Gadd45b基因高表达致MAPK通路活化是百草枯中毒肺损伤的重要机制

Paraquat(PQ) has extremely high mortality because of respiratory failure. Thus, to investigate the mechanism of PQ induced acute lung injury is very crucial to PQ intoxication therapy. In previous study, we used a new microarray with full transcription of genes to detect gene profile of lung tissues in PQ intoxicated mice, and applied bioinformatics techniques to discover that MAPK signaling pathway regulated by an important gene called Gadd45b is the core pathway in PQ induced acute lung injury; the results of PCR and western had proved that the expression of Gadd45b got high levels in PQ intoxicated lungs; also, injury lungs had high expression of phosphorylated P38, ERK and JNK MAPK; according to investigation progress of Gadd45b and the effects of MAPK pathway on acute lung injury induced by other reasons;the expression of Gadd45b increased significantly in serum samples of PQ intoxicated patients when comparing to healthy controls, we come up with this theory that MAPK signaling pathway activated by Gadd45b overexpression is the major mechanism of PQ induced acute lung injury. For further study, we will first try to find the possible role which Gadd45b plays in PQ induced acute lung injury; and then,to investigate the effects of Gadd45b on MAPK pathway and the relationship between Gadd45b expression and PQ induced acute lung injury. This study will deepen the recognition to the machanism of PQ induced lung injury, and provide a new view angle and evidence to find the possible way for PQ intoxication treatment by interfering in Gadd45b expression and inhibiting MAPK signaling pathway.

百草枯（PQ）中毒死亡率极高，首要死因为呼吸衰竭。故阐明PQ中毒致肺损伤机制是抢救成功的关键。我们前期采用新型全转录本基因芯片检测PQ中毒小鼠肺组织全基因转录表达谱，经信息学分析确立：Gadd45b是PQ肺损伤的关键核心基因；MAPK为核心信号通路，有趣的是Gadd45b是MAPK上游调控基因；PQ肺组织Gadd45b及P38、ERK、JNK MAPK磷酸化水平均明显增高；PQ中毒患者血清Gadd45b水平亦增高。据此前期结果结合Gadd45b研究进展我们认为：Gadd45b基因高表达致MAPK通路活化是PQ致肺损伤的主要机制。为验证该推断，拟首先确立Gadd45b在PQ中毒肺损伤程度中的作用，然后探索Gadd45b表达对MAPK通路的影响及与肺泡上皮细胞损伤的关系。本研究不仅深化了对PQ中毒肺损伤机理认识，还为研究基于干预Gadd45b和阻断MAPK信号通路的PQ中毒治疗新方案提供依据。

百草枯（PQ）中毒死亡率极高，首要死因为呼吸衰竭。故阐明PQ中毒致肺损伤机制是抢救成功的关键。前期基因芯片结果提示Gadd45b是PQ肺损伤的关键核心基因；MAPK为核心信号通路，Gadd45b可能是MAPK上游调控基因；PQ肺组织Gadd45b及P38、ERK、JNK MAPK磷酸化水平均明显增高；因此推测Gadd45b基因高表达致MAPK通路活化是PQ致肺损伤的主要机制。然而，通过建立体内外PQ中毒模型，结果发现MAPK各通路抑制剂均不能改善PQ中毒致急性肺损伤，亦不能影响PQ中毒急性肺损伤小鼠肺组织及肺上皮细胞中Gadd45b的表达，因此，不能证明之前的推测。从而进一步基于原基因芯片结果（Toll样受体信号通路可能参与PQ中毒肺损伤），改研究目标为观察Toll样受体通路是否参与PQ中毒急性肺损伤，经细胞实验发现Toll样受体通路抑制剂仍不能影响PQ致肺上皮细胞Gadd45b的发达。提示PQ中毒致急性肺损伤的分子机制可能与Gadd45b有关，但进一步机制仍需探索。转换研究思路，通过斑马鱼试验，发现PQ可诱导斑马鱼氧化应激基因表达，诱导细胞凋亡、激活巨噬细胞；并提示斑马鱼模型在PQ中毒机制研究中有着很好的前景，并可用于抗氧化药物筛选。同时，基于临床数据，通过相关性分析、生存率分析、回归分析等各种方法进一步研究发现：PQ中毒出现的急性肾损伤以及中毒8天内出现的纵膈气肿均可做为百草枯死亡率的预测指标；尿视黄醇结合蛋白可能为PQ致急性肾损伤的早期损伤指标；RIFLE和KDIGO诊断标准更适合用于PQ中毒相关AKI的诊断及其预后判断，从而可有助于临床PQ的早期防治。同时，应用超声造影技术评估血尿酸对糖尿病肾损伤患者肾脏微血流灌注的影响，以及评估早期糖尿病肾损伤患者肾脏微血流灌注情况。结果发现高尿酸可能增加糖尿病肾损伤的肾脏血流灌注，曲线下面积是评估肾血流灌注的良好指标；下降段曲线下面积可能是糖尿病早期肾损伤及高灌注的敏感指标，该技术有利于临床疗效、病情评估及随访。