Importance of mold allergy in asthma

Hurricane María drives increased indoor proliferation of filamentous fungi in San Juan, Puerto Rico: a two-year culture-based approach

Extensive flooding caused by Hurricane María in Puerto Rico (PR) created favorable conditions for indoor growth of filamentous fungi. These conditions represent a public health concern as contamination by environmental fungi is associated with a higher prevalence of inflammatory respiratory conditions. This work compares culturable fungal spore communities present in homes that sustained water damage after Hurricane María to those present in dry, non-flooded homes. We collected air samples from 50 houses in a neighborhood in San Juan, PR, 12 and 22 months after Hurricane María. Self-reported data was used to classify the homes as flooded, water-damage or dry non-flooded. Fungi abundances, composition and diversity were analyzed by culturing on two media. Our results showed no significant differences in indoor fungal concentrations (CFU/m3) one year after the Hurricane in both culture media studied (MEA and G25N). During the second sampling period fungal levels were 2.7 times higher in previously flooded homes (Median = 758) when compared to dry homes (Median = 283), (p-value < 0.005). Fungal profiles showed enrichment of Aspergillus species inside flooded homes compared to outdoor samples during the first sampling period (FDR-adjusted p-value = 0.05). In contrast, 22 months after the storm, indoor fungal composition consisted primarily of non-sporulated fungi, most likely basidiospores, which are characteristic of the outdoor air in PR. Together, this data highlights that homes that suffered water damage not only have higher indoor proliferation of filamentous fungi, but their indoor fungal populations change over time following the Hurricane. Ultimately, after nearly two years, indoor and outdoor fungal communities converged in this sample of naturally ventilated homes.

Allergy to Fungi in Veterinary Medicine: Alternaria, Dermatophytes and Malassezia Pay the Bill!

The fungal kingdom comprises ubiquitous forms of life with 1.5 billion years, mostly phytopathogenic and commensals for humans and animals. However, in the presence of immune disorders, fungi may cause disease by intoxicating, infecting or sensitizing with allergy. Species from the genera Alternaria, Aspergillus and Malassezia, as well as dermatophytes from the genera Microsporum, Trichophyton and Epidermophyton, are the most commonly implicated in veterinary medicine. Alternaria and Malassezia stand as the most commonly associated with either allergy or infection in animals, immediately followed by Aspergillus, while dermatophytes are usually associated with the ringworm skin infection. By aiming at the relevance of fungi in veterinary allergy it was concluded that further research is still needed, especially in the veterinary field.

Fungi and Atopy

Atopy and fungi have a long associative history. Fungal spores were among the first substances to which humans were noted to be sensitized. Humans contact fungal spores in the outdoor, indoor, and occupational environments. As organisms, fungi have their own kingdom and are found in all environmental niches on earth. Currently, fungal exposure in the indoor environment especially related to wet housing conditions is of particular concern. Sensitization rates to fungi typically exceed 5% of the general public with higher rates among the atopic population. Alternaria is the best studied of the allergic fungi; however, cross sensitization to multiple fungi is well documented. Recent advances in understanding mechanisms of the innate immune system are beginning to explain why the fungal atopy relationship is unique and why fungal sensitivity seems to extend to many non-atopic individuals. Evidence has been accumulated that indicates fungal allergen exposure can be via intact spores as well as spore and mycelial fragments. Germinating spores produce a different and often increased allergen picture. Much evidence has been developed through animal studies that extends the mechanisms surrounding long-term low-level fungal exposure. However, it should be emphasized that the presence of fungi in the air does not necessarily equate with illness. Indeed, in the absence of an atopic individual and/or a significant immune response against fungi, there is little evidence suggesting pathology. Allergists frequently deal with patients who have concerns about indoor fungal exposure and respiratory disease in those patients with an allergic response.

Association of molds and metrological parameters to frequency of severe asthma exacerbation

Background

Sensitization to airborne molds may be a risk factor for severe asthma and direct cause of asthma exacerbation (AE).

