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Tetherin does not significantly restrict dendritic cell-mediated HIV-1 transmission and its expression is upregulated by newly synthesized HIV-1 Nef.

Coleman CM, Spearman P, Wu L - Retrovirology (2011)

Bottom Line: High levels of tetherin were transiently expressed in LPS- and IFNα-induced mature DCs, while HIV-1 localized into distinct patches in these DCs.Intriguingly, we found that HIV-1 replication in immature DCs induced significant tetherin expression in a Nef-dependent manner.Nef-dependent tetherin induction in HIV-1-infected immature DCs suggests an innate immune response of DCs to HIV-1 infection.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Retrovirus Research, Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA.

ABSTRACT

Background: Dendritic cells (DCs) are among the first cells to encounter HIV-1 and play important roles in viral transmission and pathogenesis. Immature DCs allow productive HIV-1 replication and long-term viral dissemination. The pro-inflammatory factor lipopolysaccharide (LPS) induces DC maturation and enhances the efficiency of DC-mediated HIV-1 transmission. Type I interferon (IFN) partially inhibits HIV-1 replication and cell-cell transmission in CD4+ T cells and macrophages. Tetherin is a type I IFN-inducible restriction factor that blocks HIV-1 release and modulates CD4+ T cell-mediated cell-to-cell transmission of HIV-1. However, the role of type I IFN and tetherin in HIV-1 infection of DCs and DC-mediated viral transmission remains unknown.

Results: We demonstrated that IFN-alpha (IFNα)-induced mature DCs restricted HIV-1 replication and trans-infection of CD4+ T cells. Tetherin expression in monocyte-derived immature DCs was undetectable or very low. High levels of tetherin were transiently expressed in LPS- and IFNα-induced mature DCs, while HIV-1 localized into distinct patches in these DCs. Knockdown of induced tetherin in LPS- or IFNα-matured DCs modestly enhanced HIV-1 transmission to CD4+ T cells, but had no significant effect on wild-type HIV-1 replication in mature DCs. Intriguingly, we found that HIV-1 replication in immature DCs induced significant tetherin expression in a Nef-dependent manner.

Conclusions: The restriction of HIV-1 replication and transmission in IFNα-induced mature DCs indicates a potent anti-HIV-1 response; however, high levels of tetherin induced in mature DCs cannot significantly restrict wild-type HIV-1 release and DC-mediated HIV-1 transmission. Nef-dependent tetherin induction in HIV-1-infected immature DCs suggests an innate immune response of DCs to HIV-1 infection.

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Induced tetherin in mature DCs has different effects on WT and Vpu-deleted HIV-1 replication and DC-mediated HIV-1 transmission to CD4+ T cells. (A and B) The effect of tetherin on HIV-1 replication in mature DCs was assessed by tetherin knockdown and infection with WT NL(AD8) or NL(AD8)ΔVpu. Supernatant p24 in mDC-LPS (A) or mDC-IFNα (B) nucleofected with tetherin-specific siRNA or a non-silencing (NS) scramble siRNA control were assessed by p24 ELISA at 5 days post-infection. (C and D) The effect of tetherin on cell-to-cell transmission of WT NL(AD8) or NL(AD8)ΔVpu from tetherin-specific or NS siRNA nucleofected mDC-LPS (C) or mDC-IFNα (D) to Hut/CCR5 cells. Supernatants were collected after 2 days of co-culture and p24 concentration was assessed by ELISA. Graphs represent data from one donor representative of at least two experiments performed on DCs from different donors. Data are presented as mean ± SEM of duplicate samples.
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Figure 6: Induced tetherin in mature DCs has different effects on WT and Vpu-deleted HIV-1 replication and DC-mediated HIV-1 transmission to CD4+ T cells. (A and B) The effect of tetherin on HIV-1 replication in mature DCs was assessed by tetherin knockdown and infection with WT NL(AD8) or NL(AD8)ΔVpu. Supernatant p24 in mDC-LPS (A) or mDC-IFNα (B) nucleofected with tetherin-specific siRNA or a non-silencing (NS) scramble siRNA control were assessed by p24 ELISA at 5 days post-infection. (C and D) The effect of tetherin on cell-to-cell transmission of WT NL(AD8) or NL(AD8)ΔVpu from tetherin-specific or NS siRNA nucleofected mDC-LPS (C) or mDC-IFNα (D) to Hut/CCR5 cells. Supernatants were collected after 2 days of co-culture and p24 concentration was assessed by ELISA. Graphs represent data from one donor representative of at least two experiments performed on DCs from different donors. Data are presented as mean ± SEM of duplicate samples.

