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HMGB1-dependent triggering of HIV-1 replication and persistence in dendritic cells as a consequence of NK-DC cross-talk.

Saïdi H, Melki MT, Gougeon ML - PLoS ONE (2008)

Bottom Line: This was associated with the defective production of IL-12 and IL-18 by infected DCs.Moreover, the crosstalk between activated NK cells and HIV-infected DCs resulted in a dramatic increase in viral replication and proviral DNA expression in DCs.HMGB1, produced both by NK cells and DCs, was found to play a pivotal role in this process, and inhibition of HMGB1 activity by glycyrrhizin, known to bind specifically to HMGB1, or blocking anti-HMGB1 antibodies, abrogated NK-dependent HIV-1 replication in DCs.

View Article: PubMed Central - PubMed

Affiliation: Institut Pasteur, Antiviral Immunity, Biotherapy and Vaccine Unit, INSERM U668, Paris, France.

ABSTRACT

Background: HIV-1 has evolved ways to exploit DCs, thereby facilitating viral dissemination and allowing evasion of antiviral immunity. Recently, the fate of DCs has been found to be extremely dependent on the interaction with autologous NK cells, but the mechanisms by which NK-DC interaction controls viral infections remain unclear. Here, we investigate the impact of NK-DC cross-talk on maturation and functions of HIV-infected immature DCs.

Methodology/principal findings: Immature DCs were derived from primary monocytes, cultured in the presence of IL-4 and GM-CSF. In some experiments, DCs were infected with R5-HIV-1(BaL) or X4-HIV-1(NDK), and viral replication, proviral HIV-DNA and the frequency of infected DCs were measured. Autologous NK cells were sorted and either kept unstimulated in the presence of suboptimal concentration of IL-2, or activated by a combination of PHA and IL-2. The impact of 24 h NK-DC cross-talk on the fate of HIV-1-infected DCs was analyzed. We report that activated NK cells were required for the induction of maturation of DCs, whether uninfected or HIV-1-infected, and this process involved HMGB1. However, the cross-talk between HIV-1-infected DCs and activated NK cells was functionally defective, as demonstrated by the strong impairment of DCs to induce Th1 polarization of naïve CD4 T cells. This was associated with the defective production of IL-12 and IL-18 by infected DCs. Moreover, the crosstalk between activated NK cells and HIV-infected DCs resulted in a dramatic increase in viral replication and proviral DNA expression in DCs. HMGB1, produced both by NK cells and DCs, was found to play a pivotal role in this process, and inhibition of HMGB1 activity by glycyrrhizin, known to bind specifically to HMGB1, or blocking anti-HMGB1 antibodies, abrogated NK-dependent HIV-1 replication in DCs.

Conclusion: These observations provide evidence for the crucial role of NK-DC cross-talk in promoting viral dissemination, and challenge the question of the in vivo involvement of HMGB1 in the triggering of HIV-1 replication and replenishment of viral reservoirs in AIDS.

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Exogenous rh-HMGB1 triggers HIV-1 replication in iDC.(a) iDC -infected with HIV-1BaL were cultured either alone or in the presence of aNK cells for 3 days. rh-HMGB1 (1 µg/ml) was added in some cultures. HIV replication was measured by p24 quantification in culture supernatant. (b) HIV-1-infected iDC were cultured either alone or in the presence of aNK cells for 3 days. Blocking anti-HMGB1 antibodies (10 µg/ml) or glycyrrhizin (10 µg/ml) were added at culture initiation. HIV replication was measured by p24 quantification in culture supernatant. The mean±sd of three independent experiments is shown. Statistical comparisons were made with the non-parametric Mann-Whitney test. * p<0.05.
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pone-0003601-g006: Exogenous rh-HMGB1 triggers HIV-1 replication in iDC.(a) iDC -infected with HIV-1BaL were cultured either alone or in the presence of aNK cells for 3 days. rh-HMGB1 (1 µg/ml) was added in some cultures. HIV replication was measured by p24 quantification in culture supernatant. (b) HIV-1-infected iDC were cultured either alone or in the presence of aNK cells for 3 days. Blocking anti-HMGB1 antibodies (10 µg/ml) or glycyrrhizin (10 µg/ml) were added at culture initiation. HIV replication was measured by p24 quantification in culture supernatant. The mean±sd of three independent experiments is shown. Statistical comparisons were made with the non-parametric Mann-Whitney test. * p<0.05.

Mentions: Exogenous HMGB1 was recently reported to increase HIV-1 replication in infected monocytic cell lines [39], and to induce in vitro the reactivation of HIV-1 in PBMCs from HIV-1-infected patients under antiretroviral therapy [40]. Therefore, we addressed the question of the role of HMGB1 in the NK-dependent triggering of HIV replication in DCs. We found that exogenous rh-HMGB1 had a direct effect on HIV-1BaL-infected iDC, enhancing dramatically the production of p24 in culture supernatants (Fig. 6a). rh-HMGB1 had also a significant stimulatory effect on p24 production by HIV-1-infected iDC cocultured with a NK cells (Fig. 6a). To investigate the influence of HMGB1 in the triggering of HIV-1 replication in infected-iDC-aNK cocultures, HMGB1-specific neutralizing antibodies or glycyrrhizin were added to these cocultures and p24 production was measured in the supernatant. Both HMGB1 inhibitors abrogated HIV-1 production by infected DC cocultured with aNK cells or cultured alone (Fig. 6b). These results indicate that exogenous HMGB1 is able to trigger HIV-1 replication by infected iDC. They also indicate that aNK cell-dependent stimulation of HIV-1 replication in iDCs is mediated by HMGB1.


