肺泡壁细胞凋亡参与木瓜蛋白酶所致大鼠肺气肿的形成

Apoptosis of alveolar wall cells is involved in papain-induced rat pulmonary emphysema

目的:观察木瓜蛋白酶所致的肺气肿大鼠肺泡壁细胞凋亡,探讨细胞凋亡在肺气肿发病中的作用。方法:大鼠随机分为3组:正常对照组、木瓜蛋白酶组、木瓜蛋白酶联合[^(60)Co]处理组。观察肺组织病理学变化,TUNEL法检测大鼠肺泡壁凋亡细胞,免疫组化法检测肺泡壁细胞PCNA、Bax和SP-C蛋白的表达。TUNEL与SP-C免疫荧光法鉴定凋亡细胞中的II型肺泡上皮细胞。结果:木瓜蛋白酶组、木瓜蛋白酶联合[^(60)Co]处理组大鼠出现明显肺气肿。木瓜蛋白酶联合[^(60)Co]处理组平均内衬间隔,平均肺泡面积和单位面积肺泡数与木瓜蛋白酶组比较有显著差异。木瓜蛋白酶组,木瓜蛋白酶联合[^(60)Co]处理组大鼠肺泡壁细胞的AI、PI以及Bax染色阳性的细胞百分比显著高于正常对照组;而SP-C染色阳性的细胞百分比显著低于正常对照组。木瓜蛋白酶联合[^(60)Co]处理组大鼠的AI、PI、Bax染色阳性的细胞百分比显著高于木瓜蛋白酶组;而SP-C染色阳性的细胞百分比显著低于木瓜蛋白酶组。部分TUNEL阳性细胞表达II型肺泡上皮细胞标志SP-C。结论:大鼠肺泡壁细胞特别是II型肺泡上皮细胞凋亡参与肺气肿的形成,Bax蛋白的表达上调可能导致肺气肿大鼠肺泡壁细胞的凋亡。

AIM： To observe the apoptosis of alveolar wall cells in the papin - induced rat emphysema, and to explore the role of apoptosis of alveolar wall cells in the pathogenesis of emphysema. METHODS ： Rats were randomly divided into three groups： normal control group, papain only group, papain ＋ irradiation group. Morphology of lung tissues was assessed. TUNEL assay was used to determine the apoptotic cells. Immunohistochemistry was performed to determine the expression of PCNA, Bax and SP - C in the lung alveolar wall cells. SP - C immunofluorescence stainging was performed to identify the type Ⅱ alveolar cells in the TUNEL positive cells. RESULTS ： Destruction of alveolar wall and loss of the alveolar unit were observed in papain only group and papain ＋ irradiation group. There was significant difference be-tween rats of papain ＋ irradiation group and papain only growp in the mean linear interval （MLI）, the number of alveolar counted per unit area （MAN） and mean alveoli area （MAA） , respectively （P〈0.01）. The proliferation index（PI） , apoptosis index （AI） and the percentage of Bax in the papain only group and papain ＋ irradiation group were significantly greater than that in the normal control group （P 〈 0. 01 ）. However, the percentage of SP - C positive cells was significantly lower in the papain only group and papain ＋ irradiation group compared with the normal control （P 〈0. 01 ）. Moreover, the PI, AI and the percentage of Bax in the papain ＋ irradiation group was higher than those in the papain only group. The percentage of SP - C positive cells in the papain ＋ irradiation group was lower than that in the papain only group. Most of the TUNEL - positive cells expressed the SP - C. CONCLUSION ： Apoptosis of rat alveolar wall cells, especially type-Ⅱ cell may be involved in the pathogenesis of emphysema. Upregulation of Bax expression may lead to alveolar wall cells apoptosis in papain -induced emphysema.