title: Treatment with IL-7 prevents the decline of circulating CD4+ T cells during the acute phase of SIV infection in rhesus macaques.
abstract: Although treatment with interleukin-7 (IL-7) was shown to transiently expand the naïve and memory T-cell pools in patients with chronic HIV-1 infection receiving antiretroviral therapy (ART), it is uncertain whether a full immunologic reconstitution can be achieved. Moreover, the effects of IL-7 have never been evaluated during acute HIV-1 (or SIV) infection, a critical phase of the disease in which the most dramatic depletion of CD4(+) T cells is believed to occur. In the present study, recombinant, fully glycosylated simian IL-7 (50 µg/kg, s.c., once weekly for 7 weeks) was administered to 6 rhesus macaques throughout the acute phase of infection with a pathogenic SIV strain (mac251); 6 animals were infected at the same time and served as untreated controls. Treatment with IL-7 did not cause clinically detectable side effects and, despite the absence of concomitant ART, did not induce significant increases in the levels of SIV replication except at the earliest time point tested (day 4 post-infection). Strikingly, animals treated with IL-7 were protected from the dramatic decline of circulating naïve and memory CD4(+) T cells that occurred in untreated animals. Treatment with IL-7 induced only transient T-cell proliferation, but it was associated with sustained increase in the expression of the anti-apoptotic protein Bcl-2 on both CD4(+) and CD8(+) T cells, persistent expansion of all circulating CD8(+) T-cell subsets, and development of earlier and stronger SIV Tat-specific T-cell responses. However, the beneficial effects of IL-7 were not sustained after treatment interruption. These data demonstrate that IL-7 administration is effective in protecting the CD4(+) T-cell pool during the acute phase of SIV infection in macaques, providing a rationale for the clinical evaluation of this cytokine in patients with acute HIV-1 infection.
authors.affiliation: Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Lia
authors.initials: L
authors.lastname: Vassena
authors.forename: Huiyi
authors.initials: H
authors.lastname: Miao
authors.forename: Raffaello
authors.initials: R
authors.lastname: Cimbro
authors.forename: Mauro S
authors.initials: MS
authors.lastname: Malnati
authors.forename: Giulia
authors.initials: G
authors.lastname: Cassina
authors.forename: Michael A
authors.initials: MA
authors.lastname: Proschan
authors.forename: Vanessa M
authors.initials: VM
authors.lastname: Hirsch
authors.forename: Bernard A
authors.initials: BA
authors.lastname: Lafont
authors.forename: Michel
authors.initials: M
authors.lastname: Morre
authors.forename: Anthony S
authors.initials: AS
authors.lastname: Fauci
authors.forename: Paolo
authors.initials: P
authors.lastname: Lusso
mesh_terms: D000208:Acute Disease; D000818:Animals; D016516:CD4-CD8 Ratio; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism* / Q000821:virology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D002908:Chronic Disease; D004353:Drug Evaluation, Preclinical; D015658:HIV Infections / Q000188:drug therapy / Q000276:immunology / Q000378:metabolism; D015497:HIV-1 / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007156:Immunologic Memory / Q000187:drug effects*; D015851:Interleukin-7 / Q000494:pharmacology*; D008253:Macaca mulatta; D016097:Simian Acquired Immunodeficiency Syndrome / Q000188:drug therapy* / Q000276:immunology / Q000378:metabolism; D015302:Simian Immunodeficiency Virus / Q000276:immunology / Q000378:metabolism*
chemical_list: D015851:Interleukin-7