SEARCH · PubMed Health

Results for “Epithelial Cells”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

PubMed1991

Morphological and immunocytochemical characterization of cultured rat incisor cervical epithelial cells.

Epithelial cells from the cervical loop of the rat incisor were isolated by co-culture of apical explants with growth-arrested 3T3 fibroblasts. The epithelial phenotype of the expanding outgrowths was confirmed 10 days after the seeding of the explants by phase-contrast microscopy and immunocytochemical identification of cytokeratins. After 3 weeks in culture, the epithelial cells covered the entire surface of the coverslips and were then passaged. Subcultures gave rise to a confluent sheet within 10-12 days. Light and electron microscopy showed that confluent cervical epithelial cells generally reconstituted a bi-layered structure similar to Hertwig's epithelial sheath. Epithelial cells from the rat palate, cultured and subcultured according to the same procedure, organized themselves in 5-6 cell layers, the upper cells having generally a squamous morphology. Synthesis of extracellular matrix molecules by rat incisor cervical epithelial cells was studied with specific antibodies. These cells failed to produce type I collagen, but synthesized all the major basement membrane components (type IV collagen, laminin, heparan sulphate proteoglycan and fibronectin). These observations suggest that the culture conditions allowed the reconstitution of a typical Hertwig's epithelial sheath by rat incisor cervical epithelial cells.

Animals↗

PubMed1991

Endocytotic activity of the free floating cells and epithelial cells in the endolymphatic sac: an electron microscopic study.

The fine structure and its functional properties of both free floating cells and epithelial cells in the endolymphatic sac after injections of India ink particles or polystyrene latex beads, 0.24 micron in diameter, into the endolymphatic space, were studied using light and electron microscopy. Twenty-four to 48 hours after injections, these foreign materials had accumulated in the lumen of the endolymphatic sac and a large number of them were ingested into free floating cells, most of which appear to be macrophages. Granular leucocytes taking up the foreign materials into the cytoplasm were also recognized in the sac lumen. A few of these leucocytes passed through the epithelium and migrated to the subepithelial connective tissue, while the others were degenerated and phagocytosed by the free floating cells in the lumen of the sac. In addition to the free floating cells, ink particles, latex beads, and degenerated leucocytes were endocytosed into some of the epithelial cells. As we reported previously, the epithelial cells were clearly classified into two types; type-1 epithelial cells (cytoorganelle-rich cells) and type-2 epithelial cells (filament-rich cells). The foreign materials and degenerated cells were taken up mainly into the type-1 epithelial cells, while the type-2 epithelial cells did not show so marked endocytotic activity in comparison with the type-1 epithelial cells. Thus, it becomes clear that the endolymphatic sac plays an important role in the endocytotic activity for foreign materials and waste products, and both the free floating cells and the type-1 epithelial cells of the sac have strong endocytotic activity.

Animals↗

PubMed1991

Expression and function of interleukin-6 in epithelial cells.

Epithelial cells both produce and are affected by interleukin-6 (IL-6). Experiments with an adenocarcinoma-derived cell line (HeLa) reveal that activation of the transfected human IL-6 promoter occurs largely through two partially overlapping second messenger (cAMP, phorbol ester)- and cytokine (IL-1, TNF, serum)-responsive enhancer elements (MRE 1, -173 to -151 and MRE II, -158 to -145). MRE I contains the typical GACGTCA cAMP and phorbol ester-responsive (CRE-TRE) motif, whereas MRE II defines a new CRE/TRE motif that contains an imperfect dyad repeat. The mechanism of dexamethasone-mediated repression of IL-6 gene expression in epithelial cells involves occlusion of the entire MRE enhancer region and of the core-promoter elements (TATA-box and RNA start site) by ligand-activated glucocorticoid receptor. Enhanced levels of IL-6 expression are observed in many solid tumors and in the hyperproliferative (and glucocorticoid-suppressible) lesions of psoriasis. In cell culture, IL-6 enhances, inhibits, or has no effect on the proliferation of epithelial cells depending upon the cell-type examined. IL-6 enhances proliferation of keratinocytes but inhibits that of breast carcinoma cell lines ZR-75-1 and T-47D. In these breast carcinoma cells, IL-6 elicits a major change in cell phenotype which is characterized by a fibroblastoid morphology, enhanced motility, increased cell-cell separation, and decreased adherens type junctions (desmosomes and focal adhesions). The new data identify IL-6 as a regulator of epithelial cell growth and of cell-cell association.

