Laboratory experiments on membrane filter sampling of airborne mycotoxins produced by Stachybotrys atra corda

The fungus Stachybotrys chartarum has been implicated in cases of nonspecific indoor air quality complaints in adults and in cases of pulmonary hemorrhaging in infants. The effects that have been described have been attributed to mycotoxins. Previous dose-effect studies focused on exposure to a single mycotoxin in a solvent, a strategy which is unlikely to accurately characterize the effects of inhaled spores. In this study we examined the role of mycotoxins in the pulmonary effects caused by S. chartarum spores and the dose dependency of these effects. S. chartarum spores were extracted in methanol to reduce the mycotoxin content of the spores. Then either untreated (toxin-containing) or methanol-extracted S. chartarum spores were intratracheally instilled into male 10-week-old Charles River-Dawley rats. After 24 h, the lungs were lavaged, and the bronchoalveolar lavage fluid was analyzed to determine differences in lactic dehydrogenase, albumin, hemoglobin, myeloperoxidase, and leukocyte differential counts. Weight change was also monitored. Our data show that methanol extraction dramatically reduced the toxicity of S. chartarum spores. No statistically significant effects were observed in the bronchoalveolar lavage fluids of the animals that were treated with methanol-extracted spores at any dose. Conversely, dose-dependent effects of the toxin-containing spores were observed when we examined the lactic dehydrogenase, albumin, and hemoglobin concentrations, the polymorphonuclear leukocyte counts, and weight loss. Our findings show that a single, intense exposure to toxin-containing S. chartarum spores results in pulmonary inflammation and injury in a dose-dependent manner. Importantly, the effects are related to methanol-soluble toxins in the spores.Acute exposure to Stachybotrys chartarum spores results in severe pulmonary injury in animal models (15,16,21). Although several outbreaks of illness in humans have been attributed to respiratory exposure to S. chartarum, the causal link between fungal contamination in the indoor environment and adverse pulmonary effects has yet to be firmly established (4-6, 9, 13, 25).The majority of the data regarding dose-response relationships between mycotoxin exposure and health effects are 50% lethal dose data resulting from ingestion or injection exposure in animals (10, 26). There are no data on the effects of low doses and the effects of inhaled mycotoxins. One limiting factor in studies is the ability to detect the pulmonary effects of low doses, since such doses may not result in mortality or detectable histological changes. In addition, S. chartarum can concurrently produce several different mycotoxins, each of which has different effects. These toxins may act synergistically, and particle association may contribute to toxicity (1, 2, 14, 23).Bronchoalveolar lavage (BAL) has been used to detect adverse pulmonary effects resulting from indoor exposure to fungi (17). The indicators measured with BAL can be used to quantitatively evaluate pulmonary edema (albumin), cyt...

Section: Discussionmentioning

confidence: 99%

Reduction of Pulmonary Toxicity of Stachybotrys chartarum Spores by Methanol Extraction of Mycotoxins

Rao¹,

Brain²,

Burge³

2000

“…None of these compounds, however, have been a main focus of study for ailments arising from exposure to S. chartarum in indoor air. Instead, there has been much interest in the trichothecene mycotoxins that S. chartarum produces (1,27,32,33,39,40). These toxins include, but are not limited to, the macrocyclic trichothecenes verrucarins B and J, roridin E, satratoxins F, G, and H, and isosatratoxins F, G, and H (19,25).…”

mentioning

confidence: 99%

Detection of AirborneStachybotrys chartarumMacrocyclic Trichothecene Mycotoxins on Particulates Smaller than Conidia

Brasel

Douglas

Wilson

et al. 2005

116

Highly respirable particles (diameter, <1 m) 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.

“…chartarum airborne mycotoxins have been studied in various laboratory settings (4,34,44,47) and are known to be detrimental in several animal models (32,37,49). However, research that effectively demonstrates the presence of airborne S. chartarum trichothecene mycotoxins in native indoor environments is lacking.…”

mentioning

confidence: 99%

Detection of AirborneStachybotrys chartarumMacrocyclic Trichothecene Mycotoxins in the Indoor Environment

Brasel

Martin

Carriker

et al. 2005

115

103

The existence of airborne mycotoxins in mold-contaminated buildings has long been hypothesized to be a potential occupant health risk. However, little work has been done to demonstrate the presence of these compounds in such environments. The presence of airborne macrocyclic trichothecene mycotoxins in indoor environments with known Stachybotrys chartarum contamination was therefore investigated. In seven buildings, air was collected using a high-volume liquid impaction bioaerosol sampler (SpinCon PAS 450-10) under static or disturbed conditions. An additional building was sampled using an Andersen GPS-1 PUF sampler modified to separate and collect particulates smaller than conidia. Four control buildings (i.e., no detectable S. chartarum growth or history of water damage) and outdoor air were also tested. Samples were analyzed using a macrocyclic trichothecene-specific enzyme-linked immunosorbent assay (ELISA). ELISA specificity was tested using phosphate-buffered saline extracts of the fungal genera Aspergillus, Chaetomium, Cladosporium, Fusarium, Memnoniella, Penicillium, Rhizopus, and Trichoderma, five Stachybotrys strains, and the indoor air allergens Can f 1, Der p 1, and Fel d 1. For test buildings, the results showed that detectable toxin concentrations increased with the sampling time and short periods of air disturbance. Trichothecene values ranged from <10 to >1,300 pg/m 3 of sampled air. The control environments demonstrated statistically significantly (P < 0.001) lower levels of airborne trichothecenes. ELISA specificity experiments demonstrated a high specificity for the trichothecene-producing strain of S. chartarum. Our data indicate that airborne macrocyclic trichothecenes can exist in Stachybotrys-contaminated buildings, and this should be taken into consideration in future indoor air quality investigations.For the past 25 years, there has been growing concern about the presence of fungi and their adverse human health effects in indoor environments. Several genera of fungi, including Stachybotrys, Chaetomium, and Aspergillus, have raised particular concern because of their associated toxin production. To date, the majority of indoor air quality investigations have focused on analyses of mold growth on building materials (1,18,35,40) and measurements of airborne particulate matter, including dust, fungal conidia (6, 20), and animal danders (13). These types of investigations cannot directly assess occupant exposure to mycotoxins. Exposure to these factors can influence allergic hypersensitivity responses (2, 9, 29) and symptoms of asthma in certain individuals (11, 30) but most likely does not account for often-reported symptoms such as nausea, dizziness, nose bleeds, physical and mental fatigue, and neurological disorders (28, 39) seen in subjects occupying sick buildings.Among the many fungi isolated from contaminated indoor environments, Stachybotrys chartarum is one of the most well known. S. chartarum is a known producer of a number of potent mycotoxins, in particular the macrocyclic tricho...