Institut für Hygiene und Mikrobiologie
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Sonstige beteiligte Institutionen
- Broad Institute, USA (1)
- Department Pharmazie - Zentrum für Pharmaforschung, Ludwig-Maximilians-Universität München (1)
- Department of Hematology and Oncology, Sana Hospital Hof, Hof, Germany (1)
- Department of Laboratory Medicine and Medicine Huddinge, Karolinska Institutet and University Hospital, Stockholm, Sweden (1)
- Department of Medicine A, University Hospital of Münster, Münster, Germany (1)
- Instituto de Higiene, Universidad de la República, Montevideo, Uruguay (1)
- Instituto de Hygiene Montevideo, Uruguay (1)
- Krankenhaushygiene und Antimicrobial Stewardship (1)
- Krankenhaushygiene und Antimicrobial Stewardship (Universitätsklinikum) (1)
- Leibniz-Institut für Naturstoff-Forschung und Infektionsbiologie Hans-Knöll-Institut (1)
EU-Project number / Contract (GA) number
- 2016 FGR 0053 (1)
- 278864 (1)
- 715466 (1)
- 847507 (1)
Invasive aspergillosis (IA) is an infectious disease caused by the fungal pathogen Aspergillus fumigatus that mainly affects immunocompromised hosts. To investigate immune cell cross-talk during infection with A. fumigatus, we co-cultured natural killer (NK) cells and dendritic cells (DC) after stimulation with whole fungal structures, components of the fungal cell wall, fungal lysate or ligands for distinct fungal receptors. Both cell types showed activation after stimulation with fungal components and were able to transfer activation signals to the counterpart not stimulated cell type. Interestingly, DCs recognized a broader spectrum of fungal components and thereby initiated NK cell activation when those did not recognize fungal structures. These experiments highlighted the supportive function of DCs in NK cell activation. Furthermore, we focused on soluble DC mediated NK cell activation and showed that DCs stimulated with the TLR2/Dectin-1 ligand zymosan could maximally stimulate the expression of CD69 on NK cells. Thus, we investigated the influence of both receptors for zymosan, Dectin-1 and TLR2, which are highly expressed on DCs but show only minimal expression on NK cells. Specific focus was laid on the question whether Dectin-1 or TLR2 signaling in DCs is important for the secretion of soluble factors leading to NK cell activation. Our results show that Dectin-1 and TLR2 are negligible for NK cell activation. We conclude that besides Dectin-1 and TLR2 other receptors on DCs are able to compensate for the missing signal.
Seasonal Occurrence and Carbapenem Susceptibility of Bovine Acinetobacter baumannii in Germany
(2019)
Acinetobacter baumannii is one of the leading causes of nosocomial infections in humans. To investigate its prevalence, distribution of sequence types (STs), and antimicrobial resistance in cattle, we sampled 422 cattle, including 280 dairy cows, 59 beef cattle, and 83 calves over a 14-month period. Metadata, such as the previous use of antimicrobial agents and feeding, were collected to identify putative determining factors. Bacterial isolates were identified via MALDI-TOF/MS and PCR, antimicrobial susceptibility was evaluated via VITEK2 and antibiotic gradient tests, resistance genes were identified by PCR. Overall, 15.6% of the cattle harbored A. baumannii, predominantly in the nose (60.3% of the A. baumannii isolates). It was more frequent in dairy cows (21.1%) than in beef cattle (6.8%) and calves (2.4%). A seasonal occurrence was shown with a peak between May and August. The rate of occurrence of A. baumannii was correlated with a history of use of 3rd generation cephalosporins in the last 6 months prior to sampling Multilocus sequence typing (Pasteur scheme) revealed 83 STs among 126 unique isolates. Nine of the bovine STs have previously been implicated in human infections. Besides known intrinsic resistance of the species, the isolates did not show additional resistance to the antimicrobial substances tested, including carbapenems. Our data suggest that cattle are not a reservoir for nosocomial A. baumannii but carry a highly diverse population of this species. Nevertheless, some STs seem to be able to colonize both cattle and humans.
