Initial characterization of the hemolysin stachylysin from Stachybotrys chartarum

Production of Satratoxin G and H Is Tightly Linked to Sporulation in Stachybotrys chartarum

Stachybotrys chartarum is a toxigenic fungus that is frequently isolated from damp building materials or improperly stored forage. Macrocyclic trichothecenes and in particular satratoxins are the most potent mycotoxins known to be produced by this fungus. Exposure of humans or animals to these secondary metabolites can be associated with severe health problems. To assess the pathogenic potential of S. chartarum isolates, it is essential to cultivate them under conditions that reliably promote toxin production. Potato dextrose agar (PDA) was reported to be the optimal nutrition medium for satratoxin production. In this study, the growth of S. chartarum genotype S strains on PDA from two manufacturers led to divergent results, namely, well-grown and sporulating cultures with high satratoxin concentrations (20.8 ± 0.4 µg/cm2) versus cultures with sparse sporulation and low satratoxin production (0.3 ± 0.1 µg/cm2). This finding is important for any attempt to identify toxigenic S. chartarum isolates. Further experiments performed with the two media provided strong evidence for a link between satratoxin production and sporulation. A comparison of three-point and one-point cultures grown on the two types of PDA, furthermore, demonstrated an inter-colony communication that influences both sporulation and mycotoxin production of S. chartarum genotype S strains.

Stachybotrys chartarum-A Hidden Treasure: Secondary Metabolites, Bioactivities, and Biotechnological Relevance

Fungi are renowned as a fountainhead of bio-metabolites that could be employed for producing novel therapeutic agents, as well as enzymes with wide biotechnological and industrial applications. Stachybotrys chartarum (black mold) (Stachybotriaceae) is a toxigenic fungus that is commonly found in damp environments. This fungus has the capacity to produce various classes of bio-metabolites with unrivaled structural features, including cyclosporins, cochlioquinones, atranones, trichothecenes, dolabellanes, phenylspirodrimanes, xanthones, and isoindoline and chromene derivatives. Moreover, it is a source of various enzymes that could have variable biotechnological and industrial relevance. The current review highlights the formerly published data on S. chartarum, including its metabolites and their bioactivities, as well as industrial and biotechnological relevance dated from 1973 to the beginning of 2022. In this work, 215 metabolites have been listed and 138 references have been cited.

The Evolution of the Satratoxin and Atranone Gene Clusters of Stachybotrys chartarum

Stachybotrys chartarum is frequently isolated from damp building materials or improperly stored animal forage. Human and animal exposure to the secondary metabolites of this mold is linked to severe health effects. The mutually exclusive production of either satratoxins or atranones defines the chemotypes A and S. Based upon the genes (satratoxin cluster, SC1-3, sat or atranone cluster, AC1, atr) that are supposed to be essential for satratoxin and atranone production, S. chartarum can furthermore be divided into three genotypes: the S-type possessing all sat- but no atr-genes, the A-type lacking the sat- but harboring all atr-genes, and the H-type having only certain sat- and all atr-genes. We analyzed the above-mentioned gene clusters and their flanking regions to shed light on the evolutionary relationship. Furthermore, we performed a deep re-sequencing and LC-MS/MS (Liquid chromatography-mass spectrometry) analysis. We propose a first model for the evolution of the S. chartarum genotypes. We assume that genotype H represents the most ancient form. A loss of the AC1 and the concomitant acquisition of the SC2 led to the emergence of the genotype S. According to our model, the genotype H also developed towards genotype A, a process that was accompanied by a loss of SC1 and SC3.

Update on Stachybotrys chartarum-Black Mold Perceived as Toxigenic and Potentially Pathogenic to Humans

In nature, there are many species of fungi known to produce various mycotoxins, allergens and volatile organic compounds (VOCs), as well as the commonly known etiological agents of various types of mycoses. So far, none of them have provoked so much emotion among homeowners, builders, conservators, mycologists and clinicians as Stachybotrys chartarum. This species compared to fungi of the genera Fusarium and Aspergillus is not as frequently described to be a micromycete that is toxigenic and hazardous to human and animal health, but interest in it has been growing consistently for three decades. Depending on the authors of any given review article, attention is focused either on the clinical aspects alongside the role of this fungus in deterioration of biomaterials, or aspects related to its biology, ecology and taxonomic position. On the one hand, it is well established that inhalation of conidia, containing the highest concentrations of toxic metabolites, may cause serious damage to the mammalian lung, particularly with repeated exposure. On the other hand, we can find articles in which authors demonstrate that S. chartarum conidia can germinate and form hyphae in lungs but are not able to establish an effective infection. Finally, we can find case reports that suggest that S. chartarum infection is linked with acute pulmonary hemorrhage, based on fungal structures recovered from patient lung tissue. New scientific reports have verified the current state of knowledge and note that clinical significance of this fungus is exceedingly controversial. For these reasons, understanding S. chartarum requires reviewing the well-known toxigenic features and harmful factors associated with this fungus, by gathering the newest ones into a coherent whole. The research problem related to this fungus seems to be not overly publicized, and there is still a demand to truthfully define the real threats of S. chartarum and phylogenetically related species. The most important problem, which should be fully elucidated as soon as possible, remains the clarification of the pathogenicity of S. chartarum and related species. Maybe it is urgent time to ask a critical question, namely what exactly do we know 28 years after the outbreak of pulmonary hemorrhage in infants in Cleveland, Ohio, USA most likely caused by S. chartarum?

