The biology of natural killer cells in cancer, infection, and pregnancy

Association of NK cell subsets and cytotoxicity with FCGR3A gene polymorphism in functional NK cell deficiency

OBJECTIVE

The purpose of this study was to assess the association between clinical, laboratory, and functional analyses and polymorphism in the FCGR3A gene in individuals with functional NK cell deficiency.

METHODS

A total of 15 functional NK cell deficiency patients and 10 age-matched healthy controls underwent NK cell subgroup, cytotoxicity, and FCGR3A whole-exome analysis with next-generation sequencing.

RESULTS

Three different NK cell subsets (CD56brightCD16neg, CD56brightCD16int, and CD56dimCD16hi) were identified. No statistically significant difference was found in the ratio of CD56brightCD16neg cells between patients and controls. CD56brightCD16int and CD56dimCD16hi ratios were found to be significantly lower in patients. As a result of NK cell cytotoxicity analysis, a proportional decrease of K562 amount between patients and controls was found to be statistically significant (p<0.001). In the FCGR3A whole-exome analysis, all patients were found to be homozygous mutant for the c.526G > T (p.V176F) in exon 4, while three patients were homozygous wild type and 12 patients were heterozygous for the c.197T>A (p.L66H) in exon 3.

CONCLUSION

In this study, a group of pediatric patients with suspected functional NK cell deficiency were evaluated and the findings indicated that NK subsets, cytotoxicity results, and FCGR3A gene polymorphism were found to be correlated with the clinical features. We conclude that this kind of study might contribute to follow-up the patients in time.

Potentiation of natural killer cells to overcome cancer resistance to NK cell-based therapy and to enhance antibody-based immunotherapy

Natural killer (NK) cells are cellular components of the innate immune system that can recognize and suppress the proliferation of cancer cells. NK cells can eliminate cancer cells through direct lysis, by secreting perforin and granzymes, or through antibody-dependent cell-mediated cytotoxicity (ADCC). ADCC involves the binding of the Fc gamma receptor IIIa (CD16), present on NK cells, to the constant region of an antibody already bound to cancer cells. Cancer cells use several mechanisms to evade antitumor activity of NK cells, including the accumulation of inhibitory cytokines, recruitment and expansion of immune suppressor cells such as myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs), modulation of ligands for NK cells receptors. Several strategies have been developed to enhance the antitumor activity of NK cells with the goal of overcoming cancer cells resistance to NK cells. The three main strategies to engineer and boost NK cells cytotoxicity include boosting NK cells with modulatory cytokines, adoptive NK cell therapy, and the employment of engineered NK cells to enhance antibody-based immunotherapy. Although the first two strategies improved the efficacy of NK cell-based therapy, there are still some limitations, including immune-related adverse events, induction of immune-suppressive cells and further cancer resistance to NK cell killing. One strategy to overcome these issues is the combination of monoclonal antibodies (mAbs) that mediate ADCC and engineered NK cells with potentiated anti-cancer activity. The advantage of using mAbs with ADCC activity is that they can activate NK cells, but also favor the accumulation of immune effector cells to the tumor microenvironment (TME). Several clinical trials reported that combining engineered NK cells with mAbs with ADCC activity can result in a superior clinical response compared to mAbs alone. Next generation of clinical trials, employing engineered NK cells with mAbs with higher affinity for CD16 expressed on NK cells, will provide more effective and higher-quality treatments to cancer patients.

Enhancement of NK Cell Antitumor Effector Functions Using a Bispecific Single Domain Antibody Targeting CD16 and the Epidermal Growth Factor Receptor

Simple Summary

Strategies to enhance the preferential accumulation and activation of Natural Killer (NK) cells in the tumor microenvironment can be expected to increase the efficacy of NK cell-based cancer immunotherapy. In this study, we report that a bispecific single domain antibody (VHH) that targets CD16 (FcRγIII) on NK cells and the epidermal growth factor receptor (EGFR) on tumor cells can be used to target and enhance cytolysis of cancer cells. The bispecific VHH enhanced NK cell activation and cytotoxicity in an EGFR- and CD16-dependent and KRAS-independent manner. Moreover, the bispecific VHH induced stronger activity of cancer patient-derived NK cells and resulted in tumor control in a co-culture of metastatic colorectal cancer cells and either autologous peripheral blood mononuclear cells or allogeneic CD16⁺ NK cells. We believe that this novel approach could represent a valid therapeutic strategy either alone or in combination with other NK cell-based therapies.

Abstract

The ability to kill tumor cells while maintaining an acceptable safety profile makes Natural Killer (NK) cells promising assets for cancer therapy. Strategies to enhance the preferential accumulation and activation of NK cells in the tumor microenvironment can be expected to increase the efficacy of NK cell-based therapies. In this study, we show binding of a novel bispecific single domain antibody (VHH) to both CD16 (FcRγIII) on NK cells and the epidermal growth factor receptor (EGFR) on tumor cells of epithelial origin. The bispecific VHH triggered CD16- and EGFR-dependent activation of NK cells and subsequent lysis of tumor cells, regardless of the KRAS mutational status of the tumor. Enhancement of NK cell activation by the bispecific VHH was also observed when NK cells of colorectal cancer (CRC) patients were co-cultured with EGFR expressing tumor cells. Finally, higher levels of cytotoxicity were found against patient-derived metastatic CRC cells in the presence of the bispecific VHH and autologous peripheral blood mononuclear cells or allogeneic CD16 expressing NK cells. The anticancer activity of CD16-EGFR bispecific VHHs reported here merits further exploration to assess its potential therapeutic activity either alone or in combination with adoptive NK cell-based therapeutic approaches.

Natural Killer Cell Interactions With Myeloid Derived Suppressor Cells in the Tumor Microenvironment and Implications for Cancer Immunotherapy

The tumor microenvironment (TME) is a complex and heterogeneous environment composed of cancer cells, tumor stroma, a mixture of tissue-resident and infiltrating immune cells, secreted factors, and extracellular matrix proteins. Natural killer (NK) cells play a vital role in fighting tumors, but chronic stimulation and immunosuppression in the TME lead to NK cell exhaustion and limited antitumor functions. Myeloid-derived suppressor cells (MDSCs) are a heterogeneous group of myeloid cells with potent immunosuppressive activity that gradually accumulate in tumor tissues. MDSCs interact with innate and adaptive immune cells and play a crucial role in negatively regulating the immune response to tumors. This review discusses MDSC-mediated NK cell regulation within the TME, focusing on critical cellular and molecular interactions. We review current strategies that target MDSC-mediated immunosuppression to enhance NK cell cytotoxic antitumor activity. We also speculate on how NK cell-based antitumor immunotherapy could be improved.

Natural Killer Cell Defects in Breast Cancer: A Key Pathway for Tumor Evasion

As the most important innate immune component cancers invader, natural killer (NK) cells have a magnificent role in antitumor immunity without any prior sensitization. Different subsets of NK cells have distinct responses during tumor cell exposure, according to their phenotypes and environments. Their function is induced mainly by the activity of both inhibitory and activating receptors against cancerous cells. Since the immunosuppression in the tumor microenvironment of breast cancer patients has directly deteriorated the phenotype and disturbed the function of NK cells, recruiting compensatory mechanisms indicate promising outcomes for immunotherapeutic approaches. These evidences accentuate the importance of NK cell distinct features in protection against breast tumors. In this review, we discuss the several mechanisms involved in NK cells suppression which consequently promote tumor progression and disease recurrence in patients with breast cancer.

