Tumor infiltrating immune cells in gliomas and meningiomas

Tumor-infiltrating immune cells are part of a complex microenvironment that promotes and/or regulates tumor development and growth. Depending on the type of cells and their functional interactions, immune cells may play a key role in suppressing the tumor or in providing support for tumor growth, with relevant effects on patient behavior. In recent years, important advances have been achieved in the characterization of immune cell infiltrates in central nervous system (CNS) tumors, but their role in tumorigenesis and patient behavior still remain poorly understood. Overall, these studies have shown significant but variable levels of infiltration of CNS tumors by macrophage/microglial cells (TAM) and to a less extent also lymphocytes (particularly T-cells and NK cells, and less frequently also B-cells). Of note, TAM infiltrate gliomas at moderate numbers where they frequently show an immune suppressive phenotype and functional behavior; in contrast, infiltration by TAM may be very pronounced in meningiomas, particularly in cases that carry isolated monosomy 22, where the immune infiltrates also contain greater numbers of cytotoxic T and NK-cells associated with an enhanced anti-tumoral immune response. In line with this, the presence of regulatory T cells, is usually limited to a small fraction of all meningiomas, while frequently found in gliomas. Despite these differences between gliomas and meningiomas, both tumors show heterogeneous levels of infiltration by immune cells with variable functionality. In this review we summarize current knowledge about tumor-infiltrating immune cells in the two most common types of CNS tumors–gliomas and meningiomas–, as well as the role that such immune cells may play in the tumor microenvironment in controlling and/or promoting tumor development, growth and control.     

MIP-1alpha and MCP-1 Induce Migration of Human Umbilical Cord Blood Cells in Models of Stroke

Monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein (MIP-1alpha) are implicated in monocyte infiltration into the central nervous system (CNS) under pathological conditions. We previously showed that in vivo human umbilical cord blood cells (HUCB) migrate toward brain injury after middle cerebral artery occlusion (MCAO). We hypothesized that MCP-1 and MIP-1alpha may participate in the recruitment of HUCB towards the injury. Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO), and 24 hours later the production of MCP-1 and MIP-1alpha in the brain was examined with immunohistochemistry, ELISA, and western blotting. The chemotactic effect of MCP-1 and MIP-1alpha, and the expression of MCP-1 receptor CCR2 and MIP-1alpha receptor CCR1, CCR5 on the surface of HUCB were also examined. MCP-1 and MIP-1alpha expression were significantly increased in the ischemic hemisphere of brain, and significantly promoted HUCB cell migration compared to the contralateral side. This cell migration was neutralized with polyclonal antibodies against MCP-1 or MIP-1alpha. Also chemokine receptors were constitutively expressed on the surface of HUCB cells. The data suggested that the increased chemokines in the ischemic area can bind cell surface receptors on HUCB, and induce cell infiltration of systemically delivered HUCB cells into the CNS in vivo.     

Monocyte chemoattractant protein-1 increases microglial infiltration and aggressiveness of gliomas

Macrophages are thought to represent a first line of defense in anti-tumor immunity. Despite infiltration by microglial cells, however, malignant gliomas are still highly aggressive tumors. We here identify monocyte chemoattractant protein-1 (MCP-1) as a critical chemoattractant for glioma-infiltrating microglial cells. MCP-1-transfected rat CNS-1 gliomas were massively infiltrated by microglial cells. Whereas MCP-1 did not promote the growth of CNS-1 cells in vitro, intracerebral CNS-1-transfected tumors grew more aggressively than control-transfected tumors. This provides the first functional evidence that MCP-1 recruits microglial cells to gliomas and promotes their growth in vivo. Microglial cells may support rather than suppress glioma growth.     

