Tight Junctions in Salivary Epithelium

Epithelial cell tight junctions (TJs) consist of a narrow belt-like structure in the apical region of the lateral plasma membrane that circumferentially binds each cell to its neighbor. TJs are found in tissues that are involved in polarized secretions, absorption functions, and maintaining barriers between blood and interstitial fluids. The morphology, permeability, and ion selectivity of TJ vary among different types of tissues and species. TJs are very dynamic structures that assemble, grow, reorganize, and disassemble during physiological or pathological events. Several studies have indicated the active role of TJ in intestinal, renal, and airway epithelial function; however, the functional significance of TJ in salivary gland epithelium is poorly understood. Interactions between different combinations of the TJ family (each with their own unique regulatory proteins) define tissue specificity and functions during physiopathological processes; however, these interaction patterns have not been studied in salivary glands. The purpose of this review is to analyze some of the current data regarding the regulatory components of the TJ that could potentially affect cellular functions of the salivary epithelium

Effects of pro-inflamatory cytokines on polarized rat parotid Par-C10 monolayers [abstract]

Abstract only availableSjögren's syndrome (SS), an autoimmune disorder, is distinguished by inflammation and salivary gland cell death, leading to xerostomia (dry mouth). The G protein-coupled P2Y2 receptor (P2Y2R) is up-regulated in response to damage or stress in salivary epithelium. Pro-inflammatory cytokines associated with SS can be produced by infiltrating lymphocytes or salivary epithelium. Correlations have been found between lymphocytic infiltration and increased production of pro-inflammatory cytokines such as interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-Éø (TNFα) and interferon-γ (IFNγ) and decreased function of exocrine glands in SS. Recent data has shown that P2Y2R activation enhances the activity of metalloproteases that release TNFα. OBJECTIVES: To study the effects of cytokines on polarized salivary epithelium. METHODS: Polarized rat parotid (Par-C10) monolayers were used to perform these studies. Cytokines released by UTP-induced P2Y2R activation were identified by ELISA. To evaluate the role of cytokines associated with SS on epithelial integrity, epithelial resistance was determined and correlated with the expression and distribution of tight junction (TJ) proteins by immunofluorescence and Western analysis, respectively. RESULTS: Activation of P2Y2Rs in Par-C10 monolayers induced the release of TNFα. The cytokines TNFα and IFNγ, but not IL-6 or IL1β, decreased the resistance of Par-C10 cells. However, the expression/distribution of the TJ protein ZO-1 was unaffected. CONCLUSIONS: The data support a hypothesis that P2Y2R expression and activation in salivary gland cells contribute to epithelial dysfunction in SS by generating pro-inflammatory cytokines that regulate ion transport and epithelial integrity in salivary glands. Future studies will determine the role of cytokines on the expression and distribution of other TJ molecules including occludin, claudins and junctional adhesion molecules. These studies may lead to better therapeutic strategies for minimizing autoimmune-associated dysfunction of salivary gland that contributes to xerostomia in SS patient.Life Sciences Undergraduate Research Opportunity Progra

P2Y2 nucleotide receptors mediate inflammatory responses in mouse salivary gland cells

Abstract only availableSjögren's syndrome (SS) is a chronic inflammatory autoimmune disease characterized by destruction of salivary and lacrimal glands leading to xerostomia (dry mouth) and xerophthalmia (dry eyes). Although the mechanisms involved have not been adequately elucidated, the diminished function of exocrine glands in SS is often associated with lymphocytic infiltration of the tissue. Aberrant expression of specific adhesion molecules such as vascular cell adhesion molecule-1 (VCAM-1) and intracellular cell adhesion molecule-1 (ICAM-1) is also observed in salivary gland with SS, which enable salivary epithelium to interact directly with infiltrating lymphocytes. P2Y2 nucleotide receptor (P2Y2R) is G protein-couple receptor that is activated by extracellular ATP and UTP. P2Y2R expression and activity is up-regulated in response to damage or stress in a variety of tissues, including submandibular glands (SMGs), where it mediates a complex set of cellular responses to injury of disease. Additionally, P2Y2R activation up-regulates VCAM-1 expression in dispersed rat SMG cell culture and human submandibular gland (HSG) cells. Our objective is to investigate weather P2Y2R up-regulation correlates with increased expression of adhesion molecules in SMGs from a mouse model for SS (C57BL/6.NOD-Aec1Aec2) as compared with normal mouse strain (C57BL/6). P2Y2R expression was measured by RT-PCR and adhesion molecules expression was determined by Western blot analysis. Salivary flow was preformed by cannulation of individual glands. We could see that P2Y2R expression and ICAM-1 expression were both up-regulated in the SMGs from a mouse model for SS as compared with normal mouse strain. And salivary flow was decreased in salivary glands from a mouse model for SS. These results suggest that P2Y2R mediate inflammatory responses related to secretory dysfunction in the mouse model for SS. Our ultimate goal would be to translate all this information to the human salivary gland in order to understand SS and to develop new therapies for salivary dysfunction in SS.Gyeongsang National Universit

