Search PubMed⌕ Search

Biomedical subjects

A Jarry

Publications and source records attributed to A Jarry.

At least 37 records · Page 2Linked to original sources
PubMed1997

NO-dependent and NO-independent IL-1 production by a human colonic epithelial cell line under inflammatory stress.

1. The present study was designed to investigate, in an in vitro model of the human intestinal barrier, the ability of epithelial cells to produce interleukin-1 (IL-1), the cellular mechanisms involved in IL-1 release, and the intracellular signalling pathways involved in IL-1 up-regulation during inflammatory stress. 2. This study was based on the human colonic epithelial cell line HT29-Cl.16E, maintained as polarized monolayers on filters mounted in culture chambers and treated with various proinflammatory cytokines (interferon gamma (IFN gamma), tumour necrosis factor alpha (TNF alpha), IL-1 beta) alone or in combination. 3. IL-1 production, restricted to IL-1 alpha, was induced by the combination of IFN gamma/TNF alpha. When IL-1 beta was added to IFN gamma/TNF alpha, it led to an additional production of IL-1 alpha. IL-1 alpha release was associated with cell damage, as shown by the correlation between lactate dehydrogenase (LDH) release and extracellular IL-1 production, and was not accounted for by a secretory mechanism. 4. Both IFN gamma/TNF alpha and IFN gamma/TNF alpha/IL-1 beta induced inducible nitric oxide synthase (iNOS) expression as shown by quantitation of NO2-/NO3- by use of the Griess reagent, quantitation of cells scoring positive with an anti-iNOS antibody and detection of mRNAs coding for iNOS by RT-PCR. The use of NG-monomethyl-L-arginine (L-NMMA), an inhibitor of NOS, led to the demonstration of two distinct signalling pathways in IL-1 production by HT29-Cl.16E cells, one dependent on NO (L-NMMA-sensitive) under treatment with IFN gamma/TNF alpha/IL-1 beta, and the other independent of NO (L-NMMA-insensitive) under treatment with IFN gamma/TNF alpha. 5. Moreover, we examined whether a redox-based mechanism could be responsible for the apparent discrepancy between NO production and NO implication in IL-1 production under IFN gamma/TNF alpha and IFN gamma/TNF alpha/IL-1 beta treatments. Experiments with cysteine, which acts as a powerful reductant, suggest that the nitrosonium character of NO is involved in the NO-dependent pathway in IL-1 production.

Cells, Cultured↗
PubMed1997

Early functional effects of Clostridium difficile toxin A on human colonocytes.

BACKGROUND & AIMS: Previous in vitro studies have shown that Clostridium difficile toxin A is able to directly affect the intestinal epithelial barrier function. The aim of this study was to examine the early effects of toxin A on mucin exocytosis and determine whether this toxin can induce the production of the chemokine interleukin 8 (IL-8) from human colonic epithelial cells. METHODS: Two model systems were used: the HT29-CI.16E colonic goblet cell line and primary cultures of human normal colonocytes. RESULTS: Toxin A exerted a rapid and dose-related inhibition of stimulated mucin exocytosis without altering baseline (constitutive) mucin exocytosis from HT29-CI.16E cells. Toxin A was also able to induce the secretion of IL-8 from both HT29-CI.16E cells and primary cultures of human normal colonocytes, as early as 2-3 hours of incubation. CONCLUSIONS: The results show that while toxin A is able to down-regulate stimulated mucin exocytosis, it is able to up-regulate the secretion of an important chemoattractant chemokine, IL-8. These modifications illustrate the ability of colonocytes to recruit inflammatory and immune cells that will eventually bring about major mucosal damage.

Bacterial Toxins↗
PubMed1996

A redox-based mechanism for induction of interleukin-1 production by nitric oxide in a human colonic epithelial cell line (HT29-Cl.16E).

We evaluated the effects of two NO donors, sodium nitroprusside (SNP) and 3-morpholino-sydnonimine (SIN-1), characterized by alternative redox states, i.e. nitrosonium ion (NO+) and nitric oxide (NO.) respectively, on intracellular interleukin-1 (IL-1) production, by a human colonic epithelial cell line (HT29-Cl.16E). SNP was able to induce intracellular IL-1 alpha production up to 10 h incubation, in a dose-dependent manner. Several experiments provide evidence that the NO+ redox form, and not the free radical NO., is implicated in the IL-1 alpha production: (i) SIN-1, devoid of any NO+ character, led to a very weak IL-1 production as compared with SNP; (ii) the reductive action of a thiol such as cysteine on NO+ led to a dose-dependent increase in NO, concentration, measured as NO2-/NO3- accumulation, and to large decrease in IL-1 production. Dibutyryl cGMP had no effect on IL-1 production, this finding supporting the concept that a cGMP-independent pathway is involved in the intracellular signalling of NO+. Together these results point out that NO, depending on its redox form, is able to modulate IL-1 production in cultured colonic epithelial cells.