The Role of Sphingosine 1-phosphate and S1PR1-3 in the Pathophysiology of Meningococcal Meningitis
(2024)
Neisseria meningitidis (N. meningitidis) is an obligate human pathogen which causes live-threatening sepsis and meningitis. The fatality rate after meningococcal infection is high and surviving patients often suffer from severe sequelae. To cause meningitis, N. meningitidis must overcome the endothelium of the blood-brain barrier. The bacterium achieves this through the interaction with endothelial surface receptors leading to alternations of the cellular metabolism and signaling, which lastly results in cellular uptake and barrier traversal of N. meningitidis. Sphingosine 1-phosphate (S1P) is a lipid mediator that belongs to the class of sphingolipids and regulates the integrity of the blood-brain barrier through the interaction with its cognate receptors S1P receptors 1-3 (S1PR1-3).
In this study, high performance liquid chromatography coupled with mass spectrometry (LC-MS/MS) was used to generate a time-resolved picture of the sphingolipid metabolism in a brain endothelial cell line (hCMEC/D3) upon meningococcal infection. Among various changes, S1P was elevated in the cellular compartment as well as in the supernatant of infected hCMEC/D3s. Analysis of mRNA expression in infected hCMEC/D3s with quantitative real-time polymerase chain reaction (RT-qPCR) revealed that the increase in S1P could be attributed to the enhanced expression of the S1P-generating enzyme sphingosine kinase 1 (SphK1). Antibody-based detection of SphK1 protein or phosphorylation at SphK1 residue Serine 225 in hCMEC/D3 plasma membrane fractions via Western Blot revealed that N. meningitidis also induced SphK1 phospho-activation and recruitment to the plasma membrane. Importantly, recruitment of SphK1 to the plasma membrane increases the probability of substrate encounter, thus elevating SphK activity. Enhanced SphK activity was also reflected on a functional level, as detected by a commercially available ATP depletion assay used for measuring the enzymatic activity of SphK. Infection of hCMEC/D3 cells with pilus-deficient mutants resulted in a lower SphK activation compared to the N. meningitidis wild type strain. hCMEC/D3 treatment with pilus-enriched protein fractions showed SphK activation similar to the infection with living bacteria and could be ascribed to pilus interaction with the membrane-proximal domain of cellular surface receptor CD147. Inhibition of SphK1 or SphK2 through pre-treatment with specific inhibitors or RNA interference reduced uptake of N. meningitidis into hCMEC/D3 cells, as measured with Gentamicin protection assays. Released S1P induced the phospho-activation of epidermal growth factor receptor (EGFR) via S1PR2 activation, whose expression was also increasing during infection. Furthermore, S1PR2 blockage had a preventive effect on bacterial invasion into hCMEC/D3 cells. On the contrary, activation of S1PR1+3 also reduced bacterial uptake, indicating an opposing regulatory role of S1PR1+3 and S1PR2 during N. meningitidis uptake. Moreover, SphK2 inhibition prevented inflammatory cytokine expression as well as release of interleukin-8 after N. meningitidis infection. Taken together, this study demonstrates the central role of S1P and its cognate receptors S1PR1-3 in the pathophysiology of meningococcal meningitis.
