Engineered fusokine GIFT4 licenses the ability of B cells to trigger a tumoricidal T-cell response

GM-CSF and IL-7 fusion cytokine engineered tumor vaccine generates long-term Th-17 memory cells and increases overall survival in aged syngeneic mouse models of glioblastoma

Age-related immune dysfunctions, such as decreased T-cell output, are closely related to pathologies like cancers and lack of vaccine efficacy among the elderly. Engineered fusokine, GIFT-7, a fusion of interleukin 7 (IL-7) and GM-CSF, can reverse aging-related lymphoid organ atrophy. We generated a GIFT-7 fusokine tumor vaccine and employed it in aged syngeneic mouse models of glioblastoma and found that peripheral vaccination with GIFT-7TVax resulted in thymic regeneration and generated durable long-term antitumor immunity specifically in aged mice. Global cytokine analysis showed increased pro-inflammatory cytokines including IL-1β in the vaccinated group that resulted in hyperactivation of dendritic cells. In addition, GIFT-7 vaccination resulted in increased T-cell trafficking to the brain and robust Th-17 long-term effector memory T-cell formation. TCR-seq analysis showed increased productive frequency among detected rearrangements within the vaccinated group. Overall, our data demonstrate that aging immune system can be therapeutically augmented to generate lasting antitumor immunity.

Emerging concepts regarding pro- and anti tumor properties of B cells in tumor immunity

Controversial views regarding the roles of B cells in tumor immunity have existed for several decades. However, more recent studies have focused on its positive properties in antitumor immunity. Many studies have demonstrated a close association of the higher density of intratumoral B cells with favorable outcomes in cancer patients. B cells can interact with T cells as well as follicular dendritic cells within tertiary lymphoid structures, where they undergo a series of biological events, including clonal expansion, somatic hypermutation, class switching, and tumor-specific antibody production, which may trigger antitumor humoral responses. After activation, B cells can function as effector cells via direct tumor-killing, antigen-presenting activity, and production of tumor-specific antibodies. At the other extreme, B cells can obtain inhibitory functions by relevant stimuli, converting to regulatory B cells, which serve as an immunosuppressive arm to tumor immunity. Here we summarize our current understanding of the bipolar properties of B cells within the tumor immune microenvironment and propose potential B cell-based immunotherapeutic strategies, which may help promote cancer immunotherapy.

The use of supercytokines, immunocytokines, engager cytokines, and other synthetic cytokines in immunotherapy

Cytokines exert powerful immunomodulatory effects that are critical to physiology and pathology in humans. The application of natural cytokines in clinical studies has not been clearly established, and there are often problems associated with toxicity or lack of efficacy. The key reasons can be attributed to the pleiotropy of cytokine receptors and undesired activation of off-target cells. With a deeper understanding of the structural principles and functional signals of cytokine-receptor interactions, artificial modification of cytokine signaling through protein engineering and synthetic immunology has become an increasingly feasible and powerful approach. Engineered cytokines are designed to selectively target cells. Herein, the theoretical and experimental evidence of cytokine engineering is reviewed, and the "supercytokines" resulting from structural enhancement and the "immunocytokines" generated by antibody fusion are described. Finally, the "engager cytokines" formed by the crosslinking of cytokines and bispecific immune engagers and other synthetic cytokines formed by nonnatural analogs are also discussed.

