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.

Glioma-expressed antigen 2 (GLEA2): a novel protein that can elicit immune responses in glioblastoma patients and some controls

Glioma constitutes the most frequent brain tumour in man with glioblastoma as the most prevalent and malignant type. The average survival time of less than 16 months underlines the need for improvements in diagnosis and therapy. Here, we report the identification of a novel antigen termed glioma-expressed antigen 2 (GLEA2) causing a frequent immune response in glioma patients. Screening of 450 000 clones from a glioblastoma lambda zap expression library with autologous patient serum revealed a group of five serum-positive clones sharing a high sequence homology. Further sequence analysis showed a sequence homology to a hepatocellular carcinoma associated antigen 58 (HCA58). We localized the novel HCA homologous gene termed glioma-expressed antigen 2 (GLEA2) on chromosome 20 by somatic cell hybrid panel mapping. Using allogenic sera from 39 glioblastoma patients, we found an immune response against GLEA2 in 17 patients (43%). In addition, screening with allogenic sera from other glioma patients revealed GLEA2 directed antibodies in two out of five pilocytic astrocytomas and in one out of two astrocytomas. Unrelated tumour sera revealed no immune response and sera from healthy persons showed an immune response in two out of 14 cases (14%). Northern blot hybridization and RT-PCR showed ubiquitous GLEA2 gene expression in glioma and normal tissues. The novel HCA homologous gene, GLEA2, appears to induce a frequent immune response in glioma. In the light of the lack of useful glioma markers, it appears reasonable to consider GLEA2 as a potential future diagnostic marker.

Activation of human macrophages by amyloid-beta is attenuated by astrocytes

In Alzheimer's disease, neuritic amyloid-beta plaques along with surrounding activated microglia and astrocytes are thought to play an important role in the inflammatory events leading to neurodegeneration. Studies have indicated that amyloid-beta can be directly neurotoxic by activating these glial cells to produce oxygen radicals and proinflammatory cytokines. This report shows that, using primary human monocyte-derived macrophages as model cells for microglia, amyloid-beta(1-42) stimulate these macrophages to the production of superoxide anions and TNF-alpha. In contrast, astrocytes do not produce both inflammatory mediators when stimulated with amyloid-beta(1-42). In cocultures with astrocytes and amyloid-beta(1-42)-stimulated macrophages, decreased levels of both superoxide anion and TNF-alpha were detected. These decreased levels of potential neurotoxins were due to binding of amyloid-beta(1-42) to astrocytes since FACScan analysis demonstrated binding of FITC-labeled amyloid-beta(1-42) to astrocytoma cells and pretreatment of astrocytes with amyloid-beta(1-16) prevented the decrease of superoxide anion in cocultures of human astrocytes and amyloid-beta(1-42)-stimulated macrophages. To elucidate an intracellular pathway involved in TNF-alpha secretion, the activation state of NF-kappaB was investigated in macrophages and astrocytoma cells after amyloid-beta(1-42) treatment. Interestingly, although activation of NF-kappaB could not be detected in amyloid-beta-stimulated macrophages, it was readily detected in astrocytoma cells. These results not only demonstrate that amyloid-beta stimulation of astrocytes and macrophages result in different intracellular pathway activation but also indicate that astrocytes attenuate the immune response of macrophages to amyloid-beta(1-42) by interfering with amyloid-beta(1-42) binding to macrophages.

The generation of anti-tumoral cells using dentritic cells from the peripheral bloood of patients with malignant brain tumors

Dendritic cells (DCs) can be the principal initiators of antigen-specific immune responses. We analyzed the in vitro-responses against brain tumor cells using DCs from the peripheral blood of patients with brain tumors. Peripheral blood mononuclear cells (PBMC) were obtained from 19 patients with malignant brain tumors: 12 metastatic brain tumors of lung adenocarcinoma, 7 high-grade astrocytomas. PBMC were cultured with 100 ng/ml of GM-CSF and 10 ng/ml of IL-4 for 5 7 days in order to produce mature DCs. The autologous tumor lysate (5 mg/ml, containing 1 x 10(6) cells) was then added to the cultured DCs. Using the DCs generated by these treatments, we assessed the changes that occurred in their immune responses against brain tumor via 51Cr-release and lymphocyte proliferation assays. We found that the matured DCs displayed the typical surface phenotype of CD3+, CD45+, CD80+ and CD86+. After the pulsation treatment with tumor lysate, DCs were found to have strong cytotoxic T lymphocyte activity, showing 42.5+12.7% killing of autologous tumor cells. We also found an enhancement of allogeneic T cell proliferation after pulsing the DC with tumor lysate. These data support the efficacy of DC-based immunotherapy for patients with malignant brain tumors.

