In-vitro effects of novel periodontal scalers with a planar ultrasonic piezoelectric transducer on periodontal biofilm removal, dentine surface roughness, and periodontal ligament fibroblasts adhesion.

OBJECTIVES: To compare ultrasonic scaler prototypes based on a planar piezoelectric transducer with different working frequencies featuring a titanium (Ti-20, Ti-28, and Ti-40) or stainless steel (SS-28) instrument, with a commercially available scaler (com-29) in terms of biofilm removal and reformation, dentine surface roughness and adhesion of periodontal fibroblasts. MATERIALS AND METHODS: A periodontal multi-species biofilm was formed on specimens with dentine slices. Thereafter specimens were instrumented with scalers in a periodontal pocket model or left untreated (control). The remaining biofilms were quantified and allowed to reform on instrumented dentine slices. In addition, fibroblasts were seeded for attachment evaluation after 72 h of incubation. Dentine surface roughness was analyzed before and after instrumentation. RESULTS: All tested instruments reduced the colony-forming unit (cfu) counts by about 3 to 4 log10 and the biofilm quantity (each p < 0.01 vs. control), but with no statistically significant difference between the instrumented groups. After 24-hour biofilm reformation, no differences in cfu counts were observed between any groups, but the biofilm quantity was about 50% in all instrumented groups compared to the control. The attachment of fibroblasts on instrumented dentine was significantly higher than on untreated dentine (p < 0.05), with the exception of Ti-20. The dentine surface roughness was not affected by any instrumentation. CONCLUSIONS: The planar piezoelectric scaler prototypes are able to efficiently remove biofilm without dentine surface alterations, regardless of the operating frequency or instrument material. CLINICAL RELEVANCE: Ultrasonic scalers based on a planar piezoelectric transducer might be an alternative to currently available ultrasonic scalers.

Bacteriophage-mediated decolonization of Klebsiella pneumoniae in a novel Galleria mellonella gut colonization model with Enterobacteriaceae.

Galleria mellonella larvae have emerged as an invertebrate model for investigating bacterial pathogenesis and potential therapies, addressing ethical concerns related to mammalian models. This model has the advantage of having a simple gut microbiome, which is suitable for gut colonization studies. Intestinal colonization by Enterobacteriaceae significantly contributes to the spread of antibiotic resistance. This study aimed to establish a novel Enterobacteriaceae gut colonization larval model and assess its suitability for evaluating distinct antimicrobial efficacies. Larvae were force-fed sequentially with bacterial doses of K. pneumoniae and E. coli at 0, 24, and 48 h, with survival monitoring at 24 h intervals. Bacterial counts were assessed after 48 h and 120 h of force-feeding. Successfully colonized larvae were subjected to one-time force feeding of a bacteriophage cocktail (107 PFU/larvae) or MIC-based meropenem and ciprofloxacin. The colonized bacterial load was quantified by CFU count. Three doses of 106 CFU/larvae resulted in stable gut colonization, independent of the K. pneumoniae or E. coli strain. Compared with the control, force-feeding of the bacteriophage reduced the colonization of the strain Kp 419614 by 5 log10 CFU/larvae, while antibiotic treatment led to a 3 log10 CFU/larval reduction. This novel G. mellonella model provides a valuable alternative for gut colonization studies, facilitating proof-of-concept investigations and potentially reducing or replacing follow-up experiments in vertebrate models.

Influence of the orthodontic bonding procedure on biofilm formation.

INTRODUCTION: In orthodontics, white spot lesions are a persistent and widespread problem caused by the demineralization of buccal tooth surfaces around bonded brackets. The remaining adhesive around the brackets leads to surface roughness, which might contribute to demineralization. The present in vitro study aimed to compare a conventional and a modern adhesive system (APC Flash-Free technology) for orthodontic brackets with regard to the adhesion of Streptococcus sobrinus, a leading caries pathogen. METHODS: This in vitro study included 20 premolar teeth and compared 10 APC Flash-Free adhesive-coated ceramic brackets (FF)with 10 conventionally bonded (CB) ceramic clarity brackets. Specimens were incubated in an S. sobrinus suspension for 3 h. To evaluate the bacterial formation, samples were analysed with a scanning electron microscope (SEM). Imaging software was used to quantify and statistically compare percentage values of colonization (PVC) in both groups' adhesion and transition areas. RESULTS: We found a significant difference in biofilm formation between the groups for the adhesive and transition areas. PVC in the adhesive area was approximately 10.3-fold greater for the CB group compared with the FF group (median: 3.2 vs 0.31; P < 0.0001). For the transition area, median PVC was approximately 2.4-fold greater for the CB group compared with the FF group (median: 53.17 vs 22.11; P < 0.01). CONCLUSIONS: There was a significantly lower level of S. sobrinus formation around the FF bracket system than there was surrounding the conventionally bonded group. This study suggests that the FF adhesive bracket system can help reduce the occurrence of bacterial growth around orthodontic brackets.