Toxin Production by Stachybotrys chartarum Genotype S on Different Culture Media

Stachybotrys (S.) chartarum had been linked to severe health problems in humans and animals, which occur after exposure to the toxic secondary metabolites of this mold. S. chartarum had been isolated from different environmental sources, ranging from culinary herbs and improperly stored fodder to damp building materials. To access the pathogenic potential of isolates, it is essential to analyze them under defined conditions that allow for the production of their toxic metabolites. All Stachybotrys species are assumed to produce the immunosuppressive phenylspirodrimanes, but the highly cytotoxic macrocyclic trichothecenes are exclusively generated by the genotype S of S. chartarum. In this study, we have analyzed four genotype S strains initially isolated from three different habitats. We grew them on five commonly used media (malt-extract-agar, glucose-yeast-peptone-agar, potato-dextrose-agar, cellulose-agar, Sabouraud-dextrose-agar) to identify conditions that promote mycotoxin production. Using LC-MS/MS, we have quantified stachybotrylactam and all S-type specific macrocyclic trichothecenes (satratoxin G, H, F, roridin E, L-2, verrucarin J). All five media supported a comparable fungal growth and sporulation at 25 °C in the dark. The highest concentrations of macrocyclic trichothecenes were detected on potato-dextrose-agar or cellulose-agar. Malt-extract-agar let to an intermediate and glucose-yeast-peptone-agar and Sabouraud-dextrose-agar to a poor mycotoxin production. These data demonstrate that the mycotoxin production clearly depends on the composition of the respective medium. Our findings provide a starting point for further studies in order to identify individual components that either support or repress the production of mycotoxins in S. chartarum.

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.

Nanopore Fabrication and Application as Biosensors in Neurodegenerative Diseases

Since its conception as an applied biomedical technology nearly 30 years ago, nanopore is emerging as a promising, high-throughput, biomarker-targeted diagnostic tool for clinicians. The attraction of a nanopore-based detection system is its simple, inexpensive, robust, user-friendly, high-throughput blueprint with minimal sample preparation needed prior to analysis. The goal of clinical-based nanopore biosensing is to go from sample acquisition to a meaningful readout quickly. The most extensive work in nanopore applications has been targeted at DNA, RNA, and peptide identification. Although, biosensing of pathological biomarkers, which is covered in this review, is on the rise. This review is broken into two major sections: (i) the current state of existing biological, solid state, and hybrid nanopore systems and (ii) the applications of nanopore biosensors toward detecting neurodegenerative biomarkers.

Truncated satratoxin gene clusters in selected isolates of the atranone chemotype of Stachybotrys chartarum (Ehrenb.) S. Hughes

The fungus Stachybotrys (S.) chartarum was isolated from culinary herbs, damp building materials, and improperly stored animal forage. Two distinct chemotypes of the fungus were described that produced either high-cytotoxic macrocyclic trichothecenes (S type) or low-cytotoxic atranones (A type). Recently, two distinct gene clusters were described that were found to be necessary for the biosynthesis of either macrocyclic trichothecenes (21 SAT (Satratoxin) genes) or atranones (14 ATR (Atranone) genes). In the current study, PCR primers were designed to detect SAT and ATR genes in 19 S. chartarum chemotype S and eight S. chartarum chemotype A strains. Our analysis revealed the existence of three different genotypes: satratoxin-producing strains that harbored all SAT genes but lacked the ATR gene cluster (genotype S), non-satratoxin-producing strains that possessed the ATR genes but lacked SAT genes (genotype A), and a hitherto undescribed hybrid genotype among non-satratoxin-producing strains that harbored all ATR genes and an incomplete set of SAT genes (genotype H). In order to improve the discrimination of genotypes, a triplex PCR assay was developed and applied for the analysis of S. chartarum and S. chlorohalonata cultures. The results show that genes for macrocyclic trichothecenes and atranones are not mutually exclusive in S. chartarum. Correlation of the new genotype-based concept with mycotoxin production data shows also that macrocyclic trichothecenes are exclusively produced by S. chartarum genotype S strains.

Antibodies to Molds and Satratoxin in Individuals Exposed in Water-Damaged Buildings

Immunoglobulin (Ig)A, IgM, and IgG antibodies against Penicillium notatum, Aspergillus niger, Stachybotrys chartarum, and satratoxin H were determined in the blood of 500 healthy blood donor controls, 500 random patients, and 500 patients with known exposure to molds. The patients were referred to the immunological testing laboratory for health reasons other than mold exposure, or for measurement of mold antibody levels. Levels of IgA, IgM, and IgG antibodies against molds were significantly greater in the patients (p < 0.001 for all measurements) than in the controls. However, in mold-exposed patients, levels of these antibodies against satratoxin differed significantly for IgG only (p < 0.001), but not for IgM or IgA. These differences in the levels of mold antibodies among the 3 groups were confirmed by calculation of z score and by Scheffé's significant difference tests. A general linear model was applied in the majority of cases, and 3 different subsets were formed, meaning that the healthy control groups were different from the random patients and from the mold-exposed patients. These findings indicated that mold exposure was more common in patients who were referred for immunological evaluation than it was in healthy blood donors. The detection of antibodies to molds and satratoxin H likely resulted from antigenic stimulation of the immune system and the reaction of serum with specially prepared mold antigens. These antigens, which had high protein content, were developed in this laboratory and used in the enzyme-linked immunosorbent assay (ELISA) procedure. The authors concluded that the antibodies studied are specific to mold antigens and mycotoxins, and therefore could be useful in epidemiological and other studies of humans exposed to molds and mycotoxins.

