The kinetics, function, and regulation of P-selectin expressed by human brain microvessel endothelial cells in primary culture

P-selectin is an endothelial cell adhesion glycoprotein expressed on the cell surface early in inflammation where it binds to blood leukocytes. This study examines the expression, function, and regulation of P-selectin in primary cultures of human brain microvessel endothelial cells (HBMEC). Surface expression of P-selectin was minimal in unstimulated HBMEC; however, it was significantly augmented upon stimulation with histamine (10(-7)-10(-3) M) and thrombin (0.01-1 U/ml). Expression increased rapidly at 10 min and remained elevated at 60 min. Immunogold electron microscopy showed that histamine (10(-7) M) increased surface expression preferentially on the apical surface of subconfluent monolayers. A cell binding assay showed that the adhesion of polymorphonuclear leukocytes (PMNs) to confluent monolayers was augmented after histamine treatment. Histamine-induced surface expression of P-selectin was blocked by the histamine H2 receptor antagonist cimetidine. The H1 receptor antagonist mepyramine had no effect. Expression was reduced by the extracellular calcium chelator EDTA and blocked by the cyclic AMP phosphodiesterase inhibitor rolipram. Thus histamine and thrombin both increase P-selectin expression in HBMEC. Histamine mediates expression through the H2, but not the H1, receptor and calcium, whereas expression is reduced by cyclic AMP. The histamine-induced expression increases PMN binding to the HBMEC. These data suggest that P-selectin plays a role in the recruitment of acute inflammatory cells to the CNS.

Expression and function of the costimulatory molecules B7-1 (CD80) and B7-2 (CD86) in an in vitro model of the human blood--brain barrier

The interaction of B7 molecules with their ligand provides important accessory signals for optimal T cell activation and proliferation. In this study the in vitro expression of B7-1 and B7-2 by human brain microvessel endothelial cells (HBMEC) was investigated by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and immunocytochemistry. In addition, the contribution of B7 molecules to T cell proliferation on cerebral endothelial cells was studied by coincubating purified CD4+ T cells with resting or cytokine activated HBMEC. Untreated cultures constitutively expressed B7-2 RNA and surface protein, but lacked B7-1 expression. Treatment with TNF-alpha and IFN-gamma upregulated B7-2 and induced de novo expression of B7-1. Monoclonal blocking antibodies to B7-1 or B7-2 and human CTLA-4Ig chimeric protein significantly reduced the ability of HBMEC to support alpha-CD3-induced proliferation of CD4+ T lymphocytes. Expression of B7 glycoproteins and the ability to provide secondary signals for T cell proliferation suggest a potential role of the human cerebral endothelium in T cell activation during the early stages of central nervous system inflammation.

Characterization of ABCB9, an ATP binding cassette protein associated with lysosomes

We have cloned full-length human and mouse cDNAs of ABCB9, which encodes a predicted multiple-spanning transmembrane domain and a nucleotide-binding domain with Walker motifs. It is therefore designated as a "half" ATP binding cassette (ABC) transporter. Northern analysis shows that the ABCB9 mRNA is expressed at a high level in testes and moderate levels in brain and spinal cord. A splice variant mRNA deleted in the last pair of predicted transmembrane segments was shown to be expressed in human tissues. Phylogenetic analysis indicates that ABCB9 is closely related to TAP1 and TAP2, two "half" ABC proteins found in endoplasmic reticulum. ABCB9 protein colocalized with the lysosomal markers, LAMP1 and LAMP2, in transfected cells. ABCB9 protein appears to be most highly expressed in the Sertoli cells of the seminiferous tubules in mouse and rat testes. These cells have high levels of phagocytosis and secretory activities. These findings pave the way for further investigation into the potential novel function of ABCB9 in lysosomes.

Expression of complement messenger RNAs by human endothelial cells

This study evaluated complement mRNA expression in human brain microvessel endothelial cells (HBMEC), human umbilical vein endothelial cells (HUVEC), and cells of the human derived ECV304 line. Cerebral endothelial cells and HUVEC expressed detectable levels of complement gene mRNAs for the C1q B-chain, C1r, C1s, C2, C3, C4, C5, C7, C8 gamma-subunit and C9. In addition to C6 mRNA, C1q and C9 were not detected in ECV304 cells. These results indicate that endothelial cells may be a source of complement proteins in brain and other organs of the body.

A1 functions at the mitochondria to delay endothelial apoptosis in response to tumor necrosis factor

Tumor necrosis factor (TNF) does not cause endothelial apoptosis unless the expression of cytoprotective genes is blocked. We have previously demonstrated that one of the TNF-inducible cytoprotective genes is the Bcl-2 family member, A1. A1 is induced by the action of the transcription factor, NFkappaB, in response to inflammatory mediators. In this report we demonstrate that, as with other cell types, inhibition of NFkappaB initiates microvascular endothelial apoptosis in response to TNF. A1 is able to inhibit this apoptosis over 24 h. We demonstrate that A1 is localized to and functions at the mitochondria. Whereas A1 is able to inhibit mitochondrial depolarization, loss of cytochrome c, cleavage of caspase 9, BID, and poly(ADP-ribose) polymerase, it does not block caspase 8 or caspase 3 cleavage. In contrast, A1 is not able to prevent endothelial apoptosis by TNF over 72 h, when NFkappaB signaling is blocked. On the other hand, the caspase inhibitor, benzyloxycarbonyl-VAD-formylmethyl ketone, completely blocks TNF-induced endothelial apoptosis over 72 h. Our findings indicate that A1 is able to maintain temporary survival of endothelial cells in response to TNF by maintaining mitochondrial viability and function. However, a mitochondria-independent caspase pathway eventually results in endothelial death despite mitochondrial protection by A1.