Cell Line↗
PubMed1996

Direct secretory effect of interleukin-1 via type I receptors in human colonic mucous epithelial cells (HT29-C1.16E).

The stable differentiated human colonic epithelial cell line, HT29-C1.16E, was used to study the effects of interleukin-1 (IL-1) on mucin exocytosis. The main findings include: (a) IL-1 stimulated a rapid release of mucin from filter grown HT29-C1.16E cells, this effect being dose related; (b) this secretory effect was abolished in the presence of the blocking monoclonal antibody M4 specific for IL-1 receptors type I, showing that IL-1 receptors type I mediated IL-1 action; (c) experiments based on chamber cultures showed that these receptors were located on the basolateral membranes of HT29-C1.16E cells; (d) finally, mRNA for IL-1 receptors type I were detected by reverse transcriptase-polymerase chain reaction in these cells. To extend these findings to the in vivo situation, the rapid stimulatory effect of IL-1 on mucin exocytosis may contribute to the wash out of noxious agents during mucosal inflammation.

Antibodies, Monoclonal↗
PubMed1995

Patterns of expression of lineage-specific markers during the in vitro-induced differentiation of HT29 colon carcinoma cells.

The four different cell types present in the mature colon, absorptive enterocytes, mucus-secreting goblet cells, Paneth cells, and enteroendocrine cells, are believed to derive from a common precursor, the stem cell, anchored near the base of the crypt. Stem cell descendants undergo several rounds of cell division, creating a pool of transit cells that are committed to differentiation. The mechanisms by which committed cells are allocated to the different cell lineages of the intestine are poorly understood. We have used the colon carcinoma cell line HT29 and Cl.16E cells, a clonal derivative of HT29 cells, to investigate the regulation and pattern of expression of several markers (MUC2, MUC3, carcinoembryonic antigen, and alkaline phosphatase) that are associated with a more differentiated phenotype and that, in the mature cells, are lineage restricted. HT29 cells can express, upon exposure to the appropriate inducers, distinct intestinal specific markers; they are, therefore, considered multipotent, similar to the stem cells of the crypt. Conversely, Cl.16E cells are lineage restricted and respond to cell contact inhibition by expressing a fully differentiated goblet cell phenotype. We show that, in HT29 cells, different inducers (12-O-tetradecanoylphorbol-13-acetate, forskolin, and sodium butyrate) modulate specific sets of markers. Forskolin induces the expression of both MUC2 and MUC3, whereas 12-O-tetradecanoylphorbol-13-acetate is capable of inducing only MUC2, and sodium butyrate, only MUC3 gene expression. Carcinoembryonic antigen, a marker common to enterocytes and goblet cells; can be induced by all the agents, whereas the alkaline phosphatase gene, the expression of which is characteristic of enterocytes, is responsive solely to sodium butyrate treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMed1994

Cyclic AMP-induced mucin exocytosis is independent of Cl- movements in human colonic epithelial cells (HT29-Cl.16E).

The human colonic epithelial goblet cell line HT29-Cl.16E was used to test whether stimulated Cl- transport is involved in the mucin exocytotic response to an increase in intracellular cyclic AMP by measuring in parallel the short-circuit current (Isc) and mucin exocytosis. Addition of 50 microM forskolin to HT29-Cl.16E cells resulted in a 2-fold stimulation of mucin release and an increase in Isc by 20 microA/cm2. To evaluate the requirement for cosecretion of Cl-, the Cl- flux was altered by three different manipulations: (1) Cl- in the medium was replaced by the poorly transported anion gluconate; (2) basolateral Cl- influx through the Na(+)-K(+)-2Cl- cotransporter was inhibited by bumetanide; and (3) an inward Cl- flux through the apical plasma membrane was generated by reversing the Cl- gradient. These manipulations did not change the forskolin-stimulated mucin release and thereby provide evidence that Cl- movements are not required for fusion of mucin granules with the plasma membrane.

Amphotericin B↗
PubMed1994

Interferon-gamma modulates cAMP-induced mucin exocytosis without affecting mucin gene expression in a human colonic goblet cell line.

