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Interferon-α Subtypes in an Ex Vivo Model of Acute HIV-1 Infection: Expression, Potency and Effector Mechanisms.

Harper MS, Guo K, Gibbert K, Lee EJ, Dillon SM, Barrett BS, McCarter MD, Hasenkrug KJ, Dittmer U, Wilson CC, Santiago ML - PLoS Pathog. (2015)

Bottom Line: The relative potencies correlated with binding affinity to the type I IFN receptor and the induction levels of HIV-1 restriction factors Mx2 and Tetherin/BST-2 but not APOBEC3G, F and D.However, despite the lack of APOBEC3 transcriptional induction, the higher relative potency of IFNα8 and IFNα14 correlated with stronger inhibition of virion infectivity, which is linked to deaminase-independent APOBEC3 restriction activity.By contrast, both potent (IFNα8) and weak (IFNα1) subtypes significantly induced HIV-1 GG-to-AG hypermutation.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, University of Colorado Denver, Aurora, Colorado, United States of America; Department of Immunology and Microbiology, University of Colorado Denver, Aurora, Colorado, United States of America.

ABSTRACT
HIV-1 is transmitted primarily across mucosal surfaces and rapidly spreads within the intestinal mucosa during acute infection. The type I interferons (IFNs) likely serve as a first line of defense, but the relative expression and antiviral properties of the 12 IFNα subtypes against HIV-1 infection of mucosal tissues remain unknown. Here, we evaluated the expression of all IFNα subtypes in HIV-1-exposed plasmacytoid dendritic cells by next-generation sequencing. We then determined the relative antiviral potency of each IFNα subtype ex vivo using the human intestinal Lamina Propria Aggregate Culture model. IFNα subtype transcripts from the centromeric half of the IFNA gene complex were highly expressed in pDCs following HIV-1 exposure. There was an inverse relationship between IFNA subtype expression and potency. IFNα8, IFNα6 and IFNα14 were the most potent in restricting HIV-1 infection. IFNα2, the clinically-approved subtype, and IFNα1 were both highly expressed but exhibited relatively weak antiviral activity. The relative potencies correlated with binding affinity to the type I IFN receptor and the induction levels of HIV-1 restriction factors Mx2 and Tetherin/BST-2 but not APOBEC3G, F and D. However, despite the lack of APOBEC3 transcriptional induction, the higher relative potency of IFNα8 and IFNα14 correlated with stronger inhibition of virion infectivity, which is linked to deaminase-independent APOBEC3 restriction activity. By contrast, both potent (IFNα8) and weak (IFNα1) subtypes significantly induced HIV-1 GG-to-AG hypermutation. The results unravel non-redundant functions of the IFNα subtypes against HIV-1 infection, with strong implications for HIV-1 mucosal immunity, viral evolution and IFNα-based functional cure strategies.

No MeSH data available.


Related in: MedlinePlus

Correlation between ISG induction and IFNα subtype antiviral potency.(A) LPMCs (n = 3 donors) were thawed and infected with HIV-1BaL, then treated with 100 pg/ml of weak (gray bars) and potent (black bars) IFNα subtypes. IFNα1, IFNα2, IFNα8 and IFNα14 shown simply as 1, 2, 8 and 14. After 24 hr, CD4+ T cells were negatively selected and RNA extracted for qPCR. ISGs were quantified using Taqman qPCR normalized to GAPDH levels. Mean fold-induction values and SEM error bars for (B) Mx2, (C) Tetherin/BST-2 and (D) A3G relative to no IFNα control (N) are shown for the 3 donors. Data were analyzed using repeated measures ANOVA with Dunnett’s multiple comparison test. Statistical support for differences in fold-induction between IFNα1 and IFNα2, and IFNα2 and IFNα8/14 are shown. ns, not significant at p>0.05; *, p<0.05; **, p<0.01; ***, p<0.001.
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ppat.1005254.g004: Correlation between ISG induction and IFNα subtype antiviral potency.(A) LPMCs (n = 3 donors) were thawed and infected with HIV-1BaL, then treated with 100 pg/ml of weak (gray bars) and potent (black bars) IFNα subtypes. IFNα1, IFNα2, IFNα8 and IFNα14 shown simply as 1, 2, 8 and 14. After 24 hr, CD4+ T cells were negatively selected and RNA extracted for qPCR. ISGs were quantified using Taqman qPCR normalized to GAPDH levels. Mean fold-induction values and SEM error bars for (B) Mx2, (C) Tetherin/BST-2 and (D) A3G relative to no IFNα control (N) are shown for the 3 donors. Data were analyzed using repeated measures ANOVA with Dunnett’s multiple comparison test. Statistical support for differences in fold-induction between IFNα1 and IFNα2, and IFNα2 and IFNα8/14 are shown. ns, not significant at p>0.05; *, p<0.05; **, p<0.01; ***, p<0.001.

