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Dysregulated Tim-3 expression on natural killer cells is associated with increased Galectin-9 levels in HIV-1 infection.

Jost S, Moreno-Nieves UY, Garcia-Beltran WF, Rands K, Reardon J, Toth I, Piechocka-Trocha A, Altfeld M, Addo MM - Retrovirology (2013)

Bottom Line: Natural killer (NK) cells constitutively express high levels of Tim-3, an immunoregulatory molecule recently proposed to be a marker for mature and functional NK cells.Plasma concentrations of Gal-9 were higher in HIV-1-infected individuals than in healthy individuals.In vitro, Gal-9 triggered Tim-3 downregulation on NK cells as well as NK cell activation.

View Article: PubMed Central - HTML - PubMed

Affiliation: Ragon Institute of MGH, MIT and Harvard, 400 Technology Square, Cambridge, MA 02139, USA.

ABSTRACT

Background: Natural killer (NK) cells constitutively express high levels of Tim-3, an immunoregulatory molecule recently proposed to be a marker for mature and functional NK cells. Whether HIV-1 infection modulates the expression of Tim-3 on NK cells, or the levels of its ligand Galectin-9 (Gal-9), and how signaling through these molecules affects the NK cell response to HIV-1 remains inadequately understood.

Results: We analyzed Tim-3 and Gal-9 expression in a cohort of 85 individuals with early and chronic HIV-1 infection, and in 13 HIV-1 seronegative control subjects. HIV-1 infection was associated with reduced expression of Tim-3 on NK cells, which was normalized by HAART. Plasma concentrations of Gal-9 were higher in HIV-1-infected individuals than in healthy individuals. Interestingly, Gal-9 expression in immune cells was significantly elevated in early infection, with monocytes and dendritic cells displaying the highest expression levels, which correlated with HIV-1 viral loads. In vitro, Gal-9 triggered Tim-3 downregulation on NK cells as well as NK cell activation.

Conclusions: Our data suggest that high expression levels of Gal-9 during early HIV-1 infection can lead to enhanced NK cell activity, possibly allowing for improved early control of HIV-1. In contrast, persistent Gal-9 production might impair Tim-3 activity and contribute to NK cell dysfunction in chronic HIV-1 infection.

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Expression of galectin-9 in PBMCs is increased in early HIV-1 infection and correlates with HIV-1 viremia. Flow cytometry gating strategy to analyze intracellular expression of Gal-9 on (A) CD4+ and CD8+ T cells and (B) pDCs, monocytes or mDCs. Gates are set to exclude dead cells (viability marker+), and expression of Gal-9 on various lymphocyte subsets is defined by using appropriate fluorescence-minus-one controls. (C) Dot plots display the MFI of intracellular Gal-9 in the indicated immune cell subsets from 9 healthy (HIV-) and 5 untreated subjects with early infection as determined by flow cytometry. Horizontal lines indicate the median percentages. Differences where p < 0.05 are indicated. Histogram overlays display representative examples of intracellular Gal-9 expression in each lymphocyte subset analyzed in healthy controls (tinted) and in individuals with early HIV-1 infection (transparent) compared to the FMO (dotted line). PHI, early HIV-1 infection (D) Correlations between the logarithmic viral load and the MFI of intracellular Gal-9 in CD4 + T cells, CD8+ T cells, NK cells, monocytes, mDCS and pDCs from a subset of 32 HIV-1-positive individuals, including 4 subjects with early infection, 6 viremic controllers, 6 elite controllers, 9 subjects with chronic untreated, and 7 with chronic treated HIV-1 infection.
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Figure 3: Expression of galectin-9 in PBMCs is increased in early HIV-1 infection and correlates with HIV-1 viremia. Flow cytometry gating strategy to analyze intracellular expression of Gal-9 on (A) CD4+ and CD8+ T cells and (B) pDCs, monocytes or mDCs. Gates are set to exclude dead cells (viability marker+), and expression of Gal-9 on various lymphocyte subsets is defined by using appropriate fluorescence-minus-one controls. (C) Dot plots display the MFI of intracellular Gal-9 in the indicated immune cell subsets from 9 healthy (HIV-) and 5 untreated subjects with early infection as determined by flow cytometry. Horizontal lines indicate the median percentages. Differences where p < 0.05 are indicated. Histogram overlays display representative examples of intracellular Gal-9 expression in each lymphocyte subset analyzed in healthy controls (tinted) and in individuals with early HIV-1 infection (transparent) compared to the FMO (dotted line). PHI, early HIV-1 infection (D) Correlations between the logarithmic viral load and the MFI of intracellular Gal-9 in CD4 + T cells, CD8+ T cells, NK cells, monocytes, mDCS and pDCs from a subset of 32 HIV-1-positive individuals, including 4 subjects with early infection, 6 viremic controllers, 6 elite controllers, 9 subjects with chronic untreated, and 7 with chronic treated HIV-1 infection.

