Mycotoxin-induced depletion of intracellular glutathione and altered cytokine production in the human alveolar epithelial cell line A549

Citrinin as a potential anti-cancer therapy: A comprehensive review

Citrinin (CIT) is a polyketide-derived mycotoxin, which is produced by many fungal strains belonging to the gerena Monascus, Aspergillus, and Penicillium. It has been postulated that mycotoxins have several toxic mechanisms and are potentially used as antineoplastic agents. Therefore, the present study carried out a systematic review, including articles from 1978 to 2022, by collecting evidence in experimental studies of CIT antiplorifactive activity in cancer. The Data indicate that CIT intervenes in important mediators and cell signaling pathways, including MAPKs, ERK1/2, JNK, Bcl-2, BAX, caspases 3,6,7 and 9, p53, p21, PARP cleavage, MDA, reactive oxygen species (ROS) and antioxidant defenses (SOD, CAT, GST and GPX). These factors demonstrate the potential antitumor drug CIT in inducing cell death, reducing DNA repair capacity and inducing cytotoxic and genotoxic effects in cancer cells.

Metabolic profiling as a powerful tool for the analysis of cellular alterations caused by 20 mycotoxins in HepG2 cells

Mycotoxins are secondary fungal metabolites which exhibit toxic effects in low concentrations. Several mycotoxins are described as carcinogenic or immunosuppressive, but their underlying modes of action especially on molecular level have not yet been entirely elucidated. Metabolic profiling as part of the omics methods is a powerful tool to study the toxicity and the mode of action of xenobiotics. The use of hydrophilic interaction chromatography in combination with targeted mass spectrometric detection enables the selective and sensitive analysis of more than 100 polar and ionic metabolites and allows the evaluation of metabolic alterations caused by xenobiotics such as mycotoxins. For metabolic profiling, the hepato-cellular carcinoma cell line HepG2 was treated with sub-cytotoxic concentrations of 20 mycotoxins. Moniliformin and citrinin significantly affected target elements of the citric acid cycle, but also influenced glycolytic pathways and energy metabolism. Penitrem A, zearalenone, and T2 toxin mainly interfered with the urea cycle and the amino acid homeostasis. The formation of reactive oxygen species seemed to be influenced by T2 toxin and gliotoxin. Glycolysis was altered by ochratoxin A and DNA synthesis was affected by several mycotoxins. The observed effects were not limited to these metabolic reactions as the metabolic pathways are closely interrelated. In general, metabolic profiling proved to be a highly sensitive tool for hazard identification in comparison to single-target cytotoxicity assays as metabolic alterations were already observed at sub-toxic concentrations. Metabolic profiling could therefore be a powerful tool for the overall evaluation of the toxic properties of xenobiotics.

Cytotoxicity of Mycotoxins and Their Combinations on Different Cell Lines: A Review

Mycotoxins are secondary metabolites of molds and mainly produced by species of the genera Aspergillus, Penicillium and Fusarium. They can be synthesized on the field, during harvest as well as during storage. They are fairly stable compounds and difficult to remove. Among several hundreds of mycotoxins, according to the WHO, ochratoxin A, aflatoxins, zearalenone, deoxynivalenol, patulin, fumonisins as well as T-2 and HT-2 toxins deserve special attention. Cytotoxicity is one of the most important adverse properties of mycotoxins and is generally assessed via the MTT assay, the neutral red assay, the LDH assay, the CCK-8 assay and the ATP test in different cell lines. The apoptotic cell ratio is mainly assessed via flow cytometry. Aside from the assessment of the toxicity of individual mycotoxins, it is important to determine the cytotoxicity of mycotoxin combinations. Such combinations often exhibit stronger cytotoxicity than individual mycotoxins. The cytotoxicity of different mycotoxins often depends on the cell line used in the experiment and is frequently time- and dose-dependent. A major drawback of assessing mycotoxin cytotoxicity in cell lines is the lack of interaction typical for complex organisms (for example, immune responses).

