A new cell death program regulated by toll-like receptor 9 through p38 mitogen-activated protein kinase signaling pathway in a neonatal rat model with sepsis associated encephalopathy.
A new cell death program regulated by toll-like receptor 9 through p38 mitogen-activated protein kinase signaling pathway in a neonatal rat model with sepsis associated encephalopathy.
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DOI：
10.1097/cm9.0000000000002010
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发表时间：
2022-06-20
影响因子：
6.1
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中科院分区：
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脓毒症是一种严重的病死率高的疾病，通常会导致败血症相关性脑病(SAE)，涉及神经细胞死亡。然而，涉及的细胞死亡程序及其潜在的机制尚不清楚。本研究旨在探讨不同细胞死亡程序在SAE中的调控机制。采用盲肠结扎穿孔法制备新生大鼠SAE模型。监测存活率和生命体征(平均动脉压和心率)，评估神经反射，苏木精-伊红染色观察皮质病理改变。检测上睑下垂、细胞凋亡和坏死性下垂相关蛋白、丝裂原活化蛋白激酶(MAPK)及其上游调控因子Toll样受体9(TLR9)的表达。免疫荧光染色观察TLR9在神经元中的表达。用透射电子显微镜观察神经元的超微结构。首先，SAE大鼠的大脑皮层神经细胞中发现了PANO。同时，MAPKs、p38MAPK、Jun氨基末端激酶和细胞外信号调节激酶(ERK)亚基被激活。在药物抑制了每一个亚基后，只有p38MAPK被发现与泛音脱垂有关。此外，阻断p38MAPK信号通路激活了坏死性下垂，但抑制了细胞凋亡和下垂。当坏死性下垂被药物抑制时，细胞凋亡和下垂被重新激活。最后，我们发现MAPKs的调节因子TLR9在该模型中的表达显著增加。TLR9下调后，p38MAPK和ERK信号通路被抑制，从而导致PANossis的抑制。进一步分析发现，下调TLR9可提高SAE大鼠的存活率，减轻其病理改变。我们的研究表明，在SAE大鼠中，组成PANposis的程序同时被激活。TLR9通过p38MAPK信号通路激活PANosis。TLR9可能成为SAE治疗的潜在靶点。
Sepsis, a serious condition with high mortality, usually causes sepsis associated encephalopathy (SAE) that involves neuronal cell death. However, the cell death programs involved and their underlying mechanisms are not clear. This study aimed to explore the regulatory mechanisms of different cell death programs in SAE. A neonatal rat model of SAE was established by cecal ligation and perforation. Survival rate and vital signs (mean arterial pressure and heart rate) were monitored, nerve reflexes were evaluated, and cortical pathological changes were observed by hematoxylin and eosin staining. The expression of pyroptosis, apoptosis, and necroptosis (PANoptosis)-related proteins, mitogen- activated protein kinase (MAPK), and its upstream regulator toll-like receptor 9 (TLR9) were detected. The expression of TLR9 in neurons was observed by immunofluorescence staining. The ultrastructure of neurons was observed by transmission electron microscope. First, PANoptosis was found in cortical nerve cells of the SAE rats. Meanwhile, the subunits of MAPKs, p38 MAPK, Jun N- terminal kinase, and extracellular signal-regulated kinase (ERK) were activated. After pharmacologically inhibiting each of the subunits, only p38 MAPK was found to be associated with PANoptosis. Furthermore, blocking the p38 MAPK signaling pathway activated necroptosis but inhibited apoptosis and pyroptosis. When necroptosis was pharmacologically inhibited, apoptosis and pyroptosis were reactivated. Finally, we found that the expression of TLR9, a regulator of MAPKs, was significantly increased in this model. After down-regulation of TLR9, p38 MAPK, and ERK signaling pathways were inhibited, which led to the inhibition of PANoptosis. Further analysis found that down-regulation of TLR9 improved the survival rate and reduced the pathological changes in SAE rats. Our study showed that the programs comprising PANoptosis are activated simultaneously in SAE rats. TLR9 activated PANoptosis through the p38 MAPK signaling pathway. TLR9 may work as a potential target for SAE treatment.