Identification of Stachybotrys spp. by MALDI-TOF mass spectrometry

Stachybotrys (S.) spp. are omnipresent cellulolytic molds. Some species are highly toxic owing to their ability to synthesize various secondary metabolites such as macrocyclic trichothecenes or hemolysins. The reliable identification of Stachybotrys at species level is currently limited to genome-based identification. This study aimed to establish a fast and reliable MALDI-TOF MS identification method by optimizing the pre-analytical steps for protein extraction for subsequent generation of high-quality fingerprint mass spectra. Eight reference strains of the American Type Culture Collection and the Technical University of Denmark were cultivated in triplicate (biological repetitions) for 2 days in malt extract broth. The mycelia (1.5 ml) were first washed with 75 % ethanol and an additional washing step with dimethyl sulfoxide (10 %) was added to remove unspecific low weight masses. Furthermore, mycelia were broken with roughened glass beads in formic acid (70 %) and acetonitrile. The method was successfully applied to a total of 45 isolates of Stachybotrys originating from three different habitats (indoor, feed, and food samples; n = 15 each): Twenty-seven isolates of S. chartarum and 18 isolates of S. chlorohalonata could be identified by MALDI-TOF MS. The data obtained exactly matched those obtained by genome-based identification. The mean score values for S. chartarum ranged from 2.509 to 2.739 and from 2.148 to 2.622 for S. chlorohalonata with a very good reproducibility: the relative standard deviations were between 0.3 % and 6.8 %. Thus, MALDI-TOF MS proved to be a fast and reliable alternative to identification of Stachybotrys spp. by nucleotide amplification and sequencing.

Localization of Satratoxin-G in Stachybotrys chartarum Spores and Spore-Impacted Mouse Lung Using Immunocytochemistry

Satratoxin-G (SG) is the major macrocyclic trichothecene mycotoxin produced by Stachybotrys chartarum ( atra) and has been implicated as a cause of a number of animal and human health problems including pulmonary hemorrhage in infants. However, there is little understanding where this toxin is localized in the spores and mycelial fragments of this species or in the lung impacted by SG-sequestered spores. The purpose of this study was to evaluate the distribution of SG in S. chartarum spores and mycelium in culture, and spore-impacted mouse lung in vivo, using immunocytochemistry. SG was localized predominately in S. chartarum spores with moderate labelling of the phialide-apex walls. Labelling was primarily along the outer plasmalemma surface and in the inner wall layer. Only modest labelling was observed in hyphae. Toxin localization at these sites supports the position that spores contain the highest satratoxin concentrations and that the toxin is constitutively produced. In impacted mouse lung, highest SG labelling was detected in lysosomes, along the inside of the nuclear membrane in nuclear heterochromatin and RER within alveolar macrophages. Alveolar type II cells also showed modest labelling of the nuclear heterochromatin and RER. There was no evidence that the toxin accumulated in the neutrophils, fibroblasts, or other cells associated with the granulomas surrounding spores or mycelial fragments. These observations indicate that SG displays a high degree of cellular specificity with respect to its uptake in mouse lung. They further indicate that the alveolar macrophages play an important role in the sequestration and immobilization of low concentrations of the toxin.

Enzymatic and toxigenic ability of opportunistic fungi contaminating intensive care units and operation rooms at Assiut University Hospitals, Egypt

Total of 110 isolates belonging to 8 fungal species collected from intensive care units (ICUs) and operation rooms (ORs) at Assiut University hospitals were examined for their ability to produce some extracellular enzymes and mycotoxins which are considered as important factors involved in for fungal pathogenicity. The results revealed that 73, 92 and 78 out of the 110 tested isolates produced protease, lipase and urease respectively; meanwhile, 77 of the tested isolates exhibited some hemolytic activities. Chromatographic analysis (TLC) of the crude extract of the fungal isolates tested revealed that 79 isolates of them had the ability to produce at least one of these mycotoxic compounds (aflatoxins B₁, B₂, G₁, gliotoxin, fumigillin, T-2, zearalenone, roridin A & E, verrucarin A & J, trichoveroids, satratoxin H & E). These results demonstrate that the opportunistic fungal species isolated from (ICUs) and (ORs) and tested exhibited some enzymatic and mycotoxic ability which are the most effective virulence factors contributing to fungal pathogenicity indicating that the management of infection control unit at Assiut University hospitals must be aware of not only bacterial but also fungal contamination.

Fungal hemolysins

Hemolysins are a class of proteins defined by their ability to lyse red cells but have been described to exhibit pleiotropic functions. These proteins have been extensively studied in bacteria and more recently in fungi. Within the last decade, a number of studies have characterized fungal hemolysins and revealed a fascinating yet diverse group of proteins. The purpose of this review is to provide a synopsis of the known fungal hemolysins with an emphasis on those belonging to the aegerolysin protein family. New insight and perspective into fungal hemolysins in biotechnology and health are additionally presented.

