Regulation of natural killer cell function by glass-adherent cells in patients with primary intracranial malignancies

Dynamic analysis of immune status in patients with intracranial germ cell tumor and establishment of an immune risk prognostic model

Introduction

Immune status was evaluated by means of lymphocyte subset counts and immune factors in cancer. This study analyzed the peripheral blood immune index and survival outcomes in intracranial germ cell tumor (iGCT) patients.

Methods

Peripheral blood lymphocyte subset counts and levels of interleukin (IL)-2, IL-4, IL-6, IL-10, tumor necrosis factor (TNF), and interferon-γ (IFN) from 133 iGCT patients were collected and retrospectively analyzed. Their clinical information was extracted from the hospital database, and prognosis was confirmed by telephone visit. Patients (n=11) underwent prospective review and their samples of peripheral blood lymphocytes were verified.

Results

A total of 113 (84.2%) patients received comprehensive treatments, including 96 standard therapy (combination of full course chemotherapy and radiology with or without surgery) and 17 comprehensive but non-standard therapy (either without full course chemotherapy or with non-standard radiotherapy) and 98 (73.7%) reached complete or partial response. T lymphocytes (CD3⁺), cytotoxic T cells (CD3⁺CD8⁺ or Tc), and B lymphocytes (CD19⁺) decreased (p=0.047, p=0.004, and p<0.001, respectively), while activated cytotoxic T lymphocytes (CD8⁺CD25⁺) and IFN increased (p<0.001 and p=0.002, respectively) after treatment. Median survival was 45.33 months, and patients with increased Tc cells and activated Tc cells as well as IFN presented encouraging outcomes (p=0.039, p=0.041, and p=0.017 respectively). Regression analysis showed that non-increased Tc cells and non-increased activated Tc cells were independent factors of poor prognosis (p=0.016, HR=3.96, 95%CI=1.288-12.20; p=0.002, HR=4.37 95%CI= 1.738-10.97). Standard chemo-radiotherapy was independently related to reduced risk of death(p=0.022, HR=0.19, 95%CI=0.044-0.79). Consistence was seen in a nomogram established through retro and prospective studies. An immune risk model indicated the activated group (with both increased activated T cells and IFN levels) had the best prognosis, the mildly activated type with elevated IFN levels had intermediate outcome, and patients with the silent immune status had the worst outcomes (Log rank test, p=0.011).

Conclusion

Implementation of standard comprehensive treatments led to positive responses. Dynamic monitoring of peripheral blood lymphocyte subsets can be used as an auxiliary indicator for prognosis judgment.

Remodeling tumor immune microenvironment (TIME) for glioma therapy using multi-targeting liposomal codelivery

BACKGROUND

Glioblastoma (GBM) treatment is undermined by the suppressive tumor immune microenvironment (TIME). Seek for effective methods for brain TIME modulation is a pressing need. However, there are two major challenges against achieving the goal: first, to screen the effective drugs with TIME-remodeling functions and, second, to develop a brain targeting system for delivering the drugs.

METHODS

In this study, an α7 nicotinic acetylcholine receptors (nAChRs)-binding peptide ^DCDX was used to modify the codelivery liposomes to achieve a 'three-birds-one-stone' delivery strategy, that is, multi-targeting the glioma vessel endothelium, glioma cells, and tumor-associated macrophages that all overexpressed α7 nAChRs. A brain-targeted liposomal honokiol and disulfiram/copper codelivery system (CDX-LIPO) was developed for combination therapy via regulating mTOR (mammalian target of rapamycin) pathway for remodeling tumor metabolism and TIME. Honokiol can yield a synergistic effect with disulfiram/copper for anti-GBM.

RESULTS

It was demonstrated that CDX-LIPO remarkably triggered tumor cell autophagy and induced immunogenic cell death, and meanwhile, activated the tumor-infiltrating macrophage and dendritic cells, and primed T and NK (natural killer) cells, resulting in antitumor immunity and tumor regression. Moreover, CDX-LIPO promoted M1-macrophage polarization and facilitated mTOR-mediated reprogramming of glucose metabolism in glioma.

