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V H Perry

Publications and source records attributed to V H Perry.

At least 73 records · Page 4Linked to original sources
PubMed1998

Immunochemical detection of arylamine N-acetyltransferase during mouse embryonic development and in adult mouse brain.

Arylamine N-acetyltransferases (NATs) are important in susceptibility to xenobiotic-induced disorders (e.g., drug-induced autoimmune disease, bladder cancer), but their role in endogenous metabolism is yet to be elucidated. The discovery that human NAT1 acts upon p-aminobenzoylgluatamate (p-ABG) to generate p-acetamidobenzoylglutamate (p-AABG), a major urinary metabolite of folic acid, suggests that human NAT1 may play a role in folic acid metabolism and hence in the normal development of the neural tube. In this study we examined the distribution of NAT in neuronal tissue from adult mice and embryos. Immunohistochemical staining of the adult mouse cerebellum revealed NAT2 (the mouse homologue of human NAT1) expression in the cell bodies and dendrites of Purkinje cells and in the neuroglia of the molecular layer. In embryos, NAT2 was detected in developing neuronal tissue on days 9.5, 11.5, and 13.5. It was expressed intensely in the nerual tube around the time of closure. The level of expression subsequently declined in the neuroepithelium but increased in glial cells. In addition, NAT2 was detected in the developing heart and gut. These findings demonstrate that the embryo itself expresses an enzyme which is involved in the metabolism of folic acid, so that the role played by both mother and embryo must be considered when examining the role of folic acid in embryonic development. These findings imply that polymorphisms in NAT genes could play a role in determining susceptibility to neural tube defects (NTD) and orofacial clefting, developmental disorders which can be prevented by dietary administration of folic acid.

Animals↗
PubMed1998

Differential blood-brain barrier breakdown and leucocyte recruitment following excitotoxic lesions in juvenile and adult rats.

Acute neuronal degeneration can be induced by intracerebral injections of the glutamate receptor agonists kainic acid (KA) and NMDA (N-methyl-D-aspartate). It is accompanied by an inflammatory response that has not yet been fully investigated. We have previously demonstrated that the juvenile rat brain is more susceptible to an inflammatory challenge when compared to adult rat brain. This study set out to investigate whether this also applied to the inflammatory response associated with acute neuronal degeneration. NMDA and kainic acid were injected into the rat striatum and lesion size, leucocyte recruitment, and blood-brain barrier (BBB) breakdown were assessed after 4, 8, 12, 24, 72, and 168 h. Both NMDA and KA induced lesions of similar volume at either age and apoptotic and necrotic nuclei could be detected. NMDA induced cellular loss by 4 h, whereas KA-injected rats did not show signs of neuronal loss until 8-12 h. The inflammatory response was characterized by an infiltration of neutrophils followed by macrophages. Juvenile rats showed a greater susceptibility to leucocyte recruitment compared to adult rats. BBB breakdown in response to NMDA injection occurred in the absence of cellular recruitment at 4 h in juveniles and was significantly greater in juvenile compared to adult rats at 8 h. BBB breakdown was minimal in KA-injected animals while at 7 days an influx of serum IgG coincided with a loss of astrocytic GFAP staining within the lesion.

Aging↗
PubMed1998

Loss of the tight junction proteins occludin and zonula occludens-1 from cerebral vascular endothelium during neutrophil-induced blood-brain barrier breakdown in vivo.

The tight junctions found between cerebral vascular endothelial cells form the basis of the blood-brain barrier. Breakdown of the blood-brain barrier is a feature of a variety of CNS pathologies that are characterized by extensive leucocyte recruitment, such as multiple sclerosis and stroke. The molecular mechanisms associated with opening of the blood-brain barrier and leucocyte recruitment in vivo are currently poorly understood. We have used an in vivo rat model to investigate the molecular response of the CNS endothelium to neutrophil adhesion and migration. Injection of interleukin-1 beta into the striatum of juvenile brains results in a neutrophil-dependent increase in vessel permeability at 4 h. Only a subset of blood vessels were associated with neutrophil recruitment. These particular vessels displayed an increase in phosphotyrosine staining, loss of the tight junctional proteins, occludin and zonula occludens-1, and apparent redistribution of the adherens junction protein vinculin. Examination of these vessels under the electron microscope indicated that the cell-cell adhesions in such vessels are morphologically different from normal junctions. This study provides the first direct evidence in vivo that leucocyte recruitment can trigger signal transduction cascades leading to junctional disorganization and blood-brain barrier breakdown. Our results have established an endothelial cell molecular profile associated with leucocyte-induced blood-brain barrier breakdown in vivo, and the relevance of different in vitro cell culture models may now be viewed more objectively.

