Objective To investigate the effect of catalpol on lipopolysaccharide (LPS)-induced inflammatory injury, extracellular matrix (ECM) metabolic dysregulation and pyroptosis in chondrocytes, and to explore whether these effects involve the AMP-activated protein kinase (AMPK)/nuclear factor-κB (NF-κB)/NOD like receptor family pyrin domain containing 3 (NLRP3) signaling axis. Methods Network pharmacology was used to screening the intersection targets of catalpol, knee osteoarthritis and pyroptosis and enrichment analysis were performed. LPS was used to establish an inflammatory injury and induce pyroptosis model, followed by pretreatment with catalpol (20, 50 μmol/L) for 1 h. Protein expressions of collagen type II alpha 1 chain (COL2A1), aggrecan (ACAN), matrix metalloproteinase 3 (MMP3), MMP13 and key molecules in AMPK/NF-κB/NLRP3 signaling axis were detected by Western blotting. Lactate dehydrogenase (LDH) release assay was performed to assess cell membrane integrity-related injury. The levels of interleukin-1β (IL-1β) and IL-18 in supernatants were detected by ELISA. The mRNA levels of NLRP3, IL-1β, IL-6 and tumor necrosis factor-α (TNF-α) were detected by qRT-PCR. The cystein-asparate protease-1 (Caspase-1) inhibitor VX-765 was used as a positive control, the mechanism was further validated using AMPK inhibitor Compound C. Results Compared with control group, LPS stimulation could induce a decrease in ECM synthesis and an increase in ECM decomposition, significantly activate the NLRP3 related pyroptosis pathway (P < 0.001). Compared with model group, catalpol could significantly upregulate the expressions of COL2A1, ACAN and downregulate the expressions of MMP3, MMP13 (P < 0.05, 0.01, 0.001), while significantly reduce the release of LDH, IL-1β and IL-18 (P < 0.01, 0.001), and inhibit NLRP3, cleaved Caspase-1, N-terminal fragment of gasdermin D (GSDMD-N) and other pyroptosis related indicators (P < 0.05, 0.001). In addition, catalpol could significantly upregulate the expressions of p-AMPK/AMPK and phosphorylated acetyl CoA carboxylase (p-ACC)/ACC (P < 0.05, 0.001), and downregulate the expression of p-p65/p65 (P < 0.001), while downregulate the expressions of NLRP3, IL-1β, IL-6, TNF-α inflammation related genes (P < 0.05, 0.001). AMPK inhibitor Compound C could partially reverse the above-mentioned effects of catalpol (P < 0.05, 0.01, 0.001). Conclusion Catalpol may protect the matrix homeostasis of chondrocytes by activating AMPK and promoting downstream ACC phosphorylation, inhibiting NF-κB/NLRP3 related pathways.

catalpol  /  chondrocytes  /  pyroptosis  /  AMPK  /  knee osteoarthritis  /  NF-κB/NLRP3 pathway