Biomedical subjects
Publications and source records attributed to Julianna Lisziewicz.
Structured treatment interruption (STI) has been investigated for three distinct clinical scenarios: during acute infection with the goal of immune reconstitution and auto immunization; during chronic infection, to decrease the amount and toxicity of antiretroviral drugs; and during virologic failure to restore response to subsequent antiretroviral therapy. The potential costs and benefits of STI should be determined.
Highly active antiretroviral therapy (HAART) allows for substantial control of HIV replication in vivo, and has caused a significant decline in morbidity and mortality rates among patients. However, eradication of the virus from the body is not possible. Therefore, HAART necessarily becomes a life-long treatment and this is associated with several problems: (i) the high cost of therapy; (ii) increased frequency of drug-related side effects; (iii) viral resistance; and (iv) poor patient adherence to the treatment. Based on these considerations, among other alternative strategies, structured treatment interruptions (STI) have been proposed with the potential object-ive of inducing immune-mediated control of HIV replication in HIV-infected patients. The available clinical data indicate that STI might increase HIV-specific, cell-mediated immune responses in patients treated during primary HIV infection; however, it does not seem to have the same effect in patients treated during chronic infection. Nevertheless, in chronically infected patients STI might limit drug-related side effects by decreasing exposure to drugs, without influencing the efficacy of the therapy. In addition, recent data suggest a possible role for immune-modulations such as hydroxyurea and therapeutic vaccines as adjuvant therapies for limiting viral rebound in these patients. Preliminary indications suggest that there is reduced hope for STI as a salvage therapy. Finally, it is important to stress that no controlled, randomized studies of STI have been held in humans, and it is not possible to evaluate fully the clinical impact of such a strategy. Therefore, clinicians and patients should avoid using STI outside the setting of controlled clinical trials.
Dendritic cells are susceptible to human immunodeficiency virus (HIV) infection and may transmit the virus to T cells in vivo. Scarce information is available about drug efficacy in dendritic cells because preclinical testing of antiretroviral drugs has been limited predominantly to T cells and macrophages. We compared the antiviral activities of hydroxyurea and two protease inhibitors (indinavir and ritonavir) in monocyte-derived dendritic cells and in lymphocytes. At therapeutic concentrations (50 to 100 microM), hydroxyurea inhibited supernatant virus production from monocyte-derived dendritic cells in vitro but the drug was ineffective in activated lymphocytes. Concentrations of hydroxyurea insufficient to be effective in activated lymphocytes cultured alone strongly inhibited supernatant virus production from cocultures of uninfected, activated lymphocytes with previously infected monocyte-derived dendritic cells in vitro. In contrast, protease inhibitors were up to 30-fold less efficient in dendritic cells than in activated lymphocytes. Our data support the rationale for testing of the combination of hydroxyurea and protease inhibitors, since these drugs may have complementary antiviral efficacies in different cell compartments. A new criterion for combining drugs for the treatment of HIV infection could be to include at least one drug that selectively targets HIV in viral reservoirs.
The HIV pandemic represents a new challenge to biomedical research. What began as a handful of recognized cases among homosexual men in the US has become a global pandemic of such proportions that it clearly ranks as one of the most destructive viral scourges in history. In the past few years new treatments and drugs have been developed and tested, but the development of a new generation of therapies remains a major priority, because of the lack of chemotherapeutic drugs or vaccines that show long-term efficacy in vivo. Recently, gene therapeutic strategies for the treatment of patients with HIV infection have received increased attention because they are able to offer the possibility of simultaneously targeting multiple sites in the HIV genome, thereby minimizing the production of resistant virus. Recombinant genes for gene therapy can be classified as expressing interfering proteins (intracellular antibodies, dominant negative proteins) or interfering RNAs (antisense RNAs, ribozymes, RNA decoys). The latter group offers the advantage of avoiding the stimulation of host immune response which might progressively decrease the efficacy of proteins. The stumbling block to achieving lasting antiviral effects is still represented by the lack of efficient gene transfer techniques capable of generating persistent transgene expression and a high number of transduced cells relative to untransduced cells. Novel delivery vectors, such as lentiviruses, might overcome some of these shortcomings. The use of recombinant genes to generate immunity is a very promising concept that is rapidly expanding. Since the immune system can significantly amplify the response to tiny amounts of antigen, DNA vaccines can indeed be delivered by exploiting traditional gene therapy approaches without the need of high transduction efficiency.
