMV-pp65, CD40L, and OX40L effectively stimulate CMV-specific responses in vitro by promoting antigen cross-presentation to professional antigen-presenting cells (APCs). Vaccination also enhances antitumor effects of CAR-redirected CMV-CTLs in xenograft tumor models. Activation of the iC9 gene successfully induces growth arrest of engineered K562 implanted in mice.

CONCLUSIONS

Vaccination with a whole-cell vaccine obtained from K562 engineered to express CMV-pp65, CD40L, OX40L and iC9 can safely enhance the antitumor effects of CAR-redirected CMV-CTLs.

High expression of OX40 (CD134) and 4-1BB (CD137) molecules on CD4(+)CD25(high) cells in children with type 1 diabetes

PURPOSE

Despite the rapidly rising incidence of diabetes in children, with the highest rise in children<5 years of age, data on mechanisms that trigger severe beta-cells damage are limited. The aim of the study was to assess the frequency of OX40 (CD134) or 4-1BB (CD137) positive cells in the peripheral blood of children with newly diagnosed type 1 diabetes (T1D) in comparison to healthy controls.

MATERIAL/METHODS

The study included 33 children (mean age 7.3 ± 5.4 years) with newly diagnosed T1D and 39 age-matched healthy controls. Separate analysis was performed in children<5 years. Flow cytometric analysis was performed using the following markers: CD4, CD25, CD137, and CD134. Fasting C-peptide level was assessed as well.

RESULTS

The frequency of CD4(+)CD25(high)OX40(+) was higher in T1D children than in controls (median value 3.58% vs. 1.1%, respectively; p=0.003). Moreover, T1D children had higher frequency of CD4(+)CD25(high)4-1BB(+) cells than healthy subjects (median value 5.76% vs. 3.74%, respectively; p=0.037). A significant correlation was noted between the age of diabetic children and the C-peptide level (r=0.54, 95% CI [0.19-0.77], p=0.004). In comparison with age-matched controls, children<5 years had higher frequency of CD4(+)CD25(high)OX40(+) (p=0.004) and CD4(+)CD25(high)4-1BB(+) cells (p=0.079).

CONCLUSIONS

Our study showed higher frequency of both OX40 and 4-1BB positive cells in T1D children in comparison to controls. It seems that observed differences might be more pronounced in children<5 years of age than in older subjects. Further clinical studies are needed to determine the age-related differences in the immune system, in the pathogenesis of T1D.

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.

Tracking and treating activated T cells

Upon activation, T cells of various subsets are the most important mediators in cell-mediated immune responses. Activated T cells play an important role in immune system related diseases such as chronic inflammatory diseases, viral infections, autoimmune disease, transplant rejection, Crohn disease, diabetes, and many more. Therefore, efforts have been made to both visualize and treat activated T cells specifically. This review summarizes imaging approaches and selective therapeutics for activated T cells and gives an outlook on how tracking and treating can be combined into theragnositc agents for activated T cells.

Prenatal alcohol exposure alters the course and severity of adjuvant-induced arthritis in female rats

Prenatal alcohol exposure (PAE) has adverse effects on the development of numerous physiological systems, including the hypothalamic-pituitary-adrenal (HPA) axis and the immune system. HPA hyper-responsiveness and impairments in immune competence have been demonstrated. The present study investigated immune function in PAE females utilizing an adjuvant-induced arthritis (AA) model, widely used as a model of human rheumatoid arthritis. Given the effects of PAE on HPA and immune function, and the known interaction between HPA and immune systems in arthritis, we hypothesized that PAE females would have heightened autoimmune responses, resulting in increased severity of arthritis, compared to controls, and that altered HPA activity might play a role in the immune system changes observed. The data demonstrate, for the first time, an adverse effect of PAE on the course and severity of AA in adulthood, indicating an important long-term alteration in functional immune status. Although overall, across prenatal treatments, adjuvant-injected animals gained less weight, and exhibited decreased thymus and increased adrenal weights, and increased basal levels of corticosterone and adrenocorticotropin, PAE females had a more prolonged course of disease and greater severity of inflammation compared to controls. In addition, PAE females exhibited blunted lymphocyte proliferative responses to concanavalin A and a greater increase in basal ACTH levels compared to controls during the induction phase, before any clinical signs of disease were apparent. These data suggest that prenatal alcohol exposure has both direct and indirect effects on inflammatory processes, altering both immune and HPA function, and likely, the normal interactions between these systems.

