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Fang SB, Schüller S, Phillips AD. Human Intestinal In Vitro Organ Culture as a Model for Investigation of Bacteria–Host Interactions. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/j.jecm.2013.02.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Lu L, Li T, Williams G, Petit E, Borowsky M, Walker WA. Hydrocortisone induces changes in gene expression and differentiation in immature human enterocytes. Am J Physiol Gastrointest Liver Physiol 2011; 300:G425-32. [PMID: 21148402 PMCID: PMC3064117 DOI: 10.1152/ajpgi.00011.2010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
It is known that functional maturation of the small intestine occurring during the weaning period is facilitated by glucocorticoids (such as hydrocortisone, HC), including an increased expression of digestive hydrolases. However, the molecular mechanisms are not well understood, particularly in the human gut. Here we report a microarray analysis of HC-induced changes in gene expression in H4 cells (a well-characterized human fetal small intestinal epithelial cell line). This study identified a large number of HC-regulated genes, some involved in metabolism, cell cycle regulation, cell-cell or cell-extracellular matrix communication. HC also regulates the expression of genes important for cell maturation such as development of cell polarity, tight junction formation, and interactions with extracellular matrices. Using human small intestinal xenografts, we also show that HC can regulate the expression of genes important for intestinal epithelial cell maturation. Our dataset may serve as a useful resource for understanding and dissecting the molecular mechanisms of intestinal epithelial cell maturation.
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Affiliation(s)
- Lei Lu
- Developmental Gastroenterology Laboratory, Massachusetts General Hospital for Children, Boston, USA.
| | - Tiantian Li
- 1Developmental Gastroenterology Laboratory, Massachusetts General Hospital for Children, Boston;
| | | | - Elizabeth Petit
- 1Developmental Gastroenterology Laboratory, Massachusetts General Hospital for Children, Boston;
| | - Mark Borowsky
- 3Department of Molecular Biology, Massachusetts General Hospital and Department of Genetics, Harvard Medical School, Boston, Massachusetts; and
| | - W. Allan Walker
- 1Developmental Gastroenterology Laboratory, Massachusetts General Hospital for Children, Boston;
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Lu L, Khan A, Walker WA. ADP-ribosylation factors regulate the development of CT signaling in immature human enterocytes. Am J Physiol Gastrointest Liver Physiol 2009; 296:G1221-9. [PMID: 19359423 PMCID: PMC2697949 DOI: 10.1152/ajpgi.90686.2008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Diarrheal disease is a major cause of morbidity and mortality in infants and children worldwide. Evidence suggests that the interaction of immature human enterocytes with bacteria and their enterotoxins may account for the increased susceptibility of neonates to diarrheal diseases. However, the precise mechanisms that contribute to the excessive response to cholera toxin by the immature gut are largely unknown. Our aim was to characterize the cellular/molecular changes in Gs(alpha) during gut development. In this study, a colonic human epithelial cell line (T84) was used as representative of a mature enterocyte and a human fetal primary small intestinal cell line (H4) as representative of an immature enterocyte. Using our cell culture model of human intestinal development, we provide consistent evidence that cholera toxin (CT)-mediated Gs(alpha) activation in fetal enterocytes differs from that of mature enterocytes, and the difference may be related to ADP-ribosylation factor (ARF) interaction with the CT-signaling process. Here we demonstrated that ARF1 may play a critical role in clathrin-mediated CT trafficking through the endoplasmic reticulum and Golgi and that ARF6 may facilitate clathrin-mediated CT endocytosis that leads to enhanced Gs(alpha) activation by CT. Collectively, these findings support our hypothesis that there is a developmentally regulated intestinal cellular response to bacterial exotoxins involving complex cellular events that accounts for the increased incidence and severity of toxogenic diarrhea during infancy.
