Pathogenic strategies of Pseudogymnoascus destructans during torpor and arousal of hibernating bats.

Millions of hibernating bats across North America have died from white-nose syndrome (WNS), an emerging disease caused by a psychrophilic (cold-loving) fungus, Pseudogymnoascus destructans, that invades their skin. Mechanisms of P. destructans invasion of bat epidermis remain obscure. Guided by our in vivo observations, we modeled hibernation with a newly generated little brown bat (Myotis lucifugus) keratinocyte cell line. We uncovered the stealth intracellular lifestyle of P. destructans, which inhibits apoptosis of keratinocytes and spreads through the cells by two epidermal growth factor receptor (EGFR)-dependent mechanisms: active penetration during torpor and induced endocytosis during arousal. Melanin of endocytosed P. destructans blocks endolysosomal maturation, facilitating P. destructans survival and germination after return to torpor. Blockade of EGFR aborts P. destructans entry into keratinocytes.

Sensitization with Fungal Protease Allergen Establishes Long-Lived, Allergenic Th Cell Memory in the Lung.

Allergic asthma is a chronic inflammatory disease that affects millions of individuals worldwide. Exposure to allergens produced by a variety of otherwise harmless microbes, including fungi, predisposes individuals to immunopathologic disease upon subsequent encounters with allergen. We developed a mouse model that employs a purified protease produced by Aspergillus (Asp f 13) to investigate the contributions of CD4+ Th cells to recurrent lung inflammation. Notably, memory CD4+ T cells enhanced the eosinophil response of sensitized/rechallenged animals. In addition, memory CD4+ T cells maintained allergenic features, including expression of GATA-binding protein 3 and IL-5. Th2 memory T cells persisted in the peribronchiolar interstitium of the lung and expressed markers of tissue residence, such as CD69, CCR8, and IL-33R. Lastly, we identified a peptide epitope contained within Asp f 13 and generated a peptide-MHC class II tetramer. Using these tools, we further demonstrated the durability and exquisite sensitivity of memory T cells in promoting lung eosinophilia. Our data highlight important features of memory T cells that strengthen the notion that memory T cells are principal drivers of eosinophilic disease in murine models of allergic sensitization and episodic airway inflammation.

Single Cell Transcriptomes, Lineage, and Differentiation of Functional Airway Microfold Cells.

The airway epithelium is frequently exposed to pathogens and allergens, but the cells that are responsible for sampling these inhaled environmental agents have not been fully defined. Thus, there is a critical void in our understanding of how luminal antigens are delivered to the immune cells that drive the appropriate immune defenses against environmental assaults. In this study, we report the first single cell transcriptomes of airway Microfold (M) cells, whose gut counterparts have long been known for their antigen sampling abilities. Given their very recent discovery in the lower respiratory airways, the mechanisms governing the differentiation and functions of airway M cells are largely unknown. Here, we shed light on the pathways of airway M cell differentiation, establish their lineage, and identify a functional M cell-specific endocytic receptor, the complement receptor 2 (CR2). Lastly, we demonstrate that airway M cells can endocytose Aspergillus fumigatus conidia in a CR2-dependent manner. Collectively, this work lays a foundation for deepening our understanding of lung mucosal immunology and the mechanisms that drive lung immunity and tolerance.

Treatment Guideline Nonadherence Pretransport Associated With Need for Higher Level of Care in Children Transferred to a Pediatric Tertiary Care Center for Status Epilepticus.

