Corrigendum: Persisting Cryptococcus yeast species Vishniacozyma victoriae and Cryptococcus neoformans elicit unique airway inflammation in mice following repeated exposure

[This corrects the article DOI: 10.3389/fcimb.2023.1067475.].

Decrypting seasonal patterns of key pollen taxa in cool temperate Australia: A multi-barcode metabarcoding analysis

Pollen allergies pose a considerable global public health concern. Allergy risk can vary significantly within plant families, yet some key pollen allergens can only be identified to family level by current optical methods. Pollen information with greater taxonomic resolution is therefore required to best support allergy prevention and self-management. We used environmental DNA (eDNA) metabarcoding to deepen taxonomic insights into the seasonal composition of airborne pollen in cool temperate Australia, a region with high rates of allergic respiratory disease. In Hobart, Tasmania, we collected routine weekly air samples from December 2018 until October 2020 and sequenced the internal transcribed spacer 2 (ITS2) and chloroplastic tRNA-Leucine tRNA-Phenylalanine intergenic spacer (trnL-trnF) regions in order to address the following questions: a) What is the genus-level diversity of known and potential aeroallergens in Hobart, in particular, in the families Poaceae, Cupressaceae and Myrtaceae? b) How do the atmospheric concentrations of these taxa change over time, and c) Does trnL-trnF enhance resolution of biodiversity when used in addition to ITS2? Our results suggest that individuals in the region are exposed to temperate grasses including Poa and Bromus in the peak grass pollen season, however low levels of exposure to the subtropical grass Cynodon may occur in autumn and winter. Within Cupressaceae, both metabarcodes showed that exposure is predominantly to pollen from the introduced genera Cupressus and Juniperus. Only ITS2 detected the native genus, Callitris. Both metabarcodes detected Eucalyptus as the major Myrtaceae genus, with trnL-trnF exhibiting primer bias for this family. These findings help refine our understanding of allergy triggers in Tasmania and highlight the utility of multiple metabarcodes in aerobiome studies.

Fungal diversity in homes and asthma morbidity among school-age children in New York City

BACKGROUND

Asthma development has been inversely associated with exposure to fungal diversity. However, the influence of fungi on measures of asthma morbidity is not well understood.

OBJECTIVES

This study aimed to test the hypothesis that fungal diversity is inversely associated with neighborhood asthma prevalence and identify specific fungal species associated with asthma morbidity.

METHODS

Children aged 7-8 years (n = 347) living in higher (11-18%) and lower (3-9%) asthma prevalence neighborhoods were recruited within an asthma case-control study. Fungal communities were analyzed from floor dust using high-throughput DNA sequencing. A subset of asthmatic children (n = 140) was followed to age 10-11 to determine asthma persistence.

RESULTS

Neighborhood asthma prevalence was inversely associated with fungal species richness (P = 0.010) and Shannon diversity (P = 0.059). Associations between neighborhood asthma prevalence and diversity indices were driven by differences in building type and presence of bedroom carpet. Among children with asthma at age 7-8 years, Shannon fungal diversity was inversely associated with frequent asthma symptoms at that age (OR 0.57, P = 0.025) and with asthma persistence to age 10-11 (OR 0.48, P = 0.043). Analyses of individual fungal species did not show significant associations with asthma outcomes when adjusted for false discovery rates.

DISCUSSION

Lower fungal diversity was associated with asthma symptoms in this urban setting. Individual fungal species associated with asthma morbidity were not detected. Further research is warranted into building type, carpeting, and other environmental characteristics which influence fungal exposures in homes.

Persisting Cryptococcus yeast species Vishniacozyma victoriae and Cryptococcus neoformans elicit unique airway inflammation in mice following repeated exposure

Background

Allergic airway disease (AAD) is a growing concern in industrialized nations and can be influenced by fungal exposures. Basidiomycota yeast species such as Cryptococcus neoformans are known to exacerbate allergic airway disease; however, recent indoor assessments have identified other Basidiomycota yeasts, including Vishniacozyma victoriae (syn. Cryptococcus victoriae), to be prevalent and potentially associated with asthma. Until now, the murine pulmonary immune response to repeated V. victoriae exposure was previously unexplored.

Objective

This study aimed to compare the immunological impact of repeated pulmonary exposure to Cryptococcus yeasts.

Methods

Mice were repeatedly exposed to an immunogenic dose of C. neoformans or V. victoriae via oropharyngeal aspiration. Bronchoalveolar lavage fluid (BALF) and lungs were collected to examine airway remodeling, inflammation, mucous production, cellular influx, and cytokine responses at 1 day and 21 days post final exposure. The responses to C. neoformans and V. victoriae were analyzed and compared.

Results

Following repeated exposure, both C. neoformans and V. victoriae cells were still detectable in the lungs 21 days post final exposure. Repeated C. neoformans exposure initiated myeloid and lymphoid cellular infiltration into the lung that worsened over time, as well as an IL-4 and IL-5 response compared to PBS-exposed controls. In contrast, repeated V. victoriae exposure induced a strong CD4+ T cell-driven lymphoid response that started to resolve by 21 days post final exposure.

Discussion

C. neoformans remained in the lungs and exacerbated the pulmonary immune responses as expected following repeated exposure. The persistence of V. victoriae in the lung and strong lymphoid response following repeated exposure were unexpected given its lack of reported involvement in AAD. Given the abundance in indoor environments and industrial utilization of V. victoriae, these results highlight the importance to investigate the impact of frequently detected fungal organisms on the pulmonary response following inhalational exposure. Moreover, it is important to continue to address the knowledge gap involving Basidiomycota yeasts and their impact on AAD.

Spring is associated with increased total and allergenic fungal concentrations in house dust from a pediatric asthma cohort in New York City

Introduction

Asthma and allergy symptoms vary seasonally due to exposure to environmental sources of allergen, including fungi. However, we need an improved understanding of seasonal influence on fungal exposures in the indoor environment. We hypothesized that concentrations of total fungi and allergenic species in vacuumed dust vary significantly by season.

Objective

Assess seasonal variation of indoor fungi with greater implications related to seasonal asthma control.

Methods

We combined next-generation sequencing with quantitative polymerase chain reaction (qPCR) to measure concentrations of fungal DNA in indoor floor dust samples (n = 298) collected from homes participating in the New York City Neighborhood Asthma and Allergy Study (NAAS).

Results

Total fungal concentration in spring was significantly higher than the other three seasons (p ≤ 0.005). Mean concentrations for 78% of fungal species were elevated in the spring (26% were significantly highest in spring, p < 0.05). Concentrations of 8 allergenic fungal species were significantly (p < 0.5) higher in spring compared to at least two other seasons. Indoor relative humidity and temperature were significantly highest in spring (p < 0.05) and were associated with total fungal concentration (R2 = 0.049, R2 = 0.11, respectively).

Conclusion

There is significant seasonal variation in total fungal concentration and concentration of select allergenic species. Indoor relative humidity and temperature may underlie these associations.

