The membrane-damaging RTX family cytotoxin RtxA is a key virulence factor of the emerging pediatric pathogen Kingella kingae, but little is known about the mechanism of RtxA binding to host cells. While we have previously shown that RtxA binds cell surface glycoproteins, here we demonstrate that the toxin also binds different types of gangliosides. The recognition of gangliosides by RtxA depended on sialic acid side groups of ganglioside glycans. Moreover, binding of RtxA to epithelial cells was significantly decreased in the presence of free sialylated gangliosides, which inhibited cytotoxic activity of the toxin. These results suggest that RtxA utilizes sialylated gangliosides as ubiquitous cell membrane receptor molecules on host cells to exert its cytotoxic action and support K. kingae infection.
- MeSH
- bakteriální toxiny * metabolismus MeSH
- buněčná membrána metabolismus MeSH
- cytotoxiny metabolismus MeSH
- dítě MeSH
- faktory virulence metabolismus MeSH
- Kingella kingae * metabolismus MeSH
- lidé MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Gastrointestinal microbes respond to biochemical metabolites that coordinate their behaviors. Here, we demonstrate that bacterial indole functions as a multifactorial mitigator of Klebsiella grimontii and Klebsiella oxytoca pathogenicity. These closely related microbes produce the enterotoxins tilimycin and tilivalline; cytotoxin-producing strains are the causative agent of antibiotic-associated hemorrhagic colitis and have been associated with necrotizing enterocolitis of premature infants. We demonstrate that carbohydrates induce cytotoxin synthesis while concurrently repressing indole biosynthesis. Conversely, indole represses cytotoxin production. In both cases, the alterations stemmed from differential transcription of npsA and npsB, key genes involved in tilimycin biosynthesis. Indole also enhances conversion of tilimycin to tilivalline, an indole analog with reduced cytotoxicity. In this context, we established that tilivalline, but not tilimycin, is a strong agonist of pregnane X receptor (PXR), a master regulator of xenobiotic detoxification and intestinal inflammation. Tilivalline binding upregulated PXR-responsive detoxifying genes and inhibited tubulin-directed toxicity. Bacterial indole, therefore, acts in a multifunctional manner to mitigate cytotoxicity by Klebsiella spp.: suppression of toxin production, enhanced conversion of tilimycin to tilivalline, and activation of PXR. IMPORTANCE The human gut harbors a complex community of microbes, including several species and strains that could be commensals or pathogens depending on context. The specific environmental conditions under which a resident microbe changes its relationship with a host and adopts pathogenic behaviors, in many cases, remain poorly understood. Here, we describe a novel communication network involving the regulation of K. grimontii and K. oxytoca enterotoxicity. Bacterial indole was identified as a central modulator of these colitogenic microbes by suppressing bacterial toxin (tilimycin) synthesis and converting tilimycin to tilivalline while simultaneously activating a host receptor, PXR, as a means of mitigating tissue cytotoxicity. On the other hand, fermentable carbohydrates were found to inhibit indole biosynthesis and enhance toxin production. This integrated network involving microbial, host, and metabolic factors provides a contextual framework to better understand K. oxytoca complex pathogenicity.
- MeSH
- cytotoxiny metabolismus MeSH
- enterotoxiny metabolismus MeSH
- indoly metabolismus MeSH
- infekce bakteriemi rodu Klebsiella * mikrobiologie MeSH
- Klebsiella oxytoca genetika metabolismus MeSH
- lidé MeSH
- novorozenec MeSH
- pseudomembranózní enterokolitida * mikrobiologie MeSH
- Check Tag
- lidé MeSH
- novorozenec MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
Mast cells are potent immune sensors of the tissue microenvironment. Within seconds of activation, they release various preformed biologically active products and initiate the process of de novo synthesis of cytokines, chemokines, and other inflammatory mediators. This process is regulated at multiple levels. Besides the extensively studied IgE and IgG receptors, toll-like receptors, MRGPR, and other protein receptor signaling pathways, there is a critical activation pathway based on cholesterol-dependent, pore-forming cytolytic exotoxins produced by Gram-positive bacterial pathogens. This pathway is initiated by binding the exotoxins to the cholesterol-rich membrane, followed by their dimerization, multimerization, pre-pore formation, and pore formation. At low sublytic concentrations, the exotoxins induce mast cell activation, including degranulation, intracellular calcium concentration changes, and transcriptional activation, resulting in production of cytokines and other inflammatory mediators. Higher toxin concentrations lead to cell death. Similar activation events are observed when mast cells are exposed to sublytic concentrations of saponins or some other compounds interfering with the membrane integrity. We review the molecular mechanisms of mast cell activation by pore-forming bacterial exotoxins, and other compounds inducing cholesterol-dependent plasma membrane perturbations. We discuss the importance of these signaling pathways in innate and acquired immunity.