Aging↗
PubMed1998

The monoclonal antibody HB1 recognizes an adhesion molecule for macrophages in the brain.

The brain environment exerts a powerful influence on macrophage phenotype, as exemplified by microglia, but the mechanisms mediating this control are nuclear. Since adhesion molecules are known to transmit signals across cell membranes, we investigated adhesion receptors involved in macrophage interaction with brain tissue. We have demonstrated previously that macrophages adhere specifically to CNS neurones in an in vitro assay. Here we show that this adhesion is inhibited by lectins, including Griffonia simplicofolia isolectin B4 (GSI), which has been used as a microglial marker for many years. Adhesion is unaffected by antibodies to several known adhesion molecules but is markedly inhibited by a new monoclonal antibody: HB1. HB1 recognizes microglia in the normal brain and activated microglia and recruited monocytes during CNS pathology. It labels a subset of resident macrophages and recruited monocytes in other tissues. Using this antibody, we isolated a protein of about 110 kDa from macrophage cell lysates. This protein is recognized by GSI, providing the first evidence of a functional role for the antigen labelled by this lectin. Further study of the HB1 antigen may provide important information about the influence of the brain environment on the phenotype of monocytic cells.

Animals↗
PubMed1998

The influence of plasma proteins on the distribution of leucocytes within the brain parenchyma in a murine model of stroke.

Inflammatory responses are thought to play an important role in the exacerbation of neuronal loss following stroke. Leucocyte recruitment following cerebral ischaemia has been demonstrated in experimental animals, and procedures which reduce the entry of leucocytes into the brain reduce neuronal loss and improve aspects of functional recovery in these models. In this study we investigate whether leakage of plasma proteins into the central nervous system (CNS) following ischaemia influences leucocyte adhesion within the parenchyma. Using an in vitro adhesion assay, we demonstrate that the addition of exogenous serum proteins increases macrophage adhesion to CNS tissue. Following permanent middle cerebral artery occlusion (MCAO) in mice, plasma proteins leak into the apparently healthy cortex surrounding the infarcted area. We show that there is increased macrophage adhesion to sections in the border region where endogenous plasma proteins are present within the parenchyma. Using immunohistochemistry, we co-localize plasma protein distribution within the tissue with leucocyte recruitment following MCAO. We show that monocytes, not neutrophils, infiltrate the lesion border where plasma proteins are present in the parenchyma. This distribution is compatible with their contributing to neuropathology, whereas neutrophils are found in clusters in the lesion core. We conclude that leakage of plasma proteins into the brain could influence leucocyte adhesion within the parenchyma. Recruited monocytes may exacerbate neuropathology in situations such as permanent cerebral ischaemia, where disruption of the blood-brain barrier occurs.

Animals↗
PubMed1998

Longitudinal study of inflammatory factors in serum, cerebrospinal fluid, and brain tissue in Alzheimer disease: interleukin-1beta, interleukin-6, interleukin-1 receptor antagonist, tumor necrosis factor-alpha, the soluble tumor necrosis factor receptors I and II, and alpha1-antichymotrypsin.

