Interferon- and STING-independent induction of type I interferon stimulated genes during fractionated irradiation

BACKGROUND

Improvement of radiotherapy efficacy requires better insight in the dynamic responses that occur during irradiation. Here, we aimed to identify the molecular responses that are triggered during clinically applied fractionated irradiation.

METHODS

Gene expression analysis was performed by RNAseq or microarray analysis of cancer cells or xenograft tumors, respectively, subjected to 3-5 weeks of 5 × 2 Gy/week. Validation of altered gene expression was performed by qPCR and/or ELISA in multiple cancer cell lines as well as in pre- and on-treatment biopsies from esophageal cancer patients ( NCT02072720 ). Targeted protein inhibition and CRISPR/Cas-induced gene knockout was used to analyze the role of type I interferons and cGAS/STING signaling pathway in the molecular and cellular response to fractionated irradiation.

RESULTS

Gene expression analysis identified type I interferon signaling as the most significantly enriched biological process induced during fractionated irradiation. The commonality of this response was confirmed in all irradiated cell lines, the xenograft tumors and in biopsies from esophageal cancer patients. Time-course analyses demonstrated a peak in interferon-stimulated gene (ISG) expression within 2-3 weeks of treatment. The response was accompanied by a variable induction of predominantly interferon-beta and/or -lambda, but blocking these interferons did not affect ISG expression induction. The same was true for targeted inhibition of the upstream regulatory STING protein while knockout of STING expression only delayed the ISG expression induction.

CONCLUSIONS

Collectively, the presented data show that clinically applied fractionated low-dose irradiation can induce a delayed type I interferon response that occurs independently of interferon expression or STING signaling. These findings have implications for current efforts that aim to target the type I interferon response for cancer treatment.

Slowdown intracranial glioma progression by optical hyperthermia therapy: study on a CT-2A mouse astrocytoma model

Metallic nanorods are promising agents for a wide range of biomedical applications. We report an optical hyperthermia method capable of inducing slowdown tumor progression of an experimental in vivo CT-2A glioblastoma tumor. The tumor model used in this research is based on the transplantation of mouse astrocytoma CT-2A cells in the striatum of mice by intracranial stereotaxic surgery. Two weeks after cell implant, the resulting tumor is treated by irradiating intratumoral injected gold nanorods, biofunctionalized with CD133 antibody (B-GNRs), using a continuous wave laser. Nanoparticles convert the absorbed light into localized heat (reaching up to 44 °C) due to the effect of surface plasmon resonance. A significant slowdown in CT-2A tumor progression is evident, by histology and magnetic resonance imaging, at one (p = 0.03) and two weeks (p = 0.008) after irradiation treatment. A notable deceleration in tumor size (15%-75%) as compared to the control untreated groups, it is observed. Thus, laser irradiation of B-GNRs is found to be effective for the treatment of CT-2A tumor progression. Similarities between the pre-clinical CT-2A tumor model and the human astrocytoma disease, in terms of anatomy, metastatic behavior and histopathology, suggest that hyperthermic treatment by laser irradiation of B-GNRs administered into high-grade human astrocytoma might constitute a promising alternative treatment to limit the progression of this deadly disease.

Proliferating Cell Nuclear Antigen (PCNA) in Low-Grade Astrocytomas: Its Prognostic Significance

Aims and background

A clear line cannot be drawn between well-differentiated and anaplastic astrocytomas, and a subset of low-grade tumors, histologically indistinguishable from the others, behaves similarly to anaplastic astrocytomas. The proliferative index could aid in the identification of this subgroup, for which a different therapeutic approach would be indicated.

Methods

We immunohistochemically evaluated the proliferating ceil nuclear antigen (PCNA) expression in 77 well-differentiated astrocytomas, since PCNA has been considered a good proliferation marker. The prognostic significance of PCNA labeling index (LI) was assessed in univariate and multivariate analysis, taking into consideration some clinical and histologic factors known to affect prognosis.

Results

PCNA immunostaining identified a subgroup of tumors, characterized by a LI > 5%, with a median survival close to that observed in anaplastic astrocytomas. The survival table of such a group was significantly different from that of the group with a lower LI (p = 0.0009). Multivariate analysis confirmed that PCNA-LI is an independent prognostic factor (p = 0.001).

Conclusion

These data suggest that PCNA immunostaining can be a useful tool to define the prognosis of low-grade astrocytomas on routine biopsy material.

Frequency and Significance of Lymphoplasmocyte Infiltration in Human Gliomas

The problem of lymphocyte infiltration is studied in 190 operated gliomas and in 35 glioma recurrences. The tumors were classified in 4 groups: no infiltrations (0), infiltrations in a single focus (I), in several foci (II) and extra-adventitial infiltrations (III). 51.59 % of all the gliomas examined were positive for infiltrations, most of them belonging to groups I and II. Plasmacells were found in many group II and group III cases. Lymphoplasmocyte infiltration was considerably increased in group II and group III cases. Cases with such an increase were reoperated within 5 months of the first operation. The findings are discussed in relation to the immunology of tumors and of the nervous system. The increased lymphocyte infiltration in glioma recurrences is attributed to the breakdown of the blood-brain barrier that occurred in the first operation. Lymphocyte infiltration is related to a host defence mechanism against tumors.

Direct and indirect pro-inflammatory cytokine response resulting from TC-83 infection of glial cells

Venezuelan equine encephalitis virus (VEEV) is a neurotropic arbovirus that is highly infectious as an aerosol and can result in an encephalitic phenotype in infected individuals. VEEV infections are known to be associated with robust inflammation that eventually contributes to neurodegenerative phenotypes. In this study, we utilize the TC-83 strain of VEEV, which is known to induce the expression of IL-6, IL-8, and other pro-inflammatory cytokines. We had previously demonstrated that TC-83 infection resulted in changes in mitochondrial function, eventually resulting in mitophagy. In this manuscript, we provide data that links upstream mitochondrial dysfunction with downstream pro-inflammatory cytokine production in the context of microglia and astrocytoma cells. We also provide data on the role of bystander cells, which significantly contribute to the overall inflammatory load. Use of a mitochondrial-targeted antioxidant, mitoquinone mesylate, greatly reduced the inflammatory cytokine load and ameliorated bystander cell inflammatory responses more significantly than a broad-spectrum anti-inflammatory compound (BAY 11-7082). Our data suggest that the inflammatory mediators, especially IL-1β, may prime naïve cells to infection and lead to increased infection rates in microglial and astrocytoma cells. Cumulatively, our data suggest that the interplay between mitochondrial dysfunction and inflammatory events elicited in a neuronal microenvironment during a TC-83 infection may contribute to the spread of infection.

Evaluation of guggulipid and nimesulide on production of inflammatory mediators and GFAP expression in LPS stimulated rat astrocytoma, cell line (C6)

AIM OF THE STUDY

The present study was designed to investigate effect of guggulipid, a drug developed by CDRI and nimesulide on LPS stimulated neuroinflammatory changes in rat astrocytoma cell line (C6).

MATERIALS AND METHODS

Rat astrocytoma cells (C6) were stimulated with LPS (10 microg/ml) alone and in combinations with different concentrations of guggulipid or nimesulide for 24h of incubation. Nitrite release in culture supernatant, ROS in cells, expressions of COX-2, GFAP and TNF-alpha in cell lysate were estimated.

RESULTS

LPS (10 microg/ml) stimulated C6 cells to release nitrite, ROS generation, up regulated COX-2 and GFAP expressions at protein level and TNF-alpha at mRNA level. Both guggulipid and nimesulide significantly attenuated nitrite release, ROS generation and also down regulated expressions of COX-2, GFAP and TNF-alpha. Guggulipid and nimesulide per se did not have any significant effect on C6 cells.

CONCLUSION

Results demonstrate the anti-inflammatory effect of guggulipid comparable to nimesulide which suggest potential use of guggulipid in neuroinflammation associated conditions in CNS disorders.