Science gone translational: the OX40 agonist story

OX40 (CD134) is a tumor necrosis factor (TNF) receptor expressed primarily on activated CD4(+) and CD8(+) T cells and transmits a potent costimulatory signal when engaged. OX40 is transiently expressed after T-cell receptor engagement and is upregulated on the most recently antigen-activated T cells within inflammatory lesions (e.g. sites of autoimmune destruction and on tumor-infiltrating lymphocytes). Hence, it is an attractive target to modulate immune responses: OX40 blocking agents to inhibit undesirable inflammation or OX40 agonists to enhance immune responses. In regards to this review, OX40 agonists enhance anti-tumor immunity, which leads to therapeutic effects in mouse tumor models. A team of laboratory and clinical scientists at the Providence Cancer Center has collaborated to bring the preclinical observations in cancer models from the bench to the bedside. This review describes the journey from in vitro experiments through preclinical mouse models to the successful translation of the first OX40 agonist to the clinic for the treatment of patients with cancer.

Targeting TNF superfamily members for therapeutic intervention in rheumatoid arthritis

Rheumatoid arthritis (RA) is an inflammatory disease is one of the most serious medical problems, affecting ∼1% of all people worldwide, irrespective of race. The disease is autoimmune in nature and characterized by chronic inflammation of the synovial tissues in multiple joints that leads to joint destruction. Although T cells are central players in RA development, B cells are required for full penetrance of disease largely via their production of autoantibodies against Fc domain of IgG rheumatoid factor (RF). Treatment options for RA are limited and if any, are inadequate due to associated side effects. Members of the tumor necrosis factor (TNF) superfamily play important roles in a number of autoimmune diseases, including RA. In this review, we briefly summarize key features of the superfamily, we will consider how the well-characterized members concerned with immune regulation are coordinated and their roles in rheumatoid arthritis.

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.

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.

OX40/OX40L in systemic lupus erythematosus: association with disease activity and lupus nephritis

BACKGROUND AND OBJECTIVES

OX40-OX40L interaction is implicated in the pathogenesis of systemic lupus erythematosus (SLE). We evaluated the role of OX40/OX40L as markers of disease activity and nephritis in SLE patients.

DESIGN AND SETTING

Case-control study conducted in 2009 on SLE patients attending the outpatient clinics of Ain Shams University Hospital, Egypt.

PATIENTS AND METHODS

We assessed the percentage of CD4+ T-lymphocytes expressing OX40 by flowcytometry, and serum OX40 ligand (OX40L) levels in 40 patients with SLE (20 with lupus nephritis and 20 without) and in 20 healthy controls. Disease activity was assessed by the University of Toronto SLE disease activity index (SLEDAI).

RESULTS

The percentage of CD4+ T-lymphocytes expressing OX40 was significantly higher in SLE patients than in controls, and in patients with lupus nephritis than in those without. OX40 expression correlated positively with both serum creatinine levels and SLEDAI. OX40 expression was the highest in patients with class V lupus nephritis and lowest in class II. Serum OX40L levels were significantly higher in SLE patients than in controls, and in patients with nephritis than in those without. Serum OX40L levels correlated with serum creatinine levels but not with SLEDAI. OX40 expression on CD4+ T-cells had a higher sensitivity and specificity in diagnosing lupus nephritis than both OX40L and anti-double-stranded DNA levels.

CONCLUSION

OX40-OX40L interaction plays a role in the pathogenesis of SLE. The expression of OX40 on CD4+ T-lymphocytes and the serum level of OX40L may act as markers of lupus nephritis. Measurements of percentages of CD4+ T-lymphocytes expressing OX40 may serve as an indicator of disease activity in SLE.

Lack of evidence to support the association of polymorphisms within the TNFSF4 gene and coronary heart disease in a Chinese Han population

Coronary heart disease (CHD) is a complex disorder resulting from the interaction of a number of genetic and environmental factors. Increasing evidence has shown that OX40 ligand (OX40L), also known as tumor necrosis factor superfamily member 4 (TNFSF4), plays a key role in the pathogenesis of atherosclerosis. However, there have been inconsistent reports in various populations, and further studies are required to clarify this issue. A gene-based association study was conducted using five single-nucleotide polymorphisms (SNPs) reported in previous studies. The five SNPs (rs1234314, rs45454293, rs3850641, rs1234313 and rs3861950) were genotyped in 547 unrelated CHD patients and 601 healthy controls in a case-control study using polymerase chain reaction and restriction fragment length polymorphism. rs1234314, rs3850641 and rs3861950 were further genotyped in an additional 512 cases and 520 controls using the TaqMan SNP genotyping method. A possible relationship between the five SNPs and the severity of CHD was investigated. The results revealed no significant association between the TNFSF4 polymorphism and CHD. In addition, the stratified analysis of genotypic and allelic frequencies showed no association between the TNFSF4 polymorphism and CHD in either gender. Finally, no significant correlation between the TNFSF4 polymorphism and CHD severity was detected. These findings do not support a role of the TNFSF4 gene in CHD pathogenesis in the Chinese Han population.