Mycobiota and the Contribution of Yeasts in Floor Dust of 50 Elementary Schools Characterized with Sequencing Internal Transcribed Spacer Region of Ribosomal DNA

The assemblage of fungi including unicellular yeasts in schools is understudied. We conducted an environmental study to characterize fungal communities in classroom floor dust. We collected 500 samples from 50 elementary schools in Philadelphia, PA, and evaluated room dampness/mold conditions. Genomic DNA from dust was extracted for internal transcribed spacer 1 Illumina MiSeq sequencing to identify operational taxonomic units (OTUs) organized from DNA sequences. Differential abundance analyses were performed to examine significant differences in abundance among groups. We identified 724 genera from 1490 OTUs. The genus Epicoccum was not diverse but the most abundant (relative abundance = 18.9%). Fungi were less diverse but most dissimilar in composition in the most water-damaged classrooms compared to the least water-damaged, indicating differential effects of individual classroom water-damage on fungal compositions. We identified 62 yeast genera, representing 19.6% of DNA sequences. Cyberlindnera was the most abundant (6.1%), followed by Cryptococcus, Aureobasidium, Rhodotorula, and Candida. The average relative abundance of yeasts tended to increase with increasing dampness and mold score and was significantly (p-value = 0.048) higher in the most water-damaged classrooms (22.4%) than the least water-damaged classrooms (18.2%). Our study suggests the need for further research on the potential health effects associated with exposures to yeasts in schools.

Vishniacozyma victoriae (syn. Cryptococcus victoriae) in the homes of asthmatic and non-asthmatic children in New York City

BACKGROUND

Indoor environments contain a broad diversity of non-pathogenic Basidiomycota yeasts, but their role in exacerbating adverse health effects has remained unclear.

OBJECTIVE

To understand the role of Vishniacozyma victoriae exposure and its impact on human health.

METHODS

A qPCR assay was developed to detect and quantify an abundant indoor yeast species, Vishniacozyma victoriae (syn. Cryptococcus victoriae), from homes participating in the New York City Neighborhood Asthma and Allergy Study (NAAS). We evaluated the associations between V. victoriae, housing characteristics, and asthma relevant health endpoints.

RESULTS

V. victoriae was quantified in 236 of the 256 bedroom floor dust samples ranging from less than 300-45,918 cell equivalents/mg of dust. Higher concentrations of V. victoriae were significantly associated with carpeted bedroom floors (P = 0.044), mean specific humidity (P = 0.004), winter (P < 0.0001) and spring (P = 0.001) seasons, and the presence of dog (P = 0.010) and dog allergen Can f 1 (P = 0.027). V. victoriae concentrations were lower in homes of children with asthma vs. without asthma (P = 0.027), an association observed only among the non-seroatopic children.

Gaseous and Particulate Content of Laser Tattoo Removal Plume

BACKGROUND

There is increasing awareness of the potential hazards of surgical plumes. The plume associated with laser tattoo removal remains uncharacterized.

OBJECTIVE

To determine the gaseous, particulate, and microbiological content of the laser tattoo removal plume.

MATERIALS AND METHODS

Air sampling was performed during laser tattoo removal from pig skin and from patients. Measurement of metals, volatile organic compounds (VOCs), carbon monoxide (CO), hydrogen sulfide (HS), and ultrafine particulates (UPs) as well as bacterial 16S ribosomal DNA sequencing were performed.

RESULTS

Metals were identified in the plume from both pig and human skin. Volatile organic compounds were found at similar levels within and outside the treatment room. Several bacterial phyla were detected in the treatment room, but not outside. High levels of UPs were measured throughout the treatment room during tattoo removal from pig skin. Ultrafine particulates were detected at low levels in the room periphery during tattoo removal from human skin, but at higher levels in the immediate treatment zone. HS and CO were not detected.

CONCLUSION

Metals, VOCs, HS, and CO were found at levels below applicable occupational exposure limits. The presence of bacteria is of uncertain significance, but may be hazardous. High levels of UPs require further investigation.

Occupational Histoplasmosis: Epidemiology and Prevention Measures

In areas where Histoplasma is endemic in the environment, occupations involving activities exposing workers to soil that contains bird or bat droppings may pose a risk for histoplasmosis. Occupational exposures are frequently implicated in histoplasmosis outbreaks. In this paper, we review the literature on occupationally acquired histoplasmosis. We describe the epidemiology, occupational risk factors, and prevention measures according to the hierarchy of controls.

Aspergillus versicolor Inhalation Triggers Neuroimmune, Glial, and Neuropeptide Transcriptional Changes

Increasing evidence associates indoor fungal exposure with deleterious central nervous system (CNS) health, such as cognitive and emotional deficits in children and adults, but the specific mechanisms by which it might impact the brain are poorly understood. Mice were exposed to filtered air, heat-inactivated Aspergillus versicolor (3 × 10⁵ spores), or viable A. versicolor (3 × 10⁵ spores) via nose-only inhalation exposure 2 times per week for 1, 2, or 4 weeks. Analysis of cortex, midbrain, olfactory bulb, and cerebellum tissue from mice exposed to viable A. versicolor spores for 1, 2, and 4 weeks revealed significantly elevated pro-inflammatory (Tnf and Il1b) and glial activity (Gdnf and Cxc3r1) gene expression in several brain regions when compared to filtered air control, with the most consistent and pronounced neuroimmune response 48H following the 4-week exposure in the midbrain and frontal lobe. Bulk RNA-seq analysis of the midbrain tissue confirmed that 4 weeks of A. versicolor exposure resulted in significant transcriptional enrichment of several biological pathways compared to the filtered air control, including neuroinflammation, glial cell activation, and regulation of postsynaptic organization. Upregulation of Drd1, Penk, and Pdyn mRNA expression was confirmed in the 4-week A. versicolor exposed midbrain tissue, highlighting that gene expression important for neurotransmission was affected by repeated A. versicolor inhalation exposure. Taken together, these findings indicate that the brain can detect and respond to A. versicolor inhalation exposure with changes in neuroimmune and neurotransmission gene expression, providing much needed insight into how inhaled fungal exposures can affect CNS responses and regulate neuroimmune homeostasis.

Occupational Allergies to Cannabis

Within the last decade there has been a significant expansion in access to cannabis for medicinal and adult nonmedical use in the United States and abroad. This has resulted in a rapidly growing and diverse workforce that is involved with the growth, cultivation, handling, and dispensing of the cannabis plant and its products. The objective of this review was to educate physicians on the complexities associated with the health effects of cannabis exposure, the nature of these exposures, and the future practical challenges of managing these in the context of allergic disease. We will detail the biological hazards related to typical modern cannabis industry operations that may potentially drive allergic sensitization in workers. We will highlight the limitations that have hindered the development of objective diagnostic measures that are essential in separating "true" cannabis allergies from nonspecific reactions/irritations that "mimic" allergy-like symptoms. Finally, we will discuss recent advances in the basic and translational scientific research that will aid the development of diagnostic tools and therapeutic standards to serve optimal management of cannabis allergies across the occupational spectrum.

