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HTLV-1 modulates the frequency and phenotype of FoxP3+CD4+ T cells in virus-infected individuals.

Satou Y, Utsunomiya A, Tanabe J, Nakagawa M, Nosaka K, Matsuoka M - Retrovirology (2012)

Bottom Line: We conclude that FoxP3+ T- cells are disproportionately infected with HTLV-1 during chronic infection.The expression levels of the Treg associated molecules CTLA-4 and GITR were decreased in CD4+FoxP3+ T cells.Finally, we analyzed ATL cells and observed not only a high frequency of FoxP3 expression but also wide variation in FoxP3 expression level among individual cases.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory of Virus Control, Institute for Virus Research, Kyoto University, Kyoto, 606-8507, Japan. y.satou@imperial.ac.uk

ABSTRACT

Background: HTLV-1 utilizes CD4 T cells as the main host cell and maintains the proviral load via clonal proliferation of infected CD4+ T cells. Infection of CD4+ T cells by HTLV-1 is therefore thought to play a pivotal role in HTLV-1-related pathogenicity, including leukemia/lymphoma of CD4+ T cells and chronic inflammatory diseases. Recently, it has been reported that a proportion of HTLV-1 infected CD4+ T cells express FoxP3, a master molecule of regulatory T cells. However, crucial questions remain unanswered on the relationship between HTLV-1 infection and FoxP3 expression.

Results: To investigate the effect of HTLV-1 infection on CD4+ T-cell subsets, we used flow cytometry to analyze the T-cell phenotype and HTLV-1 infection in peripheral mononuclear cells (PBMCs) of four groups of subjects, including 23 HTLV-1-infected asymptomatic carriers (AC), 10 patients with HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP), 10 patients with adult T-cell leukemia (ATL), and 10 healthy donors. The frequency of FoxP3+ cells in CD4+ T cells in AC with high proviral load and patients with HAM/TSP or ATL was higher than that in uninfected individuals. The proviral load was positively correlated with the percentage of CD4+ T cells that were FoxP3+. The CD4+FoxP3+ T cells, themselves, were frequently infected with HTLV-1. We conclude that FoxP3+ T- cells are disproportionately infected with HTLV-1 during chronic infection. We next focused on PBMCs of HAM/TSP patients. The expression levels of the Treg associated molecules CTLA-4 and GITR were decreased in CD4+FoxP3+ T cells. Further we characterized FoxP3+CD4+ T-cell subsets by staining CD45RA and FoxP3, which revealed an increase in CD45RA-FoxP3low non-suppressive T-cells. These findings can reconcile the inflammatory phenotype of HAM/TSP with the observed increase in frequency of FoxP3+ cells. Finally, we analyzed ATL cells and observed not only a high frequency of FoxP3 expression but also wide variation in FoxP3 expression level among individual cases.

Conclusions: HTLV-1 infection induces an abnormal frequency and phenotype of FoxP3+CD4+ T cells.

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Frequency of HTLV-1-infection in each CD4+T-cell subset of asymptomatic HTLV-1 carriers. PBMCs from HTLV-1 asymptomatic carriers (n = 23) were cultivated for 18 hours, stained with anti-CD4, anti-CD8, anti-FoxP3, and anti-Tax antibodies, and analyzed by flow cytometry. (A) Representative dot plots of CD4 and CD8 and histograms of Tax in CD4+ or CD8+ T cells (Left panel). Right, cumulative results from 23 AC individuals are shown in graph (Right panel). (B) Representative histograms of Tax expression in FoxP3+ or FoxP3− cell (Left panel). Right, cumulative results from 23 AC individuals are shown in graph (Right panel). (C) Tax positivity in CD4+ T cells showed significant correlation with FoxP3 positivity in CD4+ T cells by Spearman’s rank correlation (P = 0.0257, r = 0.48)
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Figure 3: Frequency of HTLV-1-infection in each CD4+T-cell subset of asymptomatic HTLV-1 carriers. PBMCs from HTLV-1 asymptomatic carriers (n = 23) were cultivated for 18 hours, stained with anti-CD4, anti-CD8, anti-FoxP3, and anti-Tax antibodies, and analyzed by flow cytometry. (A) Representative dot plots of CD4 and CD8 and histograms of Tax in CD4+ or CD8+ T cells (Left panel). Right, cumulative results from 23 AC individuals are shown in graph (Right panel). (B) Representative histograms of Tax expression in FoxP3+ or FoxP3− cell (Left panel). Right, cumulative results from 23 AC individuals are shown in graph (Right panel). (C) Tax positivity in CD4+ T cells showed significant correlation with FoxP3 positivity in CD4+ T cells by Spearman’s rank correlation (P = 0.0257, r = 0.48)

Mentions: We next investigated which T-cell subset is frequently infected with HTLV-1. We cultivated PBMCs isolated from HTLV-1 infected individuals ex vivo for 12–18 hours and stained with antibodies to Tax and various T-cell subset markers such as CD4, CD8, and FoxP3. Consistent with the previous reports, the frequency of Tax positivity in CD4+ T cells was much higher than that in CD8+ T cells (p < 0.0001, Figure 3A). Among CD4+ T cells, the FoxP3 positive cell population contained a significantly higher ratio of Tax positive cells than that in FoxP3 negative cells (p < 0.0001, Figure 3B). In line with the finding in Figure 1E, the frequencies of FoxP3+ cells were significantly correlated with Tax positivity in CD4+ T cells. (r = 0.48, p = 0.0257, Figure 3C). These results indicated that the increased FoxP3+ cells in HTLV-1-infected individuals were frequently infected with HTLV-1.


