Intrahepatic natural immunity and HCV immunopathogenesis

The basal activation state of DC subsets correlates with anti-HCV treatment outcome in HCV/HIV co-infected patients

In this work we evaluated plasmacytoid (pDC) and myeloid dendritic (mDC) cells activation before and during anti-HCV treatment in HCV+/HIV+ individuals. HCV+/HIV+ patients received Peg-IFN-α2b subcutaneously for 28 days, followed by oral weight-based ribavirin. DCs activation was evaluated by flow cytometry. Baseline pDC CD80 and CD86 expression was correlated with HIV, but not with HCV viral load. A transient decrease of HIV RNA was found not associated with DC activation. When patients were grouped according to early/sustained virological response (EVR/SVR) to anti-HCV treatment, baseline pDC CD80 and CD86 expression was higher in non-EVR and non-SVR compared to EVR and SVR. Moreover, in responder patients CD80 and CD86 were upregulated by IFN-α. Our data suggest a correlation between DCs activation and response to therapy. These findings could be helpful to better understand the mediators of IFN-α action in HCV+/HIV+ patients and to explore possible exploitation of this knowledge to improve therapeutic response.

Activation of Vgamma9Vdelta2 T cells by non-peptidic antigens induces the inhibition of subgenomic HCV replication

Hepatitis C virus (HCV) has evolved complex strategies to evade host immune responses and establish chronic infection. Since human Vγ9Vδ2 T lymphocytes play a critical role in the immune response against viruses, we analyzed their antiviral functions on Huh7 hepatoma cells carrying the subgenomic HCV replicon (Rep60 cells). In a transwell culture system, Rep60 cells were co-cultured with either PBMCs or highly purified γδ T cells stimulated by non-peptidic antigens. Vγ9Vδ2 T cell activation was associated with a dramatic reduction of HCV RNA levels. Neutralizing antibodies targeting IFN-γ revealed a critical role for this cytokine in the inhibition of HCV replication. Interestingly, drugs already in clinical use, such as Phosphostim and Zoledronate, known to activate γδ T cells, were shown to induce the inhibition of HCV replication mediated by Vγ9Vδ2 T cells of HCV patients. Our data suggest that the therapeutic activation of Vγ9Vδ2 T lymphocytes may represent an additional strategy to inhibit HCV replication and to restore a T_h1-oriented immune response in HCV-infected patients.

Antiviral reactivities of gammadelta T cells

The complex antiviral immune mechanisms involve both adaptive and innate reactions mediated by γδ T lymphocytes, whose unique immunosurveillance contributions are analyzed here in different clinical and experimental settings. It is beyond any doubt that the fast, potent, cytotoxic as well as non-cytolytic antiviral activities of γδ T cells are critical in protecting the host against diverse viral pathogens.