Monocyte chemoattractant protein 1 is responsible for macrophage recruitment following injury to sciatic nerve

Following injury to the peripheral nervous system, circulating monocytes/macrophages are recruited to the damaged tissue, where they play vital roles during both nerve degeneration and subsequent regeneration. Monocyte chemoattractant protein-1 (MCP-1), a member of the C-C or β-chemokine family, is a powerful leukocyte recruitment/activation factor that is relatively specific for monocytes/macrophages. Because these are the predominant leukocyte type recruited by injured nerve, we hypothesized that up-regulation of MCP-1 expression is involved in recruitment of these cells. Indeed, assay of steady-state levels of MCP-1 mRNA in rat sciatic nerve during tellurium-induced primary demyelination indicated up-regulation of this chemokine with a peak after 3 days of tellurium exposure, preceding the peak of accumulation of phagocytic macrophages (assayed as lysozyme mRNA levels) by 6 days. Increasing levels of MCP-1 mRNA expression, induced by increasing levels of tellurium exposure, resulted in corresponding increases in subsequent recruitment of macrophages. In situ hybridization suggested that MCP-1 mRNA was localized in Schwann cells. No expression of MIP-2, which is a C-X-C or α-chemokine that is specific for recruitment of neutrophils, was detected, consistent with the lack of recruitment of significant numbers of these cells. In addition, we also investigated the response seen following nerve transection (axonal degeneration and secondary demyelination with no subsequent regeneration) and nerve crush (degeneration followed by regeneration). In these latter two nerve injury models, there was also a marked, early up-regulation of MCP-1 mRNA, with a time course that is compatible with a role for this chemokine in macrophage recruitment. We conclude that MCP-1 is involved in recruiting monocytes/macrophages to injured peripheral nerve and that the specificity of leukocyte types recruited results from specificity of chemokine production. J. Neurosci. Res. 53:260–267, 1998. © 1998 Wiley-Liss, Inc.     

趋化因子mRNA在实验性变态反应性神经炎中表达的研究

目的:实验性变态反应性神经炎(EAN)是一类T细胞介导的周围神经系统的自身免疫病,可用牛坐骨神经加完全氟氏佐剂诱导而成。本文研究趋化因子mRNA在实验性变态反应性神经炎(EAN)中的表达并探索其可能的作用。方法:用兔坐骨神经匀浆免疫Wistar大鼠,诱导格林巴利综合症(GBS)的动物模型EAN;采用地高辛标记的寡核苷酸探针检测EAN病变神经组织浸润细胞上趋化因子单核细胞趋化蛋白-1(MCP-1)及巨噬细胞炎性蛋白-1β(MIP-1β)mRNA表达情况。结果:MCP-1mRNA在临床症状出现前1-2天(14天)水平最高,随后逐渐下降;MIP-1 βmRA在临床症状出现前1-2天水平开始升高,在临床症状达到高峰时(21天)最高,进入恢复期后降至基础水平。结论:趋化因子在EAN的炎性细胞迁移及浸润进入神经细胞过程中起到重要作用。     

CNS macrophages and peripheral myeloid cells in brain tumours

Primary brain tumours (gliomas) initiate a strong host response and can contain large amounts of immune cells (myeloid cells) such as microglia and tumour-infiltrating macrophages. In gliomas the course of pathology is not only controlled by the genetic make-up of the tumour cells, but also depends on the interplay with myeloid cells in the tumour microenvironment. Especially malignant gliomas such as glioblastoma multiforme (GBM) are notoriously immune-suppressive and it is now evident that GBM cells manipulate myeloid cells to support tumour expansion. The protumorigenic effects of glioma-associated myeloid cells comprise a support for angiogenesis as well as tumour cell invasion, proliferation and survival. Different strategies for inhibiting the pathological functions of myeloid cells in gliomas are explored, and blocking the tropism of microglia/macrophages to gliomas or manipulating the signal transduction pathways for immune cell activation has been successful in pre-clinical models. Hence, myeloid cells are now emerging as a promising target for new adjuvant therapies for gliomas. However, it is also becoming evident that some myeloid-directed glioma therapies may only be beneficial for distinct subclasses of gliomas and that a more cell-type-specific manipulation of either microglia or macrophages may improve therapeutic outcomes.     