The influenza A virus promotes fungal growth of Aspergillus fumigatus via direct interaction in vitro.

Seasonal influenza A virus (IAV) infections still pose a major burden for public health worldwide. Severe disease progression or even death is often related to superinfections of the virus and a secondary bacterial pathogen. However, fungi, especially Aspergillus fumigatus, are also frequently diagnosed during IAV infection. Although, clinical studies have reported the severity of influenza-associated pulmonary aspergillosis, the molecular mechanisms underlying this type of disease are poorly understood. Here, a new in vitro model is introduced that allows the investigation of complex pathogen-host and pathogen-pathogen interactions during coinfection of lung epithelial cells with IAV and A. fumigatus. Our data reveal a reduced IAV load and IAV-induced cytokine and chemokine expression in the presence of A. fumigatus. At the same time, IAV infection promotes the growth of A. fumigatus. Even in the absence of the human host cell, purified IAV particles are able to induce hyphal growth, due to a direct interaction of the virus particles with the fungal surface. Thus, our study gives first insights into the complex interplay between IAV, A. fumigatus and the host cell as well as the two pathogens alone.

GPRC5C regulates the composition of cilia in the olfactory system.

BACKGROUND: Olfactory sensory neurons detect odourants via multiple long cilia that protrude from their dendritic endings. The G protein-coupled receptor GPRC5C was identified as part of the olfactory ciliary membrane proteome, but its function and localization is unknown. RESULTS: High-resolution confocal and electron microscopy revealed that GPRC5C is located at the base of sensory cilia in olfactory neurons, but not in primary cilia of immature neurons or stem cells. Additionally, GPRC5C localization in sensory cilia parallels cilia formation and follows the formation of the basal body. In closer examination, GPRC5C was found in the ciliary transition zone. GPRC5C deficiency altered the structure of sensory cilia and increased ciliary layer thickness. However, primary cilia were unaffected. Olfactory sensory neurons from Gprc5c-deficient mice exhibited altered localization of olfactory signalling cascade proteins, and of ciliary phosphatidylinositol-4,5-bisphosphat. Sensory neurons also exhibited increased neuronal activity as well as altered mitochondrial morphology, and knockout mice had an improved ability to detect food pellets based on smell. CONCLUSIONS: Our study shows that GPRC5C regulates olfactory cilia composition and length, thereby controlling odour perception.

Influence of Different Bracket Adhesive Systems on Enamel Demineralization-An In Vitro Study.

BACKGROUND: enamel demineralization is a common side effect of orthodontic therapy with fixed braces. The aim of the present in vitro study was to compare a conventional adhesive system and a modern adhesive system (APC Flash-Free [FF] technology) with regard to the demineralization of enamel by Streptococcus sobrinus (S. sobrinus). METHODS: this in vitro study included premolar teeth and compared APC FF adhesive brackets (Group A, n = 15) with conventional adhesive brackets (Group B, n = 15) from the same company. Specimens were incubated with a positive control group (PCG, n = 5) and a negative control group (NCG, n = 5) in an S. sobrinus suspension for three weeks. To evaluate the grade of enamel demineralization, the samples were analyzed using a polarizing microscope. RESULTS: the test specimens of group B with conventionally bonded bracket adhesive showed significantly greater (+10.8 µm) demineralization with regard to the penetration depth of the demineralization than the PCG (p = 0.012). Thus, there was a difference from group A with the new bracket adhesive of the FF brackets (+7.29 µm). Significantly, demineralization was more pronounced cervically than coronally in both groups, and it occurred cervically more frequently than grade 3 demineralization (p = 0.001). CONCLUSIONS: it seems plausible that new orthodontic bracket adhesives and the modern FF adhesive system positively contribute to the reduction in enamel demineralization during orthodontic treatment.