Mentions: Gal-9 is produced by a wide range of epithelial and immune cells[29]. In order to identify the predominant source of cellular Gal-9, we assessed its intracellular levels by flow cytometry in different immune cell subsets, including CD4+ and CD8+ T lymphocytes, NK cells, monocytes, myeloid and plasmacytoid dendritic cells (mDCs and pDCs, respectively) in a subset of 32 HIV-positive and 9 HIV negative controls (Figure 3A and B). In healthy individuals, Gal-9 trended to have higher intracellular expression in monocytes and DCs than in the other lymphocyte subsets examined (Figure 3C). However, in individuals with early HIV-1 infection, intracellular Gal-9 levels were significantly upregulated in all analyzed peripheral blood mononuclear cells (PBMCs), with monocytes and DCs displaying the highest expression levels. In contrast, intracellular Gal-9 levels in immune cells from subjects with chronic HIV-1 infection were similar to those in healthy individuals (data not shown). In line with the correlation observed between plasma Gal-9 levels and viral load, intracellular levels of Gal-9 in CD4+ T cells, CD8+ T cells, NK cells, monocytes, and mDCs all positively correlated with viral load in subjects with HIV-1 infection (Figure 3D). This association was maintained even after exclusion of elite controllers from the analysis (data not shown). Thus, levels of the soluble form of Gal-9 were overall increased in the plasma of HIV-1-infected individuals, specifically during the early phase of HIV-1 infection, coinciding with the early upregulation of Gal-9 in all PBMC subsets analyzed. Cellular expression levels of Gal-9 also correlated with the aforementioned parameters of disease progression.


Dysregulated Tim-3 expression on natural killer cells is associated with increased Galectin-9 levels in HIV-1 infection.

Jost S, Moreno-Nieves UY, Garcia-Beltran WF, Rands K, Reardon J, Toth I, Piechocka-Trocha A, Altfeld M, Addo MM - Retrovirology (2013)

