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Y Persidsky

Publications and source records attributed to Y Persidsky.

At least 37 records · Page 2Linked to original sources
PubMed1999

Model systems for studies of leukocyte migration across the blood - brain barrier.

The blood - brain barrier (BBB) plays a crucial role in central nervous system (CNS) homeostasis. Serving as the brain's protective shield it regulates soluble factor and cellular exchanges from blood to brain. Critical to its function, the BBB is composed of brain microvascular endothelial cells (BMVEC), a collagen matrix, and astrocytes. Astrocytic endfeet surround the BMVEC abluminal surface and influence the 'tightness' and trafficking role of the barrier. In neurodegenerative disorders (for example stroke, multiple sclerosis and HIV encephalitis) the BBB becomes compromised. This is, in part, immune mediated. An accumulating body of evidence demonstrates that the cellular components of the BBB are themselves immunocompetent. Perivascular cells (astrocytes, macrophages and microglial cells) and BMVEC produce inflammatory factors that affect BBB permeability and expression of adhesion molecules. These affect cell trafficking into the CNS. Leukocyte BBB migration can be influenced by cytokines and chemokines produced by glia. Astrocytes and macrophages secrete a multitude of factors that affect brain immune responses. Interactions between BMVEC, leukocytes and/or glia, immunological activation and noxious (infectious, toxic and immune-mediated) brain insults all appear to play important roles in this BBB cell trafficking. New information gained into the mechanisms of leukocyte-brain penetration may provide novel insights in the pathogenesis and treatment strategies of neurodegenerative disorders.

Animals↗
PubMed1998

SCID mice with HIV encephalitis develop behavioral abnormalities.

Severe combined immunodeficient (SCID) mice inoculated intracerebrally (i.c.) with HIV-infected human monocytes develop brain pathology similar to that in humans with HIV encephalitis. This includes HIV-positive macrophages and multinucleated giant cells, astrogliosis, microglial nodules, and neuronal dropout. These xenografts survive about 1 month. To develop a model of chronic HIV encephalitis and to assay the resulting behavioral abnormalities, we reinoculated SCID mice i.c. every 4 weeks for 3 months with either HIV-infected human monocytes (n = 5) or uninfected human macrophages (n = 4) or administered no inoculation (n = 6); these three groups were monitored for behavioral abnormalities. Tests of cognitive function in a Morris water maze 3.5 months after the first inoculation suggested that HIV-infected mice performed poorly compared with controls. Following testing in the water maze on days 4 and 5 of acquisition, motor activity of infected mice was reduced in comparison with that of controls. Retention of goal location when tested 1 week later was impaired in HIV-infected mice compared with controls. Histopathologic analysis of brains revealed significant astrogliosis and strongly suggested higher numbers of major histocompatibility complex (MHC) class II-positive multinucleated macrophages in HIV-infected compared with control mice. Thus, our preliminary studies indicate that SCID mice with HIV encephalitis develop behavioral abnormalities reminiscent of human disease. These behavioral abnormalities are associated with significantly increased astrogliosis, the presence of HIV, and probably multinucleated giant cells. These studies further support the use of this SCID animal model system for studies of the pathogenesis of HIV encephalitis and for drug interventions.

AIDS Dementia Complex↗
PubMed1998

Protein kinase C isoforms in human aortic smooth muscle cells.