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Affiliation(s)
- Lei Lu
- Developmental Gastroenterology Lab., Massachusetts General Hospital for Children, Charlestown, MA 02129-4404, USA.
| | - Abdullah Khan
- Developmental Gastroenterology Laboratory, Massachusetts General Hospital for Children, Boston, Massachusetts; The Aga Khan University Hospital, Karachi, Pakistan
| | - W. Allan Walker
- Developmental Gastroenterology Laboratory, Massachusetts General Hospital for Children, Boston, Massachusetts; The Aga Khan University Hospital, Karachi, Pakistan
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Lu L, Bao Y, Khan A, Goldstein AM, Newburg DS, Quaroni A, Brown D, Walker WA. Hydrocortisone modulates cholera toxin endocytosis by regulating immature enterocyte plasma membrane phospholipids. Gastroenterology 2008; 135:185-193.e1. [PMID: 18456000 PMCID: PMC2587123 DOI: 10.1053/j.gastro.2008.03.038] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2007] [Revised: 03/13/2008] [Accepted: 03/20/2008] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS Diarrheal disease is a major cause of morbidity and mortality in infants and children worldwide. Evidence has indicated immature human enterocytes and their interaction with bacteria and enterotoxins may account for the noted increased susceptibility of neonates to diarrhea. Our aim was to characterize the developmental difference in cholera toxin (CT)-GM1-mediated endocytosis. METHODS We used H4 cells (a fetal human small intestinal epithelial cell line), T84 cells, primary cultured mature human small intestinal epithelial cells, and human fetal small intestine xenografts. In addition, hydrocortisone was used as a potent intestinal trophic factor to induce maturation of the human enterocytes. RESULTS Here we show an increase in CT-caveolae and a decrease in CT-clathrin colocalization in H4/hydrocortisone compared with H4 cells by electron microscopy. In T84 and freshly isolated human small intestinal epithelial cells, a significant amount of GM1 was partitioned into the lipid rafts. In contrast, there was little CT-GM1/lipid raft association in H4 cells. However, hydrocortisone significantly increased GM1/lipid raft association in H4 cells. Furthermore, we noted an increase in the level of phosphatidylcholine, sphingomyelin, and the ratio of phosphatidylcholine/phosphatidylinositol in mature compared with immature enterocytes and that hydrocortisone can accelerate this maturational process. Disruption of phosphatidylinositol transfer protein alpha using small interference RNA showed an increase in GM1/lipid raft association in H4 cells and resulted in a decreased CT response. CONCLUSIONS Our studies suggest that the developmental change in CT endocytosis is partially caused by an increased GM1-lipid raft association through a maturational change of phospholipid composition on the cell surface of immature enterocytes.
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Affiliation(s)
- Lei Lu
- Developmental Gastroenterology Laboratory, Massachusetts General Hospital for Children, Boston, Massachusetts, USA.
| | - Yuanwu Bao
- Glycobiology Laboratory, Massachusetts General Hospital for Children, Boston, MA
| | | | - Allan M. Goldstein
- Pediatric Surgery, Massachusetts General Hospital for Children, Boston, MA
| | - David S Newburg
- Glycobiology Laboratory, Massachusetts General Hospital for Children, Boston, MA
| | | | - Dennis Brown
- Program in Membrane Biology, Massachusetts General Hospital, Boston, MA
| | - W. Allan Walker
- Developmental Gastroenterology Laboratory, Massachusetts General Hospital for Children, Boston, MA
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Abstract
The term toxin refers in a specific way to a toxic substance of biologic origin; that is, a true toxin is a poison produced by a living organism. The purpose of this article is to review some of the most potentially dangerous toxins of concern today. Mechanisms of action, routes of exposure, diagnostic tools, and treatment recommendations are addressed. In addition, current therapeutic uses for certain toxins are discussed.
