Chondroitin sulfate alleviated lipopolysaccharide-induced arthritis in feline and canine articular chondrocytes through regulation of neurotrophic signaling pathways and apoptosis

Osteoarthritis (OA) is a pervasive degenerative joint disease affecting companion animals, characterized by chronic inflammation and cartilage degradation. However, the effectiveness of chondroitin sulfate (CS) in treating OA in dogs and cats remains controversial. This study aimed to determine the therapeutic effects and molecular mechanisms of CS on lipopolysaccharide (LPS)-induced inflammation in feline and canine articular chondrocytes (FAC and CAC) at the cellular level in vitro. Our findings demonstrated that CS treatment (800 µg/mL) significantly enhanced cell viability and reduced oxidative stress in FAC and CAC, as evidenced by decreased levels of reactive oxygen species and increased activities of antioxidant enzymes. Furthermore, CS treatment effectively suppressed LPS-induced secretion of pro-inflammatory cytokines, including interleukin-1, tumor necrosis factor-α, interleukin-8, interleukin-10, and matrix metalloproteinases-3, and reduced apoptosis, as confirmed by fluorescence staining and flow cytometry. Transcriptomic analysis revealed that CS upregulated neurotrophic signaling pathways, promoting cell survival and proliferation. Metabolomic analysis indicated that CS treatment upregulated metabolites associated with glycerophospholipid and purine metabolism, suggesting enhanced membrane integrity and energy metabolism. Conversely, pathways involved in protein catabolism and arachidonic acid metabolism were downregulated, indicating a reduction in inflammatory mediators. Collectively, these findings elucidate the multifaceted role of CS in modulating chondrocyte metabolism and inflammatory responses, highlighting its potential to alleviate OA.