Comparative functional analysis of the adhesion and invasion factor YadA of enteropathogenic Yersiniae

Das multifunktionelle, afimbrilliäre Adhäsin YadA ist ein wichtiger Adhäsionsfaktor der enteropathogenen Bakterien Yersinia pseudotuberculosis und Yersinia enterocolitica. Es trägt durch die Bindung an Proteine der extrazellulären Matrix (EZM) maßgeblich zur Etablierung einer Infektion bei. Obwohl die YadA-Proteine beider Yersinia spp. (YadApstb und YadAent) sehr homolog sind, vermittelt nur YadApstb effiziente Invasion in Epithelzellen. Es konnte gezeigt werden, dass eine in der N-terminalen Kopfregion des YadApstb-Proteins lokalisierte Region von 31 Aminosäuren, die dem YadAent-Protein fehlt, essentiell für die YadApstb-vermittelte Invasion ist. Die Deletion dieser Domäne in YadApstb führt zu einem Verlust der Invasionsfähigkeit, während die adhäsiven Eigenschaften des Moleküls erhalten bleiben. Die Invasionsdomäne ist darüber hinaus für die aggregativen Eigenschaften und die Bindekapazität von YadA für Proteine der EZM entscheidend. Ihr Fehlen bewirkt einen Verlust der Fähigkeit Auto- und Hämagglutination zu induzieren, vermittelt demgegenüber jedoch eine deutlich gesteigerte Bindung an Kollagen und Laminin. YadApstb hingegen bindet hauptsächlich an Fibronektin, und es konnte nachgewiesen werden, dass die YadApstb-vermittelte Invasion nur auf Grundlage der Bindung an Fibronektin-gebundene a5b1-Integrine erfolgen kann. Darüber hinaus konnte gezeigt werden, dass die invasiven und aggregativen Eigenschaften des YadApstb-Proteins für die effiziente Besiedlung tiefer gelegener Gewebe und Organe während der Infektion von Bedeutung sind. Die Identifikation der YadApstb- Invasionsdomäne ermöglicht es, den Invasions- und Adhäsionsprozess deutlich voneinander abzugrenzen, so dass die Unterschiede der zu Grunde liegenden eukaryotischen Signaltransduktion erstmalig untersucht werden können. Hierfür wurde ein in vitro System etabliert, das es erlaubt, die Aktivierung der Signalmoleküle in der Wirtszelle unbeeinflusst von anderen bakteriellen Faktoren zu analysieren.The multifunctional, afimbrial adhesin YadA is the major adhesion factor of the enteropathogenic bacteria Yersinia pseudotuberculosis and Yersinia enterocolitica. It contributes to the establishment of an infection by promoting tight adherence to extracellular matrix (ECM) proteins of the host cell. Although the YadA proteins of both Yersinia spp. (YadApstb and YadAent) are highly homologous, only YadApstb promotes efficient invasion into epithelial cells. Functional and structural analyses of YadApstb and YadAent revealed that an unique N-terminal region of 31 amino acids of YadApstb, which is absent in YadAent, is crucial for the YadApstb-mediated invasion. A deletion of this domain in YadApstb abrogates cell invasion, while the adhesion remains unaffected. The uptake domain also affects the aggregation behaviour and the specificity of ECM substrate binding of YadA. The loss of this motif causes YadA variants, which are deficient in auto- and hemagglutination but promote strong binding to collagen and laminin. YadApstb however exhibits a high binding efficiency for fibronectin and it was shown that the YadApstb-mediated invasion occurs only via fibronectin-bound a5b1-integrins. Furthermore, it was demonstrated that the invasive and aggregative properties of YadApstb contribute to the efficient colonization of deeper tissues and organs during infection. The identification of the uptake domain dissects invasion from adhesion and allows for the first time the analysis of the differences in the host cell signalling during these processes. For this purpose an in vitro system was developed, which facilitates an analysis unaffected by other bacterial factors

Wie beeinflusst eine vegane Ernährung Parameter der Kraftleistung von Sportlern?

