• Viral Escape by Selection of Cytotoxic T Cellâ Resistant Variants in Influenza a Virus Pneumonia

      Price, Graeme E.; Ou, Rong; Jiang, Hong; Huang, Lei; Moskophidis, Demetrius; Institute of Molecular Medicine and Genetics (2000-06-5)
      Antigenic variation is a strategy exploited by influenza viruses to promote survival in the face of the host adaptive immune response and constitutes a major obstacle to efficient vaccine development. Thus, variation in the surface glycoproteins hemagglutinin and neuraminidase is reflected by changes in susceptibility to antibody neutralization. This has led to the current view that antibody-mediated selection of influenza A viruses constitutes the basis for annual influenza epidemics and periodic pandemics. However, infection with this virus elicits a vigorous protective CD8+ cytotoxic T lymphocyte (CTL) response, suggesting that CD8+ CTLs might exert selection pressure on the virus. Studies with influenza A virusâ infected transgenic mice bearing a T cell receptor (TCR) specific for viral nucleoprotein reveal that virus reemergence and persistence occurs weeks after the acute infection has apparently been controlled. The persisting virus is no longer recognized by CTLs, indicating that amino acid changes in the major viral nucleoprotein CTL epitope can be rapidly accumulated in vivo. These mutations lead to a total or partial loss of recognition by polyclonal CTLs by affecting presentation of viral peptide by class I major histocompatibility complex (MHC) molecules, or by interfering with TCR recognition of the mutant peptideâ MHC complex. These data illustrate the distinct features of pulmonary immunity in selection of CTL escape variants. The likelihood of emergence and the biological impact of CTL escape variants on the clinical outcome of influenza pneumonia in an immunocompetent host, which is relevant for the design of preventive vaccines against this and other respiratory viral infections, are discussed.
    • Viral infection prevents diabetes by inducing regulatory T cells through NKT cellâ plasmacytoid dendritic cell interplay

      Diana, Julien; Brezar, Vedran; Beaudoin, Lucie; Dalod, Marc; Mellor, Andrew L.; Tafuri, Anna; von Herrath, Matthias; Boitard, Christian; Mallone, Roberto; Lehuen, Agnes; et al. (2011-04-11)
      Type 1 diabetes (T1D) is an autoimmune disease resulting from T cellâ mediated destruction of insulin-producing β cells, and viral infections can prevent the onset of disease. Invariant natural killer T cells (iNKT cells) exert a regulatory role in T1D by inhibiting autoimmune T cell responses. As iNKT cellâ plasmacytoid dendritic cell (pDC) cooperation controls viral replication in the pancreatic islets, we investigated whether this cellular cross talk could interfere with T1D development during viral infection. Using both virus-induced and spontaneous mouse models of T1D, we show that upon viral infection, iNKT cells induce TGF-βâ producing pDCs in the pancreatic lymph nodes (LNs). These tolerogenic pDCs convert naive anti-islet T cells into Foxp3+ CD4+ regulatory T cells (T reg cells) in pancreatic LNs. T reg cells are then recruited into the pancreatic islets where they produce TGF-β, which dampens the activity of viral- and islet-specific CD8+ T cells, thereby preventing T1D development in both T1D models. These findings reveal a crucial cooperation between iNKT cells, pDCs, and T reg cells for prevention of T1D by viral infection.
    • A visual code book--structured probability distributions in natural scenes

      Wan, Weibing; Yong, Zhiyong; Brain & Behavior Discovery Institute; Department of Ophthalmology; Vision Discovery Institute (2012-07-16)
    • VPS35 haploinsufficiency increases Alzheimerâ s disease neuropathology

      Wen, Lei; Tang, Fu-Lei; Hong, Yan; Luo, Shi-Wen; Wang, Chun-Lei; He, Wanxia; Shen, Chengyong; Jung, Ji-Ung; Xiong, Fei; Lee, Dae-hoon; et al. (2011-11-28)
      VPS35, a major component of the retromer complex, is important for endosome-to-Golgi retrieval of membrane proteins. Although implicated in Alzheimerâ s disease (AD), how VPS35 regulates AD-associated pathology is unknown. In this paper, we show that hemizygous deletion of Vps35 in the Tg2576 mouse model of AD led to earlier-onset AD-like phenotypes, including cognitive memory deficits, defective long-term potentiation, and impaired postsynaptic glutamatergic neurotransmission in young adult age. These deficits correlated well with an increase of β-amyloid peptide (Aβ) level in the mutant hippocampus. We further demonstrate that VPS35 is predominantly expressed in pyramidal neurons of young adult hippocampus and interacts with BACE1, a protease responsible for Aβ production. Loss of VPS35 function in the mouse hippocampus increased BACE1 activity. Suppression of VPS35 expression in culture decreased BACE1 trans-Golgi localization but enriched it in endosomes. These results demonstrate an essential role for VPS35 in suppression of AD neuropathology and in inhibition of BACE1 activation and Aβ production by promoting BACE1 endosome-to-Golgi retrieval.
    • Welcome to molecular brain.

      Mei, Lin; Cho, Kei; Lee, C Justin; Li, Xiao-Jiang; Zhuo, Min; Kaang, Bong-Kiun; Institute of Molecular Medicine and Genetics (2008-09-22)
      ABSTRACT: We are delighted to announce the arrival of a brand new journal dedicated to the ever-expanding field of neuroscience. Molecular Brain is a peer-reviewed, open-access online journal that aims at publishing high quality articles as rapidly as possible. The journal will cover a broad spectrum of neuroscience ranging from molecular/cellular to behavioral/cognitive neuroscience and from basic to clinical research. Molecular Brain will publish not only research articles, but also methodology articles, editorials, reviews, and short reports. It will be a premier platform for neuroscientists to exchange their ideas with researchers from around the world to help improve our understanding of the molecular mechanisms of the brain and mind.
    • What the â Moonwalkâ Illusion Reveals about the Perception of Relative Depth from Motion

      Kromrey, Sarah; Bart, Evgeniy; Hegéd, Jay; Brain & Behavior Discovery Institute; Vision Discovery Institute; Department of Ophthalmology (2011-06-22)
      When one visual object moves behind another, the object farther from the viewer is progressively occluded and/or disoccluded by the nearer object. For nearly half a century, this dynamic occlusion cue has beenthought to be sufficient by itself for determining the relative depth of the two objects. This view is consistent with the self-evident geometric fact that the surface undergoing dynamic occlusion is always farther from the viewer than the occluding surface. Here we use a contextual manipulation ofa previously known motion illusion, which we refer to as theâ Moonwalkâ illusion, to demonstrate that the visual system cannot determine relative depth from dynamic occlusion alone. Indeed, in the Moonwalk illusion, human observers perceive a relative depth contrary to the dynamic occlusion cue. However, the perception of the expected relative depth is restored by contextual manipulations unrelated to dynamic occlusion. On the other hand, we show that an Ideal Observer can determine using dynamic occlusion alone in the same Moonwalk stimuli, indicating that the dynamic occlusion cue is, in principle, sufficient for determining relative depth. Our results indicate that in order to correctly perceive relative depth from dynamic occlusion, the human brain, unlike the Ideal Observer, needs additionalsegmentation information that delineate the occluder from the occluded object. Thus, neural mechanisms of object segmentation must, in addition to motion mechanisms that extract information about relative depth, play a crucial role in the perception of relative depth from motion.