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.

中文翻译：

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DMT1介导的铁过载通过mtDNA-cGAS-STING轴加速血友病关节病的软骨退化

过量的铁会导致血友病性关节病 (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。我们的目的是研究 DMT1 介导的铁稳态是否参与出血引起的软骨退变以及铁过载引起的软骨细胞损伤的分子机制。本研究通过用针刺破凝血因子VIII基因敲除小鼠的膝关节建立了体内HA模型，并通过柠檬酸铁铵（FAC）处理来模拟体外铁超载条件。我们证明血液暴露会导致铁超载和软骨退化，以及 DMT1 表达升高。此外，DMT1 沉默可减轻血液引起的铁过载和软骨退化。在血友病小鼠中，关节软骨变性也可以通过关节内注射 DMT1 腺相关病毒 9 (AAV9) 得到抑制。从机制上讲，RNA 测序分析表明铁过载与 cGAS-STING 通路之间存在关联。此外，铁过载会触发 mtDNA-cGAS-STING 通路激活，而 DMT1 沉默可以有效缓解这种激活。此外，我们发现 RU.521 是一种有效的环 GMP-AMP 合酶 (cGAS) 抑制剂，可成功抑制 cGAS-STING 的向下级联，从而防止软骨细胞损伤。综上所述，DMT1 介导的铁过载会促进软骨细胞损伤和小鼠 HA 的发育，而靶向 DMT1 可能为 HA 提供治疗和预防方法。