Inflammation and tumor progression: signaling pathways and targeted intervention

Cancer development and its response to therapy are regulated by inflammation, which either promotes or suppresses tumor progression, potentially displaying opposing effects on therapeutic outcomes. Chronic inflammation facilitates tumor progression and treatment resistance, whereas induction of acute inflammatory reactions often stimulates the maturation of dendritic cells (DCs) and antigen presentation, leading to anti-tumor immune responses. In addition, multiple signaling pathways, such as nuclear factor kappa B (NF-kB), Janus kinase/signal transducers and activators of transcription (JAK-STAT), toll-like receptor (TLR) pathways, cGAS/STING, and mitogen-activated protein kinase (MAPK); inflammatory factors, including cytokines (e.g., interleukin (IL), interferon (IFN), and tumor necrosis factor (TNF)-α), chemokines (e.g., C-C motif chemokine ligands (CCLs) and C-X-C motif chemokine ligands (CXCLs)), growth factors (e.g., vascular endothelial growth factor (VEGF), transforming growth factor (TGF)-β), and inflammasome; as well as inflammatory metabolites including prostaglandins, leukotrienes, thromboxane, and specialized proresolving mediators (SPM), have been identified as pivotal regulators of the initiation and resolution of inflammation. Nowadays, local irradiation, recombinant cytokines, neutralizing antibodies, small-molecule inhibitors, DC vaccines, oncolytic viruses, TLR agonists, and SPM have been developed to specifically modulate inflammation in cancer therapy, with some of these factors already undergoing clinical trials. Herein, we discuss the initiation and resolution of inflammation, the crosstalk between tumor development and inflammatory processes. We also highlight potential targets for harnessing inflammation in the treatment of cancer.

Regulatory B cells in cancer

Tumorigenesis proceeds through discrete steps where acquisition of genetic lesions and changes in the surrounding microenvironment combine to drive unrestricted neoplastic proliferation and metastasis. The ability of tumor-infiltrating immune cells to promote tumor growth via the provision of signals that enable tumor cell survival and proliferation as well as contribute to immune suppression is an active area of research. Recent efforts have provided us with mechanistic insights into how B cells can positively and negatively regulate immune responses. Negative regulation of immune responses in cancer can be mediated by regulatory B cells and is often a result of increased production of cytokines that can directly and indirectly affect anti-tumor immune function and cancer cell growth. Signals that lead to the expansion of regulatory B cells and the spectrum of their functional roles are not well understood and are the subject of active research by many groups. Here, we elaborate broadly on the history of regulatory B cells in cancer and summarize recent studies that have established genetic models for the study of regulatory B cell function and their potential for therapeutic intervention in the setting of solid cancers.

Understanding and Modulating Immunity With Cell Reprogramming

Cell reprogramming concepts have been classically developed in the fields of developmental and stem cell biology and are currently being explored for regenerative medicine, given its potential to generate desired cell types for replacement therapy. Cell fate can be experimentally reversed or modified by enforced expression of lineage specific transcription factors leading to pluripotency or attainment of another somatic cell type identity. The possibility to reprogram fibroblasts into induced dendritic cells (DC) competent for antigen presentation creates a paradigm shift for understanding and modulating the immune system with direct cell reprogramming. PU.1, IRF8, and BATF3 were identified as sufficient and necessary to impose DC fate in unrelated cell types, taking advantage of Clec9a, a C-type lectin receptor with restricted expression in conventional DC type 1. The identification of such minimal gene regulatory networks helps to elucidate the molecular mechanisms governing development and lineage heterogeneity along the hematopoietic hierarchy. Furthermore, the generation of patient-tailored reprogrammed immune cells provides new and exciting tools for the expanding field of cancer immunotherapy. Here, we summarize cell reprogramming concepts and experimental approaches, review current knowledge at the intersection of cell reprogramming with hematopoiesis, and propose how cell fate engineering can be merged to immunology, opening new opportunities to understand the immune system in health and disease.

The B-side of Cancer Immunity: The Underrated Tune

Tumor-infiltrating lymphocytes are known to be critical in controlling tumor progression. While the role of T lymphocytes has been extensively studied, the function of B cells in this context is still ill-defined. In this review, we propose to explore the role of B cells in tumor immunity. First of all we define their dual role in promoting and inhibiting cancer progression depending on their phenotype. To continue, we describe the influence of different tumor microenvironment factors such as hypoxia on B cells functions and differentiation. Finally, the role of B cells in response to therapy and as potential target is examined. In accordance with the importance of B cells in immuno-oncology, we conclude that more studies are required to throw light on the precise role of B cells in the tumor microenvironment in order to have a better understanding of their functions, and to design new strategies that efficiently target these cells by immunotherapy.

