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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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Tetherin knockdown in mature DCs modestly enhances HIV-1 transmission to CD4+ T cells. Due to the differential localization of tetherin in matured DCs (Figure 3), tetherin knockdown was verified in (A) mDC-LPS by flow cytometry and in (C) mDC-IFNα by immunoblotting. Each plot is representative of three independent experiments performed. NS, non-silencing scramble siRNA control; KD, knockdown using tetherin siRNA. Tetherin knockdown in (B) mDC-LPS and (D) mDC-IFNα significantly enhanced transmission of single-cycle luciferase HIV-1 to Hut/CCR5 cells. Each graph represents mean results ± SEM of two independent experiments performed on DCs from different donors.
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Figure 5: Tetherin knockdown in mature DCs modestly enhances HIV-1 transmission to CD4+ T cells. Due to the differential localization of tetherin in matured DCs (Figure 3), tetherin knockdown was verified in (A) mDC-LPS by flow cytometry and in (C) mDC-IFNα by immunoblotting. Each plot is representative of three independent experiments performed. NS, non-silencing scramble siRNA control; KD, knockdown using tetherin siRNA. Tetherin knockdown in (B) mDC-LPS and (D) mDC-IFNα significantly enhanced transmission of single-cycle luciferase HIV-1 to Hut/CCR5 cells. Each graph represents mean results ± SEM of two independent experiments performed on DCs from different donors.

Mentions: To examine the role of tetherin in mature DC-mediated HIV-1 transmission to CD4+ T cells, tetherin expression in mature DCs was silenced with specific siRNA. To achieve efficient knockdown, iDCs were nucleofected with tetherin-specific or control siRNA and matured with LPS or IFNα. Analyses of tetherin expression at 2 days post nucleofection confirmed efficient knockdown of surface tetherin in mDC-LPS (Figure 5A) and total tetherin in mDC-IFNα (Figure 5C). To assess DC-mediated HIV-1 transmission, tetherin-silenced DCs were pulsed with the single-cycle luciferase reporter HIV-1 and co-cultured with the target Hut/CCR5 cells. Tetherin-silenced mDC-LPS and mDC-IFNα showed a modest 30-50% increase over the scramble siRNA controls in transmission of HIV-1 to Hut/CCR5 cells (Figure 5B and 5D), though the differences were statistically significant (P < 0.01). These data suggest that high levels of tetherin induced in mature DCs can modestly impair DC-mediated transmission of HIV-1 to CD4+ T cells.


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)

Tetherin knockdown in mature DCs modestly enhances HIV-1 transmission to CD4+ T cells. Due to the differential localization of tetherin in matured DCs (Figure 3), tetherin knockdown was verified in (A) mDC-LPS by flow cytometry and in (C) mDC-IFNα by immunoblotting. Each plot is representative of three independent experiments performed. NS, non-silencing scramble siRNA control; KD, knockdown using tetherin siRNA. Tetherin knockdown in (B) mDC-LPS and (D) mDC-IFNα significantly enhanced transmission of single-cycle luciferase HIV-1 to Hut/CCR5 cells. Each graph represents mean results ± SEM of two independent experiments performed on DCs from different donors.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3108291&req=5

Figure 5: Tetherin knockdown in mature DCs modestly enhances HIV-1 transmission to CD4+ T cells. Due to the differential localization of tetherin in matured DCs (Figure 3), tetherin knockdown was verified in (A) mDC-LPS by flow cytometry and in (C) mDC-IFNα by immunoblotting. Each plot is representative of three independent experiments performed. NS, non-silencing scramble siRNA control; KD, knockdown using tetherin siRNA. Tetherin knockdown in (B) mDC-LPS and (D) mDC-IFNα significantly enhanced transmission of single-cycle luciferase HIV-1 to Hut/CCR5 cells. Each graph represents mean results ± SEM of two independent experiments performed on DCs from different donors.
Mentions: To examine the role of tetherin in mature DC-mediated HIV-1 transmission to CD4+ T cells, tetherin expression in mature DCs was silenced with specific siRNA. To achieve efficient knockdown, iDCs were nucleofected with tetherin-specific or control siRNA and matured with LPS or IFNα. Analyses of tetherin expression at 2 days post nucleofection confirmed efficient knockdown of surface tetherin in mDC-LPS (Figure 5A) and total tetherin in mDC-IFNα (Figure 5C). To assess DC-mediated HIV-1 transmission, tetherin-silenced DCs were pulsed with the single-cycle luciferase reporter HIV-1 and co-cultured with the target Hut/CCR5 cells. Tetherin-silenced mDC-LPS and mDC-IFNα showed a modest 30-50% increase over the scramble siRNA controls in transmission of HIV-1 to Hut/CCR5 cells (Figure 5B and 5D), though the differences were statistically significant (P < 0.01). These data suggest that high levels of tetherin induced in mature DCs can modestly impair DC-mediated transmission of HIV-1 to CD4+ T cells.

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