Analysis of TP53 and PTEN in gliomatosis cerebri

Gliomatosis cerebri (GC) is a rare glial neoplasm with extensive diffuse brain infiltration but relative preservation of the underlying architecture. Previous molecular studies, mostly analyzing biopsy samples, have suggested an astrocytic origin of GC, but a larger collective of autopsy tissue has not been investigated so far. Furthermore, whether the widespread neoplastic infiltration is based on a monoclonal process is still a matter of debate. In the present study, we screened paraffin-embedded brain tissue from different areas of 18 cases (8 autopsy cases and 10 biopsies) for alterations in the TP53 and PTEN genes. Nuclear accumulation of p53 protein was detected in 9 cases (50%). Somatic TP53 mutations occurred in two autopsy cases (11% of all cases). In the first case, a C-->T transition in codon 273 (Arg-->Cys) was detected in all tumor samples. In the second case, in tumor samples from one hemisphere, nuclear accumulation of p53 was caused by a G-->A transition in codon 244 (Gly-->Asp). In the present series, no mutations within the coding region of PTEN were found. Pten expression was observed in two autopsy cases (25%) and seven biopsy samples (70%). These data suggest that TP53 is affected in some cases, but other yet-unidentified genetic alterations might contribute to tumorigenesis in GC. Furthermore, although GC might be a monoclonal process, the presence of different tumor clones cannot be ruled out.

Accumulation of the proinflammatory cytokine endothelial-monocyte-activating polypeptide II in ramified microglial cells in brains of Borna virus infected Lewis rats

Borna disease virus (BDV) infection of adult Lewis rats induces a severe and often fatal neurologic disease characterized by a massive mononuclear meningo-encephalitis, and activation of microglial cells. Therefore, we analyzed expression of endothelial monocyte activating polypeptide II (EMAP II) by immunohistology as a marker for activation of microglial cells in BDV infected rat brains. EMAP II is a chemotactic peptide, inducing activation of macrophages and endothelial cells, and is considered a proinflammatory mediator of the innate immune system. An up to 30-fold increase in numbers of EMAP II+ microglial cells and a massive expression by infiltrating macrophages at perivascular inflammatory foci was observed in infected brains, with a maximum on day 25 after infection. These results provide evidence that EMAP II contributes to immune responses in inflammatory processes caused by viral infections.

Lesional expression of a proinflammatory and antiangiogenic cytokine EMAP II confined to endothelium and microglia/macrophages during secondary damage following experimental traumatic brain injury

We analyzed expression of Endothelial Monocyte-Activating Polypeptide II (EMAP II), a proinflammatory, antiangiogenic cytokine in rat brains after stab wound injury and observed a highly significant (p<0.0001) lesional accumulation confined to microglia/macrophages. Maximum numbers were seen at day 5 declining until 21 days after injury. Further, EMAP II(+) microglia/macrophages formed clusters in perivascular Virchow-Robin spaces. Prolonged accumulation of EMAP II(+), ED1(+) microglia/macrophages and increased lesional numbers of EMAP II(+) endothelial/smooth muscle cells during the acute postinjury period might indicate that EMAP II enrich the proinflammatory and antiangiogenic repertoire of effector molecules expressed by activated microglia/macrophages during secondary damage.

Cyclooxygenase-1 and -2 in brains of patients who died with sporadic Creutzfeldt-Jakob disease

Cyclooxygenases (COXs) mediate inflammation, immunomodulation, blood flow, apoptosis, and fever in various diseases of the brain. Whereas COX-2 is cytokine inducible, COX-1 is expressed by macrophages/microglial cells that accumulate in pathological foci. We analyzed the localization of COX-1 and COX-2 in postmortem cortex slices of eight patients who died with sporadic Creutzfeldt-Jakob disease (CJD) and four neuropathologically unaltered controls by immunohistochemical double-labeling, reverse transcriptase polymerase chain reaction (RT-PCR), and Western blotting experiments. In healthy brains, COX-1 was expressed by single macrophages/microglial cells and COX-2 by disseminated neurons. In patients with CJD, significantly (p = 0.0195) more COX-1-expressing macrophages/microglial cells were detected adjacent to neurons. COX-2 expression was predominantly observed in neurons, and their number was significantly higher (p < 0.0001) compared to controls. RT-PCR and Western blotting revealed more COX-1 and COX-2 mRNA and protein in one CJD patient than in one control patient. These data show that accumulation of COX-1-expressing macrophages/microglial cells and COX-2-expressing neurons might represent important regulatory mechanisms in the complex process of neuronal degeneration in CJD patients.