Immunobiological and experimental aspects of malignant astrocytoma

Today several findings indicate that a multifactorial strategy is the best strategy for treating cancer. Although radiotherapy, chemotherapy and surgery have been differently applied to treat human gliomas, no substantial improvement in life expectancy has been observed. Starting from 1992, the goal of our studies was to obtain new biological data on malignant astrocytomas to better understand the basic biology of the tumour and these are reviewed here. Immunotherapy may represent an available method in addition to the traditional therapeutic approaches. Starting from 1991, we set up a cellular model of lymphocytes obtained from peripheral blood of healthy patients treated with interleukin-2 (IL-2) in order to study the role of IL-2 in regulating lymphocytes activation. The lymphocytes responding to IL-2 treatment, named lymphokine-activated killer (LAK) cells, have a killer non MHC restricted activity, and are able to kill autologous and allogenic glioma cells. The interaction of LAK cells with various normal and transformed targets indicates that LAK cells recognize surface structures present both on normal and transformed cells. However, only the interaction with transformed cells induces lytic events and LAK cells can act as "surgical weapons" against tumour cells independently from their cell cycle. Much recent effort has focused on identifying the immune escape mechanisms used by glioma cells, in particular the modulation of the human leukocyte antigen (HLA) and antigen processing machinery component expression. Finally, another interesting field of research that will be presented is that of new tumour biomarkers of proliferation and apoptosis, cytokine/chemokine release and cytokine/chemokine receptors.

Fas ligand expression in glioblastoma cell lines and primary astrocytic brain tumors

Fas/APO-1 (CD95) is a cell surface receptor that mediates apoptosis when it reacts with Fas ligand (FasL) or Fas antibody. We previously reported that Fas expression is predominantly induced in perinecrotic glioma cells, suggesting that Fas induction is associated with apoptosis and necrosis formation, a histological hallmark of glioblastomas. In this study, we assessed the expression of FasL in 10 glioblastoma cell lines and in 14 astrocytic brain tumors (three low-grade astrocytomas and 11 glioblastomas). Reverse transcriptase (RT)-PCR revealed that all glioblastoma cell lines and primary astrocytic brain tumors express FasL. Immunohistochemically, FasL was predominantly expressed on the plasma membrane of glioma cells. These results suggest that FasL expression is common in human astrocytic brain tumors and may cause apoptosis of glioma cells if Fas expression is induced.

Gamma-aminobutyric acid inhibits synergistic interleukin-6 release but not transcriptional activation in astrocytoma cells

OBJECTIVE

A decline in the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) may enhance cytokine release in Alzheimer's disease (AD) resulting in neuroinflammation. We investigated the GABA-mediated suppression of the synergistic release of interleukin (IL)-6 due to interleukin 1-beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha).

METHODS

Rat C6 astrocytoma cells were treated with IL-1 beta and TNF-alpha in the absence and presence of GABA. Activation of p38, degradation of I kappaB-alpha and total cellular IL-6 were determined by Western blot analysis. IL-6 release and gene expression were measured by ELISA and RT-PCR, respectively.

RESULTS

Although p38 and nuclear factor (NF)-kappaB are essential for the synergistic release of IL-6, GABA did not affect either p38 phosphorylation or I kappaB-alpha degradation. Additionally, GABA suppressed IL-6 release but did not alter cytokine-driven synergistic increases in IL-6 gene expression. Western blot analysis revealed that co-treatments with IL-1 beta and TNF-alpha resulted in an increase in intracellular IL-6 that was prevented by GABA.

CONCLUSION

GABA-induced inhibition of IL-6 release appears to coincide with a reduction in cellular IL-6. The GABA-induced suppression of IL-6 release may include inhibition of IL-6 gene translation.

WHO grade associated downregulation of MHC class I antigen-processing machinery components in human astrocytomas: does it reflect a potential immune escape mechanism?

Defects of major histocompatibility complex (MHC) class I antigen-processing machinery (APM) components have been shown to contribute to immune escape of malignant cells. We investigated the expression of APM components in astrocytomas without detectable defects in HLA class I antigen expression and correlated it with grade of malignancy. Quantitative immunohistochemical analysis of astrocytomas revealed reduced expression of the cytosolic proteasome subunit low molecular weight protein 2 (LMP2), the endoplasmatic reticulum (ER) transporter associated with antigen processing-1 (TAP1), and the ER chaperone beta2-microglobulin (beta2m) in astrocytoma cells when compared to astrocytes from nonpathological brain. Among human WHO grade II-IV astrocytomas, downregulation of LMP2, TAP1 and beta2m correlated with grade of malignancy. Furthermore, astrocytoma cell lines (n = 12) expressed all APM components analyzed at levels comparable to dendritic cells (DC), which were used for comparative purposes. However, upregulation of beta2m after stimulation with inflammatory cytokines was significantly lower in astrocytoma cell lines than in control cells. Our results support the hypothesis that coordinated downregulation or impaired upregulation of certain HLA class I APM components may serve as a mechanism for astrocytoma cells to evade the host's immune response, even if HLA class I antigen surface expression is not altered.

Expression of interleukin-16 by tumor-associated macrophages/activated microglia in high-grade astrocytic brain tumors

Introduction

Macrophages/microglial cells are considered as immune cells in the central nervous system. Interleukin (IL)-16 is a proinflammatory cytokine produced by activated monocytic cells.

Materials and Methods

Expression of IL-16 was analyzed by immunohistochemistry in human astrocytic brain tumors and the rat C6 glioblastoma tumor model. IL-16 was detected in both human astrocytic brain tumors and rat C6 glioma.

Results

Compared with human control brains, a significant increase in the percentages of parenchymal IL-16⁺ macrophages/microglia was observed already in grade II astrocytomas, indicating that IL-16⁺ immunostaining could be a descriptor of a macrophage/microglia subset in astrocytic brain tumors. A further increase was observed at the transition from grade II to III astrocytomas. This increase in IL-16 immunoreactivity correlated with WHO grades of human astrocytic brain tumors.

Conclusions

Therefore, IL-16 might be a so far unknown factor in the regulation of the local inflammatory milieu of human and experimental astrocytomas.

Th1/Th2 cytokine imbalance in meningioma, anaplastic astrocytoma and glioblastoma multiforme patients

The balance between Th1 and Th2 cytokines is thought to be an important factor in terms of tumour prognosis. Serum samples from 61 newly diagnosed patients with brain tumours and 50 age- and sex-matched non-tumour controls were analysed by ELISA for circulating levels of interleukin-12 (IL-12p70 and p40) and interleukin-10 (IL-10); pivotal Th1 and Th2 cytokines, respectively. Patients were divided into various groups depending on their histological diagnosis: meningioma (n=11), anaplastic astrocytoma (n=4) and glioblastoma multiforme (GBM; n=46). Significant reduction in serum IL-12 was seen in all groups as compared with the controls: meningioma, p=0.03; anaplastic astrocytoma, p<0.001; and GBM, p<0.001. Conversely, serum IL-10 was significantly increased in anaplastic astrocytoma, p=0.02, and GBM, p=0.03. The changes in the serum cytokines were not caused by the effects of steroids, as sequential analysis of patients pre- and post-steroid treatment commencement showed no difference. This study shows that patients with advanced primary intracranial malignancies have decreased circulating IL-12 and increased circulating IL-10, demonstrating that brain tumours have a major systemic effect on the immune system.

