Elevation of interleukin-6 in inflammatory bowel disease is macrophage- and epithelial cell-dependent

Evidence for the role of gastric mucosa at the secretion of soluble triggering receptor expressed on myeloid cells (strem-1) in peptic ulcer disease

AIM: To investigate the role of gastric mucosa at the secretion of sTREM-1 in peptic ulcer.

METHODS: Seventy two patients were enrolled; 35 with duodenal, 21 with gastric ulcer and 16 with chronic gastritis. Patients were endoscoped and gastric juice was aspirated. Patients with duodenal and gastric ulcer underwent a second endoscopy post-treatment. Biopsies were incubated in the absence/presence of endotoxins or gastric juice. Supernatants were collected and sTREM-1 and TNFα were measured by enzyme immunoabsorbent assays. Scoring of gastritis was performed before and after treatment according to updated Sydney score.

RESULTS: Patients with duodenal and gastric ulcer and those with chronic gastritis had similar scores of gastritis. sTREM-1 was higher in supernatants of tissue samples of H pylori-positive than of H pylori-negative patients with gastric ulcer. Median (± SE) sTREM-1 was found increased in supernatants of patients with gastric ulcer before treatment (203.21 ± 88.91 pg/1000 cells) compared to supernatants either from the same patients post-treatment (8.23 ± 5.79 pg/1000 cells) or from patients with chronic gastritis (6.21 ± 0.71 pg/1000 cells) (P < 0.001 and < 0.001, respectively). Similar differences for sTREM-1 were recorded among LPS-stimulated tissue samples of patients (P = 0.001). Similar differences were not found for TNFα. Positive correlations were found between sTREM-1 of supernatants from patients with both duodenal and gastric ulcer before treatment and the degree of infiltration of neutrophils and monocytes.

CONCLUSION: sTREM-1 secreted by the gastric mucosa is an independent mechanism connected to the pathogenesis of peptic ulcer. sTREM-1 was released at the presence of H pylori from the inflamed gastric mucosa in the field of gastric ulcer.

Il-6 signaling in inflammatory bowel disease: pathophysiological role and clinical relevance

Crohn's disease (CD) and ulcerative colitis (UC) are chronic inflammatory bowel diseases (IBDs) occurring in the gut of genetically susceptible individuals independent of a specific pathogen. The interaction between antigen-presenting cells and the local bacterial flora contributes to an uncontrolled activation of mucosal CD4+ T lymphocytes with the consecutive release of proinflammatory cytokines such as tumor necrosis factor (TNF), interleukin (IL)-6, IL-12, IL-23, IL-27, and also IL-17, which is attributed to a specific, differentiated CD4+ lineage called Th17 (TH-IL17, THi). Recent data suggest that IL-6 contributes to Th17 differentiation. However, to clarify the importance of Th17 cells in IBD further data are needed. So far, CD has been attributed to a Th1-mediated disease, whereas UC exhibits a modified Th2 cytokine response. In both diseases CD4+ T cells at the site of inflammation are critically dependent on antiapoptotic IL-6 signaling. Thereby, IL-6 induces the transcription factor STAT-3 via transsignaling (activation of a cell lacking membrane-bound IL-6 receptor via soluble IL-6 receptor). STAT-3 itself induces the antiapoptotic factors bcl-2 and bcl-xL, thus resulting in T-cell resistance against apoptosis. This vicious circle of T-cell accumulation, mediated by apoptosis resistance, finally leading to chronic inflammation, can be blocked by anti-IL-6 receptor antibodies. This review highlights the role of IL-6 in IBD immunopathogenesis and its clinical relevance in IBD therapy and diagnostics.

Rebamipide enema therapy as a treatment for patients with active distal ulcerative colitis

BACKGROUND

The clinical efficacy of corticosteroids in the treatment of ulcerative colitis (UC) is well-established. However, prolonged usage of these drugs can result in serious complications. Rebamipide {2-(4-chlorobenzoylamino)-3[2-(1H)-quinolinon-4-yl] propionic acid}, a cytoprotective agent, has been reported to have anti-inflammatory activity and to repair mucosal injury in animal colitis models. The aim of the present study was to assess the clinical efficacy and safety of a novel Rebamipide enema therapy in UC patients.

