Activation of monocyte derived dendritic cells (MoDCs) by hepatitis C virus (HCV) glycoproteins

Hepatitis C Virus causes a persistent, chronic infection in more than 80% of the estimated 170 million infections worldwide. Persistent infection can lead to complications such as cirrhosis and hepatocellular carcinoma. Around 20% of HCV infected patients are able to spontaneously clear the infection. HCV glycoprotein E2 mediates HCV entry, and as such is the primary target for recognition by immune response. Production of broadly neutralizing antibodies to the E2 protein correlates with spontaneous clearance. However, antibody production requires efficient antigen presentation. Dendritic cells have a critical role in priming the adaptive immune response to pathogens. These cells are known as professional antigen presenting cells, that are specialise in antigen capture, uptake and presentation to cells in adaptive immunity. Priming of adaptive immunity to the HCV E2 protein is poorly understood. This study addressed this, aiming to investigate the recognition of HCV E2 envelope glycoproteins by dendritic cells. We used monocyte-derived dendritic cells MoDCs from healthy volunteers and HCV infected patients. MoD Cs are understood to provide the most potent activation of adaptive immune responses. This study analysed the binding, stimulation and eytokine production by MoDCs Following interaction with the soluble ectodomain of the E2 glycoprotein, sE2661. The activation of dendritic cells from healthy donors and HCV infected Lindividuials by the TLR4 agonist Lipopolysaccharide (LPS) and the TLR3 agonist polycytidylic acid (Poly I:C) was also analysed. It was hypothesised that the efficacy of dendritic cell recognition might contribute to the differing outcomes of HCV infection. sE2 interacted with multiple receptors on the surface of MoD Cs, including CD81 and DC-SIGN. Cell-surface expressed Mannose Receptor also bound to E2. These interactions resulted in moderate activation of MoDCs, but was associated with different profiles of cytokine release compared to cells stimulated with either LPS or Poly I:C. In both healthy donors and HCV positive patients similar expression of CD86 was observed following stimulation, either with sE2, LPS or Poly I:C. In contrast, expression of CD83 was significantly reduced in HCV infections, compared to healthy donors. MoD Cs isolated from HCV infected individuals displayed a normal cytokine production compared to healthy donors. When MoDCs were activated with combinations of sE266\ with LPS or poly I:C, di lfereuces were observed in the phenotype and production of cytokines between MoDCs isolated from healthy controls and HCV infected patients. These results demonstrate that the HCV E266\ protein is recognised by some MoDCs, resulting in up-regulated expression of the DC maturation markers CD83 and 086 and altered patterns of cytokine secretion, compared to un-stimulated cells, . This activation is not similar to that achieved with LPS or poly I:C. HCV sE2661 does not possess the capacity to induce either Th 1- or Th2-type immune responses in MoD Cs from both healthy and HCV infected patients. However, this protein induced production of TNF-a from MoDCs isolated from some healthy donors, but not from MofX's isolated from Hev -infected patients. In addition, sE2661 was found to influence MoDes function when combined with TLR ligands. It is concluded that MoDes from some HeV infected patients possess different in phenotypes to healthy controls. This may play a role in the inability to control HeV infection.EThOS - Electronic Theses Online ServiceGBUnited Kingdo