Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Iec”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 271 records · Page 15Linked to original sources
PubMed2001

Role of stem cell factor and c-kit signaling in regulation of fetal intestinal epithelial cell adhesion to fibronectin.

The interaction of stem cell factor (SCF) and c-kit is considered to be an important signaling event for the homeostasis of the epithelial barrier function in the intestinal tract. This study was designed to investigate the role of the SCF and c-kit signaling pathway in adhesion of intestinal epithelial cells (IECs) to fibronectin (FN) using primary cells. Fetal murine IECs were prepared from the small intestine of mouse fetus. The mRNAs coding for SCF in mesenchymes and c-kit in IECs were detected by reverse transcription-PCR. The expression of FN receptor VLA-5 on IECs was examined by flow cytometry. A cell adhesion assay showed that the stimulation of IECs with SCF increased the number of cells adhering to FN. Experiments using specific antibody against SCF indicated that this increase in cell adhesion was SCF-dependent. On the other hand, SCF did not influence the expression of VLA-5 on IECs. The IEC adhesion to FN was inhibited by specific antibody against the FN receptor (VLA-5), as well as competitive Arg-Gly-Asp (RGD) peptide. When alteration of intracellular signal transduction induced by SCF was examined, it was found that SCF stimulated a tyrosine-specific c-kit autophosphorylation cascade of IECs. Further, preincubation of IECs with an optimal concentration of genistein resulted in the inhibition of SCF-induced c-kit phosphorylation and adhesion of IECs to FN. These results suggested that adhesion of immature IECs to FN is regulated by activation of RGD-dependent VLA-5 through the SCF and c-kit signal transduction pathway. SCF, which may be produced by mesenchymes locally, is an important regulatory factor for the adhesion of immature IECs to basement membrane matrix via VLA-5 and FN interaction. This cytokine-regulated interaction between VLA-5 and FN may play an important role in the development and wound repair of the intestinal tract.

Animals↗
PubMed1999

Preferential enhancement of B cell IgA secretion by intestinal epithelial cell-derived cytokines and interleukin-2.

Intestinal epithelial cells (IEC) are known to secrete a number of important cytokines. Recently, we determined that IEC-derived IL-6 and TGF-beta could enhance IgA secretion and suppress IgM secretion by isolated mucosal B cells. However, since the IEC-derived cytokines must function in the context of locally produced T cell cytokines, the effect of IEC- and T cell-derived cytokines on mucosal B cell immunoglobulin secretion was determined. Using 4 day culture supernatants (IEC-SN) from the rat IEC-6 intestinal epithelial cell line and lipopolysaccharide (LPS) stimulated Peyer's patch or mesenteric lymph node B cells, the IEC- SN was found to act with IL-2 to greatly enhance IgA secretion but limit or suppress IgM secretion as compared to cultures of LPS stimulated B cells alone. However, neither IL-4, IL- 5, nor IFN-gamma affected IgA secretion with the IEC-SN. Depletion of the IEC-SN with specific anti-cytokine antibodies suggested that IEC-derived TGF-beta and IL-6 were both responsible for the enhancing effect along with IL-2 on IgA secretion, whereas IEC-derived TGF-beta alone limited or suppressed IgM secretion. These results suggest that cytokines derived from local IEC and T cells may create an environment which may contribute to the preferential enhancement of IgA secretion seen in mucosal tissues.

Animals↗
PubMed1998

Gap junctional communication between murine macrophages and intestinal epithelial cell lines.