Brain glioma and human leukocyte antigens (HLA)--is there an association

Expression of human leukocyte antigens (HLA) is important for the immune response against infectious agents and malignant cells. Association of single HLA antigens or HLA haplotypes with disease has been investigated previously, and positive correlations between HLA and some cancers, such as cervical or nasopharyngeal carcinomas have been reported. In the present study, HLA antigen frequencies of 65 adult Caucasian patients with low-grade, anaplastic, or malignant astrocytic glioma (WHO grades II-IV) were compared with 157 racially similar, asymptomatic control individuals. Both standard serologic and PCR techniques for HLA typing were employed for all patients and controls. Our results suggest a positive association between single HLA antigens and presence of symptomatic cerebral glioma. Compared with the control population, patients positive for HLA-A*25 had a 3.0-fold increased risk of glioma (p = 0.04), patients positive for HLA-B*27, a 2.7-fold risk (p = 0.03), and patients positive for HLA-DRB1*15, a 2.2-fold risk (p = 0.03), whereas HLA-DRB1*07 was associated with a 0.4-fold decreased risk of glioma (p = 0.02). Occurrence rate of some HLA antigen combinations and estimated haplotypes was also different in glioma patients. Thus, HLA-DRB1*15:DRB5*(51) occurrence in combination with HLA-DRB1*11 was associated with a 13.4-fold increased risk of glioma (p = 0.001), and the incidence of HLA-Cw*6:DRB1*07 with a 0.2-fold decreased risk of glioma (p = 0.03). In conclusion, single HLA antigens and their combinations and estimated haplotypes are possibly significantly more or less frequent in persons developing symptomatic cerebral glioma during their adult life, compared with asymptomatic individuals.

CXC chemokine receptor 4 expression and function in human astroglioma cells

Chemokines constitute a superfamily of proteins that function as chemoattractants and activators of leukocytes. Astrocytes, the major glial cell type in the CNS, are a source of chemokines within the diseased brain. Specifically, we have shown that primary human astrocytes and human astroglioma cell lines produce the CXC chemokines IFN-gamma-inducible protein-10 and IL-8 and the CC chemokines monocyte chemoattractant protein-1 and RANTES in response to stimuli such as TNF-alpha, IL-1beta, and IFN-gamma. In this study, we investigated chemokine receptor expression and function on human astroglioma cells. Enhancement of CXC chemokine receptor 4 (CXCR4) mRNA expression was observed upon treatment with the cytokines TNF-alpha and IL-1beta. The peak of CXCR4 expression in response to TNF-alpha and IL-1beta was 8 and 4 h, respectively. CXCR4 protein expression was also enhanced upon treatment with TNF-alpha and IL-1beta (2- to 3-fold). To study the functional relevance of CXCR4 expression, stable astroglioma transfectants expressing high levels of CXCR4 were generated. Stimulation of cells with the ligand for CXCR4, stromal cell-derived factor-1alpha (SDF-1alpha), resulted in an elevation in intracellular Ca(2+) concentration and activation of the mitogen-activated protein kinase cascade, specifically, extracellular signal-regulated kinase 2 (ERK2) mitogen-activated protein kinase. Of most interest, SDF-1alpha treatment induced expression of the chemokines monocyte chemoattractant protein-1, IL-8, and IFN-gamma-inducible protein-10. SDF-1alpha-induced chemokine expression was abrogated upon inclusion of U0126, a pharmacological inhibitor of ERK1/2, indicating that the ERK signaling cascade is involved in this response. Collectively, these data suggest that CXCR4-mediated signaling pathways in astroglioma cells may be another mechanism for these cells to express chemokines involved in angiogenesis and inflammation.

