Zur Initiation, Progression und Chronifikation des allergischen Asthma bronchiale

Das allergische Asthma ist eine chronisch entzündliche Erkrankung der Atemwege, die mit einer erhöhten Mukusproduktion, verschiedenen strukturellen Veränderungen der Atemwege und der Entwicklung einer Atemwegshyperreagibilität einhergeht. Die Vielfalt der Faktoren, die zur Initiation, Progression und Chronifizierung dieser Erkrankung beitragen ist ebenso komplex, wie ihr Phänotyp. In epidemiologischen Studien konnten bislang neben genetischen Faktoren auch Umweltfaktoren, wie der Lebens- und Hygienestandard, mit der Entwicklung dieser Erkrankung assoziiert werden. Daneben wurden im Rahmen der Hygiene-Hypothese Einflüsse identifiziert, die eher mit einem erniedrigten Risiko für die Entwicklung dieser Erkrankung einhergehen. Ganz besonders kontrovers wird in diesem Zusammenhang die Rolle viraler Infektionen der Atemwege beschrieben, wie sie durch das Respiratory Syncytial Virus (RSV) oder Rhinoviren verursacht werden. Solche Infektionen verursachen zumeist eine Exazerbation des bereits etablierten Asthmas, werden allerdings, zumal wenn sie im Kindesalter auftreten, sowohl mit einer initialisierenden wie auch mit einer protektiven Wirkung in Zusammenhang gebracht. Möglicherweise spielen dabei virale Toll-like Rezeptor- (TLR-) Liganden, wie virale einzel- bzw. doppelsträngige RNA eine bedeutende Rolle. Im Rahmen der vorliegenden Arbeit wurde speziell die Wirkung dieser TLR-3- bzw. TLR-7-Liganden auf die allergische Sensibilisierungs- bzw. Entzündungsreaktion untersucht. Im Mausmodell für das allergische Asthma konnte durch die systemische Applikation von synthetische TLR-3- oder TLR-7-Liganden die allergische Sensibilisierungsreaktion vollständig verhindert werden. Bei bereits erfolgter allergischer Sensibilisierung war die sekundäre Entzündungsreaktion in der Lunge nach Allergen-Rechallenge deutlich vermindert, wenn zuvor virale TLR-Liganden appliziert wurden. Sowohl die Infiltration eosinophiler Granulozyten, wie auch der Lymphozyten in das Lungengewebe als auch die bronchiale Hyperreagibilität waren signifikant erniedrigt. Daneben fanden sich Hinweise auf die Initiation einer allergenspezifischen TH1-Antwort. Da nach intra-peritonealer Injektion synthetischer TLR-3- bzw. TLR-7-Liganden Peritonealmakrophagen mit der Produktion von Interleukin 12 (IL-2) reagierten, wurde weiterhin die Rolle von IL-12 in diesem Zusammenhang näher charakterisiert. In sensibilisierten IL-12p35 defizienten Tieren hatte die Applikation viraler TLR-Liganden keine Verminderung der allergischen Entzündungsreaktion in der Lunge zur Folge. Auch die Atemwegshyperreagibilität blieb unverändert. Somit könnte die protektive Wirkung viraler Infektionen im Kindesalter auf eine durch virale TLR-Liganden induzierte TH1-Antwort basieren, die auf eine allergenspezifische TH2-Antwort gegenregulatorisch wirkt. Dieser Effekt scheint zumindest zum Teil durch IL-12 mediiert zu sein. Um die Rolle weiterer Faktoren innerhalb des Chronifizierungsprozesses des allergischen Asthmas zu charakterisieren wurde innerhalb der vorliegenden Arbeit ein Mausmodell etabliert, das den Phänotyp dieser Erkrankung möglichst komplett widerspiegelt. Durch eine zwölf-wöchige Allergenexposition wurde in sensibilisierten Mäusen eine chronische Entzündung der Atemwege induziert, die lymphozyten-domininiert ist und über einen Zeitraum von mindestens sechs Wochen nach Allergenkontakt persistiert. Die chronische Atemwegsentzündung ist dabei mit umfangreichen strukturellen Veränderungen der Atemwege, wie einer subepithelialen Fibrose, einer Becherzellhyperplasie und dem vermehrten Vorkommen von Fibroblasten und Myofibroblasten in der Atemwegswand assoziiert. Im Gegensatz zu vergleichbaren Modellen waren wiesen diese Tiere eine deutlich verstärkte Atemwegshyperreabilität sowie eine persistierende Atemweflusslimitation auf. In diesem Modell wurde nach vierwöchiger Allergnprovokation, die eine profunde Atemwegsentzündung allerdings ohne strukturelle Atemwegsveränderungen hervorrief, die weitere Infiltration eosinophiler Graulozyten durch die Applikation eines CCR-3-Antagonisten verhindert, um die Rolle dieser Zellen innerhalb des Chronifizierungsprozesses zu untersuchen. Durch die Applikation des CCR-3-Antagonisten konnte nicht nur die Infiltration eosinophiler Granulozyten, sondern auch eine subepitheliale Fibrose verhindert werden. Weiterhin zeigten diese Tiere eine erhebliche Verbesserung der Atemwegsreabilität. Somit spielen eosinophile Granulozyten eine entscheidende Rolle innerhalb der Prozesse, die sowohl in einem strukturellen Umbau der Atemwege wie auch in einer gesteigerten Atemwegsreagibilität resultieren

