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1.
Curr Alzheimer Res ; 16(8): 723-731, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31418660

RESUMO

BACKGROUND: Curcumin has been of interest in the field of Alzheimer's disease. Early studies on transgenic mice showed promising results in the reduction of amyloid plaques.However, curcumin is very poorly soluble in aqueous solutions and not easily accessible to coupling as it contains only phenolic groups as potential coupling sites. For these reasons only few imaging studies using curcumin bound as an ester were performed and curcumin is mainly used as nutritional supplement. METHODS: In the present study we produced an aminoethyl ether derivative of curcumin using a nucleophilic substitution reaction. This is a small modification and should not impact the properties of curcumin while introducing an easily accessible reactive amino group. This novel compound could be used to couple curcumin to other molecules using the standard methods of peptide synthesis. We studied the aminoethyl-curcumin compound and a tripeptide carrying this aminoethyl-curcumin and the fluorescent dye fluorescein (FITC-curcumin) in vitro on cell culture using confocal laser scanning microscopy and flow cytometry. Then these two substances were tested ex vivo on brain sections prepared from transgenic mice depicting Alzheimer-like ß-amyloid plaques. RESULTS: In the in vitro CLSM microscopy and flow cytometry experiments we found dot-like unspecific uptake and only slight cytotoxicity correlating with this uptake. As these measurements were optimized for the use of fluorescein as dye we found that the curcumin at 488nm fluorescence excitation was not strong enough to use it as a fluorescence marker in these applications. In the ex vivo sections CLSM experiments both the aminoethyl-curcumin and the FITC-curcumin peptide bound specifically to ß- amyloid plaques. CONCLUSION: In conclusion we successfully produced a novel curcumin derivative which could easily be coupled to other imaging or therapeutic molecules as a sensor for amyloid plaques.

2.
Int J Med Microbiol ; 309(6): 151333, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31362856

RESUMO

Staphylococcus aureus produces different secondary cell wall glycopolymers such as wall teichoic acids (WTA) and capsular polysaccharides (CP). These structures play an important role in S. aureus colonization, pathogenesis and bacterial evasion of the host immune defences. To fulfil their diverse functions, biosynthesis of both glycopolymers has to be tightly controlled. Regulation of WTA biosynthesis and modification is only partially understood. The transcription factor MgrA and the two-component systems (TCS) Agr, GraRS, and ArlRS control WTA export, chain-length and modification. CP synthesis is determined by transcriptional and post-transcriptional regulatory circuits. On the transcriptional level expression of the capA-P operon is mainly driven by the alternative Sigma factor B and modulated by several transcriptional factors and TCS. Post-transcriptional mechanisms are in place to avoid conflict between precursor usage by the CP synthesis machinery and the synthesis machinery of other cell wall glycopolymers. The complex interplay of these regulatory systems determines the peculiar, strictly temporal expression of CP in the late growth phase and the high degree of phenotypic heterogeneity. Differential expression of CP, WTA and its modification systems during infection and colonisation are likely important for disease development, immune escape and survival within the host.

3.
Mol Microbiol ; 112(4): 1083-1099, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31283061

RESUMO

Capsular polysaccharide (CP) biosynthesis in Staphylococcus aureus is tightly controlled resulting in a heterogeneous phenotype within a population and CP being mainly detectable in nongrowing cells. Expression of the corresponding biosynthesis gene cluster is driven by one promoter element (Pcap ). Here, we demonstrate that Pcap contains a main SigB-dependent promoter. The SigB consensus motif overlaps with a previously described inverted repeat (IR) that is crucial for cap expression. The essentiality of the IR is derived from this region acting as a SigB binding site rather than as an operator site for the proposed cap activators RbsR and MsaB. Furthermore, Pcap contains an extensive upstream region harboring a weak SigA-dependent promoter and binding sites for cap repressors such as SaeR, CodY and Rot. Heterogeneous CP synthesis is determined by SigB activity and repressor binding to the upstream region. SigB dependency and regulation by the upstream repressors are also sufficient to explain the temporal gene expression pattern at the transcriptional level. However, CP synthesis remains growth phase-dependent even when transcription is rendered constitutive, suggesting additional posttranscriptional regulatory circuits. Thus, the interference of multiple repressors with SigB-dependent promoter activity as well as post-transcriptional mechanisms ensure the appropriate regulation of CP synthesis.

