Mould exposure at home relates to inflammatory markers in blood

Airway Exposure to 1,3-Beta-d-Glucan Induces Airway Hyperresponsiveness in Guinea Pigs

1,3-Beta-d-glucan (β-glucan) is a component of mold cell walls and is frequently found in fungi and house dust mites. The studies of β-glucan are inconsistent, although it has been implicated in airway adverse responses. This study was carried out to determine whether airway hyperresponsiveness was seen 24 h after airway exposure to β-glucan in guinea pigs. Two matching guinea pigs were exposed intratracheally to either β-glucan or its vehicle. Twenty-four hours after intratracheal instillation, there was no difference between these two groups in the baseline of the total pulmonary resistance (R _L), dynamic lung compliance (C _dyn), arterial blood pressure, and heart rate. In contrast, the responses of R _L to capsaicin injection were significantly increased in β-glucan animals; capsaicin at the same dose of 3.2 μg/kg increased R _L by 184% in vehicle animals and by 400% in β-glucan animals. The effective dose 200% to capsaicin injection was lower in the β-glucan animals. Furthermore, the increases in R _L were partially reduced after transient lung hyperinflation to recruit the occluding airways; however, the R _L induced by capsaicin injection after lung hyperinflation was significantly larger than the baseline in β-glucan animals; also, the lung wet-to-dry ratio in capsaicin-injected animals was augmented in the β-glucan group. Moreover, the airway hyperresponsiveness was accompanied by increases in neutrophils in the bronchoalveolar lavage fluid in the β-glucan animals. Furthermore, the levels of substance P and the calcitonin gene-related peptide in the bronchoalveolar lavage fluid collected after capsaicin injection were increased in β-glucan animals. We provide definitive evidence that β-glucan can induce airway hyperresponsiveness in guinea pigs, and the neuropeptide releases play an important role in this airway hyperresponsiveness.

Involvement of Capsaicin-Sensitive Lung Vagal Neurons and TRPA1 Receptors in Airway Hypersensitivity Induced by 1,3-β-D-Glucan in Anesthetized Rats

Airway exposure to 1,3-β-D-glucan (β-glucan), an essential component of the cell wall of several pathogenic fungi, causes various adverse responses, such as pulmonary inflammation and airway hypersensitivity. The former response has been intensively investigated; however, the mechanism underlying β-glucan-induced airway hypersensitivity is unknown. Capsaicin-sensitive lung vagal (CSLV) afferents are very chemosensitive and stimulated by various insults to the lungs. Activation of CSLV afferents triggers several airway reflexes, such as cough. Furthermore, the sensitization of these afferents is known to contribute to the airway hypersensitivity during pulmonary inflammation. This study was carried out to determine whether β-glucan induces airway hypersensitivity and the role of the CSLV neurons in this hypersensitivity. Our results showed that the intratracheal instillation of β-glucan caused not only a distinctly irregular pattern in baseline breathing, but also induced a marked enhancement in the pulmonary chemoreflex responses to capsaicin in anesthetized, spontaneously breathing rats. The potentiating effect of β-glucan was found 45 min later and persisted at 90 min. However, β-glucan no longer caused the irregular baseline breathing and the potentiating of pulmonary chemoreflex responses after treatment with perineural capsaicin treatment that blocked the conduction of CSLV fibers. Besides, the potentiating effect of β-glucan on pulmonary chemoreflex responses was significantly attenuated by N-acetyl-L-cysteine (a ROS scavenger), HC-030031 (a TRPA1 antagonist), and Laminarin (a Dectin-1 antagonist). A combination of Laminarin and HC-030031 further reduced the β-glucan-induced effect. Indeed, our fiber activity results showed that the baseline fiber activity and the sensitivity of CSLV afferents were markedly elevated by β-glucan instillation, with a similar timeframe in anesthetized, artificially ventilated rats. Moreover, this effect was reduced by treatment with HC-030031. In isolated rat CSLV neurons, the β-glucan perfusion caused a similar pattern of potentiating effects on capsaicin-induced Ca²⁺ transients, and β-glucan-induced sensitization was abolished by Laminarin pretreatment. Furthermore, the immunofluorescence results showed that there was a co-localization of TRPV1 and Dectin-1 expression in the DiI-labeled lung vagal neurons. These results suggest that CSLV afferents play a vital role in the airway hypersensitivity elicited by airway exposure to β-glucan. The TRPA1 and Dectin-1 receptors appear to be primarily responsible for generating β-glucan-induced airway hypersensitivity.