Delivery of immunostimulatory monoclonal antibodies by encapsulated hybridoma cells

Immunostimulatory monoclonal antibodies are immunoglobulins directed toward surface proteins of immune system cells that augment the immune response against cancer in a novel therapeutic fashion. Exogenous administration of the recombinant humanized immunoglobulins is being tested in clinical trials with agents of this kind directed at a variety of immune-controlling molecular targets. In this study, the encapsulation of antibody-producing hybridoma cells was tested in comparison with the systemic administration of monoclonal antibodies. Hybridomas producing anti-CD137 and anti-OX40 mAb were encapsulated in alginate to generate microcapsules containing viable cells that secrete antibody. Immobilized cells in vitro were able to release the rat immunoglobulin produced by the hybridomas into the supernatant. Microcapsules were implanted by injection into the subcutaneous tissue of mice and thereby provided a platform for viable secreting cells, which lasted for more than 1 week. The pharmacokinetic profile of the rat monoclonal antibodies following microcapsule implantation was similar to that attained following an intraperitoneal administration of the purified antibodies. The rat-mouse hybridoma cells did not engraft as tumors in immunocompetent mice, while they lethally xenografted in immunodeficient mice, if not microencapsulated. The antitumor therapeutic activity of the strategy was studied on established CT26 colon carcinomas resulting in complete tumor eradication in an elevated fraction of cases and strong tumor-specific CTL responses with either anti-CD137 or anti-OX40 producing hybridomas, thus offering proof of the concept. This form of administration permitted combinations of more than one immunostimulatory monoclonal antibody to exploit the synergistic effects such as those known to be displayed by anti-CD137 and anti-OX40 mAb.

Activation of OX40 augments Th17 cytokine expression and antigen-specific uveitis

Uveitis is a major and common cause of visual disability. Recent studies have shown that Th17 cells are implicated in the pathogenesis of this serious intraocular disorder. Activated T cells express an inducible costimulatory molecule called OX40, and OX40 in turn promotes the activation and proliferation of these lymphocytes. Nevertheless, it is unclear whether OX40 plays a vital role in enhancing the effector function of Th17 cells as well as the severity of uveitis. In this study, we demonstrated an increase of OX40 transcription in ovalbumin-induced uveitis, whereas anti-OX40L antibody substantially inhibited the antigen-specific ocular inflammation. Next, results from flow cytometry showed that activated Th17 cells expressed OX40, and OX40-activating antibody significantly augmented the production of Th17 cytokines in vitro. To validate the impact of OX40 in vivo, we stimulated ovalbumin-specific T cells with the OX40-activating antibody. Compared to donor cells without OX40 activation, adoptive transfer of OX40-stimulated lymphocytes elicited more severe ocular inflammation. Furthermore, an interleukin-17-neutralizing antibody attenuated OX40-mediated uveitis. In conclusion, our findings suggest that activation of OX40 augments Th17 cell function and thereby contributes to ocular inflammation. This study thus enhances our knowledge of costimulatory molecule-mediated immunopathological mechanisms of uveitis and suggests a future therapeutic strategy to treat uveitis by the targeting of OX40.

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.

Combination therapy of established tumors by antibodies targeting immune activating and suppressing molecules

The blockade of immune suppression against antitumor responses is a particularly attractive strategy when combined with agents that promote tumor-specific CTLs. In this study, we have attempted to further improve the CTL induction and potent antitumor efficacy of a combination mAb-based therapy (termed "trimAb therapy") that comprises tumor cell death-inducing anti-death receptor 5 mAb and immune activating anti-CD40 and anti-CD137 mAbs. Among trimAb-treated tumors, the infiltration of CD4(+) Foxp3(+) cells was greater in progressing tumors compared with stable tumors. Blockade of CTLA-4 (CD152)-mediated signals by an antagonistic mAb substantially increased the tumor rejection rate of trimAb therapy, although the immune responses of draining lymph node cells were not augmented. Interestingly, by comparison, additional treatment with agonistic anti-glucocorticoid-induced TNF receptor mAb, antagonistic anti-programmed death-1 (CD279) mAb, or agonistic anti-OX40 (CD134) mAb significantly augmented immune responses of draining lymph node cells, but did not augment the therapeutic effect of trimAb. CD4 T cell depletion reduced the antitumor effect of anti-CTLA-4 mAb treatment alone, but did not reduce the tumor rejection rate of trimAb in conjunction with anti-CTLA-4 mAb. Thus, the blockade of the CTLA-4-mediated inhibitory signal in tumor infiltrating CTL may be the most effective strategy to augment the effect of immune therapies that generate tumor-specific CTL.