Memory-like natural killer cells for cancer immunotherapy

Natural killer (NK) cells are cytotoxic innate lymphoid cells that protect the host from infection and mediate anti-tumor responses. Classically considered part of the innate immune system, NK cells were previously thought to not possess the specificity or enhanced recall responses associated with adaptive T and B lymphocytes. However, a large body of work has transformed these long-held divisions between innate and adaptive immunity; NK cell memory and memory-like responses are clearly established after hapten exposure, viral infection, and combined cytokine activation. These advances come with opportunities to translate innate NK cell recall responses into the clinic as cancer immunotherapy. Here, we review our current understanding of the heterogeneity of memory and memory-like NK cell responses, with distinct formation, molecular biology, and memory type functions. We elaborate on cytokine-induced memory-like NK cells and highlight their application as adoptive immunotherapy for cancer, and as a platform for engineering optimal NK cell anti-tumor responses.

Inter-individual differences in immune profiles of outbred rats screened for an emotional reactivity phenotype

Inter-individual differences in emotional reactivity predict susceptibility versus resilience to mood pathology. Using experimentally-naïve outbred rats that vary in locomotor reactivity to the mild stress of an inescapable novel environment [i.e., top and bottom 1/3rd of the population identified as high responders (HR) and low responders (LR) respectively], we determined baseline variations in immune functions. Innate and adaptive immune responses vary basally in LRHR rats, namely a shift towards TH1 in LRs and TH2 in HRs was observed. These inter-individual variations in immune profiles in LRHRs could have significant implications in mood alterations and immune reactivity to microbes and cancer.

NADPH oxidase 5α promotes the formation of CD271 tumor-initiating cells in oral cancer

Oral tongue squamous cell carcinoma (OTSCC) has a distinctive cell sub-population known as tumor-initiating cells (TICs). CD271 is a functional TIC receptor in head and neck cancers. The molecular mechanisms governing CD271 up-regulation remains unclear. Oxidative stress is a contributing factor in TIC development. Here, we explored the potential role of NADPH oxidase 5 (NOX5) and its regulatory mechanism on the development of CD271-expressing OTSCC. Our results showed that the splice variant NOX5α is the most prevalent form expressed in head and neck cancers. NOX5α enhanced OTSCC proliferation, migration, and invasion. Overexpression of NOX5α increased the size of OTSCC xenograft significantly in vivo. The tumor-promoting functions of NOX5α were mediated through the reactive oxygen species (ROS)-generating property. NOX5α activated ERK singling and increased CD271 expression at the transcription level. Also, NOX5α reduces the sensitivity of OTSCC to cisplatin and natural killer cells. The findings indicate that NOX5α plays an important part in the development of TIC in OTSCC.

Safety and immune cell kinetics after donor natural killer cell infusion following haploidentical stem cell transplantation in children with recurrent neuroblastoma

INTRODUCTION

Under the hypothesis that early natural killer cell infusion (NKI) following haploidentical stem cell transplantation (haplo-SCT) will reduce relapse in the early post-transplant period, we conducted a pilot study to evaluate the safety and feasibility of NKI following haplo-SCT in children with recurrent neuroblastoma who failed previous tandem high-dose chemotherapy and autologous SCT.

METHODS

We used the high-dose 131I-metaiodobenzylguanidine and cyclophosphamide/fludarabine/anti-thymocyte globulin regimen for conditioning and infused 3 × 107/kg of ex-vivo expanded NK cells derived from a haploidentical parent donor on days 2, 9, and 16 post-transplant. Interleukin-2 was administered (1 × 106 IU/m2/day) subcutaneously to activate infused donor NK cells on days 2, 4, 6, 9, 11, 13, 16, 18, and 20 post-transplant.

RESULTS

Seven children received a total of 19 NKIs, and NKI-related acute toxicities were fever (n = 4) followed by chills (n = 3) and hypertension (n = 3); all toxicities were tolerable. Grade ≥II acute GVHD and chronic GVHD developed in two and five patients, respectively. Higher amount of NK cell population was detected in peripheral blood until 60 days post-transplant than that in the reference cohort. Cytomegalovirus and BK virus reactivation occurred in all patients and Epstein-Barr virus in six patients. Six patients died of relapse/progression (n = 5) or treatment-related mortality (n = 1), and one patient remained alive.

CONCLUSION

NKI following haplo-SCT was relatively safe and feasible in patients with recurrent neuroblastoma. Further studies to enhance the graft-versus-tumor effect without increasing GVHD are needed.

Preparation of highly activated natural killer cells for advanced lung cancer therapy

Background: Natural killer (NK) cells can be used as an adoptive immunotherapy to treat cancer patients. Purpose: In this study, we evaluated the efficacy of highly activated NK (HANK) cell immunotherapy in patients with advanced lung cancer. Patients and methods: Between March 2016 and September 2017, we enrolled 13 patients who met the enrollment criteria. Donor peripheral blood monocytes were isolated from patients and the NK cells were expanded. After 12 days of culture, the cells were collected and infused intravenously on days 13 to 15. The enrolled patients received at least one course including three times of infusions. The lymphocyte subsets, cytokine production, and the expression of carcinoembryonic antigen (CEA) and thymidine kinase 1 (TK1) were measured before treatment and after the last infusion. Results: No side effects were observed. After a three-month follow-up, the percentage of patients who achieved stable disease and progressive disease was 84.6% and 15.4%. Moreover, the level of IFN-γ was significantly higher after treatment and the level of CEA decreased substantially. The overall immune function of the patients who received the NK cell therapy remained stable. Conclusion: This is the first study to describe the efficacy of NK cell therapy of patients with advanced lung cancer. These clinical observations demonstrated that NK cell is safe and efficient for advanced lung cancer therapy.

Magnetic delivery of Fe3O4@polydopamine nanoparticle-loaded natural killer cells suggest a promising anticancer treatment

Natural killer (NK)-cell-based immunotherapy has been reported to have promising prospects in the treatment of non-small cell lung cancer, one of the most common malignancies in the world. It has been proven that higher the NK cell infiltration into the tumor, the better is the curative effect. Therefore, it would be beneficial to develop a method that increases NK cell recruitment and infiltration into the tumor site. The purpose of this study was to establish an immune-cell delivery system for clear lung cancer cells based on magnetic nanoparticle (NP)-labeled NK cells that can be accumulated at the tumor site by placing a tiny external magnetic device inside animals. We developed superparamagnetic iron oxide NPs consisting of a magnetic Fe3O4 core and a shell of polydopamine (PDA) for magnetic targeting therapy. Fe3O4@PDA NPs possess favorable physiological stability and biocompatibility that facilitate their active uptake by NK cells. The biology of NK cells was not affected by the presence of NPs. In vitro and in vivo studies showed that Fe3O4@PDA NP-labeled NK cells significantly inhibited tumor growth and reduced the expression of Ki-67 and increased the apoptosis of A549 cancer cells. H&E staining showed Fe3O4@PDA NP-labeled NK cells, under a magnetic field, had higher intra-tumoral iron density and increased accumulation of CD56+ NK cells. Our results suggest that Fe3O4@PDA NPs are a promising magnetic nanomaterial that can manipulate immune cells, thereby inhibiting tumor growth.

