Interleukin-7 in HIV pathogenesis and therapy.

Interleukin-7 (IL-7) is a γ-chain cytokine that plays a key role in T cell development and homeostasis by signaling through its cognate receptor, IL-7R or CD127, and inducing T cell survival and/or proliferation. Owing to its ability to promote CD4+ T cell homeostasis, IL-7 has elicited significant interest as a potential immunotherapy for HIV-infected individuals. Indeed, several studies have indicated that progressive HIV infection is associated with a complex dysregulation of the IL-7/IL-7R pathway consisting of increased plasma levels of this cytokine coupled with decreased percentages of CD4+ and CD8+ T cells expressing CD127. Administration of IL-7 to antiretroviral-treated HIV-infected individuals results in a selective increase in the fraction of naive and central-memory CD4+ T cells, suggesting a beneficial effect on overall CD4+ T cell function. For this reason, and given its potential role in depleting the reservoirs of latently infected CD4+ T cells, IL-7 therapy can be considered a promising approach for improving immune function in HIV-infected individuals.