Ligation of the OX40 co-stimulatory receptor reverses self-Ag and tumor-induced CD8 T-cell anergy in vivo

Tumor-specific CD8 T-cell peripheral tolerance occurs through clonal deletion, suppression, and the induction of anergy and can limit the generation of anti-tumor immunity. Several groups have demonstrated that prostate cancer can render tumor-specific CD8 T cells anergic, suggesting reversing tumor-induced anergy may greatly augment anti-tumor immunity. Recent work has demonstrated that signaling through the OX40 (CD134) co-stimulatory receptor, a member of the TNFR super-family, can augment CD4 and CD8 T-cell expansion, differentiation, and the generation of memory cells. However, whether OX40 ligation can reverse CD8 T-cell anergy, and more specifically, tumor-induced CD8 T-cell anergy, remains unclear. In the current study, we demonstrate that OX40 ligation can reverse CD8 T-cell anergy to a prostate-specific self-Ag in non-tumor-bearing hosts. Furthermore, OX40 engagement reversed tumor-specific CD8 T-cell anergy and restored the proliferative capacity of tumor-reactive CD8 T cells, which attenuated tumor growth and enhanced the survival of tumor-bearing hosts. These data demonstrate that OX40 ligation can rescue the function of anergic self- or tumor-reactive CD8 T cells in vivo and suggests that OX40-mediated therapy may provide a novel means of boosting anti-tumor immunity by restoring the responsiveness of previously anergic tumor-specific CD8 T cells.

Systematic analysis of immune infiltrates in high-grade serous ovarian cancer reveals CD20, FoxP3 and TIA-1 as positive prognostic factors

Background

Tumor-infiltrating T cells are associated with survival in epithelial ovarian cancer (EOC), but their functional status is poorly understood, especially relative to the different risk categories and histological subtypes of EOC.

Methodology/Principal Findings

Tissue microarrays containing high-grade serous, endometrioid, mucinous and clear cell tumors were analyzed immunohistochemically for the presence of lymphocytes, dendritic cells, neutrophils, macrophages, MHC class I and II, and various markers of activation and inflammation. In high-grade serous tumors from optimally debulked patients, positive associations were seen between intraepithelial cells expressing CD3, CD4, CD8, CD45RO, CD25, TIA-1, Granzyme B, FoxP3, CD20, and CD68, as well as expression of MHC class I and II by tumor cells. Disease-specific survival was positively associated with the markers CD8, CD3, FoxP3, TIA-1, CD20, MHC class I and class II. In other histological subtypes, immune infiltrates were less prevalent, and the only markers associated with survival were MHC class II (positive association in endometrioid cases) and myeloperoxidase (negative association in clear cell cases).

Conclusions/Significance

Host immune responses to EOC vary widely according to histological subtype and the extent of residual disease. TIA-1, FoxP3 and CD20 emerge as new positive prognostic factors in high-grade serous EOC from optimally debulked patients.

TNF superfamily: costimulation and clinical applications

The molecules concerned with costimulation belong either to the immunoglobulin (Ig) or tumor necrosis factor (TNF) superfamily. The tumor necrosis superfamily comprises molecules capable of providing both costimulation and cell death. In this review we briefly summarize certain TNF superfamily receptor-ligand pairs that are endowed with costimulatory properties and their importance in health and disease.

Self-antigen prevents CD8 T cell effector differentiation by CD134 and CD137 dual costimulation

We compared how CD4 vs CD8 cells attain the capacity to express the effector cytokine IFN-gamma under both immunogenic and tolerogenic conditions. Although the Ifng gene locus was epigenetically repressed in naive Ag-inexperienced CD4 cells, it had already undergone partial remodeling toward a transcriptionally competent configuration in naive CD8 cells. After TCR stimulation, CD8 cells fully remodeled the Ifng locus and gained the capacity to express high levels of IFN-gamma more rapidly than CD4 cells. Enforced dual costimulation through OX40 and 4-1BB redirected CD8 cells encountering soluble exogenous peptide to expand and differentiate into IFN-gamma and TNF-alpha double-producing effectors rather than becoming tolerant. Despite this and the stronger tendency of CD8 compared with CD4 cells to differentiate into IFN-gamma-expressing effectors, when parenchymal self-Ag was the source of tolerizing Ag, enforced dual costimulation selectively boosted expansion but did not push effector differentiation in CD8 cells while both expansion and effector differentiation were dramatically boosted in CD4 cells. Notably, enforced dual costimulation was able to push effector differentiation in CD8 cells encountering cognate parenchymal self-Ag when CD4 cells were simultaneously engaged. Thus, the ability of enforced OX40 plus 4-1BB dual costimulation to redirect CD8 cells to undergo effector differentiation was unexpectedly influenced by the source of tolerizing Ag and help was selectively required to facilitate CD8 cell effector differentiation when the tolerizing Ag derived from self.

