Project description:The role of astrocytes in innate immunity during viral infections of the central nervous system (CNS) remains to be fully elucidated. Here, we demonstrate that type I interferon (IFN) receptor (IFNAR) signaling in astrocytes regulates blood-brain barrier permeability and protects the cerebellum from infection and immunopathology. Mice with astrocytes lacking IFNAR signaling showed decreased survival after West Nile virus infection that was not due to expanded viral tropism or increased replication. Pattern recognition receptors and IFN-stimulated genes (ISGs) had higher basal and IFN-induced expression in human and mouse cerebellar astrocytes compared to cerebral cortical astrocytes. Our data identify cerebellar astrocytes as key responders to viral infection and highlight distinct innate immune programs in astrocytes from evolutionarily disparate regions of the CNS.
Project description:Toxoplasma gondii (T. gondii) is an opportunistic parasite that can infect the central nervous system, causing severe toxoplasmosis and behavioral cognitive impairment. Mortality is high in immunocompromised individuals with toxoplasmosis, most commonly due to reactivation of infection in the central nervous system (CNS). There are still no effective vaccines and drugs for the prevention and treatment of toxoplasmosis. There are five developmental stages for T. gondii to complete life cycle, of which the tachyzoite and bradyzoite stages are the key to the acute and chronic infection. In this study, to better understanding of how T. gondii interacts with the host central nervous system at different stages of infection, we constructed acute and chronic infection models of T. gondii in astrocytes, and used lab-free proteomics to detect the proteome changes before and after infection, respectively.
Project description:The local production of IFN-γ is important to control Toxoplasma gondii in the brain but the basis for these protective effects are not fully understood. The studies presented here reveal that the ability of IFN-γ to inhibit parasite replication in astrocytes in vitro is dependent on signal transducer and activator of transcription 1 (STAT1) and that mice that specifically lack STAT1 in astrocytes are unable to limit parasite replication in the central nervous system (CNS). This susceptibility is associated with a loss of anti-microbial pathways but also altered local immune responses that include decreased T cell production of IFN-γ and elevated expression of inhibitory receptors. These results identify a critical role for astrocytes in limiting the replication of an important opportunistic pathogen and highlight their role in coordinating local anti-parasitic responses.
Project description:The overall goal of the study was to use in vivo data combined with functional genomics to define gene expression signatures representative of a spectrum of HSV CNS infections. Innate immune deficiencies result in a spectrum of severe clinical outcomes following infection. In particular, there is a strong association between loss of the signal transducer and activator of transcription (Stat) pathway, breach of the blood-brain barrier (BBB), and virus-induced neuropathology. The gene signatures that characterize resistance, disease, and mortality in the virus-infected nervous system have not been defined. Herpes simplex virus type 1 (HSV-1) is commonly associated with encephalitis in humans, and humans and mice lacking Stat1 display increased susceptibility to HSV central nervous system (CNS) infections. In this study, two HSV-1 strains were used, KOS (wild type [WT]), and Δvhs, an avirulent recombinant lacking the virion host shutoff (vhs) function. In addition, two mouse strains were used: strain 129 (control) and a Stat1-deficient (Stat1(-/-)) strain. Using combinations of these virus and mouse strains, we established a model of infection resulting in three different outcomes: viral clearance without neurological disease (Δvhs infection of control mice), neurological disease followed by viral clearance (Δvhs infection of Stat1(-/-) mice and WT infection of control mice), or neurological disease followed by death (WT infection of Stat1(-/-) mice). Through the use of functional genomics on the infected brain stem and liver, we determined gene signatures that were representative of the three infection outcomes.
Project description:The overall goal of the study was to use in vivo data combined with functional genomics to define gene expression signatures representative of a spectrum of HSV CNS infections. Innate immune deficiencies result in a spectrum of severe clinical outcomes following infection. In particular, there is a strong association between loss of the signal transducer and activator of transcription (Stat) pathway, breach of the blood-brain barrier (BBB), and virus-induced neuropathology. The gene signatures that characterize resistance, disease, and mortality in the virus-infected nervous system have not been defined. Herpes simplex virus type 1 (HSV-1) is commonly associated with encephalitis in humans, and humans and mice lacking Stat1 display increased susceptibility to HSV central nervous system (CNS) infections. In this study, two HSV-1 strains were used, KOS (wild type [WT]), and Δvhs, an avirulent recombinant lacking the virion host shutoff (vhs) function. In addition, two mouse strains were used: strain 129 (control) and a Stat1-deficient (Stat1(-/-)) strain. Using combinations of these virus and mouse strains, we established a model of infection resulting in three different outcomes: viral clearance without neurological disease (Δvhs infection of control mice), neurological disease followed by viral clearance (Δvhs infection of Stat1(-/-) mice and WT infection of control mice), or neurological disease followed by death (WT infection of Stat1(-/-) mice). Through the use of functional genomics on the infected brain stem and liver, we determined gene signatures that were representative of the three infection outcomes. Gender matched, 6- to 8- week old immunocompetent, control 129S6 and 129S6 Stat1 knockout mice were infected corneally with 2x10^6 PFU of either wild type HSV-1, a vhs-null HSV virus, or mock-infected. Brain stems and liver of individual mice were isolated at days 1, 3, 5 and 7 post-inoculation for microarray analysis. For microarray analysis, samples were collected from n=2 animals (1 male, 1 female) per mouse strain and virus strain for each time point. Equal masses of tissue were pooled from two mock-infected mice per time point and run on microarray.