scholarly journals Investigating Toll-Like Receptor Agonists for Potential To Treat Hepatitis C Virus Infection

2007 ◽  
Vol 51 (8) ◽  
pp. 2969-2978 ◽  
Author(s):  
Amy Thomas ◽  
Carl Laxton ◽  
Joanne Rodman ◽  
Nisha Myangar ◽  
Nigel Horscroft ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Antiviral Activity ◽  
Mononuclear Cells ◽  
Type I Interferon ◽  
Human Peripheral Blood ◽  
Alpha Interferon ◽  
Type I ◽  
Peripheral Blood Mononuclear ◽  
Necrosis Factor Alpha

ABSTRACT Toll-like receptors (TLRs) are key mediators of innate immunity, and their activation by microbial components leads to the production of cytokines and interferons. Recombinant alpha interferon has been used to treat several viral diseases and is the current standard of care for hepatitis C virus (HCV) infection. Recently, agonists of TLR7 and TLR9 have been shown to have clinical efficacy in HCV patients, and this is correlated with their ability to induce endogenous type I interferon production. We have carried out a comprehensive study of agonists of TLRs 1 to 9 to determine if any additional TLRs can induce antiviral molecules from human peripheral blood mononuclear cells (PBMCs). The agonists were incubated with PBMCs, and the supernatant was then removed and added to HCV replicon cells to assess antiviral activity. Agonists of TLRs 3, 4, 7, 8, and 9 were found to be potent inducers of antiviral activity in PBMC supernatants, and the activity correlated with the induction of alpha interferon and the interferon-induced antiviral biomarker 2′,5′-oligoadenylate synthase. Antiviral activity of TLR7 and TLR8 agonists was blocked by an antibody that binds to the type I interferon receptor, confirming that the antiviral activity results from type I interferon induction. TLR4 and TLR8 agonists were found to strongly induce the proinflammatory cytokines interleukin 1β and tumor necrosis factor alpha at concentrations similar to those inducing antiviral activity. This raises concerns about adverse side effects if these were to be used as antiviral agents. We therefore conclude that TLRs 3, 7, and 9 represent the most attractive targets for the development of new HCV therapies.

scholarly journals SCY-635, a Novel Nonimmunosuppressive Analog of Cyclosporine That Exhibits Potent Inhibition of Hepatitis C Virus RNA Replication In Vitro

2009 ◽  
Vol 54 (2) ◽  
pp. 660-672 ◽  
Author(s):  
Sam Hopkins ◽  
Bernard Scorneaux ◽  
Zhuhui Huang ◽  
Michael G. Murray ◽  
Stephen Wring ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Antiviral Activity ◽  
Mononuclear Cells ◽  
Human Peripheral Blood ◽  
Interleukin 2 ◽  
Jurkat Cells ◽  
Cytochrome P450 Enzymes ◽  
Peripheral Blood Mononuclear

ABSTRACT SCY-635 is a novel nonimmunosuppressive cyclosporine-based analog that exhibits potent suppression of hepatitis C virus (HCV) replication in vitro. SCY-635 inhibited the peptidyl prolyl isomerase activity of cyclophilin A at nanomolar concentrations but showed no detectable inhibition of calcineurin phosphatase activity at concentrations up to 2 μM. Metabolic studies indicated that SCY-635 did not induce the major cytochrome P450 enzymes 1A2, 2B6, and 3A4. SCY-635 was a weak inhibitor and a poor substrate for P-glycoprotein. Functional assays with stimulated Jurkat cells and stimulated human peripheral blood mononuclear cells indicated that SCY-635 is a weaker inhibitor of interleukin-2 secretion than cyclosporine. A series of two-drug combination studies was performed in vitro. SCY-635 exhibited synergistic antiviral activity with alpha interferon 2b and additive antiviral activity with ribavirin. SCY-635 was shown to be orally bioavailable in multiple animal species and produced blood and liver concentrations of parent drug that exceeded the 50% effective dose determined in the bicistronic con1b-derived replicon assay. These results suggest that SCY-635 warrants further investigation as a novel therapeutic agent for the treatment of individuals who are chronically infected with HCV.

scholarly journals Dynamics of Persistent TT Virus Infection, as Determined in Patients Treated with Alpha Interferon for Concomitant Hepatitis C Virus Infection

2001 ◽  
Vol 75 (24) ◽  
pp. 11999-12004 ◽  
Author(s):  
Fabrizio Maggi ◽  
Mauro Pistello ◽  
Marialinda Vatteroni ◽  
Silvano Presciuttini ◽  
Santino Marchi ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Virus Infection ◽  
Mononuclear Cells ◽  
Clinical Manifestations ◽  
Alpha Interferon ◽  
Chronic Infections ◽  
Peripheral Blood Mononuclear ◽  
Tt Virus