Role of quercetin on sterigmatocystin-induced oxidative stress-mediated toxicity

Oxidative stress appears to be a common trigger for many of the effects associated with the exposure to various mycotoxins, including sterigmatocystin (STE). However, studies to alleviate STE toxicity through the use of natural antioxidants are sparsely reported in literature. In the present study, the cytoprotective effect of quercetin (QUE) was tested in SH-SY5Y cells against STE-induced oxidative stress and cytotoxicity. The MTT assay revealed that STE decreased cell viability, whereas pre-treatment of cells with QUE restored it. The QUE was also found to counteract STE-induced ROS generation and decrease STE-induced up-regulation of the expression of the stress-inducible enzymes HO-1 and NOS-2. Pre-treatment with QUE also prevented STE-induced nuclear translocation of NF-κB, as measured by immunofluorescence. Finally, considering the key role played by NF-κB in the regulation of inflammation, the effect of STE on the pro-inflammatory cytokines TNF-α and IL-6 expression was evaluated. Our results showed the down-regulation of TNF-α and IL-6 following STE exposure, suggesting a negative immunomodulatory effect of STE. In QUE pre-treated samples, TNF-α and IL-6 were significantly further reduced, indicating the anti-inflammatory role of QUE. The results of the present study demonstrate for the first time that QUE exerts a cytoprotective role in STE-induced toxicity.

In vitro study on aspects of molecular mechanisms underlying invasive aspergillosis caused by gliotoxin and fumagillin, alone and in combination

Gliotoxin (GT) and fumagillin (FUM) are mycotoxins most abundantly produced by Aspergillus fumigatus during the early stages of infection to cause invasive aspergillosis (IA). Therefore, we hypothesized that GT and FUM could be the possible source of virulence factors, which we put to test adopting in vitro monoculture and the novel integrated multiple organ co-culture (IdMOC) of A549 and L132 cell. We found that (i) GT is more cytotoxic to lung epithelial cells than FUM, and (ii) GT and FUM act synergistically to inflict pathology to the lung epithelial cell. Reactive oxygen species (ROS) is the master regulator of the cytotoxicity of GT, FUM and GT + FUM. ROS may be produced as a sequel to mitochondrial damage and, thus, mitochondria are both the source of ROS and the target to ROS. GT-, FUM- and GT + FUM-induced DNA damage is mediated either by ROS-dependent mechanism or directly by the fungal toxins. In addition, GT, FUM and GT + FUM may induce protein accumulation. Further, it is speculated that GT and FUM inflict epithelial damage by neutrophil-mediated inflammation. With respect to multiple organ cytotoxicity, GT was found to be cytotoxic at IC50 concentration in the following order: renal epithelial cells < type II epithelial cells < hepatocytes < normal lung epithelial cells. Taken together, GT and FUM alone and in combination contribute to exacerbate the damage of lung epithelial cells and, thus, are involved in the progression of IA.

A comprehensive review on biological properties of citrinin

Citrinin (CIT) is a mycotoxin which causes contamination in the food and is associated with different toxic effects. A web search on CIT has been conducted covering the timespan since 1946. The accumulated data indicate that CIT is produced by several fungal strains belonging to Penicillium, Aspergillus and Monascus genera, and is usually found together with another nephrotoxic mycotoxin, ochratoxin A. Although, it is evident that CIT exposure can exert toxic effects on the heart, liver, kidney, as well as reproductive system, the mechanism of CIT-induced toxicity remains largely elusive. It is still controversial what are the genotoxic and mutagenic effects of CIT. Until now, its toxic effect has been linked to the CIT-mediated oxidative stress and mitochondrial dysfunction in biological systems. However, the toxicity strongly depends on its concentration, route, frequency and time of exposure, as well as from the used test systems. Besides the toxic effects, CIT is also reported to possess a broad spectrum of bioactivities, including antibacterial, antifungal, and potential anticancer and neuro-protective effects in vitro. This systematic review presents the current state of CIT research with emphasis on its bioactivity profile.

Impact of Mycotoxins Secreted by Aspergillus Molds on the Inflammatory Response of Human Corneal Epithelial Cells

Exposure to molds and mycotoxins not only contributes to the onset of respiratory disease, it also affects the ocular surface. Very few published studies concern the evaluation of the effect of mycotoxin exposure on ocular cells. The present study investigates the effects of aflatoxin B₁ (AFB₁) and gliotoxin, two mycotoxins secreted by Aspergillus molds, on the biological activity of the human corneal epithelial (HCE) cells. After 24, 48, and 72 h of exposure, cellular viability and inflammatory response were assessed. Both endpoint cell viability colorimetric assays and continuous cell impedance measurements, providing noninvasive real-time assessment of the effect on cells, were performed. Cytokine gene expression and interleukin-8 release were quantified. Gliotoxin appeared more cytotoxic than AFB₁ but, at the same time, led to a lower increase of the inflammatory response reflecting its immunosuppressive properties. Real-time cell impedance measurement showed a distinct profile of cytotoxicity for both mycotoxins. HCE cells appeared to be a well-suited in vitro model to study ocular surface reactivity following biological contaminant exposure. Low, but persistent inflammation, caused by environmental factors, such as fungal toxins, leads to irritation and sensitization, and could be responsible for allergic manifestations which, in turn, could lead to mucosal hyper-reactivity.

