CD56-mediated activation of human natural killer cells is triggered by Aspergillus fumigatus galactosaminogalactan.

Invasive aspergillosis causes significant morbidity and mortality in immunocompromised patients. Natural killer (NK) cells are pivotal for antifungal defense. Thus far, CD56 is the only known pathogen recognition receptor on NK cells triggering potent antifungal activity against Aspergillus fumigatus.

Use of a human small airway epithelial cell line to study the interactions of with pulmonary epithelial cells.

During the initiation of invasive aspergillosis, inhaled conidia are deposited on the epithelial cells lining the bronchi, terminal bronchioles, and alveoli. While the interactions of with bronchial and type II alveolar cell lines have been investigated , little is known about the interactions of this fungus with terminal bronchiolar epithelial cells. Using the HSAEC1-KT human small airway epithelial (HSAE) cell line, we developed an model to study the interaction of two strains of with these cells.

Identification and Quantification of Monosaccharides from Fungal Cell Walls and Exopolysaccharides by Gas Chromatography Coupled to Mass Spectrometry.

The fungal cell wall and secreted exopolysaccharides play an important role in the interactions between fungi and their environment. Despite their central role in fungal biology, ecology, and host-pathogen interactions, the composition of these polymers and their synthetic pathways are not well understood. The protocols presented in this article describe an approach to isolate fungal cell wall polysaccharides and to identify and quantify the monosaccharide composition of these polymers by gas chromatography-mass spectrometry (GC-MS).

Use of a human small airway epithelial cell line to study the interactions of with pulmonary epithelial cells.

Unlabelled: During the initiation of invasive aspergillosis, inhaled conidia are deposited on the epithelial cells lining the bronchi, terminal bronchioles, and alveoli. While the interactions of with bronchial and type II alveolar cell lines have been investigated , little is known about the interactions of this fungus with terminal bronchiolar epithelial cells. We compared the interactions of with the A549 type II alveolar epithelial cell line and the HSAEC1-KT human small airway epithelial (HSAE) cell line.

Glycoside hydrolase processing of the Pel polysaccharide alters biofilm biomechanics and Pseudomonas aeruginosa virulence.

Pel exopolysaccharide biosynthetic loci are phylogenetically widespread biofilm matrix determinants in bacteria. In Pseudomonas aeruginosa, Pel is crucial for cell-to-cell interactions and reducing susceptibility to antibiotic and mucolytic treatments. While genes encoding glycoside hydrolases have long been linked to biofilm exopolysaccharide biosynthesis, their physiological role in biofilm development is unclear.

Understanding galactosaminogalactan biosynthesis: A few questions remain.

Half a century after their discovery, polymers of -acetylgalactosamine produced by the Aspergilli have garnered new interest as mediators of fungal virulence. Recent work has focused on the secreted and cell wall-associated heteropolymer, galactosaminogalactan (GAG). This polymer, composed of galactose (Gal) and partially deacetylated -acetylgalactosamine (GalNAc), plays a role in a variety of pathogenic processes including biofilm formation, immune modulation and evasion, and resistance to antifungals.

A B1a-natural IgG-neutrophil axis is impaired in viral- and steroid-associated aspergillosis.

The lung naturally resists () in healthy individuals, but multiple conditions can disrupt this resistance, leading to lethal invasive infections. Core processes of natural resistance and its breakdown are undefined. We investigated three distinct conditions predisposing to lethal aspergillosis-severe SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection, influenza A viral pneumonia, and systemic corticosteroid use-in human patients and murine models.

Prevalence of antimicrobial-resistant organisms in smaller Canadian hospitals: Community, Rural, and Northern Acute Care Point Prevalence (CNAPP-19) Survey, 2019.

Background: The availability of national data on the prevalence of antimicrobial resistant infections in smaller, community, northern and rural acute care hospitals is limited. The objective of this article is to determine the prevalence of infections caused by selected antimicrobial-resistant organisms (AROs) in these smaller hospitals.

Methods: A point prevalence survey was conducted by 55 hospitals between February and May 2019 and included representation from all 10 Canadian provinces.

