RESUMO
The ability of gut bacterial pathogens to escape immunity by antigenic variation-particularly via changes to surface-exposed antigens-is a major barrier to immune clearance1. However, not all variants are equally fit in all environments2,3. It should therefore be possible to exploit such immune escape mechanisms to direct an evolutionary trade-off. Here, we demonstrate this phenomenon using Salmonella enterica subspecies enterica serovar Typhimurium (S.Tm). A dominant surface antigen of S.Tm is its O-antigen: a long, repetitive glycan that can be rapidly varied by mutations in biosynthetic pathways or by phase variation4,5. We quantified the selective advantage of O-antigen variants in the presence and absence of O-antigen-specific immunoglobulin A and identified a set of evolutionary trajectories allowing immune escape without an associated fitness cost in naive mice. Through the use of rationally designed oral vaccines, we induced immunoglobulin A responses blocking all of these trajectories. This selected for Salmonella mutants carrying deletions of the O-antigen polymerase gene wzyB. Due to their short O-antigen, these evolved mutants were more susceptible to environmental stressors (detergents or complement) and predation (bacteriophages) and were impaired in gut colonization and virulence in mice. Therefore, a rationally induced cocktail of intestinal antibodies can direct an evolutionary trade-off in S.Tm. This lays the foundations for the exploration of mucosal vaccines capable of setting evolutionary traps as a prophylactic strategy.
Assuntos
Imunoglobulina A/imunologia , Intestinos/imunologia , Infecções por Salmonella/prevenção & controle , Vacinas contra Salmonella/imunologia , Salmonella typhimurium/imunologia , Administração Oral , Animais , Anticorpos Antibacterianos/imunologia , Variação Antigênica , Proteínas de Bactérias/genética , Evolução Molecular , Aptidão Genética , Hexosiltransferases/genética , Evasão da Resposta Imune , Imunidade nas Mucosas , Intestinos/microbiologia , Camundongos , Mutação , Antígenos O/genética , Antígenos O/imunologia , Infecções por Salmonella/microbiologia , Vacinas contra Salmonella/administração & dosagem , Salmonella typhimurium/genética , Salmonella typhimurium/patogenicidade , Vacinas Atenuadas/administração & dosagem , Vacinas Atenuadas/imunologia , VirulênciaRESUMO
Arabinogalactan, a microheterogeneous polysaccharide occurring in plants, is known for its allergy-protective activity, which could potentially be used for preventive allergy treatment. New treatment options are highly desirable, especially in a preventive manner, due to the constant rise of atopic diseases worldwide. The structural origin of the allergy-protective activity of arabinogalactan is, however, still unclear and isolation of the polysaccharide is not feasible for pharmaceutical applications due to a variation of the activity of the natural product and contaminations with endotoxins. Therefore, a pentasaccharide partial structure was selected for total synthesis and subsequently coupled to a carrier protein to form a neoglycoconjugate. The allergy-protective activity of arabinogalactan could be reproduced with the partial structure in subsequent in vivo experiments. This is the first example of a successful simplification of arabinogalactan with a single partial structure while retaining its allergy-preventive potential.
RESUMO
The structure of the polysaccharide O-chain of the lipopolysaccharide isolated from the sequenced strain Chromobacterium violaceum ATCC 12472 (NCTC 9757) was investigated by chemical and NMR analyses, and concluded to be -4-α-Leg5Ac7Ala-4-ß-d-ManNAlaA3OAc-3-α-d-GlcNAc-where Leg5Ac7Ala indicates 5-acetamido-7-alanylamido-3,5,7,9-tetradeoxy-d-glycero-d-galacto-non-2-ulopyranosonic acid and ManNAlaA3OAc 3-O-acetyl-2-alanylamido-2-deoxymannopyranuronic acid. The structure of the core with one repeating unit of the polysaccharide attached was also analyzed, and it was found that the O-chain polysaccharide is linked to the core via ß-GlcpNAc, as opposite to α-GlcpNAc inside the O-chain.