PURPOSE: To identify the protein kinase C (PKC) isoforms in human arterial smooth muscle cells (SMC) and define their subcellular location in the resting state and in response to the PKC activator, 12-O-tetradecanoylphorbol 13-acetate (TPA). METHODS: Arterial SMC cultures established from transplant donor aorta were treated with 100 nM TPA or control media, then mechanically lysed. PKC from the soluble and particulate fraction were separated by centrifugation, and protein normalized immunoblots were performed with antibodies to the PKC isoforms alpha, betaI, betaII, delta, epsilon, gamma and zeta. Bands were detected by enhanced chemiluminescence and analyzed densitometrically, with results expressed as the mean percentage of each fraction +/- SEM. Translocation was defined as a significant (p < 0.05) change in the particulate fraction for each isoform. Immunofluorescent staining of cultured SMC visualized the resting location and stimulated translocation of each isoform. RESULTS: Isoforms alpha and betaI were detected primarily in the soluble fraction, translocating to the particulate fraction with TPA stimulation (p < 0.0001). The isoforms betaII, delta, and epsilon were found primarily in the particulate fraction and did not translocate. Immunofluorescent staining confirmed these locations. Neither gamma or zeta were detected in these SMC. CONCLUSIONS: The PKC isoforms expressed in human arterial SMC differ from those reported in animal models. Their specific locations and response to stimulation suggest unique functions in cellular regulation and provide the groundwork for further investigation into their role in the development of vascular disease and regulation of matrix metabolism.

Antibodies↗
PubMed1998

Suppression of inflammatory neurotoxins by highly active antiretroviral therapy in human immunodeficiency virus-associated dementia.

A human immunodeficiency virus type 1 (HIV)-seropositive, antiretroviral-naive patient presented with significant cognitive dysfunction. Neuropsychologic, neuroradiologic, immunologic, and virologic studies confirmed HIV-associated dementia (HAD). After 12 weeks of highly active antiretroviral therapy (HAART) with ibuprofen, dramatic improvements were demonstrated in neurologic function and were sustained for > 1 year. HIV-1 RNA in cerebrospinal fluid (CSF) decreased from 10(5) to 10(4) copies/mL after 4 weeks. After 20 weeks of therapy, plasma viremia decreased from 10(6) copies/mL to undetectable (< 96 copies/mL). Assays of neurotoxins (tumor necrosis factor-alpha, quinolinic acid, and nitric oxide) in plasma and CSF were considerably elevated at presentation and significantly decreased after therapy. Baseline plasma and CSF demonstrated neurotoxic activities in vitro, which also reduced markedly. These data, taken together, support the notion that HAD is a reversible metabolic encephalopathy fueled by viral replication. HAART used with nonsteroidal antiinflammatory agents leads to the suppression of inflammatory neurotoxins and can markedly improve neurologic function in HAD.

AIDS Dementia Complex↗
PubMed1998

Human immunodeficiency virus neurotropism: an analysis of viral replication and cytopathicity for divergent strains in monocytes and microglia.

Productive replication of human immunodeficiency virus type 1 (HIV-1) in brain macrophages and microglia is a critical component of viral neuropathogenesis. However, how virus-macrophage interactions lead to neurological disease remains incompletely understood. Possibly, a differential ability of virus to replicate in brain tissue macrophages versus macrophages in other tissues underlies HIV-1 neurovirulence. To these ends, we established systems for the isolation and propagation of pure populations of human microglia and then analyzed the viral life cycles of divergent HIV-1 strains in these cells and in cultured monocytes by using identical viral inocula and indicator systems. The HIV-1 isolates included those isolated from blood, lung tissue, cerebrospinal fluids (CSF), and brain tissues of infected subjects: HIV-1(ADA) and HIV-1(89.6) (from peripheral blood mononuclear cells), HIV-1(DJV) and HIV-1(JR-FL) (from brain tissue), HIV-1(SF162) (from CSF), and HIV-1(BAL) (from lung tissue). The synthesis of viral nucleic acids and viral mRNA, cytopathicity, and release of progeny virions were assessed. A significant heterogeneity among macrophage-tropic isolates for infection of monocytes and microglia was demonstrated. Importantly, a complete analysis of the viral life cycle revealed no preferential differences in the abilities of the HIV-1 strains tested to replicate in microglia and/or monocytes. Macrophage tropism likely dictates the abilities of HIV-1 to invade, replicate, and incite disease within its microglial target cells.

Cells, Cultured↗
PubMed1998

Role of the beta-chemokine receptors CCR3 and CCR5 in human immunodeficiency virus type 1 infection of monocytes and microglia.