BCL2-BH4 antagonist BDA-366 suppresses human myeloma growth

Multiple myeloma (MM) is a heterogeneous plasma cell malignancy and remains incurable. B-cell lymphoma-2 (BCL2) protein correlates with the survival and the drug resistance of myeloma cells. BH3 mimetics have been developed to disrupt the binding between BCL2 and its pro-apoptotic BCL2 family partners for the treatment of MM, but with limited therapeutic efficacy. We recently identified a small molecule BDA-366 as a BCL2 BH4 domain antagonist, converting it from an anti-apoptotic into a pro-apoptotic molecule. In this study, we demonstrated that BDA-366 induces robust apoptosis in MM cell lines and primary MM cells by inducing BCL2 conformational change. Delivery of BDA-366 substantially suppressed the growth of human MM xenografts in NOD-scid/IL2Rγnull mice, without significant cytotoxic effects on normal hematopoietic cells or body weight. Thus, BDA-366 functions as a novel BH4-based BCL2 inhibitor and offers an entirely new tool for MM therapy.

GM-CSF and IL-4 Fusion Cytokine Induces B Cell-Dependent Hematopoietic Regeneration

Hematopoietic stem cells (HSCs) have the capacity to self-renew and differentiate into hematopoietic cells and have been utilized to replace diseased bone marrow for patients with cancers and blood disorders. Although remarkable progress has been made in developing new tools to manipulate HSCs for clinic use, there is still no effective method to expand HSCs in vivo for quick repopulation of hematopoietic cells following sublethal irradiation. We have recently described a novel synthetic cytokine that is derived from the fusion of granulocyte macrophage colony-stimulating factor (GM-CSF) and interleukin 4 (IL-4; named as GIFT4), and we have now discovered that GIFT4 fusokine promotes long-term hematopoietic regeneration in a B cell-dependent manner. We found that GIFT4 treatment triggered a robust expansion of endogenous bone marrow HSCs and multipotent progenitors in vivo. Delivery of GIFT4 protein together with B cells rescued lethally irradiated mice. Moreover, adoptive transfer of autologous or allogeneic GIFT4-treated B cells (GIFT4-B cells) enhanced long-term hematopoietic recovery in radiated mice and prevented the mice from irradiation-induced death. Our data suggest that GIFT4 as well as GIFT4-B cells could serve as means to augment HSC engraftment in the setting of bone marrow transplantation for patients with hematological malignancy.

GIFT4 fusokine converts leukemic B cells into immune helper cells

Background

Chronic lymphocytic leukemia (CLL) remains incurable with standard therapy, and is characterized by excessive expansion of monoclonal abnormal mature B cells and more regulatory immune properties of T cell compartment. Thus, developing novel strategies to enhance immune function merits further investigation as a possible therapy for CLL.

Methods

We generated a fusion cytokine (fusokine) arising from the combination of human GM-CSF and IL-4 (named GIFT4). Primary CLL cells were treated with GIFT4 or GM-CSG and IL-4 in vitro. GIFT4-triggered STAT5 signaling in CLL cells was examined by Western blot. The phenotype and secretome of GIFT4-treated CLL cells (GIFT4-CLL cells), and the immune stimulatory function of GIFT4-CLL cells on autologous T cells were analyzed by flow cytometry and luminex assay.

Results

GIFT4-CLL up-regulated the expression of co-stimulatory molecules CD40, CD80 and CD86 and adhesion molecule CD54. GIFT4-CLL cells secreted IL-1β, IL-6, ICAM-1 and substantial IL-2 relative to unstimulated CLL cells. GIFT4 treatment led to JAK1, JAK2 and JAK3-mediated hyper-phosphorylation of STAT5 in primary CLL cells, which is essential for GIFT4-triggered conversion of CLL cells. GIFT4-CLL cells directly propelled the expansion of autologous IFN-γ-producing CD314⁺ cytotoxic T cells in vitro, and that these could lyse autologous CLL cells. Furthermore, administration of GIFT4 protein promoted the expansion of human T cells in NOD-scid IL2Rγ^null immune deficient mice adoptively pre-transferred with peripheral blood mononuclear cells from subjects with CLL.

Conclusion

GIFT4 has potent capability to converts primary CLL cells into APC-like immune helper cells that initiate a T cell driven anti-CLL immune response.