METHODS

Twenty patients with the active distal type of UC in whom corticosteroid treatment had been unsuccessful were treated with rectal administration of Rebamipide twice a day for 3 weeks, during which corticosteroid dosage was kept constant. The efficacy of treatment was assessed from clinical symptoms and endoscopic findings. The anti-inflammatory effect of Rebamipide was also examined by monitoring changes in the intensity of histological inflammation and levels of cytokine activity in the rectal mucosa.

RESULTS

At 3 weeks after the initiation of Rebamipide enema therapy, 11 patients (55%) achieved clinical remission. Sixteen (80%) were colonoscopically judged to be responders, with decreased levels of interleukin (IL)-1beta but not of IL-8, and an increased ratio of IL-1 receptor antagonist/IL-1beta in organ cultures of mucosal tissues. The change in the number of infiltrating neutrophils was not significantly correlated with the clinical response to this therapy. No side-effects were noted in any patients.

CONCLUSION

Rebamipide enema therapy proved to be safe and useful in corticosteroid-refractory patients with the active distal type of UC.

Localized colonic inflammation increases cytokine levels in distant small intestinal segments in the rat

Local inflammation in the colon has been associated with nutrient malabsorption and altered motility in the small bowel. These remote effects suggest the release of mediators which can act (or alter) the function of intestinal segments located far from the primary area of inflammation. This study describes the changes in the expression of pro-inflammatory cytokines in the colon and in various segments of the small intestine in two rat models of experimental colitis. Colitis was induced by the intracolonic administration of 100 microL of 6% iodoacetamide or 250 microL of 2, 4, 6-trinitrobenzene sulfonic acid. Levels of interleukin one beta, interleukin 6, and tumor necrosis factor alpha were measured by ELISA in tissue homogenate sampled from duodenum, jejunum, ileum and colon at different time intervals. In homogenates of strips isolated from duodenum, jejunum and ileum, tumor necrosis alpha and interleukin-6, increased significantly 3-6 h after iodoacetamide or TNBS administration and remained elevated until the colonic inflammation subsided. Interleukin one beta showed comparable but delayed increase. Similar, but more pronounced increase of the three cytokines was noticed in areas of the colon adjacent to the ulcer. Histologic examinations revealed important inflammatory changes in the colon; however, examination of sections from the small intestines did not reveal significant differences between controls and rats with colitis. In conclusion, expression of pro-inflammatory cytokines is increased in remote segments of the small intestines during colitis. The findings may provide a partial explanation or a molecular substrate for the associated small bowel dysfunction.

Interleukin-6 trans-signaling in inflammatory bowel disease

The pathogenesis of inflammatory bowel disease (IBD) is complex, involving a wide range of molecules including cytokines. Recent investigations support the important role of an interleukin-6 (IL-6) signaling pathway in the development of IBD. However, the molecular mechanisms of this pathway in the intestine remain incompletely understood. The circulating and intestinal levels of IL-6 as well as soluble IL-6 receptor (sIL-6R) are increased in patients with IBD. It is remarkable that the mucosal T cells of IBD patients are extremely resistant to apoptosis and that a large fraction of these cells express membrane-bound gp130 but not IL-6R. The accumulated evidence strongly supports the hypothesis that the development and perpetuation of IBD relies on the increased formation of IL-6/sIL-6R complexes interacting with membrane-bound gp130 on T cells via trans-signaling. These studies suggest that IL-6 trans-signaling may play a role in the development of IBD; they therefore imply the possibility of a selective therapeutic strategy to target this signaling.

Improvement of real-time polymerase chain reaction for quantifying TNF-alpha mRNA expression in inflamed colorectal mucosa: an approach to optimize procedures for clinical use

OBJECTIVE

The precise measurement of local tumor necrosis factor alpha (TNF-alpha) expression in tissue is important in understanding the pathogenesis of inflammatory bowel diseases (IBD). Real-time polymerase chain reaction (PCR) is a sensitive, versatile method and is becoming a commonly used tool for the quantification of gene expression. The aim of this study was to optimize the laboratory procedure for biopsy sampling, storage and calibration of result for TNF-alpha mRNA quantification with real-time PCR of colorectal biopsies.

MATERIAL AND METHODS

Endoscopic biopsies from the colorectum were obtained from 18 patients with ulcerative colitis (UC), 11 patients with Crohn's disease (CD) and 18 normal controls. Optimization of procedures for real-time PCR performance was carried out.

