RESUMEN
Antiretroviral therapy (ART) has transformed HIV into a chronic condition, lengthening and improving the lives of individuals living with this virus. Despite successful suppression of HIV replication, people living with HIV (PLWH) are susceptible to a growing number of comorbidities, including neuroHIV that results from infection of the central nervous system (CNS). Alterations in the dopaminergic system have long been associated with HIV infection of the CNS. Studies indicate that changes in dopamine concentrations not only alter neurotransmission, but also significantly impact the function of immune cells, contributing to neuroinflammation and neuronal dysfunction. Monocytes/macrophages, which are a major target for HIV in the CNS, are responsive to dopamine. Therefore, defining more precisely the mechanisms by which dopamine acts on these cells, and the changes in cellular function elicited by this neurotransmitter are necessary to develop therapeutic strategies to treat neuroHIV. This is especially important for vulnerable populations of PLWH with chemically altered dopamine concentrations, such as individuals with substance use disorder (SUD), or aging individuals using dopamine-altering medications. The specific neuropathologic and neurocognitive consequences of increased CNS dopamine remain unclear. This is due to the complex nature of HIV neuropathogenesis, and logistical and technical challenges that contribute to inconsistencies among cohort studies, animal models and in vitro studies, as well as lack of demographic data and access to human CNS samples and cells. This review summarizes current understanding of the impact of dopamine on HIV neuropathogenesis, and proposes new experimental approaches to examine the role of dopamine in CNS HIV infection. Graphical abstract HIV Neuropathogenesis in the Presence of a Disrupted Dopamine System. Both substance abuse disorders and the use of dopaminergic medications for age-related diseases are associated with changes in CNS dopamine concentrations and dopaminergic neurotransmission. These changes can lead to aberrant immune function, particularly in myeloid cells, which contributes to the neuroinflammation, neuropathology and dysfunctional neurotransmission observed in dopamine-rich regions in HIV+ individuals. These changes, which are seen despite the use antiretroviral therapy (ART), in turn lead to further dysregulation of the dopamine system. Thus, in individuals with elevated dopamine, the bi-directional interaction between aberrant dopaminergic neurotransmission and HIV infection creates a feedback loop contributing to HIV associated neurocognitive dysfunction and neuroHIV. However, the distinct contributions and interactions made by HIV infection, inflammatory mediators, ART, drugs of abuse, and age-related therapeutics are poorly understood. Defining more precisely the mechanisms by which these factors influence the development of neurological disease is critical to addressing the continued presence of neuroHIV in vulnerable populations, such as HIV-infected older adults or drug abusers. Due to the complexity of this system, understanding these effects will require a combination of novel experimental modalities in the context of ART. These will include more rigorous epidemiological studies, relevant animal models, and in vitro cellular and molecular mechanistic analysis.
Asunto(s)
Complejo SIDA Demencia/metabolismo , Antirretrovirales/metabolismo , Dopamina/metabolismo , Trastornos Relacionados con Sustancias/metabolismo , Complejo SIDA Demencia/tratamiento farmacológico , Complejo SIDA Demencia/epidemiología , Animales , Antirretrovirales/farmacología , Antirretrovirales/uso terapéutico , Sistema Nervioso Central/efectos de los fármacos , Sistema Nervioso Central/metabolismo , Infecciones por VIH/tratamiento farmacológico , Infecciones por VIH/epidemiología , Infecciones por VIH/metabolismo , Humanos , Trastornos Relacionados con Sustancias/epidemiologíaRESUMEN
HIV is a major public health issue, and infection of CD4(+) T lymphocytes is one of its key features. Whereas several cellular proteins have been identified that facilitate viral infection and replication, the role of hemichannels in these processes has not been fully characterized. We now show that the HIV isolates, R5 and X4, induced a transient-early (5-30 min) and a later, persistent (48-120 h) opening of Panx1 hemichannels, which was dependent on the binding of HIV to CD4 and CCR5/CXCR4 receptors. Blocking Panx1 hemichannels by reducing their opening or protein expression inhibited HIV replication in CD4(+) T lymphocytes. Thus, our findings demonstrate that Panx1 hemichannels play an essential role in HIV infection.