Abortive Autophagy Induces Endoplasmic Reticulum Stress and Cell Death in Cancer Cells

Autophagic cell death or abortive autophagy has been proposed to eliminate damaged as well as cancer cells, but there remains a critical gap in our knowledge in how this process is regulated. The goal of this study was to identify modulators of the autophagic cell death pathway and elucidate their effects on cellular signaling and function. The result of our siRNA library screenings show that an intact coatomer complex I (COPI) is obligatory for productive autophagy. Depletion of COPI complex members decreased cell survival and impaired productive autophagy which preceded endoplasmic reticulum stress. Further, abortive autophagy provoked by COPI depletion significantly altered growth factor signaling in multiple cancer cell lines. Finally, we show that COPI complex members are overexpressed in an array of cancer cell lines and several types of cancer tissues as compared to normal cell lines or tissues. In cancer tissues, overexpression of COPI members is associated with poor prognosis. Our results demonstrate that the coatomer complex is essential for productive autophagy and cellular survival, and thus inhibition of COPI members may promote cell death of cancer cells when apoptosis is compromised

Protein Signature of Lung Cancer Tissues

Lung cancer remains the most common cause of cancer-related mortality. We applied a highly multiplexed proteomic technology (SOMAscan) to compare protein expression signatures of non small-cell lung cancer (NSCLC) tissues with healthy adjacent and distant tissues from surgical resections. In this first report of SOMAscan applied to tissues, we highlight 36 proteins that exhibit the largest expression differences between matched tumor and non-tumor tissues. The concentrations of twenty proteins increased and sixteen decreased in tumor tissue, thirteen of which are novel for NSCLC. NSCLC tissue biomarkers identified here overlap with a core set identified in a large serum-based NSCLC study with SOMAscan. We show that large-scale comparative analysis of protein expression can be used to develop novel histochemical probes. As expected, relative differences in protein expression are greater in tissues than in serum. The combined results from tissue and serum present the most extensive view to date of the complex changes in NSCLC protein expression and provide important implications for diagnosis and treatment

Genes but Not Genomes Reveal Bacterial Domestication of Lactococcus Lactis

BACKGROUND: The population structure and diversity of Lactococcus lactis subsp. lactis, a major industrial bacterium involved in milk fermentation, was determined at both gene and genome level. Seventy-six lactococcal isolates of various origins were studied by different genotyping methods and thirty-six strains displaying unique macrorestriction fingerprints were analyzed by a new multilocus sequence typing (MLST) scheme. This gene-based analysis was compared to genomic characteristics determined by pulsed-field gel electrophoresis (PFGE). METHODOLOGY/PRINCIPAL FINDINGS: The MLST analysis revealed that L. lactis subsp. lactis is essentially clonal with infrequent intra- and intergenic recombination; also, despite its taxonomical classification as a subspecies, it displays a genetic diversity as substantial as that within several other bacterial species. Genome-based analysis revealed a genome size variability of 20%, a value typical of bacteria inhabiting different ecological niches, and that suggests a large pan-genome for this subspecies. However, the genomic characteristics (macrorestriction pattern, genome or chromosome size, plasmid content) did not correlate to the MLST-based phylogeny, with strains from the same sequence type (ST) differing by up to 230 kb in genome size. CONCLUSION/SIGNIFICANCE: The gene-based phylogeny was not fully consistent with the traditional classification into dairy and non-dairy strains but supported a new classification based on ecological separation between "environmental" strains, the main contributors to the genetic diversity within the subspecies, and "domesticated" strains, subject to recent genetic bottlenecks. Comparison between gene- and genome-based analyses revealed little relationship between core and dispensable genome phylogenies, indicating that clonal diversification and phenotypic variability of the "domesticated" strains essentially arose through substantial genomic flux within the dispensable genome