In intestinal inflammation, inflammatory cells infiltrate the submucosa and are found juxtaposed to intestinal epithelial cell (IEC) basolateral membranes and may directly regulate IEC function. In this study we determined whether macrophage (M phi), P388D1 and J774A.1, are coupled by gap junctions to IEC lines, Mode-K and IEC6. Using flow cytometric analysis, we show bi-directional transfer of the fluorescent dye, calcein (700 Da) between IEC and M phi resulting in a 3.5-20-fold increase in recipient cell fluorescence. Homocellular and heterocellular dye transfer between M phi and/or IEC was detected in cocultures of P388D1, J774A.1, Mode-K, IEC6 and CMT93. However, transfer between P388D1 and Mode-K was asymmetrical in that transfer from P388D1 to Mode-K was always more efficient than transfer from Mode-K to P388D1. Dye transfer was strictly dependent on IEC-M phi adhesion which in turn was dependent on the polarity of IEC adhesion molecule expression. Both calcein dye transfer and adhesion were inhibited by the addition of heptanol to cocultures. Furthermore we demonstrate both IEC homocellular, and M phi-IEC heterocellular propagation of calcium waves in response to mechanical stimulation, typical of gap junctional communication. Finally, areas of close membrane apposition were seen in electron micrographs of IEC-M phi cocultures, suggestive of gap junction formation. These data indicate that IEC and M phi are coupled by gap junctions suggesting that gap junctional communication may provide a means by which inflammatory cells might regulate IEC function.

Animals↗
PubMed2005

Na+,K+-ATPase activity is inhibited in cultured intestinal epithelial cells by endotoxin or nitric oxide.

Na+K+-ATPase is an important enzyme serving vital functions in various mammalian tissues, including the intestine. We have previously documented that endotoxin (LPS) and nitric oxide (NO) can induce enterocyte injury in vitro. To examine whether alterations Na+,K+-ATPase activity might be involved in LPS- or NO-induced enterocyte dysfunction, we carried out four series of experiments. The first set of experiments documented that LPS decreases IEC-6 Na+,K+-ATPase activity at concentrations as low as 0.10 microg/ml. The second set of experiments tested whether exposure of IEC-6 cells to the exogenous NO donor, S-Nitroso-N-acetylpenicillamine (SNAP), would decrease IEC-6 Na+,K+-ATPase activity. The results of these experiments documented that SNAP significantly decreased IEC-6 Na+,K+-ATPase activity in a dose-dependent fashion at a threshold inhibitory concentration of 0.1 mM, and there was an inverse correlation between Na+,K+-ATPase activity and NO concentrations in the medium. Since enterocytes contain iNOS, and LPS can increase iNOS activity, the third set of experiments examined the relationship between LPS-induced inhibition of Na+),K+-ATPase activity and NO production by the IEC-6 cells. These results showed that LPS increased IEC-6 NO production in both a dose- and time-dependent fashion and an inverse correlation existed between LPS-induced NO production and decreased Na+,K+-ATPase activity. Addition of the NOS inhibitor, L-NNA, prevented the LPS-induced decrease in Na+,K+ATPase activity, suggesting that NO is involved in the decrease of Na+,K+-ATPase activity observed in the IEC-6 cells incubated with LPS. One mechanism by which the increased NO concentrations could have contributed to the decrease in Na+,K+ATPase activity, after the addition of LPS or SNAP, is via the production of peroxynitrite during the reaction of NO with superoxide. This notion was supported by studies showing that SNAP- and LPS-induced decreases in IEC-6 Na+,K+-ATPase activity could be blocked by adding superoxide dismutase to the medium. The last set of experiments tested whether the inhibition of Na+,K+-ATPase activity with the specific Na+,K+-ATPase inhibitor ouabain would increase the permeability of an IEC-6 monolayer. IEC-6 monolayer permeability was increased by ouabain, but only at a high concentration. In conclusion, these studies indicate that LPS or the NO donor, SNAP, inhibit Na+,K+-ATPase activity and this inhibition is at least partly related to peroxynitrite production. These studies also suggest that LPS-induced NO production by the IEC-6 cells decreases IEC-6 Na+,K+-ATPase activity in an autocrine fashion.

Animals↗
PubMed2006

Experimental exposure of arsenic in cultured rat intestinal epithelial cells and cell line: toxicological consequences.