Monoclonal antibodies to hyphal exoantigens derived from the opportunistic pathogen Aspergillus terreus

Aspergillus terreus has been difficult to identify in cases of aspergillosis, and clinical identification has been restricted to the broad identification of aspergillosis lesions in affected organs or the detection of fungal carbohydrates. As a result, there is a clinical need to identify species-specific biomarkers that can be used to detect invasive A. terreus disease. Monoclonal antibodies (MAbs) were developed to a partially purified preparation of cytolytic hyphal exoantigens (HEA) derived from A. terreus culture supernatant (CSN). Twenty-three IgG1 isotype murine MAbs were developed and tested for cross-reactivity against hyphal extracts of 54 fungal species. Sixteen MAbs were shown to be specific for A. terreus. HEA were detected in conidia, hyphae, and in CSN of A. terreus. HEA were expressed in high levels in the hyphae during early stages of A. terreus growth at 37°C, whereas at room temperature the expression of HEA peaked by days 4 to 5. Expression kinetics of HEA in CSN showed a lag, with peak levels at later time points at room temperature and 37°C than in hyphal extracts. Serum spiking experiments demonstrated that human serum components do not inhibit detection of the HEA epitopes by MAb enzyme-linked immunosorbent assay (ELISA). Immunoprecipitation and proteomic analysis demonstrated that MAbs 13E11 and 12C4 immunoprecipitated a putative uncharacterized leucine aminopeptidase (Q0CAZ7), while MAb 19B2 recognized a putative dipeptidyl-peptidase V (DPP5). Studies using confocal laser scanning microscopy showed that the uncharacterized leucine aminopeptidase mostly localized to extracellular matrix structures while dipeptidyl-peptidase V was mostly confined to the cytoplasm.

Production and characterization of IgM monoclonal antibodies against hyphal antigens of Stachybotrys species

Stachybotrys is a hydrophilic fungal genus that is well known for its ability to colonize water-damaged building materials in indoor environments. Personal exposure to Stachybotrys chartarum allergens, mycotoxins, cytolytic peptides, and other immunostimulatory macromolecules has been proposed to exacerbate respiratory morbidity. To date, advances in Stachybotrys detection have focused on the identification of unique biomarkers that can be detected in human serum; however, the availability of immunodiagnostic reagents to Stachybotrys species have been limited. In this study, we report the initial characterization of monoclonal antibodies (MAbs) against a semi-purified cytolytic S. chlorohalonata preparation (cScp) derived from hyphae. BALB/c mice were immunized with cScp and hybridomas were screened against the cScp using an antigen-mediated indirect ELISA. Eight immunoglobulin M MAbs were produced and four were specifically identified in the capture ELISA to react with the cScp. Cross-reactivity of the MAbs was tested against crude hyphal extracts derived from 15 Stachybotrys isolates representing nine Stachybotrys species as well as 39 other environmentally abundant fungi using a capture ELISA. MAb reactivity to spore and hyphal antigens was also tested by a capture ELISA and by fluorescent halogen immunoassay (fHIA). ELISA analysis demonstrated that all MAbs strongly reacted with extracts of S. chartarum but not with extracts of 39 other fungi. However, four MAbs showed cross-reactivity to the phylogenetically related genus Memnoniella. fHIA analysis confirmed that greatest MAb reactivity was ultrastructurally localized in hyphae and phialides. The results of this study further demonstrate the feasibility of specific MAb-based immunoassays for the detection of S. chartarum.

Characterization of recombinant terrelysin, a hemolysin of Aspergillus terreus

Fungal hemolysins are potential virulence factors. Some fungal hemolysins belong to the aegerolysin protein family that includes cytolysins capable of lysing erythrocytes and other cells. Here, we describe a hemolysin from Aspergillus terreus called terrelysin. We used the genome sequence database to identify the terrelysin sequence based on homology with other known aegerolysins. Aspergillus terreus mRNA was isolated, transcribed to cDNA and the open reading frame for terrelysin amplified by PCR using specific primers. Using the pASK-IBA6 cloning vector, we produced recombinant terrelysin (rTerrelysin) as a fusion product in Escherichia coli. The recombinant protein was purified and using MALDI-TOF MS determined to have a mass of 16,428 Da. Circular dichroism analysis suggests the secondary structure of the protein to be predominantly β-sheet. Results from thermal denaturation of rTerrelysin show that the protein maintained the β-sheet confirmation up to 65°C. Polyclonal antibody to rTerrelysin recognized a protein of approximately 16.5 kDa in mycelial extracts from A. terreus.

[Non allergic disorders associated with domestic moulds]

INTRODUCTION

Mouldy surfaces are encountered in up to 20 % of dwellings. Because this indoor air contamination is so widespread, respiratory physicians should be aware of its effects on health and especially of its impact on respiratory diseases.

BACKGROUND

The air contaminants within mouldy dwellings are very diverse. Therefore, a given heath effect cannot be attributed specifically to an individual contaminant. In the field of respiratory diseases, excluding asthma and allergy, long-term exposure to indoor moulds has been recognized as a risk factor for both ENT and bronchial symptoms. Hydrophilic moulds seem to have a larger health impact than other mould species. Among respiratory diseases, inhalation fever and, to a lesser extent, childhood respiratory infections are linked to exposure to moulds. In contrast, the relationship between exposure to indoor moulds and diseases such as sinusitis, mucous irritation syndrome, recurrent respiratory infections in adults, COPD and pulmonary haemorrhage has not been clearly established.

VIEWPOINT

There are still many scientific uncertainties in this field. However, the authorities are becoming more active in dealing with unhealthy buildings and encouraging research.