The observation of immunosuppressor(s) derived from cultured tumor cells and its partial neutralization with OK-432

Malignant tumors such as brain tumors have been reported to be associated with immunosuppression caused by certain tumor-secreted cytokines. The reversion of tumor-derived immunosuppression has not been described. The use of OK-432, an immunomodulatory agent prepared from Su-strain of Streptococcus pyogenes A3, to activate peripheral blood mononuclear cells from a patient with glioblastoma multiforme has demonstrated a sharp rise in proliferative response. This proliferative response was compromised in the presence of living and irradiated autogeneic cancer cells. The conditioned media from cultured cells of glioblastoma multiforme, astrocytoma, and cholangiocarcinoma were tested for immunosuppressive ability. We found that conditioned media from 3 of 4 cases of glioblastoma, all 3 cases of astrocytoma, and 1 case of cholangiocarcinoma exhibited immunosuppressive activity toward the proliferative response of allogeneic peripheral blood mononuclear cells to phytohemagglutinin. This is the first report that cholangiocarcinoma produces soluble immunosuppressor(s). Our finding suggested that soluble substance(s) as well as direct cell-cell contact between tumor cells and mononuclear cells play roles in the observed tumor-derived immunosuppression.

Vaccination of malignant glioma patients with peptide-pulsed dendritic cells elicits systemic cytotoxicity and intracranial T-cell infiltration

In this Phase I trial, patients' peripheral blood dendritic cells were pulsed with peptides eluted from the surface of autologous glioma cells. Three biweekly intradermal vaccinations of peptide-pulsed dendritic cells were administered to seven patients with glioblastoma multiforme and two patients with anaplastic astrocytoma. Dendritic cell vaccination elicited systemic cytotoxicity in four of seven tested patients. Robust intratumoral cytotoxic and memory T-cell infiltration was detected in two of four patients who underwent reoperation after vaccination. This Phase I study demonstrated the feasibility, safety, and bioactivity of an autologous peptide-pulsed dendritic cell vaccine for patients with malignant glioma.

The neuropeptide substance P activates p38 mitogen-activated protein kinase resulting in IL-6 expression independently from NF-kappa B

Substance P (SP), a member of the tachykinin peptide family, is a major mediator of neuroimmunomodulatory activities and neurogenic inflammation within the central and peripheral nervous system. SP has been shown to induce the expression of proinflammatory cytokines such as IL-6, which might be implicated in the etiopathology of several human brain disorders. We showed in a previous study that nanomolar concentrations of SP triggered activation of NF-kappaB, a transcription factor involved in the control of cytokine expression. However, activation of NF-kappaB was not involved in SP-induced expression of IL-6. Here, we describe p38 mitogen-activated protein kinase (p38 MAPK) as a signal transduction component that operates independently from NF-kappaB activation and that mediates SP-induced IL-6 expression in the human astrocytoma cell line U373 MG. SP induced the phosphorylation of p38 MAPK within 10 min, and this activation persisted up to 30 min and was independent from p42/44 MAPKs and protein kinase C activation, which all are induced after stimulation with SP. As shown by EMSA, p38 MAPK was not involved in SP-induced activation of NF-kappaB. p38 MAPK, however, mediated SP-induced IL-6 expression as shown by the use of specific inhibitors of this kinase. Our results suggest that activation of p38 MAPK is an important component controlling neurogenic inflammation within the CNS independently from NF-kappaB. Drugs targeting this MAPK may therefore interfere with SP-correlated neuropsychiatric disorders and may represent a therapeutic approach in these disorders.