OBJECTIVES: We sought to investigate the association between adherence to the American Epilepsy Society (AES) 2016 guidelines for management of convulsive status epilepticus (SE) and clinical outcomes among children requiring interhospital transport for SE. We hypothesized that pretransport guideline nonadherence would be associated with needing higher level of care posttransfer. METHODS: This was a retrospective cohort study of children aged 30 days to 18 years transferred to our pediatric tertiary center from 2017 to 2019 for management of SE. Their care episodes were classified as 2016 American Epilepsy Society guideline adherent or nonadherent. There were 40 referring hospitals represented in this cohort. RESULTS: Of 260 care episodes, 55 (21%) were guideline adherent, 184 (71%) were guideline nonadherent, and 21 (8%) had insufficient data to determine guideline adherence. Compared with the adherent group, patients in the nonadherent care group had longer hospitalizations (32 hours [17-68] vs 21 hours [7-48], P = 0.006), were more likely to require intensive care unit admission (47% vs 31%), and less likely to be discharged home from the emergency department (16% vs 35%; χ 2 test, P = 0.01). Intubation rates did not differ significantly between groups (25% vs 18%, P = 0.37). When we fit a multivariable model to adjust for confounding variables, guideline nonadherence was associated with need for higher level of care (odds ratio, 2.04; 95% confidence interval, 1.04-3.99). Treatment guideline adherence did not improve over the 3-year study period (2017: 22%, 2018: 19%, 2019: 29% [χ 2 test for differences between any 2 years, P = 0.295]). CONCLUSIONS: Guideline nonadherence pretransport was associated with longer hospitalizations and need for higher level of care among children transferred for SE at our institution. These findings suggest a need to improve SE guideline adherence through multifaceted quality improvement efforts targeting both the prehospital and community hospital settings.

Impact of an Emergency Department Saturation Tool on a Pediatric Hospital's Capacity Management Policy.

OBJECTIVE: We sought to describe how the Emergency Department Work Index (EDWIN) saturation tool (1) correlates with PED overcrowding during a capacity management activation policy, known internally as Purple Alert and (2) compare overall hospital-wide capacity metrics on days in which the alert was instituted versus days it was not. METHODS: This study was conducted between January 1, 2017 and December 31, 2019 in a 30-bed academic quaternary care, urban PED within a university hospital. The EDWIN tool was implemented in January 2019 and objectively measured the busyness of the PED. To determine correlation with overcrowding, EDWIN scores were calculated at alert initiation. Mean alert hours per month were plotted on a control chart before and after EDWIN implementation. We also compared daily numbers of PED visits, inpatient admissions, and patients left without being seen (LWBS) for days with and without alert initiation to assess whether or not Purple Alert correlated with high PED usage. RESULTS: During the study period, the alert was activated a total of 146 times; 43 times after EDWIN implementation. Mean EDWIN score was 2.5 (SD 0.5, min 1.5, max 3.8) at alert initiation. There were no alert occurrences for EDWIN scores less than 1.5 (not overcrowded). There was no statistically significant difference for mean alert hours per month before and after EDWIN was instituted (21.4 vs 20.2, P = 0.08). Mean numbers of PED visits, inpatient admissions, and patients left without being seen were higher on days with alert activation ( P < 0.001 for all). CONCLUSIONS: The EDWIN score correlated with PED busyness and overcrowding during alert activation and correlated with high PED usage. Future studies could include implementing a real-time Web-based EDWIN score as a prediction tool to prevent overcrowding and verifying EDWIN generalizability at other PED sites.

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. To address this aim, the Canadian Institute for Advanced Research (CIFAR) and the Burroughs Wellcome Fund convened a workshop to unite leading experts on fungal biology from academia and industry to strategize innovative solutions to global challenges and fungal threats. This report provides recommendations to accelerate fungal research and highlights the major research advances and ideas discussed at the meeting pertaining to 5 major topics: (1) Connections between fungi and climate change and ways to avert climate catastrophe; (2) Fungal threats to humans and ways to mitigate them; (3) Fungal threats to agriculture and food security and approaches to ensure a robust global food supply; (4) Fungal threats to animals and approaches to avoid species collapse and extinction; and (5) Opportunities presented by the fungal kingdom, including novel medicines and enzymes.

Distinctive populations of CD4+T cells associated with vaccine efficacy.

