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Protection from osteoarthritis may lie in our own joints, study suggests

2014-05-18

May 18, 2014, Prague, Czech Republic. Press Dispensary. A recent study conducted by researchers at the University of Edinburgh is suggesting a strong link between osteoarthritis, which causes pain and stiffness in the joints and is the most common form of arthritis, and the endocannabioid system, which is found in the synovial tissue and fluid that surround joints. The endocannabinoid system is composed of cannabinoid receptors (which are more popularly known for managing the body's response to the psychoactive effects of cannabis) and endocannabinoid ligands*. The type 2 cannabinoid receptor (CB2), is proving to be a significant source of defence against this potentially debilitating disease, which can affect all ages and is particularly common among the elderly.

The findings, which offer the eventual promise of new forms of protection, were presented today at the 41st European Calcified Tissue Society Congress, held in Prague on May 17 - 20, 2014, by Professor Stuart Ralston, Arthritis Research UK Professor of Rheumatology at the University of Edinburgh. Prof Ralston described how a study of mice with destabilised knee joints showed that cartilage degeneration, which lies at the heart of osteoarthritis, was up to 40% more severe in mice who were deficient in CB2 receptors, when compared to 'normal' mice, with the figure reaching up to 60% more severe among aged mice that developed spontaneous osteoarthritis and were deficient in CB2 receptors, when compared to their aged 'normal' counterparts.

The study also showed that a synthesised cannabinoid ligand, HU308, significantly inhibited the progression of arthritis in younger mice with normal  levels of CB2 and had no effect on those with CB2 receptor deficiency.

Professor Ralston said: "Learning what provides natural protection against osteoarthritis can potentially give us a much greater insight into how we can develop treatments. We know from this study that, in mice, a CB2 receptor deficiency means a much higher likelihood of developing osteoarthritis and that the use of the synthesised cannabinoid, HU308, in normal mice offers additional protection against the disease.

"Our next step, we hope, is to investigate the role of the CB2 pathway in humans with osteoarthritis."

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Notes for editors

* About receptors and ligands

Receptors and ligands carry out a great deal of physiology on the subcellular level. Receptors are sites on the surface of cells that allow specific molecules to bind to them. Ligands are these specific molecules. An agonist is a ligand that binds to the active site of a receptor and initiates some change in body function. An antagonist is a ligand that does not bring about a functional change when it binds to receptors. (Campbell, 1996).

About The European Calcified Tissue Society

The European Calcified Tissue Society (ECTS) is the major organisation in Europe for researchers and clinicians working in the field of calcified tissues and related fields. ECTS acts as a forum for the dissemination of high quality research through its annual meeting, the European Symposium on Calcified Tissues, and through training courses and workshops.

Calcified tissues are central to a healthy skeleton and to bone disorders - such as osteoporosis, back pain and fractures - that make life a misery for countless people. Children can inherit some forms of bone diseases causing bone pain, shortness and deformed limbs.

The 41st European Calcified Tissue Society Congress is taking place in Prague, the Czech Republic, on May 17-20, 2014.

The ECTS Annual Congress gives delegates the opportunity to collaborate with leading international researchers and clinical colleagues. Main discussion points are the latest in high quality science and research to benefit clinical practice..

ECTS 2015 will be in Rotterdam, 25-18 April 2015.

About the study

The presence of Cannabinoid receptors in synovial joints is known but their role in joint disease is unknown. This study set out to correct that. It examined the role of CB2 (type 2 cannabinoid receptor) in the progress of osteoarthritis, both naturally age-related and surgically induced, by studying 'normal', wild-type mice and CB2-deficient mice, both young and aged.

The severity of arthritis was graded histologically according to standard techniques and differences between genotypes were compared by Student’s T-test and it was shown that cartilage degeneration was 34%* more severe at the medial compartment of operated joints of CB2-deficient mice compared with their 'normal' littermates and specifically 40%** more severe at the tibial plateau. There were no significant differences between the types of mice in the microarchitecture of subchondral bone.

Similar analyses of aged mice that developed spontaneous osteoarthritis revealed that arthritis in the medial compartment of CB2-deficient mice was 60% more severe than their 'normal' littermates. Furthermore, treatment with the CB2-selective agonist HU308 on young mice with surgically-induced osteoarthritis significantly inhibited progression of arthritis in the medial compartment of operated joints in 'normal' mice with 32% less damage at the tibial plateau and 18% less damage at the femoral condyle, compared with mice administered with vehicle. In contrast treatment with HU308 had no significant protective effect in CB2-deficient mice, indicating a CB2-mediated effect.

The study concluded that CB2 receptor deficiency predisposes mice to age-related and surgically-induced osteoarthritis and that CB2 agonists have protective effects. These findings suggest that further studies on the role of CB2 pathway in humans with osteoarthritis are warranted.

* (mean ± SEM) 34% ± 10
** 40% ± 13
*** 60% ± 14

For further information, please contact:
Roberta Mugnai, ECTS executive director
European Calcified Tissue Society (ECTS)
Tel: + 32 476 520 716
Email:
Site: www.ectsoc.org

Congress site: www.ectscongress.org/2014/
Twitter: @ECTS_soc
Hashtag: #ECTS14

Media contacts

Roberta Mugnai, ECTS executive director
Tel: + 32 476 520 716
Email:
Site: www.ectsoc.org

Congress site: www.ectscongress.org/2014/
Twitter: @ECTS_soc
Hashtag: #ECTS14

Keywords/tags
calcified tissue bone disorders osteoporosis back pain bone fractures hip fractures endocannabioid system cannabinoid receptor CB2 receptor deficiency CB2 pathway

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