Type I Interferon Inhibition and Dendritic Cell Activation during Gammaherpesvirus Respiratory Infection

Abstract

The respiratory tract is a major mucosal site for microorganism entry into the body, and type I interferon (IFN) and dendritic cells constitute a first line of defense against viral infections. We have analyzed the interaction between a model DNA virus, plasmacytoid dendritic cells, and type I IFN during lung infection of mice. Our data show that murine gammaherpesvirus 68 (␥HV68) inhibits type I IFN secretion by dendritic cells and that plasmacytoid dendritic cells are necessary for conventional dendritic cell maturation in response to ␥HV68. Following ␥HV68 intranasal inoculation, the local and systemic IFN-␣/␤ response is below detectable levels, and plasmacytoid dendritic cells are activated and recruited into the lung with a tissue distribution that differs from that of conventional dendritic cells. Our results suggest that plasmacytoid dendritic cells and type I IFN have important but independent roles during the early response to a respiratory ␥HV68 infection. ␥HV68 infection inhibits type I IFN production by dendritic cells and is a poor inducer of IFN-␣/␤ in vivo, which may serve as an immune evasion strategy.Respiratory viral infections are the leading cause of acute illnesses worldwide, and several members of the herpesvirus family are responsible for severe pneumonia in neonates and immunocompromised patients (52). Herpes simplex virus, cytomegalovirus, varicella-zoster virus, Epstein-Barr virus, human herpesvirus 6, and Kaposi's sarcoma-associated herpesvirus (KSHV) have all been associated with respiratory diseases (7,10,30,33,42,46). Much of our understanding of immune responses to viral infection of the respiratory tract comes from experimental animal models. Murine gammaherpesvirus 68 (␥HV68) is structurally and biologically similar to the human gammaherpesviruses Epstein-Barr virus and KSHV (16,49,50), and it has become a useful in vivo model of herpesvirus infection. Intranasal infection of mice with ␥HV68 causes an acute respiratory infection that is rapidly resolved and followed by the establishment of splenic latency mainly in the B-cell compartment (16, 34). Analogous to KSHV (35,38,41), ␥HV68 also infects dendritic cells, a process that may act as a mechanism of immune evasion (18,20).Plasmacytoid dendritic cells are professional type I interferon (IFN)-producing cells that quickly respond to most viruses by secreting large amounts of type I IFNs (28). Type I IFN signaling is important for the control of acute ␥HV68 infection (17, 51). In addition, plasmacytoid dendritic cells secrete cytokines and interact with conventional dendritic cells and T cells (28) and are critical for the defense against parenteral and mucosal infections (1,13,25,29). Although plasmacytoid dendritic cells have been detected in the lungs (12,14) and have been shown to prevent the development of allergic asthma, we have limited information regarding their role in the antiviral response of the respiratory tract. This is of special importance because the lung is the largest epithelial surface in the body and constit...

Plasticity and Virus Specificity of the Airway Epithelial Cell Immune Response during Respiratory Virus Infection

“…NF-B and interferons mediate the epithelial response to RSV and influenza virus (2,5,29,56). Our recent work using mouse models of infection has highlighted that interferons and epithelial cells are central players during the immune response of the airways and that different viral infections of the lung induce singular interferon responses (24,25,55). Evidence from the analysis of IFNAR Ϫ/Ϫ and STAT1 Ϫ/Ϫ mAECs at the gene and protein levels shows a dramatic reduction of the innate effector response during influenza virus infection, corroborating that interferons and STAT1 play a central role in the initiation of immune responses by the airway epithelium.…”

Murine gammaherpesvirus 68 infection protects lupus-prone mice from the development of autoimmunity

“…The virus may otherwise alter the development of autoimmunity by modulating DCs, which are known to contribute to the development of lupus in B6.Sle123 mice by producing large amounts of proinflammatory cytokines and driving high levels of B-cell and T-cell proliferation (68)(69)(70). Acute infection of DCs with γHV68 decreases their ability to present antigen and to express proinflammatory cytokines (20,21,29,61,71). Reduced endocytic function of DCs during γHV68 acute infection was also observed in the context of the autoimmune NOD genetic background (29).…”

Type I Interferon Signaling Enhances CD8+T Cell Effector Function and Differentiation during Murine Gammaherpesvirus 68 Infection

“…Type I IFN signaling on dendritic cells functions to upregulate antigen cross-presentation to CD8 ϩ T cells as well as expression of costimulatory molecules necessary for CD8 ϩ T cell activation (38,39). During MHV68 infection, plasmacytoid dendritic cells are recruited to the lung and upregulate major histocompatibility complex (MHC) class II (40 (45). High levels of antigen exposure are key mediators of CD8 ϩ T cell exhaustion (46)(47)(48).…”