Assuntos
Chromobacterium/química , Lipopolissacarídeos/química , Sequência de Carboidratos , Chromobacterium/metabolismo , Concentração de Íons de Hidrogênio , Lipopolissacarídeos/biossínteseRESUMO
The structure of lipid A from lipopolysaccharide (LPS) of Rhodomicrobium vannielii ATCC 17100 (Rv) a phototrophic, budding bacterium was re-investigated using high-resolution mass spectrometry, NMR, and chemical degradation protocols. It was found that the (GlcpN)-disaccharide lipid A backbone was substituted by a GalpA residue that was connected to C-1 of proximal GlcpN. Some of this GalpA residue was ß-eliminated by alkaline de-acylation, which indicated the possibility of the presence of another so far unidentified substituent at C-4 in non-stoichiometric amounts. One Manp residue substituted C-4' of distal GlcpN. The lipid A backbone was acylated by 16:0(3-OH) at C-2 of proximal GlcpN, and by 16:0(3-OH), i17:0(3-OH), or 18:0(3-OH) at C-2' of distal GlcpN. Two acyloxy-acyl moieties that were mainly formed by 14:0(3-O-14:0) and 16:0(3-O-22:1) occupied the distal GlcpN of lipid A. Genes that were possibly involved in the modification of Rv lipid A were compared with bacterial genes of known function. The biological activity was tested at the model of human mononuclear cells (MNC), showing that Rv lipid A alone does not significantly stimulate MNC. At low concentrations of toxic Escherichia coli O111:B4 LPS, pre-incubation with Rv lipid A resulted in a substantial reduction of activity, but, when higher concentrations of E. coli LPS were used, the stimulatory effect was increased.
Assuntos
Lipídeo A/química , Rhodomicrobium/química , Cromatografia Líquida , Humanos , Lipopolissacarídeos/química , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Estrutura Molecular , Processos Fototróficos , Rhodomicrobium/metabolismo , Espectrometria de Massas por Ionização por Electrospray , Espectrometria de Massas em TandemRESUMO
Glycolipids (such as glycoglycerolipids, glycosphingolipids, and glycosylphosphatidylinositol) and lipoglycans (such as lipopolysaccharides (LPS), lipooligosaccharides (LOS), mycobacterial lipoarabinomannan, and mycoplasma lipoglycans) are typically found on the surface of cell membranes and play crucial roles in various cellular functions. Characterizing their structure and dynamics at the molecular level is essential to understand their biological roles, but systematic generation of glycolipid and lipoglycan structures is challenging because of great variations in lipid structures and glycan sequences (i.e., carbohydrate types and their linkages). To facilitate the generation of all-atom glycolipid/LPS/LOS structures, we have developed Glycolipid Modeler and LPS Modeler in CHARMM-GUI ( http://www.charmm-gui.org ), a web-based interface that simplifies building of complex biological simulation systems. In addition, we have incorporated these modules into Membrane Builder so that users can readily build a complex symmetric or asymmetric biological membrane system with various glycolipids and LPS/LOS. These tools are expected to be useful in innovative and novel glycolipid/LPS/LOS modeling and simulation research by easing tedious and intricate steps in modeling complex biological systems and shall provide insight into structures, dynamics, and underlying mechanisms of complex glycolipid-/LPS-/LOS-containing biological membrane systems.
Assuntos
Glicolipídeos/química , Lipopolissacarídeos/química , Proteínas de Bactérias/química , Antígenos CD59/química , Campylobacter jejuni/química , Membrana Celular/química , Simulação por Computador , Escherichia coli/química , Glicosilfosfatidilinositóis/química , Humanos , Simulação de Dinâmica Molecular , Interface Usuário-ComputadorRESUMO
Mycobacterium tuberculosis (Mtb), the main causative agent of tuberculosis (Tb), has a complex cell envelope which forms an efficient barrier to antibiotics, thus contributing to the challenges of anti-tuberculosis therapy. However, the unique Mtb cell wall can be considered an advantage and be utilized to selectively label Mtb bacteria. Here we introduce three azido pentoses as new compounds for metabolic labeling of Mtb: 3-azido arabinose (3AraAz), 3-azido ribose (3RiboAz), and 5-azido arabinofuranose (5AraAz). 5AraAz demonstrated the highest level of Mtb labeling and was efficiently incorporated into the Mtb cell wall. All three azido pentoses can be easily used to label a variety of Mtb clinical isolates without influencing Mtb-dependent phagosomal maturation arrest in infection studies with human macrophages. Thus, this metabolic labeling method offers the opportunity to attach desired molecules to the surface of Mtb bacteria in order to facilitate investigation of the varying virulence characteristics of different Mtb clinical isolates, which influence the outcome of a Tb infection.
