Structural characteristics of CD40 ligand that determine biological function

Implications of CD154 and Its Receptors in the Pathogenesis and Treatment of Systemic Lupus Erythematosus

CD154, also known as CD40 ligand, is a costimulatory molecule involved in humoral and adaptive immune responses upon pairing with its classical receptor, CD40. The CD154/CD40 dyad is a key participant in the pathogenesis of many autoimmune diseases, including systemic lupus erythematosus (SLE). In SLE, the major cells at play, T and B lymphocytes, are shown to overexpress CD154 and CD40, respectively. Subsequently, these cells and other CD40-positive cells engage in numerous effector functions contributing to SLE development. With the recent identification of additional receptors for CD154, all belonging to the integrin family, the role of CD154 in SLE is more complex and calls for deeper investigation into its biological significance. Many therapeutic strategies directed against the CD154/CD40 couple have been deployed for the treatment of SLE and proved efficient in animal models and human studies. However, the incidence of thromboembolic complications in patients treated with these anti-CD154/CD40 antibodies halted their further clinical assessments and called for another class of therapies targeting these molecules. Second-generation antibodies directed against CD154 or CD40 are showing promising results in the advanced stages of clinical testing. Our review presents a thorough description of CD154 and its receptors, CD40 and the integrin family members in SLE pathogenesis. All these elements of the CD154 system represent important therapeutic targets for the treatment of SLE.

Decoding the contextual duality of CD40 functions

Previously, we established that as a function of its mode of interaction with its ligand or cellular conditions such as membrane lipids, preexisting signaling intermediates activation status, a transmembrane receptor, as represented here with CD40, can induce counteractive cellular responses. Using CD40-binding peptides, recombinant mutated CD40-ligands, and an agonistic antibody, we have established the functional duality of CD40. CD40 builds up two constitutionally different signalosomes on lipid raft and non-raft membrane domains initiating two different signaling pathways. Although this initial signaling may be modified by the pre-existing signaling conditions downstream and may be subjected to feed-forward or negative signaling effects, the initial CD40-CD40L interaction plays a crucial role in the functional outcome of CD40. Herein, we have reviewed the influence of interaction between the CD40-CD40L evoking the functional duality of CD40 contingent upon different physiological states of the cells.

TRAF3/p38-JNK Signalling Crosstalk with Intracellular-TRAIL/Caspase-10-Induced Apoptosis Accelerates ROS-Driven Cancer Cell-Specific Death by CD40

The capacity to induce tumour-cell specific apoptosis represents the most unique feature of the TNF receptor (TNFR) family member CD40. Recent studies on the signalling events triggered by its membrane-presented ligand CD40L (mCD40L) in normal and malignant epithelial cells have started to unravel an exquisite context and cell type specificity for the functional effects of CD40. Here, we demonstrate that, in comparison to other carcinomas, mCD40L triggered strikingly more rapid apoptosis in colorectal carcinoma (CRC) cells, underpinned by its ability to entrain two concurrently operating signalling axes. CD40 ligation initially activates TNFR-associated factor 3 (TRAF3) and subsequently NADPH oxidase (NOX)/Apoptosis signal-regulating kinase 1 (ASK1)-signalling and induction of reactive oxygen species (ROS) to mediate p38/JNK- and ROS-dependent cell death. At that point, p38/JNK signalling directly activates the mitochondrial pathway, and triggers rapid induction of intracellular TNF-related apoptosis-inducing ligand (TRAIL) that signals from internal compartments to initiate extrinsic caspase-10-asscociated apoptosis, leading to truncated Bid (tBid)-activated mitochondrial signalling. p38 and JNK are essential both for direct mitochondrial apoptosis induction and the TRAIL/caspase-10/tBid pathway, but their involvement follows functional hierarchy and temporally controlled interplay, as p38 function is required for JNK phosphorylation. By engaging both intrinsic and extrinsic pathways to activate apoptosis via two signals simultaneously, CD40 can accelerate CRC cell death. Our findings further unravel the multi-faceted properties of the CD40/mCD40L dyad, highlighted by the novel TNFR crosstalk that accelerates tumour cell-specific death, and may have implications for the use of CD40 as a therapeutic target.

Ex vivo-expanded human CD19+TIM-1+ regulatory B cells suppress immune responses in vivo and are dependent upon the TIM-1/STAT3 axis

Regulatory B cells (Breg) are a heterogenous population with immune-modulating functions. The rarity of human IL-10⁺ Breg makes translational studies difficult. Here we report ex vivo expansion of human B cells with in vivo regulatory function (expBreg). CD154-stimulation of human CD19⁺ B cells drives >900-fold expansion of IL-10⁺ B cells that is maintained in culture for 14 days. Whilst expBreg-mediated suppressive function is partially dependent on IL-10 expression, CRISPR-mediated gene deletions demonstrate predominant roles for TIM-1 and CD154. TIM-1 regulates STAT3 signalling and modulates downstream suppressive function. In a clinically relevant humanised mouse model of skin transplantation, expBreg prolongs human allograft survival. Meanwhile, CD19⁺CD73^-CD25⁺CD71⁺TIM-1⁺CD154⁺ Breg cells are enriched in the peripheral blood of human donors with cutaneous squamous cell carcinoma (SCC). TIM-1⁺ and pSTAT3⁺ B cells are also identified in B cell clusters within histological sections of human cutaneous SCC tumours. Our findings thus provide insights on Breg homoeostasis and present possible targets for Breg-related therapies.

Novel Functions of Integrins as Receptors of CD154: Their Role in Inflammation and Apoptosis

CD154, an inflammatory mediator also known as CD40 ligand, has been identified as a novel binding partner for some members of the integrin family. The αIIbβ3, specifically expressed on platelets, was the first integrin to be described as a receptor for CD154 after CD40. Its interaction with soluble CD154 (sCD154) highly contributes to thrombus formation and stability. Identifying αIIbβ3 opened the door for investigating other integrins as partners of CD154. The αMβ2 expressed on myeloid cells was shown capable of binding CD154 and contributing as such to cell activation, adhesion, and release of proinflammatory mediators. In parallel, α5β1 communicates with sCD154, inducing pro-inflammatory responses. Additional pathogenic effects involving apoptosis-preventing functions were exhibited by the CD154–α5β1 dyad in T cells, conferring a role for such interaction in the survival of malignant cells, as well as the persistence of autoreactive T cells. More recently, CD154 receptors integrated two new integrin members, αvβ3 and α4β1, with little known as to their biological significance in this context. This article provides an overview of the novel role of integrins as receptors of CD154 and as critical players in pro-inflammatory and apoptotic responses.

