Secretion of the fungal toxin candidalysin is dependent on conserved precursor peptide sequences

The opportunistic fungal pathogen Candida albicans damages host cells via its peptide toxin, candidalysin. Before secretion, candidalysin is embedded in a precursor protein, Ece1, which consists of a signal peptide, the precursor of candidalysin and seven non-candidalysin Ece1 peptides (NCEPs), and is found to be conserved in clinical isolates. Here we show that the Ece1 polyprotein does not resemble the usual precursor structure of peptide toxins. C. albicans cells are not susceptible to their own toxin, and single NCEPs adjacent to candidalysin are sufficient to prevent host cell toxicity. Using a series of Ece1 mutants, mass spectrometry and anti-candidalysin nanobodies, we show that NCEPs play a role in intracellular Ece1 folding and candidalysin secretion. Removal of single NCEPs or modifications of peptide sequences cause an unfolded protein response (UPR), which in turn inhibits hypha formation and pathogenicity in vitro. Our data indicate that the Ece1 precursor is not required to block premature pore-forming toxicity, but rather to prevent intracellular auto-aggregation of candidalysin sequences.

Subsidence after calcar-guided short stem total hip arthroplasty: five-year results of a prospective multicentre study

PURPOSE

Calcar-guided short-stem total hip arthroplasty (THA) has shown excellent clinical outcomes. However, the migration pattern of such prostheses and its effect on clinical outcomes are less known. Therefore, we assessed the five-year subsidence after calcar-guided short-stem THA and its implications on clinical outcomes, patient-related factors, and complications.

METHODS

In this prospective multicentre study, we enrolled 213 patients (224 hips) who underwent calcar-guided short-stem THA mostly for degenerative hip diseases. We examined patients radiographically and clinically after six to 12 weeks, one year, two years, and five years. We evaluated subsidence using Einzel-Bild-Roentgen-Analyse femoral component analysis, assessed clinical outcomes, and systematically recorded all complications.

RESULTS

Overall, 131 patients (133 hips) were available for final follow-up at a median of 60 months (range, 2 to 72 months). We found a mean subsidence of 0.63 ± 1.22 mm at three months, 1.03 ± 1.60 mm at one year, 1.21 ± 1.91 mm at two years, and 1.54 ± 1.97 mm at five years. Patient-related factors (sex, age, weight, and BMI) did not significantly impact subsidence at five years (P > 0.05). Additionally, the Harris hip score, pain, and satisfaction improved significantly at five years compared to pre-operative values (P < 0.0001). Lastly, five patients underwent revision.

CONCLUSION

Calcar-guided short-stems revealed the highest subsidence rate within the first three months after THA and stabilisation after one year through the final follow-up examination. Moreover, patient-related factors had no influence on subsidence. Finally, clinical scores and patient satisfaction remained high at five years.

Multiple phosphorylation sites regulate the activity of the repressor Mig1 in Candida albicans

IMPORTANCE

The SNF1 protein kinase signaling pathway, which is highly conserved in eukaryotic cells, is important for metabolic adaptations in the pathogenic yeast Candida albicans. However, so far, it has remained elusive how SNF1 controls the activity of one of its main effectors, the repressor protein Mig1 that inhibits the expression of genes required for the utilization of alternative carbon sources when glucose is available. In this study, we have identified multiple phosphorylation sites in Mig1 that contribute to its inactivation. Mutation of these sites strongly increased Mig1 repressor activity in the absence of SNF1, but SNF1 could still sufficiently inhibit the hyperactive Mig1 to enable growth on alternative carbon sources. These findings reveal features of Mig1 that are important for controlling its repressor activity. Furthermore, they demonstrate that both SNF1 and additional protein kinases regulate Mig1 in this pathogenic yeast.

Subsidence analysis of a cementless short stem THA using EBRA-FCA - A seven-year prospective multicentre study

Background

Metaphyseal fixation of short stem THA allows for minimally invasive surgery, less bone removal, improved bone load transfer and reduced stress shielding. Short stems facilitate the anatomic restoration i.a. of leg length, femoroacetabular offset, and center of rotation. However, metaphyseal fixation might cause impaired primary and/or secondary stability resulting in an inherent tendency for early axial migration and aseptic loosening eventually. The objective of this study was to investigate the long-term outcome and migration pattern of a calcar-guided short stem.

Methods

In a prospective multicenter study, 213 patients (224 THAs) were enrolled. Patients were followed for up to 84 months postoperatively. Clinical outcome was assessed using the Harris Hip Score and the VAS for pain and satisfaction. Standardized and calibrated radiographs were screened i.a. for stress shielding and loosening. Einzel-Bild-Roentgen-Analyse - femoral component analysis (EBRA-FCA) was used to detect longitudinal subsidence.

Results

At 7 year follow-up, n = 139/224 cases were available for analysis. All clinical parameters improved significantly (p < 0.001) and improvement persisted. There were no radiographic changes indicating stress shielding. EBRA-FCA revealed a mean subsidence of -1.44 mm followed by a stabilization. Weight >80 kg (p = 0.115), BMI <30 kg/m2 (p = 0.282), male gender (p = 0.246), and age <65 years (p = 0.304) seemed to be associated with a higher risk for migration. The cumulative revision rate was 2.23%. Revisions due to stem migration (0.89%) occurred early (mean time between index surgery and revision: 3.3 months).

Conclusions

If at all, there appears to be a pronounced initial subsidence, which stabilizes thereafter. Stem migration was rarely a compelling reason for failure or revision. Demographics do not seem to have a significant effect on migration pattern. The absence of radioluce lines, resorption or hypertrophy of the proximal femora support the hypothesis of a reduced stress shielding for metaphyseal anchoring short stems.

Bacterial secretion systems contribute to rapid tissue decay in button mushroom soft rot disease

The soft rot pathogen Janthinobacterium agaricidamnosum causes devastating damage to button mushrooms (Agaricus bisporus), one of the most cultivated and commercially relevant mushrooms. We previously discovered that this pathogen releases the membrane-disrupting lipopeptide jagaricin. This bacterial toxin, however, could not solely explain the rapid decay of mushroom fruiting bodies, indicating that J. agaricidamnosum implements a more sophisticated infection strategy. In this study, we show that secretion systems play a crucial role in soft rot disease. By mining the genome of J. agaricidamnosum, we identified gene clusters encoding a type I (T1SS), a type II (T2SS), a type III (T3SS), and two type VI secretion systems (T6SSs). We targeted the T2SS and T3SS for gene inactivation studies, and subsequent bioassays implicated both in soft rot disease. Furthermore, through a combination of comparative secretome analysis and activity-guided fractionation, we identified a number of secreted lytic enzymes responsible for mushroom damage. Our findings regarding the contribution of secretion systems to the disease process expand the current knowledge of bacterial soft rot pathogens and represent a significant stride toward identifying targets for their disarmament with secretion system inhibitors. IMPORTANCE The button mushroom (Agaricus bisporus) is the most popular edible mushroom in the Western world. However, mushroom crops can fall victim to serious bacterial diseases that are a major threat to the mushroom industry, among them being soft rot disease caused by Janthinobacterium agaricidamnosum. Here, we show that the rapid dissolution of mushroom fruiting bodies after bacterial invasion is due to degradative enzymes and putative effector proteins secreted via the type II secretion system (T2SS) and the type III secretion system (T3SS), respectively. The ability to degrade mushroom tissue is significantly attenuated in secretion-deficient mutants, which establishes that secretion systems are key factors in mushroom soft rot disease. This insight is of both ecological and agricultural relevance by shedding light on the disease processes behind a pathogenic bacterial-fungal interaction which, in turn, serves as a starting point for the development of secretion system inhibitors to control disease progression.