Effect of chitosan and coagulation factors on the wound repair phenotype of bioengineered blood clots

Controlling the blood clot phenotype in a surgically prepared wound is an evolving concept in scaffold-guided tissue engineering. Here, we investigated the effect of added chitosan (80% or 95% Degree of Deacetylation, DDA) or coagulation factors (recombinant human Factor VIIa, Tissue Factor, thrombin) on inflammatory factors released by blood clots. We tested the hypothesis that 80% DDA chitosan specifically enhances leukotriene B₄ (LTB₄) production. Human or rabbit whole blood was combined with isotonic chitosan solutions, coagulation factors, or lipopolysaccharide, cultured in vitro at 37°C, and after 4hours the serum was assayed for LTB₄ or inflammatory factors. Only 80% DDA chitosan clots produced around 15-fold more LTB₄ over other clots including 95% DDA chitosan clots. All serum contained high levels of PDGF-BB and CXCL8. Normal clots produced very low type I cytokines compared to lipopolysaccharide clots, with even lower IL-6 and IL-12 and more CCL3/CCL4 produced by chitosan clots. Coagulation factors had no detectable effect on clot phenotype. Conclusion In blood clots from healthy individuals, 80% DDA chitosan has a unique influence of inducing more LTB₄, a potent neutrophil chemoattractant, with similar production of PDGF-BB and CXCL8, and lower type I cytokines, compared to whole blood clots.

Moisture damage in home associates with systemic inflammation in children

This study investigated the association between confirmed moisture damage in homes and systemic subclinical inflammation in children. Home inspections were performed in homes of 291 children at the age of 6 years. Subclinical inflammation at the age of 6 years was assessed by measuring the circulating levels of C-reactive protein (CRP) and leukocytes in peripheral blood and fractional exhaled nitric oxide (FeNO). Proinflammatory cytokines interleukin (IL)-1β and IL-6 and tumor necrosis factor (TNF)-α were measured in unstimulated, and in phorbol 12-myristate 13-acetate and ionomycin (PI), lipopolysaccharide (LPS), or peptidoglycan (PPG)-stimulated whole blood. Major moisture damage in the child's main living areas (living room, kitchen, or child's bedroom) and moisture damage with mold in the bathroom were associated with increased levels of CRP and stimulated production of several proinflammatory cytokines. There were no significant associations between moisture damage/visible mold and leukocyte or FeNO values. The results suggest that moisture damage or mold in home may be associated with increased systemic subclinical inflammation and proinflammatory cytokine responsiveness.

Fungal exposure, atopy, and asthma exacerbations in Puerto Rican children

BACKGROUND

Glucan is a component of the fungal cell wall that is used as a marker of fungal exposure. Little is known about indoor glucan, atopy, and asthma exacerbations among children living in tropical environments such as Puerto Rico. Our objective was to examine whether glucan exposure is associated with degree of atopy or visits to the emergency department (ED)/urgent care for asthma in Puerto Rican children.

METHODS

This was a cross-sectional study of 317 children aged 6 to 14 years with (cases, n = 160) and without (control subjects, n = 157) asthma in San Juan, Puerto Rico. Our primary outcomes were the number of positive skin tests to allergens (range, 0-15) and (in cases only) having had at least one visit to the ED/urgent care for asthma in the prior year. Levels of glucan, endotoxin, peptidoglycan, and five allergens (Der p 1, Bla g 2, Fel d 1, Can f 1, and Mus m 1) were measured in samples of house dust. Linear or logistic regression was used for the multivariate analysis.

MEASUREMENTS AND MAIN RESULTS

In a multivariate analysis adjusting for case-control status, mouse allergen, and other covariates, children exposed to glucan levels in the second and third quartiles had approximately two more positive skin tests than those in the lowest quartile (P < 0.01 in both instances). Among children with asthma, exposure to the highest quartile of glucan was associated with nearly ninefold greater odds of one or more visits to the ED/urgent care for asthma (95% confidence interval for adjusted odds ratio, 2.7-28.4; P < 0.001).

CONCLUSIONS

Our results suggest that indoor fungal exposure leads to an increased degree of atopy and visits to the ED/urgent care for asthma in Puerto Rican children.