Arsenic is a naturally occurring metalloid and the drinking water contamination by inorganic arsenic remains a major public health problem. The trivalent arsenic (arsenite) is more toxic than the pentavalent form (arsenate), and is known to cause gastrointestinal toxicity. Specific immortal cell lines are considered to be suitable for toxicity screening and testing of chemicals as they are easy to handle and possess most of the biochemical pathways present in the corresponding cells present in vivo. The present study was designed to evaluate and compare the in vitro toxicity of arsenite on rat intestinal epithelial cell line (IEC-6) and primary cultures of rat intestinal epithelial cells (IEC). To evaluate in vitro toxicity, cultures of IEC and IEC-6 cells were assessed for viability, morphometric analysis, membrane transport enzymes and structural constituents for membrane damage, dehydrogenase activity test for respiratory and energy producing processes and esterase activity test for intra and extra cellular degradation, following the post exposures to arsenite (0-20 ppm). Significantly similar concentration-dependent changes in these toxicity-screening parameters in IEC and IEC-6 were observed. Highest tested concentration of arsenite (20 ppm) was found to be detrimental in both IEC and IEC-6. Furthermore, to evaluate arsenite toxicity in epithelial cells of rat intestine, intestinal loops were filled with arsenite solutions and incubated for 30 min in situ. In situ studies also showed a significant arsenite concentration-dependent decline in epithelial cell membrane transport enzyme activities and total hexose and sialic acid contents. Concomitant release of membrane enzymes, hexose and sialic acid in the intestinal luminal fluid following higher arsenite exposures further indicated partial membrane damage. Similar morphological changes in IEC and IEC-6 were also evident. These findings also suggest that IEC-6 cell lines are suitable for initial screening of gastrointestinal cellular toxicity caused by arsenite.

Animals↗
PubMed2001

Characterization of conditions for the primary culture of human small intestinal epithelial cells.

Intestinal epithelial cells (IECs) are important for many aspects of gut physiology and pathology. Different approaches have been tried for the primary culture of human IECs, with varying degrees of success, as apoptosis easily occurs. Our aim was to develop a method for primary culture of human IECs from biopsy material. IECs and Lamina propria (LP) cells were liberated from duodenal biopsies obtained from subjects undergoing routine endoscopy for clinical investigations, whose small bowel was macroscopically normal. IECs were cultured on collagen membranes in a 12-well tissue culture cluster, with LP cells and allogeneic Epstein-Barr Virus (EBV)-transformed B lymphocytes (allo-B cells) underneath, in the well. Cultured IECs were characterized by light and confocal microscopy. Cytokine levels in culture supernatants were measured by ELISA. Cells showed the columnar morphology of IECs, even after several days in culture. Best results were obtained from IECs cultured above both LP and allo-B cells. IECs did not form monolayers as do transformed epithelial cell lines, but they did preserve their original cell-cell contacts. Analysis of culture supernatants showed that IL-10 was produced by IECs initially, but IL-1ra was produced by LP cells in the underlying wells with increasing time in culture. Very little IL-1 beta was produced from any cultures. These results show that IECs can be isolated and maintained in primary culture for a short while, which could open new possibilities for research using patient material instead of cell lines.

Biomarkers↗
PubMed2001

Differential responsiveness of intestinal epithelial cells to 1,25-dihydroxyvitamin D3--role of protein kinase C.

