环磷酸腺苷信号对矽肺纤维化形成的影响

Influence of cAMP signal on pathogenesis of silicotic fibrosis

目的观察环磷酸腺苷(cAMP)信号在大鼠矽肺纤维化发生、发展过程中的变化及其对矽肺纤维化形成的影响。方法采用HOPE-MED8050动式染尘控制系统复制大鼠矽肺模型,雄性Wistar大鼠随机分为6组,每组10只,分别染尘0、2、4、8、12和16周。采用Masson三色染色观察肺组织形态,采用免疫组织化学法染色和Western blot检测α-平滑肌肌动蛋白(α-SMA)、Ⅰ型胶原(CollagenⅠ)、纤连蛋白(Fn)、激动型G蛋白α(Gαs)、抑制型G蛋白α(Gαi2、Gαi3)及cA MP的表达。结果 Masson三色染色显示,矽肺模型4周组细胞性结节区域可见蓝紫色胶原沉积,并随模型制备时间的延长纤维化病变区域胶原沉积逐渐增加。免疫组织化学法染色显示,对照组α-SMA阳性表达部位在气管及血管平滑肌;在矽肺模型16周组,α-SMA表达于结节周边及间质纤维化病变区域。α-SMA、CollagenⅠ、Fn及Gαi2、Gαi3蛋白表达在矽肺模型4、8、12和16周较对照组逐渐增多。在矽肺模型8周组Gαs蛋白表达及cAMP含量较对照组下降,至染尘16周达最低。结论 cAMP的表达在矽肺发生、发展过程中呈下降趋势,cAMP信号参与大鼠矽肺纤维化过程。

Objective To observe the changes of cyclic adenosine monophosphate （cAMP） signal in patho-genesis and development of silicotic fibrosis. Methods A HOPE-MED8050 exposure control apparatus was used to copy the silicosis model. Male Wistar rats were randomly divided into 6 groups （10 in each group） and the rats inhaled dust respectively for 0, 2, 4, 8, 12 and 16 w. Masson trichrome staining was performed to observe the histomorphology of the lung tissues. The expressions of α smooth muscle actin （α-SMA）, col-lagen Ⅰ, fibronectin （Fn）, stimulatory G protein α （Gαs）, inhibitory G protein α （Gαi2/3） and cAMP were detected by immunohistochemistry and Western blot respectively. Results Masson trichrome staining revealed bluish-purple collagen deposition in the 4-w silicosis group, and the collagen deposition in the fibrotic lesions increased with the time of exposure to silica. Immunohistochemical results showed that in the control group positive α-SMA expression was seen in the trachea and vascular smooth muscles, while in the 16-w silicosis group α-SMA was observed around the fibrotic nodules and in the interstitial fibrotic area. The expressions ofα-SMA, collagen I, Fn and Gαi2/3 proteins gradually increased in the 4-w, 8-w, 12-w and 16-w silicosis groups compared with the control group. As compared to the control group, the expressions of Gαs and cAMP significantly decreased in the 8-w silicosis group, and were the lowest in the the 16-w silicosis group. Conclusions cAMP expression decreases along with the pathogenesis and development of silicosis, and cAMP has a significant role in silicotic formation.