Lüdemann Willie M, Heide Danijela, Kihm Lars, Zeier Martin, Scheurich Peter, Schwenger Vedat, Ranzinger Julia
Department of Nephrology, University of Heidelberg, Heidelberg, Germany.
Institute of Cell Biology and Immunology, University of Stuttgart, Stuttgart, Germany.
Perit Dial Int. 2017 May-Jun;37(3):250-258. doi: 10.3747/pdi.2016.00138. Epub 2017 Jan 17.
♦ BACKGROUND: Peritoneal dialysis (PD) coincides with high concentrations of proinflammatory cytokines, such as tumor necrosis factor (TNF), in the peritoneal cavity. During treatment, chronic inflammatory processes lead to damage of the peritoneal membrane and a subsequent ultrafiltration failure. Human peritoneal mesothelial cells (HPMCs) play a central role as mediators and targets of PD-related inflammatory changes. Although TNF Receptor 1 (TNFR1) is expressed in high numbers on the cells, TNF-induced apoptosis is inhibited. Here, the underlying molecular mechanisms of TNFR1 signaling in HPMCs are investigated. ♦ METHODS: Human peritoneal mesothelial cells were isolated from the omentum of healthy donors and the dialysis solution of PD patients. Flow cytometry was applied to determine cell surface expression of TNFR1 on HPMCS from healthy donors in absence or presence of TNF or PD fluid (PDF) and were compared to TNFR1 expression on cells from PD patients. To investigate TNFR1-mediated signaling, HPMCs were treated with PDF or TNF, and expression patterns of proteins involved in the TNFR1 signaling pathway were assessed by western blot. ♦ RESULTS: Incubation with PDF led to a significant up-regulation of TNFR1 on the cell surface correlating with elevated TNFR1 numbers on HPMCs from PD patients. Investigations of underlying molecular mechanisms of TNFR1 signaling showed that PDF affects TNFR1 signaling at the proapoptotic signaling pathway by upregulation of IκBα and downregulation of cFLIP. In contrast, TNF exclusively induces the activation of NFκB by an increase of phosphorylated IκBα. ♦ CONCLUSIONS: Novel and relevant insights into the mechanisms of TNFR1-mediated signaling in HPMCs with an impact on our understanding of PD-associated damage of the peritoneal membrane are shown.
♦ 背景：腹膜透析（PD）与腹腔内高浓度的促炎细胞因子如肿瘤坏死因子（TNF）同时存在。在治疗过程中，慢性炎症过程会导致腹膜损伤以及随后的超滤功能衰竭。人腹膜间皮细胞（HPMC）作为PD相关炎症变化的介质和靶点发挥着核心作用。尽管TNF受体1（TNFR1）在这些细胞上大量表达，但TNF诱导的细胞凋亡却受到抑制。在此，研究了HPMC中TNFR1信号传导的潜在分子机制。♦ 方法：从健康供体的大网膜和PD患者的透析液中分离出人腹膜间皮细胞。应用流式细胞术测定在有无TNF或腹膜透析液（PDF）情况下健康供体来源的HPMC上TNFR1的细胞表面表达，并与PD患者细胞上的TNFR1表达进行比较。为了研究TNFR1介导的信号传导，用PDF或TNF处理HPMC，并通过蛋白质印迹法评估TNFR1信号通路中相关蛋白质的表达模式。♦ 结果：与PDF孵育导致细胞表面TNFR1显著上调，这与PD患者来源的HPMC上TNFR1数量增加相关。对TNFR1信号传导潜在分子机制的研究表明，PDF通过上调IκBα和下调cFLIP影响促凋亡信号通路中的TNFR1信号传导。相比之下，TNF仅通过磷酸化IκBα的增加诱导NFκB的激活。♦ 结论：展示了对HPMC中TNFR1介导的信号传导机制的新的相关见解，这对我们理解PD相关的腹膜损伤具有重要意义。