CONCLUSION

This study developed a potential combinatory therapeutic strategy by regulation of TIME and a 'three-birds-one-stone'-like glioma-targeting drug delivery system.

T lymphocyte subsets and immunoglobulins in intracranial tumor patients before and after treatment, and based on histological type of tumors

It has been reported that nervous system and peripheral immune system communicate with each other and the peripheral immune status is depressed in some intracranial tumor (ICT) patients pre operatively. Little is known about the immune status of intracranial tumor patients during the post operative survival period. We thus investigated total T cells (CD 11+), helper/inducer (CD4+) T cells, suppressor/cytotoxic (CD8+) T cells, B cells (CD19+) and serum immunoglobulins in peripheral blood in certain ICT patients before and after treatment, and based on the histological type of the tumors. Post treatment analysis were conducted 30 days after surgical removal of tumor tissue in benign brain tumor patients and 30 days after chemo therapy (CT)/radiotherapy (RT) following surgical removal of tumor tissue in malignant brain tumor patients. Decreased CD11+, CD4+ and increased CD8+ T cell counts were observed in both benign and malignant tumor cases before treatment compared with control subjects. After treatment, CD4+ T cell count increased and CD8+ T cell count decreased than their pre treatment levels. Serum IgA and IgG levels were decreased in both benign and malignant brain tumor patients before treatment than in control subjects. Serum IgM level has been increased in both benign and malignant tumor patients before and after treatment than in control subjects. Anaplastic malignant astrocytoma, medulloblastoma and glioblastoma multiforme patients showed higher IgM level than astrocytoma, meningioma and ependymoma patients. In conclusions, the depressed host cellular immunity in benign and malignant tumor patients before treatment may be due to the changes in CD4+ and CD8+ counts in addition to tumour specific immunosuppressive factors. Treatment procedures such as surgery, CT and RT may play certain role in the post operative depressed immunosuppression in malignant tumor patients. Humoral immune mechanism (CD19+) in the ICT patients was less markedly affected.

Experimental appraisal of the lack of antitumor natural killer cell-mediated immunosurveillance in response to lymphomas growing in the mouse brain

OBJECT

Natural killer (NK) cell-mediated immunosurveillance in the brain is currently obscure, in contrast with the intracerebral immune reaction of cytotoxic T lymphocytes (CTLs) to tumor cells. The goal of this study, in which a controlled tumor model was used, was to investigate a relationship between NK cells and major histocompatibility complex (MHC) Class I gene expression in intracerebral tumor-bearing hosts.

METHODS

A matched set of two cloned tumor cell lines (lymphoma+ and lymphoma-), which differ only in MHC Class I gene expression, was established from the parental YAC-1 cell line (a target widely accepted as being sensitive to murine NK cells). An in vivo rapid elimination assay (REA) was performed using tumor cells labeled with [125I] 5-iodo-2-deoxyuridine to evaluate intracerebral NK cell-mediated defense immunity. There was no difference in the in vitro growth rate and c-myc gene expression between lymphoma+ and lymphoma- cells. An in vitro cytotoxicity assay showed that the lymphoma+ cell line was sensitive to MHC Class I-restricted CTL-mediated lysis, whereas the lymphoma- line was refractory to it. Both were susceptible to NK cell-mediated lysis, comparable to the level shown by YAC-1 cells. Flow cytometry revealed that lymphoma+ reacted positively for cell-surface MHC Class I molecules, whereas lymphoma- had no reaction. Four- to 72-hour REAs, performed using either cell line, disclosed no clearance of radiolabeled tumor cells from the brain in independent groups of untreated and T cell-depleted mice; this contrasted with eradication of radioactivity from the lungs. In NK cell-depleted mice, however, there was no elimination of radiolabeled tumor cells from the brain or lungs. The MHC Class I expression on lymphoma+ cells was enhanced after intracerebral inoculation, rendering them less sensitive to NK cells. By contrast, lymphoma- cells remained negative for cell-surface MHC expression, being sensitive to NK cells and refractory to CTLs after intracerebralinoculation. These results indicate the absence of NK cell-mediated lytic activity in the brain. This allows even NK cell-sensitive tumor cells to escape intracerebral immunosurveillance.

