ABSTRACT
Two major interferon (IFN)-mediated antiviral defense enzymes are double-stranded (ds)RNA-dependent 2',5'-oligoadenylate (2-5A) synthetase (2-5OAS) and p68 kinase (PKR). When activated by dsRNA, 2-5OAS synthesizes 2-5A, which binds to and activates RNase L. Activated RNase L hydrolyzes single-stranded viral RNA, thereby inhibiting viral protein synthesis. HIV-1 inhibits the IFN-mediated intracellular antiviral pathways. We have reported the synthesis and characterization of a nuclease-resistant 2-5A agonist (2-5A(N6B)) that overcomes the HIV-1 induced blockades by restoring the 2-5OAS/RNase L antiviral pathway (Homan JW, et al., J Acquir Immune Defic Syndr 2002;30:9-20). The objective of this study was to test the effect of 2-5A(N6B) on chronically infected CD4(+) T lymphocytes and CD14(+) monocytes derived from HIV-1-seropositive individuals. Wild-type HIV-1 replication was effectively inhibited by 2-5A(N6B) in CD4(+) T lymphocytes and CD14(+) monocytes purified from HIV-1 seropositive individuals (n = 18) compared to untreated cells. We also assessed the cytotoxicity of 2-5A(N6B) and report that 2-5A(N6B) exerts its anti-HIV-1 activity with no evidence of cytotoxicity (IC(90) > 100,000 nM). Furthermore, 2-5A(N6B) did not alter the cellular RNA profile, affect CCR5 or CXCR4 coreceptor expression, or activate caspase-dependent apoptosis. Evidence is also provided to show that 2-5A(N6B), and naturally occurring 2-5A(4), act as ligands to activate human Toll-like receptor 4. These results indicate that the 2-5A agonist 2-5A(N6B) has the potential to enhance host cell innate and acquired immune defense mechanisms against HIV-1 infection.
Subject(s)
Adenine Nucleotides/pharmacology , Anti-HIV Agents/pharmacology , CD4-Positive T-Lymphocytes/virology , HIV Infections/metabolism , HIV-1/drug effects , Lipopolysaccharide Receptors , Oligoribonucleotides/pharmacology , Adenine Nucleotides/agonists , Adenine Nucleotides/chemical synthesis , Adult , Aged , CD4 Lymphocyte Count , CD4-Positive T-Lymphocytes/drug effects , Cells, Cultured , Dose-Response Relationship, Drug , Female , Flow Cytometry , HIV Infections/drug therapy , HIV Seropositivity , HIV-1/physiology , Humans , Immunologic Factors/pharmacology , Male , Middle Aged , Monocytes/cytology , Monocytes/immunology , Oligoribonucleotides/agonists , Oligoribonucleotides/chemical synthesis , Reverse Transcriptase Polymerase Chain Reaction , Toll-Like Receptor 4/metabolism , Virus Replication/drug effectsABSTRACT
Opioids potentiate HIV-1 infection in vitro at least partly by suppressing immunoresponsive processes in human lymphocytes and monocytes. For example, it appears that morphine inhibits the interferon (IFN)-alpha, -beta, and -gamma-mediated natural antiviral defense pathways in human peripheral blood mononuclear cells (PBMC). In this study, we show that restoration of a key component of the antiviral pathway reverses morphine-potentiated HIV-1 infection of human PBMC. The data show that HIV-1 replication is potentiated and RNase L activity is inhibited after morphine administration. Because HIV-1 inhibits the antiviral pathway at the level of 2',5'-oligoadenylate (2-5A) synthetase and p68 kinase, antiviral enzymes that require double-stranded RNA, we overcame this blockade by the addition of the nuclease-resistant, nontoxic 2-5A agonist, 2-5A(N6B), to PBMC in culture. Addition of 2-5A(N6B), but not zidovudine or saquinavir, to morphine-treated PBMC completely reversed the morphine-induced potentiation of HIV-1 infection. Further, 2-5A(N6B) significantly enhanced expression of both IFN-alpha and IFN-gamma. Also, increased expression of IFN-gamma was associated with a significant increase in expression of RANTES and monocyte chemotactic protein (MCP)-1, chemokines that may inhibit HIV-1 infection by blocking viral attachment to CCR2 and CCR5 co-receptors. Our results suggest that reactivation of the antiviral pathway by 2-5A agonists may be useful to inhibit opioid-potentiated HIV-1 replication.