Effects of Asian Sand Dust, Arizona Sand Dust, Amorphous Silica and Aluminum Oxide on Allergic Inflammation in the Murine Lung

Abstract

The aggravating effects of Asian sand dust (SD) and related minerals on the allergic inflammation were examined in the murine lungs. The toxic materials adsorbed onto Asian SD, Arizona SD were inactivated by heat-treatment. ICR mice were administered mineral samples (0.1 mg/mouse) and/or ovalbumin (OVA) (1 μ g/mouse)—normal saline (control), Asian SD, Arizona SD, SiO₂, Al₂O₃, OVA, OVA + Asian SD, OVA + Arizona SD, OVA + SiO₂, and OVA + Al₂O₃—intratracheally four times at two-week intervals. All samples tested enhanced eosinophil recruitment induced by ovalbumin in the submucosa of the airway, which has a goblet cell proliferation in the bronchial epithelium. Arizona SD alone caused a slight increase of neutrophils in bronchoalveolar lavage fluids along with pro-inflammatory mediators, such as keratinocyte chemoattractant, but Asian SD alone or Al₂O₃ alone showed no effect. The test particles, except Al₂O₃, synergistically increased the numbers of eosinophils in BALF induced by ovalbumin. In particular, Arizona SD and SiO₂ synergistically increased the eosinophil relevant cytokine and chemokine, such as IL-5 and monocyte chemotactic protein (MCP)-3. The aggravating effects of the samples were dependent on the SiO₂ content. All samples tested also induced the adjuvant effects to specific IgG1 production by OVA. These results suggest that the aggravated allergic inflammation by mineral dusts may be due to the mineral elements (mainly SiO₂). The enhancement by Arizona SD may be mediated, at least partially, by the increased expression of IL-5 and MCP-3 and also by the modulated expression of IL-5 and MCP-3.