Lipoprotein profiles in SCID/uPA mice transplanted with human hepatocytes become human-like and correlate with HCV infection success

Abstract

remains partly unclear what determines the human specificity of HCV infection. Presumably, the presence of appropriate entry receptors is essential, and this may explain why HCV is unable to infect nonhuman hepatocytes. However, using mice with chimeric human livers, we show in this study that the presence of human hepatocytes, and therefore human entry receptors, is not sufficient for HCV infection. In successfully transplanted SCID/Alb-uPA mice, infection with HCV is reliable only when ϳ70 -80% of the liver consists of human hepatocytes. We show that chimeric mice, which are hard to infect with HCV, have significant groups of human hepatocytes that are readily infected with hepatitis B virus. Thus it is unlikely that the lack of infection with HCV can simply be attributed to low hepatocyte numbers. We investigated whether the humanization of lipoprotein profiles is positively associated with infection success. We show that the lipoprotein profiles of chimeric mice become more human-like at high levels of engraftment of human hepatocytes. This and expression of markers of human lipoprotein biosynthesis, human apolipoprotein B (ApoB) and cholesterol ester transfer protein (CETP), show a strong positive correlation with successful infection. Association of HCV in the blood of chimeric mice to ApoB-containing lipoproteins is comparable to association of HCV in patient serum and provides further support for a critical role for ApoB-containing lipoproteins in the infectious cycle of HCV. Our data suggest that the weakest link in the HCV infection chain does not appear to be the presence of human hepatocytes per se. We believe that HCV infection also depends on the presence of sufficient levels of human lipoproteins. apolipoprotein B; low-density lipoprotein; xenotransplantation; immunodeficient mouse; Flavivirus HEPATITIS C VIRUS (HCV) is a small enveloped, positive-strand RNA virus of the family of Flaviviridae and the only member of the genus Hepacivirus. Another genera in the family are Flavivirus, such as West Nile and dengue virus, and Pestivirus, such as bovine diarrhea virus. These viruses have a positivestrand RNA genome in common. Their genome consists of a single open reading frame, encoding a polyprotein that is cleaved co-and posttranslationally (11). Most Flaviviruses can infect a large range of hosts (11), but tropism of HCV infection is limited to humans and chimpanzees, and it remains unclear why other species are not susceptible to HCV infection. Possibly, the lack of entry receptors on the surface of liver cells of other species prevents infection, and recent evidence may support that idea: expression of human occludin, together with human CD81, allows for infection of mouse cells with hepatitis C pseudoparticles (18). However, replication of HCV in, for example, mouse cells is inefficient (23, 28), and there is no evidence that assembly and release of virions occur in murine hepatocytes. It is therefore likely that several other proteins or processes contribute to the tight association of HCV infe...

Glycogen synthase kinase 3β inhibitors prevent hepatitis C virus release/assembly through perturbation of lipid metabolism

“…The amount of secreted albumin was determined using an ELISA as described previously 17 . Albumin secretion was calculated as ng albumin/hour/10 7 cells and expressed as the fold-increase compared to fetal bovine serum.…”

“…Albumin secretion was calculated as ng albumin/hour/10 7 cells and expressed as the fold-increase compared to fetal bovine serum. hAAT was measured in 20 µL of tissue culture supernatant using the ELISA technique as described 17 .…”

HCV and the hepatic lipid pathway as a potential treatment target

“…Successful HCV infection of SCID/uPA mice transplanted with human hepatocytes correlates with expression of markers of human lipoprotein biosynthesis, human apoB and CETP, suggesting that CETP may be involved in the infectious cycle of HCV [157]. This raises the intriguing question of whether smallmolecule CETP inhibitors (dalcetrapib, torcetrapib, and anacetrapib) which have been or are being tested in phase 3 clinical studies, may be of benefit in chronic HCV [158].…”

Lipoprotein Lipase Inhibits Hepatitis C Virus (HCV) Infection by Blocking Virus Cell Entry

“…We first compared the effect of LPL on cell infection with different HCV strains produced in vitro in hepatoma cells (which have defective lipoprotein metabolism) with its effect on cell infection by the virus produced in primary human hepatocytes transplanted into uPA/SCID mice, a model mimicking the natural infection of differentiated human hepatocytes with normal lipid and lipoprotein metabolism [33], [34], [35], [36]. We then analyzed the mechanism of action of LPL on HCV infection, which involves the LPL catalytic function, but is dependent mostly on the structural function of the enzyme.…”