Non-transformed rat intestinal epithelial cell (IEC) lines were used to study the action of 1,25-dihydroxyvitamin D(3) (1,25(OH)2D) in the intestine. The capacity of 1,25(OH)2D to increase the expression of the cytochrome P450 component of the vitamin D 24-hydroxylase (CYP24) was determined in IEC-6 and IEC-18 cell lines. In IEC-6 cells, which are derived from crypt cells isolated from the whole small intestine, 1,25(OH)2D markedly increased expression of CYP24 protein and mRNA within 12 h. In contrast, in IEC-18 cells, which are derived from crypt cells from the ileum only, 1,25(OH)2D did not increase expression of CYP24 until 24-48 h. The maximal levels of CYP24 mRNA seen in the IEC-18 cells were only 31% of the maximal levels seen in the IEC-6 cells. In the presence of 1,25(OH)2D, phorbol esters rapidly increased CYP24 mRNA levels in IEC-18 cells from almost undetectable to levels seen in IEC-6 cells. Protein kinase inhibitors abolished the stimulation by 1,25(OH)2D and by phorbol esters in both cell lines. Stimulation of mRNA levels by phorbol esters required new protein synthesis but stimulation by 1,25(OH)2D did not. These studies demonstrated that the rapid action of 1,25(OH)2D in IEC-6 cells is related to the activation of protein kinase C, an event which is missing in the IEC-18 cells. This differential response to 1,25(OH)2D probably takes place at a post-receptor site, since the number of vitamin D receptors in each cell line was found to be similar.

Animals↗
PubMed2001

Decreased expression of Toll-like receptor-4 and MD-2 correlates with intestinal epithelial cell protection against dysregulated proinflammatory gene expression in response to bacterial lipopolysaccharide.

The lumenal surface of the colonic epithelium is continually exposed to Gram-negative commensal bacteria and LPS. Recognition of LPS by Toll-like receptor (TLR)-4 results in proinflammatory gene expression in diverse cell types. Normally, however, commensal bacteria and their components do not elicit an inflammatory response from intestinal epithelial cells (IEC). The aim of this study is to understand the molecular mechanisms by which IEC limit chronic activation in the presence of LPS. Three IEC lines (Caco-2, T84, HT-29) were tested for their ability to activate an NF-kappaB reporter gene in response to purified, protein-free LPS. No IEC line responded to LPS, whereas human dermal microvessel endothelial cells (HMEC) did respond to LPS. IEC responded vigorously to IL-1beta in this assay, demonstrating that the IL-1 receptor signaling pathway shared by TLRs was intact. To determine the reason for LPS hyporesponsiveness in IEC, we examined the expression of TLR4 and MD-2, a critical coreceptor for TLR4 signaling. IEC expressed low levels of TLR4 compared with HMEC and none expressed MD-2. To determine whether the low level of TLR4 expression or absent MD-2 was responsible for the LPS signaling defect in IEC, the TLR4 or MD-2 gene was transiently expressed in IEC lines. Transient transfection of either gene individually was not sufficient to restore LPS signaling, but cotransfection of TLR4 and MD-2 in IEC led to synergistic activation of NF-kappaB and IL-8 reporter genes in response to LPS. We conclude that IEC limit dysregulated LPS signaling by down-regulating expression of MD-2 and TLR4. The remainder of the intracellular LPS signaling pathway is functionally intact.

Antigens, Surface↗
PubMed1995

Donor-specific cytotoxicity induced by allogeneic intestinal epithelial cells in a sponge matrix model.

Small intestinal epithelial cells (IEC) constitutively express MHC class II molecules. However, little is known about the role of IEC in intestinal allograft rejection. The present study examined whether IEC can induce the development of cytotoxic T cells in vivo using a sponge matrix model. IEC isolated from ACI (RT1a) rats were injected into polyurethane sponges implanted i.p. in Lewis (RT1(1)) rats. Sponge grafts with ACI splenocytes or Lewis IEC were used as controls. The sponge grafts were removed and sponge-infiltrating cells (SIC) were harvested on post-operative days (POD) 7, 10, and 14. The phenotype of SIC was determined by FACS analysis and the cell-mediated cytotoxicity was measured using a chromium relapse assay. Non-specific inflammatory cells accumulated in the IEC sponge allografts during the first 10 days. By POD 14, however, 61% of SIC were T lymphocytes and 36% expressed cytotoxic T cell marker (OX-8). The cytotoxicity in IEC sponge allografts was detectable on POD 7 and POD 10, and markedly elevated on POD 14. The cytotoxicity induced by allogeneic splenocytes appeared in the sponge grafts on POD 7, peaked on POD 10, and declined thereafter. The allospecific cytotoxicity induced by IEC was dependent on host macrophages as pretreatment of animals with gadolinium, a rare earth metal that inactivates macrophages, abrogated the induction of cytotoxicity. We conclude that: (1) the migration and maturation of cytotoxic T cells can be induced in vivo by IEC and (2) IEC may contribute to the increased severity of intestinal rejection through interaction with macrophages.