4.
MBio ; 10(3)2019 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-31088921

RESUMO

Staphylococcus aureus is a major cause of skin and soft tissue infections and aggravator of the inflammatory skin disease atopic dermatitis (AD [eczema]). Epicutaneous exposure to S. aureus induces Th17 responses through skin Langerhans cells (LCs), which paradoxically contribute to host defense but also to AD pathogenesis. The molecular mechanisms underlying the interaction between S. aureus and LCs are poorly understood. Here we demonstrate that human LCs directly interact with S. aureus through the pattern recognition receptor langerin (CD207). Human, but not mouse, langerin interacts with S. aureus through the conserved ß-N-acetylglucosamine (GlcNAc) modifications on wall teichoic acid (WTA), thereby discriminating S. aureus from other staphylococcal species. Importantly, the specific S. aureus WTA glycoprofile strongly influences the level of proinflammatory cytokines that are produced by in vitro-generated LCs. Finally, in a murine epicutaneous infection model, S. aureus strongly upregulated transcripts of Cxcl1, Il6, and Il17, which required the presence of both human langerin and WTA ß-GlcNAc. Our findings provide molecular insight into the unique proinflammatory capacities of S. aureus in relation to skin inflammation.IMPORTANCE The bacterium Staphylococcus aureus is an important cause of skin infections and is also associated with the occurrence and severity of eczema. Langerhans cells (LCs), a specific subset of skin immune cells, participate in the immune response to S. aureus, but it is yet unclear how LCs recognize S. aureus Therefore, we investigated the molecular mechanism underlying the interaction between LCs and S. aureus We identified that wall teichoic acid, an abundant polymer on the S. aureus surface, is recognized by langerin, a receptor unique to LCs. This interaction allows LCs to discriminate S. aureus from other related staphylococcal species and initiates a proinflammatory response similar to that observed in patients with eczema. Our data therefore provide important new insights into the relationship between S. aureus, LCs, and eczema.


Assuntos
Antígenos CD/genética , Antígenos de Superfície/genética , Células de Langerhans/imunologia , Lectinas Tipo C/genética , Lectinas de Ligação a Manose/genética , Infecções Estafilocócicas/imunologia , Ácidos Teicoicos/imunologia , Acetilglucosamina , Animais , Antígenos CD/imunologia , Antígenos de Superfície/imunologia , Células Cultivadas , Citocinas/genética , Citocinas/imunologia , Humanos , Inflamação , Interleucina-17/genética , Interleucina-17/imunologia , Lectinas Tipo C/imunologia , Lectinas de Ligação a Manose/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Pele/imunologia , Pele/microbiologia , Staphylococcus aureus
5.
Sci Rep ; 9(1): 3640, 2019 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-30842543

RESUMO

Microbial resistance against clinical used antibiotics is on the rise. Accordingly, there is a high demand for new innovative antimicrobial strategies. The host-defense peptide human beta-defensin 1 (hBD-1) is produced continuously by epithelial cells and exhibits compelling antimicrobial activity after reduction of its disulphide bridges. Here we report that proteolysis of reduced hBD-1 by gastrointestinal proteases as well as human duodenal secretions produces an eight-amino acid carboxy-terminal fragment. The generated octapeptide retains antibiotic activity, yet with distinct characteristics differing from the full-length peptide. We modified the octapeptide by stabilizing its termini and by using non-natural D-amino acids. The native and modified peptide variants showed antibiotic activity against pathogenic as well as antibiotic-resistant microorganisms, including E. coli, P. aeruginosa and C. albicans. Moreover, in an in vitro C. albicans infection model the tested peptides demonstrated effective amelioration of C. albicans infection without showing cytotoxity on human cells. In summary, protease degradation of hBD-1 provides a yet unknown mechanism to broaden antimicrobial host defense, which could be used to develop defensin-derived therapeutic applications.

