Production of proinflammatory mediators by indoor air bacteria and fungal spores in mouse and human cell lines

Identification of environmental Actinobacteria in buildings by means of chemotaxonomy, 16S rRNA sequencing, and MALDI-TOF MS

Actinobacteria are abundant in soil and other environmental ecosystems and are also an important part of the human microbiota. Hence, they can also be detected in indoor environments and on building materials, where actinobacterial proliferation on damp materials can indicate moisture damage. The aim of this study was to evaluate the matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for the identification of 28 environmental strains of Actinobacteria isolated from building materials and indoor and outdoor air samples, mainly collected in the context of moisture damage investigations in buildings in Finland. The 16S rRNA gene sequencing and chemotaxonomic analyses were performed, and results were compared with the MALDI-TOF MS Biotyper identification. Using 16S rRNA gene sequencing, all isolates were identified on the species or genus level and were representatives of Streptomyces, Nocardia, and Pseudonocardia genera. Based on MALDI-TOF MS analysis, initially, 11 isolates were identified as Streptomyces spp. and 1 as Nocardia carnea with a high identification score. After an upgrade in the MALDI-TOF MS in-house database and re-evaluation of mass spectra, 13 additional isolates were identified as Nocardia, Pseudonocardia, and Streptomyces. MALDI-TOF MS has the potential in environmental strain identification; however, the standard database needs to be considerably enriched by environmental Actinobacteria representatives.

IMPORTANCE

The manuscript addresses the challenges in identifying environmental bacteria using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) Biotyper-based protein profiling. The matter of the studies-actinobacterial strains-has been isolated mostly from building materials that originated from a confirmed moisture-damaged situation. Polyphasic taxonomy, 16S RNA gene sequencing, and MALDI-TOF mass spectrometry were applied for identification purposes. In this experimental paper, a few important facts are highlighted. First, Actinobacteria are abundant in the natural as well as built environment, and their identification on the species and genus levels is difficult and time-consuming. Second, MALDI-TOF MS is an effective tool for identifying bacterial environmental strains, and in parallel, continuous enrichment of the proteomics mass spectral databases is necessary for proper identification. Third, the chemical approach aids in the taxonomical inquiry of Actinobacteria environmental strains.

Indoor microbial exposure increases complement component C3a and C-reactive protein concentrations in serum

Indoor exposure to microbial growth, caused by moisture damage, has been an established health risk for several decades. It is likely that a damp indoor environment contains biological pollutants that trigger both the innate and adaptive branches of the immune system. In this study, we investigated the association between moisture damage related microbial exposure and serum C3a, C5a and CRP concentrations in Finnish adults. Serum C3a and CRP concentrations were elevated in individuals exposed to moisture damage and microbial growth in an indoor air environment. The elevated concentrations may be due to environmental factors present in moisture-damaged buildings. Complement activation and the resulting proinflammatory cleavage products may be a driving factor in inflammatory responses following exposure to indoor moisture damage and related microbial growth.

Streptomyces albireticuli lung infection managed as a pulmonary air cyst: a case report and literature review

Streptomyces, the largest genus in the Streptomycetaceae family and a prolific producer of antibacterial drugs, is a saprophytic soil organism that rarely causes invasive infections. Here we report a case of necrotic pneumonia caused by Streptomyces albireticuli in a 75-year-old man who presented with progressive chest tightness and dyspnea. Streptomyces albireticuli was isolated from his bronchoalveolar lavage fluid and identified through whole-genome sequencing (WGS) and phylogenetic analysis. The patient responded satisfactorily to clarithromycin therapy. The findings of this study may enhance our vigilance in identifying visceral infections caused by Streptomyces.

Indoor PM2.5 from occupied residences in Sweden caused higher inflammation in mice compared to outdoor PM2.5

We spend most of our time indoors; however, little is known about the effects of exposure to aerosol particles indoors. We aimed to determine differences in relative toxicity and physicochemical properties of PM_2.5 collected simultaneously indoors (PM_{2.5 INDOOR} ) and outdoors (PM_{2.5 OUTDOOR} ) in 15 occupied homes in southern Sweden. Collected particles were extracted from filters, pooled (indoor and outdoor separately), and characterized for chemical composition and endotoxins before being tested for toxicity in mice via intratracheal instillation. Various endpoints including lung inflammation, genotoxicity, and acute-phase response in lung and liver were assessed 1, 3, and 28 days post-exposure. Chemical composition of particles used in toxicological assessment was compared to particles analyzed without extraction. Time-resolved particle mass and number concentrations were monitored. PM_{2.5 INDOOR} showed higher relative concentrations (μg mg^-1 ) of metals, PAHs, and endotoxins compared to PM_{2.5 OUTDOOR} . These differences may be linked to PM_{2.5 INDOOR} causing significantly higher lung inflammation and lung acute-phase response 1 day post-exposure compared to PM_{2.5 OUTDOOR} and vehicle controls, respectively. None of the tested materials caused genotoxicity. PM_{2.5 INDOOR} displayed higher relative toxicity than PM_{2.5 OUTDOOR} under the studied conditions, that is, wintertime with reduced air exchange rates, high influence of indoor sources, and relatively low outdoor concentrations of PM. Reducing PM_{2.5 INDOOR} exposure requires reduction of both infiltration from outdoors and indoor-generated particles.

Toxicological transcriptome of human airway constructs after exposure to indoor air particulate matter: In search of relevant pathways of moisture damage-associated health effects

BACKGROUND

Multiple health effects are associated with moisture damage in buildings. Studies explaining these associations and cell-level mechanisms behind the observed health effects are urgently called for.

OBJECTIVES

We focused on characterizing gene expression in human airway epithelium after exposure to indoor air particulate matter (PM) sampled from houses with and without moisture damage, alongside determination of general toxicological markers.

METHODS

We performed detailed technical building inspections in 25 residential houses and categorized them based on the detection of moisture damages and the probability of occupant exposure. PM sampling was complemented by microbiological and volatile organic compound assessment. We exposed human airway constructs to three dilutions (1:16, 1:8, 1:4) of collected PM from moisture-damaged (index) and non-moisture-damaged (reference) houses and imaged selected constructs with electron microscopy. We analyzed general toxicological markers and the RNA of exposed constructs was sequenced targeting genes associated with toxicological pathways. We did groupwise comparisons between index and reference houses and pairwise comparisons in matched index/reference houses.

RESULTS

In groupwise comparison, gene Cytochrome P450 Family 1 Subfamily A Member 1 (CYP1A1) was statistically significantly over-expressed in index houses at all dilutions of collected PM and Nuclear Factor Kappa B Subunit 1 (NFKB1) at dilution 1:4 of collected PM. In pairwise index/reference house comparison, several genes related to multiple toxicological pathways were activated, largest expression differences seen for CYP1A1. However, none of the genes was consistently expressed in all the matched pairs, and general toxicological markers did not differentiate index and reference houses.

DISCUSSION

The exposure to PM from index houses activated toxicology -related genes in airway constructs. Differential expression was not consistent among all the index/reference pairs, possibly due to compositional differences of bioactive particles. Our study highlights CYP1A1 and NFKB1 as potential targets in moisture damage -associated cellular responses.

Early age exposure to moisture and mould is related to FeNO at the age of 6 years

BACKGROUND

Exposure to indoor moisture damage and visible mold has been found to be associated with asthma and respiratory symptoms in several questionnaire-based studies by self-report. We aimed to define the prospective association between the early life exposure to residential moisture damage or mold and fractional exhaled nitric oxide (FeNO) and lung function parameters as objective markers for airway inflammation and asthma in 6-year-old children.

METHODS

Home inspections were performed in children's homes when infants were on average 5 months old. At age 6 years, data on FeNO (n = 322) as well as lung function (n = 216) measurements were collected. Logistic regression and generalized additive models were used for statistical analyses.