Who knows best? A Q methodology study to explore perspectives of professional stakeholders and community participants on health in low-income communities

Abstract Background Health inequalities in the UK have proved to be stubborn, and health gaps between best and worst-off are widening. While there is growing understanding of how the main causes of poor health are perceived among different stakeholders, similar insight is lacking regarding what solutions should be prioritised. Furthermore, we do not know the relationship between perceived causes and solutions to health inequalities, whether there is agreement between professional stakeholders and people living in low-income communities or agreement within these groups. Methods Q methodology was used to identify and describe the shared perspectives (‘subjectivities’) that exist on i) why health is worse in low-income communities (‘Causes’) and ii) the ways that health could be improved in these same communities (‘Solutions’). Purposively selected individuals (n = 53) from low-income communities (n = 25) and professional stakeholder groups (n = 28) ranked ordered sets of statements – 34 ‘Causes’ and 39 ‘Solutions’ – onto quasi-normal shaped grids according to their point of view. Factor analysis was used to identify shared points of view. ‘Causes’ and ‘Solutions’ were analysed independently, before examining correlations between perspectives on causes and perspectives on solutions. Results Analysis produced three factor solutions for both the ‘Causes’ and ‘Solutions’. Broadly summarised these accounts for ‘Causes’ are: i) ‘Unfair Society’, ii) ‘Dependent, workless and lazy’, iii) ‘Intergenerational hardships’ and for ‘Solutions’: i) ‘Empower communities’, ii) ‘Paternalism’, iii) ‘Redistribution’. No professionals defined (i.e. had a significant association with one factor only) the ‘Causes’ factor ‘Dependent, workless and lazy’ and the ‘Solutions’ factor ‘Paternalism’. No community participants defined the ‘Solutions’ factor ‘Redistribution’. The direction of correlations between the two sets of factor solutions – ‘Causes’ and ‘Solutions’ – appear to be intuitive, given the accounts identified. Conclusions Despite the plurality of views there was broad agreement across accounts about issues relating to money. This is important as it points a way forward for tackling health inequalities, highlighting areas for policy and future research to focus on

P2Y2 receptors Transactivate the EGFR/ERB1 and ERB3 Growth Factor Receptors in Human Salivary Gland Cells [abstract]

Abstract only availableThe epidermal growth factor receptor (EGFR/ERB1) plays a key role in the regulation of epithelial cell development, differentiation and in the pathophysiology of hyperproliferative diseases such as cancer. Transactivation of the EGFR/ERB1 by G-protein coupled receptors has been shown to be dependent on proteolytic cleavage of membrane ligands such as heparin binding epidermal growth factor (HBEGF), EGF, transforming growth factor (TGF-), epiregulin, amphiregulin and betacellulin. Utilizing the human submandibular gland (HSG) cell line, we found that activation of the P2Y2 nucleotide receptor (P2Y2R) by its agonist UTP caused a time-dependent activation of EGFR/ERB1; however, neutralizing antibodies to the known ligands to EGFR/ERB1 failed to inhibit the UTP-induced phosphorylation of EGFR/ERB1. EGFR/ERB1 phosphorylation can also be induced by heterodimerization with one of the other ERB family members, ERB2, ERB3, and ERB4. HSG cells express ERB2 and ERB3 but not ERB4. Since ERB2 is a ligandless receptor, ERB3 is the likely dimerizing partner. Our results indicate that P2Y2R activation by UTP phosphorylates ERB3. Heregulin, the only known ligand for ERB3 is expressed in HSGs. Therefore, our results suggest that P2Y2R activation stimulates the formation of ERB3-EGFR/ERB1 heterodimers by cleavage of heregulin and its binding to ERB3