Sodium thiosulfate refuels the hepatic antioxidant pool reducing ischemia-reperfusion-induced liver injury.

Ischemia-reperfusion injury is a critical liver condition during hepatic transplantation, trauma, or shock. An ischemic deprivation of antioxidants and energy characterizes liver injury in such cases. In the face of increased reactive oxygen production, hepatocytes are vulnerable to the reperfusion driving ROS generation and multiple cell-death mechanisms. In this study, we investigate the importance of hydrogen sulfide as part of the liver's antioxidant pool and the therapeutic potency of the hydrogen sulfide donors sodium sulfide (Na2S, fast releasing) and sodium thiosulfate (STS, Na2S2O3, slow releasing). The mitoprotection and toxicity of STS and Na2S were investigated on isolated mitochondria and a liver perfusion oxidative stress model by adding text-butyl hydroperoxide and hydrogen sulfide donors. The respiratory capacity of mitochondria, hepatocellular released LDH, glutathione, and lipid-peroxide levels were quantified. In addition, wild-type and cystathionine-γ-lyase knockout mice were subjected to warm selective ischemia-reperfusion injury by clamping the main inflow for 1 h followed by reperfusion of 1 or 24 h. A subset of animals was treated with STS shortly before reperfusion. Glutathione, plasma ALT, and lipid-peroxide levels were investigated alongside mitochondrial changes in structure (electron microscopy) and function (intravital microscopy). Liver tissue necrosis quantified 24 h after reperfusion indicates the net effects of the treatment on the organ. STS refuels and protects the endogenous antioxidant pool during liver ischemia-reperfusion injury. In addition, STS-mediated ROS scavenging significantly reduced lipid peroxidation and mitochondrial damage, resulting in better molecular and histopathological preservation of the liver tissue architecture. STS prevents tissue damage in liver ischemia-reperfusion injury by increasing the liver's antioxidant pool, thereby protecting mitochondrial integrity.

Effects of reducing excess dental adhesive on bacterial adhesion in the bracket periphery.

OBJECTIVES: White spot lesions are one of the most common side effects of orthodontic therapy with a multibracket appliance and may indicate a preliminary stage of caries, also known as initial caries. Several approaches may be utilized to prevent these lesions, such as reducing bacterial adhesion in the area surrounding the bracket. This bacterial colonization can be adversely affected by a number of local characteristics. In this context, the effects of excess dental adhesive in the bracket periphery were investigated by comparing a conventional bracket system with the APC flash-free bracket system. MATERIALS AND METHODS: Both bracket systems were applied to 24 extracted human premolars, and bacterial adhesion with Streptoccocus sobrinus (S. sobrinus) was performed for 24 h, 48 h, 7 d, and 14 d. After incubation, bacterial colonization was examined in specific areas by electron microscopy. RESULTS: Overall, significantly fewer bacterial colonies were found in the adhesive area around the APC flash-free brackets (n = 507 ± 13 bacteria) than the conventionally bonded bracket systems (n = 850 ± 56 bacteria). This is a significant difference (**p = 0.004). However, APC flash-free brackets tend to create marginal gaps with more bacterial adhesion in this area than conventional bracket systems (n = 265 ± 31 bacteria). This bacterial accumulation in the marginal-gap area is also significant (*p = 0.029). CONCLUSION: A smooth adhesive surface with minimal adhesive excess is beneficial for reducing bacterial adhesion but also poses a risk of marginal gap formation with subsequent bacterial colonization, which can potentially trigger carious lesions. CLINICAL RELEVANCE: To reduce bacterial adhesion, the APC flash-free bracket adhesive system with low adhesive excess might be beneficial. APC flash-free brackets reduce the bacterial colonization in the bracket environment. A lower number of bacteria can minimize white spot lesions in the bracket environment. APC flash-free brackets tend to form marginal gaps between the bracket adhesive and the tooth.

Remineralization of Artificially Demineralized Human Enamel and Dentin Samples by Zinc-Carbonate Hydroxyapatite Nanocrystals.

