RESUMEN
Tat protein, an HIV gene product known to be secreted extracellularly, was tested to determine its role in the dissemination of HIV into the central nervous system (CNS). Tat was shown to activate human CNS-derived endothelial cells (CNS-EC) by the increase in the expression of E-selectin, the synthesis of IL-6, and the secretion of plasminogen activator inhibitor-1 (PAI-1). Tat also functioned synergistically with tumor necrosis factor alpha (TNF). AIDS brains stained for tat in situ, demonstrated positive cells. These data suggest that secreted tat protein may increase leukocyte binding, and alter the blood-brain barrier permeability to enhance dissemination of HIV-infected cells into the CNS.
Asunto(s)
Sistema Nervioso Central/efectos de los fármacos , Productos del Gen tat/farmacología , Síndrome de Inmunodeficiencia Adquirida/metabolismo , Encéfalo/metabolismo , Adhesión Celular , Moléculas de Adhesión Celular/metabolismo , Células Cultivadas , Sistema Nervioso Central/citología , Sistema Nervioso Central/metabolismo , Sinergismo Farmacológico , Selectina E , Células Epiteliales , Epitelio/efectos de los fármacos , Humanos , Interleucina-6/biosíntesis , Inhibidor 1 de Activador Plasminogénico/biosíntesis , Factor de Necrosis Tumoral alfa/farmacología , Productos del Gen tat del Virus de la Inmunodeficiencia HumanaRESUMEN
A permeabilization method which allows the assay of intracellular enzymes of the Ehrlich ascites cells is described. The developmental changes in the activity of lactic dehydrogenase and glucose-6-phosphate dehydrogenase of toluene-treated Ehrlich ascites cells were studied.
Asunto(s)
Carcinoma de Ehrlich/enzimología , Células Cultivadas/efectos de los fármacos , Tolueno/farmacología , Animales , Permeabilidad de la Membrana Celular/efectos de los fármacos , Células Cultivadas/enzimología , Glucosafosfato Deshidrogenasa/metabolismo , L-Lactato Deshidrogenasa/metabolismo , RatonesRESUMEN
tat protein, a human immunodeficiency virus (HIV) gene product that functions as a transactivator for HIV replication, is known to be secreted extracellularly by infected cells. To determine the potential role of tat in the dissemination of HIV into extravascular tissue, this protein was examined for its ability to activate human endothelial cells. The results show that tat does indeed stimulate endothelial cells. This is evidenced by their expression of the endothelial-leukocyte adhesion molecules, E-selectin, critical for the initial binding of leukocytes to the blood vessel wall, and their increased synthesis of interleukin-6 (IL-6), a cytokine known to enhance endothelial cell permeability. Furthermore, tat acts synergistically with low concentrations of tumor necrosis factor-alpha to enhance IL-6 secretion. These data suggest that extracellular tat protein secreted or released into the microenvironment may contribute significantly to the determination of specific sites of leukocyte binding to blood vessels, to transmigration into tissue, and to eventual dissemination of HIV-infected cells or free virions into tissue.