4-1BB co-stimulation enhances human CD8(+) T cell priming by augmenting the proliferation and survival of effector CD8(+) T cells

Batf3+ DCs and the 4-1BB/4-1BBL axis are required at the effector phase in the tumor microenvironment for PD-1/PD-L1 blockade efficacy

The cellular source of positive signals that reinvigorate T cells within the tumor microenvironment (TME) for the therapeutic efficacy of programmed death-1 (PD-1)/programmed death-ligand 1 (PD-L1) blockade has not been clearly defined. We now show that Batf3-lineage dendritic cells (DCs) are essential in this process. Flow cytometric analysis, gene-targeted mice, and blocking antibody studies revealed that 4-1BBL is a major positive co-stimulatory signal provided by these DCs within the TME that translates to CD8+ T cell functional reinvigoration and tumor regression. Immunofluorescence and spatial transcriptomics on human tumor samples revealed clustering of Batf3+ DCs and CD8+ T cells, which correlates with anti-PD-1 efficacy. In addition, proximity to Batf3+ DCs within the TME is associated with CD8+ T cell transcriptional states linked to anti-PD-1 response. Our results demonstrate that Batf3+ DCs within the TME are critical for PD-1/PD-L1 blockade efficacy and indicate a major role for the 4-1BB/4-1BB ligand (4-1BBL) axis during this process.

CEACAM6 expression and function in tumor biology: a comprehensive review

Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) is an immunoglobulin superfamily protein primarily expressed on epithelial surfaces and myeloid cells. It plays a significant role in cancer progression by inhibiting apoptosis, promoting drug resistance, and facilitating cancer cell invasion and metastasis. Overexpression of CEACAM6 has been observed in various cancers, including lung, breast, colorectal, and hepatocellular cancers, and is associated with poorer overall survival and disease-free survival. Its differential expression on tumor cell surfaces makes it a promising cancer marker. This review aims to provide a comprehensive summary of CEACAM6's role in different cancer types, its involvement in signaling pathways, and recent advancements in CEACAM6-targeted treatments.

Pattern-recognition receptors (PRRs) in SARS-CoV-2

Pattern recognition receptors (PRRs) are specific sensors that directly recognize various molecules derived from viral or bacterial pathogens, senescent cells, damaged cells, and apoptotic cells. These sensors act as a bridge between nonspecific and specific immunity in humans. PRRs in human innate immunity were classified into six types: toll-like receptors (TLR), C-type lectin receptors (CLRs), nucleotide-binding and oligomerization domain (NOD)-like receptors (NLRs), absent in melanoma 2 (AIM2)-like receptors (ALRs), retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs), and cyclic GMP-AMP (cGAMP) synthase (cGAS). Numerous types of PRRs are responsible for recognizing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, which is immensely effective in prompting interferon responses. Detection of SARS-CoV-2 infection by PRRs causes the initiation of an intracellular signaling cascade and subsequently the activation of various transcription factors that stimulate the production of cytokines, chemokines, and other immune-related factors. Therefore, it seems that PRRs are a promising potential therapeutic approach for combating SARS-CoV-2 infection and other microbial infections. In this review, we have introduced the current knowledge of various PRRs and related signaling pathways in response to SARS-CoV-2.

FcγR requirements and costimulatory capacity of Urelumab, Utomilumab, and Varlilumab

Introduction

Targeting costimulatory receptors of the tumor necrosis factor receptor (TNFR) superfamily with agonistic antibodies is a promising approach in cancer immuno therapy. It is known that their efficacy strongly depends on FcγR cross-linking.

Methods

In this study, we made use of a Jurkat-based reporter platform to analyze the influence of individual FcγRs on the costimulatory activity of the 41BB agonists, Urelumab and Utomilumab, and the CD27 agonist, Varlilumab.

Results

We found that Urelumab (IgG4) can activate 41BB-NFκB signaling without FcγR cross-linking, but the presence of the FcγRs (CD32A, CD32B, CD64) augments the agonistic activity of Urelumab. The human IgG2 antibody Utomilumab exerts agonistic function only when crosslinked via CD32A and CD32B. The human IgG1 antibody Varlilumab showed strong agonistic activity with all FcγRs tested. In addition, we analyzed the costimulatory effects of Urelumab, Utomilumab, and Varlilumab in primary human peripheral blood mononuclear cells (PBMCs). Interestingly, we observed a very weak capacity of Varlilumab to enhance cytokine production and proliferation of CD4 and CD8 T cells. In the presence of Varlilumab the percentage of annexin V positive T cells was increased, indicating that this antibody mediated FcγR-dependent cytotoxic effects.

Conclusion

Collectively, our data underscore the importance to perform studies in reductionist systems as well as in primary PBMC samples to get a comprehensive understanding of the activity of costimulation agonists.

Delivering co-stimulatory tumor necrosis factor receptor agonism for cancer immunotherapy: past, current and future perspectives

The tumor necrosis factor superfamily (TNFSF) and their receptors (TNFRSF) are important regulators of the immune system, mediating proliferation, survival, differentiation, and function of immune cells. As a result, their targeting for immunotherapy is attractive, although to date, under-exploited. In this review we discuss the importance of co-stimulatory members of the TNFRSF in optimal immune response generation, the rationale behind targeting these receptors for immunotherapy, the success of targeting them in pre-clinical studies and the challenges in translating this success into the clinic. The efficacy and limitations of the currently available agents are discussed alongside the development of next generation immunostimulatory agents designed to overcome current issues, and capitalize on this receptor class to deliver potent, durable and safe drugs for patients.

Involvement of epigenetics in affecting host immunity during SARS-CoV-2 infection

Coronavirus disease 19 (COVID-19) is caused by a highly contagious RNA virus Severe Acute Respiratory Syndrome coronavirus-2 (SARS-CoV-2), originated in December 2019 in Wuhan, China. Since then, it has become a global public health concern and leads the disease table with the highest mortality rate, highlighting the necessity for a thorough understanding of its biological properties. The intricate interaction between the virus and the host immune system gives rise to diverse implications of COVID-19. RNA viruses are known to hijack the host epigenetic mechanisms of immune cells to regulate antiviral defence. Epigenetics involves processes that alter gene expression without changing the DNA sequence, leading to heritable phenotypic changes. The epigenetic landscape consists of reversible modifications like chromatin remodelling, DNA/RNA methylation, and histone methylation/acetylation that regulates gene expression. The epigenetic machinery contributes to many aspects of SARS-CoV-2 pathogenesis, like global DNA methylation and receptor angiotensin-converting enzyme 2 (ACE2) methylation determines the viral entry inside the host, viral replication, and infection efficiency. Further, it is also reported to epigenetically regulate the expression of different host cytokines affecting antiviral response. The viral proteins of SARS-CoV-2 interact with various host epigenetic enzymes like histone deacetylases (HDACs) and bromodomain-containing proteins to antagonize cellular signalling. The central role of epigenetic factors in SARS-CoV-2 pathogenesis is now exploited as promising biomarkers and therapeutic targets against COVID-19. This review article highlights the ability of SARS-CoV-2 in regulating the host epigenetic landscape during infection leading to immune evasion. It also discusses the ongoing therapeutic approaches to curtail and control the viral outbreak.

The emerging landscape of novel 4-1BB (CD137) agonistic drugs for cancer immunotherapy

The clinical development of 4-1BB agonists for cancer immunotherapy has raised substantial interest during the past decade. The first generation of 4-1BB agonistic antibodies entering the clinic, urelumab (BMS-663513) and utomilumab (PF-05082566), failed due to (liver) toxicity or lack of efficacy, respectively. The two antibodies display differences in the affinity and the 4-1BB receptor epitope recognition, as well as the isotype, which determines the Fc-gamma-receptor (FcγR) crosslinking activity. Based on this experience a very diverse landscape of second-generation 4-1BB agonists addressing the liabilities of first-generation agonists has recently been developed, with many entering clinical Phase 1 and 2 studies. This review provides an overview focusing on differences and their scientific rationale, as well as challenges foreseen during the clinical development of these molecules.