Induction of pro-inflammatory gene expression by Escherichia coli and mycotoxin zearalenone contamination and protection by a Lactobacillus mixture in porcine IPEC-1 cells

This work investigated the effect of Escherichia coli K88 and zearalenone contamination on pro-inflammatory gene expression (Toll like receptors, cytokines) and signalling molecules and the protective activity of a mixture of Lactobacilli sp. (Lactobacillus plantarum, Lactobacillus acidofilus and Lactobacillus paracasei) in porcine intestinal epithelial cells as part of the local immune system. IPEC-1 cell monolayer was exposed for 1 h to the individual or combined action of E. coli, zearalenone and lactobacilli mixture. Our results showed that TLRs (1-10) and cytokine (IL-1,-6,-8,-10, TNF-α, IFN-γ) genes expressed early (after 1 h of culture) in IPEC-1 cells. E. coli alone increased the TLRs mRNA expression, especially TLR4 and the inflammatory cytokines while ZEA alone showed either no effect or a marginally effect on TLRs, cytokines, and signalling genes when compared to untreated cells. The combined actions of the two contaminants lead to a synergistically up-regulation of key cytokines (IFN-γ, IL-10 and TNF-α) and TLRs (-2,-3,-4,-6, and -10). The live lactobacilli mixture was able to attenuate the pathogen and mycotoxin-induced response by downregulated the majority of inflammatory related genes suggesting that this mixture has an immunomodulatory potential and may be used to lower the inflammatory response.

Changes in biosynthesis and metabolism of glutathione upon ochratoxin A stress in Arabidopsis thaliana

Ochratoxin A (OTA) is one of the most toxic mycotoxins, which is toxic to plants and simulates oxidative stress. Glutathione is an important antioxidant in plants and is closely associated with detoxification in cells. We have previously shown that OTA exposure induces obvious expression differences in genes associated with glutathione metabolism. To characterize glutathione metabolism and understand its role in OTA phytotoxicity, we observed the accumulation of GSH in the detached leaves of Arabidopsis thaliana under OTA treatment. OTA stimulated a defense response through enhancing glutathione-S-transferase, glutathione peroxidase, glutathione reductase activities, and the transcript levels of these enzymes were increased to maintain the total glutathione content. Moreover, the level of oxidized glutathione (GSSG) was increased and the ascorbate-glutathione cycle fluctuated in response to OTA. The depletion of glutathione using buthionine sulfoximine (BSO, inhibitor of glutamate-cysteine ligase) had no profound effect on OTA toxicity, as glutathione was regenerated through the ascorbate-glutathione cycle to maintain the total glutathione content. The ROS, MDA and GSH accumulation was significantly affected in the mutant gsh1, gr1 and gpx2 after treatment with OTA, which indicated that glutathione metabolism is directly involved in the oxidative stress response of Arabidopsis thaliana subjected to OTA. In conclusion, date demonstrate that glutathione-associated metabolism is closely related with OTA stress and glutathione play a role in resistance of Arabidopsis subjected to OTA.

Gliotoxin promotes Aspergillus fumigatus internalization into type II human pneumocyte A549 cells by inducing host phospholipase D activation