RESULTS

Early age major moisture damage and moisture damage or mold in the child's main living areas were significantly associated with increased FeNO levels (>75th percentile) at the age of 6 years (adjusted odds ratios, 95% confidence intervals, aOR (95% CI): 3.10 (1.35-7.07) and 3.16 (1.43-6.98), respectively. Effects were more pronounced in those who did not change residential address throughout the study period. For lung function, major structural damage within the whole home was associated with reduced FEV1 and FVC, but not with FEV1/FVC. No association with lung function was observed with early moisture damage or mold in the child's main living areas.

CONCLUSION

These results underline the importance of prevention and remediation efforts of moisture and mold-damaged buildings in order to avoid harmful effects within the vulnerable phase of the infants and children's immunologic development.

The Genome Analysis of the Human Lung-Associated Streptomyces sp. TR1341 Revealed the Presence of Beneficial Genes for Opportunistic Colonization of Human Tissues

Streptomyces sp. TR1341 was isolated from the sputum of a man with a history of lung and kidney tuberculosis, recurrent respiratory infections, and COPD. It produces secondary metabolites associated with cytotoxicity and immune response modulation. In this study, we complement our previous results by identifying the genetic features associated with the production of these secondary metabolites and other characteristics that could benefit the strain during its colonization of human tissues (virulence factors, modification of the host immune response, or the production of siderophores). We performed a comparative phylogenetic analysis to identify the genetic features that are shared by environmental isolates and human respiratory pathogens. The results showed a high genomic similarity of Streptomyces sp. TR1341 to the plant-associated Streptomyces sp. endophyte_N2, inferring a soil origin of the strain. Putative virulence genes, such as mammalian cell entry (mce) genes were not detected in the TR1341's genome. The presence of a type VII secretion system, distinct from the ones found in Mycobacterium species, suggests a different colonization strategy than the one used by other actinomycete lung pathogens. We identified a higher diversity of genes related to iron acquisition and demonstrated that the strain produces ferrioxamine B in vitro. These results indicate that TR1341 may have an advantage in colonizing environments that are low in iron, such as human tissue.

A cohort study of cucumber greenhouse workers' exposure to microorganisms as measured using NGS and MALDI-TOF MS and biomarkers of systemic inflammation

Work in greenhouses entails exposure to airborne fungi and bacteria. The aims of this study are to obtain knowledge about whether exposure to fungal and bacterial genera and species during work in a cucumber greenhouse is affected by work tasks, and whether a cohort of greenhouse workers' serum levels of serum amyloid A (SAA) and C-reactive protein (CRP), biomarkers of systemic inflammation, are associated with this. Data on personal exposure to airborne fungal and bacterial species measured over 4 years as well as serum levels of SAA and CRP sampled over two years were analyzed. For data analysis, the main work tasks were grouped into three different groups, called 'grouped work task'. Microorganisms were identified using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF MS) and next-generation sequencing (NGS). The 'daily exposure' of greenhouse workers' were as follows: 4.8 × 10⁴ CFU bacteria/m³, 1.4 × 10⁶ CFU fungi/m³, and 392 EU/m³ of endotoxin. Workers were exposed to many different microbial species including several species within the genera Acinetobacter, Bacillus, Microbacterium, Pseudomonas, Staphylococcus, and Streptomyces. The genera Ralstonia and Cladosporium were found in most samples. The exposure levels as well as the microbial composition were associated significantly with grouped work task and season with high exposures during tasks in close contact with mature and old plants and in the autumn. CRP and SAA levels were also associated with exposure level and grouped work tasks. The Shannon-Wiener indices were not different in the 3 'grouped work tasks'. Several specific species including e.g. Halomonas elongata, Stenotrophomonas maltophilia, Podosphaera fusca, and Wallemia spp. were found frequently or in high concentrations in the exposures associated with the highest levels of CRP and SAA. The microorganisms S. maltophilia, P. fusca, and Wallemia spp. were also found on the cucumber plant leaves. In conclusion, both exposure level and the species composition seem to have an effect on the serum levels of CRP and SAA of exposed workers. The greenhouse workers were exposed to only a few species characterized as human pathogens.

Assessment of Children’s Potential Exposure to Bioburden in Indoor Environments

The exposure to particles and bioaerosols has been associated with the increase in health effects in children. The objective of this study was to assess the indoor exposure to bioburden in the indoor microenvironments more frequented by children. Air particulate matter (PM) and settled dust were sampled in 33 dwellings and four schools with a medium volume sampler and with a passive method using electrostatic dust collectors (EDC), respectively. Settled dust collected by EDC was analyzed by culture-based methods (including azole resistance profile) and using qPCR. Results showed that the PM2.5 and PM10 concentrations in classrooms (31.15 μg/m3 and 57.83 μg/m3, respectively) were higher than in homes (15.26 μg/m3 and 18.95 μg/m3, respectively) and highly exceeded the limit values established by the Portuguese legislation for indoor air quality. The fungal species most commonly found in bedrooms was Penicillium sp. (91.79%), whereas, in living rooms, it was Rhizopus sp. (37.95%). Aspergillus sections with toxigenic potential were found in bedrooms and living rooms and were able to grow on VOR. Although not correlated with PM, EDC provided information regarding the bioburden. Future studies, applying EDC coupled with PM assessment, should be implemented to allow for a long-term integrated sample of organic dust.

Strong variance in the inflammatory and cytotoxic potentials of Penicillium and Aspergillus species from cleaning workers' exposure in nursing homes

Penicillium and Aspergillus are among the dominant genera of fungi in many environments. Exposure to these fungi may cause inflammation-related health effects, however the knowledge about this at species level is limited. The aim of this study was to obtain knowledge about cleaning workers' exposure to fungi and to investigate the total inflammatory potential (TIP) and the cytotoxic potential of fungal species. The fungi were obtained from the personal exposure of cleaning workers' in five nursing homes. In total 271 fungal isolates were identified using MALDI-TOF MS. The TIP and cytotoxic potential were determined for 30 different fungal isolates covering 17 species in an in vitro assay by exposing HL-60 cells to the fungal spores of each isolate. The geometric mean exposure of the cleaning workers was 351 CFU fungi/m³ air. We showed that the TIP and cytotoxicity varied among both species and isolates. At the two lowest doses, there was a positive relationship between spore concentration and TIP. The species with highest TIPs were A. candidus and P. italicum, while the most cytotoxic ones were A. niger and A. fumigatus. There was no obvious relationship between the TIP of an isolate and its cytotoxicity. The results of this study provide a better understanding of the inflammatory potential and cytotoxicity of different environmental fungal species and contribute to the risk evaluation of exposure to different Penicillium and Aspergillus species.

Characterization and pro-inflammatory potential of indoor mold particles

A number of epidemiological studies find an association between indoor air dampness and respiratory health effects. This is often suggested to be linked to enhanced mold growth. However, the role of mold is obviously difficult to disentangle from other dampness-related exposure including microbes as well as non-biological particles and chemical pollutants. The association may partly be due to visible mycelial growth and a characteristic musty smell of mold. Thus, the potential role of mold exposure should be further explored by evaluating information from experimental studies elucidating possible mechanistic links. Such studies show that exposure to spores and hyphal fragments may act as allergens and pro-inflammatory mediators and that they may damage airways by the production of toxins, enzymes, and volatile organic compounds. In the present review, we hypothesize that continuous exposure to mold particles may result in chronic low-grade pro-inflammatory responses contributing to respiratory diseases. We summarize some of the main methods for detection and characterization of fungal aerosols and highlight in vitro research elucidating how molds may induce toxicity and pro-inflammatory reactions in human cell models relevant for airway exposure. Data suggest that the fraction of fungal hyphal fragments in indoor air is much higher than that of airborne spores, and the hyphal fragments often have a higher pro-inflammatory potential. Thus, hyphal fragments of prevalent mold species with strong pro-inflammatory potential may be particularly relevant candidates for respiratory diseases associated with damp/mold-contaminated indoor air. Future studies linking of indoor air dampness with health effects should assess the toxicity and pro-inflammatory potential of indoor air particulate matter and combined this information with a better characterization of biological components including hyphal fragments from both pathogenic and non-pathogenic mold species. Such studies may increase our understanding of the potential role of mold exposure.

