Cannabinoid receptor 2 (CB₂) is a promising therapeutic target for immunological modulation. There is, however, a deficit of knowledge regarding CB₂ signaling and function in human primary immunocompetent cells. We applied an experimental paradigm which closely models the in situ state of human primary leukocytes (PBMC; peripheral blood mononuclear cells) to characterize activation of a number of signaling pathways in response to a CB₂-selective ligand (HU308). We observed a “lag” phase of unchanged cAMP concentration prior to development of classically expected Gα_i-mediated inhibition of cAMP synthesis. Application of G protein inhibitors revealed that this apparent lag was a result of counteraction of Gα_i effects by concurrent Gα_s activation. Monitoring downstream signaling events showed that activation of p38 was mediated by Gα_i, whereas ERK1/2 and Akt phosphorylation were mediated by Gα_i-coupled βγ. Activation of CREB integrated multiple components; Gα_s and βγ mediated ∼85% of the response, while ∼15% was attributed to Gα_i. Responses to HU308 had an important functional outcome—secretion of interleukins 6 (IL-6) and 10 (IL-10). IL-2, IL-4, IL-12, IL-13, IL-17A, MIP-1α, and TNF-α were unaffected. IL-6/IL-10 induction had a similar G protein coupling profile to CREB activation. All response potencies were consistent with that expected for HU308 acting via CB₂. Additionally, signaling and functional effects were completely blocked by a CB₂-selective inverse agonist, giving additional evidence for CB₂ involvement. This work expands the current paradigm regarding cannabinoid immunomodulation and reinforces the potential utility of CB₂ ligands as immunomodulatory therapeutics.

中文翻译：

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通过G-alpha-s的大麻素受体2（CB ₂）信号并诱导人原代白细胞中IL-6和IL-10细胞因子的分泌

大麻受体2（CB ₂）是一种有希望的免疫调节治疗靶标。然而，关于人原代免疫能力细胞中CB ₂信号传导和功能的知识缺乏。我们应用了一种实验模型，该模型紧密模拟了人类原代白细胞（PBMC；外周血单核细胞）的原位状态，以表征响应CB ₂选择性配体（HU308）的许多信号通路的活化。我们之前经典预期Gα的发展观察到不变的cAMP浓度的“滞后”相_我介导的cAMP合成的抑制。G蛋白抑制剂的应用表明，这种明显的滞后是Gα对抗作用的结果_我效果并发Gα_小号活化。监测下游信号传导事件的p38显示的激活是由Gα介导的_我，而ERK1 / 2和Akt的磷酸化是由Gα介导的_我-偶联βγ。激活CREB集成了多个组件；Gα_小号和βγ介导〜85的响应的％，而〜15％归因于Gα_我。对HU308的反应具有重要的功能结局-白细胞介素6（IL-6）和10（IL-10）的分泌。IL-2，IL-4，IL-12，IL-13，IL-17A，MIP-1α和TNF-α不受影响。IL-6 / IL-10诱导具有与CREB激活相似的G蛋白偶联特性。所有响应强度均与通过CB ₂进行的HU308预期响应一致。另外，CB ₂选择性反向激动剂完全阻断了信号传导和功能作用，为CB ₂参与提供了更多证据。这项工作扩展了当前有关大麻素免疫调节的范例，并增强了CB ₂配体作为免疫调节治疗剂的潜在效用。