scholarly journals A Novel Exclusion Mechanism for Carbon Resource Partitioning in Aggregatibacter actinomycetemcomitans

2007 ◽  
Vol 189 (17) ◽  
pp. 6407-6414 ◽  
Author(s):  
Stacie A. Brown ◽  
Marvin Whiteley
Keyword(s):  
Oral Cavity ◽  
Aggregatibacter Actinomycetemcomitans ◽  
Aggressive Periodontitis ◽  
Carbon Utilization ◽  
Carbon Availability ◽  
Oral Bacterium ◽  
Carbon Substrates ◽  
Exclusion Mechanism ◽  
Slow Growing

ABSTRACT The bacterium Aggregatibacter actinomycetemcomitans is a common commensal of the human oral cavity and the putative causative agent of the disease localized aggressive periodontitis. A. actinomycetemcomitans is a slow-growing bacterium that possesses limited metabolic machinery for carbon utilization. This likely impacts its ability to colonize the oral cavity, where growth and community composition is mediated by carbon availability. We present evidence that in the presence of the in vivo relevant carbon substrates glucose, fructose, and lactate A. actinomycetemcomitans preferentially metabolizes lactate. This preference for lactate exists despite the fact that A. actinomycetemcomitans grows faster and obtains higher cell yields during growth with carbohydrates. The preference for lactate is mediated by a novel exclusion mechanism in which metabolism of lactate inhibits carbohydrate uptake. Coculture studies reveal that A. actinomycetemcomitans utilizes lactate produced by the oral bacterium Streptococcus gordonii, suggesting the potential for cross-feeding in the oral cavity.

scholarly journals Aggregatibacter actinomycetemcomitans: The virulence factors and relation to persistence biofilm formation

Biomedicine ◽  
2021 ◽  
Vol 40 (4) ◽  
pp. 429-435
Author(s):  
Syakir Syahiran ◽  
Wan Rohani Wan Taib ◽  
Norzawani Jaffar
Keyword(s):  
Oral Cavity ◽  
Virulence Factors ◽  
Tooth Loss ◽  
Periodontal Diseases ◽  
Aggregatibacter Actinomycetemcomitans ◽  
Aggressive Periodontitis ◽  
Essential Factor ◽  
Abiotic Surfaces ◽  
Functional Biology ◽  
Systemic Infections

Periodontitis is an infectious and inflammatory condition that is associated with subgingival biofilms in tooth-supporting tissues. Among the several hundred isolated organisms in the oral cavity, one of the most isolated bacteria from infected periodontal pockets are Aggregatibacter actinomycetemcomitans. It is a Gram-negative, facultative anaerobic bacillus that causes juvenile (localized aggressive periodontitis) and adolescent periodontal diseases. The development of biofilms is an essential factor in pathogenesis for A. actinomycetemcomitans. The early attachment of A. actinomycetemcomitans to abiotic surfaces relies on its protein-like fimbriae. This organism's ability to form tenacious biofilms can determine its survival and progression. A. actinomycetemcomitans, a pathogen not solely in periodontal but also involve in some systemic infections. This species has several virulence factors and genes that contribute to its oral cavity survival and, worst of all, cause bone resorption and tooth loss. Genetic diversity between the different A. actinomycetemcomitans isolates are great, and their ability to express and release virulence factors varies. In this review article, we discuss about the potential virulence factors and candidates genes for A. actinomycetemcomitans and their roles within periodontal disease by revealing their functional biology in facilitating attachment to oral surfaces, hindering protection of the host and causing inflammation and degradation of tissue.

scholarly journals Aggregatibacter actinomycetemcomitans colonization and persistence in a primate model

2019 ◽  
Vol 116 (44) ◽  
pp. 22307-22313 ◽  
Author(s):  
Senthil Kumar Velusamy ◽  
Vandana Sampathkumar ◽  
Narayanan Ramasubbu ◽  
Bruce J. Paster ◽  
Daniel H. Fine
Keyword(s):  
Aggregatibacter Actinomycetemcomitans ◽  
Aggressive Periodontitis ◽  
Microbial Interactions ◽  
Primate Model ◽  
Monkey Model ◽  
Oral Environment ◽  
Indigenous Microbiota ◽  
Weighted Network Analysis