Towards a risk evaluation of workers' exposure to handborne and airborne microbial species as exemplified with waste collection workers

Bioaerosol exposure is associated with health problems. The aim of this study is to evaluate whether it is possible to assess the risks posed by waste collection workers' exposure through identification and characterization of bacterial and fungal species, to which the workers are exposed. Using MALDI-TOF MS, microorganisms in waste collection workers' exposure through air, hand, and contact with the steering wheel were identified. Fungi found in high concentrations from the workers' exposure were characterized for the total inflammatory potential (TIP), cytotoxicity, and biofilm-forming capacity. In total, 180 different bacterial and 37 different fungal species in the workers' exposure samples were identified. Some of them belong to Risk Group 2, e.g. Escherichia coli, Klebsiella oxytoca, Staphylococcus aureus, and Aspergillus fumigatus, some have been associated with occupational health problems e.g. Penicillium citrinum and P. glabrum and some are described as emerging pathogens e.g. Aureobasidium pullulans. The TIP of fungal species was dose-dependent. High TIP values were found for Penicillium italicum, P. brevicompactum, P. citrinum, and P. glabrum. Several species were cytotoxic, e.g. A. niger and P. expansum, while some, e.g. P. chrysogenum, did not affect the cell viability. Based on waste workers' average inhalation rate, they inhaled up to 2.3 × 10⁴ cfu of A. niger, 7.4 × 10⁴ cfu of P. expansum, and 4.0 × 10⁶ cfu of P. italicum per work day. Some species e.g. A. niger and P. citrinum were able to form biofilm. In conclusion, the workers were exposed to several species of microorganisms of which some to varying degrees can be evaluated concerning risk. Thus, some microorganisms belong to Risk Group 2, and some are described as causing agents of occupational health problems, emerging pathogens, or intrinsically antibiotic resistant. For some other species very little is known. The TIP, cytotoxicity, and ability to form biofilm of the dominating fungi support and expand previous findings. These parameters depended on the species and the dose, thus highlighting the importance of species identification and exposure level in the risk assessment of exposure.

A Human Lung-Associated Streptomyces sp. TR1341 Produces Various Secondary Metabolites Responsible for Virulence, Cytotoxicity and Modulation of Immune Response

Streptomycetes, typical soil dwellers, can be detected as common colonizers of human bodies, especially the skin, the respiratory tract, the guts and the genital tract using molecular techniques. However, their clinical manifestations and isolations are rare. Recently they were discussed as possible "coaches" of the human immune system in connection with certain immune disorders and cancer. This work aimed for the characterization and evaluation of genetic adaptations of a human-associated strain Streptomyces sp. TR1341. The strain was isolated from sputum of a senior male patient with a history of lung and kidney TB, recurrent respiratory infections and COPD. It manifested remarkably broad biological activities (antibacterial, antifungal, beta-hemolytic, etc.). We found that, by producing specific secondary metabolites, it is able to modulate host immune responses and the niche itself, which increase its chances for long-term survival in the human tissue. The work shows possible adaptations or predispositions of formerly soil microorganism to survive in human tissue successfully. The strain produces two structural groups of cytotoxic compounds: 28-carbon cytolytic polyenes of the filipin type and actinomycin X2. Additionally, we summarize and present data about streptomycete-related human infections known so far.

Pro-inflammatory responses induced by A. fumigatus and A. versicolor in various human macrophage models

Exposure to mold-contaminated indoor air has been associated with various respiratory diseases, and there is a need for experimental data to confirm these associations. The pro-inflammatory properties of well-characterized aerosolized spores and hyphal fragments from Aspergillus fumigatus and Aspergillus versicolor were examined and compared using various human macrophage cell models including phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1 macrophages (THP-1 Ma), primary peripheral blood monocyte-derived macrophages (MDM), and primary airway macrophages (AM) from induced sputum. X-ray treated samples of the two mold species induced different responses with A. fumigatus displaying the most potent induction of pro-inflammatory responses. While hyphal fragments from A. fumigatus were more potent than spores, similar responses were produced by the two growth stages of A. versicolor. THP-1 Ma was the most sensitive model releasing a broad range of cytokines/chemokines. MDM exhibited a similar cytokine/chemokine profile as THP-1 Ma, except for a low-quantity release of interleukin-1β (IL-1β). In contrast, AM appeared to be nonresponsive and yielded a different pattern of pro-inflammatory markers. Toll-like receptor (TLR)4, but also to a certain degree TLR2, was involved in several responses induced by spores and aerosolized hyphal fragments of A. fumigatus in MDM. Taken together, MDM seems to be the most promising experimental macrophage model. Abbreviations: AF: A. fumigatus, Aspergillus fumigatus; AV: A. versicolor, Aspergillus versicolor; AM: Airway Macrophage; CBA: Cytometric Bead Array; CD: Cluster of Differentiation; DTT: dithiothreitol; ELISA: Enzyme Linked Immunosorbent Assay; FBS: fetal bovine serum; GM-CSF: Granulocyte macrophage colony-stimulating factor; IL-1β: Interleukin-1beta; MDM: Monocyte-Derived Macrophages; NF-κB: Nuclear Factor kappa light chain enhancer of activated B cells; NLR: NOD-like Receptor; PAMP: Pathogen Associated Molecular Pattern; PMA: Phorbol 12-myristate 13-acetate; PRR: Pattern Recognition Receptor; THP-1: Human leukemia monocyte cell line; TLR: Toll-like Receptor; TNF-α: Tumor Necrosis Factor- alpha.

AnIn VitroStudy of the Toxic Effects ofStachybotrys chartarumMetabolites on Lung Cells

During a study of indoor fungal colonisation, several isolates of Stachybotrys chartarum were recovered, and the effects of metabolites from four isolates on lung epithelial Type II cells and alveolar macrophages were studied in vitro. All the isolates showed toxic effects on both cell types, and they differed only in the extent of the changes induced. In Type II cells, the number of alkaline phosphatase positive cells was reduced, the pattern of Maclura pomifera agglutinin (MPA) binding was changed, and acid phosphatase activity in alveolar macrophages was diminished. In both cell types, the production of monocyte chemotactic protein-1 (MCP-1) and tumour necrosis factor-alpha (TNF-alpha) was changed, and parameters related to antioxidant status (superoxide dismutase, glutathione peroxidase, glutathione) were decreased.

Pro-Inflammatory Responses in Human Bronchial Epithelial Cells Induced by Spores and Hyphal Fragments of Common Damp Indoor Molds

Damp indoor environments contaminated with different mold species may contribute to the development and exacerbation of respiratory illnesses. Human bronchial epithelial BEAS-2B cells were exposed to X-ray treated spores and hyphal fragments from pure cultures of Aspergillus fumigatus, Penicillum chrysogenum, Aspergillus versicolor and Stachybotrys chartarum. Hyphal fragments of A. fumigatus and P. chrysogenum induced expression and release of the pro-inflammatory cytokine interleukin (IL)-6 and the chemokine IL-8, while none of the other hyphal preparations had effects. Hyphal fragments from A. fumigatus and P. chrysogenum also increased the expression of IL-1α, IL-1β and tumor necrosis factor (TNF)-α, but these cytokines were not released. X-ray treated spores had little or no inflammatory potential. Attenuating Toll-like receptor (TLR)-2 by blocking antibodies strongly reduced the A. fumigatus and P. chrysogenum hyphae-induced IL-6 and IL-8 release, whereas TLR4 antagonist treatment was without effects. Untreated A. fumigatus spores formed hyphae and triggered expression of pro-inflammatory genes with similarities to the effects of hyphal fragments. In conclusion, while X-ray treated spores induced no pro-inflammatory responses, hyphal fragments of A. fumigatus and P. chrysogenum enhanced a TLR2-dependent expression and release of IL-6 and IL-8.

