What is the real role of CD40 in cancer immunotherapy?

Intracellular Adhesion Molecule-1 Improves Responsiveness to Immune Checkpoint Inhibitor by Activating CD8+ T Cells

Immune checkpoint inhibitor (ICI) clinically benefits cancer treatment. However, the ICI responses are only achieved in a subset of patients, and the underlying mechanisms of the limited response remain unclear. 160 patients with non-small cell lung cancer treated with anti-programmed cell death protein-1 (anti-PD-1) or anti-programmed death ligand-1 (anti-PD-L1) are analyzed to understand the early determinants of response to ICI. It is observed that high levels of intracellular adhesion molecule-1 (ICAM-1) in tumors and plasma of patients are associated with prolonged survival. Further reverse translational studies using murine syngeneic tumor models reveal that soluble ICAM-1 (sICAM-1) is a key molecule that increases the efficacy of anti-PD-1 via activation of cytotoxic T cells. Moreover, chemokine (CXC motif) ligand 13 (CXCL13) in tumors and plasma is correlated with the level of ICAM-1 and ICI efficacy, suggesting that CXCL13 might be involved in the ICAM-1-mediated anti-tumor pathway. Using sICAM-1 alone and in combination with anti-PD-1 enhances anti-tumor efficacy in anti-PD-1-responsive tumors in murine models. Notably, combinatorial therapy with sICAM-1 and anti-PD-1 converts anti-PD-1-resistant tumors to responsive ones in a preclinical study. These findings provide a new immunotherapeutic strategy for treating cancers using ICAM-1.

Rationale and clinical development of CD40 agonistic antibodies for cancer immunotherapy

Introduction: CD40 signaling activates dendritic cells leading to improved T cell priming against tumor antigens. CD40 agonism expands the tumor-specific T cell repertoire and has the potential to increase the fraction of patients that respond to established immunotherapies.Areas covered: This article reviews current as well as emerging CD40 agonist therapies with a focus on antibody-based therapies, including next generation bispecific CD40 agonists. The scientific rationale for different design criteria, binding epitopes, and formats are discussed.Expert opinion: The ability of CD40 agonists to activate dendritic cells and enhance antigen cross-presentation to CD8⁺ T cells provides an opportunity to elevate response rates of cancer immunotherapies. While there are many challenges left to address, including optimal dose regimen, CD40 agonist profile, combination partners and indications, we are confident that CD40 agonists will play an important role in the challenging task of reprogramming the immune system to fight cancer.

Immunotherapies targeting stimulatory pathways and beyond

Co-stimulatory and co-inhibitory molecules play a critical role in T cell function. Tumor cells escape immune surveillance by promoting immunosuppression. Immunotherapy targeting inhibitory molecules like anti-CTLA-4 and anti-PD-1/PD-L1 were developed to overcome these immunosuppressive effects. These agents have demonstrated remarkable, durable responses in a small subset of patients. The other mechanisms for enhancing anti-tumor activities are to target the stimulatory pathways that are expressed on T cells or other immune cells. In this review, we summarize current phase I/II clinical trials evaluating novel immunotherapies targeting stimulatory pathways and outline their advantages, limitations, and future directions.

Characteristics and clinical trial results of agonistic anti-CD40 antibodies in the treatment of malignancies

Cluster of differentiation 40 (CD40) mediates many immune activities. Preclinical studies have shown that activation of CD40 can evoke massive antineoplastic effects in several tumour models in vivo, providing a rationale for using CD40 agonists in cancer immunotherapy. To date, several potential agonistic antibodies that target CD40 have been investigated in clinical trials. Early clinical trials have shown that the adverse events associated with agonists of CD40 thus far have been largely transient and clinically controllable, including storms of cytokine release, hepatotoxicity and thromboembolic events. An antitumour effect of targeting CD40 for monotherapy or combination therapy has been observed in some tumours. However, these antitumour effects have been moderate. The present review aimed to provide updated details of the clinical results of these agonists, and offer information to further investigate the strategies of combining CD40 activation with chemotherapy, radiotherapy, targeted therapy and immunomodulators. Furthermore, biomarkers should be identified for monitoring and predicting responses and informing resistance mechanisms.

The Use of Anti-CD40 mAb in Cancer

Immunomodulatory monoclonal antibody (mAb) therapy is at the forefront of developing cancer therapeutics with numerous targeted agents proving highly effective in selective patients at stimulating protective host immunity, capable of eradicating established tumours and leading to long-term disease-free states. The cell surface marker CD40 is expressed on a range of immune cells and transformed cells in malignant states whose signalling plays a critical role in modulating adaptive immune responses. Anti-CD40 mAb therapy acts via multiple mechanisms to stimulate anti-tumour immunity across a broad range of lymphoid and solid malignancies. A wealth of preclinical research in this field has led to the successful development of multiple anti-CD40 mAb agents that have shown promise in early-phase clinical trials. Significant progress has been made to enhance the engagement of antibodies with immune effectors through their interactions with Fcγ receptors (FcγRs) by the process of Fc engineering. As more is understood about how to best optimise these agents, principally through the fine-tuning of mAb structure and choice of synergistic partnerships, our ability to generate robust, clinically beneficial anti-tumour activity will form the foundation for the next generation of cancer therapeutics.

Efficacy of cytokine-induced killer cells targeting CD40 and GITR

Since the publication of a novel protocol in 1991, cytokine-induced killer (CIK) cells have shown promising results in the treatment against neoplastic diseases. Despite ongoing preclinical and clinical studies, CIK cell treatment in the context of human monoclonal antibodies targeting tumor-necrosis factor receptors remains overlooked. The present study investigated whether a combination of CIK cells with human monoclonal antibody anti-CD40 and anti-Glucocorticoid-induced TNF-related protein (GITR) would lead to further cytotoxicity against tumor cells expressing CD40 and GITR ligand (L). Therefore, in vitro experiments with human lymphoma cell lines SU-DHL-4 and Daudi (both CD40 positive) and human breast adenocarcinoma MCF-7 (GITRL positive) were performed and the secretion of interferon (IFN)-γ was measured. Three interesting results emerged: i) a combination of CIK cells and anti-CD40 mAb is more effective than CIK cell treatment alone; ii) the use of anti-GITR mAb and CIK cells significantly enhanced the cytotoxicity of CIK cells against MCF-7 compared with single CIK cell treatment and iii) the combination of both antibodies and CIK cells abrogates the anti tumoral effect of CIK cells on all three cell lines. By performing an ELISA for IFN-γ measurement, a lower secretion was observed when anti-CD40 or anti-GITR mAb was added. This outcome indicates that further studies in vitro and in vivo may aid in understanding the synergistic molecular mechanisms of CIK cells, and anti-CD40 and anti-GITR mAb.