Controlled Modular Multivalent Presentation of the CD40 Ligand on P22 Virus-like Particles Leads to Tunable Amplification of CD40 Signaling

Ligands of the tumor necrosis factor superfamily (TNFSF) are appealing targets for immunotherapy research due to their integral involvement in stimulation or restriction of immune responses. TNFSF-targeted therapies are currently being developed to combat immunologically based diseases and cancer. A crucial determinant of effective TNFSF receptor binding and signaling is the trimeric quaternary structure of the ligand. Additionally, ligand multivalency is essential to propagate strong signaling in effector cells. Thus, designing a synthetic platform to display trimeric TNFSF ligands in a multivalent manner is necessary to further the understanding of ligand-receptor interactions. Viral nanocages have architectures that are amenable to genetic and chemical modifications of both their interior and exterior surfaces. Notably, the exterior surface of virus-like particles can be utilized as a platform for the modular multivalent presentation of target proteins. In this study, we build on previous efforts exploring the bacteriophage P22 virus-like particle for the exterior multivalent modular display of a potent immune-stimulating TNFSF protein, CD40 ligand (CD40L). Using a cell-based reporter system, we quantify the effects of tunable avidity on CD40 signaling by CD40L displayed on the surface of P22 nanocages. Multivalent presentation of CD40L resulted in a 53.6-fold decrease of the half maximal effective concentration (EC₅₀) compared to free CD40L, indicating higher potency. Our results emphasize the power of using P22-based biomimetics to study ligand-receptor interactions within their proper structural context, which may contribute to the development of effective immune modulators.

IL-1 and CD40/CD40L platelet complex: elements of induction of Crohn's disease and new therapeutic targets

Ulcerative colitis (UC) and Crohn's disease (CD) are chronic and multifactorial diseases that affect the intestinal tract, both characterized by recurrent inflammation of the intestinal mucosa, resulting in abdominal pain, diarrhea, vomiting and, rectal bleeding. Inflammatory bowel diseases (IBD) regroup these two disorders. The exact pathological mechanism of IBD remains ambiguous and poorly known. In genetically predisposed patients, defects in intestinal mucosal barrier are due to an uncontrolled inflammatory response to normal flora. In addition to the genetic predisposition, these defects could be triggered by environmental factors or by a specific lifestyle which is widely accepted as etiological hypothesis. The involvement of the CD40/CD40L platelet complex in the development of IBD has been overwhelmingly demonstrated. CD40L is climacteric in cell signalling in innate and adaptive immunity, the CD40L expression on the platelet cell surface gives them an immunological competence. The IL-1, a major inflammation mediator could be involved in different ways in the development of IBD. Here, we provide a comprehensive review regarding the role of platelet CD40/CD40L in the pathophysiological effect of IL-1 in the development of Crohn's disease (CD). This review could potentially help future approaches aiming to target these two pathways for therapeutic purposes and elucidate the immunological mechanisms driving gut inflammation.

Targeting the CD40-CD154 Signaling Pathway for Treatment of Autoimmune Arthritis

Full activation of T lymphocytes requires signals from both T cell receptors and costimulatory molecules. In addition to CD28, several T cell molecules could deliver costimulatory signals, including CD154, which primarily interacts with CD40 on B-cells. CD40 is a critical molecule regulating several B-cell functions, such as antibody production, germinal center formation and cellular proliferation. Upregulated expression of CD40 and CD154 occurs in immune effector cells and non-immune cells in different autoimmune diseases. In addition, therapeutic benefits have been observed by blocking the CD40-CD154 interaction in animals with collagen-induced arthritis. Given the therapeutic success of the biologics abatacept, which blocks CD28 costimulation, and rituximab, which deletes B cells in the treatment of autoimmune arthritis, the inhibition of the CD40-CD154 axis has two advantages, namely, attenuating CD154-mediated T cell costimulation and suppressing CD40-mediated B-cell stimulation. Furthermore, blockade of the CD40-CD154 interaction drives the conversion of CD4+ T cells to regulatory T cells that mediate immunosuppression. Currently, several biological products targeting the CD40-CD154 axis have been developed and are undergoing early phase clinical trials with encouraging success in several autoimmune disorders, including autoimmune arthritis. This review addresses the roles of the CD40-CD154 axis in the pathogenesis of autoimmune arthritis and its potential as a therapeutic target.

A replication-incompetent CD154/40L recombinant vaccinia virus induces direct and macrophage-mediated antitumor effects in vitro and in vivo

CD40 triggering may result in antitumor effects of potentially high clinical relevance. To gain insights important for patient selection and to identify adequate targeting techniques, we investigated CD40 expression in human cancer tissues and generated a replication-incompetent recombinant vaccinia virus expressing CD40 ligand (rVV40L). Its effects were explored in vitro and in vivo upon direct CD40 targeting on malignant cells or macrophage activation. CD40 expression was analyzed by immunohistochemistry in tumor and stromal cells in a multi-tumor array including 836 specimens from 27 different tumor types. Established tumor cell lines were used to explore the capacity of rVV40L to induce malignant cell apoptosis and modulate functional profiles of polarized macrophages. CD40 expression was detectable in significantly higher numbers of stromal as compared to malignant cells in lung and breast cancers. CD40 ligation following rVV40L infection induced apoptosis in CD40(+) cancer cells, but only in the presence of intact specific signal transduction chain. Importantly, rVV40L infection promoted the induction of TNF-α-dependent antitumor activity of M1-like macrophages directed against CD40(-) targets. CD40-activated M1-like macrophages also displayed enhanced ability to CXCL10-dependently recruit CD8+ T cells and to efficiently present cancer cell intracellular antigens through cross-priming. Moreover, rVV-driven CD40L expression partially “re-educated” M2-like macrophages, as suggested by detectable CXCL10 and IL-12 production. Most importantly, we observed that intra-tumoral injection of rVV40L-infected human macrophages inhibits progression of human CD40(-) tumors in vivo. First evidences of anticancer activity of rVV40L strongly encourage further evaluations.

B Cell-Based Cancer Immunotherapy

B cells are not only producers of antibodies, but also contribute to immune regulation or act as potent antigen-presenting cells. The potential of B cells for cellular therapy is still largely underestimated, despite their multiple diverse effector functions. The CD40L/CD40 signaling pathway is the most potent activator of antigen presentation capacity in B lymphocytes. CD40-activated B cells are potent antigen-presenting cells that induce specific T-cell responses in vitro and in vivo. In preclinical cancer models in mice and dogs, CD40-activated B cell-based cancer immunotherapy was able to induce effective antitumor immunity. So far, there have been only few early-stage clinical studies involving B cell-based cancer vaccines. These trials indicate that B cell-based immunotherapy is generally safe and associated with little toxicity. Furthermore, these studies suggest that B-cell immunotherapy can elicit antitumor T-cell responses. Alongside the recent advances in cellular therapies in general, major obstacles for generation of good manufacturing practice-manufactured B-cell immunotherapies have been overcome. Thus, a first clinical trial involving CD40-activated B cells might be in reach.