RESULTS

The transport medium, RNAlater, exhibited a high preservation effect against RNA degradation even after 8 days of storage at room temperature; one biopsy from each patient was sufficient for RNA extraction, cDNA synthesis and TNF-mRNA quantification. An assay was established with a technical reproducible sensitivity of 100 copies/microL. The observed interassay variations were 7.4 % coefficient of variation (CV) and 7.2 % CV in low and high TNF-alpha mRNA expression biopsies, respectively. TNF-alpha mRNA levels in colorectal biopsies from patients with either CD or moderate to severe UC were markedly increased, and 8 approximately 9-fold higher than those in healthy controls.

CONCLUSIONS

This optimization improves the clinical use of real-time PCR for quantification of TNF-alpha gene expression in colorectal biopsies and provides a sensitive reproducible assay.

Therapeutic mechanism of Changyanqing in treatment of colitis induced by dextran sulfate sodium

AIM: To investigate the therapeutic effects of Changyanqing on dextran sulfate sodium(DSS)-induced colitis and its mechanism.

METHODS: DSS was used to establish the model of experimental colitis in 40 mice. Then the mice were averagely randomized into 4 groups (A, B, C, and D). The mice in group A, B, and C were treated with Changyanqing, salicylazosulfapyridine (SASP), and Changyanqing + SASP, respectively, and those in group D served as controls. Changyanqing was administratered by gastric irragation at a dose of 0.2 mL/(20g•d) for 7 d. The disease activity index (DAI) and the activity of intestinal myeloperoxidase (MPO) were observed. The levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and IL-6 mRNA were detected by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS: In comparison with those in the controls, the DAI (1.413 ± 0.835 vs 2.167 ± 0.911, P < 0.05), and activity of MPO (72.4 ± 0.590 nkat/g vs 117.0 ± 0.902 nkat/g, P < 0.05), and the expression of TNF-α (0.841 ± 0.190 vs 1.320 ± 0.282, P < 0.05), IL-1β (0.641 ± 0.095 vs 0.920 ± 0.082, P < 0.05), and IL-6 (1.241 ± 0.247 vs 1.620 ± 0.312, P < 0.05) mRNA were significantly decreased in group A. The above decreases were more significant in group C (DAI: 0.608 ± 0.449; MPO: 27.3 ± 0.211; TNF-α: 0.339 ± 0.081; IL-1β: 0.239 ± 0.073; IL-6: 0.639 ± 0.141)(P < 0.01). There was marked difference between group A and B (P > 0.05).

CONCLUSION: Changyanqing is effective in the treatment of DSS-induced colitis, which may be associated with the decrease of DAI, MPO activity, and TNF-α, IL-1β and IL-6 mRNA expression.

Involvement of IL-6 in the pathogenesis of inflammatory bowel disease and colon cancer

Inflammatory bowel disease (IBD), which consists of Crohn's disease and ulcerative colitis, is defined as a chronic inflammation of the gastrointestinal tract. The etiopathogenetic mechanisms underlying the development of IBD are still not completely understood, and the therapeutic strategies used thus far have been limited to mostly evidence-based principles. There is growing evidence that the pro-inflammatory cytokine interleukin (IL)-6 plays a crucial part in the uncontrolled intestinal inflammatory process, which is a main characteristic of IBD. There is elevated production of IL-6 and its soluble receptor (sIL-6R) by intestinal macrophages and CD4+T-cells. The increased formation of IL-6-sIL-6R complexes that interact with gp130 on the membrane of CD4+T-cells (trans-signaling) lead to an increased expression and nuclear translocation of STAT3, which causes the induction of anti-apoptotic genes, such as Bcl-xl. This leads to an augmented resistance of lamina propria T-cells to apoptosis. The ensuing T-cell expansion contributes to the perpetuation of chronic intestinal inflammation. This understanding concerning the predominant pathogenic role of an IL-6-dependent inflammatory cascade may lead to the development of new therapeutic strategies in the treatment of this disease. Recent studies have also suggested a potential role of IL-6-sIL-6R in the pathogenesis of colon cancer and, therefore, imply a possible novel therapeutic strategy targeting the sIL-6R and ensuing IL-6 trans-signaling.

