Anti-inflammatory and chondroprotective role of tart cherry polyphenols in SW1353 human chondrocytes

The aim of this study was to investigate the chondroprotective effect of tart cherry polyphenols (TCP) using human chondrocytes. Chondrocytes (SW 1353) were pre-treated with TCP at concentrations of 1.25, 2.5, 5, and 10 µg/mL for 24 h then stimulated with the recombinant interleukin-1β (20 ng/mL) for 24 hours. After an initial increase (p<0.05) in cell proliferation at 1.25 µg/mL TCP, a dose-dependent decrease in cell proliferation was observed with higher doses of TCP. Following a significant decrease in nitrate levels at the 1.25 µg/mL TCP dose, there was a dose-dependent increase in nitrate concentration. The dose-dependent increase in nitrate levels occurred with concomitant decreases in inducible nitric oxide synthase (iNOS) intracellular protein expression at the two highest TCP doses. Reductions in cartilage degradation were observed in the 2.5, 5, and 10 µg/mL TCP doses, as indicated by decreases in glycoprotein-39 (YKL-40) levels. TCP appeared to have no significant effect on total protein expression of the pro-inflammatory transcription factor, necrosis factor kappa B (NF-κB), or the matrix degrading enzyme, matrix metalloproteinase-3 (MMP-3). In conclusion, these findings suggest that TCP promote cartilage health by modulating pro-inflammatory pathways implicated in extracellular matrix destruction, as indicated by the effect of TCP doses on nitrite, iNOS, and YKL-40 levels. However, further research is need to elucidate the mechanism by which tart cherry polyphenols elicit these positive effects on cartilage health.