CONCLUSION

The health impact of mouldy dwellings represents a major public health issue. It needs incentives from institutions and financial support as well as the involvement of many specialists.

Inflammatory and Haematotoxic Potential of Indoor Stachybotrys chartarum (Ehrenb.) Hughes Metabolites

Mould Stachybotrys chartarum (Ehrenb.) Hughes is known to pose a health risk in indoor environments. Most of its strains can produce several intra- and extracellular trichothecene mycotoxins. Complex secondary metabolites of stachybotrys isolates from mouldy dwellings/public buildings in Slovakia were intratracheally instilled in Wistar male rats (4 μg in 0.2 mL of 0.2 % dimethylsulphoxide; diacetoxyscirpenol as the positive control). After three days, haematological parameters were measured in peripheral blood and inflammatory response biomarkers in bronchoalveolar lavage fluid (BALF), and the results were statistically analysed. Exometabolites proved to suppress red blood cell (RBC), decreasing the total RBC count, haemoglobin, and haematocrit. The exposed rats showed significantly higher total BALF cell count, indicating inflammation, lower alveolar macrophage counts, and increased granulocyte count related to the BALF cells. Due to haematotoxic and inflammation-inducing properties, metabolites of S. chartarum can cause damage to the airways and haematological disorders in occupants of mouldy buildings.

Mycotoxins in animal and human patients

The majority of human food and animal feed production occurs in a highly managed agroecosystem. Management decisions include variety grown, tillage and irrigation methods and practices, fertilization, pest and disease control, harvesting methods, and storage and transportation practices. This system is generally managed for optimum returns to labor and capital investments. The spores of toxigenic fungi have ubiquitous distribution and toxigenic fungi exploit food sources when conditions of moisture and temperature are above minimums for growth. The safety margins in the agroecosystem are close and are influenced by extrinsic factors such as climatic events. Control of fungal growth is important in management of raw feedstuffs, foodstuffs, condiments-spices, botanicals, and other consumable substances as they are grown, harvested, stored, and transported. The risk factors for mycotoxin production are weather conditions during crop growth and when the crop is mature, damage to seeds before, during, and after harvest, how commodities are physically handled, the presence of weed seeds and other foreign material in grain, and how commodity moisture and temperature are managed during storage and transportation. Diversion of commodities and by-products from human consumption to animal feedstuffs can increase the risk of mycotoxicoses in animals. The toxicology of selected toxigenic fungi and the mycotoxins they produce are reviewed.

Haemolytic fungi isolated from sago starch in Papua New Guinea

Sago haemolytic disease (SHD) is a rare but often fatal illness linked to consumption of stale sago starch in Papua New Guinea. Although the aetiology of SHD remains unknown, mycotoxins are suspected. This study investigated whether fungi isolated from Papua New Guinean sago starch were haemolytic. Filamentous fungi and yeasts from sago starch were grown on sheep blood agar and some on human blood agar. Clear haemolytic activity was demonstrated by 55% of filamentous fungal isolates, but not by yeasts. A semi-quantitative bioassay was developed involving incubation of human erythrocytes with fungal extracts. Extracts of cultures of Penicillium, Aspergillus and Fusarium all caused rapid haemolysis in the bioassay. Partial fractionation of extracts suggested that both polar and non-polar haemolytic components had haemolytic activity in vitro. Further work is warranted to identify these metabolites and determine if they play a role in SHD.

Immunohistochemical and immunocytochemical detection of SchS34 antigen in Stachybotrys chartarum spores and spore impacted mouse lungs

The purpose of this study was to evaluate the distribution of a 34 kD antigen isolated from S. chartarum sensu lato in spores and in the mouse lung 48 h after intra-tracheal instillation of spores by immuno-histochemistry. This antigen was localized in spore walls, primarily in the outer and inner wall layers and on the external wall surfaces with modest labelling observed in cytoplasm. Immuno-histochemistry revealed that in spore impacted mouse lung, antigen was again observed in spore walls, along the outside surface of the outer wall and in the intercellular space surrounding spores. In lung granulomas the labelled antigen formed a diffusate, some 2-3x the size of the long axis of spores, with highest concentrations nearest to spores. Collectively, these observations indicated that this protein not only displayed a high degree of specificity with respect to its location in spores and wall fragments, but also that it slowly diffuses into surrounding lungs.

Acute pulmonary hemorrhage during isoflurane anesthesia in two cats exposed to toxic black mold (Stachybotrys chartarum)

CASE DESCRIPTION

Acute pulmonary hemorrhage developed during isoflurane anesthesia in 2 Himalayan cats undergoing routine dental cleaning and prophylaxis.

CLINICAL FINDINGS

The cats were siblings and lived together. In both cats, results of pre-operative physical examinations and laboratory testing were unremarkable. Blood pressure and oxygen saturation were within reference ranges throughout the dental procedure. Approximately 15 to 20 minutes after administration of isoflurane was begun, frothy blood was noticed within the endotracheal tube. Blood was suctioned from the endotracheal tube, and the cats were allowed to recover from anesthesia.

TREATMENT AND OUTCOME

1 cat initially responded to supportive care but developed a second episode of spontaneous pulmonary hemorrhage approximately 30 hours later and died. The other cat responded to supportive care and was discharged after 4 days, but its condition deteriorated, and the cat died 10 days later. Subsequently, it was discovered that the home was severely contaminated with mold as a result of storm damage that had occurred approximately 7 months previously. Retrospective analysis of banked serum from the cats revealed satratoxin G, a biomarker for Stachybotrys chartarum, commonly referred to as "toxic black mold."

