Granulocyte-macrophage colony-stimulating factor (GM-CSF) counteracts the inhibiting effect of monocytes on natural killer (NK) cells

Maintenance regimen of GM-CSF with rituximab and lenalidomide improves survival in high-risk B-cell lymphoma by modulating natural killer cells

BACKGROUND

The treatment of high-risk B-cell lymphoma (BCL) remains a challenge, especially in the elderly.

METHODS

A total of 83 patients (median age 65 years), who have achieved a complete response after induction therapy, were divided into two groups: R²  + GM-CSF regimen (lenalidomide, rituximab, granulocyte-macrophage colony-stimulating factor [GM-CSF]) as maintenance therapy (n = 39) and observation (n = 44). The efficacy of the R²  + GM-CSF regimen as maintenance in patient with high-risk BCL was analyzed and compared with observation.

RESULTS

The number of natural killer cells in patients increased after R²  + GM-CSF regimen administration (0.131 × 10⁹ /L vs. 0.061 × 10⁹ /L, p = 0.0244). Patients receiving the R²  + GM-CSF regimen as maintenance therapy had longer remission (duration of response: 18.9 vs. 11.3 months, p = 0.001), and longer progression-free survival (not reached (NR) vs. 31.7 months, p = 0.037), and overall survival (OS) (NR vs. NR, p = 0.015). The R²  + GM-CSF regimen was safe and well tolerated. High international prognostic index score (p = 0.012), and high tumor burden (p = 0.005) appeared to be independent prognostic factors for worse PFS.

CONCLUSIONS

The maintenance therapy of R²  + GM-CSF regimen may improve survival in high-risk BCL patients, which might be modulated by amplification of natural killer cells. The efficacy of the R²  + GM-CSF maintenance regimen has to be further validated in prospective random clinical trials.

AAV-mediated gene transfer of a checkpoint inhibitor in combination with HER2-targeted CAR-NK cells as experimental therapy for glioblastoma

Glioblastoma (GB) is the most common primary brain tumor, which is characterized by low immunogenicity of tumor cells and prevalent immunosuppression in the tumor microenvironment (TME). Targeted local combination immunotherapy is a promising strategy to overcome these obstacles. Here, we evaluated tumor-cell specific delivery of an anti-PD-1 immunoadhesin (aPD-1) via a targeted adeno-associated viral vector (AAV) as well as HER2-specific NK-92/5.28.z (anti-HER2.CAR/NK-92) cells as components for a combination immunotherapy. In co-culture experiments, target-activated anti-HER2.CAR/NK-92 cells modified surrounding tumor cells and bystander immune cells by triggering the release of inflammatory cytokines and upregulation of PD-L1. Tumor cell-specific delivery of aPD-1 was achieved by displaying a HER2-specific designed ankyrin repeat protein (DARPin) on the AAV surface. HER2-AAV mediated gene transfer into GB cells correlated with HER2 expression levels, without inducing anti-viral responses in transduced cells. Furthermore, AAV-transduction did not interfere with anti-HER2.CAR/NK-92 cell-mediated tumor cell lysis. After selective transduction of HER2⁺ cells, aPD-1 expression was detected at the mRNA and protein level. The aPD-1 immunoadhesin was secreted in a time-dependent manner, bound its target on PD-1-expressing cells and was able to re-activate T cells by efficiently disrupting the PD-1/PD-L1 axis. Moreover, high intratumoral and low systemic aPD-1 concentrations were achieved following local injection of HER2-AAV into orthotopic tumor grafts in vivo. aPD-1 was selectively produced in tumor tissue and could be detected up to 10 days after a single HER2-AAV injection. In subcutaneous GL261-HER2 and Tu2449-HER2 immunocompetent mouse models, administration of the combination therapy significantly prolonged survival, including complete tumor control in several animals in the GL261-HER2 model. In summary, local therapy with aPD-1 encoding HER2-AAVs in combination with anti-HER2.CAR/NK-92 cells may be a promising novel strategy for GB immunotherapy with the potential to enhance efficacy and reduce systemic side effects of immune-checkpoint inhibitors.

