Michael O'Brien

Boston University, Boston, MA, USA

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Publications (15)97.39 Total impact

  • Article: Melanin-concentrating hormone (MCH) modulates C difficile toxin A-mediated enteritis in mice.
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    ABSTRACT: Melanin-concentrating hormone (MCH) is a hypothalamic orexigenic neuropeptide that regulates energy balance. However, the distribution of MCH and its receptor MCHR1 in tissues other than brain suggested additional, as yet unappreciated, roles for this neuropeptide. Based on previous paradigms and the presence of MCH in the intestine as well as in immune cells, its potential role in gut innate immune responses was examined. In human intestinal xenografts grown in mice, changes in the expression of MCH and its receptors following treatment with Clostridium difficile toxin A, the causative agent of antibiotic-associated diarrhoea in hospitalised patients, were examined. In colonocytes, the effect of C difficile toxin A treatment on MCHR1 expression, and of MCH on interleukin 8 (IL8) expression was examined. MCH-deficient mice and immunoneutralisation approaches were used to examine the role of MCH in the pathogenesis of C difficile toxin A-mediated acute enteritis. Upregulation of MCH and MCHR1 expression was found in the human intestinal xenograft model, and of MCHR1 in colonocytes following exposure to toxin A. Treatment of colonocytes with MCH resulted in IL8 transcriptional upregulation, implying a link between MCH and inflammatory pathways. In further support of this view, MCH-deficient mice developed attenuated toxin A-mediated intestinal inflammation and secretion, as did wild-type mice treated with an antibody against MCH or MCHR1. These findings signify MCH as a mediator of C difficile-associated enteritis and possibly of additional gut pathogens. MCH may mediate its proinflammatory effects at least in part by acting on epithelial cells in the intestine.
    Gut 10/2008; 58(1):34-40. · 10.11 Impact Factor
  • Article: Corticotropin-releasing hormone deficiency is associated with reduced local inflammation in a mouse model of experimental colitis.
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    ABSTRACT: CRH, the hypothalamic component of the hypothalamic-pituitary adrenal axis, attenuates inflammation through stimulation of glucocorticoid release, whereas peripherally expressed CRH acts as a proinflammatory mediator. CRH is expressed in the intestine and up-regulated in patients with ulcerative colitis. However, its pathophysiological significance in intestinal inflammatory diseases has just started to emerge. In a mouse model of acute, trinitrobenzene sulfonic acid-induced experimental colitis, we demonstrate that, despite low glucocorticoid levels, CRH-deficient mice develop substantially reduced local inflammatory responses. These effects were shown by histological scoring of tissue damage and neutrophil infiltration. At the same time, CRH deficiency was found to be associated with higher serum leptin and IL-6 levels along with sustained anorexia and weight loss, although central CRH has been reported to be a strong appetite suppressor. Taken together, our results support an important proinflammatory role for CRH during mouse experimental colitis and possibly in inflammatory bowel disease in humans. Moreover, the results suggest that CRH is involved in homeostatic pathways that link inflammation and metabolism.
    Endocrinology 08/2008; 149(7):3403-9. · 4.46 Impact Factor
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    Article: Melanin-concentrating hormone as a mediator of intestinal inflammation.
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    ABSTRACT: Melanin-concentrating hormone (MCH) is expressed primarily in the hypothalamus and has a positive impact on feeding behavior and energy balance. Although MCH is expressed in the gastrointestinal tract, its role in this system remains elusive. We demonstrate that, compared to wild type, mice genetically deficient in MCH had substantially reduced local inflammatory responses in a mouse model of experimental colitis induced by intracolonic administration of 2,4,6 trinitrobenzene sulfonic acid (TNBS). Likewise, mice receiving treatments with an anti-MCH antibody, either prophylactically or after the establishment of colitis, developed attenuated TNBS-associated colonic inflammation and survived longer. Consistent with a potential role of MCH in intestinal pathology, we detected increased colonic expression of MCH and its receptor in patients with inflammatory bowel disease. Moreover, we found that human colonic epithelial cells express functional MCH receptors, the activation of which induces IL-8 expression. Taken together, these results clearly implicate MCH in inflammatory processes in the intestine and perhaps elsewhere.
    Proceedings of the National Academy of Sciences 07/2008; 105(30):10613-8. · 9.68 Impact Factor
  • Article: Comparative efficacies of rifaximin and vancomycin for treatment of Clostridium difficile-associated diarrhea and prevention of disease recurrence in hamsters.