Die 2009 erstmals entdeckte Spezies C. auris erlangte binnen kürzester Zeit zunehmend weltweite Aufmerksamkeit. Vor allem die Tendenz der Multiresistenzentwicklung und das rasche Auslösen von nosokomialen Infektionen erschweren den Umgang und die Therapie von C. auris Infektionen im Vergleich zu anderen Candida Spezien. Diese Dissertationsarbeit umfasst eine systematische Resistenzanalyse der im NRZMyk vorhandenen Stammsammlung aus C. auris und C. parapsilosis Isolaten, um Aufschluss über den Wirkmechanismus von Amphotericin B in Hefepilzen zu erlangen. Anhand der zunächst durchgeführten Amphotericin B-Resistenztestungen kristallisierten sich CAU37 und CAU43 mit MHK-Werten bis zu 12 µg/ml als stark Amphotericin B-resistente Isolate heraus. Die Analyse der Sequenzierungsergebnisse zeigte bei beiden Stämmen eine Mutation im ERG4 Gen an Position 576, welche nicht eindeutig als alleinige Ursache für die verminderte Amphotericin B-Empfindlichkeit festgelegt werden konnte. Dennoch wurde im Rahmen eines Survival Assays bei beiden Amphotericin B-resistenten Isolaten anfänglich eine konzentrationsabhängige Aktivität gegenüber Amphotericin B festgestellt, bevor ein Nachwachsen der Kulturen beobachtet wurde. Somit wurde die Vermutung aufgestellt, dass lediglich ein Teil der aufgebrachten Candida-Zellen abgetötet wird und dies in einer Vermehrung der überlebenden Zellen resultiert. Des Weiteren konnte im Rahmen von Resistenztestungen mit dem Sphingolipidinhibitor Myriocin nachgewiesen werden, dass vor allem in Amphotericin B-resistenten Isolaten eine deutliche Wirkungsverstärkung des Polyens hervorgerufen wird. Diese Sensitivitätssteigerung ist allgemein bei allen C. auris Isolaten zu beobachten, fällt bei resistenten Stämmen jedoch deutlich stärker aus. Hierdurch kam die Annahme auf, dass Amphotericin B-Resistenzen auch in möglichen Veränderungen des Sphingolipid-Haushaltes begründet sein könnten. Darüber hinaus scheint Myriocin keinen Einfluss auf Fluconazol-resistente oder FKS-mutierte Echinocandin-resistente C. auris Stämme zu haben. Das ebenfalls untersuchte und von Myriocin abgeleitete Medikament Fingolimod hatte jedoch ebenfalls keinen wirkungsverstärkenden Effekt. Allerdings reagierte ein Großteil der C. auris Isolate (57,6 %) sensitiv gegenüber dem neusten medizinisch bekannten Triazol Isavuconazol und es konnte erstmalig ein ECV-Wert von 0,03125 µg/ml festgelegt werden. Ein valider Vergleich von C. auris zu C. parapsilosis war aufgrund der mangelnden Anzahl an C. parapsilosis Isolaten jedoch nicht möglich
Die alveoläre Echinokokkose (AE), die durch den Fuchsbandwurm Echinococcus multilocularis verursacht wird, ist eine seltene jedoch schwere und oft tödlich verlaufende Erkrankung. Aufgrund der späten Diagnosestellung sind kurative Behandlungsmethoden häufig nicht durchführbar und als einzige Behandlungsmöglichkeit bleibt eine lebenslange und nebenwirkungsreiche Therapie mit Benzimidazolen. Verbesserte Therapieoptionen durch die Entwicklung neuer Medikamente sind dringend notwendig. Hierfür kann es hilfreich sein die Biologie des Fuchsbandwurmes und die Kommunikationswege zwischen Parasit und Wirt zu verstehen. Bereits in vorherigen Arbeiten als auch in dieser Arbeit erwiesen sich evolutionsgeschichtlich konservierte Signalwege als Kommunikationsweg zwischen dem Fuchsbandwurm und seinem Wirt von zentraler Rolle.
Die Entschlüsselung des Echinococcus-Genoms gab Hinweise darauf, dass ein Mitglied der Tumornekrosefaktor-Rezeptor-Superfamilie, jedoch kein endogener TNF α ähnlicher Ligand im Genom kodiert wird. Ein Mitglied der TNFR-Superfamilie des Fuchsbandwurmes (EmTNFR) wurde in dieser Arbeit als membranständiger Rezeptor mit einer intrazellulären Todesdomäne (DD) und hoher Ähnlichkeit zum humanen Typ 16 der TNF-Rezeptor-Superfamilie, auch 〖p75〗^NTR genannt, charakterisiert. Sowohl in bioinformatischen als auch in Sequenzanalysen wurden drei alternative Splicing-Formen von emtnfr (emtnfr, emtnfr-v2 und emtnfr-v3) nachgewiesen. emtnfr-v2 entsteht durch Alternatives Splicing und kodiert ein Protein, das keine intrazelluläre Todesdomäne besitzt. emtnfr-v3 verwendet einen alternativen Transkriptionstart und wird von den letzten 3 Exons von emtnfr kodiert. emtnfr-v3, kodiert ein Protein ohne extrazelluläre Region, aber mit intrazellulärer Todesdomäne. Ein löslicher TNF-Rezeptor konnte auf Proteinebene nicht nachgewiesen werden. Aufgrund von phylogenetischen Analysen und der Rezeptor-Struktur ist zu vermuten, dass EmTNFR ein p75NTR Homolog ist und damit der ursprünglichen Form der TNF-Rezeptoren entspricht. Mitglieder eines intrazellulären TNF-Signalweges wurden in bioinformatischen Analysen beim Fuchsbandwurm E. multilocularis identifiziert.
