Potential effect of Enterolactone and Raloxifene in reversing osteoarthritis markers in cultured human articular chondrocytes

Abstract Background: Osteoarthritis (OA) is associated with cartilage destruction. Maintenance of differentiated chondrocyte biomarkers is important in prevention of degeneration. Selective estrogen receptor modulators (SERMs) such as raloxifene (Ral) and phytoestrogens like enterolactone (Ent) which have structural and functional homologies with estrogen can mime their action. This study was undertaken to evaluate in vitro the possible effects of Ral and Ent on the expression of differentiated, dedifferentiated and hypertrophic biomarkers in human articular chondrocytes (HAC). Methods: Chondrocytes of osteoarthritic patients, harvested from one passage cell culture, were treated with Ral (0.1 and 1 µM) and Ent (1 and 5 µM) for 10 and 12 days in two- (2D) and three-dimensional (3D) models. Genes expression of type I collagen (COL1A1), type II collagen (COL2A1), type X collagen (COL10A1), aggrecan (ACAN) and small novel rich in cartilage (SNORC), were detected by real-time PCR and by Western-Blotting. Results: Our study revealed that Ral increased COL2A1, ACAN and SNORC and decreased concomitantly COL1A1 and COL10A1 genes expression when compared to untreated OA chondrocytes. Ent increased COL2A1 and decreased genes expression of the other biomarkers cited above like COL1A1. Our results demonstrated that low doses of 17β-oestradiol (E2), Ral and Ent had positive effects on the expression of differentiated chondrocyte markers such as COL2A1, ACAN and SNORC whereas high dose of these compounds inhibited their effects. Our results showed that 1µM of Ral induced an up-regulation of COL2A1, ACAN and SNORC expression and a down-regulation of COL1A1 and COL10A1 expression in HAC incubated in 3D for 12 days. Conclusions: This study showed that SERMs like Ral and a phyto-estrogen like Ent induced the expression of differentiated chondrocyte markers of hyaline cartilage: COL2A1, ACAN and SNORC and decreased COL1A1 and COL10A1 genes expression on HAC of osteoarthritis patients.