Aberrant neuronal and paracellular deposition of endostatin in brains of patients with Alzheimer's disease

Cerebrovascular pathology is common in Alzheimer's disease (AD) and is considered to contribute to cerebral malfunction. However, distinct antiangiogenic proteins that accumulate in AD brains have not yet been identified. Endostatin is a 20 kDa C-terminal fragment of collagen XVIII that, when added exogenously, inhibits endothelial proliferation and migration in vitro and angiogenesis and tumor growth in vivo by inducing apoptosis in endothelial cells. We produced a monoclonal antibody directed against endostatin and observed significantly more (p < 0.0001) immunoreactive cortical neurons in AD brains compared with age-matched neuropathologically unaltered controls. High numbers of extracellular and frequently perivascular endostatin deposits were detected in the cerebral hemispheres. Double-labeling experiments revealed colocalization of endostatin in amyloid-beta(1-40) (Abeta(1-40)), tau protein, and periodic acid-Schiff stain-positive plaques that were surrounded by focal gliosis. Western blotting revealed more 20 kDa endostatin in an AD patient compared with a control. In unstimulated SKNSH supernatants, endostatin was detected that increased predominantly after hypoxia in supernatants and cellular lysates. Abeta(1-40) (80 microg/ml) supplementation to SKNSH neurons for 24 hr completely abolished the release of endostatin. These data show that endostatin is released by neurons to accumulate in amyloid plaques in Alzheimer's disease. Induction by hypoxia and complete abrogation of endostatin release after Abeta(1-40) challenge reveals intricate interactions between the two proteins and opens new avenues for the development of novel treatment strategies of AD patients.

Release of regulators of angiogenesis following Hypocrellin-A and -B photodynamic therapy of human brain tumor cells

Photodynamic therapy (PDT) is an innovative strategy for the treatment of solid neoplasms of the brain. Aside from inducing cell death in tumor cells, PDT induces endothelial cell death and promotes formation of blood clots; however, exact mechanisms that trigger these phenomena remain largely unknown. We now used Western blotting to analyze secretion of regulators of angiogenesis to the supernatants of one glioma, one macrophage, and one endothelial cell line following Hypocrellin-A and -B photodynamic therapy. We observed induction of proangiogenic VEGF (vascular endothelial growth factor) and of antiangiogenic sFlt-1, angiostatin, p43, allograft inflammatory factor-1, and connective tissue growth factor. Release of thrombospondin-1 was diminished in a glioma cell line supernatant. Endostatin release was induced in glioma cells and reduced in macrophages and endothelial cells. These data show that a wide range of antiangiogenic factors are secreted by brain tumor cells following Hypocrellin photochemotherapy. However, VEGF release is also induced thus suggesting both favorable and deleterious effects on tumor outgrowth.

Gliomatosis cerebri: molecular pathology and clinical course

Gliomatosis cerebri is a rare, diffusely growing neuroepithelial tumor characterized by extensive brain infiltration involving more than two cerebral lobes. Among 13 patients with gliomatosis cerebri (median age, 46 years), biopsies showed features of diffuse astrocytoma (n = 4), oligoastrocytoma (n = 1), anaplastic astrocytoma (n = 5), anaplastic oligoastrocytoma (n = 1), or glioblastoma (n = 2). Molecular genetic investigation showed TP53 mutations in three of seven tumors and both PTEN mutation and epidermal growth factor receptor overexpression in one tumor. Amplification of CDK4 or MDM2 or homozygous deletion of CDKN2A was not detected. Three of 10 patients receiving radiotherapy showed a partial response (one patient) or had stable disease (two patients) lasting for more than 1 year. Four of six patients treated with procarbazine, carmustine, vincristine chemotherapy demonstrated partial remission (one patient), minor response (two patients), or stable disease (one patient). Median survival time from diagnosis was 14 months (range, 4-91+ months). Infratentorial involvement was associated with shorter survival. We conclude that (1) the molecular genetic alterations in gliomatosis cerebri resemble those in diffuse astrocytomas; (2) the prognosis of gliomatosis cerebri is variable but for at least 50% of patients as poor as for glioblastoma; and (3) some patients respond to radiotherapy and/or procarbazine, carmustine, vincristine chemotherapy.