There is evidence consistent with the hypothesis that inflammatory and immune mechanisms are involved in the pathogenesis of Alzheimer disease (AD). We have investigated whether the levels of inflammatory associated proteins in serum or lumbar cerebrospinal fluid (CSF) reflect the progressive cognitive decline and brain atrophy of AD-patients. Levels of interleukin-1beta(IL-1beta), IL-1 receptor antagonist (IL-1ra), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), the soluble TNF receptors type I and II (sTNFR I and II), and the acute phase protein alpha1-antichymotrypsin (x1-ACT) were determined in paired serum and CSF samples taken yearly over a period of 2-5 years from pathologically confirmed AD patients (n = 8) and normal controls or non-AD subjects with other CNS pathology (n = 9). No significant differences were found between AD subjects and controls in the mean levels of the above mediators. There was also no correlation in either subject group between the levels of these inflammatory mediators in serum or CSF, and the change in cognitive status or the progression of the atrophy of the medial temporal lobe measured by X-ray computed tomography (CT). The concentrations of IL-1beta, IL-6, and TNF-alpha were determined in brain tissue specimens of five to nine different brain regions in six of the AD patients and four of the non-AD subjects. The levels of IL-1beta and IL-6 in the various brain regions were not significantly different in the AD and the non-AD group. However, in AD patients the level of TNF-alpha was significantly lower in the frontal cortex (32%, p = 0.024), the superior temporal gyrus (57%, p = 0.021), and the entorhinal cortex (49%, p = 0.009) compared with non-AD subjects. Low levels of TNF-alpha in the brain areas that showed neuropathology in AD may indicate a dysregulation of the inflammatory process in AD. Despite this finding, this study does not support the use of measurements of any of the inflammatory mediators investigated here as a diagnostic parameter for AD, due the large overlap in the levels of these factors between AD patients and other subjects, and the poor relation to clinical signs of AD.

Aged↗
PubMed1998

Differential adhesion of macrophages to white and grey matter in an in vitro assay.

Microglia, the resident macrophages of the brain, are monocytic cells whose phenotype is determined during development by the unique environment of the central nervous system (CNS). They are quiescent cells when compared with other tissue macrophages, and this downregulation may have important consequences for inflammatory and immune responses in the brain. In the search for features of the brain environment which might exert an influence on microglial behaviour, we have concentrated on the possible role of adhesion molecules. We have developed a robust and reproducible in vitro adhesion assay to look at the interaction between macrophages and brain tissue. We describe here the characterisation of this assay. By injecting agents into the brain in vivo, we were able to study the effect of perturbations in the resident cell population on the adhesion of macrophages to brain tissue in vitro. This provided strong evidence that RAW 264 cells adhere to neurones in preference to other CNS cell types in this assay, and this was confirmed by adhesion assays performed on monolayers of individual cell types. We hypothesise from these results that macrophages interact with CNS neurones in vivo via adhesion molecules, enabling them to sense and respond rapidly to pathology in the brain.

Animals↗
PubMed1997

Prevention of lysosomal storage in Tay-Sachs mice treated with N-butyldeoxynojirimycin.

The glycosphingolipid (GSL) lysosomal storage diseases result from the inheritance of defects in the genes encoding the enzymes required for catabolism of GSLs within lysosomes. A strategy for the treatment of these diseases, based on an inhibitor of GSL biosynthesis N-butyldeoxynojirimycin, was evaluated in a mouse model of Tay-Sachs disease. When Tay-Sachs mice were treated with N-butyldeoxynojirimycin, the accumulation of GM2 in the brain was prevented, with the number of storage neurons and the quantity of ganglioside stored per cell markedly reduced. Thus, limiting the biosynthesis of the substrate (GM2) for the defective enzyme (beta-hexosaminidase A) prevents GSL accumulation and the neuropathology associated with its lysosomal storage.

1-Deoxynojirimycin↗
PubMed1997

Ultrastructural studies of an immune-mediated inflammatory response in the CNS parenchyma directed against a non-CNS antigen.

We have shown previously that heat-killed bacillus Calmette-Guerin injected into the brain parenchyma becomes sequestered behind the blood brain barrier for months undetected by the immune system. However, independent peripheral sensitization of the immune system to bacillus Calmette-Guérin results in recognition of bacillus Calmette-Guérin in the brain and the induction of focal chronic lesions [Matyszak M. K. and Perry V. H. (1995) Neuroscience 64, 967 977]. We carried out ultrastructural studies of these lesions. Prior to subcutaneous challenge we used immunohistochemistry to detect bacillus Calmette-Guérin which was found in cells with the morphology of macrophages/microglia and in perivascular macrophages. Eight to 14 days after subcutaneous challenge there was a conspicuous leucocyte infiltration at the site of bacillus Calmette-Guérin deposits within the brain parenchyma. The majority of these cells were macrophages and lymphocytes, with some lymphocytes showing characteristic blast morphology. Dendritic cells in close contact with lymphocytes were prominent. Inflammatory cells were found in perivascular cuffs and within the brain parenchyma. The tissue was oedematous and some axons were undergoing Wallerian degeneration with associated myelin degeneration. Throughout the lesions, but more commonly at the edges, we detected macrophages containing myelin in their cytoplasm close to intact axons and axons with evidence of remyelinating sheaths, suggestive of primary demyelination. In older lesions, two to three months after the peripheral challenge, the oedema was less pronounced and there was little evidence of Wallerian degeneration. There were still many macrophages. lymphocytes and dendritic cells, although the number of these cells was lower than in earlier lesions. Late lesions also contained many plasma cells which were not present in early lesions. In these late lesions there were bundles of axons with no myelin or a few axons with thin myelin sheaths, suggestive of persistent or ongoing demyelination or remyelination. These observations show that, during a delayed-type hypersensitivity lesion in the CNS, the leucocyte populations change with time, and suggest that the mechanisms and type of tissue damage are different in the early and late stages of the lesion.