CD40L and Its Receptors in Atherothrombosis-An Update

CD40L (CD154), a member of the tumor necrosis factor superfamily, is a co-stimulatory molecule that was first discovered on activated T cells. Beyond its fundamental role in adaptive immunity-ligation of CD40L to its receptor CD40 is a prerequisite for B cell activation and antibody production-evidence from more than two decades has expanded our understanding of CD40L as a powerful modulator of inflammatory pathways. Although inhibition of CD40L with neutralizing antibodies has induced life-threatening side effects in clinical trials, the discovery of cell-specific effects and novel receptors with distinct functional consequences has opened a new path for therapies that specifically target detrimental properties of CD40L. Here, we carefully evaluate the signaling network of CD40L by gene enrichment analysis and its cell-specific expression, and thoroughly discuss its role in cardiovascular pathologies with a specific emphasis on atherosclerotic and thrombotic disease.

Determination of Genes Related to Uveitis by Utilization of the Random Walk with Restart Algorithm on a Protein-Protein Interaction Network

Uveitis, defined as inflammation of the uveal tract, may cause blindness in both young and middle-aged people. Approximately 10–15% of blindness in the West is caused by uveitis. Therefore, a comprehensive investigation to determine the disease pathogenesis is urgent, as it will thus be possible to design effective treatments. Identification of the disease genes that cause uveitis is an important requirement to achieve this goal. To begin to answer this question, in this study, a computational method was proposed to identify novel uveitis-related genes. This method was executed on a large protein–protein interaction network and employed a popular ranking algorithm, the Random Walk with Restart (RWR) algorithm. To improve the utility of the method, a permutation test and a procedure for selecting core genes were added, which helped to exclude false discoveries and select the most important candidate genes. The five-fold cross-validation was adopted to evaluate the method, yielding the average F1-measure of 0.189. In addition, we compared our method with a classic GBA-based method to further indicate its utility. Based on our method, 56 putative genes were chosen for further assessment. We have determined that several of these genes (e.g., CCL4, Jun, and MMP9) are likely to be important for the pathogenesis of uveitis.

Characterization of a Broadly Reactive Anti-CD40 Agonistic Monoclonal Antibody for Potential Use as an Adjuvant

Lack of safe and effective adjuvants is a major hindrance to the development of efficacious vaccines. Signaling via CD40 pathway leads to enhanced antigen processing and presentation, nitric oxide expression, pro-inflammatory cytokine expression by antigen presenting cells, and stimulation of B-cells to undergo somatic hypermutation, immunoglobulin class switching, and proliferation. Agonistic anti-CD40 antibodies have shown promising adjuvant qualities in human and mouse vaccine studies. An anti-CD40 monoclonal antibody (mAb), designated 2E4E4, was identified and shown to have strong agonistic effects on primary cells from multiple livestock species. The mAb recognize swine, bovine, caprine, and ovine CD40, and evoked 25-fold or greater proliferation of peripheral blood mononuclear cells (PBMCs) from these species relative to cells incubated with an isotype control (p<0.001). In addition, the mAb induced significant nitric oxide (p<0.0001) release by bovine macrophages. Furthermore, the mAb upregulated the expression of MHC-II by PBMCs, and stimulated significant (p<0.0001) IL-1α, IL6, IL-8, and TNF-α expression by PBMCs. These results suggest that the mAb 2E4E4 can target and stimulate cells from multiple livestock species and thus, it is a potential candidate for adjuvant development. This is the first study to report an anti-swine CD40 agonistic mAb that is also broadly reactive against multiple species.

Generation of a soluble recombinant trimeric form of bovine CD40L and its potential use as a vaccine adjuvant in cows

Vaccination is the most cost-effective way to control infectious diseases in cattle. However, many infectious diseases leading to severe economical losses worldwide still remain for which a really effective and safe vaccine is not available. These diseases are most often due to intracellular pathogens such as bacteria or viruses, which are, by their localization, protected from antibiotics and/or CD4(+) T cell-dependent humoral responses. We therefore postulated that strategies leading to induction of not only CD4(+) T cell responses but also CD8(+) cytotoxic T lymphocyte (CTL) responses against infected cells should be privileged in the development of new vaccines against problematic intracellular pathogens in bovines. CD40 signaling in antigen-presenting cells may lead to the induction of robust CD4-independent CTL responses and several studies, especially in mice, have used CD40 stimulation to promote CD8(+) T cell-mediated immunity. For example, we have recently shown that immunization of mice with heat-killed Staphylococcus aureus (HKSA) and agonistic anti-CD40 monoclonal antibodies elicits strong CTL responses capable of protecting mice from subsequent staphylococcal mastitis. Unfortunately, there is at present no tool available to efficiently stimulate CD40 in cattle. In this study, we therefore first produced a soluble recombinant trimeric form of the natural bovine CD40 ligand (sboCD40LT). We then observed that sboCD40LT was able to potently stimulate bovine cells in vitro. Finally, we provide evidence that immunization of cows with sboCD40LT combined with HKSA was able to significantly increase the number of both HKSA-specific CD4(+) and CD8(+) T cells in the draining lymph nodes. In conclusion, we suggest that this new molecular tool could help in the development of vaccine strategies against bovine diseases caused by intracellular pathogens.

Symmetry Controlled, Genetic Presentation of Bioactive Proteins on the P22 Virus-like Particle Using an External Decoration Protein

Viruses use spatial control of constituent proteins as a means of manipulating and evading host immune systems. Similarly, precise spatial control of proteins encapsulated or presented on designed nanoparticles has the potential to biomimetically amplify or shield biological interactions. Previously, we have shown the ability to encapsulate a wide range of guest proteins within the virus-like particle (VLP) from Salmonella typhimurium bacteriophage P22, including antigenic proteins from human pathogens such as influenza. Expanding on this robust encapsulation strategy, we have used the trimeric decoration protein (Dec) from bacteriophage L as a means of controlled exterior presentation on the mature P22 VLP, to which it binds with high affinity. Through genetic fusion to the C-terminus of the Dec protein, either the 17 kDa soluble region of murine CD40L or a minimal peptide designed from the binding region of the "self-marker" CD47 was independently presented on the P22 VLP capsid exterior. Both candidates retained function when presented as a Dec-fusion. Binding of the Dec domain to the P22 capsid was minimally changed across designed constructs, as measured by surface plasmon resonance, demonstrating the broad utility of this presentation strategy. Dec-mediated presentation offers a robust, modular means of decorating the exposed exterior of the P22 capsid in order to further orchestrate responses to internally functionalized VLPs within biological systems.