Mentions: The correlation between antiviral potency and IFNAR binding affinity suggested that the more potent IFNα subtypes might trigger higher ISG induction. To test this hypothesis, we quantified the mRNA expression levels of the IFNα-inducible HIV-1 restriction factors Mx2, Tetherin and APOBEC3 in LP CD4+ T cells after stimulation with representative IFNα subtypes. We focused on CD4+ T cells, the major cellular targets of HIV-1 replication in the GALT, but not intestinal macrophages, which are non-permissive to HIV-1 infection [53]. We selected IFNα8 and IFNα14 as potent IFNα subtypes due to their high affinity, highest antiviral potency in the LPAC model and high expression level in pDCs. IFNα1 and IFNα2 were selected as weak IFNα subtypes due to their relatively low affinity, weaker antiviral activity in the LPAC model (with IFNα2 being more potent than IFNα1), but high expression level in HIV-1-exposed pDCs (IFNα1 and IFNα2). IFNα2 was also chosen because of its clinical relevance. LPMCs were infected with HIV-1BaL and 100 pg/ml IFNα was administered. After 24 hr, CD4+ T cells were negatively selected and ISG mRNA expression was evaluated by qPCR (Fig 4A).


Interferon-α Subtypes in an Ex Vivo Model of Acute HIV-1 Infection: Expression, Potency and Effector Mechanisms.

Harper MS, Guo K, Gibbert K, Lee EJ, Dillon SM, Barrett BS, McCarter MD, Hasenkrug KJ, Dittmer U, Wilson CC, Santiago ML - PLoS Pathog. (2015)

Correlation between ISG induction and IFNα subtype antiviral potency.(A) LPMCs (n = 3 donors) were thawed and infected with HIV-1BaL, then treated with 100 pg/ml of weak (gray bars) and potent (black bars) IFNα subtypes. IFNα1, IFNα2, IFNα8 and IFNα14 shown simply as 1, 2, 8 and 14. After 24 hr, CD4+ T cells were negatively selected and RNA extracted for qPCR. ISGs were quantified using Taqman qPCR normalized to GAPDH levels. Mean fold-induction values and SEM error bars for (B) Mx2, (C) Tetherin/BST-2 and (D) A3G relative to no IFNα control (N) are shown for the 3 donors. Data were analyzed using repeated measures ANOVA with Dunnett’s multiple comparison test. Statistical support for differences in fold-induction between IFNα1 and IFNα2, and IFNα2 and IFNα8/14 are shown. ns, not significant at p>0.05; *, p<0.05; **, p<0.01; ***, p<0.001.
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ppat.1005254.g004: Correlation between ISG induction and IFNα subtype antiviral potency.(A) LPMCs (n = 3 donors) were thawed and infected with HIV-1BaL, then treated with 100 pg/ml of weak (gray bars) and potent (black bars) IFNα subtypes. IFNα1, IFNα2, IFNα8 and IFNα14 shown simply as 1, 2, 8 and 14. After 24 hr, CD4+ T cells were negatively selected and RNA extracted for qPCR. ISGs were quantified using Taqman qPCR normalized to GAPDH levels. Mean fold-induction values and SEM error bars for (B) Mx2, (C) Tetherin/BST-2 and (D) A3G relative to no IFNα control (N) are shown for the 3 donors. Data were analyzed using repeated measures ANOVA with Dunnett’s multiple comparison test. Statistical support for differences in fold-induction between IFNα1 and IFNα2, and IFNα2 and IFNα8/14 are shown. ns, not significant at p>0.05; *, p<0.05; **, p<0.01; ***, p<0.001.
Mentions: The correlation between antiviral potency and IFNAR binding affinity suggested that the more potent IFNα subtypes might trigger higher ISG induction. To test this hypothesis, we quantified the mRNA expression levels of the IFNα-inducible HIV-1 restriction factors Mx2, Tetherin and APOBEC3 in LP CD4+ T cells after stimulation with representative IFNα subtypes. We focused on CD4+ T cells, the major cellular targets of HIV-1 replication in the GALT, but not intestinal macrophages, which are non-permissive to HIV-1 infection [53]. We selected IFNα8 and IFNα14 as potent IFNα subtypes due to their high affinity, highest antiviral potency in the LPAC model and high expression level in pDCs. IFNα1 and IFNα2 were selected as weak IFNα subtypes due to their relatively low affinity, weaker antiviral activity in the LPAC model (with IFNα2 being more potent than IFNα1), but high expression level in HIV-1-exposed pDCs (IFNα1 and IFNα2). IFNα2 was also chosen because of its clinical relevance. LPMCs were infected with HIV-1BaL and 100 pg/ml IFNα was administered. After 24 hr, CD4+ T cells were negatively selected and ISG mRNA expression was evaluated by qPCR (Fig 4A).