Spontaneous neoplastic regression: the significance of apoptosis

In mammalian cells, neoplastic transformation has a direct relationship with the expression of oncogenes, the production of certain growth factors and with the mutation, loss or simple inactivation of the function of tumor suppressor genes. Genes for suppression of the development of the malignant immunophenotype, as well as inhibitory growth factors have regulatory functions within the normal processes of cell division and differentiation. Telomerase (a ribonucleoprotein polymerase) activation is frequently observed in various types of neoplastic cell transformation. Telomerase activation is regarded as essential for cell immortalization and its inhibition may result in spontaneous regression (SR) of neoplasms. SR of neoplasms occurs when the malignant tumor mass partially or completely disappears without any treatment or as a result of a therapy considered inadequate to influence systemic neoplastic disease. This definition makes it clear that the term SR applies to neoplasms in which the malignant disease is not necessarily cured, and to cases where the regression may not be complete or permanent. A number of possible mechanisms of SR are reviewed, with the understanding that no single mechanism can completely account for this phenomenon. The application of the newest immunological, molecular biological and genetic insights for more individualized anticancer immunotherapy (biotherapy) is also discussed. In conclusion, of all the possible mechanisms of SR of neoplasms, programmed cell death (PCD) or apoptosis is involved in each. The immunological mechanism is probably the main effector mechanism of SR in human neoplasms with its trigger being apoptosis. The treatments of the tumor, such as with various anti-neoplastic drugs or radiation or immunotherapy, all include the basic mechanism of programmed cell death or apoptosis. Without apoptosis, there is practically no tumor regression, none of any kind.

The cellular response of JC virus T-antigen-induced brain tumor implants to a Murine intra-ocular model

In order to define the immunologic response to central nervous system tumors in a controlled fashion, we compared xenogeneic, allogeneic and syngeneic transplants of JC virus-induced neural tumor cell aggregates implanted into anterior ocular chambers of mice. Semiquantitative assessment of the level of leukocyte common antigen (CD45) of the transplants by immunohistochemistry was used to gauge rejection. Reticulin staining was used to monitor vascularization. Immunoreactivity to the viral oncoprotein, T-antigen, was confirmed by immunohistochemistry and immunoprecipitation/Western blot analysis. The results demonstrated that transplants were viable at all time-points and developed vascularization as early as three days after transplantation. Xenotransplants, 13-days post-transplantation, and allogeneic transplants, 25 days post-transplantation were infiltrated with polymorphonuclear leukocytes. Fewer CD45 positive cells were demonstrated in syngeneic transplants. High levels of JCV T-antigen stimulated rejection in syngeneic transplants. These results establish a model for further investigation of the natural and induced immunologic response to central nervous system tumors.

Downregulation of glutamate receptor subunit 2(3) in subependymal giant-cell tumor

Immunohistochemical techniques were used to investigate the expression of glutamate receptor (GluR) subunits in samples of brain resected from children with and without tuberous sclerosis, using antibody to an epitope common to GluR subunits 2 and 3 [2(3)]. Our purpose was to characterize the phenotype of balloon cells in cortical tubers and tumor cells in subependymal giant-cell tumors. In cortical tubers, GluR 2(3) was expressed in the processes and cell bodies of balloon cells, demonstrating consistent immunoreactivity to vimentin. In subependymal giant-cell tumors, tumor cells also exhibited consistent immunoreactivity to vimentin but only faint immunoreactivity to GluR 2(3). The reason for the expression of subunit 2(3) in tubers but not in subependymal giant-cell tumors remains unknown. However, if one assumes that the presence of subunit 2 substantially reduces calcium conductance through alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid channel and maintains intracellular calcium homeostasis, one could speculate that downregulation of subunit 2(3) in tumor cells could result in increased calcium flux into these cells, causing tumorigenesis. Another explanation may be that receptor subunits cannot be produced sufficiently in tumor cells. Moreover, the pathogenetic pathways between balloon and giant-cells are distinctly different, despite the similarity in their phenotypical pathologic features.

Modulation of HLA-G antigens expression by human cytomegalovirus: specific induction in activated macrophages harboring human cytomegalovirus infection

After infection, human CMV (HCMV) establishes a latent and persistent infection in immature myeloid progenitors and peripheral blood monocytes. Completion of the HCMV life cycle is possible upon maturation of monocytes to tissue macrophages and under permissive circumstances, e.g., immunosuppression. We investigated the hypothesis that HLA-G molecules could be induced during HCMV reactivation in activated macrophages to favor virus dissemination. In this study, we provide evidence that HLA-G Ags are produced during viral reactivation in macrophages generated after allogeneic stimulation of HCMV latently infected monocytes. While HLA-G surface expression is up-regulated, classical MHC-I molecules are partially down-regulated by HCMV. In vivo, bronchoalveolar macrophages collected from patients suffering from acute HCMV pneumonitis also express HLA-G molecules. The direct correlation between HLA-G Ag induction and HCMV infection was confirmed in U-373 MG astrocytoma cells. Soluble HLA-G expression is stimulated upon HCMV infection, and this modulation depends on the cooperative action of the two immediate-early-1 pp72 and immediate-early-2 pp86 products. Because HLA-G transcription is active in macrophages and U-373 MG astrocytoma cells, it is likely that the modulation of HLA-G protein expression during HCMV replication occurs at a post-transcriptional level. Our data suggest that induction of HLA-G molecules could be an additional mechanism that helps HCMV to subvert host defenses.

