Early IFNγ-Mediated and Late Perforin-Mediated Suppression of Pathogenic CD4 T Cell Responses Are Both Required for Inhibition of Demyelinating Disease by CNS-Specific Autoregulatory CD8 T Cells

Pathogenesis of immune-mediated demyelinating diseases like multiple sclerosis (MS) is thought to be governed by a complex cellular interplay between immunopathogenic and immunoregulatory responses. We have previously shown that central nervous system (CNS)-specific CD8 T cells have an unexpected protective role in the mouse model of MS, experimental autoimmune encephalomyelitis (EAE). In this study, we interrogated the suppressive potential of PLP178-191-specific CD8 T cells (PLP-CD8). Here, we show that PLP-CD8, when administered post-disease onset, rapidly ameliorated EAE progression, and suppressed PLP178-191-specific CD4 T cell responses as measured by delayed-type hypersensitivity (DTH). To accomplish DTH suppression, PLP-CD8 required differential production of perforin and IFNγ. Perforin was not required for the rapid suppressive action of these cells, but was critical for maintenance of optimal longer term DTH suppression. Conversely, IFNγ production by PLP-CD8 was necessary for swift DTH suppression, but was less significant for maintenance of longer term suppression. These data indicate that CNS-specific CD8 T cells employ an ordered regulatory mechanism program over a number of days in vivo during demyelinating disease and have mechanistic implications for this immunotherapeutic approach

A wirelessly powered and controlled device for optical neural control of freely-behaving animals

Optogenetics, the ability to use light to activate and silence specific neuron types within neural networks in vivo and in vitro, is revolutionizing neuroscientists' capacity to understand how defined neural circuit elements contribute to normal and pathological brain functions. Typically, awake behaving experiments are conducted by inserting an optical fiber into the brain, tethered to a remote laser, or by utilizing an implanted light-emitting diode (LED), tethered to a remote power source. A fully wireless system would enable chronic or longitudinal experiments where long duration tethering is impractical, and would also support high-throughput experimentation. However, the high power requirements of light sources (LEDs, lasers), especially in the context of the extended illumination periods often desired in experiments, precludes battery-powered approaches from being widely applicable. We have developed a headborne device weighing 2 g capable of wirelessly receiving power using a resonant RF power link and storing the energy in an adaptive supercapacitor circuit, which can algorithmically control one or more headborne LEDs via a microcontroller. The device can deliver approximately 2 W of power to the LEDs in steady state, and 4.3 W in bursts. We also present an optional radio transceiver module (1 g) which, when added to the base headborne device, enables real-time updating of light delivery protocols; dozens of devices can be controlled simultaneously from one computer. We demonstrate use of the technology to wirelessly drive cortical control of movement in mice. These devices may serve as prototypes for clinical ultra-precise neural prosthetics that use light as the modality of biological control.National Institutes of Health (U.S.) (NIH Director’s New Innovator Award (DP2OD002002))National Institutes of Health (U.S.) (Grant 1R01DA029639)National Institutes of Health (U.S.) (Grant 1RC1MH088182)National Institutes of Health (U.S.) (Grant 1RC2DE020919)National Institutes of Health (U.S.) (Grant 1R01NS067199)National Institutes of Health (U.S.) (Grant 1R43NS070453)National Science Foundation (U.S.) (CAREER award)National Science Foundation (U.S.) (NSF Grant DMS 1042134)National Science Foundation (U.S.) (NSF Grant DMS 0848804)National Science Foundation (U.S.) (NSF Grant EFRI 0835878)Benesse FoundationGoogle (Firm)Dr. Gerald Burnett and Marjorie BurnettUnited States. Dept. of Defense (CDMRP PTSD Program)Massachusetts Institute of TechnologyBrain & Behavior Research FoundationAlfred P. Sloan FoundationSociety for NeuroscienceMassachusetts Institute of Technology. Media LaboratoryMcGovern Institute for Brain Research at MITWallace H. Coulter Foundatio

Kuhnian revolutions in neuroscience: the role of tool development.

The terms "paradigm" and "paradigm shift" originated in "The Structure of Scientific Revolutions" by Thomas Kuhn. A paradigm can be defined as the generally accepted concepts and practices of a field, and a paradigm shift its replacement in a scientific revolution. A paradigm shift results from a crisis caused by anomalies in a paradigm that reduce its usefulness to a field. Claims of paradigm shifts and revolutions are made frequently in the neurosciences. In this article I will consider neuroscience paradigms, and the claim that new tools and techniques rather than crises have driven paradigm shifts. I will argue that tool development has played a minor role in neuroscience revolutions.The work received no fundin

Pulmonary Infection with Influenza A Virus Induces Site-Specific Germinal Center and T Follicular Helper Cell Responses

