EZH2 inhibition reduces cartilage loss and functional impairment related to osteoarthritis

Abstract

Histone methyltransferase EZH2 is upregulated during osteoarthritis (OA), which is the most widespread rheumatic disease worldwide, and a leading cause of disability. This study aimed to assess the impact of EZH2 inhibition on cartilage degradation, inflammation and functional disability. In vitro, gain and loss of EZH2 function were performed in human articular OA chondrocytes stimulated with IL-1β. In vivo, the effects of EZH2 inhibition were investigated on medial meniscectomy (MMX) OA mouse model. The tissue alterations were assayed by histology and the functional disabilities of the mice by actimetry and running wheel. In vitro, EZH2 overexpression exacerbated the action of IL-1β in chondrocytes increasing the expression of genes involved in inflammation, pain (NO, PGE2, IL6, NGF) and catabolism (MMPs), whereas EZH2 inhibition by a pharmacological inhibitor, EPZ-6438, reduced IL-1β effects. Ex vivo, EZH2 inhibition decreased IL-1β-induced degradation of cartilage. In vivo, intra-articular injections of the EZH2 inhibitor reduced cartilage degradation and improved motor functions of OA mice. This study demonstrates that the pharmacological inhibition of the histone methyl-transferase EZH2 slows the progression of osteoarthritis and improves motor functions in an experimental OA model, suggesting that EZH2 could be an effective target for the treatment of OA by reducing catabolism, inflammation and pain.

Histone Modifications and Chondrocyte Fate: Regulation and Therapeutic Implications

“…In addition to its role in endochondral bone growth, EZH2 is shown to play important roles in the pathogenesis of OA. EZH2 is significantly upregulated in articular chondrocytes of OA patients and OA mouse model when compared with that of the normal controls Allas et al, 2020). Overexpression of EZH2 increases Ihh, Mmp13, Adamts-5, and Col10A1 expression, while inhibition of EZH2 suppresses these genes expression in chondrocytes.…”

“…Another EZH2 inhibitor EPZ-6438 is found to reduce IL-1β-induced expression of genes associated with inflammation and pain (e.g., NO, PGE2, IL-6, and NGF) and catabolism (e.g., MMPs) in chondrocytes. Intra-articular injection of EPZ-6438 reduces cartilage degradation and improves joint motor functions in the mouse OA model (Allas et al, 2020). In addition, EPZ-6438 rescues chondrogenic differentiation potential of periodontal ligament stem cells (PDLSCs) after knockdown of KDM6A by regulating H3K27me3 (Wang et al, 2018a (Ukita et al, 2020).…”

The benefit of combining curcumin, bromelain and harpagophytum to reduce inflammation in osteoarthritic synovial cells

“…Cells were lysed and protein extracted using Radio Immuno Precipitation Assay (RIPA) Buffer (50 mM Tris-HCl pH 7.5; 1% Igepal CA-630; 150 mM NaCl; 1 mM EGTA; 1 mM NaF; 0.25% Na-deoxycholate; Distilled water), and supplemented with a protease inhibitor (Leupeptin 1 mg/m; Phenyl methyl sulfonyl fluoride 200 m; pepstatin A 1 mg/ml) and a phosphatase inhibitor (sodium orthovanadate 200 mM) as previously described [ 29 ].…”

“…RPL13a was used as the invariant housekeeping gene. The decision to opt for this gene was based on our previous experience in the field [ 29 , 35 , 36 ].…”

“…PGE2 and MMP released into conditioned media were quantified using a commercially available enzyme immunoassay kit (R&D Biosystem) as previously described [ 29 ]. For IL-6, we proceeded in the same way but using the Human beta-NGF ELISA Kit and the Human IL-6 ELISA kit (Sigma Aldrich).…”