T cell adoptive immunotherapy of newly diagnosed gliomas

Patients with newly diagnosed gliomas were treated with adoptive transfer of ex vivo activated T lymphocytes, derived from lymph nodes (LNs) draining autologous tumor vaccines, to determine the long-term toxicity of this treatment. Twelve consecutive patients were enrolled: 2 with grade II astrocytoma, 4 with anaplastic gliomas, and 6 with glioblastoma multiforme. Patients were injected intradermally with short-term cultured autologous irradiated tumor cells, admixed with granulocyte macrophage colony-stimulating factor, to stimulate draining LNs. The LN cells were activated with staphylococcal enterotoxin A for 48 h and then cultured in medium containing interleukin 2 for an additional 6-8 days and subsequently transferred i.v. to the patients. The number of cells obtained from the LNs ranged from 9 x 10(7) to 1.1 x 10(9), and the median cell proliferation was 41-fold. The dose of T cells infused ranged from 0.6 to 5.5 x 10(10) with a median of 1.1 x 10(10), the majority of which were CD 4+ (mean, 71%). The entire treatment was performed as outpatient therapy and was associated with a toxicity of grade 2 or less, consisting mainly of fever, nausea, and myalgias during the first 24 h. There were no indications of late adverse events from this treatment even among three patients with follow-up greater than 2 years post T cell transfer. Moreover, four patients demonstrated partial regression of residual tumor. This Phase I clinical trial of adoptive immunotherapy for patients with newly diagnosed malignant gliomas demonstrates feasibility, lack of long-term toxicity, and several objective clinical responses.

Autoregulation of the interleukin-1 system and cytokine-cytokine interactions in primary human astrocytoma cells

Cytokines are proposed to play important roles in brain tumor biology. Previous studies reported on interleukin-1beta (IL-1beta) production and IL-1 receptor type I (IL-1RI, signaling receptor) expression in human astrocytomas, and on IL-1beta action in astrocytoma cell lines. However, all studies that have tested the direct action of cytokines have used exclusively astrocytoma cell lines, which do not recapitulate the in situ astrocytoma. Here, we demonstrate that astrocytoma cells obtained shortly after tumor neurosurgical resection respond to the direct application of human IL-1beta with a significant upregulation of IL-1alpha, IL-1beta, IL-1RI, and tumor necrosis factor-alpha (TNF-alpha) mRNAs. IL-1 receptor antagonist (IL-1Ra, an endogenous inhibitor that blocks IL-1alpha and IL-1beta actions) mRNA was not upregulated. Application of heat-inactivated IL-1beta had no effect on any cytokine component examined, demonstrating specificity of action. On the other hand, IL-1beta application did not modulate any cytokine component in acutely resected and dissociated primitive neuroectodermal tumor cells. The data have implications for a positive autoregulatory IL-1beta feedback system and synergistic IL-1beta <=> TNF-alpha interactions, which can be involved in the growth of pilocytic astrocytomas. The results together with our previous studies also support the notion that IL-1Ra or a compound with similar cytokine inhibitory activity could be useful for brain immunotherapy of astrocytomas.