Aggregatibacter actinomycetemcomitans is associated with aggressive periodontitis resulting in premature tooth loss in adolescents. Tooth adherence and biofilm persistence are prerequisites for survival in the oral domain. Here, using a rhesus monkey model, 16S rRNA sequencing, and weighted network analysis, we assessed colonization of A. actinomycetemcomitans variants and ascertained microbial interactions in biofilm communities. Variants in A. actinomycetemcomitans leukotoxin (ltx) were created, labeled, inoculated, and compared with their progenitor strain for in vivo colonization. Samples of tooth-related plaque were assessed for colonization at baseline and after debridement and inoculation of labeled strains. Null, minimal, and hyper-Ltx–producing strains were created and assessed for hydroxyapatite binding and biofilm formation in vitro. Ltx-hyperproducing strains colonized with greater prevalence and at higher levels than wild type or ltx mutants (P = 0.05). Indigenous and inoculated A. actinomycetemcomitans strains that attached were associated with lactate-producing species (i.e., Leptotrichia, Abiotrophia, and Streptoccocci). A. actinomycetemcomitans was found at 0.13% of the total flora at baseline and at 0.05% 4 wk after inoculation. In vivo data were supported by in vitro results. We conclude that hyper-Ltx production affords these strains with an attachment advantage providing a foothold for competition with members of the indigenous microbiota. Increased attachment can be linked to ltx gene expression and up-regulation of adherence-associated genes. Growth of attached A. actinomycetemcomitans in vivo was enhanced by lactate availability due to consorting species. These associations provide A. actinomycetemcomitans with the constituents required for its colonization and survival in the complex and competitive oral environment.

scholarly journals Aggregatibacter actinomycetemcomitans Cytolethal Distending Toxin Induces Apoptosis in Nonproliferating Macrophages by a Phosphatase-Independent Mechanism

2009 ◽  
Vol 77 (8) ◽  
pp. 3161-3169 ◽  
Author(s):  
Shira D. P. Rabin ◽  
Jared G. Flitton ◽  
Donald R. Demuth
Keyword(s):  
Phosphatase Activity ◽  
Specific Activity ◽  
Aggregatibacter Actinomycetemcomitans ◽  
Aggressive Periodontitis ◽  
Cytolethal Distending Toxin ◽  
U937 Cells ◽  
Active Site Residues ◽  
Induction Of Apoptosis ◽  
Induced Apoptosis

ABSTRACT Aggregatibacter actinomycetemcomitans strains that express cytolethal distending toxin (Cdt) are associated with localized aggressive periodontitis. However, the in vivo targets of Cdt in the human oral cavity have not been firmly established. Here, we demonstrate that A. actinomycetemcomitans Cdt kills proliferating and nonproliferating U937 monocytic cells at a comparable specific activity, approximately 1.5-fold lower than that against the Cdt-hypersensitive Jurkat T-cell line. Cdt functioned both as a DNase and a phosphatidylinositol 3-phosphate (PIP3) phosphatase, and these activities were distinguished by site-specific mutagenesis of the active site residues of CdtB. Using these mutants, we determined that the DNase activity of CdtB is required for cell cycle arrest and caspase-dependent induction of apoptosis in proliferating U937 cells. In contrast, Cdt holotoxin induced apoptosis by a mechanism independent of caspase- and apoptosis-inducing factor in nonproliferating U937 cells. Furthermore, apoptosis of nonproliferating U937 cells was unaffected by the Cdt mutant possessing reduced phosphatase activity or by the addition of a specific PIP3 phosphatase inhibitor, suggesting that the induction of apoptosis is independent of phosphatase activity. These results indicate that Cdt intoxication of proliferating and nonproliferating U937 cells occurs by distinct mechanisms and suggest that macrophages may also be potential in vivo targets of Cdt.

scholarly journals Human Saliva-Mediated Hydrolysis of Eugenyl-β-D-Glucoside and Fluorescein-di-β-D-Glucoside in In Vivo and In Vitro Models

Biomolecules ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 172
Author(s):  
Mariusz Dziadas ◽  
Adam Junka ◽  
Henryk Jeleń
Keyword(s):  
Oral Cavity ◽  
Control Sample ◽  
Rapid Test ◽  
Human Saliva ◽  
In Vitro Models ◽  
Microbial Hydrolysis ◽  
Amoxicillin Trihydrate ◽  
Potassium Clavulanate

Eugenyl-β-D-glucopyranoside, also referred to as Citrusin C, is a natural glucoside found among others in cloves, basil and cinnamon plants. Eugenol in a form of free aglycone is used in perfumeries, flavourings, essential oils and in medicinal products. Synthetic Citrusin C was incubated with human saliva in several in vitro models together with substrate-specific enzyme and antibiotics (clindamycin, ciprofloxacin, amoxicillin trihydrate and potassium clavulanate). Citrusin C was detected using liquid chromatography with tandem mass spectrometry (LC-MS/MS). Citrusin C was completely degraded only when incubated with substrate-specific A. niger glucosidase E.C 3.2.1.21 (control sample) and when incubated with human saliva (tested sample). The addition of antibiotics to the above-described experimental setting, stopped Citrusin C degradation, indicating microbiologic origin of hydrolysis observed. Our results demonstrate that Citrusin C is subjected to complete degradation by salivary/oral cavity microorganisms. Extrapolation of our results allows to state that in the human oral cavity, virtually all β-D-glucosides would follow this type of hydrolysis. Additionally, a new method was developed for an in vivo rapid test of glucosidase activity in the human mouth on the tongue using fluorescein-di-β-D-glucoside as substrate. The results presented in this study serve as a proof of concept for the hypothesis that microbial hydrolysis path of β-D-glucosides begins immediately in the human mouth and releases the aglycone directly into the gastrointestinal tract.