Memory T cells underpin vaccine-induced immunity but are not yet fully understood. To distinguish features of memory cells that confer protective immunity, we used single cell transcriptome analysis to compare antigen-specific CD4+T cells recalled to lungs of mice that received a protective or nonprotective subunit vaccine followed by challenge with a fungal pathogen. We unexpectedly found populations specific to protection that expressed a strong type I interferon response signature, whose distinctive transcriptional signature appeared unconventionally dependent on IFN-γ receptor. We also detected a unique population enriched in protection that highly expressed the gene for the natural killer cell marker NKG7. Lastly, we detected differences in TCR gene use and in Th1- and Th17-skewed responses after protective and nonprotective vaccine, respectively, reflecting heterogeneous Ifng- and Il17a-expressing populations. Our findings highlight key features of transcriptionally diverse and distinctive antigen-specific T cells associated with protective vaccine-induced immunity.

BACH2 in TRegs Limits the Number of Adipose Tissue Regulatory T Cells and Restrains Type 2 Immunity to Fungal Allergens.

FoxP3+ regulatory T cells (Tregs) are essential for self-tolerance and moderating tissue-damaging inflammation. Tregs that develop and mature in the thymus are classified as central Tregs or effector Tregs based on whether Tregs predominately inhabit secondary lymphoid organs (central Tregs) or tissues (effector Tregs). By generating mice that are conditionally deficient for Bach2 in peripheral Tregs, we have examined the role of Bach2 in regulating Treg homeostasis and effector functions. Unlike global and T cell-specific Bach2-deficient mice, Treg-specific Bach2 ablation did not result in unprovoked TH2 inflammation in the lungs. However, Bach2 deficiency in Tregs led to augmented expressions of IRF4, BATF, and GATA3 and a significant increase in the accumulation of ST2 (IL-33R)+ve effector Tregs in the spleen and visceral adipose tissue (VAT) but not in the lungs. Enhanced Bach2-deficient Treg numbers in VAT was not linked to hyperresponsiveness to exogenous IL-33 in vivo. Most strikingly, Treg-specific Bach2 deficiency resulted in enhanced fungal protease-induced Type 2 allergic inflammation in the lungs, with no detectable effects on Type 1 responses to systemic or respiratory viral infections. In summary, we ascribe vital roles for Bach2 in peripheral Tregs: as a transcriptional checkpoint to limit precocious differentiation into effector Tregs in lymphoid tissues and as a regulator of the functional program that restrains Type 2 but not Type 1 inflammation in lungs. Results presented in this manuscript implicate dysregulated Tregs in the pathogenesis of airway hypersensitivities, asthma, and other allergic disorders.

Vaccines to Prevent Coccidioidomycosis: A Gene-Deletion Mutant of Coccidioides Posadasii as a Viable Candidate for Human Trials.

Coccidioidomycosis is an endemic fungal infection that is reported in up to 20,000 persons per year and has an economic impact close to $1.5 billion. Natural infection virtually always confers protection from future exposure, and this suggests that a preventative vaccine strategy is likely to succeed. We here review progress toward that objective. There has been ongoing research to discover a coccidioidal vaccine over the past seven decades, including one phase III clinical trial, but for reasons of either efficacy or feasibility, a safe and effective vaccine has not yet been developed. This review first summarizes the past research to develop a coccidioidal vaccine. It then details the evidence that supports a live, gene-deletion vaccine candidate as suitable for further development as both a veterinary and a human clinical product. Finally, a plausible vaccine development plan is described which would be applicable to this vaccine candidate and also useful to other future candidates. The public health and economic impact of coccidioidomycosis fully justifies a public private partnership for vaccine development, and the development of a vaccine for this orphan disease will likely require some degree of public funding.

SLAMF1 Is Dispensable for Vaccine-Induced T Cell Development but Required for Resistance to Fungal Infection.

