Date: 29 Jan 2008

The Effects of Microbial Materials Adhered to Asian Sand Dust on Allergic Lung Inflammation

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Asian sand dust (ASD) containing microbiological materials, sulfate (SO 4 2 ), and nitrate (NO 3 ) derived from air pollutants in East China, reportedly cause adverse respiratory health effects. ASD aggravates ovalbumin (OVA)-associated experimental lung eosinophilia. In this study, the toxic materials adsorbed onto ASD were excluded by heat treatment at 360°C for 30 min. The effects of nonheated ASD or heated ASD (H-ASD) toward the allergic lung inflammation were compared in murine lungs. ICR mice were administered intratracheally with normal saline (control), H-ASD, ASD, OVA, OVA + H-ASD, and OVA + ASD, four times at 2-week intervals. ASD only increased neutrophils in bronchoalveolar lavage fluids (BALFs) along with pro-inflammatory mediators, such as keratinocyte chemoattractant (KC). H-ASD and ASD enhanced eosinophil recruitment induced by OVA in the alveoli and in the submucosa of the airway, which has a goblet cell proliferation in the bronchial epithelium. The two ASDs synergistically increased interleukin-5 (IL-5), monocyte chemotactic protein-3 (MCP-3), and eotaxin, which were associated with OVA, in BALF. The enhancing effects were much greater in ASD than in H-ASD. The two ASDs induced the adjuvant effects to specific IgE and IgG1 production by OVA. In the in vitro study using RAW264.7 cells, ASD increased the expression of Toll-like receptor 2 (TLR 2) mRNA but not TLR4 mRNA. H-ASD caused no expression of either TLR mRNA. These results suggest that the aggravated lung eosinophilia by ASD may be due to activation of Th2-associated immune response via the activation of TLR2 by microbial components adhered to ASD.