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Molecular Oral Microbiology

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
Shanshan Liang, Hongyu Ren, Haiying Guo, Wenyan Xing, Chang Liu, Yaoting Ji, Han Jiang, Ping Zhang, Minquan 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 1st molars and inoculating with P...
May 13, 2018: Molecular Oral Microbiology
Ayumi Saeki, Masahiro Sugiyama, Akira Hasebe, Toshihiko Suzuki, Ken-Ichiro Shibata
The NLRP3 inflammasome, an intracellular sensor consisting of the NOD-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 (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
Rajendra P Settem, Kiyonobu Honma, Mira Shankar, Miaomiao Li, Michael LaMonte, Ding Xu, Robert J Genco, Richard W Browne, Ashu Sharma
The periodontal pathogen Tannerella forsythia has the unique ability to produce methylglyoxal (MGO) an electrophilic compound, which can covalently modify amino acid side chains and generate inflammatory adducts known as advanced glycation endproducts (AGEs). In periodontitis, the concentrations of gingival-crevicular fluid MGO increase, and correlate with the levels of T. forsythia load. However, the source of MGO and the extent to which MGO may contribute to periodontal inflammation has not been fully explored...
March 23, 2018: Molecular Oral Microbiology
Chan Yang, Jessica Scoffield, Ren Wu, Champion Deivanayagam, Jing Zou, Hui Wu
Streptococcus mutans and Candida albicans are frequently co-isolated from dental plaque of children with early childhood caries (ECC), and only rarely found in non-ECC children, suggesting that these species interact in a manner that contribute to the pathogenesis of ECC. Previous studies have demonstrated that glucans produced by S. mutans are crucial for promoting biofilm formation and cariogenicity with C. albicans; however, it is unclear how non-glucan S. mutans biofilm factors contribute to increased biofilm formation in the presence of C...
March 23, 2018: Molecular Oral Microbiology
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
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
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
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
H M Fletcher
No abstract text is available yet for this article.
April 2018: Molecular Oral Microbiology
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
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
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
B Valdebenito, P O Tullume-Vergara, W González, J Kreth, R A Giacaman
During dental caries, the dental biofilm modifies the composition of the hundreds of involved bacterial species. Changing environmental conditions influence competition. A pertinent model to exemplify the complex interplay of the microorganisms in the human dental biofilm is the competition between Streptococcus sanguinis and Streptococcus mutans. It has been reported that children and adults harbor greater numbers of S. sanguinis in the oral cavity, associated with caries-free teeth. Conversely, S. mutans is predominant in individuals with a high number of carious lesions...
April 2018: Molecular Oral Microbiology
S Bloch, S Zwicker, N Bostanci, Å Sjöling, E A Boström, G N Belibasakis, C Schäffer
The oral pathogen Tannerella forsythia possesses a unique surface (S-) layer with a complex O-glycan containing a bacterial sialic acid mimic in the form of either pseudaminic acid or legionaminic acid at its terminal position. We hypothesize that different T. forsythia strains employ these stereoisomeric sugar acids for interacting with the immune system and resident host tissues in the periodontium. Here, we show how T. forsythia strains ATCC 43037 and UB4 displaying pseudaminic acid and legionaminic acid, respectively, and selected cell surface mutants of these strains modulate the immune response in monocytes and human oral keratinocytes (HOK) using a multiplex immunoassay...
April 2018: Molecular Oral Microbiology
M Rapala-Kozik, O Bochenska, D Zajac, J Karkowska-Kuleta, M Gogol, M Zawrotniak, A Kozik
The increased incidence of severe disseminated infections caused by the opportunistic yeast-like fungi Candida spp. highlights the urgent need for research into the major virulence factors of these pathogens-extracellular aspartic proteinases of the candidapepsin and yapsin families. Classically, these enzymes were considered to be generally destructive factors that damage host tissues and provide nutrients for pathogen propagation. However, in recent decades, novel and more specific functions have been suggested for extracellular candidal proteinases...
April 2018: Molecular Oral Microbiology
J C Robinson, N Rostami, J Casement, W Vollmer, A H Rickard, N S Jakubovics
Biofilm formation and cell-cell sensing by the pioneer dental plaque colonizer Streptococcus gordonii are dependent upon arginine. This study aimed to identify genetic factors linking arginine-dependent responses and biofilm formation in S. gordonii. Isogenic mutants disrupted in genes required for the biosynthesis or catabolism of arginine, or for arginine-dependent gene regulation, were screened for their ability to form biofilms in a static culture model. Biofilm formation by a knockout mutant of arcR, encoding an arginine-dependent regulator of transcription, was reduced to < 50% that of the wild-type whereas other strains were unaffected...
April 2018: Molecular Oral Microbiology
T Hoppe, V Göser, D Kraus, R Probstmeier, M Frentzen, M Wenghoefer, S Jepsen, J Winter
The present in vitro study examines molecular processes that are relevant during bone homeostasis after Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis infection with a focus on the differentiation level of osteoblasts. Regenerative processes are often hindered by the recurrence of bacterial infections, which can ultimately provoke a severe destruction of bone tissue. To obtain more detailed insights into such a complex scenario, we have used undifferentiated MG63 osteoblast-like cells as an experimental paradigm to examine the impact of two oral pathogens, A...
April 2018: Molecular Oral Microbiology
C J Beall, E M Mokrzan, A L Griffen, E J Leys
A novel bacterium was isolated from the subgingival plaque of a patient with periodontal disease. Bacterial strain BA112T is a facultative Gram-positive coccus. It metabolizes alanine, arginine, glycine, histidine, leucine, proline, serine and tyrosine, but does not appear to use carbohydrates. Urease, esculin, indole, catalase and nitrate reduction tests were all negative. Major cellular fatty acids were C18:0 , C12:0 , C16:0 , C18:1 w9c and C20:0 . The genome was sequenced and is 2.4 Mbp in length and has 64% GC content...
February 2018: Molecular Oral Microbiology
Y Dou, H Rutanhira, X Chen, A Mishra, C Wang, H M Fletcher
In Porphyromonas gingivalis, the protein PG1660, composed of 174 amino acids, is annotated as an extracytoplasmic function (ECF) sigma factor (RpoE homologue-σ24). Because PG1660 can modulate several virulence factors and responds to environmental signals in P. gingivalis, its genetic properties were evaluated. PG1660 is co-transcribed with its downstream gene PG1659, and the transcription start site was identified as adenine residue 54-nucleotides upstream of the ATG translation start codon. In addition to binding its own promoter, using the purified rPG1660 and RNAP core enzyme from Escherichia coli with the PG1660 promoter DNA as template, the function of PG1660 as a sigma factor was demonstrated in an in vitro transcription assay...
February 2018: Molecular Oral Microbiology
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