Co-Inhibitory Molecules – Their Role in Health and Autoimmunity; Highlighted by Immune Related Adverse Events

Immune checkpoint receptors are key players in regulating the immune response. They are responsible for both generating an immune response sufficient to kill invading pathogens, balancing the same response, and protecting against tissue destruction or the development of autoimmune events. The central role of the co-inhibitory receptors also referred to as inhibitory immune checkpoints, including PD-1 and CTLA-4 has become especially evident with the cancer treatments targeting these receptors. Blocking these pathways enhances the immune activity, resulting in both an increased chance of cancer clearance, at the same time induction of immune-related adverse events (irAE). Some of these irAE progress into actual autoimmune diseases with autoantibodies and symptoms, undistinguished from the naturally occurring diseases. This review will take advantage of the lessons learned from immune checkpoint blockade and relate this knowledge to our understanding of the same pathways in naturally occurring autoimmune diseases, mainly focusing on rheumatic diseases.

Inherited TNFSF9 deficiency causes broad Epstein-Barr virus infection with EBV+ smooth muscle tumors

Epstein-Barr virus (EBV) can infect smooth muscle cells causing smooth muscle tumors (SMTs) or leiomyoma. Here, we report a patient with a heterozygous 22q11.2 deletion/DiGeorge syndrome who developed a unique, broad, and lethal susceptibility to EBV characterized by EBV-infected T and B cells and disseminated EBV+SMT. The patient also harbored a homozygous missense mutation (p.V140G) in TNFSF9 coding for CD137L/4-1BBL, the ligand of the T cell co-stimulatory molecule CD137/4-1BB, whose deficiency predisposes to EBV infection. We show that wild-type CD137L was up-regulated on activated monocytes and dendritic cells, EBV-infected B cells, and SMT. The CD137LV140G mutant was weakly expressed on patient cells or when ectopically expressed in HEK and P815 cells. Importantly, patient EBV-infected B cells failed to trigger the expansion of EBV-specific T cells, resulting in decreased T cell effector responses. T cell expansion was recovered when CD137L expression was restored on B cells. Therefore, these results highlight the critical role of the CD137-CD137L pathway in anti-EBV immunity, in particular in the control of EBV+SMT.

Reprogramming the tumor microenvironment by genome editing for precision cancer therapy

The tumor microenvironment (TME) is essential for immune escape by tumor cells. It plays essential roles in tumor development and metastasis. The clinical outcomes of tumors are often closely related to individual differences in the patient TME. Therefore, reprogramming TME cells and their intercellular communication is an attractive and promising strategy for cancer therapy. TME cells consist of immune and nonimmune cells. These cells need to be manipulated precisely and safely to improve cancer therapy. Furthermore, it is encouraging that this field has rapidly developed in recent years with the advent and development of gene editing technologies. In this review, we briefly introduce gene editing technologies and systematically summarize their applications in the TME for precision cancer therapy, including the reprogramming of TME cells and their intercellular communication. TME cell reprogramming can regulate cell differentiation, proliferation, and function. Moreover, reprogramming the intercellular communication of TME cells can optimize immune infiltration and the specific recognition of tumor cells by immune cells. Thus, gene editing will pave the way for further breakthroughs in precision cancer therapy.

Future Prospects of Immunotherapy in Non-Small-Cell Lung Cancer Patients: Is There Hope in Other Immune Checkpoints Targeting Molecules?

Currently, one of the leading treatments for non-small-cell lung cancer is immunotherapy involving immune checkpoint inhibitors. These monoclonal antibodies restore the anti-tumour immune response altered by negative immune checkpoint interactions. The most commonly used immunotherapeutics in monotherapy are anti-PD-1 and anti-PD-L1 antibodies. The effectiveness of both groups of antibodies has been proven in many clinical trials, which have translated into positive immunotherapeutic registrations for cancer patients worldwide. These antibodies are generally well tolerated, and certain patients achieve durable responses. However, given the resistance of some patients to this form of therapy, along with its other drawbacks, such as adverse events, alternatives are constantly being sought. Specifically, new drugs targeting already known molecules are being tested, and new potential targets are being explored. The aim of this paper is to provide an overview of the latest developments in this area.

Novel Discoveries in Immune Dysregulation in Inborn Errors of Immunity

With the expansion of our knowledge on inborn errors of immunity (IEI), it gradually becomes clear that immune dysregulation plays an important part. In some cases, autoimmunity, hyperinflammation and lymphoproliferation are far more serious than infections. Thus, immune dysregulation has become significant in disease monitoring and treatment. In recent years, the wide application of whole-exome sequencing/whole-genome sequencing has tremendously promoted the discovery and further studies of new IEI. The number of discovered IEI is growing rapidly, followed by numerous studies of their pathogenesis and therapy. In this review, we focus on novel discovered primary immune dysregulation diseases, including deficiency of SLC7A7, CD122, DEF6, FERMT1, TGFB1, RIPK1, CD137, TET2 and SOCS1. We discuss their genetic mutation, symptoms and current therapeutic methods, and point out the gaps in this field.

Boosting Antitumor Response by Costimulatory Strategies Driven to 4-1BB and OX40 T-cell Receptors

Immunotherapy explores several strategies to enhance the host immune system’s ability to detect and eliminate cancer cells. The use of antibodies that block immunological checkpoints, such as anti–programed death 1/programed death 1 ligand and cytotoxic T-lymphocyte–associated protein 4, is widely recognized to generate a long-lasting antitumor immune response in several types of cancer. Evidence indicates that the elimination of tumors by T cells is the key for tumor control. It is well known that costimulatory and coinhibitory pathways are critical regulators in the activation of T cells. Besides blocking checkpoints inhibitors, the agonistic signaling on costimulatory molecules also plays an important role in T-cell activation and antitumor response. Therefore, molecules driven to costimulatory pathways constitute promising targets in cancer therapy. The costimulation of tumor necrosis factor superfamily receptors on lymphocytes surface may transduce signals that control the survival, proliferation, differentiation, and effector functions of these immune cells. Among the members of the tumor necrosis factor receptor superfamily, there are 4-1BB and OX40. Several clinical studies have been carried out targeting these molecules, with agonist monoclonal antibodies, and preclinical studies exploring their ligands and other experimental approaches. In this review, we discuss functional aspects of 4-1BB and OX40 costimulation, as well as the progress of its application in immunotherapies.

A Fas-4-1BB fusion protein converts a death to a pro-survival signal and enhances T cell therapy

Adoptive T cell therapy (ACT) with genetically modified T cells has shown impressive results against some hematologic cancers, but efficacy in solid tumors can be limited by restrictive tumor microenvironments (TMEs). For example, Fas ligand is commonly overexpressed in TMEs and induces apoptosis in tumor-infiltrating, Fas receptor-positive lymphocytes. We engineered immunomodulatory fusion proteins (IFPs) to enhance ACT efficacy, combining an inhibitory receptor ectodomain with a costimulatory endodomain to convert negative into positive signals. We developed a Fas-4-1BB IFP that replaces the Fas intracellular tail with costimulatory 4-1BB. Fas-4-1BB IFP-engineered murine T cells exhibited increased pro-survival signaling, proliferation, antitumor function, and altered metabolism in vitro. In vivo, Fas-4-1BB ACT eradicated leukemia and significantly improved survival in the aggressive KPC pancreatic cancer model. Fas-4-1BB IFP expression also enhanced primary human T cell function in vitro. Thus, Fas-4-1BB IFP expression is a novel strategy to improve multiple T cell functions and enhance ACT against solid tumors and hematologic malignancies.