Current Advances in Virus-Like Particles as a Vaccination Approach against HIV Infection

HIV-1 virus-like particles (VLPs) are promising vaccine candidates against HIV-1 infection. They are capable of preserving the native conformation of HIV-1 antigens and priming CD4+ and CD8+ T cell responses efficiently via cross presentation by both major histocompatibility complex (MHC) class I and II molecules. Progress has been achieved in the preclinical research of HIV-1 VLPs as prophylactic vaccines that induce broadly neutralizing antibodies and potent T cell responses. Moreover, the progress in HIV-1 dendritic cells (DC)-based immunotherapy provides us with a new vision for HIV-1 vaccine development. In this review, we describe updates from the past 5 years on the development of HIV-1 VLPs as a vaccine candidate and on the combined use of HIV particles with HIV-1 DC-based immunotherapy as efficient prophylactic and therapeutic vaccination strategies.

Clinically relevant genes and regulatory pathways associated with NRASQ61 mutations in melanoma through an integrative genomics approach

Therapies such as BRAF inhibitors have become standard treatment for melanoma patients whose tumors harbor activating BRAFV600 mutations. However, analogous therapies for inhibiting NRAS mutant signaling have not yet been well established. In this study, we performed an integrative analysis of DNA methylation, gene expression, and microRNA expression data to identify potential regulatory pathways associated with the most common driver mutations in NRAS (Q61K/L/R) through comparison of NRASQ61-mutated melanomas with pan-negative melanomas. Surprisingly, we found dominant hypomethylation (98.03%) in NRASQ61-mutated melanomas. We identified 1,150 and 49 differentially expressed genes and microRNAs, respectively. Integrated functional analyses of alterations in all three data types revealed important signaling pathways associated with NRASQ61 mutations, such as the MAPK pathway, as well as other novel cellular processes, such as axon guidance. Further analysis of the relationship between DNA methylation and gene expression changes revealed 9 hypermethylated and down-regulated genes and 112 hypomethylated and up-regulated genes in NRASQ61 melanomas. Finally, we identified 52 downstream regulatory cascades of three hypomethylated and up-regulated genes (PDGFD, ZEB1, and THRB). Collectively, our observation of predominant gene hypomethylation in NRASQ61 melanomas and the identification of NRASQ61-linked pathways will be useful for the development of targeted therapies against melanomas harboring NRASQ61 mutations.

Incorporation of a GPI-anchored engineered cytokine as a molecular adjuvant enhances the immunogenicity of HIV VLPs

HIV vaccines should elicit immune responses at both the mucosal portals of entry to block transmission and systemic compartments to clear disseminated viruses. Co-delivery of mucosal adjuvants has been shown to be essential to induce effective mucosal immunity by non-replicating vaccines. A novel cytokine, GIFT4, engineered by fusing GM-CSF and interleukin-4, was previously found to simulate B cell proliferation and effector function. Herein a membrane-anchored form of GIFT4 was constructed by fusing a glycolipid (GPI)-anchoring sequence and incorporated into Env-enriched HIV virus-like particles (VLPs) as a molecular adjuvant. Guinea pigs were immunized with the resulting HIV VLPs through an intramuscular priming-intranasal boosting immunization route. The GIFT4-containing VLPs induced higher levels of systemic antibody responses with significantly increased binding avidity and improved neutralizing breadth and potency to a panel of selected strains, as well as higher levels of IgG and IgA at several mucosal sites. Thus, the novel GPI-GIFT4-containging VLPs have the potential to be developed into a prophylactic HIV vaccine. Incorporation of GPI-anchored GIFT4 into VLPs as a molecular adjuvant represents a novel approach to increase their immunogenicity.

