Microbial Spectrum of Intra-Abdominal Abscesses in Perforating Crohn's Disease: Results from a Prospective German Registry.

BACKGROUND: Intra-abdominal abscesses [IAAs] are common life-threatening complications in patients with Crohn's disease [CD]. In addition to interventional drainage and surgical therapy, empirical antibiotic therapy represents a cornerstone of treatment, but contemporary data on microbial spectra and antimicrobial resistance are scarce. METHODS: We recruited 105 patients with CD and IAAs from nine German centres for a prospective registry in order to characterize the microbiological spectrum, resistance profiles, antibiotic therapy and outcome. RESULTS: In 92 of 105 patients, microbial investigations of abscess material revealed pathogenic microorganisms. A total of 174 pathogens were isolated, with a median of 2 pathogens per culture [range: 1-6]. Most frequently isolated pathogens were E. coli [45 patients], Streptococcus spp. [28 patients], Enterococci [27 patients], Candida [13 patients] and anaerobes [12 patients]. Resistance to third-generation cephalosporins, penicillins with beta-lactamase inhibitors and quinolones were observed in 51, 36 and 35 patients, respectively. Seven patients had multiple-drug-resistant bacteria. Thirty patients received inadequate empirical treatment, and this was more frequent in patients receiving steroids or immunosuppression [37%] than in patients without immunosuppression [10%: p = 0.001] and was associated with a longer hospital stay [21 days vs 13 days, p = 0.003]. CONCLUSION: Based on antimicrobial resistance profiles, we herein report a high rate of inadequate empirical first-line therapy for IAAs in CD, especially in patients receiving immunosuppression, and this is associated with prolonged hospitalization.

Bowel Ultrasonography in Inflammatory Bowel Disease.

BACKGROUND: The diagnosis of inflammatory bowel disease (IBD) is based on a combination of endoscopic, clinical and biochemical investigations as well as cross-sectional imaging. The applications of cross-sectional imaging in IBD are manifold. Ultrasonography has emerged as an important imaging modality in the diagnosis of Crohn's disease (CD) as well as for monitoring disease progression and in the therapeutic response to CD and ulcerative colitis (UC). Key Messages: Ultrasonography is non-invasive, radiation free, cheap, easy to use and well tolerated and accepted by patients. Bowel ultrasonography can be used for the primary diagnosis of CD as it has a similar sensitivity and specificity like that of MRI and CT, particularly in the case of CD. Ultrasonography can also be used to monitor treatment response to therapy and to detect disease recurrence of CD as well as UC. In CD, ultrasonography can also be used to detect complications such as strictures as well as extramural complications, including abscesses and fistulas. Contrast-enhanced ultrasonography is a useful tool that might be helpful to detect certain indications in CD, in particular the differentiation between abscesses and inflammation. CONCLUSION: A variety of advantages of bowel ultrasonography over other imaging modalities suggest the more frequent use of this method to manage IBD patients in daily practice. Bowel ultrasonography should be a standard tool in IBD centers.

CD4+ T cells transfer resistance against Citrobacter rodentium-induced infectious colitis by induction of Th 1 immunity.

Citrobacter rodentium induces an acute, self-limited colitis in mice which is histologically associated with crypt hyperplasia. The infection serves as a model for human infectious colitis induced by enteropathogenic Escherichia coli. We investigated if Balb/c mice, which had spontaneously cleared C. rodentium infection, were protected against re-infection and if resistance against intestinal infection can be systemically transferred using spleen cells. The course of infection was monitored by faecal excretion. Spleen cells, splenic CD3+ and CD4+ cells were transferred from resistant mice to non-infected recipients prior to infection. Cytokine secretion, serum and faecal antibody titres and histological disease severity were assessed. Balb/c mice were resistant against re-infection. The course of infection was shorter in mice receiving primed spleen cells, CD3+ and CD4+ cells. Transfer of CD4+ T cells from resistant mice induced gamma-interferon, interleukin (IL)-2 and IL-17 secretion and suppressed IL-10 secretion. Anti-Citrobacter serum IgG1 and IgG2a enzyme-linked immunosorbent assay OD levels were increased. Faecal IgA secretion was increased while serum IgA was suppressed in recipients of CD4+ cells. Large bowel histology showed protection from colitis in recipients of primed cells as indicated by normal colonic epithelium. In Balb/c mice, C. rodentium infection is followed by resistance, which can be transferred by CD4+ cells. Transfer of protection is associated with IL-17 secretion, enhanced serum IgG and faecal IgA secretion. This is the first study to demonstrate the mechanisms by which systemic resistance from previously C. rodentium-infected mice can be transferred to non-infected animals.

Carbon dioxide insufflation improves intubation depth in double-balloon enteroscopy: a randomized, controlled, double-blind trial.

