Endogenous cannabinoid anandamide impairs cell growth and induces apoptosis in chondrocytes

Abstract

Endocannabinoids has been described to be involved in articular degenerative disease by modulating nociception and immune system. However, the role of the endocannabinoid anandamide on chondrocyte cell viability is still unclear. Therefore, we decided to study anandamide's effects on chondrocytes viability and to evaluate its interactions with the catabolic factor TNF (tumor necrosis factor). Chondrocyte vitality was evaluated by MTT assay. We investigated LDH release, chromatin condensation, cleavage of focal adhesion kinase (FAK), and caspases-3, 8, and 9 activation. c-MYC mRNA levels were determined by RT-PCR. We studied by Western blot the activation patterns of AKT, AMPK, ERK, p38, and JNK kinases. Finally, we evaluate the effect of anandamide in TNF-induced caspase-3 cleavage. Anandamide decreased chondrocyte vitality independently of its receptors. It induced AMPK activation without LDH release. Anandamide induced chromatin condensation, activation of caspase-3, 8, and 9, and FAK cleavage. Surprisingly, despite anandamide inhibited cell proliferation, it increased c-MYC expression. Moreover anandamide inhibited AKT activation, whilst it induced a sustained activation of ERK, JNK, and p38. Finally, anandamide synergized with TNF-a in the cleavage of caspase-3. In conclusion, our findings suggest that anandamide, alone or in combination with TNF-a, may be a potential destructive agent in cartilage. Keywords: cannabinoids; chondrocyte physiology; apoptosis; signal transduction; TNF The endocannabinoid system is constituted by the cannabinoid receptors (CB 1 and CB 2 ), by the endocannabinoids (including anandamide [AEA] and others) and the machinery for their biosynthesis and metabolism.

Berberine prevents nitric oxide-induced rat chondrocyte apoptosis and cartilage degeneration in a rat osteoarthritis model via AMPK and p38 MAPK signaling

“…Recent evidences suggested that activated AMPK was involved in the anti-apoptotic effect on potential chondroprotection [41,42], and chondrocyte apoptosis was accompanied by increased phosphorylation of p38 MAPK Fig. 8 a Immunohistochemical analyses of caspase-3, Bax, Bcl-2, and Col II expressions in each group (original magnification 9200 and zoom-in areas magnification 9400).…”

Joint problems arising from lack of repair mechanisms: can cannabinoids help?

“…AEA has been found to decrease chondrocyte vitality, although this effect was not CB receptor‐dependent. Nevertheless, it was also shown to work in synergy with TNFα to cleave caspase‐3 and induce apoptosis, thus facilitating cartilage degeneration (Gómez et al ., ). Therefore, it is important to further identify the role of these receptors within normal and OA cartilage to clarify their role in healthy tissue and their potential as possible targets in the treatment of OA (Dunn et al ., ).…”

Endocannabinoids and acute pain after total knee arthroplasty

“…To date a detailed analysis of endocannabinoid levels in OA patients and their influence upon OA-associated pain has not been reported despite the well-documented role of endocannabinoids in the modulation of pain and the recognized presence of cannabinoid receptors on chondrocytes [14]. A single clinical study has examined endocannabinoid levels in the synovial fluid of OA patients and found elevated AEA and 2-AG levels and reduced content of the anti-inflammatory PEA [45], possibly reflecting a pro-inflammatory and proalgesic environment.…”