Cannabinoid Receptor 2 (CB2) Signals via G-alpha-s and Induces IL-6 and IL-10 Cytokine Secretion in Human Primary Leukocytes.

ABSTRACT: 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 G?i-mediated inhibition of cAMP synthesis. Application of G protein inhibitors revealed that this apparent lag was a result of counteraction of G?i effects by concurrent G?s activation. Monitoring downstream signaling events showed that activation of p38 was mediated by G?i, whereas ERK1/2 and Akt phosphorylation were mediated by G?i-coupled ??. Activation of CREB integrated multiple components; G?s and ?? mediated ?85% of the response, while ?15% was attributed to G?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-1?, and TNF-? 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.

SUBMITTER: Saroz Y 

PROVIDER: S-EPMC7088898 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature