CR3/43, a marker for activated human microglia: application to diagnostic neuropathology.
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Antibodies, Monoclonal↗
Biomedical subjects
M B Graeber
Publications and source records attributed to M B Graeber.
Surveillance, intervention and cytotoxicity: is there a protective role of microglia?
The study of microglial cell biology has become the key to understanding the brain's fundamental tissue reactions as well as the cellular mechanisms underlying CNS disease. This article focuses on glial-neuronal interactions with special reference to human pathology. Three important areas of brain pathology are critically reviewed: multiple sclerosis and CNS inflammation, the brain in AIDS and opportunistic infections, and neurodegenerative disorders. Although microglial cytotoxicity may cause bystander damage, e.g. in ischemia, there is little evidence to support the view that microglial activation per se is pathogenic. Results suggesting that one important normal function of microglia is to protect the integrity of the central nervous system are discussed. The concept is proposed that microglia function as a highly developed guardian to the CNS.
Animals↗
Development of the microglia literature.
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Bibliographies as Topic↗
Heterogeneity of microglial and perivascular cell populations: insights gained from the facial nucleus paradigm.
We reflect here on the development of a neuroimmunological concept which has been formulated over the past 5 years through studying microglial cell responses in the facial nerve system. A simple axotomy of the adult rat facial nerve which causes regeneration of facial motor neurons and little, if any, cell death can activate microglial cells just as easily as a full-blown degeneration of the entire nucleus induced by toxic ricin. In both instances, the prompt microglial reaction is characterized by a series of structural and phenotypic changes which are in many ways similar to an immune response, e.g., there is cell proliferation and upregulation of MHC antigens. However, since white blood cells do not participate in the retrograde response of facial motor neurons, we have adopted a notion which views microglia as a CNS-wide network of immunocompetent cells whose morphological dissimilarities from leukocytes are a result of their unique adaptation to the CNS architecture. We have continued our in vivo investigations of the phagocytic and immunophenotypic properties of microglial and perivascular cells during the retrograde reaction of facial motor neurons by using intra-neural injections of fluorogold (FG) and ricin followed by lectin and immunostaining for microglia. Two new findings can be added to the microglial neuroimmune network: (1) Microglia take up FG only after motor neuron degeneration, whereas perivascular cells may take up FG under nondegenerating conditions. (2) Immunologically important molecules, such as MHC class II, CD4, and leukocyte common antigens, are expressed by different microglial subpopulations. Thus there is functional and phenotypic heterogeneity among immunocompetent cells of the CNS.
Animals↗
Synaptic stripping in the human facial nucleus.
An autopsy case of severe peripheral facial nerve paresis with disconnection of synapses from facial motor neurons is reported. A 77-year-old man presented with left-sided otitis media and subsequent development of facial nerve paresis. Three months later, the patient died of an acute gastrointestinal bleeding from a chronic duodenal ulcer. Gross inspection of the brain revealed non-stenosing arteriosclerotic vascular changes and a single small cystic lesion in the right putamen. Microscopically, marked chromatolytic changes were observed in the left facial nucleus. Immunocytochemistry for synaptophysin revealed a marked loss of afferent synaptic contacts from somatic and stem dendritic surface membranes of all chromatolytic motor neurons. Wrapping of a number of neurons by newly formed glial fibrillary acidic protein-positive astrocytic cell processes could be detected in the regenerating facial motor nucleus. In addition, expression of HLA-DR was increased on a small number of microglia and perivascular cells. These changes were absent from the contralateral, normal-appearing facial nucleus. To our knowledge, this case provides the first evidence for disconnection of synapses following peripheral nerve lesioning in humans. Occurrence of synaptic stripping is likely to explain nuclear hyperexcitability and failure of recovery of complex fine motor movements that are commonly observed following peripheral injury to the facial nerve.
Aged↗
Four dinucleotide repeat polymorphisms at the D7S804 locus.
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Base Sequence↗
Fine mapping of the human SCIDX1 locus at Xq12-13.1.
Previous linkage analysis of families with X-linked severe combined immunodeficiency (SCIDX1) mapped this locus to a large region encompassing about 10 to 20 cM at Xq12-21. We have analyzed in SCIDX1 families the segregation of 7 highly polymorphic microsatellites repeats localized to this region, including a new polymorphic microsatellite at the DXS135 locus described in this study, to refine the mapping of this disease locus. The observations of genetic recombinants within the previously defined SCIDX1-region allow us to establish new flanking markers at the DXS135 and DXS227 loci, which significantly reduce the region harboring the SCIDX1 locus to a distance estimated between 3 to 5 cM. The existence of multiple, highly polymorphic markers in the refined SCIDX1 region will greatly improve the accuracy of carrier detection and prenatal diagnosis for SCIDX1.
Alleles↗
Non-radioactive direct sequencing of PCR products amplified from neuropathological specimens.
