The inflammation and fibrosis induced by silica dust are considered to be substantial responses in silicosis progression. Interleukin-1 beta (IL-1β) plays an important role in silica-induced lung inflammation, but the mechanisms that underlie the influence of IL-1β on the progression of silicosis remain unclear. In this study, the role of IL-1β in silica-induced inflammation and fibrosis was evaluated by administering a suspension of 2.5-mg silica dust, either with or without 40 μg anti-mouse IL-1β monoclonal antibody (mAb), to the lungs of male C57BL/6 mice. Silica + anti-IL-1β mAb-treated mice showed the depletion of IL-1β as well as the attenuation of inflammation, as evaluated in the bronchoalveolar lavage fluid (BALF) and histological sections from 1 to 84 days after silica exposure. Further study of the BALF indicated that inhibition of IL-1β could reduce the contents of tumor necrosis factor-alpha and monocyte chemoattractant protein-1. The real-time PCR and pathology results showed that the neutralization of IL-1β attenuated silica-induced fibrosis by inhibiting the gene expression of transforming growth factor-beta 1, collagen I and fibronectin. The examination of Th1-cytokine and Th2-cytokine suggested that depletion of IL-1β decelerated the Th1/Th2 balance toward a Th2-dominant response. In conclusion, the present study suggests that the neutralization of IL-1β attenuates silica-induced inflammation and fibrosis by inhibiting other inflammatory and fibrogenic mediators and modulating the Th1/Th2 balance.

A new, simple and sensitive method was developed for the determination of silicon tetrahydride in the air of workplace in this study. The alkaline resin-based spherical activated carbon was used to collect sample of silicon tetrahydride at workplace. Silicon tetrahydride was then desorbed from active carbon in 100°C hot water. After reacting with ammonium molybdate, oxalic acid and 1,2,4-trichlorobenzene alpha-naphthol amino sulfonic acid under acid condition, silicon tetrahydride was transformed into silicon molybdenum blue. The absorbance of silicon molybdenum blue was quantitatively measured at the wavelength of 680 nm. The results showed that the average sampling efficiency and desorption efficiency were 97.53% and 94.94%, respectively by this method. Detection limits were 0.054 μg/mL for the spectrophotometric method and 0.14 mg/m(3) for the determination of silicon tetrahydride in the air of workplace (sampling volume was 7.5 L). The conversion rate of silicon tetrahydride gradually decreased when storage time of samples was extended. The descent rate of sample was less than 10% when the sample was sealed for 7 days in the room temperature. It was concluded that this spectrophotometric method can be successfully used to determine silicon tetrahydride in the worksites.