- MeSH
- buněčná membrána imunologie metabolismus mikrobiologie patologie MeSH
- buněčná smrt MeSH
- buněčné mikroprostředí MeSH
- cholesterol metabolismus MeSH
- cytokiny metabolismus MeSH
- cytotoxiny metabolismus MeSH
- degranulace buněk MeSH
- grampozitivní bakteriální infekce imunologie metabolismus mikrobiologie patologie MeSH
- grampozitivní bakterie imunologie metabolismus MeSH
- interakce hostitele a patogenu MeSH
- lidé MeSH
- mastocyty imunologie metabolismus mikrobiologie patologie MeSH
- mediátory zánětu metabolismus MeSH
- vápníková signalizace MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
2'-Deoxy-5-ethynyluridine (EdU) has been previously shown to be a cell poison whose toxicity depends on the particular cell line. The reason is not known. Our data indicates that different efficiency of EdU incorporation plays an important role. The EdU-mediated toxicity was elevated by the inhibition of 2'-deoxythymidine 5'-monophosphate synthesis. EdU incorporation resulted in abnormalities of the cell cycle including the slowdown of the S phase and a decrease in DNA synthesis. The slowdown but not the cessation of the first cell division after EdU administration was observed in all of the tested cell lines. In HeLa cells, a 10 μM EdU concentration led to the cell death in the 100% of cells probably due to the activation of an intra S phase checkpoint in the subsequent S phase. Our data also indicates that this EdU concentration induces interstrand DNA crosslinks in HeLa cells. We suppose that these crosslinks are the primary DNA damage resulting in cell death. According to our results, the EdU-mediated toxicity is further increased by the inhibition of thymidylate synthase by EdU itself at its higher concentrations.
- MeSH
- buněčné linie MeSH
- cytotoxiny metabolismus toxicita MeSH
- deoxyuridin analogy a deriváty metabolismus toxicita MeSH
- DNA biosyntéza genetika metabolismus MeSH
- inhibitory enzymů metabolismus toxicita MeSH
- intracelulární prostor účinky léků metabolismus MeSH
- lidé MeSH
- poškození DNA * MeSH
- proliferace buněk účinky léků MeSH
- replikace DNA účinky léků MeSH
- S fáze účinky léků MeSH
- tetrahydrofoláty biosyntéza MeSH
- thymidin metabolismus farmakologie MeSH
- thymidinmonofosfát metabolismus MeSH
- thymidylátsynthasa antagonisté a inhibitory MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Autory je předložen přehled aktuálně dostupných informací o syndromu toxického šoku (TSS – toxic shock syndrome) – život ohrožujícím onemocnění, v jehož patogenezi sehrávají klíčovou úlohu toxiny grampozitivních bakterií Staphylococcus aureus a Streptococcus pyogenes. Autoři se věnují epidemiologii a patogenezi onemocnění, upozorňují na důležitá anamnestická data i klinické známky, které by mohly na rozvoj TSS poukazovat. V neposlední řadě zmiňují současný pohled na adekvátní diagnostiku a terapii v případě rozvíjejícího se či již rozvinutého syndromu. Pro názornost je referát doplněn popisem vlastních klinických případů, které demonstrují dvě etiologicky odlišné formy této poměrně vzácné nozologické jednotky.
The authors present an up-to-date review of toxic shock syndrome (TSS) – a life-threatening condition where toxins of the Gram-positive bacteria Staphyloccocus aureus and Streptococcus pyogenes play a key role in the pathogenesis. The authors provide insight into the epidemiology and pathogenesis of the disease and point out the relevant patient history data and clinical signs and symptoms that may indicate progression of TSS. Last but not least, the state of the art diagnostic and therapeutic approaches to early and full blown TSS are summarized. Case reports are presented to illustrate two different etiological forms of this relatively rare nosological entity.
