Development of Microbial-Human Enterocyte Interaction: Cholera Toxin

Lü, Lei; Baldeón, Manuel E.; Savidge, Tor; Pothoulakis, Charalabos; Walker, W. Allan

doi:10.1203/01.pdr.0000074974.21797.83

Cited by 14 publications

(13 citation statements)

References 30 publications

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“…Previous studies have used this cell line to investigate differences in immature and mature intestine in response to lipopolysaccharide, IL-1␤, and cholera toxin. Results obtained with the H4 line have been found to be comparable to those obtained with primary human fetal organ cultures (4,8). These cells are morphologically immature and do not form tight junctions.…”

Section: Immature Enterocytes (H4 Cells) Have Increased Il-8 Secretiosupporting

confidence: 65%

“…Certain aspects of this function are developmentally regulated, resulting in distinct differences between the immature and mature intestine with respect to interactions with microorganisms (1)(2)(3)(4). Immaturity of epithelial barrier function, relative deficiencies in the expression of antimicrobial factors, and developmental variations in the pattern of epithelial surface glycosylation all contribute to the susceptibility of early postnatal intestine to bacterial infection (5-7).…”

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confidence: 99%

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Developmentally regulated IκB expression in intestinal epithelium and susceptibility to flagellin-induced inflammation

Claud

Lü

Anton

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

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203

145

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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 IB genes when compared with the mature enterocytes. Similar developmentally regulated differences in cytokine response and IB expression were also seen in primary rat enterocytes, indicating that these observations were not peculiarities of the cell lines. Furthermore, when the level of IB␣ 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 IB 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. E nterocytes are active participants in host defense against microbial invasion. Certain aspects of this function are developmentally regulated, resulting in distinct differences between the immature and mature intestine with respect to interactions with microorganisms (1-4). Immaturity of epithelial barrier function, relative deficiencies in the expression of antimicrobial factors, and developmental variations in the pattern of epithelial surface glycosylation all contribute to the susceptibility of early postnatal intestine to bacterial infection (5-7). Concurrently, the secretion of proinflammatory cytokines is greater at earlier stages of development than in the adult. Specifically, IL-8 production in response to IL-1␤ and tumor necrosis factor ␣ has been shown to be significantly increased in the human fetal intestinal epithelial cell (IEC) line H4 and fetal intestinal organ cultures compared with the adult IEC line Caco2 and biopsies from older children (8). The combination of weaker antimicrobial defense mechanisms and exaggerated cytokine responses may render the immature gut prone to extensive inflammatory damage after infection. These properties could thus contribute to the pathogenesis of age-specific diseases such as necrotizing enterocolitis (NEC), an ischemic and inflammatory bowel necrosis that primarily affects premature neonates after the initiation of enteral feeding.We have postulated a model of NEC pathogenesis in which early feeding results in exposure to numbers and types of bacteria that the premature intestine is ill-equipped to handle (9). The exaggerated inflammatory responses that are cha...

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Section: Immature Enterocytes (H4 Cells) Have Increased Il-8 Secretiosupporting

confidence: 65%

mentioning

confidence: 99%

Developmentally regulated IκB expression in intestinal epithelium and susceptibility to flagellin-induced inflammation

Claud

Lü

Anton

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

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203

145

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“…The Isc changes peaked at 4 g/ml, while the effect observed at 6 g/ml revealed that the enterotoxic response of the 45-kDa form was masked by the cytotoxic effect of the 35-kDa form, resulting in a decrease in Isc. The enterotoxic response of the 45-kDa HAP started after a delay of 45 to 60 min and was equivalent to the effect of 1 g/ml of CT in the rat small intestine (19). Enterotoxicity is caused by an abnormal flux of negatively charged ions from the serosal side to the mucosal side (8).…”

