How cannabinoids regulate immune function in the brain and could treat neuroinflammatory diseases | Research

The takeaway

Both plant-derived and synthetic cannabinoids show anti-inflammatory and immune-modulating properties in the brain, with potential applications for MS, Alzheimer's, and ALS.

Read this if you're interested in how cannabis-related compounds might help with brain inflammation.

CB2 receptors: anti-inflammatory without psychoactive effects

What the researchers found

This review examined how cannabinoid signaling interacts with the brain's immune system. The traditional view of the brain as immune-privileged was described as oversimplified. Resident immune cells and cross-talk with peripheral immune cells are essential for normal brain function, but prolonged neuroinflammation characterizes diseases like multiple sclerosis, Alzheimer's, and ALS.

Phytocannabinoids (from cannabis), synthetic cannabinoids, and endocannabinoids all demonstrated immunoregulatory and anti-inflammatory properties in brain tissue through cannabinoid receptor activation. These effects were seen in microglia (the brain's primary immune cells), astrocytes, and other brain immune-related cells.

The review highlighted both CB1 and CB2 receptor-mediated pathways as potential therapeutic targets, with CB2 receptors being particularly relevant because they are upregulated during neuroinflammation without producing the psychoactive effects associated with CB1 activation.

Why it matters

Neuroinflammation is a shared feature of many devastating brain diseases. If cannabinoid-based approaches can modulate brain immune responses without causing psychoactive effects (via CB2 targeting), they could complement existing treatments for conditions with limited therapeutic options.

The numbers in context

Three neuroinflammatory diseases discussed: MS, Alzheimer's, ALS. Two cannabinoid receptors analyzed: CB1 and CB2. Multiple immune cell types covered: microglia, astrocytes, dendritic cells.

How the study worked

Narrative review of literature on cannabinoid modulation of brain immune responses, covering phytocannabinoids, synthetic cannabinoids, and endocannabinoids across multiple neuroinflammatory disease models.

What this study cannot tell us

Narrative review with mostly preclinical evidence. Clinical data on cannabinoid immunotherapy for neurological diseases was limited. The complexity of brain immune responses means in vitro findings may not translate to clinical settings.

How to read the evidence

Narrative review of predominantly preclinical research on cannabinoid immunomodulation in the brain.

When this study was published

Published in 2015. Cannabinoid immunology research has progressed significantly since.

The bigger picture

The discovery that the brain has its own immune system that interacts with cannabinoid signaling has opened new therapeutic avenues. The challenge is harnessing anti-inflammatory benefits while avoiding the psychoactive effects that limit clinical use of many cannabinoid compounds.

Questions still open

Can CB2-selective compounds provide neuroprotection without psychoactive effects? How does chronic cannabis use alter the brain's immune regulation? Could cannabinoid-based immunotherapy complement existing disease-modifying treatments?

Common questions

Can cannabinoids reduce brain inflammation?

Preclinical evidence shows cannabinoids have anti-inflammatory effects in brain tissue through both CB1 and CB2 receptors. CB2 receptors are particularly interesting because they modulate immunity without psychoactive effects.

Could cannabis help with MS or Alzheimer's?

Preclinical studies show promise, and cannabinoid receptors are upregulated during neuroinflammation. However, clinical evidence for disease modification in humans was limited at the time of this 2015 review.

Read the original research

Turning Over a New Leaf: Cannabinoid and Endocannabinoid Modulation of Immune Function.

Journal of neuroimmune pharmacology : the official journal of the Society on NeuroImmune Pharmacology, 10(2), 193-203

View on PubMed ↗Publisher’s paper ↗

Citation

Cabral, Guy A; Rogers, Thomas J; Lichtman, Aron H. (2015). Turning Over a New Leaf: Cannabinoid and Endocannabinoid Modulation of Immune Function.. Journal of neuroimmune pharmacology : the official journal of the Society on NeuroImmune Pharmacology, 10(2), 193-203. https://doi.org/10.1007/s11481-015-9615-z