scholarly journals Biofilm formation in the lung contributes to virulence and drug tolerance of Mycobacterium tuberculosis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Poushali Chakraborty ◽  
Sapna Bajeli ◽  
Deepak Kaushal ◽  
Bishan Dass Radotra ◽  
Ashwani Kumar
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Immune System ◽  
Biofilm Formation ◽  
Antimycobacterial Activity ◽  
Drug Tolerance ◽  
Host Immune System ◽  
Tissue Sections ◽  
Slow Growing

AbstractTuberculosis is a chronic disease that displays several features commonly associated with biofilm-associated infections: immune system evasion, antibiotic treatment failures, and recurrence of infection. However, although Mycobacterium tuberculosis (Mtb) can form cellulose-containing biofilms in vitro, it remains unclear whether biofilms are formed during infection in vivo. Here, we demonstrate the formation of Mtb biofilms in animal models of infection and in patients, and that biofilm formation can contribute to drug tolerance. First, we show that cellulose is also a structural component of the extracellular matrix of in vitro biofilms of fast and slow-growing nontuberculous mycobacteria. Then, we use cellulose as a biomarker to detect Mtb biofilms in the lungs of experimentally infected mice and non-human primates, as well as in lung tissue sections obtained from patients with tuberculosis. Mtb strains defective in biofilm formation are attenuated for survival in mice, suggesting that biofilms protect bacilli from the host immune system. Furthermore, the administration of nebulized cellulase enhances the antimycobacterial activity of isoniazid and rifampicin in infected mice, supporting a role for biofilms in phenotypic drug tolerance. Our findings thus indicate that Mtb biofilms are relevant to human tuberculosis.

scholarly journals Melatonin: A Novel Indolamine in Oral Health and Disease

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
V. K. Chava ◽  
K. Sirisha
Keyword(s):  
Gastrointestinal Tract ◽  
Oral Health ◽  
Oral Cavity ◽  
Salivary Glands ◽  
In Vivo Studies ◽  
Systemic Level ◽  
A Cell ◽  
Health And Disease ◽  
Anti Oxidant

This paper attempts to summarise the findings accumulated within the last few years concerning the hormone of darkness “melatonin.” Based on its origin, from the pineal gland until recently it was portrayed exclusively as a hormone. Due to its lipophilic nature, it is accessible to every cell. Thus, in the classic sense it is a cell protector rather than a hormone. Recent studies, by Claustrat et al. (2005), detected few extrapineal sources of melatonin like retina, gastrointestinal tract, and salivary glands. Due to these sources, research by Cutando et al. (2007), is trying to explore the implications of melatonin in the oral cavity, in addition to its physiologic anti-oxidant, immunomodulatory and oncostatic functions at systemic level that may be receptor dependent or independent. Recently, certain in vivo studies by Shimozuma et al. (2011), detected the secretion of melatonin from salivary glands further emphasising its local activity. Thus, within our confines the effects of melatonin in the mouth are reviewed, adding a note on therapeutic potentials of melatonin both systemically and orally.

Regulation of cholesterol metabolism in a slow-growing hepatoma in vivo

1988 ◽  
Vol 960 (2) ◽  
pp. 131-138 ◽  
Author(s):  
Sandra K. Erickson ◽  
Allen D. Cooper ◽  
Graham F. Barnard ◽  
Christopher M. Havel ◽  
John A. Watson ◽  
...  
Keyword(s):  
Cholesterol Metabolism ◽  
Slow Growing

scholarly journals Genome Sequence of Aggregatibacter actinomycetemcomitans Serotype c Strain D11S-1

2009 ◽  
Vol 191 (23) ◽  
pp. 7378-7379 ◽  
Author(s):  
Casey Chen ◽  
Weerayuth Kittichotirat ◽  
Yan Si ◽  
Roger Bumgarner
Keyword(s):  
Genome Sequence ◽  
Complete Genome Sequence ◽  
Complete Genome ◽  
Aggregatibacter Actinomycetemcomitans ◽  
Aggressive Periodontitis ◽  
Etiological Agent ◽  
Subgingival Plaque

ABSTRACT Aggregatibacter actinomycetemcomitans is a major etiological agent of periodontitis. Here we report the complete genome sequence of serotype c strain D11S-1, which was recovered from the subgingival plaque of a patient diagnosed with generalized aggressive periodontitis.

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