Zielińska Karolina A, de Cauwer Lode, Knoops Sofie, Van der Molen Kristof, Sneyers Alexander, Thommis Jonathan, De Souza J Brian, Opdenakker Ghislain, De Bosscher Karolien, Van den Steen Philippe E
Laboratory of Immunobiology, Department of Microbiology and Immunology, Rega Institute for Medical Research, KU Leuven, Leuven, Belgium.
Receptor Research Laboratories, Nuclear Receptor Lab, VIB-UGent Center for Medical Biotechnology, Ghent, Belgium.
Front Immunol. 2017 Sep 28;8:1199. doi: 10.3389/fimmu.2017.01199. eCollection 2017.
Malaria-associated acute respiratory distress syndrome (MA-ARDS) is an often lethal complication of malaria. Currently, no adequate therapy for this syndrome exists. Although glucocorticoids (GCs) have been used to improve clinical outcome of ARDS, their therapeutic benefits remain unclear. We previously developed a mouse model of MA-ARDS, in which dexamethasone treatment revealed GC resistance. In the present study, we investigated GC sensitivity of mouse microvascular lung endothelial cells stimulated with interferon-γ (IFN-γ) and NK65 (NK65). Upon challenge with IFN-γ alone, dexamethasone inhibited the expression of CCL5 (RANTES) by 90% and both CCL2 (MCP-1) and CXCL10 (IP-10) by 50%. Accordingly, whole transcriptome analysis revealed that dexamethasone differentially affected several gene clusters and in particular inhibited a large cluster of IFN-γ-induced genes, including chemokines. In contrast, combined stimulation with IFN-γ and NK65 extract impaired inhibitory actions of GCs on chemokine release, without affecting the capacity of the GC receptor to accumulate in the nucleus. Subsequently, we investigated the effects of GCs on two signaling pathways activated by IFN-γ. Dexamethasone left phosphorylation and protein levels of signal transducer and activator of transcription 1 (STAT1) unhampered. In contrast, dexamethasone inhibited the IFN-γ-induced activation of two mitogen-activated protein kinases (MAPK), JNK, and p38. However, NK65 extract abolished the inhibitory effects of GCs on MAPK signaling, inducing GC resistance. These data provide novel insights into the mechanisms of GC actions in endothelial cells and show how malaria may impair the beneficial effects of GCs.
疟疾相关急性呼吸窘迫综合征（MA-ARDS）是疟疾常见的致命并发症。目前，尚无针对该综合征的有效治疗方法。尽管糖皮质激素（GCs）已被用于改善ARDS的临床结局，但其治疗效果仍不明确。我们之前建立了MA-ARDS小鼠模型，其中地塞米松治疗显示出GC抵抗。在本研究中，我们研究了用干扰素-γ（IFN-γ）和NK65刺激的小鼠肺微血管内皮细胞的GC敏感性。单独用IFN-γ刺激时，地塞米松可使CCL5（RANTES）的表达抑制90%，使CCL2（MCP-1）和CXCL10（IP-10）的表达抑制50%。相应地，全转录组分析显示地塞米松对几个基因簇有不同影响，尤其抑制了一大簇IFN-γ诱导的基因，包括趋化因子。相比之下，IFN-γ和NK65提取物联合刺激削弱了GCs对趋化因子释放的抑制作用，而不影响GC受体在细胞核中积累的能力。随后，我们研究了GCs对IFN-γ激活的两条信号通路的影响。地塞米松不影响信号转导和转录激活因子1（STAT1）的磷酸化和蛋白水平。相比之下，地塞米松抑制了IFN-γ诱导的两种丝裂原活化蛋白激酶（MAPK）JNK和p38的激活。然而，NK65提取物消除了GCs对MAPK信号的抑制作用，诱导了GC抵抗。这些数据为GCs在内皮细胞中的作用机制提供了新的见解，并展示了疟疾如何损害GCs的有益作用。
