首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
In vitro cell culture models used to study how Salmonella initiates disease at the intestinal epithelium would benefit from the recognition that organs and tissues function in a three-dimensional (3-D) environment and that this spatial context is necessary for development of cultures that more realistically resemble in vivo tissues/organs. Our aim was to establish and characterize biologically meaningful 3-D models of human colonic epithelium and apply them to study the early stages of enteric salmonellosis. The human colonic cell line HT-29 was cultured in 3-D and characterized by immunohistochemistry, histology, and scanning electron microscopy. Wild-type Salmonella typhimurium and an isogenic SPI-1 type three secretion system (TTSS) mutant derivative (invA) were used to compare the interactions with 3-D cells and monolayers in adherence/invasion, tissue pathology, and cytokine expression studies. The results showed that 3-D culture enhanced many characteristics normally associated with fully differentiated, functional intestinal epithelia in vivo, including better organization of junctional, extracellular matrix, and brush-border proteins, and highly localized mucin production. Wild-type Salmonella demonstrated increased adherence, but significantly lower invasion for 3-D cells. Interestingly, the SPI-I TTSS mutant showed wild-type ability to invade into the 3-D cells but did not cause significant structural changes to these cells. Moreover, 3-D cells produced less interleukin-8 before and after Salmonella infection. These results suggest that 3-D cultures of human colonic epithelium provide valuable alternative models to study human enteric salmonellosis with potential for novel insight into Salmonella pathogenesis.  相似文献   

2.
The colonic cells of the large intestine are one of the most proliferative tissues of the animal body. The pentose pathway has an essential role in cell division and growth being the only pathway forming ribose 5-P necessary for all nucleotide and nucleic acid sunthesis. The pentose pathway may also provide reducing potential as NADPH for biosynthesis and C-3- C-8 glycolyl compounds. The maximum catalytic capacities of the reactions of the non-oxidative pentose pathway for the conversion of ribose 5-P to hexose and triose phosphates by the proximal and distal colon under feeding and starvation regimes are among the highest in the animal body. The qualitative presence of the oxidative pentose pathway was assessed by measurement of the C-1/C-6 ratio value of 1.67-1.82. Enzymes of the F-type and L-type pentose pathways are present in colonocytes and their maximum catalytic activities in colonocyte cytosol are reported. The contribution of the F-type pentose cycle to the total glucose metabolism of colonocytes, measured by the specific yield method, is negligibly low (approximately 1.5%). Colonic epithelial cells use glucose at a high rate (7.1 +/- 0.33 mumol min-1g-1 dry wt) and 79% of the glucose is converted to lactate. Arabinose 5-P has an intermediary role in the formation of keto pentose, sedoheptulose and hexose phosphates from ribose 5-P by colonocyte cytosol. The intermediary and reaction products of [1-13C] ribose 5-P dissimilation by colonocytes is investigated by 13C NMR spectroscopy. The 13C positional isotope distributions show labelling of C-1 and C-3 of hexose 6-phosphates consistent with either the theoretical predictions of the F-type pentose pathway or of the activities of exchange reactions catalysed by transketolase and/or transaldolase. Measurements of exchange reactions showed that the C-1/C-3 labelling of these compounds is mostly, if not wholly, attributable to exchange catalysis by these group transferring enzymes. The results suggest that the F-type PC has little role in the glucose metabolism of colonocytes and pentose phosphate formation may thus occur by a contribution (approx 20% of the total glucose metabolism) by the alternate L-type pathway.  相似文献   

3.
Cryosections of normal colon (NC), tubular and villous adenomas (TA, VA), and variably differentiated colon adenocarcinomas (CA) were immunostained with monoclonal antibodies to α1−6 and αv, and β1−4 integrin subunits; select samples were stained for cytokeratin (Ck) 20 and villin. In NC, α2 staining was strongest in crypt cells; α1,3 and αv, and β1,3 and β4, and Ck 20 and villin predominated in superficial enterocytes. In TA and VA, monolayered glands showed integrin, Ck 20 and villin patterns that differed slightly from both crypt and superficial enterocytes. Complex glands in VA showed decreased integrin staining and basal polarization; Ck 20 and villin were strong only in luminal cells. CA showed overall weaker integrin staining than adenomas. Regardless of invasion depth, well formed malignant glands mimicked TA; pleomorphic glands mimicked VA with focal basal integrin polarization and solid clusters displayed scanty integrins, uneven Ck 20, and villin in occasional cells. Diverse integrins in crypt compared with superficial enterocytes reflect changing adhesive requirements as cells migrate and terminally differentiate. Decreasing expression and altered distribution of integrins, Ck 20 and villin noted in TA, VA, and in CA of increasing grade indicate that certain adhesive and cytoskeletal features more closely relate to glandular architecture than to depth of invasion.  相似文献   