Correction to: Bacterial community assemblages in classroom floor dust of 50 public schools in a large city: characterization using 16S rRNA sequences and associations with environmental factors

An amendment to this paper has been published and can be accessed via the original article.

Bacterial community assemblages in classroom floor dust of 50 public schools in a large city: characterization using 16S rRNA sequences and associations with environmental factors

Characterizing indoor microbial communities using molecular methods provides insight into bacterial assemblages present in environments that can influence occupants' health. We conducted an environmental assessment as part of an epidemiologic study of 50 elementary schools in a large city in the northeastern USA. We vacuumed dust from the edges of the floor in 500 classrooms accounting for 499 processed dust aliquots for 16S Illumina MiSeq sequencing to characterize bacterial assemblages. DNA sequences were organized into operational taxonomic units (OTUs) and identified using a database derived from the National Center for Biotechnology Information. Bacterial diversity and ecological analyses were performed at the genus level. We identified 29 phyla, 57 classes, 148 orders, 320 families, 1193 genera, and 2045 species in 3073 OTUs. The number of genera per school ranged from 470 to 705. The phylum Proteobacteria was richest of all while Firmicutes was most abundant. The most abundant order included Lactobacillales, Spirulinales, and Clostridiales. Halospirulina was the most abundant genus, which has never been reported from any school studies before. Gram-negative bacteria were more abundant and richer (relative abundance = 0.53; 1632 OTUs) than gram-positive bacteria (0.47; 1441). Outdoor environment-associated genera were identified in greater abundance in the classrooms, in contrast to homes where human-associated bacteria are typically more abundant. Effects of school location, degree of water damage, building condition, number of students, air temperature and humidity, floor material, and classroom's floor level on the bacterial richness or community composition were statistically significant but subtle, indicating relative stability of classroom microbiome from environmental stress. Our study indicates that classroom floor dust had a characteristic bacterial community that is different from typical house dust represented by more gram-positive and human-associated bacteria. Health implications of exposure to the microbiomes in classroom floor dust may be different from those in homes for school staff and students. Video abstract.

Review of NIOSH Cannabis-Related Health Hazard Evaluations and Research

Since 2004, the National Institute for Occupational Safety and Health (NIOSH) has received 10 cannabis-related health hazard evaluation (HHE) investigation requests from law enforcement agencies (n = 5), state-approved cannabis grow operations (n = 4), and a coroner's office (n = 1). Earlier requests concerned potential illicit drug exposures (including cannabis) during law enforcement activities and criminal investigations. Most recently HHE requests have involved state-approved grow operations with potential occupational exposures during commercial cannabis production for medicinal and non-medical (recreational) use. As of 2019, the United States Drug Enforcement Administration has banned cannabis as a Schedule I substance on the federal level. However, cannabis legalization at the state level has become more common in the USA. In two completed cannabis grow operation HHE investigations (two investigations are still ongoing as of 2019), potential dermal exposures were evaluated using two distinct surface wipe sample analytical methods. The first analyzed for delta-9-tetrahydrocannabinol (Δ9-THC) using a liquid chromatography and tandem mass spectrometry (LC-MS-MS) method with a limit of detection (LOD) of 4 nanograms (ng) per sample. A second method utilized high performance liquid chromatography with diode-array detection to analyze for four phytocannabinoids (Δ9-THC, Δ9-THC acid, cannabidiol, and cannabinol) with a LOD (2000 ng per sample) which, when comparing Δ9-THC limits, was orders of magnitude higher than the LC-MS-MS method. Surface wipe sampling results for both methods illustrated widespread contamination of all phytocannabinoids throughout the tested occupational environments, highlighting the need to consider THC form (Δ9-THC or Δ9-THC acid) as well as other biologically active phytocannabinoids in exposure assessments. In addition to potential cannabis-related dermal exposures, ergonomic stressors, and psychosocial issues, the studies found employees in cultivation, harvesting, and processing facilities could potentially be exposed to allergens and respiratory hazards through inhalation of organic dusts (including fungus, bacteria, and endotoxin) and volatile organic compounds (VOCs) such as diacetyl and 2,3-pentanedione. These hazards were most evident during the decarboxylation and grinding of dried cannabis material, where elevated job-specific concentrations of VOCs and endotoxin were generated. Additionally, utilization of contemporary gene sequencing methods in NIOSH HHEs provided a more comprehensive characterization of microbial communities sourced during cannabis cultivation and processing. Internal Transcribed Spacer region sequencing revealed over 200 fungal operational taxonomic units and breathing zone air samples were predominantly composed of Botrytis cinerea, a cannabis plant pathogen. B. cinerea, commonly known as gray mold within the industry, has been previously associated with hypersensitivity pneumonitis. This work elucidates new occupational hazards related to cannabis production and the evolving occupational safety and health landscape of an emerging industry, provides a summary of cannabis-related HHEs, and discusses critical lessons learned from these previous HHEs.

Inhalation of Stachybotrys chartarum Fragments Induces Pulmonary Arterial Remodeling

Stachybotrys chartarum is a fungal contaminant within the built environment and a respiratory health concern in the United States. The objective of this study was to characterize the mechanisms influencing pulmonary immune responses to repeatedly inhaled S. chartarum. Groups of B6C3F1/N mice repeatedly inhaled viable trichothecene-producing S. chartarum conidia (strain A or strain B), heat-inactivated conidia, or high-efficiency particulate absolute-filtered air twice per week for 4 and 13 weeks. Strain A was found to produce higher amounts of respirable fragments than strain B. Lung tissue, serum, and BAL fluid were collected at 24 and 48 hours after final exposure and processed for histology, flow cytometry, and RNA and proteomic analyses. At 4 weeks after exposure, a T-helper cell type 2-mediated response was observed. After 13 weeks, a mixed T-cell response was observed after exposure to strain A compared with a T-helper cell type 2-mediated response after strain B exposure. After exposure, both strains induced pulmonary arterial remodeling at 13 weeks; however, strain A-exposed mice progressed more quickly than strain B-exposed mice. BAL fluid was composed primarily of eosinophils, neutrophils, and macrophages. Both the immune response and the observed pulmonary arterial remodeling were supported by specific cellular, molecular, and proteomic profiles. The immunopathological responses occurred earlier in mice exposed to high fragment-producing strain A. The rather striking induction of pulmonary remodeling by S. chartarum appears to be related to the presence of fungal fragments during exposure.