COVID-19: immunopathogenesis and Immunotherapeutics

The recent novel coronavirus disease (COVID-19) outbreak, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is seeing a rapid increase in infected patients worldwide. The host immune response to SARS-CoV-2 appears to play a critical role in disease pathogenesis and clinical manifestations. SARS-CoV-2 not only activates antiviral immune responses, but can also cause uncontrolled inflammatory responses characterized by marked pro-inflammatory cytokine release in patients with severe COVID-19, leading to lymphopenia, lymphocyte dysfunction, and granulocyte and monocyte abnormalities. These SARS-CoV-2-induced immune abnormalities may lead to infections by microorganisms, septic shock, and severe multiple organ dysfunction. Therefore, mechanisms underlying immune abnormalities in patients with COVID-19 must be elucidated to guide clinical management of the disease. Moreover, rational management of the immune responses to SARS-CoV-2, which includes enhancing anti-viral immunity while inhibiting systemic inflammation, may be key to successful treatment. In this review, we discuss the immunopathology of COVID-19, its potential mechanisms, and clinical implications to aid the development of new therapeutic strategies against COVID-19.

Lung under attack by COVID-19-induced cytokine storm: pathogenic mechanisms and therapeutic implications

The lung is a key target of the cytokine storm that can be triggered by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), responsible for the widespread clinical syndrome known as coronavirus disease 2019 (COVID-19). Indeed, in some patients, SARS-CoV-2 promotes a dysfunctional immune response that dysregulates the cytokine secretory pattern. Hypercytokinemia underlies the hyperinflammatory state leading to injury of alveolar epithelial cells and vascular endothelial cells, as well as to lung infiltration sustained by neutrophils and macrophages. Within such a pathogenic context, interleukin-6 (IL-6) and other cytokines/chemokines play a pivotal pro-inflammatory role. Therefore, cytokines and their receptors, as well as cytokine-dependent intracellular signalling pathways can be targeted by potential therapies aimed to relieve the heavy burden of cytokine storm. In particular, the anti-IL-6-receptor monoclonal antibody tocilizumab is emerging as one of the most promising pharmacologic treatments. The reviews of this paper are available via the supplemental material section.

4-1BBL has a Possible Role in Mediating Castration-Resistant Conversion of Prostate Cancer via Up-Regulation of Androgen Receptor

4-1BB ligand (4-1BBL) was a transmembrane glycoprotein belonging to the tumor necrosis factor family. It was expressed on activated T lymphocytes and function as a co-stimulatory molecule via cross-linking with 4-1BB (a.k.a, CD137). In addition to its role in immune regulation, 4-1BBL transmitted signals into the cells on which it was expressed (reverse signaling). 4-1BBL represented a promising target for enhancing antitumor immune responses. Recent studies indicated that 4-1BBL also expressed in non-immune cells and possessed different functions in various types of cells. Here, we reported that 4-1BBL didn't express in normal prostate tissues and benign prostatic hyperplasia tissues, but it expressed in prostate cancer (PCa) tissues at moderate level. Expression of 4-1BBL was up-regulated during the transition from PCa to castration resistant prostate cancer (CRPC). Increasing expression of 4-1BBL not only promoted expression of androgen receptor (AR), but also augmented proliferation and invasion ability of prostate cancer cells in androgen deprivation environment. These results were further verified by xenograft tumor experiments. Meanwhile, inhibiting AR signal pathway by chemical antagonist was able to significantly reduce 4-1BBL mediated proliferation and invasion of PCa cells. These novel findings indicated that 4-1BBL might mediate prostate cancer progression to castration-resistant prostate cancer via enhancing expression and function of AR.

Immunodeficiency and EBV-induced lymphoproliferation caused by 4-1BB deficiency

BACKGROUND

The tumor TNF receptor family member 4-1BB (CD137) is encoded by TNFRSF9 and expressed on activated T cells. 4-1BB provides a costimulatory signal that enhances CD8⁺ T-cell survival, cytotoxicity, and mitochondrial activity, thereby promoting immunity against viruses and tumors. The ligand for 4-1BB is expressed on antigen-presenting cells and EBV-transformed B cells.

OBJECTIVE

We investigated the genetic basis of recurrent sinopulmonary infections, persistent EBV viremia, and EBV-induced lymphoproliferation in 2 unrelated patients.

METHODS

Whole-exome sequencing, immunoblotting, immunophenotyping, and in vitro assays of lymphocyte and mitochondrial function were performed.

RESULTS

The 2 patients shared a homozygous G109S missense mutation in 4-1BB that abolished protein expression and ligand binding. The patients' CD8⁺ T cells had reduced proliferation, impaired expression of IFN-γ and perforin, and diminished cytotoxicity against allogeneic and HLA-matched EBV-B cells. Mitochondrial biogenesis, membrane potential, and function were significantly reduced in the patients' activated T cells. An inhibitory antibody against 4-1BB recapitulated the patients' defective CD8⁺ T-cell activation and cytotoxicity against EBV-infected B cells in vitro.

CONCLUSION

This novel immunodeficiency demonstrates the critical role of 4-1BB costimulation in host immunity against EBV infection.

Osteopontin mediates glioblastoma-associated macrophage infiltration and is a potential therapeutic target

Glioblastoma is highly enriched with macrophages, and osteopontin (OPN) expression levels correlate with glioma grade and the degree of macrophage infiltration; thus, we studied whether OPN plays a crucial role in immune modulation. Quantitative PCR, immunoblotting, and ELISA were used to determine OPN expression. Knockdown of OPN was achieved using complementary siRNA, shRNA, and CRISPR/Cas9 techniques, followed by a series of in vitro functional migration and immunological assays. OPN gene-deficient mice were used to examine the roles of non-tumor-derived OPN on survival of mice harboring intracranial gliomas. Patients with mesenchymal glioblastoma multiforme (GBM) show high OPN expression, a negative survival prognosticator. OPN is a potent chemokine for macrophages, and its blockade significantly impaired the ability of glioma cells to recruit macrophages. Integrin αvβ5 (ITGαvβ5) is highly expressed on glioblastoma-infiltrating macrophages and constitutes a major OPN receptor. OPN maintains the M2 macrophage gene signature and phenotype. Both tumor-derived and host-derived OPN were critical for glioma development. OPN deficiency in either innate immune or glioma cells resulted in a marked reduction in M2 macrophages and elevated T cell effector activity infiltrating the glioma. Furthermore, OPN deficiency in the glioma cells sensitized them to direct CD8+ T cell cytotoxicity. Systemic administration in mice of 4-1BB-OPN bispecific aptamers was efficacious, increasing median survival time by 68% (P < 0.05). OPN is thus an important chemokine for recruiting macrophages to glioblastoma, mediates crosstalk between tumor cells and the innate immune system, and has the potential to be exploited as a therapeutic target.

Features of Effective T Cell-Inducing Vaccines against Chronic Viral Infections

For many years, the focus of prophylactic vaccines was to elicit neutralizing antibodies, but it has become increasingly evident that T cell-mediated immunity plays a central role in controlling persistent viral infections such as with human immunodeficiency virus, cytomegalovirus, and hepatitis C virus. Currently, various promising prophylactic vaccines, capable of inducing substantial vaccine-specific T cell responses, are investigated in preclinical and clinical studies. There is compelling evidence that protection by T cells is related to the magnitude and breadth of the T cell response, the type and homing properties of the memory T cell subsets, and their cytokine polyfunctionality and metabolic fitness. In this review, we evaluated these key factors that determine the qualitative and quantitative properties of CD4+ and CD8+ T cell responses in the context of chronic viral disease and prophylactic vaccine development. Elucidation of the mechanisms underlying T cell-mediated protection against chronic viral pathogens will facilitate the development of more potent, durable and safe prophylactic T cell-based vaccines.