Animals↗

PubMed1988

Isolation, characterization, and long-term culture of fetal bovine tracheal epithelial cells.

Epithelial cells were isolated from fetal bovine trachea by exposing and stripping the mucosal epithelium from the adjacent connective tissue. The tissue was minced and enzymically dissociated in Ca-Mg-free medium containing dispase and dithiothreitol. The stripping procedure and selective trypsinization produced epithelial cell cultures free of fibroblasts. Seeded on plastic, the plating efficiency was 21.5% with a doubling time of 24 h. Dome formation, evidence of occluding junctions and active ion transport characteristic of epithelial cells, was common. Growth of the cells on glass, collagen, and Engelbreth-Holm-Swarm (EHS) substrate demonstrated a striking difference in morphology. Cells grown on EHS presented a more distinctly three-dimensional growth pattern and many more microvilli when compared to cells grown on glass or collagen. The cells retained their epithelioid characteristics through more than 30 passages as shown by the presence of distinct apical and basolateral membranes, tight junctions, and positive keratin staining.

Animals↗

PubMed1991

Serum-free growth and karyotype analyses of cultured normal and tumorous (SqCC/Y1) human buccal epithelial cells.

Epithelial cell cultures were obtained following tryptic digestion of normal human buccal mucosa. Primary cultures exhibited markedly higher colony-forming efficiencies and growth rates using fibronectin/collagen-coated, as compared to non-coated culture dishes and a serum-free MCDB 153 medium developed for epidermal epithelial cells than a similar medium previously developed for buccal explant outgrowth cultures. At the preferred conditions, the cells could be transferred at least 5-fold, divided at about one population doubling per day, and commonly underwent 60 population doublings resulting in yields of 10(8) to 10(11) cells per cm2 mucosal specimen. Moreover, these conditions successfully cultivated a buccal carcinoma cell line (SqCC/Y1) for several months. The carcinoma cells were resistant to factors that inhibited growth or induced differentiation of normal cells, i.e., transforming growth factor type beta 1, Ca2+, or serum. Karyotype analyses of SqCC/Y1 cells showed 63 to 83 chromosomes per metaphase and consistent occurrences of monosomy 1, tetrasomy 19 and 20, as well as trisomy 22, and at least 7 marker chromosomes, whereas cells obtained from non-cancerous donors were diploid. It is concluded that the similarly defined culture conditions may now be applied to study characteristics of both normal and tumorous buccal epithelial cells.

Blood↗

PubMed1992

Epstein-Barr virus enters B cells and epithelial cells by different routes.

Epstein-Barr virus (EBV) infects two cell types, B lymphocytes and epithelial cells. Electron microscopic studies have shown that the virus fuses with the lymphoblastoid cell line Raji but is endocytosed into thin-walled non-clathrin-coated vesicles in normal B cells before fusion takes place. To compare early interactions of EBV with epithelial cells and B cells, a fluorescence dequenching assay of fusion was employed, using virus labeled either with the pH-insensitive probe octadecyl rhodamine B chloride (R18) or with 5(N-octadecanoyl) aminofluorescein (AF), which loses emission intensity at a pH below 7.4. Fusion of virus labeled with R18 could be monitored with B cells, Raji cells, and epithelial cells. Lowering the extracellular pH or pretreatment of cells with ammonium chloride or methylamine had no effect on these measurements. In contrast, fusion of virus labeled with AF could be measured with Raji cells and epithelial cells, but not with normal B cells unless cells were previously treated with ammonium chloride. Fusion of virus with normal B cells was inhibited with chlorpromazine, chloroquine, and sodium azide, but none of these reagents had any effect on fusion with Raji or epithelial cells. These results suggest that entry of EBV into nonpolarized suspensions of epithelial cells occurs by fusion at the cell surface, that EBV may be incapable of fusing with normal B cells unless it has first been endocytosed, and that pH appears to be irrelevant to either event. A combination of the two probes, R18 and AF, may have general use for determining the sites of entry of enveloped viruses that fuse in a pH-independent manner.

