Wang Haoran, Zhu Zekai, Liu Jun
Department of Orthopaedics, Tongji Hospital of Tongji University, School of Medicine, Tongji University, Shanghai, China.
Department of Orthopaedics, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China.
Front Immunol. 2025 Sep 3;16:1628970. doi: 10.3389/fimmu.2025.1628970. eCollection 2025.
Epidural scar hyperplasia is a prevalent complication post-laminectomy, contributing significantly to persistent low back pain and other symptoms, ultimately undermining surgical outcomes. Previous studies have identified fibroblast proliferation and differentiation, as well as adipocyte fibrosis, as central to this process, though the precise mechanisms remain elusive.
A model of laminectomy was established using wild-type mice and IFITM1-KO mice. Methods such as HE staining and Masson staining were employed to assess the degree of fibrosis in the postoperative wound area of the mice. Immunofluorescence and Western blot were performed to verify the localization of IFITM1 and fibronectin. NIH-3T3 fibroblast cells and primary fibroblast cell models were established, and immunoblotting was used to detect changes in the expression levels of fibronectin, P-smad3, smad3, and IFITM1. Subsequently, co-immunoprecipitation was conducted to preliminarily demonstrate that CBR4 is a related protein of IFITM1. The amounts of adipose tissue and CBR4 in the postoperative wound area were compared between wild-type and IFITM1-KO mice in the laminectomy model. CBR4 localization was examined using immunofluorescence, followed by the establishment of an in vitro adipocyte model, where Oil Red O staining and other methods were utilized to confirm the process of adipocyte fibrosis and the roles of IFITM1/CBR4 therein.
In a murine laminectomy model, fibroblast proliferation, activation, and adipocyte fibrosis were found to exacerbate epidural scar formation. IFITM1, a critical protein regulating cell proliferation, is expressed in fibroblasts. The proliferation and activation of fibroblasts, characterized by high IFITM1 expression, were inhibited by suppression of the SMAD3 signaling pathway. studies revealed a reduction in epidural fibrosis following laminectomy in the absence of IFITM1. Additionally, CBR4, a protein associated with IFITM1 and involved in fatty acid synthesis, showed reduced expression in adipocytes under inflammatory conditions, triggering their transformation into fibroblasts, a process regulated by IFITM1. Our animal experiments also confirmed the presence of adipose tissue within epidural scars, with IFITM1 deficiency correlating with reduced adipose tissue and increased CBR4 expression.
These findings demonstrate that IFITM1 inhibits fibroblast proliferation and differentiation SMAD3 signaling suppression and modulates adipocyte fibrosis by regulating CBR4 expression, thereby influencing epidural scar hyperplasia post-laminectomy.
硬膜外瘢痕增生是椎板切除术后常见的并发症，对持续性腰痛和其他症状有显著影响，最终会影响手术效果。以往的研究已确定成纤维细胞增殖与分化以及脂肪细胞纤维化是这一过程的核心，但确切机制仍不清楚。
使用野生型小鼠和IFITM1基因敲除小鼠建立椎板切除模型。采用苏木精-伊红染色和Masson染色等方法评估小鼠术后伤口区域的纤维化程度。进行免疫荧光和蛋白质免疫印迹以验证IFITM1和纤连蛋白的定位。建立NIH-3T3成纤维细胞模型和原代成纤维细胞模型，并用免疫印迹检测纤连蛋白、磷酸化Smad3、Smad3和IFITM1表达水平的变化。随后，进行免疫共沉淀以初步证明CBR4是IFITM1的相关蛋白。比较椎板切除模型中野生型和IFITM1基因敲除小鼠术后伤口区域的脂肪组织量和CBR4量。用免疫荧光检测CBR4定位，随后建立体外脂肪细胞模型，采用油红O染色等方法确认脂肪细胞纤维化过程以及IFITM1/CBR4在其中的作用。
在小鼠椎板切除模型中，发现成纤维细胞增殖、活化以及脂肪细胞纤维化会加剧硬膜外瘢痕形成。IFITM1是一种调节细胞增殖的关键蛋白，在成纤维细胞中表达。以高IFITM1表达为特征的成纤维细胞增殖和活化受到SMAD3信号通路抑制的抑制。研究显示，在缺乏IFITM1的情况下，椎板切除术后硬膜外纤维化减少。此外，CBR4是一种与IFITM1相关且参与脂肪酸合成的蛋白，在炎症条件下其在脂肪细胞中的表达降低，促使脂肪细胞转化为成纤维细胞，这一过程受IFITM1调节。我们的动物实验还证实硬膜外瘢痕内存在脂肪组织，IFITM1缺乏与脂肪组织减少和CBR4表达增加相关。
这些研究结果表明，IFITM1通过抑制SMAD3信号通路抑制成纤维细胞增殖和分化，并通过调节CBR4表达来调节脂肪细胞纤维化，从而影响椎板切除术后的硬膜外瘢痕增生。