Resolution of Pulmonary Inflammation Induced by Carbon Nanotubes and Fullerenes in Mice: Role of Macrophage Polarization

Pulmonary exposure to certain engineered nanomaterials (ENMs) causes chronic lesions like fibrosis and cancer in animal models as a result of unresolved inflammation. Resolution of inflammation involves the time-dependent biosynthesis of lipid mediators (LMs)-in particular, specialized pro-resolving mediators (SPMs). To understand how ENM-induced pulmonary inflammation is resolved, we analyzed the inflammatory and pro-resolving responses to fibrogenic multi-walled carbon nanotubes (MWCNTs, Mitsui-7) and low-toxicity fullerenes (fullerene C60, C60F). Pharyngeal aspiration of MWCNTs at 40 μg/mouse or C60F at a dose above 640 μg/mouse elicited pulmonary effects in B6C3F1 mice. Both ENMs stimulated acute inflammation, predominated by neutrophils, in the lung at day 1, which transitioned to histiocytic inflammation by day 7. By day 28, the lesion in MWCNT-exposed mice progressed to fibrotic granulomas, whereas it remained as alveolar histiocytosis in C60F-exposed mice. Flow cytometric profiling of whole lung lavage (WLL) cells revealed that neutrophil recruitment was the greatest at day 1 and declined to 36.6% of that level in MWCNT- and 16.8% in C60F-treated mice by day 7, and to basal levels by day 28, suggesting a rapid initiation phase and an extended resolution phase. Both ENMs induced high levels of proinflammatory leukotriene B4 (LTB4) and prostaglandin E2 (PGE2) with peaks at day 1, and high levels of SPMs resolvin D1 (RvD1) and E1 (RvE1) with peaks at day 7. MWCNTs and C60F induced time-dependent polarization of M1 macrophages with a peak at day 1 and subsequently of M2 macrophages with a peak at day 7 in the lung, accompanied by elevated levels of type 1 or type 2 cytokines, respectively. M1 macrophages exhibited preferential induction of arachidonate 5-lipoxygenase activating protein (ALOX5AP), whereas M2 macrophages had a high level expression of arachidonate 15-lipoxygenase (ALOX15). Polarization of macrophages in vitro differentially induced ALOX5AP in M1 macrophages or ALOX15 in M2 macrophages resulting in increased preferential biosynthesis of proinflammatory LMs or SPMs. MWCNTs increased the M1- or M2-specific production of LMs accordingly. These findings support a mechanism by which persistent ENM-induced neutrophilic inflammation is actively resolved through time-dependent polarization of macrophages and enhanced biosynthesis of specialized LMs via distinct ALOX pathways.

Morphology and quantification of fungal growth in residential dust and carpets

Mold growth indoors is associated with negative human health effects, and this growth is limited by moisture availability. Dust deposited in carpet is an important source of human exposure due to potential elevated resuspension compared to hard floors. However, we need an improved understanding of fungal growth in dust and carpet to better estimate human exposure. The goal of this study was to compare fungal growth quantity and morphology in residential carpet under different environmental conditions, including equilibrium relative humidity (ERH) (50%, 85%, 90%, 95%, 100%), carpet fiber material (nylon, olefin, wool) and presence/absence of dust. We analyzed incubated carpet and dust samples from three Ohio homes for total fungal DNA, fungal allergen Alt a 1, and fungal morphology. Dust presence and elevated ERH (≥85%) were the most important variables that increased fungal growth. Elevated ERH increased mean fungal DNA concentration (P < 0.0001), for instance by approximately 1000 times at 100% compared to 50% ERH after two weeks. Microscopy also revealed more fungal growth at higher ERH. Fungal concentrations were up to 100 times higher in samples containing house dust compared to no dust. For fiber type, olefin had the least total fungal growth, and nylon had the most total fungi and A. alternata growth in unaltered dust. Increased ERH conditions were associated with increased Alt a 1 allergen concentration. The results of this study demonstrate that ERH, presence/absence of house dust, and carpet fiber type influence fungal growth and allergen production in residential carpet, which has implications for human exposure.

Subchronic inhalation of Aspergillus versicolor conidia leads to sustained innate immune responses and is associated with irreversible remodeling of pulmonary arterial tissue following recovery

Aspergillus versicolor is an environmentally ubiquitous fungal species that is particularly abundant in environments with water infiltration. Respiration of fungal products, including conidia, hyphal fragments, mycotoxins, and other secondary metabolites may cause adverse pulmonary health effects including asthma and allergy. In the present study, pulmonary immune responses in B6C3F1 mice were examined following 1, 2, 4, 8, and 13 weeks of repeated respiratory challenge to 3×105A. versicolor conidia. Increased alveolar macrophages, inflammatory monocytes, neutrophils, and eosinophils, which peaked between 4 and 8 weeks, were detected in the lungs of mice exposed to viable conidia. Type 2 innate lymphoid cells (ILC2s) peaked between 8 and 13 weeks compared to total T cells which increased between 2 and 8 weeks and decreased at 13 weeks. Protein concentrations of the Th2 cytokines IL4, IL5, and IL13 were highest in bronchoaveolar lavage fluid of exposed mice following 4 weeks and exhibited a time-dependent reduction at 8 and 13 weeks. Inhalation of conidia for 13 weeks led to goblet cell hyperplasia, vascular wall thickening, and perivascular inflammation. Finally, mixed perivascular inflammation and smooth muscle hypertrophy were sustained at 4 weeks post-exposure. These data indicate that exposure to A. versicolor elicits a Th2-biased immune response that is driven by innate cell populations and is associated with the induction of remodeling of the pulmonary vasculature.

Inactivation of the multi-drug resistant pathogen Candida auris using ultraviolet germicidal irradiation (UVGI)

BACKGROUND

Candida auris, often a multi-drug resistant fungal pathogen, has become an emerging threat in healthcare settings around the world. Reliable disinfection protocols specifically designed to inactivate C. auris are essential, as many chemical disinfectants commonly used in healthcare settings have been shown to have variable efficacy at inactivating C. auris.

AIM

Ultraviolet germicidal irradiation (UVGI) was investigated as a method to inactivate clinically relevant strains of C. auris.

METHODS

Ten C. auris and two C. albicans isolates were exposed to ultraviolet (UV) energy to determine the UV dose required to inactivate each isolate. Using a UV reactor, each isolate (106 cells/mL) was exposed to 11 UV doses ranging from 10-150 mJ/cm2 and then cultured to assess cell viability.

FINDINGS

An exponential decay model was applied to each dose-response curve to determine inactivation rate constants for each isolate, which ranged from 0.108-0.176 cm2/mJ for C. auris and 0.239-0.292 cm2/mJ for C. albicans. As the model of exponential decay did not accurately estimate the dose beyond 99.9% inactivation, a logistic regression model was applied to better estimate the doses required for 99.999% inactivation. Using this model, significantly greater UV energy was required to inactivate C. auris (103 to 192 mJ/cm2) when compared to C. albicans (78 to 80 mJ/cm2).

CONCLUSION

This study demonstrated UVGI as a feasible approach for inactivating C. auris, although variable susceptibility among isolates must be taken into account. This dose-response data is critical for recommending UVGI dosing strategies to be tested in healthcare settings.