Assembling OX40 aptamers on a molecular scaffold to create a receptor-activating aptamer

We show that a molecular scaffold can be utilized to convert a receptor binding aptamer into a receptor agonist. Many receptors (including tumor necrosis receptor family members) are activated when they are multimerized on the cell surface. Molecular scaffolds have been utilized to assemble multiple receptor binding peptide ligands to generate activators of such receptors. We demonstrate that an RNA aptamer that recognizes OX40, a member of the tumor necrosis factor receptor superfamily, can be converted into a receptor-activating aptamer by assembling two copies on an olignucleotide-based scaffold. The OX40 receptor-activating aptamer is able to induce nuclear localization of nuclear factor-kappaB, cytokine production, and cell proliferation, as well as enhance the potency of dendritic cell-based tumor vaccines when systemically delivered to mice.

Targeting the CD134-CD134L interaction using anti-CD134 and/or rhCD134 fusion protein as a possible strategy to prevent lupus nephritis

Lupus nephritis (LN) is characterized by an increased upregulation of Th1. This study was undertaken to evaluate the role of CD134 in cytokine production in peripheral blood mononuclear cells (PBMCs) from subjects with LN. Percentages of IFN-gamma- (Th1), IL-4-, and IL-10- (Th2) producing cells within the PBMC CD4+ T cell population of LN subjects were found to be higher than those of healthy subjects. Stimulation of PBMC from LN subjects with anti-CD3 epsilon mAb/rIL-2 resulted in further increases in cytokine production. Stimulation in the presence of anti-CD134 mAb resulted in reduced IL-4 and IL-10 production; however, it also resulted in increased IFN-gamma production. Stimulation in the presence of the fusion protein rhCD134:Fc resulted in decreased production of all three cytokines. The possibilities that anti-CD134 therapy may control the extent of IL-4- and IL-10-mediated damage in active LN and that rhCD134:Fc therapy may prevent occurrence of LN are discussed.

Identifying the susceptibility genes for coronary artery disease: from hyperbole through doubt to cautious optimism

The genetic basis of coronary artery disease (CAD) is complex, and the fact that an alarmingly high proportion of reported associations between genetic variants and CAD are not replicated has generated uncertainty as to whether molecular genetics is ever going to deliver on the promises delivered in the late 1990s. However, during 2007, the first generation of large-scale genome-wide association studies using high-density, single nucleotide polymorphism genotyping arrays have revealed genetic variants that are robustly associated with CAD and CAD-related traits such as type 2 diabetes and obesity. In particular, a robust susceptibility locus for CAD has been identified on chromosome 9p21. Also, evidence has been obtained that multiple rare alleles with fairly strong phenotypic effects may contribute to the genetic heritability of CAD, in addition to common variants with a modest impact on risk. Furthermore, new mechanistic connections have been discovered between different common complex diseases including CAD. This review focuses on the challenges and recent advances of molecular genetics in dissecting the molecular pathophysiology of atherothrombosis and defining novel targets for treatment.

Effects of CD134 monoclonal antibody on hemolysis activities and expression of perforin in peripheral blood mononuclear cells of systemic lupus erythematosus patients

Perforin had been demonstrated to play important roles in the pathology of systemic lupus erythematosus (SLE), which was a potential target of clinical treatment of SLE. CD134 was a member of the tumor necrosis factor receptor family, which had been demonstrated to inhibit expression of perforin mRNA. The aim of the present study was to determine the effects of CD134 monoclonal antibody (MAb) on expression and hemolysis activities of perforin and its mechanisms. Effects of CD134 MAb on hemolysis activities of perforin were measured by rabbit red blood cells. Effects of CD134 MAb on expression of perforin in peripheral blood mononuclear cells (PBMCs) were determined by reverse transcription-polymerase chain reaction (RT-PCR) method and flow cytometry. Then, expression of NF-kappaB P65 was detected by Western blot. The results showed that CD134 MAb could inhibit hemolysis activities and expression of perforin through decreasing expression of NF-kappaB P65. The inhibition effects were positively correlated to the SLE disease activity index (SLEDAI) and 24-hour protein-uria of SLE patients in active state. CD134 MAb is suggested to be a potential treatment for SLE patients.

Altered gene expression in mice with lupus treated with edratide, a peptide that ameliorates the disease manifestations

OBJECTIVE

To identify genes that are differently expressed in (NZB x NZW)F(1) mice with established lupus compared with healthy controls, and to determine how gene expression is affected by treatment with hCDR1 (Edratide), a peptide synthesized on the basis of the sequence of the first complementarity-determining region (CDR1) of an autoantibody.