Expression of the beta-chemokines RANTES and MIP-1 beta by human brain microvessel endothelial cells in primary culture

The mechanisms that regulate inflammatory cell recruitment across the blood-brain barrier (BBB) during CNS inflammation have not been fully characterized. Likely players in this process include the chemokines, small secondary messengers of inflammation capable of subset-specific leukocyte activation and chemoattraction. Primary cultures of human brain microvessel endothelial cells (HBMEC) were examined for their in vitro expression of the beta chemokines RANTES and MIP-1beta. Untreated HBMEC expressed low levels of RANTES and MIP-1beta RNA that were significantly upregulated following cytokine treatment. Parallel studies performed on human umbilical vein endothelial cells (HUVEC) showed induction of RANTES but not MIP-1beta RNA. Following stimulation with LPS, TNF-alpha, IFN-gamma, and IL-1beta alone or in combination, HBMEC released significant amounts of RANTES and MIP-1beta into the culture supernatants. RANTES secretion by HUVEC could be induced only with TNF-alpha/IFN-gamma. Both RANTES and MIP-1beta were detected by immunocytochemistry on the apical and basal surfaces of HBMEC, as well as bound to basal lamina-like material under the basal cell surface. Cytokine stimulation induced significant increase of RANTES and MIP-1beta molecules associated with the EC surface and subendothelial matrix. The expression of RANTES and MIP-1beta by HBMEC suggests that these chemokines may play an important role in mediating inflammatory responses and leukocyte trafficking across the BBB.

Blood mononuclear cells in patients with HTLV-I-associated myelopathy: lymphocytes are highly activated and adhesion to endothelial cells is increased

We have investigated lymphocyte subpopulations and blood mononuclear cell (MNC) adhesion to activated endothelial monolayers in patients with human T lymphotropic virus type I (HTLV-I) associated myelopathy (HAM), in HTLV-I asymptomatic carriers (carriers), and in seronegative controls. HAM patients and carriers had higher levels of CD4(+)CD29(+) "memory cells" than controls (P < 0.05). The percentage of CD3(+)CD27(-) "primed T cell" was elevated in patients with HAM (P < 0.05), but not in carriers. HAM patients had higher levels of CD8(+)CD57(+) "cytotoxic cells" (P < 0.05) than controls and carriers. The percentages of CD4(+) cells coexpressing activation markers HLA-DR and CD25, and of CD8(+) cells expressing HLA-DR, were significantly higher in HAM patients and carriers than in controls. Functional experiments indicated that MNC from HAM patients adhered more to activated endothelial monolayers than MNC from carriers or controls. Blocking studies demonstrated that the adhesion molecules VLA-4 and ICAM-1 and also L-selectin all contributed to increased binding. Analysis of expression of molecules involved in adhesion indicated that in HAM patients, L-selectin (CD62L) expression on CD4(+) and CD8(+) subsets was lower than in controls. Interestingly, HAM patients had a lower percentage of CD4(+) subsets expressing L-selectin than carriers (P < 0.05). In contrast, the percentage of CD4(+) and CD8(+) cells expressing VLA-4 (CD49d) was found to be higher in both HAM patients and carriers compared with controls. After 2 days in culture without mitogen, the percentage of T cells expressing ICAM-1 (CD54) increased in culture in carriers and more profoundly in HAM, but not in controls (P < 0. 05). After culture, T cells expressing the early activation antigen CD69 were also increased in HAM and carriers (P < 0.05) but not in controls. Interestingly, the levels of CD8(+) cells coexpressing activation antigen HLA-DR and CD38 were higher in HAM patients compared with both carriers and controls (P < 0.05) after culture. These findings are consistent with the observations that HTLV-I produces chronic lymphocyte activation with increased adhesion. This may be sufficient to initiate events leading to central nervous system inflammation and ultimately to HAM.

Agonist-stimulated calcium entry in primary cultures of human cerebral microvascular endothelial cells

Primary cultures of human cerebral microvascular endothelial cells (HCMEC) were loaded with fura-2. The intracellular free Ca2+ concentration ([Ca2+]i) was measured by digital imaging microscopy. Agonists ATP (100 micro), thrombin (10 units/ml), and histamine (25 microM) induced a transient [Ca2+]i increase. Histamine (100 microM) induced a biphasic [Ca2+]i increase with an initial [Ca2+]i peak followed by a [Ca2+]i plateau. The [Ca2+]i plateau was blocked by the receptor-operated Ca2+ channel (ROC) blockers SK&F 96365 and NCDC, indicating a contribution by Ca2+ influx through ROC to the [Ca2+]i plateau. However, this [Ca2+]i plateau was not blocked by the voltage-gated Ca2+ channel (VGC) blocker diltiazem (DTZ). Depolarization with 80K+ or application of the VGC agonist BAY K 8644 did not alter the resting [Ca2+]i; but 80K+ reduced the histamine (100 microM) induced [Ca2+]i plateau. These results show that HCMEC are devoid of functional VGC. Thus the membrane potential (Em) regulates Ca2+ entry mainly by enhancing the electrochemical Ca2+ gradient, such that hyperpolarization increases while depolarization decreases [Ca2+]i. Blockade of sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA) by CPA increased [Ca2+]i. This effect was dependent on extracellular Ca2+ and reduced by iberiotoxin (IBTX) blockade of Ca2+-activated K+ channels (Kca), suggesting a role for Kca in regulating Ca2+ influx. Ca2+ is the principal activator of endothelial nitric oxide synthase (eNOS), which stimulates cyclic GMP production. The final result that the eNOS inhibitor L-NAME enhanced the histamine (100 microM) induced [Ca2+]i plateau suggests a negative feedback loop (via cGMP) of endothelial NO on its own synthesis in the regulation of endothelial [Ca2+]i signal.

Expression and function of lymphocyte function associated antigen-3 (LFA-3) at the blood-brain barrier

Lymphocyte function associated antigen-3 (LFA-3) is a cell surface glycoprotein involved in antigen independent T-cell activation and proliferation. The expression and function of LFA-3 at the blood-brain barrier were studied in an in vitro model consisting of primary cultures of human brain microvessel endothelial cells (HBMEC). Surface expression of LFA-3 was detected by immunogold silver staining and the presence of RNA by reverse transcriptase-polymerase chain reaction (RT-PCR). Unstimulated HBMEC in primary culture constitutively express LFA-3 on their surface. Expression is only marginally upregulated following stimulation with tumor necrosis factor-alpha (TNF-alpha) or interferon-gamma (IFN-gamma). Similarly, LFA-3 RNA is present constitutively in unstimulated HBMEC with minimal increase after co-incubation with TNF-alpha and IFN-gamma. The function of LFA-3 as a costimulatory molecule on HBMEC was investigated by incubating purified CD4+ T-lymphocytes with resting or IFN-gamma treated HBMEC monolayers. Proliferation of alpha-CD3 activated CD4+ T-cells was significantly increased upon incubation with resting or activated endothelial cells. Monoclonal antibodies to LFA-3 consistently blocked the proliferative response by 64-76%. The ability of the cerebral endothelium to express LFA-3 and provide secondary signals for T-cell proliferation suggests that cerebral EC may be important in the initiation of inflammatory responses in the human central nervous system.

