背景：过量的铁有助于血友病性关节病（HA）的发展。二价金属转运蛋白1（DMT1）将铁输送到细胞质中，从而调节铁稳态。
目的：我们旨在研究DMT1介导的铁稳态是否参与出血诱导的软骨退变以及铁过载诱导的软骨细胞损伤的分子机制。
方法：本研究通过针刺凝血因子VIII基因敲除小鼠膝关节建立体内HA模型，并通过柠檬酸铁铵（FAC）处理在体外模拟铁过载条件。
结果：我们证明了血液暴露导致铁过载和软骨退化，以及DMT1的表达升高。此外，DMT1沉默可减轻血液诱导的铁过载和软骨退变。在血友病小鼠中，关节内注射DMT1腺相关病毒9（AAV9）也抑制了关节软骨变性。机械上,RNA测序分析表明铁过载与cGAS-STING途径之间存在关联。Further,铁过载引发mtDNA-cGAS-STING通路激活，DMT1沉默可以有效缓解。此外,我们发现RU.521是一种有效的环GMP-AMP合成酶（cGAS）抑制剂，成功抑制了cGAS-STING的下行级联，从而保护软骨细胞免受损伤。
结论：综合来看，DMT1介导的铁超负荷促进软骨细胞损伤和小鼠HA发育，和靶向DMT1可以在HA中提供治疗和预防方法。
Excess iron contributes to Hemophilic Arthropathy (HA) development. Divalent metal transporter 1 (DMT1) delivers iron into the cytoplasm, thus regulating iron homeostasis.
We aimed to investigate whether DMT1-mediated iron homeostasis is involved in bleeding-induced cartilage degeneration and the molecular mechanisms underlying iron overload-induced chondrocyte damage.
This study established an in vivo HA model by puncturing knee joints of coagulation factor VIII gene knockout mice with a needle, and mimicked iron overload conditions in vitro by treatment of Ferric ammonium citrate (FAC).
We demonstrated that blood exposure caused iron overload and cartilage degeneration, as well as elevated expression of DMT1. Furthermore, DMT1 silencing alleviated blood-induced iron overload and cartilage degeneration. In hemophilic mice, articular cartilage degeneration was also suppressed by intro-articularly injection of DMT1 adeno-associated virus 9 (AAV9). Mechanistically, RNA-sequencing analysis indicated the association between iron overload and cGAS-STING pathway. Further, iron overload triggered mtDNA-cGAS-STING pathway activation, which could be effectively mitigated by DMT1 silencing. Additionally, we discovered that RU.521, a potent Cyclic GMP-AMP Synthase (cGAS) inhibitor, successfully suppressed the downward cascades of cGAS-STING, thereby protecting against chondrocyte damage.
Taken together, DMT1-mediated iron overload promotes chondrocyte damage and murine HA development, and targeted DMT1 may provide therapeutic and preventive approaches in HA.