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    ABSTRACT: Clostridium difficile-associated colitis is an increasing cause of morbidity and mortality in hospitalized patients, with high relapse rates following conventional therapy. We sought to determine the efficacy of rifaximin, a novel nonabsorbed antibiotic, in the hamster model of C. difficile-associated diarrhea (CDAD). Hamsters received clindamycin subcutaneously and 24 h later were infected by gavage with one of two C. difficile strains: a reference strain (VPI 10463) and a current epidemic strain (BI17). Vancomycin (50 mg/kg of body weight) or rifaximin (100, 50, and 25 mg/kg) were then administered orally for 5 days beginning either on the same day as infection (prevention) or 24 h later (treatment). Therapeutic effects were assessed by weight gain, histology, and survival. We found that rifaximin was as effective as vancomycin in the prevention and treatment of colitis associated with the two C. difficile strains that we examined. There was no relapse after treatment with vancomycin or rifaximin in hamsters infected with the BI17 strain. Hamsters infected with the VPI 10463 strain and treated with rifaximin did not develop relapsing infection within a month of follow-up, whereas the majority of vancomycin-treated animals relapsed (0% versus 75%, respectively; P < 0.01). In conclusion, rifaximin was found to be an effective prophylactic and therapeutic agent for CDAD in hamsters and was not associated with disease recurrence. These findings, in conjunction with the pharmacokinetic and safety profiles of rifaximin, suggest that it is an attractive candidate for clinical use for CDAD.
    Antimicrobial Agents and Chemotherapy 03/2008; 52(3):1121-6. · 4.84 Impact Factor
  • Article: Corticotropin-releasing hormone receptor 2-deficient mice have reduced intestinal inflammatory responses.
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    ABSTRACT: Corticotropin-releasing hormone (CRH) and urocortins (Ucn) bind with various affinities to two G-protein-coupled receptors, CRHR1 and CRHR2, which are expressed in brain and in peripheral tissues, including immune cells. CRHR2-deficient mice display anxiety-like behavior, hypersensitivity to stress, altered feeding behavior and metabolism, and cardiovascular abnormalities. However, the phenotype of these mice in inflammatory responses has not been determined. In the present study we found that compared with wild-type CRHR2-null mice developed substantially reduced intestinal inflammation and had lower intestinal mRNA expression of the potent chemoattractants keratinocyte chemokine and monocyte chemoattractant protein 1 following intraluminal exposure to Clostridium difficile toxin A, a potent enterotoxin that mediates antibiotic-associated diarrhea and colitis in humans. This effect was recapitulated by administration of astressin 2B, a selective CRHR2 antagonist, before toxin A exposure. Moreover, Ab array analysis revealed reduced expression of several inflammatory chemokines, including keratinocyte chemokine and monocyte chemoattractant protein 1 in toxin A-exposed mice pretreated with astressin 2B. Real-time RT-PCR of wild-type mouse intestine showed that only UcnII, but not other Ucn, was significantly up-regulated by ileal administration of toxin A at 4 h compared with buffer exposure. We also found that human colonic epithelial HT-29 cells express CRHR2alpha mRNA, whereas expression of beta and gamma spliced variants was minimal. Moreover, treatment of HT-29 cells with UcnII, which binds exclusively to CRHR2, stimulated expression of IL-8 and monocyte chemoattractant protein 1. Taken together, these results provide direct evidence that CRHR2 mediates intestinal inflammatory responses via release of proinflammatory mediators at the colonocyte level.
    The Journal of Immunology 10/2006; 177(5):3355-61. · 5.79 Impact Factor
  • Article: A new transcription factor that regulates TNF-alpha gene expression, LITAF, is increased in intestinal tissues from patients with CD and UC.
