Macrophage apoptosis and the levels of interleukin-1 and interleukin-8 in the rats exposed to silica / 中华劳动卫生职业病杂志

ABSTRACT

<p><b>OBJECTIVE</b>To study the roles of macrophage apoptosis, IL-1, and IL-8 in the pathogenesis of rat pulmonary fibrosis induced by silica.</p><p><b>METHODS</b>Forty eight male Wistar rats were divided into the 4 control groups (24 rats) and 4 experimental groups (24 rats). Rats in the control groups were treated with 1 ml normal saline by trachea instillation, whereas the rats in experimental groups were exposed 1 ml silica suspension (100 mg/ml) by trachea instillation for 1, 7, 14 and 28 days, respectively. Six rats of each group were sacrificed, then the bronchoalveolar lavage fluid and lung tissues were collected, respectively. Pulmonary inflammation, fibrosis and other pathological changes were detected with H.E. staining. Morphological changes of the early stage apoptosis in macrophages were detected with transmission electron microscope (TEM). The early apoptosis rates of macrophages in BALF were also assessed using Annexin V-FITC/PI kit. The IL-1 and IL-8 levels of serum were measured with the ELISA.</p><p><b>RESULTS</b>The apoptotic rates (11.48% +/- 0.24%, 16.03% +/- 0.68%, 15.53% +/- 1.07%, 18.92% +/- 2.70%, respectively) of macrophage in the experimental groups increased obviously with time, as compared to the controls (5.47% +/- 2.06%, 6.39% +/- 0.215, 9.07% +/- 0.61% and 8.54% +/- 0.16%, Respectively) (P < 0.05). The IL-1 levels of serum in the experimental groups were 23.64 +/- 0.84, 23.38 +/- 1.10, 22.21 +/- 0.86 and 24.29 +/- 1.31 pg/ml, respectively, which were significantly higher than those (18.52 +/- 1.23, 18.40 +/- 1.6, 17.92 +/- 2.21 and 18.53 +/- 2.64 pg/ml, respectively) in the control groups (P < 0.05) without time-effect relationship. The serum IL-8 levels on the 1st, 7th and 14th days in the experimental groups were 21.32 +/- 1.44, 21.90 +/- 2.08 and 22.00 +/- 2.80 pg/ml, respectively, which were significantly higher than those (17.69 +/- 1.09, 16.98 +/- 2.09 and 17.54 +/- 1.62 pg/ml, respectively) in the control groups (P < 0.05).</p><p><b>CONCLUSION</b>The early macrophage apoptosis and changes of IL-1 and IL-8 may in lungs may play an important role in the development of pulmonary fibrosis induced by silica.</p>