BACKGROUND: Gene therapy has recently been advanced by the development of HIV-based vectors that are able to transduce some non-dividing cells. The manipulation of most non-dividing cells remains, however, scarcely efficient. One of the biological mechanisms postulated to prevent powerful transduction of quiescent cells by lentiviral vectors is the paucity of deoxynucleotides (dNTPs). In this study, a novel delivery strategy is developed to improve significantly the efficiency of HIV-based vectors in transducing non-dividing cells. This approach is based on increasing the intracellular availability of dNTPs by incubating target cells with the dNTP precursors, deoxynucleosides (dNSs). METHODS: Mature human monocyte-derived macrophages (14-21 days old) were transduced at a low multiplicity of infection (MOI) of HIV vectors carrying a reporter gene. dNSs were added to the medium during transduction (5 mM dNS) and immediately before post-transduction culture (2.5 mM dNS). Macrophages were harvested 2-7 days after transduction and assayed for transgene expression by cytofluorimetry. RESULTS: The addition of dNS to the medium significantly enhanced the efficiency of transduction of human macrophages by HIV-based vectors. The percentage of cells expressing the transgene rose up to 50% in the presence of dNS, increasing the basal transduction levels up to 35-fold (average=10.8-fold). Furthermore, treatment with dNTP precursors compensated for the wide inter-donor variability, allowing the highest enhancement effects in donors with the lowest basal transduction efficiencies. CONCLUSIONS: This is the first demonstration that a single treatment of non-dividing target cells with exogenous dNS can enhance the efficiency of lentiviral-mediated transduction of cells, allowing for high efficiency gene transfer. The effects of dNTP precursors compensated for both the poor basal levels and the wide inter-donor variability, two major limitations for the transduction of non-dividing cells. Macrophages are a representative model of cells whose permissiveness to gene delivery was increased up to levels suitable for genetic manipulation applications. This simple approach might be transferred to a broader range of quiescent cell types that are scarcely susceptible to lentiviral-based gene delivery due to low dNTP levels.
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PURPOSE: To study whether and under what circumstances HIV can be controlled in chronically infected patients. METHOD: Nine patients treated with hydroxyurea and didanosine (PANDAs) were compared with 7 patients on highly active antiretroviral therapy (HAART) during an 8-week treatment interruption. Both groups had similar baseline viral load, CD4 count, and length of treatment. Treatment was resumed if viral rebound >10,000 copies/mL (virological failure) or CD4 count decrease below 200 cells/mm(3) (immunological failure) occurred in two consecutive measurements. RESULTS: None of the PANDAs failed. Viral rebound was spontaneously contained, and CD4 count remained stable. Four out of 7 patients in the HAART group failed to control HIV by week 6 and had to restart therapy due to either viremia rebound or CD4 decrease. Before therapy interruption, the PANDAs had a vigorous HIV-specific T cell immune response (median CD4VIR 1.2%), while the HAART-treated patients did not (median CD4VIR 0.2%) (CD4VIR represents the percentage of HIV-specific CD4 subpopulation expressing IFN-gamma within the total CD4 population [CD3+, CD4+, IFN-gamma+]). This difference was statistically significant (p =.002). CONCLUSION: This study shows that HIV can be controlled during therapy interruption in patients with established infection, and that control of viral replication correlates with vigorous anti-HIV specific immune responses.