4.
Summary In the colonic epithelium of the chicken, glycoconjugates have been studied by means of selected histochemical methods of light and electron microscopy. According to the results obtained, most of the colonic goblet cells contained acidic and neutral glycoconjugates with sulphate and vicinal diol groupings, -D-mannose and -D-glucose residues and sialic acid-galactose dimers. These goblet cells were found to undergo changes in histochemical reactivity during upward migration along the crypts; -D-mannose and -D-glucose residues and terminal sialic acidgalactose dimers increased in amount. The striated border of the colonic columnar cells has, likewise, been found to contain such glycoconjugates as were similar in reactivity to those of the goblet cells. The histophysiological significances of glycoconjugates involved in the chicken colonic epithelium have been discussed with special reference to the functional activities of the carbohydrates.  相似文献   

5.
Cells within the normal human colonic epithelium undergo a dynamic cycle of growth, differentiation, and death. The organotypic culture system of human fetal colonic epithelial cells seeded on top of collagen gels with embedded colonic fibroblasts allowed prolonged culture of the colonic epithelial cells (Kalabis J, Patterson MJ, Enders GM, Marian B, Iozzo RV, Rogler G, Gimotty PA, Herlyn M. FASEB J 17: 1115-1117, 2003). Herein, we have evaluated the role of endothelin-3 (ET3) and both cognate endothelin receptors (ETRA, ETRB) for human colonic epithelial cell growth and survival. ET3 was produced continuously by the fibroblasts as a result of adenovirus-mediated gene transfer. The presence and function of the endothelin receptors (ETRs) in epithelial cells was evaluated by [(3)H]thymidine incorporation using primary epithelial cells in monoculture and by immunohistochemistry on human fetal and adult paraffin-embedded tissues. In organotypic culture, ET3 increased the number of goblet cells but not of enteroendocrine cells. The increase in goblet cells was caused by prolonged cell survival and differentiation. The inhibition of both ETRA and ETRB significantly decreased the number of goblet cells and proliferation in epithelial cells, whereas the number of enteroendocrine cells remained unchanged. ET3 induced activation of IkappaB and MAPK in the epithelial cells, suggesting that these signaling pathways mediate its proproliferation and prosurvival activities. Our results demonstrate that ET3 is involved in regulating human colonic epithelial cell proliferation and survival, particularly for goblet cells, and may be an important component of colonic homeostasis.  相似文献   

6.
In the colonic epithelium of the chicken, glycoconjugates have been studied by means of selected histochemical methods of light and electron microscopy. According to the results obtained, most of the colonic goblet cells contained acidic and neutral glycoconjugates with sulphate and vicinal diol groupings, alpha-D-mannose and alpha-D-glucose residues and sialic acid-galactose dimers. These goblet cells were found to undergo changes in histochemical reactivity during upward migration along the crypts; alpha-D-mannose and alpha-D-glucose residues and terminal sialic acid-galactose dimers increased in amount. The striated border of the colonic columnar cells has, likewise, been found to contain such glycoconjugates as were similar in reactivity to those of the goblet cells. The histophysiological significances of glycoconjugates involved in the chicken colonic epithelium have been discussed with special reference to the functional activities of the carbohydrates.  相似文献   

7.
8.
9.
L Wang  Q Liu  JC Chen  YX Cui  B Zhou  YX Chen  YF Zhao  YM Li 《Biological chemistry》2012,393(7):641-646
Abstract Human islet amyloid polypeptide (hIAPP) shows an antimicrobial activity towards two types of clinically relevant bacteria. The potency of hIAPP varies with its aggregation states. Circular dichroism was employed to determine the interaction between hIAPP and bacteria lipid membrane mimic. The antimicrobial activity of each aggregate species is associated with their ability to induce membrane disruption. Our findings provide new evidence revealing the antimicrobial activity of amyloid peptide, which suggest a possible connection between amyloid peptides and antimicrobial peptides.  相似文献   