CLINICAL RELEVANCE

Findings highlight the potential risk of acute pulmonary hemorrhage in animals living in an environment contaminated with mold following flood damage.

The role of fungal proteinases in pathophysiology of Stachybotrys chartarum

The adverse health effects of Stachybotrys chartarum have often been linked to exposure to the trichothecene mycotoxins. Recent studies have shown that in addition to mycotoxins this fungus is capable of producing and secreting in vivo proteins such as hemolysins and proteinases. Spore extracts obtained from a high trichothecene producing isolate JS 58-17 exhibited a significantly lower proteolytic activity compared to the low trichothecene producer, JS 58-06. Growing isolates on rice or potato dextrose agar results in higher proteolytic activity of the spores compared to those grown on drywall. Proteinases in the spore extracts can hydrolyze gelatin and collagen I and IV. Analysis of zymograms shows the presence of several proteins with proteolytic activity in the spores of S. chartarum. Human tracheal epithelial cells exposed to spore extracts produced significantly higher levels of IL-6, IL-8, and TNF-alpha than control cells. This stimulation of cytokine production was completely abolished by Pefabloc, a serine protease inhibitor. Neutrophil numbers and proinflammatory cytokine (IL1-beta and TNF-alpha) concentrations were highly elevated in the lungs of 7 day old rat pups exposed intratracheally to 4 x 10(4) spores/gm body weight compared to control. No significant differences in those inflammatory indices in vivo were noted between the treatments with the high trichothecene producer, isolate JS 58-17 and JS 58-06, which does not produce macrocyclic trichothecenes. Immunohistochemistry revealed reduced collagen IV labeling in spore-induced lung granulomas in rat pups exposed to both isolates. These results suggest that proteinases from S. chartarum spores significantly contribute to lung inflammation and injury.

DNA fragmentation in developing lung fibroblasts exposed to Stachybotrys chartarum (atra) toxins

Stachybotrys chartarum (atra) is a toxic mold that grows on water-damaged cellulose-based materials. Research has revealed also that inhalation of S. chartarum spores caused marked changes in respiratory epithelium, especially to developing lungs. We analyzed the epigenetic potential of S. chartarum spore toxins on developing rat lung fibroblasts using single cell gel electrophoresis (comet assay). Isolated fetal lung fibroblasts were exposed to S. chartarum spore toxins for 15 min, 3, 14, or 24 hr and control cells were exposed to saline under the same conditions. Cells were embedded in agarose, electrophoresed under alkaline conditions and silver stained. DNA damage was assessed in terms of fragmentation as measured by comet tail length (DNA migration) and intensity (% DNA contained within head and tail). Upon visual inspection, control fibroblasts showed no DNA fragmentation whereas S. chartarum-treated cells had definable comets of various degrees depending upon the time-course. Analyses of the comets revealed that exposure to S. chartarum spore toxins for at least 15 min to 14 hr, induced increased DNA fragmentation in a time-dependent manner. The fact that exposure to toxins for 24 hr showed less damage suggested that developing lung fibroblasts may have the capability of repairing DNA fragmentation.

Strain differences influence murine pulmonary responses to Stachybotrys chartarum

When the fungus Stachybotrys chartarum is inhaled, its mycotoxins may cause lung injury and inflammation. The severity of human responses to S. chartarum in both occupational and home settings varies widely. To explore these differences, we intratracheally instilled C3H/HeJ, BALB/c, and C57BL/6J mice with S. chartarum spores suspended in saline. One day later, the mice were humanely killed, bronchoalveolar lavage (BAL) was performed, and biochemical and cellular indicators of lung injury and inflammation were measured. BALB/c mice showed the highest myeloperoxidase activity, albumin and hemoglobin levels, and neutrophil numbers in their BAL among the three strains. BALB/c was the only strain to show significant increases in keratinocyte-derived cytokine (KC), monocyte chemotactic protein (MCP)-1, MCP-3, macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, MIP-1gamma, MIP-2, RANTES, IL-1alpha, IL-1beta, IL-3, IL-6, IL-18, leukemia inhibitory factor, macrophage colony-stimulating factor, and TNF-alpha. A model of allergen-induced airway inflammation was examined to assess whether underlying allergic inflammation might contribute to increased susceptibility to S. chartarum-induced pulmonary inflammation and injury. Surprisingly, in BALB/c mice, ovalbumin-induced airway inflammation produced a protective effect against some S. chartarum-induced pulmonary responses. This is the first report of mammalian strain differences affecting responses to S. chartarum. These responses differ from those reported for LPS and other fungi. Analogous underlying genetic differences may contribute to the wide range of sensitivity to Stachybotrys among humans.

Mycotoxin adducts on human serum albumin: biomarkers of exposure to Stachybotrys chartarum

OBJECTIVE

Despite the growing body of evidence showing adverse health effects from inhalation exposure to the trichothecene-producing mold Stachybotrys chartarum, controversy remains. Currently, there are no reliable assays suitable for clinical diagnosis of exposure. We hypothesized that satratoxin G (SG) -albumin adducts may serve as biomarkers of exposure to this fungus.

DESIGN

We studied the formation of adducts of SG with serum albumin in vitro using Western blots and mass spectrometry (MS) and searched for similar adducts formed in vivo using human and animal serum.