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    ABSTRACT: The proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) plays a key role in the pathogenesis of Crohn's disease (CD) and ulcerative colitis (UC). Recently, a new transcription factor termed LITAF (lipopolysaccharide-induced TNF-alpha factor) was shown to mediate TNF-alpha expression in human macrophages by direct binding to specific sequences in the promoter region of the TNF-alpha gene. In this report, we identified LITAF in resected ileal and colonic tissues from patients with CD and UC by immunohistochemistry, real-time polymerase chain reaction, and Western blot analysis. LITAF expression in inflamed and noninflamed areas of the tissues was compared. This is the first demonstration of LITAF, a newly discovered transcription factor that regulates TNF-alpha gene transcription in ileal and colonic tissues from patients with either CD or UC. LITAF immunostaining was localized to lamina propria macrophages and was markedly increased relative to tissues from controls without inflammatory bowel disease. In patients with CD, a 5-fold increase in LITAF mRNA was measurable in noninflamed colonic tissues compared with controls without inflammatory bowel disease. LITAF mRNA in tissues from inflamed areas of the colon was increased by an additional 60% compared with noninflamed tissues. In patients with UC, LITAF mRNA levels in colonic tissues resected from noninflamed areas were elevated 15-fold above nondisease controls, but they were not different in tissues resected from inflamed areas. Western blot analysis showed that in patients with CD, there was a marked increase in LITAF protein in inflamed areas compared with noninflamed areas. LITAF protein levels were not different between noninflamed and inflamed tissues obtained from patients with UC. TNF-alpha mRNA and protein levels paralleled LITAF. Similarly, in inflamed ileal tissues from patients with CD, LITAF is also localized to lamina propria macrophages. LITAF mRNA and LITAF protein were significantly increased in inflamed ileal tissues compared with noninflamed areas. LITAF is readily detectable in ileal and colonic tissues from patients with either CD or UC, is significantly elevated above controls, and is localized to macrophages, a major source of TNF-alpha. These data provide strong evidence of a role for LITAF in the pathophysiological regulation of the TNF-alpha gene and underscore the potential value of anti-LITAF strategies in the clinical management of these diseases.
    Inflammatory Bowel Diseases 08/2006; 12(7):581-7. · 4.86 Impact Factor
  • Article: Saccharomyces boulardii inhibits ERK1/2 mitogen-activated protein kinase activation both in vitro and in vivo and protects against Clostridium difficile toxin A-induced enteritis.
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    ABSTRACT: Saccharomyces boulardii (Sb), a probiotic yeast, protects against intestinal injury and inflammation caused by a wide variety of enteric pathogens, including Clostridium difficile. Given the broad range of protective effects of Sb in multiple gastrointestinal disorders, we hypothesize that Sb modulates host signaling pathways involved in intestinal inflammatory responses. In this study, we found that Sb culture supernatant (SbS) inhibits interleukin-8 production induced by C. difficile toxin A or IL-1beta in human colonocyte NCM460 cells in a dose-dependent fashion. Furthermore, SbS inhibited IL-1beta and toxin A induced Erk1/2 and JNK/SAPK but not p38 activation in NCM460 cells. To test whether this inhibition also occurs in vivo, we used a previously established mouse ileal loop model. On its own, SbS had no significant effect on basal fluid secretion or intestinal histology. However, Erk1/2 activation was significantly inhibited by SbS in toxin A exposed mouse ileal mucosa. In control loops, toxin A increased fluid secretion (2.2-fold), histological score (3.3-fold), and levels of the chemokine KC (4.5-fold). SbS pretreatment completely normalized toxin A mediated fluid secretion (p < 0.01), and histopathologic changes (p < 0.01) and substantially inhibited toxin A-associated KC increases (p < 0.001). In summary, the probiotic yeast S. boulardii inhibits C. difficile toxin A-associated enteritis by blocking the activation of Erk1/2 MAP kinases. This study indicates a new mechanism whereby Sb protects against intestinal inflammation and supports the hypothesis that Sb modulates host inflammatory signaling pathways to exert its beneficial effects.
    Journal of Biological Chemistry 08/2006; 281(34):24449-54. · 4.77 Impact Factor
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    Article: Induction of colitis causes inflammatory responses in fat depots: evidence for substance P pathways in human mesenteric preadipocytes.
