Data_Sheet_2_A Pathogen and a Non-pathogen Spotted Fever Group Rickettsia Trigger Differential Proteome Signatures in Macrophages.PDF

We have previously reported that Rickettsia conorii and Rickettsia montanensis have distinct intracellular fates within THP-1 macrophages, suggesting that the ability to proliferate within macrophages may be a distinguishable factor between pathogenic and non-pathogenic Spotted fever group (SFG) members. To start unraveling the molecular mechanisms underlying the capacity (or not) of SFG Rickettsia to establish their replicative niche in macrophages, we have herein used quantitative proteomics by SWATH-MS to profile the alterations resulted by the challenge of THP-1 macrophages with R. conorii and R. montanensis. We show that the pathogenic, R. conorii, and the non-pathogenic, R. montanensis, member of SFG Rickettsia trigger differential proteomic signatures in macrophage-like cells upon infection. R. conorii specifically induced the accumulation of several enzymes of the tricarboxylic acid cycle, oxidative phosphorylation, fatty acid β-oxidation, and glutaminolysis, as well as of several inner and outer membrane mitochondrial transporters. These results suggest a profound metabolic rewriting of macrophages by R. conorii toward a metabolic signature of an M2-like, anti-inflammatory activation program. Moreover, several subunits forming the proteasome and immunoproteasome are found in lower abundance upon infection with both rickettsial species, which may help bacteria to escape immune surveillance. R. conorii-infection specifically induced the accumulation of several host proteins implicated in protein processing and quality control in ER, suggesting that this pathogenic Rickettsia may be able to increase the ER protein folding capacity. This work reveals novel aspects of macrophage-Rickettsia interactions, expanding our knowledge of how pathogenic rickettsiae explore host cells to their advantage.

我们此前已有报道，康氏立克次体（Rickettsia conorii）与蒙大拿立克次体（Rickettsia montanensis）在THP-1巨噬细胞内具有截然不同的细胞内命运，这提示巨噬细胞内的增殖能力或许是区分致病性与非致病性斑点热群（Spotted fever group, SFG）立克次体的关键特征。为阐明斑点热群立克次体能否在巨噬细胞中建立复制微环境的分子机制，本研究采用SWATH-MS定量蛋白质组学技术，分析了THP-1巨噬细胞分别被康氏立克次体、蒙大拿立克次体感染后所产生的蛋白表达谱变化。研究结果显示，致病性的康氏立克次体与非致病性的蒙大拿立克次体，在感染巨噬细胞样细胞后，会诱导产生截然不同的蛋白质组特征。康氏立克次体可特异性诱导三羧酸循环、氧化磷酸化、脂肪酸β氧化以及谷氨酰胺分解相关的多种酶类，以及多种线粒体内膜与外膜转运蛋白的积累。上述结果表明，康氏立克次体可对巨噬细胞进行深刻的代谢重编程，使其转向M2样抗炎活化的代谢特征。此外，两种立克次体感染后，构成蛋白酶体与免疫蛋白酶体的多个亚基丰度均出现下调，这可能有助于细菌逃避免疫监视。康氏立克次体感染还可特异性诱导内质网（Endoplasmic Reticulum, ER）中参与蛋白质加工与质量控制的多种宿主蛋白积累，提示该致病性立克次体可增强内质网的蛋白质折叠能力。本研究揭示了巨噬细胞与立克次体相互作用的全新层面，拓展了我们对致病性立克次体如何利用宿主细胞以实现自身增殖的认知。