New frontiers for platelet CD154

The role of platelets extends beyond hemostasis. The pivotal role of platelets in inflammation has shed new light on the natural history of conditions associated with acute or chronic inflammation. Beyond the preservation of vascular integrity, platelets are essential to tissue homeostasis and platelet-derived products are already used in the clinics. Unanticipated was the role of platelets in the adaptative immune response, allowing a renewed conceptual approach of auto-immune diseases. Platelets are also important players in cancer growth and dissemination. Platelets fulfill most of their functions through the expression of still incompletely characterized membrane-bound or soluble mediators. Among them, CD154 holds a peculiar position, as platelets represent a major source of CD154 and as CD154 contributes to most of these new platelet attributes. Here, we provide an overview of some of the new frontiers that the study of platelet CD154 is opening, in inflammation, tissue homeostasis, immune response, hematopoiesis and cancer.

Generation of multiple peptide cocktail-pulsed dendritic cells as a cancer vaccine

Cancer immunotherapy based on dendritic cell (DC) vaccination has promising alternatives for the treatment of cancer. A central tenet of DC-based cancer immunotherapy is the generation of antigen-specific cytotoxic T lymphocyte (CTL) response. Tumor-associated antigens (TAA) and DC play pivotal roles in this process. DCs are well known to be the most potent antigen-presenting cells and have the most powerful antigen-presenting capacity. DCs pulsed with various TAA have been shown to be effective in producing specific antitumor effects both in vitro and in vivo. Several types of tumor antigens have been applied in cancer treatment including tumor RNA, lysates, apoptotic bodies, heat shock protein, peptides from TAA, and allogeneic tumor cells. Among them, the use of immunogenic HLA-A*0201-specific epitopes from multiple TAA enhances induction of antigen-specific CTL and associated therapeutic efficacy in HLA-A*0201(+) cancer patients. The current chapter provides a detailed protocol of generating multiple peptide cocktail-pulsed DC to elicit CTL with a broad spectrum of immune responses against the related tumor antigens.

High molecular weight complex analysis of Epstein-Barr virus Latent Membrane Protein 1 (LMP-1): structural insights into LMP-1's homo-oligomerization and lipid raft association

LMP-1 is a constitutively active Tumor Necrosis Factor Receptor analog encoded by Epstein-Barr virus. LMP-1 activation correlates with oligomerization and raft localization, but direct evidence of LMP-1 oligomers is limited. We report that LMP-1 forms multiple high molecular weight native LMP-1 complexes when analyzed by BN-PAGE, the largest of which are enriched in detergent resistant membranes. The largest of these high molecular weight complexes are not formed by purified LMP-1 or by loss of function LMP-1 mutants. Consistent with these results we find a dimeric form of LMP-1 that can be stabilized by disulfide crosslinking. We identify cysteine 238 in the C-terminus of LMP-1 as the crosslinked cysteine. Disulfide crosslinking occurs post-lysis but the dimer can be crosslinked in intact cells with membrane permeable crosslinkers. LMP-1/C238A retains wild type LMP-1 NF-κB activity. LMP-1's TRAF binding, raft association and oligomerization are associated with the dimeric form of LMP-1. Our results suggest the possibility that the observed dimeric species results from inter-oligomeric crosslinking of LMP-1 molecules in adjacent core LMP-1 oligomers.

CD40L-Tri, a novel formulation of recombinant human CD40L that effectively activates B cells

CD40L has a well-established role in enhancing the immunostimulatory capacity of normal and malignant B cells, but a formulation suitable for clinical use has not been widely available. Like other TNF family members, in vivo and in vitro activity of CD40L requires a homotrimeric configuration, and growing evidence suggests that bioactivity depends on higher-order clustering of CD40. We generated a novel formulation of human recombinant CD40L (CD40L-Tri) in which the CD40L extracellular domain and a trimerization motif are connected by a long flexible peptide linker. We demonstrate that CD40L-Tri significantly expands normal CD19+ B cells by over 20- to 30-fold over 14 days and induces B cells to become highly immunostimulatory antigen-presenting cells (APCs). Consistent with these results, CD40L-Tri-activated B cells could effectively stimulate antigen-specific T responses (against the influenza M1 peptide) from normal volunteers. In addition, CD40L-Tri could induce malignant B cells to become effective APCs, such that tumor-directed immune responses could be probed. Together, our studies demonstrate the potent immune-stimulatory effects of CD40L-Tri on B cells that enable their expansion of antigen-specific human T cells. The potent bioactivity of CD40L-Tri is related to its ability to self-multimerize, which may be facilitated by its long peptide linker.

CD40 signal expression in gastric cancer tissue and its correlation with prognosis of gastric cancer patients

CD40 signaling plays a critical role in the survival rate of gastric cancer patients. Tumour samples were collected from 73 patients with who were diagnosed as gastric cancer in general surgery department in the 1st affiliated hospital of Suzhou University between September 2002 and July 2003. All patients had not received radiotherapy and chemotherapy before operation. These patients include 46 male and 27 female. Here we show that CD40 is constitutively expressed in the human gastric carcinoma tissues, and CD40 protein and mRNA positive expression in gastric cancer tissues closely correlated with lymph node metastasis and tumour TNM stage. CD40 positive expression in gastric cancer patients with lymph node metastasis was markedly higher than that in gastric cancer patients without lymph node metastasis. CD40 positive expression in stage III-IV gastric cancer patients was markedly higher than that in stage I-II gastric cancer patients. Moreover, CD40 expression closely correlated with prognosis of gastric cancer patients. Therefore, CD40 was taken as grouping variable, and lymph node metastasis and clinical staging were taken as stratification variables, respectively, further analysis showed that prognosis in gastric cancer patients with lymph node metastasis and CD40 positive expression was markedly worse than that in gastric cancer patients without lymph node metastasis and CD40 negative expression (P = 0.0076). These results suggest that CD40 signaling plays a critical role in the survival of gastric cancer patients.

CD40L-containing virus-like particle as a candidate HIV-1 vaccine targeting dendritic cells

The central role of dendritic cell (DC) in mounting an immune response to a novel antigen is now well established. We sought to demonstrate the use of a particular vaccine strategy based on directing HIV-1 Gag proteins to DCs in conjunction with an activation signal. CD40L was expressed on the surface of virus-like particles (VLPs) to target HIV-1 Gag antigens to the CD40 receptor on DCs, whereas CD40L-CD40 interaction would also result in cellular activation. Multiple CD40L VLP constructs were made and evaluated in vitro and in vivo. Indeed, one VLP that expressed CD40L to the highest level showed greatest capacity to activate DCs in vitro. Correspondingly, this CD40L-VLP also proved to be most immunogenic in mice in raising both humoral and cellular responses to HIV-1 Gag. Confirmatory studies were performed to demonstrate the increased immunogenicity of CD40L-VLP is no longer observed when tested in CD40-/- mice. Our findings lend support to the belief that vaccine strategies that both target and activate DCs could yield a superior immune response.

