TT-223

Osteoarthritis (OA) is the most common joint disease worldwide, but its cause remains unclear. Oestrogen protects against OA, but its clinical use is limited. G protein-coupled receptor 30 (GPR30) is a receptor that binds oestrogen, and GPR30 treatment has benefitted patients with some degenerative diseases. However, its effects on OA prevention and treatment remain unclear. Moreover, several studies have found that activation of estrogen receptors exerting anti-ferroptosis effects, which plays an important role in chondrocyte survival. Therefore, this study explored the general and ferroptosis-related effects and mechanisms of GPR30 in OA.

Genome-wide RNA sequencing, western blotting, and immunohistochemistry were used to evaluate GPR30 expression and ferroptosis-related indicators in cartilage tissues from clinical patients. Next, we investigated the effects of G1 (a GPR30 receptor agonist) on the function and pathology of OA in an animal model. We also treated chondrocytes with erastin (ferroptosis agonist) plus G1, G15 (GPR30 receptor antagonist), GPR30 short hairpin RNA, or ferrostatin-1 (ferroptosis inhibitor), then measured cell viability and ferroptosis-related indices and performed proteomics analyses. Finally, western blotting and reverse transcription-polymerase chain reaction were used to assess the effects of G1 on yes-associated protein 1 (YAP1) and ferritin heavy chain 1 (FTH1) expression.

GPR30 expression was lower in the OA cartilage tissues than in the normal tissues, and G1 treatment significantly improved the locomotor ability of mice. Moreover, chondrocyte cell viability significantly decreased after erastin treatment, but G1 treatment concentration-dependently mitigated this effect. Furthermore, G1 treatment decreased phosphorylated YAP1 expression, increased activated YAP1 expression, and increased FTH1 transcription and protein expression, protecting against ferroptosis.

GPR30 activation inhibited ferroptosis in chondrocytes by suppressing YAP1 phosphorylation, which regulates FTH1 expression.The Translational Potential of this Article: These results provide a novel potential target for therapeutic OA interventions.

Objectives:The aim of this work was to elucidate the role of GalR2 receptor activation in protecting the rat heart in vivo from ischemia/reperfusion (I/R) damage by a pharmacological peptide agonist WTLNSAGYLLGPβAH‐OH (G1) and full‐length rat galanin GWTLNSAGYLLGPHAIDNHRSFSDKHGLT‐NH2 (G2) using M871, a selective inhibitor of GalR2.Methods:The peptides were prepared by the automatic solid‐phase synthesis using the Fmoc‐strategy and purified by high‐performance liquid chromatography (HPLC). A 40‐min left anterior descending (LAD) coronary artery occlusion followed by a 60‐min reperfusion was performed. The criteria for damage/protection of the heart were the infarct size (IS) and plasma activity of creatine kinase‐MB (CK‐MB) at the end of reperfusion.Results:Intravenous injection of G1 or G2 at an optimal dose of 1 mg/kg at the fifth minute of reperfusion significantly reduced the IS (by 35% and 32%, respectively) and activity of CK‐MB at the end of reperfusion (by 43% and 38%, respectively) compared with the control. Administration of M871 (8 mg/kg) 5 min before the onset of reperfusion abolished the effects of G1 on IS and CK‐MB activity, returning them to control values. Co‐administration of M871 (8 mg/kg) with G2 attenuated protective effect of G2 on both IS and plasma СK‐MB activity. However, differences in these parameters between the M871+G2 and G2 groups did not reach statistical significance (P = 0.139 andP = 0.121, respectively).Conclusion:Thus, GalR2 is the principal receptor subtype that transduces the protective effects of galanin and ligand G1 in myocardial I/R injury. This suggests that GalR2‐specific peptide agonists could be used as drug candidates for treating ischemic heart disease.