ABSTRACT TT virus (TTV) is a recently identified widespread DNA virus of humans that produces persistent viremia in the absence of overt clinical manifestations. In an attempt to shed light on the dynamics of chronic infection, we measured the levels of TTV in the plasma of 25 persistently infected patients during the first 3 months of alpha interferon (IFN-α) treatment for concomitant hepatitis C virus (HCV) infection. The first significant decline of TTV loads was observed at day 3 versus day 1 for HCV. Subsequently, the loads of TTV became progressively lower in most patients, but some initial responders relapsed before the end of the follow-up, suggesting that at least in some subjects the effects of IFN on TTV can be very short-lived. No correlation between the responses of TTV and HCV to therapy was found. Fitting the viremia data obtained during the first week of treatment into previously developed mathematical models showed that TTV sustains very active chronic infections, with over 90% of the virions in plasma cleared and replenished daily and a minimum of approximately 3.8 × 1010 virions generated per day. Low levels of TTV were occasionally detected in the peripheral blood mononuclear cells of patients who had cleared plasma viremia, thus corroborating previous results showing that these cells may support TTV replication and/or persistence.

scholarly journals Molecular Mimicry of Human Cytochrome P450 by Hepatitis C Virus at the Level of Cytotoxic T Cell Recognition

1999 ◽  
Vol 190 (2) ◽  
pp. 169-176 ◽  
Author(s):  
Andreas R. Kammer ◽  
Sjoerd H. van der Burg ◽  
Benno Grabscheid ◽  
Isabelle P. Hunziker ◽  
Kitty M.C. Kwappenberg ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Mononuclear Cells ◽  
Molecular Mimicry ◽  
Tissue Injury ◽  
Hcv Infection ◽  
Cytotoxic T Cell ◽  
Type I ◽  
Peripheral Blood Mononuclear

Hepatitis C virus (HCV) is thought to be involved in the pathogenesis of autoimmune hepatitis (AIH) type 2, which is defined by the presence of type I antiliver kidney microsome autoantibodies directed mainly against cytochrome P450 (CYP)2D6 and by autoreactive liver infiltrating T cells. Virus-specific CD8+ cytotoxic T lymphocytes (CTLs) that recognize infected cells and contribute to viral clearance and tissue injury during HCV infection could be involved in the induction of AIH. To explore whether the antiviral cellular immunity may turn against self-antigens, we characterized the primary CTL response against an HLA-A*0201–restricted HCV-derived epitope, i.e., HCV core 178–187, which shows sequence homology with human CYP2A6 and CYP2A7 8–17. To determine the relevance of these homologies for the pathogenesis of HCV-associated AIH, we used synthetic peptides to induce primary CTL responses in peripheral blood mononuclear cells of healthy blood donors and patients with chronic HCV infection. We found that the naive CTL repertoire of both groups contains cross-reactive CTLs inducible by the HCV peptide recognizing both CYP2A6 and CYP2A7 peptides as well as endogenously processed CYP2A6 protein. Importantly, we failed to induce CTLs with the CYP-derived peptides that showed a lower capacity to form stable complexes with the HLA-A2 molecule. These findings demonstrate the potential of HCV to induce autoreactive CD8+ CTLs by molecular mimicry, possibly contributing to virus-associated autoimmunity.

scholarly journals The 2′-O-methylation status of a single guanosine controls transfer RNA–mediated Toll-like receptor 7 activation or inhibition

2012 ◽  
Vol 209 (2) ◽  
pp. 235-241 ◽  
Author(s):  
Stefanie Jöckel ◽  
Gernot Nees ◽  
Romy Sommer ◽  
Yang Zhao ◽  
Dmitry Cherkasov ◽  
...  
Keyword(s):  
Influenza A ◽  
Mononuclear Cells ◽  
Human Peripheral Blood ◽  
Thermus Thermophilus ◽  
Methylation Status ◽  
Transfer Rna ◽  
Type I ◽  
Peripheral Blood Mononuclear ◽  
Molecular Pattern

Foreign RNA serves as pathogen-associated molecular pattern (PAMP) and is a potent immune stimulator for innate immune receptors. However, the role of single bacterial RNA species in immune activation has not been characterized in detail. We analyzed the immunostimulatory potential of transfer RNA (tRNA) from different bacteria. Interestingly, bacterial tRNA induced type I interferon (IFN) and inflammatory cytokines in mouse dendritic cells (DCs) and human peripheral blood mononuclear cells (PBMCs). Cytokine production was TLR7 dependent because TLR7-deficient mouse DCs did not respond and TLR7 inhibitory oligonucleotides inhibited tRNA-mediated activation. However, not all bacterial tRNA induced IFN-α because tRNA from Escherichia coli Nissle 1917 and Thermus thermophilus were non-immunostimulatory. Of note, tRNA from an E. coli knockout strain for tRNA (Gm18)-2′-O-methyltransferase (trmH) regained immunostimulatory potential. Additionally, in vitro methylation of this immunostimulatory Gm18-negative tRNA with recombinant trmH from T. thermophilus abolished its IFN-α inducing potential. More importantly, Gm18-modified tRNA acted as TLR7 antagonist and blocked IFN-α induction of influenza A virus–infected PBMCs.

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