Neugebauer Julia, Raulien Nora, Arndt Lilli, Akkermann Dagmar, Hobusch Constance, Lindhorst Andreas, Fröba Janine, Gericke Martin
Institute of Anatomy, Leipzig University, 04103 Leipzig, Germany.
Paul-Flechsig-Institute, Leipzig University, 04103 Leipzig, Germany.
Int J Mol Sci. 2024 Dec 4;25(23):13019. doi: 10.3390/ijms252313019.
Obesity is concurrent with immunological dysregulation, resulting in chronic low-grade inflammation and cellular dysfunction. In pancreatic islets, this loss of function has been correlated with mature β-cells dedifferentiating into a precursor-like state through constant exposure to inflammatory stressors. As mature adipocytes likewise have the capability to dedifferentiate in vitro and in vivo, we wanted to analyze this cellular change in relation to adipose tissue (AT) inflammation and adipose tissue macrophage (ATM) activity. Using our organotypic AT explant culture method combined with a double-reporter mouse model for labeling ATMs and mature adipocytes, we were able to visualize and quantify dedifferentiated fat (DFAT) cells in AT explants. Preliminary testing showed increased dedifferentiation after tamoxifen (TAM) stimulation, making TAM-dependent lineage-tracing models unsuitable for quantification of naturally occurring DFAT cells. The regulatory role of ATMs in adipocyte dedifferentiation was shown through macrophage depletion using Plexxicon 5622 or clodronate liposomes, which significantly increased DFAT cell levels. Subsequent bulk RNA sequencing of macrophage-depleted explants revealed enrichment of the tumor necrosis factor α (TNFα) signaling pathway as well as downregulation of associated genes. Direct stimulation with TNFα decreased adipocyte dedifferentiation, while application of a TNFα-neutralizing antibody did not significantly alter DFAT cell levels. Our findings suggest a regulatory role of resident ATMs in maintaining the mature adipocyte phenotype and preventing excessive adipocyte dedifferentiation. The specific regulatory pathways as well as the impact that DFAT cells might have on ATMs, and vice versa, are subject to further investigation.
肥胖与免疫失调同时存在，导致慢性低度炎症和细胞功能障碍。在胰岛中，这种功能丧失与成熟β细胞通过持续暴露于炎症应激源而逆分化为前体样状态有关。由于成熟脂肪细胞同样具有在体外和体内逆分化的能力，我们想要分析这种细胞变化与脂肪组织（AT）炎症和脂肪组织巨噬细胞（ATM）活性的关系。使用我们的器官型AT外植体培养方法，结合用于标记ATM和成熟脂肪细胞的双报告基因小鼠模型，我们能够可视化并量化AT外植体中的去分化脂肪（DFAT）细胞。初步测试显示他莫昔芬（TAM）刺激后去分化增加，使得依赖TAM的谱系追踪模型不适用于定量自然发生的DFAT细胞。通过使用Plexxicon 5622或氯膦酸脂质体清除巨噬细胞，显示了ATM在脂肪细胞去分化中的调节作用，这显著增加了DFAT细胞水平。随后对清除巨噬细胞的外植体进行的批量RNA测序揭示了肿瘤坏死因子α（TNFα）信号通路的富集以及相关基因的下调。用TNFα直接刺激可降低脂肪细胞去分化，而应用TNFα中和抗体并未显著改变DFAT细胞水平。我们的研究结果表明驻留ATM在维持成熟脂肪细胞表型和防止过度脂肪细胞去分化方面具有调节作用。具体的调节途径以及DFAT细胞可能对ATM产生的影响，反之亦然，有待进一步研究。