Asunto(s)
Linfocitos T CD4-Positivos/virología , Conexinas/fisiología , VIH/fisiología , Proteínas del Tejido Nervioso/fisiología , Conexina 43/fisiología , Humanos , Receptores CCR5/fisiología , Receptores CXCR4/fisiología , Replicación ViralRESUMEN
AIM: Multiple sclerosis (MS) is an autoimmune disease of the central nervous system, characterized by demyelination of white matter, loss of myelin forming oligodendrocytes, changes in the blood-brain barrier (BBB) and leucocyte infiltration. Myelin basic protein (MBP) is a component of the myelin sheath. Degradation of myelin is believed to be an important step that leads to MS pathology. Transmigration of leucocytes across the vasculature, and a compromised BBB participate in the neuroinflammation of MS. We examined the expression and regulation of the chemokine (C-C motif) ligand 2 (CCL2) and the cytokine interleukin-6 (IL-6) in human endothelial cells (EC), a component of the BBB, after treatment with MBP. METHODS: EC were treated with full-length MBP. CCL2 and IL-6 protein were determined by ELISA. Western blot analysis was used to determine signalling pathways. A BBB model was treated with MBP and permeability was assayed using albumin conjugated to Evan's blue dye. The levels of the tight junction proteins occludin and claudin-1, and matrix metalloprotease (MMP)-2 were assayed by Western blot. RESULTS: MBP significantly induced CCL2 and IL-6 protein from EC. This induction was partially mediated by the p38 MAPK pathway as there was phosphorylation after MBP treatment. MBP treatment of a BBB model caused an increase in permeability that correlated with a decrease in occludin and claudin-1, and an induction of MMP2. CONCLUSION: These data demonstrate that MBP induces chemotactic and inflammatory mediators. MBP also alters BBB permeability and tight junction expression, indicating additional factors that may contribute to the BBB breakdown characteristic of MS.
Asunto(s)
Permeabilidad Capilar/fisiología , Quimiocina CCL2/biosíntesis , Células Endoteliales/metabolismo , Interleucina-6/biosíntesis , Esclerosis Múltiple/metabolismo , Proteína Básica de Mielina/metabolismo , Barrera Hematoencefálica/efectos de los fármacos , Barrera Hematoencefálica/metabolismo , Barrera Hematoencefálica/patología , Western Blotting , Permeabilidad Capilar/efectos de los fármacos , Ensayo de Inmunoadsorción Enzimática , Humanos , Esclerosis Múltiple/patología , Proteína Básica de Mielina/farmacologíaRESUMEN
Cell to cell communication is essential for the organization/coordination of multicellular systems and cellular development. Cellular communication is mediated by soluble factors, including growth factors, neurotransmitters, cytokines/chemokines, gap junctions, and the recently described tunneling nanotubes (TNT). TNT are long cytoplasmatic bridges that enable long range directed communication between cells. The proposed function for TNT is the cell-to-cell transfer of large cellular structures such as vesicles and organelles. We demonstrate that HIV-infection of human macrophages results in an increased number of TNT, and show HIV particles within these structures. We propose that HIV "highjacks" TNT communication to spread HIV through an intercellular route between communicated cells, contributing to the pathogenesis of AIDS.
Asunto(s)
VIH/fisiología , Macrófagos/citología , Macrófagos/virología , Células Cultivadas , Proteína p24 del Núcleo del VIH/metabolismo , HumanosRESUMEN
HIV tat is the transactivator of HIV-1, supporting efficient viral replication by stabilizing the transcription of viral genes. Tat can be released from HIV-infected cells and alter several functions in uninfected cells. In the brain, tat induces neuronal dysfunction/toxicity, even though neurons cannot be directly infected with HIV, resulting in CNS pathology, such as the dementia and encephalitis associated with NeuroAIDS. This review discusses the most recent data addressing tat-induced neurotoxicity and integrates these new findings in the context of NeuroAIDS.
Asunto(s)
Complejo SIDA Demencia/etiología , Encefalitis Viral/etiología , Productos del Gen tat/toxicidad , Infecciones por VIH/complicaciones , Neuronas/patología , Apoptosis , Encéfalo/patología , Quimiocina CCL2/metabolismo , Humanos , Productos del Gen tat del Virus de la Inmunodeficiencia HumanaRESUMEN
Human immunodeficiency virus (HIV) infection is characterized by viral entry into the central nervous system (CNS), which is mediated, in part, by the transmigration of HIV-infected monocytes into the brain. The elaboration of chemokines and other factors by these infected cells contributes to CNS inflammation and cognitive impairment in a significant number of HIV-infected individuals. Recently, we demonstrated that HIV-infected monocyte transmigration into the CNS is enhanced greatly by the chemokine CC chemokine ligand 2 (CCL2)/monocyte chemoattractant protein-1. Platelet endothelial cell adhesion molecule-1 (PECAM-1) plays an important role in leukocyte transmigration across the endothelium of the systemic vasculature by mediating homophilic interactions between endothelial cells (EC)-EC and EC-leukocytes, thus preserving vessel integrity. The role of PECAM-1 in HIV-infected leukocyte transmigration across the blood brain barrier (BBB) and NeuroAIDS has not been characterized. We demonstrate that in brain tissue from individuals with HIV encephalitis, there is an accumulation of cleaved, soluble forms of the extracellular region of PECAM-1 (sPECAM-1). In addition, HIV-infected individuals have elevated levels of sPECAM-1 in their sera. Our in vitro data demonstrate that HIV-infected leukocytes, when treated with CCL2, shed sPECAM-1, suggesting a mechanism of extracellular PECAM-1 cleavage and release dependent on HIV infection and CCL2. We hypothesize that sPECAM-1 production by HIV-infected leukocytes, resulting in the accumulation of sPECAM-1 within the CNS vasculature and the generation of truncated, intracellular forms of PECAM-1 within leukocytes, alters PECAM-1 interactions between EC-EC and EC-leukocytes, thus contributing to enhanced transmigration of HIV-infected leukocytes into the CNS and changes in BBB permeability during the pathogenesis of NeuroAIDS.
