Limits...
Lipoprotein lipase inhibits hepatitis C virus (HCV) infection by blocking virus cell entry.

Maillard P, Walic M, Meuleman P, Roohvand F, Huby T, Le Goff W, Leroux-Roels G, Pécheur EI, Budkowska A - PLoS ONE (2011)

Bottom Line: The effect of LPL depended on its enzymatic activity.These analyses demonstrated the internalization of virus particles into hepatoma cells and their presence in intracellular vesicles and associated with lipid droplets.HCV-associated lipoproteins may therefore be a promising target for the development of new therapeutic approaches.

View Article: PubMed Central - PubMed

Affiliation: Institut Pasteur, Unité Hépacivirus et Immunité Innée, Département de Virologie, Paris, France.

ABSTRACT
A distinctive feature of HCV is that its life cycle depends on lipoprotein metabolism. Viral morphogenesis and secretion follow the very low-density lipoprotein (VLDL) biogenesis pathway and, consequently, infectious HCV in the serum is associated with triglyceride-rich lipoproteins (TRL). Lipoprotein lipase (LPL) hydrolyzes TRL within chylomicrons and VLDL but, independently of its catalytic activity, it has a bridging activity, mediating the hepatic uptake of chylomicrons and VLDL remnants. We previously showed that exogenously added LPL increases HCV binding to hepatoma cells by acting as a bridge between virus-associated lipoproteins and cell surface heparan sulfate, while simultaneously decreasing infection levels. We show here that LPL efficiently inhibits cell infection with two HCV strains produced in hepatoma cells or in primary human hepatocytes transplanted into uPA-SCID mice with fully functional human ApoB-lipoprotein profiles. Viruses produced in vitro or in vivo were separated on iodixanol gradients into low and higher density populations, and the infection of Huh 7.5 cells by both virus populations was inhibited by LPL. The effect of LPL depended on its enzymatic activity. However, the lipase inhibitor tetrahydrolipstatin restored only a minor part of HCV infectivity, suggesting an important role of the LPL bridging function in the inhibition of infection. We followed HCV cell entry by immunoelectron microscopy with anti-envelope and anti-core antibodies. These analyses demonstrated the internalization of virus particles into hepatoma cells and their presence in intracellular vesicles and associated with lipid droplets. In the presence of LPL, HCV was retained at the cell surface. We conclude that LPL efficiently inhibits HCV infection by acting on TRL associated with HCV particles through mechanisms involving its lipolytic function, but mostly its bridging function. These mechanisms lead to immobilization of the virus at the cell surface. HCV-associated lipoproteins may therefore be a promising target for the development of new therapeutic approaches.

Show MeSH

Related in: MedlinePlus

Cell infection with low- and high-density virus populations from iodixanol gradients in the presence or absence of LPL.The pooled peak fractions of the low- and high-density virus populations obtained after centrifugation through iodixanol gradients of JFH1 grown in cell culture (A) and serum samples from the m-JFH1 chimeric mouse model (B) (both gradients are shown in Figure 2) were used to infect cells in the presence or absence of 1 µg/ml LPL, as described in the Materials and Methods section. Cells were grown for 48 h at 37°C and HCV RNA was extracted and quantified by RT-qPCR. The results were normalized with respect to the cellular gene GAPDH, with the GAPDH Control Kit. The data are expressed as the amount of HCV RNA detected in cells infected with the pooled fractions from the two major virus populations in the presence of LPL as compared with the amount of HCV RNA in cells infected with the same fractions in the absence of LPL, expressed as a percentage.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3198807&req=5

pone-0026637-g003: Cell infection with low- and high-density virus populations from iodixanol gradients in the presence or absence of LPL.The pooled peak fractions of the low- and high-density virus populations obtained after centrifugation through iodixanol gradients of JFH1 grown in cell culture (A) and serum samples from the m-JFH1 chimeric mouse model (B) (both gradients are shown in Figure 2) were used to infect cells in the presence or absence of 1 µg/ml LPL, as described in the Materials and Methods section. Cells were grown for 48 h at 37°C and HCV RNA was extracted and quantified by RT-qPCR. The results were normalized with respect to the cellular gene GAPDH, with the GAPDH Control Kit. The data are expressed as the amount of HCV RNA detected in cells infected with the pooled fractions from the two major virus populations in the presence of LPL as compared with the amount of HCV RNA in cells infected with the same fractions in the absence of LPL, expressed as a percentage.

Mentions: Despite all these differences in density, LPL inhibited the infection of cells by all virus populations, regardless of whether the viruses were produced in vitro or in vivo (Figure 3A and B).


