State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China.
State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China.
Kidney Int. 2018 Oct;94(4):756-772. doi: 10.1016/j.kint.2018.05.023. Epub 2018 Aug 6.
The cannabinoid receptor type 2 (CB2) is a G protein-coupled seven transmembrane receptor that transmits endogenous cannabinoid signaling. The role of CB2 in the pathogenesis of kidney injury and fibrosis remains poorly understood. Here we demonstrate that CB2 was induced, predominantly in kidney tubular epithelium, in various models of kidney disease induced by unilateral ureteral obstruction, adriamycin or ischemia/reperfusion injury. In vitro, forced expression of CB2 or treatment with a CB2 agonist was sufficient to trigger matrix gene expression, whereas knockdown of CB2 by siRNA abolished transforming growth factor-β1-induced signaling and fibrogenic responses in kidney tubular cells. CB2 also mediated fibroblasts and macrophage activation in vitro. Mice with genetic ablation of CB2 were protected against kidney injury after ureteral obstruction, validating a pathogenic role of CB2 in renal fibrosis in vivo. By using in silico screening and medicinal chemistry modifications, we discovered a novel compound, XL-001, that bound to CB2 with high affinity and selectivity and acted as an inverse agonist. Incubation with XL-001 inhibited in a dose-dependent fashion the fibrogenic response induced by CB2 overexpression, CB2 agonist or transforming growth factor-β1. In vivo, intraperitoneal injections of XL-001 ameliorated kidney injury, fibrosis and inflammation in both the obstruction and ischemia/reperfusion models. Delayed administration of XL-001 was also effective in ameliorating kidney fibrosis and inflammation. Thus, CB2 is a pathogenic mediator in kidney fibrosis and targeted inhibition with the novel inverse agonist XL-001 may provide a strategy in the fight against fibrotic kidney diseases.
大麻素受体 2（CB2）是一种 G 蛋白偶联的七次跨膜受体，它传递内源性大麻素信号。CB2 在肾脏损伤和纤维化发病机制中的作用仍知之甚少。在这里，我们证明在单侧输尿管梗阻、阿霉素或缺血/再灌注损伤引起的各种肾脏疾病模型中，CB2 主要在肾小管上皮细胞中被诱导。在体外，CB2 的强制表达或用 CB2 激动剂治疗足以引发基质基因表达，而用 siRNA 敲低 CB2 则可消除转化生长因子-β1 诱导的肾小管细胞中的信号转导和纤维生成反应。CB2 还在体外介导成纤维细胞和巨噬细胞的激活。CB2 基因敲除的小鼠在输尿管梗阻后免受肾脏损伤，这验证了 CB2 在体内肾纤维化中的致病作用。通过使用计算机筛选和药物化学修饰，我们发现了一种新型化合物 XL-001，它与 CB2 具有高亲和力和选择性，并作为反向激动剂。XL-001 的孵育以剂量依赖性方式抑制 CB2 过表达、CB2 激动剂或转化生长因子-β1 诱导的纤维生成反应。在体内，XL-001 的腹腔注射在梗阻和缺血/再灌注模型中均改善了肾脏损伤、纤维化和炎症。XL-001 的延迟给药也可有效改善肾脏纤维化和炎症。因此，CB2 是肾脏纤维化的一种致病介质，新型反向激动剂 XL-001 的靶向抑制可能为抗纤维化肾脏疾病提供一种策略。
