De novo expression of the hemoglobin scavenger receptor CD163 by activated microglia is not associated with hemorrhages in human brain lesions

The main function of CD163 (hemoglobin scavenger receptor) is to bind the hemoglobin-haptoglobin complex, thereby mediating extravasal hemolysis. However, CD163 also has an antiinflammatory function. After CD163-mediated endocytosis, hemoglobin is catabolized further by hemeoxygenase 1 (HO-1). Previously, we found expression of HO-1 to be restricted to microglia/macrophages at sites of hemorrhages in human traumatic and ischemic brain lesions. We now investigated if CD163 expression is also correlated with hemorrhages in brain lesions. Methods. Autopsy brain tissue from 44 cases with hemorrhagic brain lesions (32 traumatic brain injuries/TBI, 12 intracerebral bleedings/ICB), 56 non-hemorrhagic brain lesions (30 ischemias, 26 hypoxias) and 6 control brains were investigated. The post injury survival times ranged from a few minutes to 60 months. Results. In controls, single perivascular monocytes expressed CD163, but only single CD163+ microglia were found in 3/6 cases. CD163+ cells in the parenchyma (activated microglia/macrophages) increased significantly within 24 hours after trauma and ischemia and within 1-7 days following ICB or hypoxia. Overall, significantly lower and higher levels of parenchymal CD163+ cells occurred in hypoxia and ischemia, respectively. Perivascular CD163+ cells also increased significantly in all pathological conditions. In areas remote from circumscribed brain lesions (TBI, ICB, ischemia), significant changes were only found in ICB and ischemia. Conclusions. De novo expression of CD163 by activated microglia/macrophages and CD163+ infiltrating monocytes are neither restricted to nor predominant in hemorrhagic brain lesions. Thus, the antiinflammatory function of CD163 probably predominates, both in hemorrhagic and non-hemorrhagic brain lesions and points to possible immunomodulatory treatment strategies targeting CD163.

Spatio-temporal deleted in colorectal cancer (DCC) and netrin-1 expression in human foetal brain development

AIMS

Deleted in colorectal cancer (DCC) and its ligand netrin-1 are known as axonal guidance factors, being involved in angiogenesis, migration and survival of precursor cells in the embryonic mammalian central nervous system (CNS). So far, little is known about the distribution of those molecules in human CNS development.

METHODS

We investigated 22 human foetal brain specimens (12th and 28th week of gestation) for DCC and netrin-1 expression by means of immunohistochemistry, immunofluorescence and confocal laser microscopy. Statistical analysis was performed by applying a semi-quantitative score, including staining intensity and frequency and correlation with foetal age.

RESULTS

DCC and netrin-1 were differentially expressed throughout the developing human foetal telencephalic and cerebellar cortical layers. Netrin-1 exhibited the highest levels in telencephalic germinal layers, whereas the strongest DCC immunoreactivity was seen in the developing cortical plate. Netrin-1 and DCC were predominantly present on cerebellar external granule layer cells. Distinct co-expression was seen in maturing foetal brainstem nuclei, cerebellar external granular layer and the choroid plexus. In contrast, endothelial cells showed strong netrin-1 expression with subsidiary DCC immunoreactivity. Pontine and telencephalic axonal fibre tracts also demonstrated strong netrin-1 expression.

CONCLUSIONS

We show that DCC and netrin-1 are ubiquitously expressed in the human foetal brain; however, both exhibit a distinct spatio-temporal expression pattern. Together with the data from animal experiments, our findings might indicate also an important role for DCC and netrin-1 in human foetal CNS development.

Immunohistochemical analysis of CDX2 expression in normal choroid plexus epithelium and choroid plexus tumors

BACKGROUND

The Wnt and BMP signaling pathways are involved in the morphogenesis of both gastrointestinal and choroid plexus epithelium. In the intestine, Wnt signaling represses the expression of the tumor suppressor gene CDX2 via SOX9, a transcription factor, which is also expressed in the choroid plexus. Recently, an inverse correlation between CDX2 expression and tumor grade, tumor stage and lymph node metastasis in colorectal adenocarcinomas has been reported. Besides intestinal tissues, expression of CDX2 has also been reported in various other epithelial tissues and carcinomas. To date, no data exist on expression of CDX2 in normal and neoplastic choroid plexus epithelium.

AIM

To investigate CDX2 expression in normal and neoplastic choroid plexus.

MATERIALS AND METHODS

Paraffin-embedded samples from 60 normal choroid plexus, including 23 fetal tissue samples and from 65 choroid plexus tumors (47 choroid plexus papillomas WHO grade I, 16 atypical choroid plexus papillomas and 2 choroid plexus carcinomas WHO grade III) were examined by immunohistochemistry. Samples from normal choroid plexus were collected from 45 autopsy cases and from 15 neurosurgical specimens.

RESULTS

Normal and neoplastic choroid plexus lacked CDX2 expression.

CONCLUSION

In our series, immunohistochemistry shows no evidence for a role of CDX2 in development or differentiation of normal choroid plexus from the 9th gestational week until adulthood. Since choroid plexus tumors reliably lack CDX2 immunoreactivity, this marker may be helpful in distinguishing cerebral metastases from CDX2-positive adenocarcinomas and choroid plexus neoplasms.

Concepts and developments in peripheral nerve surgery

Nerve injuries may result in sensory and motor deficits when not treated appropriately. Especially the surgical management of nerve defects still represents a challenge for the surgeon. In these cases the grafting of autologous nerves represents the only reasonable approach. Due to the side effects associated with this method (sacrifice of donor nerves, neuroma formation in the harvesting area, limited availability of donor nerves, etc.), numerous alternatives were proposed in order to avoid the transplantation of autologous tissue. This review provides a general view on the state of the art of how to supply gaping injuries in the peripheral nerve. Furthermore new approaches emphasizing tubulization techniques for the reconstruction of lost nerve tissue are described with a special focus on various materials with their advantages and disadvantages.

Erythropoietin receptor is expressed in meningiomas and lower levels are associated with tumour recurrence

AIMS

The Epo-EpoR pathway plays a role in tumour growth, metastasis and treatment resistance and is a potential target in oncological treatment. As the EpoR status in human meningiomas is unknown, our aim was to characterize EpoR expression in these tumours.

METHODS

We examined 131 meningioma samples of all WHO grades from 116 patients by immunohistochemistry for EpoR. Among these, 25 meningiomas showed brain invasion and 29 patients had a further tumour recurrence. A group of 20 patients without tumour recurrence served as controls. In 12 cases we were able to compare both the primary and the following recurrent tumours. The presence of EpoR in meningiomas was confirmed by RT-PCR and Western blot.

RESULTS

EpoR was expressed in all meningiomas. Statistical analysis revealed that the mean expression levels of EpoR were significantly lower in primary tumours with known recurrence compared with a recurrence-free control group. Additional matched pair analysis in individual cases showed no significant differences between primary and recurrent tumours. No significant correlation between EpoR expression and WHO grade, age, sex or brain invasion was detected. Using specific primer pairs for RT-PCR, we were able to detect all three known isoforms of EpoR: the full-length isoform EpoR-F, the truncated isoform EpoR-T and the soluble isoform EpoR-S.

CONCLUSIONS

Our results demonstrate the expression of EpoR in meningiomas. Lower EpoR mean levels might be a useful marker for a higher recurrence risk, but further studies are needed to clarify the influence of EpoR on recurrences and the role of the different isoforms.