Assuntos
Azidas/química , Parede Celular/química , Mycobacterium tuberculosis/química , Pentoses/química , Coloração e Rotulagem/métodos , Biomarcadores/metabolismo , Parede Celular/metabolismo , Citometria de Fluxo , Expressão Gênica , Humanos , Proteínas de Membrana Lisossomal/genética , Proteínas de Membrana Lisossomal/imunologia , Macrófagos/citologia , Macrófagos/imunologia , Mycobacterium tuberculosis/metabolismo , Fagocitose , Proteínas rab5 de Ligação ao GTP/genética , Proteínas rab5 de Ligação ao GTP/imunologiaRESUMO
Xanthomonas translucens pv. translucens (Xtt) is a Gram-negative pathogen of crops from the plant family Poaceae. The lipopolysaccharide (LPS) of Xtt was isolated and chemically characterized. The analyses revealed the presence of rhamnose, xylose, mannose, glucose, galacturonic acid, phosphates, 3-deoxy-D-manno-oct-2-ulopyranosonic acid (Kdo) and fatty acids (10:0, 11:0, 11:0(3-OH) i/a, 11:0(3-OH), 12:0(3-OH) i/a, 12:0(3-OH), 12:0, 13:0(3-OH) i, 13:0(3-OH) a, 13:0(3-OH), 14:0(3-OH) i/a, 14:0(3-OH) and 16:0). The rough type of LPS (lipooligosaccharides; LOS) was isolated and its composition determined utilizing mass spectrometry. The structure of core-lipid A backbone was revealed by nuclear magnetic resonance (NMR) spectroscopy performed on O-deacylated LOS sample, and was shown to be: α-D-Manp-(1â3)-α-D-Manp-(1â3)-ß-D-Glcp-(1â4)-α-D-Manp-(1â5)-α-Kdo-(2â6)-ß-D-GlcpN-(1â6)-α-D-GlcpN. 4-α-Man and Kdo were further substituted via phosphodiester groups by two galactopyranuronic acids. Xtt LPS elicited a stress response in Nicotiana tabacum suspension cell cultures, namely a transient calcium signal and the generation of H2O2 was observed. Pharmacological studies indicated the involvement of plasma membrane calcium channels, kinases and phospholipase C as key factors in Xtt LPS induced pathogen signaling.
Assuntos
Lipopolissacarídeos/química , Células Vegetais/microbiologia , Doenças das Plantas/microbiologia , Xanthomonas/química , Técnicas de Cultura de Células , Peróxido de Hidrogênio/uso terapêutico , Lipopolissacarídeos/classificação , Lipopolissacarídeos/isolamento & purificação , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Células Vegetais/química , Poaceae/microbiologia , Transdução de Sinais/efeitos dos fármacos , Nicotiana/química , Nicotiana/citologia , Nicotiana/microbiologia , Xanthomonas/patogenicidadeRESUMO
Subcellular compartmentalization of receptor signaling is an emerging principle in innate immunity. However, the functional integration of receptor signaling pathways into membrane trafficking routes and its physiological relevance for immune responses is still largely unclear. In this study, using Lyst-mutant beige mice, we show that lysosomal trafficking regulator Lyst links endolysosomal organization to the selective control of toll-like receptor 3 (TLR3)- and TLR4-mediated proinflammatory responses. Consequently, Lyst-mutant mice showed increased susceptibility to bacterial infection and were largely resistant to endotoxin-induced septic shock. Mechanistic analysis revealed that Lyst specifically controls TLR3- and TLR4-induced endosomal TRIF (TIR domain-containing adapter-inducing interferon ß) signaling pathways. Loss of functional Lyst leads to dysregulated phagosomal maturation, resulting in a failure to form an activation-induced Rab7+ endosomal/phagosomal compartment. This specific Rab7+ compartment was further demonstrated to serve as a major site for active TRIF signaling events, thus linking phagosomal maturation to specific TLR signaling pathways. The immunoregulatory role of Lyst on TLR signaling pathways was confirmed in human cells by CRISPR/Cas9-mediated gene inactivation. As mutations in LYST cause human Chédiak-Higashi syndrome, a severe immunodeficiency, our findings also contribute to a better understanding of human disease mechanisms.