BACKGROUND AND STUDY AIMS: Double-balloon enteroscopy (DBE) has been proven effective for deep intubation of the small bowel. However, intubation depth is limited by distention of the small bowel due to air insufflation during the procedure. The present trial investigated whether carbon dioxide (CO (2)) instead of standard air insufflation would improve intubation depth during DBE, as well as reduce postprocedure pain. PATIENTS AND METHODS: One hundred and twelve consecutive patients scheduled for DBE at two centers were randomly assigned to either CO (2) or air insufflation during DBE. Patients and endoscopists were blinded with regard to the type of gas used. Intubation depth was registered using a validated form. Patients scored pain and discomfort during and after the examination on a 100-mm visual analog scale. RESULTS: One hundred patients were eligible for data analysis (48 in the CO (2) group and 52 in the air group). The mean small-bowel intubation depth was extended by 30 % in the CO (2) group compared to the air group (230 vs. 177 cm, P = 0.008). The superiority was most pronounced for oral DBE, with a 71-cm improvement in intubation depth when using CO (2) (295 cm in the CO (2) group vs. 224 cm in the air group, P < 0.001). Patient pain and discomfort were significantly reduced in the CO (2) group at 1 and 3 hours after the examination. CONCLUSIONS: CO (2) insufflation significantly extended intubation depth in DBE. CO (2) insufflation also reduces patient discomfort. CO (2) insufflation may lead to a higher diagnostic and therapeutic yield of DBE, with reduced patient discomfort.

Crucial role of the melanocortin receptor MC1R in experimental colitis.

BACKGROUND AND AIMS: alpha-Melanocyte stimulating hormone (alpha MSH) is known to exert anti-inflammatory effects, for example in murine DSS (dextran sodium sulphate induced) colitis. The anti-inflammatory functions of alpha MSH are mediated by the melanocortin1-receptor (MC1R) in an autoregulatory loop. The aim of this study was therefore to determine whether a breakdown of the alpha MSH-MC1R pathway leads to worsening of disease. METHODS: Experimental colitis was induced in mice with a frameshift mutation in the MC1R gene (MC1Re/e), C57BL/6 wild type mice, and MC1Re/e-C57BL/6 bone marrow chimeras. The course of inflammation was monitored by weight loss, histological changes in the colon, and myeloperoxidase activity. In addition, MC1R expression was analysed in intestinal epithelial cells. RESULTS: While the colon of untreated MC1Re/e appeared normal, the course of DSS-colitis in MC1Re/e mice was dramatically aggravated, with a significantly higher weight loss and marked histological changes compared to C57BL/6WT. The inflammation eventually led to death in all MC1Re/e, while all C57BL/6WT survived. Similar observations were detected in a transmissible murine colitis model induced by Citrobacter rodentium. Infected MC1Re/e showed delayed clearance of infection. To determine whether missing haematopoietic cell expressed MC1R was responsible, DSS colitis was induced in MC1Re/e-C57BL/6 bone marrow chimeras. MC1Re/e mice receiving MC1R+ bone marrow showed a similar course of inflammation to non-transplanted MC1Re/e. Likewise, transplantation of MC1R bone marrow into C57BL/6WT mice did not lead to any worsening of disease. CONCLUSIONS: This is the first study to show a functional role of MC1R in intestinal inflammation. The data suggest a pivotal role of non-haematopoietic cell expressed MC1R in the host's response to pathogenic stimuli.

Role of the intestinal epithelium in orchestrating innate and adaptive mucosal immunity.

The mucosa that lines the human colon and small intestine is a site of chronic regulated "physiologic" inflammation. This contrasts markedly with other mucosal sites in that if the numbers of T and B cells, eosinophils, mast cells, macrophages, and dendritic cells that are present in the human intestinal tract were to be present in other sites, those sites would be considered to be sites of chronic pathological inflammation. This review examines the role of the intestinal epithelium in the development of "physiologic" intestinal mucosal inflammation and focuses on its role in signalling and mediating host innate and adaptive mucosal immune responses.

IFN-gamma synergizes with TNF-alpha but not with viable H. pylori in up-regulating CXC chemokine secretion in gastric epithelial cells.

Helicobacter pylori colonizes the gastric epithelial surface and induces epithelial cells to increase production of the neutrophil attractant IL-8. Little is known about the role of the gastric epithelium in regulating mucosal T cell trafficking. We therefore characterized constitutive and regulated epithelial expression of the CXC chemokines IP-10, I-TAC and Mig, which specifically attract CXCR3 expressing CD4(+) T cells. Human gastric epithelial cell lines (AGS, Kato III, NCI) were used to characterize the constitutive and regulated expression of three CXC chemokines in response to IFN-gamma, TNF-alpha and different H. pylori preparations. Chemokine mRNA and protein production were measured by RT-PCR and ELISA. Gastric epithelial cells constitutively expressed mRNA for IP-10, Mig and I-TAC. IFN-gamma in combination with TNF-alpha strongly induced secretion of those chemokines. Soluble or membranous fractions of H. pylori significantly inhibited IFN-gamma/TNF-alpha induced epithelial cell IP-10 and Mig production. Gastric epithelial cells may contribute to mucosal T cell trafficking. The capacity of H. pylori products to inhibit IP-10 and Mig secretion may explain, at least in part, the failure to induce protective immunity against this bacterium and the ability of H. pylori to affect the presentation of the local inflammation.

