Neuroinflammation has been shown to exacerbate ischemic brain injury, and is considered as a prime target for the development of stroke therapies. Clinacanthus nutans Lindau (C. nutans) is widely used in traditional medicine for treating insect bites, viral infection and cancer, due largely to its anti-oxidative and anti-inflammatory properties. Recently, we reported that an ethanol extract from the leaf of C. nutans could protect the brain against ischemia-triggered neuronal death and infarction. In order to further understand the molecular mechanism(s) for its beneficial effects, two experimental paradigms, namely, in vitro primary cortical neurons subjected to oxygen–glucose deprivation (OGD) and in vivo rat middle cerebral artery (MCA) occlusion, were used to dissect the anti-inflammatory effects of C. nutans extract. Using promoter assays, immunofluorescence staining, and loss-of-function (siRNA) approaches, we demonstrated that transient OGD led to marked induction of IL-1β, IL-6 and TNFα, while pretreatment with C. nutans suppressed production of inflammatory cytokines in primary neurons. C. nutans inhibited IL-1β transcription via preventing NF-κB/p65 nuclear translocation, and siRNA knockdown of either p65 or IL-1β mitigated OGD-mediated neuronal death. Correspondingly, post-ischemic treatment of C. nutans attenuated IκBα degradation and decreased IL-1β, IL-6 and TNFα production in the ischemic brain. Furthermore, IL-1β siRNA post-ischemic treatment reduced cerebral infarct, thus mimicking the beneficial effects of C. nutans. In summary, our findings demonstrated the ability for C. nutans to suppress NF-κB nuclear translocation and inhibit IL-1β transcription in ischemic models. Results further suggest the possibility for using C. nutans to prevent and treat stroke patients.

神经炎症已被证明会加剧缺血性脑损伤，并被认为是开发中风疗法的主要目标。Clinacanthus nutans Lindau ( C. nutans ) 在传统医学中被广泛用于治疗昆虫叮咬、病毒感染和癌症，主要是由于其抗氧化和抗炎特性。最近，我们报道了一种从C. nutans叶中提取的乙醇提取物可以保护大脑免受缺血引发的神经元死亡和梗塞。为了进一步了解其有益作用的分子机制，使用了两种实验范式，即经历氧-葡萄糖剥夺（OGD）的体外原代皮层神经元和体内大鼠大脑中动脉（MCA）闭塞。剖析C. nutans提取物的抗炎作用。使用启动子测定、免疫荧光染色和功能丧失 (siRNA) 方法，我们证明瞬时 OGD 导致 IL-1β、IL-6 和 TNFα 的显着诱导，而用C. nutans预处理抑制了炎症细胞因子的产生初级神经元。C. nutans通过阻止 NF-κB/p65 核易位来抑制 IL-1β 转录，并且 p65 或 IL-1β 的 siRNA 敲低减轻了 OGD 介导的神经元死亡。相应地，C. nutans的缺血后处理减弱了 IκBα 降解并减少了缺血脑中 IL-1β、IL-6 和 TNFα 的产生。此外，IL-1β siRNA 缺血后治疗可减少脑梗塞，从而模拟C. nutans的有益作用。总之，我们的研究结果证明了C. nutans在缺血模型中抑制 NF-κB 核易位和抑制 IL-1β 转录的能力。结果进一步表明使用C. nutans预防和治疗中风患者的可能性。