No evidence for WT1 involvement in a beta-catenin-independent activation of the Wnt signaling pathway in pituitary adenomas

The overexpression of Wilms' tumor gene product WT1, which acts as a tumor suppressor or oncogene, has been reported in various malignancies. Recent studies have shown that the interaction partner Wnt-4 is upregulated in pituitary adenomas dependent on the Pit-1 lineage (somatotrophs, lactotrophs, and thyrotrophs). However, no data on WT1 expression in nontumorous pituitary tissue or pituitary adenomas is available to date. We investigated WT1 expression in 90 paraffin-embedded pituitary adenomas, including eight atypical adenomas, and in 28 nontumorous pituitary glands by immunohistochemistry. WT1 is absent in epithelial cells of all nontumorous pituitary glands and in 87 out of 90 pituitary adenomas. Only two GHomas (including one atypical adenoma) and one gonadotropin-producing adenoma expressed WT1 in the cytoplasm of single tumor cells without nuclear staining. There is no evidence that WT1 does regulate the Wnt-4/beta-catenin-independent pathway which is activated in the Pit-1-expressing subset of pituitary adenomas.

Diagnostic value of WT1 in neuroepithelial tumours

AIMS

Currently, clinical trials using WT1 (Wilms tumour gene) peptide vaccines are conducted in haematopoietic malignancies and solid cancers. Single reports showed that the Wilms tumour gene product WT1 is also expressed in astrocytic neoplasms. Our aim was to investigate WT1 expression in a large cohort of various neuroepithelial tumours of different World Health Organization (WHO) grades and in normal central nervous system (CNS) tissue specimens to test its potential value as a diagnostic marker.

METHODS

Specimens were assessed by RT-PCR, Western blotting and immunohistochemistry. The samples investigated in our study consisted of 334 human neuroepithelial tumours, among those 33 oligodendrogliomas, 219 astrocytomas (including 105 glioblastomas) and 47 ependymomas.

RESULTS

Our results showed a de novo WT1 expression in neuroepithelial tumours. In diffuse astrocytomas and ependymomas, WT1 expression increased significantly with the grade of malignancy. In contrast, no significant difference was seen between WHO grade-II and -III oligodendrogliomas. Controlling for WHO grade, the comparison of oligodendrogliomas with ependymal and astrocytic tumours showed higher expression values for the latter.

CONCLUSIONS

Our study shows that WT1 is expressed de novo in numerous neuroepithelial tumours and increases with the grade of malignancy. These results suggest an important role of WT1 in tumourigenesis and progression in human brain tumours.

Atypical type II silent corticotrophic adenoma developing into Cushing's disease upon second recurrence

Herein, we report the case of a 73-year old male patient who presented with two recurrences of a pituitary adenoma within a period of 15 years. The first tumor resection 15 years ago revealed a non-functioning pituitary macroadenoma. 11 years later, the first recurrence of the tumor was reoperated. Throughout the early course of the disease, he suffered from secondary adrenal insufficiency and required replacement therapy with hydrocortisone. Currently, he presented with the second recurrence and clinical examination revealed signs of Cushing's disease. This was clearly confirmed by endocrinological evaluation. A retrospective analysis of all histological and immunohistochemical slides rendered an adenoma exhibiting chromophobia, ACTH-positivity and features of atypia such as elevated p53 and Ki67 expression as well as nuclear polymorphism. According to the revised WHO classification it was classified as atypical type II silent corticotroph adenoma at the time of the first and second surgery. The specimen removed during the recent surgery displayed the same histological features and was classified as corticotroph adenoma. The combination of an atypical type II adenoma and the switch in the hormone status to an endocrinologically active adenoma makes this case exceedingly rare.

Two functionally linked amino acids in the stem 2 region of measles virus haemagglutinin determine infectivity and virulence in the rodent central nervous system

Rodent brain-adapted measles virus (MV) strains, such as CAM/RB and recombinant MVs based on the Edmonston strain containing the haemagglutinin (H) of CAM/RB, cause acute encephalitis after intracerebral infection of newborn rodents. We have demonstrated that rodent neurovirulence is modulated by two mutations at amino acid positions 195 and 200 in the H protein, one of these positions (200) being a potential glycosylation site. In order to analyse the effects of specific amino acids at these positions, we introduced a range of individual and combined mutations into the open reading frame of the H gene to generate a number of eukaryotic expression plasmids. The functionality of the mutant H proteins was assessed in transfected cells and by generating recombinant viruses. Interestingly, viruses caused acute encephalitis only if the amino acid Ser at position 200 was coupled with Gly at position 195, whereas viruses with single or combined mutations at these positions, including glycosylation at position 200, were attenuated. Neurovirulence was associated with virus spread and induction of neuronal apoptosis, whereas attenuated viruses failed to infect brain cells. Similar results were obtained by using primary brain-cell cultures. Our findings indicate that a structural alteration in the stem 2 region of the H protein at position 195 or 200 interferes with infectivity of rodent neurons, and suggest that the interaction of the viral attachment protein with cellular receptors on neurons is affected.

Reactive astrocytes and activated microglial cells express EAAT1, but not EAAT2, reflecting a neuroprotective potential following ischaemia

AIMS

Glutamate receptor antagonists have failed clinical stroke trials and it has been proposed that the action of N-methyl D-aspartate receptors is necessary for neuronal survival. Thus, excitatory amino acid transporters (EAATs) might be a promising therapeutic target. The aim of this study was to investigate glial expression of EAATs following ischaemia.

METHODS AND RESULTS

Expression of EAAT1 (GLAST) and EAAT2 (Glt-1) in 24 cases of ischaemia was examined by immunohistochemistry. Cortical expression of both EAATs in the lesion decreased within 24 h (P < 0.01, each). Whereas EAAT1+ white matter cells increased 18-fold (P < 0.05) within 24 h in the lesion and remained elevated for months in adjacent (469-fold, P < 0.01) and remote areas (20-fold, P < 0.05), EAAT2+ white matter cells were equivalent in ischaemia and controls. In the first week after stroke mainly activated (ramified and amoeboid) microglia expressed EAAT1, whereas monocytic cells in perivascular spaces and foamy macrophages lacked EAAT1. After more than 1 week, predominantly reactive astrocytes expressed EAAT1.

CONCLUSIONS

Microglial EAAT1 expression is restricted to the early/intermediate stage of activation and blood-derived (perivascular) monocytes do not contribute to EAAT1+ cells following ischaemia. Whether a pharmacological increase in glial EAAT expression may compensate for loss of cortical EAAT expression and reduce neuronal damage following stroke requires investigation by further functional studies.

De novo erythropoietin receptor (EPO-R) expression in human neoplastic glial cells decreases with grade of malignancy but is favourably associated with patient survival

The erythropoietin receptor (EPO-R) is mainly known as a regulator of erythropoiesis. However, recent studies revealed that the EPO-R is not exclusively expressed in haematopoietic tissues but also in various cancer cell types and normal tissue such as the central nervous system (CNS). EPO-R is up-regulated under hypoxia and is able to counteract the deleterious effects of hypoxia on tumour growth, metastasis and treatment resistance. Therefore, the EPO-EPO-R signalling pathway is considered as a possible target for tumour treatment. Here, we investigated brain tumour samples obtained from patients between 1993 and 2003 to study EPO-R expression in vivo. Tissue samples included 194 gliomas of different WHO grades, additionally 25 infiltration zone samples and 31 relapses of WHO grade IV glioblastomas as well as 23 normal CNS tissue specimens to address the in vivo situation. Immunohistochemistry of the tissue microarray samples revealed significantly higher levels of EPO-R expression in neoplastic glial cells compared with glial cells derived from normal brain. EPO-R expression showed a highly significant decrease from low- to high-grade gliomas. Age-stratified Kaplan-Meier analysis revealed longer survival for patients exhibiting high EPO-R status in high-grade gliomas. Our results show a grade-dependent EPO-R down-regulation and might contribute to the understanding of high-grade glioma resistance to radio- and chemotherapy as both were shown to be improved by a well functioning EPO-EPO-R pathway in previous studies. Further studies are needed to investigate to what extent the decreased mortality in age-stratified patient groups with high EPO-R levels reflects a direct beneficial role of EPO-R expression.