CHST2在胶质瘤中的表达及临床意义

目的 探讨糖磺基转移酶2（CHST2）在人脑胶质瘤中的表达情况及其临床意义。方法 从Gliovis在线网站获取TCGA、CGGA、Rembrandt数据集,分析CHST2表达水平与胶质瘤病理特征、生存预后、免疫细胞浸润的关系。结果 胶质瘤母细胞瘤（GBM）组织CHST2表达水平较低级别胶质瘤（LGG）明显增高（P<0.05）,异柠檬酸脱氢酶（IDH）突变型胶质瘤CHST2表达水平较野生型明显增高（P<0.05）,1p19q未共缺失胶质瘤CHST2表达水平较未缺失胶质瘤明显增高（P<0.05）。胶质瘤、GBM和LGG病人,O6-甲基鸟嘌呤-DNA甲基转移酶（MGMT）启动子甲基化的GBM和LGG病人,以及仅进行化疗的GBM和LGG病人,CHST2高表达组生存时间均显著低于低表达组（P<0.05）。GBM和LGG组织CHST2表达水平与巨噬细胞和树突状细胞的浸润程度呈正相关（P<0.05）。结论 CHST2表达水平与胶质瘤病人生存预后、化疗反应和免疫细胞浸润密切相关。     

脑胶质瘤CHSY1的表达变化及临床意义的生信分析

目的 探讨硫酸软骨素合酶1（CHSY1）在脑胶质瘤中的表达及临床意义。方法 从Gliovis下载CHSY1在TCGA、CGGA和Rembrandt数据库中的基因表达数据和对应的临床数据,将CHSY1表达量由低到高排序,前50%为低表达组,后50%为高表达组。利用TIMER在线网站分析CHSY1在脑胶质瘤中的表达与免疫浸润的相关性。结果 胶质瘤组织CHSY1表达水平明显高于正常脑组织（P<0.05）,且与胶质瘤病理分级呈正相关（P<0.05）。多因素Cox回归分析显示CHSY1高表达是胶质瘤病人生存预后不良的独立危险因素（P<0.05）,CHSY1高表达组中位生存期较低表达组明显缩短（P<0.05）。MGMT启动子甲基化组胶质母细胞瘤病人中,CHSY1高表达组中位生存期较低表达组明显缩短（P<0.05）。CHSY1高表达组胶质瘤病人化疗后中位生存期较低表达组明显缩短（P<0.05）。TIMER分析发现,胶质母细胞瘤组织CHST1表达水平与树突状细胞的浸润程度呈正相关,低级别胶质瘤组织CHST1表达水平与B细胞、CD8+ T细胞、嗜中性粒细胞、巨噬细胞和树突状细胞的浸润程度成正比。结论 脑胶质瘤CHSY1呈高表达,与胶质瘤的恶性程度与免疫浸润呈正相关。CHSY1可作为胶质瘤预后和对化疗反应的预测因子。     

Infiltration of hematogenous lineage cells into the demyelinating central nervous system of twitcher mice

Infiltration of hematogenous lineage cells into the central nervous system (CNS) was investigated in the twitcher mouse, a murine model of globoid cell leukodystrophy in human. The hematogenous cells were selectively labeled following intraperitoneal injection of rhodamine isothiocyanate (RhIc). The frequency of detecting Rhlc-labeled cells (Rhlc+ cells) in the twitcher CNS varied with age. RhIc+ cells were hardly detected when injection was made prior to the postnatal day (PND) 30. The number of Rhlc' cells increased thereafter peaked at PND 35-38 and declined drastically at PND 40-45. The majority of RhIc+ cells were distributed in white matter of the CNS that correlated well with the areas of demyelination and of increased microglia/macrophage population described in our earlier studies. Almost all Rhlc+ cells were double-labeled with antibody for Mac-1 and also with MHC class II. Some small cells double-labeled with RhIc and antibodies for CD4, CD8, or IL-2R were also identified. By RT-PCR, the expression of monocyte chemoattractant protein- (MCP-1) mRNA increased drastically at PND 30, peaked at PND 35, and decreased gradually after PND 40. This pattern of mRNA changes correlated well with the dynamic pattern of the infiltration of hematogenous cells into the CNS, suggesting a role of chemokine(s) in the cellular infiltration in the twitcher brain. The expression of IL-10 mRNA also increased gradually. IL-10 is a cytokine inhibitory factor and a major regulator in suppressing the inflammatory response. Thus, our results indicated that hematogenous lineage cells infiltrated in the CNS of twitcher mice, and that MCP-1 and IL-10 may play an important role in regulating the cellular recruitment.     