In vitro adhesion and migration of T lymphocytes across monolayers of human brain microvessel endothelial cells: regulation by ICAM-1, VCAM-1, E-selectin and PECAM-1

Increased lymphocyte traffic across an altered blood-brain barrier (BBB) is a prominent and early event in inflammatory and immune-mediated CNS diseases. The factors that control the entry of lymphocytes into the brain have not been fully elucidated. In this study, primary cultures of human brain microvessel endothelial cells (HBMEC) were used to investigate the role of endothelial cell (EC) adhesion molecules in the adhesion and migration of peripheral blood T lymphocytes across TNF-alpha treated and untreated monolayers. Adhesion of T cells to unstimulated HBMEC was minimal and few of the adherent cells migrated across the monolayers. Treatment of HBMEC with TNF-alpha augmented adhesion by 5-fold. The binding to activated EC was significantly, but not completely, inhibited by monoclonal antibodies (mAbs) to ICAM-1 and VCAM-1, whereas adhesion to unstimulated EC was blocked by mAb to ICAM-1 but not VCAM-1. Transendothelial migration of lymphocytes increased by up to 30-fold following treatment of HBMEC with TNF-alpha. Migration across activated monolayers, but not across untreated EC, was almost completely blocked by Ab to ICAM-1 and significantly inhibited by Abs to PECAM-1 and E-selectin. VCAM-1 was not utilized during transendothelial migration. Ultrastructurally, pseudopodia from lymphocytes contacted finger-like cytoplasmic projections on EC and eventually penetrated the EC cytoplasm at focal points along the apical surface. Migrating lymphocytes moved either through the EC cytoplasm or between adjacent EC across intercellular contacts. The overlying monolayers showed no evidence of disruption and intercellular junctions appeared intact over the migrated T cells. These studies indicate that adhesion and migration of T lymphocytes across the cerebral endothelial barrier are distinct processes that depend upon the activation state of EC and are controlled by diverse receptor-ligand interactions.

Glomeruloid vascular structures in glioblastoma multiforme: an immunohistochemical and ultrastructural study

Microvascular proliferation and glomeruloid vascular structures are important histopathological features of glioblastoma multiforme (GBM). The nature of cells participating in the formation of these structures remains unclear and is the subject of this study. To define these cells better, immunohistochemical markers directed against Factor VIII-related antigen (FVIIIR:Ag), alpha smooth-muscle actin (alpha-SMA), and the lectin Ulex europaeus agglutinin type I (UEA-I) were used. Cells lining the vascular channels and a large number of proliferating abluminal cells participating in glomeruloid vascular structure formation showed positive cytoplasmic staining for FVIIIR:Ag and UEA-I. Abluminal and luminal cells were variably labeled for alpha-SMA. Ultrastructurally, complex aggregates of focally anastomosing capillaries with narrow lumina composed the glomeruloid vascular structure. Endothelial cells were hyperplastic, varied in size and shape, overlapped focally, and contained numerous cytoplasmic filaments. Tight junctions bound together adjacent and overlapping endothelial cells. Weibel-Palade bodies, usually absent from brain microvessels, were present in increased numbers in the newly formed capillaries. Each capillary loop was surrounded by basal lamina encompassing a discontinuous layer of pericytes. This study indicates that glomeruloid vascular structures in GBM are complex aggregates of newly formed microchannels lined with hyperplastic endothelial cells that have an altered morphological phenotype and that these microchannels are supported by basal lamina and pericytes and are devoid of astrocytic end-feet.

Plasmodium falciparum: involvement of additional receptors in the cytoadherence of infected erythrocytes to microvascular endothelial cells

The involvement of additional ligands in the cytoadhesion of PRBC to endothelial cells was studied by the use of human microvascular endothelial cells (HMEC-1), brain microvascular endothelial cells (HBEC-51), umbilical vein endothelial (HUVEC), and C32 melanoma cells as well as soluble CD36, ICAM-1, and thrombospondin in the adhesion assays. Immunostaining showed that ICAM-1 and thrombospondin were expressed by all cell lines, whereas CD36 and VCAM-1 were expressed constitutively only by C32 melanoma cells and HBEC-51, respectively; none of these cells had basal expression of E-selectin. Bindings of the parental HB3 parasite strain to HMEC-1 and HUVEC were higher than that to HBEC-51 and C32 melanoma cells. Selections by panning the parental HB3 through HMEC-1 (HB3EC-6 line) or C32 melanoma cells (HB3C32-6 to HMEC-1 was higher than that to C32 melanoma cells. Antibody or peptide blockade against CD36, ICAM-1, and thrombospondin or preincubation of target cells with TNF-alpha and IFN-gamma did not significantly alter the binding intensity of HB3EC-6 to HMEC-1 and HB3C32-6 to C32 melanoma cells. Preincubation of HMEC-1 with IL-4, however, reduced its binding with HB3EC-6. In vitro selection did not enhance the binding of PRBC to plate-bound CD36 or thrombospondin; binding to ICAM-1 was negligible. The binding of both selected lines was inhibited by dextran sulfate and sulfatides, but not by chondroitin sulfate A. These results suggested that in addition to CD36 and thrombospondin, sulfated glycoconjugates were probably concurrently utilized by these PRBC as receptors. Experiments with freshly isolated Kenyan parasites indicated that they also exhibited a similar mechanism of binding to endothelial cells.

Platelet/endothelial cell adhesion molecule-1 (PECAM-1) expression by human brain microvessel endothelial cells in primary culture

PECAM-1 expression was investigated in primary cultures of human brain microvessel endothelial cells (HBMEC). HBMEC constitutively express PECAM-1 along their apical cell surface, advancing processes and on the basal surface at points of contact with the extracellular matrix. Surface expression is not altered by cytokine or lipopolysaccharide treatment. This distribution may mediate cell-cell contract and migration during angiogenesis and HBMEC-leukocyte interactions in CNS inflammation.

