Effective and targeted latency reversal in CD4+ T cells from individuals on long term combined antiretroviral therapy initiated during chronic HIV-1 infection.

To date, an affordable, effective treatment for an HIV-1 cure remains only a concept with most "latency reversal" agents (LRAs) lacking specificity for the latent HIV-1 reservoir and failing in early clinical trials. We assessed HIV-1 latency reversal using a multivalent HIV-1-derived virus-like particle (HLP) to treat samples from 32 people living with HIV-1 (PLWH) in Uganda, US and Canada who initiated combined antiretroviral therapy (cART) during chronic infection. Even after 5-20 years on stable cART, HLP could target CD4+ T cells harbouring latent HIV-1 reservoir resulting in 100-fold more HIV-1 release into culture supernatant than by common recall antigens, and 1000-fold more than by chemotherapeutic LRAs. HLP induced release of a divergent and replication-competent HIV-1 population from PLWH on cART. These findings suggest HLP provides a targeted approach to reactivate the majority of latent HIV-1 proviruses among individuals infected with HIV-1.

A heterogeneous human immunodeficiency virus-like particle (VLP) formulation produced by a novel vector system.

First identified as the etiological agent behind Acquired Immunodeficiency Syndrome (AIDS) in the early 1980s, HIV-1 has continued to spread into a global pandemic and major public health concern. Despite the success of antiretroviral therapy at reducing HIV-1 viremia and preventing the dramatic CD4+ T-cell collapse, infected individuals remain HIV positive for life. Unfortunately, it is increasingly clear that natural immunity is not, and may never be, protective against this pathogen. Therefore, efficacious vaccine interventions, which can either prevent infection or eradicate the latent viral reservoir and effect cure, are a major medical priority. Here we describe the development of a safe vaccine platform, currently being utilized in on-going prophylactic and therapeutic preclinical studies and consisting of highly heterogeneous virus-like particle formulations that represent the virus diversity within infected individuals. These VLPs contain no 5'LTR, no functional integrase, and have a severely mutated stem loop 1-thereby preventing any potential reverse transcription, integration, and RNA packaging. Furthermore, we demonstrate that these VLPs are morphologically identical to wild-type virus with polyvalent Env in a functional form. Finally, we show that the VLPs are antigenic and capable of generating strong immune recall responses.

The anti-tumoral drug enzastaurin inhibits natural killer cell cytotoxicity via activation of glycogen synthase kinase-3ß.

Enzastaurin is a selective protein kinase Cß inhibitor which is shown to have direct antitumor effect as well as suppress glycogen synthase kinase-3ß (GSK-3ß) phosphorylation (resulting in its activation) in both tumor tissues and peripheral blood mononuclear cells (PBMC). It is currently used in phase II trials for the treatment of colon cancer, refractory glioblastoma and diffuse large B cell lymphoma. In this study, the direct effect of enzastaurin on effector function of human natural killer (NK) cells was investigated. The results obtained showed that enzastaurin suppressed both natural and antibody-dependent cellular cytotoxicity (ADCC) of NK cells against different tumor targets. This inhibition was associated with a specific down-regulation of surface expression of NK cell activating receptor NKG2D and CD16 involved in natural cytotoxicity and ADCC respectively, as well as the inhibition of perforin release. Analysis of signal transduction revealed that enzastaurin activated GSK-3ß by inhibition of GSK-3ß phosphorylation. Treatment of NK cells with GSK-3ß-specific inhibitor TDZD-8 prevented enzastaurin-induced inhibition of NK cell cytotoxicity. Apart from the known antitumor and antiangiogenic effects, these results demonstrate that enzastaurin suppresses NK cell activity and may therefore interfere with NK cell-mediated tumor control in enzastaurin-treated cancer patients.