Chemokine regulation of macrophage recruitment into the olfactory epithelium following target ablation: involvement of macrophage inflammatory protein-1alpha and monocyte chemoattractant protein-1

Target ablation by olfactory bulbectomy synchronizes the degenerative cell death of olfactory receptor neurons (ORNs), infiltration of macrophages, and proliferation of progenitor cells, leading to neurogenesis, ORN replacement, and regeneration of the sensory epithelium. Although macrophages participate in the degenerative and regenerative events, little is known of the molecular and cellular mechanisms associated with their recruitment during the earliest period following target ablation. Macrophage inflammatory protein-1alpha (MIP-1alpha) and monocyte chemoattractant protein-1 (MCP-1), which are members of the CC or beta-chemokine subfamily, are chemoattractants for monocytes/macrophages. Shortly after target ablation, the protein and mRNA levels for MIP-1alpha and MCP-1 were up-regulated, showing peak expression levels from 16 hr to 3 days post-OBX; this coincided with the pattern of infiltration of activated F4/80(+) macrophages. The mRNAs for MIP-1alpha and MCP-1, as well as their cognate receptors CCR1 and CCR2, respectively, were localized in resident and infiltrating macrophages in numbers commensurate with those of F4/80-immunopositive macrophages in adjacent tissue sections. The mRNA(+) macrophages were localized within olfactory epithelial compartments that corresponded with their proposed functions associated with phagocytosis, proliferation, and infiltration. Our data support the hypothesis that MIP-1alpha and MCP-1 are chemoattractant chemokines associated with the recruitment of macrophages into the olfactory epithelium shortly after target ablation.     

Differential expression of MHC class II molecules by microglia and neoplastic astroglia: relevance for the escape of astrocytoma cells from immune surveillance

There is increasing evidence that microglia serve as antigen presenters in the human CNS. Although the occurrence of MHC class II immunoreactive cells has been reported in astrocytic gliomas, the relative contribution of microglia to this cell population has not been studied in detail. Using computer-assisted image analysis, we have investigated the expression of MHC class II molecules and of the microglia/macrophage markers Ki-M1P, RCA-1, KP1 and iba1 , in 97 astrocytic gliomas comprising all WHO grades to answer the question whether there is a correlation between tumour grade and the number of MHC class II positive microglia/macrophage profiles. Microglia expressing MHC class II were common in astrocytomas and anaplastic astrocytomas but rare in pilocytic tumours although there was significant variation within each group. MHC class II immunoreactivity was reduced in highly cellular areas of glioblastomas where large numbers of cells expressing macrophage markers were still present. Thus, there was no simple relationship between tumour grade and microglial/macrophage MHC class II expression. In addition, up to 55% of astrocytic gliomas contained MHC class II immunoreactive tumour cells. Microglia but not tumour cells were found to express the BB1/B7 costimulator. We conclude that microglia in astrocytic gliomas are well equipped to function as antigen presenting cells. Yet, neoplastic astroglia appear to acquire the capacity to downregulate microglial MHC class II expression and, at the same time, may induce T-cell clonal anergy through aberrant expression of MHC class II molecules.     

Vascular cell adhesion molecule-1 mRNA is expressed in immune-mediated and ischemic injury of the rat nervous system

In this study we used nonradioactive in situ hybridization for the cellular localization of vascular cell adhesion molecule-1 (VCAM-1) mRNA in immune-mediated, ischemic and degenerative diseases of the rat nervous system. In the acute phase of experimental autoimmune encephalomyelitis and neuritis VCAM-1 mRNA was expressed not only on the luminal surface of inflamed vessels but also in perivascular cells suggesting a functional role of VCAM-1 in both endothelial adhesion and local restimulation of autoantigen-specific T cells. Accordingly, perivascular T cell accumulation was most pronounced at sites of local VCAM-1 mRNA expression. In addition, VCAM-1 mRNA was detected in the border zone around photochemically induced cerebral infarcts which is the predeliction site of T cell infiltration and expression of immune activation markers during the first week after ischemia. VCAM-1 mRNA was absent from the center of the infarcts as well as axotomized central and peripheral nerves undergoing Wallerian degeneration. These data indicate that VCAM-1-mediated adhesion processes are involved in immune-mediated and ischemic diseases of the nervous system but not in T cell-independent macrophage recruitment during Wallerian degeneration.     