Ex vivo cytokine release and pattern recognition receptor expression of subjects exposed to dampness: pilot study to assess the outcome of mould exposure to the innate immune system

In rooms with moisture damage, the indoor air can be enriched with microorganisms causing a variety of symptoms. Due to the highly diverse composition of bioaerosols and the multiple effects on humans, an assessment of the health risk is not sufficiently possible. The aim of this study was to characterize the features of innate immunity using blood from subjects exposed to moisture damage compared to control subjects living in houses without visible moisture damage. We investigated the expression of TLR-2, TLR-4 and dectin-1 on the surface of monocytes from both fresh blood and after in vitro stimulation with the model substances E. coli endotoxin, zymosan A, Pam3Cys and Aspergillus versicolor in 25 exposed subjects and 25 control subjects. In vitro stimulation of whole blood with the same components was performed for 20 h and the release of inflammatory mediators IL-8 and IL-1β were quantified. In addition to an enhanced number of blood leucocytes, the expression of the receptors TLR-2, TLR-4 and dectin-1 on blood monocytes was significantly enhanced in exposed subjects. In contrast, no different alteration in expression was detected between exposed and control group after in vitro stimulation with the model substances. The release of IL-8 and IL-1β after stimulation of whole blood with A. versicolor was increased in subjects exposed to moisture damage. Furthermore, in the exposed subjects the IL-1β release was significantly enhanced after in vitro stimulation with E. coli endotoxin (1000 pg/mL). In conclusion, features of the innate immune system (receptor expression and mediator release of monocytes) are altered in subjects exposed to moisture damage which may be a potential explanation for the increased incidence of respiratory health diseases observed in these populations.

Surface availability of beta-glucans is critical determinant of host immune response to Cladosporium cladosporioides

BACKGROUND

It is well accepted that mold exposure is a major contributor to the development of asthma, and beta-glucans are often used as a surrogate for mold exposure in the environment. Beta-glucans are an important component of mold spores and are recognized by the immune system by their receptor, Dectin-1. Cladosporium cladosporioides spores have a high beta-glucan content, but the beta-glucans are not available on the surface of live spores.

OBJECTIVE

We sought to determine whether altering the exposure of beta-glucans in C cladosporioides through heat killing could alter the immune response through binding to Dectin-1.

METHODS

In a murine model of mold-induced asthma, mice were repeatedly exposed to either live or heat-killed C cladosporioides and the phenotype was determined by the measurement of airway hyperresponsiveness, airway inflammation, and cytokine production. Pro-inflammatory cytokines from dendritic cells were measured by using quantitative PCR and ELISA.

RESULTS

Live C cladosporioides induced robust airway hyperresponsiveness, eosinophilia, and a predominately TH2 response, while heat-killed C cladosporioides induced a strong TH17 response and neutrophilic inflammation, but very mild airway hyperresponsiveness. Heat killing of C cladosporioides spores effectively exposed beta-glucans on the surface of the spores and increased binding to Dectin-1. In the absence of Dectin-1, heat-killed spores induced a predominantly TH2 response analogous to live spores. Furthermore, the production of TH17-skewing IL-6, IL-23, and TNF-α by dendritic cells in response to heat-killed C cladosporioides was dependent on Dectin-1.

CONCLUSIONS

The host immune response to C cladosporioides is dependent on the surface availability of beta-glucans rather than the total beta-glucan content.

The role of fungi in allergic diseases

Allergic diseases such as allergic rhinitis, pharyngitis, laryngitis, asthma, airborne dermatitis, or allergic conjunctivitis, can be caused or aggravated by components of bioaerosol from natural environment or from indoor environment in enclosed spaces, workplaces and homes. The main components of bioaerosol are fungi and their metabolites, which are common in the environment.

Determinants of stimulated peripheral blood cytokine production among farming women

Farming environment and environmental exposure to microbial agents have been suggested to promote favorable development of immune system in children and protect against allergic diseases. However, effects of farm exposure on adult immune responses are less clear. Aim of the present study was to examine associations of farm related factors and measured microbial exposure with stimulated production of interferon-gamma (IFN-γ) and interleukin-4 (IL-4) in peripheral blood samples among farming women. Whole peripheral blood samples were obtained from 112 women living on farms and stimulated with phorbol myristate acetate/ionomycin, lipopolysaccharide and staphylococcal enterotoxin B. Following 24h stimulation, protein levels of IFN-γ and IL-4 in the supernatants were measured by ELISA. From house dust, concentrations of 3-hydroxy fatty acids (C10:0-C14:0, marker for Gram-negative bacteria), muramic acid (Gram-positive bacteria) and ergosterol (fungal biomass) were analyzed with GC-MS/MS and viable microbes by culturing. Information on farm related factors and allergic diseases were collected from self-administered questionnaires. We found that household pets or other current or childhood farm-related factors had only few associations with stimulated cytokine production among studied farming women. Similarly, no strong associations were observed between markers of microbial exposure measured in house dust and cytokine levels. Atopic sensitization, allergic rhinitis and recent respiratory infections were, however, associated with reduced IFN-γ production. Our results suggest that the capacity of the studied environmental factors to modulate immune system is relatively weak in adulthood.

