The hemidesmosomal plaque

To examine whether constituent proteins of hemidesmosomal structures can be used as markers for certain pathways of epithelial differentiation we have examined the occurrence of the major M- approximately 230,000 plaque protein, the "bullous pemphigoid" (BP) antigen. Several bovine, rat and human tissues and bovine cell culture lines were examined, using different human autoantibody preparations in immunocytochemistry and immunoblotting. We report that this protein, also unequivocally identified by cDNA cloning from expression libraries and DNA sequencing, occurs not only in different stratified epithelia but also, apparently always in hemidesmosomal structures, in urothelium of bladder and the complex epithelia of trachea, bronchus and several glands, notably myoepithelium-containing skin glands, the mammary gland and salivary glands. The protein is absent, however, in all single-layered epithelia and in several tissues reported to have subplasmalemmal densities structurally similar to hemidesmosomes, such as Purkinje fibers of heart, meninges and perineuria. A mammary-gland-derived epithelial cell line (BMGE + H) is particularly rich in hemidesmosomes. This has been used to study the endocytotic uptake of hemidesmosome-containing plasma membrane domains into cytoplasmic vesicles upon detachment of cell sheets during treatment with dispase, a proteolytic enzyme. We propose to use the Mr- approximately 230,000 plaque protein as a marker selective for certain subsets of epithelial cell types and epithelium-derived tumors in studies of fetal and tumor development, including differentiation diagnosis of carcinomas.     

Dental bacterial plaque

The literature on the subject of dental bacterial plaque is extensive. In spite of considerable research, the mode of its formation together with the variability in bacterial content requires further clarification. Mechanical methods of plaque control are effective but limited in a population sense. Of the numerous chemotherapeutic agents in plaque control, chlorhexidin appears the most effective.     

Dental plaque formation

Dental plaque is a complex biofilm that accumulates on the hard tissues (teeth) in the oral cavity. Although over 500 bacterial species comprise plaque, colonization follows a regimented pattern with adhesion of initial colonizers to the enamel salivary pellicle followed by secondary colonization through interbacterial adhesion. A variety of adhesins and molecular interactions underlie these adhesive interactions and contribute to plaque development and ultimately to diseases such as caries and periodontal disease.     

Atherosclerotic plaque development

Atherosclerosis is now recognized as an inflammatory/immunomodulatory reaction to the presence of oxidized low-density lipoproteins within the arterial wall, often times in the setting of such risk factors as family history, hypercholesterolemia, high blood pressure, diabetes mellitus and smoking. The progression to high-risk lesions such as thin-fibrous cap atheromas results in an increased risk of sudden death, acute myocardial infarction and ischemic stroke. The interplay of macrophages, T lymphocytes and mast cells play a central role in both the development but more importantly in the progression of coronary and carotid artery disease to high-risk phenotypes.     

A novel workflow combining plaque imaging,plaque and plasma proteomics identifies biomarkers of human coronary atherosclerotic plaque disruption

Background

Atherosclerotic plaque rupture is the culprit event which underpins most acute vascular syndromes such as acute myocardial infarction. Novel biomarkers of plaque rupture could improve biological understanding and clinical management of patients presenting with possible acute vascular syndromes but such biomarker(s) remain elusive. Investigation of biomarkers in the context of de novo plaque rupture in humans is confounded by the inability to attribute the plaque rupture as the source of biomarker release, as plaque ruptures are typically associated with prompt down-stream events of myocardial necrosis and systemic inflammation.

Methods

We developed a novel approach to identify potential biomarkers of plaque rupture by integrating plaque imaging, using optical coherence tomography, with both plaque and plasma proteomic analysis in a human model of angioplasty-induced plaque disruption.

Results

We compared two pairs of coronary plaque debris, captured by a FilterWire Device, and their corresponding control samples and found matrix metalloproteinase 9 (MMP9) to be significantly enriched in plaque. Plaque contents, as defined by optical coherence tomography, affect the systemic changes of MMP9. Disruption of lipid-rich plaque led to prompt elevation of plasma MMP9, whereas disruption of non-lipid-rich plaque resulted in delayed elevation of plasma MMP9. Systemic MMP9 elevation is independent of the associated myocardial necrosis and systemic inflammation (measured by Troponin I and C-reactive protein, respectively). This information guided the selection of a subset of subjects of for further label free proteomics analysis by liquid chromatography tandem mass spectrometry (LC–MS/MS). We discovered five novel, plaque-enriched proteins (lipopolysaccharide binding protein, Annexin A5, eukaryotic translocation initiation factor, syntaxin 11, cytochrome B5 reductase 3) to be significantly elevated in systemic circulation at 5 min after plaque disruption.

Conclusion

This novel approach for biomarker discovery in human coronary artery plaque disruption can identify new biomarkers related to human coronary artery plaque composition and disruption.