Accumulation of endostatin/collagenXVIII in brains of patients who died with cerebral malaria

Endostatin is a 20 kDa C-terminal fragment of collagenXVIII that, when added exogenously, inhibits angiogenesis by inducing apoptosis of endothelial cells. In cerebral malaria (CM), blood-brain barrier dysfunction is a hallmark alteration in the formation of edema, inflammation, hemorrhage and Dürck's granulomas that are thought to represent the histopathological basis of neurological impairments observed in CM patients. We now analyzed endostatin/collagenXVIII expression in brains of seven patients who died with CM and in seven control patients by immunohistochemistry double-labeling experiments. Endostatin/collagenXVIII immunoreactive macrophages/microglial cells accumulated predominantly in Dürck's granulomas. Some immunoreactivity was observed in macrophages located in cerebral capillaries with deposition of malarial pigment and sequestration, but almost no immunoreactivity was detected in ring hemorrhages. Focal accumulation of endostatin/collagenXVIII in granulomas but not in ring hemorrhages of CM brains suggests a novel process that is involved in the destruction of endothelial cells at the time of Dürck's granuloma formation.

Expression of EMAP-II by activated monocytes/microglial cells in different regions of the rat hippocampus after trimethyltin-induced brain damage

Endothelial monocyte-activating polypeptide-II (EMAP-II), a novel cytokine with proinflammatory and antiangiogenic properties, has previously been shown to be expressed by activated monocytes/microglial cells in the rat brain and was therefore considered a useful marker to stage microglial activation in inflammatory lesions. The aim of the present immunohistochemical study was to investigate expression of EMAP-II in the rat hippocampus after intoxication with the organotin compound trimethyltin (TMT). Administration of this neurotoxicant is known to produce brain damage mainly affecting the hippocampal formation, with severe neuronal cell loss being observed predominantly in regions CA-1 and CA-3. The maximum severity of TMT-induced brain damage is observed 21 days after a single ip administration. In this well-characterized model of neurodegeneration, activated microglial cells have been described to occur mainly in the early stages of TMT-induced neurotoxicity. Following TMT intoxication, we observed a significant increase in EMAP-II(+) monocytes/microglial cells in the CA-1 and the CA-3 regions. The CA-2 region, however, was largely spared. While appearance of single EMAP-II(+) microglial cells was observed already after 5 days, EMAP-II immunoreactivity reached its maximum after 21 days and persisted in some of the rats up to 35 days. These findings show a close correlation to the temporal and spatial pattern of neuronal damage described in the rat hippocampus after TMT administration previously. Thus, upregulation of EMAP-II by activated monocytes/microglial cells may serve as a sensitive marker of neurotoxic lesions in the rat brain.

The impact of progesterone receptor expression on relapse in the long-term clinical course of 93 benign meningiomas

BACKGROUND

Previous clinicopathological observations have pointed towards an impact of progesterone receptor (PgR) expression on the clinical course of meningiomas.

MATERIALS AND METHODS

EXpression of PgR and the proliferation marker MIB-1 was assessed by immunohistochemistry in the primary tumours of 30 cases of benign, completely resected, recurrent meningiomas and compared with 63 cases of meningioma without recurrence for 14 or more years.

RESULTS

Univariate analysis showed a significantly higher risk for recurrence (odds ratio 3.533) for tumours with a low expression of PgR. A tendency for a higher risk for tumours with higher proliferation rate (odds ratio 6.889) was not significant. In 20 cases in which the primary tumour could be compared with its recurrence, no consistent changes of PgR expression were observed.

CONCLUSION

Our findings support previous studies that found an association of low or absent expression of PgR with a higher risk of recurrence. This encourages attempts at a hormonal therapy for patients with PgR-positive meningioma.

