AIMS To investigate the therapeutic effects of human amniotic mesenchymal stem cells (hAMSCs) on paraquat (PQ)-induced pulmonary fibrosis in rats and investigate the inflammatory mechanisms. MAIN METHODS hAMSCs were identified by morphological, flow cytometry and immunocytochemistry. A pulmonary fibrosis model was induced by administering PQ to rats. The hAMSCs group was treated with hAMSCs after 6 h of PQ poisoning. At 21 days after hAMSCs transplantation, lungs were harvested for H&E, Masson and immunohistochemical staining to evaluate pulmonary histopathology, collagen deposition, CD3+ cell infiltration and hAMSCs colonization. Arterial blood was used for lactic acid analysis and venous blood was used to detect TNF-α, IL-6, and TGF-β1 by ELISA method. KEY FINDINGS hAMSCs can improve the lung structure and decrease collagen deposition induced by PQ. The membranes of CD3+ T cell in the PQ group were round and complete, while that in the hAMSCs group rats exhibited punctate or diffuse staining. In addition, the CD3+ cell was decreased by hAMSCs administration, and MAB1281-positive cells were detected in lung of hAMSCs group rats. The survival rate of the hAMSCs group was significantly higher than that of the PQ group at 21 days after injection. TNF-α, IL-6, TGF-β1 and lactic acid were significantly decreased by hAMSCs administration. SIGNIFICANCE hAMSCs have a significant therapeutic effect on pulmonary fibrosis induced by acute PQ poisoning and can improve survival rate in rats. Furthermore, hAMSCs administration can improve lung histopathology and reduce collagen deposition by reducing inflammatory CD3+ T cell infiltration, inflammatory cytokine expression and lactic acid levels.

中文翻译：

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人羊膜间充质干细胞通过抑制炎症反应减轻百草枯诱导的大鼠肺纤维化。

目的探讨人羊膜间充质干细胞（hAMSCs）对百草枯（PQ）诱导的大鼠肺纤维化的治疗作用，并探讨其炎症机制。主要方法通过形态学，流式细胞术和免疫细胞化学鉴定hAMSC。通过对大鼠施用PQ来诱导肺纤维化模型。PQ中毒6 h后，用hAMSC治疗hAMSCs组。hAMSCs移植后第21天，收集肺进行H＆E，Masson和免疫组织化学染色，以评估肺的组织病理学，胶原蛋白沉积，CD3 +细胞浸润和hAMSCs定植。动脉血用于乳酸分析，静脉血用于通过ELISA方法检测TNF-α，IL-6和TGF-β1。主要发现hAMSCs可改善肺部结构并减少PQ诱导的胶原蛋白沉积。PQ组的CD3 + T细胞膜圆而完整，而hAMSCs组的大鼠则呈点状或弥漫性染色。此外，hAMSCs给药后CD3 +细胞减少，并且在hAMSCs组大鼠的肺中检测到MAB1281阳性细胞。注射后21天，hAMSCs组的存活率显着高于PQ组。hAMSCs给药后，TNF-α，IL-6，TGF-β1和乳酸显着降低。意义hAMSC对急性PQ中毒引起的肺纤维化具有显着的治疗作用，并且可以提高大鼠的存活率。此外，