Cultivation and aerosolization of Stachybotrys chartarum for modeling pulmonary inhalation exposure

Objective: Stachybotrys chartarum is a hydrophilic fungal species commonly found as a contaminant in water-damaged building materials. Although several studies have suggested that S. chartarum exposure elicits a variety of adverse health effects, the ability to characterize the pulmonary immune responses to exposure is limited by delivery methods that do not replicate environmental exposure. This study aimed to develop a method of S. chartarum aerosolization to better model inhalation exposures. Materials and methods: An acoustical generator system (AGS) was previously developed and utilized to aerosolize and deliver fungal spores to mice housed in a multi-animal nose-only exposure chamber. In this study, methods for cultivating, heat-inactivating, and aerosolizing two macrocyclic trichothecene-producing strains of S. chartartum using the AGS are described. Results and discussion: In addition to conidia, acoustical generation of one strain of S. chartarum resulted in the aerosolization of fungal fragments (<2 µm aerodynamic diameter) derived from conidia, phialides, and hyphae that initially comprised 50% of the total fungal particle count but was reduced to less than 10% over the duration of aerosolization. Acoustical generation of heat-inactivated S. chartarum did not result in a similar level of fragmentation. Delivery of dry, unextracted S. chartarum using these aerosolization methods resulted in pulmonary inflammation and immune cell infiltration in mice inhaling viable, but not heat-inactivated S. chartarum. Conclusions: These methods of S. chartarum growth and aerosolization allow for the delivery of fungal bioaerosols to rodents that may better simulate natural exposure within water-damaged indoor environments.

Ten questions concerning the implications of carpet on indoor chemistry and microbiology

Carpet and rugs currently represent about half of the United States flooring market and offer many benefits as a flooring type. How carpets influence our exposure to both microorganisms and chemicals in indoor environments has important health implications but is not well understood. The goal of this manuscript is to consolidate what is known about how carpet impacts indoor chemistry and microbiology, as well as to identify the important research gaps that remain. After describing the current use of carpet indoors, questions focus on five specific areas: 1) indoor chemistry, 2) indoor microbiology, 3) resuspension and exposure, 4) current practices and future needs, and 5) sustainability. Overall, it is clear that carpet can influence our exposures to particles and volatile compounds in the indoor environment by acting as a direct source, as a reservoir of environmental contaminants, and as a surface supporting chemical and biological transformations. However, the health implications of these processes are not well known, nor how cleaning practices could be optimized to minimize potential negative impacts. Current standards and recommendations focus largely on carpets as a primary source of chemicals and on limiting moisture that would support microbial growth. Future research should consider enhancing knowledge related to the impact of carpet in the indoor environment and how we might improve the design and maintenance of this common material to reduce our exposure to harmful contaminants while retaining the benefits to consumers.

Potential occupational and respiratory hazards in a Minnesota cannabis cultivation and processing facility

BACKGROUND

Cannabis has been legalized in some form for much of the United States. The National Institute for Occupational Safety and Health (NIOSH) received a health hazard evaluation request from a Minnesota cannabis facility and their union to undertake an evaluation.

METHODS

NIOSH representatives visited the facility in August 2016 and April 2017. Surface wipe samples were collected for analysis of delta-9 tetrahydrocannabinol (Δ9-THC), delta-9 tetrahydrocannabinol acid (Δ9-THCA), cannabidiol, and cannabinol. Environmental air samples were collected for volatile organic compounds (VOCs), endotoxins (limulus amebocyte lysate assay), and fungal diversity (NIOSH two-stage BC251 bioaerosol sampler with internal transcribed spacer region sequencing analysis).

RESULTS

Surface wipe samples identified Δ9-THC throughout the facility. Diacetyl and 2,3-pentanedione were measured in initial VOC screening and subsequent sampling during tasks where heat transference was greatest, though levels were well below the NIOSH recommended exposure limits. Endotoxin concentrations were highest during processing activities, while internal transcribed spacer region sequencing revealed that the Basidiomycota genus, Wallemia, had the highest relative abundance.

CONCLUSIONS

To the authors' knowledge, this is the first published report of potential diacetyl and 2,3-pentanedione exposure in the cannabis industry, most notably during cannabis decarboxylation. Endotoxin exposure was elevated during grinding, indicating that this is a potentially high-risk task. The findings indicate that potential health hazards of significance are present during cannabis processing, and employers should be aware of potential exposures to VOCs, endotoxin, and fungi. Further research into the degree of respiratory and dermal hazards and resulting health effects in this industry is recommended.

Landscape Plant Selection Criteria for the Allergic Patient

Patients with pollen-related allergies are concerned about the species within their landscape that provoke their symptoms. Allergists are often asked for guidance but few information sources are available to aid patients in the recognition of allergenic plants and strategies to avoid personal exposure to them. Landscaping and horticultural workers also have few reliable guidance references, and what is available usually extols the virtues of the plants rather than their negative features. The aim of this article was to provide the results of the Landscape Allergen Working Group that was formed by the AAAAI Aerobiology Committee, which aimed to fill these existing knowledge gaps and develop guidance on producing a low-allergenic landscape. Within the context that complete pollen avoidance is unrealistic, the workgroup introduces selection criteria, avoidance strategies, and guidance on low-allergenic plants that could be selected by patients to reduce the overall pollen burden in their landscape environment. Specific focus is placed on entomophilous plants, which require insects as dispersal vectors and generally produce lower quantities of pollen, compared with anemophilous (wind-pollinated) species. Other biological hazards that can be encountered while performing landscaping activities are additionally reviewed and avoidance methods presented with the aim of protecting gardeners, and workers in the landscape and horticulture industries. The guidance presented in this article will ultimately be a helpful resource for the allergist and assist in engaging patients who are seeking to reduce the burden of allergen in their landscape environment.

Characterization of fungi in office dust: Comparing results of microbial secondary metabolites, fungal internal transcribed spacer region sequencing, viable culture and other microbial indices

Recent developments in molecular and chemical methods have enabled the analysis of fungal DNA and secondary metabolites, often produced during fungal growth, in environmental samples. We compared 3 fungal analytical methods by analysing floor dust samples collected from an office building for fungi using viable culture, internal transcribed spacer (ITS) sequencing and secondary metabolites using liquid chromatography-tandem mass spectrometry. Of the 32 metabolites identified, 29 had a potential link to fungi with levels ranging from 0.04 (minimum for alternariol monomethylether) to 5700 ng/g (maximum for neoechinulin A). The number of fungal metabolites quantified per sample ranged from 8 to 16 (average = 13/sample). We identified 216 fungal operational taxonomic units (OTUs) with the number per sample ranging from 6 to 29 (average = 18/sample). We identified 37 fungal species using culture, and the number per sample ranged from 2 to 13 (average = 8/sample). Agreement in identification between ITS sequencing and culturing was weak (kappa = -0.12 to 0.27). The number of cultured fungal species poorly correlated with OTUs, which did not correlate with the number of metabolites. These suggest that using multiple measurement methods may provide an improved understanding of fungal exposures in indoor environments and that secondary metabolites may be considered as an additional source of exposure.