Movements and Population Structure of Humpback Whales in the North Pacific

Despite the extensive use of photographic identification methods to investigate humpback whales in the North Pacific, few quantitative analyses have been conducted. We report on a comprehensive analysis of interchange in the North Pacific among three wintering regions (Mexico, Hawaii, and Japan) each with two to three subareas, and feeding areas that extended from southern California to the Aleutian Islands. Of the 6,413 identification photographs of humpback whales obtained by 16 independent research groups between 1990 and 1993 and examined for this study, 3,650 photographs were determined to be of suitable quality. A total of 1,241 matches was found by two independent matching teams, identifying 2,712 unique whales in the sample (seen one to five times). Site fidelity was greatest at feeding areas where there was a high rate of resightings in the same area in different years and a low rate of interchange among different areas. Migrations between winter regions and feeding areas did not follow a simple pattern, although highest match rates were found for whales that moved between Hawaii and southeastern Alaska, and between mainland and Baja Mexico and California. Interchange among subareas of the three primary wintering regions was extensive for Hawaii, variable (depending on subareas) for Mexico, and low for Japan and reflected the relative distances among subareas. Interchange among these primary wintering regions was rare. This study provides the first quantitative assessment of the migratory structure of humpback whales in the entire North Pacific basin

Chemotactic response and adaptation dynamics in Escherichia coli

Adaptation of the chemotaxis sensory pathway of the bacterium Escherichia coli is integral for detecting chemicals over a wide range of background concentrations, ultimately allowing cells to swim towards sources of attractant and away from repellents. Its biochemical mechanism based on methylation and demethylation of chemoreceptors has long been known. Despite the importance of adaptation for cell memory and behavior, the dynamics of adaptation are difficult to reconcile with current models of precise adaptation. Here, we follow time courses of signaling in response to concentration step changes of attractant using in vivo fluorescence resonance energy transfer measurements. Specifically, we use a condensed representation of adaptation time courses for efficient evaluation of different adaptation models. To quantitatively explain the data, we finally develop a dynamic model for signaling and adaptation based on the attractant flow in the experiment, signaling by cooperative receptor complexes, and multiple layers of feedback regulation for adaptation. We experimentally confirm the predicted effects of changing the enzyme-expression level and bypassing the negative feedback for demethylation. Our data analysis suggests significant imprecision in adaptation for large additions. Furthermore, our model predicts highly regulated, ultrafast adaptation in response to removal of attractant, which may be useful for fast reorientation of the cell and noise reduction in adaptation.Comment: accepted for publication in PLoS Computational Biology; manuscript (19 pages, 5 figures) and supplementary information; added additional clarification on alternative adaptation models in supplementary informatio

Effect of ethnomedicinal plants used in folklore medicine in Jordan as antibiotic resistant inhibitors on Escherichia coli

<p>Abstract</p> <p>Background</p> <p><it>Escherichia coli </it>occurs naturally in the human gut; however, certain strains that can cause infections, are becoming resistant to antibiotics. Multidrug-resistant <it>E. coli </it>that produce extended-spectrum β lactamases (ESBLs), such as the CTX-M enzymes, have emerged within the community setting as an important cause of urinary tract infections (UTIs) and bloodstream infections may be associated with these community-onsets. This is the first report testing the antibiotic resistance-modifying activity of nineteen Jordanian plants against multidrug-resistant <it>E. coli</it>.</p> <p>Methods</p> <p>The susceptibility of bacterial isolates to antibiotics was tested by determining their minimum inhibitory concentrations (MICs) using a broth microdilution method. Nineteen Jordanian plant extracts (<it>Capparis spinosa </it>L., <it>Artemisia herba-alba Asso, Echinops polyceras </it>Boiss., <it>Gundelia tournefortii </it>L, <it>Varthemia iphionoides </it>Boiss. & Blanche, <it>Eruca sativa Mill</it>., <it>Euphorbia macroclada </it>L., <it>Hypericum trequetrifolium </it>Turra, <it>Achillea santolina </it>L., <it>Mentha longifolia </it>Host, <it>Origanum syriacum </it>L., <it>Phlomis brachydo</it>(Boiss.) Zohary, <it>Teucrium polium </it>L., <it>Anagyris foetida </it>L., <it>Trigonella foenum-graecum </it>L., <it>Thea sinensis </it>L., <it>Hibiscus sabdariffa </it>L., <it>Lepidium sativum </it>L., <it>Pimpinella anisum </it>L.) were combined with antibiotics, from different classes, and the inhibitory effect of the combinations was estimated.</p> <p>Results</p> <p>Methanolic extracts of the plant materials enhanced the inhibitory effects of chloramphenicol, neomycin, doxycycline, cephalexin and nalidixic acid against both the standard strain and to a lesser extent the resistant strain of <it>E. coli</it>. Two edible plant extracts (<it>Gundelia tournefortii L</it>. and <it>Pimpinella anisum L</it>.) generally enhanced activity against resistant strain. Some of the plant extracts like <it>Origanum syriacum </it>L.(Labiateae), <it>Trigonella foenum- graecum </it>L.(Leguminosae), <it>Euphorbia macroclada </it>(Euphorbiaceae) and <it>Hibiscus sabdariffa </it>(Malvaceae) did not enhance the activity of amoxicillin against both standard and resistant <it>E. coli</it>. On the other hand combinations of amoxicillin with other plant extracts used showed variable effect between standard and resistant strains. Plant extracts like <it>Anagyris foetida </it>(Leguminosae) and <it>Lepidium sativum </it>(Umbelliferae) reduced the activity of amoxicillin against the standard strain but enhanced the activity against resistant strains. Three edible plants; Gundelia <it>tournefortii </it>L. (Compositae) <it>Eruca sativa </it>Mill. (Cruciferae), and <it>Origanum syriacum </it>L. (Labiateae), enhanced activity of clarithromycin against the resistant <it>E. coli </it>strain.</p> <p>Conclusion</p> <p>This study probably suggests possibility of concurrent use of these antibiotics and plant extracts in treating infections caused by <it>E. coli </it>or at least the concomitant administration may not impair the antimicrobial activity of these antibiotics.</p

