The presence of latent HIV in individuals treated with highly active antiretroviral therapy (ART) has been well established. Without additional therapies, individuals must remain on ART indefinitely in order to avoid development of severe immunodeficiency and spread of the virus. Because of the existence of this reservoir, treatment interruption invariably leads to viral rebound. Thus, it is generally accepted that eradication of the virus will require elimination of the latent reservoir. A drug type under investigation, although not in human trials at this time, is the family of protein kinase C agonists. We and others demonstrated that PKC agonists, in general, display strong activity across cell models of latency and in patient cells. Ingenol, a protein kinase C (PKC) agonist found in Euphorbiacea, a large family of succulent plants from semi-desertic areas of Brazil, has shown great potency in ex vivo patient cell assays and in in vitro systems. In the R21 phase, we will examine how ingenol derivatives mediate reactivation of latent HIV and which subset(s) of PKC isoforms.
In Aim 1, we plan to investigate the mechanism of action of various ingenol derivatives.
In Aim 2 we will investigate a role for HDAC inhibitors to enhance the activity of ingenols based on their ability to induce relaxed chromatin states. These studies will inform Aim 3, where we will test the best concentrations and combinations of the above drug categories in cells from aviremic patients. These studies will set the stage for testing of these compounds in the R33 phase of the grant. The R33 phase will consist of Aims 3 and 4.
Aim 3 will examine the potential influence that our optimized stimulation regimen(s) will have on the functionality of human immune effector cells, whether these are enhancing or perhaps deleterious to their activities. The cell types being examined will include natural killer cells, cytotoxic T lymphocytes, dendritic cells an regulatory T cells.
Aim 4 will test the best concentrations and combinations of the most potent ingenol derivative with and without an HDAC inhibitor in a humanized mouse model of HIV latency.
The existence of latent reservoirs of HIV-infected cells constitutes the major impediment towards viral eradication. This application seeks to characterize the mechanisms by which ingenol derivatives, with the help of HDAC inhibitors as adjuvants, induce viral reactivation from latency, with the ultimate goal of using this pathway as a target for viral eradication strategies.
|Spivak, Adam M; Larragoite, Erin T; Coletti, McKenna L et al. (2016) Janus kinase inhibition suppresses PKC-induced cytokine release without affecting HIV-1 latency reversal ex vivo. Retrovirology 13:88|