Biology subjects

Nietzsche, S.

Publications and source records attributed to Nietzsche, S..

9 recordsLinked to original sources

bioRxiv2025

A plug-and-play transepithelial/transendothelial electric resistance (TEER)-upgraded organ-on-chip system to measure barrier dynamics in real-time

The integration of transepithelial/transendothelial electrical resistance (TEER) measurement into organ-on-chip (OoC) platforms provides a unique opportunity to monitor the integrity of biological barriers in real-time. This is particularly important for detecting rapid changes in the temporal dynamics of intercellular junctional complexes in response to drug compounds, changes in host-microbiota interactions, and pathological disease states. Conventional TEER systems usually require special cell culture components or complex measurement technology that must be operated by experienced users. In this work, we present an innovative approach that represents an extension of the existing and well-established Dynamic42 chip platform by integrating semi-transparent TEER electrodes with fixed positions in combination with a measurement device. Remarkably, this system works in a plug-and-play manner and can continuously measure TEER inside the incubator without user intervention or invasive manipulation. Other important features of OoC, such as the microfluidic perfusion, multicellular cell colonization, and the possibility of microscopic examination, are not compromised by the integrated TEER electrodes. To demonstrate the performance of this new TEER system, we leveraged a 3D intestine-on-chip (IoC) model and investigated TEER during model assembly, barrier disruption, and recovery as a proof-of-concept. Moreover, we compared and discussed this with data from a conventional end-point fluorescence permeability assay to demonstrate the benefits of real-time measurements with higher sensitivity.

bioengineering↗

bioRxiv2025

Galleria mellonella model for studying Gram-positive bacterial implant biofilms

Implant-associated biofilm infections, particularly those caused by Staphylococcus aureus and Enterococcus faecalis, present significant challenges in clinical settings, often necessitating surgical removal. This study investigates the potential of the invertebrate model Galleria mellonella for evaluating biofilm formation of S. aureus and E. faecalis clinical isolates, the leading causes of implant-associated infections. Utilizing expanded polytetrafluoroethylene (ePTFE) sutures as a surrogate for cardiac implants, we employed two biofilm formation methodologies reflecting the two main routes of implant infections: in vivo biofilm development within larvae mimicking hematogenous spread and pre-formed biofilm transplantation mimicking contamination during surgery. Scanning electron microscopy revealed complex biofilm structures for the biofilm formed inside of the larvae on implant, closely mimicking clinical conditions. Antibiotic treatments with vancomycin and rifampicin demonstrated significant reductions in bacterial biofilms, proving highly effective. The study highlights the G. mellonella models potential for preclinical biofilm research, offering a cost-effective and ethical alternative to vertebrate models while providing valuable insights into biofilm-related infections and their treatment.

microbiology↗

bioRxiv2024

Synergistic cross-kingdom host cell damage between Candida albicans and Enterococcus faecalis

The fungus Candida albicans and the Gram-positive bacterium Enterococcus faecalis share mucosal niches in the human body. As opportunistic pathogens, both are found to expand population size during dysbiosis, and can cause severe systemic infections in susceptible individuals. Here, we show that the presence of C. albicans results in increased host cell damage by E. faecalis. Furthermore, E. faecalis aggravates oropharyngeal candidiasis in mice. Increased damage is mediated by enterococcal cytolysin, and involves both physical interaction and altered glucose availability. Physical interaction promotes accumulation of bacteria on host cells, facilitating contact of cytolysin with host cells. Glucose depletion by the metabolic activity of the fungus sensitized host cells to cytolysin. This work illustrates how a complex interplay between fungi and bacteria can result in detrimental consequences for the host.

microbiology↗

bioRxiv2024

Telomerase RNA component knockout exacerbates S. aureus pneumonia by extensive inflammation and dysfunction of T cells