Molecular Mechanism of Anti-Cancer Activity of the Nano-Drug C-PC/CMC-CD59sp NPs in Cervical Cancer

The novel tumor targeted nano-drug C-PC/CMC-CD59sp nanoparticles were constructed with carbocymethyl chitosan (CMC), C-phycocyanin (C-PC) and CD59 specific ligand peptide (CD59sp). The anti-tumor drug mechanism of the C-PC/CMC-CD59sp NPs was further explored in cervical cancer cells (HeLa and SiHa) in vitro and in vivo. We found that the C-PC/CMC-CD59sp NPs could inhibit the proliferation and induce G0/G1 cell cycle arrest in cervical cancer HeLa and SiHa cells, and the cell proliferation was reduced in a dose-dependent manner. We further found that the C-PC/CMC-CD59sp NPs regulated the cell cycle via up-regulating the expression of p21, and then down-regulating the expressions of Cyclin D1 and CDK4 in vivo. Compared with C-PC and C-PC/CMC NPs, the pro-apoptosis effects of the C-PC/CMC-CD59sp NPs were more significant for HeLa and SiHa cells in vitro. Moreover, the C-PC/CMC-CD59sp NPs up-regulated the expression of cleaved caspase-3 and down-regulated the expression of bcl-2. In addition, compared with C-PC and C-PC/CMC, the C-PC/CMC-CD59sp NPs significantly inhibited MMP-2 protein expression in vivo. Our data suggested that the anti-tumor effects of C-PC/CMC-CD59sp NPs were better than C-PC and C-PC/CMC NPs. Our laboratory constructed a new drug delivery system and proved the effective antitumor effects of C-PC/CMC-CD59sp, which would widen the application of C-PC as a potential anti cervical cancer drug.

Immunoliposome co-delivery of bufalin and anti-CD40 antibody adjuvant induces synergetic therapeutic efficacy against melanoma

Liposomes constitute one of the most popular nanocarriers for improving the delivery and efficacy of agents in cancer patients. The purpose of this study was to design and evaluate immunoliposome co-delivery of bufalin and anti-CD40 to induce synergetic therapeutic efficacy while eliminating systemic side effects. Bufalin liposomes (BFL) conjugated with anti-CD40 antibody (anti-CD40-BFL) showed enhanced cytotoxicity compared with bufalin alone. In a mouse B16 melanoma model, intravenous injection of anti-CD40-BFL achieved smaller tumor volume than did treatment with BFL (average: 117 mm³ versus 270 mm³, respectively); the enhanced therapeutic efficacy through a caspase-dependent pathway induced apoptosis, which was confirmed using terminal deoxynucleotidyl transferase-mediated dUTP-Fluorescein nick end labeling and Western blot assay. Meanwhile, anti-CD40-BFL elicited unapparent body-weight changes and a significant reduction in serum levels of tumor necrosis factor-α, interleukin-1β, interleukin-6, interferon-γ, and hepatic enzyme alanine transaminase, suggesting minimized systemic side effects. This may be attributed to the mechanism by which liposomes are retained within the tumor site for an extended period of time, which is supported by the following biodistribution and flow cytometric analyses. Taken together, the results demonstrated a highly promising strategy for liposomal vehicle transport of anti-CD40 plus bufalin that can be used to enhance antitumor effects via synergetic systemic immunity while blocking systemic toxicity.

CD40 pathway activation reveals dual function for macrophages in human endometrial cancer cell survival and invasion

Reproductive malignancies are a major cause of cancer death in women worldwide. CD40 is a TNF receptor family member, which upon activation may mediate tumor regression. However, despite the great potential of CD40 agonists, their use as a therapeutic option for reproductive cancers has never been investigated. Because CD40 ligation is a potent pathway of macrophage activation, an in vitro model of pro-inflammatory type-1 (Mϕ-1) and anti-inflammatory type-2 (Mϕ-2) macrophages was developed to determine whether and how macrophage CD40 pathway activation might influence endometrial tumor cell behavior. Analysis of tumor growth kinetic in the endometrial cancer xenograft model indicates that, when injected once into the growing tumors, CD40-activated Mϕ-1 greatly reduced, while CD40-activated Mϕ-2 increased tumor size when compared to control isotype-activated Mϕ-1 and Mϕ-2, respectively. In vitro assays indicated that CD40-activated Mϕ-2 increased cell viability but failed to promote cell invasion. CD40-activated Mϕ-1, in contrast, decreased cell survival but greatly increased cell invasion in tumor cells less susceptible to cell death by apoptosis; they also induced the expression of some pro-inflammatory genes, such as IL-6, LIF, and TNF-α, known to be involved in tumor promotion and metastasis. The presence of IFN-γ is minimally required for CD40-activated Mϕ-1 to promote tumor cell invasion, a process that is mediated in part through the activation of the PI3K/Akt2 signaling pathway in tumor cells. From these results, we speculate that some functions of CD40 in tumor-associated Mϕs might limit the therapeutic development of CD40 agonists in endometrial cancer malignancies.

microRNA signature for human pancreatic cancer invasion and metastasis

Pancreatic cancer has the poorest prognosis among all human malignant solid tumors, mainly due to its high invasive and metastatic biological features. microRNAs (miRNAs) are a group of endogenous and small non-coding RNA molecules 18-25 nucleotides in length, functioning as either tumor-suppressor genes or oncogenes. Evidence has shown that regulation of miRNAs in pancreatic cancer is associated with tumor growth, invasion, metastasis and resistance to therapy. Over the last decade, many studies have also found that there is a close relationship between miRNAs and biological characteristics of pancreatic cancer invasion and metastasis, such as the presence of cancer stem cells, epithelial-mesenchymal transition (EMT) phenotype, DNA methylation or epigenetic alteration, and the activation of some specific signaling pathways. Therefore, better understanding of the complex role of miRNAs in the development and progression of pancreatic cancer metastasis may provide new insights that could be of therapeutic consequence. In this brief review, we discuss the literature concerning the correlation between miRNAs and pancreatic cancer, focusing on miRNAs that contribute to pancreatic cancer invasion and metastasis, particularly on cancer stem cell characteristics, the EMT process, epigenetic modifications and tumor-associated signaling pathways.

Cooperative function of CCR7 and lymphotoxin in the formation of a lymphoma-permissive niche within murine secondary lymphoid organs

Lymphoma cell survival and progression are putatively dependent on a specific microanatomic localization within secondary lymphoid organs. Despite compelling data correlating homeostatic chemokine receptor expression and human lymphoma pathogenesis, genetic models that either mimic lymphoma dissemination or dissect a crosstalk of lymphoma and stromal cells are missing. Applying the genetically tractable Eμ-Myc transgenic mouse model, we show that the chemokine receptor CCR7 regulates Eμ-Myc lymphoma homing to lymph nodes and distinctive microanatomic sites of the spleen. CCR7-controlled access of lymphoma cells to the splenic T-cell zone led to a significant survival advantage compared with CCR7-deficient lymphoma cells, which were excluded from this zone. Within the niche, lymphoma cells stimulated a reciprocal cross-talk with gp38(+) fibroblastic reticular cells. This reciprocal cooperation program was mediated by lymphoma B cell-presented lymphotoxin, which acted on lymphotoxin-β-receptor-bearing stromal cells followed by alteration of stromal cellular composition. Cross-talk inhibition by lymphotoxin-α deletion and using a lymphotoxin-β receptor-immunoglobulin fusion protein impaired lymphoma growth. Thus, abrogation of CCR7-governed migration and of sustained lymphotoxin signaling could provide new targets in lymphoma therapy.