Methods

A prospective, 1-year (April 2016-March 2017) study, done in Kuwait Allergy Centre, investigated the link between AEs with exposure to outdoor molds and the role of meteorological parameters in mold sensitized patients and compared with non-allergic asthma patients who had asthma deterioration. The total of 676 adult asthmatics with moderate-severe AEs were included and divided into atopic (85.65%) and non-atopic group. Atopy was defined by positive skin prick test (SPT) to at least one inhalant allergen. Data regarding atopy and asthma severity were collected from patient's records. Patients with symptoms and signs of acute respiratory infection and patient sensitized to indoor allergens only were excluded. Daily count of local pollens (Salsola kali, Bermuda grass) and molds (Aspergillus, Alternaria and Cladosporium) were obtained from the Aerobiology department. Daily metrological parameters (atmospheric pressure-AP, temperature-T and relative humidity-RH) were provided by Kuwait Environment Public Authority. Count of spores/m³ and weather variable are shown on weekly basis. The year circle was divided into 4 Seasons (1, 2, 3, 4) accordingly to typical desert climate.

Results

Sensitization to molds was relatively high but significantly less (25.0%) if compared to the pollens sensitization. The highest number of AEs was in season 4 for both molds and pollens sensitized patients. Seasonal patterns for both allergens were significant and positively correlated with RH and AP. In season 1 only, mold sensitized patients showed higher rate of AEs. Non-atopic patients have been less sensitive to increased RH than atopic. Negative correlation with T was similar in both atopic and non-atopic patients.

Conclusion

Despite of high rate of sensitization to molds, their significant role in triggering AE was not found in desert environment. Typical desert climate and high allergencity of local weeds outweigh the influence of the molds.

Relationship between mold exposure, specific IgE sensitization, and clinical asthma: A case-control study

BACKGROUND

Most of the findings related to the noxious effect of mold sensitization on asthma come from investigations based on Alternaria alternata, Cladosporium herbarum, and Aspergillus fumigatus. However, species such as Penicillium spp, Cladosporium sphaerospermum, Cladosporium cladosporioides, or Aspergillus versicolor display a more pronounced indoor tropism, and their potential harmful respiratory effects cannot be neglected.

OBJECTIVE

The goal of this work was to relate mold sensitizations with asthma severity and with the level of indoor mold contamination among mold-sensitized patients with asthma and nonsensitized patients with asthma.

METHODS

A case-control study was conducted and several asthma severity markers were compared between patients with asthma with and without mold sensitization. Indoor contamination of patients' dwellings was also investigated.

RESULTS

Our findings confirmed the association between sensitization to A fumigatus and severity for patients with asthma in contrast with sensitization to other species. Indoor mold contamination was detected in approximately 90% of dwellings. Overall mold exposure was not associated with asthma severity. However, regardless of the sensitization, exposure to A fumigatus and Penicillium spp in dust was linked to an increased risk of severe asthma.

CONCLUSION

The harmful nature of mold sensitization and mold exposure for patients with asthma was not confirmed in this study. However, sensitization to A fumigatus was associated with an increased risk for severe asthma. A better investigation of the properties of Penicillium spp is recommended because its exposure was found to be associated with a more pronounced impairment of lung function.

Investigation of inflammatory and allergic responses to common mold species: Results from in vitro experiments, from a mouse model of asthma, and from a group of asthmatic patients

Most studies on molds focus on Alternaria alternata and Aspergillus fumigatus. Here, we report on inflammatory and allergenic properties of more typical indoor species Aspergillus versicolor, P. chrysogenum, C. cladosporioïdes, and C. sphaerospermum that were compared to A. alternata and A. fumigatus. In a mouse model, after intranasal instillation, A. alternaria, A. versicolor, and C. sphaerospermum induced the early recruitment of neutrophils and the strong expression of inflammatory markers in the bronchoalveolar lavages fluids. A. fumigatus also induced the early accumulation of neutrophils but with lower levels of inflammatory markers. Chronic treatment induced variable response according to species: P. chrysogenum and A. fumigatus appeared strong pro-allergenic inducers compared to A. alternata and C. sphaerospermum while A. versicolor and C. cladosporioides induced a mixed pro-allergenic/pro-inflammatory response. In mold-sensitized asthmatics, mold-specific Immunoglobulin E (IgE) were detected with an in-house dot-blot assay. A. fumigatus and A. alternata were the most frequent sensitizers. Altogether, P. chrysogenum, P. brevicompactum, C. sphaerospermum, and C. cladosporïoides were the "major sensitizer" (defined as the strongest response against a single mold species) for almost 30% of the asthmatics. These results show that, not only A. alternata and A. fumigatus, but also indoor species have strong inflammatory and allergic properties and a harmful potency.

