Lectin histochemistry of scrapie amyloid plaques

Lectin histochemistry of the rat brain following thioacetamide-induced hepatic failure

Biotinyl derivatives of several lectins were used to study the localization of glycoconjugates in the cerebral microcapillaries and various brains of rats given at 24-h intervals two i.p. administrations of a hepatotoxin-thioacetamide (TAA) and examined 21 d posttreatment. At this time, the rats were asymptomatic with regard to hepatic encephalopathy but showed specific and selective changes in the blood-brain-barrier (BBB) transport of basic amino acid, but no BBB damage, and region-specific neuronal injury in the hippocampus and neocortex. The lectins tested recognized the following sugar residues: beta-D-galactosyl (Ricinus communis agglutinin [RCA-1]); N-acetyl-glucosaminyl and N-acetyl-neuraminic acid (wheat-germ agglutinin [WGA]); N-acetyl-D-galactosaminyl (Helix pomatia agglutinin [HPA]); beta-D-galactosyl and D-galactosyl neuraminic acid (peanut agglutinin [PNA]), and alpha-D-galactosyl and alpha-D-mannosyl (concanavalin A [Con A]). The treatment markedly decreased the binding to the cerebromicrovascular network of the hippocampus and neocortex of RCA-1 and WGA. The binding of these two lectins to their complementary monosaccharide residues appears to reflect subtle changes in BBB function, with a detection threshold below the conventional BBB permeability tests. The changes in the binding of the other two lectins: an increase of HPA binding and a decrease of Con A binding, confined to neocortical neurons and pyramidal cells of hippocampus injured by TAA treatment.

Lectin histochemistry of cerebral microvessels in ageing, Alzheimer's disease and Down's syndrome

A panel of 14 lectins was used to investigate the expression of saccharides by cerebral microvessels (MBV) in ageing, Alzheimer's disease (AD) and Down's syndrome (DS). Broad increases in lectin binding with age may reflect changes in amount and diversity of glycoproteins due to the thickening of the basement membrane (BM) common in older persons. In AD, and in persons over 50 years of age with DS, binding of e-PHA, 1-PHA and PAA was increased beyond that of age alone, as was that of UEA-I and BSA-1B4 in AD, but not in DS. Persons under 50 years of age with DS showed no changes inappropriate to their age. These specific increases in AD and DS may reflect selective disease-related changes in BM and could indicate an impaired blood-brain barrier (bbb) function or integrity. However, because they occur (in DS) after the deposition of amyloid (A4) protein and onset of neurofibrillary degeneration, it is unlikely they induce plaque and tangle formation. Such changes in MBV could stem from the loss of neurones from locus caeruleus, raphe and nucleus basalis (which are thought to innervate MBV and exert control over blood flow and permeability) that occurs in DS after 50 years of age.

Nucleoside diphosphatase (NDPase) activity associated with human beta-protein amyloid fibers

Nucleoside diphosphatase (NDPase) activity was studied by electron microscope cytochemistry in surgical specimens obtained from aged human cerebral cortices. The presence of NDPase activity on the surface of the microglial cells (MCs) and especially within the endoplasmic reticulum (ER) cisternae that are filled with amyloid fibers and that are in continuity with the extracellular amyloid deposits in plaques suggests a possible role of this enzyme in final elaboration of amyloid protein. The close structural relationship between MCs and amyloid plaques, suggesting the participation of these cells in the synthesis or final elaboration of amyloid fibers, was observed. The comparison of these observations with previously reported data on the distribution of NDPase in MCs and amyloid fibers in scrapie-infected mouse brain suggests that presumably similar mechanisms are acting in both cases. These observations, as compared with the results of other cytochemical and biochemical studies, also suggest that co-localization of NDPase activity with newly formed amyloid fibers in plaques can be associated with glycosyltransferase activities engaged in the amyloid or amyloid precursor protein glycosylation.