Assuntos
Inflamação/etiologia , Proteínas/fisiologia , Receptores Toll-Like/fisiologia , Proteínas Adaptadoras de Transporte Vesicular/fisiologia , Animais , Transporte Biológico , Células Cultivadas , Citocinas/biossíntese , Peptídeos e Proteínas de Sinalização Intracelular , Lipopolissacarídeos/toxicidade , Camundongos , Camundongos Endogâmicos C57BL , Fagossomos/fisiologia , Choque Séptico/prevenção & controle , Transdução de Sinais , Receptor 3 Toll-Like/fisiologia , Receptor 4 Toll-Like/fisiologia , Proteínas de Transporte Vesicular , Proteínas rab de Ligação ao GTP/fisiologia , proteínas de unión al GTP Rab7RESUMO
Lipoteichoic acid (LTA) is an important cell envelope compound of Gram-positive bacteria. LTA isolated from allergy-protective Staphylococcus sciuri W620 strain was characterized by chemical analyses as well as 1D and 2D NMR experiments. Compositional analyses indicated the presence of glycerol (Gro), phosphate-Gro, alanine-Gro, glucose (Glc) and fatty acids. The studied strain produced LTA with backbone composed of glycerol-phosphate repeating units only substituted with d-alanine (Ala) and the lipid anchor, typically for genus Staphyloccocus, possessing the structure ß-d-Glcp(1â6)- ß-d-Glcp(1â3)-1,2-diacyl-sn-Gro.
Assuntos
Lipopolissacarídeos/química , Staphylococcus/química , Ácidos Teicoicos/química , Sequência de CarboidratosRESUMO
The Gram-positive bacterium Enterococcus faecalis can cause life-threatening infections and is resistant to several commonly used antibiotics. The type II fatty acid pathway in bacteria is discussed as a potential target for antimicrobial therapy. However, it was shown that inhibition or deletion of its enzymes can be rescued in Gram-positive bacteria by supplementation with fatty acids. Here we show that by deletion of the fabN gene, which is essential for unsaturated fatty acid (UFA) synthesis in E. faecalis, growth is impaired but can be rescued by supplementation with oleic acid or human serum. Nonetheless, we demonstrate alterations of the UFA profile after supplementation with oleic acid in the ΔfabN mutant using a specific glycolipid. In addition, we demonstrate that cytokine release in vitro is almost abolished after stimulation of mouse macrophages by the mutant in comparison to the wild type. The results indicate that fabN is not a suitable target for antimicrobials as UFA auxotrophy can be overcome. However, deletion of fabN resulted in a decreased inflammatory response indicating that fabN and resulting UFA synthesis are relevant for virulence.
Assuntos
Proteínas de Bactérias/metabolismo , Enterococcus faecalis/fisiologia , Ácido Graxo Sintase Tipo II/metabolismo , Infecções por Bactérias Gram-Positivas/imunologia , Hidroliases/metabolismo , Macrófagos/imunologia , Animais , Proteínas de Bactérias/genética , Processos de Crescimento Celular/genética , Citocinas/metabolismo , Ácido Graxo Sintase Tipo II/genética , Humanos , Hidroliases/genética , Imunidade Inata , Mediadores da Inflamação/metabolismo , Macrófagos/microbiologia , Camundongos , Ácido Oleico/metabolismo , Organismos Geneticamente Modificados , Células RAW 264.7 , Deleção de Sequência/genética , Soro/metabolismo , Virulência/genéticaRESUMO
The structures of the lipooligosaccharides fromBrucella melitensismutants affected in the WbkD and ManBcoreproteins have been fully characterized using NMR spectroscopy. The results revealed that disruption ofwbkDgives rise to a rough lipopolysaccharide (R-LPS) with a complete core structure (ß-d-Glcp-(1â4)-α-Kdop-(2â4)[ß-d-GlcpN-(1â6)-ß-d-GlcpN-(1â4)[ß-d-GlcpN-(1â6)]-ß-d-GlcpN-(1â3)-α-d-Manp-(1â5)]-α-Kdop-(2â6)-ß-d-GlcpN3N4P-(1â6)-α-d-GlcpN3N1P), in addition to components lacking one of the terminal ß-d-GlcpN and/or the ß-d-Glcpresidues (48 and 17%, respectively). These structures were identical to those of the R-LPS fromB. melitensisEP, a strain simultaneously expressing both smooth and R-LPS, also studied herein. In contrast, disruption ofmanBcoregives rise to a deep-rough pentasaccharide core (ß-d-Glcp-(1â4)-α-Kdop-(2â4)-α-Kdop-(2â6)-ß-d-GlcpN3N4P-(1â6)-α-d-GlcpN3N1P) as the major component (63%), as well as a minor tetrasaccharide component lacking the terminal ß-d-Glcpresidue (37%). These results are in agreement with the predicted functions of the WbkD (glycosyltransferase involved in the biosynthesis of the O-antigen) and ManBcoreproteins (phosphomannomutase involved in the biosynthesis of a mannosyl precursor needed for the biosynthesis of the core and O-antigen). We also report that deletion ofB. melitensis wadCremoves the core oligosaccharide branch not linked to the O-antigen causing an increase in overall negative charge of the remaining LPS inner section. This is in agreement with the mannosyltransferase role predicted for WadC and the lack of GlcpN residues in the defective core oligosaccharide. Despite carrying the O-antigen essential inB. melitensisvirulence, the core deficiency in thewadCmutant structure resulted in a more efficient detection by innate immunity and attenuation, proving the role of the ß-d-GlcpN-(1â6)-ß-d-GlcpN-(1â4)[ß-d-GlcpN-(1â6)]-ß-d-GlcpN-(1â3)-α-d-Manp-(1â5) structure in virulence.
