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PubMed2006

Impact of intestinal colonization and invasion on the Entamoeba histolytica transcriptome.

A genome-wide transcriptional analysis of Entamoeba histolytica was performed on trophozoites isolated from the colon of six infected mice and from in vitro culture. An Affymetrix platform gene expression array was designed for this analysis that included probe sets for 9435 open reading frames (ORFs) and 9066 5' and 3' flanking regions. Transcripts were detected for > 80% of all ORFs. A total of 523 transcripts (5.2% of all E. histolytica genes) were significantly changed in amebae isolated from the intestine on Days 1 and 29 after infection: 326 and 109 solely on Days 1 and 29, and 88 on both days. Quantitative real-time reverse transcriptase PCR confirmed these changes in 11/12 genes tested using mRNA isolated from an additional six mice. Adaptation to the intestinal environment was accompanied by increases in a subset of cell signaling genes including transmembrane kinases, ras and rho family GTPases, and calcium binding proteins. Significant decreases in mRNA abundance for genes involved in glycolysis and concomitant increases in lipases were consistent with a change in energy metabolism. Defense against bacteria present in the intestine (but lacking from in vitro culture) was suggested by alterations in mRNA levels of genes similar to the AIG1 plant antibacterial proteins. Decreases in oxygen detoxification pathways were observed as expected in the anaerobic colonic lumen. Of the known virulence factors the most remarkable changes were a 20-35-fold increase in a cysteine proteinase four-like gene, and a 2-3-fold decrease in two members of the Gal/GalNAc lectin light subunit family. Control of the observed changes in mRNA abundance in the intestine might potentially rest with four related proteins with DNA binding domains that were down-regulated 6-16-fold in the intestinal environment. In conclusion, the first genome-wide analysis of the transcriptome of E. histolytica demonstrated that the vast majority of genes are transcribed in trophozoites, and that in the host intestine trophozoites altered the expression of mRNAs for genes implicated in metabolism, oxygen defense, cell signaling, virulence, antibacterial activity, and DNA binding.

Animals↗
PubMed1994

Chemotactic response to mucin by Serpulina hyodysenteriae and other porcine spirochetes: potential role in intestinal colonization.

Chemotaxis of porcine spirochetes towards a variety of mucins was measured quantitatively by a capillary method. A chemotaxis buffer consisting of 0.01 M potassium phosphate buffer (pH 7.0) and 0.2 mM L-cysteine hydrochloride was necessary for chemotaxis of spirochetes. The optimum incubation time and incubation temperature were 1 h and 40 degrees C, respectively. The mucin concentration also affected the chemotaxis observed, and a concentration of 1% (wt/vol) was near the optimum. Virulent Serpulina hyodysenteriae strains were chemotactic towards 1% (wt/vol) hog gastric mucin and 1% (wt/vol) porcine colonic mucin but not towards 1% (wt/vol) bovine submaxillary mucin. Virulent S. hyodysenteriae strains were significantly more chemotactic than avirulent strains of S. hyodysenteriae (SA3 and VS1), Serpulina intermedius, and Serpulina innocens. Other spirochetes belonging to the proposed group of spirochetes Anguillina coli were also not chemotactic. Pathogenicity of S. hyodysenteriae strains that cause swine dysentery may, in part, be attributed to their attraction to porcine intestinal mucus.

Animals↗
PubMed1980

Quantitative evidence of intestinal colonization by Clostridium botulinum in four cases of infant botulism.

Infant botulism is an infectious form of a disease heretofore principally known as food-borne intoxication. Previous epidemiologic and laboratory studies have shown that infant botulism results from the ingestion of spores of Clostridium botulinum that subsequently germinate in the infant intestine and produce botulinal toxin. A quantitative study of the fecal microflora of four infants with infant botulism revealed the presence of C. botulinum in numbers as high as 6.0 x 10(8) colony-forming units (cfu)/g. At various times after the onset of illness, the numbers of C. botulinum that were recovered from feces ranged from 10(3) to 10(8) cfu/g and constituted from 0.01% to 3.3% of the total fecal flora. It was concluded that the large numbers of C. botulinum found in patients' feces could occur only as a consequence of in vivo spore germination and outgrowth.

Botulinum Toxins↗
PubMed2007

SiiE is secreted by the Salmonella enterica serovar Typhimurium pathogenicity island 4-encoded secretion system and contributes to intestinal colonization in cattle.

Here we report that Salmonella enterica serovar Typhimurium pathogenicity island 4 carries a type I secretion system (siiCDF) which secretes an approximately 600-kDa protein (encoded by siiE). SiiE is surface expressed, and its production is regulated by HilA. SiiE and SiiF influence colonization in cattle and the invasion of bovine enterocytes.

Animals↗
PubMed2000

Intestinal colonization leading to fecal urobilinoid excretion may play a role in the pathogenesis of neonatal jaundice.

BACKGROUND: Neonatal hyperbilirubinemia remains of concern because of the potential danger for the central nervous system. Because urobilinogen is a nontoxic derivative of bilirubin, the current study was conducted to examine the fecal excretion of urobilinoids and bilirubin in healthy newborns and infants, as well as their intestinal bacteria capable of reducing bilirubin, to assess a possible relation to serum bilirubin levels during the first weeks of life. METHODS: Bilirubin pigments, urobilinoids, and porphyrins were measured in stools of infants during the first week (group A, n = 60) and between the second week and the first 6 months of life (group B, n = 64). Microbiologic analysis of stools was performed in selected cases and bilirubin-converting activity of isolated bacteria was determined in vitro. RESULTS: Urobilinoids were detectable in stools of 57% of the neonates at day 5, but not before. However, fecal urobilinoid production on that day was only a fraction of that observed in adults (0.07 vs. 0.7-3.6 mg/kg per day), whereas at week 6 it increased significantly to an average of 0.9 mg/kg per day. Microbiologic analysis of neonatal stools revealed two novel bacterial strains of Clostridium perfringens and Clostridium difficile capable of reducing bilirubin to urobilinoids. CONCLUSIONS: Urobilinoids can be detected in stools of 57% of newborns at day 5 after delivery. However, the urobilinoid production during the first week of life is quantitatively insufficient to contribute significantly to the removal of bilirubin. Enhancement of the microbial conversion of bilirubin could decrease the intestinal concentration of bilirubin and may decrease the degree or enhance the removal of neonatal hyperbilirubinemia.

Bacteria↗
PubMed2002

Synthetic analogues of beta-1,2 oligomannosides prevent intestinal colonization by the pathogenic yeast Candida albicans.

The pathogenic yeast Candida albicans displays at its cell surface beta-1,2 oligomannosides (beta-1,2-Mans). In contrast to the ubiquitous alpha-Mans, beta-1,2-Mans bind to galectin-3, a major endogenous lectin expressed on epithelial cells. The specific role of beta-1,2-Mans in colonization of the gut by C. albicans was assessed in a mouse model. A selected virulent strain of C. albicans (expressing more beta-1,2-Man epitopes) induced more intense and sustained colonization than an avirulent strain (expressing less beta-1,2-Man epitopes). Synthetic (Sigma) beta-and alpha-linked tetramannosides with antigenicities that mimicked the antigenicities of C. albicans-derived oligomannosides were then constructed. Oral administration of Sigmabeta-1,2-Man (30 mg/kg of body weight) prior to inoculation with the virulent strain resulted in almost complete eradication of yeasts from stool samples, whereas administration of Sigmaalpha-Man at the same dose did not. As most cases of human systemic candidiasis are endogenous in origin, this first demonstration that a synthetic analogue of a yeast adhesin can prevent yeast colonization in the gut opens the possibility of new prophylactic strategies.

Animals↗
PubMed1999

rfb mutations in Vibrio cholerae do not affect surface production of toxin-coregulated pili but still inhibit intestinal colonization.

The toxin-coregulated pilus (TCP) of Vibrio cholerae is essential for colonization. It was recently reported that rfb mutations in V. cholerae 569B cause the translocation arrest of the structural subunit of TCP, raising the possibility that the colonization defects of lipopolysaccharide mutants are due to effects on TCP biogenesis. However, an rfbB gene disruption in either V. cholerae O395 or 569B has no apparent effect on surface TCP production as assessed by immunoelectron microscopy and CTX phage transduction, and an rfbD::Tn5lac mutant of O395 also shows no defect in TCP expression. We conclude that the colonization defect associated with rfb mutations is unrelated to defects in TCP assembly.

Animals↗
PubMed1989

Intestinal colonization with Clostridium difficile in infants up to 18 months of age.

The faecal colonization with Clostridium difficile was investigated among 343 infants during their first 18 months of life. Rectal swabs were taken at the ages of 6 days, 6 weeks, 6 months, 11 months and 18 months. About 25% of the children were colonized with Clostridium difficile between 6 days and 6 months of age. The colonization rate decreased to 3% at 18 months of age. The rate of strains producing cytotoxin was low in infants less than 6 months of age, but at that age about half of the strains isolated were toxin-producing. Breast-fed children were significantly less often colonized with Clostridium difficile than were bottle-fed infants, both at 6 weeks of age (21% versus 47%, p less than 0.05) and at 6 months of age (19% versus 39%, p less than 0.001). Colonization with Clostridium difficile at 6 months of age was associated with a greater frequency of diarrhoeal disease between 6 and 11 months of age (27% versus 16%, p less than 0.05). This association was even more pronounced when the bacteria persisted at 11 months of age (54%, p less than 0.01). Antibiotic therapy could not be demonstrated to influence colonization with Clostridium difficile at any age.

Age Factors↗
PubMed2006

Effect of a selective decontamination of the digestive tract regimen including parenteral cefepime on establishment of intestinal colonization with vancomycin-resistant Enterococcus spp. and Klebsiella pneumoniae in mice.

In mice, a selective decontamination of the digestive tract regimen consisting of orogastric tobramycin, polymyxin E, and amphotericin B in combination with subcutaneous cefepime inhibited gram-negative bacilli, including Klebsiella pneumoniae, and did not promote vancomycin-resistant Enterococcus spp. (VRE) colonization. However, concurrent administration of subcutaneous ampicillin-sulbactam resulted in promotion of VRE.

Animals↗
PubMed1989

Antibiotic treatment and intestinal colonization by Pseudomonas aeruginosa in cancer patients.

To determine whether antibiotic treatment increases the risk of colonization by Pseudomonas aeruginosa, we performed a case-control study comparing antibiotic exposure in cancer patients colonized by P. aeruginosa and in noncolonized controls. Of 88 patients, 76 had been exposed to at least one antibiotic, but colonization was not statistically associated with exposure to any specific antibiotic treatment, administered orally or parenterally, alone or in combination.

Adolescent↗
PubMed2003

Effect of parenteral antibiotic administration on establishment of intestinal colonization in mice by Klebsiella pneumoniae strains producing extended-spectrum beta-lactamases.

A mouse model was used to test the hypothesis that antibiotics with activity against anaerobes promote overgrowth of extended-spectrum beta-lactamase-producing Klebsiella pneumoniae strains in stool. Subcutaneous clindamycin consistently promoted establishment of high-density colonization, whereas piperacillin-tazobactam, ceftriaxone, and ceftazidime promoted colonization only when a large inoculum and/or more resistant strain was administered.

Animals↗
PubMed2005

Crosstalk between NF-kappaB and beta-catenin pathways in bacterial-colonized intestinal epithelial cells.

Salmonella-epithelial cell interactions are known to activate the proinflammatory NF-kappaB signaling pathway and have recently been found to also influence the beta-catenin signaling pathway, an important regulator of epithelial cell proliferation and differentiation. Here, using polarized epithelial cell models, we demonstrate that these same bacteria-mediated effects also direct the molecular crosstalk between the NF-kappaB and beta-catenin signaling pathways. Convergence of these two pathways is a result of the direct interaction between the NF-kappaB p50 subunit and beta-catenin. We show that PhoP(c), the avirulent derivative of a wild-type Salmonella strain, attenuates NF-kappaB activity by stabilizing the association of beta-catenin with NF-kappaB. In cell lines expressing constitutively active beta-catenin, IkappaBalpha protein was indirectly stabilized and NF-kappaB activity was repressed after wild-type Salmonella colonization. Accordingly, constitutively active beta-catenin was found to inhibit the secretion of IL-8. Thus our findings strongly suggest that the crosstalk between the beta-catenin and NF-kappaB signaling pathways is an important regulator of intestinal inflammation.

Cytoskeletal Proteins↗
PubMedDate not supplied

Intestinal colonization and competitive exclusion of Campylobacter fetus subsp. jejuni in young chicks.

Colonization of Campylobacter fetus subsp. jejuni was investigated in monoxenic and holoxenic chicks. In monoxenic chicks, major colonization was found in the crop and ceca, with populations in the ceca consistently reaching 10(9) colony-forming-units/ml of cecal contents over the 28-day test period. Bacteremia was found in most chicks, but no significant gross pathological lesions were detected. In holoxenic chicks, major colonization occurred only in the ceca, and no evidence of bacteremia was detected. Colonization by native gut microflora sharply reduced subsequent colonization by C. fetus subsp. jejuni. The protective mechanism is perhaps the same as that protective against paratyphoid salmonellae and pathogenic strains of Escherichia coli.

Animals↗
PubMed2004

Proteomic analysis of nuclear proteins from proliferative and differentiated human colonic intestinal epithelial cells.

Self-renewing tissues such as the intestine contain progenitor proliferating cells which subsequently differentiate. Cell proliferation and differentiation involve gene regulation processes which take place in the nucleus. A human intestinal epithelial cell line model (Caco2/TC7) which reproduces these dynamic processes has been used to perform proteomic studies on nuclear proteins. Nuclei from Caco2/TC7 cells at proliferative and differentiated stages were purified by subcellular fractionation. After two-dimensional gel electrophoresis separation and ruthenium staining, 400 protein spots were detected by image analysis. Eighty-five spots corresponding to 60 different proteins were identified by matrix-assisted laser desorption/ionization mass spectrometry in nuclei from proliferative cells. Comparison of nuclear proteomes from proliferative or differentiated cells by differential display resulted in the identification of differentially expressed proteins such as nucleolin, hnRNP A2/B1 and hnRNP A1. By using Western blot analysis, we found that the expression and number of specific isoforms of these nuclear proteins decreased in differentiated cells. Immunocytochemistry experiments also showed that in proliferative cells nucleolin was distributed in nucleoli-like bodies. In contrast, hnRNPs A2/B1 and A1 were dispersed throughout the nucleus. This study of the nuclear proteome from intestinal epithelial cells represents the first step towards the establishment of a protein database which will be a valuable resource in future studies on the differential expression of nuclear proteins in response to physiological, pharmacological and pathological modulations.

Caco-2 Cells↗