The Role of Natural Killer Cells in Autoimmune Diseases

Natural killer (NK) cells, the large granular lymphocytes differentiated from the common lymphoid progenitors, were discovered in early 1970’s. They are members of innate immunity and were initially defined by their strong cytotoxicity against virus-infected cells and by their important effector functions in anti-tumoral immune responses. Nowadays, NK cells are classified among the recently discovered innate lymphoid cell subsets and have capacity to influence both innate and adaptive immune responses. Therefore, they can be considered as innate immune cells that stands between the innate and adaptive arms of immunity. NK cells don’t express T or B cell receptors and are recognized by absence of CD3. There are two major subgroups of NK cells according to their differential expression of CD16 and CD56. While CD16⁺CD56^dim subset is best-known by their cytotoxic functions, CD16^-CD56^bright NK cell subset produces a bunch of cytokines comparable to CD4⁺ T helper cell subsets. Another subset of NK cells with production of interleukin (IL)-10 was named as NK regulatory cells, which has suppressive properties and could take part in immune-regulatory responses. Activation of NK cells is determined by a delicate balance of cell-surface receptors that have either activating or inhibitory properties. On the other hand, a variety of cytokines including IL-2, IL-12, IL-15, and IL-18 influence NK cell activity. NK-derived cytokines and their cytotoxic functions through induction of apoptosis take part in regulation of the immune responses and could contribute to the pathogenesis of many immune mediated diseases including ankylosing spondylitis, Behçet’s disease, multiple sclerosis, rheumatoid arthritis, psoriasis, systemic lupus erythematosus and type-1 diabetes. Dysregulation of NK cells in autoimmune disorders may occur through multiple mechanisms. Thanks to the rapid developments in biotechnology, progressive research in immunology enables better characterization of cells and their delicate roles in the complex network of immunity. As NK cells stand in between innate and adaptive arms of immunity and “bridge” them, their contribution in inflammation and immune regulation deserves intense investigations. Better understanding of NK-cell biology and their contribution in both exacerbation and regulation of inflammatory disorders is a requisite for possible utilization of these multi-faceted cells in novel therapeutic interventions.

Cytokines in oncolytic virotherapy

Tumors represent a hostile environment for the effector cells of cancer immunosurveillance. Immunosuppressive receptors and soluble or membrane-bound ligands are abundantly exposed and released by malignant entities and their stromal accomplices. As a consequence, executioners of antitumor immunity inefficiently navigate across cancer tissues and fail to eliminate malignant targets. By inducing immunogenic cancer cell death, oncolytic viruses profoundly reshape the tumor microenvironment. They trigger the local spread of danger signals and tumor-associated (as well as viral) antigens, thus attracting antigen-presenting cells, promoting the activation and expansion of lymphocytic populations, facilitating their infiltration in the tumor bed, and reinvigorating cytotoxic immune activity. The present review recapitulates key chemokines, growth factors and other cytokines that orchestrate this ballet of antitumoral leukocytes upon oncolytic virotherapy.

Transcriptional Regulation of Natural Killer Cell Development and Functions

Natural killer (NK) cells are the major lymphocyte subset of the innate immune system. Their ability to mediate anti-tumor cytotoxicity and produce cytokines is well-established. However, the molecular mechanisms associated with the development of human or murine NK cells are not fully understood. Knowledge is being gained about the environmental cues, the receptors that sense the cues, signaling pathways, and the transcriptional programs responsible for the development of NK cells. Specifically, a complex network of transcription factors (TFs) following microenvironmental stimuli coordinate the development and maturation of NK cells. Multiple TFs are involved in the development of NK cells in a stage-specific manner. In this review, we summarize the recent advances in the understandings of TFs involved in the regulation of NK cell development, maturation, and effector function, in the aspects of their mechanisms, potential targets, and functions.