The infant gut bacterial microbiota and risk of pediatric asthma and allergic diseases

Among the many areas being revolutionized by the recent introduction of culture-independent microbial identification techniques is investigation of the relationship between close contact with large animals, antibiotics, breast feeding, mode of birth, and other exposures during infancy as related to a reduced risk of asthma and allergic disease. These exposures were originally clustered under the "Hygiene Hypothesis" which has evolved into the "Microbiota Hypothesis". This review begins by summarizing epidemiologic studies suggesting that the common feature of these allergy risk-related exposures is their influence on the founding and early development of a child's gut microbiota. Next, studies using culture-independent techniques are presented showing that children who have experienced the exposures of interest have altered gut microbiota. Finally, selected mouse and human studies are presented which begin to corroborate the protective exposures identified in epidemiologic studies by elucidating mechanisms through which microbes can alter immune development and function. These microbially driven immune alterations demonstrate that microbial exposures in many cases could alter the risk of subsequent allergic disease and asthma. Hopefully, a better understanding of how microbes influence allergic disease will lead to safe and effective methods for reducing the prevalence of all forms of allergic disease.

Fungal spores and pollen in particulate matter collected during agricultural activities in the Po Valley (Italy)

Airborne particulate matter (PM) containing fungal spores and pollen grains was sampled within a monitoring campaign of wheat threshing, plowing and sowing agricultural operations. Fungal spores and pollen grains were detected and identified on morphological basis. No studies were previously available about fungal spore and pollen content in agricultural PM in the Po Valley. Sampling was conducted in a Po Valley farmland in Mezzano (Ferrara, Italy). The organic particles collected were examined by scanning electron microscopy with energy dispersive X-ray spectrometer. Fungal spores and pollen grains were identified when possible at the level of species. The most frequent components of the organic particles sampled were spores of Aspergillus sp., which could represent a risk of developing allergies and aspergillosis for crop farmers.

Residential culturable fungi, (1-3, 1-6)-β-d-glucan, and ergosterol concentrations in dust are not associated with asthma, rhinitis, or eczema diagnoses in children

Qualitative reporting of home indoor moisture problems predicts respiratory diseases. However, causal agents underlying such qualitative markers remain unknown. In the homes of 198 multiple allergic case children and 202 controls in Sweden, we cultivated culturable fungi by directly plating dust, and quantified (1-3, 1-6)-β-D-glucan and ergosterol in dust samples from the child's bedroom. We examined the relationship between these fungal agents and degree of parent or inspector-reported home indoor dampness, and microbiological laboratory's mold index. We also compared the concentrations of these agents between multiple allergic cases and healthy controls, as well as IgE-sensitization among cases. The concentrations of culturable fungal agents were comparable between houses with parent and inspector-reported mold issues and those without. There were no differences in concentrations of the individual or the total summed culturable fungi, (1-3, 1-6)-β-D-glucan, and ergosterol between the controls and the multiple allergic case children, or individual diagnosis of asthma, rhinitis, or eczema. Culturable fungi, (1-3, 1-6)-β-D-glucan, and ergosterol in dust were not associated with qualitative markers of indoor dampness or mold or indoor humidity. Furthermore, these agents in dust samples were not associated with any health outcomes in the children.

Domestic airborne pollutants and asthma and respiratory symptoms in middle age

BACKGROUND AND OBJECTIVE

The role of indoor air pollution as a risk factor for asthma and respiratory symptoms in middle age is unclear. We investigated associations between indoor air pollution sources and (i) asthma phenotypes and (ii) asthma-related respiratory symptoms in middle-aged adults.

METHODS

Subjects (n = 5729) who participated in the 2004 survey of the Tasmanian Longitudinal Health Study completed respiratory and home environment questionnaires. Associations between indoor air pollution sources, and asthma phenotypes and asthma-related respiratory symptoms were estimated.

RESULTS

Recent mould in the home was associated with current asthma (odds ratio (OR) 1.26; 95% confidence interval 1.06-1.50), wheeze (OR 1.34; 1.17-1.54) and nocturnal chest tightness (OR 1.30; 1.12-1.51). Stratified by atopy and gender, recent mould was associated with current non-atopic asthma only in males (OR 3.73; 1.29-10.80). More rooms affected by mould were associated with significant trends for current asthma, wheeze and nocturnal chest tightness. Home environmental tobacco smoke was associated with doctor-diagnosed asthma (OR 1.25; 1.02-1.53), wheeze (OR 1.69; 1.41-2.03), nocturnal chest tightness (OR 1.54; 1.26-1.88), with current asthma only in non-smokers (OR 2.09; 95%: 1.30-3.35) and with current asthma only in males (OR 1.74; 95%: 1.25-2.42). Among heating appliances, reverse cycle air conditioning was negatively associated with doctor-diagnosed asthma (OR 0.84; 0.70-1.00). Neither electric nor gas stove use was associated with either asthma phenotype or with asthma-related respiratory symptoms.