Expression of EAAT1 reflects a possible neuroprotective function of reactive astrocytes and activated microglia following human traumatic brain injury

Glutamate-mediated excitotoxicity is known to cause secondary brain damage following stroke and traumatic brain injury (TBI). However, clinical trials using NMDA antagonists failed. Thus, glial excitatory amino acid transporters (EAATs) might be a promising target for therapeutic intervention.

METHODS AND RESULTS

We examined expression of EAAT1 (GLAST) and EAAT2 (Glt-1) in 36 TBI cases by immunohistochemistry. Cortical expression of both EAATs decreased rapidly and widespread throughout the brain (in lesional, adjacent and remote areas) following TBI. In the white matter numbers of EAAT1+ parenchymal cells increased 39-fold within 24h (p<0.001) and remained markedly elevated till later stages in the lesion (90-fold, p<0.01) and in peri-lesional regions (86-fold, p<0.01). In contrast, EAAT2+ parenchymal cells and EAAT1+ or EAAT2+ perivascular cells did not increase significantly. Within the first days following TBI mainly activated microglia and thereafter mainly reactive astrocytes expressed EAAT1. Perivascular monocytes and foamy macrophages lacked EAAT1 immunoreactivity. We conclude that following TBI i) loss of cortical EAATs contributes to secondary brain damage, ii) glial EAAT1 expression reflects a potential neuroprotective function of microglia and astrocytes, iii) microglial EAAT1 expression is restricted to an early stage of activation, iv) blood-derived monocytes do not express EAAT1 and v) pharmacological modification of glial EAAT expression might further limit neuronal damage.

Upregulation of frizzled 9 in astrocytomas

Wnt/frizzled (FZD) cascades play important roles in controlling cell fate, proliferation, migration, tissue architecture and organogenesis during embryonic development and in adult organisms. The potential involvement of this pathway in tumorigenesis has been established in several types of cancers. Frizzled 9 (FZD9) is expressed in brain and its aberrant expression in gastric cancer was observed. However, its association with astrocytomas remains unknown therefore we studied FZD9 expression in astrocytomas of different malignancy. In the present study, FZD9 expression in 25 astrocytomas was investigated using immunohistochemistry with specific antibodies. Further FZD9 expression in native human brain tissue and glioblastoma cell line were analysed using real-time reverse transcription polymerase chain reaction (RT-PCR). In human astrocytomas, FZD9 immunoreactivity (IR) was observed in both microvessels and neoplastic cells. The percentage of FZD9+ microvessels in relation to FZD9+ vessels was significantly higher in malignant astrocytomas than in low-grade astrocytomas and positively correlated with the astrocytoma World Health Organization (WHO) grading (r = 1, P = 0.04). Furthermore, the FZD9 IR scores positively correlated with astrocytoma WHO grading (r = 1, P = 0.04) and proliferating activity (r = 0.77, P < 0.001). Real-time RT-PCR data showed that FZD9 expression in human glioblastoma was significant higher than in normal brain (P < 0.05) but FZD9 expression was only slightly induced in cobalt chloride-treated human glioblastoma T98G cells compared with untreated cells (P > 0.05). FZD9 is upregulated in astrocytomas, suggesting that FZD9 could be important in the tumorigenesis of human astrocytomas.

Differential microglial regulation in the human spinal cord under normal and pathological conditions

As the primary intrinsic immune effector cells of the central nervous system, microglia are involved in virtually all pathological processes of the brain and spinal cord including inflammatory, neurodegenerative, traumatic, neoplastic and vascular diseases. Despite this important role, there is a lack of data concerning microglial distribution and protein expression in the human spinal cord. In this study, we immunohistochemically investigated 10 normal human spinal cords to establish reference data and compared these results with 15 pathological human spinal cords deriving from distinct pathologies. Each spinal cord was evaluated at eight different levels for three white and two grey matter areas for both constitutive (MHC-II, CD68, IL-16, AIF-1, LCA, CD4) and reactive (MRP-8, MRP-14) microglial antigens. Whereas previous studies revealed significant regional differences in microglial distribution and protein expression in human brain, normal spinal cord displayed a uniform expression pattern, reaching levels of up to 17% MHC-II positive cells of the total cell population. This datum formed the basis for the further evaluation of microglia expression levels in pathological spinal cords, where levels of up to 45% positive cells were observed. Our results represent important reference values for future neuropathological diagnostic and therapeutical approaches in spinal cord pathologies.

Bag-1 and Bcl-2 gene transfer in malignant glioma: modulation of cell cycle regulation and apoptosis

Bag-1 is a heat shock 70 kDa (Hsp70)-binding protein that can collaborate with Bcl-2 in suppressing apoptosis under some conditions. Here, we report that 11 of 12 human glioma cell lines express Bag-1 protein in vitro. Moreover, 15 of 19 human glioblastomas expressed Bag-1 as assessed by immunohistochemistry in primary tumor specimens. To examine the biological effects of Bag-1 in glioma cells, we expressed Bag-1 or Bcl-2 transgenes in 2 human malignant glioma cell lines, LN-18 and LN-229. Bag-1 significantly slowed glioma cell growth and reduced clonogenicity of both cell lines in vitro. Coexpressed Bcl-2 abrogated these effects of Bag-1. Intracranial LN-229 glioma xenografts implanted into nude mice revealed a substantial growth advantage afforded by Bcl-2. Bag-1 had no such effect, either in the absence or presence of Bcl-2. Upon serum starvation in vitro, Bcl-2 prevented cell death whereas Bag-1 did not. Both Bcl-2 and Bag-1 slowed proliferation of serum-starved cells when expressed alone. Importantly, coexpression of Bcl-2 and Bag-1 provided a distinct growth advantage under conditions of serum starvation that is probably the result of (i) the death-preventing activity of Bcl-2 and (ii) the property of Bag-1 to overcome a Bcl-2-mediated enhancement of exit from the cell cycle. In contrast to these Bcl-2/Bag-1 interactions observed under serum starvation conditions, Bag-1 did not further enhance the strong protection from staurosporine-, CD95 (Fas/Apo1) ligand-, Apo2 ligand (TRAIL)- or chemotherapeutic drug-induced apoptosis afforded by Bcl-2. Taken together, these results indicate a role for Bag-1/Bcl-2 interactions in providing a survival advantage to cancer cells in a deprived microenvironment that may be characteristic of ischemic/hypoxic tumors such as human glioblastoma multiforme, and suggest that Bcl-2/Bag-1 interactions also modulate cell proliferation.

Surviving glioblastoma for more than 5 years: The patient's perspective

The authors performed a comprehensive analysis of the functional outcome of 10 patients who had survived 5 years from a diagnosis of glioblastoma. Neurologic deficits were mild in most patients, but neuropsychological testing demonstrated cognitive deficits in all patients. Depression and anxiety were common. Although most patients thought that their social functioning and work ability were impaired, little reduction in overall quality of life was perceived.