Sorafenib paradoxically activates the RAS/RAF/ERK pathway in polyclonal human NK cells during expansion and thereby enhances effector functions in a dose- and time-dependent manner

Natural killer (NK) cells play a major role in host immunity against leukaemia and lymphoma. However, clinical trials applying NK cells have not been as efficient as hoped for. Patients treated with rapidly accelerated fibrosarcoma (RAF) inhibitors exhibit increased tumour infiltration by immune cells, suggesting that a combination of RAF inhibitors with immunotherapy might be beneficial. As mitogen-activated protein kinases (MAPKs) such as raf-1 proto-oncogene, serine/threonine kinase (CRAF) regulate NK cell functions, we performed an in-vitro investigation on the potential of clinically relevant short-acting tyrosine kinase inhibitors (TKIs) as potential adjuvants for NK cell therapy: NK cells from healthy human blood donors were thus treated with sorafenib, sunitinib or the pan-RAF inhibitor ZM336372 during ex-vivo expansion. Functional outcomes assessed after washout of the drugs included cytokine production, degranulation, cytotoxicity, apoptosis induction and signal transduction with/without target cell contact. Paradoxically, sorafenib enhanced NK cell effector functions in a time- and dose-dependent manner by raising the steady-state activation level. Of note, this did not lead to NK cell exhaustion, but enhanced activity against target cells such as K562 or Daudis mediated via the RAS/RAF/extracellular-regulated kinase (ERK) pathway, but not via protein kinase B (AKT). Our data will pave the path to develop a rationale for the considered use of RAF inhibitors such as sorafenib for pre-activation in NK cell-based adoptive immune therapy.

Triplebody Mediates Increased Anti-Leukemic Reactivity of IL-2 Activated Donor Natural Killer (NK) Cells and Impairs Viability of Their CD33-Expressing NK Subset

Natural killer cells (NK) are essential for the elimination of resistant acute myeloid and acute lymphoblastic leukemia (AML and ALL) cells. NK cell-based immunotherapies have already successfully entered for clinical trials, but limitations due to immune escape mechanisms were identified. Therefore, we extended our established NK cell protocol by integration of the previously investigated powerful trispecific immunoligand ULBP2-aCD19-aCD33 [the so-called triplebodies (TBs)] to improve the anti-leukemic specificity of activated NK cells. IL-2-driven expansion led to strongly elevated natural killer group 2 member D (NKG2D) expressions on donor NK cells which promote the binding to ULBP2⁺ TBs. Similarly, CD33 expression on these NK cells could be detected. Dual-specific targeting and elimination were investigated against the B-cell precursor leukemia cell line BV-173 and patient blasts, which were positive for myeloid marker CD33 and B lymphoid marker CD19 exclusively presented on biphenotypic B/myeloid leukemia’s. Cytotoxicity assays demonstrated improved killing properties of NK cells pre-coated with TBs compared to untreated controls. Specific NKG2D blocking on those NK cells in response to TBs diminished this killing activity. On the contrary, the observed upregulation of surface CD33 on about 28.0% of the NK cells decreased their viability in response to TBs during cytotoxic interaction of effector and target cells. Similar side effects were also detected against CD33⁺ T- and CD19⁺ B-cells. Very preliminary proof of principle results showed promising effects using NK cells and TBs against primary leukemic cells. In summary, we demonstrated a promising strategy for redirecting primary human NK cells in response to TBs against leukemia, which may lead to a future progress in NK cell-based immunotherapies.

Impact of gefitinib in early stage treatment on circulating cytokines and lymphocytes for patients with advanced non-small cell lung cancer

Objectives

The impact of epidermal growth factor receptor (EGFR) tyrosine-kinase inhibitors (TKIs) on the human immune system remains undefined. This study illustrates the immunomodulatory effect of gefitinib in patients with advanced non-small cell lung cancer (NSCLC) and its relevant prognostic significance.

Patients and methods

Peripheral blood samples were collected from 54 patients at baseline and after 4 weeks of gefitinib treatment. Circulating lymphocyte populations and cytokine levels were measured. Pilot investigation of the impact of gefitinib on programmed cell death ligand-1 (PD-L1) expression was conducted by immunohistochemistry (IHC).

Results and conclusion

A significant increase of peripheral natural killer cells and interferon-gamma (INF-γ) after 4 weeks of gefitinib treatment (P=0.005 and 0.02, respectively). In addition, circulating interleukin (IL)-6 was significantly decreased, especially in patients sensitive to gefitinib (P<0.001). Higher levels of IL-6 at baseline independently correlated with poorer progression-free survival. Experiments with NSCLC specimens illustrated that PD-L1 expression were downregulated after 4 weeks of gefitinib treatment. In summary, it was found that gefitinib treatment can alter circulating cytokines and lymphocytes. Dynamic changes of circulating lymphocytes, cytokines, and even PD-L1 IHC expression around gefitinib treatment support the specific immunomodulatory effect of this agent for advanced NSCLC.

Natural Killer Cell Adoptive Transfer Therapy: Exploiting the First Line of Defense Against Cancer

Natural killer (NK) cells constitute an important component of the initial immunological response against transformed cells. However, chronic exposure to the tumor microenvironment can fundamentally alter the ability of NK cells to sufficiently control tumor progression. Thus, the adoptive transfer of healthy, functional NK cells as an interventional therapy has been an area of great interest for improving patient outcomes. Recent developments in the field have provided a better understanding of what makes the NK compartment effective against malignant cells. Moreover, there are now multiple potential sources of NK cell products for infusion as well as techniques to manipulate these cells to enhance their antitumor functions. This review explores the advantages and disadvantages of various sources of NK cells as well as prospective therapeutic enhancements to adoptively transferred NK cells.

Immune Effects of Nickel

Data on nickel immunomodulation are contradictory. The most consistent immune effects are suppression of immune responses. It has been show that T-lymphocytes and NK cells are more susceptible to nickel toxicity than are B lymphocytes or macrophages. Data reported about cytokine production in human and nickel reactive T-cell clones are also conflicting. Some authors studied cytokine production PBMC cultures of nickel allergic individuals after stimulation with NiSo4. They showed a higher synthesis of IL4, IL5 and IL13 but not of IFN gamma and TNFα in Ni allergic subjects. We found that the addiction of NiSo4 to the PBMC cultures of non sensitised subjects induces a reduction of release of IL5, IFN γ and TNFα. Our studies demonstrate a clear difference in NK cell activity between nickel-tolerant and intolerant individuals. In particular NK cell activity in reduced in sensitised patients respect to the normal subjects and the addition of Ni to the PBMC cultures induce a significant decrease of NK cell activity. The decrease was greater in cell derived from allergic subjects than non allergic. In conclusion, reported data show Ni has immunotoxic potential. Researches are in progress in an attempt to correlate the present data with other immune parameters and to measure the effects of a Ni free diet on the immune system of subjects with Ni intolerance. The comprehension of the mechanisms inducing these changes requires further studies in the uptake and intracellular distribution and binding of the metal.

Exploiting natural anti-tumor immunity for metastatic renal cell carcinoma

Clinical observations of spontaneous disease regression in some renal cell carcinoma (RCC) patients implicate a role for tumor immunity in controlling this disease. Puzzling, however, are findings that high levels of tumor infiltrating lymphocytes (TIL) are common to RCC. Despite expression of activation markers by TILs, functional impairment of innate and adaptive immune cells has been consistently demonstrated contributing to the failure of the immune system to control RCC. Immunotherapy can overcome the immunosuppressive effects of the tumor and provide an opportunity for long-term disease free survival. Unfortunately, complete response rates remain sub-optimal indicating the effectiveness of immunotherapy remains limited by tumor-specific factors and/or cell types that inhibit antitumor immune responses. Here we discuss immunotherapies and the function of multiple immune system components to achieve an effective response. Understanding these complex interactions is essential to rationally develop novel therapies capable of renewing the immune system's ability to respond to these tumors.