METHODS

RNA was extracted from spleen cells of young, disease-free mice and of older mice with systemic lupus erythematosus (SLE) that were treated with hCDR1 or with vehicle alone. Gene expression was assessed using the DNA microarray technique and verified by real-time reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

In mice with SLE, numerous genes showed increased or decreased expression relative to that in the disease-free controls. Treatment with hCDR1 restored the expression of many of these genes to control levels. Real-time RT-PCR verified that in diseased mice RNA transcripts of Tnfsf4, Il5ra, Zbtb20, and Nid1 were up-regulated, while transcripts of Tfpi and S100a8 were down-regulated, and confirmed the effects of hCDR1 on the expression of those genes. Kidney immunostaining demonstrated that the up-regulated expression of OX40 ligand, which is a protein product of the gene tumor necrosis factor (ligand) superfamily member 4, in diseased mice was reduced by hCDR1.

CONCLUSION

Expression of numerous genes in mice with SLE differs from that in young, disease-free control mice. Treatment with hCDR1 restores the expression of 22% of these genes to levels similar to those in controls. Thus, one of the mechanisms by which hCDR1 exerts its beneficial effects on the clinical symptoms of SLE is through regulation of gene expression.

Costimulation tunes tumor-specific activation of redirected T cells in adoptive immunotherapy

Redirecting T cell effector functions towards pre-defined target cells represents an attractive concept in the adoptive immunotherapy of malignant diseases. Our understanding of the mechanisms of T cell activation and costimulation as well as the design of recombinant T cell receptors have made major progress in the last years. Translating recent concepts of T cell stimulation into recombinant protein design provides the basis to engineer T cells with both pre-defined specificity and costimulatory capacity in order to enhance anti-tumor immunity and to break tolerance. Dual signaling immunoreceptors providing the CD3zeta signal simultaneously with an appropriate costimulatory signal moreover allows to modulate the quality of the anti-tumor T cell response in a predicted fashion.

Development and characterization of recombinant human Fc:OX40L fusion protein linked via a coiled-coil trimerization domain

OX40 (CD134) is a potent costimulatory molecule found on the surface of activated CD4(+) and CD8(+) T cells. Immunotherapy with OX40 agonists administered in vivo has demonstrated efficacy in several murine tumor models. A phase I clinical trial is currently underway in patients with advanced cancer using a mouse anti-CD134 monoclonal antibody. Therapy with this antibody will likely be limited to one cycle because patients develop neutralizing human anti-mouse antibody (HAMA). Therefore, we developed a humanized OX40 agonist that links the extracellular domain of human OX40L to the Fc domain of human IgG(1) via a trimerizing isoleucine zipper domain (ILZ). Physical characterization by velocity sedimentation revealed that this novel construct, hFcILZOX40L, was assembled into hexamers in which the Fc domains formed three disulfide-bonded dimers and the ILZ-OX40L domains formed two trimers. Trimerization of the ILZ domain was necessary to achieve appropriate assembly. In vitro biologic activity of the hFcILZOX40L hexamer was equivalent to the activity of agonist antibodies in plate-bound assays and was superior when the agonists were tested as soluble agents. Our ultimate goal is to use this recombinant molecule in a future clinical trial, and we feel that the OX40L hexamer will have equivalent or superior agonist activity in vivo when compared to an anti-OX40 antibody.

Anti-OX40 (CD134) administration to nonhuman primates: immunostimulatory effects and toxicokinetic study

The immune-stimulatory properties of anti-CD134 (OX40) antibodies have been well documented in rodents, including their ability to enhance antitumor immunity. In this study, an anti-OX40 antibody (Ab) known to costimulate monkey T cells in vitro, was infused into rhesus macaque monkeys during immunization with the simian immunodeficiency virus protein, gp130. The draining lymph nodes from immunized monkeys treated with anti-OX40 were enlarged compared with immunized monkeys injected with mouse Ig. Anti-OX40-treated monkeys had increased gp130-specific Ab titers, and increased long-lived T-cell responses, compared with controls. There were no overt signs of toxicity in the anti-OX40-treated monkeys. The encouraging immune-stimulatory effects led to the good manufacturing practice production of an anti-OX40 Ab for clinical trials in cancer patients. A detailed toxicology study was performed with anti-OX40 in nonhuman primates. Three groups of 8 monkeys received anti-OX40 at 1 of 3 dose levels (0.4, 2.0, and 10 mg/kg) and a control group received saline. No clinical toxicity was observed, but acute splenomegaly and enlarged gut-associated lymph nodes were observed in the anti-OX40-treated animals; splenomegaly and lymphadenopathy resolved by day 28. These studies demonstrate the immune-stimulatory properties and safety of anti-OX40 in primates and provide a strong scientific rationale to pursue clinical trials in humans.