Asunto(s)
Complejo SIDA Demencia/inmunología , Barrera Hematoencefálica/inmunología , Encéfalo/inmunología , Quimiotaxis de Leucocito/inmunología , Monocitos/inmunología , Molécula-1 de Adhesión Celular Endotelial de Plaqueta/inmunología , Complejo SIDA Demencia/patología , Complejo SIDA Demencia/fisiopatología , Adolescente , Adulto , Barrera Hematoencefálica/fisiopatología , Encéfalo/patología , Encéfalo/virología , Quimiocina CCL2/inmunología , Quimiocina CCL2/farmacología , Niño , Preescolar , Células Endoteliales/inmunología , Espacio Extracelular/inmunología , VIH-1/inmunología , Humanos , Lactante , Persona de Mediana Edad , Modelos Biológicos , Monocitos/virología , Fragmentos de Péptidos/inmunologíaRESUMEN
Microglia are the resident phagocytes of the brain and are an important source of proinflammatory mediators. Human immunodeficiency virus (HIV)-1 infects the central nervous system early in the course of disease, and it is believed that this occurs, in part, through the transmigration of HIV-1-infected cells across the blood-brain barrier. Infected cells release viral proteins, such as Tat and gp120. After microglia interact with these proteins, they become activated and secrete chemokines; up-regulate key surface receptors, such as CD40, and also activate resident cells. This review focuses on the consequences of microglial activation in NeuroAIDS, with an emphasis on chemokine production and CD40 up-regulation after interaction with tat or gp120. The importance of microglial CD40 in two other neurological diseases, Alzheimer's disease and multiple sclerosis, is also discussed.
Asunto(s)
Antígenos CD40/farmacología , Productos del Gen tat/farmacología , Proteína gp120 de Envoltorio del VIH/farmacología , VIH-1/química , Microglía/metabolismo , Síndrome de Inmunodeficiencia Adquirida/patología , Animales , Sistema Nervioso Central/metabolismo , Sistema Nervioso Central/virología , Quimiocinas/metabolismo , Humanos , Microglía/fisiología , Productos del Gen tat del Virus de la Inmunodeficiencia HumanaRESUMEN
Acquired immunodeficiency syndrome (AIDS)-associated dementia is often characterized by chronic inflammation, with infected macrophage infiltration of the CNS resulting in the production of human immunodeficiency virus type 1 (HIV-1) products, including tat, and neurotoxins that contribute to neuronal loss. In addition to their established role in leukocyte recruitment and activation, we identified an additional role for chemokines in the CNS. Monocyte chemoattractant protein-1 (MCP-1 or CCL2) and regulated upon activation normal T cell expressed and secreted (RANTES) were found to protect mixed cultures of human neurons and astrocytes from tat or NMDA-induced apoptosis. Neuronal and astrocytic apoptosis in these cultures was significantly inhibited by co-treatment with MCP-1 or RANTES but not IP-10. The protective effect of RANTES was blocked by antibodies to MCP-1, indicating that RANTES protection is mediated by the induction of MCP-1. The NMDA blocker, MK801, also abolished the toxic effects of both tat and NMDA. Tat or NMDA treatment of mixed cultures for 24 h resulted in increased extracellular glutamate ([Glu]e) and NMDA receptor 1 (NMDAR1) expression, potential contributors to apoptosis. Co-treatment with MCP-1 inhibited tat and NMDA-induced increases in [Glu]e and NMDAR1, and also reduced the levels and number of neurons containing intracellular tat. These data indicate that MCP-1 may play a novel role as a protective agent against the toxic effects of glutamate and tat.
