Gentiopicroside ameliorates synovial inflammation and fibrosis in KOA rats by modulating the HMGB1-mediated PI3K/AKT signaling axis.

BACKGROUND

Knee osteoarthritis (KOA) is a degenerative joint disease characterized by synovial inflammation and fibrosis. Gentiopicroside (GPS), one of the main active ingredients of Gentiana macrophylla, is widely used in anti-inflammatory and anti-fibrotic therapies. However, the exact mechanism by which GPS treats synovial inflammation and fibrosis in KOA remains unclear.

METHODS

Fibroblast-like synoviocytes (FLSs) were stimulated with lipopolysaccharide (LPS) to induce inflammation and fibrosis, and CCK-8 was performed to determine the viability of GPS-treated FLSs, using immunofluorescence to examine the expression of P-PI3K and P-AKT, confocal microscopy was used to identify intracellular HMGB1 translocation. The KOA rat model was established by anterior cruciate ligament transection (ACLT) and subsequently subjected to GPS intervention. Inflammatory cytokines (TNF-α, IL-1β, and IL-6), fibrosis-related indicators (TGF-β, collagen I, TIMP1, and α-SMA), and HMGB1/PI3K/AKT signaling axis-related proteins and gene expression of fibroblast-like synoviocytes and synovial tissues were detected by Western blotting and real-time PCR. The histopathology of the synovium of the rats was assessed using Hematoxylin-eosin (HE), Sirius Red, and Masson staining. Immunohistochemistry was performed to detect the expression of HMGB1, P-PI3K, and P-AKT.

RESULTS

The present study revealed that GPS intervention significantly ameliorated inflammation and fibrosis in LPS-stimulated FLSs and KOA rat synovium. Immunofluorescence demonstrated that GPS inhibited the release of HMGB1 from the nucleus. Furthermore, GPS intervention down-regulates the levels of proteins and gene associated with the HMGB1/PI3K/AKT signaling pathway.

CONCLUSION

GPS ameliorated synovial inflammation and fibrosis in KOA rats, which may involve HMGB1-mediated activation of the PI3K/AKT signaling axis.