Homotypic signaling lymphocyte activation molecule (SLAM) receptor-ligand cell surface interactions between myeloid and lymphoid cells regulate innate and adaptive immune responses. In this article, we report that SLAMF1 is indispensable for host resistance to primary and vaccine-induced protection against fungal infection. Because vaccine immunity is dependent on cell-mediated immunity, we investigated the development of Ag-specific T cells. We studied the T cell-intrinsic and -extrinsic role of SLAMF1. We generated SLAMF1-/- TCR transgenic mice and analyzed the responses of adoptively transferred T cells. We also tracked endogenous Ag-specific T cells by using a tetramer. Intrinsic and extrinsic SLAMF1 signaling was dispensable for the development of antifungal Th1 and Th17 cells, which are requisite for the acquisition of vaccine-induced immunity. Despite intact T cell development, vaccinated SLAMF1-/- mice failed to control fungal infection. Failed accumulation of Ag-specific T cells in the lung on infection of vaccinated mice was due to uncontrolled early infection and inflammation, revealing a role for SLAMF1 in innate host immunity.

Variation in Host Resistance to Blastomyces dermatitidis: Potential Use of Genetic Reference Panels and Advances in Immunophenotyping of Diverse Mouse Strains.

Host genetic determinants that underpin variation in susceptibility to systemic fungal infection are poorly understood. Genes responsible for complex traits can be identified by correlating variation in phenotype with allele in founder strains of wild mice with known genetic variation, assembled in genetic reference panels. In this work, we describe wide natural variation in both primary and acquired resistance to experimental pulmonary blastomycosis in eight founder strains, including 129, A/J, BL/6, CAST, NOD, NZO, PWK, and WSB of the Collaborative Cross collection, and the inbred DBA strain. These differences in susceptibility across strains were accompanied by sharp differences in the accumulation and function of immune cells in the lungs. Immune perturbations were mapped by identifying reagents that phenotypically mark immune cell populations in the distinct strains of mice. In particular, we uncovered marked differences between BL/6 and DBA/2 mouse strains in the development of acquired resistance. Our findings highlight the potential value in using genetic reference panels of mice, and particularly the BXD (recombinant inbred strains of mice from a cross of C57BL/6J and DBA/2J mice) collection harboring a cross between resistant BL/6 and susceptible DBA/2 mice, for unveiling genes linked with host resistance to fungal infection. IMPORTANCE Host genetic variation significantly impacts vulnerability to infectious diseases. While host variation in susceptibility to fungal infection with dimorphic fungi has long been recognized, genes that underpin this variation are poorly understood. We used a collection of seven mouse strains that represent nearly 90% of the genetic variation in mice to identify genetic variability among the strains in resistance to pulmonary infection with the dimorphic fungus Blastomyces dermatitidis. We analyzed differences between the strains in innate resistance by infecting naive mice and in acquired resistance by infecting vaccinated mice. We identified extreme variations in both innate and acquired resistance among the strains. In particular, we found sharp differences between C57BL/6 and DBA/2 strains in the ability to acquire vaccine-induced resistance. We also identified commercial reagents that allowed the phenotyping of immune cells from this strain collection of mice. Because there are additional mice harboring a genetic cross of the C57BL/6 and DBA/2 strains (BXD collection), such mice will permit future investigations to identify the genes that underlie differences in the ability to acquire resistance to infection.

Interhospital Transport of Children With Peripheral Venous Catheters by Private Vehicle: A Mixed Methods Assessment.

