Eggshell Membrane Peptides Alleviate IL-1β-Induced Inflammatory Responses and Extracellular Matrix Degradation in Canine Chondrocytes by Inhibiting the NF-κB Signaling Pathway

Background: Eggshell membrane peptides (ESMPs) are natural bioactive compounds with reported chondroprotective properties. However, their regulatory effects on canine chondrocytes remain unclear. This study investigated ESMP in an interleukin-1β (IL-1β)-induced inflammatory model of canine chondrocytes. Methods: Chondrocytes were assigned to control (Cont), IL-1β, and ESMP + IL-1β groups. Cell viability was assessed using the Cell Counting Kit-8 (CCK-8) assay. NF-κB p65 nuclear translocation was evaluated by immunofluorescence staining. Real-time quantitative PCR (RT-qPCR) and Western blotting (WB) were used to measure mRNA and protein expression levels, respectively. Results: ESMP inhibited IL-1β-induced NF-κB p65 nuclear translocation and reduced the IL-1β-induced increases in interleukin-6 (IL-6), cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and matrix metalloproteinase-13 (MMP-13) at both mRNA and protein levels. ESMP also decreased IL-6, nitric oxide (NO), and prostaglandin E2 (PGE2) levels in culture supernatants. ESMP reversed the IL-1β-induced reduction in type II collagen α1 chain (COL2A1) and aggrecan (ACAN) expression at both transcriptional and protein levels. Conclusions: ESMP attenuates IL-1β-induced inflammatory responses and extracellular matrix degradation in canine chondrocytes, potentially associated with suppression of NF-κB p65 nuclear translocation. This supports its potential application in promoting joint health in dogs.