Involvement of IL-6 in the pathogenesis of inflammatory bowel disease and colon cancer

Inflammatory bowel disease (IBD), which consists of Crohn's disease and ulcerative colitis, is defined as a chronic inflammation of the gastrointestinal tract. The etiopathogenetic mechanisms underlying the development of IBD are still not completely understood, and the therapeutic strategies used thus far have been limited to mostly evidence-based principles. There is growing evidence that the pro-inflammatory cytokine interleukin (IL)-6 plays a crucial part in the uncontrolled intestinal inflammatory process, which is a main characteristic of IBD. There is elevated production of IL-6 and its soluble receptor (sIL-6R) by intestinal macrophages and CD4+T-cells. The increased formation of IL-6-sIL-6R complexes that interact with gp130 on the membrane of CD4+T-cells (trans-signaling) lead to an increased expression and nuclear translocation of STAT3, which causes the induction of anti-apoptotic genes, such as Bcl-xl. This leads to an augmented resistance of lamina propria T-cells to apoptosis. The ensuing T-cell expansion contributes to the perpetuation of chronic intestinal inflammation. This understanding concerning the predominant pathogenic role of an IL-6-dependent inflammatory cascade may lead to the development of new therapeutic strategies in the treatment of this disease. Recent studies have also suggested a potential role of IL-6-sIL-6R in the pathogenesis of colon cancer and, therefore, imply a possible novel therapeutic strategy targeting the sIL-6R and ensuing IL-6 trans-signaling.

Tumor necrosis factor alpha reduces butyrate oxidation in vitro in human colonic mucosa: a link from inflammatory process to mucosal damage?

BACKGROUND

Butyrate produced by colonic bacterial fermentation is the main fuel for colonocytes, glucose being an alternative fuel. During inflammatory bowel disease, butyrate oxidation by colonocytes is impaired, and increased production of proinflammatory cytokines is detected in the colonic mucosa. We hypothesized that proinflammatory cytokines might reduce butyrate oxidation, and we assessed the in vitro effects of 3 proinflammatory cytokines on butyrate and glucose oxidation in colonic mucosa.

METHODS

Colonic biopsies were obtained from normal mucosa in 42 patients who underwent a colonoscopy. Biopsies were incubated in RPMI 1640 with [1-14C]-butyrate or [U-14C]-glucose with or without 1 of the 3 following proinflammatory cytokines: tumor necrosis factor alpha (TNFalpha), interleukin (IL)-1beta, and IL-6. For each cytokine, 4 different concentrations were tested in 8 subjects. Concentrations overlapped those commonly found in inflamed mucosa and had no cytotoxicity as assessed in preliminary experiments using both the trypan blue exclusion test and lactate dehydrogenase release. Production of 14CO2 (picomoles per microgram dry weight per hour) was measured after a 2-hour incubation and expressed as a percentage of the control [14C]-substrate oxidation without cytokines.

RESULTS

Whereas glucose oxidation was not affected, butyrate oxidation was reduced significantly (P < 0.05) by TNFalpha at concentrations of 100 (-26 +/- 6%), 1000 (-32 +/- 7%), and 5000 pg/mL (-34 +/- 5%). IL-1beta (0, 500, 5000, and 25,000 pg/mL) and IL-6 (0, 100, 1000, and 5000 pg/mL) did not affect either substrate oxidation.

CONCLUSIONS

TNFalpha at concentrations found in inflamed mucosa reduces butyrate oxidation in vitro in mucosa from healthy controls. This result is not caused by a cytotoxic effect of TNFalpha and is not balanced by an increased oxidation of glucose. Reduced butyrate oxidation results in a decreased energy supply to colonocytes and may explain, in part, mucosal damage occurring during attacks of inflammatory bowel disease.

Modulation of nitric oxide and cytokines production by l-arginine in human gut mucosa

BACKGROUND

Arginine is a conditionally essential amino-acid with immuno-modulatory properties, mainly through the nitric oxide (NO) pathway.

AIM

To assess the effects of arginine on intestinal production of pro- and anti-inflammatory cytokines and NO in human gut.

METHODS

An enteral solution of arginine or a control solution of amino-acids was administered to 8 healthy volunteers on a randomized cross-over design. Duodenal biopsies were taken. Pro- (IL-6, IL-8) and anti-inflammatory (IL-4, IL-10) cytokines mRNA expression was assessed by RT-PCR. Other biopsies were cultured with 0.1, 0.5 or 2 mM arginine or control amino-acids, under basal or IL-1beta-induced inflammatory conditions. Interleukin-4, IL-6, IL-8 and IL-10 production was measured in culture supernatant by ELISA and NO production by Griess reaction.

