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CD4 depletion in SIV-infected macaques results in macrophage and microglia infection with rapid turnover of infected cells.

Micci L, Alvarez X, Iriele RI, Ortiz AM, Ryan ES, McGary CS, Deleage C, McAtee BB, He T, Apetrei C, Easley K, Pahwa S, Collman RG, Derdeyn CA, Davenport MP, Estes JD, Silvestri G, Lackner AA, Paiardini M - PLoS Pathog. (2014)

Bottom Line: In rhesus macaques (RMs), experimental depletion of CD4+ T-cells prior to SIV infection results in higher viremia and emergence of CD4-independent SIV-envelopes.In this study we used the rhesus recombinant anti-CD4 antibody CD4R1 to deplete RM CD4+ T-cells prior to SIVmac251 infection and investigate the sources of the increased viral burden and the lifespan of productively infected cells.We believe these findings have important implications for HIV eradication studies.

View Article: PubMed Central - PubMed

Affiliation: Division of Microbiology & Immunology, Yerkes National Primate Research Center, Emory University School of Medicine, Atlanta, Georgia, United States of America.

ABSTRACT
In rhesus macaques (RMs), experimental depletion of CD4+ T-cells prior to SIV infection results in higher viremia and emergence of CD4-independent SIV-envelopes. In this study we used the rhesus recombinant anti-CD4 antibody CD4R1 to deplete RM CD4+ T-cells prior to SIVmac251 infection and investigate the sources of the increased viral burden and the lifespan of productively infected cells. CD4-depleted animals showed (i) set-point viral load two-logs higher than controls; (ii) macrophages constituting 80% of all SIV vRNA+ cells in lymph node and mucosal tissues; (iii) substantial expansion of pro-inflammatory monocytes; (iv) aberrant activation and infection of microglial cells; and (v) lifespan of productively infected cells significantly longer in comparison to controls, but markedly shorter than previously estimated for macrophages. The net effect of CD4+ T-cell depletion is an inability to control SIV replication and a shift in the tropism of infected cells to macrophages, microglia, and, potentially, other CD4-low cells which all appear to have a shortened in vivo lifespan. We believe these findings have important implications for HIV eradication studies.

No MeSH data available.


Related in: MedlinePlus

Massive SIV infection of LN and intestinal macrophages in CD4-depleted RMs.(a) Immunofluorescence staining for T cell (CD3; blue) and macrophage (CD68 and/or CD163; green) lineage markers combined with in situ hybridization for SIV vRNA (red) in the LN isolated at day 42 post-infection from one representative undepleted control (left) and one CD4-depleted RM. The vast majority of SIV vRNA+ cells express CD3 in undepleted control but express CD68/CD163 in CD4-depleted RM. (b) The same staining is shown for colon (top) and jejunum (bottom) tissues in two representative CD4-depleted animals. (c) Quantitative image analysis of LN and mucosal tissues showing the fraction of SIV vRNA+ cells that express CD3 or CD68/CD163 in CD4-depleted (n = 12; the 8 animals in this study plus the 4 in Ortiz et al 2011) or undepleted control RMs (n = 6; two SIVmac251 infected animals belonging to a different study were added as controls). (d) Relative abundance of SIV vRNA+ in productively infected T cells and macrophages, determined by measuring the volumetric sum of the SIV vRNA+ intensity integration values in situ from confocal images collected under identical laser settings, is shown in four CD4-depleted RMs. Macrophages on average have higher per cell SIV vRNA+ content compared to CD4+ T cells within the same host. Statistical analyses were determined by Mann-Whitney test.
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ppat-1004467-g004: Massive SIV infection of LN and intestinal macrophages in CD4-depleted RMs.(a) Immunofluorescence staining for T cell (CD3; blue) and macrophage (CD68 and/or CD163; green) lineage markers combined with in situ hybridization for SIV vRNA (red) in the LN isolated at day 42 post-infection from one representative undepleted control (left) and one CD4-depleted RM. The vast majority of SIV vRNA+ cells express CD3 in undepleted control but express CD68/CD163 in CD4-depleted RM. (b) The same staining is shown for colon (top) and jejunum (bottom) tissues in two representative CD4-depleted animals. (c) Quantitative image analysis of LN and mucosal tissues showing the fraction of SIV vRNA+ cells that express CD3 or CD68/CD163 in CD4-depleted (n = 12; the 8 animals in this study plus the 4 in Ortiz et al 2011) or undepleted control RMs (n = 6; two SIVmac251 infected animals belonging to a different study were added as controls). (d) Relative abundance of SIV vRNA+ in productively infected T cells and macrophages, determined by measuring the volumetric sum of the SIV vRNA+ intensity integration values in situ from confocal images collected under identical laser settings, is shown in four CD4-depleted RMs. Macrophages on average have higher per cell SIV vRNA+ content compared to CD4+ T cells within the same host. Statistical analyses were determined by Mann-Whitney test.

