Interplay between canonical Wnt signaling and α5β1 integrins modulates mechanoresponse in human articular cartilage

ObjectivesMechanical cues are essential for maintaining cartilage function, yet how they integrate with molecular pathways dysregulated in osteoarthritis (OA) remains poorly defined in human tissue. Canonical Wnt signalling influences cartilage biology and cell-matrix interactions, but its role in integrin-dependent mechanoregulation in human cartilage is not fully understood. This study aimed to determine how Wnt activation affects chondrocyte responses to physiological mechanical loading, with a focus on 5{beta}1integrin and cytoskeletal organisation. MethodsHuman cartilage explants from non-OA and OA donors were subjected to short-term physiological cyclic compression. Canonical Wnt signalling was activated with CHIR99021, and integrin-mediated adhesion was modulated using the 5{beta}1 blocking peptide ATN-161 during loading. Chondrocyte responses were assessed by analysing mechanoresponsive and matrix-related gene expression, 5{beta}1 complex formation via proximity ligation assay and actin cytoskeletal organisation by confocal microscopy. ResultsOA chondrocytes exhibited a distinct integrin profile, characterised by increased ITGA5 and ITGB1 but reduced ITGA10 expression. In non-OA cartilage, canonical Wnt activation increased ITGB1 expression and 5{beta}1 integrin complex formation, while mechanical loading further enhanced ITGA5 and ITGB1 transcription under Wnt-activated conditions. Under control conditions, loading induced mechanoresponsive and anabolic gene expression in non-OA cartilage; these responses were attenuated following Wnt-activation and partially restored by 5{beta}1 blockade. Mechanical loading induced F-actin reorganization toward a more cortical distribution across cartilage zones, irrespective of disease status or treatment. Wnt activation did not result in distinct cytoskeletal phenotypes under load, and load-induced actin remodelling was comparable between groups. ConclusionThese findings identify 5{beta}1integrin as a key mediator linking canonical Wnt signalling to altered chondrocyte mechanoresponsiveness in human cartilage. While mechanical loading consistently induced cortical F-actin reorganization, Wnt-associated changes in load responsiveness arose primarily from integrin-dependent mechanisms rather than major alterations in actin organization. This study highlights the complexity of cartilage mechanoregulation and identifies integrin-mediated signaling as important contributors to canonical Wnt-driven alterations in load responsiveness relevant to OA.