CD154: an immunoinflammatory mediator in systemic lupus erythematosus and rheumatoid arthritis

Systemic lupus erythematosus and rheumatoid arthritis are two major chronic inflammatory autoimmune diseases with significant prevalence rates among the population. Although the etiology of these diseases remains unresolved, several evidences support the key role of CD154/CD40 interactions in initiating and/or propagating these diseases. The discovery of new receptors (αIIbβ3, α5β1, and αMβ2) for CD154 has expanded our understanding about the precise role of this critical immune mediator in the physiopathology of chronic inflammatory autoimmune diseases in general, and in systemic lupus erythematosus and rheumatoid arthritis in particular. This paper presents an overview of the interaction of CD154 with its various receptors and outlines its role in the pathogenesis of systemic lupus erythematosus and rheumatoid arthritis. Moreover, the potential usefulness of various CD154-interfering agents in the treatment and prevention of these diseases is also discussed.

Activated platelets and atherosclerosis

Several studies suggest an important role for platelets in atherogenesis, not only as mediators of thrombus formation, but also as inducers of inflammation. Several lines of evidence indicate that platelets are potent inflammatory cells that induce inflammatory responses in adjacent cells such as leukocytes and endothelial cells. Platelets may also themselves respond to inflammatory mediators produced by these neighboring cells. These platelet-mediated inflammatory pathways contribute to atherogenesis in both the early and late stage of the process. The bidirectional interaction between platelets and other cells may also be involved in the nonresolving inflammation characterizing atherosclerosis. In patients with atherosclerotic disorders, platelet-mediated inflammation appears to be operating in spite of the wide use of platelet-inhibiting drugs. This underscores the need for new therapeutic tools that more specifically target the pathways in platelet-mediated inflammation.

CD40 ligand expressed in adenovirus can improve the immunogenicity of the GP3 and GP5 of porcine reproductive and respiratory syndrome virus in swine

Porcine reproductive and respiratory syndrome virus (PRRSV) has recently caused heavy economic losses in swine industry worldwide. Current vaccination strategies only provide a limited protective efficacy, thus immune modulators are being considered to enhance the effectiveness of PRRSV vaccines. In this study, the recombinant adenoviruses expressing porcine CD40 ligand (CD40L) and GP3/GP5 of PRRSV were constructed and the immune responses were examined in pigs. The results showed that rAd-CD40L-GP35 (co-expressing CD40L and GP3-GP5) or rAd-GP35 (expressing GP3-GP5) plus rAd-CD40L (expressing CD40L) could provide significant higher specific anti-PRRSV ELISA antibody and neutralizing antibody. And the levels of proliferative responses of peripheral blood mononuclear cells (PBMC), IFN-γ and IL-4 were markedly increased in rAd-CD40L-GP35 and rAd-CD40L plus rAd-GP35 groups than those in rAd-GP35 group. Following homologous challenge with Chinese isolate of the North-American genotype of PRRSV, pigs inoculated with recombinant rAd-CD40L-GP35 and rAd-CD40L plus rAd-GP35 showed lighter clinical signs and lower viremia, as compared to those in rAd-GP35 group. It indicated that porcine CD40L could effectively increase humoral and cell-mediated immune responses of GP3 and GP5 of PRRSV. Porcine CD40L might be used as an attractive adjuvant or immunotargeting strategies to enhance the PRRSV subunit vaccine responses in swine.

The CD40-CD40L pathway contributes to the proinflammatory function of intestinal epithelial cells in inflammatory bowel disease

In inflammatory bowel diseases (IBD), intestinal epithelial cells (IECs) are involved in the outbalanced immune responses toward luminal antigens. However, the signals responsible for this proinflammatory capacity of IECs in IBD remain unclear. The CD40/CD40L interaction activates various pathways in immune and nonimmune cells related to inflammation and was shown to be critical for the development of IBD. Here we demonstrate CD40 expression within IECs during active IBD. Endoscopically obtained biopsies taken from Crohn's disease (n = 112) and ulcerative colitis patients (n = 67) consistently showed immunofluorescence staining for CD40 in IECs of inflamed ileal or colonic mucosa. In noninvolved mucosa during active disease, tissue obtained during Crohn's disease or ulcerative colitis in remission and biopsies from healthy controls (n = 38) IECs almost entirely lacked CD40 staining. Flow cytometry and RT-PCR analysis using different intestinal epithelial cell lines (HT29, SW480, and T84) showed IFN-gamma to effectively induce CD40 in IECs. Cells were virtually unresponsive to LPS or whole E. coli regarding CD40 expression. In addition, a moderate induction of CD40 was found in response to TNF-alpha, which exerted synergistical effects with IFN-gamma. CD40 ligation by CD40L-transfected murine fibroblasts or soluble CD40L increased the secretion of IL-8 in IFN-gamma pretreated HT29 cells. Our findings provide evidence for the epithelial expression and modulation of CD40 in IBD-affected mucosa and indicate its involvement in the proinflammatory function of IECs.

Th17/Th1 phenotype in demyelinating disease

BACKGROUND

Th17 cells are thought to contribute to the immunopathology of allergic and autoimmune conditions. Their role in multiple sclerosis (MS) pathology remains to be fully elucidated.

OBJECTIVE

To assess peripheral blood Th17 responses in patients with MS compared to controls.

METHODS

We isolated peripheral blood mononuclear cells from 41 MS patients and 23 healthy controls, which were then stimulated using phorbol ester and ionomycin, labelled for CD3, CD8, CD154, IL-17 and IFN-gamma and analysed using flow cytometry.

RESULTS

Minimal IL-17 was detectable in unstimulated cells. Following stimulation with phorbol ester and ionomycin, PBMCs taken from MS patients in relapse developed a more inflammatory profile than those taken from controls or non-relapse patients, with greater expression of CD154, IL-17 and dual expression of IL-17/IFN-gamma.

CONCLUSION

We suggest a greater tendency to Th17 and Th1/Th17 response to non-specific stimulation in MS patients in relapse compared to controls and non-relapse patients.

[Platelet immunology and the immune response]

Platelets exert not only hemostatic activities, but also pro-inflammatory effects. Platelet-linked inflammation seems essentially related to their capacity of secreting cytokines, chemokines and related molecules. This activity is important in terms of concentration of secreted products. This secretory function confers to platelets a regulatory role in immunity. Besides, platelets do exhibit non-self infectious danger detection molecules on their surfaces, belonging in particular to the "Toll-like receptor family"; through this property, platelets can bind infectious agents but also deliver differential signals for the secretion of cytokines and chemokines. Platelets, which are non-nucleated cells deprived of nuclear DNA, possess however some cellular machinery which permits intracellular signalling and even the production of RNA transcripts for certain cytokines. Last, platelets express variant surface determinants of hemostatic molecules (referred to as HPA antigens) along with HLA class I variant molecules, the function of which on platelets is still unknown. An intriguing question is to reconcile those diverse properties and to understand whether the pro-inflammatory secretory process can affect the immunogenicity of transfused, allogeneic, platelet components.

