Ethanol suppression of peripheral blood mononuclear cell trafficking across brain endothelial cells in immunodeficiency virus infection

Earlier studies suggested that the combination of alcohol use and immunodeficiency virus infection resulted in more severe neurologic disease than either condition individually. These deleterious interactions could be due to increased immune cell and virus trafficking or may result from interactions between ethanol and human immunodeficiency virus (HIV)-associated toxicity within the brain. To determine the extent to which increased trafficking played a role, we examined the effect of ethanol on the migration of different peripheral blood mononuclear cell (PBMCs) subsets across a brain endothelial cell monolayer. We utilized combinations of feline brain endothelial cells with astrocytes, and/or microglia with either acute exposure to 0.08 g/dL ethanol, a combination of ethanol and feline immunodeficiency virus (FIV), or FIV alone. Adherence of PBMCs to endothelium was increased in all combinations of cells with the addition of ethanol. Despite increased PBMC adhesion with ethanol treatment, transmigration of B cells, monocytes, CD4 T cells and CD8 T cells was not increased and was actually decreased in the presence of astrocytes. Expression of three common adhesion molecules, intercellular adhesion molecule-1 (ICAM1), ICAM2, and vascular cell adhesion molecule, was unchanged or slightly decreased by ethanol. This indicated that although adherence is increased by ethanol it is not due to an increased expression of adhesion molecules. RANTES, MIP1α, MIP1β, and MCP-1 mRNA expression was also studied in brain endothelial cells, astrocytes and microglia by reverse transcriptase-polymerase chain reaction. Ethanol treatment of astrocytes resulted in modest changes of message while FIV caused 7–92-fold increases. The combination of ethanol and FIV reversed the large increase in RANTES and MIP1α message in astrocytes but increased MIP1β and MCP to 20–38-fold over control cells. Thus, modest concentrations of alcohol do not directly influence immune cell trafficking at the endothelium but may exert more complex effects on chemokine expression from astrocytes when combined with FIV

Endothelial cell suppression of peripheral blood mononuclear cell trafficking in vitro during acute exposure to feline immunodeficiency virus

Trafficking of peripheral blood mononuclear cells (PBMCs) into the brain is a critical step in the initiation of human immunodeficiency virus (HIV)-associated central nervous system disease. To examine potential factors that control trafficking during the earliest stages of infection, PBMC transmigration across a cultured feline brain endothelial cell (BECs) monolayer was measured after selective exposure of various cell types to feline immunodeficiency virus (FIV). Infection of the PBMCs with FIV increased the trafficking of monocytes and CD4 and CD8 T cells. Additional exposure of the BECs to FIV suppressed mean monocyte, CD4 T cell, and CD8 T cell trafficking. B cell trafficking was unaltered by these changing conditions. Subsequent exposure of astrocytes or microglia to FIV altered transmigration of different PBMC subsets in different ways. Treated microglia compared with treated astrocytes decreased monocyte transmigration, whereas B cell transmigration was increased significantly. When both astrocytes and microglia were exposed to FIV, an increase in CD8 T cell transmigration relative to BECs alone, to BECs plus astrocytes, or to BECs plus microglia was demonstrated. Thus, initial exposure of PBMCs to FIV is sufficient to induce a general increase in trafficking, whereas initial exposure of endothelial cells to FIV tends to down-regulate this effect. Selectivity of trafficking of specific PBMC subsets is apparent only after exposure of cells of the central nervous system to FIV in co-culture with the endothelium

Transmigration of macrophages across the choroid plexus epithelium in response to the feline immunodeficiency virus

Although lentiviruses such as human, feline and simian immunodeficiency viruses (HIV, FIV, SIV) rapidly gain access to cerebrospinal fluid (CSF), the mechanisms that control this entry are not well understood. One possibility is that the virus may be carried into the brain by immune cells that traffic across the blood–CSF barrier in the choroid plexus. Since few studies have directly examined macrophage trafficking across the blood–CSF barrier, we established transwell and explant cultures of feline choroid plexus epithelium and measured trafficking in the presence or absence of FIV. Macrophages in co-culture with the epithelium showed significant proliferation and robust trafficking that was dependent on the presence of epithelium. Macrophage migration to the apical surface of the epithelium was particularly robust in the choroid plexus explants where 3-fold increases were seen over the first 24 h. Addition of FIV to the cultures greatly increased the number of surface macrophages without influencing replication. The epithelium in the transwell cultures was also permissive to PBMC trafficking, which increased from 17 to 26% of total cells after exposure to FIV. Thus, the choroid plexus epithelium supports trafficking of both macrophages and PBMCs. FIV significantly enhanced translocation of macrophages and T cells indicating that the choroid plexus epithelium is likely to be an active site of immune cell trafficking in response to infection

Cell trafficking through the choroid plexus

The choroid plexus is a multifunctional organ that sits at the interface between the blood and cerebrospinal fluid (CSF). It serves as a gateway for immune cell trafficking into the CSF and is in an excellent position to provide continuous immune surveillance by CD4+ T cells, macrophages and dendritic cells and to regulate immune cell trafficking in response to disease and trauma. However, little is known about the mechanisms that control trafficking through this structure. Three cell types within the choroid plexus, in particular, may play prominent roles in controlling the development of immune responses within the nervous system: the epithelial cells, which form the blood-CSF barrier, and resident macrophages and dendritic cells in the stromal matrix. Adhesion molecule and chemokine expression by the epithelial cells allows substantial control over the selection of cells that transmigrate. Macrophages and dendritic cells can present antigen within the choroid plexus and/or transmigrate into the cerebral ventricles to serve a variety of possible immune functions. Studies to better understand the diverse functions of these cells are likely to reveal new insights that foster the development of novel pharmacological and macrophage-based interventions for the control of CNS immune responses