(1) Background: Decalcified enamel and dentin surfaces can be regenerated with non-fluoride-containing biomimetic systems. This study aimed to investigate the effect of a zinc carbonate-hydroxyapatite-containing dentifrice on artificially demineralized enamel and dentin surfaces. (2) Methods: Human enamel and dentin discs were prepared and subjected to surface demineralization with 30% orthophosphoric acid for 60 s. Subsequently, in the test group (n = 20), the discs were treated three times a day for 3 min with a zinc carbonate-hydroxyapatite-containing toothpaste (biorepair®). Afterwards, all samples were gently rinsed with PBS (5 s) and stored in artificial saliva until next use. Samples from the control group (n = 20) received no dentifrice-treatment and were stored in artificial saliva, exclusively. After 15 days of daily treatment, specimens were subjected to Raman spectroscopy, energy-dispersive X-ray micro-analysis (EDX), white-light interferometry, and profilometry. (3) Results: Raman spectroscopy and white-light interferometry revealed no significant differences compared to the untreated controls. EDX analysis showed calcium phosphate and silicon dioxide precipitations on treated dentin samples. In addition, treated dentin surfaces showed significant reduced roughness values. (4) Conclusions: Treatment with biorepair® did not affect enamel surfaces as proposed. Minor mineral precipitation and a reduction in surface roughness were detected among dentin surfaces only.

Salt and Metal Tolerance Involves Formation of Guttation Droplets in Species of the Aspergillus versicolor Complex.

Three strains of the Aspergillus versicolor complex were isolated from a salty marsh at a former uranium mining site in Thuringia, Germany. The strains from a metal-rich environment were not only highly salt tolerant (up to 20% NaCl), but at the same time could sustain elevated Cs and Sr (both up to 100 mM) concentrations as well as other (heavy) metals present in the environment. During growth experiments when screening for differential cell morphology, the occurrence of guttation droplets was observed, specifically when elevated Sr concentrations of 25 mM were present in the media. To analyze the potential of metal tolerance being promoted by these excretions, proteomics and metabolomics of guttation droplets were performed. Indeed, proteins involved in up-regulated metabolic activities as well as in stress responses were identified. The metabolome verified the presence of amino sugars, glucose homeostasis-regulating substances, abscisic acid and bioactive alkaloids, flavones and quinones.

Augmented Enterocyte Damage During Candida albicans and Proteus mirabilis Coinfection.

The human gut acts as the main reservoir of microbes and a relevant source of life-threatening infections, especially in immunocompromised patients. There, the opportunistic fungal pathogen Candida albicans adapts to the host environment and additionally interacts with residing bacteria. We investigated fungal-bacterial interactions by coinfecting enterocytes with the yeast Candida albicans and the Gram-negative bacterium Proteus mirabilis resulting in enhanced host cell damage. This synergistic effect was conserved across different P. mirabilis isolates and occurred also with non-albicans Candida species and C. albicans mutants defective in filamentation or candidalysin production. Using bacterial deletion mutants, we identified the P. mirabilis hemolysin HpmA to be the key effector for host cell destruction. Spatially separated coinfections demonstrated that synergism between Candida and Proteus is induced by contact, but also by soluble factors. Specifically, we identified Candida-mediated glucose consumption and farnesol production as potential triggers for Proteus virulence. In summary, our study demonstrates that coinfection of enterocytes with C. albicans and P. mirabilis can result in increased host cell damage which is mediated by bacterial virulence factors as a result of fungal niche modification via nutrient consumption and production of soluble factors. This supports the notion that certain fungal-bacterial combinations have the potential to result in enhanced virulence in niches such as the gut and might therefore promote translocation and dissemination.

Rapid and Selective Absorption of Plant Defense Compounds From the Gut of a Sequestering Insect.

Many herbivorous insects exploit defense compounds produced by their host plants for protection against predators. Ingested plant defense compounds are absorbed via the gut epithelium and stored in the body, a physiological process that is currently not well understood. Here, we investigated the absorption of plant defense compounds from the gut in the horseradish flea beetle, Phyllotreta armoraciae, a specialist herbivore known to selectively sequester glucosinolates from its brassicaceous host plants. Feeding experiments using a mixture of glucosinolates and other glucosides not found in the host plants showed a rapid and selective uptake of glucosinolates in adult beetles. In addition, we provide evidence that this uptake mainly takes place in the foregut, whereas the endodermal midgut is the normal region of absorption. Absorption via the foregut epithelium is surprising as the apical membrane is covered by a chitinous intima. However, we could show that this cuticular layer differs in its structure and overall thickness between P. armoraciae and a non-sequestering leaf beetle. In P. armoraciae, we observed a thinner cuticle with a less dense chitinous matrix, which might facilitate glucosinolate absorption. Our results show that a selective and rapid uptake of glucosinolates from the anterior region of the gut contributes to the selective sequestration of glucosinolates in P. armoraciae.