Asunto(s)
Astrocitos/efectos de los fármacos , Quimiocina CCL2/farmacología , Productos del Gen tat/toxicidad , N-Metilaspartato/toxicidad , Neuronas/efectos de los fármacos , Complejo SIDA Demencia/metabolismo , Apoptosis/efectos de los fármacos , Astrocitos/citología , Astrocitos/fisiología , Células Cultivadas , Quimiocina CCL5/farmacología , Técnicas de Cocultivo , Maleato de Dizocilpina/farmacología , Antagonistas de Aminoácidos Excitadores/farmacología , Ácido Glutámico/metabolismo , Humanos , Neuronas/citología , Neuronas/fisiología , Fármacos Neuroprotectores/farmacología , Receptores de N-Metil-D-Aspartato/metabolismo , Productos del Gen tat del Virus de la Inmunodeficiencia HumanaRESUMEN
There have been increasing reports of acute coronary thrombotic events in patients with HIV. Although these clinical events have been attributed primarily to dyslipidemia associated with protease inhibitor therapy, autopsy studies in children with HIV suggest the presence of an underlying arteriopathy. This study demonstrates that the HIV envelope protein, gp120, activates human arterial smooth muscle cells to express tissue factor, the initiator of the coagulation cascade. The induction of tissue factor by gp120 is mediated by two biologically relevant coreceptors for HIV infection, CXCR4 and CCR5, and is also dependent on the presence of functional CD4. Induction of tissue factor by gp120 requires activation of mitogen-activating protein kinases, activation of protein kinase C, and generation of reactive oxygen species, signaling pathways that have protean effects on smooth muscle cell physiology. The activation of smooth muscle cells by gp120 may play an important role in the vascular, thrombotic, and inflammatory responses to HIV infection.
Asunto(s)
Proteína gp120 de Envoltorio del VIH/toxicidad , Músculo Liso Vascular/efectos de los fármacos , Antígenos CD4/metabolismo , Células Cultivadas , Quimiocina CXCL12 , Quimiocinas CXC/metabolismo , Quimiocinas CXC/farmacología , Trombosis Coronaria/etiología , Infecciones por VIH/complicaciones , Humanos , Ligandos , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Músculo Liso Vascular/fisiología , Músculo Liso Vascular/virología , Proteína Quinasa C/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Receptores CCR5/metabolismo , Receptores CXCR4/metabolismo , Proteínas Recombinantes/toxicidad , Tromboplastina/biosíntesisRESUMEN
Macrophages play a critical role in the development and progression of atherosclerosis. This study was designed to examine the effect of the glucocorticoid, dexamethasone, (Dex), on macrophage accumulation after acute arterial injury. Twenty New Zealand white rabbits were fed a 2% cholesterol, 6% peanut oil, rabbit chow diet for one month prior to bilateral balloon dilatation of the femoral arteries. Ten rabbits received Dex (1 mg/kg, im.) the day before and then daily for 7 days after arterial injury; control rabbits received vehicle only. Seven days after injury, Dex treatment resulted in a 96% and 77% reduction (P < 0.002) in the mean number of macrophages accumulating in the intima and media, respectively. This effect was apparently not due to a reduction in the number of circulating monocytes or to the ability of monocytes from Dex treated animals to adhere to endothelium or migrate in response to a chemotactic signal, determined in vitro under static conditions. It was associated with a 61% reduction in monocyte chemoattractant protein-1 (MCP-1) antigen (P < 0.004) in the injured arterial wall (media+intima). Glucocorticoids may be useful in attenuating the inflammatory response and subsequent foam-cell accumulation after arterial injury.
