@article{FanEbnerReichertetal.2019, author = {Fan, Sook-Ha and Ebner, Patrick and Reichert, Sebstian and Hertlein, Tobias and Zabel, Susanne and Lankapalli, Aditya Kumar and Nieselt, Kay and Ohlsen, Knut and G{\"o}tz, Friedrich}, title = {MpsAB is important for Staphylococcus aureus virulence and growth at atmospheric CO2 levels}, series = {Nature Communications}, volume = {10}, journal = {Nature Communications}, doi = {10.1038/s41467-019-11547-5}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-227624}, year = {2019}, abstract = {The mechanisms behind carbon dioxide (CO2) dependency in non-autotrophic bacterial isolates are unclear. Here we show that the Staphylococcus aureus mpsAB operon, known to play a role in membrane potential generation, is crucial for growth at atmospheric CO2 levels. The genes mpsAB can complement an Escherichia coli carbonic anhydrase (CA) mutant, and CA from E. coli can complement the S. aureus delta-mpsABC mutant. In comparison with the wild type, S. aureus mps mutants produce less hemolytic toxin and are less virulent in animal models of infection. Homologs of mpsA and mpsB are widespread among bacteria and are often found adjacent to each other on the genome. We propose that MpsAB represents a dissolved inorganic carbon transporter, or bicarbonate concentrating system, possibly acting as a sodium bicarbonate cotransporter.}, language = {en} } @article{SeethalerHertleinWeckleinetal.2019, author = {Seethaler, Marius and Hertlein, Tobias and Wecklein, Bj{\"o}rn and Ymeraj, Alba and Ohlsen, Knut and Lalk, Michael and Hilgeroth, Andreas}, title = {Novel small-molecule antibacterials against Gram-positive pathogens of Staphylococcus and Enterococcus species}, series = {Antibiotics}, volume = {8}, journal = {Antibiotics}, number = {4}, issn = {2079-6382}, doi = {10.3390/antibiotics8040210}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-193130}, year = {2019}, abstract = {Defeat of the antibiotic resistance of pathogenic bacteria is one great challenge today and for the future. In the last century many classes of effective antibacterials have been developed, so that upcoming resistances could be met with novel drugs of various compound classes. Meanwhile, there is a certain lack of research of the pharmaceutical companies, and thus there are missing developments of novel antibiotics. Gram-positive bacteria are the most important cause of clinical infections. The number of novel antibacterials in clinical trials is strongly restricted. There is an urgent need to find novel antibacterials. We used synthetic chemistry to build completely novel hybrid molecules of substituted indoles and benzothiophene. In a simple one-pot reaction, two novel types of thienocarbazoles were yielded. Both indole substituted compound classes have been evaluated as completely novel antibacterials against the Staphylococcus and Enterococcus species. The evaluated partly promising activities depend on the indole substituent type. First lead compounds have been evaluated within in vivo studies. They confirmed the in vitro results for the new classes of small-molecule antibacterials.}, language = {en} } @article{GomesWestermannSauerweinetal.2019, author = {Gomes, Sara F. Martins and Westermann, Alexander J. and Sauerwein, Till and Hertlein, Tobias and F{\"o}rstner, Konrad U. and Ohlsen, Knut and Metzger, Marco and Shusta, Eric V. and Kim, Brandon J. and Appelt-Menzel, Antje and Schubert-Unkmeir, Alexandra}, title = {Induced pluripotent stem cell-derived brain endothelial cells as a cellular model to study Neisseria meningitidis infection}, series = {Frontiers in Microbiology}, volume = {10}, journal = {Frontiers in Microbiology}, number = {1181}, doi = {10.3389/fmicb.2019.01181}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-201562}, year = {2019}, abstract = {Meningococcal meningitis is a severe central nervous system infection that occurs when Neisseria meningitidis (Nm) penetrates brain endothelial cells (BECs) of the meningeal blood-cerebrospinal fluid barrier. As a human-specific pathogen, in vivo models are greatly limited and pose a significant challenge. In vitro cell models have been developed, however, most lack critical BEC phenotypes limiting their usefulness. Human BECs generated from induced pluripotent stem cells (iPSCs) retain BEC properties and offer the prospect of modeling the human-specific Nm interaction with BECs. Here, we exploit iPSC-BECs as a novel cellular model to study Nm host-pathogen interactions, and provide an overview of host responses to Nm infection. Using iPSC-BECs, we first confirmed that multiple Nm strains and mutants follow similar phenotypes to previously described models. The recruitment of the recently published pilus adhesin receptor CD147 underneath meningococcal microcolonies could be verified in iPSC-BECs. Nm was also observed to significantly increase the expression of pro-inflammatory and neutrophil-specific chemokines IL6, CXCL1, CXCL2, CXCL8, and CCL20, and the secretion of IFN-γ and RANTES. For the first time, we directly observe that Nm disrupts the three tight junction proteins ZO-1, Occludin, and Claudin-5, which become frayed and/or discontinuous in BECs upon Nm challenge. In accordance with tight junction loss, a sharp loss in trans-endothelial electrical resistance, and an increase in sodium fluorescein permeability and in bacterial transmigration, was observed. Finally, we established RNA-Seq of sorted, infected iPSC-BECs, providing expression data of Nm-responsive host genes. Altogether, this model provides novel insights into Nm pathogenesis, including an impact of Nm on barrier properties and tight junction complexes, and suggests that the paracellular route may contribute to Nm traversal of BECs.