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Characterization of HCV interactions with Toll-like receptors and RIG-I in liver cells.

Eksioglu EA, Zhu H, Bayouth L, Bess J, Liu HY, Nelson DR, Liu C - PLoS ONE (2011)

Bottom Line: We found that innate immunity against HCV is associated with the induction of apoptosis by RIG-I through the TRAIL pathway and the establishment of an antiviral state by TLR3.These findings correlate with the lower expression level of PRRs in HCV chronic patients and highlight the importance of the PRRs in the initial interaction of the virus and its host cells.This work represents a novel mechanism of viral pathogenesis for HCV and demonstrates the role of PRRs in viral infection.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Immunology and Laboratory Medicine, University of Florida College of Medicine, Gainesville, Florida, United States of America.

ABSTRACT

Background and aim: The aim of this study was to examine the mechanisms of IFN induction and viral escape. In order to accomplish the goal we compared our new hepatoma cell line LH86, which has intact TLR3 and RIG-I expression and responds to HCV by inducing IFN, with Huh7.5 cells which lack those features.

Methods: The initial interaction of LH86 cells, Huh7.5 cells or their transfected counter parts (LH86 siRIG-I, siTLR3 or siTLR7 and Huh7.5 RIG-I, TLR3 or TLR7) after infection with HCV (strain JFH-1) was studied by measuring the expression levels of IFNβ, TRAIL, DR4, DR5 and their correlation to viral replication.

Results: HCV replicating RNA induces IFN in LH86 cells. The IFN induction system is functional in LH86, and the expression of the RIG-I and TLR3 in LH86 is comparable to the primary hepatocytes. Both proteins appear to play important roles in suppression of viral replication. We found that innate immunity against HCV is associated with the induction of apoptosis by RIG-I through the TRAIL pathway and the establishment of an antiviral state by TLR3. HCV envelope proteins interfere with the expression of TLR3 and RIG-I.

Conclusion: These findings correlate with the lower expression level of PRRs in HCV chronic patients and highlight the importance of the PRRs in the initial interaction of the virus and its host cells. This work represents a novel mechanism of viral pathogenesis for HCV and demonstrates the role of PRRs in viral infection.

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Related in: MedlinePlus

The expression of TLR3 and RIG-I is affected by intact virion proteins in hepatocytes A) IFNβ mRNA expression in Huh7.5 TLR3 or TLR7 stable cell lines co-transfected with either PKR or RIG-I after infection with HCV MOI = 0.1. Expression was calculated by the ΔΔCt method where uninfected cells were the experimental control and the housekeeping gene GAPDH was the internal control. Error bars represent the SEM of three separate experiments. B) TLR3 and RIG-I mRNA expression levels 7 days after infection with different HCV dilutions (methodology as in figure 1C). C) TLR3 and RIG-I gene expression levels 7 days after infection with normal, heated or UV-treated virus calculated as described in part A.
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pone-0021186-g005: The expression of TLR3 and RIG-I is affected by intact virion proteins in hepatocytes A) IFNβ mRNA expression in Huh7.5 TLR3 or TLR7 stable cell lines co-transfected with either PKR or RIG-I after infection with HCV MOI = 0.1. Expression was calculated by the ΔΔCt method where uninfected cells were the experimental control and the housekeeping gene GAPDH was the internal control. Error bars represent the SEM of three separate experiments. B) TLR3 and RIG-I mRNA expression levels 7 days after infection with different HCV dilutions (methodology as in figure 1C). C) TLR3 and RIG-I gene expression levels 7 days after infection with normal, heated or UV-treated virus calculated as described in part A.

Mentions: Since TLR3 and RIG-I have different functions, we hypothesized that their combined activation could lead to viral clearance. To test this hypothesis, we co-transfected the Huh7.5 TLR3 and TLR7 stable cell lines with RIG-I. We also did co-transfections of TLR3 and TLR7 cells with PKR, a different cytosolic receptor. While TLR7 did synergize with RIG-I to induce a strong IFN response, the TLR3/RIG-I combination did not show this effect. In these cells, contrary to our hypothesis, HCV infection down regulated IFN (Figure 5A). Furthermore, these effects are specific to TLR/RIG-I co-expressions in HCV infection since co-transfecting with PKR did not synergize or disrupt the IFN normally induced by either cell.


