Sheng Kai, Bisson Daniel G, Saran Neil, Bourdages Jake, Coluni Christopher, Upshaw Kirby, Tiedemann Kerstin, Komarova Svetlana V, Ouellet Jean A, Haglund Lisbet
Shriners Hospital for Children, Montreal, QC, Canada.
Department of Surgery, Orthopaedic Research Laboratory, Mcgill University, Montreal, QC, Canada.
Arthritis Res Ther. 2025 Mar 31;27(1):68. doi: 10.1186/s13075-025-03535-6.
Facet joint osteoarthritis (OA) is prevalent in patients with adolescent idiopathic scoliosis (AIS). The most pronounced OA presents above and below the curve's apex where the intervertebral rotation is the greatest. This indicates that facet joint OA is implicated and potentially contributes to AIS progression. OA impacts both cartilage and bone and we have previously demonstrated an association between lower bone quality and more severe OA in AIS facet joints. This study aimed to further investigate the molecular mechanisms underlying cartilage-bone crosstalk in the facet joints of patients with AIS.
Unbiased deep RNA sequencing was performed to compare gene expression in facet joint chondrocytes of age-matched AIS patients and non-scoliotic individuals. Differentially expressed genes of interest were validated through qPCR and ELISA in a larger sample cohort. Key regulatory pathways involved in cartilage-bone crosstalk were identified through bioinformatic analysis. Functional studies were conducted by treating chondrocytes with TLR2 and TLR4 agonists, collecting conditioned media, and administering it to an in vitro osteoclastogenesis model. The expression of M-CSF, a key regulatory factor influencing osteoclast proliferation, was measured in individual facet joint cartilage samples at different spinal levels and correlated with cartilage morphological grade and 3D structural parameters extracted from spine reconstruction.
One thousand four hundred twenty six upregulated genes were detected, and gene ontology analysis revealed a significant enrichment of the TLR pathway, and bone-regulating biological processes in AIS chondrocytes. TLR activation of AIS chondrocytes induced expression of bone-regulating factors, including M-CSF, a key regulator of osteoclast proliferation. Furthermore, secreted factors from AIS chondrocytes enhanced osteoclast proliferation and maturation, with a stronger effect observed following TLR pre-activation. Clinically, M-CSF expression was found to correlate strongly with increased OA severity and a greater degree of intervertebral axial rotation.
Together, our findings suggest that the TLR-M-CSF axis is implicated in osteoclastogenesis, resulting in increased bone turnover and may contribute to curve progression in AIS patients.
小关节骨关节炎（OA）在青少年特发性脊柱侧凸（AIS）患者中很常见。最明显的OA出现在曲线顶点的上方和下方，此处椎间旋转最大。这表明小关节OA与之相关，并可能导致AIS进展。OA会影响软骨和骨骼，我们之前已经证明AIS小关节中较低的骨质量与更严重的OA之间存在关联。本研究旨在进一步探讨AIS患者小关节软骨-骨相互作用的分子机制。
进行无偏深度RNA测序，以比较年龄匹配的AIS患者和非脊柱侧凸个体的小关节软骨细胞中的基因表达。通过qPCR和ELISA在更大的样本队列中验证感兴趣的差异表达基因。通过生物信息学分析确定参与软骨-骨相互作用的关键调控途径。通过用TLR2和TLR4激动剂处理软骨细胞、收集条件培养基并将其应用于体外破骨细胞生成模型来进行功能研究。在不同脊柱水平的单个小关节软骨样本中测量影响破骨细胞增殖的关键调控因子M-CSF的表达，并将其与软骨形态学分级以及从脊柱重建中提取的3D结构参数相关联。
检测到1426个上调基因，基因本体分析显示AIS软骨细胞中TLR途径和骨调节生物学过程显著富集。AIS软骨细胞的TLR激活诱导了骨调节因子的表达，包括破骨细胞增殖的关键调节因子M-CSF。此外，AIS软骨细胞分泌的因子增强了破骨细胞的增殖和成熟，TLR预激活后观察到更强的作用。临床上，发现M-CSF表达与OA严重程度增加和椎间轴向旋转程度更大密切相关。
总之，我们的研究结果表明TLR-M-CSF轴与破骨细胞生成有关，导致骨转换增加，并可能导致AIS患者的曲线进展。