Glycosphingolipid component profiles or human gliomas--correlation to survival time and histopathological malignancy grading

BACKGROUND: Glycosphingolipids (GSL) are expressed on the surface of neuroectodermal cells. The correlation of a variety of distinct GSL with different primary brain tumors has been demonstrated. Three distinct GSL-component profiles (GSL-types I, II and III) of human gliomas have been defined by our group. The purpose of this study was to evaluate the correlation of the established GSL-types I-III with survival time and histopathological malignancy grading in 40 human gliomas. METHODS: Neutral and acidic GSL-component patterns, histopathological malignancy grade and survival time, and a number of other relevant variables were examined. Kaplan-Meier survival curves were analyzed with the log rank test. RESULTS: GSL-type I was expressed in 18 tumors (17 Glioblastoma multiforme (GBM) and 1 anaplastic astrocytoma (AA)). GSL-type II was expressed in 11 tumors (7 GBM, 3 AA, 1 low grade astrocytoma (LGA)). 10 patients presented with GSL-type III (3 GBM, 4 AA, 3 LGA). Kaplan Meier survival curves of GSL-types I-III differed significantly (p = 0.0231, log-rank-test). However, survival time correlated better to the WHO grades. Within a given malignancy grade, GSL-types gave additional informations about the proliferative properties. CONCLUSIONS: This is the first report of a correlation between survival time and human glioma neutral and acidic GSL-components. The results are in agreement with observations of other investigators. The analysis of GSL-type expression might give useful additional information about proliferative properties of human gliomas in a given malignancy grade. In particular, the early prediction of outcomes in anaplastic or low grade gliomas might be possible.     

Interferon-beta treatment alters peripheral blood monocytes chemokine production in MS patients

Chemokines direct the recruitment of leukocytes to inflammatory sites and may also participate in the regulation of cytokine production by naive T helper cells. Chemokine production by blood monocytes was investigated by intracytoplasmic staining in interferon-beta (IFN-beta)-treated multiple sclerosis (MS) patients, untreated MS patients, and healthy controls. Under unstimulated conditions, no differences in the production of interleukin-8 (IL-8), IFN-inducible protein 10 (IP-10), monokine induced by interferon-gamma (Mig), monocyte chemoattractant protein-1 (MCP-1), and monocyte chemoattractant protein-3 (MCP-3) were seen between untreated MS patients and controls. Chemokine production by monocytes following T cell activation was decreased in MS patients taking IFN-beta compared to controls and untreated MS patients. Unlike other chemokines, macrophage inflammatory protein-1alpha (MIP-1alpha) production by monocytes was significantly decreased in untreated MS patients compared to controls, and IFN-beta treatment increased MIP-1alpha expression to the level seen in controls. In vitro addition of IFN-beta1b to peripheral blood mononuclear cells (PBMC) cultures tended to decrease the production of IL-8, IP-10, Mig, MCP-1, and MCP-3, but not of MIP-1alpha. These findings suggest that IFN-beta treatment may have a differential affect on chemokine production by monocytes. Longitudinal studies must be done to confirm these observations.     

Production of Monocyte Chemotactic Protein-1 By Rat Brain Macrophages

In the present study, we show that cultured rat brain macrophages release a soluble factor that stimulates the migration of bone marrow-derived macrophages, as determined by an in vitro chemotaxis assay. A checkerboard analysis indicated that most of this effect resulted from a polarized migration of the cells (chemotactic phenomenon), rather than in an increase in cell motility (chemokinesis). This activity was significantly decreased by an immune serum directed against the rat monocyte chemoattractant protein-1 (chernokine MCP-1). Northern blot analysis demonstrated expression of the MCP-1 gene in cultured brain macrophages, but its absence in unstimulated bone marrow-derived macrophages. Up-regulation of MCP-1 expression was observed when lipopolysaccharide was added to cultured brain macrophages, a peak occurring after a 6 h period of stimulation. Also, inflammatory cytokines such as interleukin (IL)-1β, colony stimulating factor-1, tumour necrosis factor-α and IL-6 individually increased the basal level of MCP-1 mRNA. Subsequently, we demonstrated the in vivo production of MCP-1 in the adult rat brain following injury induced by a local injection of kainic acid. MCP-1 synthesis was localized in both astrocytes and brain macrophages. These results suggest that the activation of resting microglial cells into brain macrophages and their subsequent secretion of chemokines could contribute to the mechanism(s), leading to the infiltration of the CNS by blood-derived monocytes, as observed in several pathologies.