[Glial tumors of the brain: current aspects of their classification and bases for genetic predisposition]

Gliomas are the most common tumors of the central nervous system (CNS). Malignant astrocytic gliomas account for 50% of all primary brain tumors. Cells of origin are unknown for the majority of brain tumors: CNS tumors have frequently in their content many histological forms and their classification will depend on what the parts of neoplasm that will be clearly identified at the material taking and further investigation. Current immunohistochemical studies may determine the antigenic structure of a tumor cell, compare it with the antigens expressed by a certain cell type and, thus, classify the tumor by its origin, but there are no antibodies which would correctly identify different types of tumors. The lecture reflects the current classifications of glial tumors: the typical three-leveled classification, the Kernokhan classification, the Duma-Duport classification. A part of the lecture deals with the specific features of genetics and molecular biology of gliomas: recent studies cast any doubt on the existing data on the sources of growth of these tumors.

Genetic analysis of intracranial tumors in a murine model of glioma demonstrate a shift in gene expression in response to host immunity

For the study of malignant glioma, we have previously characterized a highly tumorigenic murine astrocytoma, SMA-560, which arose spontaneously in an inbred, immunocompetent VM/Dk mouse. Using this cell line as a model of murine glioma, we performed DNA microarray analysis of autologous normal murine astroctyes (NMA) and SMA-560 tumor cells grown in monolayer culture or intracranially in syngeneic immunocompetent or immunocompromised hosts in order to determine whether tumors grown in vitro recreate the complex genetic regulation that occurs in vivo. Our findings support our hypothesis that glioma phenotype in vitro may be quite different in vivo and significantly altered by in situ growth factors and other invading cell populations.

A sequential scanning of the immune efficiency in astrocytoma (Grade I to Grade Iii), meningioma and secondary glioma patients with and without therapeutic scheduling

PURPOSE

Glioma induces immune suppression. However, data revealing the immune status in glioma patients with sequential therapeutic interventions is missing. Thus, the study aims at evaluating the sequential immune status of glioma bearing patients (Astrocytoma Grade I to Grade III) receiving conventional therapeutic measures. The results were compared with the immune status of metastatic secondary glioma and meningioma patients where there is minimal immune suppression and the effect of therapeutic intervention on the above score.

METHODS

Functional immune parameters of peripheral blood lymphocytes were assayed by CD2 receptors enumeration through E-rosetting and lymphocyte cytotoxicity assay and assessing the generation of reactive oxygen species by NBT assay of peripheral blood macrophages in patient groups bearing Astrocytoma (Grade I to Grade III), meningioma and secondary glioma.

RESULTS

Patients bearing Astrocytoma (all 3 grades) showed maximum immune suppression as compared to the normal subjects, diseased meningioma controls, and secondary glioma. Therapeutic interventions viz. radiotherapy, surgery and radiotherapy after surgery and chemotherapy could not recover the suppressed activity of the CD2 bearing lymphocytes and that of peripheral blood macrophages. However, therapeutic scheduling could recover the functional activity of the CD8 bearing lymphocytes and the CD56 NK cells from that of tumor bearing patients.

CONCLUSION

Astrocytoma and not meningioma is capable of causing immunesuppression. As the tumor progresses from Grade I to Grade III, a linear reduction in the functional efficacy of immunocytes is seen to occur. Radiotherapy, surgery, and chemotherapy also induces an inhibitory effect towards the host immune system. The inhibitory effect of tumor as well as of therapy were mainly directed towards the CD2 bearing lymphocyte population and the peripheral blood macrophage population.

Expression of MHC I and NK ligands on human CD133+ glioma cells: possible targets of immunotherapy

Mounting evidence suggests that gliomas are comprised of differentiated tumor cells and brain tumor stem cells (BTSCs). BTSCs account for a fraction of total tumor cells, yet are apparently the sole cells capable of tumor initiation and tumor renewal. BTSCs have been identified as the CD133-positive fraction of human glioma, whereas their CD133-negative daughter cells have limited proliferative ability and are not tumorogenic. It is well established that the bulk tumor mass escapes immune surveillance by multiple mechanisms, yet little is known about the immunogenicity of the CD133-positive fraction of the tumor mass. We investigated the immunogenicity of CD133-positive cells in two human astrocytoma and two glioblastoma multiforme samples. Flow cytometry analyses revealed that the majority of CD133-positive cells do not express detectable MHC I or natural killer (NK) cell activating ligands, which may render them resistant to adaptive and innate immune surveillance. Incubating CD133-positive cells in interferon gamma (INF-gamma) significantly increased the percentage of CD133-positive cells that expressed MHC I and NK cell ligands. Furthermore, pretreatment of CD133-positive cells with INF-gamma rendered them sensitive to NK cell-mediated lysis in vitro. There were no consistent differences in immunogenicity between the CD133-positive and CD133-negative cells in these experiments. We conclude that CD133-posistive and CD133-negative glioma cells may be similarly resistant to immune surveillance, but that INF-gamma may partially restore their immunogenicity and potentiate their lysis by NK cells.

Systematic immunohistochemical profiling of 378 brain tumors with 37 antibodies using tissue microarray technology

We performed a systematic immunohistochemical study on 378 brain tumors using 37 antibodies and tissue microarray (TMA) technology. The aim of this study was to find new diagnostic biomarkers using antibodies established in our laboratory. Our TMA consisted of a grid of 1.5-mm cores that were extracted from individual donor blocks. Staining for each antibody was scored using a three-point system. We used hierarchical clustering analysis to interpret these data, which resulted in separation of all the brain tumors into seven groups. Although there were some exceptions, cases with the same histological diagnosis were generally grouped together. We then carried out statistical analyses to find the most useful antibodies for grouping of brain tumors. Ten antibodies [glial fibrillary acidic protein (GFAP), Olig2, vimentin, epithelial membrane antigen (EMA), cytokeratin (AE1/AE3), alpha-internexin, nestin, pinealocytes PP5, aquaporin-4 (AQP4) M13d and AQP4M13e] discriminated between astrocytomas and oligodendroglial tumors. Six antibodies [EMA, AE1/AE3, TUJ1, nestin, neurofilament protein-MH (NF-MH) and perivascular cells GP-1] showed significant differences between high-grade and low-grade gliomas. Our data have revealed new antibodies with potential diagnostic utility (Olig2, PP5, GP-1) and demonstrate that TMA technology is highly useful for evaluating newly established antibodies in brain-tumor research.

Microwave-assisted antigen retrieval and incubation with cox-2 antibody of archival paraffin-embedded human oligodendroglioma and astrocytomas

Immunohistochemistry is an important tool that is often used for the diagnosis of pathologies; however, the length of time required to process the tissue is relatively long. Furthermore, the quality and sensitivity of immunohistochemical staining is affected by formalin fixation which results in variable loss of antigenicity, known as masking effect. Here we assess the effect of microwave irradiation on the incubation time required to obtain high quality immunohistochemical staining for cox-2 using archival formalin-fixed, paraffin-embedded human oligodendrogliomas and astrocytomas. The results show that intermittent microwave irradiation during the incubation with the primary antibody reduced the time requirement to 5 min while the staining quality was indistinguishable from 1 or 24 h long incubations. Thus, the use of this procedure results in a significant saving of time which is important for a timely diagnosis of pathological conditions that await treatment.

131I-chTNT-1/B mAb: tumour necrosis therapy for malignant astrocytic glioma

Treatment of malignant glioma is therapeutically challenging. Despite improvements in neurosurgery, radiotherapy and chemotherapy, few patients diagnosed with anaplastic astrocytoma (AA) or glioblastoma multiforme (GBM) (WHO grades 3 and 4, respectively) will live beyond 2 years. Poor survival is due to the highly invasive nature and protected location of these tumours. Most malignant gliomas cannot be completely resected or irradiated due to their ability to infiltrate diffusely into normal brain tissue. Brain tissue is protected from the systemic circulation via the blood-brain barrier (BBB), which impedes entry of water-soluble chemotherapeutic agents into the tumour at therapeutic concentrations. (131)I-chTNT-1/B mAb (Cotara) employs an innovative strategy to treat the invasive portion of the tumour and the core lesion. (131)I-chTNT-1/B mAb is a genetically engineered, radiolabelled, chimeric monoclonal antibody specific for a universal intracellular antigen (i.e., DNA/histone H1 complex) exposed in the necrotic core of malignant gliomas. This antigen provides an abundant, insoluble, non-diffusible anchor for the mAb. Once localised to necrotic regions of the tumour, (131)I-chTNT-1/B mAb delivers a cytotoxic dose of (131)I radiation to the core lesion. (131)I-chTNT-1/B mAb is delivered via convection-enhanced delivery in order to maximise coverage to the tumour and the invasive front of the glial tumour. The clinical experience to date with (131)I-chTNT-1/B mAb is presented.