CONCLUSIONS

In middle age, reducing home exposure to mould and environmental tobacco smoke might reduce asthma and asthma-related respiratory symptoms.

Wheeze in infancy: protection associated with yeasts in house dust contrasts with increased risk associated with yeasts in indoor air and other fungal taxa

BACKGROUND

While fungal exposures are assumed to provoke wheeze through irritant or allergenic mechanisms, little is known about the differential effects of indoor and outdoor fungi on early-life wheeze.

METHODS

In a Boston prospective birth cohort of 499 at-risk infants, culturable fungi in bedroom air and dust and outdoor air were measured at the age of 2-3 months. Wheeze was determined using bimonthly telephone questionnaires. Odds ratios were estimated for an interquartile increase in fungal natural log-transformed concentrations, adjusting for predictors of wheeze and potential confounders.

RESULTS

Increased odds of 'any wheeze' (≥1 vs 0 episodes) by age one were positively associated with indoor dust Alternaria [odds ratio (OR) = 1.83; 95% confidence interval (CI), 1.07-3.14], Penicillium [OR = 1.18; (0.98-1.43)], and Cladosporium [OR = 1.47; (1.16-1.85)]; indoor air Penicillium [OR = 1.26; (0.92-1.74)]; and outdoor air Cladosporium [OR = 1.68; (1.04-2.72)]. In contrast, indoor dust yeasts were protective [OR = 0.78; (0.66-0.93)]. 'Frequent wheeze' (≥2 vs <2 episodes) by age one was borderline associated with dust yeasts [OR = 0.86; (0.70-1.04)] and indoor air yeasts [OR = 1.53; (0.93-2.53)]. Alternaria concentration was associated with any wheeze for children with maternal mold sensitization [OR = 9.16; (1.37-61.22)], but not for those without maternal mold sensitization [OR = 1.32; (0.79-2.20)].

CONCLUSIONS

While wheeze rates were higher with exposures to fungal taxa considered to be irritant or allergenic in sensitive subjects, yeasts in the home had a strong protective association with wheeze in infancy. Molecular microbiologic studies may elucidate specific components of innate microbiologic stimulants that lead to contrasting effects on wheeze development.

Asthma associations in children attending a museum of science

We explored the relative strength of environmental and social factors associated with pediatric asthma in middle class families and considered the efficacy of recruitment for an educational study at a science museum. Eligibility criteria were having a child aged 4-12 and English fluency. Our questionnaire included information on demographics, home environment, medical history, and environmental toxicant exposures. Statistically significant associations were found for: child's age (t = -2.46; p = 0.014), allergies (OR = 11.5; 95%CI = 5.9-22.5), maternal asthma (OR = 2.2; 95%CI = 1.2-3.9), parents' education level (OR = 0.5; 95%CI = 0.3-0.9), family income (OR = 2.4; 95%CI = 1.1-5.5), water damage at home (OR = 2.5; 95%CI = 1.1-5.5), stuffed animals in bedroom (OR = 0.4; 95%CI = 0.2-0.7), hospitalization within a week after birth (OR = 3.2; 95%CI = 1.4-7.0), diagnosis of pneumonia (OR = 2.8; 95%CI = 1.4-5.9), and multiple colds in a year (OR = 2.9; 95%CI = 1.5-5.7). Several other associations approached statistical significance, including African American race (OR = 3.3; 95%CI = 1.0-10.7), vitamin D supplement directive (OR = 0.2; 95%CI = 0.02-1.2), mice in the home (OR = 0.5, 95%CI = 0.2-1.1), and cockroaches in the home (OR = 4.3; CI = 0.8-21.6). In logistic regression, age, parents' education, allergies, mold allergies, hospitalization after birth, stuffed animals in the bedroom, vitamin D supplement directive, and water damage in the home were all significant independent predictors of asthma. The urban science museum was a low-resource approach to address the relative importance of risk factors in this population.

Improving pediatrician knowledge about environmental triggers of asthma

BACKGROUND

Control of environmental triggers (ETs) greatly improves asthma outcomes in children. Disseminating these findings to general pediatricians has not been well established.

