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Molecular Oral Microbiology

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https://www.readbyqxmd.com/read/30007055/porphyromonas-gingivalis-inhibits-m2-activation-of-macrophages-by-suppressing-%C3%AE-ketoglutarate-production-in-mice
#1
Shihui Yu, Luyang Ding, Dongyu Liang, Lijun Luo
Reprograming of metabolic pathways is critical in governing the polarization of macrophages into classical pro-inflammatory M1 or alternative anti-inflammatory M2 phenotypes in metabolic diseases, such as diabetes. Porphyromonas gingivalis (P. gingivalis), a keystone pathogen of periodontitis, causes an imbalance in M1/M2 activation, resulting in a hyper-inflammatory environment that promotes the pathogenesis of periodontitis. However, whether P. gingivalis infection modulates metabolic pathways to alter macrophage polarization remains unclear...
July 14, 2018: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/29968346/antibiotics-alter-the-window-of-competence-for-natural-transformation-in-streptococci
#2
Kjersti Sturød, Gabriela Salvadori, Roger Junges, Fernanda Petersen
Streptococcus pneumoniae transformation occurs within a short competence window, during which the alternative sigma factor X (SigX) is activated to orchestrate the expression of genes allowing extracellular DNA uptake and recombination. Importantly, antibiotic stress promotes transcriptional changes that may affect more than 20% of the S. pneumoniae genome, including competence genes. These can be activated or repressed, depending on the antibiotic agent. For most antibiotics, however, it remains unknown whether transcriptional effects on competence translate into altered transformability...
July 2, 2018: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/29939498/transcriptome-analysis-of-porphyromonas-gingivalis-and-acinetobacter-baumannii-in-polymicrobial-communities
#3
Daniel P Miller, Qian Wang, Aaron Weinberg, Richard J Lamont
Acinetobacter baumannii is a nosocomial, opportunistic pathogen that causes several serious conditions such as meningitis, septicemia, endocarditis and pneumonia. It can be found in the oral biofilm, which may be a reservoir for pneumonia and chronic obstructive pulmonary disease. Subgingival colonization by A. baumannii is associated with chronic and aggressive periodontitis as well as refractory periodontal disease. Porphyromonas gingivalis, a keystone periodontal pathogen localized to subgingival plaque, is also implicated in several chronic conditions including aspiration pneumonia...
June 25, 2018: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/29897662/live-and-let-die-hydrogen-peroxide-production-by-the-commensal-flora-and-its-role-in-maintaining-a-symbiotic-microbiome
#4
REVIEW
Sylvio Redanz, Xingqun Cheng, Rodrigo A Giacaman, Carmen S Pfeifer, Justin Merritt, Jens Kreth
The majority of commensal oral streptococci are able to generate hydrogen peroxide (H2 O2 ) during aerobic growth, which can diffuse through the cell membrane and inhibit competing species in close proximity. Competing H2 O2 production is mainly dependent upon the pyruvate oxidase SpxB, and to a lesser extent the lactate oxidase LctO, both of which are important for energy generation in aerobic environments. Several studies point to a broad impact of H2 O2 production in the oral environment, including a potential role in biofilm homeostasis, signaling, and interspecies interactions...
June 13, 2018: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/29888871/deficiency-of-brpa-in-streptococcus-mutans-reduces-virulence-in-rat-caries-model
#5
Zezhang T Wen, Kathleen Scott-Anne, Sumei Liao, Arpan De, Meng Luo, Christopher Kovacs, Brendaliz S Narvaez, Roberta C Faustoferri, Qingzhao Yu, Christopher M Taylor, Robert G Quivey
Our recent studies have shown that BrpA in Streptococcus mutans plays a critical role in cell envelope biogenesis, stress responses, and biofilm formation. In this study, a 10-species consortium was used to assess how BrpA deficiency influences the establishment, persistence, and competitiveness of S. mutans during growth in a community under conditions typical of the oral cavity. Results showed that, like the wild-type, the brpA mutant was able to colonize and establish on the surfaces tested. Relative to the wild-type, however, the brpA mutant had a reduced ability to persist and grow in the 10-species consortium (P < ...
June 11, 2018: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/29847019/potential-role-for-streptococcus-gordonii-derived-hydrogen-peroxide-in-haem-acquisition-by-porphyromonas-gingivalis
#6
Jason L Brown, Edwin Yates, Marcin Bielecki, Teresa Olczak, John W Smalley
Streptococcus gordonii, an accessory pathogen and early coloniser of plaque, co-aggregates with many oral species including Porphyromonas gingivalis. It causes α-haemolysis on blood agar, a process mediated by H2 O2 and thought to involve concomitant oxidation of haemoglobin (Hb). P. gingivalis has a growth requirement for haem which is acquired mainly from Hb. The paradigm for Hb haem acquisition involves the initial oxidation of oxyhaemoglobin (oxyHb) to methaemoglobin (metHb), followed by haem release and extraction via the actions of K-gingipain protease and/or the HmuY haemophore-like protein...
