CBD Reduced MS-Like Inflammation in Mice by Activating Immune-Suppressing Cells
Multiple sclerosis (MS) is an autoimmune disease in which the immune system attacks myelin, the protective coating around nerve fibers in the brain and spinal cord. The resulting inflammation can contribute to symptoms such as weakness, impaired coordination, vision problems, pain, muscle spasms, fatigue and cognitive changes.
Cannabidiol (CBD), a non-intoxicating compound found in cannabis, has been studied for its potential anti-inflammatory effects. Cannabis-based medicines such as nabiximols, marketed as Sativex, contain both CBD and tetrahydrocannabinol (THC) and are used in some countries to help manage MS-related spasticity when other treatments have not provided sufficient relief. These products are intended to treat symptoms; they are not established cures for MS or replacements for disease-modifying therapies.
The biological mechanisms behind CBD’s possible effects on MS-related inflammation remain uncertain. In a 2018 study published in Frontiers in Immunology, researchers at the University of South Carolina School of Medicine examined the question using experimental autoimmune encephalomyelitis (EAE), a mouse model that reproduces some features of MS.
The researchers used female mice and induced EAE by immunizing them with a myelin-related peptide. Once treatment began, the animals received CBD or a vehicle control by intraperitoneal injection. CBD was administered at 20 milligrams per kilogram daily from day 9 through day 25, and the researchers monitored neurological symptoms using a standardized clinical scoring system.
Compared with control animals, the CBD-treated mice developed less severe paralysis and had fewer inflammatory T cells infiltrating the central nervous system. Their blood also contained lower levels of the pro-inflammatory signaling molecules interleukin-17 (IL-17) and interferon-gamma (IFN-γ).
Additional experiments showed that CBD altered immune activity outside the brain and spinal cord. In treated mice, levels of the transcription factors T-bet and RORγT—associated with inflammatory T-cell responses—fell, while production of the anti-inflammatory cytokine interleukin-10 (IL-10) increased.
The study focused particularly on myeloid-derived suppressor cells, or MDSCs. These immune cells can restrain T-cell activity during inflammation. CBD increased the number of MDSCs in peripheral tissues, including the peritoneal cavity and spleen, but not in the central nervous system. In laboratory experiments, the CBD-induced MDSCs suppressed the proliferation of T cells stimulated by the myelin-related peptide and reduced their production of IL-17 and IFN-γ while increasing IL-10.
Two further tests supported a role for MDSCs. Transferring CBD-induced MDSCs into mice reduced the severity of EAE, while depleting MDSCs partly reversed CBD’s protective effect. The findings suggest that CBD may limit disease in this model by dampening the activation of myelin-reactive T cells in peripheral immune organs before those cells migrate into the central nervous system.
However, the research was conducted in mice, not people with MS. EAE captures some aspects of autoimmune neuroinflammation but does not reproduce the full biology or long-term course of human MS. The study also tested purified CBD under a specific laboratory dosing regimen—not over-the-counter CBD oils or Sativex in human patients.
For people with MS, evidence for cannabis-based medicines is strongest for certain symptoms, particularly spasticity, and results vary by product and patient. The MS Trust’s information on Sativex describes its restricted use for moderate to severe MS-related spasticity in the United Kingdom. In the United States, the Food and Drug Administration warns that unapproved CBD products have not been evaluated for effectiveness, dosage, drug interactions or safety.
The South Carolina study therefore provides a potential explanation for how CBD can reduce inflammation in an animal model, particularly through the expansion of immunosuppressive MDSCs. It does not yet establish that CBD can slow, prevent or treat MS in humans. Clinical studies will be needed to determine whether this immune pathway can be translated into a safe and effective therapy.