Early age exposure to moisture damage and systemic inflammation at the age of 6 years

Cross-sectional studies have shown that exposure to indoor moisture damage and mold may be associated with subclinical inflammation. Our aim was to determine whether early age exposure to moisture damage or mold is prospectively associated with subclinical systemic inflammation or with immune responsiveness in later childhood. Home inspections were performed in children's homes in the first year of life. At age 6 years, subclinical systemic inflammation was measured by serum C-reactive protein (CRP) and blood leukocytes and immune responsiveness by ex vivo production of interleukin 1-beta (IL-1β), IL-6, and tumor necrosis factor alpha (TNF-α) in whole blood cultures without stimulation or after 24 hours stimulation with phorbol 12-myristate 13-acetate and ionomycin (PI), lipopolysaccharide (LPS), or peptidoglycan (PPG) in 251-270 children. Moisture damage in child's main living areas in infancy was not significantly associated with elevated levels of CRP or leukocytes at 6 years. In contrast, there was some suggestion for an effect on immune responsiveness, as moisture damage with visible mold was positively associated with LPS-stimulated production of TNF-α and minor moisture damage was inversely associated with PI-stimulated IL-1β. While early life exposure to mold damage may have some influence on later immune responsiveness, it does not seem to increase subclinical systemic inflammation in later life.

Characterization and pro-inflammatory responses of spore and hyphae samples from various mold species

Mold particles from Aspergillus fumigatus, Penicillium chrysogenum, Aspergillus versicolor, and Stachybotrys chartarum have been linked to respiratory-related diseases. We characterized X-ray-inactivated spores and hyphae fragments from these species by number of particles, morphology, and mycotoxin, β-glucan and protease content/activity. The pro-inflammatory properties of mold particles were examined in human bronchial epithelial cells (BEAS-2B) and THP-1 monocytes and phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1. Spores from P. chrysogenum and S. chartarum contained some hyphae fragments, whereas the other preparations contained either spores or hyphae. Each mold species produced mainly one gelatin-degrading protease that was either of the metallo- or serine type, while one remains unclassified. Mycotoxin levels were generally low. Detectable levels of β-glucans were found mainly in hyphae particle preparations. PMA-differentiated THP-1 macrophages were by far the most sensitive model with effects in the order of 10 ng/cm² . Hyphae preparations of A. fumigatus and P. chrysogenum were more potent than respective spore preparations, whereas the opposite seems to be true for A. versicolor and S. chartarum. Hyphae fragments of A. fumigatus, P. chrysogenum, and A. versicolor enhanced the release of metalloprotease (proMMP-9) most markedly. In conclusion, species, growth stage, and characteristics are all important factors for pro-inflammatory potential.

Bacteria in a water-damaged building: associations of actinomycetes and non-tuberculous mycobacteria with respiratory health in occupants

We examined microbial correlates of health outcomes in building occupants with a sarcoidosis cluster and excess asthma. We offered employees a questionnaire and pulmonary function testing and collected floor dust and liquid/sludge from drain tubing traps of heat pumps that were analyzed for various microbial agents. Forty-nine percent of participants reported any symptom reflecting possible granulomatous disease (shortness of breath on exertion, flu-like achiness, or fever and chills) weekly in the last 4 weeks. In multivariate regressions, thermophilic actinomycetes (median = 529 CFU/m² ) in dust were associated with FEV₁ /FVC [coefficient = -2.8 per interquartile range change, P = 0.02], percent predicted FEF_25-75% (coefficient = -12.9, P = 0.01), and any granulomatous disease-like symptom [odds ratio (OR) = 3.1, 95% confidence interval (CI) = 1.45-6.73]. Mycobacteria (median = 658 CFU/m² ) were positively associated with asthma symptoms (OR = 1.5, 95% CI = 0.97-2.43). Composite score (median = 11.5) of total bacteria from heat pumps was negatively associated with asthma (0.8, 0.71-1.00) and positively associated with FEV₁ /FVC (coefficient = 0.44, P = 0.095). Endotoxin (median score = 12.0) was negatively associated with two or more granulomatous disease-like symptoms (OR = 0.8, 95% CI = 0.67-0.98) and asthma (0.8, 0.67-0.96). Fungi or (1→3)-β-D-glucan in dust or heat pump traps was not associated with any health outcomes. Thermophilic actinomycetes and non-tuberculous mycobacteria may have played a role in the occupants' respiratory outcomes in this water-damaged building.

Inflammatory potential in relation to the microbial content of settled dust samples collected from moisture-damaged and reference schools: results of HITEA study

Aiming to identify factors causing the adverse health effects associated with moisture-damaged indoor environments, we analyzed immunotoxicological potential of settled dust from moisture-damaged and reference schools in relation to their microbiological composition. Mouse RAW264.7 macrophages were exposed to settled dust samples (n = 25) collected from moisture-damaged and reference schools in Spain, the Netherlands, and Finland. After exposure, we analyzed production of inflammatory markers [nitric oxide (NO), tumor necrosis factor-α (TNF-)α, interleukin (IL)-6, and macrophage inflammatory protein (MIP)2] as well as mitochondrial activity, viability, apoptosis, and cell cycle arrest. Furthermore, particle counts, concentration of selected microbial groups as well as chemical markers such as ergosterol, 3-hydroxy fatty acids, muramic acid, endotoxins, and glucans were measured as markers of exposure. Dust from moisture-damaged schools in Spain and the Netherlands induced stronger immunotoxicological responses compared to samples from reference schools; the responses to Finnish samples were generally lower with no difference between the schools. In multivariate analysis, IL-6 and apoptosis responses were most strongly associated with moisture status of the school. The measured responses correlated with several microbial markers and numbers of particles, but the most important predictor of the immunotoxicological potential of settled dust was muramic acid concentration, a marker of Gram-positive bacteria.

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.

Microbial communities associated with house dust

House dust is a complex mixture of inorganic and organic material with microbes in abundance. Few microbial species are actually able to grow and proliferate in dust and only if enough moisture is provided. Hence, most of the microbial content originates from sources other than the dust itself. The most important sources of microbes in house dust are outdoor air and other outdoor material tracked into the buildings, occupants of the buildings including pets and microbial growth on moist construction materials. Based on numerous cultivation studies, Penicillium, Aspergillus, Cladosporium, and about 20 other fungal genera are the most commonly isolated genera from house dust. The cultivable bacterial flora is dominated by Gram-positive genera, such as Staplylococcus, Corynebacterium, and Lactococcus. Culture-independent studies have shown that both the fungal and the bacterial flora are far more diverse, with estimates of up to 500-1000 different species being present in house dust. Concentrations of microbes in house dust vary from nondetectable to 10(9) cells g(-1) dust, depending on the dust type, detection method, type of the indoor environment and season, among other factors. Microbial assemblages in different house dust types usually share the same core species; however, alterations in the composition are caused by differing sources of microbes for different dust types. For example, mattress dust is dominated by species originating from the user of the mattress, whereas floor dust reflects rather outdoor sources. Farming homes contain higher microbial load than urban homes and according to a recent study, temperate climate zones show higher dust microbial diversity than tropical zones.

Environmental mold and mycotoxin exposures elicit specific cytokine and chemokine responses

Background

Molds can cause respiratory symptoms and asthma. We sought to use isolated peripheral blood mononuclear cells (PBMCs) to understand changes in cytokine and chemokine levels in response to mold and mycotoxin exposures and to link these levels with respiratory symptoms in humans. We did this by utilizing an ex vivo assay approach to differentiate mold-exposed patients and unexposed controls. While circulating plasma chemokine and cytokine levels from these two groups might be similar, we hypothesized that by challenging their isolated white blood cells with mold or mold extracts, we would see a differential chemokine and cytokine release.