Atypical teratoid-rhabdoid tumor spreading along the trigeminal nerve

We here describe the case of a boy with an atypical teratoid-rhabdoid tumor (ATRT) of the 4th ventricle at 1 year of age and a local tumor recurrence at 19 months of age. Due to brainstem infiltration, only incomplete tumor resection was possible each time. High-dose chemotherapy, stem cell transplantation and irradiation resulted in complete tumor remission on a control MRI. At 8 years of age, another tumor appeared extending from the cerebellopontine angle along the right trigeminal nerve through Meckel's cave into the cavernous sinus. The trigeminal tumor was not in continuity with the primary ATRT but was located within the field of prior irradiation, neuroradiologically mimicking a schwannoma or a meningioma. The origin of the trigeminal tumor as a late metastasis of the former ATRT or as a less likely irradiation-induced secondary ATRT and the operative approach are discussed.

A new family with frontotemporal dementia with intronic 10+3 splice site mutation in the tau gene: neuropathology and molecular effects

Mutations in the tau gene cause familial frontotemporal dementia with parkinsonism linked to chromosome 17 characterized by filamentous tau protein deposits. Here we describe the clinical and neuropathological features of a case from a newly identified family with an intron 10+3-splice site mutation in the tau gene. The proband presented with severe personality changes and stereotyped speech followed by parkinsonian symptoms. He died at age 56 after a disease duration of approximately 6 years. At autopsy, there was marked frontotemporal degeneration with abundant tau-immunoreactive neuronal and glial inclusions widespread in the cortex and brainstem. RT-PCR analysis revealed a 3.7-fold increase of tau transcripts with exon 10, resulting in an 1.7-fold higher expression level of 4-repeat tau isoforms in soluble tau fractions when compared to control brains and exclusively 4-repeat tau isoforms in the sarcosyl-insoluble tau fractions. In accordance with the hypothesis that the overexpression leads to saturation of microtubule binding sites and an increase of unbound 4-repeat tau isoforms which assemble into filaments, the neuronal and glial inclusions in this case were exclusively composed of 4-repeat tau isoforms. The clinical and neuropathological data of this family are compared with results from the two other published families with the intron 10 + 3 mutation, the MSTD and the SOT 254 family.

Adult medulloblastoma: prognostic factors and response to therapy at diagnosis and at relapse

Adult medulloblastoma is a rare tumor with few retrospective studies published so far. The role of adjuvant chemotherapy or chemotherapy at relapse is unclear. This study reports therapy and outcome in all adult (>or=16 years old) medulloblastoma (n=34) and supratentorial primitive neuroectodermal tumor (PNET) patients (n=2) treated in 2 neuro-oncological centers between 1976 and 2002. The median age was 24.5 years (range 16-76). After resection, 16 patients were treated with craniospinal radiotherapy alone, 20 patients also received adjuvant chemotherapy (8 vincristine, CCNU, cisplatin; 7 methotrexate alone or methotrexate/vincristine-based polychemotherapy; 5 other protocols). Median survival in the whole cohort was 126 months (2+ - 200+months). Five-year and 10-year survival rates were 79 % and 56%. Adjuvant chemotherapy was associated with a non-significant trend to prolonged survival (relative risk (RR) 1.89; p=0.068). The median progression-free survival (PFS) after primary therapy was 83 months. At relapse, 10 of 12 evaluable patients achieved a complete response upon second-line therapy. The median survival times from first (n=17) and second relapse (n=9) were 21 months (0-67+ months; 5/17 without second relapse) and 20 months (1-29 months). Cox regression analysis revealed the infiltration of the floor of the 4(th) ventricle at diagnosis as the only therapy-independent prognostic factor (RR 0.48; p=0.03). In conclusion, adjuvant chemotherapy may prolong survival in adult medulloblastoma patients. Moreover, second-line therapy may be beneficial for these patients. As in pediatric medulloblastoma patients, primary infiltration of the floor of the 4(th) ventricle indicates a poor prognosis.

Expression and functional activity of osteoprotegerin in human malignant gliomas

Apo2L/TRAIL-based therapy is a promising experimental approach to the treatment of human malignant gliomas. Osteoprotegerin (OPG) is a soluble decoy receptor for Apo2L/TRAIL that antagonizes Apo2L/TRAIL-induced apoptosis. High levels of OPG expressed by tumor cells might therefore abrogate the activity of exogenously added or adenovirally expessed Apo2L/TRAIL. Here we assessed the expression of OPG in human gliomas in vivo, in primary glioma cell cultures and in established glioma cell lines. Immunohistochemistry revealed weak OPG immunoreactivity in up to 5% of the tumor cells in 8 of 13 glioblastomas. Strong OPG labeling was detected in single scattered tumor cells in one of these specimens. Five glioblastomas did not express OPG. High OPG expression was found in 1 of 6 primary glioma cell cultures and in 1 of 12 established glioma cell lines, T98G. OPG released by T98G cells was biologically active in that it inhibited Apo2L/TRAIL-induced apoptosis in sensitive glioma cells. Altogether, however, these data suggest that OPG expression may not be a major pathway of glioma cell resistance to future Apo2L/TRAIL-based therapeutic approaches.

The allograft inflammatory factor-1 in Creutzfeldt-Jakob disease brains

The allograft inflammatory factor-1 (AIF-1) is a 17-kDa IFN-gamma inducible Ca(2+)-binding EF-hand protein that is encoded within the HLA class III genomic region and is involved in immune dysfunction and smooth muscle cell activation. We used immunohistochemistry double labelling experiments to analyse the spatial distribution and cell-type-specific localization of AIF-1 in the brains of patients who died as a result of sporadic Creutzfeldt-Jakob disease (CJD) and neuropathologically unaltered controls. Significantly more AIF-1 immunoreactive macrophages/microglial cells and, interestingly, neurones were observed in CJD patients compared to controls. Western blotting confirmed more prominent AIF-1 immunoreactive bands of approximately 50 kDa in four CJD patients compared to three controls. Chaotropic SDS-PAGE of the recombinant AIF-1 resulted in almost complete reduction of the 50 kDa band and mass spectrometry revealed only AIF-1-specific tryptic protein fragments suggesting that trimerized AIF-1 is the predominant form in vivo. Finally, we analysed mechanisms of neuronal AIF-1 induction. Following H2O2 challenge, a model of general cell stress, we observed the gradual induction of AIF-1 and, more interestingly, release to the supernatant of SKNSH neurones. Parallel reverse transcriptase polymerase chain reaction and sequencing was used to confirm AIF-1 mRNA expression.

Cortical neurons of Creutzfeldt-Jakob disease patients express the urokinase-type plasminogen activator receptor

Plasminogen belongs to the plasminogen activator system of cell signaling proteins and has recently been identified to bind to pathological prion protein PrPSC, but not to its normal conformer, PrPC. Plasminogen binds specifically to the urokinase-type plasminogen activator receptor (uPAR) to promote pericellular proteolysis, regulate integrin function, and mediate cell signaling. By using immunohistochemistry, we observed that significantly more cortical neurons in eight postmortem brains of patients who died with sporadic Creutzfeldt-Jakob disease (CJD) are immunoreactive for uPAR compared with controls. These data provide the pathophysiological basis for detailed analyses of the role of the plasminogen activator system in CJD and related diseases.