Vascular permeability, vascular hyperpermeability and angiogenesis

The vascular system has the critical function of supplying tissues with nutrients and clearing waste products. To accomplish these goals, the vasculature must be sufficiently permeable to allow the free, bidirectional passage of small molecules and gases and, to a lesser extent, of plasma proteins. Physiologists and many vascular biologists differ as to the definition of vascular permeability and the proper methodology for its measurement. We review these conflicting views, finding that both provide useful but complementary information. Vascular permeability by any measure is dramatically increased in acute and chronic inflammation, cancer, and wound healing. This hyperpermeability is mediated by acute or chronic exposure to vascular permeabilizing agents, particularly vascular permeability factor/vascular endothelial growth factor (VPF/VEGF, VEGF-A). We demonstrate that three distinctly different types of vascular permeability can be distinguished, based on the different types of microvessels involved, the composition of the extravasate, and the anatomic pathways by which molecules of different size cross-vascular endothelium. These are the basal vascular permeability (BVP) of normal tissues, the acute vascular hyperpermeability (AVH) that occurs in response to a single, brief exposure to VEGF-A or other vascular permeabilizing agents, and the chronic vascular hyperpermeability (CVH) that characterizes pathological angiogenesis. Finally, we list the numerous (at least 25) gene products that different authors have found to affect vascular permeability in variously engineered mice and classify them with respect to their participation, as far as possible, in BVP, AVH and CVH. Further work will be required to elucidate the signaling pathways by which each of these molecules, and others likely to be discovered, mediate the different types of vascular permeability

Models of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a major global health problem and is predicted to become the third most common cause of death by 2020. Apart from the important preventive steps of smoking cessation, there are no other specific treatments for COPD that are as effective in reversing the condition, and therefore there is a need to understand the pathophysiological mechanisms that could lead to new therapeutic strategies. The development of experimental models will help to dissect these mechanisms at the cellular and molecular level. COPD is a disease characterized by progressive airflow obstruction of the peripheral airways, associated with lung inflammation, emphysema and mucus hypersecretion. Different approaches to mimic COPD have been developed but are limited in comparison to models of allergic asthma. COPD models usually do not mimic the major features of human COPD and are commonly based on the induction of COPD-like lesions in the lungs and airways using noxious inhalants such as tobacco smoke, nitrogen dioxide, or sulfur dioxide. Depending on the duration and intensity of exposure, these noxious stimuli induce signs of chronic inflammation and airway remodelling. Emphysema can be achieved by combining such exposure with instillation of tissue-degrading enzymes. Other approaches are based on genetically-targeted mice which develop COPD-like lesions with emphysema, and such mice provide deep insights into pathophysiological mechanisms. Future approaches should aim to mimic irreversible airflow obstruction, associated with cough and sputum production, with the possibility of inducing exacerbations

Model selection in historical research using approximate Bayesian computation

Formal Models and History Computational models are increasingly being used to study historical dynamics. This new trend, which could be named Model-Based History, makes use of recently published datasets and innovative quantitative methods to improve our understanding of past societies based on their written sources. The extensive use of formal models allows historians to reevaluate hypotheses formulated decades ago and still subject to debate due to the lack of an adequate quantitative framework. The initiative has the potential to transform the discipline if it solves the challenges posed by the study of historical dynamics. These difficulties are based on the complexities of modelling social interaction, and the methodological issues raised by the evaluation of formal models against data with low sample size, high variance and strong fragmentation. This work examines an alternate approach to this evaluation based on a Bayesian-inspired model selection method. The validity of the classical Lanchester's laws of combat is examined against a dataset comprising over a thousand battles spanning 300 years. Four variations of the basic equations are discussed, including the three most common formulations (linear, squared, and logarithmic) and a new variant introducing fatigue. Approximate Bayesian Computation is then used to infer both parameter values and model selection via Bayes Factors. Results indicate decisive evidence favouring the new fatigue model. The interpretation of both parameter estimations and model selection provides new insights into the factors guiding the evolution of warfare. At a methodological level, the case study shows how model selection methods can be used to guide historical research through the comparison between existing hypotheses and empirical evidence.Funding for this work was provided by the SimulPast Consolider Ingenio project (CSD2010-00034) of the former Ministry for Science and Innovation of the Spanish Government and the European Research Council Advanced Grant EPNet (340828).Peer ReviewedPostprint (published version

Policy-making power of opposition players

The organisation of legislative chambers and the consequences of parliamentary procedures have been among the most prominent research questions in legislative studies. Even though democratic elections not only lead to the formation of a government but also result in an opposition, the literature has mostly neglected oppositions and their role in legislative chambers. This paper proposes to fill this gap by looking at the legislative organisation from the perspective of opposition players. The paper focuses on the potential influence of opposition players in the policy-making process and presents data on more than 50 legislative chambers. The paper shows considerable variance of the formal power granted to opposition players. Furthermore, the degree of institutionalisation of opposition rights is connected to electoral systems and not necessarily correlated with other institutional characteristics such as regime type or the size of legislative chambers