The regulation of intestinal mucin secretion by cytokines, soluble factors released by mucosal activated immune cells, is so far unknown. The aim of the present study was (1) to investigate the regulatory effects of interferon-gamma on baseline and stimulated mucin secretion elicited by an increase in intracellular cAMP, either a short-term increase (induced by vasoactive intestinal peptide or by forskolin) or a long-term increase (cholera toxin-induced), and (2) to attempt to delineate the site of action of interferon-gamma. The in vitro model used was the human colonic goblet cell line Cl.16E, which has already been shown to respond to physiological secretagogues in terms of mucin secretion. We examined the effects of interferon-gamma 1) on mucin exocytosis, measured as release of [3H]glucosamine-labeled macromolecules trapped at the stacking/running gel interface of polyacrylamide gels, and 2) on mucin biosynthesis, examined at the RNA level using a cDNA probe directed to the MUC2 mucin gene. We demonstrated that, while interferon-gamma did not alter baseline Cl.16E mucin secretion and MUC2 gene expression, it strongly inhibited the protein kinase A-dependent secretory response to VIP, forskolin, or cholera toxin. However, interferon-gamma had no effect on the protein kinase A-dependent MUC2 over-expression induced by cholera toxin. We thus concluded that the target for interferon-gamma inhibition of cAMP-stimulated Cl.16E mucin secretion is distal to protein kinase A and might be a component of the exocytotic machinery. Together, our results establish interferon-gamma as a pharmacologically powerful tool to specifically inhibit stimulated secretory processes without affecting baseline secretion.

Blotting, Northern↗
PubMed1992

Cytokine effects in a human colonic goblet cell line. Cellular damage and its partial prevention by 5 aminosalicylic acid.

The aim of the present study was to investigate the effects of cytokines on intestinal goblet cells in vitro. For this purpose, we examined the effects of recombinant interferon gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) on the human colonic goblet cell line Cl.16E by morphological and kinetic studies, and by the assessment of mucus production during IFN-gamma/TNF-alpha treatment. Control cultures of Cl.16E cells grown on nitrocellulose filters formed monolayers of polarized goblet cells, which had kinetic characteristics similar to those of a differentiated epithelium in steady state. The combined action of IFN-gamma and TNF-alpha caused a dose-related cellular exfoliation, leading to the formation of a mucoid cap made of mucus and cellular debris. The remaining viable cells underlying the mucoid cap were cuboidal and devoid of mucus granules. A dose-related increase in cellular incorporation of [3H]thymidine was reactive to the cytokine-induced cell loss. The synergistic effects of IFN-gamm and TNF-alpha were found to be reversible when the cells were reincubated in a culture medium without cytokines. Furthermore, 5-aminosalicylic acid partially protected Cl.16E cells against cellular injury caused by IFN-gamma and TNF-alpha. On the whole, these morphological and kinetic findings argue that the changes induced in Cl.16E cells by IFN-gamma and TNF-alpha closely parallel those observed during the acute phase of ulcerative colitis, and show that these cytokines can regulate intestinal mucus production by modulating cellular exfoliation, thus leading probably to a reinforced protection of the damaged mucosa.

Aminosalicylic Acids↗
PubMed1990

Subsets of CD3+ (T cell receptor alpha/beta or gamma/delta) and CD3- lymphocytes isolated from normal human gut epithelium display phenotypical features different from their counterparts in peripheral blood.

Intestinal intraepithelial lymphocytes (IEL) were studied, after isolation in humans, for their surface antigens with a large variety of monoclonal antibodies. They show peculiar characteristics when compared with peripheral blood lymphocytes and intestinal lamina propria lymphocytes. Although a majority of human intraepithelial lymphocytes (IEL) express an alpha/beta type of T cell receptor (TcR), 13% express a gamma/delta TcR, a percentage which was significantly higher than that found in blood and in lamina propria. In contrast to observations in mice, there was no evidence that normal human TcR gamma/delta+ intestinal IEL might use preferential variable segments of gamma genes. About 10% of human intestinal IEL expressed the alpha chain but not the beta chain of CD8, thus resembling a subset of CD8 alpha+beta- IEL, which was recently described in mice and found to be of thymoindependent origin. In addition, 10% of human IEL had a unique phenotype of immature T cells, as they bore only CD7, but no other T cell or natural killer cell markers. Finally, even the major population of IEL which expressed the usual markers of the T cell lineage (CD3, TcR alpha/beta, CD2, CD4 or CD8 alpha/beta) differed from peripheral blood T lymphocytes by their peculiar expression of surface antigens associated with activation. Indeed, 80% of IEL were CD45R0+, CD45A-, but co-expression of CD11a, CD29 and LFA-3 was inconstant. In addition, 90% of IEL expressed HML-1.

