Defective Mucosal Barrier Research Articles

Bacterial translocation: gap in the shield

The gastrointestinal tract is not only regarded as a system where nutrient absorption takes place, but also as a vital barrier against intraluminal pathogens entering the circulation and the maintenance of immune homeostasis. Bacterial translocation is defined as the penetration of viable bacteria or bacterial compounds from the gastrointestinal tract to extraintestinal sites. This disorder has been described in several clinical conditions. The main promoting factors for bacterial translocation have been proposed to be changes in the intestinal microflora, mucosal barrier failure and defects in host immunity. The presence of bacterial translocation has been associated with higher complications and mortality rates; therefore it should be taken into account in the therapeutic strategies of patients with predisposing factors.

Characterisation of enterocolitis in the piroxicam-accelerated interleukin-10 knock out mouse — A model mimicking inflammatory bowel disease

BackgroundIn inflammatory bowel disease a defective mucosal barrier, a dysregulated immune response and an excessive reactivity against the gut microbiota are assumed to cause a breakdown of the intestinal homeostasis and lead to chronic inflammation. Piroxicam treatment is a method for induction of colitis in IL-10 k.o. mice, which integrates a dysfunction of both the intestinal barrier and the immune system. However, the translational value of this model has not been thoroughly clarified. AimTo characterise the piroxicam-accelerated colitis (PAC) IL-10 k.o. model with respect to clinical features, pathogenic mechanisms and its ability to respond to existing therapies. MethodsThe PAC IL-10k.o. model was established on a C57BL/6J background and the clinical manifestations, immunological mechanisms and efficacy of ampicillin and anti-IL-12/23p40 treatment were assessed. ResultsThe PAC IL-10 k.o. mice developed weight loss and diarrhoea, and colonoscopy revealed a thickened granulomatous mucosa. Histological evaluation of ileum and colon showed Crohn's disease-like changes with pronounced hyperplasia and focal transmural inflammation. Ileitis was also observed in piroxicam treated wild type mice. The total number of neutrophils, monocytes and natural killer cells was elevated in the blood compared to IL-10 k.o. and wild type mice, indicating a role of the innate immune system in the pathogenesis. These findings were supported by analyses of the intestinal cytokine profile. Ampicillin and anti-IL-12/23p40 treatment significantly suppressed disease in the model. ConclusionThe PAC IL-10 k.o. model resembles several features of Crohn's disease and could be a useful in vivo model in preclinical research.

Mitochondrial Gene Polymorphisms That Protect Mice From Colitis

Dysregulated energy homeostasis in the intestinal mucosa frequently is observed in patients with ulcerative colitis (UC). Intestinal tissues from these patients have reduced activity of the mitochondrial oxidative phosphorylation (OXPHOS) complex, so mitochondrial dysfunction could contribute to the pathogenesis of UC. However, little is known about the mechanisms by which OXPHOS activity could be altered. We used conplastic mice, which have identical nuclear but different mitochondrial genomes, to investigate activities of the OXPHOS complex. Colitis was induced in C57BL/6J wild-type (B6.B6) and 3 strains of conplastic mice (B6.NZB, B6.NOD, and B6.AKR) by administration of dextran sodium sulfate or rectal application of trinitrobenzene sulfonate. Colon tissues were collected and analyzed by histopathology, immunohistochemical analysis, and immunoblot analysis; we also measured mucosal levels of adenosine triphosphate (ATP) and reactive oxygen species, OXPHOS complex activity, and epithelial cell proliferation and apoptosis. We identified mice with increased mucosal OXPHOS complex activities and levels of ATP. These mice developed less-severe colitis after administration of dextran sodium sulfate or trinitrobenzene sulfonate than mice with lower mucosal levels of ATP. Colon tissues from these mice also had increased enterocyte proliferation and transcription factor nuclear factor-κB activity, which have been shown to protect the mucosal barrier-defects in these processes have been associated with inflammatory bowel disease. Variants in mitochondrial DNA thatincrease mucosal levels of ATP protect mice from colitis. Increasing mitochondrial ATP synthesis in intestinal epithelial cells could be a therapeutic approach for UC.

