Patients with rheumatoid arthritis and osteoarthritis had significantly lower blood levels of 2-AG, a key pain-regulating endocannabinoid, along with altered pro- and anti-inflammatory lipid profiles compared to healthy controls.
Rheumatologists, pain researchers, endocannabinoid system researchers, arthritis patients
2-AG significantly depleted in both RA and OA patients
What the researchers found
Among 80 participants (25 RA, 18 OA, 37 healthy), 2-arachidonoylglycerol (2-AG) levels were significantly lower in both RA and OA patients compared to controls. RA patients also had higher ethanolamide-type endocannabinoids (anandamide, DHA-EA, etc.) and lower levels of the pro-resolving lipid 9-oxoODE and omega-3 fatty acids EPA and DHA.
Why it matters
2-AG is a critical regulator of pain signaling and inflammation. Finding it depleted in arthritis suggests a specific endocannabinoid deficiency that could help explain residual pain and points toward targeted cannabinoid therapies.
The numbers in context
80 participants (25 RA, 18 OA, 37 controls); 16 endocannabinoids and 129 oxylipins quantified; 2-AG significantly lower in RA and OA; ethanolamides higher in RA; EPA and DHA lower in RA.
How the study worked
Clinical study of 80 participants comparing 16 endocannabinoids/congeners and 129 oxylipins in plasma using LC-MS/MS assays across RA patients, OA patients, and healthy controls.
What this study cannot tell us
Small sample sizes per group. Cross-sectional design cannot determine whether low 2-AG causes arthritis symptoms or results from them. Plasma levels may not reflect tissue-level endocannabinoid concentrations at joint sites.
How to read the evidence
Well-characterized clinical study with comprehensive biomarker profiling, limited by small group sizes and cross-sectional design.
When this study was published
2025 publication
The bigger picture
The endocannabinoid deficiency theory proposes that low endocannabinoid levels contribute to chronic pain conditions. This study provides direct evidence of 2-AG depletion in two major forms of arthritis, supporting this theory and suggesting why exogenous cannabinoids might help.
Questions still open
- Would restoring 2-AG levels (via MAGL inhibitors or exogenous cannabinoids) improve arthritis pain?
- Is the 2-AG deficiency a cause or consequence of chronic inflammation?
Common questions
Are endocannabinoid levels different in people with arthritis?
Could cannabinoids help with arthritis pain?
Read the original research
Endocannabinoid Tone and Oxylipins in Rheumatoid Arthritis and Osteoarthritis-A Novel Target for the Treatment of Pain and Inflammation?
International journal of molecular sciences, 26(12)
Citation
Klawitter, Jost; Clauw, Andrew D; Seifert, Jennifer A; Klawitter, Jelena; Tompson, Bridget; Sempio, Cristina; Ingram, Susan L; Christians, Uwe; Moreland, Larry W. (2025). Endocannabinoid Tone and Oxylipins in Rheumatoid Arthritis and Osteoarthritis-A Novel Target for the Treatment of Pain and Inflammation?. International journal of molecular sciences, 26(12). https://doi.org/10.3390/ijms26125707
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