RESULTS

Samples of purified human serum albumin that had been incubated with increasing concentrations of SG showed concentration-dependent albumin bands in Western blots developed with anti-SG antibodies. MS analysis found that as many as 10 toxin molecules can be bound in vitro to one albumin molecule. The sequencing of albumin-adduct tryptic peptides and the analysis of pronase/aminopeptidase digests demonstrated that lysyl, cysteinyl, and histidyl residues are involved in the formation of these adducts. Serum samples from three patients with documented exposure to S. chartarum similarly revealed lysine-, cysteine-, and histidine-SG adducts after exhaustive digestion, affinity column enrichment, and MS analysis. These adducts were also found in the sera from rats exposed to the spores of S. chartarum in contrast to control human subjects and control animals.

CONCLUSIONS

These data document the occurrence of SG-albumin adducts in both in vitro experiments and in vivo human and animal exposures to S. chartarum.

RELEVANCE TO CLINICAL PRACTICE

SG-amino acid adducts may serve as reliable dosimeter biomarkers for detection of exposure to S. chartarum.

Hemolysin chrysolysin from Penicillium chrysogenum promotes inflammatory response

Some strains of Penicillium chrysogenum produce a proteinaceous hemolysin, chrysolysinTM, when incubated on sheep's blood agar at 37 degrees C but not at 23 degrees C. However, 92% (11/12) of the indoor air isolates produced hemolysis but only 43% (3/7) of the non-indoor air isolates did so. Chrysolysin is an aggregating protein composed of approximately 2kDa monomers, contains one cysteine amino acid, and has an isoelectric point of 4.85. Treatment of murine macrophage cell line RAW 264.7 with purified chrysolysin caused statistically significant (T-test, p < 0.05) increased production of macrophage inflammatory protein-2 (MIP-2) in a dose dependent manner after 6 h treatment. This suggests that chrysolysin might act to promote the host's inflammatory response after P. chrysogenum exposures.

Ultraviolet germicidal irradiation disinfection of Stachybotrys chartarum

The ultraviolet germicidal irradiation (UVGI) dose necessary to inactivate fungal spores on an agar surface and the efficacy of UVGI were determined for cultures of Stachybotrys chartarum (ATCC 208877). This study employed a UVGI testing unit consisting of four chambers with a 9-W, Phillips, low pressure, mercury UVGI lamp in each chamber. The testing unit's apertures were adjusted to provide 50, 100, 150, and 200 µW/cm2 of uniform flux to the Petri dish surfaces, resulting in a total UVGI surface dose ranging from 12 to 144 mJ/cm2. The UVGI dose necessary to inactivate 90% of the S. chartarum was greater than the maximum dose of 144 mJ/cm2 evaluated in this study. While UVGI has been used to inactivate several strains of culturable fungal spores, S. chartarum was not susceptible to an appropriate dose of UVGI. The results of this study may not correlate directly to the effect of UVGI on airborne fungal spores. However, they indicate that current technology may not be efficacious as a supplement to ventilation unless it can provide higher doses of UVGI to kill spores, such as S. chartarum, traveling through the irradiated zone.Key words: Stachybotrys chartarum (synonyms S. atra, S. alternana), ultraviolet germicidal irradiation, fungi.

Detection of airborne Stachybotrys chartarum macrocyclic trichothecene mycotoxins on particulates smaller than conidia

Highly respirable particles (diameter, <1 microm) constitute the majority of particulate matter found in indoor air. It is hypothesized that these particles serve as carriers for toxic compounds, specifically the compounds produced by molds in water-damaged buildings. The presence of airborne Stachybotrys chartarum trichothecene mycotoxins on particles smaller than conidia (e.g., fungal fragments) was therefore investigated. Cellulose ceiling tiles with confluent Stachybotrys growth were placed in gas-drying containers through which filtered air was passed. Exiting particulates were collected by using a series of polycarbonate membrane filters with decreasing pore sizes. Scanning electron microscopy was employed to determine the presence of conidia on the filters. A competitive enzyme-linked immunosorbent assay (ELISA) specific for macrocyclic trichothecenes was used to analyze filter extracts. Cross-reactivity to various mycotoxins was examined to confirm the specificity. Statistically significant (P < 0.05) ELISA binding was observed primarily for macrocyclic trichothecenes at concentrations of 50 and 5 ng/ml and 500 pg/ml (58.4 to 83.5% inhibition). Of the remaining toxins tested, only verrucarol and diacetylverrucarol (nonmacrocyclic trichothecenes) demonstrated significant binding (18.2 and 51.7% inhibition, respectively) and then only at high concentrations. The results showed that extracts from conidium-free filters demonstrated statistically significant (P < 0.05) antibody binding that increased with sampling time (38.4 to 71.9% inhibition, representing a range of 0.5 to 4.0 ng/ml). High-performance liquid chromatography analysis suggested the presence of satratoxin H in conidium-free filter extracts. These data show that S. chartarum trichothecene mycotoxins can become airborne in association with intact conidia or smaller particles. These findings may have important implications for indoor air quality assessment.