Improved Cytotoxic T Lymphocyte Responses to Vaccination with Porcine Reproductive and Respiratory Syndrome Virus in 4-1BB Transgenic Pigs

Vaccination is the most reliable measure to prevent infectious diseases in domestic animals. Development of novel vaccines demands extensive studies with new technologies, such as using novel adjuvants and immunomodulatory molecules. The co-stimulatory molecule 4-1BB provides a key signal that directs the fate of T cells during activation, and thus is important to their function in immune protection. To determine whether host immune responses to viral infection could be promoted by enhancing 4-1BB co-stimulation, in this study, we produced transgenic pig clones expressing an extra copy of the 4-1BB gene by clustered regularly interspaced short palindromic repeats/CRISPR-associated gene 9-mediated homologous recombination at the Rosa26 locus. The immune responses of transgenic pigs to porcine reproductive and respiratory syndrome virus (PRRSV) vaccine were determined on day 14. We show that peripheral blood lymphocytes of transgenic pigs expressed around twice the level of 4-1BB mRNA than those of control pigs. We also found IL-2, TNF-α, and granzyme B mRNA levels as well as PRRSV-specific IFN-γ response were significantly upregulated in 4-1BB transgenic pigs, leading to more efficient cytotoxic T lymphocyte (CTL) killing, whereas the expressions of IL-4, IL-17, and Foxp3 were not affected. These results indicate that higher levels of 4-1BB expression involve in promoting Th1 differentiation and enhancing specific CTL responses to PRRSV, and provide a novel approach to increase the efficacy of current vaccines to control the infectious diseases.

Potent anti-prostate cancer immune response induced by dendritic cells transduced with recombinant adenoviruses encoding 4-1BBL combined with cytokine-induced killer cells

AIM

To test the effect of dendritic cells (DCs) transduced with recombinant adenoviruses encoding 4-1BBL combined with cytokine-induced killer cells (CIKs) against prostate cancer.

METHOD

Flow cytometry was used to detect the surface markers of the co-cultured cells, and cytotoxicity against prostate cancer cells in vitro as well as antitumor activities in vivo were observed.

RESULTS

Our results showed that Ad-4-1BBL-transduced DCs could increase percentage of CD3(+)CD56(+) cells in CIKs, and CIKs co-cultured with Ad-4-1BBL-transduced DCs could augment the secretion of IL-12 and IFN-γ and decrease TGF-β production. In addition, Ad-4-1BBL-transduced DCs enhanced the cytotoxicity of CIKs against prostate cancer and resulted in inhibition of tumor growth and tumor-bearing animals' survival.

CONCLUSION

These results demonstrate that 4-1BBL-engineered DCs can improve CIKs cytotoxicity against prostate cancer cells.

Depletion of Alloreactive T-Cells by Anti-CD137-Saporin Immunotoxin

Depletion of alloreactive T-lymphocytes from allogeneic bone marrow tansplants may prevent graft-versus-host disease (GVHD) without impairing donor cell engraftment, immunity, and the graft-versus-leukemia (GVL) effect. Alloreactive T-cells may be identified by their expression, upon activation, of CD137, a costimulatory receptor and putative surrogate marker for antigen-specific effector T-cells. In this context, we tested the use of anti-CD137-saporin immunotoxin to selectively deplete mouse and human alloreactive T-cells. Anti-CD137 antibodies were internalized by cells within 4 h of binding to the cell surface CD137, and anti-CD137-saporin immunotoxin effectively killed polyclonally activated T-cells or antigen-stimulated T-cells. Transfer of donor T-cells after allodepletion with anti-CD137-saporin immunotoxin failed to induce any evident expression of GVHD; however, a significant GVL effect was observed. Targeting of CD137 with an immunotoxin was also effective in killing polyclonally activated or alloreactive human T-cells. Our results indicate that anti-CD137-saporin immunotoxin may be used to deplete alloreactive T-cells prior to bone marrow transplantation and thereby prevent GVHD and the relapse of leukemia.

Recombinant Salmonella-based CEACAM6 and 4-1BBL vaccine enhances T-cell immunity and inhibits the development of colorectal cancer in rats: In vivo effects of vaccine containing 4-1BBL and CEACAM6

The present study aimed to determine the effect of recombinant Salmonella (SL3261)-based CEACAM6 and 4-1BB ligand (4-1BBL) vaccine on the development of colorectal cancer in rats and the potential immune mechanisms involved. Attenuated Salmonella typhimurium (vaccine strain)‑carrying plasmids pIRES-CEACAM6, pIRES‑4‑1BBL and pIRES-CEACAM6-4-1BBL were constructed. The rats were administered subcutaneous injections of 1,2-dimethyl-hydrazine (DMH) once a week for 18 weeks. Eight weeks after the first injection, the rats were divided into the pIRES/SL3261, pIRES-4-1BBL/SL3261, pIRES-CEACAM6/SL3261 and pIRES-CEACAM6-4-1BBL/SL3261 groups, and fed with corresponding vaccine strains. The rats were then sacrificed, the number of colon tumors were recorded, and the Dukes' stage were evaluated. CD3, CD4, CD8, CD56, FOXP3 and CEACAM6 expression in tumor tissues was determined by immunohistochemical staining. Compared with the expression levels in the pIRES/SL3261 group, similar levels of CD3+, CD8+ and CD56+ expression were identified for the pIRES-CEACAM6/SL3261 group of rats. Additionally, a comparable number of tumors was detected in the pIRES-4-1BBL/SL3261 and pIRES-CEACAM6/SL3261 groups. By contrast, a significantly fewer number of tumors, albeit with a higher density of CD3+CD8+, CD56+ and a lower density of Foxp3+ tumor-infiltrating lymphocyte (TIL) cells was detected in the pIRES-CEACAM6-4-1BBL/SL3261 group of rats. The results indicated that vaccination with recombinant attenuated Salmonella harboring the CEACAM6 and 4-1BBL gene efficiently increased the number of CD3+CD8+ TIL and NK cells, decreased the number of FOXP3 cells and inhibited the development of DMH-induced colorectal cancer in rats.

Transcriptional and posttranscriptional regulation of cytokine gene expression in HIV-1 antigen-specific CD8+ T cells that mediate virus inhibition

The ability of CD8+ T cells to effectively limit HIV-1 replication and block HIV-1 acquisition is determined by the capacity to rapidly respond to HIV-1 antigens. Understanding both the functional properties and regulation of an effective CD8+ response would enable better evaluation of T cell-directed vaccine strategies and may inform the design of new therapies. We assessed the antigen specificity, cytokine signature, and mechanisms that regulate antiviral gene expression in CD8+ T cells from a cohort of HIV-1-infected virus controllers (VCs) (<5,000 HIV-1 RNA copies/ml and CD4+ lymphocyte counts of >400 cells/μl) capable of soluble inhibition of HIV-1. Gag p24 and Nef CD8+ T cell-specific soluble virus inhibition was common among the VCs and correlated with substantial increases in the abundance of mRNAs encoding the antiviral cytokines macrophage inflammatory proteins MIP-1α, MIP-1αP (CCL3L1), and MIP-1β; granulocyte-macrophage colony-stimulating factor (GM-CSF); lymphotactin (XCL1); tumor necrosis factor receptor superfamily member 9 (TNFRSF9); and gamma interferon (IFN-γ). The induction of several of these mRNAs was driven through a coordinated response of both increased transcription and stabilization of mRNA, which together accounted for the observed increase in mRNA abundance. This coordinated response allows rapid and robust induction of mRNA messages that can enhance the CD8+ T cells' ability to inhibit virus upon antigen encounter.

IMPORTANCE

We show that mRNA stability, in addition to transcription, is key in regulating the direct anti-HIV-1 function of antigen-specific memory CD8+ T cells. Regulation at the level of RNA helps enable rapid recall of memory CD8+ T cell effector functions for HIV-1 inhibition. By uncovering and understanding the mechanisms employed by CD8+ T cell subsets with antigen-specific anti-HIV-1 activity, we can identify new strategies for comprehensive identification of other important antiviral genes. This will, in turn, enhance our ability to inhibit virus replication by informing both cure strategies and HIV-1 vaccine designs that aim to reduce transmission and can aid in blocking HIV-1 acquisition.

