[Show abstract][Hide abstract] ABSTRACT: HIV infection and the associated chronic immune activation alter T cell homeostasis leading to CD4 T cell depletion and CD8 T cell expansion. The mechanisms behind these outcomes are not totally defined and only partially explained by the direct cytopathic effect of the virus. In this manuscript, we addressed the impact of lymphopenia and chronic exposure to IFN-α on T cell homeostasis. In a lymphopenic murine model, this interaction led to decreased CD4 counts and CD8 T cell expansion in association with an increase in the Signal Transducer and Activator of Transcription 1 (STAT1) levels resulting in enhanced CD4 T cell responsiveness to IFN-α. Thus, in the setting of HIV infection, chronic stimulation of this pathway could be detrimental for CD4 T cell homeostasis.
[Show abstract][Hide abstract] ABSTRACT: Determining the precise lifespan of human T-cell is challenging due to inability of standard techniques to distinguish between dividing and dying cells. Here, we measured the duration of in vivo persistence by following a pool of T-cells that were "naturally" labeled with a single integrated clone of a replication-incompetent HIV-1 provirus.
Utilizing a combination of techniques we were able to sequence/map an integration site of a unique provirus with a stop codon at position 42 of the HIV-1 protease. In-vitro reconstruction of this provirus into an infectious clone confirmed its inability to replicate. By combing cell separation and integration site-specific PCR we were able to follow the fate of this single provirus in multiple T-cell subsets over a 20-year period. As controls, a number of additional integrated proviruses were also sequenced.
The replication-incompetent HIV-1 provirus was solely contained in the pool of effector memory (EM) CD4 T-cell for 17 years. The percentage of the total EM CD4 T-cells containing the replication-incompetent provirus peaked at 1% with a functional half-life of 11.1 months. In the process of sequencing multiple proviruses, we also observed high levels of lethal mutations in the peripheral blood pool of proviruses.
These data indicate that human EM CD4 T-cells are able to persist in vivo for >17 years without detectably reverting to a central memory phenotype. A secondary observation is that the fraction of the pool of integrated HIV-1 proviruses capable of replicating may be considerably less than the 12% currently noted in the literature.
AIDS (London, England) 01/2014; · 4.91 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Data from prospectively planned cohort studies on risk of major clinical outcomes and prognostic factors for patients with influenza A(H1N1)pdm09 virus are limited. In 2009, in order to assess outcomes and evaluate risk factors for progression of illness, two cohort studies were initiated: FLU 002 in outpatients and FLU 003 in hospitalized patients.
PLoS ONE 01/2014; 9(7):e101785. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: IL-27 is an immunomodulatory cytokine with potent anti-HIV properties in PBMCs, CD4+ T cells, macrophages and immature dendritic cells. Previous smaller studies have suggested that HIV-1 infection may alter IL-27 and influence HIV-1 pathogenesis. The aim of this study was to examine the relationship between plasma IL-27 levels in a well-characterised cohort of HIV-1 infected patients.
PLoS ONE 01/2014; 9(6):e98989. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The optimal individualized selection of antiretroviral drugs in resource-limited settings is challenging because of the limited availability of drugs and genotyping. Here we describe the development of the latest computational models to predict the response to combination antiretroviral therapy without a genotype, for potential use in such settings.
Random forest models were trained to predict the probability of a virological response to therapy (<50 copies HIV RNA/mL) following virological failure using the following data from 22 567 treatment-change episodes including 1090 from southern Africa: baseline viral load and CD4 cell count, treatment history, drugs in the new regimen, time to follow-up and follow-up viral load. The models were assessed during cross-validation and with an independent global test set of 1000 cases including 100 from southern Africa. The models' accuracy [area under the receiver-operating characteristic curve (AUC)] was evaluated and compared with genotyping using rules-based interpretation systems for those cases with genotypes available.
The models achieved AUCs of 0.79-0.84 (mean 0.82) during cross-validation, 0.80 with the global test set and 0.78 with the southern African subset. The AUCs were significantly lower (0.56-0.57) for genotyping.
The models predicted virological response to HIV therapy without a genotype as accurately as previous models that included a genotype. They were accurate for cases from southern Africa and significantly more accurate than genotyping. These models will be accessible via the online treatment support tool HIV-TRePS and have the potential to help optimize antiretroviral therapy in resource-limited settings where genotyping is not generally available.
Journal of Antimicrobial Chemotherapy 11/2013; · 5.34 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In addition to silencing specific genes, small interfering RNA (siRNA) transfection is also associated with the non-specific induction of inflammatory cytokines and type I interferon. Those so-called "off-target" effects have considerable implications for the interpretation of in vitro studies and clinical application of siRNA. The present study attempted to develop a better understanding of the mechanism involved in these off target effects. Synthesized siRNA significantly enhances DNA-mediated interferon lambda-1 response (IFN-λ1/IL-29), a newly characterized antiviral interferon in non-immune or primary immune cells. This enhancement was most pronounced by double-stranded siRNA with at least a 2-nucleotide overhang at one 3' terminus in a dose-dependent manner, while the presence of DNA was indispensable. A pull-down assay using biotinylated siRNA- or DNA-conjugated beads indicated that retinoic acid-inducible gene I (RIG-I) and interferon gamma-inducible protein 16 (IFI16) were involved in the sensing of siRNA and DNA, respectively. Co-immunoprecipitation analysis further revealed that RIG-I and IFI16 formed a complex via siRNA, and the dissociation of IFI16 from this complex in the presence of DNA activated the downstream STING-TBK1-IRF3 (stimulator of interferon genes - tank-binding kinase 1 - interferon regulatory factor 3) pathway, shedding light on a new physiological signalling pathway to activate innate immunity. Collectively, these findings may provide rational information for siRNA-induced innate immunity, with important implications for developing siRNA-based reagents to control human diseases.
Nucleic Acids Research 09/2013; · 8.81 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Interleukin 27 (IL-27) is an immunomodulatory cytokine with important roles in both the innate and adaptive immune systems. In the last five years, the addition of exogenous IL-27 to primary cell cultures has been demonstrated to decrease HIV-1 replication in a number of cell types including peripheral blood mononuclear cells (PBMCs), CD4+ T cells, macrophages and dendritic cells. These in vitro findings suggest that IL-27 may have therapeutic value in the setting of HIV-1 infection. In this review, we describe the current knowledge of the biology of IL-27, its effects primarily on HIV-1 replication but also in other viral infections and explore its potential role as a therapeutic cytokine for the treatment of patients with HIV-1 infection.
[Show abstract][Hide abstract] ABSTRACT: During HIV infection distinct mechanisms drive immune activation of the CD4 and CD8 T cells leading to CD4 T-cell depletion and expansion of the CD8 T-cell pool. This immune activation is polyclonal and extends beyond HIV-specific T cells. One consequence of this immune activation is a profound decrease in IL-7Rα (CD127) expression on memory CD8 T cells. The mechanisms leading to this are unknown and because of the potential impact of reduced IL-7 signaling in memory T cells specific to HIV and other pathogens, in the present study we examined the molecular mechanisms implicated in this downregulation of CD127.
Membrane bound (mIL7RA) and soluble (sIL7RA) mRNA expression was determined by qRT-PCR. CD127, Eomesodermin (Eomes) and T-bet expression in healthy controls and HIV-infected patients were studied by flow cytometry.
CD127 downregulation occurs at the transcriptional level for both mIL7RA and sIL7RA alternative spliced forms in the CD127 memory CD8 T cells. CD127 memory CD8 T cells exhibited increased Eomes expression and an 'effector-like' gene profile. These changes were associated with higher HIV-RNA levels. Following combination antiretroviral therapy (cART), there was an increase in CD127 expression over an extended period of time (>5 months) which was associated with decreased Eomes expression.
CD127 is downregulated at a transcriptional level in memory CD8 T cells in association with upregulation of Eomes expression.
AIDS (London, England) 07/2013; 27(12):1867-77. · 4.91 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We report a case of AIDS presenting as VZV meningomyeloradiculitis associated with HIV viral quasispecies compartmentalization within the CSF, and a CSF viral load that was 1 log higher than in peripheral blood. Prolonged antiviral therapy for both VZV and HIV-1 was associated with partial resolution.
[Show abstract][Hide abstract] ABSTRACT: Interleukin (IL)-2 has been used in culture of primary T cell to maintain cell proliferation. We have previously reported that IL-27 inhibits HIV-1 replication in primary T cells in the presence of IL-2. To gain a better understanding of the mechanisms involved in this inhibitory effect, we attempted to investigate in detail the effects of IL-27 and IL-2 using several cell lines. Unexpectedly, IL-27 did not inhibit HIV-1 in T cell lines, while IL-2 inhibited HIV-1 replication in the HTLV-1 transformed T cell lines, MT-2, MT-4 SLB-1 and ATL-2. No effects were seen in HTLV-1 negative cell lines. Utilizing MT-2 cells we demonstrated that IL-2-treatment inhibited HIV-1 syncytia-inducing ability and dose-dependently decreased supernatant p24 antigen levels by >90%. Using real time PCR and western blot analysis, we observed that IL-2 treatment induced the host restriction factor, APOBEC3G with accumulation into the lower molecular mass active form as characterized by FPLC. Further analysis revealed that the virus recovered from IL-2-treated MT-2 cells had impaired replication competency. This was found to be due to incorporation of APOBEC3G into the virion despite the presence of Vif. These findings demonstrate a novel role for IL-2 in regulating production of infectious HIV-1 virions in HTLV-1 infected cells through the induction of APOBEC3G.
Journal of Biological Chemistry 05/2013; · 4.65 Impact Factor