A phylogenetic approach to explore the Aspergillus fumigatus conidial surface-associated proteome and its role in pathogenesis

Aspergillus fumigatus , an important pulmonary fungal pathogen causing several diseases collectively called aspergillosis, relies on asexual spores or conidia for initiating host infection. Here, we used a phylogenomic approach to compare proteins in the conidial surface of A. fumigatus , two closely related non-pathogenic species, Aspergillus fischeri and Aspergillus oerlinghausenensis , and the cryptic pathogen Aspergillus lentulus . After identifying 62 proteins uniquely expressed on the A. fumigatus conidial surface, we deleted 42 genes encoding conidial proteins. We found deletion of 33 of these genes altered susceptibility to macrophage killing, penetration and damage to epithelial cells, and cytokine production. Notably, a gene that encodes glycosylasparaginase, which modulates levels of the host pro-inflammatory cytokine IL-1β, is important for infection in an immunocompetent murine model of fungal disease. These results suggest that A. fumigatus conidial surface proteins and effectors are important for evasion and modulation of the immune response at the onset of fungal infection.

Disruption of the Aspergillus fumigatus RNA interference machinery alters the conidial transcriptome

The RNA interference (RNAi) pathway has evolved numerous functionalities in eukaryotes, with many on display in Kingdom Fungi. RNAi can regulate gene expression, facilitate drug resistance, or even be altogether lost to improve growth potential in some fungal pathogens. In the WHO fungal priority pathogen, Aspergillus fumigatus, the RNAi system is known to be intact and functional. To extend our limited understanding of A. fumigatus RNAi, we first investigated the genetic variation in RNAi-associated genes in a collection of 217 environmental and 83 clinical genomes, where we found that RNAi components are conserved even in clinical strains. Using endogenously expressed inverted-repeat transgenes complementary to a conditionally essential gene (pabA) or a nonessential gene (pksP), we determined that a subset of the RNAi componentry is active in inverted-repeat transgene silencing in conidia and mycelium. Analysis of mRNA-seq data from RNAi double-knockout strains linked the A. fumigatus dicer-like enzymes (DclA/B) and RNA-dependent RNA polymerases (RrpA/B) to regulation of conidial ribosome biogenesis genes; however, surprisingly few endogenous small RNAs were identified in conidia that could explain this broad change. Although RNAi was not clearly linked to growth or stress response defects in the RNAi knockouts, serial passaging of RNAi knockout strains for six generations resulted in lineages with diminished spore production over time, indicating that loss of RNAi can exert a fitness cost on the fungus. Cumulatively, A. fumigatus RNAi appears to play an active role in defense against double-stranded RNA species alongside a previously unappreciated housekeeping function in regulation of conidial ribosomal biogenesis genes.

Streptomyces polyketides mediate bacteria-fungi interactions across soil environments

Although the interaction between prokaryotic and eukaryotic microorganisms is crucial for the functioning of ecosystems, information about the processes driving microbial interactions within communities remains scarce. Here we show that arginine-derived polyketides (arginoketides) produced by Streptomyces species mediate cross-kingdom microbial interactions with fungi of the genera Aspergillus and Penicillium, and trigger the production of natural products. Arginoketides can be cyclic or linear, and a prominent example is azalomycin F produced by Streptomyces iranensis, which induces the cryptic orsellinic acid gene cluster in Aspergillus nidulans. Bacteria that synthesize arginoketides and fungi that decode and respond to this signal were co-isolated from the same soil sample. Genome analyses and a literature search indicate that arginoketide producers are found worldwide. Because, in addition to their direct impact, arginoketides induce a secondary wave of fungal natural products, they probably contribute to the wider structure and functioning of entire soil microbial communities.

Functional analysis of the Aspergillus fumigatus kinome reveals a DYRK kinase involved in septal plugging is a novel antifungal drug target

More than 10 million people suffer from lung diseases caused by the pathogenic fungus Aspergillus fumigatus. The azole class of antifungals represent first line therapeutics for most of these infections however resistance is rising. Identification of novel antifungal targets that, when inhibited, synergise with the azoles will aid the development of agents that can improve therapeutic outcomes and supress the emergence of resistance. As part of the A. fumigatus genome-wide knockout program (COFUN), we have completed the generation of a library that consists of 120 genetically barcoded null mutants in genes that encode the protein kinase cohort of A. fumigatus. We have employed a competitive fitness profiling approach (Bar-Seq), to identify targets which when deleted result in hypersensitivity to the azoles and fitness defects in a murine host. The most promising candidate from our screen is a previously uncharacterised DYRK kinase orthologous to Yak1 of Candida albicans, a TOR signalling pathway kinase involved in modulation of stress responsive transcriptional regulators. Here we show that the orthologue YakA has been repurposed in A. fumigatus to regulate blocking of the septal pore upon exposure to stress via phosphorylation of the Woronin body tethering protein Lah. Loss of YakA function reduces the ability of A. fumigatus to penetrate solid media and impacts growth in murine lung tissue. We also show that 1-ethoxycarbonyl-beta-carboline (1-ECBC), a compound previously shown to inhibit Yak1 in C. albicans prevents stress mediated septal spore blocking and synergises with the azoles to inhibit A. fumigatus growth.

Control of TurboID-dependent biotinylation intensity in proximity ligation screens

Proximity biotinylation screens are a widely used strategy for the unbiased identification of interacting or vicinal proteins. The latest generation biotin ligase TurboID has broadened the range of potential applications, as this ligase promotes an intense and faster biotinylation, even in subcellular compartments like the endoplasmic reticulum. On the other hand, the uncontrollable high basal biotinylation rates deny the system's inducibility and are often associated with cellular toxicity precluding its use in proteomics. We report here an improved method for TurboID-dependent biotinylation reactions based on the tight control of free biotin levels. Blockage of free biotin with a commercial biotin scavenger reversed the high basal biotinylation and toxicity of TurboID, as shown by pulse-chase experiments. Accordingly, the biotin-blockage protocol restored the biological activity of a bait protein fused to TurboID in the endoplasmic reticulum and rendered the biotinylation reaction inducible by exogenous biotin. Importantly, the biotin-blockage protocol was more effective than biotin removal with immobilized avidin and did not affect the cellular viability of human monocytes over several days. The method presented should be useful to researchers interested in exploiting the full potential of biotinylation screens with TurboID and other high-activity ligases for challenging proteomics questions. SIGNIFICANCE: Proximity biotinylation screens using the last generation biotin ligase TurboID represent a powerful approach for the characterisation of transient protein-protein interaction and signaling networks. However, a constant and high basal biotinylation rate and the associated cytotoxicity often preclude the use of this method in proteomic studies. We report a protocol based on modulation of free biotin levels that prevents the deleterious effects of TurboID while allowing inducible biotinylation, even in subcellular compartments such as the endoplasmic reticulum. This optimised protocol greatly expands the applications of TurboID in proteomic screens.