HIV infection and the intestinal mucosal barrier

HIV infection induces a barrier defect of the intestinal mucosa, which is closely linked to immune activation and CD4 T cell depletion. The HIV-induced barrier defect is initiated in early acute and maintained through chronic infection. In acute infection, increased epithelial permeability is associated with increased epithelial apoptosis possibly caused by perforin-expressing cytotoxic T cells. In chronic infection, mucosal production of inflammatory cytokines is associated with increased epithelial permeability, epithelial apoptosis, and alterations of epithelial tight junctions. In addition to HIV-induced immune-mediated effects, viral proteins have the potential to directly affect epithelial barrier function. After prolonged viral suppression by antiretroviral therapy, there is, at least partial, restoration of the HIV-associated intestinal mucosal barrier defect despite persisting alterations of the mucosal immune system.

Mucosal barrier defects in gastric intestinal metaplasia: in vivo evaluation by confocal endomicroscopy

Helicobacter pylori infection and intestinal metaplasia (IM) are associated with gastric cancer. An impaired gastric mucosal barrier could be involved in this carcinogenesis. To evaluate laser confocal laser endomicroscopy (CLE) for in vivo functional imaging of mucosal barrier defects in patients with IM. Prospective, controlled study. A tertiary-care academic center. This study involved patients with IM of the gastric mucosa who underwent CLE for surveillance. Specific IM mucosa and non-IM mucosa in patients were identified by CLE, and targeted biopsy samples were taken for histopathology and electron microscopy. Post-CLE assessment of paracellular fluorescein leakage was devised and validated by electron microscopy. We also evaluated the effect of H pylori eradication on the mucosal barrier. Forty-two patients were included. Of non-IM samples, the paracellular permeability was significantly increased in H pylori-positive samples compared with H pylori-negative controls (54 ± 31% vs 3 ± 6%, P < .05). Of IM samples, the permeability was significantly increased in both H pylori-negative and H pylori-positive samples (67 ± 34% and 72 ± 28% vs 3 ± 6%, both P < .05). The results of post-CLE assessment correlated well with the electron microscopy findings (R(2) 0.834, P < .0001). After the eradication of H pylori, the paracellular barrier dysfunction of non-IM mucosa was significantly improved as shown by electron microscopy and CLE (both P < .001). However, there was no significant change in IM mucosa. Single-center study. CLE allows functional imaging of mucosal barrier defects. Gastric IM is associated with an impaired paracellular barrier irrespective of H pylori eradication.

Regulatory T Cells in Patients with Whipple’s Disease

Classical Whipple's disease (CWD) is caused by chronic infection with Tropheryma whipplei that seems to be associated with an underlying immune defect. The pathognomonic hallmark of CWD is a massive infiltration of the duodenal mucosa with T. whipplei-infected macrophages that disperse systemically to many other organ systems. An alleviated inflammatory reaction and the absence of T. whipplei-specific Th1 reactivity support persistence and systemic spread of the pathogen. In this article, we hypothesized that regulatory T cells (T(reg)) are involved in immunomodulation in CWD, and we asked for the distribution, activation, and regulatory capacity of T(reg) in CWD patients. Whereas in the lamina propria of CWD patients before treatment numbers of T(reg) were increased, percentages in the peripheral blood were similar in CWD patients and healthy controls. However, peripheral T(reg) of CWD patients were more activated than those of controls. Elevated secretion of IL-10 and TGF-β in the duodenal mucosa of CWD patients indicated locally enhanced T(reg) activity. Enhanced CD95 expression on peripheral memory CD4(+) T cells combined with reduced expression of IFN-γ and IL-17A upon polyclonal stimulation by CD4(+) cells from untreated CWD patients further hinted to T(reg) activity-related exhaustion of effector CD4(+) T cells. In conclusion, increased numbers of T(reg) can be detected within the duodenal mucosa in untreated CWD, where huge numbers of T. whipplei-infected macrophages are present. Thus, T(reg) might contribute to the chronic infection and systemic spread of T. whipplei in CWD but in contrast prevent mucosal barrier defect by reducing local inflammation.