RESULTS

Arginine enhanced the production of NO under inflammatory conditions in a dose-dependent manner (P=0.03). IL-1beta increased the production of IL-8 and IL-6 (P<0.01). Arginine had no effect on pro- and anti-inflammatory cytokines production both under basal and inflammatory conditions.

CONCLUSIONS

Arginine enhanced the production of NO but did not affect that of cytokines in inflammatory human gut. Further clinical studies are required to assess whether arginine-enhanced NO production plays a beneficial or deleterious effect in intestinal inflammation.

Signal transducers and activators of transcription 3 signaling pathway: an essential mediator of inflammatory bowel disease and other forms of intestinal inflammation

Crohn's disease (CD) and ulcerative colitis (UC), the two major forms of chronic inflammatory bowel disease (IBD), are characterized by mucosal immune cell activation that is driven by a cytokine imbalance. Several cytokines involved in IBD act through the activation of the signal transducers and activators of transcription (STAT) family. We investigated the activation of STAT3 in the mucosa of CD and UC patients, and evaluated whether this event is specific for IBD patients. Using immunofluorescence and immunoblotting, total and phosphorylated STAT3 levels were assessed in biopsy specimens, isolated lamina propria mononuclear cells, and peripheral blood mononuclear cells from patients with CD, UC, other forms of intestinal inflammation, and control subjects. Immunoblotting revealed phosphorylated STAT3 in mucosal biopsy specimens from patients with CD, UC, celiac disease, and acute self-limited colitis, but not in the normal mucosa of control subjects. In IBD patients, STAT3 activation was confined to actively inflamed areas. Accordingly, activated STAT3 was detected in isolated lamina propria mononuclear cells from inflamed IBD tissues, but not in peripheral blood mononuclear cells from control subjects or IBD patients. Immunofluorescence demonstrated that the sources of activated STAT3 were macrophages and T lymphocytes, but not neutrophils. STAT3 activation also was detected in T cells infiltrating the duodenal mucosa of celiac disease patients. We conclude that STAT3 signaling occurs in both CD and UC, where it is strictly confined to areas of active inflammation and is limited to infiltrating macrophages and T cells. The occurrence of STAT3 signaling in other acute and chronic intestinal inflammatory conditions suggests that, rather than a specific feature of IBD, it represents a fundamental signaling pathway that is shared by multiple forms of gut inflammation.

Proinflammatory cytokines alter/reduce esophageal circular muscle contraction in experimental cat esophagitis

Cholinergic mechanisms are largely responsible for esophageal contraction in response to swallowing or to in vitro electrical field stimulation (EFS). After induction of experimental esophagitis by repeated acid perfusion, the responses to swallowing and to EFS were significantly reduced but contraction in response to ACh was not affected, suggesting that cholinergic mechanisms are damaged by acid perfusion but that myogenic mechanisms are not. Measurements of ACh release in response to EFS confirmed that release of ACh was reduced in esophagitis compared with normal controls. To examine factors contributing to this neuropathy, normal esophageal strips were incubated for 1-2 h with the proinflammatory cytokines IL-1beta (100 U/ml), IL-6 (1 ng/ml), or TNF-alpha (1 ng/ml). IL-1beta and IL-6 levels, measured by Western blot analysis, increased in esophagitis compared with normal circular muscle. IL-1beta and IL-6 reduced contraction in response to EFS (2-10 Hz, 0.2 ms) but did not affect ACh-induced contraction, suggesting that these cytokines inhibit ACh release without affecting myogenic contractile mechanisms. EFS-induced ACh release was significantly reduced in normal esophageal strips by incubation in IL-1beta or IL-6, suggesting that they may contribute to the contractility changes. TNF-alpha at 1 ng/ml, however, did not affect the response to ACh or to electrical stimulation but inhibited both at higher concentrations. TNF-alpha levels were low in normal muscle and did not increase with esophagitis. The data suggest that the proinflammatory cytokines IL-1beta and IL-6 contribute to reduced esophageal contraction by inhibiting release of ACh from myenteric neurons.