Antigens, CD↗
PubMed1990

Infected cells and immune cells in the gastrointestinal tract of AIDS patients. An immunohistochemical study of 127 cases.

Human immunodeficiency virus (HIV) proteins were detected by immunohistochemistry in the duodenal and rectal mucosa of 30% of 127 AIDS patients studied. HIV-infected cells were present in the lamina propria in 95% of the positive biopsies. They were immune cells, either isolated lymphocytes and macrophages (1-4 per positive biopsy) or dendritic reticulum cells forming a network in the germinal centres of mucosal lymphoid follicles. HIV proteins were not found in the duodenal epithelium or in the superficial rectal epithelium. In two cases (5% of the positive biopsies), they were found in rectal glands: the HIV-infected cells could be either epithelial cells or immune cells. This study confirms that the gut can be a target organ for HIV and that HIV is mainly carried by gut immune cells. The phenotypic study of lymphoid populations and macrophages in the gut mucosa of AIDS patients showed an inverse CD4/CD8 ratio in the lamina propria, compared with normal controls. This was independent of the presence of HIV proteins and is probably responsible for the appearance of opportunistic infections in the mucosa. An increase in activated macrophages was also noted in the mucosa of AIDS patients.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Role of in vivo activated T cells in the mechanisms of villous atrophy in humans: study of allograft rejection.

Four children aged 6 months to 9 years received fully HLA-mismatched ABO identical small intestinal allografts. In order to monitor the rejection process and to study epithelial changes induced by intestinal T cells activated by an allogeneic reaction, iterative biopsies were performed through the ileal enterostomy and processed for histology and immunohistochemistry. Episodes of acute histological reaction were observed in all 4 patients between day 10 and 160. It was preceded by appearance of pericryptic CD3+CD4+ or CD8+ T cells of recipient origin, increasing numbers of which expressed CD25. Simultaneously, early epithelial changes were noted: increased HLA-DR expression by enterocytes and decreased mitotic rate as shown by decreased numbers of KI67+ cells in crypts. During acute histological rejection, massive infiltration of mucosa by CD25+CD3+ T-cells and activated macrophages (KIM6+CD25+), was associated with crypt necrosis and then, destruction of surface epithelium. Successful treatment of graft rejection episodes with antilymphocytic serum (2), anti-CD3 monoclonal antibody (2), anti-CD25 monoclonal antibody (1) resulted in a rapid decrease of CD3+ cells, a more progressive decrease of CD25+ and KIM6+ macrophages, reappearance of KI67+ cells in crypts followed after a variable delay by recovery of villous architecture. Chronic histological rejection was observed in 1 patient after 7 months. It was characterized by total villous atrophy, fibrosis, endarteritis, infiltration of lamina propria and epithelium by CD3+CD8+ cells, a small number of which CD25+, strong HLA-DR expression by crypt and surface epithelium, increased numbers of KI67 enterocytes. Altogether these data suggested that activated T cells can induce two types of villous atrophy.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrophy↗
PubMed1989

Immune cells associated with M cells in the follicle-associated epithelium of Peyer's patches in the rat. An electron- and immuno-electron-microscopic study.

Follicle-associated epithelium of Peyer's patches can be differentiated from nearby villous epithelium by the presence of M cells which are antigen-sampling epithelial cells, and by an increase in intraepithelial lymphocytes that are in close contact with M cells. The phenotype of the immune cells close to the M cells of the follicle-associated epithelium of rat Peyer's patches was determined by immunohistochemistry and compared with that of the intra-epithelial lymphocytes of the villous epithelium. Lymphoid T cells, predominantly of the cytotoxic/suppressor phenotype, were observed both in follicle-associated epithelium and in villous epithelium. Lymphoid B cells, mainly immunoblasts and plasma cells containing intracytoplasmic IgM, were present only in the follicle-associated epithelium, near M cells. Macrophages were also present, in contact with M cells, in follicle-associated epithelium, but not in villous epithelium. In addition, M cells bore Ia molecules on their apical membranes. These findings reinforce the concept of immune specialization of the follicle-associated epithelium, by demonstrating that this epithelium contains all the effector cells of immune responses.

Animals↗