Eicosapentaenoic Acid suppresses the proliferation of synoviocytes from rheumatoid arthritis

Fatty Acids and Oxylipins in Osteoarthritis and Rheumatoid Arthritis-a Complex Field with Significant Potential for Future Treatments

Purpose of Review

Osteoarthritis (OA) and rheumatoid arthritis (RA) are characterized by abnormal lipid metabolism manifested as altered fatty acid (FA) profiles of synovial fluid and tissues and in the way dietary FA supplements can influence the symptoms of especially RA. In addition to classic eicosanoids, the potential roles of polyunsaturated FA (PUFA)-derived specialized pro-resolving lipid mediators (SPM) have become the focus of intensive research. Here, we summarize the current state of knowledge of the roles of FA and oxylipins in the degradation or protection of synovial joints.

Recent Findings

There exists discordance between the large body of literature from cell culture and animal experiments on the adverse and beneficial effects of individual FA and the lack of effective treatments for joint destruction in OA and RA patients. Saturated 16:0 and 18:0 induce mostly deleterious effects, while long-chain n-3 PUFA, especially 20:5n-3, have positive influence on joint health. The situation can be more complex for n-6 PUFA, such as 18:2n-6, 20:4n-6, and its derivative prostaglandin E₂, with a combination of potentially adverse and beneficial effects. SPM analogs have future potential as analgesics for arthritic pain.

Summary

Alterations in FA profiles and their potential implications in SPM production may affect joint lubrication, synovial inflammation, pannus formation, as well as cartilage and bone degradation and contribute to the pathogeneses of inflammatory joint diseases. Further research directions include high-quality randomized controlled trials on dietary FA supplements and investigations on the significance of lipid composition of microvesicle membrane and cargo in joint diseases.

Bufalin exerts inhibitory effects on IL-1β-mediated proliferation and induces apoptosis in human rheumatoid arthritis fibroblast-like synoviocytes

Rheumatoid arthritis fibroblast-like synoviocytes (RAFLSs) proliferate abnormally and resist apoptosis. Bufalin inhibits cell proliferation and induces apoptosis in human cancer cells. In this study, we explored the effects of bufalin on interleukin-1beta (IL-1β)-induced proliferation and apoptosis of RAFLSs. The cell proliferation and apoptosis were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide assay and annexin V/propidium iodide staining, respectively. Bufalin dose-dependently inhibited IL-1β-induced RAFLS proliferation. Mechanistically, bufalin decreased the activation of mitogen-activated protein kinases (MAPKs) and nuclear factor-kappa B (NF-κB), both of which are involved in IL-1β-mediated RAFLS proliferation. Moreover, bufalin induced apoptosis and mitochondrial damage of RAFLSs, which was associated with Bcl-2 downregulation, Bax upregulation, mitochondrial cytochrome c release, and enhanced cleavages of caspase-3 and poly-(ADP-ribose) polymerase. Collectively, our results reveal that bufalin suppresses IL-1β-induced proliferation of RAFLSs through MAPK and NF-κB signaling pathways and induces RAFLS apoptosis via the mitochondria-dependent pathway.

Hempseed oil induces reactive oxygen species- and C/EBP homologous protein-mediated apoptosis in MH7A human rheumatoid arthritis fibroblast-like synovial cells

ETHNOPHARMACOLOGICAL RELEVANCE

The medicinal efficacy of hempseed (Cannabis sativa L.), which is rich in polyunsaturated fatty acids, in atopic dermatitis, inflammation, and rheumatoid arthritis (RA) has been suggested for centuries. Hempseed has been used as a treatment for these diseases in Korean and Chinese folk medicine. The aim of the study is to investigate the effects of hempseed oil (HO) on MH7A human RA fibroblast-like synovial cells.

MATERIALS AND METHODS

MH7A cells were used to study the anti-rheumatoid effects of hempseed (Cannabis sativa L., cv. Cheungsam/Cannabaceae) oil by investigating cell viability, apoptosis, lipid accumulation, oxidative stress, and endoplasmic reticulum (ER) stress-induced apoptosis.

RESULTS

HO treatment reduced the survival rate of MH7A cells and promoted apoptotic cell death in a time- and dose-dependent manner. Both lipid accumulation and the level of intracellular reactive oxygen species (ROS) increased in HO-treated MH7A cells. Co-treatment with the antioxidant Tiron effectively abrogated the cytotoxic effects of HO; the ROS level was reduced, cell viability was recovered, and apoptotic cell death was significantly diminished. Moreover, HO-treated cells exhibited increased expression of the major ER stress markers, glucose-regulated protein 78 and C/EBP homologous protein (CHOP). The siRNA-mediated knockdown of CHOP prevented HO-induced apoptosis.

CONCLUSIONS

Our results suggest that HO treatment induced lipid accumulation, ROS production, CHOP expression, and apoptosis in MH7A cells, and that CHOP functions as an anti-rheumatoid factor downstream of HO in MH7A cells.

Eicosapentaenoic acid attenuates arthritis-induced muscle wasting acting on atrogin-1 and on myogenic regulatory factors

Eicosapentaenoic acid (EPA) is an omega-3 polyunsaturated fatty acid that has anti-inflammatory and anticachectic actions. The aim of this work was to elucidate whether EPA administration is able to prevent an arthritis-induced decrease in body weight and muscle wasting in rats. Arthritis was induced by intradermal injection of Freund's adjuvant; 3 days later, nine rats received 1 g/kg EPA or coconut oil daily. All rats were killed 15 days after adjuvant injection. EPA administration decreased the external signs of arthritis and paw volume as well as liver TNF-alpha mRNA. EPA did not modify arthritis-induced decrease in food intake or body weight gain. However, EPA treatment prevented arthritis-induced increase in muscle TNF-alpha and atrogin-1, whereas it attenuated the decrease in gastrocnemius weight and the increase in MuRF1 mRNA. Arthritis not only decreased myogenic regulatory factors but also increased PCNA, MyoD, and myogenin mRNA in the gastrocnemius. Western blot analysis showed that changes in protein content followed the pattern seen with mRNA. In the control rats, EPA administration increased PCNA and MyoD mRNA and protein. In arthritic rats, EPA did not modify the stimulatory effect of arthritis on these myogenic regulatory factors. The results suggest that in experimental arthritis, in addition to its anti-inflammatory effect, EPA treatment attenuates muscle wasting by decreasing atrogin-1 and MuRF1 gene expression and increasing the transcription factors that regulate myogenesis.