CB2 Receptors in Skin Cells Suppressed Chemo-Induced Nerve Pain in Mice | Research

The takeaway

CB2 cannabinoid receptors expressed in previously unrecognized skin cell populations suppressed chemotherapy-induced nerve pain in mice, pointing to a peripheral mechanism that avoids brain-related side effects.

Cancer patients experiencing neuropathy, pain researchers, cannabinoid pharmacology researchers

CB2 found in 4 previously unrecognized skin cell types

What the researchers found

CB2 agonists (AM1710 and LY2828360) suppressed paclitaxel-induced mechanical and cold allodynia in mice. The antiallodynic effect was blocked by a peripherally restricted CB2 antagonist, and local injection into the paw was effective, indicating a peripheral mechanism. CB2 was found in skin keratinocytes, Langerhans cells, dendritic cells, and Merkel cells.

Why it matters

Chemotherapy-induced peripheral neuropathy affects many cancer patients and has few effective treatments. A peripheral CB2 mechanism that avoids the psychoactive effects of CB1 activation could lead to targeted pain therapies.

The numbers in context

CB2 found in keratinocytes, Langerhans cells, dendritic cells, and Merkel cells; paclitaxel treatment dynamically increased Langerhans cells in the epidermis; local paw injection was effective

How the study worked

Used transgenic CB2-EGFP reporter mice to visualize CB2-expressing cell types. Tested structurally distinct CB2 agonists in a paclitaxel-induced neuropathy model. Combined behavioral testing with immunohistochemistry and mass cytometry.

What this study cannot tell us

Animal study in transgenic mice. CB2 expression patterns may differ in humans. The reporter gene approach may not capture all CB2-expressing cell types.

How to read the evidence

Well-designed animal study with transgenic reporter mice and multiple verification methods, but human translation is unconfirmed.

When this study was published

Published in 2022

The bigger picture

CB2 receptors have been a "holy grail" target for pain relief without intoxication. This study identifies specific skin cells as the site of action, potentially simplifying drug development toward topical or locally acting treatments.

Questions still open

Would topical CB2 agonists be effective for chemotherapy neuropathy in humans? Do the Langerhans cell changes represent a therapeutic target or a side effect of treatment?

Common questions

Could this lead to a pain cream for chemo patients?

The study showed that activating CB2 receptors locally in the paw suppressed nerve pain in mice, and these receptors are expressed in skin cells. This supports the concept of topical CB2-targeted treatments, though human trials are needed.

What is the advantage of targeting CB2 instead of CB1?

CB1 receptors are concentrated in the brain and cause the "high" from cannabis. CB2 receptors are found peripherally (including in skin cells) and can reduce pain without psychoactive effects.

Read the original research

A peripheral CB2 cannabinoid receptor mechanism suppresses chemotherapy-induced peripheral neuropathy: evidence from a CB2 reporter mouse.

Pain, 163(5), 834-851

View on PubMed ↗Publisher’s paper ↗

Citation

Lin, Xiaoyan; Xu, Zhili; Carey, Lawrence; Romero, Julian; Makriyannis, Alexandros; Hillard, Cecilia J; Ruggiero, Elizabeth; Dockum, Marilyn; Houk, George; Mackie, Ken; Albrecht, Phillip J; Rice, Frank L; Hohmann, Andrea G. (2022). A peripheral CB2 cannabinoid receptor mechanism suppresses chemotherapy-induced peripheral neuropathy: evidence from a CB2 reporter mouse.. Pain, 163(5), 834-851. https://doi.org/10.1097/j.pain.0000000000002502