Soluble factors released by virus specific activated cytotoxic T-lymphocytes induce apoptotic death of astroglioma cell lines

Astrocytomas and astrogliomas represent the most common types of primary tumors in human central nervous system and are associated with high mortality due to the absence of efficient therapy. Here we demonstrate that, upon antigen-specific activation, cytotoxic T-lymphocytes (CTLs) secrete products that inhibit proliferation and induce apoptosis in a significant proportion of astroglioma cell lines. This effect is tumor specific in that normal cultured astrocytes do not develop apoptotic changes upon exposure to supernatant of activated CTLs. Experiments with purified lymphokines and lymphokine specific blocking antibodies indicate that synergistic activities of tumor necrosis factor (TNF)-alpha and interferon (INF)-gamma are required for the apoptosis inducing effect on some astroglioma cell lines. However, this effect appears to be dependent on additional factors produced by activated CTLs. Our results suggest that local application of factors released by activated CTLs or induction of CTL migration and activation in the tumor site may have a therapeutic effect in patients with astrogliomas.

Immunohistochemical detection of dUTPase in intracranial tumors

The nuclear isoform of deoxyuridine 5'-triphosphate nucleotidohydrolase (dUTPase, OMIM *601266, EC 3.6.1.23) is immunohistochemically detectable in all proliferating tissues and may thus be a useful adjunct for the grading of tumors analogous to Ki-67 labeling. A hundred and twenty-seven human intracranial tumors, including 56 astrocytomas, 12 oligodendrogliomas, 8 oligoastrocytomas, 34 meningiomas, 7 ependymomas, and 10 metastatic carcinomas, were stained using the monoclonal rat anti-human dUTPase antibody (clone 3E6) with formalin-fixed and paraffin-embedded tissue. The labeling indices were compared with those obtained with the proliferation marker Ki-67 on parallel tissue sections. All tumors contained dUTPase-positive nuclei, whereas the percentage of positive tumor cells generally increased with grade of malignancy. Meningiomas of higher grades, i.e., World Health Organization (WHO) grades II and III, contained additional cells with cytoplasmic reactivity. There were usually fewer dUTPase- than Ki-67-positive nuclei detectable. Unlike Ki-67, dUTPase was not detectable in mitotic figures. Labeling indices for dUTPase, but not for Ki-67, showed significant differences between all 3 WHO grades of diffuse astrocytomas. In summary, dUTPase staining provides a useful measure of cell proliferation distinct from that offered by Ki-67 labeling. It proved particularly useful for the evaluation of diffuse astrocytomas.

Altered Expression of Immune Defense Genes in Pilocytic Astrocytomas

Pilocytic astrocytoma (WHO grade I) is a circumscribed, slowly growing, benign astrocytoma that most frequently develops in the cerebellar hemispheres and in midline structures and occurs predominantly in childhood and adolescence. In contrast to diffusely infiltrating gliomas in adults (e.g. grade II astrocytomas, oligodendrogliomas), survival of patients with pilocytic astrocytoma is excellent after surgical intervention. To search for potential molecular mechanisms underlying its benign biologic behavior, we compared gene expression profiles of pilocytic astrocytomas (8 cases) with those of normal cerebellum (4 cases), low-grade astrocytomas (WHO grade II; 15 cases), and oligodendrogliomas (WHO grade II; 17 cases) by cDNA array analysis. A number of immune system-related genes such as HLA-DRalpha, HLA-DPB1, HLA-DQB1, IgG3, IgGK, FCER1G, A2M, FCRN, IFI-56K, and DAP12 were upregulated in pilocytic astrocytomas relative to normal cerebellum, grade II astrocytomas, and oligodendrogliomas. Genes expressed at higher levels in pilocytic astrocytomas than in grade II astrocytomas and oligodendrogliomas include HLA-DRalpha, HLA-DPA1, HLA-DPB1, HLA-DQB1, A2M, TIMP1, TIMP2, CDKN1A, and SOCS3 and those expressed at lower levels include EGFR and PDGFRA. Hierarchical clustering analysis using the entire set of 1176 genes distinguished pilocytic astrocytomas from grade II astrocytomas and oligodendrogliomas. Clustering analysis using selected subgroups of genes based on their molecular functions revealed that immune system-related genes (75 genes) or cell adhesion, migration, and angiogenesis-related genes (69 genes) showed similar power to the entire gene set for separation of pilocytic astrocytomas from diffusely infiltrating low-grade gliomas. Immunohistochemistry revealed that HLA-DRalpha is expressed diffusely in neoplastic cells in pilocytic astrocytomas, whereas in oligodendrogliomas, expression was limited to scattered reactive astrocytes. These results suggest that gene expression profiles of pilocytic astrocytomas differ significantly from those of diffusely infiltrating low-grade gliomas and that their benign biologic behavior may be related to upregulation of immune defense-associated genes.

The expression of the epitope H recognized by the monoclonal antibody H is higher in astrocytomas compared to anaplastic astrocytomas and glioblastomas

The epitope H contains an O-linked N-acetylglucosamine residue in a specific conformation and/or environment recognized by the monoclonal antibody H (mAbH). mAbH stains two bands with Mr x0.001 of 209 and 62 in lysates of cultured rat astrocytes. In normal human brains epitope H is absent from the overwhelming majority of normal astrocytes and only sparse reactivity is observed, confined mostly to fibrous astrocytes. Upregulation of the epitope H takes place in reactive astrocytes. In the present study we used the mAbH to investigate the immunohistochemical expression of the epitope H in 41 cases of astrocytic tumors including 19 cases of astrocytomas, 8 cases of anaplastic astrocytomas and 14 cases of glioblastomas. Seven out of 19 cases (37%) of astrocytomas showed weak staining, 10 cases (53%) moderate staining and 2 cases (10%) intense staining. Two out of 8 cases (25%) of anaplastic astrocytomas appeared negative, 3 cases (37.5%) showed weak staining and 3 cases (37.5%) moderate staining. Four out of 14 cases (28.5) of glioblastomas appeared negative, 7 cases (50%) showed weak staining, 2 cases (14%) showed moderate staining and only one case (7.5%) showed intense staining. There was a statistically significant elevation of the expression of the epitope H in astrocytomas compared to anaplastic astrocytomas and glioblastomas (p=0.047). These results indicate that the expression of the epitope H decreases in parallel with the increase of the grade of astrocytic tumors from low to higher grade neoplasms. This could be of interest for predicting the progression of an astrocytic tumor since it is documented that astrocytomas progress to tumors of higher grade of malignancy. Further investigation of the antigens bearing the epitope H might help to gain further insight into the mechanisms which regulate the progression of astrocytic tumors and to examine the relevance of the mAbH staining with respect to the prognosis of these neoplasms.

The utility of MIB-1/Ki-67 immunostaining in the evaluation of central nervous system neoplasms

The diagnosis and assignment of grade in neoplasms of the central nervous system (CNS), for the most part, are morphologically based and predicated on the interpretation of descriptions of what the phenotypic findings are for a particular tumor type. Not surprisingly, the application of various grading systems in CNS neoplasia has been limited somewhat by interobserver variability. Since assignment of grade and tumor type is the basis upon which therapeutic intervention is grounded, investigators have been searching for ancillary means by which morphologically based systems can be improved. Utilization of cell proliferation markers in the evaluation of tumors can be potentially useful in this endeavor. This review focuses on issues surrounding the utilization of MIB-1 or Ki-67 antibody in the evaluation of CNS neoplasms.