Artificial antigen-presenting cells expressing CD80, CD70, and 4-1BB ligand efficiently expand functional T cells specific to tumor-associated antigens

Professional antigen-presenting cells (APCs), notably dendritic cells (DCs), are the most potent for expanding antigen-specific T cells ex vivo. However, the labor-intensive and expensive procedure for customized preparation of autologous APCs has hampered their broad clinical application. Artificial APC (aAPC) systems, which can be readily prepared from off-the-shelf components, have been proposed as a promising alternative to custom-made professional APCs. Here, in order to develop a novel aAPC system, we established K562 erythroleukemia cells expressing different combinations of co-stimulatory molecule ligands, CD80, CD70, and/or 4-1BB ligand (4-1BBL). When nucleofected with in vitro-generated mRNA encoding a tumor-associated antigen, MART-1, the K562 cells expressing all of CD80, CD70, and 4-1BBL were the most efficient for expansion of functional T cells specific to an HLA-A2-restricted immunodominant epitope, MART-126-35. In addition, only the K562 cells expressing all three of these co-stimulatory molecule ligands could clearly expand T cells specific to other less immunogenic antigen epitopes, gp100154-162 and Cyp1B1239-247, through transfection with in vitro generated gp100 and Cyp1B1 mRNA, respectively. These results indicated that non-redundant and synergistic effects of co-stimulation via CD28/CD80, CD27/CD70, and 4-1BB/4-1BBL might be critical for eliciting efficient expansion of T cells; co-stimulation via the 4-1BB/4-1BBL interaction might expand antigen-specific T cells by preventing apoptotic cell death triggered by specific antigens in the presence of the CD28/CD80 and CD27/CD70 signaling. Taken together, our findings suggested that this K562-based aAPC system expressing CD80, CD70, and 4-1BBL would be useful for efficiently stimulating functional antigen-specific T cells ex vivo, in particular when detailed information on the epitope specificities is unavailable.

Apoptosis-regulated low-avidity cancer-specific CD8(+) T cells can be rescued to eliminate HER2/neu-expressing tumors by costimulatory agonists in tolerized mice

A major barrier to vaccines in cancer treatment is their failure to activate and maintain a complete cancer-specific CD8(+) effector T-cell repertoire. Low-avidity T cells are more likely to escape clonal deletion in the thymus when compared with high-avidity T cells, and therefore comprise the major population of effector T cells available for activation in patients with cancer. However, low-avidity T cells fail to traffic into the tumor microenvironment and function in eradicating tumor under optimal vaccination conditions as opposed to high-avidity T cells that escape clonal deletion and function in tumor killing. We used high- and low-avidity T-cell receptor transgenic CD8(+) T cells specific for the immunodominant epitope HER2/neu (RNEU420-429) to identify signaling pathways responsible for the inferior activity of the low-avidity T cells. Adoptive transfer of these cells into tumor-bearing vaccinated mice identified the members of apoptosis pathways that are upregulated in low-avidity T cells. The increased expression of proapoptotic proteins by low-avidity T cells promoted their own cell death and also that of other tumor-specific CD8(+) T cells within their local environment. Importantly, we show that this proapoptotic effect can be overcome by using a strong costimulatory signal that prevents the activation-induced cell death and enables the low-avidity T cells to traffic into the tumor and assist in tumor clearance. These findings identify new therapeutic opportunities for activating the most potent anticancer T-cell responses.

CD137 stimulation and p38 MAPK inhibition improve reactivity in an in vitro model of glioblastoma immunotherapy

Dendritic cell vaccination has become an interesting option for cancer immunotherapy. Tumor-lysate-pulsed dendritic cells (DC) can prime naïve T cells and induce the regression of established tumors including gliomas as shown in various animal models. Despite hopeful results even in clinical studies, the outcome for many patients is still unsatisfying. In the present study, we tested the combination of tumor-lysate-pulsed dendritic cells (TPDC) with a monoclonal antibody against CD137, a monoclonal antibody against CD25 (daclizumab) and a specific p38 mitogen-activated protein kinase (p38 MAPK) inhibitor (SB203580) for improving immunostimulation in an in vitro model of immunotherapy for human gliomas. We observed a higher secretion of interferon gamma by TPDC-primed peripheral blood mononuclear cells (PBMC) that were incubated with an antibody against CD137 or the p38 MAPK inhibitor. In addition, we observed higher specific lysis of tumor cells after incubation of PBMC with the p38 MAPK inhibitor or the anti-CD137 antibody. In contrast, incubation of TPDC-primed PBMC with the anti-CD25 antibody did enhance neither interferon gamma secretion nor cellular cytotoxicity. Cell depletion experiments demonstrated that the immune reaction induced by TPDC is strongly dependent on CD4-positive and CD8-positive cells. Incubation of DC during maturation and antigen loading with the anti-CD137 antibody did not enhance cytotoxicity and interferon gamma secretion in comparison with application of the anti-CD137 antibody during priming. In conclusion, our data suggest that p38 MAPK inhibition and anti-CD137 antibodies can enhance the immune response against glioblastoma cells.

Targeting CD137 enhances vaccine-elicited anti-respiratory syncytial virus CD8+ T cell responses in aged mice

Respiratory syncytial virus (RSV) causes significant morbidity and mortality in children and the elderly. No vaccines for RSV are in use. Because of immunosenescence, the immunologic requirements for a successful RSV vaccine in the elderly might differ from a RSV vaccine for young children. Using an aged mouse model of RSV pathogenesis, we found that aged mice had impaired Ag-specific CD8(+) T cell responses and delayed RSV clearance compared with young mice. To study vaccine-elicited RSV-specific CD8(+) T cells in aged mice, we used a peptide vaccine approach. TriVax is a commixture of a peptide representing immunodominant RSV CD8(+) T cell epitope M282-90, a TLR agonist (polyinosinic-polycytidylic acid), and a costimulatory anti-CD40 Ab. TriVax vaccination generated robust, polyfunctional, and protective CD8(+) T cell responses in young BALB/c mice, but not in 18-mo-old (aged) BALB/c mice. We hypothesized that treatment of aged mice with agonistic anti-CD137 (41BB) mAb will partially restore T cell responses and TriVax efficacy in aged mice. We immunized 18-mo-old BALB/c mice twice with TriVax + anti-41BB mAb or TriVax + isotype control Ab. Coadministration of anti-41BB mAb with TriVax enhanced RSV-specific CD8(+) T cell responses and TriVax efficacy in challenge experiments. Triggering the 41BB costimulatory pathway may be a strategy for enhancing T cell responses to vaccines in the elderly.

A study of immunomodulatory genes responses to macrophages of Schistosoma japonicum infection during different stages by microarray analysis

Macrophages initiate, modulate, and also serve as final effector cells in immune responses during the course of schistosomal infections. In this study, we investigated the gene expression profile and functional changes of macrophages in immune responses against the Schistosoma japonicum by microarray analysis. Hierarchical clustering analysis demonstrated that a significant switch in gene transformation associated with a type-1 response and linked with a type-2 cytokine phenotype occurs between 4.5 and 8 weeks post-infection. Moreover, the gene profiles at 3 later time-points following egg challenge were similar in complexity and magnitude. The data also showed that there were mostly inhibition of gene expression related TLR, IFN, MHC and TNFrsf at the switch between 4.5 and 8 weeks post-infection, It is suggested that these immunomodulatory genes may be down-regulated in defense against S. japonicum eggs and granuloma pathology. The induction of alternatively activated macrophage (AAMϕ) was important for dampening the inflammation in hepatic granulomas and contributing to a decrease in cytotoxicity. The gene expressions involved in repair/remodeling during liver fibrosis were also observed after egg production. Understanding the immune mechanisms associated with parasitic resistance, pathology of parasite infection, and parasite growth will provide useful insight on host-schistosome interactions and for the control of schistosomiasis.