Animals↗
PubMed1997

The blood-brain barrier and the inflammatory response.

The environment of the brain is controlled by a sophisticated endothelial barrier that prevents the free entry of solutes from the blood. It is commonly assumed that this blood-brain barrier (BBB) also prevents the entry of leukocytes into the central nervous system. However, recent evidence in animal models shows that this is not the case, and leukocytes can cross an intact BBB during health and disease. Indeed, in many neurological diseases, including Alzheimer's disease, prion diseases and AIDS-related dementia, leukocytes enter the brain parenchyma without concomitant BBB breakdown. Current research is concentrating on factors that control the integrity of the BBB and the mechanisms that leukocytes use to enter the brain.

Animals↗
PubMed1997

Histone H1; a neuronal protein that binds bacterial lipopolysaccharide.

Bacterial lipopolysaccharide (LPS) is a potent inflammogen following systemic infection. Macrophages express a number of surface molecules including CD14, CD18 and the scavenger receptor that are capable of recognizing and binding LPS. Injection of the CNS with LPS produces an atypical inflammatory response including a delay in the recruitment of macrophages to the brain parenchyma. We have shown using a ligand blot overlay approach, that LPS is capable of binding to histone H1 present in brain homogenate. The ability of LPS to bind to H1 has only been previously shown for monocytes. Subsequent immunohistochemistry revealed that the anti-H1 antibody, ANA-108, stained neuronal cell bodies and was located in the membrane, possibly at the cell surface. Further experiments revealed that the H1 antigen recognized by the ANA-108 antibody was not a histone wholly restricted to the nucleus but may represent a novel CNS form of the protein. This observation has implications for the autoimmune disease systemic lupus erythematosus (SLE) due to the presence of auto-antibodies, particularly against DNA and nuclear proteins, in serum. The formation of immune complexes in various organs leads to severe dysfunction. Anti-histone antibodies are typical of the auto-antibodies found in SLE serum and the presence of the H1 antigen on the surface of neurons could provide an insight into biology underlying the neurological problems associated with SLE.

Animals↗
PubMed1997

Axonal damage in acute multiple sclerosis lesions.

One of the histological hallmarks of early multiple sclerosis lesions is primary demyelination, with myelin destruction and relative sparing of axons. On the other hand, it is widely accepted that axonal loss occurs in, and is responsible for, the permanent disability characterizing the later chronic progressive stage of the disease. In this study, we have used an antibody against amyloid precursor protein, known to be a sensitive marker of axonal damage in a number of other contexts, in immunocytochemical experiments on paraffin embedded multiple sclerosis lesions of varying ages in order to see at which stage of the disease axonal damage, in addition to demyelination, occurs and may thus contribute to the development of disability in patients. The results show the expression of amyloid precursor protein in damaged axons within acute multiple sclerosis lesions, and in the active borders of less acute lesions. This observation may have implications for the design and timing of therapeutic intervention, one of the most important aims of which must be the reduction of permanent disability.

Acute Disease↗
PubMed1997

Age-related effects of interleukin-1 beta on polymorphonuclear neutrophil-dependent increases in blood-brain barrier permeability in rats.

