VAAM-Jahrestagung 2012 18.–21. März in Tübingen

119cultures for cheese fermentation or as a probiotic is currently limited bythe potential health risks associated with its use. E. faecalis also occurs asan opportunistic pathogen that can cause severe infections such asendocarditis, septicemia and urinary tract infections. Therefore, thoroughcharacterization of isolates is necessary in order to assess potential risksfor susceptible individuals. In this study, we investigated the effect of thegrowth environment on the secretome of two phenotypically similar E.faecalis strains from food and clinical origin. To investigate the scenario ofpotentially pathogenic E. faecalis ingestion with food, they were grown inthe standard laboratory medium M17 and in Simulated Colon EnvironmentMedium (SCEM) to mimic the conditions in the gut. As many of the E.faecalis virulence factors identified so far are secreted, extracellularproteins were isolated, separated and identified by 1D-SDS-PAGE- LC-MS/MS and comparatively analyzed. A total of 346 proteins wereidentified. In the further analysis, special attention was given to knownvirulence factors as well as the 36 proteins being solely expressed inSCEM.MPP042A scavenger receptor on nasal epithelial surfaces - Animportant player in Staphylococcus aureus nasal colonizationM. Rautenberg*, S. Baur, S. Wanner, L. Kull, C. WeidenmaierInterfaculty Institute of Microbiology and Infection Medicine, MedicalMicrobiology, Tübingen, GermanyMany severe bacterial infections originate from the microflora of the host.One of the most frequent causes of such infections is Staphylococcusaureus, which colonizes the noses of about one third of the population.However, the molecular basis of this colonization is only understoodincompletely. It has been demonstrated that cell wall glycoploymers(CWGs) are important for adhesion of Gram-positive bacteria to host cells.The cell wall teichoic acid (WTA) of S. aureus has been shown to mediateadhesion to nasal epithelial cells and to be crucial for S. aureuscolonization in a cotton rat model. However, the appropriate receptor onnasal epithelial cells remains elusive.Recent research in the field of glycobiology suggests members of thescavenger receptor family as an interaction partner for WTA. Previouslythis hypothesis could be confirmed by using inhibitors against scavengerreceptors, which inhibited adhesion of S. aureus to nasal epithelial cells,markedly. Recently, the expression of a scavenger receptor on epithelialcells has been described. In accordance, function blocking antibodies tothis receptor inhibited S. aureus adhesion to human epithelial cells understatic and mild sheer stress conditions. To further elucidate these findingsin a nasal colonization model in cotton rats we established primary cellcultures of nasal epithelial cells from cotton rats. Thereby we could detectthe expression of the mentioned scavenger receptor. Moreover, we wereable to demonstrate a specific binding of WTA to these primary cotton ratepithelial cells using WTA labeled latex beads. Recently, we confirmedthe crucial role of this scavenger receptor in vivo by blocking S. aureusadhesion to nasal epithelial cells by preincubating nasal epithelia of cottonrats with an antibody against this scavenger receptor. Thus, we herepresent the first receptor for WTA in nasal colonization.MPP043Infection of human endothelial progenitor cells withBartonella henselae induces vessel-like growth in vitro.F. O'Rourke* 1 , T. Mändle 2 , C. Urbich 3 , S. Dimmeler 3 , K. Lauber 41 Klinikum der Goethe Universität Frankfurt, Medizinische Mikrobiologie,Frankfurt am Main, Germany2 Universitätsklinikum, Medizinische Mikrobiologie, Tübingen, Germany3 Klinikum der Goethe Universität Frankfurt, Institut für KardiovaskuläreRegeneration, Frankfurt am Main, Germany4 Universität München, Molekulare Onkologie, München, GermanyEndothelial progenitor cells (EPCs) are a heterogeneous mixture of adultstem cells that play an essential role in revascularization after vasculardamage. Their discovery over a decade ago led to various pre-clinical andclinical trials investigating the use of these cells in regenerative medicinefor ischemic injury. In our work we investigated an unconventionalmethod of improving the angiogenic potential of EPCs through bacterialinfection.Bartonella spp.are facultative intracellular pathogens and theonly known bacteria to induce angiogenesis in humans. Here we describefor the first time the course of a bacterial infection of EPCs with thevasculotropic bacteriumB. henselae. Our data demonstrate that EPCs arehighly susceptible toB. henselaeand that infection does not disturb theirinitial differentiation under angiogenic conditions. Upon infection EPCsshow a strong activation of hypoxia inducible factor-1 (HIF-1), the keytranscription factor in angiogenesis. This is followed by the signature HIF-1-dependent pro-angiogenic cell response including production ofcytokines such as vascular endothelial growth factor (VEGF) andadrenomedullin (ADM). Furthermore,B. henselaeprevents apoptosis ofEPCs and induces cell migration along a stromal cell-derived