Molds and mycotoxins in indoor environments--a survey in water-damaged buildings

Mycotoxins are toxic, secondary metabolites frequently produced by molds in water-damaged indoor environments. We studied the prevalence of selected, potent mycotoxins and levels of fungal biomass in samples collected from water-damaged indoor environments in Sweden during a 1-year period. One hundred samples of building materials, 18 samples of settled dust, and 37 samples of cultured dust were analyzed for: (a) mycoflora by microscopy and culture; (b) fungal chemical marker ergosterol and hydrolysis products of macrocyclic trichothecenes and trichodermin (verrucarol and trichodermol) by gas chromatography-tandem mass spectrometry; and (c) sterigmatocystin, gliotoxin, aflatoxin B(1), and satratoxin G and H by high performance liquid chromatography-tandem mass spectrometry. Sixty-six percent of the analyzed building materials samples, 11% of the settled dust samples, and 51% of the cultured dust samples were positive for at least one of the studied mycotoxins. In addition, except in the case of gliotoxin, mycotoxin-positive building material samples contained 2-6 times more ergosterol than mycotoxin-negative samples. We show that (a) molds growing on a range of different materials indoors in water-damaged buildings generally produce mycotoxins, and (b) mycotoxin-containing particles in mold-contaminated environments may settle on surfaces above floor level. The mass spectrometry methods used in this study are valuable tools in further research to survey mycotoxin exposure and investigate potential links with health effects.

Mold exposure during infancy as a predictor of potential asthma development

BACKGROUND

Exposure to mold has been associated with exacerbation of asthma symptoms in children.

OBJECTIVE

To report how the presence of visible mold and exposure to (1-3)-beta-D-glucan in infancy affects the risk of asthma at the age of 3 years as defined by an Asthma Predictive Index (API).

METHODS

Visible mold was evaluated by means of home inspection. (1-3)-beta-D-glucan levels were measured in settled dust. Children were considered to be at high risk for asthma at later ages if they reported recurrent wheezing at the age of 3 years and met at least 1 of 3 major or 2 of 3 minor API criteria.

RESULTS

Children aged 3 years with high visible mold in the home during infancy were 7 times more likely to have a positive API than were those with no visible mold (adjusted odds ratio [aOR], 7.1; 95% confidence interval [CI], 2.2-12.6). In contrast, at low (1-3)-beta-D-glucan levels (< 22 microg/g), children were at increased risk of a positive API (aOR, 3.4; 95% CI, 0.5-23.5), whereas those with high (1-3)-beta-D-glucan levels (> 133 microg/g) were at decreased risk (aOR, 0.6; 95% CI, 0.2-1.6). Of the other covariates, mother's smoking was the strongest significant risk factor for the future development of asthma based on a positive API (aOR, 4.4; 95% CI, 1.7-11.6).

CONCLUSIONS

The presence of high visible mold and mother's smoking during infancy were the strongest risk factors for a positive API at the age of 3 years, suggesting an increased risk of asthma. High (1-3)-beta-D-glucan exposure seems to have an opposite effect on API than does visible mold.

Pulmonary Exposure to 1→3-β-Glucan Alters Adaptive Immune Responses in Rats

1 --> 3-beta-glucans have been associated with increased pulmonary inflammation in fungal-related indoor air problems. Epidemiological studies have shown a correlation between increases in T-cell proliferation and decreases in CD4+/CD8+ ratio after exposure to fungi. The objective of the present investigation was to determine the mechanisms by which 1 --> 3-beta-glucans affect immune responses using an animal model. Rats received a single dose of zymosan A (2.5 mg/kg body weight) via intratracheal instillation (IT) and were euthanized on days 1, 4, 6, 8, and 10 post IT. Bronchoalveolar lavage was performed at each time point post-IT. Inflammation and lung injury were assessed by measuring neutrophil infiltration into bronchoalveolar lavage fluid (BALF) and by measuring albumin and lactate dehydrogenase levels in BALF, respectively. Alveolar macrophage activation was determined by chemiluminescence. Immune response was characterized via immunophenotyping of bronchoalveolar lavage cells and lymphocytes isolated from the lung-associated lymph nodes. Upon challenge with zymosan, rats exhibited increased inflammation and injury at early time points (days 1 and 4) post IT exposure. Although elevations in neutrophil infiltration and chemiluminescence had returned to control levels on day 4, lymphocytes recovered from lung-associated lymph nodes continued to proliferate and reached a maximum on day 6. The CD4+/CD8+ T cell ratio from lymph nodes was lower in zymosan-treated rats than in control rats. Zymosan treatment increased tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, IL-10, and IL-12p70 secretion in BALF on day 1. In summary, rats exposed to zymosan had an increase in acute inflammation, and the altered lymphocyte profiles were consistent with the findings of epidemiology studies.

