Pathological Study of Chronic Pulmonary Toxicity Induced by Intratracheally Instilled Asian Sand Dust (Kosa)

Abstract

Asian sand dust (ASD) events are associated with an increase in pulmonary morbidity and mortality. The number of ASD events has increased rapidly in the east Asian region since 2000. To study the chronic lung toxicity of ASD, saline suspensions of low doses (200 and 400 mg) and high doses (800 and 3,000 mg) of ASD were intratracheally instilled into ICR mice. Animals were sacrificed at 24 hr, 1 week, or 1, 2, or 3 months after instillation. Histopathological examination revealed that ASD induced acute inflammation at 24 hr after instillation. The acute inflammation was transient and subsided at 1 week and 1 month after instillation. At 2 and 3 months after instillation, focal infiltration of lymphocytes with accumulation of epithelioid macrophages, which is a suggestive finding of transformation to granuloma, and granuloma formation were occasionally observed. Aggregation of macrophages containing particles was observed in the pulmonary lymph nodes at 3 months after instillation in high-dose groups. Prolonged inflammatory foci (granuloma) and presence of ASD particles in pulmonary lymph nodes would have a chance to induce immunological modulation leading to adverse health effects in the exposed animals.

Pathological study of pulmonary toxicity induced by intratracheally instilled Asian sand dust (Kosa): Effects of lowered serum zinc level on the toxicity

“…A lung histological examination revealed similar patterns in the lesions of normal-and low-serum levels of Zn in mice treated with ASD; these changes were both purulent (acute) and pyogranulomatous (chronic) in nature. These findings are largely in agreement with previous reports of pulmonary toxicity in mice induced by the same dose of intratracheally instilled ASD particles; this is relevant for both the acute purulent inflammation and following chronic granulomatous inflammation [9][10][11][12]. However, the inflammatory changes appeared to be more prominent and persistent in mice with low levels of serum Zn.…”

“…The changes were characterized by acute purulent inflammation and ensuing chronic granulomatous inflammation [9][10][11][12]. The direct effects of the ASD particles, release of cytokines from macrophages, and oxidative stress generated in the lesions may be involved in the development of lung toxicity [10].…”

Adverse effects of inhaled sand dust particles on the respiratory organs of sheep and goats exposed to severe sand storms in Mongolia

“…The major mineralogical component of ASD is silica (SiO 2 ), which is primarily derived from feldspar and quartz (crystalline silica) [19]. Silica is birefringent and white in color under polarized light, as observed in this and previous study [22]. Exposure to quartz (crystalline silica) reportedly induces silicosis, which is characterized by pulmonary fibrosis and granuloma formation [13].…”

“…In this study, myofibroblasts, which are positive for a-SMA and are involved in fibrosis of damaged lung tissue [27], were observed in the thickened alveoli. A granulomatous response in the lungs and tracheobronchial lymph nodes was also observed in mice exposed to ASD [22]. Involvement of cytokines, including TNF-a and IL-6, in the pulmonary inflammatory changes in patients with silicosis has been reported.…”

“…Silica is the major mineralogical component of ASD [19]. Previous studies examining experimental pulmonary toxicity of ASD particles showed that the mineralogical components of ASD particles that were free from chemical and biological pollutants cause acute [20,21] and chronic [22] inflammatory changes with granuloma formation in the lung tissues of mice. Similar mineral deposits of unknown origin in the tracheobronchial lymph nodes were reported in dogs [23,24].…”