Section: Discussionmentioning

confidence: 98%

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

Ghosh¹,

Saha²,

Hoque³

et al. 2006

Infect Immun

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Cholera toxin gene-negativeVibrio cholerae non-O1, non-O139 strains are an intriguing group that can cause typical cholera-like disease but do not produce cholera toxin (CT) (23). The virulence factor in V. cholerae non-O1, non-O139 strains that do not produce cholera toxin and yet cause symptoms similar to cholera has not yet been identified (6). It was found that none of the previously described virulence-related genes like the RTX (repeats in toxin) toxin gene cluster, the hlyA gene coding for hemolysin, the mshA gene for mannose-sensitive hemagglutinin pilus, and the stn gene encoding a heat-stable enterotoxin of non-O1 vibrios (NAG-ST) was specifically associated with the pathogenesis of TCP Ϫ CTX Ϫ non-O1, non-O139 strains that colonized mice and caused fluid accumulation in rabbits (6). In the above-mentioned study, the role of the hapA gene (coding for hemagglutinin protease [HAP]) in the disease process was not investigated. Studies by Benítez et al. with vaccine strain 638, which bears a core deletion of the ctx gene and an insertional mutation of the hapA gene, showed fewer symptoms and a decrease in diarrhea in volunteers compared to those in previous studies using only the core deletion strain (2). In addition, strain 638 induced lower levels of interleukin-8 (IL-8) than its parent wild-type strain did in HT29 cells (2, 30). Cholera vaccine strain CVD 110, a mutant of El Tor Ogawa strain E7946, which is deleted of all known virulence genes except hap, gives rise to a highly inflammatory reaction (36). Concentrated proteins derived from the culture supernatant of CVD 110 caused morphological changes in cultured MDCK-1 epithelial cells and altered their arrangement of filamentous actin and zonula occludens-associated protein (ZO-1) (38). The drastic morphological changes were inhibited by Zincov, a specific bacterial metalloprotease inhibitor. After fast-performance liquid chromatography, the cytotoxic fractions of the sample showed two visible bands with molecular masses of approximately 34 and 32 kDa. Microsequencing of these proteins revealed that they were in fact HAP. Culture supernatants prepared from the reactogenic strains of V. cholerae cause a decrease in the transcellular epithelial resistance of T84 intestinal cells (21). This decrease correlates with the presence of HAP but not with the presence of other potential accessory toxins or proteases (21). Microarray studies of the global transcription pattern of V. cholerae grown in vivo in the rabbit ileal loop (RIL) model have shown that the hemagglutinin protease (hap) gene is one of the 12 genes that belong to the pathogenesis functional group and are highly expressed compared to their levels of expression under laboratory conditions (29). V. cholerae O1 classical and El Tor biotypes as well as non-O1 serotypes produce HAP (3). The secreted HAP has been purified, cloned, and sequenced (9, 14). The hap gene consists of 1,827 nucleotides with a predicted molecular mass of 69.3 kDa. This is larger than the molecular mass of the purified HAP (3...

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“…This study employed two human intestinal epithelial cell lines, H4 and T84. H4 is a previously characterized primary human fetal small intestinal cell line that we used in numerous studies defining the role of human enterocytes in the development of intestinal host defenses (8,9,13,19,20). T84, a well-characterized, human colon carcinoma cell line that comprises highly differentiated crypt-like cells, has been used as a mature human intestinal model (8,20,28).…”

Section: Methodsmentioning

confidence: 99%

“…33). Among many endogenous biological mediators, hydrocortisone (HC), epidermal growth factor, and transforming growth factor-␤ (TGF-␤) promote growth and differentiation (34), modulate the inflammatory response (9), and reduce an excessive secretory response to cholera toxin in human and rat immature enterocytes (7,19,20).…”

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confidence: 99%

Hydrocortisone induces changes in gene expression and differentiation in immature human enterocytes

Lü

Williams

et al. 2011

American Journal of Physiology-Gastrointestinal and Liver Physi

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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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Development of Microbial-Human Enterocyte Interaction: Cholera Toxin

Cited by 14 publications

References 30 publications

Developmentally regulated IκB expression in intestinal epithelium and susceptibility to flagellin-induced inflammation

Developmentally regulated IκB expression in intestinal epithelium and susceptibility to flagellin-induced inflammation

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

Hydrocortisone induces changes in gene expression and differentiation in immature human enterocytes

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