Background:Osteoarthritis (OA) is a chronic joint disease characterized by
the degradation of articular cartilage. Polyphyllin I (PPI) has anti-inflammatory effects
in many diseases. However, the mechanism of PPI in OA remains unclear.Methods:HC-a cells treated with IL-1β were identified by immunofluorescence
staining and microscopic observation. The expression of collagen II and DAPI in HC-a
cells was detected by immunofluorescence. The effects of gradient concentration of
PPI on IL-1β-induced cell viability, apoptosis, senescence, and inflammatory factor
release were detected by MTT, flow cytometry, SA-β-Gal assay and ELISA,
respectively. Expressions of apoptosis-related genes, extracellular matrix (ECM)-
related genes, and TWIST1 were determined by qRT-PCR and western blot as
needed. The above-mentioned experiments were conducted again after TWIST1
overexpression in IL-1β-induced chondrocytes.Results:IL-1β reduced the number of chondrocytes and the density of collagen II. PPI
(0.25, 0.5, 1 μmol/L) had no effect on cell viability, but it dose-dependently elevated the
inhibition of cell viability regulated by IL-1β. The elevation of cell apoptosis,
senescence and expression of IL-6 and TNF-α were suppressed by PPI in a dosedependent
manner. Additionally, PPI reduced the expression of cleaved caspase-3,
bax, MMP-3, and MMP-13 and promoted the expression of collagen II. TWIST1
expression was diminished by PPI. TWIST1 overexpression reversed the abovementioned
effects of PPI on chondrocytes.Conclusion:PPI suppressed apoptosis, senescence, inflammation, and ECM
degradation of OA chondrocytes by downregulating the expression of TWIST1.