Identification and localization of the cytokine SDF1 and its receptor, CXC chemokine receptor 4, to regions of necrosis and angiogenesis in human glioblastoma

Glioblastoma multiforme (GBM) tumors display extensive histomorphological heterogeneity, with great variability in the extent of invasiveness, angiogenesis, and necrosis. The identification of genes associated with these phenotypes should further the molecular characterization, permitting better definition of glioma subsets that may ultimately lead to better treatment strategies. Therefore, we performed a differential mRNA display analysis comparing six GBM-derived primary cell cultures from patients having tumors with varied histomorphological features. We identified stromal cell-derived factor 1 (SDF1) as a gene with varied expression. SDF1 (cytokine) and CXC chemokine receptor 4 (CXCR4) interactions are implicated in modulating cell migration. They are also implicated in modulating the immune response in AIDS patients by macrophage-mediated T-cell apoptosis. GBM patients also fail to mount an immune response, although their tumors are seemingly exposed to immune cells in regions of angiogenesis, where the blood-brain barrier is absent, or in areas of necrosis. To determine whether the expression and localization of SDF1 and CXCR4 are consistent with such a role in these brain tumors, immunohistochemical analyses of these proteins were performed on normal brain and astrocytomas (grades II-IV). In normal brain tissue, low levels of SDF1 (0.5+) were observed in astrocytic processes, in neurons, and in the occasional phagocytic cells around vessels. CXCR4 expression was negative in brain tissue but was observed in phagocytic cells within the vessel lumen. In tumors, SDF1 and CXCR4 expression was colocalized when both were expressed, and SDF1 and CXCR4 expression increased with increasing tumor grade (from 0.5+ to 6+). Additionally, CXCR4 was expressed in neovessel endothelial cells. The proteins were expressed in regions of angiogenesis and degenerative, necrotic, and microcystic changes. Those tumors displaying greater amounts of these features had greater staining intensity of the proteins. The expression of SDF1 and CXCR4 did not colocalize with the proliferation marker MIB-1. Thus, our data suggest that SDF1 and CXCR4 expressions: (a) increase with increasing grade; (b) colocalize to regions within these tumors where their interaction may contribute to angiogenesis and/or modulation of the immune response; and (c) may serve to characterize subsets of GBMs.

Astrocytoma infiltrating lymphocytes include major T cell clonal expansions confined to the CD8 subset

Anaplastic astrocytoma and glioblastoma are frequent and malignant brain tumors that are infiltrated by T lymphocytes. Whether these cells result from non-specific inflammation following blood-brain barrier disruption or an antigen-driven specific immune response is unknown. In this study, an in-depth characterization of TCR diversity in tumor and blood RNA biopsies was performed in a series of 16 patients with malignant astrocytoma. Whilst there was no obvious restriction of the AV and BV gene segment usage, complementarity-determining region 3 size analysis and sequencing of amplified TCR transcripts revealed multiple T cell oligoclonal expansions in all astrocytomas analyzed. Unique T cell clones were present in different adjacent areas of a given tumor, but never detected in the blood. Quantification of the number of TCR clonal transcripts per microg of tumor RNA indicated that certain T cell clonal expansions may represent at least 300 cells/10(6) tumor cells. Furthermore, we demonstrated that the in vivo expanded clones were almost exclusively confined to the CD8(+) subset. Overall, these data suggest that spontaneous antigen-driven immune responses may be elicited against human astrocytoma despite the immunosuppressive microenvironment generated by the brain and the tumor itself. However, the ultimate failure of the immune system to control tumor growth could be the consequence of a deficient CD4 T(h) component of the response. This observation could have important consequences for the development of immunotherapies for astrocytoma patients.

Fas (Apo-1, CD95) receptor expression in childhood astrocytomas. Is it a marker of the major apoptotic pathway or a signaling receptor for immune escape of neoplastic cells?