Beagle pup germinal matrix maturation studies

Intraventricular hemorrhage, or hemorrhage into the germinal matrix tissues of the developing brain, remains a common problem of preterm infants. The "risk period" for this insult is the first 3-4 postnatal days. We hypothesized that this risk period for hemorrhage is related to rapid perinatal maturation of the germinal matrix vasculature and employed the newborn beagle pup model for the study of this maturation. Newborn beagle pups (n = 30) were anesthetized and systemically perfused with buffered formalin; the brains were removed and prepared for immunohistochemical study. Sections stained with Bandeiraea lectin demonstrated that there was no difference in germinal matrix vessel density between postnatal days 1 and 4. Germinal matrix sections were also stained for antibodies to alpha-smooth muscle actin, collagen IV, collagen V, desmin, factor VIII-related antigen, fibronectin, glial fibrillary acidic protein, laminin, transferrin, and vimentin. Vasculature staining by alpha-smooth muscle actin was not noted until postnatal day 10, and differential staining was detected for antibodies to laminin and collagen V. Quantification of staining intensity by confocal microscopy demonstrated a significant increase in both extracellular matrix components at postnatal day 4 compared with day 1 (p less than 0.05 for both). These basement membrane proteins may add sufficient structural integrity to germinal matrix vessels to prevent capillary rupture and thus intraventricular hemorrhage.

Aluminum neurotoxicity in mammals

Although aluminum comprises a large percentage of the Earth's crust, it is excluded from body tissues, and especially from the central nervous system. When aluminum is experimentally introduced to the central nervous system, several neurotoxic effects are observed:i.e. neurofibrillary changes, behavioral and cognitive deficits and enzymatic and neurotransmitter changes, as well as certain types of epileptic seizures.The localization of relatively high levels of aluminum in Alzheimer disease, Guamanian amyotrophic lateral sclerosis and Parkinsonism-dementia has led to the implication of aluminum as a pathogenic factor in these diseases. Recent studies have shown that microtubule-associated proteins are part of the paired helical filaments which make up the intraneuronal neurofibrillary tangle. Other studies have identified the protein making the vascular and neuritic (senile) plaque amyloid and located the gene responsible for this protein to chromosome 21.Our electron microprobe analysis studies have not found the levels of aluminum or silicon in either the neurofibrillary tangles or amyloid cores reported elsewhere, nor have the levels of aluminum been elevated in approximately one half of the tangles and plaque cores examined to date.

Sulfated glycosaminoglycans in amyloid plaques of prion diseases

Brain sections from cases of human Creutzfeldt-Jakob disease, Gerstmann-Sträussler syndrome, kuru, and hamster scrapie containing amyloid were examined for the presence of sulfated glycosaminoglycans (GAGs), the anionic component of proteoglycans, using the sulfated Alcian blue method and Alcian blue technique with 0.3 M and 0.7 M magnesium chloride. These studies suggest that sulfated glycosaminoglycans are part of the CNS amyloid plaques in each of the above human prion disorders as well as in experimental scrapie. All the amyloid plaques stained positively with Alcian blue at 0.3 M, and less so at 0.7 M magnesium chloride indicating the presence of sulfated GAGs. Therefore, the amyloid plaques of prion diseases possess similar histochemical features to those found in Alzheimer's disease.

Concanavalin A binding sites of rough endoplasmic reticulum containing intracisternal microtubules in canine neurones

Lectin histochemistry was used to identify sugar residues of IM-containing RER in elderly canine sympathetic ganglionic neurones. IM-inclusions stained with ConA-peroxidase conjugate, but not with soybean agglutinin (SBA), wheat germ agglutinin (WGA), peanut agglutinin (PNA), Dolichos biflorus agglutinin (DBA), Ricinus communis agglutinin (RCA I) and Ulex europaeus agglutinin (UEA I). ConA-binding sites were visualized within cisternae of RER containing IM; reaction product was localized in IM-containing RER cisternae and IM. Inhibition with specific sugars (0.1 M alpha-methyl-D-mannoside or 0.5 M D-glucose) blocked the binding of ConA to IM-inclusions and normal Nissl substance. When a low sugar concentration (5 x 10(-3) M alpha-methyl-D-mannoside or 0.2 M D-glucose) was employed, IM-inclusions were still strongly ConA-positive, but normal Nissl substance was not. These results demonstrate that IM-containing RER have an excessive amount of carbohydrates (mannose or glucose-rich sugars) which are essentially detected in flattened RER under normal conditions and further indicate that glycoproteins in IM differ from those in cytoplasmic microtubules.