Regualtion by cytokines and lipopolysaccharide of E-selectin expression by human brain microvessel endothelial cells in primary culture

E-selectin is an adhesion molecule expressed on endothelial cells after treatment with inflammatory agents in vitro and in inflammatory diseases in vivo. Interactions between leukocytes and endothelial cells are mediated partly through this adhesion molecule. In this study, the kinetic expression of E-selectin by human cerebral endothelium was studied under standard conditions and following treatment of primary cultures with bacterial lipopolysaccharide (LPS), tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and interferon-gamma (IFN-gamma). Surface expression of E-selectin was detected by immunocytochemistry, ELISA and immunoelectron microscopy. Untreated human cerebral endothelial cells constitutively expressed low levels of E-selectin. Treatment with LPS, TNF-alpha and IL-beta increased the mean level of E-selectin expression per cell and the percentage of cells expressing E-selectin, in a time and concentration-dependent manner. E-selectin expression was maximal by 4 h post-stimulation and returned unstimulated levels by 48 h. LPS and TNF-alpha were most effective followed by IL-1beta, while the IFN-gamma had no effect on E-selectin expression. Immunoelectron microscopy demonstrated that E-selectin was preferentially expressed on the apical surface of unstimulated and TNF-alpha treated cells. Cytokine stimulation induced a several-fold increase of E-selectin expression on the apical and to a lesser extent on the basal cell surface. Modulation of E-selectin expression on cerebral endothelium by inflammatory cytokines suggests a potentially important role of this adhesion molecule in the recruitment of leukocytes in central nervous (CNS) inflammation.

Tenascin-C expression by angiogenic vessels in human astrocytomas and by human brain endothelial cells in vitro

The expression of the extracellular matrix glycoprotein tenascin-C (TN) is enhanced in human astrocytomas and correlates with angiogenesis. To determine whether vascular cells are able to synthesize TN, we investigated the expression of TN protein and mRNA in nine astrocytomas. Immunogold electron microscopy in two glioblastomas multiforme detected the presence of TN in an extracellular perivascular location and to a lesser extent among tumor cells, confirming light microscopy immunohistochemical findings. In situ hybridization of astrocytomas using a digoxigenin-labeled antisense riboprobe detected strong staining for TN mRNA in vascular cells, especially in hyperplastic vessels, including those at the invasive edge of the tumors but not in vessels of normal brains. We observed weaker staining in tumor cells indicating a higher level of TN mRNA in vascular than in tumor cells. No staining was detected with the sense probe. Moreover, we investigated the ability of human brain microvessel endothelial cells (HBMECs) in primary culture to synthesize TN in vitro. Western blot analysis of the culture supernatants from HBMECs detected large amounts of TN. Immunogold silver staining demonstrated the presence of TN on the surface of HBMECs and in the subendothelial matrix. The distribution of TN mRNA in vascular cells of astrocytomas and the ability of HBMECs to synthesize TN in vitro demonstrate that vascular cells, including endothelial cells, are a major source of TN associated with angiogenesis. Furthermore, our results suggest that TN expression may be associated with endothelial cell activation and may play an important role in angiogenesis.

Interferon-beta downregulates interferon-gamma-induced class II MHC molecule expression and morphological changes in primary cultures of human brain microvessel endothelial cells

Regulation of class II MHC (Ia) antigen expression by interferons beta and gamma was studied in an in vitro model of the blood-brain barrier. Primary cultures of human brain microvessel endothelial cells were incubated with IFN-beta, gamma or a combination of the two cytokines and surface expression of class II MHC molecules was investigated with the immunogold silver staining technique and enzyme-linked immunosorbent assay. Treatment of monolayers with IFN-beta (100-6000 U/ml) failed to induce Class II MHC molecules. Co-incubation with IFN-gamma (100 U/ml), with or without pretreatment with IFN-beta, significantly inhibited the IFN-gamma-induced de novo expression in a concentration-dependent manner. Downregulation was less significant when incubation with both cytokines was preceded by 2-day treatment with IFN-gamma and was not observed in cultures incubated for an additional 4 days with IFN-gamma. Endothelial cells treated with IFN-gamma exhibited prominent morphological changes and frequent overlapping. These changes were not observed in the presence of either IFN-beta or both cytokines in the media. IFN-beta alone, or in combination with IFN-gamma, significantly inhibited the growth of endothelial cells, while only slight inhibition was observed with IFN-gamma. The results of these studies suggest that IFN-beta may function in modulating IFN-gamma-mediated immune responses in the human central nervous system at the level of the blood-brain barrier and this negative regulatory mechanism may be, at least in part, responsible for the recently reported beneficial effect of IFN-beta in relapsing-remitting multiple sclerosis.

Expression of vascular cell adhesion molecule-1 (VCAM-1) by human brain microvessel endothelial cells in primary culture

Vascular cell adhesion molecule-1 (VCAM-1) is an endothelial cell membrane glycoprotein that has been implicated in leukocyte/endothelial cell interactions in inflammation. In this study, we report the expression of VCAM-1 in primary cultures of human brain microvessel endothelial cells (HBMEC) under standard conditions and following bacterial lipopolysaccharide (LPS), tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), or interferon-gamma (IFN-gamma) treatment. Surface expression was detected and quantitated by light and immunogold electron microscopy and ELISA. Unstimulated cerebral endothelial cells (EC) constitutively expressed low levels of VCAM-1. LPS, TNF-alpha, or IL-1 beta increased the overall intensity of surface staining and the percentage of cells expressing VCAM-1 in a time- and concentration-dependent manner. LPS had the most potent effect, followed by TNF-alpha and then IL-1 beta. IFN-gamma did not upregulate VCAM-1. The level of VCAM-1 expression increased by 12-24 hr and returned to unstimulated levels by 48 hr. Immunoelectron microscopy demonstrated that VCAM-1 was preferentially localized on the apical as compared to the basal surface in both unstimulated and cytokine-treated cells. In addition, the intensity of immunostaining was significantly greater in stimulated versus unstimulated EC. The polarization and significant upregulation of VCAM-1 after cytokine treatment suggest a possible role of this adhesion molecule in inflammatory and autoimmune processes within the central nervous system.