HTLV-1 modulates the frequency and phenotype of FoxP3+CD4+ T cells in virus-infected individuals.

Satou Y, Utsunomiya A, Tanabe J, Nakagawa M, Nosaka K, Matsuoka M - Retrovirology (2012)

Frequency of HTLV-1-infection in each CD4+T-cell subset of asymptomatic HTLV-1 carriers. PBMCs from HTLV-1 asymptomatic carriers (n = 23) were cultivated for 18 hours, stained with anti-CD4, anti-CD8, anti-FoxP3, and anti-Tax antibodies, and analyzed by flow cytometry. (A) Representative dot plots of CD4 and CD8 and histograms of Tax in CD4+ or CD8+ T cells (Left panel). Right, cumulative results from 23 AC individuals are shown in graph (Right panel). (B) Representative histograms of Tax expression in FoxP3+ or FoxP3− cell (Left panel). Right, cumulative results from 23 AC individuals are shown in graph (Right panel). (C) Tax positivity in CD4+ T cells showed significant correlation with FoxP3 positivity in CD4+ T cells by Spearman’s rank correlation (P = 0.0257, r = 0.48)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3403885&req=5

Figure 3: Frequency of HTLV-1-infection in each CD4+T-cell subset of asymptomatic HTLV-1 carriers. PBMCs from HTLV-1 asymptomatic carriers (n = 23) were cultivated for 18 hours, stained with anti-CD4, anti-CD8, anti-FoxP3, and anti-Tax antibodies, and analyzed by flow cytometry. (A) Representative dot plots of CD4 and CD8 and histograms of Tax in CD4+ or CD8+ T cells (Left panel). Right, cumulative results from 23 AC individuals are shown in graph (Right panel). (B) Representative histograms of Tax expression in FoxP3+ or FoxP3− cell (Left panel). Right, cumulative results from 23 AC individuals are shown in graph (Right panel). (C) Tax positivity in CD4+ T cells showed significant correlation with FoxP3 positivity in CD4+ T cells by Spearman’s rank correlation (P = 0.0257, r = 0.48)
Mentions: We next investigated which T-cell subset is frequently infected with HTLV-1. We cultivated PBMCs isolated from HTLV-1 infected individuals ex vivo for 12–18 hours and stained with antibodies to Tax and various T-cell subset markers such as CD4, CD8, and FoxP3. Consistent with the previous reports, the frequency of Tax positivity in CD4+ T cells was much higher than that in CD8+ T cells (p < 0.0001, Figure 3A). Among CD4+ T cells, the FoxP3 positive cell population contained a significantly higher ratio of Tax positive cells than that in FoxP3 negative cells (p < 0.0001, Figure 3B). In line with the finding in Figure 1E, the frequencies of FoxP3+ cells were significantly correlated with Tax positivity in CD4+ T cells. (r = 0.48, p = 0.0257, Figure 3C). These results indicated that the increased FoxP3+ cells in HTLV-1-infected individuals were frequently infected with HTLV-1.

Bottom Line: We conclude that FoxP3+ T- cells are disproportionately infected with HTLV-1 during chronic infection.The expression levels of the Treg associated molecules CTLA-4 and GITR were decreased in CD4+FoxP3+ T cells.Finally, we analyzed ATL cells and observed not only a high frequency of FoxP3 expression but also wide variation in FoxP3 expression level among individual cases.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory of Virus Control, Institute for Virus Research, Kyoto University, Kyoto, 606-8507, Japan. y.satou@imperial.ac.uk

ABSTRACT

Background: HTLV-1 utilizes CD4 T cells as the main host cell and maintains the proviral load via clonal proliferation of infected CD4+ T cells. Infection of CD4+ T cells by HTLV-1 is therefore thought to play a pivotal role in HTLV-1-related pathogenicity, including leukemia/lymphoma of CD4+ T cells and chronic inflammatory diseases. Recently, it has been reported that a proportion of HTLV-1 infected CD4+ T cells express FoxP3, a master molecule of regulatory T cells. However, crucial questions remain unanswered on the relationship between HTLV-1 infection and FoxP3 expression.

Results: To investigate the effect of HTLV-1 infection on CD4+ T-cell subsets, we used flow cytometry to analyze the T-cell phenotype and HTLV-1 infection in peripheral mononuclear cells (PBMCs) of four groups of subjects, including 23 HTLV-1-infected asymptomatic carriers (AC), 10 patients with HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP), 10 patients with adult T-cell leukemia (ATL), and 10 healthy donors. The frequency of FoxP3+ cells in CD4+ T cells in AC with high proviral load and patients with HAM/TSP or ATL was higher than that in uninfected individuals. The proviral load was positively correlated with the percentage of CD4+ T cells that were FoxP3+. The CD4+FoxP3+ T cells, themselves, were frequently infected with HTLV-1. We conclude that FoxP3+ T- cells are disproportionately infected with HTLV-1 during chronic infection. We next focused on PBMCs of HAM/TSP patients. The expression levels of the Treg associated molecules CTLA-4 and GITR were decreased in CD4+FoxP3+ T cells. Further we characterized FoxP3+CD4+ T-cell subsets by staining CD45RA and FoxP3, which revealed an increase in CD45RA-FoxP3low non-suppressive T-cells. These findings can reconcile the inflammatory phenotype of HAM/TSP with the observed increase in frequency of FoxP3+ cells. Finally, we analyzed ATL cells and observed not only a high frequency of FoxP3 expression but also wide variation in FoxP3 expression level among individual cases.

Conclusions: HTLV-1 infection induces an abnormal frequency and phenotype of FoxP3+CD4+ T cells.

Show MeSH
Related in: MedlinePlus