CONCLUSIONS

These experiments have refined the information that the brain may lack NK cell-mediated defense immunity against intracerebrally growing tumors, representing a characteristic aspect of this immunologically privileged organ.

Therapeutic activity of NK cells against tumors

While it is generally accepted that natural killer (NK) cells, by killing tumor cells in the circulation, represent a first line of defense against metastases, their therapeutic activity against established tumors has been limited. In this review, we describe studies to improve the therapeutic effectiveness of activated NK cells in both animal models and clinical trials to better understand the biological problems that limit their effectiveness.

Exploitation of immune mechanisms in the treatment of central nervous system cancer

Malignant gliomas are among the most common intrinsic brain tumors of both children and adults, and, because of unique aspects of their biology and anatomic site, they are the most refractory to conventional therapeutic strategies involving surgery, radiotherapy, or chemotherapy. Given the failure of standard therapies to improve the outlook of affected patients, significant attention has been focused on development of alternative treatments, particularly immunotherapy. Attempts have been made to treat gliomas using a variety of immunologically based strategies, including passive immunization, adoptive cellular immunotherapy, local and systemic delivery of biological response modifiers, and vaccination with tumor cells. Although preclinical modeling of these therapies provided an impetus for translation of their results into clinical protocols, these therapies have failed to yield consistently promising results in initial trials. However, significant insights into the immunobiology of the central nervous system (CNS) and gliomas have been gained from these studies, and have established that a number of immunobiological features of the brain and of gliomas themselves may be critical determinants in regulating efficacious treatment of these tumors. These include the following: (1) the presence of a blood-brain barrier that, although partially disrupted by the tumor, functions to exclude elements of the immune system from the tumor or brain parenchyma; (2) a lack of organized secondary lymphatic tissues supporting efficient immune responses locally in the CNS; (3) low levels of expression of major histocompatibility complex proteins in the CNS; (4) an apparent paucity of the most efficient antigen-presenting cells; and (5) glioma-derived immunosuppressive factors, such as transforming growth factor-beta, that interfere with the induction of local as well as systemic immune responses to the tumor. Recognition of these factors, and an appreciation of the underlying need for and validity of developing immunologically based therapies for gliomas, supports continued development of novel immunotherapeutic approaches, particularly those attempting to enhance the immunogenicity of glioma cells. This review addresses the current state of knowledge regarding the immunobiology of gliomas, recent developments in immunotherapy of gliomas, and promising future directions for development and implementation of cellular immunotherapy of gliomas.

Immune defects observed in patients with primary malignant brain tumors

Malignant glioblastomas (gliomas) account for approximately one third of all diagnosed brain tumors. Yet, a decade of research has made little progress in advancing the treatment of these tumors. In part this lack of progress is linked to the challenge of discovering how glial tumors are capable of both modulating host immune function and neutralizing immune-based therapies. Patients with gliomas exhibit a broad suppression of cell-mediated immunity. The impaired cell-mediated immunity observed in patients with gliomas appears to result from immunosuppressive factor(s) secreted by the tumor. This article reviews what has been elucidated about the immune defects of patients harboring glioma and the glioma-derived factors which mediate this immunosuppression. A model involving systemic cytokine dysregulation is presented to suggest how the immune defects arise in these individuals.

Interleukin 2 and interferon alpha modulation of the lymphocyte non-major histocompatibility-restricted lytic activity in glioblastoma patients

We studied the non-major histocompatibility-restricted cytotoxic activity induced by interleukin 2 (IL-2) and interferon alpha (IFN-alpha) in mononuclear cells of peripheral blood (PBMNC) from glioblastoma patients. We observed a depressed cytotoxic activity against natural killer (NK)-sensitive target cells in PBMNC from all the patients studied. Culture of these PBMNC with IFN-alpha for 5 days augmented the cytotoxic activity against NK-sensitive target cells in a small group of patients. Incubation with IL-2 for 5 days normalizes the decreased cytotoxic activity against NK-sensitive target cells of PBMNC from all the glioblastoma patients studied. When PBMNC from these patients were incubated with IL-2 for 5 days and IFN-alpha was added to the culture medium in the last 2 h of culture, an enhancement of non-major histocompatibility-restricted cytotoxic activity was observed compared with that obtained with either IL-2 or IFN-alpha alone. This improvement of the cytotoxic activity was more relevant when it was tested against NK-resistant target cells. The potential utility of the sequential use of the two cytokines in generating non-major histocompatibility cytotoxic activity in glioblastoma patients is discussed.