Mucosal immunosuppression and epithelial barrier defects are key events in murine psychosocial stress-induced colitis

Chronic psychosocial stress is a risk factor for many affective and somatic disorders, including inflammatory bowel diseases. In support chronic subordinate colony housing (CSC, 19days), an established mouse model of chronic psychosocial stress, causes the development of spontaneous colitis. However, the mechanisms underlying the development of such stress-induced colitis are poorly understood. Assessing several functional levels of the colon during the initial stress phase, we show a pronounced adrenal hormone-mediated local immune suppression, paralleled by impaired intestinal barrier functions, resulting in enhanced bacterial load in stool and colonic tissue. Moreover, prolonged treatment with broad-spectrum antibiotics revealed the causal role of these early maladaptations in the development of stress-induced colitis.Together, we demonstrate that translocation of commensal bacteria is crucial in the initiation of stress-induced colonic inflammation. However, aggravation by the immune-modulatory effects of fluctuating levels of adrenal hormones is required to develop this into a full-blown colitis.

Acute HIV Infection Induces Mucosal Infiltration With CD4+ and CD8+ T Cells, Epithelial Apoptosis, and a Mucosal Barrier Defect

A barrier defect of the intestinal mucosa is thought to affect the progression of human immunodeficiency virus (HIV) infection. It is not clear whether the mucosal barrier impairment already is present in acute infection and what mechanisms cause this defect. We analyzed T-cell subsets, epithelial apoptosis, and barrier function of the duodenal mucosa in patients with acute HIV infection. Mucosal T-cell subsets, epithelial apoptosis, and barrier function were assessed by immunohistochemistry, immunofluorescence, flow cytometry, and impedance spectroscopy in duodenal samples from 8 patients with early acute infection, 8 patients with chronic infection, and 9 HIV-negative individuals (controls). One patient was analyzed serially, before and during acute infection. Compared with controls, densities of mucosal CD8+ and, surprisingly, of mucosal CD4+ T cells too, increased in patients with acute infection. Most mucosal CD4+ T cells had an activated effector memory phenotype (CD45RA-CD45RO+CD62L-CD40L+CD38+) and did not proliferate. Perforin-expressing mucosal CD8+ T cells also were increased in acutely infected patients; their frequency correlated with epithelial apoptosis. The epithelial barrier was impaired significantly in patients with acute HIV infection. The patient analyzed serially developed increased densities of mucosal CD4+ and CD8+ T cells, increased apoptosis of epithelial cells, and mucosal barrier impairment during acute infection. Before depleting CD4+ T cells, acute HIV infection induces infiltration of the mucosa with activated effector memory CD4+ and CD8+ T cells. The HIV-induced barrier defect of the intestinal mucosa is evident already in acute infection; it might arise from increased epithelial apoptosis, induced by perforin-positive mucosal cytotoxic T cells.

Magnetic Resonance Imaging Detects Intestinal Barrier Dysfunction in a Rat Model of Acute Mesenteric Ischemia/Reperfusion Injury

To develop an in vivo intestinal permeability assay applying magnetic resonance imaging (MRI) to monitor real-time gut barrier defects in animal models of acute mesenteric ischemia/reperfusion (I/R) insult. Twenty Wistar rats were divided to 2 groups for I/R challenge or sham controls. I/R rats received occlusion of superior mesenteric artery for 20 minutes and reperfusion for 1 hour. Sham-operation controls received laparotomy without manipulation of artery. To assess gut permeability, a 10-cm jejunal sac was created distal to the ligament of Treitz in both groups of rats after laparotomy, and a contrast agent (gadodiamide) was injected into the lumen of the ligated intestinal sac. The signals produced by gadodamide in the liver, kidney, and plasma before and after the start of reperfusion were examined by 1.5 Tesla MRI (GE Signa Excite), and the increment of signal-to-noise ratio (SNR) in these organs that parallels the luminal-to-serosal flux rate of the probe was used as an indicator of gut permeability. At the end of procedures, jejunal tissues and mucosal scrapings were collected for histologic examination and Western blotting for epithelial tight junctional proteins. Moreover, liver and spleen homogenates were cultured on fresh blood agar plates to measure the bacterial colony-forming units per gram of tissue. In I/R rats, disrupted villous structure and decreased epithelial tight junctional expression were seen in the jejunum associated with massive enteric bacterial translocation to the liver and spleen. The SNR in the liver of I/R rats was higher than sham controls (2.65 +/- 0.56 vs. 0.65 +/- 0.26, P < 0.01) at 15 minutes postreperfusion. Elevation of SNR in the kidney was also found in I/R rats compared with sham controls (11.61 +/- 2.07 vs. 3.06 +/- 1.15, P < 0.05). The plasma gadodiamide concentration in I/R rats was significantly increased compared with sham controls (0.220 +/- 0.044 vs. 0.006 +/- 0.004 mM, P < 0.01) at 15 minutes postreperfusion. This novel MRI-based intestinal permeability assay has shown a significant increase in the signal intensity in liver, kidney, and plasma samples that correlated with mucosal barrier defects in experimental models of acute mesenteric I/R.