Recombinant Salmonella-based 4-1BBL vaccine enhances T cell immunity and inhibits the development of colorectal cancer in rats: in vivo effects of vaccine containing 4-1BBL

Background

Immunotherapy with vaccines is attractive for the treatment of cancer. This study is aimed at determining the effect of recombinant Salmonella (SL3261)-based 4-1BB ligand (4-1BBL) vaccine on the development of colorectal cancers and the potential immune mechanisms in rats.

Results

In comparison with that in the PBS group, similar levels of 4-1BBL expression, the frequency of T cells, IFN-γ responses, and comparable numbers of tumors were detected in the SL3261 and SL3261C groups of rats. In contrast, significantly fewer numbers of tumors, increased levels of 4-1BBL expression in the spleens and colorectal tissues, higher frequency of peripheral blood and splenic CD3⁺CD25⁺ T cells, and stronger splenic T cell IFN-γ responses were detected in the SL3261R group of rats.

Conclusion

Our results indicated that vaccination with recombinant attenuated Salmonella harboring the 4-1BBL gene efficiently enhanced T cell immunity and inhibited the development of carcinogen-induced colorectal cancers in rats.

Enhanced function of cytotoxic T lymphocytes induced by dendritic cells modified with truncated PSMA and 4-1BBL

Interactions between costimulatory molecules and their receptors are vital for Ag-presenting dendritic cells (DCs) to initiate T cells activation, expansion and their antitumor immune responses. Augmentation of costimulatory signal due to the interaction of DCs and T cells may amplify, sustain and drive diversity of cytotoxic T lymphocytes (CTLs) and consequently enhance the antitumor response. 4-1BBL/4-1BB is such a pair of costimulatory ligand and receptor, playing an important role in the co-stimulation of CTLs. Previously, we demonstrated that DCs transduced with recombinant adenovirus encoding truncated PSMA (tPSMA) and m4-1BBL could induce prostate cancer regression in mouse models. In the present study, we further explored the adjuvant role of 4-1BBL in modulating CTLs activation induced by tPSMA gene-pulsed DCs. The apoptosis and cytotoxicity against tPSMA expressing RM-1 cells of CTLs were determined. Results showed that tPSMA gene-pulsed DCs effectively induced T lymphocyte activation and cytotoxicity, which was enhanced by upregulated expression of 4-1BBL, displaying better cell viability, lower CTLs apoptosis, higher expression anti-apoptotic protein of Bcl-xL and phosphorylation of P38, enhanced NF-κB activation, as well as more IFN-γ production. These results demonstrated that 4-1BBL may play a significant role in the co-stimulation pathway for Ag-presenting DCs-mediated CTLs activity, which might be a beneficial adjuvant factor for DCs-based cancer immunotherapy.

4-1BB protects dendritic cells from prostate cancer-induced apoptosis

It has been shown that human prostate cancer (PCa) cells induced apoptotic death of the most potent antigen-presenting cells, dendritic cells (DCs), which are responsible for the induction of specific antitumor immune responses. Here, we investigated the function of 4-1BB on protecting DCs from prostate cancer-induced apoptosis with an agonistic mAb to 4-1BB. RM-1 cells and DCs were co-incubated for 48 h and DC apoptosis was assessed by Annexin Vassay. TNF-α and IL-12 production were assessed by enzyme-linked immunosorbent assay (ELISA) and Bcl-2 and Bcl-xL on DCs were analyzed by Western blot. We have shown that co-incubation of RM-1 cells with DCs is accompanied by an increased level of DCs apoptosis. Triggering 4-1BB on DCs resulted in increased resistance of DCs to RM-1 cells-induced apoptosis, which was owing to the up-regulated expression of Bcl-2 and Bcl-xL, and increased secretion of TNF-αand IL-12. These results demonstrate that triggering 4-1BB on DCs could increased resistance of DCs to PCa-induced apoptosis.

Chemokines, costimulatory molecules and fusion proteins for the immunotherapy of solid tumors

In this article, the role of chemokines and costimulatory molecules in the immunotherapy of experimental murine solid tumors and immunotherapy used in ongoing clinical trials are presented. Chemokine networks regulate physiologic cell migration that may be disrupted to inhibit antitumor immune responses or co-opted to promote tumor growth and metastasis in cancer. Recent studies highlight the potential use of chemokines in cancer immunotherapy to improve innate and adaptive cell interactions and to recruit immune effector cells into the tumor microenvironment. Another critical component of antitumor immune responses is antigen priming and activation of effector cells. Reciprocal expression and binding of costimulatory molecules and their ligands by antigen-presenting cells and naive lymphocytes ensures robust expansion, activity and survival of tumor-specific effector cells in vivo. Immunotherapy approaches using agonist antibodies or fusion proteins of immunomodulatory molecules significantly inhibit tumor growth and boost cell-mediated immunity. To localize immune stimulation to the tumor site, a series of fusion proteins consisting of a tumor-targeting monoclonal antibody directed against tumor necrosis and chemokines or costimulatory molecules were generated and tested in tumor-bearing mice. While several of these reagents were initially shown to have therapeutic value, combination therapies with methods to delete suppressor cells had the greatest effect on tumor growth. In conclusion, a key conclusion that has emerged from these studies is that successful immunotherapy will require both advanced methods of immunostimulation and the removal of immunosuppression in the host.

Combination immunotherapy with 4-1BBL and CTLA-4 blockade for the treatment of prostate cancer

Immune regulation has been shown to be involved in the progressive growth of some murine tumours. Interruption of immune regulatory pathways via activation of 4-1BB or cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) blockade appears to be a promising strategy for cancer immunotherapy. In this study, we examined the effectiveness of 4-1BBL-expressing tumor cell vaccine in combination with CTLA-4 blockade on rejection of murine prostate cancer RM-1. We found that the combination of both a vaccine consisting of 4-1BBL-expressing RM-1 cells and CTLA-4 blockade resulted in regression of RM-1 tumors and a significant increase in survival of the tumour cell recipients, compared to that of either treatment alone. The combined vaccination resulted in higher CTL against RM-1 cells and increased secretion of IFN-γ, TNF-α, and IL-2 in the mix-cultured supernatant. These results suggest that combining activation of 4-1BB and blockade of CTLA-4 may offer a new strategy for prostate cancer immunotherapy.

Effects of 4-1BB signaling on the biological function of murine dendritic cells

4-1BB signaling has profound effects on the T cell-induced cell immune response, but its biological function in dendritic cells (DCs) has remained largely uncharacterized. In this study, we investigated the function of 4-1BB in murine DCs with an agonistic mAb to 4-1BB. Interleukin (IL)-6 and IL-12 production was assessed by an enzyme-linked immunosorbent assay (ELISA). Co-stimulatory molecules (CD80 and CD86) in DCs were analyzed by flow cytometry. The results showed that 4-1BB was strongly expressed in DCs during the maturation process. Triggering 4-1BB increased the secretion of IL-6 and IL-12 and the upregulation of co-stimulatory molecules (CD80 and CD86) from DCs, indicating that agonistic mAb to 4-1BB directly improves the activation of DCs. Moreover, triggering 4-1BB induced a higher survival rate of DCs compared to that of hamster IgG isotype control, due to the upregulated expression of Bcl-2 and Bcl-xL. To further assess the role of 4-1BB on DCs stimulating T-cell proliferation, allogeneic mixed lymphocyte reactions were analyzed. The agonistic anti-4-1BB mAb induced a higher T-cell proliferation. These results suggest that 4-1BB affects the duration, DC-T interaction and immunogenicity of DCs.