Aspergillus fumigatus hijacks human p11 to redirect fungal-containing phagosomes to non-degradative pathway

The decision whether endosomes enter the degradative or recycling pathway in mammalian cells is of fundamental importance for pathogen killing, and its malfunctioning has pathological consequences. We discovered that human p11 is a critical factor for this decision. The HscA protein present on the conidial surface of the human-pathogenic fungus Aspergillus fumigatus anchors p11 on conidia-containing phagosomes (PSs), excludes the PS maturation mediator Rab7, and triggers binding of exocytosis mediators Rab11 and Sec15. This reprogramming redirects PSs to the non-degradative pathway, allowing A. fumigatus to escape cells by outgrowth and expulsion as well as transfer of conidia between cells. The clinical relevance is supported by the identification of a single nucleotide polymorphism in the non-coding region of the S100A10 (p11) gene that affects mRNA and protein expression in response to A. fumigatus and is associated with protection against invasive pulmonary aspergillosis. These findings reveal the role of p11 in mediating fungal PS evasion.

Perturbations of mesenchymal stromal cells after allogeneic hematopoietic cell transplantation predispose for bone marrow graft-versus-host-disease

Functional impairment of the bone marrow (BM) niche has been suggested as a major reason for prolonged cytopenia and secondary graft failure after allogeneic hematopoietic cell transplantation (alloHCT). Because mesenchymal stromal cells (MSCs) serve as multipotent progenitors for several niche components in the BM, they might play a key role in this process. We used collagenase digested trephine biopsies to directly quantify MSCs in 73 patients before (n = 18) and/or after alloHCT (n = 65). For the first time, we demonstrate that acute graft-versus-host disease (aGvHD, n = 39) is associated with a significant decrease in MSC numbers. MSC reduction can be observed even before the clinical onset of aGvHD (n = 10). Assessing MSCs instantly after biopsy collection revealed phenotypic and functional differences depending on the occurrence of aGvHD. These differences vanished during ex vivo expansion. The MSC endotypes observed revealed an enhanced population of donor-derived classical dendritic cells type 1 and alloreactive T cells as the causing agent for compartmental inflammation and MSC damage before clinical onset of aGvHD was ascertained. In conclusion, MSCs endotypes may constitute a predisposing conductor of alloreactivity after alloHCT preceding the clinical diagnosis of aGvHD.

Total Synthesis and Functional Evaluation of IORs, Sulfonolipid-based Inhibitors of Cell Differentiation in Salpingoeca rosetta

The choanoflagellate Salpingoeca rosetta is an important model system to study the evolution of multicellularity. In this study we developed a new, modular, and scalable synthesis of sulfonolipid IOR-1A (six steps, 27 % overall yield), which acts as bacterial inhibitor of rosette formation in S. rosetta. The synthesis features a decarboxylative cross-coupling reaction of a sulfonic acid-containing tartaric acid derivative with alkyl zinc reagents. Synthesis of 15 modified IOR-1A derivatives, including fluorescent and photoaffinity-based probes, allowed quantification of IOR-1A, localization studies within S. rosetta cells, and evaluation of structure-activity relations. In a proof of concept study, an inhibitory bifunctional probe was employed in proteomic profiling studies, which allowed to deduce binding partners in bacteria and S. rosetta. These results showcase the power of synthetic chemistry to decipher the biochemical basis of cell differentiation processes within S. rosetta.

CORK1, A LRR-Malectin Receptor Kinase, Is Required for Cellooligomer-Induced Responses in Arabidopsis thaliana

Cell wall integrity (CWI) maintenance is central for plant cells. Mechanical and chemical distortions, pH changes, and breakdown products of cell wall polysaccharides activate plasma membrane-localized receptors and induce appropriate downstream responses. Microbial interactions alter or destroy the structure of the plant cell wall, connecting CWI maintenance to immune responses. Cellulose is the major polysaccharide in the primary and secondary cell wall. Its breakdown generates short-chain cellooligomers that induce Ca²⁺-dependent CWI responses. We show that these responses require the malectin domain-containing CELLOOLIGOMER-RECEPTOR KINASE 1 (CORK1) in Arabidopsis and are preferentially activated by cellotriose (CT). CORK1 is required for cellooligomer-induced cytoplasmic Ca²⁺ elevation, reactive oxygen species (ROS) production, mitogen-associated protein kinase (MAPK) activation, cellulose synthase phosphorylation, and the regulation of CWI-related genes, including those involved in biosynthesis of cell wall material, secondary metabolites and tryptophan. Phosphoproteome analyses identified early targets involved in signaling, cellulose synthesis, the endoplasmic reticulum/Golgi secretory pathway, cell wall repair and immune responses. Two conserved phenylalanine residues in the malectin domain are crucial for CORK1 function. We propose that CORK1 is required for CWI and immune responses activated by cellulose breakdown products.

P343 Novel hydrophobic binding surface proteins are instrumental for phagocytosis of Lichtheimia corymbifera by macrophages

 

Poster session 3, September 23, 2022, 12:30 PM - 1:30 PM

Objectives

Methods

Two strains of L. corymbifera (JMRC: FSU: 09682 and JMRC: FSU: 10164) were used in this study. For phagocytosis assay, the spores were labeled with 0.1 mg/ml Fluorescein isothiocyanate (FITC) (Sigma Aldrich Chemie) in 0.1 M Na2CO3 for 30 min 146 at 30°C. Murine alveolar macrophages MH-S (ATCC:CRL-2019) were cultivated in RPMI-1640 (Sigma, 30-2001) supplemented.

Identification of the surface proteins of L. corymbifera was carried out as described before with minor modification.¹ The supernatants were stored at −80°C for liquid chromatography-mass spectrometry (LC-MS/MS) analysis. Secreted proteins of L. corymbifera were determined as described in a previous study with minor modification².

The raw files generated by the LC-MS/MS were further processed by the software Proteome Discoverer v1.4.0.288 (Thermo). Tandem mass spectra were searched against the NCBI L. corymbifera protein database.³ Approximately 10 000 MH-S cells were cultivated onto 96-well microplates (NUNC 163320) in 100 μL RPMI-1640 medium (Sigma, 30-2001). Images were acquired by the Zeiss Axio Observer 7 Spinning Disk Confocal Microscope (ZEISS, Jena, Germany) and processed with ZEN 2.1 Software (ZEISS) by 63x objective lens.

Results

Abundant surface proteins were found which serve as Candidates for secretome analysis. A total of 113 proteins were identified. Thirty proteins were confirmed to be on the spore surface based on the presence of signal peptides³. The following proteins were predominantly identified: Spore coat protein (CotH), hydrophobic surface binding protein A (HsbA), aconitase, ricin-like lectin, two transition elongation factors, multi-copper oxidase, heat shock protein 70 family (Hsp70), malate synthase, putative allergen Candidates, etc.

These proteins were heterologsly overexpressed in yeast. Successful overexpression was confirmed by LC-MS/MS. The yeast mutants were subjected to phagocytosis assays (Fig. 1). The role of surface proteins in macrophages is discussed.

Conclusion

The surface proteins are instrumental for recognition of L. corymbifera by macrophages and for intracellular survival in macrophages. The role of surface proteins is discussed in the light of evolution from environmental to human pathogenic fungus.