Quantitative polymerase chain reaction analysis of fungi in dust from homes of infants who developed idiopathic pulmonary hemorrhaging

Fungal concentrations were measured in the dust of 6 homes in Cleveland, Ohio, where an infant developed pulmonary hemorrhage (pulmonary hemorrhage homes [PHH]) and 26 reference homes (RH) with no known fungal contamination. Quantitative polymerase chain reaction assays for 82 species (or assay groups) were used to identify and quantify fungal concentrations. The ratios of the geometric means of PHH to RH were >1 for 26 species (group I). However, the same ratios were <1 for 10 species (group II). Probit analysis of the sum of the logs of the concentrations of these 2 groups resulted in a 95% probability range for separating PHH from RH homes. The same 82 fungal species were also tested for hemolysin production on sheep's blood agar (incubated at 37 degree C). Hemolysins were more commonly produced by group I species (42%) compared with group II species (10%).

Clinical use of immunoassays in assessing exposure to fungi and potential health effects related to fungal exposure

OBJECTIVE

To review and summarize current evidence regarding the proper role of immunoassays in clinical assessments of exposure to fungi and health effects related to fungal exposure.

DATA SOURCES

We reviewed relevant scientific investigations and previously published reviews concerning this topic.

STUDY SELECTION

The authors' clinical, laboratory, and public health experiences were used to evaluate relevant data for scientific merit.

RESULTS

Testing to determine the presence of IgE to specific fungi may be a useful component of a complete clinical evaluation in the diagnosis of illnesses that can be caused by immediate hypersensitivity such as allergic rhinitis and asthma. Detection of IgG to specific fungi has been used as a marker of exposure to agents that may cause illnesses such as hypersensitivity pneumonitis. However, the ubiquitous nature of many fungi and the lack of specificity of fungal antigens limit the usefulness of these types of tests in the evaluation of potential building-related illness and fungal exposure. Specific serologic tests (such as tests for cryptococcal antigen, coccidioidal antibody, and Histoplasma antigen) have been shown to be useful in the diagnosis of some fungal infections, but these are the exception not the rule.

CONCLUSIONS

There is currently not enough scientific evidence to support the routine clinical use of immunoassays as a primary means of assessing environmental fungal exposure or health effects related to fungal exposure. Health care providers who care for persons expressing concerns about the relationship of symptoms to potential exposure to fungi are advised to use immunoassay results with care and only as an adjunct to a comprehensive approach to patient care.

Partial Amino Acid Sequence of a Cellulase-Like Component with IgE-Binding Properties from Stachybotrys chartarum

BACKGROUND

The aim of this study was to characterize the amino acid sequence of a selected Stachybotrys chartarum component and to investigate human IgE reactivity against components of S. chartarum and nine other fungal species.

METHODS

Human IgE reactivity against S. chartarum and nine other fungal extracts was investigated by the immunoblotting method. For automated amino acid sequencing analyses, the S. chartarum extract was purified by ion exchange chromatography prior to in-gel alkylation and digestion with modified trypsin.

RESULTS

Human IgE reactivity was detected against eight components in the S. chartarum extract. Over 80% of the sera from the exposed subjects and less than 50% of the control sera recognized the 33-, 48- and 50-kD S. chartarum components. The human sera detected a 48- to 50-kD component from the extracts of eight fungal species. Nineteen peptide sequences were identified from the 48-kD component of S. chartarum. An analysis of the peptide sequences revealed homology with known fungal glycoside hydrolase enzymes (cellulases).

CONCLUSIONS

The data showed human IgE reactivity against several S. chartarum components, including one at 48 kD. On the other hand, the human sera recognized 48- to 50-kD components from seven other fungal species, suggesting shared antigenic components (e.g. enolase) between the fungi. Thus, to our knowledge, this is the first antigen identified from S. chartarum.

Pathogenesis of indoor fungal diseases*

Mold growth within homes and other buildings has been associated to varying degrees with human health problems. These problems vary from allergenic disease to toxicosis. Case definitions for mold exposure have not been adequately defined to allow for a pathognomonic diagnosis of mold-caused disease following indoor exposure. Some important factors that may contribute to the pathogenesis of indoor mold induced disease include beta (1,3)-D-glucans, outer cell wall fungal hydrophobins, 1,8-dihydroxynaphthalene melanin, fungal volatile organic compounds, mycotoxins, and stachylysin. The information in this contribution was presented as the ISHAM Presidential address as a means to clarify some of the confusing surrounding indoor mold-related health issues.

Stachybotrys chartarum: a fungus for our time

Stachybotrys chartarum, a fungus found in damp buildings and sometimes ascribed a role in building-related illnesses, produces a variety of secondary metabolites including trichothecenes, triprenylated phenolics, and a new class of diterpenoids called atranones. A related fungus, Memnoniella echinata also produces trichothecenes and the triprenylated phenolics. Herein the production of these compounds from cultures of the above are reviewed.

Stachybotrys chartarum: cause of human disease or media darling?

This is a review of the literature of associations of the saprotrophic fungus Stachybotrys chartarum sensu lato with human and animal illnesses. This fungus grows on very wet cellulose-based building materials. S. chartarum has been the subject of considerable media attention because of temporal associations of exposure with unexpected and dramatic outcomes such as infant pulmonary hemosiderosis and neurocognitive damage. It is generally accepted that living or working in mouldy environments is associated with building related asthma, exacerbating asthma in mould-sensitive asthmatics and increased rates of upper respiratory disease. However, such relationships are with building-associated moulds, comprising many species that colonize wet or damp building materials, and are not specific to S. chartarum. There is limited evidence that severe lung damage can occur from building exposure to S. chartarum but possibly only under conditions of exposure that approach those associated with handling contaminated straw. There is no positive evidence in the literature to account for putative neurological damage resulting from exposure to this mould.