Human Immunodeficiency Virus In Macrophages Research Articles

Nano-NRTIs demonstrate low neurotoxicity and high antiviral activity against HIV infection in the brain

Antiviral therapy using nucleoside reverse transcriptase inhibitors (NRTIs) is neurotoxic and has low efficiency in eradication of HIV-1 harbored in central nervous system (CNS). Previously, we reported that active 5′-triphosphates of NRTIs encapsulated in cationic nanogels (nano-NRTIs) suppress HIV-1 activity more efficiently than NRTIs and exhibit reduced mitochondrial toxicity [Vinogradov SV, Poluektova LY, Makarov E, Gerson T, Senanayake MT. Nano-NRTIs: efficient inhibitors of HIV type-1 in macrophages with a reduced mitochondrial toxicity. Antivir Chem Chemother. 2010; 21:1-14. Makarov E, Gerson T, Senanayake T, Poluektova LY, Vinogradov. Efficient suppression of Human Immunodeficiency Virus in Macrophages by Nano-NRTIs. Antiviral Res. 2010; 86(1):A38-9]. Here, we demonstrated low neurotoxicity and excellent antiviral activity of nano-NRTIs decorated with the peptide (AP) binding brain-specific apolipoprotein E receptor. Nano-NRTIs induced lower levels of apoptosis and formation of reactive oxygen species, a major cause of neuron death, than free NRTIs. Optimization of size, surface decoration with AP significantly increased brain accumulation of nano-NRTIs. The efficient CNS delivery of nano-NRTIs resulted in up to 10-fold suppression of retroviral activity and reduced virus-associated inflammation in humanized mouse model of HIV-1 infection in the brain. Our data provide proof of the advanced efficacy of nano-NRTIs as safer alternative of current antiviral drugs. From the Clinical EditorThis team of investigators demonstrated low neurotoxicity and excellent anti-HIV activity of nano-nucleoside reverse transcriptase inhibitors decorated with the peptide (AP) binding brain-specific apolipoprotein E receptor, providing proof of enhanced efficacy and a safer alternative compared with current antiviral drugs.

Efficient Suppression of Human Immunodeficiency Virus in Macrophages by Nano-NRTIs

Efficient Suppression of Human Immunodeficiency Virus in Macrophages by Nano-NRTIs

Thymidine and 3‘-azido-3‘-deoxythymidine metabolism in human peripheral blood lymphocytes and monocyte-derived macrophages. A study of both anabolic and catabolic pathways.

3'-Azido-3'-deoxythymidine (AZT) is HIV-inhibitory in human macrophages, which is surprising in view of the low AZT phosphorylation reported in macrophage extracts. To elucidate the mechanism of AZT activation, we studied AZT anabolism as well as catabolism in human lymphocytes and macrophages, and compared it to that of thymidine. Thymidine kinase (TK)-specific activity in mitogen-stimulated lymphocytes was 15 times higher than in macrophages. However, the TK activity per cell was only 1.3 times higher, because of the large macrophage cell volume. Total cellular TK activity, but not specific activity, matched the level of intracellular AZT anabolism. The substrate specificity of TK in macrophages strongly suggests that mitochondrial TK2 was the enzyme phosphorylating thymidine and AZT in these cells, whereas it was cytosolic TK1 in stimulated lymphocytes. In vivo thymidine catabolism was extensive, forming thymine and dihydrothymine. In macrophages more than 95% of the added thymidine (0.5 microM) was degraded within 60 min. AZT, in contrast, was not catabolized, which explains the high AZT nucleotide accumulation, a process opposed only by AZTMP excretion. The lack of catabolism together with phosphorylation by TK2 clarifies how AZT can inhibit human immunodeficiency virus in macrophages. The fact that TK2 and not TK1 phosphorylates AZT in macrophages should have important implications for combination chemotherapy.

T-cell-induced expression of human immunodeficiency virus in macrophages

Macrophages are major reservoirs of human immunodeficiency virus (HIV) in the tissues of infected humans. As monocytes in the peripheral blood do not show high levels of infection, we have investigated the expression of HIV in T-cell-activated, differentiated macrophages. Peripheral blood mononuclear cells were isolated from HIV-seropositive individuals and stimulated with antigens or mitogens, and the nonadherent fraction was removed. Macrophages were cultured alone for 2 weeks, and HIV expression was assessed. Results from p24 antigen capture assays demonstrated that the presence of autologous T cells and concanavalin A or autologous T cells and allogeneic cells for the initial 24 h of culture induced HIV expression in 35 of 47 (74%) HIV-seropositive patients tested. The macrophage monolayers could be immunostained with anti-HIV antibodies to reveal discrete infectious centers, indicating that complete virus replication was occurring in the macrophages and that infection of adjacent cells was mediated by cell-cell contact. Time course studies of the interval of coculture of the adherent and nonadherent cells indicated that 24 h (but not 2 h) was sufficient for induction of HIV in the macrophages. Direct contact between the adherent cells and activated T cells was required as well. Since the presence of autologous T cells also appeared to be necessary, induction of HIV expression in macrophages may be genetically restricted. HIV-seronegative nonadherent cells were able to induce HIV expression in macrophages from HIV-seropositive donors, demonstrating that the virus originated in the monocytes and was reactivated in the context of a classic T-cell-mediated immune reaction. The high percentage of monocytes from HIV-seropositive donors which can be induced to replicate HIV by activated T cells suggests that infection of monocytes may be critical to the pathogenesis of this lentivirus infection.