Sumpf Kristina, Nast Roswitha, Downie Bryan, Salinas Gabriela, Lüder Carsten G K
Institute for Medical Microbiology, University Medical Center, Georg-August-University, Kreuzbergring 57, 37075 Göttingen, Germany.
Transcriptome and Genome Analysis Laboratory, University Medical Center, Georg-August-University, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany.
Exp Parasitol. 2017 Sep;180:45-54. doi: 10.1016/j.exppara.2017.02.011. Epub 2017 Feb 9.
Toxoplasma gondii is a ubiquitous apicomplexan parasite of mammals and birds and an important pathogen of humans. IFN-γ is the major mediator of host resistance against T. gondii but intriguingly, parasite-infected host cells including macrophages are severely impaired to respond to IFN-γ due to defective transcriptional activation of target genes. Here, we tested the possibility that the impaired responsiveness of T. gondii-infected macrophages to IFN-γ can be restored by inhibiting histone deacetylases (HDACs) using the class I-specific inhibitor MS-275. Treatment of RAW264.7 cells with MS-275 indeed increased MHC class II surface expression in infected and non-infected cells and largely abolished the inhibition of IFN-γ-regulated MHC class II expression exerted by T. gondii. Genome-wide transcriptome profiling revealed that MS-275 increased mean mRNA levels of IFN-γ-regulated genes particularly in non-infected macrophages. Transcript levels of 33% of IFN-γ secondary response genes but only those of a few primary response genes were also increased by MS-275 in T. gondii-infected cells. Importantly, the unresponsiveness of parasite-infected cells to IFN-γ was however not abolished by MS-275. Furthermore, MS-275 also up-regulated several anti-inflammatory cytokines or signaling molecules in T. gondii-infected macrophages. It additionally regulated expression of more than 2500 genes in non-infected macrophages expression of which was surprisingly counteracted by prior infection with T. gondii. FACS analysis and immunofluorescence microscopy revealed that MS-275 did not considerably diminish the number of parasite-positive cells or the intracellular replication in macrophages stimulated or not with IFN-γ. Thus, a supportive therapy using MS-275 appears inappropriate for treatment of toxoplasmosis.
刚地弓形虫是一种广泛存在于哺乳动物和鸟类中的顶复门寄生虫，也是人类的重要病原体。干扰素-γ是宿主抵抗刚地弓形虫的主要介质，但有趣的是，包括巨噬细胞在内的被寄生虫感染的宿主细胞由于靶基因转录激活缺陷，对干扰素-γ的反应严重受损。在这里，我们测试了使用I类特异性抑制剂MS-275抑制组蛋白脱乙酰酶（HDACs）是否可以恢复刚地弓形虫感染的巨噬细胞对干扰素-γ的受损反应性。用MS-275处理RAW264.7细胞确实增加了感染和未感染细胞中MHC II类分子的表面表达，并在很大程度上消除了刚地弓形虫对干扰素-γ调节的MHC II类分子表达的抑制作用。全基因组转录组分析表明，MS-275增加了干扰素-γ调节基因的平均mRNA水平，特别是在未感染的巨噬细胞中。在刚地弓形虫感染的细胞中，MS-275也增加了33%的干扰素-γ二级反应基因的转录水平，但仅增加了少数初级反应基因的转录水平。重要的是，MS-275并未消除寄生虫感染细胞对干扰素-γ的无反应性。此外，MS-275还上调了刚地弓形虫感染的巨噬细胞中的几种抗炎细胞因子或信号分子。它还调节了未感染巨噬细胞中2500多个基因的表达，而刚地弓形虫先前感染出人意料地抵消了这些基因的表达。流式细胞术分析和免疫荧光显微镜检查显示，MS-275并没有显著减少干扰素-γ刺激或未刺激的巨噬细胞中寄生虫阳性细胞的数量或细胞内复制。因此，使用MS-275的支持性疗法似乎不适用于治疗弓形虫病。
