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Epithelial Integrity (epithelial + integrity)

Distribution by Scientific Domains

Medical Sciences	75%

Selected Abstracts

Disruption of nasopharyngeal epithelium by pneumococci is density-linked

EUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 4 2003
K. Lagrou
Abstract Background The aim of this project was to study the influence of pneumococci on nasopharyngeal epithelial integrity as a function of time and pneumococcal density. Materials and methods Cell layers of an in vitro model of human nasopharyngeal epithelium were inoculated with different pneumococcal strains. The transepithelial electrical resistance (TEER), a measure of the integrity of the cell layers, and the pneumococcal concentration in the apical fluid on the epithelial cells were measured at different times after inoculation. Results Pneumococci caused a decrease in the TEER when a density of 1 × 107 CFU mL,1 was reached. The growth rate of pneumococci in our in vitro model differed between the strains tested and, for the same strain, between in vitro culture on the epithelial cells and broth culture. Differences in timing of the onset of decrease in the TEER between strains were the result of differences in growth rate on the epithelial cells. Antibiotic-induced lysis of pneumococci caused an immediate decrease in the TEER of the cell layers. Conclusion Pneumococci cause a decrease in the TEER at a density of 1 × 107 CFU mL,1. Our hypothesis is that this decrease in the TEER is the result of quorum-induced lysis of the pneumococci. [source]

Keratinocyte growth factor and scatter factor expression by regionally defined oral fibroblasts

EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 1 2003
Scott Thomas William McKeown
Keratinocyte growth factor (KGF) and hepatocyte growth factor/scatter factor (SF) are two signalling molecules thought to play important roles in regulating epithelial,mesenchymal interactions. Expression of both factors by fibroblasts in subepithelial connective tissue may play a role in maintaining epithelial integrity in health and in the apical migration of junctional epithelium in periodontitis. The aims of this study were (a) to compare expression levels of KGF and SF by periodontal ligament (PDL) and gingival fibroblasts; and (ii) to determine the effects of interleukin (IL)-1,, transforming growth factor (TGF)-,1, platelet-derived growth factor (PDGF)-BB and epidermal growth factor (EGF) on KGF/SF expression by these cell populations. Three paired PDL and gingival fibroblast strains were developed. The KGF and SF protein levels were analysed by enzyme-linked immunosorbent assay. Relative levels of KGF and SF mRNA in cytokine-treated cultures were determined using semiquantitative reverse transcriptase polymerase chain reaction. No differences in the levels of KGF and SF produced by PDL and gingival (SOG) populations were found. In both cell types IL-1, stimulated KGF and SF expression, while TGF-,1 significantly inhibited expression at both the mRNA and protein levels. Epidermal growth factor and PDGF-BB induced differing effects on expression, stimulating SF protein production but inhibiting KGF output in both fibroblast populations. Differences in response to EGF and PDGF were also seen between paired PDL and gingival fibroblasts. [source]

Exclusive Breast-feeding: Does It Have the Potential to Reduce Breast-feeding Transmission of HIV-1?

NUTRITION REVIEWS, Issue 11 2000
Melanie M. Smith M.N.S.
Exclusive breast-feeding is unambiguously the optimal infant feeding practice and is universally promoted in the absence of human immunodeficiency virus (HIV-1). It is associated with reduced morbidity and mortality from diarrheal and respiratory diseases. Recent findings suggest that exclusive breast-feeding may pose less risk of HIV-1 transmission than the more common practice of mixed feeding (i.e., breast-feeding concurreptwith the feeding of water, other fluids, and foods), which has important infant feeding policy implications for low-resource settings. This paper reviews the biologic mechanisms associated with exclusive breast-feeding that provide protection against gastrointestinal, respiratory, and atopic diseases, and evaluates the relevance of these mechanisms for HIV-1 transmission. Potential mechanisms include reduction in dietary antigens and enteric pathogens that may maintain integrity of the intestinal mucosal barrier and limit inflammatory responses of the gut mucosa; promotion of beneficial intestinal microflora that may increase resistance to infection and modulate the infant's immune response; alteration in specific antiviral or anti-inflammatory factors in human milk that may modulate maternal hormonal or immunologic status; and maintenance of mammary epithelial integrity that may reduce viral load in breast milk. [source]

Escherichia coli,-haemolysin induces focal leaks in colonic epithelium: a novel mechanism of bacterial translocation

CELLULAR MICROBIOLOGY, Issue 10 2007
Hanno Troeger
Summary Extraintestinal pathogenic Escherichia coli (ExPEC) are usually harmless colonizer of the intestinal microflora. However, they are capable to translocate and cause life-threatening disease. Translocation of ExPEC isolates was quantified in colonic monolayers. Transepithelial resistance (Rt) was monitored and local changes in conductivity analysed with conductance scanning. Confocal microscopy visualized the translocation route. Corroboratory experiments were performed on native rat colon. One translocating strain E. coli O4 was identified. This translocation process was associated with an Rt decrease (36 ± 1% of initial resistance) beginning only 2 h after inoculation. The sites of translocation were small defects in epithelial integrity (focal leaks) exhibiting highly increased local ion permeability. Translocation was enhanced by preincubation of monolayers with tumour necrosis factor-, or interleukin-13. Mutant strains lacking alpha-haemolysin lost the ability to induce focal leaks, while this effect could be restored by re-introducing the haemolysin determinant. Filtrate of a laboratory strain carrying the alpha-haemolysin operon was sufficient for focal leak induction. In native rat colon, E. coli O4 decreased Rt and immunohistology demonstrated focal leaks resembling those in cell monolayers. E. coli,-haemolysin is able to induce focal leaks in colonic cell cultures as well as in native colon. This process represents a novel route of bacterial translocation facilitated by pro-inflammatory cytokines. [source]