Collection and Extraction of Occupational Air Samples for Analysis of Fungal DNA

Traditional methods of identifying fungal exposures in occupational environments, such as culture and microscopy-based approaches, have several limitations that have resulted in the exclusion of many species. Advances in the field over the last two decades have led occupational health researchers to turn to molecular-based approaches for identifying fungal hazards. These methods have resulted in the detection of many species within indoor and occupational environments that have not been detected using traditional methods. This protocol details an approach for determining fungal diversity within air samples through genomic DNA extraction, amplification, sequencing, and taxonomic identification of fungal internal transcribed spacer (ITS) regions. ITS sequencing results in the detection of many fungal species that are either not detected or difficult to identify to species level using culture or microscopy. While these methods do not provide quantitative measures of fungal burden, they offer a new approach to hazard identification and can be used to determine overall species richness and diversity within an occupational environment.

Microbial hazards during harvesting and processing at an outdoor United States cannabis farm

Cannabis cultivation is an emerging industry within the United States. Organic dust derived in part from naturally occurring microorganisms is known to cause byssinosis in the hemp industry. In this pilot study, bacteria and fungi encountered by workers at an outdoor cannabis farm that utilized organic practices were elucidated by 16 S ribosomal RNA (rRNA) and Internal Transcribed Spacer (ITS) region sequencing, respectively. Area (n = 14) and personal air samples (n = 12) were collected during harvesting and processing activities. 16 S rRNA and ITS regions of extracted bacterial and fungal genomic DNA were amplified and sequenced using Sanger sequencing. Bacterial sequencing resolved 1,077 sequences that were clustered into 639 operational taxonomic units (OTUs) and predominantly placed in the phylum, Actinobacteria (46%). Personal air samples revealed higher bacterial and Actinobacteria diversity compared to outdoor area samples collected within the facility (p < 0.05). A high degree of dissimilarity between bacteria was identified within and between samples. Fungal sequences (n = 985) were identified and predominantly clustered in the phylum Ascomycota (53%). Of the 216 fungal OTUs elucidated, the cannabis plant pathogenic species, Botrytis cinerea, was the most prevalent and accounted for 34% of all fungal sequences. The relative abundance of B. cinerea was highest in personal air samples (59%) compared to area samples collected in the drying room (19%), greenhouse (18%), and outdoor environment (6%). There was 49% sample similarity between fungi identified within personal air samples, but higher dissimilarity coefficients were observed within and between greenhouse, drying room, and outdoor area air samples. The results of this pilot study suggest that the cannabis farm workers are potentially exposed to Actinobacteria as well as the cannabis plant pathogen, B. cinerea during harvesting, bud-stripping, and hand-trimming processes.

Investigating local and systemic immune changes following sub-chronic inhalation of Aspergillus versicolor spores

Fungi are environmentally ubiquitous, and can be particularly abundant in damp indoor locations which may lead to pulmonary fungal exposure via inhalation of bioaerosols. Some of the adverse pulmonary health effects associated with fungal challenges include asthma, allergy, hypersensitivity pneumonitis, and local or disseminated infection. Here, we study the innate immune effects following 13 weeks sub-chronic inhalation exposures to spores derived from a common indoor fungal contaminant, Aspergillus versicolor. Compared to air-only control mice, A. versicolor-exposed B6C3F1 mice exhibited increased recruitment of leukocytes to the lung, particularly eosinophils and type 2 innate lymphoid cells (ILC2s), but also alveolar macrophages, inflammatory monocytes, and neutrophils following 13 weeks of exposure in nose-only inhalation chambers. Local expression of ccl2, ccl7, eotaxin, and il13 mRNA was increased in lung tissue. In addition, IL-4, CCL3, CCL4, CXCL1, and CXCL5 were increased in bronchoaveolar lavage fluid of A. versicolor-exposed mice compared to controls. Systemically, circulating CCL7, CXCL1, CXCL5, and CXCL10 were increased in serum of mice following inhalation of spores. Taken together, these data indicate A. versicolor elicits a Th2-biased immune response that is driven by multiple innate immune cell populations, including monocytes, eosinophils, and ILC2s.

Aspergillus fumigatus viability drives allergic responses to inhaled conidia

BACKGROUND

Aspergillus fumigatus-induced allergic airway disease has been shown to involve conidial germination in vivo, but the immunological mechanisms remain uncharacterized.

OBJECTIVE

A subchronic murine exposure model was used to examine the immunological mediators that are regulated in response to either culturable or nonculturable A fumigatus conidia.

METHODS

Female B6C3F1/N mice were repeatedly dosed via inhalation with 1 × 105 viable or heat-inactivated conidia (HIC), twice per week for 13 weeks (26 exposures). Control mice inhaled high-efficiency particulate arrestor-filtered air. The influence of A fumigatus conidial germination on the pulmonary immunopathological outcomes was evaluated by flow cytometry analysis of cellular infiltration in the airways, assessment of lung messenger RNA expression, quantitative proteomics, and histopathology of whole lung tissue.

RESULTS

Repeated inhalation of viable conidia, but not HIC, resulted in allergic inflammation marked by vascular remodeling, extensive eosinophilia, and accumulation of alternatively activated macrophages (AAMs) in the murine airways. More specifically, mice that inhaled viable conidia resulted in a mixed TH1 and TH2 (IL-13) cytokine response. Recruitment of eosinophils corresponded with increased Ccl11 transcripts. Furthermore, genes associated with M2 or alternatively activated macrophage polarization (eg, Arg1, Chil3, and Retnla) were significantly up-regulated in viable A fumigatus-exposed mice. In mice inhaling HIC, CD4+ T cells expressing IFN-γ (TH1) dominated the lymphocytic infiltration. Quantitative proteomics of the lung revealed metabolic reprogramming accompanied by mitochondrial dysfunction and endoplasmic reticulum stress stimulated by oxidative stress from repetitive microbial insult.

CONCLUSION

Our studies demonstrate that A fumigatus conidial viability in vivo is critical to the immunopathological presentation of chronic fungal allergic disease.

MicroRNA Regulation of Host Immune Responses following Fungal Exposure

Fungal bioaerosols are ubiquitous in the environment and human exposure can result in a variety of health effects ranging from systemic, subcutaneous, and cutaneous infections to respiratory morbidity including allergy, asthma, and hypersensitivity pneumonitis. Recent research has focused on the role of microRNAs (miRNAs) following fungal exposure and is overlooked, yet important, group of regulators capable of influencing fungal immune responses through a variety of cellular mechanisms. These small non-coding ribose nucleic acids function to regulate gene expression at the post-transcriptional level and have been shown to participate in multiple disease pathways including cancer, heart disease, apoptosis, as well as immune responses to microbial hazards and occupational allergens. Recent animal model studies have characterized miRNAs following the exposure to inflammatory stimuli. Studies focused on microbial exposure, including bacterial infections, as well as exposure to different allergens have shown miRNAs, such as miR-21, miR-146, miR-132, miR-155, and the let-7 family members, to be involved in immune and inflammatory responses. Interestingly, the few studies have assessed that the miRNA profiles following fungal exposure have identified the same critical miRNAs that have been characterized in other inflammatory-mediated and allergy-induced experimental models. Review of available in vitro, animal and human studies of exposures to Aspergillus fumigatus, Candida albicans, Cryptococcus neoformans, Paracoccidioides brasiliensis, and Stachybotrys chartarum identified several miRNAs that were shared between responses to these species including miR-125 a/b (macrophage polarization/activation), miR-132 [toll-like receptor (TLR)2-mediated signaling], miR-146a (TLR mediated signaling, alternative macrophage activation), and miR-29a/b (natural killer cell function, C-leptin signaling, inhibition of Th1 immune response). Although these datasets provide preliminary insight into the role of miRNAs in fungal exposed models, interpretation of miRNA datasets can be challenging for researchers. To assist in navigating this rapidly evolving field, the aim of this review is to describe miRNAs in the framework of host recognition mechanisms and provide initial insight into the regulatory pathways in response to fungal exposure.