10.
Previously, we discovered a binding site for the Fc region of IgG in human small intestinal and colonic mucosa. The binding site (Fc gamma IBS) appeared to be primarily associated with goblet cells, to consist of greater than 200,000 Da and 78,000 Da components, and to be distinct from leukocyte FcR. In the present work, we used mAb made to colonocyte IgG-binding material to more accurately define the molecular structure and cellular locations of the Fc gamma IBS. In immunoblot and fast protein liquid chromatography analysis, the mAb revealed that the Fc gamma IBS consists of a 110,000- to 140,000-Da component in addition to the two components previously recognized. The greater than 200,000 component may be the critical component for IgG binding, inasmuch as mAb to it but not to the other two components inhibited binding of IgG to colonic sections in vitro. Used in immunoelectron microscopy, the mAb documented that the Fc gamma IBS is present in the endoplasmic reticulum of goblet cells, in the cytoplasmic matrix separating secretory granules of goblet cells, and within the granules themselves; occasionally it has the appearance of being secreted into the intestinal lumen with mucus. The Fc gamma IBS could not be solubilized from colonocyte homogenates by three different detergents, which suggests that it exists in complex with cytoskeletal elements. We speculate that the Fc gamma IBS aids in immunologic protection of the intestine by facilitating interaction between intestinal mucus and antigenic material in the lumen.  相似文献   

11.
12.
The amphibian intestinal epithelium provides an excellent aid to study the developmental pattern of protein synthesis during cell life. The metamorphosing tissue demonstrates a kaleidoscope of cell degeneration, proliferation and differentiation. These events occur at specific period in a synchronized cell population. Two-dimensional gel electrophoresis, together with histological studies, has been used to examine the changes in the patterns of protein synthesis during intestinal epithelium substitution in metamorphosing Alytes obstetricians larvae. Of the approximately 280 polypeptides detected by this method, 24 show major changes in their patterns of synthesis. Five polypeptides are only synthesized during the larval period and are characteristic of the primary epithelium. Six polypeptides are characteristic of the secondary intestinal epithelium, as they are only detected in the newly-metamorphosed juvenile. Four polypeptides of Mr 81,000, 78,000, 42,000 (pI, 5.1 and 6.2) are characteristic of the epithelium crisis, as they are only detected during climax. They may represent molecular markers of growing stem cells. On the other hand, two polypeptides, of Mr 66,500 and 63,500, are not synthesized during this critical period, but are synthesized before and after metamorphosis. Seven polypeptides show changes in the relative rate of their synthesis during metamorphosis of the intestinal epithelium. Among them, the protein of Mr 105,000 which presents two isoelectric variants (pI 5.5 and 5.55) is immunologically related to villin. Expression of this protein has been studied using immunoblotting of cell extracts onto nitrocellulose and immunodetection in tissue sections. The protein is localized in the brush border of primary and secondary epithelium.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

13.
Ionized forms of vanadium are known to exert diverse biological activities. Of particular interest in the inhibitory action of the vanadium ion on (Na+ + K+)-ATPase. This report describes another action of the vanadium ion on the rabbit colonic epithelium. Micromolar quantities of vanadate, applied to the serosal side of the isolated rabbit colonic epithelium, result in a stimulation of electrogenic chloride secretion by this epithelium. Sodium transport is unaffected by the vanadium ion in the concentrations used in this study. It is proposed that the vanadyl ion activates adenylate cyclase and thereby initiates subsequent secretory events.  相似文献   

14.
15.
Cytology of the human seminiferous epithelium   总被引:2,自引:0,他引:2  
The appearances in cytologic specimens of the principal cell types in the normal human seminiferous epithelium are described and illustrated. Sertoli cells, which are larger than spermatogenic cells, are characterized by a slightly basophilic, ill-defined cytoplasm of triangular, elongated or columnar shape; the cytoplasm may be vacuolated and may contain spermatozoa. The nuclei of Sertoli cells are round, with a uniformly finely granulated chromatin and a single nucleolus. Spermatogenic cells are round or oval and show scanty cytoplasm with deeper basophilia and well-defined cytoplasmic borders. Multinucleation is common in spermatogenic cells. The Sertoli cells constitute a very homogeneous cell population as compared to the spermatogenic cells, which show several distinct cell types (spermatogonia, primary and secondary spermatocytes, spermatids and spermatozoa) whose nuclear structures depend on the stage of meiosis. Both cell types may occur as naked nuclei. Some problems of cell classification are discussed.  相似文献   