BACKGROUND: Many children seeking emergency care at community hospitals require transport to tertiary centers for definitive management. Interhospital transport via ambulance versus patient's own vehicle (POV) are 2 possible modes of transport; however, presence of a peripheral venous catheter (PIV) can determine transport by ambulance. Caregiver satisfaction, patient comfort, and PIV complications related to POV transport have not been described. OBJECTIVE: The aims of the study were to examine caregivers' satisfaction and perceptions of POV transport in children with/without PIVs and to assess PIV-related complications during transport. METHODS: We performed a mixed-methods, prospective cohort study of children who presented with low-acuity conditions to a community hospital and subsequently required transfer to a pediatric tertiary center. Caregivers of patients with/without PIVs were given the choice of transport by POV or ambulance. Surveys completed after transport used dichotomous, 5-point Likert scale, and open-ended responses to assess satisfaction, perceptions, and PIV-related complications. Responses were quantitatively and qualitatively analyzed accordingly. The receiving hospital assessed PIV integrity. RESULTS: Sixty-nine of 78 eligible patients were enrolled; of those, 67 (97%) elected transport by POV and 55 (82%) completed surveys. Most caregivers had positive responses related to satisfaction, comfort, and safety. Results did not differ significantly between those with/without PIVs. The majority (96%) would choose POV transport again. There were no reported PIV complications; all PIVs were functional upon arrival. Qualitative analysis identified themes of comfort, convenience, and efficiency. CONCLUSIONS: In select scenarios, interfacility transport by POV is preferred by families and doing so with a saline-locked PIV does not result in complications.

Human Airway Epithelium Responses to Invasive Fungal Infections: A Critical Partner in Innate Immunity.

The lung epithelial lining serves as the primary barrier to inhaled environmental toxins, allergens, and invading pathogens. Pulmonary fungal infections are devastating and carry high mortality rates, particularly in those with compromised immune systems. While opportunistic fungi infect primarily immunocompromised individuals, endemic fungi cause disease in immune competent and compromised individuals. Unfortunately, in the case of inhaled fungal pathogens, the airway epithelial host response is vastly understudied. Furthering our lack of understanding, very few studies utilize primary human models displaying pseudostratified layers of various epithelial cell types at air-liquid interface. In this review, we focus on the diversity of the human airway epithelium and discuss the advantages and disadvantages of oncological cell lines, immortalized epithelial cells, and primary epithelial cell models. Additionally, the responses by human respiratory epithelial cells to invading fungal pathogens will be explored. Future investigations leveraging current human in vitro model systems will enable identification of the critical pathways that will inform the development of novel vaccines and therapeutics for pulmonary fungal infections.

Combination Adjuvants Enhance Recombinant Protein Vaccine Protection against Fungal Infection.

The development of effective vaccines against fungal infections requires the induction of protective, pathogen-specific cell-mediated immune responses. Here, we asked whether combination adjuvants based on delta inulin (Advax) formulated with Toll-like receptor (TLR) agonists could improve vaccine protection mediated by a fungal recombinant protein, Bl-Eng2 (i.e., Blastomyces endoglucanase 2), which itself harbors an immunodominant antigen and dectin-2 agonist/adjuvant. We found that Bl-Eng2 formulated with Advax3 containing TLR9 agonist or Advax8 containing TLR4 agonist provided the best protection against pulmonary infection with Blastomyces dermatitidis, being more effective than complete Freund's adjuvant or Adjuplex. Advax3 was most efficient in inducing gamma interferon (IFN-γ)- and interleukin-17 (IL-17)-producing antigen-specific T cells that migrated to the lung upon Blastomyces dermatitidis infection. Mechanistic studies revealed Bl-Eng2/Advax3 protection was tempered by neutralization of IL-17 and particularly IFN-γ. Likewise, greater numbers of lung-resident T cells producing IFN-γ, IL-17, or both IFN-γ and IL-17 correlated with fewer fungi recovered from lung. Protection was maintained after depletion of CD4+ T cells, partially reduced by depletion of CD8+ T cells, and completely eliminated after depletion of both CD4+ and CD8+ T cells. We conclude that Bl-Eng2 formulated with Advax3 is promising for eliciting vaccine-induced antifungal immunity, through a previously uncharacterized mechanism involving CD8+ and also CD4+ T cells producing IFN-γ and/or IL-17. Although no licensed vaccine exists as yet against any fungal disease, these findings indicate the importance of adjuvant selection for the development of effective fungal vaccines. IMPORTANCE Fungal disease remains a challenging clinical and public health problem. Despite medical advances, invasive fungal infections have skyrocketed over the last decade and pose a mounting health threat in immunocompetent and -deficient hosts, with worldwide mortality rates ranking 7th, even ahead of tuberculosis. The development of safe, effective vaccines remains a major hurdle for fungi. Critical barriers to progress include the lack of defined fungal antigens and suitable adjuvants. Our research is significant in identifying adjuvant combinations that elicit optimal vaccine-induced protection when formulated with a recombinant protective antigen and uncovering the mechanistic bases of the underlaying vaccine protection, which will foster the strategic development of antifungal vaccines.

