Jennewein Jonas, Matuszak Jasmin, Walter Steffi, Felmy Boas, Gendera Kathrin, Schatz Valentin, Nowottny Monika, Liebsch Gregor, Hensel Michael, Hardt Wolf-Dietrich, Gerlach Roman G, Jantsch Jonathan
Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Institut für Klinische Mikrobiologie und Hygiene, Universitätsklinikum Erlangen und Friedrich-Alexander Universität (FAU) Erlangen-Nürnberg, Erlangen, Germany.
Institut für Klinische Mikrobiologie und Hygiene, Universitätsklinikum Regensburg und Universität Regensburg, Regensburg, Germany.
Cell Microbiol. 2015 Dec;17(12):1833-47. doi: 10.1111/cmi.12476. Epub 2015 Jul 16.
In Salmonella infection, the Salmonella pathogenicity island-2 (SPI-2)-encoded type three secretion system (T3SS2) is of key importance for systemic disease and survival in host cells. For instance, in the streptomycin-pretreated mouse model SPI-2-dependent Salmonella replication in lamina propria CD11c(-)CXCR1(-) monocytic phagocytes/macrophages (MΦ) is required for the development of colitis. In addition, containment of intracellular Salmonella in the gut critically depends on the antimicrobial effects of the phagocyte NADPH oxidase (PHOX), and possibly type 2 nitric oxide synthase (NOS2). For both antimicrobial enzyme complexes, oxygen is an essential substrate. However, the amount of available oxygen upon enteroinvasive Salmonella infection in the gut tissue and its impact on Salmonella-MΦ interactions was unknown. Therefore, we measured the gut tissue oxygen levels in a model of Salmonella enterocolitis using luminescence two-dimensional in vivo oxygen imaging. We found that gut tissue oxygen levels dropped from ∼78 Torr (∼11% O2) to values of ∼16 Torr (∼2% O2) during infection. Because in vivo virulence of Salmonella depends on the Salmonella survival in MΦ, Salmonella-MΦ interaction was analysed under such low oxygen values. These experiments revealed an increased intracellular replication and survival of wild-type and t3ss2 non-expressing Salmonella. These findings were paralleled by blunted nitric oxide and reactive oxygen species (ROS) production and reduced Salmonella ROS perception. In addition, hypoxia enhanced SPI-2 transcription and translocation of SPI-2-encoded virulence protein. Neither pharmacological blockade of PHOX and NOS2 nor impairment of T3SS2 virulence function alone mimicked the effect of hypoxia on Salmonella replication under normoxic conditions. However, if t3ss2 non-expressing Salmonella were used, hypoxia did not further enhance Salmonella recovery in a PHOX and NOS2-deficient situation. Hence, these data suggest that hypoxia-induced impairment of antimicrobial activity and Salmonella virulence cooperate to allow for enhanced Salmonella replication in MΦ.
在沙门氏菌感染中，沙门氏菌致病岛2（SPI-2）编码的三型分泌系统（T3SS2）对于全身性疾病以及在宿主细胞中的存活至关重要。例如，在链霉素预处理的小鼠模型中，固有层CD11c(-)CXCR1(-)单核吞噬细胞/巨噬细胞（MΦ）中依赖SPI-2的沙门氏菌复制是结肠炎发生所必需的。此外，肠道中细胞内沙门氏菌的控制严重依赖于吞噬细胞NADPH氧化酶（PHOX）以及可能的2型一氧化氮合酶（NOS2）的抗菌作用。对于这两种抗菌酶复合物而言，氧气是必需的底物。然而，肠道组织中侵袭性沙门氏菌感染时的可用氧量及其对沙门氏菌-MΦ相互作用的影响尚不清楚。因此，我们使用发光二维体内氧成像技术在沙门氏菌小肠结肠炎模型中测量了肠道组织的氧水平。我们发现，在感染期间肠道组织氧水平从约78托（约11% O2）降至约16托（约2% O2）。由于沙门氏菌的体内毒力取决于其在MΦ中的存活，因此在如此低的氧值下分析了沙门氏菌-MΦ相互作用。这些实验揭示了野生型和不表达t3ss2的沙门氏菌在细胞内的复制和存活增加。这些发现伴随着一氧化氮和活性氧（ROS）产生的减弱以及沙门氏菌对ROS的感知降低。此外，缺氧增强了SPI-2转录以及SPI-2编码的毒力蛋白的转运。单独对PHOX和NOS2进行药理阻断或T3SS2毒力功能受损均无法模拟缺氧对常氧条件下沙门氏菌复制的影响。然而，如果使用不表达t3ss2的沙门氏菌，在PHOX和NOS2缺陷的情况下，缺氧并不会进一步提高沙门氏菌的恢复率。因此，这些数据表明，缺氧诱导的抗菌活性受损与沙门氏菌毒力协同作用，使得沙门氏菌在MΦ中的复制得以增强。