Modulation by interferon alpha of the decreased natural killer activity in patients with glioblastoma

It is known that natural killer (NK) cells are involved in immunosurveillance against tumours. This study examines the NK activity of mononuclear cells (MNC) from the peripheral blood of patients with glioblastoma. The cytotoxic inducer effect of interferon-alpha (IFN-alpha) upon these MNC has also been studied. A marked decrease in NK activity mediated by MNC from these patients was found. This functional defected in MNC is not due to a decrease in phenotypically defined NK cells. After long-term (5-day) incubation with IFN-alpha, MNC from 5 out of 14 patients showed strong lytic activity against NK-sensitive target cells. In this system, IFN-alpha failed to induce cytotoxic activity against NK-resistant target cells in MNC from all the patients studied. This in vitro induction of cytotoxic activity in MNC from some patients with glioblastoma by IFN-alpha suggests a potential immunotherapeutic use of the lymphokine in these subjects.

Cell mediated cytotoxicity and cytokine production in peripheral blood mononuclear cells of glioma patients

A mannoprotein preparation (MP) from Candida albicans induced MHC-unrestricted cytotoxicity in peripheral blood mononuclear cells (PBMC) from healthy subjects, but not in those from glioma-bearing subjects. The two groups of subjects did not significantly differ in the number of cells bearing typical natural killer (NK) markers (both in resting and MP stimulated PBMC) and NK activity. However, interferon gamma (IFN-gamma) production was in tumour patients minimal or significantly reduced, as compared to healthy subjects, following PBMC stimulation by MP or phytohaemoagglutinin, respectively. In addition, minimal, if any, stimulation of interleukin-2 (IL-2) production was achieved in MP stimulated PBMC from glioma patients. Considering the pivotal role of the above cytokines in immune responses, particularly in those concerning generation of antitumour effectors, our results consistently suggest that defective cytokine production is one possible mechanism of immunological impairment in glioma patients. They also provide indirect support for a possible clinical use of IFN-gamma as an immunopotentiating agent in gliomatous subjects.

Immunotherapy of glioblastoma with intratumoural administration of autologous lymphocytes and human lymphoblastoid interferon. A further clinical study

A clinical trial of an immunotherapy which consisted of intratumoural injections of autologous lymphocytes with human lymphoblastoid interferon was evaluated in 31 patients with intracranial glioblastoma. Immunotherapy was performed after stereotactic biopsy or surgical resection. The treatment was tolerated well by all patients. Three patients showed positive response to immunotherapy as documented by transient regression or stabilization of the tumour size on computed tomography. Nevertheless, there is no significant difference in the survival time of the patients treated with immunotherapy and those not treated. We conclude that this immunotherapeutic regimen is not beneficial in patients with glioblastoma when used as single treatment after tumoural biopsy or resection.

Comparison of lymphokine-activated killer activities between thymocytes and splenocytes in rats with brain tumors

We studied the lymphokine-activated killer (LAK) activity in splenocytes and thymocytes of rats with brain tumors chronologically from the early stage to the late stage, in order to clarify how much LAK activity would be developed at each stage. Simultaneously the natural killer (NK) activity in splenocytes, as one aspect of the host immunocompetence, was also determined. The splenic NK activity was significantly depressed in rats with brain tumors during the 2nd and 3rd weeks after tumor transplantation, as compared with normal controls. On the other hand, the splenocytes incubated with interleukin-2 showed the same killer activity in rats with brain tumors as in normal rats at all times. The LAK activity in thymocytes from rats with brain tumors was significantly higher than that of controls in the 1st and 2nd weeks and became equal to that of the controls during the 3rd week. The killer activity after incubation with interleukin-2 in thymocytes was superior to that in splenocytes throughout the experiment in both tumor-bearing rats and controls, which suggested that the precursor of LAK cells was not NK cells.