6.
Artigo em Inglês | MEDLINE | ID: mdl-30271756

RESUMO

Staphylococcus aureus is one of the major human bacterial pathogens causing a broad spectrum of serious infections. Myeloid-derived suppressor cells (MDSC) represent an innate immune cell subset capable of regulating host-pathogen interactions, yet their role in the pathogenesis of S. aureus infections remains incompletely defined. The aim of this study was to determine the influence of different S. aureus strains and associated virulence factors on human MDSC generation. Using an in vitro MDSC generation assay we demonstrate that low concentrations of supernatants of different S. aureus strains led to an induction of functional MDSC, whereas increased concentrations, conversely, reduced MDSC numbers. The concentration-dependent reduction of MDSC correlated with T cell proliferation and cytotoxicity. Several findings supported a role for staphylococcal enterotoxins in modulating MDSC generation. Staphylococcal enterotoxins recapitulated concentration-dependent MDSC induction and inhibition, T cell proliferation and cytotoxicity, while an enterotoxin-deficient S. aureus strain largely failed to alter MDSC. Taken together, we identified staphylococcal enterotoxins as main modulators of MDSC generation. The inhibition of MDSC generation by staphylococcal enterotoxins might represent a novel therapeutic target in S. aureus infections and beyond in non-infectious conditions, such as cancer.


Assuntos
Proliferação de Células/efeitos dos fármacos , Enterotoxinas/imunologia , Células Supressoras Mieloides/efeitos dos fármacos , Células Supressoras Mieloides/imunologia , Staphylococcus aureus/imunologia , Células Cultivadas , Enterotoxinas/metabolismo , Humanos , Evasão da Resposta Imune , Tolerância Imunológica , Modelos Teóricos , Infecções Estafilocócicas/imunologia , Infecções Estafilocócicas/patologia , Staphylococcus aureus/metabolismo
8.
Curr Pharm Des ; 24(16): 1821-1826, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29623828

RESUMO

Curcumin, as the main ingredient of the curcuma spice, has increasingly become the target of scientific research. The turmeric root where the spice is obtained from has been widely used in the traditional medicine. Moreover, scientific studies have found that curcumin has anti-inflammatory, anti-cancer, anti-angiogenic effects as well as antibacterial properties. Recently, curcumin has gathered interest as a potential therapeutic agent in the research on Alzheimer's disease. A consistent problem in the investigative and therapeutic applications of curcumin is its poor solubility in aqueous solutions. In the present study, we synthesized a conjugate of curcumin, the amino acid lysine and the fluorescent dye fluorescein. This conjugate was soluble in cell culture medium and facilitated the examination of curcumin with fluorescence imaging methods. We studied the cell growth impact of unmodified curcumin on seven different human cell lines and then analyzed the uptake and cellular localization of our curcumin conjugate with confocal laser scanning imaging and flow cytometry on the seven cell lines. We found that unbound curcumin inhibited cell growth in vitro and was not taken up into the cells. The curcumin conjugate was internalized into the cell cytoplasm in a dot-like pattern and cellular uptake correlated with the cell membrane damage which was measured using propidium iodide. The CAL-72 osteosarcoma cell exhibited 3-4fold increased conjugate uptake and a strong uniform fluorescein staining in addition to the dot-like pattern observed in all cell lines. In conclusion, we successfully synthesized a novel water-soluble fluorescent curcumin conjugate which showed a strong preference for CAL-72 osteosarcoma cells in vitro.


Assuntos
Antineoplásicos/química , Antineoplásicos/farmacologia , Curcumina/química , Curcumina/farmacologia , Fluorescência , Imagem Óptica , Antineoplásicos/síntese química , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Curcumina/síntese química , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Estrutura Molecular , Solubilidade , Relação Estrutura-Atividade
9.
Nat Commun ; 9(1): 1379, 2018 04 11.
Artigo em Inglês | MEDLINE | ID: mdl-29643357

RESUMO

Secretion of extracellular vesicles (EVs), a process common to eukaryotes, archae, and bacteria, represents a secretory pathway that allows cell-free intercellular communication. Microbial EVs package diverse proteins and influence the host-pathogen interaction, but the mechanisms underlying EV production in Gram-positive bacteria are poorly understood. Here we show that EVs purified from community-associated methicillin-resistant Staphylococcus aureus package cytosolic, surface, and secreted proteins, including cytolysins. Staphylococcal alpha-type phenol-soluble modulins promote EV biogenesis by disrupting the cytoplasmic membrane; whereas, peptidoglycan cross-linking and autolysin activity modulate EV production by altering the permeability of the cell wall. We demonstrate that EVs purified from a S. aureus mutant that is genetically engineered to express detoxified cytolysins are immunogenic in mice, elicit cytolysin-neutralizing antibodies, and protect the animals in a lethal sepsis model. Our study reveals mechanisms underlying S. aureus EV production and highlights the usefulness of EVs as a S. aureus vaccine platform.


