SMAC Mimetics as Therapeutic Agents in HIV Infection

Although combination antiretroviral therapy is extremely effective in lowering HIV RNA to undetectable levels in the blood, HIV persists in latently infected CD4⁺ T-cells and persistently infected macrophages. In latently/persistently infected cells, HIV proteins have shown to affect the expression of proteins involved in the apoptosis pathway, notably the inhibitors of apoptosis proteins (IAPs), and thereby influence cell survival. IAPs, which are inhibited by endogenous second mitochondrial-derived activators of caspases (SMAC), can serve as targets for SMAC mimetics, synthetic compounds capable of inducing apoptosis. There is increasing evidence that SMAC mimetics can be used to reverse HIV latency and/or kill cells that are latently/persistently infected with HIV. Here, we review the current state of knowledge of SMAC mimetics as an approach to eliminate HIV infected cells and discuss the potential future use of SMAC mimetics as part of an HIV cure strategy.

Soluble CD127 potentiates IL-7 activity in vivo in healthy mice

Introduction

Soluble forms of cytokine receptors can be involved in the endogenous regulation of cytokine activity. Soluble interleukin 7 receptor α (sCD127) naturally binds IL‐7, therefore there is interest in its potential application as an immunotherapeutic agent to regulate IL‐7. With the hypothesis that sCD127 enhances IL‐7 activity, thus promoting T‐cell proliferation in vivo, we sought to assess the effect of sCD127, IL‐7 or IL‐7 + sCD127 treatment on CD4⁺ and CD8⁺ T‐cells in the blood and spleen of mice.

Methods

Peripheral blood mononuclear cells and splenocytes were prepared, and analyzed for T‐cell number, phenotype and proliferation (Ki67⁺) by flow cytometry.

Results

IL‐7 treatment induced T‐cell proliferation, increased T‐cell number, and triggered T‐cell differentiation each of which was enhanced with the addition of sCD127. IL‐7 + sCD127 treatment significantly increased spleen weight over that seen with IL‐7 treatment alone. More pronounced proliferation and a greater increase in cell number was observed in CD8⁺ T‐cells relative to the effect on CD4⁺ T‐cells.

Conclusions

These findings suggest that the addition of sCD127 enhances IL‐7‐mediated T‐cell proliferation and suggests a potential therapeutic use for sCD127.