Immunobiology of brain tumors

In summary, many actual interactions between tumors in the CNS and the immune system have been demonstrated. The normal brain does not possess a lymphatic system and is partially hidden from the systemic immune system by the BBB, furthermore brain cells do not express MHC antigens which are necessary for the initiation of an immune response. In pathological conditions however, immunocompetent cells may find their way through transformed endothelial cells. Microglia and astrocytes may function as antigen presenting cells. Glioma cells when stimulated by cytokines such as IFN gamma can be induced to express MHC class I and class II antigens, thus making them more susceptible to an immune attack. In addition glioma cells are capable of secreting several cytokines including IL 1, IL 3 and IL 6 also involved in the generation of an immune response. Indeed, a functional analysis of lymphocytes infiltrating gliomas has revealed the accumulation at the tumor site of cytotoxic T lymphocytes as well as NK cells. However host-immune responses against gliomas seem to be weak in comparison to other cancers. Glioma cells are known to secrete TGF beta 2 and PGE 2 which may in part be responsible for this lack of immune response, thus shielding themselves from immune attack. In order to be recognized by the immune system the tumor cells must express TAA in addition to MHC antigens, and such TAA have been identified by MAbs. These MAbs can be used for "targeted" therapy when coupled to toxic agents or radionuclides. Preclinical studies have shown that, after intravenous or intracarotid injection, there is specific accumulation of the MAb in the tumor but in insufficient amounts for therapeutic use. The relatively small amount of MAb binding to the tumor in vivo can be due to several factors: not all the cells in a single tumor express a given tumor-associated antigens, the MAb may have a low affinity for the antigen, the BBB may hinder the passage of the MAb. Attempts have been made to overcome these drawbacks by opening the BBB for example. In addition MAbs can readily be used for the treatment of carcinomatous meningitis. There has been little success in the development of immunotherapy with IFN beta 1 and even less with adoptive immunotherapy using LAK cells plus IL 2. TIL as well as LAK cells can be expanded in vitro with IL2 and it is feasible to reinject these cells into the tumor site.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunology of central nervous system tumors

With progress in cellular immunology and the development of hybridoma technology, the idea of manipulating host-tumor immune interactions to improve the prognosis of brain tumors has aroused renewed interest. Although no brain tumor-specific antigens have been found, and in spite of the wide antigenic heterogeneity of brain tumor cells, some monoclonal antibodies possessing restricted specificity have been isolated and their potential clinical applications investigated. One of the most pronounced changes in the cellular immune responses of brain tumor patients is a profound depression of the T4-helper lymphocytes. Clinical and laboratory trials are under way to assess the ability of lymphokines, such as gamma-interferon or interleukin-2, to restore immunologic competence in these patients and potentiate a specific anti-tumor immunologic response. Recent work suggests that the endothelium-astrocyte complex may have a pivotal role in assisting the escape of brain tumors from the host's immunologic responses, since it is responsible for the intracerebral sequestration of antigens and local anti-tumor responses. In this review, the data on the antigenic properties of central nervous system tumors and the host's humoral and cellular immune responses to them are analyzed and potential immunologic therapies are discussed.

Presence and significance of NK cells in glioblastomas

A monoclonal antibody against the surface marker IOT-10 of natural killer (NK) cells was used to investigate the presence of these cells in a series of 25 glioblastomas. In 40% of the tumors, IOT-10-positive NK cells were found in small numbers scattered among the tumor cells. The presence of IOT-10-positive NK cells was not related to the degree of lymphocytic infiltration in the tumor as demonstrated by hematoxylin and eosin staining, nor did it appear to influence the survival time of the patients studied.

