IL-1α、IL-6和IL-8通过MAPK通路介导内质网应激影响垂体激素分泌的分子机制研究

As always we think endocrine hypofunction in the low saddle tumor area is mainly caused by the tumor oppressionin the pituitary gland and the pituitary stalk.There was no significant difference inthe oppression on pituitary or pituitary stalk from craniopharyngioma and no functional pituitary adenomas, while higher incidence of endocrine disorders caused by craniopharyngioma,and the difference can not always be explained .This research found that: craniopharyngioma P2X7 receptor expression excessively can activate the MAPK pathway, leading to excessive expression of IL-1α、IL-6 and IL-8 .The relationship between over expression of inflammatory factors and endocrine function is very close and the former will cause the change of the internal environment with interfering with proper protein folding in ER and mitochondrial metabolism balance and leading to endoplasmic reticulum stress. Cell apoptosiscaused by incorrect protein folding and internal net stress may lead to low pituitary endocrine function.On this basis, this study proposes the following hypothesis: craniopharyngioma P2X7 receptor is supposed to activate MAPK pathway,leading to an increased the expression and release of IL-1α、IL-6 and IL-8, and lead to radical endoplasmic reticulum stress, leading to the decrease of the pituitary gland endocrine function and apoptosis. P2X7 receptor inhibitor can reduce the inflammation of craniopharyngioma, and adjust the endoplasmic reticulum stress, and then improve the endocrine function of pituitary gland.This study helps to further understand the regulation mechanism of the normal pituitary cell microenvironment on pituitary gland endoplasmic reticulum stress and apoptosis,which will provide new theoretical basis for improving the endocrine function.

既往认为鞍区肿瘤内分泌功能低下主要是垂体或血管受压迫所致。颅咽管瘤与无功能垂体腺瘤对垂体的压迫无显著差异，但内分泌功能障碍率较高，既往观点不能解释这种差异。本课题组发现颅咽管瘤的P2X7R的过表达能激活MAPK通路，导致IL-1α、IL-6和IL-8的释放增多。临床研究发现炎症因子的过表达与垂体前叶激素水平下降密切相关。炎症因子可干扰内质网蛋白质正确折叠,导致内质网应激和细胞凋亡。错误的蛋白质折叠和细胞凋亡均可导致垂体内分泌功能下降。据此，本研究提出如下假说：颅咽管瘤P2X7受体激活MAPK通路，导致IL-1α、IL-6和IL-8表达和释放增加，并导致内质网应激进而导致垂体前叶激素分泌功能下降。P2X7受体抑制剂能减少颅咽管瘤炎症，并调节内质网应激，进而改善内分泌功能。本研究有助于进一步了解垂体炎症微环境对细胞内质网应激及凋亡的调控机制，为改善颅咽管瘤患者内分泌功能提供新的理论依据。

背景：生长激素缺乏(GHD)在釉质上皮型颅咽管瘤(aCP)中的发生率明显高于其他鞍区肿瘤，但其可能的机制尚不清楚。.材料与方法：为诊断GHD，记录15例aCP患者胰岛素刺激试验后的体重指数(BMI)、胰岛素样生长因子-1(IGF-1)和生长激素峰值(GH)值。对aCP标本进行组织学染色。采用Millipore bead arrays检测肿瘤组织和细胞上清中9种促炎细胞因子的水平。在体内和体外观察IL-1α对生长激素分泌的影响。采用Western blot、qRT-PCR和细胞功能检测等方法，探讨IL-1α抑制生长激素分泌的可能机制。采用立体定向ALZET渗透泵技术模拟大鼠aCP促炎细胞因子的分泌。将重组IL-1α (rrIL-1α)和aCP细胞上清制备的条件培养基(CM)在28天内，以1 ul/h的速度直接注入大鼠鞍内，测定IL-1α对垂体病理改变和GH分泌的影响。为了进一步证实IL-1α是否通过IL-1R1影响GH分泌，从第1天至第28天皮下注射IL-1R1阻滞剂(IL-1R1a, 10 mg/kg体重，每日1次)。.结果：垂体纤维化与GHD呈显著正相关(rS=0.756, P=0.001)。许多细胞因子，特别是IL-1α、白细胞介素-8 (IL-8)和单核细胞趋化蛋白-1 (MCP-1)在肿瘤组织和细胞上清中升高。GHD组与No-GHD组间只有IL-1 -α差异有统计学意义(肿瘤组织中P＜0.001, F=6.251；细胞上清中P=0.003, F=1.529)。IL-1α显著降低了GH3和周细胞共培养时GH的分泌。IL-1α介导的周细胞活化是通过IL-1R1信号通路介导的。在体内IL-1α诱导垂体纤维化，进而导致GH水平下降。这种病理变化被IL-1R1a拮抗。.结论：本研究发现，aCP细胞与垂体间质细胞即周细胞之间的联系是GHD形成的重要因素，我们提出，中和IL-1α的下游信号可能是aCP中GHD的潜在治疗方法。