Attachment Sites, Microbiological↗

PubMed1992

Growth of epithelial cells in the thymic medulla is under the control of mature T cells.

Epithelial cells in the thymic medulla are conspicuous in normal adult mice, but sparse in the early fetal thymus and the thymus of adult T cell-deficient SCID mice. To examine whether growth of medullary epithelial cells (MEC) depends upon local contact with mature T cells, we used the finding that the SCID thymus is unusually permeable to mature T cells entering from the bloodstream. When SCID mice received multiple injections of mature lymph node T cells from birth, the thymus accumulated large numbers of mature TCR+ T cells of resting phenotype, but contained virtually no immature (CD4+8+) cells. The injected T cells localized in the medullary region of the thymus and led to marked regeneration of MEC. These and other data suggest that the growth of MEC is under the control of mature T cells. Placing MEC under T cell control might be a device for regulating the size and integrity of the medulla, especially during the phase of rapid thymic growth. Maintaining the cellular components of the medulla in proper balance could be critical for ensuring efficient self tolerance induction.

Animals↗

PubMed1990

Human oral epithelial cell culture. II. Keratin expression in fetal and adult gingival cells.

Epithelial cells from human fetal and adult gingiva were cultured in keratinocyte growth medium (KGM), a serum-free medium. The expression of keratin proteins in these cells was evaluated using immunohistochemistry and SDS-PAGE-immunoblot analysis and compared with expression in the tissue. Keratins 5, 6, 14, 16, and 19 were identified in cells cultured from both fetal and adult tissues. K19 was localized in basal cells of fetal oral tissue but was not seen in adult gingiva (except for scattered Merkel cells). K1 and K10 were expressed in tissue, but not in cultured cells. The keratin profiles of cultured epithelial cells from several adult donors were similar and were identical in cultures from primary through Passage 5. K13, a differentiation-specific keratin, was expressed in all suprabasal cells of fetal oral epithelium, but shows only spotty expression in adult gingival tissue. K13 was expressed in cultures of fetal cells, but very weakly or not at all in cultures of adult cells. K13 expression was greater in cultures grown with physiologic calcium concentrations (1.2 mM) than in those grown at 0.15 mM or less. Our findings are consistent with basal-like characters of these cells in 0.15 mM calcium growth conditions. Differentiation of fetal oral cells in culture to the suprabasal basal cell stage in 1.2 mM Ca2+ is shown by the expression of K13.

Adult↗

PubMed1992

Biological characteristics of primary cultures of human gallbladder epithelial cells.

Epithelial cells of the gallbladder have potential to represent an important model for studies of ductal epithelial in normal and pathological states. We therefore initiated studies to establish human gallbladder epithelial cells (GBEC) in culture. GBEC were isolated by trypsinization of small tissue fragments from human gallbladders obtained at cholecystectomy; cells were plated on tissue culture dishes and grown in defined MCDB 153 medium containing added growth factors. In this medium, GBEC showed a plating efficiency of approximately 1%; those GBEC that attached formed colonies and proliferated, as demonstrated by autoradiographic analysis of [3H]thymidine incorporation into DNA. Cultured GBEC expressed two markers found on GBEC in situ, i.e., gamma-glutamyl transpeptidase and cytokeratin 19. By using various attachment substrates, with and without added serum, increased plating efficiency and better growth were achieved. When type IV collagen was used as substrate and 10% fetal bovine serum was added to MCDB 153, passage of GBEC was possible, and cells proliferated through five to six population doublings. GBEC in culture under all conditions eventually enlarged, showed vacuolization, and demonstrated irreversible growth arrest. Nonetheless, the culture conditions described here allow for preparation of large quantities of highly enriched human GBEC.