We have developed a simple, rapid and relatively inexpensive protocol for direct non-isotopic cycle sequencing of DNA amplified using the polymerase chain reaction (PCR). PCR is performed on routine and archival neuropathological tissue. For sequencing, a 5'-digoxigenin end-labelled oligonucleotide primer is annealed and extended during thermal cycling, sequencing reactions are separated on a standard sequencing gel and the gel is contact-blotted to a nylon membrane. Sequenced DNA is visualized using immunological detection of digoxigenin.
Base Sequence↗
Quantitative immunohistochemistry in the rat facial nucleus with [125I]-iodinated secondary antibodies and in situ autoradiography: non-linear binding characteristics of primary monoclonal and polyclonal antibodies.
Indirect immunohistochemistry is an important routine method in histology and histopathology. Here we have investigated the quantitative aspects of antibody binding to tissue sections, using a range of monoclonal and polyclonal antibodies and the regenerating rat facial nucleus as the experimental model. The in situ binding of primary antibodies was quantified using appropriate [125I]-iodinated secondary antibodies and quantitative autoradiography. The majority of primary antibodies revealed an apparently bell-shaped curve of in situ antibody binding, with the binding increasing up to a specific antibody concentration and then decreasing; similar data were also obtained with enzymatic immunohistochemistry. There was also a close correlation between the quantitative changes in antibody binding during the time course of facial nerve regeneration and those observed with enzyme histochemistry.
Animals↗
Delineation of the dystonia-parkinsonism syndrome locus in Xq13.
The X chromosome-linked dystonia-parkinsonism syndrome (XDP) is a severe movement disorder, characterized by both dystonia and parkinsonism. XDP is a genetically homogeneous disorder. Known ancestry of all patients has been traced back to Panay, Philippines, where the disease probably originated from a single mutation (founder effect). The gene locus, DYT3, has been previously assigned to the proximal long arm of the X chromosome (Xq12-q21.1). Using four dinucleotide tandem repeat (DNTR) sequences from Xq13-derived yeast artificial chromosomes (YACs), we further delineate DYT3 within Xq13. Observation of a recombination event between DYT3 and DNTR locus 4548-7, derived from a YAC encompassing locus DXS56, establishes 4548-7 as a distal flanking marker. Assignment of DYT3 to a region in Xq13, flanked by loci 4548-7 and DXS159, is further supported by highly significant allelic association between DYT3 and a total of four DNTR loci--PY2-31, PY5-10, 4548-1, and 4548-7--located in a region defined by PGK1 and DXS56. /phi/ and /delta/ values were 0.82/0.35, 0.78/0.42, 0.65/0.34, and 0.88/0.58 for PY2-31, PY5-10, 4548-1, and 4548-7 at P less than 10(-2), P less than 10(-4), P less than 10(-3), and P less than 10(-6).
Base Sequence↗
5'-Nucleotidase immunoreactivity of perineuronal microglia responding to rat facial nerve axotomy.
The ecto-enzyme 5'-nucleotidase was localized immunocytochemically in the axotomized rat facial nucleus. As revealed by the monoclonal antibody 5N4-2,5'-nucleotidase immunoreactivity markedly increased on perineuronal microglia during the first week following axotomy, and gradually disappeared from these cells by the end of the third post-operative week. Interestingly, parenchymal microglia were not or only weakly stained. These findings indicate that 5'-nucleotidase 5N4-2-immunoreactivity may serve as a marker for perineuronal microglia, a population of satellite glial cells that appear to be actively engaged in lesion-induced synaptic changes during regeneration.
5'-Nucleotidase↗
Isolation of DNTR polymorphisms from yeast artificial chromosomes encompassing X chromosomal loci PGK1 and DXS56.
Five dinucleotide tandem repeat (DNTR) sequences were isolated from yeast artificial chromosomes containing the PGK1 and DXS56 loci in Xq13. Sequence information of these DNTR loci is given. Four of the five DNTR sequences were polymorphic. Polymorphism information content values were 0.44, 0.49, 0.47, and 0.76 for loci PY5-10, PY2-31, 4548-1, and 4548-7, respectively. Corresponding heterozygosities were 0.55, 0.55, 0.56, and 0.78. These DNTRs are useful for the fine mapping of disease loci in Xq13 and provide sequence tagged sites for this region of the X chromosome.
Base Sequence↗
Contralateral early blink reflex in patients with facial nerve palsy: indication for synaptic reorganization in the facial nucleus during regeneration.
Fifty patients with Bell's palsy and 30 patients with etiologically different symptomatic peripheral facial nerve palsy were studied by means of electrically evoked blink reflexes 1-23 days after onset of paresis. Their results were compared with a normal control group of 30 healthy subjects. In a significant number of patients (64% in Bell's palsy and 53% in symptomatic facial nerve palsy) a contralateral early blink reflex response (R1) could be elicited upon stimulation of the normal side as compared to 13% in the control group. It is suggested that this result may be explained by synaptic reorganization of the facial nucleus leading to functional unmasking of pre-existing crossed trigemino-facial reflex pathways during regeneration. This view is in line with previous experimental data in animals on the time course of structural changes in the facial nucleus after lesioning of the ipsilateral facial nerve.