The internalization of Aspergillus fumigatus into lung epithelial cells is critical for the infection process in the host. Gliotoxin is the most potent toxin produced by A. fumigatus. However, its role in A. fumigatus internalization into the lung epithelial cells is still largely unknown. In the present study, the deletion of the gliP gene regulating the production of gliotoxin in A. fumigatus suppressed the internalization of conidia into the A549 lung epithelial cells, and this suppression could be rescued by the exogenous addition of gliotoxin. At lower concentrations, gliotoxin enhanced the internalization of the conidia of A. fumigatus into A549 cells; in contrast, it inhibited the phagocytosis of J774 macrophages in a dose-dependent manner. Under a concentration of 100 ng/ml, gliotoxin had no effect on A549 cell viability but attenuated ROS production in a dose-dependent manner. Gliotoxin significantly stimulated the phospholipase D activity in the A549 cells at a concentration of 50 ng/ml. This stimulation was blocked by the pretreatment of host cells with PLD1- but not PLD2-specific inhibitor. Morphological cell changes induced by gliotoxin were observed in the A549 cells accompanying with obvious actin cytoskeleton rearrangement and a moderate alteration of phospholipase D distribution. Our data indicated that gliotoxin might be responsible for modulating the A. fumigatus internalization into epithelial cells through phospholipase D1 activation and actin cytoskeleton rearrangement.

Deficient glutathione in the pathophysiology of mycotoxin-related illness

Evidence for the role of oxidative stress in the pathophysiology of mycotoxin-related illness is increasing. The glutathione antioxidant and detoxification systems play a major role in the antioxidant function of cells. Exposure to mycotoxins in humans requires the production of glutathione on an “as needed” basis. Research suggests that mycotoxins can decrease the formation of glutathione due to decreased gene expression of the enzymes needed to form glutathione. Mycotoxin-related compromise of glutathione production can result in an excess of oxidative stress that leads to tissue damage and systemic illness. The review discusses the mechanisms by which mycotoxin-related deficiency of glutathione may lead to both acute and chronic illnesses.

Regulation of IL-8 promoter activity by verrucarin A in human monocytic THP-1 cells

Macrocyclic trichothecenes have been frequently detected in fungi in water-damaged buildings and exhibited higher toxicity than the well-studied trichothecenes; however, the mechanism underlying their toxicity has been poorly understood. In this study, transcriptional regulation of the cytokine interleukin (IL)-8 by a macrocyclic trichothecene, verrucarin A (VA), in human monocytic THP-1 cells is reported. Consistent with previous findings, VA was 100-fold more cytotoxic than deoxynivalenol (DON), while ochratoxin A (OA) was not cytotoxic. In cells transduced with the wild-type IL-8 promoter luciferase construct, VA induced a biphasic dose response composed of an upregulation of luciferase expression at low concentrations of 0.01-1 ng/ml and a downregulation at high levels of 10 ng/ml and higher. In contrast, DON induced a sigmoid-shaped dose response with the EC50 of 11.6 ng/ml, while OA did not markedly affect the IL-8 expression. When cells were transduced with IL-8 promoter with a mutation of transcription factor nuclear factor-κB (NF-κB)-binding site, VA (1 ng/ml), DON (1000 ng/ml), and tumor necrosis factor (TNF) α (20 ng/ml)-induced luciferase expression were impaired. In addition, the NF-κB inhibitor caffeic acid phenethyl ester inhibited VA-, DON-, and TNFα-induced luciferase expression. Mutation of the CCAAT/enhancer-binding protein (CEBP) β binding site of the IL-8 promoter affected only DON-, but not VA- and TNFα-induced luciferase expression. Taken together, these results suggested that VA activated IL-8 promoter via an NF-κB-dependent, but not CEBPβ-dependent, pathway in human monocytes.

Inflammatory cytokine gene expression in THP-1 cells exposed to Stachybotrys chartarum and Aspergillus versicolor

Very little is known about the mechanisms that occur in human cells upon exposure to fungi as well as their mycotoxins. A better understanding of toxin-regulated gene expression would be helpful to identify safe levels of exposure and could eventually be the basis for establishing guidelines for remediation scenarios following a water intrusion event. In this research, cytokine mRNA expression patterns were investigated in the human monocytic THP-1 cell line exposed to fungal extracts of various fragment sizes obtained from Stachybotrys chartarum RTI 5802 and/or Aspergillus versicolor RTI 3843, two common and well-studied mycotoxin producing fungi. Cytokine mRNA expression was generally upregulated 2-10 times following a 24 h exposure to fungal extracts. Expression of the proinflammatory interleukin-1β, interleukin-8, and tumor necrosis factor-α genes increased while the anti-inflammatory gene interleukin-10 also increased albeit at very low level, suggesting that negative feedback regulation mechanism of production of proinflammatory cytokines initiated upon 24 h of incubation. In addition, submicron size extracts of A. versicolor caused significant death of THP-1 cells, whereas extracts of S. chartarum caused no cell death while the mixture of the two fungi had an intermediate effect. There was no general correlation between gene expression and fragment sizes, which suggests that all submicron fragments may contribute to inflammatory response.

