Loss of periodontal ligament fibroblasts (PDLFs) is one critical issue for regenerating lost periodontal tissues. A wide variety of regulated cell death pathways, such as apoptosis, pyroptosis, and necroptosis have been proposed in the periodontitis development. The aim of the present study was to explore whether long-term periodontitis-level butyrate may trigger ferroptosis, a newly characterized iron-dependent regulated cell death in PDLFs. Here, we showed that long-term treatment of butyrate, an important short-chain fatty acid in the periodontal pocket, induces the cargo receptor nuclear receptor coactivator 4 (NCOA4)-mediated ferritinophagy and ferroptosis in PDLFs. Butyrate-induced iron accumulation, reactive oxygen species (ROS) generation, glutathione depletion and lipid peroxidation in PDLFs, and the butyrate-induced ferroptosis can be blocked by the lipid peroxide scavenger ferrostatin-1. The NCOA4-mediated ferritinophagy is dependent on p38/hypoxia inducible factor-1α (HIF-1α) pathway activation as well as Bromodomain-containing protein (BRD) 4 and cyclin-dependent kinase 9 (CDK9) coordination. These lines of evidence provide a new mechanistic insight into the mechanism of loss of PDLFs during periodontitis development, showing that periodontitis-level butyrate disrupted iron homeostasis by activation of NCOA4-mediated ferritinophagy, leading to ferroptosis in PDLFs.

牙周膜成纤维细胞（PDLF）的丢失是再生丢失的牙周组织的关键问题之一。在牙周炎的发展中已经提出了多种调控的细胞死亡途径，例如凋亡，发烧和坏死性坏死。本研究的目的是探讨长期牙周炎水平的丁酸盐是否会引发铁锈病，这是PDLFs中铁依赖性调节细胞死亡的新特征。在这里，我们表明长期治疗丁酸（牙周袋中的一种重要的短链脂肪酸）会诱导PDLFs的货运受体核受体共激活因子4（NCOA4）介导的铁蛋白吞噬作用和肥大症。PDLF中丁酸盐引起的铁积累，活性氧（ROS）产生，谷胱甘肽耗竭和脂质过氧化，脂质过氧化物清除剂ferrostatin-1可以阻止丁酸盐引起的肥大病。NCOA4介导的铁蛋白吞噬依赖于p38 /低氧诱导因子1α（HIF-1α）途径激活以及含溴结构域蛋白（BRD）4和细胞周期蛋白依赖性激酶9（CDK9）的协调。这些证据为牙周炎发展过程中PDLFs的丧失机理提供了新的机械原理，表明牙周炎水平的丁酸酯通过激活NCOA4介导的铁蛋白吞噬作用而破坏了铁稳态，从而导致PDLFs的肥大化。