Department of Neurosurgery, The Second Affiliated Hospital, Jiangxi Medical College, Nanchang University, 1# Minde Road, Nanchang, Jiangxi, People's Republic of China.
Jiangxi Key Laboratory of Neurological Tumors and Cerebrovascular Diseases, Nanchang, China.
J Neuroinflammation. 2023 Dec 19;20(1):304. doi: 10.1186/s12974-023-02989-2.
Inflammasomes in astrocytes have been shown to play a crucial role in the pathogenesis of neurodegenerative diseases such as Parkinson's disease (PD) and Alzheimer's disease (AD). Cannabinoid Receptor 2(CB2R), a G protein-coupled receptor (GPCR), is considered a promising therapeutic target in inflammation-related disorders. This study aims to explore the role of CB2R in regulating NOD-like receptor family pyrin domain containing 3 (NLRP3)-mediated neuroinflammation in astrocytes.
In an in vivo animal model, specific targeting of astrocytic CB2R was achieved by injecting CB2R-specific adenovirus (or fork head box g1(foxg1) adenovirus) to knock down CB2R or administering CB2R agonists, inhibitors, etc., in the substantia nigra pars compacta (SNc) of mice. A PD mouse model was established using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induction. Animal behavioral tests, western blot, immunofluorescence, and other experiments were performed to assess the loss of midbrain tyrosine hydroxylase (TH) neurons, activation of astrocytes, and activation of the NLRP3 pathway. Primary astrocytes were cultured in vitro, and NLRP3 inflammasomes were activated using 1-methyl-4-phenylpyridinium (MPP) or lipopolysaccharide (LPS) and adenosine triphosphate (ATP). Western blot and ELISA experiments were conducted to assess the release of inflammatory factors. Transcriptomic sequencing and CUT&RUN techniques were employed to study the CB2R regulation of the foxg1 binding site on the autophagy molecule microtubule-associated protein 1 light chain 3 beta (MAP1LC3B).
Astrocytic CB2R knockdown impaired the motor abilities of MPTP-induced mice, exacerbated the loss of TH neurons, and induced activation of the NLRP3/Caspase-1/interleukin 1 (IL-1β) pathway. Activation of CB2R significantly alleviated motor impairments in mice while reducing NLRP3 deposition on astrocytes. In vitro cell experiments showed that CB2R activation attenuated the activation of the NLRP3/Caspase-1/IL-1β pathway induced by LPS + ATP or MPP. Additionally, it inhibited the binding of foxg1 to MAP1LC3B, increased astrocytic autophagy levels, and facilitated NLRP3 degradation through the autophagy-lysosome pathway.
Activation of CB2R on astrocytes effectively mitigates NLRP3-mediated neuroinflammation and ameliorates the disease characteristics of PD in mice. CB2R represents a potential therapeutic target for treating PD.
星形胶质细胞中的炎症小体在帕金森病（PD）和阿尔茨海默病（AD）等神经退行性疾病的发病机制中起着至关重要的作用。大麻素受体 2（CB2R），一种 G 蛋白偶联受体（GPCR），被认为是炎症相关疾病的有希望的治疗靶点。本研究旨在探讨 CB2R 在调节星形胶质细胞中 NOD 样受体家族 pyrin 结构域包含 3（NLRP3）介导的神经炎症中的作用。
在体内动物模型中，通过向小鼠黑质致密部（SNc）注射 CB2R 特异性腺病毒（或叉头框 G1（foxg1）腺病毒）来特异性靶向星形胶质细胞的 CB2R，以敲低 CB2R 或给予 CB2R 激动剂、抑制剂等，从而实现 CB2R 的下调或激活。使用 1-甲基-4-苯基-1,2,3,6-四氢吡啶（MPTP）诱导建立 PD 小鼠模型。进行动物行为测试、western blot、免疫荧光等实验，以评估中脑酪氨酸羟化酶（TH）神经元的丧失、星形胶质细胞的激活和 NLRP3 途径的激活。体外培养原代星形胶质细胞，用 1-甲基-4-苯基吡啶（MPP）或脂多糖（LPS）和三磷酸腺苷（ATP）激活 NLRP3 炎症小体。进行 western blot 和 ELISA 实验以评估炎症因子的释放。采用转录组测序和 CUT&RUN 技术研究 CB2R 对自噬分子微管相关蛋白 1 轻链 3 型β（MAP1LC3B）上的 foxg1 结合位点的调控。
星形胶质细胞 CB2R 敲低损害了 MPTP 诱导的小鼠的运动能力，加剧了 TH 神经元的丧失，并诱导 NLRP3/Caspase-1/白细胞介素 1β（IL-1β）途径的激活。CB2R 的激活显著减轻了小鼠的运动障碍，同时减少了 LPS+ATP 或 MPP 诱导的 NLRP3 在星形胶质细胞上的沉积。此外，它抑制了 foxg1 与 MAP1LC3B 的结合，增加了星形胶质细胞的自噬水平，并通过自噬溶酶体途径促进 NLRP3 的降解。
星形胶质细胞上 CB2R 的激活可有效减轻 NLRP3 介导的神经炎症，并改善 PD 小鼠的疾病特征。CB2R 是治疗 PD 的潜在治疗靶点。