Asunto(s)
Antiinflamatorios/uso terapéutico , Arteriosclerosis/cirugía , Cateterismo/efectos adversos , Quimiotaxis/efectos de los fármacos , Colesterol en la Dieta/toxicidad , Dexametasona/uso terapéutico , Dieta Aterogénica , Arteria Femoral/lesiones , Oclusión de Injerto Vascular/prevención & control , Macrófagos/efectos de los fármacos , Animales , Antiinflamatorios/farmacología , Arteriosclerosis/inducido químicamente , Arteriosclerosis/patología , Adhesión Celular/efectos de los fármacos , Quimiocina CCL2/metabolismo , Dexametasona/farmacología , Evaluación Preclínica de Medicamentos , Endotelio Vascular/efectos de los fármacos , Endotelio Vascular/patología , Arteria Femoral/metabolismo , Arteria Femoral/patología , Hiperplasia , Macrófagos/patología , Masculino , Monocitos/efectos de los fármacos , Monocitos/patología , Conejos , Túnica Íntima/efectos de los fármacos , Túnica Íntima/patología , Heridas y Lesiones/tratamiento farmacológicoRESUMEN
Cryptococcus neoformans is an encapsulated fungal pathogen commonly acquired by inhalation. Extrapulmonary dissemination can lead to infection of the bloodstream and various organs, most commonly resulting in meningoencephalitis. However, infection with C. neoformans is often characterized by a scant inflammatory response. The leukocyte response to infection depends in part upon a gradient of chemotactic factors and adhesion molecules expressed by the host vascular endothelium, yet the inflammatory response of human endothelial cells (EC) to C. neoformans has not been previously investigated. We found that incubation of primary human EC with C. neoformans did not induce chemokine synthesis, and resulted in differential inhibition of cytokine-induced IL-8, IFN-gamma-inducible protein-10, and monocyte chemoattractant protein-1. In contrast, C. neoformans had little effect on EC surface expression of the leukocyte ligand, ICAM-1, as determined by flow cytometry. Modulation of chemokine production was dependent on the chemokine under study, the inoculum of C. neoformans used, fungal viability, and cell-cell contact, but independent of cryptococcal strain or encapsulation. These observations suggest a novel mechanism whereby C. neoformans can affect EC function and interfere with the host inflammatory response.
Asunto(s)
Quimiocinas/antagonistas & inhibidores , Quimiocinas/biosíntesis , Cryptococcus neoformans/inmunología , Endotelio Vascular/inmunología , Endotelio Vascular/microbiología , Tolerancia Inmunológica/inmunología , Transporte Biológico/inmunología , Comunicación Celular/inmunología , Núcleo Celular/metabolismo , Células Cultivadas , Cryptococcus neoformans/crecimiento & desarrollo , Cryptococcus neoformans/patogenicidad , Cryptococcus neoformans/fisiología , Citocinas/antagonistas & inhibidores , Citocinas/farmacología , Relación Dosis-Respuesta Inmunológica , Endotelio Vascular/citología , Endotelio Vascular/metabolismo , Humanos , Molécula 1 de Adhesión Intercelular/biosíntesis , FN-kappa B/metabolismo , Infecciones Oportunistas/inmunología , Infecciones Oportunistas/microbiología , Especificidad de la Especie , Esporas Fúngicas/inmunología , Esporas Fúngicas/fisiologíaRESUMEN
Staphylococcal strain 8325-4, unlike other staphylococcal strains, fails to induce cytokine IL-1 and IL-6 gene expression in human endothelial cells. In the present investigation, this strain was shown to release a product that inhibited cytokine gene expression in endothelial cells infected with another staphylococcal strain. This inhibition was due to prevention of internalization, but not adherence, of bacteria by endothelial cells. Induction of endothelial cell cytokine gene expression by lipopolysaccharide was not affected by the staphylococcal supernatant. In contrast to endothelial cells, 8325-4 did not inhibit Wb-induced cytokine gene expression in monocytes. Further characterization of the inhibitory factor suggests that it is a lipoprotein and that both protein and lipid components play a role in its inhibitory function.
Asunto(s)
Endotelio Vascular/inmunología , Interleucina-1/genética , Interleucina-6/genética , Lipoproteínas/fisiología , Staphylococcus aureus/fisiología , Animales , Adhesión Bacteriana , Línea Celular , Células Cultivadas , Medios de Cultivo , Endotelio Vascular/citología , Endotelio Vascular/microbiología , Regulación de la Expresión Génica , Humanos , Interleucina-1/biosíntesis , Interleucina-1/metabolismo , Interleucina-6/biosíntesis , Interleucina-6/metabolismo , Ratones , Monocitos/inmunología , Monocitos/microbiología , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/inmunología , Staphylococcus aureus/metabolismo , Venas UmbilicalesRESUMEN
Immune/inflammatory responses of arterial vessel wall constituents to lipid metabolic disturbances have been postulated to contribute to the pathogenesis of atherosclerosis. Mycophenolate mofetil (MMF), an antiproliferative agent used in clinical transplantation, has been shown to inhibit smooth muscle cell (SMC) proliferation and decrease the recruitment of monocytes into sites of chronic inflammation. This study was conducted to determine the effect of MMF on atherosclerotic plaque development after cholesterol-induced injury. New Zealand white rabbits were fed a high-cholesterol diet containing 0.5% cholesterol and 8% peanut oil. The experimental group (n = 10) was given MMF (80 mg/kg/day subcutaneously); the control group (n = 10) received placebo injections. The aortas were harvested at 12 weeks for immunohistochemical analyses. SMCs were identified by reactivity with a monoclonal antibody (mAb) to alpha smooth