Ultrastructural studies of glycoconjugates in brain micro-blood vessels and amyloid plaques of scrapie-infected mice

Lectin or glycoprotein-gold complexes and samples of scrapie-infected mouse brain embedded in Lowicryl K4M were used for ultrastructural localization of glycoconjugates. The lectins tested recognize the following residues: beta-D-galactosyl [RCA, Ricinus communis agglutinin (aggl.) 120], N-acetyl and N-glycolyl neuraminic acid (LFA, Limax flavus aggl.), N-acetyl-D-glucosaminyl and sialyl (WGA, Wheat germ aggl.), N-acetyl-D-galactosaminyl (HPA, Helix pomatia aggl., and DBA, Dolichos biflorus aggl.), alpha-D-mannosyl/alpha-D-glucosyl (Con A, Concanavalin A), alpha-D-galactosyl and alpha-D-galactopyranoside (BSA, Bandeirea simplicifolia aggl., izolectin B4). Labeling of the majority of micro-blood vessels (MBVs) located outside the plaque area and in the remaining cerebral cortex was similar to that which has been previously observed in non-infected animals. Some MBVs, however, located inside the plaque area and surrounded directly by amyloid fibers showed attenuation of the endothelium, the surface of which was scarcely and irregularly decorated with RCA, LFA, WGA and Con A. These abnormalities in the composition of glycoconjugates can be associated with previously noted increased permeability of some MBVs in the brains of scrapie-infected mice. Some vessels in the plaque area were encapsulated by perivascular deposits of homogeneous or flocculogranular material containing several glycoconjugates. A very intimate structural relation between reactive (microglial-like) cells and amyloid fibers suggests the participation of these cells in elaboration of plaque material. Labeling of the cell surface and adjacent amyloid fibers with the same lectins (RCA, WGA, DBA, Con A) suggests the possibility that the glycosylation of these fibers occurs extracellularly. Only WGA and DBA were occasionally labeling some Golgi elements of the reactive cells.

Culture of mouse brain capillary endothelial cell lines that express factor VIII, gamma-glutamyl transpeptidase, and form junctional complexes in vitro

The isolation and culture of cell lines from mouse brain capillary endothelium (MBE) is described. Cells migrating from collagenase-treated capillary fragments proliferated rapidly in the 1st wk of culture forming large epithelioid cobblestonelike colonies. The cells showed only marginal proliferation after 2 to 3 wk in culture, until peripheral cells migrated away from the colony which exhibited a marked degree of proliferation. These cells were trypsinized and subcultured to confluence. The cells can be maintained for well over 40 passages and seem to retain their endothelial morphology. The endothelial origin of these cells was demonstrated by positive immunoperoxidase reactivity with Factor VIII-related antigen, specific binding of Bandeiraea simplicifolia lectin and gamma-glutamyl transpeptidase activity. Electron microscopic examination of the MBE cells showed junctional complexes including intermediate junctions, but no tight junctions. The overall ultrastructure indicates that a degree of dedifferentiation has occurred, the cells ultrastructurally resembling immature endothelium. An earlier investigation of cultured mouse brain endothelial cells reported a cell line that had lost many functional and structural characteristics. Our study demonstrates, as the previous one, that a certain degree of dedifferentiation needs to occur if MBE cells are to be maintained for long-term culture. However, the degree of dedifferentiation seems to be variable, depending in part on the culture conditions employed.

Sulfated glycosaminoglycans in Alzheimer's disease

Using the sulfated alcian blue and alcian blue-MgCl2 techniques for demonstrating sulfated glycosaminoglycans (GAGs), we have shown sulfated GAGs to be associated with the amyloidotic lesions of Alzheimer's disease, the neuritic plaques, the neurofibrillary tangle, and the congophilic angiopathy. To determine how specific these findings are to Alzheimer's disease, other neurologic disorders with neurofibrillary tangles and filamentous inclusions were examined. These included progressive supranuclear palsy, Pick's disease, subacute sclerosing panencephalitis, and postencephalitic parkinsonism. Sulfated GAGs were not demonstrated in the neurofibrillary tangles or filamentous structures in any of these disorders. The relationship of GAGs to the pathology of Alzheimer's disease is discussed as is their possible importance in determining the characteristic morphology of the amyloidotic lesion.