Methods and Findings

Peripheral blood mononuclear cells (PBMCs) were isolated from blood from 33 patients with a history of mold exposures and from 17 controls. Cultured PBMCs were incubated with the most prominent Stachybotrys chartarum mycotoxin, satratoxin G, or with aqueous mold extract, ionomycin, or media, each with or without PMA. Additional PBMCs were exposed to spores of Aspergillus niger, Cladosporium herbarum and Penicillium chrysogenum. After 18 hours, cytokines and chemokines released into the culture medium were measured by multiplex assay. Clinical histories, physical examinations and pulmonary function tests were also conducted. After ex vivo PBMC exposures to molds or mycotoxins, the chemokine and cytokine profiles from patients with a history of mold exposure were significantly different from those of unexposed controls. In contrast, biomarker profiles from cells exposed to media alone showed no difference between the patients and controls.

Conclusions

These findings demonstrate that chronic mold exposures induced changes in inflammatory and immune system responses to specific mold and mycotoxin challenges. These responses can differentiate mold-exposed patients from unexposed controls. This strategy may be a powerful approach to document immune system responsiveness to molds and other inflammation-inducing environmental agents.

An innate immune system-mimicking, real-time biosensing of infectious bacteria

An immune system-mimicking real-time biosensing could detect bacteria (<100 CFU mL⁻¹) automatically within the working time.

Role of microbial and chemical composition in toxicological properties of indoor and outdoor air particulate matter

Background

Ambient air particulate matter (PM) is increasingly considered to be a causal factor evoking severe adverse health effects. People spend the majority of their time indoors, which should be taken into account especially in future risk assessments, when the role of outdoor air particles transported into indoor air is considered. Therefore, there is an urgent need for characterization of possible sources seasonally for harmful health outcomes both indoors and outdoors.

Methods

In this study, we collected size-segregated (PM_10–2.5, PM_2.5–0.2) particulate samples with a high volume cascade impactor (HVCI) simultaneously both indoors and outdoors of a new single family detached house at four different seasons. The chemical composition of the samples was analyzed as was the presence of microbes. Mouse macrophages were exposed to PM samples for 24 hours. Thereafter, the levels of the proinflammatory cytokines, NO-production, cytotoxicity and changes in the cell cycle were investigated. The putative sources of the most toxic groups of constituents were resolved by using the principal component analysis (PCA) and pairwise dependencies of the variables were detected with Spearman correlation.

Results

Source-related toxicological responses clearly varied according to season. The role of outdoor sources in indoor air quality was significant only in the warm seasons and the significance of outdoor microbes was also larger in the indoor air. During wintertime, the role of indoor sources of the particles was more significant, as was also the case for microbes. With respect to the outdoor sources, soil-derived particles during a road dust episode and local wood combustion in wintertime were the most important factors inducing toxicological responses.

Conclusions

Even though there were clear seasonal differences in the abilities of indoor and outdoor air to induce inflammatory and cytotoxic responses, there were relatively small differences in the chemical composition of the particles responsible of those effects. Outdoor sources have only a limited effect on indoor air quality in a newly built house with a modern ventilation system at least in a low air pollution environment. The most important sources for adverse health related toxicological effects were related to soil-derived constituents, local combustion emissions and microbes.

Electronic supplementary material

The online version of this article (doi:10.1186/s12989-014-0060-6) contains supplementary material, which is available to authorized users.

Murine model of Bacillus cereus gastrointestinal infection

Bacillus cereus is a spore-forming micro-organism responsible for foodborne illness. In this study, we focus on the host response following intragastric challenge with a pathogenic B. cereus strain (B10502) isolated from a foodborne outbreak. C57BL/6J female mice were infected by gavage with strain B10502. Controls were administered with PBS. Infection leads to significant modification in relevant immune cells in the spleen, Peyer's patches (PP) and mesenteric lymph nodes (MLN). These findings correlated with an increase in the size of PP as compared with uninfected controls. Histological studies showed that B. cereus infection increased the ratio of intestinal goblet cells and induces mononuclear cell infiltrates in spleen at 5 days post-infection. Evaluation of cytokine mRNA expression demonstrated a significant increase in IFN-γ in MLN after 2 days of infection. The present work demonstrates that infection of mice with vegetative B. cereus is self-limited. Our findings determined relevant cell populations that were involved in the control of the pathogen through modification of the ratio and/or activation.

In vitro inflammation inhibition model based on semi-continuous toll-like receptor biosensing

A chemical inhibition model of inflammation is proposed by semi-continuous monitoring the density of toll-like receptor 1 (TLR1) expressed on mammalian cells following bacterial infection to investigate an in vivo-mimicked drug screening system. The inflammation was induced by adding bacterial lysate (e.g., Pseudomonas aeruginosa) to a mammalian cell culture (e.g., A549 cell line). The TLR1 density on the same cells was immunochemically monitored up to three cycles under optimized cyclic bacterial stimulation-and-restoration conditions. The assay was carried out by adopting a cell-compatible immunoanalytical procedure and signal generation method. Signal intensity relative to the background control obtained without stimulation was employed to plot the standard curve for inflammation. To suppress the inflammatory response, sodium salicylate, which inhibits nuclear factor-κB activity, was used to prepare the standard curve for anti-inflammation. Such measurement of differential TLR densities was used as a biosensing approach discriminating the anti-inflammatory substance from the non-effector, which was simulated by using caffeic acid phenethyl ester and acetaminophen as the two components, respectively. As the same cells exposed to repetitive bacterial stimulation were semi-continuously monitored, the efficacy and toxicity of the inhibitors may further be determined regarding persistency against time. Therefore, this semi-continuous biosensing model could be appropriate as a substitute for animal-based experimentation during drug screening prior to pre-clinical tests.

Chemiluminometric immuno-analysis of innate immune response against repetitive bacterial stimulations for the same mammalian cells

For monitoring of human cellular response to repetitive bacterial stimulations (e.g., Pseudomonas aeruginosa in a lysate form), we devised a chemiluminescent immuno-analytical system for toll-like receptor 1 (TLR1) as marker present on cell surfaces (e.g., A549). Upon stimulation, TLR1 recognizes pathogen-associated molecular patterns of the infectious agent and are then up-regulated via activation of the nuclear factor-κB (NF-κB) pathway. In this study, the receptor density was quantified by employing an antibody specific to the target receptor and by producing a chemiluminometric signal from an enzyme labeled to the binder. The activated status was then switched back to normal down-regulated stage, by changing the culture medium to one containing animal serum. The major factors affecting activation were the stimulation dose of the bacterial lysate, stimulation timing during starvation, and up- and down-regulation time intervals. Reiterative TLR regulation switching up to three times was not affected by either antibody remained after immunoassay or enzyme substrate (e.g., hydrogen peroxide) in solution. This immuno-analysis for TLRs could be unique to acquire accumulated response of the human cells to repeated stimulations and, therefore, can eventually apply to persistency testing of the cellular regulation in screening of anti-inflammatory substances.

Stenotrophomonas, Mycobacterium, and Streptomyces in home dust and air: associations with moldiness and other home/family characteristics

Respiratory illnesses have been linked to children's exposures to water-damaged homes. Therefore, understanding the microbiome in water-damaged homes is critical to preventing these illnesses. Few studies have quantified bacterial contamination, especially specific species, in water-damaged homes. We collected air and dust samples in twenty-one low-mold homes and twenty-one high-mold homes. The concentrations of three bacteria/genera, Stenotrophomonas maltophilia, Streptomyces sp., and Mycobacterium sp., were measured in air and dust samples using quantitative PCR (QPCR). The concentrations of the bacteria measured in the air samples were not associated with any specific home characteristic based on multiple regression models. However, higher concentrations of S. maltophilia in the dust samples were associated with water damage, that is, with higher floor surface moisture and higher concentrations of moisture-related mold species. The concentrations of Streptomyces and Mycobacterium sp. had similar patterns and may be partially determined by human and animal occupants and outdoor sources of these bacteria.