In vitro interaction of coronaviruses with primate and human brain microvascular endothelial cells

Primary human and primate brain microvascular endothelial cells were tested for permissiveness to coronaviruses JHM and 229E. While sub-genomic viral RNAs could be detected up to 72 hours post-infection, primate cells were abortively infected and neither virus caused cytopathology. Human cells were non-permissive for JHM but permissive for 229E replication; peak production of progeny 229E and observable cytopathic effects occurred approximately 22 and 32 hour post-infection, respectively. Using the criterion of cytopathology induction in infected endothelial cells, 229E was compared to other human RNA and DNA viruses. In addition, virus induced modulation of intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1) and HLA I was monitored by immunostaining of infected cells.

Additive effect of allopurinol and deferoxamine in the prevention of spinal cord injury caused by aortic crossclamping

Fourteen domestic swine were divided into two groups. Group A (n = 7) was the control group, in which no pharmacologic intervention was applied. In group B (n = 7), the ischemic-reperfused spinal cord was treated with the combination of allopurinol (50 mg/kg/day for 3 days before the day of operation) and deferoxamine (Desferal, 50 mg/kg administered intravenously over 3 to 4 hours). The administration of deferoxamine was completed 1 hour before crossclamping. The crossclamp was placed on the descending aorta just distal to the left subclavian artery for 30 minutes. Proximal hypertension was controlled with sodium nitroprusside and volume depletion. Methods of assessment included an evaluation of the neurologic status of the animals by quantitative Tarlov criteria, blood flow by radiolabeled microspheres, and histologic examination of the spinal cord. All animals in the control group, group A, were completely paraplegic with 0% recovery by Tarlov criteria at 24 hours after the removal of the crossclamp. In contrast, all animals in group B, in which the combination of allopurinol and deferoxamine was used, completely recovered (100% recovery by Tarlov criteria), and at 24 hours after the ischemic episode they were able to walk with no difficulty and had intact sensation. Functional parameters of these animals fully correlated with the morphologic findings. Widespread acute neuronal injury and vacuolation of neuropil were observed in the control group of animals. In contrast, animals in group B showed much less pronounced morphologic changes after the same period of ischemia. In summary, the combined use of these agents significantly (p < 0.001) reduced the incidence of paraplegia induced by aortic crossclamping with 82% additivity.

Hippocampal synaptic pathology in patients with temporal lobe epilepsy

Immunostaining of synaptic terminals was studied in the hippocampus of 26 patients who had surgical resections for intractable temporal lobe epilepsy. Two monoclonal antibodies (EP10 and SP12) reactive with distinct synaptic antigens were used on paraffin-embedded tissues. The results indicated qualitative reductions on synaptic terminals in CA4 and other regions where cell loss is reported. The inner molecular layer of the dentate gyrus was observed to have increased synaptic immunostaining. Synaptic terminal loss in CA4 and redistribution in the molecular layer were most frequent in cases with hippocampal sclerosis. However, both forms of synaptic pathology were also noted in most cases where the pathological findings were classified as indefinite, and in some cases associated with mass lesions of the temporal lobe. These results support the importance of neuronal loss and synaptic reorganization as possible mechanisms of illness in epilepsy. They also indicate that synaptic immunostaining may be a useful adjunct to routine neuropathological diagnostic techniques.

Effects of interferon-gamma on primary cultures of human brain microvessel endothelial cells

Primary cultures of human brain microvessel endothelial cells were used to study the effects of human recombinant interferon-gamma (IFN-gamma) on cerebral endothelium in vitro. Incubation of monolayers with various concentrations of IFN-gamma (10 to 200 U/ml) for 12 to 96 hours induced surface expression of class II major histocompatibility complex (Ia) antigen in a time- and concentration-dependent manner. In immunogold-stained cultures, labeling was observed as early as 12 hours, was maximal after 48 hours, and persisted at plateau levels in the continuous presence of the cytokine. Expression was blocked by coincubation with anti-IFN-gamma antibody and was reversed 4 days following removal of IFN-gamma from the culture media. Endothelial cells treated with IFN-gamma for 3 to 4 days became spindle-shaped, extensively overlapped, and frequently formed cellular whorls. These changes did not occur in the presence of anti-IFN-gamma antibody and reversed upon removal of IFN-gamma from the media. The morphological alterations were associated with increased permeability of confluent monolayers to macromolecules as compared with untreated cultures. The results of these studies indicate that human brain microvessel endothelial cells respond to in vitro cytokine stimulation by undergoing profound morphological, functional, and permeability changes. We conclude that cerebral endothelium may play an important role in the initiation and regulation of lymphocyte traffic across the blood-brain barrier in inflammatory disorders of the human central nervous system.

Upregulation of intercellular adhesion molecule-1 (ICAM-1) expression in primary cultures of human brain microvessel endothelial cells by cytokines and lipopolysaccharide

The expression of intercellular adhesion molecule-1 (ICAM-1) by human cerebral endothelium was studied in primary cultures of human brain microvessel endothelial cells following treatment with bacterial lipopolysaccharide (LPS), tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta) and interferon-gamma (IFN-gamma). Surface expression of ICAM-1 was examined with the immunogold silver staining technique. Intact cerebral endothelial cells constitutively express low levels of ICAM-1. Stimulation with LPS and cytokines induces upregulation of ICAM-1 which is minimal with IFN-gamma and maximal with LPS or a combination of IFN-gamma and TNF-alpha. Upregulation of ICAM-1 expression is concentration- and time-dependent, is observed as early as 4 h following incubation and persists for up to 72 h in the continuous presence of LPS or cytokines. The ICAM-1 expression is not reversed by 3 days after removal of the LPS or cytokines. These findings may be relevant to the interactions between leukocytes and brain microvessel endothelial cells in inflammatory and demyelinating diseases of the CNS.