Myelin phagocytosis in Wallerian degeneration. Properties of millipore diffusion chambers and immunohistochemical identification of cell populations

Myelin phagocytosis in Wallerian degeneration was studied using a model of murine sciatic nerve degeneration in millipore diffusion chambers in the peritoneal cavity of host mice. Immunocytological investigations showed the dependence of myelin digestion on the invasion of Fc-positive, Mac-1-positive and partly Ia-positive monocytes. Lymphocytes did not play a prominent role. Compared to Wallerian degeneration in situ, phagocytosis was decreased in nerves enclosed by millipore membranes on both sides of the chamber. The membrane acted as a trap for invading monocytes/macrophages. Neither tissue integrity nor genetic strain influenced the degree of phagocytosis. A modification of the experimental technique is introduced which permits myelin phagocytosis in the peritoneal cavity in a degree comparable to that in Wallerian degeneration in situ.

Lectin histochemistry of plaques and tangles in Alzheimer's disease

Biotinyl derivatives of several lectins and avidin-horseradish peroxidase were used to study the localization of glycoconjugates in amyloid plaques and in neuritic tangles in brains of patients with Alzheimer's disease (AD), Downs syndrome (DS) and Gerstmann-Sträussler syndrome (GSS). The lectins tested recognize the following residues: beta-D-galactosyl [Ricinus communis agglutinin 120, (RCA-1) and peanut agglutinin, (PNA)]; alpha-D-galactosyl [Griffonia simplicifolia agglutinin (GSA)]; alpha-D-mannosyl greater than alpha-D-glucosyl [concanavalin A (Con A) and Lens culinaris agglutinin (LcH)]; N-acetyl- and N-glycolyl-neuraminic acid [Limax flavus agglutinin (LFA) and Limulus polyphemus agglutinin (LPA)]; N-acetyl-glucosaminyl and sialyl [wheat germ agglutinin (WGA)]; N-acetyl-D-galactosaminyl [Helix pomatia agglutinin (HPA) and Dolichos biflorus agglutinin (DBA)] and alpha-L-fucosyl [Ulex europeus agglutinin (UEA-1)]. The majority of lectins listed above bind preferentially to the peripheral area of AD plaques, whereas in plaques of DS they are mainly bound to central amyloid core. In neurofibrillary tangles of AD brains only residues recognized by WGA and HPA or DBA were found, whereas in DS brains, in addition to above mentioned, beta-D-galactose (RCA-1) and sialic acid (LFA) were also present. In brain microblood vessels the strongest reaction in endothelia appeared with UEA-1 and RCA-1, indicating the abundance of alpha-L-fucosyl and beta-D-galactosyl residues. In AD brains deposits of amyloid were noted in the wall of some blood vessels, where monosaccharide residues recognized by RCA-1, GSA, UEA and WGA but not by Con A and LFA were present. However, our studies of some organs (liver, kidney, heart and testes) of patients with generalized amyloidosis revealed a lack of these sugar residues. It indicates, that the composition of amyloid present in brains of AD is different to that in other organs in generalized amyloidosis.

Lectin histochemistry of canine polyglucosan bodies

Lectin histochemistry was investigated to identify sugar residues of the polyglucosan bodies of canine brain, spinal cord and caecum. The polyglucosan bodies in the brain and spinal cord stained with concanavalin A (ConA) but not with soybean agglutinin, wheat germ agglutinin, peanut agglutinin, Dolichos biflorus agglutinin, Ricinus communis agglutinin and Ulex europaeus agglutinin. Caecum polyglucosan bodies, however, did not stain with any of the seven lectins employed. After periodate oxidation, paradoxical ConA staining was observed in the polyglucosan bodies of the brain, spinal cord and caecum. These results indicate that polyglucosan bodies contain mannose and glucose residues and suggest that the component of polyglucosan bodies is partially derived from rough endoplasmic reticulum, the Golgi apparatus and hypolemmal cisternae.