Bacterial marginolactones trigger formation of algal gloeocapsoids, protective aggregates on the verge of multicellularity.

Photosynthetic microorganisms including the green alga Chlamydomonas reinhardtii are essential to terrestrial habitats as they start the carbon cycle by conversion of CO2 to energy-rich organic carbohydrates. Terrestrial habitats are densely populated, and hence, microbial interactions mediated by natural products are inevitable. We previously discovered such an interaction between Streptomyces iranensis releasing the marginolactone azalomycin F in the presence of C. reinhardtii Whether the alga senses and reacts to azalomycin F remained unknown. Here, we report that sublethal concentrations of azalomycin F trigger the formation of a protective multicellular structure by C. reinhardtii, which we named gloeocapsoid. Gloeocapsoids contain several cells which share multiple cell membranes and cell walls and are surrounded by a spacious matrix consisting of acidic polysaccharides. After azalomycin F removal, gloeocapsoid aggregates readily disassemble, and single cells are released. The presence of marginolactone biosynthesis gene clusters in numerous streptomycetes, their ubiquity in soil, and our observation that other marginolactones such as desertomycin A and monazomycin also trigger the formation of gloeocapsoids suggests a cross-kingdom competition with ecological relevance. Furthermore, gloeocapsoids allow for the survival of C. reinhardtii at alkaline pH and otherwise lethal concentrations of azalomycin F. Their structure and polysaccharide matrix may be ancestral to the complex mucilage formed by multicellular members of the Chlamydomonadales such as Eudorina and Volvox Our finding suggests that multicellularity may have evolved to endure the presence of harmful competing bacteria. Additionally, it underlines the importance of natural products as microbial cues, which initiate interesting ecological scenarios of attack and counter defense.

Long-Chain and Very Long-Chain Ceramides Mediate Doxorubicin-Induced Toxicity and Fibrosis.

Doxorubicin (Dox) is a chemotherapeutic agent with cardiotoxicity associated with profibrotic effects. Dox increases ceramide levels with pro-inflammatory effects, cell death, and fibrosis. The purpose of our study was to identify the underlying ceramide signaling pathways. We aimed to characterize the downstream effects on cell survival, metabolism, and fibrosis. Human fibroblasts (hFSF) were treated with 0.7 µM of Dox or transgenically overexpressed ceramide synthase 2 (FLAG-CerS2). Furthermore, cells were pre-treated with MitoTempo (MT) (2 h, 20 µM) or Fumonisin B1 (FuB) (4 h, 100 µM). Protein expression was measured by Western blot or immunofluorescence (IF). Ceramide levels were determined with mass spectroscopy (MS). Visualizations were conducted using laser scanning microscopy (LSM) or electron microscopy. Mitochondrial activity was measured using seahorse analysis. Dox and CerS2 overexpression increased CerS2 protein expression. Coherently, ceramides were elevated with the highest peak for C24:0. Ceramide- induced mitochondrial ROS production was reduced with MT or FuB preincubation. Mitochondrial homeostasis was reduced and accompanied by reduced ATP production. Our data show that the increase in pro-inflammatory ceramides is an essential contributor to Dox side-effects. The accumulation of ceramides resulted in a lipotoxic shift and subsequently mitochondrial structural and functional damage, which was partially reversible following inhibition of ceramide synthesis.

In Vitro Activity of Propolis on Oral Microorganisms and Biofilms.