LYSMD3: A mammalian pattern recognition receptor for chitin.

Chitin, a major component of fungal cell walls, has been associated with allergic disorders such as asthma. However, it is unclear how mammals recognize chitin and the principal receptor(s) on epithelial cells that sense chitin remain to be determined. In this study, we show that LYSMD3 is expressed on the surface of human airway epithelial cells and demonstrate that LYSMD3 is able to bind chitin, as well as ß-glucan, on the cell walls of fungi. Knockdown or knockout of LYSMD3 also sharply blunts the production of inflammatory cytokines by epithelial cells in response to chitin and fungal spores. Competitive inhibition of the LYSMD3 ectodomain by soluble LYSMD3 protein, multiple ligands, or antibody against LYSMD3 also blocks chitin signaling. Our study reveals LYSMD3 as a mammalian pattern recognition receptor (PRR) for chitin and establishes its role in epithelial cell inflammatory responses to chitin and fungi.

The Known Unknowns of the Immune Response to Coccidioides.

Coccidioidomycosis, otherwise known as Valley Fever, is caused by the dimorphic fungi Coccidioides immitis and C. posadasii. While most clinical cases present with self-limiting pulmonary infection, dissemination of Coccidioides spp. results in prolonged treatment and portends higher mortality rates. While the structure, genome, and niches for Coccidioides have provided some insight into the pathogenesis of disease, the underlying immunological mechanisms of clearance or inability to contain the infection in the lung are poorly understood. This review focuses on the known innate and adaptive immune responses to Coccidioides and highlights three important areas of uncertainty and potential approaches to address them. Closing these gaps in knowledge may enable new preventative and therapeutic strategies to be pursued.

Characterization of antifungal C-type lectin receptor expression on murine epithelial and endothelial cells in mucosal tissues.

Our data reveal that selection of enzymes for generating single cell suspensions from murine tissues influences detection of surface expression of antifungal CLRs. Using a method that most preserves receptor expression, we show that non-myeloid expression of antifungal CLRs is limited to MelLec on endothelial cells in murine mucosal tissues.

An Analysis of Computed Tomography-Related Radiation Exposure in Pediatric Trauma Patients.

OBJECTIVE: To compare radiation doses used for pediatric computed tomography (CT) scans at community-based referring facilities (RF) to those at a designated pediatric trauma center (PTC) to assess the consistency of radiation exposure. METHODS: In this retrospective study, patients 0 to 18 years of age with CT imaging performed either at a RF or at a PTC from January 1, 2015, to January 5, 2016, were identified. Data about patients, CT radiation dose, and characteristics of the RFs were compared. RESULTS: We identified 502 patients (156 RF, 346 PTC) with 281 head CTs (79 RF, 202 PTC) and 86 abdominal/pelvis CTs (28 RF, 58 PTC). The radiation dose (measured in mean dose-length product [DLP] ± 1 standard deviation) was significantly higher for RF scans compared with PTC scans (head, RF DLP = 545 ± 334 vs PTC DLP = 438 ± 186 (P < 0.001); abdomen/pelvis, RF DLP = 279 ± 160 vs PTC DLP = 181 ± 201 [P = 0.027]). There was a nonsignificant trend toward lower head CT radiation dosages at RFs with a dedicated pediatric emergency department compared with RFs without a pediatric emergency department. CONCLUSIONS: Our data suggest that CT scans performed at RFs expose pediatric patients to significantly higher doses of radiation when compared with a PTC. These data support further study to identify factors associated with increased radiation and educational outreach to RFs.