Cerebral localization and regulation of the cell volume-sensitive serum- and glucocorticoid-dependent kinase SGK1

The serum- and glucocorticoid-dependent kinase SGK1 is regulated by alterations of cell volume, whereby cell shrinkage increases and cell swelling decreases the transcription, expression and activity of SGK1. The kinase is expressed in all human tissues studied including the brain. The present study was performed to localize the sites of SGK1 transcription in the brain, to elucidate the influence of the hydration status on SGK1 transcription and to explore the functional significance of altered SGK1 expression. Northern blot analysis of human brain showed SGK1 to be expressed in all cerebral structures examined: amygdala, caudate nucleus, corpus callosum, hippocampus, substantia nigra, subthalamic nucleus and thalamus. In situ hybridization and immunohistochemistry in the rat revealed increased expression of SGK1 in neurons of the hippocampal area CA3 after dehydration, compared with similar slices from brains of euvolaemic rats. Additionally, several oligodendrocytes, a few microglial cells, but no astrocytes, were positive for SGK1. The abundance of SGK1 mRNA in the temporal lobe, including hippocampus, was increased by dehydration and SGK1 transcription in neuroblastoma cells was stimulated by an increase of extracellular osmolarity. Co-expression studies in Xenopus laevis oocytes revealed that SGK1 markedly increased the activity of the neuronal K+ channel Kv1.3. As activation of K+ channels modifies excitation of neuronal cells, SGK1 may participate in the regulation of neuronal excitability.

Macrophage/microglial cell subpopulations in glioblastoma multiforme relapses are differentially altered by radiochemotherapy

Following surgical removal of glioblastoma multiforme (GBM), radiochemotherapy impedes neoplastic outgrowth and relapse formation. Macrophages/microglial cells are believed to be potent mediators of the host defense system in GBM. However, little is known about their alteration by postsurgical therapies. We have now analyzed expression of LCA (leucocyte common antigen), CD68 (phagocytic cells), HLA-DR, -DP, -DQ (MHC class II), MRP-8 (myeloid-related protein, S100A8), MRP-14 (S100A9), LCF (lymphocyte chemoattractant factor, IL-16) and NOS II (inducible nitric oxide synthase) in macrophages/microglial cells in 39 GBM relapses and their matched primary tumors. Following surgery of the primary tumors, 15 patients received irradiation and chemotherapy, 17 irradiation and 7 no treatment. In irradiated relapses, we observed significantly more macrophages/microglial cells expressing MRP-14 compared to untreated GBM relapses. Furthermore, we observed a significant increase of CD68 expressing macrophages/microglial cells in patients without postsurgical treatment, but not in those with radiochemotherapy. In conclusion, our findings suggest that radiochemotherapy alters the number of MRP-14 expressing cells. The lacking increase of CD68 expressing cells in patients with radiochemotherapy suggests depletion of this cell type by postsurgical therapy.

AMP deaminase in rat brain: localization in neurons and ependymal cells

The purine nucleotide cycle enzyme AMP deaminase (AMPD) catalyzes the irreversible hydrolytic deamination of AMP. The physiological function of the purine nucleotide cycle in the brain is unknown. In situ hybridization and immunocytochemical studies were performed to identify the regional and cellular expression of AMPD in rat brain with the goal of elucidating the neural function of the purine nucleotide cycle. AMPD messenger RNA was detected in ventricular ependymal cells and cells of the choroid plexus and in neurons of distinct brain areas. Although only low antibody titers were obtained by immunization with the purified sheep brain AMPD, immunization of mice with synthetic lipopeptide vaccines containing oligopeptides derived from a known partial complementary DNA sequence of the enzyme yielded an antiserum suitable for immunocytochemistry. Immunostaining of cells in culture showed that neurons but not astroglial cells express appreciable amounts of the enzyme. Results of immunocytochemical staining performed on rat brain slices were in accord with the localization of AMPD messenger RNA, thus confirming the expression of AMPD in neurons of the brain stem, hippocampus, cerebellar nuclei and mesencephalic nuclei, as well as in ventricular ependymal cells and their cilia.

Recombinant measles viruses expressing altered hemagglutinin (H) genes: functional separation of mutations determining H antibody escape from neurovirulence

Measles virus (MV) strain CAM/RB, which was adapted to growth in the brain of newborn rodents, is highly neurovirulent. It has been reported earlier that experimentally selected virus variants escaping from the monoclonal antibodies (MAbs) Nc32 and L77 to hemagglutinin (H) preserved their neurovirulence, whereas mutants escaping MAbs K71 and K29 were found to be strongly attenuated (U. G. Liebert et al., J. Virol. 68:1486-1493, 1994). To investigate the molecular basis of these findings, we have generated a panel of recombinant MVs expressing the H protein from CAM/RB and introduced the amino acid substitutions thought to be responsible for antibody escape and/or neurovirulence. Using these recombinant viruses, we identified the amino acid changes conferring escape from the MAbs L77 (377R-->Q and 378M-->K), Nc32 (388G-->S), K71 (492E-->K and 550S-->P), and K29 (535E-->G). When the corresponding recombinant viruses were tested in brains of newborn rodents, we found that the mutations mediating antibody escape did not confer differential neurovirulence. In contrast, however, replacement of two different amino acids, at positions 195G-->R and 200S-->N, which had been described for the escape mutant set, caused the change in neurovirulence. Thus, antibody escape and neurovirulence appear not to be associated with the same structural alterations of the MV H protein.

Loss of heterozygosity at 11p15 and p53 alterations in malignant gliomas

PURPOSE

Malignant gliomas are the most frequent primary brain tumors. Recent studies defined several genetic markers, which might characterize molecular-biological subsets of glioblastomas with prognostic implications. In the later steps of tumor-progression, deletions on chromosome 11p15 and mutations of the tumor suppressor gene p53 were determined for different malignancies. To elucidate the involvement of 11p15 deletions in the tumorigenesis of malignant gliomas, we analyzed a series of 50 glioblastomas for loss of heterozygosity (LOH).

METHODS

Paired tissue and blood samples from 50 patients with glioblastoma multiforme were included. Microsatellite markers located on 11p15.1-11p15.5 were used for LOH analysis. Additionally, mutation analysis of the tumor suppressor gene p53 was performed, which might correlate with favorable survival in glioblastomas.

RESULTS

The region 11p15.4-5 was deleted heterozygously in 28% of cases representing 15 cM. Twenty-six glioblastomas did not show allelic loss for any locus. Our data revealed close association of LOH 11p15 with p53 mutations, and survival analysis showed a trend indicating better prognosis in glioblastomas characterized by LOH 11p15.

CONCLUSION

In the tumorigenesis of malignant gliomas, p53 mutations and 11p15 deletions seem to indicate a genetic subset of tumors with favorable prognostic value.