M1686 Epithelial MLCK and iNOS Are Involved in Mucosal Barrier Defects and Bacterial Translocation Induced By Ileal Obstruction

M1686 Epithelial MLCK and iNOS Are Involved in Mucosal Barrier Defects and Bacterial Translocation Induced By Ileal Obstruction

Impairment of the intestinal barrier is evident in untreated but absent in suppressively treated HIV-infected patients

Background and aims:Impairment of the gastrointestinal mucosal barrier contributes to progression of HIV infection. The purpose of this study was to investigate the effect of highly active antiretroviral therapy (HAART)...

Probiotics and Irritable Bowel Syndrome

Growing evidence suggests a potential role of intestinal microbiota in irritable bowel syndrome (IBS) pathophysiology and symptom generation. Earlier studies based on classic microbiologic techniques hypothesized the presence of qualitative changes in intestinal microbiota in IBS patients. Recently, studies with molecular techniques have provided evidence of significant changes in microbial profiles in IBS and that the composition may be correlated with certain symptoms reported by patients. Although these studies are far from being exhaustive and conclusive they provide promising results that deserve further investigation. In addition, initial evidence indicated the presence of increased amounts of bacteria in the upper small intestine of IBS patients, a condition know as small intestinal bacterial overgrowth. However, the results of these studies have provided contradictory results suggesting that this area requires further work. These qualitative and quantitative changes in intestinal microbiota may induce different effects on the intestinal mucosa including mucosal barrier defects and immune activation which may contribute to symptom generation. Studies in IBS patients have attempted to target changes in intestinal microflora with different therapeutic approaches, such as the use of prebiotics, probiotics, synbiotics, and nonabsorbable and systemic antibiotics. Overall, the results obtained in probiotic clinical trials suggest some beneficial effect over placebo in the relief of IBS symptoms. However, these results, although encouraging, should be confirmed in larger well-designed, placebo-controlled studies. A number of open questions remain to be addressed, including the dose, type, and time of administration of probiotics.

Loci on 20q13 and 21q22 are associated with pediatric-onset inflammatory bowel disease

Inflammatory bowel disease (IBD) is a common inflammatory disorder with complex etiology that involves both genetic and environmental triggers, including but not limited to defects in bacterial clearance, defective mucosal barrier and persistent dysregulation of the immune response to commensal intestinal bacteria. IBD is characterized by two distinct phenotypes: Crohn's disease (CD) and ulcerative colitis (UC). Previously reported GWA studies have identified genetic variation accounting for a small portion of the overall genetic susceptibility to CD and an even smaller contribution to UC pathogenesis. We hypothesized that stratification of IBD by age of onset might identify additional genes associated with IBD. To that end, we carried out a GWA analysis in a cohort of 1,011 individuals with pediatric-onset IBD and 4,250 matched controls. We identified and replicated significantly associated, previously unreported loci on chromosomes 20q13 (rs2315008[T] and rs4809330[A]; P = 6.30 x 10(-8) and 6.95 x 10(-8), respectively; odds ratio (OR) = 0.74 for both) and 21q22 (rs2836878[A]; P = 6.01 x 10(-8); OR = 0.73), located close to the TNFRSF6B and PSMG1 genes, respectively.

Bacteria in Crohn's Disease

Microbial agents are implicated in each of the most prevalent etiologic hypotheses of Crohn's disease. Although chronic infection with a specific, persistent pathogen cannot be excluded, it is more likely that Crohn's disease is caused by an overly aggressive immune response to normal commensal enteric bacteria. The complex, predominantly anaerobic microbiota in the distal ileum and colon provide a constant source of antigens and adjuvants that stimulate chronic immune-mediated inflammation in genetically susceptible hosts. Host genetic susceptibility in the form of defective mucosal barrier function, bacterial killing or processing can lead to enhanced exposure to luminal bacteria and their immunologically active components, whereas defective immunoregulation can lead to lack of appropriate immunosuppression. Either process can lead to overly aggressive T-cell responses to normal bacteria that causes tissue damage. Transient infection with pathogenic organisms could serve as environmental triggers to initiate inflammatory responses that are perpetuated in susceptible hosts by commensal microbial antigens. In addition, commensal bacteria such as Escherichia coli recovered from the ileum of patients with recurrent Crohn's disease after resection can contain virulence factors that mediate epithelial attachment, invasion, and resistance to killing. Finally, Western diet, antibiotic use, hygiene, and public health practices may have altered the balance of beneficial versus aggressive microbial species. Crohn's disease patients exhibit enhanced humoral and T-cell responses to common commensal bacterial and fungal antigens. These observations may help identify clinically relevant patient subsets and suggest novel therapeutic approaches to restore a beneficial balance of enteric microbiota, enhanced microbial killing, and inhibit aggressive T-cell responses to microbial antigens.