The antileukemic potential of natural killer cells

The antileukemic potential of natural killer (NK) cells has over the years raised considerable interest and new immune-based treatment protocols characterized by the infusion of freshly isolated or ex vivo activated and expanded effectors have been designed. Several aspects still need to be addressed, including the optimal timing of NK infusion during the course of the disease, the best preparative regimen, the origin of NK cells and the possible need of ex vivo NK cell manipulation before the infusion. The aims of this review are to discuss the experimental and clinical data available on the role played by NK cells for leukemia patients and to revise the different good manufacturing practice protocols for ex vivo manipulation of these effector cells.

Natural killer (NK) cells inhibit systemic metastasis of glioblastoma cells and have therapeutic effects against glioblastomas in the brain

BACKGROUND

Glioblastoma multiforme (GBM) is characterized by extensive local invasion, which is in contrast with extremely rare systemic metastasis of GBM. Molecular mechanisms inhibiting systemic metastasis of GBM would be a novel therapeutic candidate for GBM in the brain.

METHODS

Patient-derived GBM cells were primarily cultured from surgical samples of GBM patients and were inoculated into the brains of immune deficient BALB/c-nude or NOD-SCID IL2Rgamma(null) (NSG) mice. Human NK cells were isolated from peripheral blood mononucleated cells and expanded in vitro.

RESULTS

Patient-derived GBM cells in the brains of NSG mice unexpectedly induced spontaneous lung metastasis although no metastasis was detected in BALB/c-nude mice. Based on the difference of the innate immunity between two mouse strains, NK cell activities of orthotopic GBM xenograft models based on BALB/c-nude mice were inhibited. NK cell inactivation induced spontaneous lung metastasis of GBM cells, which indicated that NK cells inhibit the systemic metastasis. In vitro cytotoxic activities of human NK cells against GBM cells indicated that cytotoxic activity of NK cells against GBM cells prevents systemic metastasis of GBM and that NK cells could be effective cell therapeutics against GBM. Accordingly, NK cells transplanted into orthotopic GBM xenograft models intravenously or intratumorally induced apoptosis of GBM cells in the brain and showed significant therapeutic effects.

CONCLUSIONS

Our results suggest that innate NK immunity is responsible for rare systemic metastasis of GBM and that sufficient supplementation of NK cells could be a promising immunotherapeutic strategy for GBM in the brain.

Human cancer cells with stem cell-like phenotype exhibit enhanced sensitivity to the cytotoxicity of IL-2 and IL-15 activated natural killer cells

Tumors harbor a population of cancer stem cells (CSCs) which can drive tumor progression and therapeutical resistance. Nature killer (NK) cells are best known for their ability to directly recognize and kill malignant cells. However, the susceptibility of cancer stem cells to NK cells is not fully understood. Here we demonstrated that human CD44+CD24- breast CSCs were shown enhanced sensitivity to IL-2 and IL-15 activated NK cells. CD44+CD24- CSCs expressed higher levels of NKG2D ligands ULBP1, ULBP2 and MICA. Blockade assay showed that the sensitivity of CSCs to NK cells-mediated lysis was mainly dependent on NKG2D. Furthermore, redox oxygen species (ROS)-low tumor cells were more sensitive to NK cells. The presence of antioxidant enzymes inhibitor L-S,R-buthionine sulfoximine or H2O2 retarded the cytotoxicity of NK cells to CD44+CD24- CSCs. In addition, NK cells could readily target CD133+ colonal CSCs. Our findings provide novel targets for NK cells-based immunotherapy and are of great importance for translational medicine.

Establishment of a heterotypic 3D culture system to evaluate the interaction of TREG lymphocytes and NK cells with breast cancer

Three-dimensional (3D) culture approaches to investigate breast tumour progression are yielding information more reminiscent of the in vivo microenvironment. We have established a 3D Matrigel system to determine the interactions of luminal phenotype MCF-7 cells and basal phenotype MDA-MB-231 cells with regulatory T lymphocytes and Natural Killer cells. Immune cells were isolated from peripheral blood using magnetic cell sorting and their phenotype validated using flow cytometry both before and after activation with IL-2 and phytohaemagglutinin. Following the establishment of the heterotypic culture system, tumour cells displayed morphologies and cell-cell associations distinct to that observed in 2D monolayer cultures, and associated with tissue remodelling and invasion processes. We found that the level of CCL4 secretion was influenced by breast cancer phenotype and immune stimulation. We further established that for RNA extraction, the use of proteinase K in conjunction with the Qiagen RNeasy Mini Kit and only off-column DNA digestion gave the best RNA yield, purity and integrity. We also investigated the efficacy of the culture system for immunolocalisation of the biomarkers oestrogen receptor-α and the glycoprotein mucin 1 in luminal phenotype breast cancer cells; and epidermal growth factor receptor in basal phenotype breast cancer cells, in formalin-fixed, paraffin-wax embedded cultures. The expression of these markers was shown to vary under immune mediation. We thus demonstrate the feasibility of using this co-culture system for downstream applications including cytokine analysis, immunolocalisation of tumour biomarkers on serial sections and RNA extraction in accordance with MIQE guidelines.

Immunotherapeutic applications of NK cells

Natural Killer (NK) cells are lymphoid cells that exhibit an innate response against virus-infected cells. These cells are also capable of mounting an immune response against tumor cells after education through major histocompatibility complex (MHC) class I molecules. NK cell regulation is mediated through IFN-gamma and IL-15, important cytokines which can drive NK cell expansion in vivo. Previous studies have shown effective infusion of allogeneic NK cells after lymphodepleting regimens with induction of remission of poor prognosis acute myeloid leukemia (AML). Challenges remain in the expansion of these NK cells once infused and in their education to recognize tumor targets. A principal mechanism of tumor recognition is through KIR mismatch in cells lacking self MHC I molecules. Activating KIRs exist, though their ligands are unknown at this time. Impacting NK cell expansion and education in vivo has been challenging, and thus far clinical applications of NK cells have shown promise in helping to maintain remission in humans, though this remission has not been maintained. Future efforts to utilize NK cells clinically are focusing on developing more consistency in successful expansion of NK cell and educating them to recognize their tumor targets. Additional efforts to utilize novel antibody-based therapy to engage NK cells to their tumor targets are also in development.

Adoptive Cell Therapy of Melanoma with Cytokine-induced Killer Cells

Melanoma is the most aggressive skin cancer and its incidence is gradually increasing worldwide. Patients with metastatic melanoma have a very poor prognosis (estimated 5-year survival rate of <16%). In the last few years, several drugs have been approved for malignant melanoma, such as tyrosine kinase inhibitors and immune checkpoint blockades. Although new therapeutic agents have improved progression-free and overall survival, their use is limited by drug resistance and drug-related toxicity. At the same time, adoptive cell therapy of metastatic melanoma with tumor-infiltrating lymphocytes has shown promising results in preclinical and clinical studies. In this review, we summarize the currently available drugs for treatment of malignant melanoma. In addition, we suggest cytokine-induced killer (CIK) cells as another candidate approach for adoptive cell therapy of melanoma. Our preclinical study and several previous studies have shown that CIK cells have potent anti-tumor activity against melanomas in vitro and in an in vivo human tumor xenograft model without any toxicity.