TBC-2 Is Required for Embryonic Yolk Protein Storage and Larval Survival during L1 Diapause in Caenorhabditis elegans

C. elegans first stage (L1) larvae hatched in the absence of food, arrest development and enter an L1 diapause, whereby they can survive starvation for several weeks. The physiological and metabolic requirements for survival during L1 diapause are poorly understood. However, yolk, a cholesterol binding/transport protein, has been suggested to serve as an energy source. Here, we demonstrate that C. elegans TBC-2, a RAB-5 GTPase Activating Protein (GAP) involved in early-to-late endosome transition, is important for yolk protein storage during embryogenesis and for L1 survival during starvation. We found during embryogenesis, that a yolk::green fluorescent protein fusion (YP170::GFP), disappeared much more quickly in tbc-2 mutant embryos as compared with wild-type control embryos. The premature disappearance of YP170::GFP in tbc-2 mutants is likely due to premature degradation in the lysosomes as we found that YP170::GFP showed increased colocalization with Lysotracker Red, a marker for acidic compartments. Furthermore, YP170::GFP disappearance in tbc-2 mutants required RAB-7, a regulator of endosome to lysosome trafficking. Although tbc-2 is not essential in fed animals, we discovered that tbc-2 mutant L1 larvae have strongly reduced survival when hatched in the absence of food. We show that tbc-2 mutant larvae are not defective in maintaining L1 diapause and that mutants defective in yolk uptake, rme-1 and rme-6, also had strongly reduced L1 survival when hatched in the absence of food. Our findings demonstrate that TBC-2 is required for yolk protein storage during embryonic development and provide strong correlative data indicating that yolk constitutes an important energy source for larval survival during L1 diapause

Evolution and Diversity of Clonal Bacteria: The Paradigm of Mycobacterium tuberculosis

International audienceBACKGROUND: Mycobacterium tuberculosis complex species display relatively static genomes and 99.9% nucleotide sequence identity. Studying the evolutionary history of such monomorphic bacteria is a difficult and challenging task. PRINCIPAL FINDINGS: We found that single-nucleotide polymorphism (SNP) analysis of DNA repair, recombination and replication (3R) genes in a comprehensive selection of M. tuberculosis complex strains from across the world, yielded surprisingly high levels of polymorphisms as compared to house-keeping genes, making it possible to distinguish between 80% of clinical isolates analyzed in this study. Bioinformatics analysis suggests that a large number of these polymorphisms are potentially deleterious. Site frequency spectrum comparison of synonymous and non-synonymous variants and Ka/Ks ratio analysis suggest a general negative/purifying selection acting on these sets of genes that may lead to suboptimal 3R system activity. In turn, the relaxed fidelity of 3R genes may allow the occurrence of adaptive variants, some of which will survive. Furthermore, 3R-based phylogenetic trees are a new tool for distinguishing between M. tuberculosis complex strains. CONCLUSIONS/SIGNIFICANCE: This situation, and the consequent lack of fidelity in genome maintenance, may serve as a starting point for the evolution of antibiotic resistance, fitness for survival and pathogenicity, possibly conferring a selective advantage in certain stressful situations. These findings suggest that 3R genes may play an important role in the evolution of highly clonal bacteria, such as M. tuberculosis. They also facilitate further epidemiological studies of these bacteria, through the development of high-resolution tools. With many more microbial genomes being sequenced, our results open the door to 3R gene-based studies of adaptation and evolution of other, highly clonal bacteria