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Affiliation(s)
- Matthew Salzman
- Department of Emergency Medicine, Drexel University College of Medicine, 2900 W. Queen Lane, Philadelphia, PA 19129, USA
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Ghosh A, Saha DR, Hoque KM, Asakuna M, Yamasaki S, Koley H, Das SS, Chakrabarti MK, Pal A. Enterotoxigenicity of mature 45-kilodalton and processed 35-kilodalton forms of hemagglutinin protease purified from a cholera toxin gene-negative Vibrio cholerae non-O1, non-O139 strain. Infect Immun 2006; 74:2937-46. [PMID: 16622232 PMCID: PMC1459690 DOI: 10.1128/iai.74.5.2937-2946.2006] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2005] [Revised: 10/14/2005] [Accepted: 02/14/2006] [Indexed: 11/20/2022] Open
Abstract
Cholera toxin gene-negative Vibrio cholerae non-O1, non-O139 strain PL-21 is the etiologic agent of cholera-like syndrome. Hemagglutinin protease (HAP) is one of the major secretory proteins of PL-21. The mature 45-kDa and processed 35-kDa forms of HAP were purified in the presence and absence of EDTA from culture supernatants of PL-21. Enterotoxigenicities of both forms of HAP were tested in rabbit ileal loop (RIL), Ussing chamber, and tissue culture assays. The 35-kDa HAP showed hemorrhagic fluid response in a dose-dependent manner in the RIL assay. Histopathological examination of 20 microg of purified protease-treated rabbit ileum showed the presence of erythrocytes and neutrophils in the upper part of the villous lamina propria. Treatment with 40 microg of protease resulted in gross damage of the villous epithelium with inflammation, hemorrhage, and necrosis. The 35-kDa form of HAP, when added to the lumenal surface of rat ileum loaded in an Ussing chamber, showed a decrease in the intestinal short-circuit current and a cell rounding effect on HeLa cells. The mature 45-kDa form of HAP showed an increase in intestinal short-circuit current in an Ussing chamber and a cell distending effect on HeLa cells. These results show that HAP may play a role in the pathogenesis of PL-21.
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Affiliation(s)
- A Ghosh
- Division of Pathophysiology, National Institute of Cholera and Enteric Diseases, Calcutta 700010, West Bengal, India
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Mrnka L, Beskid S, Sevastyanova O, Bryndová J, Pácha J. Age-dependent effect of secretagogues during colonic maturation. Eur J Pharmacol 2005; 516:268-75. [PMID: 15963977 DOI: 10.1016/j.ejphar.2005.04.042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2005] [Accepted: 04/29/2005] [Indexed: 10/25/2022]
Abstract
Intestinal secretory response is altered during colonic development. The aim of this report was to study the developmental changes of the Ca(2+)- and cAMP-induced regulatory pathways with special attention to the direct and indirect effect of secretagogues on the colonic epithelium. We investigated the effect of bethanechol, 5-hydroxytryptamine (5-HT), and histamine on Cl(-) secretion and stimulation of intracellular Ca(2+) ([Ca(2+)](i)) and cAMP in the distal colon of suckling, weanling and adult rats. In the presence of tetrodotoxin, immature colon of suckling and weanling rats displayed higher potency (EC(50)) of 5-HT to stimulate Cl(-) secretion, whereas the potency of histamine was not changed during development. The potency of bethanechol was reduced during weaning and partially restored in adulthood. 5-HT increased cAMP level similarly in both neonatal and adult colonic crypts, but the adults had higher basal level of cAMP than suckling rats. Also the effect of bethanechol on [Ca(2+)](i) was independent of colonic maturation. The results suggest that colonic Cl(-) secretion displays developmental changes of regulation depending on the non-neural secretagogue-signalling pathway and that these developmental changes seem to be localized somewhere outside colonocytes.
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Affiliation(s)
- Libor Mrnka
- Institute of Physiology, Czech Academy of Sciences, Vídenská 1083, CZ-142 20 Prague 4, Czech Republic
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Lu L, Khan S, Lencer W, Walker WA. Endocytosis of cholera toxin by human enterocytes is developmentally regulated. Am J Physiol Gastrointest Liver Physiol 2005; 289:G332-41. [PMID: 15790757 DOI: 10.1152/ajpgi.00521.2004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Many secretory diarrheas including cholera are more prevalent and fulminant in young infants than in older children and adults. Cholera toxin (CT) elicits a cAMP-dependent chloride secretory response in intestinal epithelia, which accounts for the fundamental pathogenesis of this toxigenic diarrhea. We have previously reported that the action of this bacterial enterotoxin is excessive in immature enterocytes and under developmental regulation. In this study, we tested the hypothesis that enhanced endocytosis by immature human enterocytes may, in part, account for the excessive secretory response to CT noted in the immature intestine and that enterocyte endocytosis of CT is developmentally regulated. To test this hypothesis, we used specific inhibitors to define endocytic pathways in mature and immature cell lines. We showed that internalization of CT in adult enterocytes is less and occurs via the caveolae/raft-mediated pathway in contrast to an enhanced immature human enterocyte CT uptake that occurs via a clathrin pathway. We also present evidence that this clathrin pathway is developmentally regulated as demonstrated by its response to corticosteroids, a known maturation factor that causes a decreased CT endocytosis by this pathway.