Measuring the Quality of Endoscopy

There has been recent interest into the potential role of cellular and molecular mechanisms in the pathophysiology of irritable bowel syndrome (IBS). Although the intestinal mucosa of IBS patients is endoscopically and histologically "normal," it contains an increased number of activated T lymphocytes and mast cells, along with evidence of an increased release of mediators known to signal to epithelial, neuronal, and muscle cells leading to intestinal dysfunction. In this issue, Dunlop et al. provide evidence of increased intestinal permeability in patients with diarrhea predominant IBS. There is now consistent evidence indicating that mucosal barrier defects allow the passage of an increased load of luminal antigens of dietary and bacterial origin which, in turn, elicit the activation of mucosal immune responses involved in the generation of diarrhea. Further work has now to be done to better understand the interplay among luminal factors, epithelial cells, and mucosal immunocytes in the pathogenesis of IBS.

Inflammatory bowel disease: Epidemiology, pathogenesis, and therapeutic opportunities

Ulcerative colitis (UC) and Crohn's disease (CD), the primary constituents of inflammatory bowel disease (IBD), are precipitated by a complex interaction of environmental, genetic, and immunoregulatory factors. Higher rates of IBD are seen in northern, industrialized countries, with greater prevalence among Caucasians and Ashkenazic Jews. Racial gaps are closing, indicating that environmental factors may play a role. IBD is multigenic, with the most clearly established genetic link between certain NOD2 variants and CD. Regardless of the underlying genetic predisposition, a growing body of data implicates a dysfunctional mucosal immune response to commensal bacteria in the pathogenesis of IBD, especially CD. Possible triggers include a chronic inflammatory response precipitated by infection with a particular pathogen or virus or a defective mucosal barrier. The characteristic inflammatory response begins with an infiltration of neutrophils and macrophages, which then release chemokines and cytokines. These in turn exacerbate the dysfunctional immune response and activate either TH1 or TH2 cells in the gut mucosa, respectively associated with CD and, less conclusively, with UC. Elucidation of immunological and genetic factors indicate multiple points at which the inflammatory cascade may be interrupted, yielding the possibility of precise, targeted therapies for IBD.

Altered immune system glycosylation causes colitis in alpha1,2-fucosyltransferase transgenic mice.

Altered glycosylation of the mucosal barrier has been proposed as a primary defect in the pathogenesis of IBD. Glycosylation defects however may also have a profound influence on immune function. Mice transgenic for human alpha1,2-fucosyl-transferase (hFUT1) have widespread disturbances in cell surface glycosylation and spontaneously develop colitis. The aims of this study were to characterize colitis in hFUT1 mice and to determine whether glycosylation-induced changes of the mucosal barrier or the immune system were critical for its pathogenesis. The pathologic features of hFUT1 transgenic mice were characterized. The mucosal barrier was assessed by lectin binding and permeability studies. T-cells and the thymus were assessed by FACS analysis and histology. To isolate the hFUT1 mucosal barrier from the hFUT1 immune system, bone marrow chimeras were generated. Seventy percent of hFUT1 mice raised in SPF conditions developed histologic evidence of colitis. The mucosal barrier demonstrated altered glycosylation but intestinal permeability was preserved. HFUT1 mice were profoundly lymphopenic, with aberrant T-cell markers and thymic medullary hypoplasia. Reconstitution with wild type bone marrow restored thymic morphology and prevented colitis in hFUT1 mice. Altered glycosylation in hFUT1 mice has a profound influence on T-cell development and this defect, rather than a mucosal barrier defect, is crucial for the development of colitis.