muscle actin. Monocytes/macrophages were detected with mAb RAM 11. Cross-sectional areas of the media and neointima were measured using computer-assisted image analysis. The density of SMCs and macrophage/foam cells within the neointima was calculated by dividing the number of cells by the area of the plaque. Total cholesterol, triglyceride, high density lipoprotein, and low density lipoprotein were significantly increased compared with levels before the initiation of a high-cholesterol diet, but there were no significant differences between the MMF-treated and untreated groups. Neointimal area in aortic tissue sections of the MMF-treated group (0.586 +/- 0.602 mm(2)) was significantly lower when compared with that in control animals (1.082 +/- 0.621 mm(2)) (P < 0.05). The densities of neointimal SMCs and monocytes/macrophages in the control group were 778 +/- 293 and 341 +/- 90 cells/mm(2), respectively. MMF treatment significantly reduced the number of neointimal SMCs (506 +/- 185 cells/mm(2)) (P < 0.05). The number of monocytes/macrophages was also reduced after MMF treatment (260 +/- 124 cells/mm(2)) but not significantly. Our results demonstrate that the administration of MMF significantly reduced neointimal SMC accumulation and plaque development in a hypercholesterolemic model of atherosclerosis.
Asunto(s)
Arteriosclerosis/inducido químicamente , Arteriosclerosis/patología , Colesterol en la Dieta , Ácido Micofenólico/análogos & derivados , Animales , Aorta/efectos de los fármacos , Aorta/patología , Macrófagos/patología , Masculino , Monocitos/patología , Músculo Liso Vascular/efectos de los fármacos , Músculo Liso Vascular/patología , Ácido Micofenólico/farmacología , Conejos , Túnica Íntima/efectos de los fármacos , Túnica Íntima/patologíaRESUMEN
HIV-1 encephalitis occurs in up to one-third of HIV-1-infected individuals. The mechanisms through which this pathology develops are thought to involve viral passage across the blood-brain barrier (BBB), as well as entry of HIV-infected and/or uninfected inflammatory cells into the central nervous system (CNS). Viral proteins and cytokines may also contribute to the pathogenesis of encephalitis. We show that the chemokines SDF-1 and MCP-1 induce transmigration of uninfected human lymphocytes and monocytes across our model of the BBB, a co-culture of human fetal astrocytes and endothelial cells. We also demonstrate that the HIV-1 protein Tat induces adhesion molecule expression and chemokine production by human fetal astrocytes and microglia, which could further contribute to leukocyte entry into the CNS. Finally, our data indicate that inflammatory cytokines modulate the expression of CXCR4, a co-receptor for HIV-1, on human fetal astrocytes, suggesting that these cytokines may potentially modulate the infectability of astrocytes by HIV-1. These findings support the hypothesis that there may be several different mechanisms that contribute to the development and progression of HIV-1 encephalitis.
Asunto(s)
Barrera Hematoencefálica , Encéfalo/virología , Quimiotaxis de Leucocito , VIH-1/metabolismo , Linfocitos/metabolismo , Monocitos/metabolismo , Adulto , Astrocitos/metabolismo , Encéfalo/patología , Células Cultivadas , Quimiocina CCL2/metabolismo , Quimiocina CXCL12 , Quimiocinas CXC/metabolismo , Técnicas de Cocultivo , Endotelio Vascular/citología , Feto , Productos del Gen tat/metabolismo , VIH-1/patogenicidad , Humanos , Molécula 1 de Adhesión Intercelular/metabolismo , Receptores CXCR4/metabolismo , Molécula 1 de Adhesión Celular Vascular/metabolismo , Productos del Gen tat del Virus de la Inmunodeficiencia HumanaRESUMEN
The expression of monocyte-specific adhesion molecules and chemokines by cell types within the vessel wall plays an important role in foam cell accumulation during atherosclerotic plaque development. We previously identified IG9, a novel monocyte adhesion protein that is expressed on endothelial cells (ECs) overlying human and rabbit advanced atherosclerotic plaques. The present study was designed to determine the temporal and spatial expression of IG9 and the chemokine, monocyte chemoattractant protein-1 (MCP-1), after balloon injury with (double injury) or without (single injury) prior air desiccation EC injury in the femoral arteries of rabbits fed a high-cholesterol diet. By immunohistochemical analyses, intense reactivity with monoclonal antibodies to IG9 and MCP-1 was detected 24 hours after single injury in medial smooth muscle cells (SMCs) and in SMCs of adventitial microvessels. However, monocyte infiltration of the tunica media was minimal or not detected in these sections. IG9 and MCP-1 antibody reactivity in vessel sections 28 days after single injury and 24 hours, 7 days, and 28 days after double injury was localized to medial and neointimal SMCs, foam cells, and luminal ECs overlying the plaques. Uninjured rabbit (cholesterol or normal diet) vessel sections exhibited minimal IG9 and MCP-1 immunostaining. In vitro studies using human aortic SMCs demonstrated IG9 protein induction after 24 hours of treatment with platelet-derived growth factor-BB and interferon-gamma or epidermal growth factor. IG9 expression was further increased by pretreatment of SMCs with the proatherogenic lipid, minimally oxidized low density lipoprotein. After balloon injury (24 hours), IG9 is induced in vascular SMCs before the detectable accumulation of monocytes within the vessel wall. Thus, the expression of IG9 by SMCs as well as by ECs may be an important factor in the accumulation of foam cells in atherosclerotic plaque development after arterial injury.