Variability of indoor fungal microbiome of green and non-green low-income homes in Cincinnati, Ohio

"Green" housing is designed to use low-impact materials, increase energy efficiency and improve occupant health. However, little is known about the indoor mycobiome of green homes. The current study is a subset of a multicenter study that aims to investigate the indoor environment of green homes and the respiratory health of asthmatic children. In the current study, the mycobiome in air, bed dust and floor dust was compared between green (study site) and non-green (control site), low-income homes in Cincinnati, Ohio. The samples were collected at baseline (within four months following renovation), and 12months after the baseline at the study site. Parallel sample collection was conducted in non-green control homes. Air samples were collected by PM2.5 samplers over 5-days. Bed and floor dust samples were vacuumed after the air sampling was completed. The DNA sample extracts were analyzed using ITS amplicon sequencing. Analysis indicated that there was no clear trend in the fungal communities between green and non-green homes. Instead, fungal community differences were greatest between sample types - air, bed, and floor. Microbial communities also changed substantially between sampling intervals in both green and non-green homes for all sample types, potentially indicating that there was very little stability in the mycobiomes. Research gaps remain regarding how indoor mycobiome fluctuates over time. Longer follow-up periods might elucidate the effect of green renovation on microbial load in buildings.

Assessment of fungal diversity in a water-damaged office building

Recent studies have described fungal communities in indoor environments using gene sequencing-based approaches. In this study, dust-borne fungal communities were elucidated from a water-damaged office building located in the northeastern region of the United States using internal transcribed spacer (ITS) rRNA gene sequencing. Genomic DNA was extracted from 5 mg of floor dust derived from 22 samples collected from either the lower floors (n = 8) or a top floor (n = 14) of the office building. ITS gene sequencing resolved a total of 933 ITS sequences and was clustered into 216 fungal operational taxonomic units (OTUs). Analysis of fungal OTUs at the 97% similarity threshold showed a difference between the lower and top floors that was marginally significant (p = 0.049). Species richness and diversity indices were reduced in the lower floor samples compared to the top floor samples and there was a high degree of compositional dissimilarity within and between the two different areas within the building. Fungal OTUs were placed in the phyla Ascomycota (55%), Basidiomycota (41%), Zygomycota (3%), Glomeromycota (0.4%), Chytridiomycota (0.3%), and unassigned fungi (0.5%). The Ascomycota classes with the highest relative abundances included the Dothideomycetes (30%) and Eurotiomycetes (16%). The Basidiomycota consisted of the classes Ustilaginomycetes (14%), Tremellomycetes (11%), and Agaricomycetes (8%). Sequence reads derived from the plant pathogen Ustilago syntherismae were the most abundant in the analysis as were obligate Basidiomycota yeast species that accounted for 12% and 11% of fungal ITS sequences, respectively. ITS gene sequencing provides additional insight into the diversity of fungal OTUs. These data further highlight the contribution of fungi placed in the phylum Basidiomycota, obligate yeasts, as well as xerophilic species that are typically not resolved using traditional culture methods.

Microbial rRNA sequencing analysis of evaporative cooler indoor environments located in the Great Basin Desert region of the United States

Recent studies conducted in the Great Basin Desert region of the United States have shown that skin test reactivity to fungal and dust mite allergens are increased in children with asthma or allergy living in homes with evaporative coolers (EC). The objective of this study was to determine if the increased humidity previously reported in EC homes leads to varying microbial populations compared to homes with air conditioners (AC). Children with physician-diagnosed allergic rhinitis living in EC or AC environments were recruited into the study. Air samples were collected from the child's bedroom for genomic DNA extraction and metagenomic analysis of bacteria and fungi using the Illumina MiSeq sequencing platform. The analysis of bacterial populations revealed no major differences between EC and AC sampling environments. The fungal populations observed in EC homes differed from AC homes. The most prevalent species discovered in AC environments belonged to the genera Cryptococcus (20%) and Aspergillus (20%). In contrast, the most common fungi identified in EC homes belonged to the order Pleosporales and included Alternaria alternata (32%) and Phoma spp. (22%). The variations in fungal populations provide preliminary evidence of the microbial burden children may be exposed to within EC environments in this region.

Fungal Microbiomes Associated with Green and Non-Green Building Materials

Water-damaged buildings can lead to fungal growth and occupant health problems. Green building materials, derived from renewable sources, are increasingly utilized in construction and renovations. However, the question as to what fungi will grow on these green compared to non-green materials, after they get wet, has not been adequately studied. By determining what fungi grow on each type of material, the potential health risks can be more adequately assessed. In this study, we inoculated green and non-green pieces of ceiling tile, composite board, drywall, and flooring with indoor dust containing a complex mixture of naturally occurring fungi. The materials were saturated with water and incubated for two months in a controlled environment. The resulting fungal microbiomes were evaluated using ITS amplicon sequencing. Overall, the richness and diversity of the mycobiomes on each pair of green and non-green pieces were not significantly different. However, different genera dominated on each type of material. For example, Aspergillus spp. had the highest relative abundance on green and non-green ceiling tiles and green composite boards, but Peniophora spp. dominated the non-green composite board. In contrast, Penicillium spp. dominated green and non-green flooring samples. Green gypsum board was dominated by Phialophora spp. and Stachybotrys spp., but non-green gypsum board by Myrothecium spp. These data suggest that water-damaged green and non-green building materials can result in mycobiomes that are dominated by fungal genera whose member species pose different potentials for health risks.

Investigating a persistent odor at an aircraft seat manufacturer

An aircraft seat manufacturing company requested a NIOSH health hazard evaluation to help identify a strong odor that had persisted throughout the facility for over a year. Employees reported experiencing health effects thought to be related to the odor. We collected and analyzed area air samples for volatile organic compounds, endotoxin, bacterial and fungal metagenome, and metalworking fluid aerosol. Bulk metalworking fluid samples were analyzed for endotoxin, bacterial and fungal metagenome, and viable bacteria and fungus. We also evaluated the building ventilation systems and water diversion systems. Employees underwent confidential medical interviews about work practices, medical history, and health concerns. Based on our analyses, the odor was likely 2-methoxy-3,5-dimethylpyrazine. This pyrazine was found in air samples across the facility and originated from bacteria in the metalworking fluid. We did not identify bacteria known to produce the compound but bacteria from the same Proteobacteria order were found as well as bacteria from orders known to produce other pyrazines. Chemical and biological contaminants and odors could have contributed to health symptoms reported by employees, but it is likely that the symptoms were caused by several factors. We provided several recommendations to eliminate the odor including washing and disinfecting the metalworking machines and metalworking fluid recycling equipment, discarding all used metalworking fluid, instituting a metalworking fluid maintenance program at the site, and physically isolating the metalworking department from other departments.

