Clinically relevant intra-articular corticosteroid doses impair equine osteoclast function in vitro.

OBJECTIVE

To assess the effects of clinically relevant doses of commonly employed intra-articular corticosteroids-specifically, triamcinolone acetonide (TCA), methylprednisolone acetate (MPA), and combination of betamethasone acetate and betamethasone sodium phosphate (BM)-on equine osteoclasts.

STUDY

DESIGN

In vitro controlled laboratory study.

SAMPLE POPULATION: Three donor mares (13-19 years).

METHODS

Following differentiation from bone marrow aspirates, osteoclasts were cultured alone (pure osteoclast cultures; n = 18 wells per group) or on equine bone slices (osteoclast-bone cultures; n = 6 wells per group) and treated with TCA (36 μg/mL), MPA (48 μg/mL), or BM (4 μg/mL). Untreated wells were controls. Outcome parameters included number of osteoclasts, bone resorption area and media biomarker concentrations, specifically tartrate-resistant acid phosphatase isoform-5b (TRACP-5b) and C-terminal telopeptide of type I collagen (CTX-I), measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

In pure osteoclast cultures (n = 16 wells in control and BM groups; n = 17 wells in TCA and MPA groups), mature osteoclast numbers were lower following corticosteroid addition compared with controls (MPA, p < .001; TCA, p = .009; BM, p = .002), and lower in the MPA group than the TCA group (p = .015). There was no difference in TRACP-5b between groups. In osteoclast-bone cultures (n = 5 in control group; n = 6 wells in TCA, MPA and BM groups), CTX-I decreased with MPA treatment compared with controls (p = .001), TCA (p = .006), and BM (p = .007) groups. TRACP-5b decreased with TCA compared with controls (p = .001). No differences in bone resorption area were measured.

CONCLUSION

Clinically relevant doses of commonly employed intra-articular corticosteroids-TCA, MPA, and BM-impacted equine osteoclast activity in vitro.

CLINICAL SIGNIFICANCE: Understanding that intra-articular corticosteroids may influence osteoclast activity, potentially affecting subchondral bone remodeling and repair, is important for guiding judicious use in equine joint management.