Vav-1 expression correlates with NFκB activation and CD40-mediated cell death in diffuse large B-cell lymphoma cell lines

Diffuse large B-cell lymphoma (DLBCL) is an aggressive malignancy with a variable response to therapy. We have previously shown that DLBCL cell lines differ in their susceptibility to CD40-mediated cell death, and that resistance to CD40-targeted antibodies correlated with increased expression of markers of immature B-cell and absence of Vav-1 mRNA. We used gene expression profiling to investigate the mechanism of CD40 resistance in these cell lines, and found that resistance correlated with lack of Vav-1 and inability to activate NFκB upon CD40 ligation. Analysis of tissue microarrays of 213 DLBCL cases revealed that Vav-1 expression correlated with a higher proliferative index and the presence of the post-germinal centre marker Irf-4. Our results suggest that Vav-1 expression may be associated with activated B-cell DLBCL origin and higher proliferative activity, and indicate Vav-1 as a potential marker to identify tumours likely to respond to CD40-targeted therapies.

CD40/CD40L signaling and its implication in health and disease

CD40, a transmembrane receptor of the tumor necrosis factor gene superfamily is expressed on a variety of cells, such as monocytes, B-cells, antigen presenting cells, endothelial, smooth muscle cells, and fibroblasts. The interaction between CD40 and CD40 ligand (CD40L) enhances the expression of cytokines, chemokines, matrix metalloproteinases, growth factors, and adhesion molecules, mainly through the stimulation of nuclear factor kappa B. The aim of this review is to summarize the molecular and cellular characteristics of CD40 and CD40L, the mechanisms that regulate their expression, the cellular responses they stimulate and finally their implication in the pathophysiology of inflammatory and autoimmune diseases.

Involvement of CD40 targeting miR-224 and miR-486 on the progression of pancreatic ductal adenocarcinomas

BACKGROUND

Genetic and epigenetic alterations during development of pancreatic ductal adenocarcinomas (PDAC) are well known. Genetic and epigenetic data were correlated with tumor biology to find specific alterations responsible for invasion and metastasis in pancreatic ductal adenocarcinomas.

METHODS

A total of 16 human PDAC cell lines were used in murine orthotopic PDAC models. By means of standardized dissemination scores, local invasion and metastatic spread were assessed. mRNA and microRNA expression were studied by microarray and TaqMan low-density array. Quantitative real-time-polymerase chain reaction and flow cytometry were used for expression validation.

RESULTS

CD40 was detected as a relevant target gene for differentially expressed miRNAs observed in highly invasive and metastatic PDAC only. A significant overexpression (P < .05) of CD40-related miRNAs miR-224 and miR-486 was detected in highly invasive and metastatic PDAC, whereas CD40 mRNA expression was not significantly altered. Instead, CD40 protein expression at cell surfaces of these highly invasive and metastatic PDAC was significantly reduced (P < .01).

CONCLUSIONS

Epigenetic alterations with upregulated CD40-targeting miR-224 and miR-486 are related to downregulated CD40 protein expression at cell surfaces in highly invasive and metastatic PDAC. Thus, miRNA-regulated CD40 expression seems to play an important role in progression of PDAC. These data suggest a diagnostic and therapeutic potential for CD40 and/or its targeting miRNAs in PDAC.

Therapeutic interventions targeting CD40L (CD154) and CD40: the opportunities and challenges

CD40 was originally identified as a receptor on B-cells that delivers contact-dependent T helper signals to B-cells through interaction with CD40 ligand (CD40L, CD154). The pivotal role played by CD40-CD40L interaction is illustrated by the defects in B-lineage cell development and the altered structures of secondary lymphoid tissues in patients and engineered mice deficient in CD40 or CD40L. CD40 signaling also provides critical functions in stimulating antigen presentation, priming of helper and cytotoxic T-cells and a variety of inflammatory reactions. As such, dysregulations in the CD40-CD40L costimulation pathway are prominently featured in human diseases ranging from inflammatory conditions to systemic autoimmunity and tissue-specific autoimmune diseases. Moreover, studies in CD40-expressing cancers have provided convincing evidence that the CD40-CD40L pathway regulates survival of neoplastic cells as well as presentation of tumor-associated antigens to the immune system. Extensive research has been devoted to explore CD40 and CD40L as drug targets. A number of anti-CD40L and anti-CD40 antibodies with diverse biological effects are in clinical development for treatment of cancer and autoimmune diseases. This chapter reviews the role of CD40-CD40L costimulation in disease pathogenesis, the characteristics of therapeutic agents targeting this pathway and status of their clinical development.

Identification of a strongly activating human anti-CD40 antibody that suppresses HIV type 1 infection

We characterized the functional properties of a novel set of human anti-CD40 monoclonal antibodies originating from a human phage display library and identified an antibody that strongly activates cells via the CD40 receptor for potential use in HIV therapy. The anti-CD40 antibodies were converted from a single chain antibody fragment format (scFv) to an IgG format and produced in HEK293 cells, and the binding characteristics were evaluated. Next, their ability to (1) rescue a human B cell line from induced apoptosis, (2) stimulate B cell proliferation, and (3) block the CD40-CD40L interaction was determined. Finally, the most activating anti-CD40 antibody was tested for its ability to block HIV-1 infection in a monocyte-derived cell line. The different anti-CD40 antibodies, A24, B44, E30, F33, and A2-54, displayed a wide variety of binding and functional properties. In particular, B44 showed a very strong ability to activate normal human B cells and, in addition, did not block the CD40-CD40L interaction. This antibody was able to suppress HIV-1 infection in a human cell line (MonoMac 1) and may be a potential therapeutic candidate in HIV infection.

Sensitivity of HIV type 1 primary isolates to human anti-CD40 antibody-mediated suppression is related to coreceptor use

The effect of CD40 ligation on infection by HIV-1 primary isolates with different R5 phenotypes was evaluated with a novel set of anti-CD40 monoclonal antibodies originating from a human phage display library. Five human monoclonal anti-CD40 antibodies of IgG1 subtype characterized by the ability to activate B cells via CD40 were tested for induction of the CC-chemokines RANTES and MIP-1alpha and inhibition of HIV-1 replication in primary monocyte-derived macrophages (MDM). All activating anti-CD40 antibodies were able to induce CC-chemokines in MDM. We chose the most potent antibody, clone B44, for further experiments. This antibody had a suppressive effect on HIV-1 isolates of the R5 phenotype with limited use of CCR5/CXCR4 chimeric receptors. In comparison, HIV-1 isolates with broader use of CCR5/CXCR4 chimeric receptors or with CXCR4 use were less sensitive to anti-CD40-induced suppression. The results indicate that HIV-1 replication is inhibited by human anti-CD40 monoclonal antibodies through the mechanism of CC-chemokine induction. This effect is thus restricted to HIV-1 isolates sensitive to inhibition by CC-chemokines.

TRAF proteins in CD40 signaling

The tumor necrosis factor receptor (TNFR) superfamily molecule CD40 is expressed by a wide variety of cell types following activation signals, and constitutively on B lymphocytes, macrophages, and dendritic cells. CD40 signals to cells stimulate kinase activation, gene expression, production of a antibody and a variety of cytokines, expression or upregulation of surface molecules, and protection or promotion of apoptosis. Initial steps in CD40-mediated signal cascades involve the interactions of CD40 with various members of the TNFR-associated factor (TRAF) family of cytoplasmic proteins. This review summarizes current understanding of the nature of these interactions, and how they induce and regulate CD40 functions.