Sources:

S7.4d Candida albicans SR-like protein kinases regulate different cellular processes: Sky1 is involved in thecontrol of ion homeostasis, while Sky2 is important for dipeptide utilization

S7.4 Pathogenesis and host defense, September 23, 2022, 10:30 AM - 12:00 PM

 

 

Protein kinases play a crucial role in regulating cellular processes such as growth, proliferation, environmental adaptation, and stress responses. Candida albicans genome comprises of 108 predicted protein kinases, of which the exact role of nearly half of those kinases remains unknown. One family of protein kinases is serine-arginine (SR) protein kinases, which are highly conserved in eukaryotes and regulate fundamental processes such as constitutive and alternative splicing, mRNA processing, and ion homeostasis. The C. albicans genome encodes two (Sky1, Sky2) and the C. glabrata genome has one homolog (Sky1) of the human SR protein kinase 1, but their functions have not yet been investigated. We used deletion strains of the corresponding genes in both fungi to study their cellular functions. C. glabrata and C. albicans strains lacking SKY1 exhibited higher resistance to osmotic stress and toxic polyamine concentrations, similar to their ortholog Sky1 in Saccharomyces cerevisiae. Deletion of SKY2 in C. albicans resulted in impaired utilization of various dipeptides as the sole nitrogen source which was shown by utilizing a high-throughput phenotypic screen. Subsequent phosphoproteomic analysis identified the di- and tri-peptide transporter Ptr22 as a potential Sky2 substrate. Our data suggest that Sky2 seems to be involved in Ptr22 regulation since overexpression of PTR22 in the sky2∆ mutant restored the ability to grow on dipeptides and made the cells more susceptible to the dipeptide antifungals Polyoxin D and Nikkomycin Z. Altogether, our results demonstrate that C. albicans and C. glabrata Sky1 protein kinases are functionally similar to Sky1 in S. cerevisiae, whereas C. albicans Sky2, a unique kinase of the CTG clade, likely regulates dipeptide uptake via Ptr22.

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.

Candida albicans SR-Like Protein Kinases Regulate Different Cellular Processes: Sky1 Is Involved in Control of Ion Homeostasis, While Sky2 Is Important for Dipeptide Utilization

Protein kinases play a crucial role in regulating cellular processes such as growth, proliferation, environmental adaptation and stress responses. Serine-arginine (SR) protein kinases are highly conserved in eukaryotes and regulate fundamental processes such as constitutive and alternative splicing, mRNA processing and ion homeostasis. The Candida albicans genome encodes two (Sky1, Sky2) and the Candida glabrata genome has one homolog (Sky1) of the human SR protein kinase 1, but their functions have not yet been investigated. We used deletion strains of the corresponding genes in both fungi to study their cellular functions. C. glabrata and C. albicans strains lacking SKY1 exhibited higher resistance to osmotic stress and toxic polyamine concentrations, similar to Saccharomyces cerevisiae sky1Δ mutants. Deletion of SKY2 in C. albicans resulted in impaired utilization of various dipeptides as the sole nitrogen source. Subsequent phosphoproteomic analysis identified the di- and tripeptide transporter Ptr22 as a potential Sky2 substrate. Sky2 seems to be involved in Ptr22 regulation since overexpression of PTR22 in the sky2Δ mutant restored the ability to grow on dipeptides and made the cells more susceptible to the dipeptide antifungals Polyoxin D and Nikkomycin Z. Altogether, our results demonstrate that C. albicans and C. glabrata Sky1 protein kinases are functionally similar to Sky1 in S. cerevisiae, whereas C. albicans Sky2, a unique kinase of the CTG clade, likely regulates dipeptide uptake via Ptr22.

Exploring planet geology through force-feedback telemanipulation from orbit

Current space exploration roadmaps envision exploring the surface geology of celestial bodies with robots for both scientific research and in situ resource utilization. In such unstructured, poorly lit, complex, and remote environments, automation is not always possible, and some tasks, such as geological sampling, require direct teleoperation aided by force-feedback (FF). The operator would be on an orbiting spacecraft, and poor bandwidth, high latency, and packet loss from orbit to ground mean that safe, stable, and transparent interaction is a substantial technical challenge. For this scenario, a control method was developed that ensures stability at high delay without reduction in speed or loss of positioning accuracy. At the same time, a new level of safety is achieved not only through FF itself but also through an intrinsic property of the approach preventing hard impacts. On the basis of this method, a tele-exploration scenario was simulated in the Analog-1 experiment with an astronaut on the International Space Station (ISS) using a 6-degree-of-freedom (DoF) FF capable haptic input device to control a mobile robot with manipulator on Earth to collect rock samples. The 6-DoF FF telemanipulation from space was performed at a round-trip communication delay constantly between 770 and 850 milliseconds and an average packet loss of 1.27%. This experiment showcases the feasibility of a complete space exploration scenario via haptic telemanipulation under spaceflight conditions. The results underline the benefits of this control method for safe and accurate interactions and of haptic feedback in general.

PLB-985 Neutrophil-Like Cells as a Model To Study Aspergillus fumigatus Pathogenesis

Fungal infections remain a major global concern. Emerging fungal pathogens and increasing rates of resistance mean that additional research efforts and resources must be allocated to advancing our understanding of fungal pathogenesis and developing new therapeutic interventions. Neutrophilic granulocytes are a major cell type involved in protection against the important fungal pathogen Aspergillus fumigatus, where they employ numerous defense mechanisms, including production of antimicrobial extracellular vesicles. A major drawback to work with neutrophils is the lack of a suitable cell line system for the study of fungal pathogenesis. To address this problem, we assessed the feasibility of using differentiated PLB-985 neutrophil-like cells as an in vitro model to study A. fumigatus infection. We find that dimethylformamide-differentiated PLB-985 cells provide a useful recapitulation of many aspects of A. fumigatus interactions with primary human polymorphonuclear leukocytes. We show that differentiated PLB-985 cells phagocytose fungal conidia and acidify conidia-containing phagolysosomes similar to primary neutrophils, release neutrophil extracellular traps, and also produce antifungal extracellular vesicles in response to infection. In addition, we provide an improved method for the isolation of extracellular vesicles produced during infection by employing a size exclusion chromatography-based approach. Advanced liquid chromatography-tandem mass spectrometry (LC-MS/MS) proteomics revealed an enrichment of extracellular vesicle marker proteins and a decrease of cytoplasmic proteins in extracellular vesicles isolated using this improved method. Ultimately, we find that differentiated PLB-985 cells can serve as a genetically tractable model to study many aspects of A. fumigatus pathogenesis. IMPORTANCE Polymorphonuclear leukocytes are an important defense against human fungal pathogens, yet our model systems to study this group of cells remain very limited in scope. In this study, we established that differentiated PLB-985 cells can serve as a model to recapitulate several important aspects of human polymorphonuclear leukocyte interactions with the important human fungal pathogen Aspergillus fumigatus. The proposed addition of a cultured neutrophil-like cell line to the experimental toolbox to study fungal pathogenesis will allow for a more mechanistic description of neutrophil antifungal biology. In addition, the easier handling of the cell line compared to primary human neutrophils allowed us to use PLB-985 cells to provide an improved method for isolation of neutrophil-derived extracellular vesicles using size exclusion chromatography. Together, these results provide significant tools and a baseline knowledge for the future study of neutrophil-derived extracellular vesicles in the laboratory.