Hintergrund: Die vegane Ernährungsweise erlebt in den letzten Jahren einen steigenden Interessenszuwachs. Aufgrund einer potenziell kritischen Nährstoffaufnahme steht die rein pflanzliche Ernährungunter besonderer Kritik. Es ist fraglich, ob die vegane Ernährungsweise den erhöhten Nährstoffbedarf von Kraftsportathleten deckt und somit die Kraftleistung im selben Ausmaß unterstützt, wie bei omnivorer Ernährungsweise. Die vorliegende Bachelorarbeit hat das Ziel die Datenlage zum Einfluss einer veganen Ernährung auf die Kraftleistung näher zu beleuchten. Methode: Es wird eine umfassende Literaturrecherche in den Datenbanken „PubMed“ und „Google Scholar“ durchgeführt. Veröffentlichungen, welche die Auswirkungen einer veganen Ernährung auf Parameter der Kraftleistung untersuchen, werden in die Recherche eingeschlossen. Ergebnisse: Eine vegane Ernährung zeichnet sich durch einen erhöhten Kohlenhydrat- und Ballaststoffanteil in der Nahrung und einen geringeren Konsum von Proteinen, Cholesterin und gesättigten Fettsäuren im Vergleich zur omnivoren Ernährung, aus. Durch die Kombination vielfältiger Proteinquellen ist es veganen Athleten möglich den erhöhten Bedarf an Proteinen und Aminosäuren, welche für die Kraftleistung essenziell sind, zu decken. Signifikante Unterschiede zwischen veganer und omnivorer Ernährungsform in den Parametern der Kraftleistung sind nicht zu verzeichnen. Fazit: Die evidenzbasierte Datenlage zur Thematik ist zu gering, um aussagekräftige Schlüsse ziehen zu können. Es benötigt weitere, besonders evidenzbasierte Studien. Nach jetzigem Stand lässt sich vermuten, dass eine vegane Ernährung weder ausschlaggebende Vorteile noch Nachteile auf die Kraftleistung von Sportlern hat.Background: The vegan diet has experienced an increasing interest in the recent years. Due to a potentially critical nutrient intake, the plant-based diet is criticized. It is questionable whether the vegan diet covers the increased nutrient requirements of strength athletes and thus supports strength performance to the same level as an omnivorous diet. The aim of this bachelor thesis is to examine the data on the influence of a vegan diet on strength performance. Method: A comprehensive literature research in the databases "PubMed" and "Google Scholar" was conducted. Publications investigating the effects of a vegan diet on parameters of strength performance are included in the search. Results: A vegan diet is characterized by an increased carbohydrate and fiber intake and a lower consumption of proteins, cholesterol and saturated fatty acids compared to an omnivorous diet. By combining multiple protein sources, vegan athletes are able to meet the increased requirements for proteins and amino acids that are essential for strength performance. Significant differences between vegan and omnivorous diets in the parameters of strength performance are not observed. Conclusion: The evidence-based data on this topic is too limited to provide meaningful conclusions. Further, especially evidence-based studies are needed. Currently, it can be assumed that a vegan diet has neither significant advantages nor disadvantages on the strength performance of athletes

Assessment of mixture toxicity of (tri)azoles and their hepatotoxic effects in vitro by means of omics technologies.

Seeger B, Mentz A, Knebel C, et al. Assessment of mixture toxicity of (tri)azoles and their hepatotoxic effects in vitro by means of omics technologies. Archives of toxicology. 2019;93(8):2321-2333.Consumers are constantly exposed to chemical mixtures such as multiple residues of different pesticides via the diet. This raises questions concerning potential combination effects, especially because these substances are tested for regulatory purposes on an individual basis. With approximately 500 active substances approved as pesticides, there are too many possible combinations to be tested in standard animal experiments generally requested for regulatory purposes. Therefore, the development of in vitro tools and alternative testing strategies for the assessment of mixture effects is extremely important. As a first step in the development of such in vitro tools, we used (tri)azoles as model substances in a set of different cell lines derived from the primary target organ of these substances, the liver (human: HepaRG, rat: H4IIE). Concentrations were reconciled with measured tissue concentrations obtained from in vivo experiments to ensure comparable effect levels. The effects of the substances were subsequently analyzed by transcriptomics and metabolomics techniques and compared to data from corresponding in vivo studies. The results show that similar toxicity pathways are affected by substances and combinations, thus indicating a similar mode of action and additive effects. Two biomarkers obtained by the approach, CAR and Cyp1A1, were used for mixture toxicity modeling and confirmed the concentration-additive effects, thus supporting the selected testing strategy and raising hope for the development of in vitro methods suitable to detect combination effects and prioritize mixtures of concern for further testing

Trimeric Autotransporter Adhesin-Dependent Adherence of Bartonella henselae, Bartonella quintana, and Yersinia enterocolitica to Matrix Components and Endothelial Cells under Static and Dynamic Flow Conditions ▿ †

Trimeric autotransporter adhesins (TAAs) are important virulence factors of Gram-negative bacteria responsible for adherence to extracellular matrix (ECM) and host cells. Here, we analyzed three different TAAs (Bartonella adhesin A [BadA] of Bartonella henselae, variably expressed outer membrane proteins [Vomps] of Bartonella quintana, and Yersinia adhesin A [YadA] of Yersinia enterocolitica) for mediating bacterial adherence to ECM and endothelial cells. Using static (cell culture vials) and dynamic (capillary flow chambers) experimental settings, adherence of wild-type bacteria and of the respective TAA-negative strains was analyzed. Under static conditions, ECM adherence of B. henselae, B. quintana, and Y. enterocolitica was strongly dependent on the expression of their particular TAAs. YadA of Y. enterocolitica did not mediate bacterial binding to plasma or cellular fibronectin under either static or dynamic conditions. TAA-dependent host cell adherence appeared more significant under dynamic conditions although the total number of bound bacteria was diminished compared to the number under static conditions. Dynamic models expand the methodology to perform bacterial adherence experiments under more realistic, bloodstream-like conditions and allow dissection of the biological role of TAAs in ECM and host cell adherence under static and dynamic conditions