Expressionsuntersuchungen zeigten sowohl in Trankriptomdaten als auch auf Proteinebene eine starke Expression von EmTNFR in Primärzellen und im Metazestoden (MZ), dem pathogenen Stadium für den Zwischenwirt. Echinococcus-Stammzellkulturen zeigten nach RNA-Interferenz-basiertem Knockdown des EmTNFR-kodierenden Gens deutliche Entwicklungsdefekte. Des Weiteren zeigten Echinococcus-Stammzellkulturen nach einer Behandlung mit TNF-α, einem potentiellen Liganden des TNF-Rezeptors und einem zentralen Zytokin in der Immunabwehr des Zwischenwirtes, Entwicklungsfortschritte, wie eine verbesserte Bildung von MZ aus Stammzellen. Zusätzlich wurde in whole-mount in situ Hybridisierungs-Versuchen eine ubiquitäre Expression von emtnfr in der Germinalschicht des MZ sowie eine Spezifität von emtnfr für den MZ, welcher ursächlich für die AE ist, nachgewiesen. Somit scheinen sowohl EmTNFR als auch TNF-α eine wichtige Funktion bei der Entwicklung und Etablierung des Fuchsbandwurmes während der frühen Phase der Infektion des Zwischenwirtes zu haben. TNF-α könnte ein weiterer Faktor für den ausgeprägten Organtropismus des Parasiten zur Leber sein, denn dort bestehen durch Kupfferzellen produzierte hohe lokale Konzentration von TNF-α.
Zusammenfassend deuten die hier erarbeiteten Daten darauf hin, dass EmTNFR über die Bindung von Wirts-TNF-α bei der frühen Entwicklung des Echincoccus-Metazestoden eine Rolle spielt.
In most organisms, ribosomal RNA (rRNA) contributes to >85% of total RNA. Thus, to obtain useful information from RNA-sequencing (RNA-seq) analyses at reasonable sequencing depth, typically, mature polyadenylated transcripts are enriched or rRNA molecules are depleted. Targeted depletion of rRNA is particularly useful when studying transcripts lacking a poly(A) tail, such as some non-coding RNAs (ncRNAs), most bacterial RNAs and partially degraded or immature transcripts. While several commercially available kits allow effective rRNA depletion, their efficiency relies on a high degree of sequence homology between oligonucleotide probes and the target RNA. This restricts the use of such kits to a limited number of organisms with conserved rRNA sequences. In this study we describe the use of biotinylated oligos and streptavidin-coated paramagnetic beads for the efficient and specific depletion of trypanosomal rRNA. Our approach reduces the levels of the most abundant rRNA transcripts to less than 5% with minimal off-target effects. By adjusting the sequence of the oligonucleotide probes, our approach can be used to deplete rRNAs or other abundant transcripts independent of species. Thus, our protocol provides a useful alternative for rRNA removal where enrichment of polyadenylated transcripts is not an option and commercial kits for rRNA are not available.