Multimeric soluble CD40 ligand (sCD40L) efficiently enhances HIV specific cellular immune responses during DNA prime and boost with attenuated poxvirus vectors MVA and NYVAC expressing HIV antigens

The attenuated poxvirus vectors MVA and NYVAC are now in clinical trials against HIV/AIDS. Due to the vectors restricted replication capacity in human cells, approaches to enhance their immunogenicity are highly desirable. Here, we have analyzed the ability of a soluble form of hexameric CD40L (sCD40L) to stimulate specific immune responses to HIV antigens when inoculated in mice during priming with DNA and in the booster with MVA or NYVAC, expressing the vectors HIV-1 Env, Gag, Pol and Nef antigens from clade B. Our findings revealed that sCD40L in DNA/poxvirus combination enhanced the magnitude about 2-fold (DNA-B/MVA-B) and 4-fold (DNA-B/NYVAC-B), as well as the breath of the HIV antigen specific cellular immune responses. sCD40L was necessary in both prime and boost inoculations triggering a potent polarization of the Th response towards a Th1 type. In DNA-B/NYVAC-B regime the addition of sCD40L significantly enhanced the humoral immune response against HIV gp160, but not in DNA-B/MVA-B combination. These findings provided evidence for the immunostimulatory benefit of sCD40L when DNA and the poxvirus vectors MVA and NYVAC are used as immunogens.

Estimation of the number of CD154 molecules in membrane extracts used as a source of CD40 stimulation of human B lymphocytes

The CD40-CD154 interaction is better exemplified by a rheostat than by an on-off switch, and variations in its intensity can play a role in the regulation of B lymphocyte activation following primary and/or secondary humoral immune response. The CD40-CD154 interaction is often studied in co-culture models using CD154+ adherent cells, which can be problematic when performing protein or gene analyses. The use of membrane extracts prepared from CD154+-transfected cells can eliminate possible interferences caused by the presence of contaminating feeder cells. Given the dose-response effect of CD154 on target B cells, it is important to measure the amount of CD154 when using soluble membranes. We hereby report a simple method, based on cytometry analysis, to estimate the relative number of CD154 molecules in membrane extracts, allowing reproducibility in human B-cell activation level.

Incorporation of CD40 ligand into the envelope of pseudotyped single-cycle Simian immunodeficiency viruses enhances immunogenicity

A vaccine for the prevention of human immunodeficiency virus (HIV) infection is desperately needed to control the AIDS pandemic. To address this problem, we developed vesicular stomatitis virus glycoprotein-pseudotyped replication-defective simian immunodeficiency viruses (dSIVs) as an AIDS vaccine strategy. The dSIVs retain characteristics of a live attenuated virus without the drawbacks of potential virulence caused by replicating virus. To improve vaccine immunogenicity, we incorporated CD40 ligand (CD40L) into the dSIV envelope. CD40L is one of the most potent stimuli for dendritic cell (DC) maturation and activation. Binding of CD40L to its receptor upregulates expression of major histocompatibility complex class I, class II, and costimulatory molecules on DCs and increases production of proinflammatory cytokines and chemokines, especially interleukin 12 (IL-12). This cytokine polarizes CD4(+) T cells to Th1-type immune responses. DC activation and mixed lymphocyte reaction (MLR) studies were performed to evaluate the immunogenicity of CD40L-dSIV in vitro. Expression levels of CD80, CD86, HLA-DR, and CD54 on DCs transduced with the dSIV incorporating CD40L (CD40L-dSIV) were significantly higher than on those transduced with dSIV. Moreover, CD40L-dSIV-transduced DCs expressed up to 10-fold more IL-12 than dSIV-transduced DCs. CD40L-dSIV-transduced DCs enhanced proliferation and gamma interferon secretion by naive T cells in an MLR. In addition, CD40L-dSIV-immunized mice exhibited stronger humoral and cell-mediated immune responses than dSIV-vaccinated animals. The results show that incorporating CD40L into the dSIV envelope significantly enhances immunogenicity. As a result, CD40L-dSIVs can be strong candidates for development of a safe and highly immunogenic AIDS vaccine.

Peripheral blood CD27+ IgG+ B cells rapidly proliferate and differentiate into immunoglobulin-secreting cells after exposure to low CD154 interaction

In vitro CD40 stimulation of human B cells isolated from lymphoid organs is dominated by memory B cells undergoing faster proliferation and higher differentiation than naive B cells. In contrast, we previously reported that blood memory B cells mainly differentiate into immunoglobulin-secreting cells in response to CD40 stimulation. However, variations in CD40-CD154 interaction are now recognized to influence B-cell fate. In this study, we have compared the in vitro response of blood CD27(-) and CD27(-) IgG(-) to CD27(+) and CD27(+) IgG(+) B cells following low-density exposure to CD154 in the presence of a mixture of interleukin-2 (IL-2), IL-4 and IL-10. The evolution of these cell populations was monitored during initiation and following long-term stimulation. Over a 5-day period, CD27(+) B cells underwent differentiation into immunoglobulin-secreting cells more readily than CD27(-) cells, and CD27(+) IgG(+) B cells gave rise to a near homogeneous population of CD19(+) CD27(++) CD38(+) IgG(lo) cells capable of high immunoglobulin G (IgG) secretion. During the same period, CD27(-) IgG(-) B cells partially became CD19(++) CD27(-) CD38(-) IgG(++) cells but showed no IgG secretion. Long-term stimulation revealed that CD27(+) IgG(+) B cells retained a high expansion capacity and could maintain their momentum towards differentiation over naive B cells. In addition, long-term stimulation was driving CD27(-) IgG(-) and total CD19(+) B cells to evolve into similar CD27(+) and CD27(-) subsets, suggesting naive homeostatic proliferation. Overall, these results tend to reconcile memory B cells from blood and lymphoid organs regarding their preferential differentiation capacity compared to naive cells, and further suggest that circulating memory IgG(+) cells may be intrinsically prone to rapid activation upon appropriate stimulation.

Chemotherapy targeted to cancer tissue potentiates antigen-specific immune response induced by vaccine for in vivo antigen loading and activation of dendritic cells

Our laboratory has created an Ad-sig-TAA/ecdCD40L vaccine platform designed to activate dendritic cells (DCs). Two subcutaneous (s.c.) injections of the TAA/ecdCD40L protein following the s.c. injection of the Ad-sig-TAA/ecdCD40L vector (TAA/ecdCD40L VPP vaccine) further increases the levels of the tumor-associated antigen (TAA)-specific CD8 effector T cells induced by the vector. We tested the combined effect of chemotherapy-induced destruction of tumor cells and TAA/ecdCD40L VPP vaccine which further increases the levels of TAA available to the DCs at the time of vaccination. The chemotherapy was delivered selectively to the tumor cells using intratumoral (i.t.) injection of the AdCDIRESE1A vector followed by intraperitoneal (i.p.) 5-fluorocytosine (5FC). The 5-fluorouracil (5FU) produced in the vector infected the tumor cells, destroys them and releases the TAA for processing and presentation by the DCs. This mode of delivery spares the TAA CD8 effector T cells from the destructive effect of the 5FU when their proliferation is induced by the vaccine. Test mice treated with both the s.c. administered TAA/ecdCD40L VPP vaccine and the AdCDIRESE1A/5FC chemosensitization vector had the smallest tumor volumes and survived longer than mice treated with either of these agents alone (P < 0.001).

