Dual role of α-defensin-1 in anti–HIV-1 innate immunity
Theresa L. Chang, … , Armando DelPortillo, Mary E. Klotman
Theresa L. Chang, … , Armando DelPortillo, Mary E. Klotman
Published March 1, 2005
Citation Information: J Clin Invest. 2005;115(3):765-773. https://doi.org/10.1172/JCI21948.
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Article AIDS/HIV

Dual role of α-defensin-1 in anti–HIV-1 innate immunity

Abstract

α-Defensins are abundant antimicrobial peptides in polymorphonuclear leukocytes and play an important role in innate immunity. We have previously shown that α-defensin-1 can inhibit HIV-1 replication following viral entry. Here we examined the molecular mechanism(s) of α-defensin-1–mediated HIV-1 inhibition. α-Defensin-1 had a direct effect on HIV-1 virions at a low MOI in the absence of serum. The direct effect on HIV-1 virions was abolished by the presence of serum or an increase in virus particles. Studying the kinetics of the HIV life cycle revealed that α-defensin-1 inhibited steps following reverse transcription and integration. Analysis of PKC phosphorylation in primary CD4+ T cells in response to α-defensin-1 indicated that α-defensin-1 inhibited PKC activity. Pretreatment of infected CD4+ T cells with a PKC activator, bryostatin 1, partially reversed α-defensin-1–mediated HIV inhibition. Like α-defensin-1, the PKC isoform–selective inhibitor Go6976 blocked HIV-1 infection in a dose-dependent manner. Furthermore, kinetic studies and analysis of HIV-1 products indicated that α-defensin-1 and Go6976 blocked HIV-1 infection at similar stages in its life cycle, including nuclear import and transcription. Taken together, our studies demonstrate that, in the absence of serum, α-defensin-1 may act directly on the virus, but, in the presence of serum, its effects are on the cell, where it inhibits HIV-1 replication. At least 1 of the cellular effects associated with HIV inhibition is interference with PKC signaling in primary CD4+ T cells. Studying the complex function of α-defensin-1 in innate immunity against HIV has implications for prevention as well as therapeutics.

Authors

Theresa L. Chang, Jesus Vargas Jr., Armando DelPortillo, Mary E. Klotman

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Involvement of PKC signaling pathway(s) in α-defensin-1–mediated HIV-1 i...
Involvement of PKC signaling pathway(s) in α-defensin-1–mediated HIV-1 inhibition. (A) Whole-cell extracts were prepared from cells treated without or with α-defensin-1 at 10 μg/ml for 0, 5, and 15 minutes. PKC phosphorylation was analyzed using a phospho-PKC antibody. The blot was then stripped and reprobed with an antibody against PKC as a control. (B) Activated CD4+ T cells were infected with HIV-1HxB2–pseudotyped replication-defective luciferase virus. Infected cells were then treated with bryostatin 1 at 10 nM for 30 minutes, washed, and incubated without or with α-defensin-1 for 48 hours before measurement of luciferase activity. Data are mean ± SD of triplicate samples and represent 2 independent experiments. (C) Primary activated CD4+ T cells were pretreated without (lanes 1 and 2) or with (lanes 3 and 4) bryostatin 1 for 30 minutes and then not treated (lanes 1 and 3) or treated (lanes 2 and 4) with α-defensin-1 for 15 minutes. Whole-cell extracts were prepared and PKC phosphorylation was analyzed as described above.