Migration and interactions of immune cells are routinely studied by time-lapse microscopy of in vitro migration and confrontation assays. To objectively quantify the dynamic behavior of cells, software tools for automated cell tracking can be applied. However, many existing tracking algorithms recognize only rather short fragments of a whole cell track and rely on cell staining to enhance cell segmentation. While our previously developed segmentation approach enables tracking of label-free cells, it still suffers from frequently recognizing only short track fragments. In this study, we identify sources of track fragmentation and provide solutions to obtain longer cell tracks. This is achieved by improving the detection of low-contrast cells and by optimizing the value of the gap size parameter, which defines the number of missing cell positions between track fragments that is accepted for still connecting them into one track. We find that the enhanced track recognition increases the average length of cell tracks up to 2.2-fold. Recognizing cell tracks as a whole will enable studying and quantifying more complex patterns of cell behavior, e.g. switches in migration mode or dependence of the phagocytosis efficiency on the number and type of preceding interactions. Such quantitative analyses will improve our understanding of how immune cells interact and function in health and disease.
Background
Increasing incidence of invasive infections caused by rare fungi was observed over the recent years.
Case
Here, we describe the first reported case of an infection caused by the thermophilic mold Talaromyces thermophilus. Cultivation and, hence, identification of this fastidious organism is challenging since standard incubation conditions are not sufficient. Retrospective analysis of patient samples and in vitro experiments demonstrated that testing for fungal antigens, i.e., the cell wall components galactomannan and β-1,3-D-glucan, is a promising tool.
Ultra-high field cardiac MRI in large animals and humans for translational cardiovascular research
(2023)
A key step in translational cardiovascular research is the use of large animal models to better understand normal and abnormal physiology, to test drugs or interventions, or to perform studies which would be considered unethical in human subjects. Ultrahigh field magnetic resonance imaging (UHF-MRI) at 7 T field strength is becoming increasingly available for imaging of the heart and, when compared to clinically established field strengths, promises better image quality and image information content, more precise functional analysis, potentially new image contrasts, and as all in-vivo imaging techniques, a reduction of the number of animals per study because of the possibility to scan every animal repeatedly. We present here a solution to the dual use problem of whole-body UHF-MRI systems, which are typically installed in clinical environments, to both UHF-MRI in large animals and humans. Moreover, we provide evidence that in such a research infrastructure UHF-MRI, and ideally combined with a standard small-bore UHF-MRI system, can contribute to a variety of spatial scales in translational cardiovascular research: from cardiac organoids, Zebra fish and rodent hearts to large animal models such as pigs and humans. We present pilot data from serial CINE, late gadolinium enhancement, and susceptibility weighted UHF-MRI in a myocardial infarction model over eight weeks. In 14 pigs which were delivered from a breeding facility in a national SARS-CoV-2 hotspot, we found no infection in the incoming pigs. Human scanning using CINE and phase contrast flow measurements provided good image quality of the left and right ventricle. Agreement of functional analysis between CINE and phase contrast MRI was excellent. MRI in arrested hearts or excised vascular tissue for MRI-based histologic imaging, structural imaging of myofiber and vascular smooth muscle cell architecture using high-resolution diffusion tensor imaging, and UHF-MRI for monitoring free radicals as a surrogate for MRI of reactive oxygen species in studies of oxidative stress are demonstrated. We conclude that UHF-MRI has the potential to become an important precision imaging modality in translational cardiovascular research.
Psychosocial factors affect mental health and health-related quality of life (HRQL) in a complex manner, yet gender differences in these interactions remain poorly understood. We investigated whether psychosocial factors such as social support and personal and work-related concerns impact mental health and HRQL differentially in women and men during the first year of the COVID-19 pandemic. Between June and October 2020, the first part of a COVID-19-specific program was conducted within the “Characteristics and Course of Heart Failure Stages A-B and Determinants of Progression (STAAB)” cohort study, a representative age- and gender-stratified sample of the general population of Würzburg, Germany. Using psychometric networks, we first established the complex relations between personal social support, personal and work-related concerns, and their interactions with anxiety, depression, and HRQL. Second, we tested for gender differences by comparing expected influence, edge weight differences, and stability of the networks. The network comparison revealed a significant difference in the overall network structure. The male (N = 1370) but not the female network (N = 1520) showed a positive link between work-related concern and anxiety. In both networks, anxiety was the most central variable. These findings provide further evidence that the complex interplay of psychosocial factors with mental health and HRQL decisively depends on gender. Our results are relevant for the development of gender-specific interventions to increase resilience in times of pandemic crisis.