Assuntos
Anticorpos Neutralizantes/biossíntese , Citotoxinas/administração & dosagem , Vesículas Extracelulares/imunologia , Sepse/prevenção & controle , Infecções Estafilocócicas/prevenção & controle , Vacinas Antiestafilocócicas/administração & dosagem , Animais , Parede Celular/química , Parede Celular/imunologia , Citotoxinas/metabolismo , Vesículas Extracelulares/química , Feminino , Engenharia Genética/métodos , Staphylococcus aureus Resistente à Meticilina/química , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/imunologia , Staphylococcus aureus Resistente à Meticilina/patogenicidade , Camundongos , Peptidoglicano/química , Peptidoglicano/imunologia , Sepse/imunologia , Sepse/microbiologia , Sepse/mortalidade , Infecções Estafilocócicas/imunologia , Infecções Estafilocócicas/microbiologia , Infecções Estafilocócicas/mortalidade , Vacinas Antiestafilocócicas/genética , Vacinas Antiestafilocócicas/imunologia , Análise de Sobrevida , Vacinação
10.
Sci Rep ; 8(1): 1889, 2018 01 30.
Artigo em Inglês | MEDLINE | ID: mdl-29382892

RESUMO

Surface carbohydrate moieties are essential for bacterial communication, phage-bacteria and host-pathogen interaction. Most Staphylococcus aureus produce polyribitolphosphate type Wall teichoic acids (WTAs) substituted with α- and/or ß-O-linked N-acetyl-glucosamine (α-/ß-O-GlcNAc) residues. GlcNAc modifications have attracted particular interest, as they were shown to govern staphylococcal adhesion to host cells, to promote phage susceptibility conferring beta-lactam resistance and are an important target for antimicrobial agents and vaccines. However, there is a lack of rapid, reliable, and convenient methods to detect and quantify these sugar residues. Whole cell Fourier transform infrared (FTIR) spectroscopy could meet these demands and was employed to analyse WTAs and WTA glycosylation in S. aureus. Using S. aureus mutants, we found that a complete loss of WTA expression resulted in strong FTIR spectral perturbations mainly related to carbohydrates and phosphorus-containing molecules. We could demonstrate that α- or ß-O-GlcNAc WTA substituents can be clearly differentiated by chemometrically assisted FTIR spectroscopy. Our results suggest that whole cell FTIR spectroscopy represents a powerful and reliable method for large scale analysis of WTA glycosylation, thus opening up a complete new range of options for deciphering the staphylococcal pathogenesis related glycocode.


Assuntos
Proteínas de Bactérias/metabolismo , Staphylococcus aureus/metabolismo , Ácidos Teicoicos/metabolismo , Glicosilação , Glicosiltransferases/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Infecções Estafilocócicas/metabolismo , Infecções Estafilocócicas/microbiologia , Resistência beta-Lactâmica/fisiologia
11.
Nat Rev Microbiol ; 15(11): 675-687, 2017 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-29021598

RESUMO

Although human colonization by facultative bacterial pathogens, such as Staphylococcus aureus, represents a major risk factor for invasive infections, the commensal lifestyle of such pathogens has remained a neglected area of research. S. aureus colonizes the nares of approximately 30% of the human population and recent studies suggest that the composition of highly variable nasal microbiota has a major role in promoting or inhibiting S. aureus colonization. Competition for epithelial attachment sites or limited nutrients, different susceptibilities to host defence molecules and the production of antimicrobial molecules may determine whether nasal bacteria outcompete each other. In this Review, we discuss recent insights into mechanisms that are used by S. aureus to prevail in the human nose and the counter-strategies that are used by other nasal bacteria to interfere with its colonization. Understanding such mechanisms will be crucial for the development of new strategies for the eradication of endogenous facultative pathogens.