Microbial content of household dust associated with exhaled NO in asthmatic children

Exhaled nitric oxide (eNO) is increasingly used as a non-invasive measure of airway inflammation. Despite this, little information exists regarding the potential effects of indoor microbial components on eNO. We determined the influence of microbial contaminants in house dust and other indoor environmental characteristics on eNO levels in seven-year-olds with and without a physician-diagnosis of asthma. The study included 158 children recruited from a birth cohort study, and 32 were physician-diagnosed as asthmatic. The relationship between eNO levels and exposures to home dust streptomycetes, endotoxin, and molds was investigated. Streptomycetes and endotoxin were analyzed both as loads and concentrations in separate models. Dog, cat, and dust mite allergens also were evaluated. In the multivariate exposure models, high streptomycetes loads and concentrations were significantly associated with a decrease in eNO levels in asthmatic (p<0.001) but not in healthy children. The presence of dog allergen, however, was associated with increased levels of eNO (p=0.001). Dust endotoxin was not significant. The relationship between eNO and indoor exposure to common outdoor molds was u-shaped. In non-asthmatic children, none of the exposure variables was significantly associated with eNO levels. To our knowledge, this is the first study demonstrating a significant association between microbial components in the indoor environment and eNO levels in asthmatic children. This study demonstrates the importance of simultaneously assessing multiple home exposures of asthmatic children to better understand opposing effects. Common components of the indoor Streptomyces community may beneficially influence airway inflammation.

Effect of moisture-damage intervention on the immunotoxic potential and microbial content of airborne particles and on occupants' upper airway inflammatory responses

This intervention study evaluated the effect of moisture-damage repairs on the exposure and on the upper airway inflammatory responses of the occupants. The airborne microbial exposure was followed by quantitative PCR analyses of 13 microbial species in repeated long-term indoor air samples before (N = 26) and after (N = 28) repairs of the school building. Airborne particulate matter was collected similarly from the same premises (before N = 25, after N = 34) for determination of nitric oxide (NO), tumor necrosis factor α (TNFα), and interleukin-6 (IL-6), measured in the cell culture medium of mouse macrophages. NO, TNFα, IL-6, and IL-4 were also analyzed in the nasal lavage (NAL) samples of the occupants (N = 13) to characterize their upper airway inflammatory responses during the exposure and after its cessation. After the repairs, concentrations of the measured airborne microbes decreased, the difference being significant for six of 13 species. After renovation, airborne particulate matter also caused significantly lower production of IL-6 and TNF-α in mouse macrophages than the material collected before the renovation. The concentration of IL-4 in the NAL samples was significantly lower after the renovation. These results show that the inflammatory potential of the airborne material decreases after intensive repair of the moisture damage.

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.

Determination of indoor air quality in archives and biodeterioration of the documentary heritage

Documentary heritage is permanently subject to suffering from physical, chemical, and/or biological alterations. Biological deterioration by microorganisms (bacteria and fungi) causes undesirable changes on material properties. Microorganisms affect different organic, natural or synthetic substrates (cellulose, polycarbonates), metals, and compounds of optical and magnetic devices (CD, VHS). Paper made by vegetal fibers, functional additives (glue, optical polishers, consolidating agents), and inks with organic bindings are used as sources of nutrients. The environmental microorganisms that form the microbial charge of indoor air at repositories (archives, libraries) storing cultural heritage can deteriorate the different supports of heritage importance and affect human health as allergies and skin affections. The aims of this research were to study microbial contamination of the environment and its influence on biodeterioration by the biofilm formation and to analyze the relationship between environment microbiota and biofilm formation in materials stored at three archives in Argentina and in two repositories of the National Archive of the Republic of Cuba.

Rhinosinusitis and mold as risk factors for asthma symptoms in occupants of a water-damaged building

Mold exposure in damp buildings is associated with both nasal symptoms and asthma development, but the progression of building-related (BR) rhinosinusitis symptoms to asthma is unstudied. We examined the risk of developing BR-asthma symptoms in relation to prior BR-rhinosinusitis symptoms and microbial exposure among occupants of a damp building. We conducted four cross-sectional health and environmental surveys among occupants of a 20-story water-damaged office building. We defined BR-rhinosinusitis symptom (N=131) and comparison (N=361) groups from participants' first questionnaire responses. We compared the odds for the development of BR-asthma symptoms between these two groups over the subsequent surveys, using logistic regression models adjusted for demographics, smoking, building tenure, and first-survey exposures to fungi, endotoxin, and ergosterol. The BR-rhinosinusitis symptom group had higher odds for developing BR-asthma symptoms [odds ratio (OR)=2.2; 95% confidence interval (CI)=1.3-3.6] in any subsequent survey compared to those without BR-rhinosinusitis symptoms. The BR-rhinosinusitis symptom group with higher fungal exposure within the building had an OR of 7.4 (95% CI=2.8-19.9) for developing BR-asthma symptoms, compared to the lower fungal exposure group without BR-rhinosinusitis symptoms. Our findings suggest that rhinosinusitis associated with occupancy of water-damaged buildings may be a sentinel for increased risk for asthma onset in such buildings.

PRACTICAL IMPLICATIONS

Exposure to mold is associated with the development of asthma in damp building occupants, and rhinitis is known to be a risk factor for asthma. However, there is little information about the degree of risk for the progression of rhinosinusitis to asthma owing to mold exposures in damp buildings. Our study of damp building occupants demonstrates that building-related (BR) rhinosinusitis symptoms were a risk factor for the development of BR asthma symptoms and that exposure to mold (fungi) or other dampness-related agents augments risk for the development of BR asthma symptoms among those with BR rhinosinusitis symptoms. Our findings suggest that occurrence of BR upper respiratory illness in water-damaged buildings may presage future endemic asthma.

Exposure assessment of residential mould, fungi and microbial components in relation to children's health: achievements and challenges

Each day we are exposed to a complex mixture of microbial agents and components in indoor environments. A major part of this mixture derives from fungal and bacterial origin. The impact between those microbial agents in the home environment in relation to respiratory health in children is still a major issue in research. There is little known about the causal agents that provoke or arrest the development of allergic respiratory disorders in children. Identification is complicated by the biodiversity and variability of microbial components in indoor air as well as the lack of validated and standardized exposure assessment methods. In this review, we aim to consider all important aspects in terms of research which may encounter an epidemiological study. Apart from the need for standardized exposure assessment methods which consider cost, handling and effort, especially for the participants, we suggest that a combination of different analysis methods such as chemical and molecular methods may have the potential to best describe the microbial milieu in indoor environments at present. Further, the impact of mould and moisture remediation activities on health is still heavily under investigated, especially in larger prospective cohorts of children and should be a topic of future research. Moreover, the exposure to mould and microbial agents might be embedded in a broader spectrum of children's health such as behavior and cognitive development.