Influence of Aspergillus fumigatus conidia viability on murine pulmonary microRNA and mRNA expression following subchronic inhalation exposure

BACKGROUND

Personal exposure to fungal bioaerosols derived from contaminated building materials or agricultural commodities may induce or exacerbate a variety of adverse health effects. The genomic mechanisms that underlie pulmonary immune responses to fungal bioaerosols have remained unclear.

OBJECTIVE

The impact of fungal viability on the pulmonary microRNA and messenger RNA profiles that regulate murine immune responses was evaluated following subchronic inhalation exposure to Aspergillus fumigatus conidia.

METHODS

Three groups of naïve B6C3F1/N mice were exposed via nose-only inhalation to A. fumigatus viable conidia, heat-inactivated conidia (HIC), or HEPA-filtered air twice a week for 13 weeks. Total RNA was isolated from whole lung 24 and 48 h postfinal exposure and was further processed for gene expression and microRNA array analysis. The molecular network pathways between viable and HIC groups were evaluated.

RESULTS

Comparison of data sets revealed increased Il4, Il13 and Il33 expression in mice exposed to viable vs. HIC. Of 415 microRNAs detected, approximately 50% were altered in mice exposed to viable vs. HIC 48 h postexposure. Significantly down-regulated (P ≤ 0.05) miR-29a-3p was predicted to regulate TGF-β3 and Clec7a, genes involved in innate responses to viable A. fumigatus. Also significantly down-regulated (P ≤ 0.05), miR-23b-3p regulates genes involved in pulmonary IL-13 and IL-33 responses and SMAD2, downstream of TGF-β signalling. Using Ingenuity Pathway Analysis, a novel interaction was identified between viable conidia and SMAD2/3.

CONCLUSIONS AND CLINICAL RELEVANCE

Examination of the pulmonary genetic profiles revealed differentially expressed genes and microRNAs following subchronic inhalation exposure to A. fumigatus. MicroRNAs regulating genes involved in the pulmonary immune responses were those with the greatest fold change. Specifically, germinating A. fumigatus conidia were associated with Clec7a and were predicted to interact with Il13 and Il33. Furthermore, altered microRNAs may serve as potential biomarkers to evaluate fungal exposure.

Differences in grass pollen allergen exposure across Australia

Objective: Allergic rhinitis and allergic asthma are important chronic diseases posing serious public health issues in Australia with associated medical, economic, and societal burdens. Pollen are significant sources of clinically relevant outdoor aeroallergens, recognised as both a major trigger for, and cause of, allergic respiratory diseases. This study aimed to provide a national, and indeed international, perspective on the state of Australian pollen data using a large representative sample.

Methods: Atmospheric grass pollen concentration is examined over a number of years within the period 1995 to 2013 for Brisbane, Canberra, Darwin, Hobart, Melbourne, and Sydney, including determination of the ‘clinical’ grass pollen season and grass pollen peak.

Results: The results of this study describe, for the first time, a striking spatial and temporal variability in grass pollen seasons in Australia, with important implications for clinicians and public health professionals, and the Australian grass pollen‐allergic community.

Conclusions: These results demonstrate that static pollen calendars are of limited utility and in some cases misleading. This study also highlights significant deficiencies and limitations in the existing Australian pollen monitoring and data.

Implications: Establishment of an Australian national pollen monitoring network would help facilitate advances in the clinical and public health management of the millions of Australians with asthma and allergic rhinitis.

Regional and seasonal variation in airborne grass pollen levels between cities of Australia and New Zealand

Although grass pollen is widely regarded as the major outdoor aeroallergen source in Australia and New Zealand (NZ), no assemblage of airborne pollen data for the region has been previously compiled. Grass pollen count data collected at 14 urban sites in Australia and NZ over periods ranging from 1 to 17 years were acquired, assembled and compared, revealing considerable spatiotemporal variability. Although direct comparison between these data is problematic due to methodological differences between monitoring sites, the following patterns are apparent. Grass pollen seasons tended to have more than one peak from tropics to latitudes of 37°S and single peaks at sites south of this latitude. A longer grass pollen season was therefore found at sites below 37°S, driven by later seasonal end dates for grass growth and flowering. Daily pollen counts increased with latitude; subtropical regions had seasons of both high intensity and long duration. At higher latitude sites, the single springtime grass pollen peak is potentially due to a cooler growing season and a predominance of pollen from C₃ grasses. The multiple peaks at lower latitude sites may be due to a warmer season and the predominance of pollen from C₄ grasses. Prevalence and duration of seasonal allergies may reflect the differing pollen seasons across Australia and NZ. It must be emphasized that these findings are tentative due to limitations in the available data, reinforcing the need to implement standardized pollen-monitoring methods across Australasia. Furthermore, spatiotemporal differences in grass pollen counts indicate that local, current, standardized pollen monitoring would assist with the management of pollen allergen exposure for patients at risk of allergic rhinitis and asthma.

Subchronic exposures to fungal bioaerosols promotes allergic pulmonary inflammation in naïve mice

BACKGROUND

Epidemiological surveys indicate that occupants of mold contaminated environments are at increased risk of respiratory symptoms. The immunological mechanisms associated with these responses require further characterization.

OBJECTIVE

The aim of this study was to characterize the immunotoxicological outcomes following repeated inhalation of dry Aspergillus fumigatus spores aerosolized at concentrations potentially encountered in contaminated indoor environments.

METHODS

Aspergillus fumigatus spores were delivered to the lungs of naïve BALB/cJ mice housed in a multi-animal nose-only chamber twice a week for a period of 13 weeks. Mice were evaluated at 24 and 48 h post-exposure for histopathological changes in lung architecture, recruitment of specific immune cells to the airways, and serum antibody responses.

RESULT

Germinating A. fumigatus spores were observed in lungs along with persistent fungal debris in the perivascular regions of the lungs. Repeated exposures promoted pleocellular infiltration with concomitant epithelial mucus hypersecretion, goblet cell metaplasia, subepithelial fibrosis and enhanced airway hyperreactivity. Cellular infiltration in airways was predominated by CD4(+) T cells expressing the pro-allergic cytokine IL-13. Furthermore, our studies show that antifungal T cell responses (IFN-γ(+) or IL-17A(+) ) co-expressed IL-13, revealing a novel mechanism for the dysregulated immune response to inhaled fungi. Total IgE production was augmented in animals repeatedly exposed to A. fumigatus.

CONCLUSIONS & CLINICAL RELEVANCE

Repeated inhalation of fungal aerosols resulted in significant pulmonary pathology mediated by dynamic shifts in specific immune populations and their cytokines. These studies provide novel insights into the immunological mechanisms and targets that govern the health outcomes that result from repeated inhalation of fungal bioaerosols in contaminated environments.