ASC filament formation serves as a signal amplification mechanism for inflammasomes

A hallmark of inflammasome activation is the ASC speck, a micrometre-sized structure formed by the inflammasome adaptor protein ASC (apoptosis-associated speck-like protein containing a CARD), which consists of a pyrin domain (PYD) and a caspase recruitment domain (CARD). Here we show that assembly of the ASC speck involves oligomerization of ASC(PYD) into filaments and cross-linking of these filaments by ASC(CARD). ASC mutants with a non-functional CARD only assemble filaments but not specks, and moreover disrupt endogenous specks in primary macrophages. Systematic site-directed mutagenesis of ASC(PYD) is used to identify oligomerization-deficient ASC mutants and demonstrate that ASC speck formation is required for efficient processing of IL-1β, but dispensable for gasdermin-D cleavage and pyroptosis induction. Our results suggest that the oligomerization of ASC creates a multitude of potential caspase-1 activation sites, thus serving as a signal amplification mechanism for inflammasome-mediated cytokine production

Effector mechanisms of non-canonical inflammasome activation

Our body constantly faces all kinds immunological challenges, ranging from sterile wounds to non-pathogenic and sometimes pathogenic microorganisms. The innate immune system represents the first line of defense against these challenges. It is capable of detecting invading microorganisms and tissue damage by conserved, germline-encoded pattern recognition receptors (PRRs) and launches a first counterstrike through mechanisms including phagocytosis, reactive oxygen species (ROS) or anti-microbial peptides. Concomitant production and secretion of cytokines alerts the adaptive immune system and initializes are very potent, highly specific and sustained immune response governed by the activation and expansion of T- and B-cells. Inflammasomes are one important class of cytosolic PRRs as they recognize a large variety of pathogens. Engagement of inflammasome pathways leads to death of the infected host cell by pyroptosis and secretion of pro-inflammatory cytokines like IL-1b and IL-18. The recently discovered non-canonical inflammasome pathway is triggered by intracellular bacterial lipopolysaccharide (LPS), which binds to caspase-11 to activate it. Active caspase-11 triggers pyroptosis and activates a canonical Nlrp3 inflammasome to promote caspase-1 activation and IL-1 secretion. The molecular details of pyroptosis execution and the signaling events downstream of caspase-11 have not been thoroughly characterized, which is why this was the main interest underlying my PhD work. I investigated the connection between caspase-11 activation and cytokine release triggered by the canonical NLRP3 inflammasome. I could show that caspase-11 stimulates NLRP3 activation by promoting potassium efflux, a well characterized trigger for the NLRP3 inflammasome, in a cell autonomous manner. Subsequently I got interested in the molecular mechanisms underlying pyroptosis induction by Gasdermin-D. We could characterize pore formation by the Gasdermin-D N-terminal fragment as the final step of pyroptosis. Finally, I investigated if cells are capable of preventing or delaying pyroptosis downstream of caspase-11/gasdermin-D. I found that removal of Gasdermin-D pores by ESCRT-III mediated membrane repair represents one mechanism by which cells prevent Gasdermin-D dependent cell death. Overall my results revealed connections between innate immunity signaling pathways, uncovered a novel form of cellular pore forming toxins and demonstrated an unexpected regulation of pyroptosis by cellular survival pathways

GSDMD membrane pore formation constitutes the mechanism of pyroptotic cell death

Pyroptosis is a lytic type of cell death that is initiated by inflammatory caspases. These caspases are activated within multi-protein inflammasome complexes that assemble in response to pathogens and endogenous danger signals. Pyroptotic cell death has been proposed to proceed via the formation of a plasma membrane pore, but the underlying molecular mechanism has remained unclear. Recently, gasdermin D (GSDMD), a member of the ill-characterized gasdermin protein family, was identified as a caspase substrate and an essential mediator of pyroptosis. GSDMD is thus a candidate for pyroptotic pore formation. Here, we characterize GSDMD function in live cells and in vitro We show that the N-terminal fragment of caspase-1-cleaved GSDMD rapidly targets the membrane fraction of macrophages and that it induces the formation of a plasma membrane pore. In vitro, the N-terminal fragment of caspase-1-cleaved recombinant GSDMD tightly binds liposomes and forms large permeability pores. Visualization of liposome-inserted GSDMD at nanometer resolution by cryo-electron and atomic force microscopy shows circular pores with variable ring diameters around 20 nm. Overall, these data demonstrate that GSDMD is the direct and final executor of pyroptotic cell death

Wissensgesellschaft als Herausforderung für ländlich-periphere Regionen: Beispiele aus Nordostdeutschland