Animals↗
PubMed2002

Expansion of CD8+ T cells with regulatory function after interaction with intestinal epithelial cells.

BACKGROUND & AIMS: Regulatory T cells play a role in the control of immune responses in the intestinal mucosa and their absence may predispose to inflammatory bowel disease (IBD). We have previously shown that T cells activated by intestinal epithelial cells (IECs) are suppressive in function. Our goal was to characterize the phenotype and function of T cells proliferating after interaction with IECs. METHODS: Irradiated human IECs, isolated from normal resection specimens, were cultured with carboxy fluorescein succinimidyl ester (CFSE) labeled T cells. Flow cytometric analysis of T cells was performed at days 5-10. CD8+ T cells proliferating in culture with IECs were sorted and added to suppressive assays. RESULTS: The precursor frequency of T cells proliferating in response to IECs ranged from 0.3%-0.9%. Several subpopulations were shown to proliferate (CD8+CD28-/CD8+CD28+/CD4+CD25+), but one population (CD8+CD28-CD101+CD103+) appeared to be dependent on contact with the CD8 ligand gp180. After sorting, culture in the presence of interleukin (IL)-7 and IL-15 allowed for the generation of cell lines. IEC-activated CD8+ T cells, but not nonactivated CD8+ T cells, were suppressive in function. Suppression belonged to the CD101+CD103+ subset of IEC-activated CD8+ T cells and appeared to require cell contact. CD8+ lamina propria T cells also showed suppressive function, suggesting the presence of CD8+ regulatory T cells in the mucosa. CONCLUSIONS: IECs are able to induce the proliferation of a small fraction of CD8+ peripheral T cells. The CD8+CD28- subset of IEC-activated CD8+ T cells, which express CD101 and CD103, interacts with IECs through gp180 and has regulatory function.

Antigens, CD↗
PubMed2000

Primary murine small intestinal epithelial cells, maintained in long-term culture, are susceptible to rotavirus infection.

We describe a method for long-term culture of primary small intestinal epithelial cells (IEC) from suckling mice. IEC were digested from intestinal fragments as small intact units of epithelium (organoids) by using collagenase and dispase. IEC proliferated from organoids on a basement-membrane-coated culture surface and remained viable for 3 weeks. Cultured IEC had the morphologic and functional characteristics of immature enterocytes, notably sustained expression of cytokeratin and alkaline phosphatase. Few mesenchymal cells were present in the IEC cultures. IEC were also cultured from adult BALB/c mice and expressed major histocompatibility complex (MHC) class II antigens for at least 48 h in vitro. Primary IEC supported the growth of rhesus rotavirus (RRV) to a greater extent than a murine small intestinal cell line, m-IC(cl2). Cell-culture-adapted murine rotavirus strain EDIM infected primary IEC and m-IC(cl2) cells to a lesser extent than RRV. Wild-type EDIM did not infect either cell type. Long-term culture of primary murine small intestinal epithelial cells provides a method to study (i) virus-cell interactions, (ii) the capacity of IEC to act as antigen-presenting cells using a wide variety of MHC haplotypes, and (iii) IEC biology.

Adaptation, Physiological↗
PubMed2002

Activation of caspases in intestinal villus epithelial cells of normal and nematode infected rats.