factor(SDF)-1 gradient, both essential functional components of the angiogenicresponse. Finally, when culture plates are coated with a basementmembrane which simulates the extra-cellular matrix(Matrigel TM ), infectedEPCs assemble into complex vessel-like structuresin vitro. We haverecently shown that heat-killedB. henselaecan also induce the building ofvessel-like structuresin vitrosuggesting the involvement of some yetunknownouter membrane element. Cumulatively, our data demonstratethat infection withB. henselaecan improve the angiogenic capacity ofEPCs and induce vessel-like growthin vitro. At present we are working tophenotypically and genetically characterize the transformation of EPCsfrom circulation progenitor cells to vessel-like structures and identifygenes and pathways involved in this bacterial induced process.MPP044Sweet toothed bats without cavities - almost no appearance ofdental caries in the frugivorous bat Artibeus jamaicensisS. Brändel* 1,2 , F. Bengelsdorf 1 , I. Wagner 2 , A. Mack 3 , R. Diebolder 4 ,B. Stegmann 1 , M. Tschapka 2 , B. Haller 3 , R. Hibst 4 , E.K.V. Kalko 2 , P. Dürre 11 University Ulm, Institute of Microbiology and Biotechnology, Ulm, Germany2 University Ulm, Institute of Experimental Ecology, Ulm, Germany3 University Ulm, Klinik für Zahnerhaltungskunde und Parodontologie, Ulm,Germany4 University Ulm, Institut für Lasertechnologien in der Medizin undMesstechnik, Ulm, GermanyDental caries is a widespread disease which affects humans and othermammal species, but obviously not the frugivorous bat Artibeusjamaicensis. There are many studies concerning dental decay in humansand animal models, but so far little is known about the complexmicrobiological and environmental interactions which lead to dental caries.Although these bats consume nearly exclusively figs and consequentlyhigh amounts of sugars, they are less affected by cavities than humans. Toconfirm this observation and to offer an explanation, a study wasconducted including ecological, microbiological, dental, and microscopicaltechniques.Animals were captured in the wild during field work on Barro ColoradoIsland (Panama). The teeth of the bats were analyzed with dental criteria todetermine the incidence of dental caries. Only three of 230 captured A.jamaicensis were affected. In general, only 0.9 % of the surveyed surfaceof the teeth showed appearance of dental plaque as documented bystaining, notoriously less than in humans.To identify the oral microbial community of these bats, saliva sampleswere taken, genomic DNA was extracted, and the amplified bacterial 16SrDNA fragments were analyzed by 454-Pyrosequencing. It was found thatthe oral microbiota of healthy bats is similar to human saliva regarding thecomposition of microorganisms with one exception: Healthy bats salivalacks obligate anaerobic bacteria. Nevertheless, plaque-forming as well asfacultative anaerobic bacteria could be found. Obligate anaerobes couldonly be detected in a saliva sample of a caries affected A. lituratus. Allanaerobic bacteria found are potentially cariogenic under anaerobicconditions, normally found in elder dental plaque. The confirmation ofpotentially cariogenic bacteria in the saliva of bats leads to the assumptionthat there are no substances protecting against caries in saliva inhibitingtheir growth.Extracted teeth of dead specimens were examined in reference to humanteeth in their hardness, surface structure, and enamel. First results show asmoother surface structure, the lack of pores, and a thinner enamel layer.These results indicate that it is the particular surface shape of the enamel ofthe teeth of bats which is related to less caries incidence in A. jamaicencis,despite the attendance of cariogenic bacteria.MPP045Staphylococcal major autolysin (Atl) is involved in excretion ofcytoplasmic proteinsL. Dube* 1 , A.-K. Ziebandt 1 , M. Schlag 1 , S. Haase 1 , M. Franz-Wachtel 2 ,J. Madlung 2 , F. Götz 11 University of Tübingen, Microbial Genetics, Tübingen, Germany2 University of Tübingen, Proteome Center Tübingen, Tübingen, GermanyIn both gram-positive and -negative bacteria as well as in yeasts typicalcytoplasmic proteins/enzymes are found outside the cell in the culturesupernatant or attached to the cell surface where they may contribute tovirulence. Nothing is known how these “extracellular” cytoplasmicproteins are translocated through the cytoplasmic membrane and this typeof secretion was referred to as "nonclassical protein secretion". We coulddemonstrate that in Staphylococcus aureus the major autolysin Atl plays acrucial role in release of cytoplasmic proteins. We could show that inStaphylococcus aureus 20 typical cytoplasmic proteins were excreted andusing glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as acytoplasmic indicator enzyme, we showed that all clinical isolates testedexcreted this protein. To answer the question of how discriminatory theexcretion of cytoplasmic proteins is, we performed a two-dimensionalPAGE of cytoplasmic proteins isolated from WT. We disproved thecommon opinion that only highly expressed and abundant cytoplasmicBIOspektrum | Tagungsband 2012