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. 2001 Nov;75(22):10843-55.
doi: 10.1128/JVI.75.22.10843-10855.2001.

Exogenous interleukin-2 administration corrects the cell cycle perturbation of lymphocytes from human immunodeficiency virus-infected individuals

M Paiardini  1 , D Galati, B Cervasi, G Cannavo, L Galluzzi, M Montroni, D Guetard, M Magnani, G Piedimonte, G Silvestri
Affiliations

Exogenous interleukin-2 administration corrects the cell cycle perturbation of lymphocytes from human immunodeficiency virus-infected individuals

M Paiardini et al. J Virol. 2001 Nov.

Abstract

Human immunodeficiency virus (HIV)-induced immunodeficiency is characterized by progressive loss of CD4(+) T cells associated with functional abnormalities of the surviving lymphocytes. Increased susceptibility to apoptosis and loss of proper cell cycle control can be observed in lymphocytes from HIV-infected individuals and may contribute to the lymphocyte dysfunction of AIDS patients. To better understand the relation between T-cell activation, apoptosis, and cell cycle perturbation, we studied the effect of exogenous interleukin-2 (IL-2) administration on the intracellular turnover of phase-dependent proteins. Circulating T cells from HIV-infected patients display a marked discrepancy between a metabolic profile typical of G(0) and a pattern of expression of phase-dependent proteins that indicates a more-advanced position within the cell cycle. This discrepancy is enhanced by in vitro activation with ConA and ultimately results in a marked increase of apoptotic events. Conversely, treatment of lymphocytes with IL-2 alone restores the phase-specific pattern of expression of cell cycle-dependent proteins and is associated with low levels of apoptosis. Interestingly, exogenous IL-2 administration normalizes the overall intracellular protein turnover, as measured by protein synthesis, half-life of newly synthesised proteins, and total protein ubiquitination, thus providing a possible explanation for the effect of IL-2 on the intracellular kinetics of cell cycle-dependent proteins. The beneficial effect of IL-2 administration is consistent with the possibility of defective IL-2 function in vivo, which is confirmed by the observation that lymphocytes from HIV-infected patients show abnormal endogenous IL-2 paracrine/autocrine function upon in vitro mitogen stimulation. Overall these results confirm that perturbation of cell cycle control contributes to HIV-related lymphocyte dysfunction and, by showing that IL-2 administration can revert this perturbation, suggest a new mechanism of action of IL-2 therapy in HIV-infected patients.