CD14 expression by activated parenchymal microglia/macrophages and infiltrating monocytes following human traumatic brain injury

The immune response in the central nervous system (CNS) is under tight control of regulatory mechanisms, resulting in the establishment of immune privilege. CNS injury induces an acute inflammatory reaction, composed mainly of invading leukocytes and activated microglial cells/macrophages. The generation of this robust immune response requires binding of receptors such as CD14, a pattern recognition receptor of the immune system. CD14, a surface molecule of monocytic cells, is up-regulated after monocyte stimulation and is involved in cellular activation. To examine CD14 expression in human brain lesions we investigated sections of brains obtained at autopsy from 25 cases following closed traumatic brain injury (TBI) and 5 control brains by immunohistochemistry. Detection of CD14 in controls demonstrated constitutive expression by perivascular cells, but not in parenchymal microglial cells, equivalent to known expression pattern of ED2 in rats. Following TBI, numbers of CD14(+) cells in perivascular spaces and in the brain parenchyma increased in parallel within 1-2 days, both at the lesion and in adjacent perilesional areas. The number of CD14(+) cells in perivascular spaces and in the brain parenchyma reached maximum levels within 4-8 days and remained elevated until weeks after trauma. In contrast to activated parenchymal microglia/macrophages, resting parenchymal microglial cells lacked CD14. Thus, early CD14 expression constitutes an essential part of the acute inflammatory CNS response following trauma.

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.

Persistent accumulation of cyclooxygenase-1-expressing microglial cells and macrophages and transient upregulation by endothelium in human brain injury

OBJECT

Secondary damage after central nervous system (CNS) injury is driven in part by oxidative stress and CNS inflammation and is substantially mediated by cyclooxygenases (COXs). To date, the rapidly inducible COX-2 isoform has been primarily linked to inflammatory processes, whereas expression of COX-1 is confined to physiological functions. The authors report the differential localization of COX-1 in human traumatic brain injury (TBI).

METHODS

Differential cellular COX-1 protein expression profiles were analyzed following TBI in 31 patients and compared with neuropathologically unaltered control brains by using immunohistochemistry. In these patients with TBI, a significant increase of COX-1 protein expression by vessel endothelial and smooth-muscle cells and CD68+ microglia/macrophages was observed to be strictly confined to the lesion. Accumulation of COX-1+ microglia/macrophages in the lesion was already evident 6 hours postinjury, reaching maximal levels after several weeks and remaining elevated at submaximal levels for several months after injury. Furthermore, COX-1+ cell clusters were located in the Virchow-Robin space during the leukocyte infiltration period from Days 4 to 8 after TBI. Double-labeling experiments confirmed coexpression of COX-1 by CD68+ microglia/macrophages. The numbers of COX-1+ vessel endothelial and smooth-muscle cells increased from Day 1, remaining at submaximal levels for months after injury.

CONCLUSIONS

The prolonged accumulation of COX- 1+ microglia/macrophages that were restricted to perilesional areas affected by the acute inflammatory response points to a role of COX-1 in secondary injury. The authors have identified localized, accumulated COX- I expression as a potential pharmacological target following TBI. Their results challenge the current paradigms of a selective COX-2 role in the postinjury inflammatory response.

A functional role of HLA-G expression in human gliomas: an alternative strategy of immune escape

HLA-G is a nonclassical MHC molecule with highly limited tissue distribution that has been attributed chiefly immune regulatory functions. Glioblastoma is paradigmatic for the capability of human cancers to paralyze the immune system. To delineate the potential role of HLA-G in glioblastoma immunobiology, expression patterns and functional relevance of this MHC class Ib molecule were investigated in glioma cells and brain tissues. HLA-G mRNA expression was detected in six of 12 glioma cell lines in the absence of IFN-gamma and in 10 of 12 cell lines in the presence of IFN-gamma. HLA-G protein was detected in four of 12 cell lines in the absence of IFN-gamma and in eight of 12 cell lines in the presence of IFN-gamma. Immunohistochemical analysis of human brain tumors revealed expression of HLA-G in four of five tissue samples. Functional studies on the role of HLA-G in glioma cells were conducted with alloreactive PBMCs, NK cells, and T cell subpopulations. Expression of membrane-bound HLA-G1 and soluble HLA-G5 inhibited alloreactive and Ag-specific immune responses. Gene transfer of HLA-G1 or HLA-G5 into HLA-G-negative glioma cells (U87MG) rendered cells highly resistant to direct alloreactive lysis, inhibited the alloproliferative response, and prevented efficient priming of cytotoxic T cells. The inhibitory effects of HLA-G were directed against CD8 and CD4 T cells, but appeared to be NK cell independent. Interestingly, few HLA-G-positive cells within a population of HLA-G-negative tumor cells exerted significant immune inhibitory effects. We conclude that the aberrant expression of HLA-G may contribute to immune escape in human glioblastoma.