HMGB1-dependent triggering of HIV-1 replication and persistence in dendritic cells as a consequence of NK-DC cross-talk.

Saïdi H, Melki MT, Gougeon ML - PLoS ONE (2008)

Exogenous rh-HMGB1 triggers HIV-1 replication in iDC.(a) iDC -infected with HIV-1BaL were cultured either alone or in the presence of aNK cells for 3 days. rh-HMGB1 (1 µg/ml) was added in some cultures. HIV replication was measured by p24 quantification in culture supernatant. (b) HIV-1-infected iDC were cultured either alone or in the presence of aNK cells for 3 days. Blocking anti-HMGB1 antibodies (10 µg/ml) or glycyrrhizin (10 µg/ml) were added at culture initiation. HIV replication was measured by p24 quantification in culture supernatant. The mean±sd of three independent experiments is shown. Statistical comparisons were made with the non-parametric Mann-Whitney test. * p<0.05.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2571988&req=5

pone-0003601-g006: Exogenous rh-HMGB1 triggers HIV-1 replication in iDC.(a) iDC -infected with HIV-1BaL were cultured either alone or in the presence of aNK cells for 3 days. rh-HMGB1 (1 µg/ml) was added in some cultures. HIV replication was measured by p24 quantification in culture supernatant. (b) HIV-1-infected iDC were cultured either alone or in the presence of aNK cells for 3 days. Blocking anti-HMGB1 antibodies (10 µg/ml) or glycyrrhizin (10 µg/ml) were added at culture initiation. HIV replication was measured by p24 quantification in culture supernatant. The mean±sd of three independent experiments is shown. Statistical comparisons were made with the non-parametric Mann-Whitney test. * p<0.05.
Mentions: Exogenous HMGB1 was recently reported to increase HIV-1 replication in infected monocytic cell lines [39], and to induce in vitro the reactivation of HIV-1 in PBMCs from HIV-1-infected patients under antiretroviral therapy [40]. Therefore, we addressed the question of the role of HMGB1 in the NK-dependent triggering of HIV replication in DCs. We found that exogenous rh-HMGB1 had a direct effect on HIV-1BaL-infected iDC, enhancing dramatically the production of p24 in culture supernatants (Fig. 6a). rh-HMGB1 had also a significant stimulatory effect on p24 production by HIV-1-infected iDC cocultured with a NK cells (Fig. 6a). To investigate the influence of HMGB1 in the triggering of HIV-1 replication in infected-iDC-aNK cocultures, HMGB1-specific neutralizing antibodies or glycyrrhizin were added to these cocultures and p24 production was measured in the supernatant. Both HMGB1 inhibitors abrogated HIV-1 production by infected DC cocultured with aNK cells or cultured alone (Fig. 6b). These results indicate that exogenous HMGB1 is able to trigger HIV-1 replication by infected iDC. They also indicate that aNK cell-dependent stimulation of HIV-1 replication in iDCs is mediated by HMGB1.

Bottom Line: This was associated with the defective production of IL-12 and IL-18 by infected DCs.Moreover, the crosstalk between activated NK cells and HIV-infected DCs resulted in a dramatic increase in viral replication and proviral DNA expression in DCs.HMGB1, produced both by NK cells and DCs, was found to play a pivotal role in this process, and inhibition of HMGB1 activity by glycyrrhizin, known to bind specifically to HMGB1, or blocking anti-HMGB1 antibodies, abrogated NK-dependent HIV-1 replication in DCs.

View Article: PubMed Central - PubMed

Affiliation: Institut Pasteur, Antiviral Immunity, Biotherapy and Vaccine Unit, INSERM U668, Paris, France.

ABSTRACT

Background: HIV-1 has evolved ways to exploit DCs, thereby facilitating viral dissemination and allowing evasion of antiviral immunity. Recently, the fate of DCs has been found to be extremely dependent on the interaction with autologous NK cells, but the mechanisms by which NK-DC interaction controls viral infections remain unclear. Here, we investigate the impact of NK-DC cross-talk on maturation and functions of HIV-infected immature DCs.

Methodology/principal findings: Immature DCs were derived from primary monocytes, cultured in the presence of IL-4 and GM-CSF. In some experiments, DCs were infected with R5-HIV-1(BaL) or X4-HIV-1(NDK), and viral replication, proviral HIV-DNA and the frequency of infected DCs were measured. Autologous NK cells were sorted and either kept unstimulated in the presence of suboptimal concentration of IL-2, or activated by a combination of PHA and IL-2. The impact of 24 h NK-DC cross-talk on the fate of HIV-1-infected DCs was analyzed. We report that activated NK cells were required for the induction of maturation of DCs, whether uninfected or HIV-1-infected, and this process involved HMGB1. However, the cross-talk between HIV-1-infected DCs and activated NK cells was functionally defective, as demonstrated by the strong impairment of DCs to induce Th1 polarization of naïve CD4 T cells. This was associated with the defective production of IL-12 and IL-18 by infected DCs. Moreover, the crosstalk between activated NK cells and HIV-infected DCs resulted in a dramatic increase in viral replication and proviral DNA expression in DCs. HMGB1, produced both by NK cells and DCs, was found to play a pivotal role in this process, and inhibition of HMGB1 activity by glycyrrhizin, known to bind specifically to HMGB1, or blocking anti-HMGB1 antibodies, abrogated NK-dependent HIV-1 replication in DCs.

Conclusion: These observations provide evidence for the crucial role of NK-DC cross-talk in promoting viral dissemination, and challenge the question of the in vivo involvement of HMGB1 in the triggering of HIV-1 replication and replenishment of viral reservoirs in AIDS.

Show MeSH
Related in: MedlinePlus