Comparative Secretome Analyses of Trichoderma/Arabidopsis Co-cultures Identify Proteins for Salt Stress, Plant Growth Promotion, and Root Colonization

Numerous Trichoderma strains are beneficial for plants, promote their growth, and confer stress tolerance. A recently described novel Trichoderma strain strongly promotes the growth of Arabidopsis thaliana seedlings on media with 50 mM NaCl, while 150 mM NaCl strongly stimulated root colonization and induced salt-stress tolerance in the host without growth promotion. To understand the dynamics of plant-fungus interaction, we examined the secretome from both sides and revealed a substantial change under different salt regimes, and during co-cultivation. Stress-related proteins, such as a fungal cysteine-rich Kp4 domain-containing protein which inhibits plant cell growth, fungal WSC- and CFEM-domain-containing proteins, the plant calreticulin, and cell-wall modifying enzymes, disappear when the two symbionts are co-cultured under high salt concentrations. In contrast, the number of lytic polysaccharide monooxygenases increases, which indicates that the fungus degrades more plant lignocellulose under salt stress and its lifestyle becomes more saprophytic. Several plant proteins involved in plant and fungal cell wall modifications and root colonization are only found in the co-cultures under salt stress, while the number of plant antioxidant proteins decreased. We identified symbiosis- and salt concentration-specific proteins for both partners. The Arabidopsis PYK10 and a fungal prenylcysteine lyase are only found in the co-culture which promoted plant growth. The comparative analysis of the secretomes supports antioxidant enzyme assays and suggests that both partners profit from the interaction under salt stress but have to invest more in balancing the symbiosis. We discuss the role of the identified stage- and symbiosis-specific fungal and plant proteins for salt stress, and conditions promoting root colonization and plant growth.

Functionality of the human antibody response to Candida albicans

Candida albicans is a common commensal on human mucosal surfaces, but can become pathogenic, e.g. if the host is immunocompromised. While neutrophils, macrophages and T cells are regarded as major players in the defense against pathogenic C. albicans, the role of B cells and the protective function of their antibodies are less well characterized. In this study, we show that human serum antibodies are able to enhance the association of human THP-1 monocyte-like cells with C. albicans cells. Human serum antibodies are also capable of inhibiting the adherence and damage dealt to epithelial cells. Furthermore, human serum antibodies impair C. albicans invasion of human oral epithelial cells by blocking induced endocytosis and consequently host cell damage. While aspartic proteases secreted by C. albicans are able to cleave human IgG, this process does not appear to affect the protective function of human antibodies. Thus, humans are equipped with a robust antibody response to C. albicans, which can enhance antifungal activities and prevent fungal-mediated epithelial damage.

The fungivorous amoeba Protostelium aurantium targets redox homeostasis and cell wall integrity during intracellular killing of Candida parapsilosis

Predatory interactions among microbes are major evolutionary driving forces for biodiversity. The fungivorous amoeba Protostelium aurantium has a wide fungal food spectrum including foremost pathogenic members of the genus Candida. Here we show that upon phagocytic ingestion by the amoeba, Candida parapsilosis is confronted with an oxidative burst and undergoes lysis within minutes of processing in acidified phagolysosomes. On the fungal side, a functional genomic approach identified copper and redox homeostasis as primary targets of amoeba predation, with the highly expressed copper exporter gene CRP1 and the peroxiredoxin gene PRX1 contributing to survival when encountered with P. aurantium. The fungicidal activity was largely retained in intracellular vesicles of the amoebae. Following their isolation, the content of these vesicles induced immediate killing and lysis of C. parapsilosis in vitro. Proteomic analysis identified 56 vesicular proteins from P. aurantium. Although completely unknown proteins were dominant, many of them could be categorised as hydrolytic enzymes targeting the fungal cell wall, indicating that fungal cell wall structures are under selection pressure by predatory phagocytes in natural environments. TAKE AWAY: The amoeba Protostelium aurantium feeds on fungi, such as Candida parapsilosis. Ingested yeast cells are exposed to reactive oxygen species. A copper exporter and a peroxiredoxin contribute to fungal defence. Yeast cells undergo intracellular lysis. Lysis occurs via a cocktail of hydrolytic enzymes from intracellular vesicles.

The bZIP Transcription Factor HapX Is Post-Translationally Regulated to Control Iron Homeostasis in Aspergillus fumigatus

The airborne fungus Aspergillus fumigatus causes opportunistic infections in humans with high mortality rates in immunocompromised patients. Previous work established that the bZIP transcription factor HapX is essential for virulence via adaptation to iron limitation by repressing iron-consuming pathways and activating iron acquisition mechanisms. Moreover, HapX was shown to be essential for transcriptional activation of vacuolar iron storage and iron-dependent pathways in response to iron availability. Here, we demonstrate that HapX has a very short half-life during iron starvation, which is further decreased in response to iron, while siderophore biosynthetic enzymes are very stable. We identified Fbx22 and SumO as HapX interactors and, in agreement, HapX post-translational modifications including ubiquitination of lysine¹⁶¹, sumoylation of lysine²⁴² and phosphorylation of threonine³¹⁹. All three modifications were enriched in the immediate adaptation from iron-limiting to iron-replete conditions. Interfering with these post-translational modifications, either by point mutations or by inactivation, of Fbx22 or SumO, altered HapX degradation, heme biosynthesis and iron resistance to different extents. Consistent with the need to precisely regulate HapX protein levels, overexpression of hapX caused significant growth defects under iron sufficiency. Taken together, our results indicate that post-translational regulation of HapX is important to control iron homeostasis in A. fumigatus.

Candidalysin delivery to the invasion pocket is critical for host epithelial damage induced by Candida albicans

The human pathogenic fungus Candida albicans is a frequent cause of mucosal infections. Although the ability to transition from the yeast to the hypha morphology is essential for virulence, hypha formation and host cell invasion per se are not sufficient for the induction of epithelial damage. Rather, the hypha-associated peptide toxin, candidalysin, a product of the Ece1 polyprotein, is the critical damaging factor. While synthetic, exogenously added candidalysin is sufficient to damage epithelial cells, the level of damage does not reach the same level as invading C. albicans hyphae. Therefore, we hypothesized that a combination of fungal attributes is required to deliver candidalysin to the invasion pocket to enable the full damaging potential of C. albicans during infection. Utilising a panel of C. albicans mutants with known virulence defects, we demonstrate that the full damage potential of C. albicans requires the coordinated delivery of candidalysin to the invasion pocket. This process requires appropriate epithelial adhesion, hyphal extension and invasion, high levels of ECE1 transcription, proper Ece1 processing and secretion of candidalysin. To confirm candidalysin delivery, we generated camelid V_H Hs (nanobodies) specific for candidalysin and demonstrate localization and accumulation of the toxin only in C. albicans-induced invasion pockets. In summary, a defined combination of virulence attributes and cellular processes is critical for delivering candidalysin to the invasion pocket to enable the full damage potential of C. albicans during mucosal infection. TAKE AWAYS: Candidalysin is a peptide toxin secreted by C. albicans causing epithelial damage. Candidalysin delivery to host cell membranes requires specific fungal attributes. Candidalysin accumulates in invasion pockets created by invasive hyphae. Camelid nanobodies enabled visualisation of candidalysin in the invasion pocket.