BACKGROUND: Small intestinal epithelial cells (IEC) show apoptosis in physiological turnover of cells and in certain inflammatory diseases. AIMS: To investigate the role of caspases in the progression of IEC apoptosis in vivo. METHODS: IEC were separated along the villus-crypt axis from the jejunum of normal and Nippostrongylus brasiliensis infected rats at 4 degrees C. Caspases were examined by a fluorometric assay method, histochemistry, and immunoblotting. RESULTS: Villus cell rich IEC from normal rats exhibited a high level of caspase-3-like activity whereas activities of caspase-1, -8, and -9 were negligible. Immunoblotting analysis of villus cell rich IEC revealed partial cleavage of procaspase-3 into a 17 kDa molecule as well as cleavage of a caspase-3 substrate, poly(ADP-ribose) polymerase (PARP), whereas in crypt cell rich IEC, caspase-3 cleavage was less significant. Caspase-3 activity was also observed histochemically in villus epithelium on frozen sections of the normal small intestine. IEC prepared at 4 degrees C did not reveal nuclear degradation whereas subsequent incubation in a suspension at 37 degrees C induced intense nuclear degradation within one hour in accordance with increases in active caspase-3. This apoptosis was partially suppressed by the caspase inhibitor Z-VAD-fmk. Nematode infected animals showed villus atrophy together with significant increases in levels of caspase-3 in IEC but not of caspase-1, -8, or -9. CONCLUSION: Caspase-3 may have an important role in the physiological replacement of IEC as well as in progression of IEC apoptosis induced by nematode infection.

Animals↗
PubMed1992

Relationship between inhibitor of extrathyroidal 5'-deiodinase activity and serum free fatty acid in children with nonthyroidal illness and acute ketosis.

To clarify whether serum free fatty acid (FFA) is an inhibitor of extrathyroidal conversion (IEC) of thyroxine (T4) to thyronine (T3), we measured the concentration of FFA, IEC activity and thyroid hormones in normal subjects, acute ketotic children and children with low T3 syndrome due to nonthyroidal illness (NTI). Iodothyronine (I) 5'-deiodinase activity was assayed with reverse triiodothyronine (rT3) as substrate and liberated 125I-was measured. The IEC was determined by the inhibition of I 5'-deiodination by ether extract of sera or standard oleate solution. IEC values were represented as mM oleate. The serum concentration of FFA was 0.470 +/- 0.117 (SD) mM in 11 normal subjects, and it was significantly higher (1.242 +/- 0.248 mM; P < 0.01) in 10 acute ketotic children and in 7 samples from 6 NTI children (0.904 +/- 0.530 mM; P < 0.05). In contrast, there was no difference in IEC among three groups (normal subject, 0.451 +/- 0.069 mM; acute ketosis, 0.437 +/- 0.040 mM; NTI, 0.465 +/- 0.224 mM). No correlations were found between IEC activity and the serum FFA concentration or thyroid hormones in 28 samples from three groups. The sequential changes in serum thyroid hormones, FFA and IEC in 3 of 6 NTI children revealed no consistent relationship. Furthermore, one NTI child had significantly high IEC (> 1.000 mM) but its serum FFA (1.182 mM) was below the mean value for the acute ketotic group. These results indicate that 1) many NTI patients may bear no relation to IEC and 2) IEC may not be caused by serum FFA only but includes several factors.

Acute Disease↗
PubMed2006

Th2 cytokines down-regulate TLR expression and function in human intestinal epithelial cells.