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Figures

FIG. 1
FIG. 1
Abnormal expression of cell cycle-dependent proteins in PBLs from HIV-infected patients. Experiments were performed on samples collected from 20 HIV-infected individuals and 10 uninfected controls; results are expressed as means and standard deviations. (A) ODC expression as measured by optical density in spectrophotometry. (B) Intracellular concentration of the 19S regulator subunit 7 of the proteasome as measured by Western blotting. (C) Cyclin B intracellular concentration by Western blotting (D) Percentage of cyclin B-positive cells by flow cytometry as measured in the subpopulations of cells with DNA contents of 2n (G0/G1 phase), between 2n and 4n (S phase), and and 4n (G2/M phase). PBLs from HIV-infected patients and controls were costained with anti-cyclin B antibody and propidium iodide for DNA content. (E) Total intracellular nucleolin concentration (left) and AgNOR areas (right) in PBLs from HIV-infected patients and controls.
FIG. 1
FIG. 1
Abnormal expression of cell cycle-dependent proteins in PBLs from HIV-infected patients. Experiments were performed on samples collected from 20 HIV-infected individuals and 10 uninfected controls; results are expressed as means and standard deviations. (A) ODC expression as measured by optical density in spectrophotometry. (B) Intracellular concentration of the 19S regulator subunit 7 of the proteasome as measured by Western blotting. (C) Cyclin B intracellular concentration by Western blotting (D) Percentage of cyclin B-positive cells by flow cytometry as measured in the subpopulations of cells with DNA contents of 2n (G0/G1 phase), between 2n and 4n (S phase), and and 4n (G2/M phase). PBLs from HIV-infected patients and controls were costained with anti-cyclin B antibody and propidium iodide for DNA content. (E) Total intracellular nucleolin concentration (left) and AgNOR areas (right) in PBLs from HIV-infected patients and controls.
FIG. 2
FIG. 2
AgNOR and nucleolin staining in normal PBLs during phases of the cell cycle. G0 phase, unstimulated PBLs; G1/S, PBLs treated with ConA alone for 48 h (competence stimulus); G2/M, cells treated for 24 h with ConA followed by 24 h with IL-2 (competence and progression stimuli). Values of uptake of amino acids for system A (picomoles per minute per 106 cells), protein synthesis in initial velocity (nanomoles of [3H] leucine per 30 min per 106 cells), and DNA synthesis (counts per minute per 30 min per 106 cells) were normalized at 100 and expressed as percentages of peak activity. Values relative to those for unstimulated cells were described as not detectable (N.D.) since they were found to be consistently less than 0.5% of the peak activity.
FIG. 3
FIG. 3
Effect of ConA stimulation on AgNOR (A) and nucleolin (B) staining of PBLs from HIV-infected patients and controls. Stainings were performed at 24 and 48 h after ConA stimulation, and total cell count, cell death (as indicated by trypan blue exclusion), and apoptosis (as indicated by a DNA content of <2n) were determined at the same times.
FIG. 4
FIG. 4
Effect of exogenous IL-2 administration on AgNOR (A) and nucleolin (B) staining of PBLs from HIV-infected patients and controls. Stainings were performed at 24 and 48 h after IL-2 stimulation, and total cell count, cell death (as indicated by trypan blue exclusion), and apoptosis (as indicated by a DNA content of <2n) were determined at the same times.
FIG. 5
FIG. 5
Lymphocytes from HIV-infected patients produce normal amounts of IL-2 with reduced and shortened biological activity. (A) IL-2 accumulation in culture medium from ConA-treated PBLs from HIV-infected patients (open symbols) and controls (solid symbols). IL-2 levels were measured by ELISA. IL-2 accumulation in the conditioned media was measured as follows. After 4, 8, 12, 16, 20, and 24 h of in vitro mitogen activation, cells were collected and spun and the supernatant was used to measure IL-2 levels. Pelleted cells were then reincubated with fresh medium at the original concentration on a 24-well plate. (B) Initial velocity of IL-2 production by ConA-treated PBLs from HIV-infected patients (open symbols) and controls (solid symbols). After 4, 16, and 24 h of culture cells were washed in complete medium and IL-2 production was determined at 1, 5, and 10 min. (C) IL-2 biological activity in conditioned media from PBLs from HIV-infected patients (open symbols) and controls (solid symbols) at 4, 16, and 24 h after ConA activation. IL-2 activity is measured as proliferation index of the IL-2-dependent CTLL cell line. (D) Duration of IL-2 biological activity in conditioned medium from ConA-activated PBLs from HIV-infected patients (open symbols) and controls (solid symbols). IL-2 biological activity of the conditioned media is expressed as a percentage of the post-ConA peak biological activity after 4, 16, and 24 h of 37°C incubation.
FIG. 6
FIG. 6
IL-2 restores the intracellular protein turnover in lymphocytes from HIV-infected patients. (A) Polyacrylamide gel electrophoresis PAGE and Coomassie staining (left) and PAGE and autoradiography of newly synthesized proteins (right), as indicated by [35S]methionine incorporation in ConA-activated PBLs from HIV-infected patients and controls. (B) Half-life of newly synthesized proteins after ConA or IL-2 activation of PBLs from HIV-infected patients and controls. Half-life was determined by pulse-chase experiment using [3H] leucine incorporation. (C) Autoradiography gel showing the level of protein ubiquitination in ConA-and IL-2-treated PBLs from HIV-infected patients and controls. The total pixel intensity relative to any individual lane is plotted on the right side of the panel (open bars, results from HIV-infected patients; solid bars, results from uninfected controls). (D) Intracellular concentration of the 19S regulator subunit 7 of the proteasome. Shown are a Western blot of freshly isolated PBLs from HIV-infected patients (open bars) and controls (solid bars) and a Western blot of the same samples after 24 h of IL-2 treatment.
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References

    1. Adachi Y, Oyaizu N, Than S, McCloskey T W, Pahwa S. IL-2 rescues in vitro lymphocyte apoptosis in patients with HIV infection: correlation with its ability to block culture-induced down-modulation of bcl-2. J Immunol. 1996;157:4184–4193. - PubMed
    1. Amendola A, Poccia F, Martini F, Gioia C, Galati V, Pierdominici M, Marziali M, Pandolfi F, Colizzi V, Piacentini M, Girardi E, D'offizi G. Decreased CD95 expression on naive T cells from HIV-infected persons undergoing highly active anti-retroviral therapy (HAART) and the influence of IL-2 low dose administration. Irhan Group Study. Clin Exp Immunol. 2000;120:324–332. - PMC - PubMed
    1. Baserga R. Oncogenes and the strategy of growth factors. Cell. 1994;79:927–930. - PubMed
    1. Bohler T, Walcher J, Holzl-Wenig G, Geiss M, Buchholz B, Linde R, Debatin K M. Early effects of antiretroviral combination therapy on activation, apoptosis and regeneration of T cells in HIV-1-infected children and adolescents. AIDS. 1999;13:779–789. - PubMed
    1. Caggiari L, Zanussi S, Bortolin M T, Dandrea M, Nasti G, Simonelli C, Tirelli U, DePaoli P. Effects of therapy with highly active anti-retroviral therapy (HAART) and IL-2 on CD4+ and CD8+ T lymphocyte apoptosis in HIV+ patients. Clin Exp Immunol. 2000;120:101–106. - PMC - PubMed

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