Assuntos
Microbiota , Nariz/microbiologia , Staphylococcus aureus/fisiologia , Animais , Modelos Animais de Doenças , Farmacorresistência Bacteriana Múltipla , Interações Hospedeiro-Patógeno , Humanos , Modelos Moleculares , Cavidade Nasal/microbiologia , Fatores de Risco , Infecções Estafilocócicas/prevenção & controle , Staphylococcus aureus/efeitos dos fármacos
12.
Infect Immun ; 85(10)2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28760929

RESUMO

The human pathogen Burkholderia pseudomallei and the related species Burkholderia thailandensis are facultative intracellular bacteria characterized by the ability to escape into the cytosol of the host cell and to stimulate the formation of multinucleated giant cells (MNGCs). MNGC formation is induced via an unknown mechanism by bacterial type VI secretion system 5 (T6SS-5), which is an essential virulence factor in both species. Despite the vital role of the intracellular life cycle in the pathogenesis of the bacteria, the range of host cell types permissive for initiation and completion of the intracellular cycle is poorly defined. In the present study, we used several different types of human primary cells to evaluate bacterial entry, intracellular survival, and MNGC formation. We report the capacity of B. pseudomallei to enter, efficiently replicate in, and mediate MNGC formation of vein endothelial and bronchial epithelial cells, indicating that the T6SS-5 is important in the host-pathogen interaction in these cells. Furthermore, we show that B. pseudomallei invades fibroblasts and keratinocytes and survives inside these cells as well as in monocyte-derived macrophages and neutrophils for at least 17 h postinfection; however, MNGC formation is not induced in these cells. In contrast, infection of mixed neutrophils and RAW264.7 macrophages with B. thailandensis stimulated the formation of heterotypic MNGCs in a T6SS-5-dependent manner. In summary, the ability of the bacteria to enter and survive as well as induce MNGC formation in certain host cells may contribute to the pathogenesis observed in B. pseudomallei infection.


Assuntos
Burkholderia pseudomallei/fisiologia , Células Gigantes/microbiologia , Interações Hospedeiro-Patógeno , Macrófagos/microbiologia , Fagócitos/microbiologia , Animais , Brônquios/citologia , Brônquios/microbiologia , Burkholderia pseudomallei/crescimento & desenvolvimento , Burkholderia pseudomallei/patogenicidade , Linhagem Celular , Células Cultivadas , Citosol/microbiologia , Células Endoteliais/microbiologia , Células Epiteliais/microbiologia , Fibroblastos/microbiologia , Humanos , Queratinócitos/microbiologia , Camundongos , Neutrófilos/microbiologia , Sistemas de Secreção Tipo VI/metabolismo , Virulência
14.
Nat Microbiol ; 2: 16257, 2017 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-28112716

RESUMO

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) are the cause of a severe pandemic consisting primarily of skin and soft tissue infections. The underlying pathomechanisms have not been fully understood and we report here a mechanism that plays an important role for the elevated virulence of CA-MRSA. Surprisingly, skin abscess induction in an animal model was correlated with the amount of a major cell wall component of S. aureus, termed wall teichoic acid (WTA). CA-MRSA exhibited increased cell-wall-associated WTA content (WTAhigh) and thus were more active in inducing abscess formation via a WTA-dependent and T-cell-mediated mechanism than S. aureus strains with a WTAlow phenotype. We show here that WTA is directly involved in S. aureus strain-specific virulence and provide insight into the underlying molecular mechanisms that could guide the development of novel anti-infective strategies.