Comparison of the virulence potential of Acinetobacter strains from clinical and environmental sources

Several Acinetobacter strains have utility for biotechnology applications, yet some are opportunistic pathogens. We compared strains of seven Acinetobacter species (baumannii, Ab; calcoaceticus, Ac; guillouiae, Ag; haemolyticus, Ah; lwoffii, Al; junii, Aj; and venetianus, Av-RAG-1) for their potential virulence attributes, including proliferation in mammalian cell conditions, haemolytic/cytolytic activity, ability to elicit inflammatory signals, and antibiotic susceptibility. Only Ah grew at 10² and 10⁴ bacteria/well in mammalian cell culture medium at 37°C. However, co-culture with colonic epithelial cells (HT29) improved growth of all bacterial strains, except Av-RAG-1. Cytotoxicity of Ab and Ah toward HT29 was at least double that of other test bacteria. These effects included bacterial adherence, loss of metabolism, substrate detachment, and cytolysis. Only Ab and Ah exhibited resistance to killing by macrophage-like J774A.1 cells. Haemolytic activity of Ah and Av-RAG-1 was strong, but undetectable for other strains. When killed with an antibiotic, Ab, Ah, Aj and Av-RAG-1 induced 3 to 9-fold elevated HT29 interleukin (IL)-8 levels. However, none of the strains altered levels of J774A.1 pro-inflammatory cytokines (IL-1β, IL-6 and tumor necrosis factor-α). Antibiotic susceptibility profiling showed that Ab, Ag and Aj were viable at low concentrations of some antibiotics. All strains were positive for virulence factor genes ompA and epsA, and negative for mutations in gyrA and parC genes that convey fluoroquinolone resistance. The data demonstrate that Av-RAG-1, Ag and Al lack some potentially harmful characteristics compared to other Acinetobacter strains tested, but the biotechnology candidate Av-RAG-1 should be scrutinized further prior to widespread use.

Cadmium telluride quantum dot nanoparticle cytotoxicity and effects on model immune responses to Pseudomonas aeruginosa

This study examines dose effects of cadmium telluride quantum dots (CdTe-QDs) from two commercial sources on model macrophages (J774A.1) and colonic epithelial cells (HT29). Effects on cellular immune signalling responses were measured following sequential exposure to QDs and Pseudomonasaeruginosa strain PA01. At CdTe-QD concentrations between 10^-2 and 10 µg/ml, cells exhibited changes in metabolism and morphology. Confocal imaging revealed QD internalisation and changes in cell–cell contacts, shapes and internal organisations. QD doses below 10^-2 µg/ml caused no observed effects. When QD exposures at 10^-7 to 10^-3 µg/ml preceded PA01 (10⁷ bacteria/ml) challenges, there were elevated cytotoxicity (5–22%, p < 0.05) and reduced levels (two- to fivefold, p < 0.001) of nitric oxide (NO), TNF-α, KC/CXC−1 and IL-8, compared with PA01 exposures alone. These results demonstrate that exposures to sub-toxic levels of CdTe-QDs can depress cell immune-defence functions, which if occurred in vivo would likely interfere with normal neutrophil recruitment for defence against bacteria.

Streptomycetes in house dust: associations with housing characteristics and endotoxin

In addition to mold, indoor bioaerosols also contain bacterial components that may have implications for human health. Endotoxin is a cell wall component in Gram-negative bacteria present at varying levels indoors that has been found to have respiratory health implications. Streptomyces is a large genus of Gram-positive bacteria, and some species have been shown to produce inflammatory reactions in vitro and in vivo. The aim of this study was to determine predictors of streptomycetes levels in house dust and to compare the variation in streptomycetes levels with that in endotoxin levels. Dust was collected by floor vacuuming from 178 homes in the Cincinnati metropolitan area. Streptomycetes levels were measured by quantitative PCR, and endotoxin was assayed by the Limulus amebocyte lysate method. Associations between home characteristics and bacterial contaminants, expressed as concentration and load, were investigated through multiple regression analyses. The presence of two or more dogs was a strong predictor of both streptomycetes and endotoxin levels. Season of dust collection and levels of outdoor molds were predictors of streptomycetes but not endotoxin levels. In contrast, number of inhabitants was a significant predictor of endotoxin load only. Neither streptomycetes nor endotoxin levels were associated with metrics of moisture damage.

Flood management: prediction of microbial contamination in large-scale floods in urban environments

With a changing climate and increased urbanisation, the occurrence and the impact of flooding is expected to increase significantly. Floods can bring pathogens into homes and cause lingering damp and microbial growth in buildings, with the level of growth and persistence dependent on the volume and chemical and biological content of the flood water, the properties of the contaminating microbes, and the surrounding environmental conditions, including the restoration time and methods, the heat and moisture transport properties of the envelope design, and the ability of the construction material to sustain the microbial growth. The public health risk will depend on the interaction of these complex processes and the vulnerability and susceptibility of occupants in the affected areas. After the 2007 floods in the UK, the Pitt review noted that there is lack of relevant scientific evidence and consistency with regard to the management and treatment of flooded homes, which not only put the local population at risk but also caused unnecessary delays in the restoration effort. Understanding the drying behaviour of flooded buildings in the UK building stock under different scenarios, and the ability of microbial contaminants to grow, persist, and produce toxins within these buildings can help inform recovery efforts. To contribute to future flood management, this paper proposes the use of building simulations and biological models to predict the risk of microbial contamination in typical UK buildings. We review the state of the art with regard to biological contamination following flooding, relevant building simulation, simulation-linked microbial modelling, and current practical considerations in flood remediation. Using the city of London as an example, a methodology is proposed that uses GIS as a platform to integrate drying models and microbial risk models with the local building stock and flood models. The integrated tool will help local governments, health authorities, insurance companies and residents to better understand, prepare for and manage a large-scale flood in urban environments.

Cytotoxicity screening of 23 engineered nanomaterials using a test matrix of ten cell lines and three different assays

Background

Engineered nanomaterials display unique properties that may have impact on human health, and thus require a reliable evaluation of their potential toxicity. Here, we performed a standardized in vitro screening of 23 engineered nanomaterials. We thoroughly characterized the physicochemical properties of the nanomaterials and adapted three classical in vitro toxicity assays to eliminate nanomaterial interference. Nanomaterial toxicity was assessed in ten representative cell lines.

Results

Six nanomaterials induced oxidative cell stress while only a single nanomaterial reduced cellular metabolic activity and none of the particles affected cell viability. Results from heterogeneous and chemically identical particles suggested that surface chemistry, surface coating and chemical composition are likely determinants of nanomaterial toxicity. Individual cell lines differed significantly in their response, dependent on the particle type and the toxicity endpoint measured.

Conclusion

In vitro toxicity of the analyzed engineered nanomaterials cannot be attributed to a defined physicochemical property. Therefore, the accurate identification of nanomaterial cytotoxicity requires a matrix based on a set of sensitive cell lines and in vitro assays measuring different cytotoxicity endpoints.

Involvement of epidermal growth factor receptor-linked signaling responses in Pseudomonas fluorescens-infected alveolar epithelial cells

Pseudomonas fluorescens is an opportunistic indoor pathogen that can cause severe airway proinflammatory responses. Pulmonary epithelium, like other mucosal epithelial linings of the body, constitutes the first line of defense against airway microbial pathogens. Mucosal epithelial cells can be a sentinel of pathogenic bacteria via stimulation of specific cell surface receptors, including the epidermal growth factor receptor (EGFR) and Toll-like receptor (TLR). This study addressed the involvement of EGFR in airway epithelial pathogenesis by P. fluorescens. Human A549 pneumocytes showed prolonged production of proinflammatory interleukin-8 (IL-8) in response to infection with P. fluorescens, which was via the nuclear factor-kappa B (NF-κB) signaling pathway. Production of proinflammatory cytokine IL-8 was not mediated by P. fluorescens lipopolysaccharide, a representative TLR4 agonist, but was mediated through EGFR-linked signals activated by the opportunistic bacteria. Moreover, EGFR signals were involved in NF-κB signal-mediated production of proinflammatory cytokines. Along with persistent NF-κB activation, P. fluorescens enhanced the EGFR phosphorylation and subsequent activation of downstream mediators, including protein kinase B or extracellular-signal-regulated kinases 1/2. Blocking of EGFR-linked signals increased epithelial susceptibility to pathogen-induced epithelial cell death, suggesting protective roles of EGFR signals. Thus, airway epithelial exposure to P. fluorescens can trigger antiapoptotic responses via EGFR and proinflammatory responses via TLR4-independent NF-κB signaling pathway in human pneumocytes.