The neuropathogenesis of feline immunodeficiency virus infection: Barriers to overcome

Feline immunodeficiency virus (FIV), like human immunodeficiency virus (HIV)-1, is a neurotropic lentivirus, and both natural and experimental infections are associated with neuropathology. FIV enters the brain early following experimental infection, most likely via the blood-brain and blood-cerebrospinal fluid barriers. The exact mechanism of entry, and the factors that influence this entry, are not fully understood. As FIV is a recognised model of HIV-1 infection, understanding such mechanisms is important, particularly as HIV enters the brain early in infection. Furthermore, the development of strategies to combat this central nervous system (CNS) infection requires an understanding of the interactions between the virus and the CNS. In this review the results of both in vitro and in vivo FIV studies are assessed in an attempt to elucidate the mechanisms of viral entry into the brain

Conditioning laboratory cats to handling and transport

As research subjects, cats have contributed substantially to our understanding of biological systems, from the development of mammalian visual pathways to the pathophysiology of feline immunodeficiency virus as a model for human immunodeficiency virus. Few studies have evaluated humane methods for managing cats in laboratory animal facilities, however, in order to reduce fear responses and improve their welfare. The authors describe a behavioral protocol used in their laboratory to condition cats to handling and transport. Such behavioral conditioning benefits the welfare of the cats, the safety of animal technicians and the quality of feline research data

Cell trafficking through the choroid plexus

The choroid plexus is a multifunctional organ that sits at the interface between the blood and cerebrospinal fluid (CSF). It serves as a gateway for immune cell trafficking into the CSF and is in an excellent position to provide continuous immune surveillance by CD4(+) T cells, macrophages and dendritic cells and to regulate immune cell trafficking in response to disease and trauma. However, little is known about the mechanisms that control trafficking through this structure. Three cell types within the choroid plexus, in particular, may play prominent roles in controlling the development of immune responses within the nervous system: the epithelial cells, which form the blood-CSF barrier, and resident macrophages and dendritic cells in the stromal matrix. Adhesion molecule and chemokine expression by the epithelial cells allows substantial control over the selection of cells that transmigrate. Macrophages and dendritic cells can present antigen within the choroid plexus and/or transmigrate into the cerebral ventricles to serve a variety of possible immune functions. Studies to better understand the diverse functions of these cells are likely to reveal new insights that foster the development of novel pharmacological and macrophage-based interventions for the control of CNS immune responses

Endothelial cell suppression of peripheral blood mononuclear cell trafficking in vitro during acute exposure to feline immunodeficiency virus

Trafficking of peripheral blood mononuclear cells (PBMCs) into the brain is a critical step in the initiation of human immunodeficiency virus (HIV)-associated central nervous system disease. To examine potential factors that control trafficking during the earliest stages of infection, PBMC transmigration across a cultured feline brain endothelial cell (BECs) monolayer was measured after selective exposure of various cell types to feline immunodeficiency virus (FIV). Infection of the PBMCs with FIV increased the trafficking of monocytes and CD4 and CD8 T cells. Additional exposure of the BECs to FIV suppressed mean monocyte, CD4 T cell, and CD8 T cell trafficking. B cell trafficking was unaltered by these changing conditions. Subsequent exposure of astrocytes or microglia to FIV altered transmigration of different PBMC subsets in different ways. Treated microglia compared with treated astrocytes decreased monocyte transmigration, whereas B cell transmigration was increased significantly. When both astrocytes and microglia were exposed to FIV, an increase in CD8 T cell transmigration relative to BECs alone, to BECs plus astrocytes, or to BECs plus microglia was demonstrated. Thus, initial exposure of PBMCs to FIV is sufficient to induce a general increase in trafficking, whereas initial exposure of endothelial cells to FIV tends to down-regulate this effect. Selectivity of trafficking of specific PBMC subsets is apparent only after exposure of cells of the central nervous system to FIV in co-culture with the endothelium

Conditioning laboratory cats to handling and transport

As research subjects, cats have contributed substantially to our understanding of biological systems, from the development of mammalian visual pathways to the pathophysiology of feline immunodeficiency virus as a model for human immunodeficiency virus. Few studies have evaluated humane methods for managing cats in laboratory animal facilities, however, in order to reduce fear responses and improve their welfare. The authors describe a behavioral protocol used in their laboratory to condition cats to handling and transport. Such behavioral conditioning benefits the welfare of the cats, the safety of animal technicians and the quality of feline research data

The neuropathogenesis of feline immunodeficiency virus infection: Barriers to overcome

Feline immunodeficiency virus (FIV), like human immunodeficiency virus (HIV)-1, is a neurotropic lentivirus, and both natural and experimental infections are associated with neuropathology. FIV enters the brain early following experimental infection, most likely via the blood-brain and blood-cerebrospinal fluid barriers. The exact mechanism of entry, and the factors that influence this entry, are not fully understood. As FIV is a recognised model of HIV-1 infection, understanding such mechanisms is important, particularly as HIV enters the brain early in infection. Furthermore, the development of strategies to combat this central nervous system (CNS) infection requires an understanding of the interactions between the virus and the CNS. In this review the results of both in vitro and in vivo FIV studies are assessed in an attempt to elucidate the mechanisms of viral entry into the brain