Sadeghi Kambis, Wisgrill Lukas, Wessely Isabelle, Diesner Susanne C, Schüller Simone, Dürr Celia, Heinle Armando, Sachet Monika, Pollak Arnold, Förster-Waldl Elisabeth, Spittler Andreas
Dept. of Paediatrics and Adolescent Medicine, Division of Neonatology, Paediatric Intensive Care & Neuropaediatrics, Medical University of Vienna, Vienna, Austria.
Dept. of Surgery, Medical University of Vienna, Vienna, Austria.
PLoS One. 2016 Oct 3;11(10):e0162667. doi: 10.1371/journal.pone.0162667. eCollection 2016.
Toll-like receptors (TLR) are crucial sensors of microbial agents such as bacterial or viral compounds. These receptors constitute key players in the induction of inflammation, e.g. in septic or chronic inflammatory diseases. Colony-stimulating factors (CSFs) such as granulocyte-macrophage-CSF (GM-CSF) or granulocyte-CSF (G-CSF) have been extensively investigated in their capacity to promote myelopoiesis in febrile neutropenia or to overcome immunosuppression in patients suffering from sepsis-associated neutropenia or from monocytic immunoincompetence. We report here that GM-CSF, downregulates TLR1, TLR2 and TLR4 in a time- and dose-dependent fashion in human monocytes. Diminished pathogen recognition receptor expression was accompanied by reduced downstream p38 and extracellular-signal-regulated kinase (ERK) signaling upon lipoteichoic acid (LTA) and lipopolysaccharide (LPS) binding-and accordingly led to impaired proinflammatory cytokine production. Knockdown experiments of the transcription factors PU.1 and VentX showed that GM-CSF driven effects on TLR regulation is entirely PU.1 but not VentX dependent. We further analysed monocyte TLR and CD14 expression upon exposure to the IMID® immunomodulatory drug Pomalidomide (CC-4047), a Thalidomide analogue known to downregulate PU.1. Indeed, Pomalidomide in part reversed the GM-CSF-mediated effects. Our data indicate a critical role of PU.1 in the regulation of TLR1, 2, 4 and of CD14, thus targeting PU.1 ultimately results in TLR modulation. The PU.1 mediated immunomodulatory properties of GM-CSF should be taken into consideration upon usage of GM-CSF in inflammatory or infection-related conditions.
Toll样受体（TLR）是微生物病原体（如细菌或病毒化合物）的关键传感器。这些受体是炎症诱导中的关键参与者，例如在败血症或慢性炎症性疾病中。集落刺激因子（CSF），如粒细胞巨噬细胞集落刺激因子（GM-CSF）或粒细胞集落刺激因子（G-CSF），在促进发热性中性粒细胞减少症中的骨髓生成或克服败血症相关中性粒细胞减少症或单核细胞免疫功能不全患者的免疫抑制方面的能力已得到广泛研究。我们在此报告，GM-CSF在人单核细胞中以时间和剂量依赖性方式下调TLR1、TLR2和TLR4。病原体识别受体表达的减少伴随着脂磷壁酸（LTA）和脂多糖（LPS）结合后下游p38和细胞外信号调节激酶（ERK）信号的减少，因此导致促炎细胞因子产生受损。转录因子PU.1和VentX的敲低实验表明，GM-CSF对TLR调节的驱动作用完全依赖于PU.1，而不依赖于VentX。我们进一步分析了暴露于IMID®免疫调节药物泊马度胺（CC-4047）后单核细胞TLR和CD14的表达，泊马度胺是一种已知可下调PU.1的沙利度胺类似物。事实上，泊马度胺部分逆转了GM-CSF介导的作用。我们的数据表明PU.1在TLR1、2、4和CD14的调节中起关键作用，因此靶向PU.1最终会导致TLR调节。在炎症或感染相关疾病中使用GM-CSF时，应考虑GM-CSF的PU.介导的免疫调节特性。