Lactobacillus reuteri CRL 1098 and Lactobacillus acidophilus CRL 1014 differently reduce in vitro immunotoxic effect induced by Ochratoxin A

Ochratoxin A (OTA) is a widespread mycotoxin contaminating several food products which causes detrimental health effects. The ability of Lactobacillus reuteri CRL 1098 and Lactobacillus acidophilus CRL 1014 to prevent OTA effects on TNF-α and IL-10 production and apoptosis induction in human peripheral blood mononuclear cells (PBMC) was investigated. Membrane rafts participation in these responses was also evaluated. L. reuteri reduced by 29% the OTA inhibition of TNF-α production whereas L. acidophilus increased 8 times the TNF-α production by OTA treated-PBMC. Also, both bacteria reversed apoptosis induced by OTA by 32%. However, neither of the bacteria reversed the OTA inhibition on IL-10 production. On the other hand, the lactobacilli were less effective to reverse OTA effects on disrupted-rafts PBMC. This study shows that two lactobacilli strains can reduce some negative OTA effects, being membrane rafts integrity necessary to obtain better results. Also, the results highlight the potential capacity of some lactobacilli strains usually included in natural dietary components in milk-derived products and cereals feed, to reduce OTA toxicity once ingested by humans or animals.

Glutathione redox control of asthma: from molecular mechanisms to therapeutic opportunities

Asthma is a chronic inflammatory disorder of the airways associated with airway hyper-responsiveness and airflow limitation in response to specific triggers. Whereas inflammation is important for tissue regeneration and wound healing, the profound and sustained inflammatory response associated with asthma may result in airway remodeling that involves smooth muscle hypertrophy, epithelial goblet-cell hyperplasia, and permanent deposition of airway extracellular matrix proteins. Although the specific mechanisms responsible for asthma are still being unraveled, free radicals such as reactive oxygen species and reactive nitrogen species are important mediators of airway tissue damage that are increased in subjects with asthma. There is also a growing body of literature implicating disturbances in oxidation/reduction (redox) reactions and impaired antioxidant defenses as a risk factor for asthma development and asthma severity. Ultimately, these redox-related perturbations result in a vicious cycle of airway inflammation and injury that is not always amenable to current asthma therapy, particularly in cases of severe asthma. This review will discuss disruptions of redox signaling and control in asthma with a focus on the thiol, glutathione, and reduced (thiol) form (GSH). First, GSH synthesis, GSH distribution, and GSH function and homeostasis are discussed. We then review the literature related to GSH redox balance in health and asthma, with an emphasis on human studies. Finally, therapeutic opportunities to restore the GSH redox balance in subjects with asthma are discussed.

Immune modulatory effects of the foodborne contaminant citrinin in mice

The mycotoxin citrinin can cause mycotoxic nephropathy, cytotoxicity and genotoxicity. To investigate the immune modulatory effects, CTN was orally administered to female BALB/c mice at the dose of 1, 5, or 10 mg/kg body weight for 14 days, and several immunotoxicity tests were performed. The populations of F4/80+ cells and CD19+ cells were significantly decreased in spleen and MLN. In MLN, CD4+, CD8+, and CD4+CD25+Foxp3+ cell populations were increased. CD8+ cells were increased but CD19+ cells were decreased in intra-epithelial, lamina propria and Peyer's patches lymphocytes. In a cell proliferation assay, along with the increased proliferative capacities of ConA-induced splenocytes and MLN cells, IFN-γ production was increased. The expression of TLR 2 was increased in spleen, but TLR 3 expression in MLN was decreased. The level of serum IgM was reduced. Furthermore, apoptosis was induced in spleen, MLN and Peyer's patches and promoted by the change in the ratio of Bax/Bcl-2 activities. Autophagy gene Atg5 and Beclin-1 were up-regulated in spleen. The expressions of IL-1β, IL-10, and TNF-α were inhibited in murine macrophage cells pre-exposed with TLR ligands. These results indicate that CTN has multiple immune modulatory effects in mice that may alter normal functions of immune system.