Development of a two-site enzyme immunoassay based on monoclonal antibodies to measure airborne exposure to (1-->3)-beta-D-glucan

(1-->3)-beta-D-glucan is found in cell walls of some fungi, bacteria and plants. It plays a crucial role in bioaerosol-induced inflammatory reactions. To estimate the level of airborne (1-->3)-beta-D-glucan exposure, a monoclonal antibody-based two-site enzyme immunoassay (mAb-EIA) was developed. The results obtained with the mAb-EIA were compared with the results of a Limulus amoebocyte lysate-based assay for (1-->3)-beta-D-glucan. Three mAbs produced by mouse immunization with bovine serum albumin-conjugated laminarin were enriched by in vitro production in a modular mini-fermenter and affinity purified. Two mAbs were selected for the development of a two-site EIA specific for (1-->3)-beta-D-glucan. Different polysaccharides, fungal and plant seed extracts, and airborne inhalable dust from workplaces (poultry farms, pig stables, grain storage houses, and a laboratory animal facility) were sampled with portable pumps and measured with both the mAb-EIA and Glucatell assay. Using carboxymethylated curdlan as a standard, the mAb-EIA gave a steep dose-response curve for concentrations between 0.36-15 ng/ml. The mAb-EIA was specific for (1-->3)-beta-D-glucan and was sufficiently sensitive to detect (1-->3)-beta-D-glucan in airborne dust samples. In comparing the EIA results to the values obtained with the Glucatell assay, the correlation was found to be high (coefficient of correlation r(2)=0.91), and the mean ratio of the values was 1.7. Depending on the dust source, either the Glucatell assay or the mAb-EIA gave higher results. The mAb-EIA is sensitive enough to detect (1-->3)-beta-D-glucan in airborne dust samples collected with portable pumps. Thus, the assay is suited for the investigation of the health effects induced by exposure to this class of biologically active molecules.

Microbial antigen treatment in sarcoidosis – A new paradigm?

Increasing evidence suggests that the risk for sarcoidosis is related to exposure to microbes, particularly molds. Microbial cell wall agents, even in the absence of clinical infection, could cause a late hypersensitivity reaction leading to the formation of granulomas. A few interventions studies using antimicrobial treatment demonstrate improvement in sarcoidosis. It is suggested that diagnostic tools for the presence of microbes are used in patients with sarcoidosis and that antimicrobial treatment is considered in cases resistant to corticosteroids.

The weapon potential of human pathogenic fungi

With the exception of Coccidioides spp., human pathogenic fungi are not found among lists of microbes with potential for biological warfare and bioterrorism against humans. However, many human pathogenic fungi are easily obtainable from the environment, are highly dispersible and can cause significant disease after inhalation with relatively low inocula. When the biological and pathogenic attributes of certain human pathogenic fungi are considered using a formula for calculating the relative weapon potential of a microbe it is as apparent that some organisms such as Coccidioides spp. are comparable to other microbes for which there is significant concern. Our analysis suggests that the current indifference to fungi as potential biological weapons against human populations is probably a perception engendered by their non-communicability, lack of history of use or development as biological weapons, and a relatively low incidence of symptomatic disease following natural infection. Awareness of the weapon potential of human pathogenic fungi is an important consideration for greater preparedness against the threat posed by biowarfare and bioterrorism.

Health effects of mold in children

Mold is ubiquitous, and exposure to mold and its products of metabolism is unavoidable, whether indoors or outdoors. Mold can produce a variety of adverse health outcomes by four scientifically validated pathophysiologic mechanisms: hypersensitivity, toxicity, infection, and irritation. Some adverse health outcomes have been attributed to mold for which mechanisms of injury are not well defined or are implausible. This article discusses these adverse health outcomes, focusing predominantly on those for which valid associations have been established.