Mentions: To further examine the role of induced tetherin in replication-competent HIV-1 infection and transmission mediated by DCs, we assessed the effect of tetherin knockdown on the release of WT and Vpu-deleted (ΔVpu) HIV-1 from infected mature DCs and on DC-mediated HIV-1 transmission to Hut/CCR5 cells. Efficient tetherin knockdown was achieved in mDC-LPS and mDC-IFNα (Figure 5A,C and data not shown). Tetherin-silenced mature DCs were infected with WT NL(AD8) or ΔVpu NL(AD8) and HIV-1 p24 in the supernatants was assessed at 5 dpi, which was generally the peak of HIV-1 replication in iDCs (Figure 2D). Tetherin knockdown in mDC-LPS had no significant effect on the release of WT HIV-1, while the release of ΔVpu HIV-1 was inhibited 2-fold upon tetherin knockdown (Figure 6A). By contrast, the release of WT and ΔVpu HIV-1 from mDC-IFNα was enhanced by 38% and 2-fold upon tetherin knockdown, respectively (Figure 6B). HIV-1 infections of tetherin-silenced mature DCs were performed three times with different donors' cells and there was no statistically significant difference in WT HIV-1 release. Thus, induced tetherin expression in mature DCs does not play a major role in restriction of WT HIV-1 replication.


Tetherin does not significantly restrict dendritic cell-mediated HIV-1 transmission and its expression is upregulated by newly synthesized HIV-1 Nef.

Coleman CM, Spearman P, Wu L - Retrovirology (2011)

Induced tetherin in mature DCs has different effects on WT and Vpu-deleted HIV-1 replication and DC-mediated HIV-1 transmission to CD4+ T cells. (A and B) The effect of tetherin on HIV-1 replication in mature DCs was assessed by tetherin knockdown and infection with WT NL(AD8) or NL(AD8)ΔVpu. Supernatant p24 in mDC-LPS (A) or mDC-IFNα (B) nucleofected with tetherin-specific siRNA or a non-silencing (NS) scramble siRNA control were assessed by p24 ELISA at 5 days post-infection. (C and D) The effect of tetherin on cell-to-cell transmission of WT NL(AD8) or NL(AD8)ΔVpu from tetherin-specific or NS siRNA nucleofected mDC-LPS (C) or mDC-IFNα (D) to Hut/CCR5 cells. Supernatants were collected after 2 days of co-culture and p24 concentration was assessed by ELISA. Graphs represent data from one donor representative of at least two experiments performed on DCs from different donors. Data are presented as mean ± SEM of duplicate samples.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 6: Induced tetherin in mature DCs has different effects on WT and Vpu-deleted HIV-1 replication and DC-mediated HIV-1 transmission to CD4+ T cells. (A and B) The effect of tetherin on HIV-1 replication in mature DCs was assessed by tetherin knockdown and infection with WT NL(AD8) or NL(AD8)ΔVpu. Supernatant p24 in mDC-LPS (A) or mDC-IFNα (B) nucleofected with tetherin-specific siRNA or a non-silencing (NS) scramble siRNA control were assessed by p24 ELISA at 5 days post-infection. (C and D) The effect of tetherin on cell-to-cell transmission of WT NL(AD8) or NL(AD8)ΔVpu from tetherin-specific or NS siRNA nucleofected mDC-LPS (C) or mDC-IFNα (D) to Hut/CCR5 cells. Supernatants were collected after 2 days of co-culture and p24 concentration was assessed by ELISA. Graphs represent data from one donor representative of at least two experiments performed on DCs from different donors. Data are presented as mean ± SEM of duplicate samples.
Mentions: To further examine the role of induced tetherin in replication-competent HIV-1 infection and transmission mediated by DCs, we assessed the effect of tetherin knockdown on the release of WT and Vpu-deleted (ΔVpu) HIV-1 from infected mature DCs and on DC-mediated HIV-1 transmission to Hut/CCR5 cells. Efficient tetherin knockdown was achieved in mDC-LPS and mDC-IFNα (Figure 5A,C and data not shown). Tetherin-silenced mature DCs were infected with WT NL(AD8) or ΔVpu NL(AD8) and HIV-1 p24 in the supernatants was assessed at 5 dpi, which was generally the peak of HIV-1 replication in iDCs (Figure 2D). Tetherin knockdown in mDC-LPS had no significant effect on the release of WT HIV-1, while the release of ΔVpu HIV-1 was inhibited 2-fold upon tetherin knockdown (Figure 6A). By contrast, the release of WT and ΔVpu HIV-1 from mDC-IFNα was enhanced by 38% and 2-fold upon tetherin knockdown, respectively (Figure 6B). HIV-1 infections of tetherin-silenced mature DCs were performed three times with different donors' cells and there was no statistically significant difference in WT HIV-1 release. Thus, induced tetherin expression in mature DCs does not play a major role in restriction of WT HIV-1 replication.