Differential activation of microglial cells in local and remote areas of IRBP1169-1191-induced rat uveitis

Using a Lewis rat model of interphotoreceptor retinoid binding protein (IRBP)-induced experimental autoimmune uveitis (EAU) we examined cellular reactions in the optic pathway (retina, choroid, optic nerve, optic tract, colliculus superior, and visual cortex). Two to six animals were studied at days 0, 7, 9, 11, 12, 13, 14, 18 and 22 after immunization by immunohistochemistry with monoclonal antibodies against ED , ED2, OX6, OX22, EMAP II, AIF-1 and W3/13. In the retina, choroid and distal optic nerve increased immunoreactivity to ED1, OX6, OX22, EMAP II, AIF-1 and W3/13 was initially observed at day 9, peaked at days 13-14 and diminished rapidly from day 18 onwards. No changes were seen in the density of ED2-positive resident macrophages. In the optic tract, ED1 and OX6 expression was induced in microglial cells beginning with day 11 and persisted until day 22. AIF-1, EMAP II and ED2 expression was not visibly up-regulated and no lymphocytic infiltrates (OX22-, W3/13-positive cells) were observed. In the central projection fields, no cellular reaction could be found. Thus, cellular response in IRBP-induced rat uveoretinitis is not restricted to the eye. Microglial activation is also seen in the distal optic nerve and optic tract. This remote microglial activation, however, differs in intensity, time course and expression of activation markers, thus indicating different activation cascades. The mild remote microglial activation is probably due to neuronal-microglial interactions resulting from neuronal damage in the retinal ganglion cell layer and nerve fiber layer with consecutive axonal degeneration and not from an inflammatory reaction as seen in the eye.

Galectin-3: cellular distribution and correlation with WHO-grade in human gliomas

In order to elucidate the reason for conflicting results that have been published previously on galectin-3 expression in human gliomas, we used single labeling and double labeling immunohistochemistry experiments to identify cellular origin and extent of galectin-3 positivity in 53 glioma-samples (16 glioblastomas, 21 anaplastic astrocytomas, 16 low-grade astrocytomas). Galectin-3 positivity was observed in neoplastic astrocytes, macrophages/microglial cells. endothelial cells and some B- and T-lymphocytes. The quantitative analysis showed that the percentage of galectin-3 positive cells was significantly higher in the tumor parenchyma of glioblastomas than in anaplastic (p = 0.0371) and low-grade astrocytomas (p = 0.0042). Single labeling with anti-CD68 antibodies revealed a significant correlation between CD68 and galectin-3 immunoreactivity (p = 0.0092). Endothelial cells were labeled in all low-grade and anaplastic astrocytomas, but only in 10/16 glioblastomas (p = 0.0003). This detailed analysis demonstrates that galectin-3 positivity in human gliomas is considerably influenced by tumor-infiltrating macrophages. The differential expression on endothelial cells raises the question if galectin-3 plays a role in tumor angiogenesis of human gliomas.

Localization of endostatin in rat and human gliomas

BACKGROUND

Endostatin is a potent inhibitor of endothelial cell proliferation, angiogenesis, and tumor growth. Its occurrence and localization has not yet been examined in human brain tumors. The authors report the production of a monoclonal antibody and detection of endostatin in rat and human gliomas by immunohistochemistry.

METHODS

The authors analyzed localization and tissue distribution of endostatin in 41 paraffin embedded glioma samples (18 glioblastoma multiforme, 7 WHO Grade III astrocytomas, 13 fibrillary, and 3 protoplasmic WHO Grade II astrocytomas) of human origin and 21 rat C6 gliomas by immunohistochemistry. Double labeling experiments confirmed the origin of endostatin-labeled cells.

RESULTS

Endostatin immunoreactivity was detected in tumor cells, endothelial cells, macrophages, and lymphocytes of both rat and human gliomas. The percentage of cells labeled with the endostatin antibody was significantly lower (P = 0.0126) in the tumor parenchyma of human glioblastomas than in WHO Grade II astrocytomas.

CONCLUSIONS

Endostatin was present in various cell types in rat and human gliomas in vivo. Lower levels in glioblastomas than in WHO Grade II astrocytomas might have reflected the shift of a probable regulatory balance between promoters and inhibitors of angiogenesis towards facilitation of neovascularization.

Differential cellular accumulation of connective tissue growth factor defines a subset of reactive astrocytes, invading fibroblasts, and endothelial cells following central nervous system injury in rats and humans

In brain injury, the primary trauma is followed by a cascade of cellular and molecular mechanisms resulting in secondary injury and scar formation. Astrogliosis and expression of transforming growth factor beta (TGF-beta) are key components of scar formation. A cytokine mediating the effects of TGF-beta is connective tissue growth factor (CTGF), a fibrogenic peptide encoded by an immediate early gene with suggested roles in tissue regeneration and aberrant deposition of extracellular matrix. In order to investigate CTGF in traumatic lesions, we evaluated 20 human brains with traumatic brain injury (TBI) and 18 rat brains with stab wound injury. Compared to remote areas and unaltered control brains, CTGF+ cells accumulated in border zones of the traumatic lesion site (p < 0.0001). In the direct peri-lesional rim, CTGF expression was confined to invading vimentin+, GFAP- fibroblastoid cells, endothelial and smooth muscle cells of laminin+ vessels, and GFAP+ reactive astrocytes. In the direct peri-lesional rim, CTGF+ astrocytes (>80%) co-expressed the activation associated intermediate filaments nestin and vimentin. In injured rat brains, numbers of CTGF+ cells peaked at day 3 and 7 and decreased to almost base level 3 weeks postinjury, whereas in humans, CTGF+ cells remained persistently elevated up to 6 months (p < 0.0001). The restricted accumulation of CTGF+-reactive astrocytes and CTGF+ fibroblastoid cells lining the adjacent laminin+ basal lamina suggests participation of these cells in scar formation. Furthermore, peri-lesional upregulation of endothelial CTGF expression points to a role in blood-brain barrier function and angiogenesis. In addition, CTGF appears to be a sensitive marker of early astrocyte activation.

In vivo expression of insulin-like growth factor-binding protein-2 in human gliomas increases with the tumor grade

Human central nervous system tumors and glioma cell lines highly express the insulin-like growth factor-binding protein (IGFBP)-2. As IGFBP-2 can affect tumor growth, we studied the relationship between IGFBP-2 expression and the malignancy of brain tumors in vivo. To do so, we investigated by immunohistochemistry the accumulation of IGFBP-1, -2, and -3 in 50 human gliomas classified by the WHO Malignancy Scale. Double labeling using anti-CD68 (monocytes/macrophages), antiglial fibrillary acidic protein, and anti-CD3 (T cells) antibodies was performed to further characterize the IGFBP-1, -2, and -3(+) cells. The expression of IGFBP messenger RNAs (mRNAs) was tested by RT-PCR in tumor samples from nine gliomas of different grades and in eight cell lines representing the cellular composition of human glioma. As controls, the accumulation of IGFBP-2 was investigated in normal brain and in the rat C6 glioblastoma model. IGFBP-1 and -3 accumulated in endothelial and macrophage/microglial cells. IGFBP-2(+) macrophage/microglial and glioma cells clustered in the immediate vicinity of focal necrosis of the human gliomas as well as of the rat C6 glioblastoma. The labeling score of IGFBP-1 accumulation in endothelial cells correlated negatively (P: = 0.0229), and that of IGFBP-2 accumulation in glioma cells correlated positively (P: < 0.0006) with the tumor grade of the gliomas. In addition, RT-PCR analysis confirmed mRNA expression of IGFBP-1, -2, and -3 by the gliomas and glial cells. Small amounts of IGFBP-1 and -3 mRNA, but high amounts of IGFBP-2 mRNA, were detectable in macrophage-like and glioma cell lines. The results suggest cell type-specific accumulation of IGFBP-1, -2, and -3 in human glial tumors of the brain. The increase in IGFBP-2 expression with this malignancy suggests a role of IGFBP-2 in the biology of human gliomas.