Immunophenotypic and functional characterization of ex vivo expanded natural killer cells for clinical use in acute lymphoblastic leukemia patients

The management of acute lymphoblastic leukemia (ALL) patients has witnessed profound changes in recent years. Nonetheless, most patients tend to relapse, underlining the need for new therapeutic approaches. The anti-leukemic potential of natural killer (NK) cells has over the years raised considerable interest. In this study, we developed an efficient method for the expansion and activation of NK cells isolated from healthy donors and ALL patients for clinical use. NK cell products were derived from peripheral blood mononuclear cells of 35 healthy donors and 4 B-lineage ALL by immunomagnetic CD3 T cell depletion followed by CD56 cell enrichment. Isolated NK cells were expanded and stimulated in serum-free medium supplemented with irradiated autologous feeder cells and autologous plasma in the presence of clinical grade interleukin (IL)-2 and IL-15 for 14 days. Healthy donor NK cells expanded on average 34.9 ± 10.4 fold and were represented, after expansion, by a highly pure population of CD3(-)CD56(+) cells showing a significant upregulation of natural cytotoxicity receptors, activating receptors and maturation markers. These expanded effectors showed cytolytic activity against K562 cells and, most importantly, against primary adult B-lineage ALL blasts. NK cells could be efficiently isolated and expanded-on average 39.5 ± 20.3 fold-also from primary B-lineage ALL samples of patients in complete remission. The expanded NK cells from these patients showed a significantly increased expression of the NKG2D- and DNAM1-activating receptors and were cytotoxic against K562 cells. These data provide the basis for developing new immunotherapeutic strategies for the management of ALL patients.

A good manufacturing practice method to ex vivo expand natural killer cells for clinical use

BACKGROUND

Great interest has been raised recently by the design of new adoptive immunotherapeutic strategies based on the in vivo infusion of ex vivo-expanded and activated natural killer (NK) cells. The development of good manufacturing practice (GMP) methods for the efficient production of fully functional NK cells is mandatory for clinical application.

MATERIALS AND METHODS

Peripheral blood mononuclear cells were obtained by leukapheresis and processed in the GMP facility. For NK-cell enrichment, a two-step immunomagnetic procedure consisting of CD3(+) T-cell depletion followed by CD56(+) cell positive selection was used. Isolated NK cells were suspended in serum-free medium containing autologous plasma, interleukin (IL)-2 and IL-15 in the presence of irradiated autologous feeder cells and cultured for 14 days at 37 °C. IL-2 and IL-15 were also added during the last 24 hours of culture. Expanded cells underwent full quality control testing for cytogenetic characteristics, viability, sterility, phenotype and endotoxin status; functional tests, such as degranulation assays and cytotoxicity, were performed on expanded NK cells before cryopreservation and after thawing.

RESULTS

NK-cell populations expanded on average 15.7±4.7 fold by day 14, with a viability of 96% ±0.5. At the end of the incubation period, 97% ±1.1 of the expanded population was CD56(+) NK cells; these effector cells showed significant up-regulation of the activating receptors NKG2D and DNAM-1. Functional tests demonstrated that expanded NK cells are fully functional with no difference whether tested before cryopreservation or after thawing.

DISCUSSION

These data provide the basis for developing new NK-cell-based immunotherapeutic strategies for the treatment of patients with cancer.

hIL-15 gene-modified human natural killer cells (NKL-IL15) augments the anti-human hepatocellular carcinoma effect in vivo

Genetic modification of NK cells may provide new possibilities for developing effective cancer immunotherapy by improving NK cell function and specificity. We previously established human interleukin-15 (hIL-15) gene-modified NKL cells (NKL-IL15) and demonstrated their therapeutic efficiency against human hepatocellular carcinoma (HCC) in vitro. To further assess the applicability of NKL-IL15 cells in adoptive cellular immunotherapy, we further investigated their natural cytotoxicity against HCC in vivo in the present study. NKL-IL15 cells exhibited strong inhibition on the growth of transplanted human HCC tumors in xenograft nude mouse models. Further investigation showed that NKL-IL15 cells expressed much higher levels of cytolysis-related molecules, including NKp80, TRAIL, granzyme B, IFN-γ, and TNF-α, than parental NKL cells in response to HCC stimulation. Moreover, soluble mediators secreted by NKL-IL15 cells decreased HCC cell proliferation; in particular, NKL-IL15-derived TNF-α and IFN-γ induced higher NKG2D ligand expression on target cells and resulted in the increased susceptibility of HCCs to NKL-mediated cytolysis. These results show that hIL-15 gene-modified human NK cells can augment the anti-tumor effect of NK cells on human HCC in vivo and suggest their promising applicability as a new candidate for adoptive immunotherapy against HCCs in the future.

Cell transfer therapy for cancer: past, present, and future

Cell transfer therapy for cancer has made a rapid progress recently and the immunotherapy has been recognized as the fourth anticancer modality after operation, chemotherapy, and radiotherapy. Lymphocytes used for cell transfer therapy include dendritic cells, natural killer (NK) cells, and T lymphocytes such as tumor-infiltrating lymphocytes (TILs) and cytotoxic T lymphocytes (CTLs). In vitro activated or engineered immune cells can traffic to cancer tissues to elicit persistent antitumor immune response which is very important especially after immunosuppressive treatments such as chemotherapy. In this review, we overviewed recent advances in the exploration of dendritic cells, NK cells, and T cells for the treatment of human cancer cells.

Adoptive cell therapies for glioblastoma

Glioblastoma (GBM) is the most common and most aggressive primary brain malignancy and, as it stands, is virtually incurable. With the current standard of care, maximum feasible surgical resection followed by radical radiotherapy and adjuvant temozolomide, survival rates are at a median of 14.6 months from diagnosis in molecularly unselected patients (1). Collectively, the current knowledge suggests that the continued tumor growth and survival is in part due to failure to mount an effective immune response. While this tolerance is subtended by the tumor being utterly “self,” it is to a great extent due to local and systemic immune compromise mediated by the tumor. Different cell modalities including lymphokine-activated killer cells, natural killer cells, cytotoxic T lymphocytes, and transgenic chimeric antigen receptor or αβ T cell receptor grafted T cells are being explored to recover and or redirect the specificity of the cellular arm of the immune system toward the tumor complex. Promising phase I/II trials of such modalities have shown early indications of potential efficacy while maintaining a favorable toxicity profile. Efficacy will need to be formally tested in phase II/III clinical trials. Given the high morbidity and mortality of GBM, it is imperative to further investigate and possibly integrate such novel cell-based therapies into the current standards-of-care and herein we collectively assess and critique the state-of-the-knowledge pertaining to these efforts.

Ex vivo activation and expansion of natural killer cells from patients with advanced cancer with feeder cells from healthy volunteers

BACKGROUND AIMS

Culturing natural killer (NK) cells from patients with advanced cancer is difficult and has restricted the generation of sufficient cell numbers for autologous adoptive NK-cell therapy. The aim of this study was to establish a novel method for ex vivo NK-cell expansion from patients with cancer.