<div><p>Protection from influenza A virus (IAV) challenge requires switched, high affinity Abs derived from long-lived memory B cells and plasma cells. These B cell subsets are generated in germinal centers (GCs), hallmark structures of T helper cell-driven B cell immunity. A full understanding of the GC reaction after respiratory IAV infection is lacking, as is the characterization of T follicular helper (T_FH) cells that support GCs. Here, GC B cell and T_FH cell responses were studied in mice following pulmonary challenge with IAV. Marked GC reactions were induced in draining lymph nodes (dLNs), lung, spleen and nasal-associated lymphoid tissue (NALT), although the magnitude and kinetics of the response was site-specific. Examination of switching within GCs demonstrated IgG2⁺ cells to compose the largest fraction in dLNs, lung and spleen. IgA⁺ GC B cells were infrequent in these sites, but composed a significant subset of the switched GC population in NALT. Further experiments demonstrated splenectomized mice to withstand a lethal recall challenge, suggesting the spleen to be unnecessary for long-term protection in spite of strong GC responses in this organ. Final studies showed that T_FH cell numbers were highest in dLNs and spleen, and peaked in all sites prior to the height of the GC reaction. T_FH cells purified from dLNs generated IL-21 and IFNγ upon activation, although CD4⁺CXCR5⁻ T effector cells produced higher levels of all cytokines. Collectively, these findings reveal respiratory IAV infection to induce strong T helper cell-driven B cell responses in various organs, with each site displaying unique attributes.</p> </div

Distribution of IgG subclass-expressing B cells within the GC.

<p>Animals were infected i.n. with a 0.1LD₅₀ dose of IAV on day 0. dLNs, lung, and spleen were harvested on days 8–30 post-infection and stained with PNA, anti-B220 mAb and either goat anti-IgG1, IgG2a, IgG2b, IgG3 or IgA specific Abs. A) Representative plots (from B220⁺PNA^hi parent gates) show the gating strategy used to define IgG1⁺, IgG2a⁺, IgG2b⁺, IgG3⁺ and IgA⁺ GC B cells in dLNs, lung and spleen at day 18 post-infection. B) Bar graphs represent the percent of IgG⁺ subsets within the B220⁺PNA^hi GC population. Each bar represents mean ± SEM. <i>n</i> = 5–6 mice per group and time point.</p

IAV-induced GC B cell responses exhibit site-specific switching characteristics.

<p>Animals were infected i.n. with a 0.1LD₅₀ dose of IAV on day 0. dLNs, lung, and spleen were harvested on days 8–30 post-infection and stained with PNA, anti-B220 mAb and anti-IgM mAb. A) Representative plots show the gating strategy used to define non-switched IgM⁺ and switched IgM⁻ GC B cells in dLNs, lung and spleen at day 18 post-infection. B) Bar graphs represent the percent of non-switched IgM⁺ (closed bars) and switched IgM⁻ (hatched bars) B cells within the B220⁺PNA^hi GC population. C) Bar graphs represent the total number of non-switched IgM⁺ (closed bars) and switched IgM⁻ (hatched bars) GC B cells per organ. dLN data are shown as total cells per lymph node. Each bar represents mean ± SEM. <i>n</i> = 5–6 mice per group and time point.</p

IAV-induced T_FH cell dynamics in dLNs, spleen and lung¹.

1<p>Animals were given a 0.1LD₅₀ dose of IAV i.n. on day 0. dLNs, spleen and lung were harvested on days 8–24 post-infection and T_FH cell populations identified by flow cytometry based on their CD4⁺CD44^hiCXCR5⁺CD150^lo phenotype. Values represent mean ± SEM. <i>n</i> = 5–6 mice per group and time point.</p>2<p>Total number of T_FH cells per spleen or lung; total number of T_FH cells per node.</p>3<p>Ratio of GC B cells to T_FH cells is based on total recovered GC and T_FH cells per lung or spleen; dLN ratios were based on cell recovery per node.</p

IAV-specific Ab responses in serum and BAL fluid.

<p>Animals were infected i.n. with a 0.1LD₅₀ dose of IAV on day 0. Serum and BAL samples were harvested from mice on day 24 post-infection or from naïve uninfected animals. Serum and BAL Ab responses were measured using an IAV-specific whole virus ELISA. A) The top panel shows total IAV-specific IgG and IgA responses in serum. IAV-specific IgA levels were near background levels. IAV-specific IgG and IgA Abs were undetectable in sera from uninfected animals. The bottom panel represents IAV-specific IgG1, IgG2a, IgG2b, and IgG3 Ab levels is serum. B) The top panel shows total IAV-specific IgG and IgA responses in BAL samples. IAV-specific IgG and IgA Abs were undetectable in BAL fluid from uninfected animals. The bottom panel represents IAV-specific IgG1, IgG2a, IgG2b, and IgG3 Ab levels in BAL fluid. Each value represents mean ± SEM. The results in panels A and B are representative of 2 separate ELISA tests performed with separate groups of mice. <i>n</i> = 3 mice per group.</p

Splenectomized mice withstand a secondary 10.0LD₅₀ IAV infection.

<p>Sham or splenectomized animals were given a sublethal 0.1LD₅₀ dose of IAV i.n. on day 0 and a subsequent 10.0LD₅₀ dose of IAV i.n. on day 42. Morbidity and mortality were monitored through day 50. Serum samples were harvested on day 28 following primary sublethal infection. A) Line graphs represent percent of starting body weight (morbidity) after primary and secondary infection. B) Line graphs represent survival (mortality) after primary and secondary infection. C) IgG1, IgG2a, IgG2b and IgG3 Ab responses were measured in day 28 post-infection sera using an IAV-specific whole virus ELISA. Sera from naïve mice were also tested. Each value represents mean ± SEM. <i>n</i> = 4 for sham splenectomized mice. <i>n</i> = 5 for splenectomized mice. *<i>p</i><0.05; represents the statistical difference between sham and splenectomized mouse sera at the indicated dilutions as determined by the unpaired Student's t test.</p