Exposure to mycotoxins increases the allergic immune response in a murine asthma model

RATIONALE

Epidemiological studies have shown that indoor molds are associated with increased prevalence and exacerbation of respiratory symptoms and asthma. Mycotoxins, secondary metabolites of molds, may contribute to these effects.

OBJECTIVES

To investigate the adjuvant activity of mycotoxins on allergic airway inflammation.

METHODS

Balb/c mice were exposed via the airways to gliotoxin and via the intestine to patulin, sensitized with ovalbumin (OVA), and then analyzed in acute and chronic murine asthma models. In addition, the effect of mycotoxin exposure on dendritic cell (DC) function was investigated using murine bone marrow-derived DCs.

MEASUREMENTS AND MAIN RESULTS

Exposure of mice to both mycotoxins enhanced dose-dependently airway hyperreactivity, eosinophilic lung inflammation, and OVA-specific IgE serum levels compared with mice that received only the antigen. These findings correlated with increased Th2 cytokine levels and decreased IFN-gamma production. Long-term mycotoxin exposure exacerbated chronic airway inflammation and airway remodeling. In vitro or in vivo mycotoxin exposure inhibited IL-12 production in maturing DCs and enhanced airway inflammation after adoptive DC transfer into Balb/c mice. Mycotoxin exposure enhanced OVA-induced lung lipid peroxidation and moderately increased isoprostane levels in naive mice. Treatment of mycotoxin-exposed DCs with the antioxidants N-acetylcysteine or glutathione ethyl ester restored IL-12 secretion and pretreatment of exposed mice with N-acetylcysteine prevented the mycotoxin-induced increase of airway inflammation and AHR.

CONCLUSIONS

Our results demonstrate that gliotoxin and patulin increase the allergic immune response in mice by modulating the Th1/Th2 balance via direct effects on IL-12 secretion in DCs and by inducing oxidative stress.

Toxicological Properties of Citrinin

Citrinin (CTN) is a nephrotoxic mycotoxin produced by several fungal strains belonging to the generaPenicillium, Aspergillus, andMonascus.It contaminates various commodities of plant origin, cereals in particular, and is usually found together with another nephrotoxic mycotoxin, ochratoxin A (OTA). These two mycotoxins are believed to be involved in the aetiology of endemic nephropathy. In addition to nephrotoxicity, CTN is also embryocidal and fetotoxic. The genotoxic properties of CTN have been demonstrated with the micronuleus test (MN), but not with single-cell gel electrophoresis. The mechanism of CTN toxicity is not fully understood, especially not whether CTN toxicity and genotoxicity are the consequence of oxidative stress or of increased permeability of mitochondrial membranes. CTN requires complex cellular biotransformation to exert mutagenicity.

Compared with other mycotoxins, CTN contamination of food and feed is rather scarce. However, it is reasonable to believe that humans are much more frequently exposed to CTN than generally accepted, because it is produced by the same moulds as OTA, which is a common contaminant of human food all over the world.

At present, there are no specific regulations either in Croatia or in the European Union concerning CTN in any kind of commodity.

Mass spectrometry-based strategy for direct detection and quantification of some mycotoxins produced by Stachybotrys and Aspergillus spp. in indoor environments

Dampness in buildings has been linked to adverse health effects, but the specific causative agents are unknown. Mycotoxins are secondary metabolites produced by molds and toxic to higher vertebrates. In this study, mass spectrometry was used to demonstrate the presence of mycotoxins predominantly produced by Aspergillus spp. and Stachybotrys spp. in buildings with either ongoing dampness or a history of water damage. Verrucarol and trichodermol, hydrolysis products of macrocyclic trichothecenes (including satratoxins), and trichodermin, predominately produced by Stachybotrys chartarum, were analyzed by gas chromatography-tandem mass spectrometry, whereas sterigmatocystin (mainly produced by Aspergillus versicolor), satratoxin G, and satratoxin H were analyzed by high-performance liquid chromatography-tandem mass spectrometry. These mycotoxin analytes were demonstrated in 45 of 62 building material samples studied, in three of eight settled dust samples, and in five of eight cultures of airborne dust samples. This is the first report on the use of tandem mass spectrometry for demonstrating mycotoxins in dust settled on surfaces above floor level in damp buildings. The direct detection of the highly toxic sterigmatocystin and macrocyclic trichothecene mycotoxins in indoor environments is important due to their potential health impacts.