TLRs serve important immune and nonimmune functions in human intestinal epithelial cells (IECs). Proinflammatory Th1 cytokines have been shown to promote TLR expression and function in IECs, but the effect of key Th2 cytokines (IL-4, IL-5, IL-13) on TLR signaling in IECs has not been elucidated so far. We stimulated human model IECs with Th2 cytokines and examined TLR mRNA and protein expression by Northern blotting, RT-PCR, real-time RT-PCR, Western blotting, and flow cytometry. TLR function was determined by I-kappaBalpha phosphorylation assays, ELISA for IL-8 secretion after stimulation with TLR ligands and flow cytometry for LPS uptake. IL-4 and IL-13 significantly decreased TLR3 and TLR4 mRNA and protein expression including the requisite TLR4 coreceptor MD-2. TLR4/MD-2-mediated LPS uptake and TLR ligand-induced I-kappaBalpha phosphorylation and IL-8 secretion were significantly diminished in Th2 cytokine-primed IECs. The down-regulatory effect of Th2 cytokines on TLR expression and function in IECs also counteracted enhanced TLR signaling induced by stimulation with the hallmark Th1 cytokine IFN-gamma. In summary, Th2 cytokines appear to dampen TLR expression and function in resting and Th1 cytokine-primed human IECs. Diminished TLR function in IECs under the influence of Th2 cytokines may protect the host from excessive TLR signaling, but likely also impairs the host intestinal innate immune defense and increases IEC susceptibility to chronic inflammation in response to the intestinal microenvironment. Taken together, our data underscore the important role of Th2 cytokines in balancing TLR signaling in human IECs.

Cell Line, Tumor↗
PubMed2005

[An experimental study of the effect of IL-2 on the growth of irradiated intestinal epithelial cells].

AIM: To observe the effect of ionizing radiation on intestinal epithelial cells 6 (IEC-6) and the effect of IL-2 on the proliferation and recovery of radiation-injured IEC-6 cells. METHODS: IEC-6 cells exposed to 4, 8 and 12 Gy gamma ray were analyzed with MTT colorimetry, light microscopy, electron microscopy, DNA gel electrophoresis and flow cytometry at 3, 6, 9, 12 hours and 1, 2, 3 days after radiation. Proliferation of 8 Gy gamma ray-irradiated IEC-6 cells which was treated with IL-2 was detected by MTT colorimetry at 3, 6, 9, 12 and 24 hours after irradiation. RESULTS: Proliferation of IEC-6 decreased with the increased dose of gamma ray radiation. Apoptotic IEC-6 cells increased apparently at 24 hours after radiation with 8.0 Gy gamma ray, IL-2 could enhance the proliferation of irradiated IEC-6 cells (especially at concentration of 1 x 10(5) U/L) in a dose-dependent manner. CONCLUSION: 4-12 Gy of gamma ray radiation can reduce the proliferation and cause apoptosis of IEC-6 cells. IL-2 can accelerate proliferation of irradiated IEC-6 cells and protect IECs from ionization radiation injury.

Animals↗
PubMedDate not supplied

Stunting syndrome in turkey poults: isolation and identification of the etiologic agent.

Stunting syndrome (SS) is an enteric disease of turkey poults that causes high morbidity including reduced growth, impaired feed efficiency, and diarrhea. The etiologic agent of this disease has not been previously reported. The objectives of the present study were to identify, isolate, and purify the etiologic agent of SS. Day-old poults were orally inoculated with a SS-inducing inoculum. The intestinal epithelial cells (IECs) were isolated on the fourth day postinoculation. The IECs were lysed and filtered through 0.2-, 0.1-, and 0.02-micron filters. The cell lysate filtrate (0.1 micron) was subjected to density gradient ultracentrifugation. Intact IECs, filtrates from IECs (0.2, 0.1, and 0.02 micron ), and IEC lysate fractions from gradients (FRG) were used as inocula to infect day-old turkey poults. The weight gain, jejunal maltase activity, and gross intestinal lesions were used as the parameters of evaluation. Weight gain and maltase activity were reduced (P = 0.001) by the isolated IECs, 0.2 and 0.1 micron filtrates, and FRG when compared with corresponding controls. IEC lysate filtrate (0.1 micron) and FRG were examined under transmission electron microscope (EM). Enveloped, pleomorphic particles varying in size from 60 to 95 nm were observed and termed stunting syndrome agent (SSA). Primary cultures of turkey IECs were used to further isolate and propagate the SSA. Following the fifth passage in the turkey IECs, the cell lysate induced SS in day-old poults. SSA particles were observed under EM after the fifth passage. The results of this study provide evidence that a viral agent has been isolated and identified from IECs of SS-infected poults and is the etiologic agent of SS.