May 30, 2018: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/29768735/tobacco-induced-suppression-of-the-vascular-response-to-dental-plaque
#7
Nurcan Buduneli, David A Scott
Cigarette smoking presents oral health professionals with a clinical and research conundrum: reduced periodontal vascular responsiveness to the oral biofilm accompanied by increased susceptibility to destructive periodontal diseases. This presents a significant problem, hampering diagnosis and complicating treatment planning. The aim of this review is to summarize contemporary hypotheses that help explain mechanistically the phenomenon of a suppressed bleeding response to dysbiotic plaque in the periodontia of smokers...
May 16, 2018: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/29754448/periodontal-infection-with-porphyromonas-gingivalis-induces-preterm-birth-and-lower-birth-weight-in-rats
#8
S Liang, H Ren, H Guo, W Xing, C Liu, Y Ji, H Jiang, P Zhang, M Du
Preterm birth (PTB), accompanied by low birth weight (LBW) or not, is a syndrome with tremendous risk factors and long-term health consequences for children. In recent decades, overwhelming studies have shown that periodontitis contributes to prematurity and LBW. This study was conducted to determine the link between maternal periodontitis and the pathogenesis of PTB and/or LBW through a rat infection model induced by Porphyromonas gingivalis, an important periodontopathic bacterium. The murine model was established by surgically ligating the left mandibular first molars and inoculating with P...
May 13, 2018: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/29682880/activation-of-nlrp3-inflammasome-in-macrophages-by-mycoplasmal-lipoproteins-and-lipopeptides
#9
A Saeki, M Sugiyama, A Hasebe, T Suzuki, K Shibata
The NLRP3 inflammasome, an intracellular sensor consisting of the nucleotide-binding oligomerization domain-like receptor family, pyrin domain containing 3 (NLRP3), the adaptor protein apoptosis-associated speck-like protein containing a caspase-recruitment domain (ASC), and procaspase-1, plays critical roles in host defense against microbial pathogens by inducing production of interleukin-1β (IL-1β) and IL-18. Mycoplasma salivarium and Mycoplasma pneumoniae cells activated murine bone marrow-derived macrophages (BMMs) to induce production of IL-1α, IL-1β, and IL-18...
April 23, 2018: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/29524318/whole-genome-sequence-and-phenotypic-characterization-of-a-cbm-serotype-e-strain-of-streptococcus-mutans
#10
A Avilés-Reyes, I A Freires, J K Kajfasz, D Barbieri, J H Miller, J A Lemos, J Abranches
We report the whole genome sequence of the serotype e Cbm+ strain LAR01 of Streptococcus mutans, a dental pathogen frequently associated with extra-oral infections. The LAR01 genome is a single circular chromosome of 2.1 Mb with a GC content of 36.96%. The genome contains 15 phosphotransferase system gene clusters, seven cell wall-anchored (LPxTG) proteins, all genes required for the development of natural competence and genes coding for mutacins VI and K8. Interestingly, the cbm gene is genetically linked to a putative type VII secretion system that has been found in Mycobacteria and few other Gram-positive bacteria...
June 2018: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/29498487/plasminogen-binding-and-degradation-by-treponema-denticola-identification-of-the-plasminogen-binding-interface-on-the-fhbb-protein
#11
B K Tegels, L D Oliver, D P Miller, R T Marconi
Treponema denticola is a proteolytic-anaerobic spirochete whose abundance in the subgingival crevice correlates with periodontal disease severity. Treponema denticola evades serum-mediated killing through the binding of factor H (FH), a negative regulator of the complement system. The T. denticolaFH receptor has been identified as FhbB, an 11.4kDa immunodominant lipoprotein. Three distinct subfamilies of FhbB proteins have been delineated and designated as FhbB1, FhbB2 and FhbB3. In this study we demonstrate that all FhbB variants bind human plasminogen (Plg)...
June 2018: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/29498485/in-vivo-expression-of-proteases-and-protease-inhibitor-a-serpin-by-periodontal-pathogens-at-teeth-and-implants
#12
M Eckert, D Mizgalska, A Sculean, J Potempa, A Stavropoulos, S Eick
Porphyromonas gingivalis and Tannerella forsythia secrete proteases, gingipains and KLIKK-proteases. In addition, T. forsythia produces a serpin (miropin) with broad inhibitory spectrum. The aim of this pilot study was to determine the level of expression of miropin and individual proteases in vivo in periodontal and peri-implant health and disease conditions. Biofilm and gingival crevicular fluid (GCF)/ peri-implant sulcular fluid (PISF) samples were taken from healthy tooth and implant sites (n = 10), gingivitis and mucositis sites (n = 12), and periodontitis and peri-implantitis sites (n = 10)...