16.
17.
The subunit polypeptides of human fibrinogen   总被引:10,自引:0,他引:10  
  相似文献   

18.
Gingival innate immunity has been studied by using biopsies and normal or transformed epithelial cell monolayers. To overcome individual biological variabilities and as a physiological alternative, we have proposed using a reconstructed tissue equivalent. In this study, we investigated the functionality and the stage of differentiation of a reconstructed human gingival epithelium. We also characterized this epithelium at the molecular level to investigate its differentiation stage compared with native human gingival epithelium. The expression levels and localization of markers related to proteins and lipids of well-differentiated stratified epithelium, such as cytokeratins, cornified envelope proteins and enzymes, or to factors in lipid synthesis and trafficking were examined. Immunohistochemistry revealed similar localization patterns in both types of epithelia and mRNA quantification showed a close resemblance of their expression profiles. We further revealed that, like native gingiva, reconstructed gingival epithelium was able to respond to pro-inflammatory or lipopolysaccharide stimuli by producing antimicrobial peptides hβD-2, hβD-3 or LL-37. Finally, we demonstrated that reconstructed human gingival epithelium, as a model, was good enough to be proposed as a functional equivalent for native human gingival epithelium in order to study the regulation of gingival innate immunity against periodontal infections. This investigation was supported by a grant from Pierre Fabre Oral Care.  相似文献   

19.
CD44 promotes resistance to apoptosis in murine colonic epithelium   总被引:3,自引:0,他引:3  
Dysregulated expression of CD44 isoforms occurs consistently in colon carcinogenesis, and this change occurs also in most other types of cancer. One of the basic features of malignant transformation is the acquisition of resistance to apoptosis. We previously found that the colonic epithelium of mice, deficient in CD44 is predisposed to apoptosis. In this study, we asked whether the expression of CD44 alters the response of the colon to an apoptotic stimulus, and what are the mechanisms involved. For this, we assessed the susceptibility of the murine colon to apoptosis by total body irradiation to induce apoptosis. Apoptotic and concomitant changes relevant to the mechanisms of apoptosis were monitored by molecular markers of apoptosis. We found enhanced susceptibility to apoptosis in CD44 deficient colonic epithelium based on an increase in the number of apoptotic bodies, and activation of caspase 3. This was not associated with alterations in proliferations as shown by comparable Ki-67 expression and BrdU labeling. Furthermore, upregulated active caspase 3 in CD44 deficient colon was accompanied by concomitant molecular alterations in caspase 9 and not caspase 8, and this indicated the involvement of the mitochondrial pathway in apoptosis execution. Overall, this is the first report demonstrating CD44 mediated resistance to apoptosis in the colonic epithelium in vivo. This implicates CD44 in promoting cell transformation into a malignant phenotype, in conjunction with other anti-apoptotic factors.  相似文献   

20.
1. The effects of fasting and fasting followed by refeeding on the relative activities of the pyruvate dehydrogenase (PDH) complex and the tricarboxylic acid (TCA) cycle in isolated rat colonocytes were estimated by the rate of production of 14CO2 from [1-14C]pyruvate and [3-14C]pyruvate, respectively. 2. Decarboxylation of pyruvate by the PDH complex exceeded that by the TCA cycle in both fasted and fasted/refed colonocytes, was higher in distal than in proximal colon, and was stimulated by refeeding following a fast. 3. Oxidation of pyruvate by both the PDH complex and the TCA cycle was inhibited by butyrate. 4. Propionate alone had no effect, but synergized with butyrate to further reduce pyruvate decarboxylation by the TCA cycle. 5. Preferential utilization of butyrate by proliferating colonic epithelial cells is postulated to maximize the energy yield and spare pyruvate and its precursors for alternative synthetic roles necessary for active cell division.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号