Ultrastructural localization of factor VIII-related antigen in cultured human brain microvessel endothelial cells

Immunogold staining of primary cultures of human brain microvessel endothelial cells demonstrated the presence of Factor VIII-related antigen within cytoplasmic vesicles in close association with the rough endoplasmic reticulum and Golgi apparatus. Immunoperoxidase staining, at the light microscopic level, revealed a similar granular, perinuclear staining. The morphology and location of these vesicular profiles indicate that they are part of the trans-Golgi region where terminal processing and short-term storage of Factor VIII-related antigen takes place. Weibel-Palade bodies, specific storage organelles for von Willebrand factor in large vessel endothelium, were not observed in cerebral microvessel endothelium. The release of Factor VIII-related antigen from the cytoplasmic vesicles was influenced by some of the factors known to stimulate or inhibit the regulated pathway of secretion from Weibel-Palade bodies. Thus, stimulation of endothelial cells with calcium ionophore A23187 resulted in almost complete loss of staining, while addition of EGTA to the culture medium led to slight increase of intracellular pools of Factor VIII-related antigen. Pre-incubation of monolayers with interferon-gamma was associated with significant increase in the number of labeled vesicles, suggesting an additional role of this cytokine in the localized immune reaction within the central nervous system.

Haemophilus influenzae lipopolysaccharide disrupts confluent monolayers of bovine brain endothelial cells via a serum-dependent cytotoxic pathway

An in vitro blood-brain barrier (BBB) model consisting of primary cultures of bovine brain microvascular endothelial cells was used to examine the effect of Haemophilus influenzae type b (Hib) on the BBB. Whole bacteria and purified lipopolysaccharide (LPS; greater than 10 ng/ml) caused marked cytotoxicity on the bovine brain endothelial cells. This effect could be completely blocked by polymyxin B. Similar cytotoxic effects were observed with a cultured bovine pulmonary endothelial cell line. Serum was essential for the LPS-mediated cytotoxic effect, and human, horse, bovine, or fetal calf serum all had similar effects. The serum factor was not a complement component. A monoclonal antibody against CD14, a receptor involved in mediating the effect of LPS in monocytes, completely blocked the cytotoxic effect in both brain and pulmonary endothelial cells. These results suggest that Hib LPS disrupts an in vitro BBB model via a serum- and CD14-dependent pathway and that LPS has cytotoxic effects on bovine endothelial cells without the involvement of monocytic cells, an effect that may be important in gram-negative meningitis and in endotoxic shock.

Adhesion and migration of human polymorphonuclear leukocytes across cultured bovine brain microvessel endothelial cells

Adhesion and migration of human polymorphonuclear leukocytes (PMN) across cerebral endothelium were studied in an in vitro model consisting of monolayers of bovine brain microvessel endothelial cells (BBMEC) grown on amniotic stroma or collagen membranes. Polymorphonuclear leukocytes were stimulated to adhere to and migrate across confluent BBMEC monolayers in response to chemotactic gradients produced by formyl-methionyl-leucyl phenylalanine (fMLP), leukotriene B4 (LTB4) or acetyl-glyceryl-ether-phosphorylcholine (AGEPC) placed below the cultures. Under these conditions, PMN adherence to endothelium was 2-10-fold greater than that observed in the absence of chemoattractants or in the presence of equal concentrations of chemoattractants below and above the cultures. Transendothelial migration of PMN occurred rapidly and at focal points across the monolayers. Scanning and electron microscopic studies revealed that stimulated PMN migrated across the monolayers by first adhering to the apical surface of the endothelium and then moving between adjacent endothelial cells. Following their migration, PMN accumulated beneath the endothelium. The overlying endothelial monolayers showed no evidence of disruption and the interendothelial junctions appeared intact at the end of the migration period. We conclude that this in vitro system reproduces the endothelial cell-leukocyte interactions occurring during acute inflammation in vivo and should provide a useful in vitro model for studying the molecular mechanisms underlying these interactions in inflammatory diseases of the central nervous system.

Neurologic complications in allogeneic bone marrow transplant patients receiving cyclosporin

Regimens using cyclosporin (CSP) and either methylprednisolone (MP) or methotrexate (MTX) have been useful in the prophylaxis of acute graft-versus-host disease (GVHD) after allogeneic bone marrow transplantation (BMT). However, CSP produces a number of side effects, including neurologic toxicity. A retrospective review of recipients of 239 BMTs given CSP-based prophylactic regimens revealed that 10 patients (4.2%, 95% confidence interval 0% to 10.4%) experienced a syndrome characterized by hypertension, severe visual disturbances, seizures and occipital lobe density changes on brain computed tomography (nine patients) or nuclear magnetic resonance imaging (one patient). Neurologic findings were reversible in all cases, usually after temporary discontinuation of CSP. Univariate analysis identified the following risk factors for neurotoxicity: use of unrelated or HLA-mismatched related donors, administration of etoposide (VP-16) or total body irradiation as part of conditioning, use of corticosteroids for prophylaxis or treatment of acute GVHD, or development of either acute GVHD or clinically significant microangiopathic hemolytic anemia (MAHA) post-BMT. In multivariate analysis, the most important predictors were the use of VP-16 (p = 0.008), the use of a continuous infusion CSP plus MP prophylactic regimen for GVHD (p = 0.003) and the development of MAHA after BMT (p less than 0.001). The strong association with MAHA suggests that endothelial damage is related to the development of this complication.

Extensive replacement of spinal cord and brainstem by hemangioblastoma in a case of von Hippel-Lindau disease

We report an extremely unusual case of von Hippel-Lindau disease, characterized by almost total replacement of the spinal cord and most of the medulla by capillary hemangioblastoma (CHB). A 34-year-old female presented 20 years earlier with signs of lower limb weakness. She developed progressive quadriplegia despite multiple surgical attempts to remove separate CHBs from the midthoracic and cervical spinal cord. Spinal cord lesions continued to develop as did multiple cerebellar CHBs. She eventually became respirator-dependent and died following severe upper gastrointestinal hemorrhage. At autopsy there was extensive replacement of spinal cord and medulla by CHB as well as multiple solid and cystic cerebellar tumors. Both kidneys were enlarged and largely replaced by renal cell carcinomas and simple cysts. Additionally she had small pancreatic cysts and microscopic pulmonary hamartomas were observed. There was no evidence of retinal lesions clinically or at autopsy. Light microscopic and immunohistochemical studies of the lesions are presented. The early onset of this disease in a female, with such extensive spinal cord involvement, in addition to other CNS and visceral manifestations of von Hippel-Lindau disease, is unusual and has not been previously reported.