Short-course antibiotic therapy: The next frontier in antimicrobial stewardship.

Ensuring appropriate use of antibiotics is critical to preserving their effectiveness through limiting the development and spread of antimicrobial resistance. Evidence is accumulating that shorter courses of antibiotics are as effective as traditional longer regimens for many common infections and can reduce the risk of adverse events. Despite the availability of evidence and guidelines supporting short-course antibiotic therapy for these conditions, prolonged use of antibiotics remains common.

Filamentous fungal biofilms: Conserved and unique aspects of extracellular matrix composition, mechanisms of drug resistance and regulatory networks in Aspergillus fumigatus.

The filamentous fungus Aspergillus fumigatus is an ubiquitous mold that can cause invasive pulmonary infections in immunocompromised patients. Within the lung, A. fumigatus forms biofilms that can enhance resistance to antifungals and immune defenses, highlighting the importance of defining the mechanisms underlying biofilm development and associated emergent properties.

The future of fungi: threats and opportunities.

The fungal kingdom represents an extraordinary diversity of organisms with profound impacts across animal, plant, and ecosystem health. Fungi simultaneously support life, by forming beneficial symbioses with plants and producing life-saving medicines, and bring death, by causing devastating diseases in humans, plants, and animals. With climate change, increased antimicrobial resistance, global trade, environmental degradation, and novel viruses altering the impact of fungi on health and disease, developing new approaches is now more crucial than ever to combat the threats posed by fungi and to harness their extraordinary potential for applications in human health, food supply, and environmental remediation.

Preclinical Evaluation of Recombinant Microbial Glycoside Hydrolases as Antibiofilm Agents in Acute Pulmonary Pseudomonas aeruginosa Infection.

The bacterium Pseudomonas aeruginosa can colonize the airways of patients with chronic lung disease. Within the lung, P. aeruginosa forms biofilms that can enhance resistance to antibiotics and immune defenses.

Serum bridging molecules drive candidal invasion of human but not mouse endothelial cells.

During hematogenously disseminated candidiasis, blood borne fungi must invade the endothelial cells that line the blood vessels to infect the deep tissues. Although Candida albicans, which forms hyphae, readily invades endothelial cells, other medically important species of Candida are poorly invasive in standard in vitro assays and have low virulence in immunocompetent mouse models of disseminated infection. Here, we show that Candida glabrata, Candida tropicalis, Candida parapsilosis, and Candida krusei can bind to vitronectin and high molecular weight kininogen present in human serum.

Phosphatidylinositol 3-Kinase (PI3K) Orchestrates Aspergillus fumigatus-Induced Eosinophil Activation Independently of Canonical Toll-Like Receptor (TLR)/C-Type-Lectin Receptor (CLR) Signaling.

Eosinophilia is associated with various persisting inflammatory diseases and often coincides with chronic fungal infections or fungal allergy as in the case of allergic bronchopulmonary aspergillosis (ABPA). Here, we show that intranasal administration of live Aspergillus fumigatus conidia causes fatal lung damage in eosinophilic interleukin-5 (IL-5)-transgenic mice. To further investigate the activation of eosinophils by A.

The Pel polysaccharide is predominantly composed of a dimeric repeat of α-1,4 linked galactosamine and N-acetylgalactosamine.

The genetic capacity to synthesize the biofilm matrix exopolysaccharide Pel is widespread among Gram-negative and Gram-positive bacteria. However, its exact chemical structure has been challenging to determine. Using a Pseudomonas aeruginosa strain engineered to overproduce Pel, improvements to the isolation procedure, and selective hydrolysis with the glycoside hydrolase PelA, we demonstrate that Pel is a partially de-N-acetylated linear polymer of α-1,4-N-acetylgalactosamine comprised predominantly of dimeric repeats of galactosamine and N-acetylgalactosamine.

Co-Operative Biofilm Interactions between and through Secreted Galactosaminogalactan Exopolysaccharide.

The mold and bacterium form biofilms in the airways of individuals with cystic fibrosis. Biofilm formation by depends on the self-produced cationic exopolysaccharide galactosaminogalactan (GAG), while biofilms can contain the cationic exopolysaccharide Pel. GAG and Pel are rendered cationic by deacetylation mediated by either the secreted deacetylase Agd3 () or the periplasmic deacetylase PelA ().

