Search

Abstract: Innate immune responses are critical in the defense against viral infections. NK cells, myeloid and plasmacytoid dendritic cells, and invariant CD1d-restricted NKT cells mediate both effector and regulatory functions in this early immune response. In chronic uncontrolled viral infections such as HCV and HIV-1, these essential immune functions are compromised and can become a double edged sword contributing to the immunopathogenesis of viral disease. In particular, recent findings indicate that innate immune responses play a central role in the chronic immune activation which is a primary driver of HIV-1 disease progression. HCV/HIV-1 co-infection is affecting millions of people and is associated with faster viral disease progression. Here, we review the role of innate immunity and chronic immune activation in HCV and HIV-1 infection, and discuss how mechanisms of innate immunity may influence protection as well as immunopathogenesis in the HCV/HIV-1 co-infected human host. [Copyright &y& Elsevier]

Abstract: The programmed death (PD)-1 interacts with its ligand (PDL-1) delivering a negative signal to T cells. During human immunodeficiency virus (HIV)-1 infection PD-1 and PDL-1 expressions are increased. Here we show that monocytes and CCR5+ T cells of HIV-uninfected donors upregulated PDL-1 upon in vitro exposure to HIV. HIV-induced PDL-1 required interferon (IFN)-α, but not IFN-γ, production. Inhibition of endocytosis, required for HIV-induced IFN-α production, prevented PDL-1 upregulation. IFN-α-inducing Toll-like receptor (TLR) agonists increased PDL-1 on monocytes and CCR5+ T cells. CD80 and CD86 were also increased on monocytes and CCR5+ T cells after HIV exposure, but only CD80 was IFN-α-dependent. IFN-α-receptor subunit 2 (IFNAR2), was expressed only by CCR5+ T cells and monocytes, explaining why these leukocytes responded to HIV-induced IFN-α. Finally, T cell proliferation was improved by PDL-1 blockade in HIV-treated PBMC. In the setting of HIV infection, IFN-α may negatively affect T cell responses by inducing PDL-1. [Copyright &y& Elsevier]