目的:Kupffer细胞的激活和单核细胞的募集是纤维发生的关键事件。这些细胞释放可溶性介质,诱导肝星状细胞(HSC)的激活,肝脏内主要的纤维化细胞类型。Mer酪氨酸激酶(MerTK)信号调节巨噬细胞中的多个过程,并且与非酒精性脂肪性肝炎相关纤维化的发病机理有关。在这项研究中,我们探讨了巨噬细胞中的MerTK激活是否影响HSC的促纤维化表型。
方法:巨噬细胞来源于THP-1细胞或从外周血单核细胞分化为MerTK+/CD206+/CD163+/CD209-巨噬细胞。通过药理学和遗传抑制来评估MerTK的作用。HSC迁移是在Boyden室中确定的,通过MTT测定法测量活力,通过BrdU掺入试验评估增殖。
结果:Gas-6诱导巨噬细胞中的MerTK磷酸化和Akt活化,这些效应被UNC569抑制。在极化期间,MerTK+/CD206+/CD163+/CD209-巨噬细胞显示STAT3、ERK1/2、p38的激活和VEGF-A的表达增加。THP-1巨噬细胞中MerTK的活化诱导了促进迁移显著增加的分泌组,扩散,促纤维化因子在HSC中的活力和表达。同样,来自MerTK+巨噬细胞的条件培养基诱导细胞迁移的显著增加,扩散,STAT3和p38磷酸化与IL-8表达上调。此外,来自Gas-6刺激的Kupffer细胞的条件培养基诱导了HSC增殖的显着增加。这些效应与巨噬细胞中的MerTK表达和活性特别相关,如药理抑制和敲低实验所示。
结论:巨噬细胞中的MerTK激活修饰了分泌组以促进HSC的促纤维化特征,该受体与肝纤维化的发病机制有关。
背景:纤维化是慢性肝病患者形成瘢痕的过程。这个过程取决于特定细胞类型的瘢痕组织成分的产生,命名为肝星状细胞,并通过与其他细胞的相互作用来调节。在这里,我们证明了MerTK的激活,存在于巨噬细胞群体中的受体,导致产生作用于肝星状细胞的因子,增加它们产生疤痕组织的能力。
OBJECTIVE: Activation of Kupffer cells and recruitment of monocytes are key events in fibrogenesis. These cells release soluble mediators which induce the activation of hepatic stellate cells (HSCs), the main fibrogenic cell type within the liver. Mer tyrosine kinase (MerTK) signaling regulates multiple processes in macrophages and has been implicated in the pathogenesis of non-alcoholic steatohepatitis-related fibrosis. In this study, we explored if MerTK activation in macrophages influences the profibrogenic phenotype of HSCs.
METHODS: Macrophages were derived from THP-1 cells or differentiated from peripheral blood monocytes towards MerTK+/CD206+/CD163+/CD209- macrophages. The role of MerTK was assessed by pharmacologic and genetic inhibition. HSC migration was determined in Boyden chambers, viability was measured by the MTT assay, and proliferation was evaluated by the BrdU incorporation assay.
RESULTS: Gas-6 induced MerTK phosphorylation and Akt activation in macrophages, and these effects were inhibited by UNC569. During polarization, MerTK+/CD206+/CD163+/CD209- macrophages exhibited activation of STAT3, ERK1/2, p38 and increased expression of VEGF-A. Activation of MerTK in THP-1 macrophages induced a secretome which promoted a significant increase in migration, proliferation, viability and expression of profibrogenic factors in HSCs. Similarly, conditioned medium from MerTK+ macrophages induced a significant increase in cell migration, proliferation, STAT3 and p38 phosphorylation and upregulation of IL-8 expression in HSCs. Moreover, conditioned medium from Gas-6-stimulated Kupffer cells induced a significant increase in HSC proliferation. These effects were specifically related to MerTK expression and activity in macrophages, as indicated by pharmacologic inhibition and knockdown experiments.
CONCLUSIONS: MerTK activation in macrophages modifies the secretome to promote profibrogenic features in HSCs, implicating this receptor in the pathogenesis of hepatic fibrosis.
BACKGROUND: Fibrosis represents the process of scarring occurring in patients with chronic liver diseases. This process depends on production of scar tissue components by a specific cell type, named hepatic stellate cells, and is regulated by interaction with other cells. Herein, we show that activation of MerTK, a receptor present in a population of macrophages, causes the production of factors that act on hepatic stellate cells, increasing their ability to produce scar tissue.