Abstract
BackgroundEpidemiological studies suggest an association between exposure to volatile organic compounds (VOCs) and adverse allergic and respiratory symptoms. However, whether VOCs exhibit a causal role as adjuvants in asthma development remains unclear.MethodsTo investigate the effect of VOC exposure on the development of allergic airway inflammation Balb/c mice were exposed to VOCs emitted by new polyvinylchloride (PVC) flooring, sensitized with ovalbumin (OVA) and characterized in acute and chronic murine asthma models. Furthermore, prevalent evaporated VOCs were analyzed and mice were exposed to selected single VOCs.ResultsExposure of mice to PVC flooring increased eosinophilic lung inflammation and OVA-specific IgE serum levels compared to un-exposed control mice. The increased inflammation was associated with elevated levels of Th2-cytokines. Long-term exposure to PVC flooring exacerbated chronic airway inflammation. VOCs with the highest concentrations emitted by new PVC flooring were N-methyl-2-pyrrolidone (NMP) and 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (TXIB). Exposure to NMP or TXIB also increased the allergic immune response in OVA-sensitized mice. In vitro or in vivo exposure to NMP or TXIB reduced IL-12 production in maturing dendritic cells (DCs) and enhanced airway inflammation after adoptive DC transfer into Balb/c mice. At higher concentrations both VOCs induced oxidative stress demonstrated by increased isoprostane and glutathione-S-transferase-pi1 protein levels in the lung of non-sensitized mice. Treatment of PVC flooring-exposed mice with N-acetylcysteine prevented the VOC-induced increase of airway inflammation.ConclusionsOur results demonstrate that exposure to VOCs may increase the allergic immune response by interfering with DC function and by inducing oxidative stress and has therefore to be considerate as risk factor for the development of allergic diseases.
Highlights
Over the last two decades the prevalence of allergic diseases and asthma has increased substantially in industrial nations [1]
Interior products such as synthetic coated furniture, carpets, polyvinylchloride (PVC) flooring and building materials and cleaning agents emit an array of volatile organic compounds (VOCs) [5]
The results indicate an adjuvant effect of VOC exposure that was mediated by modulating the Th1/Th2 balance via direct effects on IL-12 production in dendritic cells (DCs) and by inducing oxidative stress in the airways
Summary
Over the last two decades the prevalence of allergic diseases and asthma has increased substantially in industrial nations [1]. It has been suggested that exposure to chemicals commonly found indoors could exhibit a role for adverse allergic airway symptoms [4]. Interior products such as synthetic coated furniture, carpets, polyvinylchloride (PVC) flooring and building materials and cleaning agents emit an array of volatile organic compounds (VOCs) [5]. In mouse studies it has been shown that gaseous formaldehyde or low molecular weight respiratory sensitizers may affect allergen-specific serum IgE or IL-4 levels, respectively [17,18] These data suggest a direct interaction of VOCs with redox-sensitive pathways that may lead to a modified immune response. Whether VOCs exhibit a causal role as adjuvants in asthma development remains unclear
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