Immunotoxicological properties of airborne particles at landfill, urban and rural sites and their relation to microbial concentrations

We investigated the immunotoxicological activity of airborne particles in three different environments during 11 months. Specifically, we analyzed the relation of the immunotoxicological activity to microbial concentrations. During the study period, samples from a landfill, an urban and a rural site were collected on filters once a month. The immunotoxicological characteristics of collected particle samples were studied by exposing mouse macrophages (RAW264.7), and measuring the viability and production of inflammatory mediators i.e. nitric oxide (NO), tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 after 24 hours. In addition, the results were compared to corresponding microbial concentrations measured with quantitative polymerase chain reaction (qPCR) in the same sites. The particles collected from the landfill caused significantly more toxicity and inflammatory responses than the particles from other sites. The immunotoxicological activity of the samples changed according to the season, being the lowest in all study sites in the winter. In the rural and urban sites the responses peaked during the spring, whereas at the landfill the highest responses were detected towards the fall. All immunotoxic responses correlated strongly with airborne microbial concentrations at the landfill, whereas on the other sites the correlations were weaker. These results indicate that the overall immunotoxicological activity of the particles is increased in waste handling area with a heavy microbial load. The activity of the samples collected from different sites changes according to the season being at their lowest at wintertime. At the waste center, the immunotoxicological responses are related with concentrations of microbes, whereas at rural area and city center other factors seem to govern the toxicity of the sample.

Co-cultivated damp building related microbes Streptomyces californicus and Stachybotrys chartarum induce immunotoxic and genotoxic responses via oxidative stress

Oxidative stress has been proposed to be one mechanism behind the adverse health outcomes associated with living in a damp indoor environment. In the present study, the capability of damp building-related microbes Streptomyces californicus and Stachybotrys chartarum to induce oxidative stress was evaluated in vitro. In addition, the role of oxidative stress in provoking the detected cytotoxic, genotoxic, and inflammatory responses was studied by inhibiting the production of reactive oxygen species (ROS) using N-acetyl-l-cysteine (NAC). RAW264.7 macrophages were exposed in a dose- and time-dependent manner to the spores of co-cultivated S. californicus and S. chartarum, to their separately cultivated spore-mixture, or to the spores of these microbes alone. The intracellular peroxide production and cytotoxicity were measured by flow cytometric analysis, nitric oxide production was analyzed by the Griess method, DNA damage was determined by the comet assay, and cytokine production was measured by an immunochemical ELISA (enzyme-linked immunosorbent assay). All the studied microbial exposures triggered oxidative stress and subsequent cellular damage in RAW264.7 macrophages. The ROS scavenger, NAC, prevented growth arrest, apoptosis, DNA damage, and cytokine production induced by the co-culture since it reduced the intracellular level of ROS within macrophages. In contrast, the DNA damage and cell cycle arrest induced by the spores of S. californicus alone could not be prevented by NAC. Bioaerosol-induced oxidative stress in macrophages may be an important mechanism behind the frequent respiratory symptoms and diseases suffered by residents of moisture damaged buildings. Furthermore, microbial interactions during co-cultivation stimulate the production of highly toxic compound(s) which may significantly increase oxidative damage.

Fungal spores: a critical review of the toxicological and epidemiological evidence as a basis for occupational exposure limit setting

Fungal spores are ubiquitous in the environment. However, exposure levels in workplaces where mouldy materials are handled are much higher than in common indoor and outdoor environments. Spores of all tested species induced inflammation in experimental studies. The response to mycotoxin-producing and pathogenic species was much stronger. In animal studies, nonallergic responses dominated after a single dose. Allergic responses also occurred, especially to mycotoxin-producing and pathogenic species, and after repeated exposures. Inhalation of a single spore dose by subjects with sick building syndrome indicated no observed effect levels of 4 x 10(3) Trichoderma harzianum spores/m(3) and 8 x 10(3) Penicillium chrysogenum spores/m(3) for lung function, respiratory symptoms, and inflammatory cells in the blood. In asthmatic patients allergic to Penicillium sp. or Alternaria alternata, lowest observed effect levels (LOELs) for reduced airway conductance were 1 x 10(4) and 2 x 10(4) spores/m(3), respectively. In epidemiological studies of highly exposed working populations lung function decline, respiratory symptoms and airway inflammation began to appear at exposure levels of 10(5) spores/m(3). Thus, human challenge and epidemiological studies support fairly consistent LOELs of approximately 10(5) spores/m(3) for diverse fungal species in nonsensitised populations. Mycotoxin-producing and pathogenic species have to be detected specifically, however, because of their higher toxicity.

Aspergillus fumigatus germ tube growth and not conidia ingestion induces expression of inflammatory mediator genes in the human lung epithelial cell line A549

Inhalation of conidia is the main cause of invasive pulmonary aspergillosis (IPA) and the respiratory epithelium is the first line of defence. To explore the triggering factor for the inflammatory response to Aspergillus fumigatus, the species mainly responsible for IPA, this study analysed the differential expression of three inflammatory genes in A549 cells after challenge with live and killed conidia. The influence of steroids, one of the main risk factors for developing IPA, was also investigated. Quantification of mRNAs of the inflammatory mediator genes encoding interleukin (IL)-8, tumour necrosis factor (TNF)-alpha and granulocyte-monocyte colony-stimulating factor (GM-CSF) was carried out using real-time PCR. Ingestion rates were studied for the conidia of A. fumigatus and Penicillium chrysogenum using a fluorescence brightener. Similar results were obtained for both species, with ingestion rates ranging from 35 to 40 %. Exposure of A549 cells to live A. fumigatus conidia only induced a four- to fivefold increase in the mRNA levels of the three genes, starting 8 h after the initial contact. Both inactivation of live A. fumigatus conidia and treatment by dexamethasone (10(-7) M) prevented the overexpression of TNF-alpha, IL-8 and GM-CSF. Fungal growth, rather than conidia ingestion, appears to be the main stimulus for the production of inflammatory mediators by epithelial cells, and this production is inhibited by steroid therapy. These results underline the role that the epithelium plays in the innate response against IPA.

Indoor air particles and bioaerosols before and after renovation of moisture-damaged buildings: the effect on biological activity and microbial flora

Many building-related health problems coincide with moisture damage and mold growth within a building. Their elimination is assumed to improve indoor air quality. The aim of this study was to follow the success of remediation in two individual buildings by analyzing the microbial flora and immunotoxicological activity of filter samples. We compare results from samples collected from indoor air in the moisture-damaged buildings before and after renovation and results from matched reference buildings and outdoor air. The microbial characteristics of the samples were studied by analyzing ergosterol content and determining the composition of fungal flora with quantitative polymerase chain reaction (QPCR). In addition, the concentrations of particles were monitored with optical particle counter (OPC). The immunotoxicological activity of collected particle samples was tested by exposing mouse macrophages (RAW264.7) for 24 h to particle suspension extracted from the filters, and measuring the viability of the exposed cells (MTT-test) and production of inflammatory mediators (nitric oxide, IL-6 and TNF*) in cell culture medium by enzyme-linked immunoassay (ELISA). The results show that for Location 1 the renovation decreased the immunotoxicological activity of the particles collected from damaged building, whereas no difference was detected in the corresponding samples collected from the reference building. Interestingly, only slight differences were seen in the concentration of fungi. In the Location 2, a decrease was seen in the concentration of fungi after the renovation, whereas no effect on the immunotoxicological responses was detected. In this case, the immunotoxicological responses to the indoor air samples were almost identical to those caused by the samples from outdoor air. This indicates that the effects of remediation on the indoor air quality may not necessarily be readily measurable either with microbial or toxicological parameters. This may be associated with different spectrum of harmful agents in different mold and moisture-damaged buildings.