METHODS

After delivering a structured and standardized presentation on ET identification and control to pediatricians, we surveyed them about knowledge and practices of ET assessment and management. We analyzed matched responses for pre/post and 3- to 6-month follow-up using McNemar's χ(2) test.

RESULTS

Matched data were available for 367 participants, and 3- to 6-month follow-up data were available for 83. There was a significant posttraining increase in intention to ask about ETs and recommend ET management. After 3 to 6 months, all responses remained significantly higher than baseline, except "likely to refer to an asthma specialist."

CONCLUSION

Pediatricians reported a significant improvement in knowledge about ETs of asthma and a willingness to incorporate exposure history questions and remediation recommendations in their routine practice.

Identity of the fungal species present in the homes of asthmatic children

BACKGROUND

Fungal exposures are believed to play an important role in the development of asthma and atopy, accounting for increased asthmatic symptoms and severe asthma exacerbation. Indoor fungal species vary both in taxa and concentration in different residences and in different regions.

OBJECTIVES

We explored the fungal species spectrum in 88 homes with at least one asthmatic child in the Middle West region of the United States mostly during late spring and fall season in comparison with 85 homes that did not contain an asthmatic child during flu season.

METHODS

The average fungal spore counts per cubic metre of air in the bedroom of the enrolled child, the main living spaces and outdoor environments, and the culturable fungal colony-forming units per cubic metre of air samples in the main living space from each home were measured.

RESULTS

The results indicated that Cladosporium, Penicillium, Aspergillus, Basidiospores, Epicoccum and Pithomyces were found in more asthmatic homes than in homes without an asthmatic child or existed in higher concentration in asthmatic homes than in homes without an asthmatic child even after adjusting outdoor spore concentration. The results for culturable fungal species confirmed most of these findings even after adjusting for seasonal factors. Although Alternaria was commonly found in both kinds of homes, there was no significant difference in detection rate or concentration of Alternaria between asthmatic homes and homes without an asthmatic child by either spore counting or culturable airborne detection.

CONCLUSION AND CLINICAL RELEVANCE

Since many allergens have been identified in these fungal species, identifying and controlling these fungal species in asthmatic homes might be expected to improve asthma care and benefit asthmatic children.

Occurrence of household mold and efficacy of sodium hypochlorite disinfectant

The occurrence and distribution of mold on household surfaces and the efficacy of bleach-based (sodium hypochlorite, NaOCl) disinfectants on mold viability and allergenicity was documented. Household microenvironments prone to increased moisture were specifically targeted. Using the sticky tape method, 1330 samples were collected from non-porous indoor surfaces of 160 homes across the United States, and analyzed for mold. Homes were randomly selected and recruited via phone interviews. Culture and immunoassays were used to measure the viability and reduction of allergenic properties of Aspergillus fumigatus following 2.4% NaOCl treatment. All homes and 72.9% of surfaces tested positive for mold. Windowsills were the most frequently contaminated site (87.5%) and Cladosporium the most commonly identified mold (31.0%). Five-minute exposures to 2.4% NaOCl resulted in a >3 to >6-log₁₀ reduction of culturable mold counts in controlled laboratory studies. Organisms were nonculturable after 5- and 10-min contact times on non-porous and porous ceramic carriers, respectively, and A. fumigatus spore-eluted allergen levels were reduced by an average 95.8% in 30 sec, as indicated by immunoassay. All homes are contaminated with some level of mold, and regrowth is likely in moisture-prone microenvironments. The use of low concentrations (2.4%) of NaOCl for the reduction of culturable indoor mold and related allergens is effective and recommended.

Efficacy of sublingual specific immunotherapy in patients with respiratory allergy to Alternaria alternata: a randomised, assessor-blinded, patient-reported outcome, controlled 3-year trial

BACKGROUND

Alternaria alternata (AA) sensitisation is a common cause of respiratory allergies such as rhinitis and asthma. So far there are no controlled double-blind trials evaluating the efficacy and safety of specific sublingual immunotherapy (SLIT) in AA allergies.

OBJECTIVE

To evaluate the efficacy of SLIT treatment in terms of clinical improvement and rescue medication usage in patients with confirmed AA respiratory allergy.