METHODS

NK cells (CD3(-)CD56(+)) were isolated from peripheral blood mononuclear cells from healthy volunteers and cancer patients, and NK(-) fractions were used as feeder cells. Purified NK cells were co-cultured with feeder cells in AIM-V medium (Invitrogen, Carlsbad, CA, USA) supplemented with 5% human serum and 1000 units/mL human interleukin-2.

RESULTS

NK cells co-cultured with feeder cells from healthy volunteers (feeder-HV) expanded more than NK cells co-cultured with feeder cells from cancer patients (feeder-CP). During the 14-day culture period, NK cells from patients with advanced cancer co-cultivated with feeder-HV expanded on average 300-fold. NK cells co-cultivated with feeder-CP expanded on average 169.4-fold. Cultures grown in the presence of feeder-HV contained 93.8 ± 7.0% (mean ± standard deviation; n = 6) CD3(-)CD56(+) NK cells, and cultures grown in the presence of feeder-CP contained 83.6 ± 15.9% CD3(-)CD56(+) NK cells. Feeder-HV caused a relative increase in CD3(+)CD4(+) T cells, whereas feeder-CP did not induce changes. Interleukin-15, a cytokine that induces NK-cell proliferation, was detected in the culture supernatants of feeder-HV but not in those of feeder-CP.

CONCLUSIONS

Feeder cells obtained from healthy volunteers have the potential to expand and activate NK cells from patients with advanced cancer. The novel NK-cell expansion method described here provides a technique for acquiring the large numbers of highly active NK cells from patients with cancer for autologous adoptive immunotherapy.

Enhanced interaction between natural killer cells and lung cancer cells: involvement in gefitinib-mediated immunoregulation

Background

Natural killer (NK) cells can kill tumor cells in a non-MHC-restricted manner. However, cancer cells frequently escape from the attack of NK cells by multiple ways. In this study, we investigated the effect of gefitinib on the interaction between NK cells and lung cancer cells.

Methods

⁵¹Cr release assay, CD107a assay, and IFN-γ secretion assay were performed to detect the sensitivity of lung cancer cell lines A549 and H1975 to NK cells cytotoxicity in the presence of gefitinib. Human NK cells were co-cultured with A549 and H1975 cell lines in the presence of gefitinib. NKG2D ligands, ULBP1, ULBP2, MICA, and MHC-I on tumor cells, and NKG2D, NKp44 and NKp46 on NK cells were evaluated with flow cytometry. ⁵¹Cr release assay was performed when NKG2D antibody were added into the co-culture system. Expressions of stat3 and LC3 I/II on tumor cells were determined with western blot after co-cultured with NK cells. After treated with gefitinib, mannose-6-phosphate receptor (MPR) on H1975 cells was evaluated by flow cytometry. ⁵¹Cr release assay were performed when MPR antagonist were used.

Results

Gefitinib increased cytotoxicity of NK cells to human lung cancer H1975 cells with EGFR L858R + T790M mutations, while not in A549 cells with wild type EGFR. Gefitinib could block the immune escape by up-regulating the expression of NKG2D ligands ULBP1, ULBP2 or MICA on tumor cells and NKG2D on NK cells in the co-culture system. Gefitinib and NK cells up-regulated MHC-I expression in A549 while not in H1975 cells. NKG2D antibody blocked the enhanced NK cytotoxicity by gefitinib. The combination of NK cells and gefitinib could significantly down-regulate stat3 expression. Furthermore, NK cells-mediated tumor cell autophagy was observed in A549 cells while not in H1975 cells. Notably, gefitinib increased autophagy and MPR expression in H1975 cells, which improved the sensitivity to NK cell-based immunotherapy.

Conclusions

Gefitinib greatly enhanced NK cell cytotoxicity to lung cancer cells with EGFR L858R + T790M resistance mutation. Combination of EGFR tyrokinase inhibitors and NK cells adoptive immunotherapy may represent a potentially effective strategy for patients with non-small cell lung cancer.

hIFN-α gene modification augments human natural killer cell line anti-human hepatocellular carcinoma function

Natural killer (NK) cells are characterized by an efficient antitumor activity, and this activity has been exploited as the basis of cancer immunotherapy strategies. Interferon-α (IFN-α) is an important cytokine required for induction of the durable antitumor immune response and is an important stimulator of NK cells. In this study, to augment the efficiency of NK cell cytotoxicity to tumor cells, human IFN-α gene-modified natural killer cell line (NKL) (NKL-IFNα) cells, which could stably secrete IFN-α, were established. We investigated the natural cytotoxicity of NKL-IFNα cells against human hepatocarcinoma cells (HCCs) in vitro and in vivo. NKL-IFNα cells displayed a significantly stronger cytolytic activity against both human HCC cell lines and primary human hepatoma cancer cells compared with parental NKL cells. The increased cytolytic activity of NKL-IFNα cells was associated with the upregulation of cytotoxicity-related genes, such as perforin, granzyme B and Fas ligand, in the NK cells. Moreover, cytokines secreted by NKL-IFNα cells, such as tumor necrosis factor-α and IFN-γ, induced increased expression of Fas on the target HCC cells, and resulted in increased susceptibility of the HCC cells to NK-mediated cytolysis. Encouragingly, NKL-IFNα cells could significantly inhibit HCC tumor growth in a xenograft model and prolonged the survival of tumor-bearing nude mice. These results suggest that IFN-α gene-modified NKL cells could be suitable for the future development of cell-based immunotherapeutic strategies for hepatocellular carcinoma.

Gallic acid: molecular rival of cancer

Gallic acid, a predominant polyphenol, has been shown to inhibit carcinogenesis in animal models and in vitro cancerous cell lines. The inhibitory effect of gallic acid on cancer cell growth is mediated via the modulation of genes which encodes for cell cycle, metastasis, angiogenesis and apoptosis. Gallic acid inhibits activation of NF-κB and Akt signaling pathways along with the activity of COX, ribonucleotide reductase and GSH. Moreover, gallic acid activates ATM kinase signaling pathways to prevent the processes of carcinogenesis. The data so far available, both from in vivo and in vitro studies, indicate that this dietary polyphenol could be promising agent in the field of cancer chemoprevention.

NK cell-based immunotherapy for malignant diseases

Natural killer (NK) cells play critical roles in host immunity against cancer. In response, cancers develop mechanisms to escape NK cell attack or induce defective NK cells. Current NK cell-based cancer immunotherapy aims to overcome NK cell paralysis using several approaches. One approach uses expanded allogeneic NK cells, which are not inhibited by self histocompatibility antigens like autologous NK cells, for adoptive cellular immunotherapy. Another adoptive transfer approach uses stable allogeneic NK cell lines, which is more practical for quality control and large-scale production. A third approach is genetic modification of fresh NK cells or NK cell lines to highly express cytokines, Fc receptors and/or chimeric tumor-antigen receptors. Therapeutic NK cells can be derived from various sources, including peripheral or cord blood cells, stem cells or even induced pluripotent stem cells (iPSCs), and a variety of stimulators can be used for large-scale production in laboratories or good manufacturing practice (GMP) facilities, including soluble growth factors, immobilized molecules or antibodies, and other cellular activators. A list of NK cell therapies to treat several types of cancer in clinical trials is reviewed here. Several different approaches to NK-based immunotherapy, such as tissue-specific NK cells, killer receptor-oriented NK cells and chemically treated NK cells, are discussed. A few new techniques or strategies to monitor NK cell therapy by non-invasive imaging, predetermine the efficiency of NK cell therapy by in vivo experiments and evaluate NK cell therapy approaches in clinical trials are also introduced.