Cell Division↗

PubMed1990

Comparison of the function of the tight junctions of endothelial cells and epithelial cells in regulating the movement of electrolytes and macromolecules across the cell monolayer.

In cell culture, both endothelial and epithelial cell monolayers have been found to generate structurally similar tight junctional complexes, as assessed by thin complexes of the two cell types are, at least in part, responsible for the very different permeability characteristics of native endothelial and epithelial cell monolayers. The purpose of this work was to compare cultured endothelial and epithelial cells with respect to the function of their tight junctional complexes in regulating the movement of macromolecules and ions across the cell monolayers, and define functional parameters to characterize the tight junctional complexes. Bovine aorta endothelial cells and T84 colonic carcinoma epithelial cells were cultured on a microporous membrane support. The permeability coefficients of inulin, albumin, and insulin were determined with the cell monolayers and compared with the permeability coefficients obtained with 3T3-C2 fibroblasts, a cell line that does not generate tight junctions. Electrical resistance measurements across the monolayer-filter systems were also compared. The permeability coefficient of albumin across the endothelial cell monolayer compared favorably with other reported values. Likewise, the electrical resistance across the T84 cell monolayer was in good agreement with published values. Utilizing permeability coefficients for macromolecules as an index of tight junction function, we found that a distinction between a lack of tight junctions (fibroblasts), the presence of endothelial tight junctions, and the presence of epithelial tight junctions was readily made. However, when utilizing electrical resistance as an index of tight junction function, identical measurements were obtained with fibroblasts and endothelial cells. This indicates that more than one index of tight junction function is necessary to characterize the junctional complexes. Although structurally similar, epithelial cell and endothelial cell tight junctions perform very different functions, and, from our data, we conclude that the demonstration of tight junctional structures by electron microscopy is not relevant to the functional nature of the junction: structure does not imply function. A minimal assessment of tight junction function should rely on both the determination of the electrical resistance across the cell monolayer, and the determination of the permeability coefficients of selected macromolecules.

Animals↗

PubMed1977

Contribution of mucosal chloride to chloride in toad bladder epithelial cells.

Epithelial cells were scraped from the bladders of toads of the species Bufo marinus obtained from the Dominican Republic. These epithelial cells exchanged their chloride virtually completely with 36Cl i; the medium within 60 min. Of this chloride, about 93% came from the serosal medium. The approximately 20 mmole/kg dry wt of chloride which equilibrates with 36Cl in the mucosal medium was still present when choline replaced sodium in the medium in the presence of amiloride (10(-4) M) and was almost all readily removed by rapid washing of the mucosal surface immediately prior to analysis. These observations suggest that little chloride of mucosal origin is truly intracellular. This conclusion is supported by the fact that after vasopressin the increased cellular chloride was not of mucosal origin.

Animals↗

PubMed1989

Decay accelerating factor regulates complement activation on glomerular epithelial cells.

Epithelial cells of the glomerular capillary are the site of C5b-9 mediated injury in rat membranous nephropathy. We investigated the regulation of C activation by cultured glomerular epithelial cells (GEC). Rat and human GEC were more resistant to C injury by homologous C than heterologous C. In human GEC homologous C cytotoxicity was enhanced by antiserum to decay accelerating factor (DAF) indicating that homologous C activation was, at least in part, restricted by membrane DAF. Anti-DAF immunoprecipitated a 67-kDa protein from human glomeruli. In rat GEC, pronase and phosphatidylinositol-specific phospholipase C (which are known to inactivate human DAF) enhanced cytotoxicity by homologous C. Thus, DAF is present on human GEC in culture and in human kidney glomeruli, and a DAF-like protein is present on cultured rat GEC. These proteins regulate C activation in vitro and may play a role in controlling C activation on GEC in vivo.