Effect of human cytomegalovirus on expression of MHC class I-related chains A

The MHC-encoded MHC class I-related chains A (MICA) glycoproteins are known to enhance the functions of NK and T cells by ligating the stimulating receptor NKG2D and appear to play an important role in host defense. Human CMV (HCMV) evades the immune response in many different ways, but has not previously been found to down-regulate MICA. We have found that a common form of MICA, which has a nucleotide insertion in exon 5 corresponding to the transmembrane region and no cytoplasmic tail, was increased on the surface of fibroblasts HFS-13 compared with the mock-infected sample of the same cells that had been cultured to confluence. However, an astrocytoma cell line, U373, which has a full-length variant of MICA, showed that the expression of MICA was decreased after HCMV infection. Retroviral transduction of different MICA alleles into fibroblasts HFF-D, which express no MICA of their own, established that full-length MICA was down-regulated by HCMV, and the truncated form was not. Fibroblasts with decreased MICA due to HCMV infection were found to be protected from NK cell killing, whereas in the presence of the truncated form of MICA, the virus-infected cells were destroyed. Thus, the truncated form of MICA, which is the most common, has a mutation that allows it to persist on the surface and hinder efforts of the virus to evade the immune response.

Proteomic characterization of harvested pseudopodia with differential gel electrophoresis and specific antibodies

Malignant gliomas (astrocytomas) are lethal tumors that invade the brain. Invasive cell migration is initiated by extension of pseudopodia into interstitial spaces. In this study, U87 glioma cells formed pseudopodia in vitro as cells pushed through 3 microm pores of polycarbonate membranes. Harvesting pseudopodia in a novel two-step method provided material for proteomic analysis. Differences in the protein profiles of pseudopodia and whole cells were found using differential gel electrophoresis (DIGE) and immunoblotting. Proteins from two-dimensional (2D) gels with M(R)'s of 20-100 kDa and pI's of 3.0-10.0 were identified by peptide mass fingerprinting analysis using mass spectrometry. For DIGE, lysates of pseudopodia and whole cells were each labeled with electrophilic forms of fluorescent dyes, Cy3 or Cy5, and analyzed as mixtures. Analysis was repeated with reciprocal labeling. Differences in protein distributions were detected by manual inspection and computer analysis. Topographical digital maps of the scanned gels were used for algorithmic spot matching, normalization of background, quantifying spot differences, and elimination of artifacts. Pseudopodial proteins in Coomassie-stained 2D gels included isoforms of glycolytic enzymes as the largest group, seven of 24 proteins. Peptide mass fingerprint analysis of DIGE gels demonstrated increased isoforms of annexin (Anx) I, AnxII, enolase, pyruvate kinase, and aldolase, and decreased mitochondrial manganese superoxide dismutase and transketolase in pseudopodia. Specific antibodies showed restricted immunoreactivity of the hepatocyte growth factor (HGF) alpha chain to pseudopodia, indicating localization of its active form. Met (the HGF receptor), actin, and total AnxI were increased in pseudopodial lysates on immunoblots. Increased constituents of the pseudopodial proteome in glioma cells, identified in this study as actin, HGF, Met, and isoforms of AnxI, AnxII, and several glycolytic enzymes, represent therapeutic targets to consider for suppression of tumor invasion.

Minichromosome maintenance protein 3 elicits a cancer-restricted immune response in patients with brain malignancies and is a strong independent predictor of survival in patients with anaplastic astrocytoma

PURPOSE

The identification of new molecular markers in astrocytic tumors may help to understand the biology of these tumors in more detail. Informative tumor markers may represent prognostic factors for response to therapy and outcome as well as potential targets for novel anticancer therapies.

EXPERIMENTAL DESIGN

Tumor-associated antigens were identified by immunoscreening of a human glioma cDNA expression library with allogeneic sera from patients with diffuse astrocytoma (WHO grades 2-4). The expression of one of the identified antigens, the replication licensing factor minichromosome maintenance protein 3 (MCM3), was analyzed by immunohistochemistry in 142 primary and 27 recurrent astrocytomas (WHO grades 2-4). In addition, 98 serum specimens from patients with primary and secondary brain malignancies and 30 serum specimens from healthy controls were examined by serologic immunoscreening for immunoreactivity with MCM3.

RESULTS

MCM3 is overexpressed in human astrocytic tumors and elicits a cancer-restricted humoral immune response in 9.3% (9 of 97) of patients with brain tumors (n = 95) and brain metastases (n = 2) but not in healthy controls. Expression of MCM3 in diffuse astrocytoma is significantly associated with age (P < 0.001), histologic grade (P < 0.001), time to recurrence (P = 0.01), and expression of the proliferation marker Ki-67 (P < 0.001) but not with sex (P = 0.800). Univariate and multivariate Cox regression analysis confirmed MCM3 expression as an independent predictor of poor outcome in astrocytoma patients (P < 0.001 for both).

CONCLUSIONS

MCM3 may represent a glioma-associated antigen with significant prognostic role as well as have some potential as a target for cancer-directed therapy.

[Glial tumors of the brain: classification, present-day aspects of immunopathogenesis and immunogenetic diagnostics]

Glial tumors of the brain present a complicated problem in neurosurgery due to the peculiarities of their growth biology, their prevalence, infiltrative growth and diagnostic difficulties. The complexity of treatment, which includes surgical removal of a tumor, radiotherapy, chemotherapy, and immune correction, makes the problem even more topical. Modem classification of glial neoplasms is of no less importance, because treatment depends on the histologic structure of a tumor. Thereupon, the authors of the article pay special attention to the modem WHO classification of gliomas. As immune diagnostics and treatment are indispensable in modern neurooncology, application of neurospecific oncologic markers is being widely introduced into clinical and scientific practice in many scientific centers. However, there are no objective tests to verify the diagnosis of astrocytic glioma with reliable accuracy. Hereditary syndromes associated with glial tumors have been distinguished and are being studied. The most interesting and promising direction is research into genetic anomalies in patients with glial processes.

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.

Vaccination with Tumor Lysate-Pulsed Dendritic Cells Elicits Antigen-Specific, Cytotoxic T-Cells in Patients with Malignant Glioma

The primary goal of this Phase I study was to assess the safety and bioactivity of tumor lysate-pulsed dendritic cell (DC) vaccination to treat patients with glioblastoma multiforme and anaplastic astrocytoma. Adverse events, survival, and cytotoxicity against autologous tumor and tumor-associated antigens were measured. Fourteen patients were thrice vaccinated 2 weeks apart with autologous DCs pulsed with tumor lysate. Peripheral blood mononuclear cells were differentiated into phenotypically and functionally confirmed DCs. Vaccination with tumor lysate-pulsed DCs was safe, and no evidence of autoimmune disease was noted. Ten patients were tested for the development of cytotoxicity through a quantitative PCR-based assay. Six of 10 patients demonstrated robust systemic cytotoxicity as demonstrated by IFN-gamma expression by peripheral blood mononuclear cells in response to tumor lysate after vaccination. Using HLA-restricted tetramer staining, we identified a significant expansion in CD8+ antigen-specific T-cell clones against one or more of tumor-associated antigens MAGE-1, gp100, and HER-2 after DC vaccination in four of nine patients. A significant CD8+ T-cell infiltrate was noted intratumorally in three of six patients who underwent reoperation. The median survival for patients with recurrent glioblastoma multiforme in this study (n = 8) was 133 weeks. This Phase I study demonstrated the feasibility, safety, and bioactivity of an autologous tumor lysate-pulsed DC vaccine for patients with malignant glioma. We demonstrate for the first time the ability of an active immunotherapy strategy to generate antigen-specific cytotoxicity in brain tumor patients.