The telomerase RNA component (Terc) constitutes a non-coding RNA critical for telomerase function, commonly associated with aging and pivotal in immunomodulation during inflammation. Our study unveils heightened susceptibility to pneumonia caused by Staphylococcus aureus (S. aureus) in Terc knockout (Tercko/ko) mice compared to both young and old infected counterparts. The exacerbated infection in Tercko/ko mice correlates with heightened inflammation, manifested by elevated interleukin-1{beta} (IL-1{beta}) levels and activation of the NLR Family Pyrin Domain Containing 3 (NLRP3) inflammasome within the lung. Employing mRNA sequencing methods alongside in vitro analysis of alveolar macrophages (AMs) and T cells, our study elucidates a compelling correlation between Tercko/ko, inflammation, and impaired T cell functionality. Terc deletion results in compromised T cell function, characterized by dysregulation of the T cell receptor and absence of CD247, potentially compromising the hosts capacity to mount an effective immune response against S. aureus. This investigation provides insights into the intricate mechanisms governing increased vulnerability to severe pneumonia in the context of Terc deficiency, which might also contribute to aging-related pathologies, while also revealing for the first time the influence of Terc on T cell function. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=172 SRC="FIGDIR/small/599722v2_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@15977f5org.highwire.dtl.DTLVardef@d2b203org.highwire.dtl.DTLVardef@a50641org.highwire.dtl.DTLVardef@3dc906_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2024

The murine lung microbiome is dysbalanced by the human pathogenic fungus Aspergillus fumigatus resulting in enrichment of anaerobic bacteria

Here, we report significant changes in the composition of the lung microbiome and metabolome of mice under immune suppression, infection of immunosuppressed mice with virulent and avirulent strains of the clinically important human-pathogenic fungus Aspergillus fumigatus, and treatment with the clinically used antifungal drug voriconazole. Our data also indicate the important role of the gut microbiome for the lung homeostasis mediated by the plasma metabolome. In the lung microbiome, infection by A. fumigatus led to a significant increase of anaerobic bacteria, most prominently of Ligilactobacillus murinus, which was confirmed by the isolation of live bacteria from the murine lower respiratory tract. In vitro, L. murinus is tolerated and even internalized by alveolar epithelial cells. Co-cultivation of L. murinus and A. fumigatus led to a reduction in oxygen concentration accompanied by an increase of L. murinus cells suggesting that A. fumigatus establishes a microaerophilic niche, thereby promoting growth of anaerobic bacteria.

microbiology↗

bioRxiv2023

Bacteriophage-mediated decolonization of Enterobacteriaceae in a novel Galleria mellonella gut colonization model

PurposeGalleria mellonella larvae have emerged as an invertebrate model for studying bacterial pathogenesis and novel therapeutic options due to ethical concerns associated with the use of mammalian models such as mice. The benefits of using G. mellonella larvae include a less complex microbiome in the gut, making it suitable for gut colonization studies. The intestinal colonization of Klebsiella pneumoniae (Kp) and Escherichia coli (Ec), two of the most antibiotic-resistant bacteria on the World Health Organizations (WHO) priority list, plays a key role in the spread of antibiotic resistance. Bacteriophage therapy is emerging as a promising alternative for antibiotic-resistant bacteria due to its ability to specifically target and infect bacterial hosts, making it suitable for gut decontamination. This study aimed to establish a novel Enterobacteriaceae G. mellonella larvae gut colonization model and compare the efficacy of conventional antibiotic treatment with a one-time phage cocktail in decolonizing the gut. ApproachLarvae were force-fed with different concentrations of bacterial doses of K. pneumoniae and E. coli at 0 h, 24 h, and 48 h, followed by survival monitoring at 24 h intervals. After 48 h and 120 h of the last force feed, the colony forming unit (CFU) count in the gut was evaluated. After successful colonization, larvae were one-time force-fed with either a 107 PFU/larvae bacteriophage cocktail or with ciprofloxacin 4 mg/L or meropenem 2 mg/L. After 24 h post phage feeding, CFU counts were determined. Main findingsThree bacterial doses of 106 CFU/larvae led to a stable gut colonization in the larvae gut regardless of the K. pneumoniae and E. coli strains. Bacteriophage force-feeding reduced bacterial colonization by 4 log10 CFU/larvae whereas antibiotic treatment led to a 2 log10 CFU/larvae reduction compared to the control. The novel alternative G. mellonella model for gut colonization studies can be used for proof-of-concept studies, reducing or even obviating the number of follow-up experiments in vertebrate models.

