RESUMEN
Coreceptor utilization by HIV-1 is an important determinant of pathogenesis. However, coreceptor selectivity is defined in vitro, while in vivo critical pathogenic events occur in lymphoid tissues. Using pharmacological inhibitors, we recently provided evidence that coreceptor selectivity by the R5X4 dual-tropic isolate 89.6 was more restricted in ex vivo infected lymphoid tissue than in vitro [S. Glushakova, Y. Yi, J. C. Grivel, A. Singh, D. Schols, E. De Clercq, R. G. Collman, and L. Margolis (1999). J. Clin. Invest. 104, R7-R11]. Here we extend those observations using CCR5-deficient (CCR5Delta32) lymphoid tissue as well as additional primary isolates. We definitively show that neither CCR5 nor secondary coreceptors used in vitro mediate 89.6 infection in lymphoid tissue. We also demonstrate that restricted coreceptor use in lymphoid tissue ex vivo compared with in vitro utilization occurs with other dual-tropic primary isolates and is not unique to 89.6. For all strains tested that are dual tropic in vitro, severe CD4 T cell depletion in lymphoid tissue correlated with preferential CXCR4 use in this ex vivo system.
Asunto(s)
VIH-1/patogenicidad , Tejido Linfoide/virología , Receptores CCR5/deficiencia , Recuento de Linfocito CD4 , Efecto Citopatogénico Viral , Genotipo , Infecciones por VIH/inmunología , VIH-1/genética , Humanos , Técnicas In Vitro , Tejido Linfoide/inmunología , Tejido Linfoide/patología , Fenotipo , Receptores CCR5/genética , Receptores CXCR4/genética , Receptores CXCR4/metabolismo , Linfocitos T/patología , Linfocitos T/virologíaRESUMEN
Progression of human immunodeficiency virus (HIV) disease is associated with massive death of CD4(+) T cells along with death and/or dysfunction of CD8(+) T cells. In vivo, both HIV infection per se and host factors may contribute to the death and/or dysfunction of CD4(+) and CD8(+) T cells. Progression of HIV disease is often characterized by a switch from R5 to X4 HIV type 1 (HIV-1) variants. In human lymphoid tissues ex vivo, it was shown that HIV infection is sufficient for CD4(+) T-cell depletion. Here we address the question of whether infection of human lymphoid tissue ex vivo with prototypic R5 or X4 HIV variants also depletes or impairs CD8(+) T cells. We report that whereas productive infection of lymphoid tissue ex vivo with R5 and X4 HIV-1 isolates induced apoptosis in CD4(+) T cells, neither viral isolate induced apoptosis in CD8(+) T cells. Moreover, in both infected and control tissues we found similar numbers of CD8(+) T cells and similar production of cytokines by these cells in response to phorbol myristate acetate or anti-CD3-anti-CD28 stimulation. Thus, whereas HIV-1 infection per se in human lymphoid tissue is sufficient to trigger apoptosis in CD4(+) T cells, the death of CD8(+) T cells apparently requires additional factors.
Asunto(s)
Apoptosis , Linfocitos T CD4-Positivos/virología , Linfocitos T CD8-positivos/virología , VIH-1/metabolismo , Tejido Linfoide/virología , Anticuerpos Monoclonales , Linfocitos T CD4-Positivos/fisiología , Linfocitos T CD8-positivos/fisiología , Citometría de Flujo , VIH-1/inmunología , Humanos , Técnicas In Vitro , Interferón gamma/análisis , Interleucina-2/análisis , Tejido Linfoide/citología , Tonsila Palatina/citología , Tonsila Palatina/virología , Factor de Necrosis Tumoral alfa/análisisRESUMEN
The effect of thyroxine on Ca2+-dependent mitochondrial permeability transition has been examined. It is shown that 40 microM thyroxine induces high amplitude swelling and decrease in membrane potential in Ca2+-loaded rat liver mitochondria, both in the presence and absence of cyclosporin A. Thyroxine-induced decrease in membrane potential is partially or completely reversed by addition of EGTA into the incubation medium. Nigericin and ADP are shown to prevent, or significantly delay, the effects of thyroxine on both mitochondrial swelling and membrane potential, whereas nicotinamide potentiates the permeabilisation of mitochondria. It is suggested that thyroxine induced reversible, cyclosporin A-insensitive permeability transition pore (PTP) opening in the inner mitochondrial membrane.