Asunto(s)
Traumatismos de las Arterias Carótidas/metabolismo , Moléculas de Adhesión Celular/genética , Colesterol en la Dieta/administración & dosificación , Endotelio Vascular/metabolismo , Regulación de la Expresión Génica , Músculo Liso Vascular/metabolismo , Animales , Aorta , Traumatismos de las Arterias Carótidas/etiología , Cateterismo , Adhesión Celular , Células Cultivadas , Quimiocina CCL2/genética , Citocinas/farmacología , Regulación de la Expresión Génica/efectos de los fármacos , Sustancias de Crecimiento/farmacología , Humanos , Lipoproteínas LDL/farmacología , Monocitos , ConejosRESUMEN
Human immunodeficiency virus (HIV) encephalitis is a prominent pathology seen in children infected with HIV. Immunohistochemical analyses of pediatric brain tissue showed distinct differences in expression of C-C chemokines and their receptors between children with HIV encephalitis and those with non-CNS-related pathologies. Evidence suggests that soluble factors such as HIV Tat released from HIV-infected cells may have pathogenic effects. Our results show Tat effects on chemokines and their receptors in microglia and astrocytes as well as chemokine autoregulation in these cells. These results provide evidence for the complex interplay of Tat, chemokines, and chemokine receptors in the inflammatory processes of HIV encephalitis and illustrate an important new role for chemokines as autocrine regulators.
Asunto(s)
Quimiocinas/metabolismo , Neuroglía/metabolismo , Receptores de Quimiocina/metabolismo , Adolescente , Astrocitos/efectos de los fármacos , Encéfalo/citología , Encéfalo/embriología , Células Cultivadas , Quimiocina CCL2/metabolismo , Quimiocina CCL4 , Niño , Preescolar , Femenino , Regulación de la Expresión Génica/fisiología , Productos del Gen tat/farmacología , Homeostasis , Humanos , Inmunohistoquímica , Lactante , Proteínas Inflamatorias de Macrófagos/metabolismo , Masculino , Microglía/efectos de los fármacos , Isoformas de Proteínas/metabolismo , Receptores CCR2 , Receptores CCR5/metabolismo , Receptores CXCR4/metabolismoRESUMEN
In this study, the temporal and spatial expression of the chemotactic factor monocyte chemotactic protein-1 (MCP-1) was examined in the rabbit retina after challenge with the proinflammatory cytokine interleukin-1beta (IL-1). In these tissues, IL-1 induces an acute inflammatory response of the epiretinal vessels that peaks approximately 24 h postintraocular injection (pi) with the cytokine. At 2 h after challenge with IL-1, MCP-1 mRNA was expressed by perivascular microglial cells and astrocytes that form the glial limitans. Protein analysis at 3 h pi with IL-1 confirmed these sites of MCP-1 expression. The intensity of the mRNA and protein signals increased at 6 h and at 24 h. At these time points, MCP-1 message and protein also were detected in infiltrating macrophages and, at the latest time point, in endothelial cells as well. These data support the conclusion that IL-1 provides a strong stimulus for the rapid expression of MCP-1 mRNA and protein in retinal tissues, and they further support the role of endogenous glial cells as important sources of mediators involved in the regulation of inflammation occurring within the nervous system.