Bottom Line: The relative potencies correlated with binding affinity to the type I IFN receptor and the induction levels of HIV-1 restriction factors Mx2 and Tetherin/BST-2 but not APOBEC3G, F and D.However, despite the lack of APOBEC3 transcriptional induction, the higher relative potency of IFNα8 and IFNα14 correlated with stronger inhibition of virion infectivity, which is linked to deaminase-independent APOBEC3 restriction activity.By contrast, both potent (IFNα8) and weak (IFNα1) subtypes significantly induced HIV-1 GG-to-AG hypermutation.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, University of Colorado Denver, Aurora, Colorado, United States of America; Department of Immunology and Microbiology, University of Colorado Denver, Aurora, Colorado, United States of America.

ABSTRACT
HIV-1 is transmitted primarily across mucosal surfaces and rapidly spreads within the intestinal mucosa during acute infection. The type I interferons (IFNs) likely serve as a first line of defense, but the relative expression and antiviral properties of the 12 IFNα subtypes against HIV-1 infection of mucosal tissues remain unknown. Here, we evaluated the expression of all IFNα subtypes in HIV-1-exposed plasmacytoid dendritic cells by next-generation sequencing. We then determined the relative antiviral potency of each IFNα subtype ex vivo using the human intestinal Lamina Propria Aggregate Culture model. IFNα subtype transcripts from the centromeric half of the IFNA gene complex were highly expressed in pDCs following HIV-1 exposure. There was an inverse relationship between IFNA subtype expression and potency. IFNα8, IFNα6 and IFNα14 were the most potent in restricting HIV-1 infection. IFNα2, the clinically-approved subtype, and IFNα1 were both highly expressed but exhibited relatively weak antiviral activity. The relative potencies correlated with binding affinity to the type I IFN receptor and the induction levels of HIV-1 restriction factors Mx2 and Tetherin/BST-2 but not APOBEC3G, F and D. However, despite the lack of APOBEC3 transcriptional induction, the higher relative potency of IFNα8 and IFNα14 correlated with stronger inhibition of virion infectivity, which is linked to deaminase-independent APOBEC3 restriction activity. By contrast, both potent (IFNα8) and weak (IFNα1) subtypes significantly induced HIV-1 GG-to-AG hypermutation. The results unravel non-redundant functions of the IFNα subtypes against HIV-1 infection, with strong implications for HIV-1 mucosal immunity, viral evolution and IFNα-based functional cure strategies.

No MeSH data available.


Related in: MedlinePlus