     

Optimizing bacteriophage plaque fecundity

Bacteriophages (phages), the viruses of bacteria, form visible lesions within bacterial lawns (called plaques), which are employed ubiquitously in phage isolation and characterization. Plaques also can serve as models for phage population growth within environments that display significant spatial structure, e.g. soils, sediments, animal mucosal tissue, etc. Furthermore, phages growing within plaques, in experimental evolution studies, may become adapted to novel conditions, may be selected for faster expansion, or may evolve toward producing more virions per plaque. Here, we examine the evolution of the latter, greater plaque fecundity, considering especially tradeoffs between phage latent period and phage burst size. This evolution is interesting because genetically lengthening latent periods, as seen with phage lysis-timing mutants, should increase phage burst sizes, as more time is available for phage-progeny maturation during infection. Genetically shortening latent periods, however, is a means toward producing larger phage plaques since phage virions then can spend more time diffusing rather than infecting. With these larger plaques more bacteria become phage infected, resulting in more phage bursts. Given this conflict between latent period's impact on per-plaque burst number versus per-infection burst size, and based on analysis of existing models of plaque expansion, we provide two assertions. First, latent periods that optimize plaque fecundity are longer (e.g. at least two-fold longer) than latent periods that optimize plaque size (or that optimize phage population growth within broth). Second, if increases in burst size can contribute to plaque size (i.e. larger plaques with larger bursts), then latent-period optima that maximize plaque fecundity should be longer still. As a part of our analysis, we provide a means for predicting latent-period optima-for maximizing either plaque size or plaque fecundity-which is based on knowledge of only phage eclipse period and the relative contribution of phage burst size versus latent period toward plaque size.     

The kinetics of hemolytic plaque formation. IV. IgM plaque inhibition.

An analysis of the inhibition of hemolytic plaques formed against IgM antibodies is presented. The starting point is the equations of DeLisi &; Bell (1974) which describe the kinetics of plaque growth, and DeLisi &; Goldstein (1975) which describe inhibition of IgG plaques. However, the physical chemical models which were used previously to describe IgG inhibition data are shown to be inadequate for describing the characteristics of IgM inhibition curves. Moreover, it is shown that the experimental results place severe restrictions on the possible choices of physical chemical models for IgM upon which to base the calculations. It is argued that in order to account even qualitatively for all the data, one must assume (1) a very restricted motion of IgMs about the Fab hinge region and (2) a very narrow secretion rate distribution of IgM by antibody secreting cells.     

Dental plaque as a biofilm

Dental plaque is the diverse microbial community found on the tooth surface embedded in a matrix of polymers of bacterial and salivary origin. Once a tooth surface is cleaned, a conditioning film of proteins and glycoproteins is adsorbed rapidly to the tooth surface. Plaque formation involves the interaction between early bacterial colonisers and this film (the acquired enamel pellicle). To facilitate colonisation of the tooth surface, some receptors on salivary molecules are only exposed to bacteria once the molecule is adsorbed to a surface. Subsequently, secondary colonisers adhere to the already attached early colonisers (co-aggregation) through specific molecular interactions. These can involve protein-protein or carbohydrate-protein (lectin) interactions, and this process contributes to determining the pattern of bacterial succession. As the biofilm develops, gradients in biologically significant factors develop, and these permit the co-existence of species that would be incompatible with each other in a homogeneous environment. Dental plaque develops naturally, but it is also associated with two of the most prevalent diseases affecting industrialised societies (caries and periodontal diseases). Future strategies to control dental plaque will be targeted to interfering with the formation, structure and pattern of development of this biofilm.     

Molecular mechanisms of plaque instability

PURPOSE OF REVIEW: Coronary artery thrombosis superimposed on a disrupted atherosclerotic plaque initiates abrupt arterial occlusion and is the proximate event responsible for 60-80% cases of acute coronary syndromes. This article provides a concise update on the evolving concepts in the pathophysiology of plaque rupture and thrombosis. RECENT FINDINGS: Over the past several years, the critical role of plaque composition rather than plaque size or stenosis severity, in plaque rupture and thrombosis have been recognized. The necrotic lipid core and plaque inflammation appear to be key factors. Extracellular matrix loss in the fibrous cap, a prelude to rupture, is attributed to matrix degrading enzymes as well as to death of matrix synthesizing smooth muscle cells; inflammation appears to play a critical role in both these processes. Inflammatory cell derived tissue factor is a key contributor to plaque thrombogenicity. Inflammation has also been implicated in plaque neovascularity, intraplaque hemorrhage and plaque expansion. Recent observations have also highlighted the important modulatory role of immune system in atherosclerosis and plaque composition. SUMMARY: Improved understanding of mechanisms causing plaque instability should provide novel insights into prevention of athero-thrombotic cardiovascular events.     