Animals↗

PubMed1990

Cysteinyl leukotrienes enhance growth of human airway epithelial cells.

Epithelial inflammation may play an obligatory role in the pathogenesis of a number of chronic pulmonary diseases such as asthma or bronchitis and has been implicated during the promotion phase of multistage carcinogenesis. At sites of inflammation, bioactive lipid mediators are released and activate a wide range of pathophysiological responses including bronchospasm. Previous studies suggest that one class of inflammatory mediators, the eicosanoids, can also influence cell growth. Epithelial cell proliferation and hyperplasia are common sequelae to irritation and inflammation, and because the lung has a high capacity to produce eicosanoids, we investigated the effects of a group of these compounds, the cysteinyl leukotrienes, on growth of human airway epithelial cells. Leukotrienes were found to be mitogenic in a concentration-dependent manner and exhibit a structure-activity relationship, with leukotriene C4 being more potent than its sequential metabolites leukotriene D4 and E4. The potency of leukotriene C4 is striking, stimulating colony-forming efficiency in concentrations as low as 10 fM. These findings suggest a new physiological role for leukotrienes in the lung that links inflammation with epithelial cell proliferation.

Arachidonic Acids↗

PubMed1977

Cytotoxicity of ricinoleic acid (castor oil) and other intestinal secretagogues on isolated intestinal epithelial cells.

Epithelial cells were isolated from hamster small intestine by a technique of vibration and used to measure cytotoxicity in vitro of certain substances known to stimulate intestinal fluid secretion. These secretagogues have laxative properties and produce mucosal damage in vivo. Compounds tested were ricinoleic acid (caster oil), dioctyl sodium sulfosuccinate, oleic acid, sodium deoxycholate and sodium cholate. Cytotoxicity was assessed by: 1) exclusion of trypan blue; 2) release of intracellular (prelabeled) 51Cr; and 3) inhibition of cellular uptake of 3-O-methylglucose. Ricinoleate produced a dose-dependent (0.1-2.0 mM) cytotoxicity as assessed by all three methods. Oleic acid, a nonhydroxylated analog of ricinoleate, was less potent. The dihydroxy bile acid, deoxycholate, was equipotent with ricinoleate, was less potent. The dihydroxy bile acid, deoxycholate, was equipotent with ricinoleate but its trihydroxy congener, cholate, was less potent. Dioctyl sodium sulfosuccinate had cytotoxicity similar in magnitude to that of ricinoleate and deoxycholate. Cytotoxicity of these agents to isolated cells may relate to their secretory potential in vivo, their abilities to produce structural change at the mucosal surface and their laxative properties.

Animals↗

PubMed1990

Langerhans cells and epithelial cell modifications in cervical intraepithelial neoplasia: correlation with human papillomavirus infection.

The study of a series of 18 cervical intraepithelial neoplasia (CIN) grade II and III was aimed at determining the distribution and phenotype of immunocompetent cells (Langerhans cells, T and NK cells) and the alteration in the expression of EGF receptors and beta 2-microglobulin in correlation with human papillomavirus (HPV) infection (viral antigen and DNA typing with biotinylated probes). These lesions were characterized by a reduced number of Langerhans cells and a dense infiltrate. HPV infection did not induce HLA-DR expression in the infected epithelial cells. We observed an enhanced expression of epidermal growth factor (EGF) receptors by epithelial cells and a reduced beta 2-microglobulin reactivity by both epithelial and immunocompetent cells. Most of CIN showed foci of infected cells. No significant differences were observed in immunological markers of CIN harboring benign HPV 6/11 DNA or oncogenic HPV 16/18 DNA. Viral antigen was not detected in these lesions. These changes in the epithelial cells of CIN and their microenvironment associated to the lack of HLA-DR expression in the infected cells hamper the squamous epithelial cells to function as antigen presenting cells. This may facilitate a decrease in the immunological surveillance and may contribute to the severity of such lesions.