Assuntos
Abscesso/microbiologia , Parede Celular/química , Staphylococcus aureus Resistente à Meticilina/patogenicidade , Infecções Cutâneas Estafilocócicas/microbiologia , Ácidos Teicoicos/biossíntese , Animais , Antibacterianos/farmacologia , Infecções Comunitárias Adquiridas/microbiologia , Masculino , Staphylococcus aureus Resistente à Meticilina/química , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/genética , Camundongos , Pele/microbiologia , Pele/patologia , Ácidos Teicoicos/análise , Virulência , Fatores de Virulência/biossíntese
15.
Curr Top Microbiol Immunol ; 409: 57-93, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-26728067

RESUMO

The major surface polysaccharides of Staphylococcus aureus include the capsular polysaccharide (CP), cell wall teichoic acid (WTA), and polysaccharide intercellular adhesin/poly-ß(1-6)-N-acetylglucosamine (PIA/PNAG). These glycopolymers are important components of the staphylococcal cell envelope, but none of them is essential to S. aureus viability and growth in vitro. The overall biosynthetic pathways of CP, WTA, and PIA/PNAG have been elucidated, and the functions of most of the biosynthetic enzymes have been demonstrated. Because S. aureus CP and WTA (but not PIA/PNAG) utilize a common cell membrane lipid carrier (undecaprenyl-phosphate) that is shared by the peptidoglycan biosynthesis pathway, there is evidence that these processes are highly integrated and temporally regulated. Regulatory elements that control glycopolymer biosynthesis have been described, but the cross talk that orchestrates the biosynthetic pathways of these three polysaccharides remains largely elusive. CP, WTA, and PIA/PNAG each play distinct roles in S. aureus colonization and the pathogenesis of staphylococcal infection. However, they each promote bacterial evasion of the host immune defences, and WTA is being explored as a target for antimicrobial therapeutics. All the three glycopolymers are viable targets for immunotherapy, and each (conjugated to a carrier protein) is under evaluation for inclusion in a multivalent S. aureus vaccine. Future research findings that increase our understanding of these surface polysaccharides, how the bacterial cell regulates their expression, and their biological functions will likely reveal new approaches to controlling this important bacterial pathogen.


Assuntos
Polissacarídeos , Staphylococcus aureus , Polissacarídeos Bacterianos
17.
Nature ; 535(7613): 511-6, 2016 07 28.
Artigo em Inglês | MEDLINE | ID: mdl-27466123

RESUMO

The vast majority of systemic bacterial infections are caused by facultative, often antibiotic-resistant, pathogens colonizing human body surfaces. Nasal carriage of Staphylococcus aureus predisposes to invasive infection, but the mechanisms that permit or interfere with pathogen colonization are largely unknown. Whereas soil microbes are known to compete by production of antibiotics, such processes have rarely been reported for human microbiota. We show that nasal Staphylococcus lugdunensis strains produce lugdunin, a novel thiazolidine-containing cyclic peptide antibiotic that prohibits colonization by S. aureus, and a rare example of a non-ribosomally synthesized bioactive compound from human-associated bacteria. Lugdunin is bactericidal against major pathogens, effective in animal models, and not prone to causing development of resistance in S. aureus. Notably, human nasal colonization by S. lugdunensis was associated with a significantly reduced S. aureus carriage rate, suggesting that lugdunin or lugdunin-producing commensal bacteria could be valuable for preventing staphylococcal infections. Moreover, human microbiota should be considered as a source for new antibiotics.


Assuntos
Antibacterianos/metabolismo , Peptídeos Cíclicos/metabolismo , Infecções Estafilocócicas/microbiologia , Infecções Estafilocócicas/prevenção & controle , Staphylococcus aureus/crescimento & desenvolvimento , Staphylococcus lugdunensis/metabolismo , Simbiose , Tiazolidinas/metabolismo , Animais , Antibacterianos/biossíntese , Portador Sadio/microbiologia , Modelos Animais de Doenças , Resistência Microbiana a Medicamentos , Feminino , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Testes de Sensibilidade Microbiana , Microbiota/fisiologia , Nariz/microbiologia , Sigmodontinae , Infecções Estafilocócicas/tratamento farmacológico , Staphylococcus aureus/patogenicidade
18.
FEBS Lett ; 590(21): 3758-3771, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27396949

RESUMO

Cell wall glycopolymers (CWGs) of gram-positive bacteria have gained increasing interest with respect to their role in colonization and infection. In most gram-positive pathogens they constitute a large fraction of the cell wall biomass and represent major cell envelope determinants. Depending on their chemical structure they modulate interaction with complement factors and play roles in immune evasion or serve as nonprotein adhesins that mediate, especially under dynamic conditions, attachment to different host cell types. In particular, covalently peptidoglycan-attached CWGs that extend well above the cell wall seem to interact with glyco-receptors on host cell surfaces. For example, in the case of Staphylococcus aureus, the cell wall-attached teichoic acid (WTA) has been identified as a major CWG adhesin. A recent report indicates that a type-F scavenger receptor, termed SR-F1 (SREC-I), is the predominant WTA receptor in the nasal cavity and that WTA-SREC-I interaction plays an important role in S. aureus nasal colonization. Therefore, understanding the role of CWGs in complex processes that mediate colonization and infection will allow novel insights into the mechanisms of host-microbiota interaction.