Animals↗
PubMed1995

Intestinal epithelial cells down-regulate macrophage tumor necrosis factor-alpha secretion: a mechanism for immune homeostasis in the gut-associated lymphoid tissue.

BACKGROUND: The gut lumen contains more than 10(6) organisms per gram of luminal contents. The mechanisms that limit the response of macrophages in the lamina propria to these microbial antigens are unknown, although an intrinsic defect in this mechanism may contribute to the development of inflammatory bowel disease. Intestinal epithelial cells (IEC) may play an important role in mediating tonic down-regulation of local immune cell activation. The purpose of this study was to discern whether IEC might modulate macrophage activation in response to a variety of microbial stimuli. METHODS: Thioglycollate-elicited murine peritoneal macrophages were activated by endotoxin, zymosan, Escherichia coli, and Candida albicans in the presence or absence of IEC from the rat intestinal epithelial cell line IEC-6. Macrophage tumor necrosis factor-alpha (TNF-alpha) secretion was determined by enzyme-linked immunosorbent assay. RESULTS: Lipopolysaccharide or zymosan-activated macrophages in coculture with IEC secreted significantly less TNF-alpha than macrophages cultured alone. The inhibitory effect of the IEC was dependent on their activation by lipopolysaccharide. Interleukin-1 alpha production was not affected. IEC-mediated suppression of macrophage TNF-alpha secretion was reversed by indomethacin but not by neutralizing antibody to TGF-beta. CONCLUSIONS: Lipopolysaccharide-activated IEC down-regulate macrophage TNF-alpha secretion in response to microbial stimuli through a prostanoid-mediated mechanism. IEC may mediate tonic down-regulation of immune cell activation in the gut-associated lymphoid tissue and may thereby regulate local and systemic inflammatory responses.

Animals↗
PubMed2001

p53-dependent radiation-induced crypt intestinal epithelial cells apoptosis is mediated in part through TNF-TNFR1 system.

Radiation induces apoptosis of crypt intestinal epithelial cells (IEC) through a pathway that is largely dependent on p53. However, exactly how p53 mediates IEC apoptosis is unclear. Studies in vitro suggest that one mechanism by which p53 mediates apoptosis is through its ability to transactivate members of the TNF receptor family of 'Death Receptors'. Here, we examined the role of one of its member, TNF receptor type 1 (TNFR1), in an in vivo model of p53-dependent radiation-induced IEC apoptosis. We demonstrate that mice genetically engineered to be deficient in TNF receptor type 1 (TNFR1(-/-)) and mice injected with TNFR1-fusion chimeric protein (TNFR1-Fc; a competitive inhibitor of TNFR1) were partially protected (30-40%) from p53-dependent radiation-induced IEC apoptosis. However, we found no evidence to support the possibility p53 transcriptionally regulates the expression of TNFR1 nor increases the susceptibility of IEC to TNF-mediated apoptosis. Interestingly, we found that injection of TNF readily induced IEC apoptosis and that radiation induced a p53-dependent increase in the intestinal level of TNF. Furthermore, injection of a neutralizing anti-TNF mAb reduced p53-dependent radiation-induced IEC apoptosis by approximately 60%. Overall, these results suggest that p53-dependent radiation-induced IEC apoptosis is mediated in part through ability of p53 to regulate TNF, which subsequently induces IEC apoptosis through TNFR1.

Animals↗