Chen Yuhua, Meng Jiao, Bi Fangfang, Li Hua, Chang Cuicui, Ji Chen, Liu Wei
Department of Central Laboratory, Xi'an Peihua University, Xi'an, China.
Department of Neurosurgery, the Second Affiliated Hospital of Xi'an Medical University, Xi'an, China.
Front Mol Neurosci. 2019 Aug 29;12:202. doi: 10.3389/fnmol.2019.00202. eCollection 2019.
As one of the most common causes of mortality and disability, traumatic brain injury (TBI) is a huge psychological and economic burden to patients, families, and societies worldwide. Neuroinflammation reduction may be a favorable option to alleviate secondary brain injuries and ameliorate the outcome of TBI. The nucleotide-binding oligomerization domain, leucine-rich repeat and pyrin domain-containing 3 (NLRP3) inflammasome, has been shown to be involved in TBI. NIMA-related kinase 7 (NEK7) has been verified as an essential mediator of NLRP3 inflammasome activation that is recruited upstream of the formation of inflammasomes in response to NLRP3 activators. However, the underlying mechanism by which NEK7 operates post-TBI remains undefined. In this study, we performed both and experiments. Using an mouse TBI model, mice were administered an intracerebroventricular injection of NEK7-shRNA virus. For the analysis, primary cortical neurons with NEK7-shRNA were stimulated with lipopolysaccharide (LPS)/ATP or potassium (K). We evaluated the effects of NEK7 knock-down on neurological deficits, NLRP3 inflammasomes, caspase-1 activation, and neuronal injury. During the 0-168 h post-TBI period , NEK7 and NLRP3 inflammasome activation increased in what appeared to be a time-dependent manner. As well as pyroptosis-related markers, caspase-1 activation (p20) and interleukin-1β (IL-1β) activation (p17) were up-regulated. NEK7 down-regulation attenuated neurological deficits, NLRP3 inflammasomes, caspase-1 activation, and neuronal injury. The same phenomena were observed during the experiments. Furthermore, NEK7 knock-down suppressed NLRP3 inflammasome activation and pyroptosis, which were triggered by K efflux, and the LPS + ATP-triggered NEK7-NLRP3 complex was reversed in primary cortical neurons placed in 50 mM K medium. Collectively, the data demonstrated that NEK7, as a modulator, regulates NLRP3 inflammasomes and downstream neuroinflammation in response to K efflux, through NEK7-NLRP3 assembly, pro-caspase-1 recruitment, caspase-1 activation, and pyroptosis in nerve injuries, post-TBI. NEK7 may be a potential therapeutic target for attenuating neuroinflammation and nerve injury post-TBI.
作为导致死亡和残疾的最常见原因之一，创伤性脑损伤（TBI）给全球范围内的患者、家庭和社会带来了巨大的心理和经济负担。减轻神经炎症可能是减轻继发性脑损伤和改善TBI预后的一个有利选择。含核苷酸结合寡聚化结构域、富含亮氨酸重复序列和吡啉结构域3（NLRP3）炎性小体已被证明与TBI有关。NIMA相关激酶7（NEK7）已被证实是NLRP3炎性小体激活的关键介质，在响应NLRP3激活剂时，它在炎性小体形成的上游被招募。然而，TBI后NEK7发挥作用的潜在机制仍不明确。在本研究中，我们进行了体内和体外实验。使用小鼠TBI模型，通过脑室内注射NEK7-shRNA病毒处理小鼠。对于体外分析，用脂多糖（LPS）/ATP或钾（K）刺激转染NEK7-shRNA的原代皮质神经元。我们评估了敲低NEK7对神经功能缺损、NLRP3炎性小体、半胱天冬酶-1激活和神经元损伤的影响。在TBI后的0-168小时内，NEK7和NLRP3炎性小体的激活呈时间依赖性增加。除了与焦亡相关的标志物外，半胱天冬酶-1激活（p20）和白细胞介素-1β（IL-1β）激活（p17）也上调。NEK7下调减轻了神经功能缺损、NLRP3炎性小体、半胱天冬酶-1激活和神经元损伤。在体外实验中也观察到了相同的现象。此外，敲低NEK7抑制了由钾外流触发的NLRP3炎性小体激活和焦亡，并且在置于50 mM K培养基中的原代皮质神经元中，LPS + ATP触发的NEK7-NLRP3复合物被逆转。总体而言，数据表明，作为一种调节因子，NEK7通过NEK7-NLRP3组装、前半胱天冬酶-1募集、半胱天冬酶-1激活和神经损伤后TBI中的焦亡，响应钾外流调节NLRP3炎性小体和下游神经炎症。NEK7可能是减轻TBI后神经炎症和神经损伤的潜在治疗靶点。