Cellular and molecular characterisation of the hyper immunoglobulin M syndrome associated with congenital rubella infection

INTRODUCTION

The hyper-immunoglobulin M syndrome (HIM) is a rare group of immune deficiency disorders characterised by normal or increased serum IgM with normal or reduced IgG, IgA and IgE.

MATERIALS AND METHODS

We have undertaken detailed cellular and molecular studies in a 53-year-old man with HIM as a result of congenital rubella.

RESULTS

No mutations were detected in the CD40 ligand, activation-induced cytidine deaminase and uracil DNA glycosylase. His T-cell responses to lectins and antigens were normal. Flow cytometry confirmed the presence of CD40 ligand on activated T cells. Most CD40-dependent functions that were tested, including B-cell proliferation, isotype switching and production of memory B cells, were normal. CD40/IL4 dependent rescue from anti-IgM-induced apoptosis was impaired.

CONCLUSION

The detection of cell-surface IgG but lack of serum IgG indicated that he may have an antibody secretion defect.

Characterisation of soluble murine CD137 and its association with systemic lupus

CD137 is a member of the tumor necrosis factor receptor family, and is involved in the regulation of activation, proliferation, differentiation and apoptosis of T cells, B cells, monocytes, dendritic cells, natural killer cells and granulocytes. Here report that soluble forms of murine CD137 (sCD137) are generated by differential splicing and are released by activated T cells. Levels of sCD137 correlate with cell activation and the extent of cell death but not with cellular proliferation. While CD8+ T cells express significantly more cell surface CD137 than CD4+ T cells, both T cell subsets express similar levels of sCD137, resulting a twofold increased ratio of soluble to cell surface CD137 for CD4+ T cells. sCD137 exists as a trimer and a higher order multimer, can bind to CD137 ligand, and inhibits secretion of IL-10 and IL-12. sCD137 is present in sera of mice with autoimmune disease but is undetectable in sera of healthy mice.

Macrophages prevent the differentiation of autoreactive B cells by secreting CD40 ligand and interleukin-6

Activation of the innate immune system promotes polyclonal antibody secretion to eliminate invading pathogens. Inherent in this process is the potential to activate autoreactive B cells and induce autoimmunity. We showed previously that TLR-stimulated dendritic cells and macrophages regulate B cell tolerance to Smith antigen, in part through the secretion of interleukin-6 (IL-6). In this manuscript, we show that neutralization of IL-6 fails to abrogate macrophage-mediated repression and identify soluble CD40 ligand (CD40L) as a second repressive factor secreted by macrophages. CD40L selectively repressed Ig secretion by chronically antigen-experienced (anergic) immunoglobulin transgenic and nontransgenic B cells but not by transiently stimulated B cells. The importance of macrophages in maintaining B cell tolerance was apparent in lupus-prone MRL/lpr mice. Compared with C57BL/6 mice, macrophages from MRL/lpr mice were significantly less efficient at repressing immunoglobulin secretion coincident with diminished IL-6 and CD40 ligand production. These data indicate that macrophages regulate autoreactive B cells by secreting repressive factors that prohibit terminal differentiation of B cells. The regulation of autoreactive B cells by macrophages is diminished in lupus-prone mice suggesting a role in autoimmunity.

Macrophages prevent the differentiation of autoreactive B cells by secreting CD40 ligand and interleukin-6

Activation of the innate immune system promotes polyclonal antibody secretion to eliminate invading pathogens. Inherent in this process is the potential to activate autoreactive B cells and induce autoimmunity. We showed previously that TLR-stimulated dendritic cells and macrophages regulate B cell tolerance to Smith antigen, in part through the secretion of interleukin-6 (IL-6). In this manuscript, we show that neutralization of IL-6 fails to abrogate macrophage-mediated repression and identify soluble CD40 ligand (CD40L) as a second repressive factor secreted by macrophages. CD40L selectively repressed Ig secretion by chronically antigen-experienced (anergic) immunoglobulin transgenic and nontransgenic B cells but not by transiently stimulated B cells. The importance of macrophages in maintaining B cell tolerance was apparent in lupus-prone MRL/lpr mice. Compared with C57BL/6 mice, macrophages from MRL/lpr mice were significantly less efficient at repressing immunoglobulin secretion coincident with diminished IL-6 and CD40 ligand production. These data indicate that macrophages regulate autoreactive B cells by secreting repressive factors that prohibit terminal differentiation of B cells. The regulation of autoreactive B cells by macrophages is diminished in lupus-prone mice suggesting a role in autoimmunity.

CD40-CD40L interaction in immunity against protozoan infections

Activation of the immune system against protozoan infections relies particularly on two specific signals provided by cognate interaction of T cells with antigen presenting cells (APCs). The first signal is attributed to binding of the T-cell receptor (TCR) to peptide/MHC complexes on the surface of APCs, whereas the second signal is triggered through binding of several costimulatory molecules on the surface of APCs with their corresponding receptors on T cells. Among these costimulatory signallings, CD40/CD40L interactions have been particularly investigated in protozoan infection models with regard to their potential to amplify cell-mediated immunity against intracellular parasites. This article reviews current studies of the potential role of CD40/CD40L interaction in the modulation of immune responses against some protozoan parasites and highlights recent developments regarding manipulation of this interaction for promoting control of parasite infections.

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.

Identification and characterization of functional CD154 (CD40 ligand) in the Pekin duck

Binding of CD154, a member of the TNF ligand superfamily, to its receptor CD40 is essential for the development and regulation of adaptive immune responses in mammals. The duck CD154 (DuCD154) encoding gene was isolated from activated splenocytes using RT-PCR. Sequence analysis of the cloned DuCD154 gene revealed an open reading frame of 819 base pairs encoding a 272 amino acid protein. The extracellular domain of DuCD154 was identified and expressed for characterization and generation of antibodies. DuCD154 mRNA was predominantly expressed in spleen, thymus and duodenum. DuCD154 protein generated in cell culture was secreted and formed dimers. DuCD154 markedly enhanced proliferative responses in duck splenocytes when used alone or in conjunction with LPS or PHA. These observations suggest that DuCD154 has functional equivalence with mammalian CD154 and that the central role of CD154 as an immunoregulatory protein had already evolved before the divergence of birds and mammals.

