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HCV+ hepatocytes induce human regulatory CD4+ T cells through the production of TGF-beta.

Hall CH, Kassel R, Tacke RS, Hahn YS - PLoS ONE (2010)

Bottom Line: Hepatitis C Virus (HCV) is remarkably efficient at establishing persistent infection and is associated with the development of chronic liver disease.Notably, CD4(+) T cells in contact with Huh7.5-FL expressed an increased level of the Treg markers, CD25, Foxp3, CTLA-4 and LAP, and were able to suppress the proliferation of effector T cells.These results demonstrate that HCV infected hepatocytes are capable of directly inducing Tregs development and may contribute to impaired host T cell responses.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Beirne B. Carter Center for Immunology Research, University of Virginia, Charlottesville, Virginia, USA.

ABSTRACT

Background: Hepatitis C Virus (HCV) is remarkably efficient at establishing persistent infection and is associated with the development of chronic liver disease. Impaired T cell responses facilitate and maintain persistent HCV infection. Importantly, CD4(+) regulatory T cells (Tregs) act by dampening antiviral T cell responses in HCV infection. The mechanism for induction and/or expansion of Tregs in HCV is unknown.

Methodology/principal findings: HCV-expressing hepatocytes were used to determine if hepatocytes are able to induce Tregs. The infected liver environment was modeled by establishing the co-culture of the human hepatoma cell line, Huh7.5, containing the full-length genome of HCV genotype 1a (Huh7.5-FL) with activated CD4(+) T cells. The production of IFN-gamma was diminished following co-culture with Huh7.5-FL as compared to controls. Notably, CD4(+) T cells in contact with Huh7.5-FL expressed an increased level of the Treg markers, CD25, Foxp3, CTLA-4 and LAP, and were able to suppress the proliferation of effector T cells. Importantly, HCV(+) hepatocytes upregulated the production of TGF-beta and blockade of TGF-beta abrogated Treg phenotype and function.

Conclusions/significance: These results demonstrate that HCV infected hepatocytes are capable of directly inducing Tregs development and may contribute to impaired host T cell responses.

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Related in: MedlinePlus

HCV+ hepatocytes cause immunosuppression of CD4+ T cells due to enhanced TGF-β production.A, B) Hepatocyte TGF-β production was assessed by intracellular flow cytometry (A) and by Western blot (B). Data are reproducible in 3 independent experiments. C, D) TGF-β siRNA knockdown was conducted in hepatocytes using 2 different siRNAs targeting TGF-β and a random RNA sequence not found in the human genome as a control. (C) siRNA knockdown was confirmed by intracellular flow staining of TGF-β. (D) IFN-γ production was assessed by ELISA. Data are compiled from 4 CD4+ T cell donors.
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pone-0012154-g006: HCV+ hepatocytes cause immunosuppression of CD4+ T cells due to enhanced TGF-β production.A, B) Hepatocyte TGF-β production was assessed by intracellular flow cytometry (A) and by Western blot (B). Data are reproducible in 3 independent experiments. C, D) TGF-β siRNA knockdown was conducted in hepatocytes using 2 different siRNAs targeting TGF-β and a random RNA sequence not found in the human genome as a control. (C) siRNA knockdown was confirmed by intracellular flow staining of TGF-β. (D) IFN-γ production was assessed by ELISA. Data are compiled from 4 CD4+ T cell donors.

Mentions: Given the crucial role of TGF-β in induction of Tregs and the ability of HCV core protein to induce TGF-β mRNA expression in other hepatocyte cell lines[13], [14], we next determined if the Huh7.5 cell lines were contributing TGF-β to the co-culture. Intracellular TGF-β staining confirmed that Huh7.5-FL produced more TGF-β than did Huh7.5 or Huh7.5-SG (Fig. 6A). This data was also confirmed by western blot analysis (Fig. 6B).


HCV+ hepatocytes induce human regulatory CD4+ T cells through the production of TGF-beta.

Hall CH, Kassel R, Tacke RS, Hahn YS - PLoS ONE (2010)

HCV+ hepatocytes cause immunosuppression of CD4+ T cells due to enhanced TGF-β production.A, B) Hepatocyte TGF-β production was assessed by intracellular flow cytometry (A) and by Western blot (B). Data are reproducible in 3 independent experiments. C, D) TGF-β siRNA knockdown was conducted in hepatocytes using 2 different siRNAs targeting TGF-β and a random RNA sequence not found in the human genome as a control. (C) siRNA knockdown was confirmed by intracellular flow staining of TGF-β. (D) IFN-γ production was assessed by ELISA. Data are compiled from 4 CD4+ T cell donors.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2921368&req=5

pone-0012154-g006: HCV+ hepatocytes cause immunosuppression of CD4+ T cells due to enhanced TGF-β production.A, B) Hepatocyte TGF-β production was assessed by intracellular flow cytometry (A) and by Western blot (B). Data are reproducible in 3 independent experiments. C, D) TGF-β siRNA knockdown was conducted in hepatocytes using 2 different siRNAs targeting TGF-β and a random RNA sequence not found in the human genome as a control. (C) siRNA knockdown was confirmed by intracellular flow staining of TGF-β. (D) IFN-γ production was assessed by ELISA. Data are compiled from 4 CD4+ T cell donors.
Mentions: Given the crucial role of TGF-β in induction of Tregs and the ability of HCV core protein to induce TGF-β mRNA expression in other hepatocyte cell lines[13], [14], we next determined if the Huh7.5 cell lines were contributing TGF-β to the co-culture. Intracellular TGF-β staining confirmed that Huh7.5-FL produced more TGF-β than did Huh7.5 or Huh7.5-SG (Fig. 6A). This data was also confirmed by western blot analysis (Fig. 6B).

Bottom Line: Hepatitis C Virus (HCV) is remarkably efficient at establishing persistent infection and is associated with the development of chronic liver disease.Notably, CD4(+) T cells in contact with Huh7.5-FL expressed an increased level of the Treg markers, CD25, Foxp3, CTLA-4 and LAP, and were able to suppress the proliferation of effector T cells.These results demonstrate that HCV infected hepatocytes are capable of directly inducing Tregs development and may contribute to impaired host T cell responses.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Beirne B. Carter Center for Immunology Research, University of Virginia, Charlottesville, Virginia, USA.

ABSTRACT

Background: Hepatitis C Virus (HCV) is remarkably efficient at establishing persistent infection and is associated with the development of chronic liver disease. Impaired T cell responses facilitate and maintain persistent HCV infection. Importantly, CD4(+) regulatory T cells (Tregs) act by dampening antiviral T cell responses in HCV infection. The mechanism for induction and/or expansion of Tregs in HCV is unknown.

Methodology/principal findings: HCV-expressing hepatocytes were used to determine if hepatocytes are able to induce Tregs. The infected liver environment was modeled by establishing the co-culture of the human hepatoma cell line, Huh7.5, containing the full-length genome of HCV genotype 1a (Huh7.5-FL) with activated CD4(+) T cells. The production of IFN-gamma was diminished following co-culture with Huh7.5-FL as compared to controls. Notably, CD4(+) T cells in contact with Huh7.5-FL expressed an increased level of the Treg markers, CD25, Foxp3, CTLA-4 and LAP, and were able to suppress the proliferation of effector T cells. Importantly, HCV(+) hepatocytes upregulated the production of TGF-beta and blockade of TGF-beta abrogated Treg phenotype and function.

Conclusions/significance: These results demonstrate that HCV infected hepatocytes are capable of directly inducing Tregs development and may contribute to impaired host T cell responses.

Show MeSH
Related in: MedlinePlus