外源性精胺对百草枯致肺损伤的保护效应及其机制的研究

The main clinical features of patients with acute paraquat（PQ） poisoning is widespread pulmonary fibrosis followed behind acute lung injury (ALI) and then eventually respiratory failure and death, which is related to active accumulation of PQ in the lungs via polyamine transport system (PTS). It is extremely urgent seeking specific antidotes for PQ due to poor treatment effect and high mortality rate after acute PQ poisoning. For PQ to cause ALI is attributed to the active accumulation of PQ against a concentration gradient in the pulmonary cells via PTS in pulmonary cellular membrane. PQ and polyamine are uptaked in the same way, which is PTS.There is the inherent antagonistic mechanism of lung uptaking paraquat in vivo.Endogenous spermine, which is very similar with PQ in the molecular structure, can suppress PQ uptaking into lung tissue cells.We can assume it is feasible increasing concentration of spermine to suppress PQ intake into the lung cells which will block its toxic effect on cells can reduce lung injury and pulmonary fibrosis caused by PQ.Our research team found in the preliminary experiments that exogenous spermine can reduce the degree of acute lung injury and pulmonary fibrosis caused by PQ in rats,but the mechanism is not yet entirely clear. We will have the integrated research about acute PQ poisoning mechanism and exogenous spermine intervention therapy, which may provide a new target and the starting point for treatment of acute PQ poisoning. It is the main line of studies for PQ to cause ALI and pulmonary fibrosis, protective effect of exogenous spermine on lung injury PQ-induced and its time-effect and dose-effect relationship, effect of exogenous spermine on TGF-β and monocyte-macrophage.

百草枯（PQ）毒性强，中毒后救治效果差、病死率高，寻求特效解毒药物迫在眉睫。肺细胞膜存在能主动摄取PQ 的多胺转运系统（PTS），致使PQ聚集于肺而致肺损伤。PQ与多胺的摄取途径同为PTS。机体存在固有的拮抗肺摄取PQ的机制，内源性精胺由于与PQ结构相似，因而可与PQ相互竞争PTS进入肺细胞。可以设想在PQ中毒早期，补充外源性精胺以提高体内多胺浓度，通过与PQ竞争PTS来阻止肺细胞摄取PQ，达到减轻PQ致肺损伤目的。我们前期实验发现，精胺可减轻PQ中毒大鼠急性肺损伤及肺纤维化程度并延长动物存活时间。本项目拟围绕PQ中毒作用机制和外源性精胺对PQ中毒治疗效应及机制这一核心科学问题，以PQ致肺损伤、纤维化、外源性精胺对PQ致肺损伤保护效应的时效、量效关系，以及对TGF-β和单核巨噬细胞影响为研究主线，对急性PQ中毒机制及外源性精胺干预进行整合性研究，为PQ中毒治疗提供新的理论和实验依据。

百草枯（PQ）毒性强，中毒后救治效果差、病死率高，寻求特效解毒药物迫在眉睫。肺细胞膜存在能主动摄取PQ 的多胺转运系统（PTS），致使PQ聚集于肺而致肺损伤。PQ与多胺的摄取途径同为PTS。机体存在固有的拮抗肺摄取PQ的机制，内源性精胺由于与PQ结构相似，因而可与PQ相互竞争PTS进入肺细胞。可以设想在PQ中毒早期，补充外源性精胺以提高体内多胺浓度，通过与PQ竞争PTS来阻止肺细胞摄取PQ，达到减轻PQ致肺损伤目的。我们前期实验发现，精胺可减轻PQ中毒大鼠急性肺损伤及肺纤维化程度并延长动物存活时间。本项目围绕PQ中毒作用机制和外源性精胺对PQ中毒治疗效应及机制这一核心科学问题，以PQ致肺损伤、纤维化、外源性精胺对PQ致肺损伤保护效应的时效、量效关系，以及对TGF-β和单核巨噬细胞影响为研究主线，对急性PQ中毒机制及外源性精胺干预进行整合性研究，为PQ中毒治疗提供新的理论和实验依据。得出以下重要结果：1.动物实验方面：外源性精胺可有效减轻百草枯所致肺损害从而降低百草枯染毒大鼠死亡率，与精胺可抑制百草枯染毒大鼠肺组织MDA、TGF-β1的高表达，且可明显增高SOD水平有关。关键数据：PQ+S组（精胺干预组）10天内死亡率（13.3%）明显低于PQ中毒模型组（死亡率为36.6%）；3d肺W/D，与PQ组（6.79±0.61）比较，PQ+S组（5.65±0.36）显著下降(P＜0.05)；3d 肺组织病理切片HE染色比较，PQ+S组明显轻于PQ中毒模型组；14天肺组织病理切片Masson染色比较，PQ+S组肺纤维化明显轻于PQ模型组；3d 肺组织匀浆中丙二醛(MDA)含量，PQ+S组（6.37±0.49nmol/ml）明显低于PQ中毒（7.45±0.36nmol/ml），超氧化物歧化酶(SOD)含量PQ+S组（196.56±14.78U/ml）明显高于PQ中毒组（152.33±13.64U/ml），肺组织匀浆中TGF-β1 含量PQ+S组（ 66.36±9.28pg/ml）明显低于PQ中毒组（123.78±26.86pg/ml）。2. 细胞生物学实验方面：外源性精胺对百草枯所致肺泡细胞损伤的保护及其机制探究。关键数据：PQ+S组（精胺干预组）肺泡细胞活力（87.8%）明显高于PQ中毒模型组（50%）；PQ+S组改善PQ对细胞超微结构的损害，减少细胞凋亡率等。