Human immunodeficiency virus type 1 (HIV-1) infection in mononuclear phagocyte lineage cells (monocytes, macrophages, and microglia) is a critical component in the pathogenesis of viral infection. Viral replication in macrophages serves as a reservoir, a site of dissemination, and an instigator for neurological sequelae during HIV-1 disease. Recent studies demonstrated that chemokine receptors are necessary coreceptors for HIV-1 entry which determine viral tropism for different cell types. To investigate the relative contribution of the beta-chemokine receptors CCR3 and CCR5 to viral infection of mononuclear phagocytes we utilized a panel of macrophage-tropic HIV-1 strains (from blood and brain tissue) to infect highly purified populations of monocytes and microglia. Antibodies to CD4 (OKT4A) abrogated HIV-1 infection. The beta chemokines and antibodies to CCR3 failed to affect viral infection of both macrophage cell types. Antibodies to CCR5 (3A9) prevented monocyte infection but only slowed HIV replication in microglia. Thus, CCR5, not CCR3, is an essential receptor for HIV-1 infection of monocytes. Microglia express both CCR5 and CCR3, but antibodies to them fail to inhibit viral entry, suggesting the presence of other chemokine receptors for infection of these cells. These studies demonstrate the importance of mononuclear phagocyte heterogeneity in establishing HIV-1 infection and persistence.

Animals↗
PubMed1998

Matrix metalloproteinase-2 production and its binding to the matrix are increased in abdominal aortic aneurysms.

Degradation of the elastic media is a hallmark of abdominal aortic aneurysms (AAAs). We examined the expression of 2 elastolytic matrix metalloproteinases (MMPs), MMP-2 and MMP-9, in AAA aortic tissues compared with those from atherosclerotic occlusive disease (AOD) and nondiseased control tissues. Quantitative competitive reverse transcription-polymerase chain reaction and gelatin zymography showed increased MMP-9 mRNA and protein in both AAA and AOD tissues compared with those in control tissue, but there was no significant difference between AAA and AOD. In contrast, MMP-2 mRNA and protein levels were significantly higher in AAA than in AOD or control tissues. Sequential extraction of the MMPs from the aortic tissue with a physiological salt solution, 2% dimethylsulfoxide (DMSO), and 10 mol/L urea showed that large amounts of MMP-2 and MMP-9 were bound to the matrix. The most conspicuous finding was that the levels of MMP-2 were significantly elevated in the DMSO fraction in AAA tissues compared with AOD and control tissues. In addition, a large portion of MMP-2 found in the DMSO and urea fractions was in the active 62-kDa form, indicating that the precursor of MMP-2 in AAA is largely activated locally and binds to the tissue matrix tightly. By immunolocalization, MMP-9 was found to be primarily produced by macrophages and MMP-2 by mesenchymal cells. The production of MMP-2 was prominent when mesenchymal cells were surrounded by inflammatory cells, suggesting paracrine modulation of MMP-2 expression in AAAs. These observations emphasize that MMP-2 participates in the progression of AAAs by degrading aortic tissue matrix components.

Aged↗
PubMed1997

A model for monocyte migration through the blood-brain barrier during HIV-1 encephalitis.

HIV-1 invades the central nervous system early during viral infection, but neurologic impairment usually occurs years later. The strongest predictor for clinical dementia is the absolute numbers of immunocompetent brain macrophages. Thus, how monocytes penetrate the brain during disease remains critical for understanding the neuropathogenic mechanisms of HIV-1 encephalitis. To these ends, we constructed an artificial blood-brain barrier (BBB) consisting of a matrix-coated membrane with brain microvascular endothelial cells (BMVEC) on one side and astrocytes on the other. Astrocyte endfeet contacted the monolayer of BMVEC that formed tight junctions. To determine the role of viral and immune factors in monocyte penetration across the BBB, HIV-infected or uninfected monocytes with or without immune stimulation were placed onto the upper chamber of the BBB model system. Placement of immune-stimulated (LPS-treated) cells onto the BBB construct elicited gaps between BMVEC, with bulging of nuclear zones and increased numbers of vesicular Golgi complexes and endoplasmic reticulum. This correlated with a profound increase (up to 20-fold) in the number of migrating cells. Viral infection did not enhance monocyte migration. The activated monocytes showed increased numbers of philopodia, lysosomes, and vesicular Golgi complexes and expressed large levels of proinflammatory cytokines (TNF-alpha, IL-6, and IL-10). These data suggest that a major mechanism for the transendothelial migration of monocytes during HIV encephalitis is the immune activation that accompanies viral infection of the central nervous system.