Complete rejection of a T-cell lymphoma due to synergism of T-cell receptor costimulatory molecules, CD80, CD40L, and CD40

The equal importance of the qualitative and quantitative characteristics of antigen presentation as well as the set of costimulatory signals provided by antigen presenting cells to T-cells in determining the outcome of T-cell responses at the time of antigen recognition is now clear. Moreover, an important function in innate mechanisms has been recently attributed to costimulatory molecules demonstrating their relevant role in different stages of immune response. In this paper, we demonstrated the ability of CD40L (CD154) and CD80 costimulatory molecules expression in a T-cell lymphoma to induce both T-cell dependent and independent immune responses leading to an important anti-tumor effect. CD40 expression by LBC cells enhanced only T-cell dependent anti-tumor immune response resulting in tumor rejection. Furthermore, this work represents the first report to describe complete tumor rejection after co-inoculation of lymphoma cells transfected with CD40L and CD80 in either presence or absence of CD40 expressing lymphoma cells. In addition, this synergistic effect resulted in long lasting immunity to parental tumor cells. Co-inoculation of tumor cells each genetically modified to express a different costimulatory molecule circumvents the need to co-transfect genetically unstable tumor cells and represents an option for those weakly or non-immunogenic tumors where either treatment alone proved to be inefficient. This strategy represents a promising approach for inducing anti-tumor immunity and provides a new rational design of cancer therapies.

CD40 ligand-mediated activation of the de novo RelB NF-kappaB synthesis pathway in transformed B cells promotes rescue from apoptosis

CD40, a tumor necrosis factor receptor family member, is expressed on B lymphocytes. Interaction between CD40 and its ligand (CD40L), expressed on activated T lymphocytes, is critical for B cell survival. Here, we demonstrate that CD40 signals B cell survival in part via transcriptional activation of the RelB NF-kappaB subunit. CD40L treatment of chronic lymphocytic leukemia cells induced levels of relB mRNA. Similarly, CD40L-mediated rescue of WEHI 231 B lymphoma cells from apoptosis induced upon B cell receptor (surface IgM) engagement led to increased relB mRNA levels. Recently, we characterized a new de novo synthesis pathway for the RelB NF-kappaB subunit, induced by the cytomegalovirus IE1 protein, in which binding of p50/p65 NF-kappaB and c-Jun/Fra-2 AP-1 complexes to the relB promoter works in synergy to potently activate transcription (Wang, X., and Sonenshein, G. E. (2005) J. Virol. 79, 95-105). CD40L treatment of WEHI 231 cells caused induction of AP-1 family members Fra-2, c-Jun, JunD, and JunB. Cotransfection of Fra-2 with the Jun AP-1 subunits and p50/c-Rel NF-kappaB led to synergistic activation of the relB promoter. Ectopic expression of relB or RelB knockdown using small interfering RNA demonstrated the important role of this subunit in control of WEHI 231 cell survival and implicated activation of the anti-apoptotic factors Survivin and manganese superoxide dismutase. Thus, CD40 engagement of transformed B cells activates relB gene transcription via a process we have termed the de novo RelB synthesis pathway, which protects these cells from apoptosis.

T cells stimulated by CD40L positive leukemic blasts-pulsed dendritic cells meet optimal functional requirements for adoptive T-cell therapy

Adoptive T-cell immunotherapy may provide complementary therapy for childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL). In this study, we have analyzed the functional characteristics of anti-BCP-ALL effector T cells generated by co-culturing T lymphocytes and dendritic cells (DC) from allogeneic human stem cell transplantation (HSCT) donors. After 21-day co-culture with DC pulsed with CD40L+ apoptotic BCP-ALL blasts, T cells presented with both effector and central memory phenotype, and showed high and specific cytotoxic activity against leukemic cells (average lysis = 77%), mostly mediated by CD8+ T cells. Noticeably, growth of CD4 T cells was maintained (45% of total cells), which actively produced Th1 cytokines (IFN-gamma, TNF-alpha, IL-2), but not IL-4, IL-5 and IL-10. Anti-BCP-ALL T cells expressed CD49d and CXCR4 (implicated in the recruitment to bone marrow), and CD62L and CCR7 (involved in the migration to lymphoid organs). In accordance with this profile, T cells significantly migrated in response to the chemokines CXCL12 and CCL19. In conclusion, stimulation of T cells with CD40L+BCP-ALL cells-loaded DC not only elicited the generation of potent and specific anti-leukemic cytotoxic effectors, but also the differentiation of specific and functional Th-1 CD4 lymphocytes. These effectors are fully equipped to reach leukemia-infiltrated tissues and have characteristics to support and orchestrate the anti-tumor immune-response.

Activating anti-CD40 antibodies induce tumour invasion by cytotoxic T-lymphocytes and inhibition of tumour growth in experimental liver cancer

The aim of this study was to investigate the effects of an activating anti-CD40 antibody (aCD40Ab) on leukocyte adhesion to tumour vessels, leukocyte migration and tumour growth in experimental liver cancer. Morris-Hepatoma was induced by subcapsular inoculation of tumour cells in the liver of ACI-rats. On day 7 and 8 after tumour cell injection, one group of the animals received aCD40Ab. On day 13 the tumour volume was measured and intravital microscopy was performed quantifying leukocyte adherence in the liver. Furthermore, immunohistological analyses were performed. aCD40Ab-Treated animals showed increased leukocyte-endothelium interaction, demonstrated substantially more T- and natural killer (NK) cells in the tumour and had a distinctly decreased tumour volume. Our results show that treatment with aCD40Ab stimulates endothelial leukocyte adhesion in tumour vessels and migration of CD4 cells/CD8 T-cells and NK cells into the tumour and inhibits tumour growth. Thus, the CD40/CD154 pathway is a worthwhile target for adjuvant immunotherapy.

Constitutive activation of the CD40 pathway promotes cell transformation and neoplastic growth

CD40, a tumour necrosis factor (TNF) receptor family member, is expressed in a variety of cell types, including B lymphocytes, macrophages, fibroblasts, endothelial and epithelial cells, and this widespread expression is likely to account for its central role in normal physiology and disease pathogenesis. In this study, we provide evidence to support a role for constitutive CD40 signalling in cell transformation. We show that the ligand for CD40 (CD40L/CD154) is expressed in CD40-positive human breast tumour biopsies, suggesting that the constitutive activation of the CD40 receptor in vivo may contribute to the oncogenic process. Coexpression of CD40 and CD40L confers oncogenic effects on immortalized human epithelial cells in vitro, increasing their proliferation, motility and invasion. Expression of LMP:CD40, a hybrid molecule comprising the N-terminus and transmembrane domains of the Epstein-Barr virus-encoded latent membrane protein-1 (LMP1) fused to the cytoplasmic tail of CD40, mimics a constitutively active CD40 receptor and promotes the transformation of immortalized rodent fibroblasts in vitro and their oncogenicity in vivo. The observed effects of aberrant CD40 activation on cell transformation are largely diminished upon suppression of the oncogenic NF-kappaB signalling pathway. Taken together, our results suggest a role for the constitutive engagement of the CD40L/CD40/NF-kappaB activation pathway in cell transformation and neoplastic growth. Strategies that neutralize this pathway may therefore be useful in cancer treatment and prevention.

