Epithelial-derived interleukin-23 promotes oral mucosal immunopathology.

At mucosal surfaces, epithelial cells provide a structural barrier and an immune defense system. However, dysregulated epithelial responses can contribute to disease states. Here, we demonstrated that epithelial cell-intrinsic production of interleukin-23 (IL-23) triggers an inflammatory loop in the prevalent oral disease periodontitis.

: Biofilm Architecture and Age-Dependent Pleomorphy.

Round bodies in spirochete cultures have been a controversial subject since their description seven decades ago. We report the existence of round bodies (spherical cells) in cultures of , a spiral bacterium phylogenetically distant from spirochetes. Furthermore, when grown in biofilms, demonstrates a unique morphology known as cording, which has been previously described only in mycobacteria.

Effect of mechanically stimulated saliva on initial human dental biofilm formation.

This study evaluated the impact of mechanically stimulated saliva on initial bacterial colonization. Interaction between oral bacteria and both unstimulated and stimulated saliva was examined in vitro by laying labeled bacteria over SDS-PAGE-separated salivary proteins. The effects of chewing on in vivo biofilm, microbial composition, and spatial arrangement were examined in two human volunteers using an intraoral stent containing retrievable enamel chips.

Mechanisms by which Porphyromonas gingivalis evades innate immunity.

The oral cavity is home to unique resident microbial communities whose interactions with host immunity are less frequently studied than those of the intestinal microbiome. We examined the stimulatory capacity and the interactions of two oral bacteria, Porphyromonas gingivalis (P. gingivalis) and Fusobacterium nucleatum (F.

Interbacterial Adhesion Networks within Early Oral Biofilms of Single Human Hosts.

Specific interbacterial adhesion, termed coaggregation, is well established for three early colonizers of the plaque biofilm: streptococci, actinomyces, and veillonellae. However, little is known about interactions of other early colonizers and about the extent of interactions within the bacterial community from a single host. To address these gaps, subject-specific culture collections from two individuals were established using an intraoral biofilm retrieval device.

Aggregatibacter actinomycetemcomitans-induced hypercitrullination links periodontal infection to autoimmunity in rheumatoid arthritis.

A bacterial etiology of rheumatoid arthritis (RA) has been suspected since the beginnings of modern germ theory. Recent studies implicate mucosal surfaces as sites of disease initiation. The common occurrence of periodontal dysbiosis in RA suggests that oral pathogens may trigger the production of disease-specific autoantibodies and arthritis in susceptible individuals.

Cell Surface Glycoside Hydrolases of Streptococcus gordonii Promote Growth in Saliva.

Unlabelled: The growth of the oral commensal Streptococcus gordonii in saliva may depend on a number of glycoside hydrolases (GHs), including three cell wall-anchored proteins that are homologs of pneumococcal β-galactosidase (BgaA), β-N-acetylglucosaminidase (StrH), and endo-β-N-acetylglucosaminidase D (EndoD). In the present study, we introduced unmarked in-frame deletions into the corresponding genes of S. gordonii DL1, verified the presence (or absence) of the encoded proteins on the resulting mutant strains, and compared these strains with wild-type strain DL1 for growth and glycan foraging in saliva.

Differential Utilization of Basic Proline-Rich Glycoproteins during Growth of Oral Bacteria in Saliva.

Unlabelled: Although saliva is widely recognized as a primary source of carbon and nitrogen for growth of the dental plaque biofilm community, little is known about how different oral bacteria utilize specific salivary components. To address this question, 32 strains representing 16 genera commonly isolated from early plaque biofilms were compared for growth over two transfers in stimulated (by chewing Parafilm) whole saliva that was stabilized by heat treatment and dialysis. The cell densities, measured by quantitative PCR (qPCR), ranged from ∼1 × 10(6) to 1 × 10(7)/ml for strains of Streptococcus gordonii, Streptococcus oralis, and Streptococcus mitis and one strain of Streptococcus sanguinis Strains of Streptococcus mutans, Gemella haemolysans, and Granulicatella adiacens reached ∼1 × 10(5) to 1 × 10(6)/ml.

Composition and development of oral bacterial communities.

The oral bacterial microbiome encompasses approximately 700 commonly occurring phylotypes, approximately half of which can be present at any time in any individual. These bacteria are largely indigenous to the oral cavity; this limited habitat range suggests that interactions between the various phylotypes, and between the phylotypes and their environment, are crucial for their existence. Molecular cataloging has confirmed many basic observations on the composition of the oral microbiome that were formulated well before ribosomal RNA-based systematics, but the power and the scope of molecular taxonomy have resulted in the discovery of new phylotypes and, more importantly, have made possible a level of bacterial community analysis that was unachievable with classical methods.

Porphyromonas gingivalis promotes Th17 inducing pathways in chronic periodontitis.