Apoptosis is a physiological process wherein the cell initiates a sequence of events culminating in the fragmentation of its DNA, nuclear collapse, and finally disintegration of the cell into small, membrane-bound apoptotic bodies. Expression of Fas (APO-1, CD95) Receptor (FasR) and programmed or active cell (PCD) death was studied in childhood astrocytomas (ASTRs) with varying stages of malignancy, including pilocytic ASTR, low grade ASTR, anaplastic ASTR, and glioblastoma multiforme (GBM). The great majority of childhood glial tumors, particularly ASTRs express FasR whereas normal cells in the central nervous system (CNS) do not. FasR represents a transmembrane glycoprotein which belongs to the nerve growth factor/tumor necrosis factor (NGF/TNF) receptor superfamily. Apoptosis within ASTRs is triggered by the binding of FasR to its natural ligand (FasL) or by cross-linking with antibodies developed against FasR. Presence of FasL was also detected in childhood glial tumors. The expression of both FasR and FasL was also observed within the same ASTRs. Therefore, spontaneous, IP regulatory, intratumoral apoptotic cell death (autocrine suicide) is possible in childhood glial tumors. During a systematic, immunocytochemical screening of 42 childhood ASTRs tissues divided according to WHO classification: 6 WHO grade I or pilocytic ASTRs; 14 WHO grade II or low grade ASTRs; 16 WHO grade III or anaplastic ASTRs and 6 WHO grade IV or glioblastoma multiforme (GBM), we detected strong expression (intensity of staining: "A"--the highest possible; number of stained cells: +2 to +4, between 20% to 90%) of FasR, employing 4 microns thick, formalin fixed, paraffin-wax embedded tissue slides. FasR was present on 70% to 90% of tumor cells in pilocytic ASTRs, in 50% to 60% of the tumor cells in low grade ASTRs, in between 30% and 40% of the tumor cells in anaplastic ASTRs, and in between 20% to 35% of GBM cells. The panel of normal tissues employed as positive and negative tissue controls demonstrated presence of FasR in the prenatal thymus, mature tonsils and colonic epithelium. The use of a sensitive, indirect, six step immunoperoxidase or alkaline phosphatase conjugated streptavidin-biotin antigen detection technique provided excellent immunocytochemical results. A broad spectrum of neoplastic cells have been identified to express FasR: 1) carcinomas of epithelial origin, such as breast (ductal invasive, lobular invasive, mucinous), renal cell, gastric, colorectal, endometrial, prostate, pancreas, hepatocellular and large cell and squamous cell lung carcinomas: 2) non-epithelial neoplasms such as B cell mediastinal B cell and nodal non-Hodgkin's lymphomas large granular lymphocytic leukemia of T or NK cell origin malignant fibrous histiocytoma, malignant mesothelioma, leiomyosarcoma, epitheloid sarcoma and alveolar soft part sarcoma, as well as melanomas. Flow cytometry studies have also detected FasR expression on cells of adult T cell, and hairy cell leukemias, as well as in chronic B cell lymphocytic leukemia (BCLL). The coexpression of both FasR and FasL on several malignant cell types may represent an effective mechanism of tumor escape from the cellular immunological response of the host. It has been well established that brain tumors and melanomas produce their autocrine FasL, and even become capable of switching the signal transduction associated with FasL-FasR coupling from the PCD pathway to a tumor growth, proliferative pathway. It seems that the therapeutical use of FasR-FasL (main apoptotic pathway) may represent a new and exciting type of immunotherapy in the treatment of primary childhood glial tumors.

Expression of cytokines by human astrocytomas following stimulation by C3a and C5a anaphylatoxins: specific increase in interleukin-6 mRNA expression

C3a and C5a anaphylatoxins are two proinflammatory peptides generated during complement activation that act through distinct Gi protein-coupled receptors named C3aR and C5aR, respectively. We have demonstrated previously that human astrocytes expressed C3aR and C5aR constitutively and were able to produce a functional complement. In this study, we examined the effect of an anaphylatoxin stimulation on cytokine expression by human astrocyte cell lines. Interleukin (IL)-1beta, IL-6, tumor necrosis factor-alpha, and transforming growth factor-beta mRNA expression was studied by quantitative RT-PCR. Whereas IL-1beta, tumor necrosis factor-alpha, and transforming growth factor-beta mRNA levels remained unchanged, stimulation of astrocytoma cells (T98G, CB193, U118MG) by C3a, C5a, and peptidic C3aR and C5aR agonists induced an increase in the IL-6 mRNA level. The amount of IL-6 was markedly increased at 3 and 6 h and returned to the basal level at 9 h of stimulation. This response was specific, because pretreatment of cells with pertussis toxin or with polyclonal anti-C3aR or anti-C5aR antibodies completely blocked the IL-6 mRNA increase. The IL-6 response was also investigated at the protein level, but IL-6 protein was detected neither in cell lysates nor in supernatants of stimulated cells. The anaphylatoxin-mediated transcriptional activation of IL-6 gene suggests that C3a and C5a could play a role in priming glial cells during the inflammatory process in the brain.

