Transcriptional Regulation of Tumor Necrosis Factor-alpha by Human Immunodeficiency Virus-1 Vpr

HIV-1 Vpr is known to regulate both viral and host cellular promoters resulting in transcriptional regulation of various cellular factors in host immune cells, such as T cells, macrophages and dendritic cells. It has been shown that Vpr has a role in the upregulation of proinflammatory cytokine TNF-á, which affects immune regulation during infection. However, the mechanisms by which TNF-á is regulated by HIV-1 Vpr are not well understood. A goal of this project is to determine the effects of Vpr in its biologically relevant forms and identify the domains of Vpr involved in TNF-á production. Additionally, we also sought to determine whether TNF-á is up-regulated in infected/exposed cells and/or bystander cells. From our experiments, we conclude that HIV-1 Vpr increases TNF-a production in the context of infection as well as exposure in the absence of other viral proteins. Furthermore, HIV-1 Vpr has multiple domains capable of inducing TNF-á production. However, the increase in TNF-alpha production in DC is dependent on LPS stimulation. We were unable to conclusively determine the cell type that is responsible for this observed phenotype however the results from our studies indicate that infected/exposed cells could be the dominant producers.Due to the association of Vpr with transcriptional regulation of various cellular factors, we investigated the domains of the TNF-á promoter involved in Vpr-mediated TNF-á regulation. Using the HeLa T4 cell line, TNF-á promoter mediated transactivation was increased by two fold when exposed to HIV-1 Vpr(+) as opposed to HIV-1 Vpr(-) as detected by luciferase reporter assay. A six fold increase was observed in the transactivation of full length and mutant TNF-á promoter in macrophage-derived microglia cell line in the presence of Vpr expression. Results from mapping studies indicate that HIV-1 Vpr can regulate TNF-á production via multiple domains of the TNF-á promoter, however for maximum transactivation, the full-length promoter is required. Statement of Public Health Significance: By determining the details of HIV-1 Vpr and TNF-á interaction and the mechanisms for which they interact could reveal novel targets for the development of HIV-1 therapeutics in the fight against this epidemic