Abstract
BACKGROUND: Osteoarthritis (OA) is a chronic condition characterized by joint pain and disability, driven by excessive oxidative stress and inflammatory cytokine production in chondrocytes, resulting in cell death and cartilage matrix breakdown. Our previous study showed that in monosodium iodoacetate (MIA)-induced OA rats, oral administration of heat-killed Lactobacillus delbrueckii subsp. lactis 557 (LDL557) could significantly decrease OA progression. METHODS: Accordingly, we designed an in vitro cell culture study aimed at investigating the effects of heat-killed LDL557 extracts on chondrocytes using SW1353 cells (a human chondrosarcoma cell line) challenged with 5 μM MIA to mimic OA conditions. RESULTS: The results showed that the 10 μg/mL LDL557 extracts protected SW1353 cells from MIA-induced death and reduced extracellular matrix (ECM) loss, as evaluated by toluidine blue O staining and extracellular matrix component synthesis with RT-qPCR measurement. This was achieved by decreasing the expression of MIA-induced pro-inflammatory cytokines, including IL-1β, IL-6, and TNF-α, while slightly increasing the MIA-suppressed expression of the anti-inflammatory cytokine IL-10, which were evidenced by RT-qPCR analysis. Moreover, the RT-qPCR evaluation also indicated that the LDL557 extracts slightly reduced the expression of COX-2 compared with the control, while it did not reduce the MIA-increased expression of microsomal prostaglandin E synthase-1 (mPGES-1). In addition, the LDL557 extracts influenced neither the matrix-degrading protease expressions measured via RT-qPCR nor the oxidative stress measured via fluorescence flow cytometry in the cells with or without the MIA challenge. CONCLUSIONS: This study demonstrates that LDL557 extracts may protect chondrocytes from OA damage by reducing inflammation-related factors and thus mitigating cartilage matrix loss, suggesting LDL557 extracts are attractive alternatives for OA applications.