Mentions: We next investigated the levels of SIV infection of macrophages in peripheral lymph node and intestine from CD4-depleted and control RMs by immunofluorescence staining for cell lineage markers combined with fluorescence in situ hybridization (F-ISH) for SIV vRNA. Since monocyte/macrophage express CD4, we used CD3 to determine the infection frequency of CD4+ T-cells. At day 42 p.i. SIV vRNA+ cells were more frequent in the LN of CD4-depleted animals as compared to controls (Figure 4a), consistent with the ∼2-log higher plasma viremia found at the same experimental point. The vast majority of SIV vRNA+ cells expressed the T cell marker CD3 in undepleted controls, but macrophage markers (CD68 and/or CD163) in CD4-depleted RMs. We then performed the same F-ISH staining on day 42 rectal biopsies from the RMs included in the current study as well as on colon and jejunal tissues at necropsy from the four CD4-depleted animals included in Ortiz A.M et al[7]. In contrast to our current study, those latter animals were not ART-treated and thus showed high viremia when euthanized. The same phenomena of increased levels of total SIV vRNA+ cells and expression of macrophage markers by infected cells were observed in the intestine of CD4-depleted (Figure 4b), but not of control RMs. Quantitative image analysis of LN and intestinal tissues showed that in undepleted controls more than 80% of SIV vRNA+ cells were CD3+ T-cells, while in CD4-depleted RMs ∼80% of SIV vRNA+ cells were CD68+ and/or CD163+ macrophages (Figure 4c).


CD4 depletion in SIV-infected macaques results in macrophage and microglia infection with rapid turnover of infected cells.

Micci L, Alvarez X, Iriele RI, Ortiz AM, Ryan ES, McGary CS, Deleage C, McAtee BB, He T, Apetrei C, Easley K, Pahwa S, Collman RG, Derdeyn CA, Davenport MP, Estes JD, Silvestri G, Lackner AA, Paiardini M - PLoS Pathog. (2014)

Massive SIV infection of LN and intestinal macrophages in CD4-depleted RMs.(a) Immunofluorescence staining for T cell (CD3; blue) and macrophage (CD68 and/or CD163; green) lineage markers combined with in situ hybridization for SIV vRNA (red) in the LN isolated at day 42 post-infection from one representative undepleted control (left) and one CD4-depleted RM. The vast majority of SIV vRNA+ cells express CD3 in undepleted control but express CD68/CD163 in CD4-depleted RM. (b) The same staining is shown for colon (top) and jejunum (bottom) tissues in two representative CD4-depleted animals. (c) Quantitative image analysis of LN and mucosal tissues showing the fraction of SIV vRNA+ cells that express CD3 or CD68/CD163 in CD4-depleted (n = 12; the 8 animals in this study plus the 4 in Ortiz et al 2011) or undepleted control RMs (n = 6; two SIVmac251 infected animals belonging to a different study were added as controls). (d) Relative abundance of SIV vRNA+ in productively infected T cells and macrophages, determined by measuring the volumetric sum of the SIV vRNA+ intensity integration values in situ from confocal images collected under identical laser settings, is shown in four CD4-depleted RMs. Macrophages on average have higher per cell SIV vRNA+ content compared to CD4+ T cells within the same host. Statistical analyses were determined by Mann-Whitney test.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4214815&req=5