June 2018: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/29360244/historical-aspects-of-studies-on-roles-of-the-inflammasome-in-the-pathogenesis-of-periodontal-diseases
#13
REVIEW
K Shibata
The proinflammatory cytokine interleukin-1β (IL-1β) is produced as inactive proIL-1β and then processed by caspase-1 to become active. In 2002, it was demonstrated that the intracellular multiprotein complex known as the inflammasome functions as a molecular platform to trigger activation of caspase-1. Inflammasomes are known to function as intracellular sensors for a broad spectrum of various pathogen-associated and damage-associated molecular patterns. In 1985, it was demonstrated that Porphyromonas gingivalis, a representative bacterium causing chronic periodontitis, induces IL-1 production by murine peritoneal macrophages...
June 2018: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/29327482/streptococcus-oralis-maintains-homeostasis-in-oral-biofilms-by-antagonizing-the-cariogenic-pathogen-streptococcus-mutans
#14
T Thurnheer, G N Belibasakis
Bacteria residing in oral biofilms live in a state of dynamic equilibrium with one another. The intricate synergistic or antagonistic interactions between them are crucial for determining this balance. Using the six-species Zürich "supragingival" biofilm model, this study aimed to investigate interactions regarding growth and localization of the constituent species. As control, an inoculum containing all six strains was used, whereas in each of the further five inocula one of the bacterial species was alternately absent, and in the last, both streptococci were absent...
June 2018: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/29319934/identification-and-functional-characterization-of-type-ii-toxin-antitoxin-systems-in-aggregatibacter-actinomycetemcomitans
#15
B Schneider, W Weigel, M Sztukowska, D R Demuth
Type II toxin/antitoxin (TA) systems contribute to the formation of persister cells and biofilm formation for many organisms. Aggregatibacter actinomycetemcomitans thrives in the complex oral microbial community subjected to continual environmental flux. Little is known regarding the presence and function of type II TA systems in this organism or their contribution to adaptation and persistence in the biofilm. We identified 11 TA systems that are conserved across all seven serotypes of A. actinomycetemcomitans and represent the RelBE, MazEF and HipAB families of type II TA systems...
June 2018: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/29314782/chemotherapy-induced-oral-mucositis-and-associated-infections-in-a-novel-organotypic-model
#16
T Sobue, M Bertolini, A Thompson, D E Peterson, P I Diaz, A Dongari-Bagtzoglou
Oral mucositis is a common side effect of cancer chemotherapy, with significant adverse impact on the delivery of anti-neoplastic treatment. There is a lack of consensus regarding the role of oral commensal microorganisms in the initiation or progression of mucositis because relevant experimental models are non-existent. The goal of this study was to develop an in vitro mucosal injury model that mimics chemotherapy-induced mucositis, where the effect of oral commensals can be studied. A novel organotypic model of chemotherapy-induced mucositis was developed based on a human oral epithelial cell line and a fibroblast-embedded collagen matrix...
June 2018: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/29461020/porphyromonas-gingivalis-the-gift-of-community-involvement
#17
EDITORIAL
H M Fletcher
No abstract text is available yet for this article.
April 2018: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/29290101/the-competence-system-of-streptococcus-anginosus-and-its-use-for-genetic-engineering
#18
R Bauer, S Mauerer, A Grempels, B Spellerberg
Streptococcus anginosus is considered a human commensal but improvements in species identification in recent years have highlighted its role as an emerging pathogen. However, our knowledge about the pathogenicity mechanisms in this species is scarce. One reason for this is the lack of published genetic manipulation techniques in the S. anginosus group. To establish a novel mutation technique we investigated the competence system of S. anginosus and created a Cre-recombinase-based mutation method that allows the generation of markerless gene deletions in S...
April 2018: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/29284195/extracellular-matrix-influence-in-streptococcus-mutans-gene-expression-in-a-cariogenic-biofilm
#19
E J Florez Salamanca, M I Klein
Caries etiology is biofilm-diet-dependent. Biofilms are highly dynamic and structured microbial communities enmeshed in a three-dimensional extracellular matrix. The study evaluated the expression dynamics of Streptococcus mutans genes associated with exopolysaccharides (EPS) (gtfBCD, gbpB, dexA), lipoteichoic acids (LTA) (dltABCD, SMU_775c) and extracellular DNA (eDNA) (lytST, lrgAB, ccpA) during matrix development within a mixed-species biofilm of S. mutans, Actinomyces naeslundii and Streptococcus gordonii...
April 2018: Molecular Oral Microbiology
https://www.readbyqxmd.com/read/29247483/peptidoglycan-synthesis-in-tannerella-forsythia-scavenging-is-the-modus-operandi
#20
REVIEW
A Ruscitto, A Sharma
Tannerella forsythia is a Gram-negative oral pathogen strongly associated with periodontitis. This bacterium has an absolute requirement for exogenous N-acetylmuramic acid (MurNAc), an amino sugar that forms the repeating disaccharide unit with amino sugar N-acetylglucosamine (GlcNAc) of the peptidoglycan backbone. In silico genome analysis indicates that T. forsythia lacks the key biosynthetic enzymes needed for the de novo synthesis of MurNAc, and so relies on alternative ways to meet its requirement for peptidoglycan biosynthesis...
April 2018: Molecular Oral Microbiology
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