Assuntos
Brucella melitensis/metabolismo , Brucella melitensis/patogenicidade , Lipopolissacarídeos/metabolismo , Fatores de Virulência/metabolismo , Animais , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Brucella melitensis/genética , Brucelose/genética , Brucelose/metabolismo , Sequência de Carboidratos , Feminino , Lipopolissacarídeos/genética , Manose-6-Fosfato Isomerase/genética , Manose-6-Fosfato Isomerase/metabolismo , Camundongos , Complexos Multienzimáticos/genética , Complexos Multienzimáticos/metabolismo , Nucleotidiltransferases/genética , Nucleotidiltransferases/metabolismo , Oligossacarídeos/genética , Oligossacarídeos/metabolismo , Fatores de Virulência/genéticaRESUMO
In Yersinia pseudotuberculosis complex, the O-antigen of LPS is used for the serological characterization of strains, and 21 serotypes have been identified to date. The O-antigen biosynthesis gene cluster and corresponding O-antigen structure have been described for 18, leaving O:8, O:13 and O:14 unresolved. In this study, two O:8 isolates were examined. The O-antigen gene cluster sequence of strain 151 was near identical to serotype O:4a, though a frame-shift mutation was found in ddhD, while No. 6 was different to 151 and carried the O:1b gene cluster. Structural analysis revealed that No. 6 produced a deeply truncated LPS, suggesting a mutation within the waaF gene. Both ddhD and waaF were cloned and expressed in 151 and No. 6 strains, respectively, and it appeared that expression of ddhD gene in strain 151 restored the O-antigen on LPS, while waaF in No. 6 resulted in an LPS truncated less severely but still without the O-antigen, suggesting that other mutations occurred in this strain. Thus, both O:8 isolates were found to be spontaneous O-antigen-negative mutants derived from other validated serotypes, and we propose to remove this serotype from the O-serotyping scheme, as the O:8 serological specificity is not based on the O-antigen.
Assuntos
Lipopolissacarídeos/imunologia , Mutação/genética , Antígenos O/genética , Infecções por Yersinia pseudotuberculosis/diagnóstico , Yersinia pseudotuberculosis/imunologia , Biologia Computacional , Humanos , Lipopolissacarídeos/química , Estrutura Molecular , Família Multigênica/genética , Antígenos O/química , Antígenos O/isolamento & purificação , Sorogrupo , Sorotipagem , Especificidade da Espécie , Yersinia pseudotuberculosis/genéticaRESUMO
Streptococcus uberis is frequently isolated from the mammary gland of dairy cattle. Infection with some strains can induce mild subclinical inflammation whilst others induce severe inflammation and clinical mastitis. We compared here the inflammatory response of primary cultures of bovine mammary epithelial cells (pbMEC) towards S. uberis strains collected from clinical or subclinical cases (seven strains each) of mastitis with the strong response elicited by Escherichia coli. Neither heat inactivated nor live S. uberis induced the expression of 10 key immune genes (including TNF, IL1B, IL6). The widely used virulent strain 0140J and the avirulent strain, EF20 elicited similar responses; as did mutants defective in capsule (hasA) or biofilm formation (sub0538 and sub0539). Streptococcus uberis failed to activate NF-κB in pbMEC or TLR2 in HEK293 cells, indicating that S. uberis particles did not induce any TLR-signaling in MEC. However, preparations of lipoteichoic acid (LTA) from two strains strongly induced immune gene expression and activated NF-κB in pbMEC, without the involvement of TLR2. The immune-stimulatory LTA must be arranged in the intact S. uberis such that it is unrecognizable by the relevant pathogen receptors of the MEC. The absence of immune recognition is specific for MEC, since the same S. uberis preparations strongly induced immune gene expression and NF-κB activity in the murine macrophage model cell RAW264.7. Hence, the sluggish immune response of MEC and not of professional immune cells to this pathogen may aid establishment of the often encountered belated and subclinical phenotype of S. uberis mastitis.