4-1BB signaling synergizes with programmed death ligand 1 blockade to augment CD8 T cell responses during chronic viral infection

Previous studies have identified the inhibitory role that the programmed death 1 (PD-1) pathway plays during chronic infection. Blockade of this pathway results in rescue of viral-specific CD8 T cells, as well as reduction of viral loads in mice chronically infected with lymphocytic choriomeningitis virus (LCMV). We tested the effect of combining PD ligand 1 (PD-L1) blockade with an agonistic regimen that induces 4-1BB costimulation during chronic LCMV infection. There is a boosting effect in the rescue of LCMV-specific CD8 T cell responses after dual treatment with PD-L1 blockade and 4-1BB agonistic Abs when the amount and timing of 4-1BB costimulation are carefully controlled. When PD-L1-blocking Abs are given together with a single low dose of anti-4-1BB agonistic Abs, there is an enhanced and stable expansion of viral-specific CD8 T cells. Conversely, when blocking Abs to PD-L1 are given with a repetitive high dose of anti-4-1BB, there is an initial synergistic expansion of viral-specific CD8 T cells by day 7, followed by dramatic apoptosis by day 14. Viral control paralleled CD8 T cell kinetics after dual treatment. By day 7 posttreatment, viral titers were lower in both of the combined regimens (compared with PD-L1 blockade alone). However, whereas the high dose of anti-4-1BB plus PD-L1 blockade resulted in rebound of viral titers to original levels, the low dose of anti-4-1BB plus PD-L1 blockade resulted in a stable reduction of viral loads. These findings demonstrate the importance of carefully manipulating the balance between activating and inhibitory signals to enhance T cell responses during chronic infection.

Costimulation through the CD137/4-1BB pathway protects human melanoma tumor-infiltrating lymphocytes from activation-induced cell death and enhances antitumor effector function

Adoptive T-cell therapy (ACT) using expanded tumor-infiltrating lymphocytes (TIL) with high-dose interleukin-2 is a promising form of immunotherapy for stage IV melanoma having clinical response rates of 50% or more. One of the major problems preventing further success of this therapy is that the current protocols used to highly expand TIL for infusion drive CD8(+) T cells to differentiate into effector cells losing key costimulatory molecules such as CD28 and CD27. This has been associated with a lack of persistence in vivo for reasons not entirely clear. In this study, we demonstrate that while human melanoma CD8(+) TIL lost CD27 and CD28 expression during the rapid expansion for ACT, they gained expression of the alternative costimulatory molecule CD137/4-1BB, and to a lesser extent CD134/OX40. Postrapid expansion protocol (REP) TIL were found to be highly sensitive to activation-induced cell death when reactivated through the T-cell receptor with low levels of OKT3 antibody. However, coligation of 4-1BB using 2 different agonistic anti-4-1BB antibodies potently prevented activation-induced cell death of post-REP CD8(+) TIL, including those specific for melanoma antigen recognized by T cells, and facilitated even further cell expansion. This was correlated with increased levels of bcl-2 and bcl-xL together with decreased bim expression. 4-1BB costimulated post-REP TIL also expressed increased levels of the cytolytic granule proteins and exhibited enhanced cytotoxic T-cell activity against melanoma cells. Lastly, post-REP CD8(+) TIL were protected from cell death by anti-4-1BB ligation when exposed to human leukocyte antigen-matched melanoma cells. Our results indicate that 4-1BB costimulation may significantly improve TIL survival during melanoma ACT and boost antitumor cytolytic activity.

Construction of a recombinant adenovirus co-expressing truncated human prostate-specific membrane antigen and mouse 4-1BBL genes and its effect on dendritic cells

Our aim was to construct a recombinant adenovirus co-expressing truncated human prostate-specific membrane antigen (tPSMA) and mouse 4-1BBL genes and to determine its effect on dendritic cells (DCs) generated from bone marrow suspensions harvested from C57BL/6 mice for which the effect of 4-1BBL on DCs is not clear, especially during DCs processing tumor-associated antigen. Replication deficient adenovirus AdMax™ Expression System was used to construct recombinant adenovirus Ad-tPSMA-internal ribosome entry site-mouse 4-1BBL (Ad-tPSMA-IRES-m4-1BBL) and Ad-enhanced green fluorescent protein. Day 7 proliferating DC aggregates generated from C57BL/6 mice were collected as immature DCs and further mature DCs were obtained by lipopolysaccharide activated immature DCs. After DCs were exposed to the recombinant adenovirus with 250 multiplicity of infection, the expression of tPSMA and m4-1BBL proteins were detected by Western blot, and the apoptosis and phenotype of DCs were analyzed by flow cytometry. Cytokines (IL-6 and IL-12) in the supernatant were detected by enzyme-linked immunosorbent assay (ELISA). Proliferation of T cells was detected by allogeneic mixed lymphocyte reactions. The tPSMA and m4-1BBL proteins were expressed correctly. The apoptosis rate of DCs transfected with Ad-tPSMA-IRES-m4-1BBL was 14.6%, lower than that of control DCs. The expression of co-stimulatory molecules [CD80 (81.6 ± 5.4%) and CD86 (80.13 ± 2.81%)] up-regulated in Ad-tPSMA-IRES-m4-1BBL-pulsed DCs, and the level of IL-6 (3960.2 ± 50.54 pg/mL) and IL-12 (249.57 ± 12.51 pg/mL) production in Ad-tPSMA-IRES-m4-1BBL-transduced DCs were significantly higher (P < 0.05) than those in control DCs. Ad-tPSMA-IRES-m4-1BBL induced higher T-cell proliferation (OD(450) = 0.614 ± 0.018), indicating that this recombinant adenovirus can effectively enhance the activity of DCs.

Efficient inhibition of human B-cell lymphoma in SCID mice by synergistic antitumor effect of human 4-1BB ligand/anti-CD20 fusion proteins and anti-CD3/anti-CD20 diabodies

Here we constructed and produced a recombinant human 4-1BB ligand (4-1BBL)/anti-CD20 fusion protein and examined its antitumor activity, alone and in combination with an anti-CD3/anti-CD20 bispecific diabody. The 4-1BBL/anti-CD20 fusion protein retained both the costimulatory activity of 4-1BBL on T cells and the tumor targeting ability of CD20 antibody on B cells. The fusion protein bound as efficiently to 4-1BB- and CD20-positive cells as its respective parental antibodies, and was capable of cross-linking human T lymphocytes and CD20-positive tumor cells. Combination treatment with 4-1BBL/anti-CD20 fusion protein and anti-CD3/anti-CD20 diabody led to significantly increased T-cell cytotoxicity to human B-lymphoma cells in vitro and drastically more potent tumor inhibitory activity in vivo in xenografted B-cell lymphoma in severe combined immunodeficiency disease mice. Mechanistic studies revealed that the combination treatment remarkably inhibited apoptosis of human peripheral blood lymphocytes, accompanied by upregulation of Bcl-XL and Bf1-1, perforin and granzyme B mRNA, and increased interleukin-2 production. Taken together, these results suggest that targeted delivery of 4-1BBL to the tumor site, when combined with anti-CD3/anti-CD20 diabody, could strongly potentiate the antitumor activity of the diabody, thus may have significant clinical application in the treatment of human CD20-positive B-cell malignancies.

Update on vaccine development for renal cell cancer

Renal cell carcinoma (RCC) remains a significant health concern that frequently presents as metastatic disease at the time of initial diagnosis. Current first-line therapeutics for the advanced-stage RCC include antiangiogenic drugs that have yielded high rates of objective clinical response; however, these tend to be transient in nature, with many patients becoming refractory to chronic treatment with these agents. Adjuvant immunotherapies remain viable candidates to sustain disease-free and overall patient survival. In particular, vaccines designed to optimize the activation, maintenance, and recruitment of specific immunity within or into the tumor site continue to evolve. Based on the integration of increasingly refined immunomonitoring systems in both translational models and clinical trials, allowing for the improved understanding of treatment mechanism(s) of action, further refined (combinational) vaccine protocols are currently being developed and evaluated. This review provides a brief history of RCC vaccine development, discusses the successes and limitations in such approaches, and provides a rationale for developing combinational vaccine approaches that may provide improved clinical benefits to patients with RCC.

The change of immunoactivity of dendritic cells induced by mouse 4-1BBL recombinant adenovirus

PURPOSE

The purpose of this study is to construct a recombinant adenovirus vector carrying mouse 4-1BBL and observe its effects in dendritic cells.