Bacterial cell wall-degrading enzymes induce basidiomycete natural product biosynthesis

Natural products play a vital role for intermicrobial interactions. In the basidiomycete arena an important representative is variegatic acid, a lactone natural product pigment whose ecological relevance stems from both inhibiting bacterial swarming and from indirect participation in breakdown of organic matter by brown-rotting fungi. Previous work showed that the presence of bacteria stimulates variegatic acid production. However, the actual external molecular trigger that prompts its biosynthesis in the mushroom hyphae remained unknown. Here, we report on the identification of Bacillus subtilis subtilisin E (AprE) and chitosanase (Csn) as primary inducers of pulvinic acid pigment formation. Using the established co-culture system of B. subtilis and Serpula lacrymans, we used activity-guided FPLC-based fractionation of B. subtilis culture supernatants and subsequent peptide fingerprinting to identify candidates, and their role was corroborated by means of a pigment production assay using heterologously produced chitosanase and subtilisin. B. subtilis mutants defective in either the aprE or the csn gene still triggered pigmentation, yet to a lower degree, which points to a multicausal scenario and suggests the combined activity of these cell wall polymer-attacking enzymes as true stimulus.

Inositol Signaling in the Basidiomycete Fungus Schizophyllum commune

Intracellular signaling is conserved in eukaryotes to allow for response to extracellular signals and to regulate development and cellular functions. In fungi, inositol phosphate signaling has been shown to be involved in growth, sexual reproduction, and metabolic adaptation. However, reports on mushroom-forming fungi are lacking so far. In Schizophyllum commune, an inositol monophosphatase has been found up-regulated during sexual development. The enzyme is crucial for inositol cycling, where it catalyzes the last step of inositol phosphate metabolism, restoring the inositol pool from the monophosphorylated inositol monophosphate. We overexpressed the gene in this model basidiomycete and verified its involvement in cell wall integrity and intracellular trafficking. Strong phenotypes in mushroom formation and cell metabolism were evidenced by proteome analyses. In addition, altered inositol signaling was shown to be involved in tolerance towards cesium and zinc, and increased metal tolerance towards cadmium, associated with induced expression of kinases and repression of phosphatases within the inositol cycle. The presence of the heavy metals Sr, Cs, Cd, and Zn lowered intracellular calcium levels. We could develop a model integrating inositol signaling in the known signal transduction pathways governed by Ras, G-protein coupled receptors, and cAMP, and elucidate their different roles in development.

AIDeveloper: Deep Learning Image Classification in Life Science and Beyond

Artificial intelligence (AI)-based image analysis has increased drastically in recent years. However, all applications use individual solutions, highly specialized for a particular task. Here, an easy-to-use, adaptable, and open source software, called AIDeveloper (AID) to train neural nets (NN) for image classification without the need for programming is presented. AID provides a variety of NN-architectures, allowing to apply trained models on new data, obtain performance metrics, and export final models to different formats. AID is benchmarked on large image datasets (CIFAR-10 and Fashion-MNIST). Furthermore, models are trained to distinguish areas of differentiated stem cells in images of cell culture. A conventional blood cell count and a blood count obtained using an NN are compared, trained on >1.2 million images, and demonstrated how AID can be used for label-free classification of B- and T-cells. All models are generated by non-programmers on generic computers, allowing for an interdisciplinary use.

Modeling ternary fluids in contact with elastic membranes

We present a thermodynamically consistent model of a ternary fluid interacting with elastic membranes. Following a free-energy modeling approach for the fluid phases, we derive the governing equations for the dynamics of the ternary fluid flow and membranes. We also provide the numerical framework for simulating such fluid-structure interaction problems. It is based on the lattice Boltzmann method for the ternary fluid (Eulerian description) and a finite difference representation of the membrane (Lagrangian description). The ternary fluid and membrane solvers are coupled through the immersed boundary method. For validation purposes, we consider the relaxation dynamics of a two-dimensional elastic capsule placed at a fluid-fluid interface. The capsule shapes, resulting from the balance of surface tension and elastic forces, are compared with equilibrium numerical solutions obtained by surface evolver. Furthermore, the Galilean invariance of the proposed model is proven. The proposed approach is versatile, allowing for the simulation of a wide range of geometries. To demonstrate this, we address the problem of a capillary bridge formed between two deformable capsules.

Carbon Catabolite Repression in Filamentous Fungi Is Regulated by Phosphorylation of the Transcription Factor CreA

Filamentous fungi of the genus Aspergillus are of particular interest for biotechnological applications due to their natural capacity to secrete carbohydrate-active enzymes (CAZy) that target plant biomass. The presence of easily metabolizable sugars such as glucose, whose concentrations increase during plant biomass hydrolysis, results in the repression of CAZy-encoding genes in a process known as carbon catabolite repression (CCR), which is undesired for the purpose of large-scale enzyme production. To date, the C2H2 transcription factor CreA has been described as the major CC repressor in Aspergillus spp., although little is known about the role of posttranslational modifications in this process. In this work, phosphorylation sites were identified by mass spectrometry on Aspergillus nidulans CreA, and subsequently, the previously identified but uncharacterized site S262, the characterized site S319, and the newly identified sites S268 and T308 were chosen to be mutated to nonphosphorylatable residues before their effect on CCR was investigated. Sites S262, S268, and T308 are important for CreA protein accumulation and cellular localization, DNA binding, and repression of enzyme activities. In agreement with a previous study, site S319 was not important for several here-tested phenotypes but is key for CreA degradation and induction of enzyme activities. All sites were shown to be important for glycogen and trehalose metabolism. This study highlights the importance of CreA phosphorylation sites for the regulation of CCR. These sites are interesting targets for biotechnological strain engineering without the need to delete essential genes, which could result in undesired side effects.IMPORTANCE In filamentous fungi, the transcription factor CreA controls carbohydrate metabolism through the regulation of genes encoding enzymes required for the use of alternative carbon sources. In this work, phosphorylation sites were identified on Aspergillus nidulans CreA, and subsequently, the two newly identified sites S268 and T308, the previously identified but uncharacterized site S262, and the previously characterized site S319 were chosen to be mutated to nonphosphorylatable residues before their effect on CCR was characterized. Sites S262, S268, and T308 are important for CreA protein accumulation and cellular localization, DNA binding, and repression of enzyme activities. In agreement with a previous study, site S319 is not important for several here-tested phenotypes but is key for CreA degradation and induction of enzyme activities. This work characterized novel CreA phosphorylation sites under carbon catabolite-repressing conditions and showed that they are crucial for CreA protein turnover, control of carbohydrate utilization, and biotechnologically relevant enzyme production.