Assuntos
Células Epiteliais/fisiologia , Macrófagos/fisiologia , Glândulas Mamárias Animais/microbiologia , Mastite Bovina/microbiologia , Infecções Estreptocócicas/veterinária , Streptococcus/classificação , Animais , Bovinos , Doenças dos Bovinos , Linhagem Celular , Feminino , Glândulas Mamárias Animais/citologia , Camundongos , Infecções Estreptocócicas/imunologia , Infecções Estreptocócicas/microbiologiaRESUMO
BACKGROUND: Unique phosphodihydroceramides containing phosphoethanolamine and glycerol have been previously described in Porphyromonas gingivalis. Importantly, they were shown to possess pro-inflammatory properties. Other common human bacteria were screened for the presence of these lipids, and they were found, amongst others, in the oral pathogen Tannerella forsythia. To date, no detailed study into the lipids of this organism has been performed. METHODS: Lipids were extracted, separated and purified by HPTLC, and analyzed using GC-MS, ESI-MS and NMR. Of special interest was how T. forsythia acquires the metabolic precursors for the lipids studied here. This was assayed by radioactive and stable isotope incorporation using carbon-14 and deuterium labeled myo-inositol, added to the growth medium. RESULTS: T. forsythia synthesizes two phosphodihydroceramides (Tf GL1, Tf GL2) which are constituted by phospho-myo-inositol linked to either a 17-, 18-, or 19-carbon sphinganine, N-linked to either a branched 17:0(3-OH) or a linear 16:0(3-OH) fatty acid which, in Tf GL2, is, in turn, ester-substituted with a branched 15:0 fatty acid. T. forsythia lacks the enzymatic machinery required for myo-inositol synthesis but was found to internalize inositol from the medium for the synthesis of both Tf GL1 and Tf GL2. CONCLUSION: The study describes two novel glycolipids in T. forsythia which could be essential in this organism. Their synthesis could be reliant on an external source of myo-inositol. GENERAL SIGNIFICANCE: The effects of these unique lipids on the immune system and their role in bacterial virulence could be relevant in the search for new drug targets.
Assuntos
Bacteroidaceae/metabolismo , Ceramidas/análise , Etanolaminas/análise , Inositol/metabolismo , Bacteroidaceae/química , Radioisótopos de Carbono , Ceramidas/biossíntese , Ceramidas/química , Cromatografia Líquida de Alta Pressão , Deutério , Etanolaminas/química , Etanolaminas/metabolismo , Glicerol/análise , Glicerol/química , Marcação por Isótopo , Extração Líquido-Líquido , Espectroscopia de Ressonância Magnética , Esfingosina/análogos & derivados , Esfingosina/química , Esfingosina/metabolismoRESUMO
Volume 22, no. 2, p. 178184, 2015. Page 180, column 1, final line: "IgG2a" should read "IgG1."
RESUMO
RATIONALE: The early hygiene hypothesis explained the development of allergies by a lack of infections; nowadays, the aspect of excessive cleanliness in affluent populations seems to have replaced this concept. Yet, no investigation has shown that home or personal cleanliness relate to allergic diseases. OBJECTIVES: To relate personal and home cleanliness to risk of asthma and allergies. METHODS: Comprehensive questionnaire information on home or personal cleanliness and allergic health conditions at school age was collected in 399 participants of the urban Perinatale Asthma Umwelt Langzeit Allergie Studie (PAULA) birth cohort. Bacterial markers were assessed in floor and mattress dust and were related to cleanliness and allergic diseases. MEASUREMENTS AND MAIN RESULTS: Personal cleanliness was inversely related to bacterial compounds on floors and mattresses, whereas home cleanliness effectively reduced dust amount but not microbial markers. Exposure to muramic acid related to a lower prevalence of school-age asthma (adjusted odds ratio, 0.59 [95% confidence interval, 0.39; 0.90]). Mattress endotoxin in the first year of life was inversely associated with atopic sensitization (0.73 [0.56-0.96]) and asthma at school age (0.72 [0.55-0.95]). Despite the associations of dust parameters both with cleanliness and allergic health conditions, the development of allergies was not related to home and personal cleanliness. CONCLUSIONS: Bacterial exposure in house dust determined childhood asthma and allergies. Personal cleanliness, such as washing hands, and home cleanliness were objectively reflected by dust parameters in homes. However, neither personal nor home cleanliness was associated with a risk for asthma and allergies. Other microbial components in house dust not affected by personal hygiene are likely to play a role.