- MeSH
- antibakteriální látky terapeutické užití MeSH
- bolest etiologie MeSH
- C-reaktivní protein MeSH
- cytotoxiny fyziologie imunologie metabolismus MeSH
- debridement MeSH
- dospělí MeSH
- edém etiologie MeSH
- erytém etiologie terapie MeSH
- exantém etiologie MeSH
- exotoxiny metabolismus MeSH
- hemodynamika účinky léků MeSH
- hospitalizace MeSH
- imunitní systém - jevy fyziologie imunologie účinky léků MeSH
- intravenózní imunoglobuliny MeSH
- kalcitonin MeSH
- klindamycin terapeutické užití MeSH
- lidé MeSH
- modely nemocí na zvířatech MeSH
- multiorgánové selhání etiologie mikrobiologie MeSH
- myši MeSH
- otorinolaryngologické chirurgické výkony využití MeSH
- peniciliny MeSH
- pleurální výpotek etiologie terapie MeSH
- pooperační komplikace diagnóza etiologie imunologie patofyziologie terapie MeSH
- respirační insuficience etiologie terapie MeSH
- rizikové faktory MeSH
- septický šok * diagnóza epidemiologie etiologie patofyziologie terapie MeSH
- směrnice pro lékařskou praxi jako téma MeSH
- stafylokokové infekce etiologie imunologie patologie MeSH
- Staphylococcus aureus izolace a purifikace patogenita MeSH
- Streptococcus pyogenes izolace a purifikace MeSH
- streptokokové infekce etiologie imunologie patologie MeSH
- T-lymfocyty fyziologie imunologie metabolismus MeSH
- výsledek terapie MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mužské pohlaví MeSH
- myši MeSH
- ženské pohlaví MeSH
- Publikační typ
- kazuistiky MeSH
- práce podpořená grantem MeSH
Extensive selection of cyanobacterial strains (82 isolates) belonging to the genus Nostoc, isolated from different climatic regions and habitats, were screened for both their secondary metabolite content and their cytotoxic effects to mammalian cell lines. The overall occurrence of cytotoxicity was found to be 33%, which corresponds with previously published data. However, the frequency differs significantly among strains, which originate from different climatic regions and microsites (particular localities). A large fraction of intensely cytotoxic strains were found among symbiotic strains (60%) and temperate and continental climatic isolates (45%); compared with the less significant incidences in strains originating from cold regions (36%), deserts (14%), and tropical habitats (9%). The cytotoxic strains were not randomly distributed; microsites that clearly had a higher occurrence of cytotoxicity were observed. Apparently, certain natural conditions lead to the selection of cytotoxic strains, resulting in a high cytotoxicity occurrence, and vice versa. Moreover, in strains isolated from a particular microsite, the cytotoxic effects were caused by different compounds. This result supports our hypothesis for the environmental dependence of cytotoxicity. It also contradicts the hypothesis that clonality and lateral gene transfer could be the reason for this phenomenon. Enormous variability in the secondary metabolites was detected within the studied Nostoc extracts. According to their molecular masses, only 26% of these corresponded to any known structures; thus, pointing to the high potential for the use of many terrestrial cyanobacteria in both pharmacology and biotechnology.
Coelomic fluid of the Lumbricid Eisenia fetida contains a 42-kDa pattern recognition protein named coelomic cytolytic factor (CCF) that binds microbial cell wall components and triggers the activation of the prophenoloxidase cascade, an important invertebrate defense pathway. Here we report on the sequence characterization of CCF-like molecules of other Lumbricids: Aporrectodea caliginosa, Aporrectodea icterica, Aporrectodea longa, Aporrectodea rosea, Dendrobaena veneta, Lumbricus rubellus and Lumbricus terrestris, and show that CCF from E. fetida has a broader saccharide-binding specificity, being the only one recognizing N,N'-diacetylchitobiose. We suggest that the broad recognition repertoire of E. fetida CCF reflects a particular microbial environment this species lives in.
- MeSH
- cytotoxiny farmakologie genetika metabolismus MeSH
- disacharidy metabolismus MeSH
- financování organizované MeSH
- fylogeneze MeSH
- katecholoxidasa metabolismus MeSH
- lektiny farmakologie genetika metabolismus MeSH
- lidé MeSH
- molekulární sekvence - údaje MeSH
- nádorové buněčné linie MeSH
- Oligochaeta genetika metabolismus MeSH
- prekurzory enzymů metabolismus MeSH
- sekvence aminokyselin MeSH
- sekvence nukleotidů MeSH
- sekvenční seřazení MeSH
- substrátová specifita MeSH
- technika náhodné amplifikace polymorfní DNA MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- srovnávací studie MeSH
- MeSH
- bakteriální proteiny genetika MeSH
- bakteriemie mikrobiologie mortalita MeSH
- cytotoxiny genetika metabolismus MeSH
- finanční podpora výzkumu jako téma MeSH
- krysa rodu rattus MeSH
- meningokokové infekce mortalita MeSH
- Neisseria meningitidis metabolismus patogenita MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