Galectin-3 labeling correlates positively in tumor cells and negatively in endothelial cells with malignancy and poor prognosis in oligodendroglioma patients

BACKGROUND

Galectin-3 modulates cell growth, transformation and metastasis in a wide range of neoplasms.

PATIENTS AND METHODS

We analyzed galectin-3 expression in a total of 69 oligodendroglioma tissue samples by immunocytochemistry double labeling and RT-PCR experiments.

RESULTS

Galectin-3 expression was observed in oligodendrocytes, endothelial cells and macrophages/microglial cells in areas of solid tumor growth. Significantly fewer galectin-3+ oligodendroglioma cells and macrophages/microglial cells were detected in WHO grade II oligodendrogliomas than in their matched relapses and in WHO grade III anaplastic oligodendrogliomas. Inversely, significantly more galectin-3+ endothelial cells were detected in WHO grade II oligodendrogliomas than in their matched relapses and in WHO grade III anaplastic oligodendrogliomas. Patients with low endothelial galectin-3 labeling scores in primary oligodendrogliomas and anaplastic oligodendrogliomas had significantly shorter time to progression and overall survival than patients with high endothelial galectin-3 labeling scores.

CONCLUSION

We conclude from these data that the cell-type specific expression of galectin-3 is differentially involved in oligodendroglioma pathology.

Infiltrating CD14+ monocytes and expression of CD14 by activated parenchymal microglia/macrophages contribute to the pool of CD14+ cells in ischemic brain lesions

CD14, a key pattern recognition receptor of the innate immune system, is a surface molecule on monocytic cells involved in cellular activation. We investigated 18 autopsy cases of focal cerebral infarctions (FCI) by immunohistochemistry to examine CD14 expression following ischemia. Controls confirmed constitutive CD14 expression by few perivascular cells. In contrast to quiescent CD14- parenchymal microglial cells, following ischemia activated microglia/macrophages expressed abundant CD14. In FCI, CD14+ cells increased both in perivascular spaces and in brain parenchyma within 1-2.5 days and remained elevated until late stages. Early CD14 expression suggests an essential part of CD14 in the acute inflammatory response following stroke.

Macrophages/microglial cells in patients with cerebral malaria

Cerebral malaria is a life threatening sequel of Plasmodium falciparum infection and contributes significantly to malaria mortality, especially among children. Accumulation of macrophages and proliferation of microglial cells play key roles in cerebral malaria and are thought to contribute to the pathophysiological alterations observed in these patients, which include enhanced adherence of infected erythrocytes to the cerebral vasculature by expression and secretion of proinflammatory molecules, disruption of the blood-brain barrier, recruitment of other inflammatory cells to the lesion site. In this review, recent advances in the understanding of the involvement of macrophages/microglial cells in the development of cerebral malaria are summarized.

The allograft inflammatory factor-1 family of proteins

The allograft inflammatory factor-1 (AIF-1) is a 17 kDa interferon-gamma-inducible Ca(2+)-binding EF-hand protein that is encoded within the HLA class III genomic region. Three proteins are probably identical with AIF-1 termed Iba1 (ionized Ca(2+)-binding adapter), MRF-1 (microglia response factor) and daintain. Considerable but not complete sequence identity with AIF-1 has been described for IRT-1 (interferon-responsive transcript), BART-1 (balloon angioplasty-responsive transcript), and other, yet unassigned alternatively spliced variants. In this review, genomic and functional characteristics of AIF-1-related proteins are summarized and a common nomenclature is proposed.

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.