SUBJECTS AND METHODS

A randomised, parallel group study in 52 subjects was conducted (32 men, mean age 20 ± 9 years) with clinically- and laboratory-confirmed AA respiratory allergies (allergic rhinitis with or without mild-to-moderate asthma). Patients were randomly assigned to SLIT treatment (SLITone Alternaria, ALK-Abellò, Denmark) one vial per day without up-dosing for 3 consecutive years (n = 34) or to a control group (n = 18) with a random allocation ratio of 2:1. Clinical improvement was assessed by evaluating patient-reported outcome (PRO) using a 6 cm visual analogue scale (0: extreme worsening; 3: no change; 6: extreme improvement). The VAS score was evaluated every year with an intra- and inter-group comparison. Rescue medication score (MS) was assessed by evaluating symptomatic drug consumption.

RESULTS

After 3 years the VAS score was 4.7 ± 0.8 in the SLIT group and 2 ± 1.6 in the control group (p = 0.0002). Clinical improvement was observed in 33 out of 34 subjects in the SLIT group (97%) and in 5 out of 18 in the control group (27%) (p = 0.0001; Fisher's exact test). The MS significantly (p = 0.0001) decreased in the SLIT group from 4.3 to 1.7 at the end of 3 years' treatment. In the control group MS increased from 3.4 to 4.0 by the end of the trial. No serious adverse events were observed in the either group. Six patients in the SLIT group (17%) reported side-effects, in general mild and transient. One patient prematurely discontinued the treatment due to gastrointestinal discomfort.

CONCLUSION

The current study has shown that a 3-year course of SLIT is efficacious and well-tolerated in subjects with AA respiratory allergies.

Gene expression profiling and network analysis of peripheral blood monocytes in a chronic model of allergic asthma

The Aspergillus fumigatus mouse model of asthma mimics the characteristics of human fungal asthma, including local and systemic inflammation. Monocyte/macrophage lineage cells direct innate immune responses and guide adaptive responses. To identify gene expression changes in peripheral blood monocytes in the context of fungal allergy, mice were exposed to systemic and intranasal inoculations of fungal antigen (sensitized), and naïve and sensitized animals were challenged intratracheally with live A. fumigatus conidia. Microarray analysis of blood monocytes from allergic versus non-allergic mice showed ≥ twofold modulation of 45 genes. Ingenuity pathway analysis revealed a network of these genes involved in antigen presentation, inflammation, and immune cell trafficking. These data show that allergen sensitization and challenge affects gene expression in peripheral monocytes.

Murine models of airway fungal exposure and allergic sensitization

Inhalation of common indoor filamentous fungi has been associated with the induction or exacerbation of allergic respiratory disease. The understanding of fungal inhalation and allergic sensitization has significantly advanced with the use of small animal models, especially mouse models. Numerous studies have employed different animal exposure and sensitization techniques, each with inherent advantages and disadvantages that are addressed in this review. In addition, most studies involve exposure of animals to fungal spores or spore extracts while neglecting the influence of hyphal or subcellular fragment exposures. Recent literature examining the potential for hyphae and fungal fragments to induce or exacerbate allergy is discussed. Innate immune recognition of fungal elements and their contribution to lung allergic inflammation in animal models are also reviewed. Though physical properties of fungi play an important role following exposure, host immune development is also critical in airway inflammation and allergy. We discuss the importance of environmental factors that influence early immune development and subsequent susceptibility to allergy. Murine studies that examine the role of intestinal microflora and prenatal or early life environmental factors that promote allergic sensitization are also evaluated. Future studies will require animal models that accurately reflect natural fungal exposures and identify environmental factors that influence immune development and thus promote respiratory fungal allergy and disease.

Elevated atmospheric carbon dioxide concentrations amplify Alternaria alternata sporulation and total antigen production

BACKGROUND

Although the effect of elevated carbon dioxide (CO2) concentration on pollen production has been established in some plant species, impacts on fungal sporulation and antigen production have not been elucidated.

OBJECTIVE

Our purpose was to examine the effects of rising atmospheric CO2 concentrations on the quantity and quality of fungal spores produced on timothy (Phleum pratense) leaves.

METHODS

Timothy plants were grown at four CO2 concentrations (300, 400, 500, and 600 micromol/mol). Leaves were used as growth substrate for Alternaria alternata and Cladosporium phlei. The spore abundance produced by both fungi, as well as the size (microscopy) and antigenic protein content (ELISA) of A. alternata, were quantified.