In periodontitis, a common chronic inflammatory condition, gram-negative-rich bacterial biofilms trigger, in susceptible individuals, perpetuating inflammation that results in extensive tissue damage of tooth supporting structures. To delineate immune cell-dependent mechanisms whereby bacterial challenge drives persistent destructive inflammation in periodontitis and other inflammatory diseases, we studied involved tissues ex vivo and investigated host cell responses to the periodontal pathogen Porphyromonas gingivalis, in vitro. Diseased lesions were populated by abundant Th17 cells, linked to infection, chronic inflammation/autoimmunity and tissue pathology.

Oral multispecies biofilm development and the key role of cell-cell distance.

Growth of oral bacteria in situ requires adhesion to a surface because the constant flow of host secretions thwarts the ability of planktonic cells to grow before they are swallowed. Therefore, oral bacteria evolved to form biofilms on hard tooth surfaces and on soft epithelial tissues, which often contain multiple bacterial species. Because these biofilms are easy to study, they have become the paradigm of multispecies biofilms.

Supragingival and subgingival plaque: paradigm of biofilms.

Most microorganisms in nature live in multispecies communities attached to a substratum-biofilms. Within these communities, organismal interaction is spatiotemporally defined. Because biofilms exist at an interface, their environment is characterized by gradients of nutrients that encourage spatial and metabolic diversity within the population.

Shear-enhanced oral microbial adhesion.

Shear-enhanced adhesion, although not observed for fimbria-mediated adhesion of oral Actinomyces spp., was noted for Hsa-mediated adhesion of Streptococcus gordonii to sialic acid-containing receptors, an interaction implicated in the pathogenesis of infective endocarditis.

Characterization of a Streptococcus sp.-Veillonella sp. community micromanipulated from dental plaque.

Streptococci and veillonellae occur in mixed-species colonies during formation of early dental plaque. One factor hypothesized to be important in assembly of these initial communities is coaggregation (cell-cell recognition by genetically distinct bacteria). Intrageneric coaggregation of streptococci occurs when a lectin-like adhesin on one streptococcal species recognizes a receptor polysaccharide (RPS) on the partner species.

Pictures of microbiology -- the biofilm imaging facility under Dr. David C. White.

This contribution honoring David C. White (DC) summarizes the five years I interacted with him on a daily basis in his laboratory. Over this time we worked on many different projects all tied together by the unifying principle now recognized as central to bacterial life in nature: biofilms.

Use of quantum dot luminescent probes to achieve single-cell resolution of human oral bacteria in biofilms.

Oral biofilms are multispecies communities, and in their nascent stages of development, numerous bacterial species engage in interspecies interactions. Better insight into the spatial relationship between different species and how species diversity increases over time can guide our understanding of the role of interspecies interactions in the development of the biofilms. Quantum dots (QD) are semiconductor nanocrystals and have emerged as a promising tool for labeling and detection of bacteria.

Streptococcal receptor polysaccharides: recognition molecules for oral biofilm formation.

Background: Strains of viridans group streptococci that initiate colonization of the human tooth surface typically coaggregate with each other and with Actinomyces naeslundii, another member of the developing biofilm community. These interactions generally involve adhesin-mediated recognition of streptococcal receptor polysaccharides (RPS). The objective of our studies is to understand the role of these polysaccharides in oral biofilm development.

Autoinducer 2: a concentration-dependent signal for mutualistic bacterial biofilm growth.

4,5-Dihydroxy-2,3-pentanedione (DPD), a product of the LuxS enzyme in the catabolism of S-ribosylhomocysteine, spontaneously cyclizes to form autoinducer 2 (AI-2). AI-2 is proposed to be a universal signal molecule mediating interspecies communication among bacteria. We show that mutualistic and abundant biofilm growth in flowing saliva of two human oral commensal bacteria, Actinomyces naeslundii T14V and Streptococcus oralis 34, is dependent upon production of AI-2 by S.

Rapid succession within the Veillonella population of a developing human oral biofilm in situ.

Streptococci are the primary component of the multispecies oral biofilm known as supragingival dental plaque; they grow by fermentation of sugars to organic acids, e.g., lactic acid.

Molecular characterization of subject-specific oral microflora during initial colonization of enamel.

The initial microbial colonization of tooth surfaces is a repeatable and selective process, with certain bacterial species predominating in the nascent biofilm. Characterization of the initial microflora is the first step in understanding interactions among community members that shape ensuing biofilm development. Using molecular methods and a retrievable enamel chip model, we characterized the microbial diversity of early dental biofilms in three subjects.

Environmental influences on Actinobacillus actinomycetemcomitans biofilm formation.

Fresh clinical isolates of the periodontal pathogen Actinobacillus actinomycetemcomitans have an adherent, rough colony morphology that transforms into a minimally adherent, smooth colony phenotype during successive in vitro passage. The objectives of this study were: (1) to compare biofilm formation of the rough (RVs) and smooth variants (SVs) of several strains of A. actinomycetemcomitans grown under various environmental conditions and (2) to examine the dynamics of biofilm formation.