Die Heuristik einer dreidimensionalen Wissensgesellschaft wird in diesem Band aufgegriffen und weiterentwickelt. Die soziale, die ökonomische und die technische Dimension der Wissensgesellschaft werden im theoretischen Teil ausdifferenziert und anhand charakteristischer Ausprägungen strukturiert, z.B. individuelle Kompetenzen, kollektive Lernprozesse, Wirtschaftsfaktor Wissen, Zentralität, Mobilität oder Einbindung in globale Institutionensysteme. Diese strukturierenden Elemente bilden die Grundlage für die Auswahl von vertiefenden Studien im ländlichen, peripher gelegenen Raum Nordostdeutschlands im Hinblick auf Wachstumskerne in Brandenburg, Gesundheitsinfrastruktur, Mobilitätsangebote und Anschluss an Kommunikationstechnologien sowie Aus- und Weiterbildung, Bildungsnetzwerke und Bildungslandschaften. Beim Vergleich von Theorie und Praxis, von heuristischem Modell und Fallstudien, ist die Auswahl der Beispiele nicht repräsentativ und deckt nicht die ganze Vielfalt und Vielschichtigkeit der Wissensgesellschaft in ländlich- peripheren Räumen ab. Erste Konturen, wie die Wissensgesellschaft in diesen Räumen zum Ausdruck kommt, welche strategischen Herausforderungen dies mit sich bringt und welchen Anteil die räumliche Planung an den anstehenden strategischen Ansätzen haben kann, zeigen sich dennoch. Der Fachkräftemangel scheint eine zentrale Ausprägung und Herausforderung der Wissensgesellschaft in der ländlichen Peripherie zu sein. Die scharfe, theoretisch begründete Trennung der Dimensionen ist in der Praxis nicht in dieser Form aufrechtzuerhalten: So sind die für die ökonomische Dimension charakteristischen Innovationen nicht ohne soziale Lernprozesse und brückenschlagende Institutionensysteme, die hier der technischen Dimension zugerechnet werden, denkbar. Letztere wiederum funktionieren nur dann tatsächlich, wenn Menschen und Wissen mobilisiert werden und damit Wissensnetzwerke entstehen. Die peripher gelegenen ländlichen Räume sind genauso wie die Metropolräume Teil der Wissensgesellschaft. Damit sind beide Raumtypen gleichermaßen Wettbewerbs- und Selektionsprozessen ausgesetzt. Aus dieser Konstellation ergeben sich für ländlich-periphere Regionen Kernherausforderungen, die sich in zwei sich ergänzenden strategischen Ansätzen manifestieren: eine mitnehmende Basisstrategie und eine flankierende Profilierungsstrategie. Der Beitrag der räumlichen Planung zur Steuerung der wissensgesellschaftlich relevanten Veränderungsprozesse beschränkt sich weitgehend auf folgende Funktionen: Sensibilisierung für räumliche Zusammenhänge, Organisation räumlichen Wandels und Umsetzungsbegleitung sowie damit verbunden Interessenausgleich der vielen unterschiedlichen Akteure einer Region.The heuristics of a three-dimensional knowledge society has been addressed and further developed in this volume. The social, economic and technical dimensions are differentiated and structured in accordance to characteristic manifestations such as individual competences, collective learning processes, knowledge as an economic factor, centrality, mobility, or integration in global institutional systems. These structuring elements provide the basis for the choice of in-depth studies in the rural, peripherally located area of northeast Germany with regard to regional growth cores in Brandenburg, health infrastructure, mobility offerings, access to communication technologies, and educational networks and educational landscapes. Regarding the comparison of theory and practice, of the heuristic model and the case studies, the choice of examples is not representative and does not cover the entire diversity and complexity of the knowledge society in rural peripheral areas. However, the case studies do provide an initial picture of how the knowledge society finds expression in these areas, the strategic challenges it brings with it, and the role that spatial planning can play in necessary strategic approaches. The shortage of skilled workers seems to be a central feature of and a challenge for the knowledge society in the rural periphery. The sharp, theoretically founded differentiation made between the dimensions cannot be sustained in this form in practice. Thus the innovations characteristic for the economic dimension are not feasible without social learning processes and bridging institutional systems, which are here regarded as part of the technical dimension. Furthermore, these processes and systems will only actually function when people and knowledge are mobilised and knowledge networks develop. The peripherally located rural areas are just as much part of the knowledge society as the metropolitan areas. Both types of area are thus similarly subject to processes of competition and selection. This constellation gives rise to key challenges for rural peripheral regions that manifest themselves in two complementary strategic approaches: a participatory basic strategy and a flanking strategy focused on profiling. The contribution of spatial planning to the processes of change related to the knowledge society is thus mainly restricted on raising awareness of spatial interrelations, organising spatial transformation and guiding implementation while ensuring the interests of the many different regional actors