Preclinical antilymphoma activity of a humanized anti-CD40 monoclonal antibody, SGN-40

SGN-40 is a humanized IgG1 antihuman CD40 that is currently in a phase I clinical trial for the treatment of multiple myeloma. As surface CD40 expression on B-lineage cells is maintained from pro-B cells to plasma cells, SGN-40 may be applicable to treatment of other B-cell neoplasias, including non-Hodgkin's lymphoma. In this study, we examined potential in vitro and in vivo anti-B-lineage lymphoma activity of SGN-40. Recombinant SGN-40 was expressed and purified from Chinese hamster ovary cells and characterized based on binding affinity, specificity, and normal B-cell stimulation. The ability of SGN-40 to target neoplastic B cells was examined in vitro by proliferation inhibition, cytotoxicity, and antibody-dependent cell cytotoxicity assays and in vivo by human lymphoma xenograft models. Recombinant SGN-40 showed high affinity, Kd of approximately 1 nmol/L, and specific binding to CD40. Whereas SGN-40 was a weak agonist in stimulating normal B-cell proliferation in the absence of IL-4 and CD40L, it delivered potent proliferation inhibitory and apoptotic signals to, and mediated antibody-dependent cytotoxicity against, a panel of high-grade B-lymphoma lines. These in vitro antilymphoma effects were extended to disseminated and s.c. xenograft CD40 tumor models. In these xenograft models, the antitumor activity of SGN-40 was comparable with that of rituximab. The preclinical in vitro and in vivo antilymphoma activity of SGN-40 observed in this study provides a rationale for the clinical testing of SGN-40 in the treatment of CD40+ B-lineage lymphomas.

The role of CD40-CD154 interaction in cell immunoregulation

CD40, a member of the nerve growth factor/tumor necrosis factor receptor superfamily, and its ligand, CD154, play essential roles in cell immune responses. The results of many studies have indicated that CD40-CD154 interaction can upregulate costimulatory molecules, activate antigen-presenting cells (APCs), influence T-cell priming and T-cell-mediated effector functions as well as participate in the pathogenic processing of chronic inflammatory diseases, such as autoimmune diabetes, graft rejection, atherosclerosis, and cancer. Ligation of CD40 on cancer cells was also found to produce a direct growth-inhibitory effect through cell cycle blockage and/or apoptosis with no overt side effects on normal cells and treatment with CD154 can heighten tumor rejection immune response as well. However, systemic treatment with CD154 has some potential risks. Therefore, searching for efficient and safe strategies of CD154-based cancer therapy has been a hot topic in human cancer research. This review focuses on the latest discovered functions of CD40-CD154 interaction in cell immune responses and on the new findings of CD154-based human cancer therapy.

Sensitization of multiple myeloma and B lymphoma lines to dexamethasone and ?-radiation-induced apoptosis by CD40 activation

We examined the effects of CD40 activation with dexamethasone (Dex) or 60Co-gamma-irradiation on the growth of malignant B cells in vitro, using the human multiple myeloma (MM) cell line, XG2, and the B lymphoma Daudi cell line as models. Both lines are resistant to Dex and irradiation; 10(-7)M Dex or 10 Gy of gamma-irradiation induced only minimal growth arrest and apoptosis of the cells. Treatment of the cells with the agonistic anti-CD40 monoclonal antibody 5C11 partially inhibited the proliferation of the Daudi cells; XG2 underwent apoptosis. XG2 is an Interleukin-6 (IL-6)-dependent myeloma cell line and CD40 activation blocked XG2 in the G1 phase of the cell cycle, in a manner similar to the effect of IL-6 deprivation. Daudi was blocked in the G2/M phase after treatment with the agonistic CD40 mAb 5C11. Furthermore, the activation of CD40 on Daudi and XG2 enhanced their sensitivity to dexamethasone-and gamma-irradiation -induced growth arrest and apoptosis. CD40 activation stimulated both anti-apoptotic Bcl-XL and pro-apoptotic Bax mRNA synthesis in the Daudi cell line; CD40 activation increased the Bax mRNA level but had no effect on the Bcl-XL mRNA level in the XG2 cell line. Apoptosis in both cell lines was associated with an increasing ratio of Bax-to-Bcl-XL both in mRNA and in protein levels. It is concluded that use of the anti-CD40 mAb 5C11 either by itself or in combination with chemotherapy and/or radiotherapy may have significant therapeutic potential.

Activation of CD40 in Cervical Carcinoma Cells Facilitates CTL Responses and Augments Chemotherapy-Induced Apoptosis

In this study, we describe the expression and function of CD40, a TNF receptor family member, in cervical carcinomas. CD40 was present at very low levels in normal cervical epithelium but was overexpressed in human papillomavirus-infected lesions and advanced squamous carcinomas of the cervix. The stimulation of CD40-positive cervical carcinoma cell lines with soluble CD40L (CD154) resulted in activation of the NF-kappaB and MAPK signaling pathways and up-regulation of cell surface markers and intracellular molecules associated with Ag processing and presentation. Concomitantly, the CD154-induced activation of CD40 in carcinoma cells was found to directly influence susceptibility to CTL-mediated killing. Thus, CD40 stimulation in cervical carcinoma cell lines expressing a TAP-dependent human papillomavirus 16 E6 Ag epitope resulted in their enhanced killing by specific CTLs. However, CD154 treatment of carcinoma cells expressing proteasome-dependent but TAP-independent Ags from the EBV-encoded BRLF1 and BMLF1 failed to increase tumor cell lysis by specific CTLs. Moreover, we demonstrate that chemotherapeutic agents that suppress protein synthesis and reverse the CD40-mediated dissociation of the translational repressor eukaryotic initiation factor 4E-binding protein from the initiation factor eukaryotic initiation factor 4E, such as 5-fluorouracil, etoposide, and quercetin, dramatically increase the susceptibility of cervical carcinoma cells to CD40L-induced apoptosis. Taken together, these observations demonstrate the functional expression of CD40 in epithelial tumors of the cervix and support the clinical exploitation of the CD40 pathway for the treatment of cervical cancer through its multiple effects on tumor cell growth, apoptosis, and immune recognition.

Potential use of CD40 ligand for immunotherapy of childhood B-cell precursor acute lymphoblastic leukaemia

Around 20% of children affected by B-cell precursor acute lymphoblastic leukaemia (BCP-ALL) still experience a recurrence of the disease after diagnosis, despite a significant improvement in the cure rate (80%). Moreover, standard therapies have high and often unacceptable acute and chronic organ toxicity, with an increased risk for secondary malignancies. Therefore, new strategies are needed to improve overall survival and decrease treatment-associated morbidity. Recent in-vitro and in-vivo studies have demonstrated that CD40 engagement improves tumour immunogenicity and, consequently, generates a strong antitumour immune response. The CD40-CD40 ligand (CD40L) system is of pivotal importance in the immune response via interactions between T cells and antigen-presenting cells. The general aim of this chapter is to review the feasibility of developing cellular strategies to increase childhood BCP-ALL immunogenicity, and the potential use of CD40L as a new strategy to induce an antileukaemia immune response in BCP-ALL.

