Cartilage metabolism
Four studies investigated changes in PG synthesis after the application of corticosteroids. MPA decreased PG synthesis in a dose-dependent way (Murphy et al., 2000; Doyle et al., 2005; Byron et al., 2008); however, one group reported that it did not cause significant decreases in synthesis at 0.1 mg/mL in the first days after exposure, followed by an increase in synthesis only between days 4 and 7 (Murphy et al., 2000). BTM was also investigated regarding its effects on PG synthesis in one study (Frean, Cambridge & Lees, 2002), where suppression was caused by higher concentrations (0.1–100 𝜇g/mL) with no significant changes at lower doses (0.001–0.05 𝜇g/mL) (Frean, Cambridge & Lees, 2002). Collagen synthesis was also evaluated for MPA, which significantly decreased at higher doses (Fubini et al., 2001).
PG degradation (i.e., PG released into the medium) was evaluated in four studies. Three evaluated the effect of MPA/MPS and found conflicting results. While no significant changes were found by Byron et al. (2008), increases in PG degradation were found by Murphy et al. (2000). Doyle et al. (2005) found that MPA had a positive effect by significantly decreasing the release of newly synthesized PG at one tested dose (5 mg/mL). BTM was evaluated in one study, which found significant increases in PG released into media at higher doses (Frean, Cambridge & Lees, 2002).
Total GAG content showed significant increases to no changes when MPA was applied (Doyle et al., 2005; Byron et al., 2008), and total cartilage DNA content showed no significant changes in response to MPA (Doyle et al., 2005; Byron et al., 2008), DEX, or TA (Busschers, Holt & Richardson, 2010).
Oxidative profile was evaluated in one study only, which investigated the TA treatment in normal cartilage explants. There were no differences in lipid peroxidation, activity of catalase, or glutathione peroxidase compared to controls (Palma et al., 2019a).