RESULTS

Leaf carbon-to-nitrogen ratio was greater at 500 and 600 micromol/mol, and leaf biomass was greater at 600 micromol/mol than at the lower CO2 concentrations. Leaf carbon-to-nitrogen ratio was positively correlated with A. alternata spore production per gram of leaf but negatively correlated with antigenic protein content per spore. At 500 and 600 micromol/mol CO2 concentrations, A. alternata produced nearly three times the number of spores and more than twice the total antigenic protein per plant than at lower concentrations. C. phlei spore production was positively correlated with leaf carbon-to-nitrogen ratio, but overall spore production was much lower than in A. alternata, and total per-plant production did not vary among CO2 concentrations.

CONCLUSIONS

Elevated CO2 concentrations often increase plant leaf biomass and carbon-to-nitrogen ratio. Here we demonstrate for the first time that these leaf changes are associated with increased spore production by A. alternata, a ubiquitous allergenic fungus. This response may contribute to the increasing prevalence of allergies and asthma.

Culturable mold in indoor air and its association with moisture-related problems and asthma and allergy among Swedish children

In a nested case-control study with 198 children with asthmatic and allergic symptoms (cases) and 202 healthy controls in Värmland, Sweden, we have investigated the relationship between mold spore exposure (mean colony-forming unit) indoor and (i) different indexes of moldy odor indoor (observed by professional inspectors and reported by parents), (ii) visible signs of dampness in the homes of the children (observed and reported), and (iii) doctor-diagnosed asthma/allergy in children. No association was found between the spore concentration indoor and moldy odor and signs of visible dampness in the homes. When a semi-quantitative method in distinguishing between moldy houses or non-moldy houses was used, there were no significant differences between the observed indexes of moldy odor or visible signs of dampness (both observed and reported). No association could be found between the spore concentration in indoor air and asthma/allergy in the children.

PRACTICAL IMPLICATIONS

Mold spore exposure indoor have been suggested as a possible explanation for airway problems such as asthma and allergy among people living in buildings with moisture-related problems. However, this investigation could not find any associations between the spore concentrations in indoor air and signs of dampness and moldy odor reported by parents or observed by professional inspectors. Neither was there any association between the indoor spore concentration and asthma/allergy among children. With these results, there is no reason for one-time air sampling of mold colony-forming unit (CFU) in indoor air of homes to identify risk factors for asthma/allergy in children living in Scandinavian countries.

An inhalation model of airway allergic response to inhalation of environmental Aspergillus fumigatus conidia in sensitized BALB/c mice

Fungal exposure may elicit a number of pulmonary diseases in man, including allergic asthma. Fungal sensitization is linked to asthma severity, although the basis for this increased pathology remains ambiguous. To create conditions simulating environmental fungal allergen exposure in a human, nose-only inhalation delivery of Aspergillus fumigatus conidia was employed in mice previously sensitized to Aspergillus antigen extract. BALB/c mice were immunized with subcutaneous and intraperitoneal injections of soluble A. fumigatus extract in alum, which was followed by three intranasal inoculations of the same fungal antigens dissolved in saline to elicit global sensitization in a manner similar to other published models. The animals were then challenged with a 10-min inhaled dose of live conidia blown directly from the surface of a mature A. fumigatus culture. After a single challenge with inhaled A. fumigatus conidia, allergic pulmonary inflammation and airway hyperresponsiveness were significantly increased above that of either naïve animals or animals that had been sensitized to A. fumigatus antigens but not challenged with conidia. The architecture of the lung was changed by inhalation of conidia when compared to controls in that there were significant increases in epithelial thickness, goblet cell metaplasia, and peribronchial collagen deposition. Additionally, α-smooth muscle actin staining of histological sections showed visual evidence of increased peribronchial smooth muscle mass after fungal challenge. In summary, the delivery of live A. fumigatus conidia to the sensitized airways of BALB/c mice advances the study of the pulmonary response to fungi by providing a more natural route of exposure and, for the first time, demonstrates the consistent development of fibrosis and smooth muscle changes accompanying exposure to inhaled fungal conidia in a mouse model.

New-onset adult asthma in relation to damp and moldy workplaces

OBJECTIVE

Damp and moldy indoor environments aggravate pre-existing asthma. Recent meta-analyses suggest that exposure to such environments may also induce new-onset asthma. We assessed the probability of molds being the cause of asthma in a patient series examined because of respiratory symptoms in relation to workplace dampness and molds.

METHODS

Altogether 694 such patients had been clinically assessed between 1995 and 2004. According to their histories, they had all been exposed to molds at work and had suffered from work-related lower respiratory symptoms. The investigations had included specific inhalation challenge (SIC) tests with mold extracts and serial peak expiratory flow (PEF) recordings. Using internationally recommended diagnostic criteria for occupational asthma (OA), we categorized the patients into three groups: probable, possible, and unlikely OA (156, 45, and 475 patients, respectively). The clinical details of 258 patients were analyzed, and their levels of microbial exposure were evaluated.