AIDS Dementia Complex↗
PubMed1997

Development of laboratory and animal model systems for HIV-1 encephalitis and its associated dementia.

The neuropathogenesis of HIV-1 encephalitis and its associated dementia revolves around sustained viral replication in cells of mononuclear phagocyte origin (brain macrophages, multinucleated giant cells, and microglia). Macrophage secretory factors play important roles in facilitating monocyte trafficking into the brain, in regulating productive viral replication, and in producing neurotoxic responses. To study these events, we constructed an artificial blood-brain barrier (BBB) to assay monocyte transendothelial migration and developed an animal model system for HIV-1 encephalitis to ascertain the role that virus-infected mononuclear phagocytes play in disease pathogenesis. The BBB model was composed of brain microvascular endothelial cells and astrocytes placed on opposite sides of a porous membrane. Monocyte activation, not HIV-1 infection per se, was the central event affecting monocyte BBB migration. Many of the pathological features of HIV-1 encephalitis were reproduced in SCID mice stereotactically inoculated with virus-infected monocytes. These included widespread astrogliosis, apoptosis of neurons, dendritic damage, and macrophage/microglial activation. Such laboratory and animal model systems are being used to ascertain the pathogenic potential of virus-infected macrophages in brain and ways to curb such injurious effects.

AIDS Dementia Complex↗
PubMed1997

Dexamethasone therapy worsens the neuropathology of human immunodeficiency virus type 1 encephalitis in SCID mice.

Human immunodeficiency virus (HIV) dementia is a late complication of viral infection. Cognitive dysfunction revolves around the secretion of neurotoxins from immunologically competent virus-infected brain macrophages and microglia. Such macrophage neurotoxins are inflammatory factors that produce selective neuronal dysfunction and ultimately cell death. To evaluate the potential efficacy of antiinflammatory therapy for HIV dementia, dexamethasone was administered to severe combined immunodeficient mice with HIV-1 encephalitis. Mice were given therapeutic doses of dexamethasone before intracerebral inoculation with HIV-1-infected human monocytes. Histochemical evaluation showed a worsening of neuropathology after treatment, with astrogliosis and increased apoptosis of neurons. Laboratory investigation of the mechanisms for the dexamethasone effects revealed increased viability of HIV-infected macrophages and incomplete suppression of neurotoxic inflammatory secretions. The results suggest the need for caution in administering glucocorticoids for treatment of HIV encephalitis in humans.

AIDS Dementia Complex↗
PubMed1997

An analysis of HIV-1-associated inflammatory products in brain tissue of humans and SCID mice with HIV-1 encephalitis.

The human immunodeficiency virus type 1 (HIV)-associated dementia complex (ADC) is a neuroimmunological disorder fueled by viral replication in mononuclear phagocytes (MP) (brain macrophages and microglia). The elucidation of MP inflammatory factors involved in neurological dysfunction is pivotal for unraveling pathogenic mechanisms and in developing new therapies for this disease. Recent advances in animal model systems for ADC and its associated encephalitis have provided important insights into how virus-infected macrophages cause brain injury. Indeed, the stereotactic inoculation of HIV infected monocytes into the basal ganglia/cortex of mice with severe combined immunodeficiency disease (SCID) results in pathological features similar to those of human HIV-1 encephalitis (HIVE). We used this SCID model to study the roles of macrophage secretory factors in HIVE. The expression of interleukin-1 (IL-1 beta, IL-6, IL-10), tumor necrosis factors-alpha (TNF alpha), vascular endothelial growth factor (VEGF), and adhesion molecules (E-selectin, intracellular cell adhesion molecule (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1)) in encephalitic brains of mice and humans was evaluated by semi-quantitative polymerase chain reaction (PCR). In SCID mice with HIVE, human and mouse TNF alpha, and mouse IL-6, VEGF, VCAM-1 and E-selectin were expressed at high levels. These results paralleled, to a great extent, those in HIVE brain tissues. Laser scanning confocal microscopy performed to assess the associated neuronal damage showed that microtubule associated protein-2 (MAP-2) immunoreactive dendrites were significantly reduced in both the ipsilateral and contralateral hemispheres of encephalitic mice. These results demonstrate the importance of macrophage inflammatory products in the pathogenesis of HIVE and further validates this model of viral encephalitis in SCID mice.