microbiology↗

bioRxiv2020

SARS-CoV-2 causes severe alveolar inflammation and barrier dysfunction

Infections with SARS-CoV-2 lead to mild to severe coronavirus disease-19 (COVID-19) with systemic symptoms. Although the viral infection originates in the respiratory system, it is unclear how the virus can overcome the alveolar barrier, which is observed in severe COVID-19 disease courses. To elucidate the viral effects on the barrier integrity and immune reactions, we used mono-cell culture systems and a complex human alveolus-on-a-chip model composed of epithelial, endothelial, and mononuclear cells. Our data show that SARS-CoV-2 efficiently infected epithelial cells with high viral loads and inflammatory response, including the interferon expression. By contrast, the adjacent endothelial layer was no infected and did neither show productive virus replication or interferon release. With prolonged infection, both cell types are damaged, and the barrier function is deteriorated, allowing the viral particles to overbear. In our study, we demonstrate that although SARS-CoV-2 is dependent on the epithelium for efficient replication, the neighboring endothelial cells are affected, e.g., by the epithelial cytokine release, which results in the damage of the alveolar barrier function and viral dissemination.

microbiology↗

bioRxiv2020

Early postmortem mapping of SARS-CoV-2 RNA in patients with COVID-19 and correlation to tissue damage

Clinical observations indicate that COVID-19 is a systemic disease. An investigation of the viral distribution within the human body in correlation to tissue damage can help understanding the pathophysiology of SARS-CoV-2 infection.We present a detailed mapping of viral RNA in 61 tissues and organs of 11 deceased patients with the diagnosis COVID-19. The autopsies were performed within the (very) early postmortem interval (mean: 5.6 hours) to avoid bias due to viral RNA and tissue degradation. Viral loads, blood levels of cytokines, prothrombotic factors as well as macro- and micro-morphology were correlated.Very high (> 104 copies/ml) viral loads were detected in the lungs of most patients and then correlated to severe tissue damage. Intact viral particles could be verified in the lung tissue by transmission electron microscopy. Viral loads in the lymph nodes were associated with a loss of follicular architecture. Viral RNA was detected throughout further extra-pulmonary tissues and organs without visible tissue damage. Inflammatory cytokines as well as the prothrombotic factors were elevated in all patients.In conclusion, the dissemination of SARS-CoV-2-RNA throughout the body supports the hypothesis of a maladaptive host response with viremia and multi-organ dysfunction.View Full Text

immunology↗

bioRxiv2019

Human neutrophils produce antifungal extracellular vesicles against Aspergillus fumigatus

Polymorphonuclear granulocytes (PMNs) are indispensable for controlling life-threatening fungal infections. In addition to various effector mechanisms, PMNs also produce extracellular vesicles (EVs). Their contribution to antifungal defense has remained unexplored. We reveal that the clinically important human pathogenic fungus Aspergillus fumigatus triggers PMNs to release a distinct set of antifungal EVs (afEVs). Proteome analyses indicated that afEVs are enriched in antimicrobial proteins. The cargo and release kinetics of EVs are modulated by the fungal strain confronted. Tracking of afEVs indicated that they associated with fungal cells and even entered fungal hyphae, resulting in alterations in the morphology of the fungal cell wall and dose-dependent antifungal effects. Two human proteins enriched in afEVs, cathepsin G and azurocidin, were heterologously expressed in fungal hyphae, which led to reduced fungal growth relative to a control retinol binding protein 7 producing strain. In conclusion, the production of afEVs by PMNs offers an intriguing, previously overlooked mechanism of antifungal defense against A. fumigatus. ImportanceInvasive fungal infections caused by the mold Aspergillus fumigatus are a growing concern in the clinic due to the increasing use of immunosuppressive therapies and increasing antifungal drug resistance. These infections result in high mortality as treatment and diagnostic options remain limited. In healthy individuals, neutrophilic granulocytes are critical for elimination of A. fumigatus from the host; however, the exact extracellular mechanism of neutrophil-mediated antifungal activity remains unresolved. Here, we present a mode of antifungal defense employed by human neutrophils against A. fumigatus not previously described. We find that extracellular vesicles produced by neutrophils in response to A. fumigatus infection are able to associate with the fungus, limit growth, and elicit cell damage by delivering antifungal cargo. In the end, antifungal extracellular vesicle biology provides a significant step forward in our understanding of A. fumigatus host pathogenesis and opens up novel diagnostic and therapeutic possibilities.

microbiology↗