Inoue Kosuke, Uchida Kentaro, Matsumoto Mitsuyoshi, Tazawa Ryo, Ohta Etsuro, Hattori Akito, Kenmoku Tomonori, Ito Yuka, Uekusa Yui, Inoue Gen, Takaso Masashi
Department of Orthopaedic Surgery, Kitasato University School of Medicine, 1-15-1 Minami-ku, Kitasato, Sagamihara 252-0374, Kanagawa, Japan.
Division of Blood Transfusion and Transplantation, Kitasato University School of Health Sciences, Minamiuonuma 949-7241, Nigata, Japan.
Curr Issues Mol Biol. 2025 Jul 2;47(7):511. doi: 10.3390/cimb47070511.
Rotator cuff tears are a leading cause of shoulder pain and dysfunction, yet the molecular mechanisms that link tendon injury to inflammation and nociceptive signaling remain poorly understood. Netrin-1, a classical axon guidance cue signaling through dependence receptors UNC5B and Neogenin-1, has been implicated in both neuronal plasticity and inflammatory processes, but its role in tendon pathology has not been explored. A rat supraspinatus tear model was employed to assess, in vivo, the expression of genes encoding netrin-1 () and its receptors ( and ) at 0, 7, 14, 28, and 56 days post-injury (n = 10 per time point). Primary rat tenocytes isolated from rotator cuff tissue were treated in vitro with recombinant netrin-1, and transcriptional changes in genes encoding TNF-α (), IL-6 (), MMP-1 (), and MMP-3 () were quantified by qRT-PCR. Separately, human iPSC-derived sensory neurons were exposed to netrin-1, and dose- and time-dependent effects on neurite outgrowth were measured at 4 and 14 days in culture. In injured tendons, mRNA increased significantly at day 14 ( = 0.010) and 28 ( = 0.042), at day 7 ( = 0.002) and 14 ( < 0.001), and at day 14 ( < 0.001) versus intact controls. Tenocyte exposure to 500 ng/mL netrin-1 induced transient upregulation of (3 h, = 0.023; 6 h, = 0.009) and (3 h-24 h, all < 0.013), as well as (3-24 h, < 0.043) and (6 h-24 h, < 0.024); no induction was observed at 50 ng/mL. In sensory neurons, 50 ng/mL of netrin-1 enhanced neurite extension at day 4 ( = 0.006) but not at 500 ng/mL or at day 14 for either dose. Netrin-1 and its receptors are upregulated in a rat rotator cuff tear model, and netrin-1 elicits distinct pro-inflammatory and matrix-remodeling responses in tenocytes while promoting early neurite growth in sensory neurons. These findings suggest netrin-1 as a key modulator of tendon inflammation, matrix turnover, and peripheral nerve plasticity following injury.
肩袖撕裂是肩部疼痛和功能障碍的主要原因，然而，将肌腱损伤与炎症和伤害性信号联系起来的分子机制仍知之甚少。Netrin-1是一种通过依赖受体UNC5B和Neogenin-1发出信号的经典轴突导向因子，已被证明与神经元可塑性和炎症过程有关，但其在肌腱病理中的作用尚未得到探索。采用大鼠冈上肌撕裂模型，在体内评估损伤后0、7、14、28和56天编码Netrin-1（）及其受体（和）的基因表达（每个时间点n = 10）。从肩袖组织中分离出的原代大鼠肌腱细胞在体外用重组Netrin-1处理，通过qRT-PCR定量编码TNF-α（）、IL-6（）、MMP-1（）和MMP-3（）的基因的转录变化。另外，将人诱导多能干细胞衍生的感觉神经元暴露于Netrin-1，并在培养4天和14天时测量对神经突生长的剂量和时间依赖性影响。在受伤的肌腱中，与完整对照相比，在第14天（= 0.010）和28天（= 0.042）时mRNA显著增加，在第7天（= 0.002）和14天（< 0.001）时增加，在第14天（< 0.001）时增加。肌腱细胞暴露于500 ng/mL Netrin-1会诱导（3小时，= 0.023；6小时，= 0.009）和（3小时 - 24小时，均< 0.013）以及（3 - 24小时，< 0.043）和（6小时 - 24小时，< 0.024）的瞬时上调；在50 ng/mL时未观察到诱导作用。在感觉神经元中，50 ng/mL的Netrin-1在第4天增强了神经突延伸（= 0.006），但在500 ng/mL时或在两个剂量的第14天时均未增强。Netrin-1及其受体在大鼠肩袖撕裂模型中上调，并且Netrin-1在肌腱细胞中引发不同的促炎和基质重塑反应，同时促进感觉神经元中的早期神经突生长。这些发现表明Netrin-1是损伤后肌腱炎症、基质周转和周围神经可塑性的关键调节因子。