Lymphokine activated killer cells from umbilical cord blood show higher antitumor effect against anaplastic astrocytoma cell line (U87) and medulloblastoma cell line (TE671) than lymphokine activated killer cells from peripheral blood

OBJECTS

The aims of this study were to assess the cytotoxic capability of lymphokine-activated killer (LAK) cells from umbilical cord blood (UCB), to compare them with those of peripheral blood (PB)-derived cells against anaplastic astrocytoma cell line (U87) and medulloblastoma cell line (TE671), and to identify which mechanism and genes were involved in cytotoxicity.

METHODS

The effector cells were generated by interleukin-2 from UCB and PB. The antitumor property of effector cells against the target cells (U87, TE671) were estimated using a visual survival cell assay. The mixed target and effector (UCB) cells were analyzed for whether DNA fragmentation was present or not. Reverse transcription polymerase chain reaction analysis was then performed to estimate the statement of the perforin and FasL genes in activated and inactivated cells from UCB.

RESULTS

The higher in vitro antitumor properties of the LAK cells from UCB were observed in comparison to the LAK cells from PB against the U87 and the TE671 ( p<0.05). Apoptosis may be one of the lysis mechanisms of target cells by the LAK cells from UCB. The contributing genes could be FasL and perforin.

CONCLUSIONS

This study suggests that UCB may be used as a source of LAK cells in adults and children suffering from anaplastic astrocytoma or medulloblastoma.

Expression of macrophage/histiocytic antigens in pleomorphic xanthoastrocytomas

Pleomorphic xanthoastrocytoma (PXA) is a rare variant of a superficial cerebral astrocytoma characterised by distinct clinical and histological features. Its derivation from subpial astrocytes has been proposed, although the capacity of neoplastic cells for expression of different immunohistochemical markers is still under debate. These immunohistochemical studies were performed on eight cases of PXA in order to evaluate the expression and co-expression of glial and macrophage/histiocytic markers in various tumour cell populations. The expression of antigens was examined with the use of single- and double-immunolabelling methods for GFAP, vimentin, LCA, CD68, HLA-class II and MAC 387. All the cases of PXA showed variable immunoreactivity to GFAP, both in spindle-shaped and pleomorphic lipidised tumour cells. A subset of neoplastic cells was stained strongly with HLA-class II monoclonal antibody and with antibody to CD68. The reactivity to LCA and MAC 387 was absent in neoplastic cells, while it was easily evidenced in the non-neoplastic infiltrative component. The immunohistochemical double staining demonstrated the co-expression of GFAP and HLA-class II or CD68 antigens in the cytoplasm of individual neoplastic cells, including large pleomorphic, lipid-laden ones. It seems that tumour cells in PXAs derived from subpial astrocytes reveal monocyte/macrophage immunophenotype and demonstrate the capability of functional behaviour as mesenchymal cells with phagocytic activities. The variability in expression of antigens related to glial and monocytic/macrophage differentiation stressed the immunophenotypic heterogeneity of tumour cells in PXAs.

Nonredundant role of Bax and Bak in Bid-mediated apoptosis

Animal models suggest that Bax and Bak play an essential role in the implementation of apoptosis and as a result can hinder tumorigenesis. We analyzed the expression of these proteins in 50 human glioblastoma multiforme (GBM) tumors. We found that all the tumors expressed Bak, while three did not express Bax. In vitro, Bax-deficient GBM (BdGBM) exhibited an important resistance to various apoptogenic stimuli (e.g., UV, staurosporine, and doxorubicin) compared to the Bax-expressing GBM (BeGBM). Using an antisense strategy, we generated Bak(-) BeGBM and Bak(-) BdGBM, which enabled us to show that the remaining sensitivity of the BdGBM to apoptosis was due to the overexpression of Bak. Bax/Bak single or double deficiency had no influence on either the clonogenicity or the growth of tumors in Swiss nude mice. Of note, Bak(-) BeGBM cells were resistant to apoptosis induced by caspase 8 (C8) but not to that induced by granzyme B (GrB). Cells lacking both Bax and Bak (i.e., Bak(-) BdGBM) were completely resistant to all stimuli including the microinjection of C8 and GrB. We show that GrB-cleaved Bid and C8-cleaved Bid differ in size and utilize preferentially Bax and Bak, respectively, to promote cytochrome c release from mitochondria. Our results suggest that Bax deficiency is compensated by an increase of the expression of Bak in GBM and show, for the first time in human cancer, that the double Bax and Bak deficiency severely impairs the apoptotic program.

[Antigen-specific immunotherapy as a component of combined therapy for malignant brain tumors]

The purpose of the present research was to study immunity in the course of complex treatment for malignant gliomas of the brain and to evaluate extracorporeal antigen-specific immunotherapy (EASIT), a pilot procedure which was carried out according to an approved protocol. Initially, lowered HLA-DR+ monocyte count and in vitro inhibition of proliferative activity were reported in all patients. Inductive EASIT started in early postoperative period aborted immune disturbances caused by surgery. In 1998-2000, the procedure was performed in 33 patients with anaplastic astrocytoma (AA) (20) and glioblastoma (GB) (13). Mean dose of cell infusion was 2.43(0.18 x 109/patient and was well tolerated. There are 22 survivors and 9 patients died (GB--4 and AA--5; overall mortality--29%). Mean relapse-free survival was 14.2 mo (22); stable remission during 12-18 mo--37.5% (3/8)(GB) and 64% (9/14) (AA) Complete rehabilitation of immunity was generally reported 12 mo after the course of EASIT. Hence, complex treatment (surgery + EASIT) enhanced its efficacy in the management of brain tumors.

Serum antibodies to JC virus, BK virus, simian virus 40, and the risk of incident adult astrocytic brain tumors

Genomic sequences of the human polyomaviruses, JC virus (JCV) and BK virus (BKV), and simian virus 40 (SV40) have been reported from several types of human brain tumors, but there have been no population-based seroepidemiologic studies to evaluate the association between polyomavirus infection and brain tumors. We conducted a case-control study, nested within a prospective cohort, to investigate the association between antibodies to JCV, BKV, and SV40, as measured in serum collected 1-22 years before diagnosis and incident primary malignant brain tumors. Brain tumor cases (n = 44) and age-, gender-, and race-matched controls (n = 88) were identified from participants of two specimen banks in Washington County, Maryland. IgG antibodies to the capsid proteins of JCV and BKV were assessed using ELISAs. SV40-neutralizing antibodies were measured using plaque neutralization assays. Similar to the general population, the prevalence of JCV and BKV infection was high in our study population (77 and 85%, respectively). Antibodies to SV40 were less prevalent (11%). The odds ratio for subsequent brain tumor development was 1.46 [95% confidence interval (CI), 0.61-3.5] for JCV, 0.66 for BKV (95% CI, 0.22-1.95), and 1.00 for SV40 (95% CI, 0.30-3.32). Given the high prevalence of JCV and BKV infections and the millions who were potentially exposed to SV40 through contaminated polio vaccines, future studies should attempt to replicate these findings.

Epigenetics in high-grade astrocytomas: opportunities for prevention and detection of brain tumors

Human high-grade astrocytomas (HGA) are the most prevalent incurable brain tumors. We found that the vast majority of HGA patients overexpress a restricted receptor for an immune regulatory cytokine, interleukin 13 (IL-13). Interestingly, the HGA-associated restricted receptor protein IL-13Ralpha2 is expressed in the testes, and its gene is localized to chromosome X. These mirror the expression pattern and genomic localization of cancer/testes tumor antigens (CTA). Hypothetical considerations and now experimental evidence are beginning to point towards epigenetics, and DNA methylation alterations in particular, as being responsible for the appearance in cancer of CTA, including IL-13Ralpha2. In line with our interest in the X chromosome and oncogenesis, we have identified a new ubiquitous angiogenic factor in HGA, a vascular endothelial growth factor-D (VEGF-D). We have also demonstrated that the activating protein-1 (AP-1) family of transcription factors play a potentially critical role in the progression of gliomas by eliciting uncontrolled upregulation of VEGF-D and other compounds essential for cancer cell proliferation, tumorigenesis, and infiltration. The possibility exists that an unopposed constitutive increase in AP-1 activity in HGA is related to epigenetic silencing of the inhibitors of AP-1 activity. These phenomena offer potential targets for exploitation in either prevention or early detection of brain tumors. For example, anticancer vaccines against shared CTA could help in prevention of HGA development. Furthermore, drugs with anti-AP-1 activity could be effective in preventing formation/progression of HGA, or progression from less malignant lower grade gliomas to HGA. Also, circulating antibodies against CTA and factors that are AP-1 regulated may provide a useful tool in early detection of brain tumors or for monitoring their progression following initial treatment.