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    ABSTRACT: Intracolonic administration of trinitrobenzene sulfonic acid in mice causes inflammation in the colon that is accompanied by increased expression of proinflammatory cytokines and of the substance P (SP), neurokinin 1 receptor (NK-1R) in the proximal mesenteric fat depot. We also investigated whether human mesenteric preadipocytes contain NK-1R and examined the functional consequences of exposure of these cells to SP as it relates to proinflammatory signaling. We found that human mesenteric preadipocytes express NK-1R both at the mRNA and protein levels. Exposure of human mesenteric preadipocytes to SP increased NK-1R mRNA and protein expression by 3-fold, and stimulated IL-8 mRNA expression and protein secretion. This effect was abolished when these cells were pretreated with the specific NK-1R antagonist CJ 012,255. Moreover, human mesenteric preadipocytes transfected with a luciferase promoter/reporter system containing the IL-8 promoter with a mutated NF-kappaB site lost their ability to respond to SP, indicating that SP-induced IL-8 expression is NF-kappaB-dependent. This report indicates that human mesenteric preadipocytes contain functional SP receptors that are linked to proinflammatory pathways, and that SP can directly increase NK-1R expression. We speculate that mesenteric fat depots may participate in intestinal inflammatory responses via SP-NK-1R-related pathways, as well as other systemic responses to the presence of an ongoing inflammation of the colon.
    Proceedings of the National Academy of Sciences 04/2006; 103(13):5207-12. · 9.68 Impact Factor
  • Article: Interleukin-6 genetic ablation protects from trinitrobenzene sulfonic acid-induced colitis in mice. Putative effect of antiinflammatory cytokines.
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    ABSTRACT: Interleukin (IL)-6 is a proinflammatory cytokine implicated in the pathogenesis of inflammatory bowel disease. IL-6 is locally upregulated in inflammatory bowel disease patients and in murine models of experimental colitis. Treatment with anti-IL-6 receptor antibody ameliorates intestinal inflammation. It was the aim of this study to investigate the role of genetic IL-6 deficiency in trinitrobenzene sulfonic acid (TNBS)-mediated colitis, an experimental model inflammation that shares several features with Crohn's disease in humans. Acute colitis was induced in wild-type and IL-6-deficient (Il-6(-/-)) mice by intracolonic administration of TNBS. Forty-eight hours after treatment, the local and systemic features of inflammation, i.e. food intake, weight loss, histological markers of colitis, cytokine expression by real-time PCR, food intake and body weight changes, were assessed. In wild-type mice, TNBS administration increased both IL-6 serum levels and local expression of IL-6 by 36 and 9 fold, respectively, compared with control, vehicle-injected mice. Compared with the wild-type mice, the Il-6(-/-) mice had significantly reduced intestinal inflammation as evidenced by epithelial damage, neutrophil infiltration, colon thickness and proinflammatory cytokine expression, following treatment with TNBS. Moreover, baseline levels of the antiinflammatory cytokines IL-10 and tumor growth factor-beta were significantly elevated in Il-6(-/-)compared with the wild-type mice. Our results demonstrate that Il-6(-/-)are partially protected from the development of TNBS-induced acute experimental colitis, most likely via their significantly elevated baseline levels of antiinflammatory cytokines.
    NeuroImmunoModulation 02/2006; 13(2):114-21. · 2.38 Impact Factor
  • Article: NF-kappaB activation precedes increases in mRNA encoding neurokinin-1 receptor, proinflammatory cytokines, and adhesion molecules in dextran sulfate sodium-induced colitis in rats.
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    ABSTRACT: Nuclear factor kappa B (NF-kappa B) plays a key role in initiating inflammation associated with colitis. A systematic study was conducted in the rat DSS colitis model to determine the temporal relationship between NF-kappa B activation and expression of substance P (SP), neurokinin-1 receptor (NK-1R), proinflammatory cytokines, and adhesion molecules. Rats were given 5% DSS in their water and sacrificed daily for 6 days. Colon tissue was collected for assessment of histological changes, NF-kappa B activation, myeloperoxidase (MPO) activity, and expression of NK-1R, SP, TNFalpha, IL-1beta, VCAM-1, ICAM-1, E-selectin, CINC-1, MIP-1alpha, and iNOS. NF-kappa B activation increased, biphasically, on Day 1 and again on Days 4-6. The mRNA levels for ICAM-1, CINC-1, IL-1beta, TNFalpha, VCAM-1, and NK-1R rose significantly (P < 0.05) by 2-4 days. Increased iNOS mRNA levels, MPO activity, and mucosal damage occurred on Day 6. These data demonstrate that NF-kappa B activation substantially precedes the onset of physical disease signs and active inflammation.
    Digestive Diseases and Sciences 01/2006; 50(12):2366-78. · 2.12 Impact Factor
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    Article: Pathophysiological role of Toll-like receptor 5 engagement by bacterial flagellin in colonic inflammation.
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    ABSTRACT: Commensal and enteroinvasive microbes in the human gut release bacterial flagellin, a specific microbial ligand of Toll-like receptor 5 (TLR5). However, the pathophysiological role of bacterial flagellin in gastrointestinal inflammation has not been determined. Here we evaluated the role of bacterial flagellin using native human colonic mucosa and the mouse colitis model of dextran sulfate sodium (DSS). We demonstrate that, in intact human colonic mucosa, the flagellin/TLR5 response occurs only after exposure to the basolateral, not the apical, surface, implying a basolaterally polarized TLR5 response in human colonic mucosa. In this context, flagellin exposure to injured colonic mucosa due to DSS administration in mice resulted in a TLR5-associated response evaluated by in vivo activation of mitogen-activated protein kinase/extracellular signal-related kinase 1/2 (MEK1/2) and elevated IL-6, TNF-alpha, and keratinocyte-derived chemokine production, whereas intact colonic mucosa did not respond to flagellin. Moreover, flagellin exposure to injured mouse colon in vivo, but not to intact colon, also significantly aggravated colonic inflammation, increased mouse mortality, and enhanced histopathological damage in the colonic mucosa. However, the TLR2-specific agonist, peptidoglycan or lipoteichoic acid, did not cause an inflammatory response in intact or DSS-injured mouse colon. Furthermore, intracolonic flagellin administration in mice causes severe apoptosis in colonic epithelium disrupted by DSS administration. These data suggest that intracolonic flagellin via TLR5 engagement is able to elicit inflammatory responses in disrupted colon, whereas the normal colon is not responsive to bacterial flagellin. These results demonstrate that bacterial flagellin plays an important role in the development and progress of colitis.
    Proceedings of the National Academy of Sciences 10/2005; 102(38):13610-5. · 9.68 Impact Factor
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    Article: Rifalazil treats and prevents relapse of clostridium difficile-associated diarrhea in hamsters.
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    ABSTRACT: Although vancomycin and metronidazole effectively treat Clostridium difficile-associated diarrhea and colitis (CDAD), their use is associated with a high incidence of relapsing C. difficile infection. Rifalazil is a new benzoxazinorifamycin that possesses activity against Mycobacterium tuberculosis and gram-positive bacteria. Here we compared rifalazil and vancomycin for effectiveness in preventing or treating clindamycin-induced cecitis in a hamster model of CDAD. Golden Syrian hamsters were injected subcutaneously with clindamycin phosphate (10 mg/kg), followed 24 h later by C. difficile gavage. Hamsters received by gavage for 5 days vehicle, vancomycin (50 mg/kg), or rifalazil (20 mg/kg) either simultaneously with (prophylactic protocol) or 24 h after C. difficile administration (treatment protocol). While all vehicle-administered animals became moribund within 48 h of C. difficile administration, no rifalazil- or vancomycin-treated animals in either protocol showed signs of morbidity after 7 days. Ceca of rifalazil-treated animals showed absence of epithelial cell damage, significantly reduced congestion and edema, and less, but not statistically significantly less, neutrophil infiltration compared to those of vehicle-treated animals. In contrast, vancomycin-treated animals demonstrated severe epithelial cell damage and mildly reduced congestion and edema. Moreover, hamsters relapsed and tested C. difficile toxin positive (by enzyme-linked immunosorbent assay) 10 to 15 days after discontinuation of vancomycin treatment. None of the rifalazil-treated hamsters showed signs of disease or presence of toxins in their feces 30 days after discontinuation of treatment. Our results indicate that once daily rifalazil may be superior to vancomycin for curative treatment of CDAD.
    Antimicrobial Agents and Chemotherapy 11/2004; 48(10):3975-9. · 4.84 Impact Factor
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    Article: Corticotropin-releasing hormone (CRH) requirement in Clostridium difficile toxin A-mediated intestinal inflammation.
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    ABSTRACT: Clostridium difficile, the causative agent of antibiotic-associated colitis, mediates inflammatory diarrhea by releasing toxin A, a potent 308-kDa enterotoxin. Toxin A-induced inflammatory diarrhea involves many steps, including mucosal release of substance P (SP) corticotropin-releasing hormone (CRH) and neutrophil transmigration. Here we demonstrate that, compared with wild type, mice genetically deficient in CRH (Crh(-/-)) have dramatically reduced ileal fluid secretion, epithelial cell damage, and neutrophil transmigration 4 h after intraluminal toxin A administration. This response is associated with diminished mucosal activity of the neutrophil enzyme myeloperoxidase compared with that of wildtype mice. In wild-type mice, toxin A stimulates an increase in intestinal SP content compared with buffer administration. In contrast, toxin A administration in Crh(-/-) mice fails to result in an increased SP content. Moreover, immunohistochemical experiments showed that CRH and SP are colocalized in some enteric nerves of wild-type mice, and this colocalization is more evident after toxin A administration. These results provide direct evidence for a major proinflammatory role for CRH in the pathophysiology of enterotoxin-mediated inflammatory diarrhea and indicate a SP-linked pathway.
    Proceedings of the National Academy of Sciences 07/2004; 101(22):8503-8. · 9.68 Impact Factor
  • Article: Clostridium difficile toxin B is an inflammatory enterotoxin in human intestine.
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    ABSTRACT: Clostridium difficile causes antibiotic-associated diarrhea and pseudomembranous colitis, diseases afflicting millions of people each year. Although C. difficile releases 2 structurally similar exotoxins, toxin A and toxin B, animal experiments suggest that only toxin A mediates diarrhea and enterocolitis. However, toxin A-negative/toxin B-positive strains of C. difficile recently were isolated from patients with antibiotic-associated diarrhea and colitis, indicating that toxin B also may be pathogenic in humans. Here we used subcutaneously transplanted human intestinal xenografts in immunodeficient mice to generate a chimeric animal model for C. difficile toxin-induced pathology of human intestine. We found that intraluminal toxin B, like equivalent concentrations of toxin A, induced intestinal epithelial cell damage, increased mucosal permeability, stimulated interleukin (IL)-8 synthesis, and caused an acute inflammatory response characterized by neutrophil recruitment and tissue damage. Laser capture microdissection and real-time quantitative reverse-transcription polymerase chain reaction (RT-PCR) showed that intestinal epithelial cell-specific IL-8 gene expression also was increased significantly after luminal exposure to C. difficile toxins in vivo. We conclude that C. difficile toxin B, like toxin A, is a potent inflammatory enterotoxin for human intestine. Future therapeutic or vaccine strategies for C. difficile infection therefore need to target both toxins.
    Gastroenterology 08/2003; 125(2):413-20. · 11.68 Impact Factor
  • Article: Colonic metaplasia in the ileal pouch is associated with inflammation and is not the result of long-term adaptation.
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    ABSTRACT: Ileal pouch-anal anastomosis (IPAA) is the preferred surgical therapy for chronic ulcerative colitis (CUC) and familial adenomatous polyposis (FAP). Previous studies have demonstrated morphologic changes in pouch mucosa such as villous atrophy and crypt hyperplasia. These changes have been labeled "colonic metaplasia." The aims of this study were to determine whether these changes represent "normal" long-term adaptation of the nondiseased pouch or instead are present only in the setting of inflammation. Twenty-four patients were identified, greater than 5 years status post-IPAA for CUC, who underwent pouchoscopy for surveillance and had no history of pouchitis. Thirty-one patients were identified greater than 5 years status post-IPAA for CUC, who had a history of pouchitis and had undergone pouchoscopy at least 5 years status post-IPAA. Eight patients status post-IPAA for FAP were also identified. Biopsy specimens were reevaluated by a single, blinded pathologist for degree of inflammation, the presence of villous atrophy and crypt hyperplasia, and evidence of dysplasia. Among the patients with CUC, the inflammation score was greater in the pouchitis group, 13.2 +/- 1.2, compared to the nonpouchitis group, 4.0 +/- 0.5 (P < 0.0001). Median colonic metaplasia score was greater in the pouchitis group (4 [range 2 to 6]) vs. 2 (9 [range 0 to 6]; P < 0.0001). The colonic metaplasia score correlated with the inflammation score (Spearman coefficient r = 0.83; P < 0.0001). In the eight patients with FAP, the inflammation score was 5.1 +/- 0.9 and the median colonic metaplasia score was 1 (range 0 to 4). There was no evidence of dysplasia in any of the biopsy specimens. Patients without a history of pouchitis or symptoms of pouchitis have only a minimal degree of villous atrophy and crypt hyperplasia. These morphologic changes in the ileal pouch are found primarily in the setting of inflammation, and likely represent a reparative response.
    Journal of Gastrointestinal Surgery 03/2003; 7(2):246-53; discussion 253-4. · 2.83 Impact Factor