Inflammation-Associated Changes in Piezo1 Expression, Mitophagy-Related Markers, and Matrix Dysregulation in an LPS-Stimulated Co-Culture Organoid System

Osteoarthritis (OA) is a progressive joint disease characterized by cartilage degeneration, chronic low-grade inflammation, and disruption of tissue homeostasis. Although the mechanosensitive ion channel Piezo1 has been implicated in OA pathogenesis, its expression may also be modulated by inflammatory stimuli independently of applied mechanical loading. This study established a scaffold-free three-dimensional co-culture organoid model comprising human bone marrow-derived mesenchymal stem cell-derived chondrocyte-like cells and M-CSF/RANKL-differentiated RAW264.7-derived osteoclast-like cells to investigate Piezo1-associated molecular responses, inflammatory signaling, and mitophagy-related markers under lipopolysaccharide (LPS)-induced inflammatory conditions. Osteoclast-like differentiation was validated in parallel monolayer cultures by tartrate-resistant acid phosphatase staining and the presence of multinucleated cells before the corresponding differentiated cultures were used for organoid generation. Histological staining, immunofluorescence, CellTiter-Glo 3D viability assay, lactate dehydrogenase cytotoxicity assay, RT-qPCR, and Western blotting were used to evaluate extracellular matrix formation and inflammatory, catabolic, and mitochondrial quality-control-associated markers. LPS stimulation increased the expression of Piezo1, HIF-1α, phosphorylated CaMKII, NLRP3, cleaved Caspase-1, and MMP13, together with alterations in mitophagy- and autophagy-associated markers. Among the evaluated compounds, curcumin produced the greatest improvement in viability relative to the LPS-treated group and was selected for subsequent molecular analyses. Curcumin treatment was associated with reduced inflammatory and catabolic marker expression and partial preservation of cartilage-associated matrix markers. These findings demonstrate inflammation-associated changes in Piezo1 expression and related molecular markers but do not establish mechanically activated Piezo1 signaling or Piezo1-dependent causality. The organoid system therefore represents an exploratory LPS-induced inflammatory model exhibiting selected OA-relevant molecular and matrix-associated features.