The Role of RodA-Conserved Cysteine Residues in the Aspergillus fumigatus Conidial Surface Organization

Immune inertness of Aspergillusfumigatus conidia is attributed to its surface rodlet-layer made up of RodAp, characterized by eight conserved cysteine residues forming four disulfide bonds. Earlier, we showed that the conserved cysteine residue point (ccrp) mutations result in conidia devoid of the rodlet layer. Here, we extended our study comparing the surface organization and immunoreactivity of conidia carrying ccrp-mutations with the RODA deletion mutant (∆rodA). Western blot analysis using anti-RodAp antibodies indicated the absence of RodAp in the cytoplasm of ccrp-mutant conidia. Immunolabeling revealed differential reactivity to conidial surface glucans, the ccrp-mutant conidia preferentially binding to α-(1,3)-glucan, ∆rodA conidia selectively bound to β-(1,3)-glucan; the parental strain conidia showed negative labeling. However, permeability of ccrp-mutants and ∆rodA was similar to the parental strain conidia. Proteomic analyses of the conidial surface exposed proteins of the ccrp-mutants showed more similarities with the parental strain, but were significantly different from the ∆rodA. Ccrp-mutant conidia were less immunostimulatory compared to ∆rodA conidia. Our data suggest that (i) the conserved cysteine residues are essential for the trafficking of RodAp and the organization of the rodlet layer on the conidial surface, and (ii) targeted point mutation could be an alternative approach to study the role of fungal cell-wall genes in host–fungal interaction.

Biotinylated Surfome Profiling Identifies Potential Biomarkers for Diagnosis and Therapy of Aspergillus fumigatus Infection

Aspergillus fumigatus is one of the most common airborne molds capable of causing mycoses and allergies in humans. During infection, fungal surface proteins mediate the first contact with the human immune system to evade immune responses or to induce hypersensitivity. Several methods have been established for surface proteomics (surfomics). Biotinylation coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) identification of peptides is a particularly efficient method to identify the surface-exposed regions of proteins that potentially mediate interaction with the host. After biotinylation of surface proteins during spore germination, we detected 231 different biotinylated surface proteins (including several well-known proteins such as RodA, CcpA, and DppV; allergens; and heat shock proteins [HSPs]), as well as some previously undescribed surface proteins. The dynamic change of the surface proteome was illustrated by detection of a relatively high number of proteins exclusively at one developmental stage. Using immunofluorescence microscopy, we confirmed the surface localization of several HSPs of the HSP70 family, which may have moonlighting functions. Collectively, by comparing our data with data representative of previously published A. fumigatus surface proteomes, our study generated a comprehensive data set corresponding to the A. fumigatus surfome and uncovered the surface-exposed regions of many proteins on the surface of conidia or hyphae. These surface-exposed regions are candidates for direct interaction with host cells and may represent antigenic epitopes that either induce protective immune responses or mediate immune evasion. Thus, our data sets provided and compiled here represent reasonable immunotherapy and diagnostic targets for future investigations.IMPORTANCEAspergillus fumigatus is the most important airborne human-pathogenic mold, capable of causing both life-threatening invasive pulmonary aspergillosis in immunocompromised patients and allergy-inducing infections in individuals with atopic allergy. Despite its obvious medical relevance, timely diagnosis and efficient antifungal treatment of A. fumigatus infection remain major challenges. Proteins on the surface of conidia (asexually produced spores) and mycelium directly mediate host-pathogen interaction and also may serve as targets for diagnosis and immunotherapy. However, the similarity of protein sequences between A. fumigatus and other organisms, sometimes even including the human host, makes selection of targets for immunological-based studies difficult. Here, using surface protein biotinylation coupled with LC-MS/MS analysis, we identified hundreds of A. fumigatus surface proteins with exposed regions, further defining putative targets for possible diagnostic and immunotherapeutic design.

Functional surface proteomic profiling reveals the host heat-shock protein A8 as a mediator of Lichtheimia corymbifera recognition by murine alveolar macrophages

Mucormycosis is an emergent, fatal fungal infection of humans and warm-blooded animals caused by species of the order Mucorales. Immune cells of the innate immune system serve as the first line of defence against inhaled spores. Alveolar macrophages were challenged with the mucoralean fungus Lichtheimia corymbifera and subjected to biotinylation and streptavidin enrichment procedures followed by LC-MS/MS analyses. A total of 28 host proteins enriched for binding to macrophage-L. corymbifera interaction. Among those, the HSP70-family protein Hspa8 was found to be predominantly responsive to living and heat-killed spores of a virulent and an attenuated strain of L. corymbifera. Confocal scanning laser microscopy of infected macrophages revealed colocalization of Hspa8 with phagocytosed spores of L. corymbifera. The amount of detectable Hspa8 was dependent on the multiplicity of infection. Incubation of alveolar macrophages with an anti-Hspa8 antibody prior to infection reduced their capability to phagocytose spores of L. corymbifera. In contrast, anti-Hspa8 antibodies did not abrogate the phagocytosis of Aspergillus fumigatus conidia by macrophages. These results suggest an important contribution of the heat-shock family protein Hspa8 in the recognition of spores of the mucoralean fungus L. corymbifera by host alveolar macrophages and define a potential immunomodulatory therapeutic target.

Single-Step Formation of a Low Work Function Cathode Interlayer and n-type Bulk Doping from Semiconducting Polymer/Polyethylenimine Blend Solution

The use of polyethylenimine (PEI) as a thin interlayer between cathodes and organic semiconductors in order to reduce interfacial Ohmic losses has become an important approach in organic electronics. It has also been shown that such interlayers can form spontaneously because of vertical phase separation when spin-coating a blended solution of PEI and the semiconductor. Furthermore, bulk doping of semiconducting polymers by PEI has been claimed. However, to our knowledge, a clear delineation of interfacial from bulk effects has not been published. Here, we report a study on thin films formed by spin-coating blended solutions of PEI and poly{[N,N'-bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} [P(NDI2OD-T₂)] on indium tin oxide. We observed the vertical phase separation in such films, where PEI accumulates at the bottom and the top, sandwiching the semiconductor layer. The PEI interlayer on ITO reduces the electron injection barrier to the minimum value determined by Fermi level pinning, which, in turn, reduces the contact resistance by 5 orders of magnitude. Although we find no evidence for doping-induced polarons in P(NDI2OD-T₂) upon mixing with PEI from optical absorption, more sensitive electron paramagnetic resonance measurements provide evidence for doping and an increased carrier density, at a very low level. This, in conjunction with an increased charge carrier mobility due to trap filling, results in an increase in the mixed polymer conductivity by 4 orders of magnitude relative to pure P(NDI2OD-T₂). Consequently, both interfacial and bulk effects occur with notable magnitude in thin films formed from blended semiconductor polymer/PEI solution. Thus, this facile one-step procedure to form PEI interlayers must be applied with attention, as modification of the bulk semiconductor polymer (here doping) may occur simultaneously and might go un-noticed if not examined carefully.

Immune modulation by complement receptor 3-dependent human monocyte TGF-β1-transporting vesicles

Extracellular vesicles have an important function in cellular communication. Here, we show that human and mouse monocytes release TGF-β1-transporting vesicles in response to the pathogenic fungus Candida albicans. Soluble β-glucan from C. albicans binds to complement receptor 3 (CR3, also known as CD11b/CD18) on monocytes and induces the release of TGF-β1-transporting vesicles. CR3-dependence is demonstrated using CR3-deficient (CD11b knockout) monocytes generated by CRISPR-CAS9 genome editing and isolated from CR3-deficient (CD11b knockout) mice. These vesicles reduce the pro-inflammatory response in human M1-macrophages as well as in whole blood. Binding of the vesicle-transported TGF-β1 to the TGF-β receptor inhibits IL1B transcription via the SMAD7 pathway in whole blood and induces TGFB1 transcription in endothelial cells, which is resolved upon TGF-β1 inhibition. Notably, human complement-opsonized apoptotic bodies induce production of similar TGF-β1-transporting vesicles in monocytes, suggesting that the early immune response might be suppressed through this CR3-dependent anti-inflammatory vesicle pathway.

