Non-psychoactive cannabidiol (CBD), one of the active compounds in medical cannabis, significantly reduced the clinical signs of a multiple sclerosis (MS)-like disease in an experimental mouse model of autoimmune encephalomyelitis. Researchers have found that CBD promotes an increase in suppressor cells called myeloid suppressor cells.
The results were presented in the study “https://www.frontiersin.org/articles/10.3389/fimmu.2018.01782/full” published in Frontiers in Immunology.
Medical cannabis contains over 100 pharmacologically active compounds (so-called cannabinoids) that have been shown to have strong anti-inflammatory effects and are potential treatments for a number of autoimmune diseases, including MS.
In MS, the potential of CBD, one of the most studied cannabinoids, along with tetrahydrocannabinol (THC), to modulate spasticity, as well as seizures, inflammation, pain, anxiety, and other conditions. The fact that CBD does not have the psychoactive (so-called “narcotic”) properties that accompany THC makes it a more attractive therapeutic agent.
In addition, CBD is reported to be neuroprotective by stopping inflammation in the brain. However, the mechanisms by which CBD suppresses neuroinflammation in MS remain unknown.
Now, researchers https://sc.edu/study/colleges_schools/medicine/index.php at the University of South Carolina School of Medicine used an MS mouse model called the Autoimmune Encephalomyelitis (EAE) Experimental Model to evaluate the effect of CBD treatment on neuroinflammation.
In addition, CBD reduced the production of pro-inflammatory cytokines (signaling molecules) such as interleukin (IL)-17 and interferon (IFN)-gamma, while promoting the production of drugs with anti-inflammatory properties, namely IL-10.
The researchers went on to investigate whether the effect of CBD on EAE was also associated with increased production of myeloid-derived cells.
They analyzed the abdominal region of mice (site of CBD injection) and observed a massive influx of myeloid-derived target cells on days 10 and 12 compared to control animals. Over time, the number of cells decreased by day 16.
However, in the spinal cord and brain of mice treated with CBD, the number of target cells derived from myeloid was lower than in control animals.
In vitro experiments have shown that myeloid-derived suppressor cells inhibit the proliferation of T cells, the immune cells that carry the attack against myelin in MS.
In the latest experiment, the researchers showed that injecting purified CBD-induced myeloid suppressor cells into EAE mice slowed the progression of the disease, as evidenced by a significant reduction in clinical scores and T-cell infiltrates in the central nervous system.
Overall, the results suggest that myeloid suppressor cells play a “critical role in attenuating CBD-mediated EAE,” the researchers write, and that “CBD may be an excellent candidate for the treatment of MS and other autoimmune diseases,” they concluded.