Natural products are being discussed as alternatives to commonly used chemicals in antimicrobial therapy. The study aimed to investigate the antimicrobial activity of propolis against microbial species associated with caries, periodontal disease, and Candida infections. Two commercially available ethanolic extracts of Brazilian and one of European propolis (EEP) were used. The minimal inhibitory concentrations (MIC) of propolis and controls against eight microbial strains were determined. Scanning and transmission electron microscopy (SEM and TEM) images visualized the effect of propolis on microorganisms. Subsequently, the activity on three different multi-species biofilms (both formation and existing biofilms) was assessed. All MIC values of the Brazilian EEPs were low against the tested oral species (≤0.1 mg/mL-3.13 mg/mL propolis (Candida albicans)). The European EEP had slightly higher MICs than the Brazilian EEPs. The SEM and TEM images suggest an interaction of propolis with the microbial cell wall. The European EEP exhibited the strongest effect on retarding biofilm formation, whereas the Brazilian EEPs were highly active against preformed biofilms (100 mg/mL propolis of both EEPs reduced colony forming unit counts always by more than 6 log10). The antimicrobial and anti-biofilm activities point to the potential of propolis as an adjunct in oral health care products.

Intracellular persistence of Staphylococcus aureus in endothelial cells is promoted by the absence of phenol-soluble modulins.

A large proportion of clinical S. aureus isolates that carry an inactive Agr system are associated with persistent infection that is difficult to treat. Once S. aureus is inside the bloodstream, it can cross the endothelial barrier and invade almost every organ in the human body. Endothelial cells can either be lysed by this pathogen or they serve as a niche for its intracellular long-term survival. Following phagocytosis, several vesicles such as phagosomes and autophagosomes, target intracellular S. aureus for elimination. S. aureus can escape from these vesicles into the host cytoplasm through the activation of phenol-soluble modulins (PSMs) αß. Thereafter, it replicates and lyses the host cell to disseminate to adjacent tissues. Herein we demonstrate that staphylococcal strains which lack the expression of PSMs employ an alternative pathway to better persist within endothelial cells. The intracellular survival of S. aureus is associated with the co-localization of the autophagy marker LC3. In cell culture infection models, we found that the absence of psmαß decreased the host cell lysis and increased staphylococcal long-term survival. This study explains the positive selection of agr-negative strains that lack the expression of psmαß in chronic infection due to their advantage in surviving and evading the clearance system of the host.

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

Clinical observations indicate that COVID-19 is a systemic disease. An investigation of the viral distribution within the human body and its correlation with tissue damage can aid in understanding the pathophysiology of SARS-CoV-2 infection. We present a detailed mapping of the viral RNA in 61 tissues and organs of 11 deceased patients with COVID-19. The autopsies were performed within the early postmortem interval (between 1.5 and 15 hr, mean: 5.6 hr) to minimize the bias due to viral RNA and tissue degradation. Very high viral loads (>104copies/ml) were detected in most patients' lungs, and the presence of intact viral particles in the lung tissue could be verified by transmission electron microscopy. Interestingly, viral RNA was detected throughout various extrapulmonary tissues and organs without visible tissue damage. The dissemination of SARS-CoV-2-RNA throughout the body supports the hypothesis that there is a maladaptive host response with viremia and multiorgan dysfunction.

Since the discovery of the new coronavirus that causes COVID-19, scientists have been scrambling to understand the different features of the virus. While a lot more is now known about SARS-CoV-2, several key questions have proved more difficult to answer. For example, it remained unclear where the virus travels to in the body and causes the most harm. To help answer this question, Deinhardt-Emmer, Wittschieber et al. performed postmortem examinations on 11 patients who had recently died of COVID-19. After sampling 61 different organs and tissues from each patient, several tests were used to detect traces of SARS-CoV-2. The experiments showed that the largest pool of SARS-CoV-2 was present in the lungs, where it had caused severe damage to the alveolae, the delicate air sacs at the end of the lungs' main air tubes. Small amounts of the virus were also detected in other organs and tissues, but no severe tissue damage was seen. In addition, Deinhardt-Emmer, Wittschieber et al. found that each patient had increased levels of some of the proteins involved in inflammation and blood clotting circulating their bloodstream. This suggests that the inflammation caused by SARS-CoV-2 leads to an excessive immune reaction throughout the entire body. This research provides important new insights into which areas of the body are most impacted by SARS-CoV-2. These findings may help to design more effective drug treatments that target the places SARS-CoV-2 is most likely to accumulate and help patients fight off the infection at these regions.

SARS-CoV-2 causes severe epithelial inflammation and barrier dysfunction.