Natural killer cell lines in tumor immunotherapy

Natural killer (NK) cells are considered to be critical players in anticancer immunity. However, cancers are able to develop mechanisms to escape NK cell attack or to induce defective NK cells. Current NK cell-based cancer immunotherapy is aimed at overcoming NK cell paralysis through several potential approaches, including activating autologous NK cells, expanding allogeneic NK cells, usage of stable allogeneic NK cell lines and genetically modifying fresh NK cells or NK cell lines. The stable allogeneic NK cell line approach is more practical for quality-control and large-scale production. Additionally, genetically modifying NK cell lines by increasing their expression of cytokines and engineering chimeric tumor antigen receptors could improve their specificity and cytotoxicity. In this review, NK cells in tumor immunotherapy are discussed, and a list of therapeutic NK cell lines currently undergoing preclinical and clinical trials of several kinds of tumors are reviewed.

Tim-3 is an inducible human natural killer cell receptor that enhances interferon gamma production in response to galectin-9

NK-cell function is regulated by the integration of signals received from activating and inhibitory receptors. Here we show that a novel immune receptor, T-cell Ig and mucin-containing domain-3 (Tim-3), is expressed on resting human NK cells and is up-regulated on activation. The NK92 NK-cell line engineered to overexpress Tim-3 showed a marked increase in IFN-γ production in the presence of soluble rhGal-9 or Raji tumor cells engineered to express Gal-9. The Tim-3(+) population of low-dose IL-12/IL-18-activated primary NK cells significantly increased IFN-γ production in response to soluble rhGal-9, Gal-9 presented by cell lines, and primary acute myelogenous leukemia (AML) targets that endogenously express Gal-9. This effect is highly specific as Tim-3 Ab blockade significantly decreased IFN-γ production, and Tim-3 cross-linking induced ERK activation and degradation of IκBα. Exposure to Gal-9-expressing target cells had little effect on CD107a degranulation. Reconstituted NK cells obtained from patients after hematopoietic cell transplantation had diminished expression of Tim-3 compared with paired donors. This observation correlates with the known IFN-γ defect seen early posttransplantation. In conclusion, we show that Tim-3 functions as a human NK-cell coreceptor to enhance IFN-γ production, which has important implications for control of infectious disease and cancer.

Short-term physiological effects of a xenobiotic mixture on the freshwater mussel Elliptio complanata exposed to municipal effluents

The aim of this study was to investigate the short-term effects of tertiary-treated municipal effluents on the freshwater mussel Elliptio complanata. Caged mussels were immersed during 2 weeks in a river located North of Montreal Island, upstream/downstream the outfall and in one reference site located at the beginning of the Rivière des Prairies. A selection of biomarkers was analyzed to depict changes on various physiological systems: general physiology (mussel viability, condition index and gonado-somatic index), immune status (hemocyte viability, cellularity, phagocytosis efficiency, NK-like cytotoxic activity and lysozyme activity), inflammation (cyclo-oxygenase activity), detoxification (glutathione-S-transferases activity) and vitellogenesis (alkali-labile phosphate level). The analysis of total and fecal coliform counts in water and of heterotrophic bacteria levels in mussel tissues showed that the bacteriological quality of the water strongly decreased from the reference site to the downstream site. This was correlated with a significant loss of weight and an increase of mussel mortality. Cellularity and phagocytosis efficiency were significantly increased in the downstream site compared to the reference site. Though not statistically significant, lysozyme activity was also increased. NK-like cytotoxicity, activity of the pro-inflammatory enzyme COX and the levels of ALP and MT were not significantly changed. Conversely, the municipal effluents induced a significant increase of GST activity in downstream site, indicating a stimulation of detoxification metabolism. Altogether, these results confirm that a short-term exposure to a mixture of bacterial and chemical compounds released by the wastewater treatment plant La Pinière induces adverse physiological effects in E. complanata, as observed with the modulation of immune response and induction of detoxification metabolism.

Natural killer cells and tumor control

PURPOSE OF REVIEW

After hematopoietic cell transplantation (HCT) donor-derived natural killer (NK) cells kill tumor cells to prevent relapse and mediate other beneficial clinical effects including control of infections without inducing graft-vs.-host disease (GVHD). Understanding the determinants of NK cell alloreactivity and function will support improvements in the design of HCT and adoptive cellular therapies.

RECENT FINDINGS

Refinements to the model of NK cell education or licensing have been made which will inform strategies to develop functional alloreactive NK cells for therapeutic use. Differences in NK cell function have been shown to be dependent on the nature of the stimuli. Recent advances have been made in our understanding of the role of activating NK receptors on education and outcome after HCT. The use of adoptively transferred NK cells to treat hematopoietic malignancies has been expanding. New approaches to modulate target sensitivity to NK cell-mediated killing are under development.

SUMMARY

NK cells play an important role in the therapeutic efficacy of HCT, with effects on control of infections, GVHD, engraftment and relapse prevention. Recent advances in our understanding of NK cell biology will support improvements in our ability to exploit NK cells to treat cancer.

Role of interleukin-18 in human natural killer cell is associated with interleukin-2

Human natural killer (NK) cells constitute an important cellular component of innate immunity, capable of killing infected and transformed cells. The proliferation and activation of NK cells are regulated by various cytokines. Interleukin-18 (IL-18) promotes NK cell activation; however, whether the effects of IL-18 on NK cell are associated with other cytokines is still unknown. In this study, we observed that IL-18 induced NK cell apoptosis and inhibited NK cell expansion in the presence of low concentrations of interleukin-2 (IL-2), while high concentrations of IL-2 overcame these effects of IL-18, and high concentrations of IL-2 promoted the stimulatory activity of IL-18 on NK cells. At a low concentration of IL-2, IL-18 induced NK cell apoptosis in part through activation of the FasL/Fas- and TNFα/TNFR-mediated death receptor signaling by enhancing FasL expression and inhibiting c-FLIP(long) expression. However, high concentrations of IL-2 strongly blocked IL-18-induced NK cell apoptosis through alleviating IL-18-induced FasL expression and activation of Fas-mediated death signaling and increasing anti-apoptosis molecule (Bcl-X(L)). These results reveal that the effects of IL-18 on human NK cell are associated with IL-2 concentration and suggest the importance of IL-2 level in cytokine immunotherapy.

Quercetin enhances susceptibility to NK cell-mediated lysis of tumor cells through induction of NKG2D ligands and suppression of HSP70

It is known that treatments with heat shock, some anticancer drugs, and ionizing radiation increase the expression of heat-shock proteins (HSPs) and natural killer group 2D (NKG2D) ligands in tumor cells. The increased HSPs may make the tumor cells resistant to apoptosis and reduction of HSPs may make the tumor cells more susceptible to natural killer (NK)-cell mediated lysis of tumor cells. In this study, we investigated whether quercetin which has inhibitory activities against heat-shock factor, protein kinase C, nuclear factor-kappaB, and phosphatidyl inositol 3-kinase, can modulate the expression of NKG2D ligands and suppress the HSPs in tumor cells. The results of this study showed that quercetin significantly induced the expression of several NKG2D ligands including major histocompatibility complex class I-related chain B, UL16-binding protein 1, and UL16-binding protein 2 in K562, SNU1, and SNU-C4 cells. The quercetin-treated K562, SNU1, and SNU-C4 cells showed an enhanced susceptibility to NK-92 cells through induction of NKG2D ligands. This increased expression of NKG2D ligands seemed to be due to the inhibition of the nuclear factor-kappaB and phosphatidyl inositol 3-kinase pathways. The findings of this study suggest that the induced NKG2D ligands with the decrease of HSP70 protein by quercetin may provide an attractive strategy to improve the effectiveness of NK cell-based cancer immunotherapy.

