分析人羊膜间充质干细胞(human amniotic mesenchymal stromal cells, hAMSCs)移植后对急性肺损伤(acute lung injury, ALI)大鼠肺组织水通道蛋白1(AQP1)和磷酸化p38丝裂原活化蛋白激酶(p-p38MAPK)表达的影响及对肺损伤的作用机制。

随机将84只SD雄性大鼠分为4组(n＝21)：生理盐水对照组(NS组)、LPS诱导ALI模型组(LPS组)、hAMSCs对照组(NH组)及hAMSCs干预组(LH组)。LPS组和LH组大鼠通过舌下静脉注射LPS(4 mg/kg)造模；NS组和NH组大鼠通过舌下静脉注射250 μl生理盐水，2 h后NH组和LH组大鼠通过尾静脉注射250 μl经DAPI标记的hAMSCs(2.5×10⁶个)；NS组和LPS组大鼠通过尾静脉注射250 μl生理盐水。每组分别于6 h、12 h、72 h随机处死7只大鼠观察hAMSCs在每组中的定植情况、肺组织病理形态，湿干重比值(W/D)，Elisa法检测BALF中TNF-α、IL-1β水平，IHC及WB法检测各组大鼠肺组织AQP1、p38MAPK和p-p38 MAPK的表达。

①NH和LH组大鼠肺泡周围有蓝色荧光标记的hAMSCs, LH组分布较多，NH组分布较少；②NS组、NH组对应时相点的大鼠肺组织病理评分、W/D比值、BALF中TNF-α和IL-1β水平、AQP1和p-p38 MAPK蛋白表达量相比较无显著性差异(P>0.05)；③与NS组、NH组时相点相比较，LPS组、LH组对应时相点大鼠肺组织病理评分、W/D比值、BALF中TNF-α、IL-1β水平和p-p38 MAPK蛋白表达量升高，AQP1表达量降低(P<0.05)；④LPS 6 h组与12 h组大鼠肺组织病理评分、W/D比值、BALF中TNF-α和IL-1β水平、AQP1和p-p38 MAPK蛋白表达量无明显差异(P>0.05)；与LPS 6 h组、12 h组相比较，LPS 72 h组大鼠肺组织病理评分、W/D比值、BALF中IL-1β和TNF-α水平、p-p38 MAPK蛋白表达量降低，AQP1表达量升高(P<0.05)；LH 6 h组与12 h组大鼠肺组织病理评分、W/D比值、BALF中IL-1β和TNF-α水平、AQP1和p-p38 MAPK蛋白表达量无明显差异(P>0.05)；与LH 6 h组、12 h组相比较，LH 72 h组大鼠肺组织病理评分、W/D比值、BALF中IL-1β和TNF-α水平、p-p38 MAPK蛋白表达量降低，AQP1表达量升高(P<0.05)；LH组与LPS组时相点相比，大鼠肺组织病理评分、W/D比值、BALF中TNF-α和IL-1β水平、p-p38 MAPK蛋白表达量降低，AQP1表达量升高(P<0.05)；⑤每组时相点大鼠肺组织p38 MAPK表达量相比较无明显差异(P>0.05)。

①外源性hAMSCs能归巢并定植于受损伤肺组织；②hAMSCs可抑制p38 MAPK激活，减少炎症因子TNF-α、IL-1β释放，减轻肺部炎症反应；③hAMSCs静脉移植可上调肺组织AQP1表达，加强肺泡液体清除能力，减轻肺损伤。

To investigate the effect of the transplantation of human amniotic mesenchymal stem cell (hAMSCs) on the expressions of Aquaporin 1 (AQP1) and phosphorylated p38 mitogen activated protein kinase (p-p38MAPK) in lung tissue of rats with acute lung injury (ALI), and to further explore whether it can alleviate lung injury and its possible mechanism.

84 male SD rats were divided into 4 groups (n=21): normal saline control group (NS group), LPS induced ALI model group (LPS group), hAMSCs control group (NH group) and hAMSCs intervention group (LH group). The rats in LPS group and LH group were injected with LPS (4 mg/kg) through a sublingual vein to create models. NS group and NH group were injected with 250μl normal saline through a sublingual vein, and two hours later NH group and LH group were injected with 250μl DAP-labeled hAMSCs (2.5×10⁶) through a caudal vein. NS group and LPS group were injected with 250μl normal saline through a caudal vein. Seven rats in each group were killed at 6 h, 12 h and 72 h in order to observe the colonization of hAMSCs in the lung tissue of rats, the pathological morphology of lung tissue and the lung wet/dry weight (W/D) ratio. Furthermore, the levels of tumor necrosis factor-α (TNF-α) and interleukin- 1β (IL-1β) in bronchoalveolar lavage fluid(BALF) of rats in each group were detected by enzyme linked immunosorbent assay (ELISA). Immunohistochemistry (IHC) and western blot (WB) was used to detect the expressions of AQP1, p38 MAPK and p-p38 MAPK in the lung tissue of each group.

①Under the fluorescence microscope, it could be observed that there were blue fluorescent labeled hAMSCs around the alveoli of rats in NH and LH groups. Among them, the distribution of hAMSCs in LH group is more than that in NH group, indicating that hAMSCs can " homing" and colonize in the injured lung tissue. ②There was no significant difference in lung histopathological score, W/D ratio, TNF-α and IL-1 β levels in BALF, AQP1 and p-p38 MAPK protein expressions between NS group and NH group at each time point (P>0.05). ③Compared with the NS group and NH group at each time point, the LPS group and LH group showed an increase in lung histopathological score, W/D ratio, TNF-α and IL- 1 β levels in BALF, and p-p38 MAPK protein expression, and decrease in AQP1 expression at corresponding time points (P<0.05). ④Intra-group comparison of the LPS group revealed that there was no significant difference in lung histopathological score, W/D ratio, TNF-α and IL- 1 β levels in BALF, AQP1 and p-p38 MAPK protein expressions at the time points of 6 h and 12 h (P>0.05). Compared with LPS 6 h group and the LPS 12 h group, LPS 72 h group exhibited a decrease in lung histopathological score, W/D ratio, TNF-α and IL- 1 β levels in BALF, and p-p38 MAPK protein expression, and increase in AQP1 expression (P<0.05). Furthermore, there was no significant difference in lung histopathological score, W/D ratio, TNF-α and IL- 1 β levels in BALF, AQP1 and p-p38 MAPK protein expression between LH 6 h group and LH 12 h group (P>0.05). Compared with the 6 h and 12 h LH groups, LH 72 h group revealed a decrease in lung histopathological score, W/D ratio, TNF-α and IL- 1 β levels in BALF, and p-p38 MAPK protein expression, while the expression level of AQP1 was increased (P<0.05). Compared with the LPS group at each time point, lung histopathological score, W/D ratio, levels of TNF-α and IL-1β in BALF and expression of P-P38 MAPK protein were decreased in LH group, while AQP1 expression was increased (P<0.05). ⑤There were no significant difference in the expression of p38 MAPK in lung tissue at each time point among all groups (P>0.05).

①There is a homing and colonization of exogenous hAMSCs in the injured lung tissue. ②hAMSCs can inhibit the activation of p38 MAPK, decrease the release of inflammatory factors TNF-α and IL- 1β, and alleviate pulmonary inflammatory response. ③Intravenous transplantation of hAMSCs can upregulate the expression of AQP1 in lung tissue to enhance alveolar fluid clearance, so as to alleviate lung injury.