Assuntos
Parede Celular/metabolismo , Firmicutes/metabolismo , Polissacarídeos Bacterianos/metabolismo , Receptores Depuradores Classe F/metabolismo , Adesinas Bacterianas/química , Adesinas Bacterianas/metabolismo , Parede Celular/química , Firmicutes/química , Infecções por Bactérias Gram-Positivas/microbiologia , Interações Hospedeiro-Patógeno , Humanos , Cavidade Nasal/microbiologia , Polissacarídeos Bacterianos/química
19.
Med Chem ; 13(1): 57-64, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27026529

RESUMO

BACKGROUND: Previously, glycopeptides antibiotics such as vancomycin, ramoplanin and an antifungal antibiotic nystatin have been studied for their diagnostic and therapeutic potential. OBJECTIVE: To further explore the diagnostic and chemotherapeutic potential of other antibiotics we have now employed daptomycin, a lipopetide antibiotic and bacitracin, a polypeptide antibiotic in uptake and vitality tests on human cell lines. METHOD: Fluorescent conjugates of bacitracin and daptomycin were synthesized using fluorescein isothiocynate (FITC) for confocal laser scanning microscopy (CLSM) and fluorescence activated cell sorting (FACS). The cellular uptake of the synthesized daptomycin and bacitracin conjugates was studied on seven human cell lines, two healthy and five malignant using CLSM and FACS. To examine the cell membrane damage caused by the conjugates FACS experiments were carried out using propidium iodide. RESULTS: The uptake pattern was different for both antibiotics for all the cell lines. The cytoplasmic uptake of daptomycin conjugate was lower than the bacitracin conjugate, resulting in decreased cell membrane damage. CONCLUSION: No preferential uptake into malignant or healthy cells was found for the two different antibiotic conjugates and the uptake patterns were also different between the two antibiotics. However, the lower cytotoxicity and different uptake mechanism makes daptomycin conjugate a prospective candidate for further study as a diagnostic agent for various intracellular infections.


Assuntos
Bacitracina/química , Daptomicina/química , Fluoresceína/química , Corantes Fluorescentes/química , Imagem Óptica , Bacitracina/síntese química , Bacitracina/farmacocinética , Separação Celular , Daptomicina/síntese química , Daptomicina/farmacocinética , Fluoresceína/síntese química , Fluoresceína/farmacocinética , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/farmacocinética , Células HEK293 , Humanos , Células MCF-7 , Microscopia Confocal , Estrutura Molecular , Células Tumorais Cultivadas
20.
PLoS One ; 11(3): e0150907, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26960193

RESUMO

Treatment of Staphylococcus aureus in stationary growth phase with high doses of the antibiotic daptomycin (DAP) eradicates the vast majority of the culture and leaves persister cells behind. Despite resting in a drug-tolerant and dormant state, persister cells exhibit metabolic activity which might be exploited for their elimination. We here report that the addition of glucose to S. aureus persisters treated with DAP increased killing by up to five-fold within one hour. This glucose-DAP effect also occurred with strains less sensitive to the drug. The underlying mechanism is independent of the proton motive force and was not observed with non-metabolizable 2-deoxy-glucose. Our results are consistent with two hypotheses on the glucose-DAP interplay. The first is based upon glucose-induced carbohydrate transport proteins that may influence DAP and the second suggests that glucose may trigger the release or activity of cell-lytic proteins to augment DAP's mode of action.


Assuntos
Antibacterianos/farmacologia , Daptomicina/farmacologia , Glucose/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Sinergismo Farmacológico , Testes de Sensibilidade Microbiana
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