Assuntos
Asma/imunologia , Poeira , Hipótese da Higiene , Higiene , Poeira/análise , Poeira/imunologia , Endotoxinas/análise , Humanos , Hipersensibilidade/imunologia , Estilo de Vida , Ácidos Murâmicos/análise , Medição de RiscoRESUMO
Enterococcus faecalis is one of most important nosocomial and often multi-antibiotic resistant pathogens responsible for infections that are difficult to treat. Previously, a cell-wall polysaccharide termed diheteroglycan (DHG) was isolated and characterized as a promising vaccine candidate. However, the configuration of its lactic acid (LA) residue attached to the galactofuranoside unit was not assessed, although it influences conformation of DHG chain in terms of biological recognition and immune evasion. This study proves the Râ configuration of the LA residue by means of chemical analysis, investigation of intramolecular NMR nuclear Overhauser effects and molecular dynamics simulations of native DHG and corresponding R and S models, which were obtained by using pyranoside-into-furanoside rearrangement. As alternative treatment and prevention strategies for E.â faecalis are desperately needed, this discovery may offer the prospect of a synthetic vaccine to actively immunize patients at risk.
Assuntos
Parede Celular/química , Enterococcus faecalis/química , Polissacarídeos/química , Galactosídeos/química , Infecções por Bactérias Gram-Positivas/microbiologia , Humanos , Ácido Láctico/química , Conformação MolecularRESUMO
The O-polysaccharide (OPS, O-Ag) cap of LPS is a major virulence factor of Yersinia species and also serves as a receptor for the binding of lytic bacteriophage φR1-37. Currently, the OPS-based serotyping scheme for the Yersinia pseudotuberculosis complex includes 21 known O-serotypes that follow three distinct lineages: Y. pseudotuberculosis sensu stricto, Y. similis and the Korean group of strains. Elucidation of the Y. pseudotuberculosis complex OPS structures and characterization of the OPS genetics (altogether 18 O-serotypes studied thus far) allows a better understanding of the relationships among the various O serotypes and will facilitate the analysis of the evolutionary processes giving rise to new serotypes. Here we present the characterization of the OPS structure and gene cluster of Y. similis O:9. Bacteriophage φR1-37, which uses the Y. similis O:9 OPS as a receptor, also infects a number of Y. enterocolitica serotypes, including O:3, O:5,27, O:9 and O:50. The Y. similis O:9 OPS structure resembled none of the receptor structures of the Y. enterocolitica strains, suggesting that φR1-37 can recognize several surface receptors, thus promoting broad host specificity.
Assuntos
Polissacarídeos/biossíntese , Polissacarídeos/genética , Yersinia/genética , Yersinia/metabolismo , Bacteriófagos/efeitos dos fármacos , Metilação de DNA , DNA Bacteriano/genética , Família Multigênica , Polissacarídeos/química , Fatores de Virulência/química , Fatores de Virulência/genética , Yersinia/química , Yersinia enterocolitica/genéticaRESUMO
The O-specific polysaccharide (OPS) obtained by mild-acid degradation of the lipopolysaccharide from Aeromonas sobria strain Pt312 was studied by sugar and methylation analyses along with 1H and 13C NMR spectroscopy, including 2D 1H,1H COSY, TOCSY, NOESY, 1H-detected 1H,13C HSQC, and HMBC experiments. The sequence of the sugar residues was determined using 1H,1H NOESY and 1H,13C HMBC experiments. It was found that the OPS was built up of disaccharide repeating units composed of GlcpNAc and non-stoichiometrically O-acetylated Rhap residues, and had the structure.