RESULTS

The agreement between the serial PEF recordings and SIC tests (both being either positive or negative) was 56%. In the group of probable OA, mold sensitization was found in 20%. The level of exposure and sensitization to molds was associated with probable OA. At 6 months, the follow-up examinations of 136 patients with probable OA showed that the symptoms were persistent, and no improvement in spirometry was noted despite adequate treatment. Only 58% of the patients had returned to work.

CONCLUSIONS

Exposure to damp and moldy workplaces can induce new-onset adult asthma. IgE mediation is a rare mechanism, whereas other mechanisms are unknown.

Home and school environmental assessment and remediation

Children spend a considerable portion of their time indoors. Therefore, homes and schools are an important source of allergen exposure. Chronic exposure to the major indoor allergens can lead to allergic sensitization and provoke allergic symptoms in children. Environmental assessment is crucial for the identification and quantification of such allergens in indoor spaces. Reduction of allergen exposure below sensitization and symptom thresholds is possible with various remediation techniques. This article reviews and discusses evidence for the assessment and remediation of indoor allergens commonly found in homes and schools. A literature review was performed using the PubMed database for English-language articles published between January 1, 1980, and February 2009. Additional information was obtained from a review of recent textbooks and one professional society's webpage.

Do obese adults have a higher risk of asthma attack when exposed to indoor mold? A study based on the 2005 Behavioral Risk Factor Surveillance System

OBJECTIVE

Some studies show an association between asthma and obesity, but it is unknown whether exposure to mold will increase the risk of asthma attacks among obese people. This study examined whether obese adults have a higher risk of asthma attacks than non-obese adults when exposed to indoor mold.

METHODS

We used data from the 2005 Behavioral Risk Factor Surveillance System to conduct a cross-sectional analysis among 9,668 respondents who reported exposure to indoor mold.

RESULTS

With exposure to indoor mold, weighted prevalence of asthma attacks among obese respondents was 11.4% (95% confidence interval [CI] 6.0, 20.6], which was 2.3 times as high as among the exposed non-obese respondents (5.0%, 95% CI 2.8, 8.8). This ratio was almost the same as the ratio of 2.0:1 between the obese respondents (5.7%, 95% CI 4.6, 7.2) and the non-obese respondents (2.8%, 95% CI 2.3, 3.9) when neither group had exposure to mold. The odds ratio of asthma attack among obese people was 3.10 (95% CI 1.10, 8.67) for those with exposure to mold and 2.21 (95% CI 1.54, 3.17) for those without exposure to mold after adjusting for age, sex, race/ethnicity, and smoking status.

CONCLUSION

Our study suggests that obese adults who have been exposed to indoor mold may not necessarily have a higher risk of asthma attack than obese adults who have not been exposed, even though obesity and exposure to indoor mold are both major risk factors for asthma attack. Medical professionals should not only incorporate weight-control or weight-reduction measures as the components of asthma treatment plans, but also advise asthma patients to avoid exposure to indoor mold.

Th2 allergic immune response to inhaled fungal antigens is modulated by TLR-4-independent bacterial products

Allergic airway disease is characterized by eosinophilic inflammation, mucus hypersecretion and increased airway resistance. Fungal antigens are ubiquitous within the environment and are well known triggers of allergic disease. Bacterial products are also frequently encountered within the environment and may alter the immune response to certain antigens. The consequence of simultaneous exposure to bacterial and fungal products on the lung adaptive immune response has not been explored. Here, we show that oropharyngeal aspiration of fungal lysates (Candida albicans, Aspergillus fumigatus) promotes airway eosinophilia, secretion of Th2 cytokines and mucus cell metaplasia. In contrast, oropharyngeal exposure to bacterial lysates (Pseudomonas aeruginosa) promotes airway inflammation characterized by neutrophils, Th1 cytokine secretion and no mucus production. More importantly, administration of bacterial lysates together with fungal lysates deviates the adaptive immune response to a Th1 type associated with neutrophilia and diminished mucus production. The immunomodulatory effect that bacterial lysates have on the response to fungi is TLR4 independent but MyD88 dependent. Thus, different types of microbial products within the airway can alter the host's adaptive immune response and potentially impact the development of allergic airway disease to environmental fungal antigens.