Amelioration of doxorubicin-induced myocardial oxidative stress and immunosuppression by grape seed proanthocyanidins in tumour-bearing mice

We have investigated the protective effects of grape seed proanthocyanidins on doxorubicin-induced toxicity in tumour-bearing mice. The intraperitoneal administration of doxorubicin (2 mg kg−1 every other day, cumulative dosage for 18 mg kg−1) significantly inhibited the growth of sarcoma 180, and induced myocardial oxidative stress with decreased superoxide dismutase and glutathione peroxidase activity while increasing malondialdehyde formation in the heart or serum. Doxorubicin-induced myocardial oxidative stress also reduced lactate dehydrogenase and creatine kinase activity in the heart and elevated their levels in the serum. Doxorubicin also affected immune functions of tumour-bearing mice with significantly decreased interleukin-2 (IL-2) and interferon-γ (INF-γ) production, and slightly decreased natural killer (NK) cell cytotoxicity, lymphocyte proliferation and CD4+/CD8+ ratio. It markedly increased the percentages of cytotoxic T cells (CD3+CD8+), helper T cells (CD3+CD4+), IL-2R+CD4+, and IL-2R+ cells as compared with untreated tumour-bearing mice. The intragastric administration of proanthocyanidin (200 mg kg−1 daily) significantly inhibited tumour growth, and increased NK cell cytotoxicity, lymphocyte proliferation, CD4+/CD8+ ratio, IL-2 and INF-γ production. Moreover, proanthocyanidin strongly enhanced the anti-tumour effect of doxorubicin and the above immune responses, and completely eliminated myocardial oxidative stress induced by doxorubicin. In conclusion, intragastric administration of proanthocyanidin could enhance the anti-tumour activity of doxorubicin and ameliorate doxorubicin-induced myocardial oxidative stress and immunosuppression in tumour-bearing mice.

Anti-cancer activity and mechanistic features of a NK cell activating molecule

Natural cytotoxicity receptors (NCRs) are major activating receptors involved in NK cytotoxicity. NCR expression varies with the activation state of NK cells, and the expression level correlates with NK cells' natural cytotoxicity. In this study, we found that Gö6983, a PKC inhibitor, induced a remarkable increase of NCR expression on primary NK cells, but other PKC inhibitors and NK cell stimulators such as IL-2 and PMA, did not. Gö6983 increased the expression of NCR in a time- and concentration-dependent manner. Furthermore, Gö6983 strongly upregulated the surface expression of death ligands FasL and TRAIL, but not cytotoxic molecules perforin and granzyme B. Unlike two other NK stimulating molecules, IL-2, and PMA, Gö6983 did not induce NK cell proliferation. Up-regulation of NCRs and death ligands on NK cells by Gö6983 resulted in a significant enhancement of NK cytotoxicity against various cancer cell lines. Most importantly, administration of Gö6983 effectively inhibited pulmonary tumor metastasis in mice in a dose-dependent manner. These results suggest that Gö6983 functions as an NK cell activating molecule (NKAM); this NKAM is a novel anti-cancer and anti-metastasis drug candidate because it enhances NK cytotoxicity against cancer cells in vivo as well as in vitro.

Infusion of the allogeneic cell line NK-92 in patients with advanced renal cell cancer or melanoma: a phase I trial

BACKGROUND

Renal cell cancer and malignant melanoma are two types of cancer that are responsive to immunotherapy. In this phase I dose-escalation study, the feasibility of large-scale expansion and safety of administering ex vivo-expanded NK-92 cells as allogeneic cellular immunotherapy in patients with refractory renal cell cancer and melanoma were determined.

METHODS

Twelve patients (aged 31-74 years) were enrolled, three per cohort at cell dose levels of 1x10(8)/m(2), 3x10(8)/m(2), 1x10(9)/m(2) and 3x10(9)/m(2). One treatment course consisted of three infusions. Eleven patients had refractory metastatic renal cell cancer; one patient had refractory metastatic melanoma.

RESULTS

The NK-92 cells were expanded in X-Vivo 10 serum-free media supplemented with 500 U/mL Proleukin recombinant human interleukin-2 (rhIL-2), amino acids and 2.5% human AB plasma. Final yields of approximately 1x10(9) cells/culture bag (218-250xexpansion) over 15-17 days were achievable with >or=80% viability. Infusional toxicities of NK-92 were generally mild, with only one grade 3 fever and one grade 4 hypoglycemic episode. All toxicities were transient, resolved and did not require discontinuation of treatment. One patient was alive with disease at 4 years post-NK-92 infusion. The one metastatic melanoma patient had a minor response during the study period. One other patient exhibited a mixed response.

DISCUSSION

This study establishes the feasibility of large-scale expansion and safety of administering NK-92 cells as allogeneic cellular immunotherapy in advanced cancer patients and serves as a platform for future study of this novel natural killer (NK)-cell based therapy.

Chemotherapeutic potential of two gallic acid derivative compounds from leaves of Casearia sylvestris Sw (Flacourtiaceae)

Casearia sylvestris is a plant used in the treatment of several diseases, including cancer. Studies have shown that C. sylvestris presents an interesting antitumoral potential, due to the presence of casearins and some sesquiterpens with antitumoral activity. In this work, we tested the potential chemotherapeutic of two gallic acid-derived compounds isolated from C. sylvestris leaves: isobutyl gallate-3,5-dimethyl ether (IGDE) and methyl gallate-3,5-dimethyl ether (MGDE). We utilized two tumoral models: Ehrlich ascites tumor cells (EAT)/BALB/c mice and Lewis lung cancer cells (LLC1)/C57bl/6 mice. MGDE and IGDE increased the survival of mice inoculated with EAT cells and decreased the tumor volume in the LLC1 model, compared to control groups. Both compounds presented similar and low in vitro cytotoxicity against Ehrlich ascites tumor cells and did not present any significant toxicity against Lewis lung cancer cells. Since the direct in vitro activity against Ehrlich tumor and Lewis lung cancer cells was low, we investigated the effects of MGDE or IGDE treatment on the activity of total natural killer cells from Ehrlich ascites tumor-bearing mice, as a possible explanation for the mechanisms of these compounds in vivo. MGDE and IGDE improved NK cell cytotoxicity against Ehrlich ascites cells. As expected, tumor growth in non-treated mice markedly suppressed NK cell cytolysis while, IGDE completely reversed this effect, when mice were treated with 0.5 mg/kg dosages of these compounds for 4 days. The pharmacokinetic studies showed that IGDE remains in the organism for a long period of time, possibly explaining the higher compound efficiency.

Immunotherapy of AML

The applications of chemotherapy for the treatment of AML have been unchanged over the past three decades, with only 30% of patients demonstrating disease-free survival (DFS) [118]. Despite achieving CR following induction chemotherapy, the majority of patients relapse and succumb to their disease [6]. In view of the limitations encountered by cytarabine/anthracycline based regimes, attention has shifted to immunotherapy as a means to treat AML and provide significant long-term DFS. This chapter will discuss the role of the immune system and recent advances in immunotherapy for the treatment of AML, focusing on cellular and non-cellular approaches.