Cutting edge: Prolonged exposure to HIV reinforces a poised epigenetic program for PD-1 expression in virus-specific CD8 T cells - PubMed (original) (raw)

. 2013 Jul 15;191(2):540-4.

doi: 10.4049/jimmunol.1203161. Epub 2013 Jun 14.

Alessandra Noto, Filippos Porichis, Rama S Akondy, Zaza M Ndhlovu, James W Austin, Rebeka Bordi, Francesco A Procopio, Toshiyuki Miura, Todd M Allen, John Sidney, Alessandro Sette, Bruce D Walker, Rafi Ahmed, Jeremy M Boss, Rafick-Pierre Sékaly, Daniel E Kaufmann

Affiliations

Cutting edge: Prolonged exposure to HIV reinforces a poised epigenetic program for PD-1 expression in virus-specific CD8 T cells

Ben Youngblood et al. J Immunol. 2013.

Abstract

Ag-specific CD8 T cells play a critical role in controlling HIV infection but eventually lose antiviral functions in part because of expression and signaling through the inhibitory programmed death-1 (PD-1) receptor. To better understand the impact of prolonged TCR ligation on regulation of PD-1 expression in HIV-specific CD8 T cells, we investigated the capacity of virus-specific CD8 T cells to modify the PD-1 epigenetic program after reduction in viral load. We observed that the transcriptional regulatory region was unmethylated in the PD-1(hi) HIV-specific CD8 T cells, whereas it remained methylated in donor-matched naive cells at acute and chronic stages of infection. Surprisingly, the PD-1 promoter remained unmethylated in HIV-specific CD8 T cells from subjects with a viral load controlled by antiviral therapy for >2 y or from elite controllers. Together, these data demonstrate that the epigenetic program at the PD-1 locus becomes fixed after prolonged exposure to HIV virus.

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Figures

Figure 1

Figure 1. The PD-1 locus transcriptional regulatory region is demethylated in virus-specific CD8 T cells at the acute stage of HIV infection and remains unmethylated during the chronic stage of infection

A) Cartoon representation of the PD-1 transcriptional regulatory region. Gray lollipops indicate the location of CpG sites ranging between −769 and −972 base pairs from the start codon. The red arrows indicate the approximate location of the primers used for bisulfite sequencing methylation analysis. B) Representative bisulfite sequencing DNA methylation analysis. Bisulfite sequencing of the PD-1 conserved regulatory (CR) region was performed on purified (>95% purity) naïve and HIV-specific CD8 T cell genomic DNA from donors at the acute (n=2) and chronic (n=3) stages of infection. Each line represents an individual clone picked for sequencing. Filled circles = methylated cytosine. Open circles = non-methylated cytosine. CpG sites 18–26 are shown for clarity.

Figure 2

Figure 2. Reduced viremia in HAART treated donors does not result in DNA remethylation of the PD-1 locus in virus-specific CD8 T cells

A) Representative bisulfite sequencing DNA methylation analysis of naïve and HIV-specific CD8 T cells from donors pre- and post-HAART therapy. B) Longitudinal analysis of percent CpG methylation at the PD-1 regulatory region in donor matched naïve and HIV-specific CD8 T cells pre and post HAART. C) PD-1 MFI on HIV-specific CD8 T cells used for methylation studies. PD-1 MFI on tetramer+ CD8 T cells represented as a fold over PD-1 MFI on donor matched naïve CD8 T cells.

Figure 3

Figure 3. Chronic HIV infection uncouples PD-1 locus remethylation from CD8 T cell activation

A) Histogram analysis of PD-1 expression on HIV-specific CD8 T cells KK10, SL9, and IW9 (blue) relative to fluorescence minus one (red). B) Representative bisulfite sequencing DNA methylation analysis of naïve and HIV-specific CD8 T cells from elite controllers. C) PD-1 levels were measured on HIV tetramer-specific CD8 T cells (n=15) from HIV-infected subjects (n=7) with viral loads <50 copies/mL. PD-1 expression is plotted according to the autologous viral sequence of the epitopes corresponding to the tetramers used: “conserved”: autologous epitope sequence identical to the tetramer; “mutated”: autologous epitope harboring a known escape mutation. Each color corresponds to a single individual. D) Graph of average CpG methylation among all sites vs % PD-1+ expression on naïve and HIV-specific CD8 T cells. The difference in PD-1 locus DNA methylation between naïve and HIV-specific CD8 T cells is highly significant; p-value < 0.0001. Pearson analysis of PD-1 expression vs DNA methylation results in R2 values of 0.32 and 0.04 for naïve and HIV-specific CD8 T cells respectively.

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