AIDS Dementia Complex↗
PubMed1996

Mechanisms for the transendothelial migration of HIV-1-infected monocytes into brain.

HIV-1 penetration of the brain is a pivotal event in the neuropathogenesis of AIDS-associated dementia. The establishment of productive viral replication or up-regulation of adhesion molecule expression on brain microvascular endothelial cells (BMVEC) could permit entry of HIV into the central nervous system. To investigate the contribution of both, we inoculated primary human BMVEC with high titer macrophage-tropic HIV-1 or cocultured them with virus-infected monocytes. In both instances, BMVEC failed to demonstrate productive viral replication. Cell to cell contact between monocytes and microvascular endothelium resulted in E-selectin expression on BMVEC. BMVEC. cocultured with LPS-activated HIV-infected monocytes expressed even higher levels of E-selectin and vascular cell adhesion molecule-1 (VCAM-1). Transwell assays supported a role of soluble factors, from virus-infected monocytes, for the induction of adhesion molecules on BMVEC. To verify the in vivo relevance of these findings, levels of adhesion molecules were compared with those of proinflammatory cytokines and HIV-1 gene products in brain tissue of AIDS patients with or without encephalitis and HIV-seronegative controls. E-Selectin, and to a lesser degree VCAM-1, paralleled the levels of HIV-1 gene products and proinflammatory cytokines in brain tissue of subjects with encephalitis. Most importantly, an association between macrophage infiltration and increased endothelial cell adhesion molecules was observed in encephalitic brains. Monocyte binding to encephalitic brain tissue was blocked with Abs to VCAM-1 and E-selectin. These data, taken together, suggest that HIV entry into brain is, in part, a consequence of the ability of virus-infected and immune-activated monocytes to induce adhesion molecules on brain endothelium.

Base Sequence↗
PubMed1996

Human immunodeficiency virus encephalitis in SCID mice.

The human immunodeficiency virus (HIV) is neuroinvasive and commonly causes cognitive and motor deficits during the later stages of viral infection. (referred to as HIV dementia). The mechanism(s) for disease revolves around secretory products produced from immune-activated brain macrophages/microglia. Recently, we developed an animal model system for HIV dementia that contains xenografts of HIV-1-infected cells inoculated into brains of mice with severe combined immunodeficiency (SCID). This animal system was used to quantitatively evaluate HIV-induced neuropathology. Xenografts of HIV-1-infected human monocytes (placed into the putamen and cortex of SCID mice) remained viable for 5 weeks. HIV-1 p24 antigen expression in mouse brain was persistent. Progressive inflammatory responses (including astrogliosis and cytokine production), which began at 3 days, peaked at day 12. The range of astrocyte proliferative reactions exceeded the inoculation site by > 1000 microns. Brains with virus-infected monocytes showed a > or = 1.6-fold increase in glial fibrillary acidic protein (staining distribution and intensity) as compared with similarly inoculated brains with uninfected control monocytes. These findings paralleled the accumulation and activation of murine microglia (increased branching of cell processes, formation of microglial nodules, interleukin (IL)-1 beta and IL-6 expression). An inflammatory reaction of human monocytes (as defined by HLA-DR, IL-1 beta, IL-6, and tumor necrosis factor-alpha expression) and neuronal injury (apoptosis) also developed after virus-infected monocyte xenograft placement into mouse brain tissue. These data, taken together, demonstrate that this SCID mouse model of HIV-1 neuropathogenesis can reproduce key aspects of disease (virus-infected macrophages, astrocytosis, microglial activation, and neuronal damage). This model may serve as an important means for therapeutic development directed toward improving mental function in HIV-infected subjects with cognitive and motor dysfunction.