In adult rats, 50,000 units of recombinant interleukin-1 beta (IL-1 beta) injected into the brain parenchyma produced an intense meningitis and disruption of the blood-CSF barrier by 4 h. No increase in vascular permeability to horseradish peroxidase or leukocyte recruitment was observed at the site of injection. By contrast, in juvenile rats, 100 units of IL-1 beta injected into the striatum gave rise to a large increase in blood-brain barrier permeability and recruitment of polymorphonuclear neutrophils into the tissue around the injection site by 4 h. This effect was also accompanied by a marked meningitis. The injection of 100 units of IL-1 beta into neonatal (2-h-old) rats gave rise to an increase in permeability of vessels to serum proteins in the meninges, but no increase in vascular permeability was observed at the injection site. The IL-1 beta-induced increases in vessel permeability in the meninges, parenchyma, and choroid plexus were polymorphonuclear neutrophil dependent, since leukocyte depletion by irradiation or polymorphonuclear neutrophil anti-serum pre-treatment eliminated the response in the juvenile animals and in the adults. Seventy-five thousand units of murine tumour necrosis factor-alpha injected into the parenchyma of both adults and juvenile animals failed to induce an increase in blood-brain barrier permeability or polymorphonuclear neutrophil recruitment, but did give rise to a mild meningitis. These findings demonstrate clear differences in the responsiveness of different CNS compartments to IL-1 beta. Furthermore, while tumour necrosis factor-alpha and IL-1 beta might have been expected to exhibit similar proinflammatory effects in the CNS, this is not the case. We also show, for the first time, that age has a significant effect on the response to a cytokine. The "window of susceptibility' to an inflammatory stimulus in juvenile rats, if paralleled in humans, may be a major factor in the increased susceptibility of children to trauma or to infectious insults to the CNS.

Animals↗
PubMed1997

Adhesion molecules involved in macrophage responses to Wallerian degeneration in the murine peripheral nervous system.

When a peripheral nerve is damaged the severed axon undergoes Wallerian degeneration. The distal nerve is infiltrated by large numbers of monocyte-derived macrophages which participate in the phagocytosis of degenerating myelin. In other tissues, adhesion molecules play a crucial role in leukocyte recruitment during inflammation. Blood-borne cells enter damaged tissue by interacting with adhesion molecules expressed on activated endothelium. Having crossed the endothelium, leukocytes must adhere and migrate within the tissue. We investigated the adhesion molecules involved in both stages of the macrophage response to transection of one sciatic nerve of BALB/c mice. By injecting monoclonal antibodies in vivo, before and after peripheral nerve injury, we showed that intercellular adhesion molecule-1 (ICAM-1) and integrins alpha4beta1 (VLA-4) and alphaMbeta2 (type 3 complement receptor) are unlikely to be involved in the transendothelial migration of monocytes responding to peripheral nerve degeneration. We also studied the adhesion of macrophages within the endoneurium, using an in vitro adhesion assay. Macrophages showed much greater levels of adhesion to cryostat sections of transected nerves than to control nerves. This increased adhesion was partially inhibited by antibodies to the beta1-integrin chain, and more strongly inhibited by the extracellular matrix molecules fibronectin and collagen. Adhesion was unaffected by laminin-1 and by antibodies to other adhesion molecules, including alpha4beta1- and alpha5beta1-integrins. Thus we conclude that monocyte entry into a degenerating peripheral nerve is independent of alphaLbeta2/alphaMbeta2-ICAM-1 or alpha4beta1/VCAM-1 interactions, and that adhesion within the endoneurium is mediated in part by a beta1-integrin other than alpha4beta1 or alpha5beta1.

Animals↗
PubMed1997

Lymphocyte recruitment following spinal cord injury in mice is altered by prior viral exposure.

The inflammatory response induced by mechanical lesion of the spinal cord is known to include the recruitment of neutrophils and macrophages, while the involvement of lymphocytes has been largely ignored. We have studied the pattern of lymphocyte recruitment following partial transection of the mouse spinal cord. Using immunohistochemical techniques, all three types of lymphocytes (CD4-positive T-cells, CD8-positive T-cells and B-cells) were found in the vicinity of the lesion site within hours and persisted for up to 7 days. There was a predominance of B-lymphocytes during the first 3 days. A second, late phase of cell infiltration, dominated by CD8-positive T-lymphocytes, occurred in mice that had been raised in a conventional breeding unit and had acquired antibody titres to a common murine virus (mouse hepatitis virus). In contrast, mice kept in specific pathogen-free facilities did not show this late-phase response. These findings suggest a possible role for lymphocytes in secondary tissue loss, local demyelination, scar formation, cytokine-mediated inflammatory responses or trophic processes. They also provide evidence that a virus infection can significantly enhance the reaction of T-cells to a spinal cord lesion.

Animals↗