Immunotargeting with CD154 (CD40 ligand) enhances DNA vaccine responses in ducks

Engagement of CD154 on activated T cells with CD40 on antigen-presenting cells (APCs) potentiates adaptive immune responses in mammals. Soluble multimeric forms of CD154 have been used as an adjuvant or in immunotargeting strategies to enhance vaccine responses. The objective of our study was to examine the ability of duck CD154 (DuCD154) to enhance DNA vaccine responses in the duck hepatitis B model. Constructs were generated to express the functional domain of DuCD154 (tCD154), truncated duck hepatitis B virus (DHBV) core antigen (tcore) and chimera of tcore fused to tCD154 (tcore-tCD154). Expression in LMH cells demonstrated that all proteins were secreted and that tCD154 and tcore-tCD154 formed multimers. Ducks immunized with the plasmid ptcore-tCD154 developed accelerated and enhanced core-specific antibody responses compared to ducks immunized with ptcore or ptcore plus ptCD154. Antibody responses were better sustained in both ptcore-tCD154- and ptcore plus ptCD154-immunized ducks. Core-specific proliferative responses of duck peripheral blood mononuclear cells were enhanced in ducks immunized with ptcore-tCD154 or ptcore alone. This study suggests that the role of CD154 in the regulation of adaptive immune responses had already evolved before the divergence of birds and mammals. Thus, targeting of antigens to APCs with CD154 is an effective strategy to enhance DNA vaccine responses not only in mammalian species but also in avian species.

ADAM10 is a principal 'sheddase' of the low-affinity immunoglobulin E receptor CD23

CD23, the low-affinity immunoglobulin E receptor, is an important modulator of the allergic response and of diseases such as rheumatoid arthritis. The proteolytic release of CD23 from cells is considered a key event in the allergic response. Here we used loss-of-function and gain-of-function experiments with cells lacking or overexpressing candidate CD23-releasing enzymes (ADAM8, ADAM9, ADAM10, ADAM12, ADAM15, ADAM17, ADAM19 and ADAM33), ADAM-knockout mice and a selective inhibitor to identify ADAM10 as the main CD23-releasing enzyme in vivo. Our findings provide a likely target for the treatment of allergic reactions and set the stage for further studies of the involvement of ADAM10 in CD23-dependent pathologies.

Rapid and efficient nonviral gene delivery of CD154 to primary chronic lymphocytic leukemia cells

Interactions between CD40 and CD40 ligand (CD154) are essential in the regulation of both humoral and cellular immune responses. Forced expression of human CD154 in B chronic lymphocytic leukemia (B-CLL) cells can upregulate costimulatory and adhesion molecules and restore antigen-presenting capacity. Unfortunately, B-CLL cells are resistant to direct gene manipulation with most currently available gene transfer systems. In this report, we describe the use of a nonviral, clinical-grade, electroporation-based gene delivery system and a standard plasmid carrying CD154 cDNA, which achieved efficient (64+/-15%) and rapid (within 3 h) transfection of primary B-CLL cells. Consistent results were obtained from multiple human donors. Transfection of CD154 was functional in that it led to upregulated expression of CD80, CD86, ICAM-I and MHC class II (HLA-DR) on the B-CLL cells and induction of allogeneic immune responses in MLR assays. Furthermore, sustained transgene expression was demonstrated in long-term cryopreserved transfected cells. This simple and rapid gene delivery technology has been validated under the current Good Manufacturing Practice conditions, and multiple doses of CD154-expressing cells were prepared for CLL patients from one DNA transfection. Vaccination strategies using autologous tumor cells manipulated ex vivo for patients with B-CLL and perhaps with other hematopoietic malignancies could be practically implemented using this rapid and efficient nonviral gene delivery system.

Vector Prime/Protein Boost Vaccine That Overcomes Defects Acquired during Aging and Cancer

We showed that the Ad-sig-TAA/ecdCD40L vaccine induces a tumor suppressive immune response to the hMUC-1 and rH2N tumor-associated self Ags (TAA) and to the Annexin A1 tumor vascular Ag, even in mice in which anergy exists to these Ags. When the TAA/ecdCD40L protein is given s.c. as a boost following the Ad-sig-TAA/ecdCD40L vector, the levels of the TAA-specific CD8 T cells and Abs increase dramatically over that seen with vector alone, in young (2-mo-old) as well as old (18-mo-old) mice. The Abs induced against hMUC-1 react with human breast cancer. This vaccine also induces a 4-fold decrement of negative regulatory CD4CD25FOXP3-T cells in the tumor tissue of 18-mo-old mice. These results suggest that the Ad-sig-TAA/ecdCD40L vector prime-TAA/ecdCD40L protein boost vaccine platform may be valuable in reducing postsurgery recurrence in a variety of epithelial neoplasms.

Short communication: impairment of membrane markers on peripheral blood mononuclear cells and imbalance of cytokine secretion in the pathogenesis of multiple sclerosis active phases

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS). In active disease, a transmigration of autoreactive T cells to myelin antigens recruited from the peripheral blood (PBMC) to the CNS occurs, and there these cells prolong their survival and contribute to the perpetuation of the inflammation. In the active local lesions of MS patients, these cells display activation and apoptosis surface markers and secrete a range of cytokines. The aim of this research is to study on PBMCs and in the serum of stable and active MS subjects (1) the behavior of the CD40/CD40L system and the consequent balance of Th1 and Th2 cytokines and (2) the apoptosis marker system CD95/CD95L and tumor necrosis factor (TNF)- binding receptors, TNFRI and TNFRII. A possible excess of activation marker expression affecting and driving Th1 cytokine production or a parallel impairment of apoptosis may contribute to MS relapses. Our results may indicate that a dysregulation of early activation and apoptosis receptor systems and a profound and complex imbalance of cytokine production occurred in the peripheral blood of MS patients. This impairment could account for active phases of the disease.

Differential responses of human B-lymphocyte subpopulations to graded levels of CD40-CD154 interaction

Naïve and memory B-lymphocyte populations are activated by CD154 interaction through cell-surface CD40. This interaction plays an important role in the regulation of the humoral immune response, and increasing evidence indicates that fine variation in CD40 binding influences B lymphocytes, macrophages and dendritic cells in murine models. Here we have investigated whether and how variations in the intensity of the CD40-CD154 interaction could contribute to differential regulation of human B-lymphocyte populations. Proliferation and differentiation of B lymphocytes were monitored in response to graded levels of CD40 stimulation in the presence of interleukin (IL)-2, IL-4 and IL-10. Our results show that the level of CD154 binding to CD40 on B lymphocytes can directly influence the evolution of CD19(+) CD27(-) and CD19(+) CD27(+) cell populations. Furthermore, proliferation, global expansion of CD19(+) cells and emergence of CD38(++) CD138(+) cells, as well as immunoglobulin G (IgG) and IgM secretion, were affected by the level of exposure of B lymphocytes to CD154. These results suggest that the CD40-CD154 interaction is more like a rheostat than an on/off switch, and its variation of intensity may play a role in the regulation of B-lymphocyte activation following the primary and/or secondary humoral immune response.