Ke Ping, Shao Bo-Zong, Xu Zhe-Qi, Wei Wei, Han Bin-Ze, Chen Xiong-Wen, Su Ding-Feng, Liu Chong
Department of Pharmacology, School of Pharmacy, Second Military Medical University, Shanghai, China.
Institute of Quality and Standard for Agro-products, Zhejiang Academy of Agricultural Sciences; Hangzhou, Zhejiang, China.
PLoS One. 2016 Sep 9;11(9):e0155076. doi: 10.1371/journal.pone.0155076. eCollection 2016.
Activation of cannabinoid receptor 2 (CB2R) ameliorates inflammation, but the underlying mechanism remains unclear. In the present study, we examined whether activation of CB2R could suppress the nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3) inflammasome. In peritoneal macrophages isolated from C57BL/6 mice, LPS/DSS challenge for 24 h increased the expression of the components of NLRP3 inflammasome NLRP3, Casp-1 p20/Casp-1 p45 ratio, proIL-1β and IL-1β and also enhanced autophagy (LC3-II/LC3-I ratio, Beclin-1 and SQSTM1). Pretreatment of peritoneal macrophages with HU 308, a selective CB2R agonist, attenuated LPS/DSS-induced NLRP3 inflammasome activation, but further enhanced autophagy. In comparison with wild-type (WT) control, peritoneal macrophages from CB2R knockout (KO) mice had more robust NLRP3 inflammasome activation and attenuated autophagy upon LPS/DSS challenge. Knockdown autophagy-related gene 5 (Atg5) with a siRNA in peritoneal macrophages attenuated the inhibitory effects of HU 308 on LPS/DSS-induced NLRP3 inflammasome activation in vitro. In vivo, HU308 treatment attenuated DSS-induced colitis mice associated with reduced colon inflammation and inhibited NLRP3 inflammasome activation in wild-type mice. In CB2R KO mice, DSS-induced inflammation and NLRP3 inflammasome activation were more pronounced than those in WT control. Finally, we demonstrated that AMPK-mTOR-P70S6K signaling pathway was involved in this CB2R-mediated process. We conclude that activation of CB2R ameliorates DSS-induced colitis through enhancing autophagy that may inhibit NLRP3 inflammasome activation in macrophages.
大麻素受体2（CB2R）的激活可改善炎症反应，但其潜在机制仍不清楚。在本研究中，我们检测了CB2R的激活是否能抑制核苷酸结合寡聚化结构域样受体蛋白3（NLRP3）炎性小体。在从C57BL/6小鼠分离的腹腔巨噬细胞中，LPS/DSS刺激24小时可增加NLRP3炎性小体成分NLRP3、Casp-1 p20/Casp-1 p45比值、前白细胞介素-1β（proIL-1β）和白细胞介素-1β（IL-1β）的表达，同时也增强了自噬（LC3-II/LC3-I比值、Beclin-1和SQSTM1）。用选择性CB2R激动剂HU 308预处理腹腔巨噬细胞可减弱LPS/DSS诱导的NLRP3炎性小体激活，但进一步增强了自噬。与野生型（WT）对照相比，CB2R基因敲除（KO）小鼠的腹腔巨噬细胞在LPS/DSS刺激后具有更强的NLRP3炎性小体激活和减弱的自噬。用小干扰RNA（siRNA）敲低腹腔巨噬细胞中自噬相关基因5（Atg5）可减弱HU 308对LPS/DSS诱导体外NLRP3炎性小体激活的抑制作用。在体内，HU308治疗减轻了DSS诱导的结肠炎小鼠的结肠炎症，并抑制了野生型小鼠中NLRP3炎性小体的激活。在CB2R KO小鼠中，DSS诱导的炎症和NLRP3炎性小体激活比WT对照更明显。最后，我们证明AMPK-mTOR-P70S6K信号通路参与了这一CB2R介导的过程。我们得出结论，CB2R的激活通过增强自噬改善DSS诱导的结肠炎，自噬可能抑制巨噬细胞中NLRP3炎性小体的激活。