Expression and function of the OX40/OX40L costimulatory pair during herpes stromal keratitis

Herpes stromal keratitis (HSK) is an immunopathological disease regulated by Th1 CD4 T cells, which require APC and costimulation within the infected cornea to mediate disease. Recent studies suggest the OX40:OX40 ligand (OX40L) interaction enhances effector cell cytokine secretion at inflammatory sites. OX40(+) cells were detected in HSV-1-infected mouse corneas as early as 3 days postinfection (dpi), prior to the onset of HSK, and their frequency increased through 15 dpi, when all mice exhibited severe HSK. OX40L(+) cells were first detected at 7 dpi, coincident with the initiation of HSK. It is interesting that the OX40L(+) cells did not coexpress MHC Class II or the dendritic cell (DC) marker CD11c. Our findings demonstrate rapid infiltration of activated (OX40(+)) CD4(+) T cells into HSV-1-infected corneas and expression of OX40L on MHC Class II-negative cells but surprisingly, not on MHC Class II(+) CD11c(+) DC, which are present in the infected corneas and required for HSK. Moreover, neither local nor systemic treatment of mice with a blocking antibody to OX40L or with a blocking fusion protein altered the course of HSK significantly, possibly as a result of a lack of OX40L expression on functional APC.

The role of TNFalpha and IL-17 in the development of excess IL-1 signaling-induced inflammatory diseases in IL-1 receptor antagonist-deficient mice

IL-1 receptor antagonist (IL-1Ra)-deficient mice spontaneously develop several inflammatory diseases, resembling rheumatoid arthritis, aortitis, and psoriasis in humans. As adoptive T cell transplantation could induce arthritis and aortitis in recipient mice, it was suggested that an autoimmune process is involved in the development of diseases. In contrast, as dermatitis developed in scid/scid-IL-IRa-deficient mice and could not be induced by T cell transfer, a T cell-independent mechanism was suggested. The expression of proinflammatory cytokines was augmented at the inflammatory sites. The development of arthritis and aortitis was significantly suppressed by the deficiency of TNFalpha or IL-17. The development of dermatitis was also inhibited by the deficiency of TNFalpha. These observations suggest that TNFalpha and IL-17 play a crucial role in the development of autoimmunity downstream of IL-1 signaling, and excess IL-1 signaling-induced TNFalpha also induces skin inflammation in a T cell-independent manner.

Effect of antibody to CD134 on perforin-mediated cytolysis in human peripheral blood mononuclear cells

CD134 (OX40) is a new member of the tumor necrosis factor receptor (TNFR) superfamily. The influence of CD134 on perforin-mediated cytolysis remains obscure. In this study, human peripheral blood mononuclear cells (PBMC) were induced with phytohemagglutinin (50 microg/mL), by using anti-CD134 blocking monoclonal antibody (MAb; 1, 5, and 10 microg/mL) for 6, 12, 24, and 48 h. Perforin-mediated cytolysis against human erythrocytes of PBMC was detected. The expression of perforin mRNA and protein was also measured by reverse transcription-polymerase chain reaction and flow cytometry. Our data showed that the perforin-mediated cytolysis of PBMC was downregulated by various concentrations of anti-CD134 blocking MAb for different times and reached a minimum at 24 h at any concentration. Anti-CD134 blocking MAb induced downregulation of perforin-mediated cytolysis of PBMC in a dose-dependent manner in the range of 1-5 microg/mL. Perforin- mediated cytolysis of PBMC reached a plateau when the concentration of anti-CD134 blocking MAb exceeded 5 microg/mL. Anti-CD134 blocking MAb also induced the inhibition of the expression of perforin protein and mRNA in PBMC. In conclusion, anti-CD134 blocking MAb inhibits perforin-mediated cytolysis of PBMC by, at least in some part, decreasing the production of preforin, which may be useful in treating several autoimmune diseases.

Molecules involved in T-B co-stimulation and B cell homeostasis: possible targets for an immunological intervention in autoimmunity

The deepened knowledge of co-stimulatory mechanisms within the immunological synapse and the emerging biological principles governing B cell homeostasis provide a plethora of new possibilities to selectively block or enhance immune responses. These mechanisms are highly relevant to the development of new treatment modalities for autoimmune diseases. Here we review approaches to antagonise members of the CD28-B7 superfamily as well as the TNF receptor ligand superfamily members, BAFF and APRIL, and their corresponding receptors on B cells (BAFF-R, TACI and BCMA). The proof of principle that such manipulations have indeed profound consequences for the human immune response comes from genetically manipulated mouse models, and, more importantly, from human immunodeficiency syndromes. Thus, the recent discovery of deletions in the ICOS, BAFF-R and TACI genes leading to disturbances in late B cell differentiation and hypogammaglobulinaemia underline the potential impact of targeting these molecules for therapeutic strategies in autoimmune disorders.