CD40 activation of BCP-ALL cells generates IL-10–producing, IL-12–defective APCs that induce allogeneic T-cell anergy

The use of leukemia cells as antigen-presenting cells (APCs) in immunotherapy is critically dependent on their capacity to initiate and sustain an antitumor-specific immune response. Previous studies suggested that pediatric B-cell precursor acute lymphoblastic leukemia (BCP-ALL) cells could be manipulated in vitro through the CD40-CD40L pathway to increase their immunostimulatory capacity. We extended the APC characterization of CD40L-activated BCP-ALL for their potential use in immunotherapy in a series of 19 patients. Engaging CD40 induced the up-regulation of CCR7 in 7 of 11 patients and then the migration to CCL19 in 2 of 5 patients. As accessory cells, CD40L-activated BCP-ALL induced a strong proliferation response of naive T lymphocytes. Leukemia cells, however, were unable to sustain proliferation over time, and T cells eventually became anergic. After CD40-activation, BCP-ALL cells released substantial amounts of interleukin-10 (IL-10) but were unable to produce bioactive IL-12 or to polarize TH1 effectors. Interestingly, adding exogenous IL-12 induced the generation of interferon-γ (IFN-γ)–secreting TH1 effectors and reverted the anergic profile in a secondary response. Therefore, engaging CD40 on BCP-ALL cells is insufficient for the acquisition of full functional properties of immunostimulatory APCs. These results suggest caution against the potential use of CD40L-activated BCP-ALL cells as agents for immunotherapy unless additional stimuli, such as IL-12, are provided.

Immunobiology of haematological malignant disorders: the basis for novel immunotherapy protocols

The immune system is a complex arrangement of cellular interactions that preserve the integrity of a organism by elimination of all elements judged dangerous. However, the development of tumours in immunocompetent patients suggests the existence of an imbalance that favours tumour cells against the immune response. What are the different possibilities for reversing this process to drive an efficient antitumour response? We discuss, focusing on the haematological features, classic immunity (ie, antigen-specific and HLA-restricted immunity). We address the central issues of tumour antigen presentation and recognition and their possible clinical use. Last, we discuss non-HLA-restricted immunity, which does not require the recognition of specific antigens and relies on particular cell populations such as natural killer cells.

Stimulation of non-Hodgkin's lymphoma via HVEM: an alternate and safe way to increase Fas-induced apoptosis and improve tumor immunogenicity

Stimulation by CD40 ligand (L) improves B-cell malignancy immunogenicity, and also induces proliferative signals. To avoid these tumorigenic effects, we studied an alternate way of tumor-cell stimulation by homologous to lymphotoxin, inducible expression, competing for GpD of herpesvirus, which binds to the herpesvirus entry mediator (HVEM), and is expressed on T-lymphocytes (LIGHT), the ligand for HVEM, a new member of the tumor necrosis factor (TNF)/TNF-receptor (-R) family. HVEM is constitutively expressed on the surface of tumor B cells. We focused our attention on mantle cell lymphoma, a subtype of B-cell malignancy of poor prognosis. Triggering by LIGHT, in contrast to CD40L stimulation, did not increase lymphoma proliferation nor decrease chemotherapy entrance. We observed an upregulation of the TNFR apoptosis-inducing ligand Fas, and in contrast to CD40L-induced protection, an enhancement of lymphoma sensitivity to Fas-induced apoptosis. LIGHT triggering increased lymphoma cell recognition in a mixed lymphocyte response. In conclusion, LIGHT-mediated triggering renders B-cell lymphomas more immunogenic and sensitive to apoptosis, without inducing proliferation. Since LIGHT triggering also enhances the functions of T-lymphocytes and dendritic cells, it could be a unique way to restore an efficient cancer control by its pleiotropic effects on immune effectors and tumor cells.

Tracking death dealing by Fas and TRAIL in lymphatic neoplastic disorders: pathways, targets, and therapeutic tools

In the past decade, it was concluded from a number of investigations that death domain-containing members of the tumor necrosis factor-receptor (TNF-R) family and their ligands such as Fas/FasL and TNF-related apoptosis-inducing ligand (TRAIL)-R/TRAIL are essential for maintaining an intact immune system for surveillance against infection and cancer development and that nondeath domain-containing members such as CD30 or CD40 are involved in the fine tuning of this system during the selection process of the lymphatic system. In line with this conclusion are the observations that alterations in structure, function, and regulation of these molecules contribute to autoimmunity and cancer development of the lymphoid system. Besides controlling size and function of the lymphoid cell pool, Fas/FasL and TRAIL-R/TRAIL regulate myelopoiesis and the dendritic cell functions, and severe alterations of these lineages during the outgrowth and expansion of the lymphoid tumors have been reported. It is the aim of this review to summarize what is currently known about the complex role of these two death receptor/ligand systems in normal, disturbed, and neoplastic hemato-/lymphopoiesis and to point out how such knowledge can be used in developing novel, therapeutic options and the problems that will have to be faced along the way.

Affinity and epitope profiling of mouse anti-CD40 monoclonal antibodies

The CD40-CD40L interaction plays a critical role in both humoral and cellular immune responses and interfering antibodies have been suggested as an effective approach for the treatment of lymphomas and autoimmune diseases. In this study we have profiled a panel of mouse antihuman CD40 monoclonal antibodies (MoAbs), regarding their CD40 binding affinity and epitope-specificity relative to the CD40L binding in relation to their cellular activating potential. Despite a rather similar domain-recognition profile, the MoAbs blocked the CD40L binding to a varying degree, with MoAb 5C3 being the poorest inhibitor. There was no correlation between affinity and cellular activation potential. In contrast, a correlation between the ability to block CD40L-binding and activation potential could be seen. We believe that this analysis of several mouse anti-CD40 antibodies can be used to develop strategies for producing new human anti-CD40 antibodies that can more effectively induce or block B-cell proliferation.

New approaches in the immunotherapy of haematological malignancies

Advances in the management of haematological malignancies have allowed to obtain improved remission rates. Nonetheless, relapses impair these results and justify the search for novel therapeutic strategies. Clinical data demonstrate that the immune system plays an important role in the control of haematological malignancies. An increased frequency of haematological malignancies is observed in immunodeficiency states. Reversal of the immunosuppression is sometimes sufficient to induce tumour regression (withdrawal of cyclosporine in post-transplant lymphoproliferations, highly active anti-retroviral treatment in human immunodeficiency virus related Kaposi's disease). Another line of evidence for the involvement of the immune system in the anti-tumour response comes from the observation of spontaneous anti-tumour responses that parallel the occurrence of paraneoplastic immune-mediated syndromes. Finally, the efficiency of allogeneic transplantation in the haematological field has been clearly demonstrated to depend on the immune-mediated graft vs. leukaemia effect. Nonetheless, tumours develop in immune competent patients because of various tumour escape mechanisms, such as loss of human leucocyte antigen class I antigens, absence of target recognition by deficient adhesion/co-stimulatory molecule expression, tumour cell counterattack against immune effectors, direct (contact-dependent) or indirect (cytokine-mediated) impairment of T-lymphocyte activation. Novel immunotherapy approaches are now orientated in a convergent direction, i.e. the reversal of immune escape mechanisms either via the correction of deficient phases of the immune response or by the amplification of physiological mechanisms.