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Affiliation(s)
- Lei Lu
- Developmental Gastroenterology Laboratory, Massachusetts General Hospital, 114 16th St. (114-3503), Charlestown, MA 02129-4404, USA
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Claud EC, Lu L, Anton PM, Savidge T, Walker WA, Cherayil BJ. Developmentally regulated IkappaB expression in intestinal epithelium and susceptibility to flagellin-induced inflammation. Proc Natl Acad Sci U S A 2004; 101:7404-8. [PMID: 15123821 PMCID: PMC409931 DOI: 10.1073/pnas.0401710101] [Citation(s) in RCA: 177] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Necrotizing enterocolitis is a devastating inflammatory condition of the intestine that occurs almost exclusively in premature newborns. Although its exact pathogenesis is unclear, we have postulated that it may result from a predisposition of the immature intestine to mount an unusually robust and damaging response to microbial infection. In support of this idea, we report that the IL-8 response of an immature human enterocyte cell line to bacterial infection was significantly higher than that of a mature enterocyte cell line. The response in both cell lines was flagellin-dependent. Corresponding to the difference in IL-8 production, the immature enterocytes expressed appreciably lower levels of specific IkappaB genes when compared with the mature enterocytes. Similar developmentally regulated differences in cytokine response and IkappaB expression were also seen in primary rat enterocytes, indicating that these observations were not peculiarities of the cell lines. Furthermore, when the level of IkappaBalpha expression was increased in the immature cell line by transfection, the flagellin-dependent IL-8 response was attenuated. Thus, we have demonstrated a previously undescribed developmental regulation of IkappaB expression in the intestine involved in modulating the IL-8 response to bacterial infection, which may contribute to the pathogenesis of age-specific inflammatory bowel diseases such as necrotizing enterocolitis.
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Affiliation(s)
- Erika C Claud
- Pediatric Gastroenterology Unit, Massachusetts General Hospital, 114 16th Street, Charlestown, MA 02129, USA.
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Walker WA. The Dynamic Effects of Breastfeeding on Intestinal Development and Host Defense. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2004; 554:155-70. [PMID: 15384575 DOI: 10.1007/978-1-4757-4242-8_15] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
In this review, evidence is provided to support the hypothesis that human milk provides a link between the mother and her newborn infant in the extrauterine environment in a manner similar to the placental link between mother and fetus in utero. In addition, breastfeeding helps prevent age-related diseases affecting the gastrointestinal tract during the newborn period. To provide evidence to support this hypothesis, anecdotal clinical studies are sited to suggest that human milk contains factors that may be missing in inherited diseases of inborn errors in metabolism and provide passive protective factors that lessen the expression of neonatal allergic and infectious diseases. In some instances, by providing the missing factor in an inherited disease, the newborn may be protected from serious damage to its developing brain. A second line of evidence to support this hypothesis is the observation that the composition of human milk varies with the infant's needs. To illustrate this principal, the composition of milk from mothers delivering prematurely and milk of mothers of full-term infants were compared, and the differences in trophic and protective factors in colostrum versus mature milk from mothers delivering full-term are cited. Finally, using observations from the laboratory that define the immaturities in neonatal and premature human intestinal defenses as the neonate's host defense deficiency, the specific effect that anti-inflammatory and maturational factors in human milk has on these immaturities is discussed. The active stimulus of maternal milk on the rapid development of host defenses is underscored. These cited examples of human milk effects in the newborn help support the stated hypothesis. Additional studies of human immature gut function along with translational and clinical studies are necessary to provide further objective evidence in support of breastfeeding for all neonates, particularly premature neonates.
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Affiliation(s)
- W Allan Walker
- Departments of Nutrition and Pediatrics, Harvard Medical School, Laboratory, Massachusetts General Hospital, Charlestown, MA 02129, USA.
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