Bottom Line: High levels of tetherin were transiently expressed in LPS- and IFNα-induced mature DCs, while HIV-1 localized into distinct patches in these DCs.Intriguingly, we found that HIV-1 replication in immature DCs induced significant tetherin expression in a Nef-dependent manner.Nef-dependent tetherin induction in HIV-1-infected immature DCs suggests an innate immune response of DCs to HIV-1 infection.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Retrovirus Research, Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA.

ABSTRACT

Background: Dendritic cells (DCs) are among the first cells to encounter HIV-1 and play important roles in viral transmission and pathogenesis. Immature DCs allow productive HIV-1 replication and long-term viral dissemination. The pro-inflammatory factor lipopolysaccharide (LPS) induces DC maturation and enhances the efficiency of DC-mediated HIV-1 transmission. Type I interferon (IFN) partially inhibits HIV-1 replication and cell-cell transmission in CD4+ T cells and macrophages. Tetherin is a type I IFN-inducible restriction factor that blocks HIV-1 release and modulates CD4+ T cell-mediated cell-to-cell transmission of HIV-1. However, the role of type I IFN and tetherin in HIV-1 infection of DCs and DC-mediated viral transmission remains unknown.

Results: We demonstrated that IFN-alpha (IFNα)-induced mature DCs restricted HIV-1 replication and trans-infection of CD4+ T cells. Tetherin expression in monocyte-derived immature DCs was undetectable or very low. High levels of tetherin were transiently expressed in LPS- and IFNα-induced mature DCs, while HIV-1 localized into distinct patches in these DCs. Knockdown of induced tetherin in LPS- or IFNα-matured DCs modestly enhanced HIV-1 transmission to CD4+ T cells, but had no significant effect on wild-type HIV-1 replication in mature DCs. Intriguingly, we found that HIV-1 replication in immature DCs induced significant tetherin expression in a Nef-dependent manner.

Conclusions: The restriction of HIV-1 replication and transmission in IFNα-induced mature DCs indicates a potent anti-HIV-1 response; however, high levels of tetherin induced in mature DCs cannot significantly restrict wild-type HIV-1 release and DC-mediated HIV-1 transmission. Nef-dependent tetherin induction in HIV-1-infected immature DCs suggests an innate immune response of DCs to HIV-1 infection.

Show MeSH
Related in: MedlinePlus