AIDS Dementia Complex↗
PubMed1995

A regulatory role for astrocytes in HIV-1 encephalitis. An overexpression of eicosanoids, platelet-activating factor, and tumor necrosis factor-alpha by activated HIV-1-infected monocytes is attenuated by primary human astrocytes.

HIV-1-infected brain macrophages participate in neurologic dysfunction through their continual secretion of neurotoxins. We previously demonstrated that astroglial cells activate HIV-1-infected monocytes to produce such neurotoxic activities. In this study, the mechanism underlying these monocyte secretory activities was unraveled and found dependent on HIV-1's ability to prime monocytes for activation. LPS stimulation of HIV-1-infected monocytes resulted in an overexpression of eicosanoids, platelet-activating factor (PAF), and TNF-alpha. This was dependent on the level of HIV-1 infection and monocyte stimulation. Cell to cell interactions between activated virus-infected monocytes and primary human astrocytes reduced monocyte secretions. The capacity of astrocytes to deactivate monocytes was, notably, TGF-beta independent. Although astrocytes constitutively produced latent TGF-beta 2, HIV-1-infected monocytes neither affected TGF-beta 2 production nor converted it into a bioactive molecule. Furthermore, addition of rTGF-beta 1 or rTGF-beta 2 or its Abs to LPS-stimulated monocyte-astrocyte mixtures had no effect on monokine production. In contrast, addition of rIL-10 to LPS-stimulated monocytes produced a dose-dependent decrease in TNF-alpha. IL-10 mRNAs were detected in monocytes, but not astrocytes, following LPS treatment. These results suggest that macrophage activation, a major component of HIV-1 infection in the brain, precipitates neuronal injury by causing virus-infected cells to synthesize neurotoxins. The neurotoxins produced by monocytes are then regulated by astrocytes. Astrocytes therefore, can play either positive or negative roles for disease depending on prior macrophage activation. These findings begin to unravel the cellular control mechanisms that influence cognitive and motor dysfunctions in HIV-1-infected individuals.

Astrocytes↗
PubMed1995

Presence of virion protein x (Vpx) of simian immunodeficiency virus SIVmac 251 in target cells in vivo.

Localization of virion-associated protein x (Vpx) of SIVmac 251 was studied in lymph nodes and liver of six SIVmac-infected monkeys. Vpx was found associated with the network of follicular dendritic cells and macrophages in lymph nodes and/or livers from five out of six animals by immunohistochemistry. Although the humoral response to Vpx occurs in only 50% of the animals, the presence of Vpx in target cell or antibodies to Vpx in all the monkeys studied, suggests that Vpx may be necessary for viral replication in vivo.

Animals↗
PubMed1995

The development of animal model systems for HIV-1 encephalitis and its associated dementia.

The human immunodeficiency virus (HIV) is neuroinvasive and can be neurovirulent. Indeed, 20-30% of individuals with the acquired immune deficiency syndrome (AIDS) develop cognitive and motor dysfunction (termed the AIDS dementia complex or HIV dementia) coincident with advanced immunosuppression. Despite massive research efforts to discern viral neuropathogenic mechanisms, much remains incompletely understood. Recently, we and others developed animal model systems to elucidate how HIV infection within the brain can lead to impairment of central nervous system function. In this report, we evaluate each of the published animal models for their ability to mirror HIV dementia. Ease of handling and expense were also under consideration. Ultimately, studies in animal systems should permit a better understanding of the nature of HIV-1-induced neurological injury and aid in the development of effective treatments for this dreaded complication of HIV infection.

AIDS Dementia Complex↗