Microfluidic squeezing for intracellular antigen loading in polyclonal B-cells as cellular vaccines

B-cells are promising candidate autologous antigen-presenting cells (APCs) to prime antigen-specific T-cells both in vitro and in vivo. However to date, a significant barrier to utilizing B-cells as APCs is their low capacity for non-specific antigen uptake compared to “professional” APCs such as dendritic cells. Here we utilize a microfluidic device that employs many parallel channels to pass single cells through narrow constrictions in high throughput. This microscale “cell squeezing” process creates transient pores in the plasma membrane, enabling intracellular delivery of whole proteins from the surrounding medium into B-cells via mechano-poration. We demonstrate that both resting and activated B-cells process and present antigens delivered via mechano-poration exclusively to antigen-specific CD8⁺T-cells, and not CD4⁺T-cells. Squeezed B-cells primed and expanded large numbers of effector CD8⁺T-cells in vitro that produced effector cytokines critical to cytolytic function, including granzyme B and interferon-γ. Finally, antigen-loaded B-cells were also able to prime antigen-specific CD8⁺T-cells in vivo when adoptively transferred into mice. Altogether, these data demonstrate crucial proof-of-concept for mechano-poration as an enabling technology for B-cell antigen loading, priming of antigen-specific CD8⁺T-cells, and decoupling of antigen uptake from B-cell activation.

A GMCSF and IL7 fusion cytokine leads to functional thymic-dependent T-cell regeneration in age-associated immune deficiency

The competence of cellular immunity depends on a diverse T-cell receptor (TCR) repertoire arising from thymic output. Normal thymopoiesis arises from marrow-derived CD3(-)CD4(-)CD8(-) triple-negative T-cell progenitors (TN), which develop into mature single-positive (SP) CD4 or CD8 T cells after expressing both CD4 and CD8 (double-positive, DP) transiently, leading to de novo T-cell production. Interleukin-7 (IL7) is a singularly important common γ-chain IL involved in normal thymic development. Our previous work has demonstrated that γc cytokines fused with granulocyte-macrophage colony stimulating factor (GMCSF) at the N-terminus acquire unheralded biological properties. Therefore, to enhance thymopoiesis, we developed a novel biopharmaceutical based on the fusion of GMCSF and IL7, hereafter GIFT7. Systemic administration of GIFT7 leads to cortical thymic hyperplasia including the specific expansion of CD44(int)CD25(-) double-negative 1 (DN1) thymic progenitors. During murine cytomegalovirus (mCMV) infection of aged animals, GIFT7-mediated neo-thymopoiesis led to increased absolute numbers of viral-specific CD8(+) T cell. Our work demonstrated that thymic precursors can be therapeutically repopulated and its reconstitution leads to meaningful central and peripheral T-cell neogenesis, correcting immune dysfunction arising from age-associated thymic atrophy.

Concise review: engineering the fusion of cytokines for the modulation of immune cellular responses in cancer and autoimmune disorders

As our understanding of the basic precepts of immunobiology continue to advance at a rapid pace, translating such discoveries into meaningful therapies for patients has proved challenging. This is especially apparent in the use of cytokine-based immunotherapies for cancer. Unanticipated and serious side effects, as well as low objective response rates seen in clinical trials, have dealt setbacks to the field. Granulocyte-macrophage colony-stimulating factor (GM-CSF) and common γ-chain (γ-c) interleukins are cytokines that have been used as stand-alone immunotherapies with moderate success. Our group has found that the fusion of GM-CSF to members of γ-c interleukins results in the generation of novel proteins with unique signaling properties and unheralded biological effects. These fusion proteins, termed GIFT (GM-CSF interleukin fusion transgenes) fusokines, are the result of combining GM-CSF and a γ-c interleukin into a single, bifunctional polypeptide. In our experience, GIFT fusokines often confer immune cells with a gain of function that cannot be explained by the mere sum of their constituent moieties. They act as bispecific ligands, coupling activated GM-CSF and interleukin receptors together to drive unique downstream signaling events. The synergy that arises from these fusions has shown great promise in its ability to modulate the immune response and overcome maladaptive biological processes that underlie diseases such as cancer and autoimmune conditions. In this review, we discuss the ways in which the GIFT fusokines are able to alter the immune response, particularly in disease states, with a special emphasis on how these novel molecules may be translated into effective therapies in the clinical setting.

B cells for cancer immunotherapy

We have engineered a novel fusion cytokine named GIFT4 derived from GM-CSF and IL-4, and displaying robust gain-of-function immunostimulatory effects on B cells. GIFT4-programmed B cells have a unique identity and potent capacity to elicit a tumoricidal - cell response, thus comprising a novel B cell-based cancer immunotherapeutic approach.