IL-7 as a potential therapy for HIV-1-infected individuals

Highly active antiretroviral therapy (HAART), although effective in ameliorating the quality of life of HIV-1-infected individuals and their survival, has not been able to eradicate HIV-1. In fact, when HAART is interrupted, HIV-1 plasma viral load rebounds from viral reservoirs such as resting CD4+ T lymphocytes, monocytes and macrophages, remaining a major obstacle in attempting HIV eradication. Different therapeutic strategies have been attempted, such as structured treatment interruption (STI), immunotherapy (interleukin [IL]-2 and anti-CD3 antibodies [e.g., OKT3]), to try to stimulate HIV-1 out of latency along with antiretroviral intensification therapy. IL-7, a pleiotropic cytokine, bears diverse immune properties and plays a major role in T cell homeostasis. Moreover, IL-7 has recently been investigated as a possible immune adjuvant as well as a viral strain-specific inducer of HIV-1 replication. In fact, IL-7 was shown not only to be more effective than IL-2 in stimulating HIV-1 replication from resting CD4+ T lymphocytes ex vivo, but also to selectively induce a specific HIV-1 viral strain as compared with IL-2, suggesting the potential need for different viral inducers if complete eradication is to be achieved. In this present review, different immunological and virological properties of IL-7 are discussed, along with the possibility of its use as part of a combined antiretroviral-immune rationally based HIV-1 eradication approach.