Asunto(s)
Quimiocina CCL2/metabolismo , Interleucina-1/metabolismo , Retina/metabolismo , Animales , Quimiocina CCL2/genética , Femenino , Inmunohistoquímica , Hibridación in Situ , ARN Mensajero/análisis , Conejos , Factores de TiempoRESUMEN
CC chemokine receptors are important modulators of inflammation. Although CC chemokine receptors have been found predominantly on leukocytes, recent studies have suggested that vascular smooth muscle cells respond to CC chemokines. We now report that human smooth muscle cells express CCR5, a co-receptor for human immunodeficiency virus. CCR5 mRNA was detectable by RNA blot hybridization in human aortic and coronary artery smooth muscle cells. The cDNA generated by reverse transcription-polymerase chain reaction from aortic smooth muscle cells had 100% identity throughout the entire coding region with the CCR5 cloned from THP-1 cells. By immunohistochemistry, CCR5 and the CCR5 ligand, macrophage inflammatory protein-1beta (MIP-1beta), were detected in smooth muscle cells and macrophages of the atherosclerotic plaque. In smooth muscle cell culture, MIP-1beta induced a significant increase in intracellular calcium concentrations, which was blocked by an antibody to CCR5. In addition, MIP-1beta caused a calcium-dependent increase in tissue factor activity. Tissue factor is the initiator of coagulation and is thought to play a key role in arterial thrombosis. These data suggest that human arterial smooth muscle cells express functional CCR5 receptors and MIP-1beta is an agonist for these cells.
Asunto(s)
Músculo Liso Vascular/metabolismo , Receptores CCR5/metabolismo , Aorta/metabolismo , Arteriosclerosis/metabolismo , Calcio/metabolismo , Quelantes/farmacología , Quimiocina CCL4 , Vasos Coronarios/metabolismo , Relación Dosis-Respuesta a Droga , Ácido Egtácico/análogos & derivados , Ácido Egtácico/farmacología , Endotelio Vascular/metabolismo , Humanos , Inmunohistoquímica , Inflamación/metabolismo , Proteínas Inflamatorias de Macrófagos/metabolismo , ARN Mensajero/metabolismo , Receptores CCR5/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Tromboplastina/metabolismo , Trombosis/metabolismo , Factores de Tiempo , Cordón Umbilical/metabolismoRESUMEN
Chemokines are secreted proteins that function as chemoattractants, mediating the recruitment of specific subsets of leukocytes to sites of tissue damage and immunological reactions. Chemokines may also function as antiviral agents, since viruses such as human immunodeficiency virus type 1 (HIV-1) use chemokine receptors as co-receptors for viral entry. This study examines whether virus-induced interferon, IFNbeta, or immune-related interferon, IFNgamma, affects the production of beta-chemokines by CNS microglia and peripheral monocytes. When IFNbeta was used as the stimulus, induction of MIP-1alpha, MIP-1beta, MCP-1, and RANTES mRNA and protein was observed within 12 h of stimulation in microglia. By contrast, when IFNgamma was used as the stimulus, only MCP-1 was induced. IFNbeta stimulation of blood monocytes resulted in upregulation of MIP-1alpha, MIP-1beta, and MCP-1. Thus, type I and II interferons differentially regulate beta-chemokines in human fetal microglia and peripheral blood monocytes. These observations may have relevance for the therapeutic activity of IFNbeta in multiple sclerosis and for the antiviral effects of IFNbeta for HIV-1 infection of monocytes and microglia.
Asunto(s)
Quimiocinas/metabolismo , Interferón Tipo I/farmacología , Interferón gamma/farmacología , Microglía/efectos de los fármacos , Microglía/metabolismo , Células Cultivadas , Quimiocina CCL2/metabolismo , Quimiocina CCL3 , Quimiocina CCL4 , Quimiocina CCL5/metabolismo , Feto , Humanos , Proteínas Inflamatorias de Macrófagos/metabolismo , Monocitos/metabolismoRESUMEN
AIDS encephalitis is a frequent consequence of CNS HIV infection, especially in children. One of its many characteristics is a leukocyte infiltrate that is believed to contribute to the production of cytokines, chemokines and neurotoxic factors resulting in CNS damage. Entry of such leukocytes into the CNS is mediated in part by the expression of adhesion molecules by blood - brain barrier (BBB) endothelial cells. Expression of these proteins by astrocytes, the other main component of the BBB, also serves to target leukocytes to the CNS parenchyma. We now demonstrate that HIV-1-derived Tat, a soluble protein secreted by infected cells, induced astrocyte VCAM-1 and ICAM-1 expression in a dose- and time-dependent manner. The functional role of Tat in monocyte binding in vitro was also demonstrated. These data suggest that the presence of extracellular Tat may be a significant factor in the trafficking of HIV-infected and inflammatory cells into the CNS via its effect on adhesion molecule expression by astrocytes.