Adolescent↗
Ultrastructural location of major histocompatibility complex (MHC) class II positive perivascular cells in histologically normal human brain.
The expression of major histocompatibility complex (MHC) class I and II antigens was studied in surgical and postmortem brain biopsy tissue using light and electron microscopic immunocytochemistry. In addition, monoclonal antibodies directed against human macrophages (EBM11) and alpha-smooth muscle actin were applied. It is shown that blood vessel-associated MHC class II immunoreactivity in histologically normal human brain can be localized to a distinct class of cells, termed perivascular cells, which share macrophage but not smooth muscle cell antigen. This immunophenotype, the location in the perivascular space as well as the morphology, frequency and tissue distribution distinguish perivascular cells from pericytes and intraparenchymal microglia. It is suggested that MHC class II positive perivascular cells are a normal constituent of the human cerebral microvasculature. The potential role of these cells in immunological reactions occurring at the blood-brain interface is discussed.
Antibodies, Monoclonal↗
The X-linked dystonia-parkinsonism syndrome (XDP): clinical and molecular genetic analysis.
Dystonia and parkinsonism are two major representatives of movement disorders. The X-linked dystonia-parkinsonism syndrome (XDP) serves as a model system for the study of both dystonia and parkinsonism since both symptom complexes occur together and are inherited as Mendelian traits with very high penetrance. XDP, which is endemic to the Philippine island of Panay, originated by a single mutation ("genetic founder effect"), thus assuring homogeneity of the disorder at the molecular level. The disease locus, DYT3, has been assigned to the proximal long arm (Xq12-21.1) of the human X chromosome. A strategy is described to isolate this gene by positional cloning. The rationale of this strategy, the major methods involved and technical terms are explained.
Base Sequence↗
Dystonia-parkinsonism syndrome (XDP) locus: flanking markers in Xq12-q21.1.
The study of rare genetic forms of dystonia and parkinsonism permits positional cloning of genes potentially involved in more common, multifactorial forms of these diseases. One movement disorder amenable to molecular genetic analysis is the X-linked dystonia-parkinsonism syndrome (XDP). This disease is endemic to the Philippines where it originated by a genetic founder effect. Linkage analysis was performed with DNA from 14 XDP kindreds by using 12 polymorphic DNA sequences in Xp11-Xq22. Two-point analysis demonstrated maximum lod scores of 5.45, 4.95, 4.28, and 5.99 for DXS106, DXS159, PGK1, and DXS72, respectively, at recombination fractions of zero (DXS106 and DXS159), .01 (PGK1), and .04 (DXS72). Multipoint analysis resulted in a maximum-likelihood score (Zmax) of 8.41 with a (Zmax - 1) support interval of 9 cM between DXS159 and DXS72 (Xq12-q21.1). In 19 XDP kindreds significant linkage disequilibrium was found for loci DXS72 (delta = .47), PGK1 (delta = .36), DXS95 (delta = .30), DXS106 (delta = .28), and DXS159 (delta = .26). These data indicate that the gene mutated in XDP (locus DYT3) is located in Xq12-q21.1.
Chromosome Mapping↗
Synaptic 5'-nucleotidase is transient and indicative of climbing fiber plasticity during the postnatal development of rat cerebellum.
The transient appearance of 5'-nucleotidase, an adenosine-producing ecto-enzyme, was studied during specific stages of postnatal synaptogenesis in the rat cerebellum. For ultrastructural detection of 5'-nucleotidase activity, an enzyme-cytochemical technique was used. Between postnatal days 4 and 6, enzymatic reaction product was present in the synaptic clefts of climbing fibers containing the perisomatic spines, apical cones and emerging dendrites of Purkinje cells (CF-PC synapses). Labeled parallel fiber synapses were observed on dendritic shafts of cerebellar interneurons. At postnatal days 9 and 12, enzyme-positive parallel fiber terminals were in addition numerous on the spines of peripheral Purkinje branchlets, and gradually disappeared thereafter. Between postnatal days 8 and 15, labeling of perisomatic CF-PC contacts persisted. In contrast, climbing fiber synapses on Purkinje dendrites were only occasionally labeled. Between postnatal days 18 and 21, synaptic reaction product was restricted to mossy fibers. At the same time, association of 5'-nucleotidase with glial profiles was prominent throughout the cerebellar layers. In adult cerebellum (from 24 days onwards) all synapses were devoid of enzymatic activity. Throughout development, basket, stellate and Golgi cell synapses were devoid of enzymatic activity. We conclude that 5'-nucleotidase is present in excitatory cerebellar synapses during part of their generation period. The transient nature of this phenomenon suggests that 5'-nucleotidase may serve as a novel, cytochemical marker for a specific state of synaptic maturation, and in particular for climbing fiber plasticity. A role of 5'-nucleotidase in purinergic neuromodulation and cellular contact formation could be significant in these processes.
5'-Nucleotidase↗