Eicosapentaenoic acid restores inflammation-induced changes in chondrocyte mechanics by suppressing the NF-κB p65/CD44 signaling pathway and attenuates osteoarthritis

Here we investigate the effects and mechanisms of eicosapentaenoic acid (EPA) in regulating chondrocyte mechanics during inflammation in the progression of osteoarthritis (OA). Primary porcine chondrocytes and human OA chondrocytes were isolated and cultured. Cell mechanical properties were measured using atomic force microscopy. RNA sequencing, immunocytochemistry, quantitative PCR and western blotting were used to elucidate associated signaling mechanisms. Porcine cartilage and human OA cartilage explants were collected. Human articular cartilage samples were obtained from ten donors. Anterior cruciate ligament transection surgery was performed to induce OA in male C57BL/6J mice. The therapeutic effects of EPA and activation of associated signaling were evaluated using histology, immunohistochemistry and micro-computed tomography. EPA reduced F-actin intensity and Young's modulus in IL-1α-treated porcine chondrocytes and in human OA chondrocytes. Mechanistically, EPA inhibited IL-1α-induced increase in CD44 expression in porcine chondrocytes by suppressing phosphorylation of NF-κB subunits p65. In addition, EPA alleviated articular cartilage degeneration and decreased the expression of p-p65 and CD44 in IL-1α-treated porcine and human OA cartilage explants. Moreover, EPA suppressed the increase in Young's modulus induced by CD44 ligands (A6 peptide and low-molecular-weight hyaluronic acid) in porcine chondrocytes. Finally, intraarticular injection of EPA emulsion-integrated hyaluronic acid injection attenuated OA-associated alterations in articular cartilage and subchondral bone and decreased CD44 expression in mice. Our data not only provide new insights into EPA's chondroprotective actions and underlying mechanisms but also offer new evidence supporting the therapeutic efficacy of a novel EPA emulsion-integrated hyaluronic acid injection for OA treatment.