ppat-1004467-g004: Massive SIV infection of LN and intestinal macrophages in CD4-depleted RMs.(a) Immunofluorescence staining for T cell (CD3; blue) and macrophage (CD68 and/or CD163; green) lineage markers combined with in situ hybridization for SIV vRNA (red) in the LN isolated at day 42 post-infection from one representative undepleted control (left) and one CD4-depleted RM. The vast majority of SIV vRNA+ cells express CD3 in undepleted control but express CD68/CD163 in CD4-depleted RM. (b) The same staining is shown for colon (top) and jejunum (bottom) tissues in two representative CD4-depleted animals. (c) Quantitative image analysis of LN and mucosal tissues showing the fraction of SIV vRNA+ cells that express CD3 or CD68/CD163 in CD4-depleted (n = 12; the 8 animals in this study plus the 4 in Ortiz et al 2011) or undepleted control RMs (n = 6; two SIVmac251 infected animals belonging to a different study were added as controls). (d) Relative abundance of SIV vRNA+ in productively infected T cells and macrophages, determined by measuring the volumetric sum of the SIV vRNA+ intensity integration values in situ from confocal images collected under identical laser settings, is shown in four CD4-depleted RMs. Macrophages on average have higher per cell SIV vRNA+ content compared to CD4+ T cells within the same host. Statistical analyses were determined by Mann-Whitney test.
Mentions: We next investigated the levels of SIV infection of macrophages in peripheral lymph node and intestine from CD4-depleted and control RMs by immunofluorescence staining for cell lineage markers combined with fluorescence in situ hybridization (F-ISH) for SIV vRNA. Since monocyte/macrophage express CD4, we used CD3 to determine the infection frequency of CD4+ T-cells. At day 42 p.i. SIV vRNA+ cells were more frequent in the LN of CD4-depleted animals as compared to controls (Figure 4a), consistent with the ∼2-log higher plasma viremia found at the same experimental point. The vast majority of SIV vRNA+ cells expressed the T cell marker CD3 in undepleted controls, but macrophage markers (CD68 and/or CD163) in CD4-depleted RMs. We then performed the same F-ISH staining on day 42 rectal biopsies from the RMs included in the current study as well as on colon and jejunal tissues at necropsy from the four CD4-depleted animals included in Ortiz A.M et al[7]. In contrast to our current study, those latter animals were not ART-treated and thus showed high viremia when euthanized. The same phenomena of increased levels of total SIV vRNA+ cells and expression of macrophage markers by infected cells were observed in the intestine of CD4-depleted (Figure 4b), but not of control RMs. Quantitative image analysis of LN and intestinal tissues showed that in undepleted controls more than 80% of SIV vRNA+ cells were CD3+ T-cells, while in CD4-depleted RMs ∼80% of SIV vRNA+ cells were CD68+ and/or CD163+ macrophages (Figure 4c).

Bottom Line: In rhesus macaques (RMs), experimental depletion of CD4+ T-cells prior to SIV infection results in higher viremia and emergence of CD4-independent SIV-envelopes.In this study we used the rhesus recombinant anti-CD4 antibody CD4R1 to deplete RM CD4+ T-cells prior to SIVmac251 infection and investigate the sources of the increased viral burden and the lifespan of productively infected cells.We believe these findings have important implications for HIV eradication studies.

View Article: PubMed Central - PubMed

Affiliation: Division of Microbiology & Immunology, Yerkes National Primate Research Center, Emory University School of Medicine, Atlanta, Georgia, United States of America.

ABSTRACT
In rhesus macaques (RMs), experimental depletion of CD4+ T-cells prior to SIV infection results in higher viremia and emergence of CD4-independent SIV-envelopes. In this study we used the rhesus recombinant anti-CD4 antibody CD4R1 to deplete RM CD4+ T-cells prior to SIVmac251 infection and investigate the sources of the increased viral burden and the lifespan of productively infected cells. CD4-depleted animals showed (i) set-point viral load two-logs higher than controls; (ii) macrophages constituting 80% of all SIV vRNA+ cells in lymph node and mucosal tissues; (iii) substantial expansion of pro-inflammatory monocytes; (iv) aberrant activation and infection of microglial cells; and (v) lifespan of productively infected cells significantly longer in comparison to controls, but markedly shorter than previously estimated for macrophages. The net effect of CD4+ T-cell depletion is an inability to control SIV replication and a shift in the tropism of infected cells to macrophages, microglia, and, potentially, other CD4-low cells which all appear to have a shortened in vivo lifespan. We believe these findings have important implications for HIV eradication studies.

No MeSH data available.


Related in: MedlinePlus