Allogeneic astrocytoma in immune competent dogs

We have induced in canines long-term immune tolerance to an allogeneic cell line derived from a spontaneous canine astrocytoma. Allogeneic astrocytoma cells were implanted endoscopically into the subcutaneous space of fetal dogs before the onset of immune competency (< 40th gestational day). At adulthood, dogs rendered tolerant successfully serve as recipients of intracranial transplants of their growing allogeneic, subcutaneous tumor. Transplanted dogs subsequently develop a solid brain tumor with histological features similar to the original astrocytoma. This model may allow rapid development and evaluation of new therapies for brain tumors, as well as afford tumor biology studies that are untenable in smaller, immune incompetent, or inbred animals harboring less representative tumors.

Requirements for measles virus induction of RANTES chemokine in human astrocytoma-derived U373 cells

Interferons and chemokines play a critical role in regulating the host response to viral infection. Measles virus, a member of the Paramyxoviridae family, induces RANTES expression by astrocytes. We have examined the mechanism of this induction in U373 cells derived from a human astrocytoma. RANTES was induced in a dose- and time-dependent manner by measles virus infection. Inhibition of receptor binding by the anti-CD46 antibody TRA-2.10 and of virus-membrane fusion by the tripeptide X-Phe-Phe-Gly reduced RANTES expression. Formalin-inactivated virus, which can bind but not fuse, and extensively UV-irradiated virus, which can bind and fuse, were both ineffective. Therefore, virus binding to the cellular receptor CD46 and subsequent membrane fusion were necessary, but not sufficient, to induce RANTES. UV irradiation of virus for less than 10 min proportionally inhibited viral transcription and RANTES expression. RANTES induction was decreased in infected cells treated with ribavirin, which inhibits measles virus transcription. However, RANTES mRNA was superinduced by measles virus in the presence of cycloheximide. These data suggest that partial transcription of the viral genome is sufficient and necessary for RANTES induction, whereas viral protein synthesis and replication are not required. This hypothesis was supported by the fact that RANTES was induced through transient expression of the measles virus nucleocapsid gene but not by measles genes encoding P or L proteins or by leader RNA in A549 cells. Thus, transcription of specific portions of measles virus RNA, such as the nucleocapsid gene, appears able to generate the specific signaling required to induce RANTES gene expression.

Ki-67 (clone MIB-1) proliferation index in recurrent glial neoplasms: no prognostic significance

BACKGROUND

To determine if the Ki-67 (MIB-1 clone) proliferative index (PI) has prognostic potential in patients with recurrent astroglial neoplasms.

METHODS

We conducted a retrospective review of 27 patients whose initial and recurrent specimens were available. Histopathology was determined according to the World Health Organization classification. Proliferation index was calculated on formalin-fixed tissue using the Ki-67 (MIB-1 clone) antibody. Morphometric data were analyzed in conjunction with clinical data and Cox Proportionate Hazards Analysis, Spearman's correlation coefficient and Mann-Whitney Test.

RESULTS

Initial histopathology included 14 glioblastoma multiforme, 7 anaplastic astrocytoma, 3 oligoastrocytoma, and 3 astrocytoma. Recurrent specimens showed changes consistent with treatment. While univariate analysis shows initial histology correlated with survival (p<0.036), PI did not correlate with survival after either initial (p = 0.86) or recurrent (p = 0.46) surgery for any tumor type. PI difference between specimens also did not correlate with survival (p = 0.91). Initial PI did not correlate with recurrent PI either (p = 0.43).

CONCLUSIONS

Ki-67 PI does not confer additional prognostic information for patients with recurrent astroglial neoplasms. One possible explanation for this observation is that treatment may alter the PI independent of its effect on tumor growth.

Cytokine gene expression within the central nervous system

1. The identification of cytokine genes expressed in the central nervous system is critical to understanding the immune network in various diseases of brain, such as infection, degeneration, and malignancy. 2. Expression of cytokine genes in human astrocytoma cell lines and in fresh brain specimens was studied by the reverse-transcribed/polymerase chain reaction method. 3. The correlation between clinical malignancy and cytokine gene expression within malignant glioma was examined, especially regarding the relevancy of inhibitory cytokines, such as transforming growth factor-beta and interleukin-10.