Lipoprotein lipase inhibits hepatitis C virus (HCV) infection by blocking virus cell entry.

Maillard P, Walic M, Meuleman P, Roohvand F, Huby T, Le Goff W, Leroux-Roels G, Pécheur EI, Budkowska A - PLoS ONE (2011)

Cell infection with low- and high-density virus populations from iodixanol gradients in the presence or absence of LPL.The pooled peak fractions of the low- and high-density virus populations obtained after centrifugation through iodixanol gradients of JFH1 grown in cell culture (A) and serum samples from the m-JFH1 chimeric mouse model (B) (both gradients are shown in Figure 2) were used to infect cells in the presence or absence of 1 µg/ml LPL, as described in the Materials and Methods section. Cells were grown for 48 h at 37°C and HCV RNA was extracted and quantified by RT-qPCR. The results were normalized with respect to the cellular gene GAPDH, with the GAPDH Control Kit. The data are expressed as the amount of HCV RNA detected in cells infected with the pooled fractions from the two major virus populations in the presence of LPL as compared with the amount of HCV RNA in cells infected with the same fractions in the absence of LPL, expressed as a percentage.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3198807&req=5

pone-0026637-g003: Cell infection with low- and high-density virus populations from iodixanol gradients in the presence or absence of LPL.The pooled peak fractions of the low- and high-density virus populations obtained after centrifugation through iodixanol gradients of JFH1 grown in cell culture (A) and serum samples from the m-JFH1 chimeric mouse model (B) (both gradients are shown in Figure 2) were used to infect cells in the presence or absence of 1 µg/ml LPL, as described in the Materials and Methods section. Cells were grown for 48 h at 37°C and HCV RNA was extracted and quantified by RT-qPCR. The results were normalized with respect to the cellular gene GAPDH, with the GAPDH Control Kit. The data are expressed as the amount of HCV RNA detected in cells infected with the pooled fractions from the two major virus populations in the presence of LPL as compared with the amount of HCV RNA in cells infected with the same fractions in the absence of LPL, expressed as a percentage.
Mentions: Despite all these differences in density, LPL inhibited the infection of cells by all virus populations, regardless of whether the viruses were produced in vitro or in vivo (Figure 3A and B).

Bottom Line: The effect of LPL depended on its enzymatic activity.These analyses demonstrated the internalization of virus particles into hepatoma cells and their presence in intracellular vesicles and associated with lipid droplets.HCV-associated lipoproteins may therefore be a promising target for the development of new therapeutic approaches.

View Article: PubMed Central - PubMed

Affiliation: Institut Pasteur, Unité Hépacivirus et Immunité Innée, Département de Virologie, Paris, France.

ABSTRACT
A distinctive feature of HCV is that its life cycle depends on lipoprotein metabolism. Viral morphogenesis and secretion follow the very low-density lipoprotein (VLDL) biogenesis pathway and, consequently, infectious HCV in the serum is associated with triglyceride-rich lipoproteins (TRL). Lipoprotein lipase (LPL) hydrolyzes TRL within chylomicrons and VLDL but, independently of its catalytic activity, it has a bridging activity, mediating the hepatic uptake of chylomicrons and VLDL remnants. We previously showed that exogenously added LPL increases HCV binding to hepatoma cells by acting as a bridge between virus-associated lipoproteins and cell surface heparan sulfate, while simultaneously decreasing infection levels. We show here that LPL efficiently inhibits cell infection with two HCV strains produced in hepatoma cells or in primary human hepatocytes transplanted into uPA-SCID mice with fully functional human ApoB-lipoprotein profiles. Viruses produced in vitro or in vivo were separated on iodixanol gradients into low and higher density populations, and the infection of Huh 7.5 cells by both virus populations was inhibited by LPL. The effect of LPL depended on its enzymatic activity. However, the lipase inhibitor tetrahydrolipstatin restored only a minor part of HCV infectivity, suggesting an important role of the LPL bridging function in the inhibition of infection. We followed HCV cell entry by immunoelectron microscopy with anti-envelope and anti-core antibodies. These analyses demonstrated the internalization of virus particles into hepatoma cells and their presence in intracellular vesicles and associated with lipid droplets. In the presence of LPL, HCV was retained at the cell surface. We conclude that LPL efficiently inhibits HCV infection by acting on TRL associated with HCV particles through mechanisms involving its lipolytic function, but mostly its bridging function. These mechanisms lead to immobilization of the virus at the cell surface. HCV-associated lipoproteins may therefore be a promising target for the development of new therapeutic approaches.

Show MeSH
Related in: MedlinePlus