MATERIALS AND METHODS

Mouse 4-1BBL cDNA was taken from the plasmid pcDNA3-m4- 1BBL and subcloned into adenovirus shuttle plasmid pAdTrack-CMV, and then transformed into competent BJ5183 with plasmid pAdEasy-1. After recombination in E.coli, Ad-4-1BBL was packaged and amplified in HEK 293 cells. The expression of 4-1BBL in Ad-4-1BBL-transfected mouse prostate cancer cell line RM-1 was detected by reverse transcription polymerase chain reaction (RT-PCR) and Western blot. After the co-culture of dendritic cells (DCs) with Ad-4-1BBL-transfected RM-1 cells, interleukin (IL)-6 and IL-12 production were assessed by enzyme-linked immunosorbent assay (ELISA) and co-stimulatary molecules (CD80 and CD86) on DCs were analyzed by flow cytometry.

RESULTS

The levels of IL-6 (3,960 pg/mL) and IL-12 (249 pg/mL) production in Ad-m4-1BBL-pulsed DCs were more than those in none-pulsed DCs. The differences were statistically significant (p < 0.05). The expression of co-stimulatary molecules (CD80 and CD86) was up-regulated in Ad-m4-1BBL-pulsed DCs.

CONCLUSION

The results indicated the recombinant mouse 4-1BBL can effectively activate DCs.

Regulating functional cell fates in CD8 T cells

The attributes of specificity and memory enable CD8(+) T cells to provide long-lasting protection against a variety of challenges. Although, the importance of CD8(+) T cells for protection against intracellular infections and transformation is well-established, the functional type; effector phenotypes (Tc1, Tc2, Tc17 and/or Tcreg) and/or memory (effector or central), of CD8(+) T cells most desirable for tumor immunity is not established. To determine the tumor efficacy of various effector types and/or memory CD8 T cells, it is imperative to better understand intrinsic and extrinsic factors that regulate CD8(+) T cell differentiation and use this information to generate and test distinct functional cell types in tumor models. The focus of our laboratory investigations is to identify the extrinsic factors such as antigen strength, co-stimulatory molecules, cytokines, and small molecule modifiers that regulate intrinsic programs for various effector and/or memory cell fate in antigen specific CD8 T cells. The use of this information to generate immunity in murine tumor models has facilitated development of new adoptive cell transfer (ACT) as well as immunization strategies for cancer treatment.

Harnessing regulatory T cells to suppress asthma: from potential to therapy

Regulatory T cells (Tregs) play an essential role in maintaining the homeostatic balance of immune responses. Asthma is an inflammatory condition of the airways that is driven by dysregulated immune responses toward normally innocuous antigens. Individuals with asthma have fewer and less functional Tregs, which may lead to uncontrolled effector cell responses and promote proasthmatic responses of T helper type 2, T helper 17, natural killer T, antigen-presenting, and B cells. Tregs have the capacity to either directly or indirectly suppress these responses. Hence, the induced expansion of functional Tregs in predisposed or individuals with asthma is a potential approach for the prevention and treatment of asthma. Infection by a number of micro-organisms has been associated with reduced prevalence of asthma, and many infectious agents have been shown to induce Tregs and reduce allergic airways disease in mouse models. The translation of the regulatory and therapeutic properties of infectious agents for use in asthma requires the identification of key modulatory components and the development and trial of effective immunoregulatory therapies. Further translational and clinical research is required for the induction of Tregs to be harnessed as a therapeutic strategy for asthma.

TNFR2-deficient memory CD8 T cells provide superior protection against tumor cell growth

TNF receptor-2 (TNFR2) plays a critical role in promoting the activation and survival of naive T cells during the primary response. Interestingly, anti-CD3 plus IL-2 activated TNFR2(-/-) CD8 T cells are highly resistant to activation-induced cell death (AICD), which correlates with high expression levels of prosurvival molecules such as Bcl-2, survivin, and CD127 (IL-7Ralpha). We determined whether the resistance of activated TNFR2(-/-) CD8 T cells to AICD contributes to more effective protection against tumor cell growth. We found that during a primary tumor challenge, despite initial inferiority in controlling tumor cell growth, TNFR2(-/-) mice were able to more effectively control tumor burden over time compared with wild-type (WT) mice. Furthermore, vaccination of TNFR2(-/-) mice with recombinant Listeria monocytogenes that express OVA confers better protection against the growth of OVA-expressing E.G7 tumor cells relative to similarly vaccinated WT mice. The enhanced protection against tumor cell growth was not due to more effective activation of OVA-specific memory CD8 T cells in vaccinated TNFR2(-/-) mice. In vitro studies indicate that optimally activated OVA-specific TNFR2(-/-) CD8 T cells proliferated to the same extent and possess similar cytotoxicity against E.G7 tumor cells as WT CD8 T cells. However, relative to WT cells, activated OVA-specific TNFR2(-/-) CD8 T cells were highly resistant to AICD. Thus, the enhanced protection against E.G7 in TNFR2(-/-) mice is likely due to the recruitment and activation of OVA-specific memory TNFR2(-/-) CD8 T cells and their prolonged survival at the tumor site.

Timing and tuning of CD27-CD70 interactions: the impact of signal strength in setting the balance between adaptive responses and immunopathology

SUMMARY

After binding its natural ligand cluster of differentiation 70 (CD70), CD27, a tumor necrosis factor receptor (TNFR)-associated factor-binding member of the TNFR family, regulates cellular activity in subsets of T, B, and natural killer cells as well as hematopoietic progenitor cells. In normal immune responses, CD27 signaling appears to be limited predominantly by the restricted expression of CD70, which is only transiently expressed by cells of the immune system upon activation. Studies performed in CD27-deficient and CD70-transgenic mice have defined a non-redundant role of this receptor-ligand pair in shaping adaptive T-cell responses. Moreover, adjuvant properties of CD70 have been exploited for the design of anti-cancer vaccines. However, continuous CD27-CD70 interactions may cause immune dysregulation and immunopathology in conditions of chronic immune activation such as during persistent virus infection and autoimmune disease. We conclude that optimal tuning of CD27-CD70 interaction is crucial for the regulation of the cellular immune response. We provide a detailed comparison of costimulation through CD27 with its closely related family members 4-1BB (CD137), CD30, herpes virus entry mediator, OX40 (CD134), and glucocorticoid-induced TNFR family-related gene, and we argue that these receptors do not have a unique function per se but that rather the timing, context, and intensity of these costimulatory signals determine the functional consequence of their activity.

In vivo anti-melanoma efficacy of allo-restricted CTLs specific for melanoma expanded by artificial antigen-presenting cells

Cytotoxic CD8(+) T cells are key effectors in the immunotherapy of malignant and viral diseases. However, autologous T cell responses to tumor antigens presented by self-MHC are usually weak and ineffective. Allo-restricted T cells represent a potent source of tumor-specific T cells for adoptive immunotherapy. This study reports in vivo anti-melanoma efficacy of the pTRP2-specific allo-restricted CTLs expanded from the BALB/c splenocytes by multiple stimulations with aAPCs made by coating H-2K(b)-Ig/pTRP2 dimeric complexes, anti-CD28 antibody, 4-1BBL molecules and CD83 molecules to cell-sized latex beads. The induced allo-restricted CTLs exhibited specific lysis against RMA-S cells pulsed with the peptide pTRP2 and H-2K(b+) melanoma cells expressing TRP2, while a murine Lewis lung carcinoma cell line 3LL could not be recognized by the CTLs. The peptide-specific activity was inhibited by anti-H-2K(b) monoclonal antibody Y3. Adoptive transfer of the allo-restricted CTLs specific for malignant melanoma expanded by the aAPCs can mediate effective anti-melanoma response in vivo. These results suggested that the specific allo-restricted CTLs expanded by aAPCs coated with an MHC-Ig/peptide complex, anti-CD28 antibody, 4-1BBL and CD83 could be a potential option of specific immunotherapy for patients with malignant melanoma.