Culture and characterization of microvascular endothelial cells derived from human brain

Primary cultures of human cerebral endothelial cells were established from microvessels isolated from cortical fragments removed at surgery for seizure disorder and from brains at autopsy. A uniform population of cells growing in close association to each other formed confluent monolayers by 7 to 10 days in culture. They contained factor VIII/Von Willebrand antigen, the most specific marker for cells of endothelial origin, and showed lectin-binding sites for Ulex europaeus agglutinin characteristic of human endothelium. Cultured cells formed thin, continuous monolayers, contained few pinocytotic vesicles, and were joined together by tight junctional complexes. More than 99% of the intercellular junctions restricted the transendothelial passage of horseradish peroxidase. Monolayers of human brain microvessel endothelial cells thus resemble cerebral endothelium in vivo and should provide a useful in vitro model for studies of the biology of these cells and their role in the pathogenesis of certain human central nervous system diseases associated with abnormal blood-brain barrier function.

Innervation of the zona fasciculata of the adult human adrenal cortex: a light and electron microscopic study

Autonomic innervation of the adrenal cortex has been demonstrated in several species. Detailed ultrastructural studies on the innervation of the zona fasciculata of the normal human adrenal cortex are lacking. We report herein our observations on the pattern of innervation of the cells of the zona fasciculata of the normal adult human cortex at both the light and electron microscope levels. Postganglionic unmyelinated fibers were observed to descend from a dense capsular meshwork and to be distributed as delicate branches among the columns of endocrine cells. Immunoperoxidase staining confirmed the presence of nerve fibers in the zona fasciculata in a distribution similar to that observed after staining with silver impregnation methods. Ultrastructural findings lent further support to these observations by the demonstration of bundles of unmyelinated fibers with focal enlargements containing terminal boutons with both clear and dense core vesicles in close approximation with the endocrine cells.

Severe cerebral damage in ornithine transcarbamylase deficiency

Two patients are described with hyperammonemia due to ornithine transcarbamylase (OTC) deficiency who suffered severe shrinkage and collapse of the brain. The cerebral cortex was spongy and cavitated, containing only a few residual neurons, and was markedly gliosed. In one patient the basal ganglia were affected and harbored Alzheimer type II astrocytes. These lesions resemble those of acquired hepatocerebral degeneration and occur especially in female children with the milder form of the disease, who have a potential to survive. Strict observance of dietary restrictions is mandatory to avoid catastrophic damage to the brain.

Increased adrenal weight in victims of violent suicide

Adrenal weight was significantly higher in 16 victims of violent suicide than in 10 subjects who died suddenly from other causes. Since approximately half of suicide victims are depressed, these results support an association between depression and hypertrophy of the adrenal cortex.

Formation of a barrier by brain microvessel endothelial cells in culture

Endothelial cells (EC) isolated from bovine brain microvessels produce a continuous monolayer when grown in primary culture. The EC are joined together by tight junctions and contain few pinocytotic vesicles. Horseradish peroxidase (HRP) is unable to penetrate this in vitro barrier system. Exposure of the cells to 1.6 M arabinose produces a reversible separation of the tight junctions with penetration of HRP across the monolayer in a pattern similar to that observed in animals after infusion of hyperosmotic solutions into the carotid artery. The behavior of brain microvascular cells in culture suggest that they retain properties important to the formation of the blood-brain barrier.

Hyperosmotic urea reversibly opens the tight junctions between brain capillary endothelial cells in cell culture

The effect of hyperosmotic solutions of urea on primary cultures of bovine brain microvessel endothelial cells was examined. Confluent monolayers of cells positive for Factor VIII-related antigen were obtained by seven days in culture. The cells were: incubated in media containing 1 M, 2 M or 3 M urea and horseradish peroxidase (HRP) for various periods of time and then examined by transmission electron microscopy. Exposed to hypertonic urea solutions and 14C-3-O-methyl-D-glucose for determination of the intracellular water space. In control cultures endothelial cells were bound together by tight junctional complexes over 91% of which excluded HRP. In experimental cultures 82% of the interendothelial clefts became permeable to HRP after one minute of incubation with 3 M urea. The degree of cell shrinkage corresponded well with the extent of junctional opening. In monolayers examined 24 hours following removal of urea from the media more than 63% of the intercellular clefts were impermeable to HRP. These observations indicate that hyperosmotic solutions of urea reversibly open the tight junctions between brain microvessel endothelial cells in tissue culture. Decrease in cell volume appears to be linked to the increased junctional permeability.

In vitro studies of the blood-brain barrier using isolated brain capillaries and cultured endothelial cells

The endothelial cells in brain capillaries are the anatomic site of the blood-brain barrier. To learn more about the biology of these specialized cells, we developed methods to prepare suspensions of purified brain microvessels as well as primary cultures of endothelial cells in monolayer. These two preparations allow for direct investigation of the metabolism, transport properties, and receptor content of the brain capillary. We used isolated brain microvessels to study distribution of membrane carriers between the luminal and the abluminal plasma membrane of endothelial cells. We found that Na+K+-ATPase and the A-system amino-acid transport system are located predominantly on the abluminal surface of brain capillary endothelial cells. This distribution of transport carriers is consistent with the low permeability of potassium and small neutral amino acids in the blood-to-brain direction. It suggests, however, that both solutes can be actively transported across brain capillaries from the brain interstitial fluid to the blood. In tissue culture, the endothelial cells form continuous tight junctions with their neighbors. This results in a cellular layer impermeable to protein tracers. When exposed to hyperosmolar solutions, in an attempt to mimic the conditions that open the blood-brain barrier in vivo, we found a reversible separation of the tight junctions between contiguous endothelial cells. No indication of activation of pinocytosis was observed. In vitro systems provide a novel approach for studying the function of the blood-brain barrier and allow for observations not possible with intact animals.

The fibromatoses: CT-pathologic correlation

Although CT has been used in the evaluation of benign fibroblastic tumors (fibromatoses), data are lacking on radiologic-histopathologic correlation. In an attempt to explain the variable CT appearance of these lesions, a retrospective analysis was carried out of CT findings and histopathologic features in nine patients with fibromatoses. In three of four patients who had precontrast CT scans, the tumors were hyperdense relative to muscle, whereas in one patient the lesion was hypodense. The postenhancement appearance was variable. The pathologic specimens were analyzed and graded for collagen content, cellular content, tumor necrosis, and tumor vascularity. No consistent relationship could be established between the CT appearance of these lesions and their histologic appearance.