Human focal cerebral infarctions induce differential lesional interleukin-16 (IL-16) expression confined to infiltrating granulocytes, CD8+ T-lymphocytes and activated microglia/macrophages

Focal cerebral ischemia elicits a strong inflammatory response which readily participates in lipid oxygenation, edema formation, apoptotic cell death and tissue remodeling. Within these conditions, cytokines are key players of cell activation and are crucial for delayed mechanisms of ischemic damage. Mature IL-16 is an immunomodulatory cytokine, exerting CD4 dependent and independent effects and is characterized by chemotactic activity, induction of early gene phosphorylation, stimulation of pro-inflammatory IL-1beta, IL-6, TNFalpha expression in monocytic cells and also modulates apoptosis. We have now analyzed expression of IL-16 in 20 brains of patients following focal cerebral infarctions (FCI, n=20). Compared to normal control brains (n=3), IL-16 was expressed by infiltrating immune cells such as neutrophils, CD8+ lymphocytes and activated CD68+ microglia/macrophages accumulating in lesion associated reactive zones and in peri-vascular regions. IL-16+ cells accumulated significantly (P<0.0001) in the necrotic lesion and at bordering peri-lesional areas at day 1-2 reaching maximum levels at day 3-4 (P<0.0001). Also, peri-vascular IL-16+ cells reached maximum levels at day 3-4 (P<0.0001) following infarction and decreased after several weeks. During the early microglial activation period, IL-16+ microglia/macrophages coexpress the activation antigen MRP-8. The accumulation of IL-16+ granulocytes, IL-16+, CD8+ lymphocytes and activated IL-16+, CD68+, CD4- microglia/macrophages, early after infarction suggest a CD4 independent, paracrine role of IL-16 in the postinjury inflammatory response, such as recruitment and activation of immune cells leading to microvessel clustering and blood-brain barrier disturbance resulting in secondary damage.

Local distribution of microglia in the normal adult human central nervous system differs by up to one order of magnitude

Although microglia are considered to be a sensitive sensor for pathological processes in the central nervous system, there are only a few studies about the distribution and density of microglia in the normal human brain. Therefore, a study of local density of microglial cells was conducted by investigating 20 normal human brains with no clinical neurological symptoms or diseases and no neuropathological alterations. Microglial cells were visualized by immunolabeling of proteins which are known to be expressed either constitutively or facultatively, such as CD68, major histocompatibility complex class II (MHC-II), leukocyte common antigen (LCA), leukocyte chemotactic factor (LCF), macrophage inhibitory factor-related protein (MRP) 8, MRP14, CD4 and allograft-inflammatory factor-1 (AIF-1). CD68, MHC-II and AIF-1 showed the highest densities with significant regional differences ranging from 0.5% to 16.6% of all cells in the brain parenchyma with significantly more microglia in white than in gray matter. LCF and LCA showed a similar pattern of distribution as the proteins described above, but with lower percentages of microglial cells. CD4 was not found in the brain parenchyma. We conclude that CD68, MHC-II and AIF-1 define the main microglial cell population, whereas LCF and LCA are expressed by a subpopulation of microglial cells. The brains showed no or a negligible vascular expression of MRP8 and MRP14. Information about the local microglia density in the normal human brain can serve as a reference for the evaluation of pathological microglial responses.

IL-16 is differentially expressed in the developing human fetal brain by microglial cells in zones of neuropoesis

Microglial cells are regulators of tissue homeostasis in the adult central nervous system and readily participate in pathological processes, orchestrating tissue remodeling. Cytokines produced by microglial cells are markers of cell activation and contribute to reactive processes. In this paper, we have studied the expression of IL-16 (leukocyte chemoattractant factor), a natural soluble ligand to the CD4 molecule, in human fetal brains from the 11th to the 20th(.) week of gestation by immunohistochemistry. Interleukin (IL)-16(+) cells were detected already at the 11th gestational week, accumulating with aging in cortical layers (P<0.0001) at the 16th and 19th week, and reaching maximum numbers in the 20th week. Most IL-16(+) microglia (>80%) revealed morphological hallmarks of activated microglia. We observed that IL-16 cells coexpress LCA (>80%) and MRP-8, an activation-associated Ca(2+) binding S-100 family member (>80%). In contrast, only few IL-16(+) cells proliferated (PCNA(+), 20-40%) or co-expressed the HLA-DR, -DP, or -DQ antigen (<10%), and rare coexpression with CD68 (20-40%) was detected until 17th week. No coexpression with CD4, CD8 or CD20 was detected. Furthermore, we observed accumulation of IL-16(+) microglia in zones of neuronal proliferation, migration and differentiation. Increasing numbers of IL-16(+) cells were detected in bordering zones adjacent to the basal ganglia. Our data suggests that the early presence of IL-16(+) microglia exert a CD4-independent function-mediating activation, and chemotaxis of microglia precursors during neuronal development. In addition, IL-16 immunoreactivity might be a helpful tool to determine distinct developmental stages of microglial cells during fetal central nervous system ontogeny.

Preirradiation gemcitabine chemotherapy for newly diagnosed glioblastoma. A phase II study

BACKGROUND

The median survival for patients with glioblastoma is reported to be 12 months. To improve the outcome for glioblastoma patients, the authors evaluated the therapeutic efficacy of preirradiation gemcitabine chemotherapy followed by standard radiotherapy.

METHODS

Twenty-one patients with newly diagnosed glioblastoma were enrolled in a prospective unicenter trial of preirradiation gemcitabine chemotherapy. Chemotherapy included up to 4 monthly cycles of intravenous gemcitabine (Day 1, Day 8, and Day 15; 1000 mg/m2). Involved field radiotherapy was given after chemotherapy or earlier in the case of disease progression or gemcitabine intolerance.

RESULTS

With gemcitabine chemotherapy alone, there was a median progression free survival of 11 weeks and a progression free survival rate at 4 months of 24%. In 18 of 21 patients who subsequently received a full course of radiotherapy, the median progression free survival from the time of diagnosis was 8 months and the progression free survival rate at 12 months was 17% (3 of 18 patients). The median overall survival was 11 months. There was no specific treatment-related neurotoxicity reported. Neither age nor extent of residual postoperative tumor predicted the duration of progression free survival in patients treated with gemcitabine chemotherapy alone or in those treated with gemcitabine plus radiotherapy.

CONCLUSIONS

Gemcitabine followed by radiotherapy is a safe regimen for patients with newly diagnosed glioblastoma but the gemcitabine schedule used in the current study did not appear to confer any survival advantage compared with standard involved field radiotherapy alone.

Heme oxygenase-1 in lesions of human cerebral malaria

Human cerebral malaria is a life threatening complication of Plasmodium falciparum infection. The cascades of signaling events resulting in tissue trauma, lesion formation, coma or resolution of lesions are only slowly becoming unraveled. Understanding the generation of local tissue protective cellular reactions might pave the way for generation of novel drugs limiting the formation of cerebral malaria lesions. Heme oxygenase-1 (HO-1) is an inducible enzyme degrading heme into the gaseous mediator carbon monoxide (CO) and biliverdin, a local antioxidant. Expression of HO-1 is considered a protective reaction against inflammatory and other insults to the brain. We have localized HO-1 to Durck's granulomas, typical lesions of advanced cerebral malaria. Here, activated monocytic cells and ramified microglia in direct vicinity to the lesions express HO-1. The striking association of HO-1 expression with areas of bleedings suggests that released hemoglobin and heme-- known inducers of HO-1--are mainly responsible for induction of monocytic HO-1 expression. HO-1 is expressed rather late to play a protective role in lesion formation and appears to have only a major role in Durck's granulomas. Further, generation of the gaseous mediator CO might contribute to the neurological derangements of advanced cerebral malaria.