Natural Killer Cells: Development, Maturation, and Clinical Utilization

Natural killer (NK) cells are the predominant innate lymphocyte subsets that mediate anti-tumor and anti-viral responses, and therefore possess promising clinical utilization. NK cells do not express polymorphic clonotypic receptors and utilize inhibitory receptors (killer immunoglobulin-like receptor and Ly49) to develop, mature, and recognize “self” from “non-self.” The essential roles of common gamma cytokines such as interleukin (IL)-2, IL-7, and IL-15 in the commitment and development of NK cells are well established. However, the critical functions of pro-inflammatory cytokines IL-12, IL-18, IL-27, and IL-35 in the transcriptional-priming of NK cells are only starting to emerge. Recent studies have highlighted multiple shared characteristics between NK cells the adaptive immune lymphocytes. NK cells utilize unique signaling pathways that offer exclusive ways to genetically manipulate to improve their effector functions. Here, we summarize the recent advances made in the understanding of how NK cells develop, mature, and their potential translational use in the clinic.

Immunomodulatory Properties of Coriolus versicolor: The Role of Polysaccharopeptide

Traditional uses of herbal medicine have depended mostly on anecdotal evidence for much of history. The increasing application of scientific rigor to the study some of these traditional therapies in recent years has revealed potent bioactivity, notably demonstrated by the 2015 Nobel Prize for the discovery of an antimalarial compound from traditional Chinese herbs. Given the recent successes of immunotherapy and checkpoint blockade, there is a renewed interest in identifying new drugs with immunomodulatory effects. As an estimated 45-60% of cancer patients worldwide are reported to use complementary alternative medicine alongside traditional therapy, this review will highlight the literature on the immunomodulatory effects of one of these compounds. We report on the induction of a largely pro-inflammatory cytokine profile by the polysaccharopeptide (PSP) isolated from the Coriolus versicolor (Yun zhi) mushroom, as well as its effects on various immune subsets, and the clinical data that have led to its widespread adoption as an adjunct cancer therapeutic in many Eastern cultures. Particular focus is given to the potential mechanisms underlying the bioactivity of PSP and reports of its ability to promote antitumor immunity by helping overcome tolerogenic tumor microenvironments.

Elevation of MMP-9 and IDO induced by pancreatic cancer cells mediates natural killer cell dysfunction

Background

Natural killer (NK) cells play a key role in non-specific immune response in different cancers, including pancreatic cancer. However the anti-tumor effect of NK cells decreases during pancreatic cancer progression. The regulatory pathways by which NK cells facilitate tumor immune escape are unclear, therefore our purpose was to investigate the roles of the contributory factors.

Methods

NK cells isolated from fresh healthy peripheral blood were co-cultured with normal human pancreatic ductal cells hTERT-HPNE and human pancreatic cancer cell lines SW1990 and BxPc-3 in vitro. Then NK cell function was determined by Flow cytometric analysis of surface receptors and cytotoxic granules in NK cells, NK cell apoptosis and cytotoxicity, and Enzyme-linked immunosorbent assay of cytokines. Expression level of MMP-9, IDO and COX-2 in hTERT-HPNE and SW1990 cells were detected by quantitative RT-PCR. Statistical differences between data groups were determined by independent t-tests using SPSS 19.0 software.

Results

Our results showed that NK cell function was significantly downregulated following exposure to pancreatic cancer cells compared to normal pancreatic cells, as demonstrated by lower expressions of activating surface receptors (NKG2D, DNAM-1, NKp30 and NKp46) and cytotoxic granules (Perforin and Granzyme B); decreased secretion of cytokines (TNF-α and IFN-γ); and reduced cytotoxicity against myelogenous leukemia K562 cells. Further investigations revealed that MMP-9 and IDO may be implicated in SW1990 cell-induced NK cell dysfunction by facilitating tumor immune evasion. Blockade by TIMP-1 and/or 1-MT could partially restore NK function.