Lymphokine-activated killer (LAK) activity against autologous malignant tumors of the skin

When peripheral blood mononuclear cells (PBMC) cultured with interleukin 2 (IL-2) develop the ability to lyse fresh tumor cells, such activity is referred to as lymphokine-activated killer (LAK) activity. In this paper, we examined LAK activity against the autologous skin tumors, malignant melanoma (MM), squamous cell carcinoma (SCC), and basal cell epithelioma (BCE), which have distinct clinical characteristics. Similar levels of LAK activity against Daudi 1A4, an NK resistant cell line were significantly obtained from all cancer patients. However, different levels of LAK activity against autologous tumor cells were found from three kinds of cancer patients using mixtures of autologous tumors and LAK. The levels of cytotoxicity were 29.8 +/- 7.0% in five MM, 15.9 +/- 4.9% in seven SCC, and 4.0 +/- 2.3% in five BCE patients at an effector/target ratio of 50/1. Allogeneic MM targets were lysed by LAK from all three types of cancer patients at similar levels, implying that LAK is not restricted to major histocompatibility complex (MHC) antigens. These results indicate that the levels of autologous LAK activity were significantly associated with the magnitude of clinical malignancy of the tumor targets, and suggested the selective lysis of tumor targets by LAK. NK activity of cancer patients bearing tumors was also examined prior to therapy. The levels of NK activity observed in MM patients were considerably lower than those in two other cancer patients.

Comparison of in vitro glioma cell cytotoxicity of LAK cells from glioma patients and healthy subjects

Peripheral blood mononuclear cells from 11 glioma patients and 11 healthy control subjects were cultured in medium containing recombinant interleukin-2 for a period of 5 days. The cytotoxicity of these lymphokine-activated killer (LAK) cells was tested on chromium-51-labeled freshly prepared allogeneic glioblastoma cells, and on the cell lines K562 (natural killer cell (NK)-sensitive) and Daudi (NK-resistant). Peripheral blood mononuclear cells from all subjects showed high levels of cytotoxicity against these targets. There was no significant difference between the patients and the control group when LAK cytotoxicity was compared. Thus, although glioma patients are known to have depressed immunological reactivity, the cytotoxic capacity of LAK cells derived from glioma patients is similar to that of LAK cells from healthy control subjects. However, the glioma patients had significantly reduced numbers of mononuclear cells in their peripheral blood, possibly due to steroid treatment. Therefore, the volume of blood required to generate the same number of LAK cells was approximately three times larger from the glioma patients than from control subjects.

Mononuclear cell infiltration in central portions of human astrocytomas

The mononuclear cell infiltration in the central portion of human low- and high-grade astrocytomas has been examined using monoclonal antibodies to cell surface differentiation antigens. There was no significant difference between the number of T cells, B cells, or macrophages. The OKT8+ (suppressor/cytotoxic) T cell population was the major lymphocyte subset in the infiltrates. There was, however, indirect evidence for a proportion of the total OKT8+ cells being natural killer cells. Overall, there was a significant difference in the number of macrophages compared to the total lymphoid cell population. Several cell types seem to play an equal role in the cellular and humoral immune response within the center of the tumors, as distinct from that occurring at the periphery.

Modulation of natural killer cytotoxicity by muramyl dipeptide and trehalose dimycolate incorporated in squalane droplets

The effect on natural killer (NK) cytotoxicity of splenic cells from BALB/c mice pretreated i.v. with squalane-in-water preparations of muramyl dipeptide (MDP), trehalose dimycolate (TDM), or the combination of MDP-plus-TDM was investigated. MDP or TDM augmented the NK cytotoxicity which peaked 48 h after the pretreatment whereas the combination of MDP and TDM induced an inhibition of the NK activity. Infection with influenza virus, a potent stimulator of NK cells, after the pretreatment with biological response modifiers resulted in a markedly enhanced NK activity on day 2 in MDP and control groups. Mice pretreated with TDM or the combination of MDP and TDM showed only moderate NK activity which peaked on day 3 after influenza infection. The NK activity was susceptible to asialo GM1 and complement treatment. The cytotoxicity of MDP-plus-TDM cells could be significantly enhanced after treatment with anti-macrophage monoclonal antibody and complement. NK activity induced by MDP or TDM was reduced by mixing MDP-plus-TDM cells. Addition of adherent cell-depleted MDP-plus-TDM suspension to MDP or TDM cells had a NK restorative effect. Splenic cells from mice pretreated 2 days earlier with MDP or TDM, but not MDP-plus-TDM, generated enhanced levels of luminol-dependent chemiluminescence.