Expression of galectin-9 in PBMCs is increased in early HIV-1 infection and correlates with HIV-1 viremia. Flow cytometry gating strategy to analyze intracellular expression of Gal-9 on (A) CD4+ and CD8+ T cells and (B) pDCs, monocytes or mDCs. Gates are set to exclude dead cells (viability marker+), and expression of Gal-9 on various lymphocyte subsets is defined by using appropriate fluorescence-minus-one controls. (C) Dot plots display the MFI of intracellular Gal-9 in the indicated immune cell subsets from 9 healthy (HIV-) and 5 untreated subjects with early infection as determined by flow cytometry. Horizontal lines indicate the median percentages. Differences where p < 0.05 are indicated. Histogram overlays display representative examples of intracellular Gal-9 expression in each lymphocyte subset analyzed in healthy controls (tinted) and in individuals with early HIV-1 infection (transparent) compared to the FMO (dotted line). PHI, early HIV-1 infection (D) Correlations between the logarithmic viral load and the MFI of intracellular Gal-9 in CD4 + T cells, CD8+ T cells, NK cells, monocytes, mDCS and pDCs from a subset of 32 HIV-1-positive individuals, including 4 subjects with early infection, 6 viremic controllers, 6 elite controllers, 9 subjects with chronic untreated, and 7 with chronic treated HIV-1 infection.
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Show All Figures
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Figure 3: Expression of galectin-9 in PBMCs is increased in early HIV-1 infection and correlates with HIV-1 viremia. Flow cytometry gating strategy to analyze intracellular expression of Gal-9 on (A) CD4+ and CD8+ T cells and (B) pDCs, monocytes or mDCs. Gates are set to exclude dead cells (viability marker+), and expression of Gal-9 on various lymphocyte subsets is defined by using appropriate fluorescence-minus-one controls. (C) Dot plots display the MFI of intracellular Gal-9 in the indicated immune cell subsets from 9 healthy (HIV-) and 5 untreated subjects with early infection as determined by flow cytometry. Horizontal lines indicate the median percentages. Differences where p < 0.05 are indicated. Histogram overlays display representative examples of intracellular Gal-9 expression in each lymphocyte subset analyzed in healthy controls (tinted) and in individuals with early HIV-1 infection (transparent) compared to the FMO (dotted line). PHI, early HIV-1 infection (D) Correlations between the logarithmic viral load and the MFI of intracellular Gal-9 in CD4 + T cells, CD8+ T cells, NK cells, monocytes, mDCS and pDCs from a subset of 32 HIV-1-positive individuals, including 4 subjects with early infection, 6 viremic controllers, 6 elite controllers, 9 subjects with chronic untreated, and 7 with chronic treated HIV-1 infection.
Mentions: Gal-9 is produced by a wide range of epithelial and immune cells[29]. In order to identify the predominant source of cellular Gal-9, we assessed its intracellular levels by flow cytometry in different immune cell subsets, including CD4+ and CD8+ T lymphocytes, NK cells, monocytes, myeloid and plasmacytoid dendritic cells (mDCs and pDCs, respectively) in a subset of 32 HIV-positive and 9 HIV negative controls (Figure 3A and B). In healthy individuals, Gal-9 trended to have higher intracellular expression in monocytes and DCs than in the other lymphocyte subsets examined (Figure 3C). However, in individuals with early HIV-1 infection, intracellular Gal-9 levels were significantly upregulated in all analyzed peripheral blood mononuclear cells (PBMCs), with monocytes and DCs displaying the highest expression levels. In contrast, intracellular Gal-9 levels in immune cells from subjects with chronic HIV-1 infection were similar to those in healthy individuals (data not shown). In line with the correlation observed between plasma Gal-9 levels and viral load, intracellular levels of Gal-9 in CD4+ T cells, CD8+ T cells, NK cells, monocytes, and mDCs all positively correlated with viral load in subjects with HIV-1 infection (Figure 3D). This association was maintained even after exclusion of elite controllers from the analysis (data not shown). Thus, levels of the soluble form of Gal-9 were overall increased in the plasma of HIV-1-infected individuals, specifically during the early phase of HIV-1 infection, coinciding with the early upregulation of Gal-9 in all PBMC subsets analyzed. Cellular expression levels of Gal-9 also correlated with the aforementioned parameters of disease progression.

Bottom Line: Natural killer (NK) cells constitutively express high levels of Tim-3, an immunoregulatory molecule recently proposed to be a marker for mature and functional NK cells.Plasma concentrations of Gal-9 were higher in HIV-1-infected individuals than in healthy individuals.In vitro, Gal-9 triggered Tim-3 downregulation on NK cells as well as NK cell activation.

View Article: PubMed Central - HTML - PubMed

Affiliation: Ragon Institute of MGH, MIT and Harvard, 400 Technology Square, Cambridge, MA 02139, USA.

ABSTRACT

Background: Natural killer (NK) cells constitutively express high levels of Tim-3, an immunoregulatory molecule recently proposed to be a marker for mature and functional NK cells. Whether HIV-1 infection modulates the expression of Tim-3 on NK cells, or the levels of its ligand Galectin-9 (Gal-9), and how signaling through these molecules affects the NK cell response to HIV-1 remains inadequately understood.

Results: We analyzed Tim-3 and Gal-9 expression in a cohort of 85 individuals with early and chronic HIV-1 infection, and in 13 HIV-1 seronegative control subjects. HIV-1 infection was associated with reduced expression of Tim-3 on NK cells, which was normalized by HAART. Plasma concentrations of Gal-9 were higher in HIV-1-infected individuals than in healthy individuals. Interestingly, Gal-9 expression in immune cells was significantly elevated in early infection, with monocytes and dendritic cells displaying the highest expression levels, which correlated with HIV-1 viral loads. In vitro, Gal-9 triggered Tim-3 downregulation on NK cells as well as NK cell activation.

Conclusions: Our data suggest that high expression levels of Gal-9 during early HIV-1 infection can lead to enhanced NK cell activity, possibly allowing for improved early control of HIV-1. In contrast, persistent Gal-9 production might impair Tim-3 activity and contribute to NK cell dysfunction in chronic HIV-1 infection.

Show MeSH
Related in: MedlinePlus