Conclusions

Taken together, elevation of MMP-9 and IDO induced by pancreatic cancer cells mediates NK cell dysfunction. Our findings could contribute to the development of NK cell-based immunotherapy in patients with pancreatic cancer.

Neutralization of measles virus infectivity and antibody-dependent cell-mediated cytotoxicity activity against an Epstein-Barr virus-infected cell line by intravenous immunoglobulin G [corrected]

Patients with antibody deficiency disorders are highly susceptible to microbial infections. Intravenous (i.v.) immunoglobulin concentrates were originally developed as replacement therapy for such patients. The present study assesses the measles virus neutralizing antibody titers and the antibody-dependent cell-mediated cytotoxicity (ADCC) capacities against Epstein-Barr virus (EBV)-infected cells of immunoglobulin G (IgG) preparations produced for i.v. use (i.v. IgG). The level of neutralizing antibodies against measles virus was determined by a syncytium neutralization test with Vero cells as targets. The measles virus neutralizing antibody titers of the i.v. IgG preparations were >3 x 10(2) and were an average of 1.0 log higher than the titers in pooled plasma from healthy subjects. The two IgG preparations tested showed similar ADCC activities against EBV-infected Raji cells, being active at concentrations of 3 mg/ml or higher. i.v. IgG bound to Raji cells but not to the EBV-negative Ramos cells, as evaluated by flow cytometry. Our in vitro findings may provide further support for the use of i.v. IgG for the prevention and treatment of infections caused by specific viral pathogens.

Enhancement of natural killer cell-mediated cytotoxicity by coexpression of GM-CSF/B70 in hepatoma

On investigating the role of granulocyte-macrophage colony-stimulating factor (GM-CSF) and costimulatory molecule, B70, in antitumor immunity, we have found important effects of GM-CSF/B70 coexpression in the interaction with natural killer (NK) cells. We used the pLSN vector system to contain the neomycin-resistant gene and LTR promoter. The pLSNGM-CSF, pLSNB70 and pLSNB70/GM-CSF, pLSN vectors each containing GM-CSF, B70, and B70/GM-CSF cDNA, respectively, were constructed. They were transfected into human hepatocellular carcinoma cell (SK-HEP1), and stable cells (SK-pLSN, SK-GM, SK-B70 and SK-BG) were selected after neomycin treatment. According to enzyme-linked immunosorbent analysis and FACS, we showed that expression of GM-CSF was increased up to 23-fold in SK-GM and SK-BG cells, and also expression of B70 was induced at least 76-97% in SK-B70 and SK-BG cells. Expression of B70 was remarkably increased by autocrine effect of GM-CSF in SK-BG cells. Primary cytolytic ability of GM-CSF and B70 significantly increased almost 4-fold (effector/target ratio, 100:1) in SK-BG cells. In in vivo studies, SK-BG cells showed much less subcutaneous tumor formation in nude mice accompanying increased NK cell proliferation and cytotoxicity. Therefore, these results suggest that combining expression of GM-CSF and B70 may enhance NK-mediated cytotoxicity, and then induce the antitumor immunity in hepatoma transplanted into nude mice.

A highly sensitive whole blood natural killer cell assay

The assessment of natural killer cell activity at baseline and the monitoring of this activity during treatment is important in many diseases especially in patients with cancer and AIDS. An optimised and standardised whole blood chromium release assay is described using K562 cells, the standard target erythroleukaemic cell line. The tumour cell lysis observed using whole blood is comparable to that obtained with the standard 4 h lysis assay using peripheral blood mononuclear cells as effector cells. Results with the whole blood assay are reproducible when the incubation with K562 cells is performed over a period of 18 h. The assay necessitates only 0.6 ml of blood collected in 10 IU/ml of sodium heparin as the anticoagulant. In this report, depletion experiments, also standardised using whole blood, show that the effector cells in the whole blood assay are contained within the CD56 + cell population. This assay will be of interest where the immunological status of patients with different diseases need to be frequently monitored.