T Cell Costimulation in the Development of Cardiac Allograft Vasculopathy

Cardiac allograft vasculopathy (CAV) is a form of coronary arterial stenosis and a leading cause of death in patients who survive beyond the first year after heart transplantation. Histopathologically, this lesion is concentric diffuse intimal hyperplasia of the arterial wall that is accompanied by extensive infiltration of inflammatory cells, including T cells. Many studies have explored the potential risk factors related to this arterial lesion and its pathogenesis. Continuous minor endothelial cell damage evokes inflammatory processes including T cell activation. Costimulatory molecules play crucial roles in this T cell activation. Many costimulatory pathways have been described, and some are involved in the pathogenesis of CAV, atherogenesis, and subsequent plaque formation. In this review, we summarize the present knowledge of the role of these pathways in CAV development and the possibility of manipulating these pathways as a means to treat heart allograft vascular disease and atherosclerosis.

OX40 (CD134) engagement drives differentiationof CD4+ T cells to effector cells

Naive, CD4+ T cells proliferate extensively but fail to differentiate when they are transferred into unirradiated recipients that express alloantigen or transgenic antigen on all MHC class II+ cells. Addition of an agonist antibody to OX40 (CD134), a costimulatory TNF receptor family member expressed on activated CD4+ T cells, enables the proliferating T cells to accumulate as differentiated effector cells and kill the host animals. The donor T cells from anti-OX40-treated animals express high levels of IL-2R alpha (CD25) and acquire the ability to secrete IFN-gamma when stimulated with IL-12 and IL-18. OX40 promotes differentiation by 48 h in T cell priming, before changes in Bcl-2 expression or cell recovery become apparent. We found that a Bcl-2 transgene or deficiency in Fas or TNFR1 failed to influence accumulation of differentiated donor cells, and found larger changes in expression of cytokine and cytokine receptor genes than in survival genes. Accumulation of differentiated CD4+ effector T cells is initiated directly through OX40, but some OX40-deficient donor cells can gain effector function as bystanders to OX40+/+ cells. Taken together, these data suggest that CD4+ T cell differentiation to effector function is an important effect of OX40 engagement under conditions of ubiquitous antigen presentation.

Characterization and application of two novel monoclonal antibodies against human OX40: costimulation of T cells and expression on tumor as well as normal gland tissues

OX40, a membrane-bound molecule of the tumor-necrosis-factor-receptor superfamily, is a critical costimulatory receptor during the immune response. Here, we newly generated two specific mouse antihuman OX40 monoclonal antibodies (mAbs) (2G2 and 1F7), whose specificities are quite different from the available OX40 mAb (ACT35) by competition assay. It was also found that both mAbs could enhance the proliferation, activation and differentiation of T lymphocytes primed by anti-CD3 mAb. These results evidenced that both were functional antihuman OX40 mAbs. Furthermore, stained by 2G2 and 1F7, FCM and immunohistochemistry detected the constitutive expression of OX40 on tumor cell lines from epithelium, breast cancer and glioma tissues. Meanwhile, the non-tumor tissues (thyroid gland, stomach gland) were also found OX40 expression. These results suggested that OX40 is not only expressed in activated T cells, but also in some tumors as well as normal gland tissues. Such expression pattern indicated that OX40 may be a valuable surface antigen in unveiling its expression and function outside the immune system. Briefly, these novel antibodies may contribute to the evaluation of the mechanism of tumor metastasis and eventually shed light on further study of tumor immunotherapy and autoimmune diseases.

OX40 ligation of CD4+ T cells enhances virus-specific CD8+ T cell memory responses independently of IL-2 and CD4+ T regulatory cell inhibition

We have previously shown that CD4(+) T cells are required to optimally expand viral-specific memory CD8(+) CTL responses using a human dendritic cell-T cell-based coculture system. OX40 (CD134), a 50-kDa transmembrane protein of the TNFR family, is expressed primarily on activated CD4(+) T cells. In murine models, the OX40/OX40L pathway has been shown to play a critical costimulatory role in dendritic cell/T cell interactions that may be important in promoting long-lived CD4(+) T cells, which subsequently can help CD8(+) T cell responses. The current study examined whether OX40 ligation on ex vivo CD4(+) T cells can enhance their ability to "help" virus-specific CTL responses in HIV-1-infected and -uninfected individuals. OX40 ligation of CD4(+) T cells by human OX40L-IgG1 enhanced the ex vivo expansion of HIV-1-specific and EBV-specific CTL from HIV-1-infected and -uninfected individuals, respectively. The mechanism whereby OX40 ligation enhanced help of CTL was independent of the induction of cytokines such as IL-2 or any inhibitory effect on CD4(+) T regulatory cells, but was associated with a direct effect on proliferation of CD4(+) T cells. Thus, OX40 ligation on CD4(+) T cells represents a potentially novel immunotherapeutic strategy that should be investigated to treat and prevent persistent virus infections, such as HIV-1 infection.