Effects of Cannabidiol on the In Vitro Lymphocyte Pro-Inflammatory Cytokine Production of Senior Horses.

Cannabis sativa L. contains cannabidiol (CBD), a compound that has many anti-inflammatory properties. In this study, 99.9% CBD powder was used to determine its in vitro efficacy as an anti-inflammatory agent. Heparinized blood was collected via jugular venipuncture from senior horses. PBMCs were isolated then incubated for 24 hours with increasing dilutions of CBD dissolved in DMSO. PBMCs were stimulated the last 4 hours of incubation with PMA/IO and Brefeldin A. A Vicell counter was used to evaluate viability after incubation. PBMCs were stained intracellularly for IFNγ and TNFα then analyzed via flow cytometry. RT-PCR was used to analyze samples for gene expression. Five equine-specific intron-spanning primers/probes used are: CB1, CB2, TNFα, IFNγ, IL-10, and Beta-glucuronidase. Data was analyzed using RM One-way ANOVA (significance P < .05). Viability of PBMCs with CBD was completed to determine cytotoxicity. The dilution of CBD that did not affect cell viability was 4 µg/mL (P<0.05). CBD at 4 µg/mL significantly reduced production of IFN-γ and TNF-α (P < .05). RT-PCR results for TNFα and IFNγ at 4 µg/mL showed a reduction compared with the positive control and IL-10 showed a similar reduction at 2 µg/mL and 4 µg/mL. RT-PCR gene expression results showed significance for 10 μg/mL CBD in CB1 and CB2. CBD at 4 µg/mL reduced in vitro production of inflammatory cytokines from senior horses. This in vitro study supports further investigation of CBD to determine if it may be effective as an anti-inflammatory treatment for chronic inflammation in the horse.