The effects of HIV-1 viral protein r (vpr) and anti-retroviral drugs in the brain: Implications in HIV-1 associated neurocognitive disorders
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The morbidity and mortality of HIV-1 infected individuals has declined significantly by the introduction of highly active antiretroviral therapy (HAART). Nevertheless, different forms of HIV-1 associated neurocognitive disorders (HAND) still persist and affect about half of the HIV infected population. The importance of HIV-1 accessory protein Vpr has been well established in the pathology of AIDS in the peripheral and central nervous system. However, the role of Vpr in neuroinflammation and the underlying mechanisms involved have not been extensively studied. The RNA/Protein expression levels of three cytokines/chemokines (IL-6, IL-8 and CCL5) in the Vpr expressing astrocytes were determined in our study. We also examined the cellular mechanisms responsible for the Vpr-mediated induction of IL-6, IL-8 and CCL5. Recently, it has been noted that long term use of HAART and its associated toxicity might be involved in the persistence of HAND in HAART era. We studied the effects of antiretroviral drugs in vitro in astrocytes and neurons and in vivo in mice. We found that antiretroviral drugs lopinavir/ritonavir produce neuroinflammatory cytokines/chemokines (IL 6 and IL-8) and oxidative stress in vitro. Neuroplasticity proteins and antioxidant system were also perturbed by lopinavir/ritonavir treatment in mice brain which were prevented by the pretreatment with sulforaphane. In the first chapter, we investigate the effect of Vpr on the induction of IL-6 and IL-8 in human astrocytes. The levels of IL-6 and IL-8 showed significant increase both in primary human fetal astrocytes and in SVG astrocytic cell line transfected with a Vpr-expressing plasmid. Also, the involvements of PI3K-Akt and p38MAPK pathways as well as the transcription factor NF-κB, C/EBP and AP-1 were determined in Vpr-mediated induction of IL-6 and IL-8 by utilization of chemical inhibitors and siRNAs. In additional experiments, the translocation of NF-κB subunit p65 and the phosphorylation levels of various signaling molecules triggered by Vpr were determined. In the second chapter, the effect of Vpr on CCL5 induction was investigated in astrocytes. The expression levels of CCL5 showed significant up-regulation induced by Vpr. Moreover, the involvements of PI3K-Akt and p38MAPK pathways as well as the transcription factors NF-κB and AP-1 were determined in Vpr-mediated induction of CCL5 in astrocytes. In the third chapter, we investigate the effects of protease inhibitor drugs on the memory dysfunction. Proinflammatory cytokines/chemokines IL-6 and IL-8 showed significant up-regulation by lopinavir/ritonavir treatment in human fetal astrocytes and SVG astrocytic cell line. Reactive oxygen species was increased by lopinavir/ritonavir treatment in human fetal astrocytes, SVG astrocytes and differentiated SH-SY5Y neuronal cells. Lopinavir/ritonavir treatment caused significant learning and memory dysfunction in mice accompanied by the development of anxiety like phenomenon. Synaptic neuroplasticity genes, neurotropic factors and antioxidant genes were compromised by lopinavir/ritonavir treatment in mice brain. Neuroprotective plant isothiocynate compound sulforaphane rescued memory dysfunction caused by lopinavir/ritonavir and increased the levels of synaptic neuroplasticity genes, neurotropic factors and antioxidant genes. In conclusion, we demonstrated that HIV-1 Vpr was able to increase the production of pro-inflammatory cytokine/chemokines IL-6, IL-8 and CCL5 via different pathways. We demonstrated that lopinavir/ritonavir is involved in the development of HAND by inducing IL-6, IL-8, ROS and reducing antioxidant genes, neurotropic factors and synaptic plasticity proteins. We also showed that sulforaphane pretreatment was protective in lopinavir/ritonavir treated mice. The underlying mechanisms provide possible therapeutic targets for the intervention of neurocognitive dysfunction in HAND.
Table of Contents
General introduction -- General materials and methods -- The effects of HIV-1 VPR in the induction of interlukin-6 (IL-6) and interlukin-8 (IL-8) in the astrocytes -- the effects of HIV 1 VPR in the induction of C-C motif chemokine ligand-5 (CCL5) in the astrocytes -- The role of protease inhibitors in the development of HIV-1 associated neurocognitive disorder: prevention by sulforaphane -- Summary and future directions -- Appendix
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Ph.D.