CD40-mediated transcriptional regulation of the IL-6 gene in B lymphocytes: involvement of NF-kappa B, AP-1, and C/EBP

Engagement of CD40 by its ligand CD154 induces IL-6 production by B lymphocytes. We previously reported that this IL-6 production is dependent upon binding of the adapter protein TNF receptor-associated factor 6 to the cytoplasmic domain of CD40, while binding of TNF receptor-associated factors 2 and 3 is dispensable, as is the activation-induced nuclear translocation of NF-kappa B. The present study was designed to characterize CD40-mediated transcriptional control of the IL-6 gene in B cells. CD40 engagement on B lymphocytes activated the IL-6 promoter, and mutations in the putative binding sites for AP-1 and C/EBP transcription factors reduced this activation. Interestingly, a mutation in the putative NF-kappa B binding site completely abrogated the basal promoter activity, thus also rendering the promoter unresponsive to CD40 stimulation, suggesting that this site is required for binding of NF-kappa B constitutively present in the nucleus of mature B cells. The expression of dominant negative Fos or C/EBP alpha proteins, which prevent binding of AP-1 or C/EBP complexes to DNA, also reduced CD40-mediated IL-6 gene expression. Furthermore, CD40 stimulation led to phosphorylation of c-Jun on its activation domain, implicating CD40-mediated Jun kinase activation in the transcriptional regulation of IL-6 production.

Cell death regulation in oral squamous cell carcinoma: methodological considerations and clinical significance

In the last three decades, more work has been done on apoptosis and its role in the pathogenesis of many diseases including cancer. In almost all instances of cancer, dysregulation of cell death (apoptosis) and cell proliferation have been found to play a major role in tumourigenesis. A lot of progress has been made on understanding the molecular basis of apoptosis and its regulatory mechanisms. This review focuses on current knowledge on the regulation of apoptosis in oral squamous cell carcinoma, current methodologies and methodological consideration in estimation of cell death in tissue sections and the clinical significance of apoptosis related molecules in progression of oral squamous cell carcinoma.

CD40 in hepatocellular carcinoma: relevant or not?

The expression of the CD40 receptor in different tumours suggests that it might be involved in tumour development and proliferation. In this article, we discuss recent findings on CD40 expression in hepatocellular carcinoma, its possible biological role for tumour development, and different experimental therapeutic strategies such as gene therapy and immunotherapy protocols.

Prospects for CD40-directed experimental therapy of human cancer

CD40, a member of the tumor necrosis factor receptor (TNF-R) family, is a surface receptor best known for its capacity to initiate multifaceted activation signals in normal B cells and dendritic cells (DCs). CD40-related treatment approaches have been considered for the experimental therapy of human leukemias, lymphomas, and multiple myeloma, based on findings that CD40 binding by its natural ligand (CD40L), CD154, led to growth modulation of malignant B cells. Recent studies also exploited the selective expression of the CD40 receptor on human epithelial and mesenchymal tumors but not on most normal, nonproliferating epithelial tissues. Ligation of CD40 on human breast, ovarian, cervical, bladder, non small cell lung, and squamous epithelial carcinoma cells was found to produce a direct growth-inhibitory effect through cell cycle blockage and/or apoptotic induction with no overt side effects on their normal counterparts. CD154 treatment also heightened tumor rejection immune responses through DC activation, and by increasing tumor immunogenicity through up-regulation of costimulatory molecule expression and cytokine production of epithelial cancer cells. These immunopotentiating features can produce a "bystander effect" through which the CD40-negative tumor subset is eliminated by activated tumor-reactive cytotoxic T cells. However, the potential risk of systemic inflammation and autoimmune consequences remains a concern for systemic CD154-based experimental therapy. The promise of CD154 as a tumor therapeutic agent to directly modulate tumor cell growth, and indirectly activate antitumor immune response, may depend on selective and/or restricted CD154 expression within the tumor microenvironment. This may be achieved by inoculating cancer vaccines of autologous cancer cells that have been transduced ex vivo with CD154, as documented by recently clinical trials. This review summarizes recent findings on CD154 recombinant protein- and gene therapy-based tumor treatment approaches, and examines our understanding of the multifaceted molecular mechanisms of CD154-CD40 interactions.

Improved immunogenicity of a self tumor antigen by covalent linkage to CD40 ligand

The interaction between the CD40 ligand (CD40L) and CD40 on antigen-presenting cells (APCs) is critical in promoting humoral and cellular immune responses. Agonistic anti-CD40 monoclonal antibody and soluble CD40L can act as powerful adjuvants to promote vaccination, but usually require repeated high-dose treatment. In this study, we demonstrate that the adjuvant effect of CD40L can be greatly improved by directly linking the antigen to CD40L. We constructed a fusion protein (Id-CD40L) consisting of the extracellular domain of CD40L and the idiotype (Id) protein, a weakly immunogenic tumor-specific antigen derived from the murine 38C13 B-cell lymphoma. The soluble Id-CD40L fusion protein retained CD40 binding activity and stimulated CD80 and CD86 upregulation and interleukin (IL)-12 production by macrophages. Immunization of mice with Id-CD40L without adjuvants resulted in high titers of anti-Id Abs dominated by the IgG1 isotype and protected the mice from subsequent lethal tumor challenge. In a dose-response study, we demonstrated that Id-CD40L elicited anti-Id antibody (Ab) responses in all immunized animals, even at a dose as low as 0.5 microg. Immunization with free Id and an IgG-CD40L fusion protein, which was identical in structure to Id-CD40L but lost the Id determinant, resulted in significant lower anti-Id responses, indicating that physical linkage between the tumor antigen and CD40L was required for the optimal immune response. These results demonstrate that fusing CD40L to a candidate antigen can greatly improve the adjuvant activity of CD40L. This approach may be useful in developing vaccines for a variety of malignant and infectious diseases.

CD40L induces proliferation, self-renewal, rescue from apoptosis, and production of cytokines by CD40-expressing AML blasts

OBJECTIVE

Conflicting experimental and clinical results have been reported regarding the role of CD40 in acute myeloid leukemia (AML). In the present study, we analyzed the capability of CD40L/CD154 to modulate several functional aspects of CD40-expressing AML blasts.

METHODS

After defining the constitutive expression levels of CD40 in a wide panel (n = 67) of AMLs and evaluating the capability of cytokines to modulate its expression, we investigated the effects of CD40 engagement by soluble (s) CD40L on proliferation, self-renewal capacity, apoptosis, homotypic adhesion, and cytokine production of leukemia cells.

RESULTS

CD40 was detected in blast cells from about 37% of AMLs, the highest frequency being documented in monocytic subtypes, and its expression was upregulated or de novo induced by treatment with interleukin (IL)-1alpha, IL-3, IL-4, granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon-gamma, and tumor necrosis factor-alpha. Exposure of CD40(+) AML blasts to sCD40L resulted in a dose-dependent proliferative response, enhancement of clonogenic growth and self-renewal capacity, and a striking increase in colony size. CD40 engagement was able to rescue AML blasts from apoptosis induced by serum deprivation, as demonstrated by reduced expression of APO2.7 and annexin-V binding, as well as upregulation of the anti-apoptotic protein bcl-x(L). CD40 triggering upregulated cell surface expression of the adhesion molecules CD54, CD58, and CD15 and resulted in homotypic aggregation of leukemia cells at least in part CD54-dependent. An increased production of IL-6 and GM-CSF by CD40(+) AML blasts was also documented upon sCD40L exposure.

