Phytocannabinoids regulate inflammation in IL‐1β‐stimulated human gingival fibroblasts

Objectives Billions of individuals worldwide suffer from periodontal disease, an inflammatory disease that results in hard‐tissue and soft‐tissue destruction. A viable therapeutic option to treat periodontal disease may be via cannabinoids that exert immunomodulatory effects, and the endocannabinoid system (ECS) is readily present in periodontal tissues that exhibit cannabinoid type 1 and 2 receptors (CB1R and CB2R). Phytocannabinoids (pCBs), which are a part of a heterogeneous group of molecules acting on cannabinoid receptors (CBR) derived from the cannabis plants, have been attributed to a wide variety of effects including anti‐inflammatory activity and some pro‐inflammatory effects depending on the cell type. Thus, this study aims to examine the effects of pCBs on primary human gingival fibroblasts (HGFs) in IL‐1β stimulated (simulated periodontal disease) HGFs. Materials and Methods Human gingival fibroblasts (HGFs) obtained from ATCC were cultured per the manufacturer's recommendation. The functional activity of cannabinoid receptors was measured using ACTOne (cAMP)‐based CB1R and CB2R assay. The effects of three pCBs (0.1–10 μg/ml or 10–4.5–10−6.5 M) on cell viability were assessed using the CCK‐8 cellular dehydrogenase assay. IL‐1β (1 ng/ml) was added an hour before the treatment to stimulate inflammation in the HGFs before the addition of cannabinoid ligands. After 24‐h incubation, the production of INF‐γ, IL‐2, IL‐4, IL‐6, IL‐8, IL‐10, IL‐12p70, IL‐13, and TNF‐α was measured using Mesoscale Discovery (MSD) Human Pro‐Inflammatory kit. To measure prostaglandin E 2 levels (PGE2), Cisbio HTRF PGE2 assay kit was used per the manufacturer's recommendation to measure after 24‐h incubation. The data were analyzed using GraphPad Prism 6.0. The analytes for each group were compared using a one‐way ANOVA test with Bonferroni's correction. Results Cannabidivarin (CBVN or CBDV) (EC50 = 12 nM) and cannabigerol (CBG) (EC50 = 30 nM) exhibited agonist activity on CB2R with intermediate efficacy. Cannabidiol (CBD) did not exhibit activation of the CB2R, and the CB1R activation was not observed with any of the pCBs. Cytotoxicity results showed that concentrations of 2.50 μg/ml or greater for the pCBs were toxic except for CBVN. Lower concentrations of CBD and CBG (0.1–0.75 μg/ml), and CBVN at 2.50 μg/ml exhibited significant effects on HGF proliferation. In IL‐1β‐stimulated HGFs, prostaglandin E2 (PGE2) production was significantly suppressed only by CBG and CBVN.