Microglia in brain tumors

Microglia have long been ignored by neurooncologists. This has changed with the realization that microglial cells not only occur within and around brain tumors but also contribute significantly to the actual tumor mass, notably in astrocytic gliomas. In addition, it has been speculated that microglia could play a role in the defense against neoplasms of the nervous system. However, the biological success of these tumors, i.e., their highly malignant behavior, indicates that natural microglial defense mechanisms do not function properly in astrocytomas. In fact, there is evidence that microglial behavior is controlled by tumor cells, supporting their growth and infiltration. This unexpected "Achilles heel" of microglial immune defense illustrates the risk of generalizing on the basis of a single aspect of microglial biology. Microglia are highly plastic cells, capable of exerting cytotoxic functions under conditions of CNS infections, but not necessarily during glioma progression. Thus, the suggestion that microglial activation through stimulation by cytokines (e.g., interferon-gamma) will benefit patients with brain tumors could prove fatally wrong. Therapeutic recruitment of microglia to treat such diffusely infiltrative brain tumors as astrocytic gliomas must be considered premature.

[Characteristics and immunologic changes in patients with malignant brain tumors]

The investigation was concerned with assaying immunity and evaluating the role played by monocytes and tumor cells in the formation of T-cell dysfunction in malignant glioma (MG). The study group included 28 patients with anaplastic astrocytomas (n = 18) and glioblastomas (n = 10). MG patients showed significant changes in the numbers of CD16+ NK-cells and HLA-DR monocytes as well as lowered levels of HLA-DR expression on monocytes and proliferative response of T-lymphocytes as compared with both standard and alternative pathways of activation. Monocytes and macrophages suppressed T-cell activity due to production of prostaglandins E2 in such patients. Enhanced immunosuppression was also reported in 24-hour supernatants of tumor cells. Immune disorders were shown to involve apoptosis-independent mechanisms. Hence, despite the immune privilege of the brain, immunocompetent cells crossed blood-brain barrier and counteracted with tumor cells. As a consequence, monocyte function and cellular cooperation dropped while production of immunosuppressive factors rose, and T-cell dysfunction was brought about through apoptosis-independent mechanisms.

[The features of the brain immune system in brain neoplasms]

Examining responses of the local immune system of the brain in neurocancer patients suggests that the immune system is involved in the neuroimmune interaction of both physiological and pathological conditions in the central nervous system (CNS). The setting off the local immune system of the brain is of functional nature, similar to functional analogy with the local system of the mucosae. By functional analogy, the aggregate of immune responses in the nervous tissue and cerebrospinal fluid should be called local and the system that includes these responses should named the local immune system of the brain. Due to the fact that nervous, endocrine, and immune regulatory pathways intersect in the CNS (hypothalamus), it is expedient to call this aggregate of defensive factors and mechanisms in CNS more broadly--the neuroimmune system.

Morphine Regulates Gene Expression of α- and β-Chemokines and Their Receptors on Astroglial Cells Via the Opioid μ Receptor

The brain is a target organ for recreational drugs and HIV-1. Epidemiological data demonstrate that opioid abuse is a risk factor for HIV-1 infection and progression to AIDS. Chemokines and their receptors have been implicated in the neuropathogenesis of HIV-1 infections. However, little is known about the effects of opioids on the expression of chemokines and their receptors (the latter also are HIV-1 coreceptors) by cells of the CNS. Herein we describe the effects of morphine on gene expression of the alpha- and beta-chemokines and their receptors by the astrocytoma cell line U87 and by primary normal human astrocyte (NHA) cultures. U87 cells treated with morphine showed significant down-regulation of IL-8 gene expression, whereas expression of the IL-8 receptor CXCR2 was reciprocally up-regulated as detected by RT-PCR. Treatment of NHAs with morphine suppressed IL-8 and macrophage-inflammatory protein-1beta gene expression, whereas expression of their receptor genes, CCR3 and CCR5, was simultaneously enhanced. These morphine-induced effects on U87 and NHA cells were reversed by the opioid mu receptor antagonist beta-funaltrexamine. Morphine also enhanced the constitutive expression of the opioid mu receptor on astroglial cells. Our results support the hypothesis that opioids play a significant role in the susceptibility of the CNS to HIV-1 infection and subsequent encephalopathy by inhibiting local production of HIV-1-protective chemokines (IL-8 and macrophage-inflammatory protein-1beta) and enhancing expression of HIV-1 entry coreceptor genes (CCR3, CCR5, and CXCR2) within the CNS. These effects of opioids appear to be mediated through the opioid mu receptor that we demonstrated on astroglial cells.

Adenovirus-mediated gene transfer of B7.1 induces immunological anti-tumor effects in a murine brain tumor

The purpose of the present study was to determine if adenovirus-mediated transfection of a syngeneic mouse brain tumor with the gene encoding B7.1 enhances immunogenicity against tumor. Malignant astrocytoma cells were transfected with adenoviral vectors carrying the B7.1 gene (AdB7). Immunocytochemical analysis confirmed the expression of B7.1 in vitro and in vivo. To investigate the effects of B7.1 expression on tumorigenicity of the malignant astrocytoma, mice were implanted intracerebrally with B7.1-transfected glioma cells. There was no significant difference in proliferation between B7.1-transfected cells and controls in vitro. Nevertheless, mice implanted with B7. 1-transfected cells survived significantly longer than those in the control groups. Immunocytochemical analysis of the tumors showed that there was infiltration of a number of CD8+ T-cells and CD25+ activated T-cells in the brain implanted with B7.1-transfected glioma cells. The results showed the possibility that adenovirus-mediated B7.1 gene transfection to a brain tumor induced activation of CD8+ cytotoxic T-lymphocytes.

Local treatment of brain tumors with targeted chimera cytotoxic proteins

High-grade astrocytomas (HGA) are the most prevalent brain tumors that represent a unique pharmaceutical challenge. Their cerebral localization and characteristic features of tumor progression primarily dictate this challenge. Targeted chimera conjugate/fusion cytotoxic proteins have become the newest class of investigative drug candidates for the treatment of HGA due to their inherent properties that are compatible with drug deliveries to brain tumors. A conjugate of a human transferrin with bacterial toxin, Diphtheria toxin, has shown clinical efficacy in Phase I and II trials when administered intratumorally through convection-enhanced delivery. This immunotoxin belongs to the first group of immunotoxins that started to live up to early expectations. Other anti-brain tumor cytotoxins have entered or will enter the clinic shortly. The clinical applicability of targeted bacterial toxin-containing cytotoxins in the treatment of brain tumors warrants further development and careful clinical evaluation.

Sister cytotoxic CD8+ T cell clones differing in natural killer inhibitory receptor expression in human astrocytoma

Natural killer (NK) inhibitory receptors are thought to play a critical role in the regulation of cytotoxicity of NK cells and certain self-reactive T cells. In the present study, we investigated whether astrocytoma infiltrating T lymphocytes may be functionally compromised by NK receptors (NKRs). The NK inhibitory receptor CD94/NKG2A was found on a significant proportion of CD8+ astrocytoma infiltrating lymphocytes. The functional consequences of CD94/NKG2A expression were explored at the clonal level, using a T cell clone that exhibited substantial variation in the expression of this heterodimer. Triggering of CD94/NKG2A inhibited the killing properties of T cells with a high level of this receptor, but not those from T cells with a low level. Our data indicate that some astrocytoma infiltrating lymphocytes express functional inhibitory CD94/NKG2A, raising the possibility that they may represent silent T cells specific for self-antigens (Ags) expressed on tumor cells. Understanding the mechanisms of regulation of these receptors may bring new insights for optimizing an anti-tumor immune response.

Immunophenotype of pleomorphic xanthoastrocytoma

Pleomorphic xanthoastrocytoma (PXA) is an uncommon tumor, often seizure-associated and occurring in the temporal lobe of young adults. Although its cells are considered astrocytic in nature, recent studies suggest the presence of neuronal differentiation and a possible relationship to glioneuronal neoplasms. We immunostained 40 cases of PXA, including two composite PXA-gangliogliomas (PXA-GG), with a panel of glial (glial fibrillary acidic protein, S-100 protein) and neuronal markers (class III beta-tubulin, synaptophysin, neurofilament proteins, MAP2, and chromogranin A). Conventional PXAs demonstrated immunoreactivity for glial fibrillary acidic protein (100% of cases), S-100 protein (100%), class III beta-tubulin (73%), synaptophysin (38%), NF proteins (18 and 8%), and MAP2 (8%). Chromogranin A stain was absent in all conventional PXA cases. Neoplastic ganglion cells in both PXA-GGs stained with class III beta-tubulin, synaptophysin, and chromogranin A. Ultrastructural studies, performed in nine cases, demonstrated neuronal features including microtubules, dense core granules, and/or clear vesicles largely limited to cell processes (two PXAs) and in the cytoplasm (PXA component of one PXA-GG). Although the essential nature of PXA is clearly and uniformly glial, the significance of the limited neuronal differentiation is unclear, as it is the relationship between conventional PXA and PXA-GG. We found no evidence that the former is a precursor of the latter.

The potential for efficacy of the modified (ICP 34.5(-)) herpes simplex virus HSV1716 following intratumoural injection into human malignant glioma: a proof of principle study

We have previously demonstrated the safety of intratumoural administration of the selectively replication-competent herpes simplex virus mutant HSV1716 in patients with high-grade glioma (HGG). Here we show its potential for efficacy by demonstrating that the virus survives and replicates when injected into the tumours of patients. Since HSV replication is a cytolytic process it must result in tumour cell killing. Twelve patients with biopsy-verified HGG received an intratumoural injection of 10(5) plaque-forming units (p.f.u.) of HSV1716. Four to 9 days after inoculation, tumours were removed and assayed for evidence of viral replication. In two patients, HSV1716, in excess of the input dose was recovered from the injection site. HSV DNA was detected by PCR at the sites of inoculation in 10 patients and at distal tumour sites in four. HSV-specific antigen was detected in tumour tissue from two patients. In five patients an immunological response to HSV1716, as detected by changes in levels of IgG and IgM, was demonstrated. This study demonstrates that HSV1716 replicates in HGG without causing toxicity in both HSV-seropositive and -seronegative patients.

Analysis of the antibody repertoire of astrocytoma patients against antigens expressed by gliomas

The molecular characterization of antigens preferentially or exclusively expressed by astrocytomas and recognized by the autologous immune system are a prerequisite for the development of specific vaccines. To identify such antigens, we screened 5 cDNA expression libraries derived from astrocytomas and other gliomas for reactivity with high-titered IgG antibodies in the sera of astrocytoma patients using SEREX, the serologic identification of antigens by recombinant cDNA expression cloning. Autologous and allogeneic SEREX analysis of >5 x 10(6) clones with the sera of 18 astrocytoma patients revealed 10 antigens: the differentiation antigen glial fibrillary acidic protein (GFAP), Bax-inhibitor 1 (which was overexpressed in all glioma samples tested), 3 other molecules involved in the regulation of gene expression and proliferation (the nm23-H2-encoded nucleoside diphosphate kinase B, the Ran binding protein-2 and a DNA binding protein encoded by the son gene), SP40,40 (a complement inhibitory molecule), the chaperonin TCP-1, calnexin and 2 new gene products. No immune responses were detected against the "shared tumor" or "cancer testis antigens" that are regularly expressed in gliomas. Antibody responses in astrocytoma patients against antigens expressed by gliomas were rare and, with the exception of Bax-inhibitor 1 and the product of the son gene, were also found in apparently healthy controls. We conclude that although astrocytomas express a broad spectrum of antigens, they elicit antibody responses only rarely, most likely because of their intrinsic immunosuppressive effects.

Fas engagement increases expression of interleukin-6 in human glioma cells

Although Fas (APO-1/CD95) is expressed ubiquitously and induces cell death, it is also known to mediate other responses such as inflammation and angiogenesis in vivo. Previously, we have reported that Fas ligation induces selective expression of chemokines (IL-8 and MCP-1) in human astroglioma cells in vitro. In this study, we investigated whether Fas ligation can induce expression of other cytokines. Expression of IL-1alpha, IL-1beta, IL-6, IL-10, IL-12, IFN-beta, IFN-gamma, LT-beta, TGF-beta, TNF-a and TNF-beta mRNA levels in CRT-MG human astroglioma cells upon Fas ligation was investigated using RNase protection assay (RPA). We found that IL-6 mRNA is selectively induced upon Fas ligation, and IL-6 mRNA and protein expression was further investigated using single probe RPA and ELISA. To investigate the in vivo expression of IL-6, human brain specimens were homogenized and ELISA was performed for IL-6 expression. Herein, we demonstrate that: (1) Among these cytokines, only IL-6 was induced upon Fas ligation in a dose- and time-dependent manner; (2) A selective p38 MAP kinase inhibitor, SB202190, and a MEK inhibitor, U0126, suppressed induction of IL-6 mRNA and protein expression by Fas ligation; and (3) Glioblastoma multiforme samples (n = 11) contain significantly higher levels of IL-6 compared to those of control brains (n = 5), which correlate with increased levels of Fas. These results suggest that the Fas-FasL system may play a role in the regulation of tumor growth and survival by inducing the pleiotropic cytokine IL-6.

MCP-1 expression in CNS-1 astrocytoma cells: implications for macrophage infiltration into tumors in vivo

Gliomas are among the most resistant tumors to conventional anti-tumor therapy, and are typified by their highly infiltrative nature and ill-defined borders. Macrophages constitute a major proportion of the tumor cell mass in both primary human gliomas and as shown here, a CNS-1 glioma model. The objective of this study was to identify tumor-cell-derived chemotactic factor(s) which participate in macrophage recruitment into tumors in vivo. This study demonstrates the constitutive expression of monocyte chemoattractant protein-1 (MCP-1), a potent monocyte chemoattractant, by the rat astrocytoma cell line CNS-1. Characterization of cytokine expression by CNS-1 cells in vitro revealed the constitutive expression of TGF-beta but not other proinflammatory cytokines. However, numerous cytokines were detected in CNS-I tumors in vivo including Ltbeta, IL-1alpha, IL-1beta, TNF-alpha, TNF-beta, IL-10, and IFN-gamma. Attenuation of MCP- I release from CNS-1 cells using an anti-sense approach revealed no significant alterations in macrophage infiltration into tumors in vivo, suggesting redundancy in the signal(s) involved in macrophage recruitment. Depletion of peripheral macrophages using liposome-encapsulated clodronate revealed no significant differences in tumor growth or in the degree of macrophage infiltration into CNS-1 tumors in vivo. These results indicate that CNS-1 cells produce chemotactic factors which likely participate in macrophage recruitment into tumors in vivo. Whether or not macrophage recruitment confers a growth advantage for the tumor remains to be determined.