Scalp neoplasm associated with cranium bifidum in a 24-week human fetus

Prenatal ultrasonography at 24 weeks disclosed a fetus with a large mass protruding from the occiput. The mass was an invasive, undifferentiated mesenchymal neoplasm of the scalp associated with a defect in the occipital bone (cranium bifidum). The tumor may have derived from neural crest at the site of rhombencephalic closure. The tumor itself would seem to be a sporadic event, but the cranium bifidum may imply a recurrence risk of 2-3% for future pregnancies.

Correlations between aminergic metabolites simultaneously obtained from human CSF and brain

Brain and cerebrospinal fluid (CSF) levels of homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) were simultaneously measured in 48 individuals at autopsy. Concentrations of 5-HIAA and HVA in the cerebral cortex were positively correlated with their levels in the CSF for the same individual. Additionally a positive correlation was observed between postmortem CSF levels of 5-HIAA and HVA and a significant concentration gradient for both metabolites was observed in serial fractions of CSF. These findings suggest that determinations of 5-HIAA and HVA in CSF from living individuals may reflect brain metabolite levels as well as the functional activity of these specific neuronal systems.

Abnormal neuromuscular transmission in an infantile myasthenic syndrome

A term infant required intubation for respiratory depression. Examination revealed hypotonia and areflexia with intact extraocular movements. Electrodiagnostic studies demonstrated defective neuromuscular transmission characterized by borderline low motor evoked amplitudes, profound decremental responses at all stimulation rates, and moderate facilitation (50 to 740%) 15 seconds after 5 seconds of 50 Hz stimulation. Repetitive muscle action potential responses were not recorded following stimulation of nerves by single shocks. Sensory evoked responses and needle electromyographic findings were normal, as were acetylcholine receptor antibody levels. Results of muscle histochemical analyses, including acetylcholinesterase stains, were normal. End-plate histometric analyses demonstrated only a slight reduction in mean synaptic vesicle diameter compared with that in an adult control subject. In vitro muscle contractile properties, stimulating the muscle directly, were normal. Anticholinesterase medications were ineffective. Guanidine produced clinical deterioration. The amplitude of motor evoked responses progressively declined, whereas the percentage of decrement and amount of post-tetanic facilitation increased. Although the nature of the transmission defect was not identified, the data are consistent with abnormal acetylcholine resynthesis, mobilization, or storage without abnormality of release or receptors.

Hyperosmotic arabinose solutions open the tight junctions between brain capillary endothelial cells in tissue culture

Tight junctions between bovine brain capillary endothelial cells in primary cell culture are impermeable to horseradish peroxidase (HRP) after 5 min of incubation. However, following 1-5 min of exposure to 1.6 M arabinose, HRP penetrates the extracellular space between successive tight junctions. Endothelial cells in control cultures contain a small number of cytoplasmic pits and vesicles containing HRP which do not increase in number after hyperosmotic treatment.

A murine model of polymyositis induced by coxsackievirus B1 (Tucson strain)

A murine model of polymyositis induced by coxsackievirus B1, Tucson strain (CVBT) is described. Intraperitoneal CVBT inoculation of CD 1 Swiss mice less than 48 hours old resulted in proximal hindquarter weakness that was first apparent 7 days after viral challenge and persisted for more than 10 weeks. Electromyographic and histologic evidence of a continuing myositis was present during this entire period of time. However, virus was not detectable later than 2 weeks post infection, despite clinical progression of disease. The finding of electromyographic and histologic abnormalities in CVBT-infected mice, long after virus had cleared and neutralizing antibody production evoked, suggests that persistent myositis may be immunologically mediated, triggered by the initial acute viral infection.

New form of familial Parkinson-dementia syndrome: clinical and pathologic findings

We studied a family in which three siblings had a syndrome characterized by parkinsonism features, mental deterioration, pyramidal signs, and abnormal eye movements beginning in the third decade. The pathology resembled that of progressive supranuclear palsy or the Parkinson-dementia complex of Guam, but these were excluded by the clinical presentation. This syndrome appears to be a new entity.

Ionic lanthanum passage across cerebral endothelium exposed to hyperosmotic arabinose

Hyperosmotic media infused into the cerebral circulation open the blood-brain barrier to protein and colloid. The mechanism whereby such substances cross the affected vessels is still disputed. We describe here the transendothelial route taken by ionic lanthanum (La3+), a small electron-dense tracer which, unlike colloidal lanthanum, can be administered to the living animal. In adult rats, 2.9 ml of hyperosmotic (1.4 M) arabinose was infused into the internal carotid artery as a 30-s bolus, followed by 5 mM LaCl3. To find the extravasated La3+, which is invisible by light microscopy, horseradish peroxidase (HRP) was injected simultaneously into the femoral vein. The hyperosmotic treatment resulted in exudation of both HRP and La3+ primarily around cerebral arterioles. The La3+ crossed arterioles through successive tight junctions between endothelial cells. Although the tight junctions were not discernibly opened, they must have become permeable because the extracellular pools between successive tight junctions were penetrated by the La3+. These pools are normally inaccessible to La3+. Luminal and abluminal pits and cytoplasmic vesicles, some of them containing La3+, formed intraendothelial clusters. Their role, if any, in the transfer of ion remains uncertain.

Massive ocular astrocytoma in a congenitally deformed eye

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Types of human intrafusal muscle fibers

The histochemical and fine structural profiles of human intrafusal muscle fibers were studied. Spindles were located in freshly frozen specimens taken from biopsied normal external intercostal muscles, and periodic 10- and 50-mum-thick cross sections were processed alternately for enzyme histochemical and electron microscopic examination. Nuclear bag fibers were of two types, bag1 and bag2, histochemically, and they displayed two distinct types of ultrastructure. Nuclear chain fibers were histochemically and ultrastructurally homogeneous. Regional differences in enzymatic staining and ultrastructure occurred along individual intrafusal fibers. Human bag1 and bag2 fibers appear to be analogous to the two types of nuclear bag fiber identified in animal spindles and are considered to have different roles in spindle function. The presence of three types of intrafusal fibers should be taken into account when studying spindle abnormalities in human neuromuscular disorders.