}, language = {en} } @article{NguyenSaisingTribellietal.2019, author = {Nguyen, Minh-Thu and Saising, Jongkon and Tribelli, Paula Maria and Nega, Mulugeta and Diene, Seydina M. and Fran{\c{c}}ois, Patrice and Schrenzel, Jacques and Spr{\"o}er, Cathrin and Bunk, Boyke and Ebner, Patrick and Hertlein, Tobias and Kumari, Nimerta and H{\"a}rtner, Thomas and Wistuba, Dorothee and Voravuthikunchai, Supayang P. and M{\"a}der, Ulrike and Ohlsen, Knut and G{\"o}tz, Friedrich}, title = {Inactivation of farR Causes High Rhodomyrtone Resistance and Increased Pathogenicity in Staphylococcus aureus}, series = {Frontiers in Microbiology}, volume = {10}, journal = {Frontiers in Microbiology}, doi = {10.3389/fmicb.2019.01157}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-224117}, year = {2019}, abstract = {Rhodomyrtone (Rom) is an acylphloroglucinol antibiotic originally isolated from leaves of Rhodomyrtus tomentosa. Rom targets the bacterial membrane and is active against a wide range of Gram-positive bacteria but the exact mode of action remains obscure. Here we isolated and characterized a spontaneous Rom-resistant mutant from the model strain Staphylococcus aureus HG001 (RomR) to learn more about the resistance mechanism. We showed that Rom-resistance is based on a single point mutation in the coding region of farR [regulator of fatty acid (FA) resistance] that causes an amino acid change from Cys to Arg at position 116 in FarR, that affects FarR activity. Comparative transcriptome analysis revealed that mutated farR affects transcription of many genes in distinct pathways. FarR represses for example the expression of its own gene (farR), its flanking gene farE (effector of FA resistance), and other global regulators such as agr and sarA. All these genes were consequently upregulated in the RomR clone. Particularly the upregulation of agr and sarA leads to increased expression of virulence genes rendering the RomR clone more cytotoxic and more pathogenic in a mouse infection model. The Rom-resistance is largely due to the de-repression of farE. FarE is described as an efflux pump for linoleic and arachidonic acids. We observed an increased release of lipids in the RomR clone compared to its parental strain HG001. If farE is deleted in the RomR clone, or, if native farR is expressed in the RomR strain, the corresponding strains become hypersensitive to Rom. Overall, we show here that the high Rom-resistance is mediated by overexpression of farE in the RomR clone, that FarR is an important regulator, and that the point mutation in farR (RomR clone) makes the clone hyper-virulent.}, language = {en} } @article{TruebeHertleinMrochenetal.2019, author = {Tr{\"u}be, Patricia and Hertlein, Tobias and Mrochen, Daniel M. and Schulz, Daniel and Jorde, Ilka and Krause, Bettina and Zeun, Julia and Fischer, Stefan and Wolf, Silver A. and Walther, Birgit and Semmler, Torsten and Br{\"o}ker, Barbara M. and Ulrich, Rainer G. and Ohlsen, Knut and Holtfreter, Silva}, title = {Bringing together what belongs together: Optimizing murine infection models by using mouse-adapted Staphylococcus aureus strains}, series = {International Journal of Medical Microbiology}, volume = {309}, journal = {International Journal of Medical Microbiology}, doi = {10.1016/j.ijmm.2018.10.007}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-229081}, pages = {26-38}, year = {2019}, abstract = {Staphylococcus (S.) aureus is a leading cause of bacterial infection world-wide, and currently no vaccine is available for humans. Vaccine development relies heavily on clinically relevant infection models. However, the suitability of mice for S. aureus infection models has often been questioned, because experimental infection of mice with human-adapted S. aureus requires very high infection doses. Moreover, mice were not considered to be natural hosts of S. aureus. The latter has been disproven by our recent findings, showing that both laboratory mice, as well as wild small mammals including mice, voles, and shrews, are naturally colonized with S. aureus. Here, we investigated whether mouse-and vole-derived S. aureus strains show an enhanced virulence in mice as compared to the human-adapted strain Newman. Using a step-wise approach based on the bacterial genotype and in vitro assays for host adaptation, we selected the most promising candidates for murine infection models out of a total of 254 S. aureus isolates from laboratory mice as well as wild rodents and shrews. Four strains representing the clonal complexes (CC) 8, 49, and 88 (n = 2) were selected and compared to the human-adapted S. aureus strain Newman (CC8) in murine pneumonia and bacteremia models. Notably, a bank vole-derived CC49 strain, named DIP, was highly virulent in BALB/c mice in pneumonia and bacteremia models, whereas the other murine and vole strains showed virulence similar to or lower than that of Newman. At one tenth of the standard infection dose DIP induced disease severity, bacterial load and host cytokine and chemokine responses in the murine bacteremia model similar to that of Newman. In the pneumonia model, DIP was also more virulent than Newman but the effect was less pronounced. Whole genome sequencing data analysis identified a pore-forming toxin gene, lukF-PV(P83)/lukM, in DIP but not in the other tested S. aureus isolates. To conclude, the mouse-adapted S. aureus strain DIP allows a significant reduction of the inoculation dose in mice and is hence a promising tool to develop clinically more relevant infection models.}, language = {en} }