RESUMO
The DC-SIGN receptor on human dendritic cells interacts with HIV gp120 to promote both infection of antigen-presenting cells and transinfection of T cells. We hypothesized that in DC-SIGN-expressing cells, both DC-SIGN ligands such as dextrans and gp120 antagonists such as peptide triazoles would inhibit HIV infection with potential complementary antagonist effects. To test this hypothesis, we evaluated the effects of dextran (D66), isomaltooligosaccharides (D06), and several peptide triazoles (HNG156, K13, and UM15) on HIV infection of B-THP-1/DC-SIGN cells. In surface plasmon resonance competition assays, D66 (IC50 = 35.4 µM) and D06 (IC50 = 3.4 mM) prevented binding of soluble DC-SIGN to immobilized mannosylated bovine serum albumin (BSA). An efficacious dose-dependent inhibition of DC-SIGN-mediated HIV infection in both pretreatment and posttreatment settings was observed, as indicated by inhibitory potentials (EC50) [D66 (8 µM), D06 (48 mM), HNG156 (40 µM), UM15 (100 nM), and K13 (25 nM)]. Importantly, both dextrans and peptide triazoles significantly decreased HIV gag RNA levels [D66 (7-fold), D06 (13-fold), HNG156 (7-fold), K-13 (3-fold), and UM15 (6-fold)]. Interestingly, D06 at the highest effective concentration showed a 14-fold decrease of infection, while its combination with 50 µM HNG156 showed a 26-fold decrease. Hence, these compounds can combine to inactivate the viruses and suppress DC-SIGN-mediated virus-cell interaction that as shown earlier leads to dendritic cell HIV infection and transinfection dependent on the DC-SIGN receptor.
Assuntos
Moléculas de Adesão Celular/antagonistas & inibidores , Dextranos/farmacologia , Proteína gp120 do Envelope de HIV/antagonistas & inibidores , HIV-1/efeitos dos fármacos , Lectinas Tipo C/antagonistas & inibidores , Peptídeos/farmacologia , Receptores de Superfície Celular/antagonistas & inibidores , Triazóis/farmacologia , Sítios de Ligação , Moléculas de Adesão Celular/genética , Moléculas de Adesão Celular/metabolismo , Linhagem Celular , Células Dendríticas/efeitos dos fármacos , Células Dendríticas/metabolismo , Células Dendríticas/virologia , Dextranos/metabolismo , Regulação da Expressão Gênica , Proteína gp120 do Envelope de HIV/genética , Proteína gp120 do Envelope de HIV/metabolismo , HIV-1/genética , HIV-1/metabolismo , Interações Hospedeiro-Patógeno , Humanos , Lectinas Tipo C/genética , Lectinas Tipo C/metabolismo , Ligantes , Manose/antagonistas & inibidores , Manose/metabolismo , Oligossacarídeos/metabolismo , Oligossacarídeos/farmacologia , Peptídeos/metabolismo , Ligação Proteica , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo , Albumina Sérica/antagonistas & inibidores , Albumina Sérica/metabolismo , Transdução de Sinais , Triazóis/metabolismo , Carga Viral/efeitos dos fármacos , Produtos do Gene gag do Vírus da Imunodeficiência Humana/antagonistas & inibidores , Produtos do Gene gag do Vírus da Imunodeficiência Humana/biossíntese , Produtos do Gene gag do Vírus da Imunodeficiência Humana/genéticaRESUMO
The hepatitis C virus (HCV) genome codes for highly mannosylated envelope proteins, which are naturally retained in the endoplasmic reticulum. We found that the HCV envelope glycoprotein E2 binds the dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN) and the related liver endothelial cell lectin L-SIGN through high-mannose N-glycans. Competing ligands such as mannan and an antibody directed against the carbohydrate recognition domains (CRD) abrogated binding. While no E2 interaction with distant monomeric CRDs on biosensor chips could be detected, binding is observed if CRDs are closely seeded (Kd = 48 nm) and if the CRD is part of the oligomeric-soluble extracellular domain of DC-SIGN (Kd = 30 nm). The highest affinity is seen for plasma membrane-expressed DC-SIGN and L-SIGN (Kd = 3 and 6 nm, respectively). These results indicate that several high-mannose N-glycans in a structurally defined cluster on E2 bind to several subunits of the oligomeric lectin CRD. High affinity interaction of viral glycoproteins with oligomeric lectins might represent a strategy by which HCV targets to and concentrates in the liver and infects dendritic cells.