Infections with SARS-CoV-2 can be asymptomatic, but they can also be accompanied by a variety of symptoms that result in mild to severe coronavirus disease-19 (COVID-19) and are sometimes associated 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 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 interferon expression. By contrast, the adjacent endothelial layer was neither infected nor did it show productive virus replication or interferon release. With prolonged infection, both cell types were damaged, and the barrier function was 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 cytokines or components induced during infection, which further results in the damage of the epithelial/endothelial barrier function and viral dissemination.IMPORTANCESARS-CoV-2 challenges healthcare systems and societies worldwide in unprecedented ways. Although numerous new studies have been conducted, research to better understand the molecular pathogen-host interactions are urgently needed. For this, experimental models have to be developed and adapted. In the present study we used mono cell-culture systems and we established a complex chip model, where epithelial and endothelial cells are cultured in close proximity. We demonstrate that epithelial cells can be infected with SARS-CoV-2, while the endothelium did not show any infection signs. Since SARS-CoV-2 is able to establish viremia, the link to thromboembolic events in severe COVID-19 courses is evident. However, whether the endothelial layer is damaged by the viral pathogens or whether other endothelial-independent homeostatic factors are induced by the virus is essential for understanding the disease development. Therefore, our study is important as it demonstrates that the endothelial layer could not be infected by SARS-CoV-2 in our in vitro experiments, but we were able to show the destruction of the epithelial-endothelial barrier in our chip model. From our experiments we can assume that virus-induced host factors disturbed the epithelial-endothelial barrier function and thereby promote viral spread.

The impact of episporic modification of Lichtheimia corymbifera on virulence and interaction with phagocytes.

Fungal infections caused by the ancient lineage Mucorales are emerging and increasingly reported in humans. Comprehensive surveys on promising attributes from a multitude of possible virulence factors are limited and so far, focused on Mucor and Rhizopus. This study addresses a systematic approach to monitor phagocytosis after physical and enzymatic modification of the outer spore wall of Lichtheimia corymbifera, one of the major causative agents of mucormycosis. Episporic modifications were performed and their consequences on phagocytosis, intracellular survival and virulence by murine alveolar macrophages and in an invertebrate infection model were elucidated. While depletion of lipids did not affect the phagocytosis of both strains, delipidation led to attenuation of LCA strain but appears to be dispensable for infection with LCV strain in the settings used in this study. Combined glucano-proteolytic treatment was necessary to achieve a significant decrease of virulence of the LCV strain in Galleria mellonella during maintenance of the full potential for spore germination as shown by a novel automated germination assay. Proteolytic and glucanolytic treatments largely increased phagocytosis compared to alive resting and swollen spores. Whilst resting spores barely (1-2%) fuse to lysosomes after invagination in to phagosomes, spore trypsinization led to a 10-fold increase of phagolysosomal fusion as measured by intracellular acidification. This is the first report of a polyphasic measurement of the consequences of episporic modification of a mucormycotic pathogen in spore germination, spore surface ultrastructure, phagocytosis, stimulation of Toll-like receptors (TLRs), phagolysosomal fusion and intracellular acidification, apoptosis, generation of reactive oxygen species (ROS) and virulence.

In vitro Activity of Oral Health Care Products on Candida Biofilm Formation.

The activity of mouthwash ingredients used in daily oral care (chlorhexidine digluconate, benzalkonium chloride, povidone iodine solution, tea tree oil) and of nystatin was evaluated not only on planktonic Candida albicans or C. glabrata, but also on the inhibition of biofilm formation. A microbroth dilution technique was used to determine the minimum inhibitory concentration of the substances against two laboratory strains and seven clinical isolates. Furthermore, a potential inhibition of biofilm formation of C. albicans or C. glabrata (single-species biofilm or mixed with two oral bacteria) was assessed. The results showed an activity of all tested substances against all C. albicans and C. glabratastrains. In the biofilm assays, a concentration-dependent effect of the substances was visible. However, a low concentration of povidone iodine solution and in particular of benzalkonium chloride seemed to increase the virulence of C. albicans. Most test substances affected both bacteria and yeasts in the mixed biofilms, only nystatin predominately reduced the yeasts. In conclusion, nystatin might be the drug of choice when exclusively preventing the colonization of Candida sp. in biofilms. The alternatives, benzalkonium chloride, povidone iodine solution, and tea tree oil, should be investigated further.