Cyclooxygenase (COX)-1 expressing macrophages/microglial cells and COX-2 expressing astrocytes accumulate during oligodendroglioma progression

Cyclooxygenases (COX, prostaglandin endoperoxide synthases, PGG/H synthases) are potent mediators of edema, impeding blood flow and immunomodulation in the pathologically altered brain. Two COX iso-enzymes have been associated with brain disease, the constitutively expressed COX-1 and the cytokine-inducible COX-2. We have used single and double labeling immunohistochemistry to analyse COX-1 and COX-2 expression in twenty-six primary WHO grade II oligodendrogliomas, sixteen primary WHO grade III anaplastic oligodendrogliomas, twenty-seven matched recurrences and ten neuropathologically unaltered brains. COX-1 immunoreactivity was predominantly observed in macrophages/microglial cells. The number of COX-1 expressing macrophages/microglial cells was significantly lower in primary oligodendrogliomas than in primary anaplastic oligodendrogliomas (P<0.0001) and in anaplastic oligodendroglioma relapses (P=0.011). Patients with low COX-1 labeling scores in the primary tumors had significantly longer time to progression and overall survival (P=0.0285) than those with high COX-1 labeling scores. COX-2 immunoreactivity was predominantly observed in disseminated neurons and astrocytes. In glioblastoma multiforme relapses, accumulation of COX-2 expressing astrocytes was observed surrounding areas of focal necrosis. The number of COX-2 expressing astrocytes was significantly (P=0.0471) lower in primary oligodendrogliomas than in high grade oligodendroglioma relapses. These data provide convincing evidence for the differential accumulation of cyclooxygenase isoforms during oligodendroglioma progression in vivo.

Allograft inflammatory factor-1 defines a distinct subset of infiltrating macrophages/microglial cells in rat and human gliomas

Allograft inflammatory factor-1 (AIF-1) is a Ca2+-binding peptide that constitutes a potential modulator of macrophage activation and function during the immune response of the brain. Peptides termed microglia response factor-1 or ionized calcium-binding adaptor molecule- have been reported to be identical with AIF-1. We have investigated the expression of AIF-1 in the rat C6 glioblastoma and 9L gliosarcoma tumor models and additionally assessed AIF- expression in a diverse range of human astrocytomas by immunohistochemistry. AIF-1 was expressed by activated microglial cells and a subset of infiltrating macrophages in areas of infiltrative tumor growth and in compact tumor areas in both rat and human gliomas. Double-labeling experiments in rats and humans characterized the nature and the functional status of AIF-1+ cells. AIF-1 expression was detected in cells expressing major histocompatibility complex class II molecules and in a subset of activated macrophages/microglial cells. All MRP-8+ cells coexpressed AIF-1. In humans, there was a strong correlation of AIF-1-expressing activated macrophages/microglial cells with tumor malignancy (P < 0.0001). These results suggest that AIF-1 defines a distinct subset of tumor-associated activated macrophages/ microglial cells.

Lesion-associated accumulation of uPAR/CD87- expressing infiltrating granulocytes, activated microglial cells/macrophages and upregulation by endothelial cells following TBI and FCI in humans

Urokinase-type plasminogen activator receptor (uPAR/CD87) together with its ligand, urokinase-type plasminogen activator (uPA), constitutes a proteolytic system associated with tissue remodelling and leucocyte infiltration. uPAR is a member of the glycosyl phosphatidyl inositol (GPI) anchored protein family. The functional role of uPAR comprises fibrinolysis by conversion of plasminogen to plasmin. In addition, uPAR promotes cell adhesion, migration, proliferation, re-organization of the actin cytoskeleton, and angiogenesis. Furthermore, uPAR is involved in prevention of scar formation and is chemoattractant to macrophages and leucocytes. In order to investigate the pathophysiological role of uPAR following human CNS injury we examined necrotic brain lesions resulting from traumatic brain injury (TBI; n = 28) and focal cerebral infarctions (FCI; n = 17) by immunohistochemistry. Numbers of uPAR+ cells and uPAR+ blood vessels were counted. Following brain damage, uPAR+ cells increased significantly within 12 h, reached a maximum after 3-4 days and remained elevated until later stages. uPAR was expressed by infiltrating granulocytes, activated microglia/macrophages and endothelial cells. Numbers of uPAR+ vessels increased in parallel subsiding earlier following FCI than post TBI. The restricted, lesion-associated accumulation of uPAR+ cells in the brain parenchyma and upregulated expression by endothelial cells suggests a crucial role for the influx of inflammatory cells and blood-brain barrier (BBB) disturbance. Through a failure in BBB function, uPAR participates in formation of brain oedema and thus contributes to secondary brain damage. In conclusion, the study defines the localization, kinetic course and cellular source of uPAR as a potential pharmacological target following human TBI and FCI.

A case of spinal glioblastoma multiforme: immunohistochemical study and review of the literature

A 31-year old female underwent subtotal resection of a spinal glioblastoma multiforme (GBM) at level D 10/11 in June 1997. Immunohistochemistry revealed increased MIB-1 labeling index and accumulation of p53 protein. Routine MRI in February 1998 showed multiple tumors of the lumbar spinal cord. At open biopsy, diffuse infiltration of multiple radices was seen. Histologically and immunohistochemically, the tumor was similar to the primary. In May 1998, MRI revealed multiple intracranial metastases and meningeal involvement. The patient died in June 1998, 13 months after the onset of symptoms. The lifes of patients with spinal gliomas are not endangered by direct compression of the brain stem, and systemic metastases are extremely uncommon with gliomas. Yet, survival times in the reported case and in the literature are not better than with cerebral localization. Analysis of the present case and a survey of the literature indicate that CSF involvement and consecutive intracranial seeding determine the prognosis of patients with spinal GBM. Thus, regular monitoring of CSF-cytology and/or spinal MRI appear to be advisable in spinal GBM.

Heme oxygenase (HO)-1 expressing macrophages/microglial cells accumulate during oligodendroglioma progression

Heme oxygenase (HO-1, HSP32) catalyzes the oxidation of heme to biliverdin and carbon monoxide, a putative neurotransmitter. In the brain, HO-1 expression has been associated with neuroprotection during oxidative stress and hypoxia. However, consecutive downstream mediation is involved in neoangiogenesis and consequent neoplastic outgrowth. We have analyzed HO-1 expression in 69 oligodendroglioma tissue samples, in rat intracranially transplanted C6 gliomas, and neuropathologically unaltered control brains by immunohistochemistry. Double labeling experiments confirmed the nature of HO-1 expressing cells. Reverse transcription-polymerase chain reaction was used to demonstrate HO-1 gene expression. HO-1 immunoreactivity was predominantly observed in macrophages/microglial cells. The number of HO-1 expressing macrophages/microglial cells was significantly lower in primary oligodendrogliomas than in their matched relapses (P<0.0001) and lower in primary anaplastic oligodendrogliomas than in their relapses (P=0.0006). Prominent accumulation of HO-1 expressing macrophages/microglial cells was observed in perinecrotic areas of both experimental rat and human glioblastoma relapses. HO-1 expressing neurons, macrophages/microglial cells and astrocytes were scattered in areas of infiltrative tumor growth. Surprisingly, HO-1 mRNA was detected in only one glioblastoma multiforme relapse. We conclude from these data that HO-1 expressing macrophages/microglial cells accumulate during oligodendroglioma progression in areas of focal necrosis. However, overall biological function of this phenomenon remains to be determined.