Transfusable neutrophil progenitors as cellular therapy for the prevention of invasive fungal infections.

The use of mature neutrophil (granulocyte) transfusions for the treatment of neutropenic patients with invasive fungal infections (IFIs) has been the focus of multiple clinical trials. Despite these efforts, the transfusion of mature neutrophils has resulted in limited clinical benefit, likely owing to problems of insufficient numbers and the very short lifespan of these donor cells. In this report, we employed a system of conditionally immortalized murine neutrophil progenitors that are capable of continuous expansion, allowing for the generation of unlimited numbers of homogenous granulocyte-macrophage progenitors (GMPs).

Tackling the emerging threat of antifungal resistance to human health.

Invasive fungal infections pose an important threat to public health and are an under-recognized component of antimicrobial resistance, an emerging crisis worldwide. Across a period of profound global environmental change and expanding at-risk populations, human-infecting pathogenic fungi are evolving resistance to all licensed systemic antifungal drugs. In this Review, we highlight the main mechanisms of antifungal resistance and explore the similarities and differences between bacterial and fungal resistance to antimicrobial control.

An Alanine Aminotransferase Is Required for Biofilm-Specific Resistance of Aspergillus fumigatus to Echinocandin Treatment.

Alanine metabolism has been suggested as an adaptation strategy to oxygen limitation in organisms ranging from plants to mammals. Within the pulmonary infection microenvironment, Aspergillus fumigatus forms biofilms with steep oxygen gradients defined by regions of oxygen limitation. An alanine aminotransferase, AlaA, was observed to function in alanine catabolism and is required for several aspects of A.

Preventing Biofilms on Indwelling Catheters by Surface-Bound Enzymes.

Implanted medical devices such as central venous catheters are highly susceptible to microbial colonization and biofilm formation and are a major risk factor for nosocomial infections. The opportunistic pathogen uses exopolysaccharides, such as Psl, for both initial surface attachment and biofilm formation. We have previously shown that chemically immobilizing the Psl-specific glycoside hydrolase, PslG, to a material surface can inhibit biofilm formation.

Spt20, a Structural Subunit of the SAGA Complex, Regulates Aspergillus fumigatus Biofilm Formation, Asexual Development, and Virulence.

The exopolysaccharide galactosaminogalactan (GAG) plays an important role in mediating adhesion, biofilm formation, and virulence in the pathogenic fungus Aspergillus fumigatus. Previous work showed that in A. fumigatus, the Lim domain-binding protein PtaB can form a complex with the sequence-specific transcription factor SomA for regulating GAG biosynthesis, biofilm formation, and asexual development.

Preclinical Evaluation of Recombinant Microbial Glycoside Hydrolases in the Prevention of Experimental Invasive Aspergillosis.

Aspergillus fumigatus is a ubiquitous mold that can cause invasive pulmonary infections in immunocompromised patients. Within the lung, A. fumigatus forms biofilms that can enhance resistance to antifungals and immune defenses.

Model Systems to Study the Chronic, Polymicrobial Infections in Cystic Fibrosis: Current Approaches and Exploring Future Directions.

A recent workshop titled "Developing Models to Study Polymicrobial Infections," sponsored by the Dartmouth Cystic Fibrosis Center (DartCF), explored the development of new models to study the polymicrobial infections associated with the airways of persons with cystic fibrosis (CF). The workshop gathered 35+ investigators over two virtual sessions. Here, we present the findings of this workshop, summarize some of the challenges involved with developing such models, and suggest three frameworks to tackle this complex problem.

The IL-1 Receptor Is Required to Maintain Neutrophil Viability and Function During Airway Infection.

airway infections are associated with increased rates of hospitalizations and declining lung function in patients with chronic lung disease. While the pathogenesis of invasive infections is well studied, little is known about the development and progression of airway infections. Previous studies have demonstrated a critical role for the IL-1 cytokines, IL-1α and IL-1β in enhancing pulmonary neutrophil recruitment during invasive aspergillosis.