Denitrification in human dental plaque

Background  

Microbial denitrification is not considered important in human-associated microbial communities. Accordingly, metabolic investigations of the microbial biofilm communities of human dental plaque have focused on aerobic respiration and acid fermentation of carbohydrates, even though it is known that the oral habitat is constantly exposed to nitrate (NO₃ ^-) concentrations in the millimolar range and that dental plaque houses bacteria that can reduce this NO₃ ^- to nitrite (NO₂ ^-).     

Amoxycillin-resistant streptococci in dental plaque

This investigation was undertaken to study the prevalence of amoxycillin-resistant oral streptococci in normal healthy patients and patients with a cardiac condition, susceptible to infective endocarditis. Samples of supragingival dental plaque were collected from two test groups, children with congenital heart disease and adults with a history of rheumatic fever, and two control groups comprising normal healthy children and normal healthy adults. Bacteria from these samples were grown on a medium selective for oral streptococci, as well as on the same medium containing known concentrations of amoxycillin. The results indicate that a high percentage of rheumatic heart patients and children with congenital heart disease harboured amoxycillin-resistant oral streptococci. The level of amoxycillin resistance in the plaque of adults with rheumatic heart disease was significantly greater than in that of normal adults. In view of the high percentage of patients at risk harbouring amoxycillin-resistant streptococci, it is important that the individual clinical situation be monitored. Perhaps antibiotic sensitivity tests should be performed to select an appropriate antibiotic for prophylaxis of infective endocarditis.     

Carotid plaque age is a feature of plaque stability inversely related to levels of plasma insulin

Background

The stability of atherosclerotic plaques determines the risk for rupture, which may lead to thrombus formation and potentially severe clinical complications such as myocardial infarction and stroke. Although the rate of plaque formation may be important for plaque stability, this process is not well understood. We took advantage of the atmospheric ¹⁴C-declination curve (a result of the atomic bomb tests in the 1950s and 1960s) to determine the average biological age of carotid plaques.

Methodology/Principal Finding

The cores of carotid plaques were dissected from 29 well-characterized, symptomatic patients with carotid stenosis and analyzed for ¹⁴C content by accelerator mass spectrometry. The average plaque age (i.e. formation time) was 9.6±3.3 years. All but two plaques had formed within 5–15 years before surgery. Plaque age was not associated with the chronological ages of the patients but was inversely related to plasma insulin levels (p = 0.0014). Most plaques were echo-lucent rather than echo-rich (2.24±0.97, range 1–5). However, plaques in the lowest tercile of plaque age (most recently formed) were characterized by further instability with a higher content of lipids and macrophages (67.8±12.4 vs. 50.4±6.2, p = 0.00005; 57.6±26.1 vs. 39.8±25.7, p<0.0005, respectively), less collagen (45.3±6.1 vs. 51.1±9.8, p<0.05), and fewer smooth muscle cells (130±31 vs. 141±21, p<0.05) than plaques in the highest tercile. Microarray analysis of plaques in the lowest tercile also showed increased activity of genes involved in immune responses and oxidative phosphorylation.

Conclusions/Significance

Our results show, for the first time, that plaque age, as judge by relative incorporation of ¹⁴C, can improve our understanding of carotid plaque stability and therefore risk for clinical complications. Our results also suggest that levels of plasma insulin might be involved in determining carotid plaque age.     

Reduction in plaque size and reduction in plaque number as differing indices of influenza virus-antibody reactions

Jahiel, R. I. (Cornell University Medical College, New York, N.Y.), and E. D. Kilbourne. Reduction in plaque size and reduction in plaque number as differing indices of influenza virus-antibody reactions. J. Bacteriol. 92:1521-1534. 1966.-The serological reactivity of an antigenically hybrid influenza virus recombinant (X-7) was studied in a heteroploid cell plaquing system in which antisera to the parental viruses NWS/(A(0)) and RI/5(+) (A(2)) were incorporated in agar overlay media. Two different effects on plaque formation were found. With NWS antiserum, there was close relationship between reduction in plaque size and in plaque number [plaque inhibition (PI) pattern]. With RI/5 antiserum, plaque size reduction (PSR) occurred over a wide zone of serum dilutions without concomitant change in plaque number (PSR pattern). Several different preinoculation neutralization tests showed a strong reactivity of X-7 with NWS antisera and little if any reactivity with RI/5 antisera. We interpret the differing effects of NWS and RI/5 antisera on X-7 as indicative of the possible occurrence of different mechanisms of neutralization or of the possible participation of different surface antigens. The kinetics of PSR are consistent with the hypothesis that it results from the reaction of RI/5 antiserum with the RI/5-like neuraminidase of X-7. Studies with the antiserum-in-overlay technique of PSR and PI patterns comprise a sensitive method for quantitative antigenic analysis of plaque-forming influenza viruses.