Calcar-Guided Short Stems in Total Hip Arthroplasty: A Two-Year Prospective Multicentre Study

Background:

Calcar-guided short-stem Total Hip Arthroplasty (THA) is increasingly being used to preserve proximal femoral bone stock for potential later revision surgery.

Objective:

In this study, we aimed to expand the clinical evidence on calcar-guided short-stem THA used in daily clinical practice, focusing on clinical outcomes as well as radiographic signs of stress shielding and femoral bone loss.

Methods:

In a prospective multicentre study, we enrolled 213 patients with a total of 224 THAs for mainly degenerative indications. The patients were examined clinically and radiographically 6 to 12 weeks, 12 months, and 24 months postoperatively.

Results:

All clinical outcomes improved significantly over the first 6 to 12 weeks compared to preoperative values (P < 0.001). At 24 months, the mean Harris hip score was 95.3 ± 6.7, and the mean visual analogue scale for pain was 1.0 ± 1.7 under load and 0.5 ± 1.3 at rest. We observed early distal stem migration in six patients and late migration in one patient. Additionally, we found 16 cases of radiographic signs indicative of stress shielding. Four patients required stem revision surgery: two for stem migration, one for periprosthetic fracture, and one for deep infection.

Conclusion:

Overall, calcar-guided short-stem THA resulted in excellent clinical outcomes after two years of follow-up, and the radiographs revealed few signs of stress shielding. We, therefore, regard calcar-guided short-stem THA as a safe and effective treatment alternative in daily clinical practice.

Dynamic Surface Proteomes of Allergenic Fungal Conidia

Fungal spores and hyphal fragments play an important role as allergens in respiratory diseases. In this study, we performed trypsin shaving and secretome analyses to identify the surface-exposed proteins and secreted/shed proteins of Aspergillus fumigatus conidia, respectively. We investigated the surface proteome under different conditions, including temperature variation and germination. We found that the surface proteome of resting A. fumigatus conidia is not static but instead unexpectedly dynamic, as evidenced by drastically different surface proteomes under different growth conditions. Knockouts of two abundant A. fumigatus surface proteins, ScwA and CweA, were found to function only in fine-tuning the cell wall stress response, implying that the conidial surface is very robust against perturbations. We then compared the surface proteome of A. fumigatus to other allergy-inducing molds, including Alternaria alternata, Penicillium rubens, and Cladosporium herbarum, and performed comparative proteomics on resting and swollen conidia, as well as secreted proteins from germinating conidia. We detected 125 protein ortholog groups, including 80 with putative catalytic activity, in the extracellular region of all four molds, and 42 nonorthologous proteins produced solely by A. fumigatus. Ultimately, this study highlights the dynamic nature of the A. fumigatus conidial surface and provides targets for future diagnostics and immunotherapy.

Targeted induction of a silent fungal gene cluster encoding the bacteria-specific germination inhibitor fumigermin

Microorganisms produce numerous secondary metabolites (SMs) with various biological activities. Many of their encoding gene clusters are silent under standard laboratory conditions because for their activation they need the ecological context, such as the presence of other microorganisms. The true ecological function of most SMs remains obscure, but understanding of both the activation of silent gene clusters and the ecological function of the produced compounds is of importance to reveal functional interactions in microbiomes. Here, we report the identification of an as-yet uncharacterized silent gene cluster of the fungus Aspergillus fumigatus, which is activated by the bacterium Streptomyces rapamycinicus during the bacterial-fungal interaction. The resulting natural product is the novel fungal metabolite fumigermin, the biosynthesis of which requires the polyketide synthase FgnA. Fumigermin inhibits germination of spores of the inducing S. rapamycinicus, and thus helps the fungus to defend resources in the shared habitat against a bacterial competitor.

Reliable isolation of human mesenchymal stromal cells from bone marrow biopsy specimens in patients after allogeneic hematopoietic cell transplantation

Isolation of mesenchymal stromal cells (MSCs) from pretreated, hematologic patients is challenging. Especially after allogeneic hematopoietic cell transplantation (HCT), standard protocols using bone marrow aspirates fail to reliably recover sufficient cell numbers. Because MSCs are considered to contribute to processes that mainly affect the outcome after transplantation, such as an efficient lymphohematopoietic recovery, extent of graft-versus-host disease as well as the occurrence of leukemic relapse, it is of great clinical relevance to investigate MSC function in this context. Previous studies showed that MSCs can be isolated by collagenase digestion of large bone fragments of hematologically healthy patients undergoing hip replacement or knee surgeries. We have now further developed this procedure for the isolation of MSCs from hematologic patients after allogeneic HCT by using trephine biopsy specimens obtained during routine examinations. Comparison of aspirates and trephine biopsy specimens from patients after allogeneic HCT revealed a significantly higher frequency of clonogenic MSCs (colony-forming unit-fibroblast [CFU-F]) in trephine biopsy specimens (mean, 289.8 ± standard deviation 322.5 CFU-F colonies/1 × 10⁶ total nucleated cells versus 4.2 ± 9.9; P < 0.0001). Subsequent expansion of functional MSCs isolated from trephine biopsy specimen was more robust and led to a significantly higher yield compared with control samples expanded from aspirates (median, 1.6 × 10⁶; range, 0-2.3 × 10⁷ P0 MSCs versus 5.4 × 10⁴; range, 0-8.9 × 10⁶; P < 0.0001). Using trephine biopsy specimens as MSC source facilitates the investigation of various clinical questions.

Redox Proteomic Analysis Reveals Oxidative Modifications of Proteins by Increased Levels of Intracellular Reactive Oxygen Species during Hypoxia Adaptation of Aspergillus fumigatus

Aspergillus fumigatus faces abrupt changes in oxygen concentrations at the site of infection. An increasing number of studies has demonstrated that elevated production of intracellular reactive oxygen species (ROS) under low oxygen conditions plays a regulatory role in modulating cellular responses for adaptation to hypoxia. To learn more about this process in A. fumigatus, intracellular ROS production during hypoxia has been determined. The results confirm increased amounts of intracellular ROS in A. fumigatus exposed to decreased oxygen levels. Moreover, nuclear accumulation of the major oxidative stress regulator AfYap1 is observed after low oxygen cultivation. For further analysis, iodoTMT labeling of redox-sensitive cysteine residues is applied to identify proteins that are reversibly oxidized. This analysis reveals that proteins with important roles in maintaining redox balance and protein folding, such as the thioredoxin Asp f 29 and the disulfide-isomerase PdiA, undergo substantial thiol modification under hypoxia. The data also show that the mitochondrial respiratory complex IV assembly protein Coa6 is significantly oxidized by hypoxic ROS. Deletion of the corresponding gene results in a complete absence of hypoxic growth, indicating the importance of complex IV during adaptation of A. fumigatus to oxygen-limiting conditions.