Characterization of HCV interactions with Toll-like receptors and RIG-I in liver cells.

Eksioglu EA, Zhu H, Bayouth L, Bess J, Liu HY, Nelson DR, Liu C - PLoS ONE (2011)

The expression of TLR3 and RIG-I is affected by intact virion proteins in hepatocytes A) IFNβ mRNA expression in Huh7.5 TLR3 or TLR7 stable cell lines co-transfected with either PKR or RIG-I after infection with HCV MOI = 0.1. Expression was calculated by the ΔΔCt method where uninfected cells were the experimental control and the housekeeping gene GAPDH was the internal control. Error bars represent the SEM of three separate experiments. B) TLR3 and RIG-I mRNA expression levels 7 days after infection with different HCV dilutions (methodology as in figure 1C). C) TLR3 and RIG-I gene expression levels 7 days after infection with normal, heated or UV-treated virus calculated as described in part A.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3117876&req=5

pone-0021186-g005: The expression of TLR3 and RIG-I is affected by intact virion proteins in hepatocytes A) IFNβ mRNA expression in Huh7.5 TLR3 or TLR7 stable cell lines co-transfected with either PKR or RIG-I after infection with HCV MOI = 0.1. Expression was calculated by the ΔΔCt method where uninfected cells were the experimental control and the housekeeping gene GAPDH was the internal control. Error bars represent the SEM of three separate experiments. B) TLR3 and RIG-I mRNA expression levels 7 days after infection with different HCV dilutions (methodology as in figure 1C). C) TLR3 and RIG-I gene expression levels 7 days after infection with normal, heated or UV-treated virus calculated as described in part A.
Mentions: Since TLR3 and RIG-I have different functions, we hypothesized that their combined activation could lead to viral clearance. To test this hypothesis, we co-transfected the Huh7.5 TLR3 and TLR7 stable cell lines with RIG-I. We also did co-transfections of TLR3 and TLR7 cells with PKR, a different cytosolic receptor. While TLR7 did synergize with RIG-I to induce a strong IFN response, the TLR3/RIG-I combination did not show this effect. In these cells, contrary to our hypothesis, HCV infection down regulated IFN (Figure 5A). Furthermore, these effects are specific to TLR/RIG-I co-expressions in HCV infection since co-transfecting with PKR did not synergize or disrupt the IFN normally induced by either cell.

Bottom Line: We found that innate immunity against HCV is associated with the induction of apoptosis by RIG-I through the TRAIL pathway and the establishment of an antiviral state by TLR3.These findings correlate with the lower expression level of PRRs in HCV chronic patients and highlight the importance of the PRRs in the initial interaction of the virus and its host cells.This work represents a novel mechanism of viral pathogenesis for HCV and demonstrates the role of PRRs in viral infection.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Immunology and Laboratory Medicine, University of Florida College of Medicine, Gainesville, Florida, United States of America.

ABSTRACT

Background and aim: The aim of this study was to examine the mechanisms of IFN induction and viral escape. In order to accomplish the goal we compared our new hepatoma cell line LH86, which has intact TLR3 and RIG-I expression and responds to HCV by inducing IFN, with Huh7.5 cells which lack those features.

Methods: The initial interaction of LH86 cells, Huh7.5 cells or their transfected counter parts (LH86 siRIG-I, siTLR3 or siTLR7 and Huh7.5 RIG-I, TLR3 or TLR7) after infection with HCV (strain JFH-1) was studied by measuring the expression levels of IFNβ, TRAIL, DR4, DR5 and their correlation to viral replication.

Results: HCV replicating RNA induces IFN in LH86 cells. The IFN induction system is functional in LH86, and the expression of the RIG-I and TLR3 in LH86 is comparable to the primary hepatocytes. Both proteins appear to play important roles in suppression of viral replication. We found that innate immunity against HCV is associated with the induction of apoptosis by RIG-I through the TRAIL pathway and the establishment of an antiviral state by TLR3. HCV envelope proteins interfere with the expression of TLR3 and RIG-I.

Conclusion: These findings correlate with the lower expression level of PRRs in HCV chronic patients and highlight the importance of the PRRs in the initial interaction of the virus and its host cells. This work represents a novel mechanism of viral pathogenesis for HCV and demonstrates the role of PRRs in viral infection.

Show MeSH
Related in: MedlinePlus