The mycotoxins citrinin and gliotoxin differentially affect production of the pro-inflammatory cytokines tumour necrosis factor-alpha and interleukin-6, and the anti-inflammatory cytokine interleukin-10

BACKGROUND

Microbial growth is considered one of the major causes of indoor air problems. Moulds have been associated with asthma, allergy and a wide range of diffuse indoor air-related symptoms. However, mechanisms of the adverse health effects are not well understood.

OBJECTIVE

We hypothesized that the mycotoxins citrinin and gliotoxin could cause an imbalance between the secretion of the pro-inflammatory cytokines TNF-alpha and IL-6 and the anti-inflammatory cytokine IL-10.

METHODS

We investigated the influence of citrinin and gliotoxin on the human monocytic cell line Mono-Mac-6 (MM6) with and without lipopolysaccharide -stimulation. The levels of IL-10, IL-6 and TNF-alpha were analysed in cell culture supernatants by ELISA. Cell viability and cell apoptosis were measured by flow cytometry.

RESULTS

The strongest inhibition of cytokine secretion was found for IL-10. IL-6 levels were found to decrease in a dose-dependent manner along with reduced cell viability. TNF-alpha levels increased with low gliotoxin exposure (less than 100 ng/mL), but decreased significantly at 375 ng/mL and higher along with increased cell apoptosis and reduced cell viability. TNF-alpha levels were not reduced by citrinin exposure.

CONCLUSION

We observed a cytokine imbalance with a more pronounced reduction of IL-10 concentrations compared with those of TNF-alpha and IL-6. We suggest that low exposure doses of citrinin and gliotoxin (corresponding to less than 100 ng/mL gliotoxin and less than 10 mug/mL citrinin) may inhibit IL-10 and lead to increased risk of an inflammatory response with relative overproduction of TNF-alpha and IL-6. The findings and their clinical implications must be verified by human studies. However, we speculate that the observed biological effects may be of importance as they may partly explain the occurrence of diffuse general indoor air-related symptoms as well as the worsening of asthmatic inflammatory reactions experienced in mouldy environments.

(1-->3)-Beta-D-glucans and respiratory health: a review of the scientific evidence

(1-->3)-Beta-D-glucan are non-allergenic structural cell wall components of most fungi that have been suggested to play a causal role in the development of respiratory symptoms associated with indoor fungal exposure. This review describes the currently available epidemiological literature on health effects of (1-->3)-beta-D-glucan, focusing on atopy, airway inflammation and symptoms, asthma, and lung function. In addition to population studies, studies in human volunteers experimentally exposed to (1-->3)-beta-D-glucan are described as well as relevant animal studies. Furthermore, the review discusses exposure assessment methods, the potential for exposure control and it concludes with identifying research needs. The observational and experimental studies reviewed suggested some association between (1-->3)-beta-D-glucan exposure, airway inflammation and symptoms, however, results were mixed and specific symptoms and potential underlying inflammatory mechanisms associated with exposure could not be identified. Large observational studies using well validated exposure assessment methods are needed to further our knowledge regarding the potential health effects of indoor (1-->3)-beta-D-glucan exposure.

PRACTICAL IMPLICATIONS

The currently available epidemiological data do not permit conclusions to be drawn regarding the presence (or absence) of an association between environmental (1-->3)-beta-D-glucan exposure and specific adverse health effects, nor is it clear from the currently available evidence which specific immunological mechanisms underlie the presumed health effects. More and larger observational studies are needed to asses whether (1-->3)-beta-D-glucan exposure plays a significant role in respiratory morbidity. In addition, existing methods to assess environmental (1-->3)-beta-D-glucan exposure require validation and further development before they can be used routinely in large scale epidemiological studies.

Working Group report 1: tools for the diagnosis of organic dusts-induced disease

This paper describes the outcomes of the discussion of Working Group 1. The tasks of the workgroup were to: i) review current methods for the clinical diagnosis of organic dust induced disease, and ii) suggest how further research in this field should proceed. The working group proceeded on the paradigm that for diagnosis specific and precise tests are needed, where outcomes can be related to the risk for disease. The different methods available for the investigation of individuals and groups exposed to organic dusts are summed and graded according to scientific or diagnostic values. Many of the tools should be used in experimental research only, but can be used diagnostically for evaluation during follow up of patients when treated or removed from exposure. These techniques may also be employed for investigations of outbreaks, however, only after comparison with a proper control group. Future research should focus on associations between markers of inflammation and symptoms or clinical outcomes and dose-response relationships both for short-term and long-term health effects.