A multi-center study of their physicochemical characteristics, cell culture and in vivo experiments

PVP-capped silver nanoparticles with a diameter of the metallic core of 70 nm, a hydrodynamic diameter of 120 nm and a zeta potential of −20 mV were prepared and investigated with regard to their biological activity. This review summarizes the physicochemical properties (dissolution, protein adsorption, dispersability) of these nanoparticles and the cellular consequences of the exposure of a broad range of biological test systems to this defined type of silver nanoparticles. Silver nanoparticles dissolve in water in the presence of oxygen. In addition, in biological media (i.e., in the presence of proteins) the surface of silver nanoparticles is rapidly coated by a protein corona that influences their physicochemical and biological properties including cellular uptake. Silver nanoparticles are taken up by cell-type specific endocytosis pathways as demonstrated for hMSC, primary T-cells, primary monocytes, and astrocytes. A visualization of particles inside cells is possible by X-ray microscopy, fluorescence microscopy, and combined FIB/SEM analysis. By staining organelles, their localization inside the cell can be additionally determined. While primary brain astrocytes are shown to be fairly tolerant toward silver nanoparticles, silver nanoparticles induce the formation of DNA double-strand-breaks (DSB) and lead to chromosomal aberrations and sister-chromatid exchanges in Chinese hamster fibroblast cell lines (CHO9, K1, V79B). An exposure of rats to silver nanoparticles in vivo induced a moderate pulmonary toxicity, however, only at rather high concentrations. The same was found in precision-cut lung slices of rats in which silver nanoparticles remained mainly at the tissue surface. In a human 3D triple-cell culture model consisting of three cell types (alveolar epithelial cells, macrophages, and dendritic cells), adverse effects were also only found at high silver concentrations. The silver ions that are released from silver nanoparticles may be harmful to skin with disrupted barrier (e.g., wounds) and induce oxidative stress in skin cells (HaCaT). In conclusion, the data obtained on the effects of this well-defined type of silver nanoparticles on various biological systems clearly demonstrate that cell-type specific properties as well as experimental conditions determine the biocompatibility of and the cellular responses to an exposure with silver nanoparticles

Mobility in a Globalised World 2013

The term mobility has different meanings in the following science disciplines. In economics, mobility is the ability of an individual or a group to improve their economic status in relation to income and wealth within their lifetime or between generations. In information systems and computer science, mobility is used for the concept of mobile computing, in which a computer is transported by a person during normal use. Logistics creates by the design of logistics networks the infrastructure for the mobility of people and goods. Electric mobility is one of today‘s solutions from engineering perspective to reduce the need of energy resources and environmental impact. Moreover, for urban planning, mobility is the crunch question about how to optimise the different needs for mobility and how to link different transportation systems. In this publication we collected the ideas of practitioners, researchers, and government officials regarding the different modes of mobility in a globalised world, focusing on both domestic and international issues. We are grateful for the academic hospitality at the Stuttgart Media University for our conference 2013 "Mobility in a globalised world" in September 2013. We would like to thank Prof. Dr Johannes Maucher and Dr. Heiko Roßnagel for their technical support during our sojourn in Stuttgart

Mobility in a Globalised World 2012

The term mobility has different meanings in the following science disciplines. In economics, mobility is the ability of an individual or a group to improve their economic status in relation to income and wealth within their lifetime or between generations. In information systems and computer science, mobility is used for the concept of mobile computing, in which a computer is transported by a person during normal use. By designing logistics networks, logistics creates the infrastructure for the mobility of people and goods. Electric mobility is one of today’s solutions from an engineering perspective to the problem of reducing the need for energy resources and environmental impact. Finally, for urban planning, mobility is the crunch question as to how to optimise the different needs for mobility and how to link different transportation systems. In this publication we have collected the ideas of practitioners, researchers, and government officials about the different modes of mobility in a globalised world, focusing on both domestic and international issues

Mobility in a Globalised World 2014

The term mobility has different meanings in the following science disciplines. In economics, mobility is the ability of an individual or a group to improve their economic status in relation to income and wealth within their lifetime or between generations. In information systems and computer science, mobility is used for the concept of mobile computing, in which a computer is transported by a person during normal use. Logistics creates by the design of logistics networks the infrastructure for the mobility of people and goods. Electric mobility is one of today’s solutions from engineering perspective to reduce the need of energy resources and environmental impact. Moreover, for urban planning, mobility is the crunch question about how to optimise the different needs for mobility and how to link different transportation systems. In this publication we collected the ideas of practitioners, researchers, and government officials regarding the different modes of mobility in a globalised world, focusing on both domestic and international issues