Colonic epithelial cells induce endothelial cell expression of ICAM-1 and VCAM-1 by a NF-kappaB-dependent mechanism.

Epithelial cells are positioned in close proximity to endothelial cells. A non-contact coculture system was used to investigate whether colonic epithelial cells activated with various cytokines are able to provide signals that can modulate ICAM-1 and VCAM-1 expression on endothelial cells. Coculture of human umbilical vein endothelial cells (HUVEC) and human microvascular endothelial cells (HMEC-1) with TNF-alpha/IFN-gamma-stimulated human colon epithelial cell lines led to a significant up-regulation of endothelial ICAM-1 and VCAM-1 expression. Increased ICAM-1 and VCAM-1 expression by endothelial cells was accompanied by an increase in endothelial cell NF-kappaB p65 and NF-kappaB-DNA-binding activity. Inhibition of endothelial NF-kappaB activation using the proteosome inhibitors MG-132 and BAY 11-7082 resulted in a significant decrease of ICAM-1 expression, indicating an important role for NF-kappaB in this response. This cross-talk may represent a biological mechanism for the gut epithelium to control the colonic inflammatory response and the subsequent immune cell recruitment during inflammation.

Interleukin-15 strongly inhibits interleukin-8 and monocyte chemoattractant protein-1 production in human colonic epithelial cells.

Interleukin-15 (IL-15) is a novel cytokine with actions similar to IL-2 because of common receptor components. Although IL-15 is expressed in colonic epithelial cells and may regulate epithelial cell function, its effects on these cells are not fully defined. We explored the regulatory effects of IL-15 on IL-8 and monocyte-chemoattractant protein-1 (MCP-1) production in the colonic epithelial cell line Caco-2 as well as in freshly isolated human colonic epithelial cells. IL-15 was added to intestinal epithelial cells under various culture conditions. Levels of chemokines were determined by enzyme-linked immunosorbent assay. To determine the elements of the IL-2/IL-15R complex involved we used neutralizing antibodies specific for individual receptor chains. IL-15 down-regulates IL-8 and MCP-1 production in Caco-2 cells as well as in freshly isolated human colonic epithelial cells in a dose-dependent manner. Intestinal epithelial cells became more responsive to IL-15-induced suppression when activated with greater IL-1 doses. Strong chemokine suppression was seen when IL-15 was given prior to, simultaneous with, or after stimulatory agent. Anti-IL-2Rgamma antibodies efficiently blocked (82% inhibition) the suppression induced by IL-15, while anti-IL-2Rbeta antibodies were less effective. The involvement of beta-chain was further suggested by the finding that a mixture of both monoclonal antibodies (mAb) at a suboptimal concentration (1 microgram/ml of each mAb) produced a synergistic inhibitory effect on down-regulation of epithelial chemokine production. These results show that IL-15 can suppress IL-8 and MCP-1 secretion by intestinal epithelial cells. A microenvironment containing high concentrations of IL-15 may alter the recruitment of neutrophils to enterocytes at least partly by inhibiting IL-8 and MCP-1 production.

Transcriptional activation of the human growth hormone gene by ras oncogene.

ras Oncogenes play an important role in causing cellular transformation and proliferation. They have been implicated in the formation of many human tumors but only rarely been identified in pituitary adenomas. We studied the effect of ras activation on growth hormone (GH) production. Transcriptional regulation of human GH was investigated by transient transfections in a pituitary cell line GH4 using different promoter fragments cloned 5' of the luciferase reporter gene (-344 to -83). Co-transfection of the constitutively active valine 12 mutant ras oncogene (V-12 ras) resulted in a selective and dose-dependent stimulation of -344-GH/Luc activity. This effect is pituitary-cell specific as activation of the human GH promoter by ras was absent in a human chorion carcinoma cell line JEG3. Co-transfection of protein kinase inhibitor did not influence ras mediated stimulation of the human GH promoter. Investigations of several deletion constructs of the human GH promoter revealed that elements between - 145 and - 83 are sufficient to transduce ras signaling. This region contains two Pit-1 bindings sites as well as a Zn-15 binding site. These studies demonstrate transduction of ras signaling to the human GH promoter through a protein kinase A (PKA) independent signaling pathway. This separate transduction mechanism may convey regulation by yet unknown factors.