Assessment of the Total Inflammatory Potential of Bioaerosols by Using a Granulocyte Assay

Abstract

Occupational health symptoms related to bioaerosol exposure have been observed in a variety of working environments. Bioaerosols contain microorganisms and microbial components. The aim of this study was to estimate the total inflammatory potential (TIP) of bioaerosols using an in vitro assay based on granulocyte-like cells. A total of 129 bioaerosol samples were collected in the breathing zone of workers during their daily working routine at 22 biofuel plants. The samples were analyzed by traditional assays for dust, endotoxin, fungal spores, (133)-␤-D-glucan, total number of bacteria, the enzyme N-acetyl-␤-D-glucosaminidase (NAGase; primarily originating from fungi), Aspergillus fumigatus, and mesophilic and thermophilic actinomycetes; the samples were also assayed for TIP. In a multilinear regression four factors were significant for the TIP values obtained: endotoxin (P < 0.0001), fungal spores (P < 0.0001), (133)-␤-D-glucan (P ‫؍‬ 0.0005), and mesophilic actinomycetes (P ‫؍‬ 0.0063). Using this model to estimate TIP values on the basis of microbial composition, the correlation to the measured values was r ‫؍‬ 0.91. When TIP values obtained in the granulocyte assay were related to the primary working area, we found that bioaerosol samples from personnel working in straw storage facilities showed high TIP values (Ϸ50 times the TIP of unstimulated controls). In contrast, bioaerosol samples from personnel with work functions in offices or laboratories showed low TIP values (Ϸ5 times the TIP of the unstimulated control). This indicates, as expected, that these areas were less contaminated. In conclusion, the granulocyte assay reacts to multiple contaminants in the environmental samples and can be used to obtain a measurement of TIP. Therefore, potential occupational health effects related to inflammation of the airways in a working environment can be estimated using this assay.For several years reports have related increased prevalence of respiratory symptoms to the exposure to bioaerosols containing, e.g., organic dust particles, actinomycetes, endotoxin, and fungal spores. Occupational health effects of bioaerosols have been reported in swine confinement houses and poultry farms as well as during hay handling. Airway diseases are frequent occupational disorders among farmers in many countries around the world (19,23). During mechanical handling, biofuels such as straw and wood chips release high amounts of various microbial components such as, e.g., actinomycetes, fungal spores, and endotoxin (11,25). Studies of personnel exposure to bioaerosols at biofuel plants reveal high concentrations of different microbial components and exposure levels higher than the suggested occupational exposure limits (10).Exposure limits or suggested exposure limits are usually based on studies where traditional microbial quantification methods have been applied and are normally related to the concentration of a single contaminant (e.g., endotoxin) (17) or to gravimetric measures of dust. Furthermore, it is recognized that exposur...

Seasonal Variations of Indoor Microbial Exposures and Their Relation to Temperature, Relative Humidity, and Air Exchange Rate

“…The assay is based on the differentiated HL-60 cell line, which, upon exposure to microbial compounds, reacts by producing reactive oxygen species (ROS) quantifiable by a luminal-dependent chemiluminometric assay. In this study, measurement of TIP was conducted as described previously (55). Prior to analysis, all samples were subjected to ultrafiltration for removal of Tween, as Tween inhibits the cellular ROS response in the granulocyte assay.…”

“…Prior to analysis, all samples were subjected to ultrafiltration for removal of Tween, as Tween inhibits the cellular ROS response in the granulocyte assay. Ultrafiltration was also conducted as described previously (55). The chemiluminescence reaction caused by sample activity was measured with a thermostated (37°C) Orion II Microplate luminometer (Berthold Detection Systems, Germany), which measured relative light units (RLU) per second for 1 s every 120 s for 180 min.…”

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Impact of air pollution on lung inflammation and the role of Toll-like receptors

“…92 Mechanistic studies have confirmed the presence of microbial components on PM samples and their ability to produce TLR-mediated signaling. 93 These studies demonstrate significant enhancement of the biological response to inactive PM with the addition of low levels of bacterial contamination.…”

Identification of Work Tasks Causing High Occupational Exposure to Bioaerosols at Biofuel Plants Converting Straw or Wood Chips

“…Also particles from combustion of dried animal drugs are described to be highly oxidative (Mudway et al 2005). Occupational exposure to bioaerosol components and the inflammatory potential of these bioaerosols are different in different working areas at the plants (Madsen 2006;Timm et al 2009). Furthermore the microbial dustiness of different biofuels (straw, wood chips, wood pellets and wood briquettes) differs (Madsen et al 2004) and also depends on the storage method and period (Sebastian et al 2006).…”