State Key Laboratory of Genetic Engineering, School of Life Science, and Human Phenome Institute, Zhangjiang Fudan International Innovation Center, Fudan University, Shanghai, China.
Department of Dermatology, Jing'an District Central Hospital, Shanghai, China.
Arthritis Res Ther. 2023 Oct 5;25(1):194. doi: 10.1186/s13075-023-03142-3.
Ankylosing spondylitis (AS) is a chronic inflammatory disease that mainly affects the sacroiliac joint and spine. However, the real mechanisms of immune cells acting on syndesmophyte formation in AS are not well identified. We aimed to find the key AS-associated cytokine and assess its pathogenic role in AS.
A protein array with 1000 cytokines was performed in five AS patients with the first diagnosis and five age- and gender-matched healthy controls to discover the differentially expressed cytokines. The candidate differentially expressed cytokines were further quantified by multiplex protein quantitation (3 AS-associated cytokines and 3 PDGF-pathway cytokines) and ELISA (PDGFB) in independent samples (a total of 140 AS patients vs 140 healthy controls). The effects of PDGFB, the candidate cytokine, were examined by using adipose-derived stem cells (ADSCs) and human fetal osteoblast cell line (hFOB1.19) as in vitro mesenchymal cell and preosteoblast models, respectively. Furthermore, whole-transcriptome sequencing and enrichment of phosphorylated peptides were performed by using cell models to explore the underlying mechanisms of PDGFB. The xCELLigence system was applied to examine the proliferation, chemotaxis, and migration abilities of PDGFB-stimulated or PDGFB-unstimulated cells.
The PDGF pathway was observed to have abnormal expression in the protein array, and PDGFB expression was further found to be up-regulated in 140 Chinese AS patients. Importantly, PDGFB expression was significantly correlated with BASFI (Pearson coefficient/p value = 0.62/6.70E - 8) and with the variance of the mSASSS score (mSASSS , Pearson coefficient/p value = 0.76/8.75E - 10). In AS patients, preosteoclasts secreted more PDGFB than the healthy controls (p value = 1.16E - 2), which could promote ADSCs osteogenesis and enhance collagen synthesis (COLI and COLIII) of osteoblasts (hFOB 1.19). In addition, PDGFB promoted the proliferation, chemotaxis, and migration of ADSCs. Mechanismly, in ADSCs, PDGFB stimulated ERK phosphorylation by upregulating GRB2 expression and then increased the expression of RUNX2 to promote osteoblastogenesis of ADSCs.
PDGFB stimulates the GRB2/ERK/RUNX2 pathway in ADSCs, promotes osteoblastogenesis of ADSCs, and enhances the extracellular matrix of osteoblasts, which may contribute to pathological bone formation in AS.
强直性脊柱炎（AS）是一种主要影响骶髂关节和脊柱的慢性炎症性疾病。然而，免疫细胞在 AS 中形成骨桥的真正机制尚不清楚。我们旨在寻找关键的 AS 相关细胞因子，并评估其在 AS 中的致病作用。
对 5 例初诊 AS 患者和 5 名年龄和性别匹配的健康对照者进行了 1000 种细胞因子的蛋白质芯片检测，以发现差异表达的细胞因子。通过多重蛋白质定量（3 种 AS 相关细胞因子和 3 种 PDGF 通路细胞因子）和 ELISA（PDGFB）在独立样本中进一步定量候选差异表达细胞因子（共 140 例 AS 患者与 140 例健康对照者）。使用脂肪来源的干细胞（ADSCs）和人胎成骨细胞系（hFOB1.19）作为体外间充质细胞和前成骨细胞模型，分别检测候选细胞因子 PDGFB 的作用。此外，通过细胞模型进行全转录组测序和磷酸化肽富集，以探索 PDGFB 的潜在机制。应用 xCELLigence 系统检测 PDGFB 刺激或未刺激细胞的增殖、趋化性和迁移能力。
在蛋白质芯片中观察到 PDGF 通路异常表达，并且 PDGFB 表达在 140 例中国 AS 患者中进一步上调。重要的是，PDGFB 表达与 BASFI 显著相关（Pearson 系数/p 值=0.62/6.70E-8），与 mSASSS 评分方差显著相关（mSASSS ，Pearson 系数/p 值=0.76/8.75E-10）。在 AS 患者中，前破骨细胞分泌的 PDGFB 多于健康对照者（p 值=1.16E-2），可促进 ADSCs 成骨，并增强成骨细胞（hFOB 1.19）的胶原合成（COLI 和 COLIII）。此外，PDGFB 促进了 ADSCs 的增殖、趋化和迁移。在 ADSCs 中，PDGFB 通过上调 GRB2 表达刺激 ERK 磷酸化，然后增加 RUNX2 的表达，从而促进 ADSCs 的成骨。
PDGFB 在 ADSCs 中刺激 GRB2/ERK/RUNX2 通路，促进 ADSCs 的成骨，并增强成骨细胞的细胞外基质，这可能有助于 AS 中的病理性骨形成。