Alterations in Serum Anti-α-Galactosyl Antibodies in Patients with Crohn's Disease and Ulcerative Colitis

Anti-galactosyl α1-3-galactosyl (anti-Gal) is a natural serum antibody abundantly produced in humans in response to immune stimulation by enteric bacteria. Marked elevation of its titer has been detected in parasitic diseases and in some autoimmune disorders. Because persistent intestinal infection and defective mucosal barrier have been suggested as potential etiologic agents of inflammatory bowel disease, the aim of this study was to analyze the sera levels of anti-Gal antibodies in patients with Crohn's disease and ulcerative colitis. An ELISA assay was performed to analyze circulating antibody using the disaccharide Gal (α1-3)Gal coupled to human serum albumin as antigen and alkaline phosphatase-conjugated rabbit anti-human immunoglobulin G, A, M as antibody. Immunoglobulin classes were assayed using class-specific antibodies. The optical densities of sera from Crohn's disease (1.83 ± 0.63) and ulcerative colitis (1.45 ± 0.7) were significantly higher (P < 0.0001 and P < 0.0005, respectively) than those of the control group (0.97 ± 0.39). In Crohn's disease the increase was distributed among the three immunoglobulin classes; in ulcerative colitis a significant increase was observed only for immunoglobulin A. The increased levels of circulating antibodies against Gal (α1-3)Gal in the presence of intestinal bacterial strains expressing antigenic epitopes and breakdown of mucosal barrier could contribute to the dysregulated immune response observed in inflammatory bowel disease.

Somatic mutations of the trefoil factor family 1 gene in gastric cancer

Background & Aims: There is increasing evidence that trefoil factor family 1 (TFF1) is a stabilizer of the mucous gel overlying the gastrointestinal mucosa that provides a physical barrier against various noxious agents. TFF1 knockout mice developed multiple gastric adenomas and carcinomas, suggesting that TFF1 is a gastric-specific tumor-suppressor gene. Methods: We analyzed the somatic mutations and loss of heterozygosity (LOH) of the TFF1 gene using an intragenic polymorphic marker in 61 gastric tumors. The expression pattern of TFF1 was also examined by immunohistochemistry. Results: We detected a total of 8 somatic mutations—1 (5.5%) of 18 adenomas and 7 (16.3%) of 43 carcinomas—that were all missense mutations confined to the loop I and loop II structure of TFF1. We detected LOH in 5 (1 in adenoma and 4 in cancer) of 30 (16.7%) informative gastric tumors with an intragenic polymorphic marker −2 base pairs (bp) upstream of the coding region of the TFF1 gene. Although 2 cases were noninformative, the 7 gastric cancers with mutation seemed to show the loss of the remaining allele except in 1 case, suggesting that TFF1 is a tumor-suppressor gene. We found loss of TFF1 expression in 44.2% of the gastric carcinomas, but there is no correlation between immunoreactivity and genetic alterations of the TFF1 gene. Conclusions: These results indicate that genetic alterations of TFF1 may lead to gastric mucosal barrier defects and contribute to the pathogenesis of gastric cancer.GASTROENTEROLOGY 2000;119:691-698

Mediators of Inflammation in Chronic Inflammatory Bowel Disease

A distinguishing feature of inflammatory bowel disease (IBD) is its apparently spontaneous, chronic relapsing course. Despite extensive research over several decades the etiology of IBD remains unknown, but evidence has accumulated to suggest that the mucosal inflammatory response may be caused by (i) a defective mucosal barrier function resulting in an abnormally increased exposure to luminal antigens and toxins, (ii) an appropriate immunologic response to an unusual infection, antigen or toxin, or (iii) an inappropriate immunological response to ubiquitous antigens or stimuli. In recent years, the identification of established and potential mediators of inflammation has expanded to include eicosanoids, platelet activating factor, biogenic amines, kinins, complement-derived peptides, chemotactic peptides, cytokines, neuropeptides, and reactive metabolites of oxygen and nitrogen. Thus, the study of the inflammatory process has become ever more complex. Until the predisposing and trigger factors have been identified the achievement of a more rational and effective approach to therapy in IBD relies on interruption of the mechanisms responsible for excess mediator formation. As summarized in this review on the role of soluble mediators of inflammation, several Danish gastroenterologists have been profoundly engaged in basic and clinical research in the past 25 years to place some pieces of the confusing puzzle of IBD.