Adult↗

PubMed1989

Separate regulatory control of apical and basolateral Na+/H+ exchange in renal epithelial cells.

Epithelial layers of LLC-PK1/PKE20 cells, a renal epithelial cell line which expresses Na+/H+ exchange activities in the apical as well as basolateral membrane domains, are examined in the single cell mode by microspectrofluorometry. We provide evidence that basolateral Na+/H+ exchange is more sensitive to amiloride inhibition than is apical Na+/H+ exchange. Furthermore, we demonstrate that the two exchange activities differ in their regulatory control: kinase A activation (forskolin, 8-Br-cAMP) leads to inhibition of both exchange activities, whereas kinase C activation (phorbol ester) stimulates basolateral and inhibits apical Na+/H+ exchange. Thus, renal epithelial cells may contain two Na+/H+ exchange activities: an apical ("epithelial") and basolateral ("housekeeping") which may serve different cellular functions and are under separate regulatory controls.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1992

Transient appearance of Ca-binding protein (spot 35-calbindin) in bronchial epithelial cells, thyroid parafollicular cells and thymic epithelial cells during the development of rats.

Tracheobronchial epithelium, thyroid organ, thymus, of the developing rats were examined by immunohistochemistry using anti-spot 35 calbindin-antiserum. At E 14, weak to moderate immunoreactivity for spot 35-calbindin was detected in the airway epithelia of the distal half of the trachea and the extrapulmonary bronchus. The immunoreactive cells increased in intensity at E 16-E 21, but decreased markedly after birth. These cells were non-ciliated cells and comprised a majority of the epithelial cells especially in the ventral/cartilaginous portion of the airway. They were characterized by microvilli, vacuoles, granular and agranular endoplasmic reticulum. Typical ciliated cells, which were much less numerous than the immunopositive non-ciliated cells, were immunonegative. In thyroid gland, calbindin-immunoreactive cells first appeared at E 18. They increased in number at E 20-P 1 and decreased gradually after P 7. These cells were the parafollicular cells characterized by numerous secretory granules and situated in close proximity to the basal surface of the follicular cells. In the thymus, immunoreactive cells appeared in the thymic medulla at E 20. They increased in number at P 1, but decreased gradually after P 7. They were stellate in shape and had vesicles, vacuoles, intermediate filaments and represented a subpopulation of thymic reticular epithelial cells. Such a transient appearance of spot 35-calbindin in these cells suggests that this protein may be involved in the regulation of differentiation or may be involved in the process of secretion during the limited developmental period.

Animals↗

PubMed1989

Chronic inflammatory cells with epithelial cell characteristics in teleost fishes.

Certain cells that participate in the chronic inflammatory response of teleost fishes have many features typical of epithelioid cells of mammals. Such features include high metabolic activity, frequent phagolysosomes, and cytoplasmic interdigitations between adjacent cells; however, the epithelioid granulomas formed in response to certain diseases in teleost fishes also have several features associated with epithelial cells. Cases of ulcerative mycosis or acid-fast bacterial infection in Atlantic menhaden (Brevoortia tyrannus), fungal infection in silver perch (Bairdiella chrysoura), and mycobacteriosis in Mozambique tilapia (Oreochromis mossambicus) had epithelioid cells that were joined together by well-formed desmosomes with tonofilaments. "Mature granulomas" of the ulcerative mycosis-infected menhaden stained positively for cytokeratin, a cytoskeletal protein that is considered to be highly specific for epithelial cells. The consistent presence of these heretofore unrecognized epithelial features suggest that they may be characteristic of certain types of cells participating in piscine chronic inflammation.

Animals↗