CONCLUSIONS

This study indicates a possible involvement of CD40 in the interactions of AML blasts with other growth-sustaining microenvironmental accessory cells and immune effectors, in turn expressing CD40L. Caution in the use of CD40 triggering in immunotherapy of AMLs is also suggested.

Modulation of the CD40-CD40 ligand interaction using human anti-CD40 single-chain antibody fragments obtained from the n-CoDeR phage display library

CD40 plays a central regulatory role in the immune system and antibodies able to modulate CD40 signalling may consequently have a potential in immunotherapy, in particular for treatment of lymphomas and autoimmune disease like multiple sclerosis. As a first step to achieve this goal, we describe the selection and characterization of a novel set of fully human anti-CD40 antibody fragments (scFv) from a phage display library (n-CoDeR). In order to determine their biological potential, these antibody fragments have been analysed for their ability to promote B-cell activation, rescue from apoptosis and to block the CD40-CD40 ligand (CD40L) interaction. The selected cohort of human scFv could be subcategorized, each expressing a distinct functional signature. Thus scFv were generated that induced B-cell proliferation, rescued B cells from apoptosis and blocked the CD40-CD40L interaction to different extents. In particular, one of the scFv clones (F33) had the ability to abrogate completely this interaction. The epitope recognition patterns as well as individual rate constants were also determined and the affinity was shown to vary from low to high nanomolar range. In conclusion, this panel of human anti-CD40 scFv fragments displays a number of distinct properties, which may constitute a valuable source when evaluating candidates for in vivo trials.

Association of CD40 ligand expression on HTLV-I-infected T cells and maturation of dendritic cells

Human T lymphotropic virus type I (HTLV-I) induces HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and adult T-cell leukemia (ATL). The development of HAM/TSP is associated with rapid maturation of dendritic cells (DCs), while ATL is accomplished with their maturation defect. The DC maturation is induced by cell-to-cell contact with CD4+ T cells expressing CD40 ligand (L). We determined the influence of CD40L expressed on various HTLV-I-infected T cells on the DC maturation. Around 60% of CD4+ T cells infected with HTLV-I for 1 week, expressed CD40L molecules involved in DC maturation. DCs matured by the CD40L+ T cells activated autologous CD4+ and CD8+ T cells. HTLV-I-immortalized T-cell lines established from healthy donors consistently expressed CD40L molecules for 3 months, however, some lines lost the expression soon thereafter. Interleukin (IL)-2-independent and transformed lines lacked that expression. Furthermore, T cells obtained from HAM/TSP patients expressed CD40L molecules for at least 3 weeks, whereas T cells from ATL patients did not express that. The CD40L T cells did not induce DC maturation, and required exogenous CD40L molecules for maturation. The CD40L+ T-cell-induced maturation was blocked by anti-CD40L antibody. Therefore, the lack of CD40L expression on HTLV-I-infected T cells may be associated with the development of ATL.

Induction of antitumor immunity by transduction of CD40 ligand gene and interferon-gamma gene into lung cancer

CD40-CD40 ligand (CD40L) interaction is an important costimulatory signaling pathway in the crosstalk between T cells and antigen-presenting cells. This receptor-ligand system is known to be essential in eliciting strong cellular immunity. Here we demonstrate that murine lung cancer cells (3LLSA) transduced with the CD40L gene (3LLSA-CD40L) were rejected in syngeneic C57BL/6 mice, but grew in CD40-deficient mice to the same extent as control tumor cells. Immunohistochemical study showed that inflammatory cells, including CD4+, CD8+ T cells and NK cells, infiltrated into the inoculated 3LLSA-CD40L tumor tissue. Inoculation of 3LLSA-CD40L cells into mice resulted in the induction of 3LLSA-specific cytotoxic T-cell immunity, and the growth of parental 3LLSA tumors was inhibited when 3LLSA cells were inoculated into C57BL/6 mice mixed with 3LLSA-CD40L cells or when they were rechallenged 4 weeks after 3LLSA-CD40L cells were rejected. Furthermore, co-inoculation of interferon (IFN)-gamma-transduced cells (3LLSA-IFNgamma) with 3LLSA-CD40L cells enhanced the antitumor immunity efficiently in vivo. These results indicate that the in vivo priming with CD40L- and IFN-gamma gene-transduced lung cancer cells is a promising strategy for inducing antitumor immunity in the treatment of lung cancer.

Regulation of CD40 function by its isoforms generated through alternative splicing

CD40 is a member of the tumor necrosis factor receptor superfamily. The interaction between CD40 and CD40 ligand (CD154) activates NF-kappa B, Jun N-terminal kinase, and Janus kinase/signal transducers and activators of transcription pathways and promotes B cell growth, differentiation, and survival as well as IL-12 production in macrophages and dendritic cells. We demonstrate here the existence of multiple isoforms of CD40 mRNA generated by alternative splicing and show that their expression is regulated differentially in activated macrophages and dendritic cells. Pre-CD40 RNA is spliced preferentially out to signal-transducible CD40 mRNA in the early stage of activation; half of the CD40 mRNA is replaced by the signal-nontransducible CD40 mRNAs in the later stages (24 h). Using IL-12 p40 gene expression as a reporter for CD40 signaling, we show that three of the alternative isoforms can disable signaling through CD40. The major alternative isoform lacks the membrane-associated endodomain and seems to reduce the amount of the signal-transducible form available on the cell surface. It would seem, therefore, that CD40 expression is controlled by posttranscriptional and posttranslational regulation through alternative splicing. Modulation of isoform expression may provide a mechanism by which cells regulate their susceptibility to CD40L signaling.

Reciprocal expression of the TNF family receptor herpes virus entry mediator and its ligand LIGHT on activated T cells: LIGHT down-regulates its own receptor

The TNF receptor (TNFR) family plays a central role in the development of the immune response. Here we describe the reciprocal regulation of the recently identified TNFR superfamily member herpes virus entry mediator (HVEM) (TR2) and its ligand LIGHT (TL4) on T cells following activation and the mechanism of this process. T cell activation resulted in down-regulation of HVEM and up-regulation of LIGHT, which were both more pronounced in CD8(+) than CD4(+) T lymphocytes. The analysis of HVEM and LIGHT mRNA showed an increase in the steady state level of both mRNAs following stimulation. LIGHT, which was present in cytoplasm of resting T cells, was induced both in cytoplasm and at the cell surface. For HVEM, activation resulted in cellular redistribution, with its disappearance from cell surface. HVEM down-regulation did not rely on de novo protein synthesis, in contrast to the partial dependence of LIGHT induction. Matrix metalloproteinase inhibitors did not modify HVEM expression, but did enhance LIGHT accumulation at the cell surface. However, HVEM down-regulation was partially blocked by a neutralizing mAb to LIGHT or an HVEM-Fc fusion protein during activation. As a model, we propose that following stimulation, membrane or secreted LIGHT binds to HVEM and induces receptor down-regulation. Degradation or release of LIGHT by matrix metalloproteinases then contributes to the return to baseline levels for both LIGHT and HVEM. These results reveal a self-regulating ligand/receptor system that contributes to T cell activation through the interaction of T cells with each other and probably with other cells of the immune system.