The role of costimulatory molecules CD80 and CD86 and IFNgamma in the pathogenesis of ulcerative colitis

Several studies showed that costimulatory signals on antigen presenting cells are up-regulated in inflammatory bowel disease. We quantified the expression of CD80, CD86, and IFNgamma in colonic mucosa of patients affected by ulcerative colitis and correlated it with clinical and biochemical parameters to identify the context of this up regulation. We enrolled 21 patients affected by ulcerative colitis and 6 healthy subjects. We evaluated for each patient gender, age, duration of disease, clinical, endoscopic and histologic disease activity index, medical therapy, ESR, serum CRP, WBC, and serum al-acid glycoprotein. CD80, CD86, and IFNgamma expression in the colonic mucosa was quantified using reverse transcription polymerase chain reaction. Statistical analysis was performed using Mann-Whitney U test and Spearman's rank correlation test. Significance was set at P < 0.05. CD80 was detectable in seven patients, while CD86 and IFNgamma expression was evident in all UC patients. CD80 and CD86 were not detectable in control specimens. Colonic CD80 expression was correlated to the age of the patients. CD86 expression showed an inverse correlation with duration of disease and a direct correlation with serum CRP levels and histologic grade of disease activity. IFNgamma was not correlated with any of the examined parameter. Our study confirms a major role in ulcerative colitis pathogenesis for CD86 which correlates with histologic grade of disease and with serum CRP levels, and its upregulation seems to be higher at the beginning of the disease. In "in vivo" conditions IFNgamma may not be the only factor responsible for CD86 up-regulation in the ulcerative colitis colonic mucosa.

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Review article: Osteoporosis and inflammatory bowel disease

Studies using dual-energy X-ray absorptiometry have suggested a high prevalence of osteoporosis in inflammatory bowel disease. However, population-based data on fracture incidence suggest only a small increased risk of fracture amongst patients with inflammatory bowel disease compared with the general population. Therefore, it would be helpful to identify patients with inflammatory bowel disease at particularly high risk for fracture so that these risks might be modified or interventions might be undertaken. The data on calcium intake as a predictor of bone mineral density are conflicting. Although there are data suggesting that a one-time survey to determine current calcium intake will not help to predict bone mineral density in inflammatory bowel disease, persistently reduced calcium intake does appear to lead to lower bone mineral density. In the general population, body mass is strongly correlated with bone mineral density, which also appears to be true in Crohn's disease. Hence, subjects with inflammatory bowel disease and considerable weight loss, or who are obviously malnourished, could be considered for bone mineral density testing, and the finding of a low bone mineral density would suggest the need for more aggressive nutritional support. Although vitamin D is undoubtedly important in bone health, vitamin D intake and serum vitamin D levels do not correlate well with bone mineral density. Sex hormone deficiency can also adversely affect bone health, although a well-developed strategy for sex hormone measurements in patients with inflammatory bowel disease remains to be established. Ultimately, the determination of genetic mutations that accurately predict fracture susceptibility may be the best hope for developing a simplified strategy for managing bone health in inflammatory bowel disease. The therapy of osteoporosis in inflammatory bowel disease has been adapted from other osteoporosis settings, such as post-menopausal or corticosteroid-induced osteoporosis. To date, there remains no therapy proven to be efficacious in inflammatory bowel disease-related osteoporosis; however, calcium and vitamin D supplementation and bisphosphonates have their roles.

Hydrogen peroxide contributes to motor dysfunction in ulcerative colitis

Ulcerative colitis (UC) affects colonic motor function, but the mechanism responsible for this motor dysfunction is not well understood. We have shown that neurokinin A (NKA) may be an endogenous neurotransmitter mediating contraction of human sigmoid colonic circular muscle (HSCCM). To elucidate factors responsible for UC motor dysfunction, we examined the role of hydrogen peroxide (H(2)O(2)) in the decrease of NKA-induced response of HSCCM. As previously demonstrated, NKA-induced contraction or Ca(2+) increase of normal muscle cells is mediated by release of Ca(2+) from intracellular stores, because it was not affected by incubation in Ca(2+)-free medium (CFM) containing 200 microM BAPTA. In UC, however, CFM reduced both cell contraction and NKA-induced Ca(2+) increase, suggesting reduced Ca(2+) release from intracellular stores. In normal Ca(2+) medium, NKA and KCl caused normal Ca(2+) signal in UC cells but reduced cell shortening. The decreased Ca(2+) signal and contraction in response to NKA or thapsigargin were partly recovered in the presence of H(2)O(2) scavenger catalase, suggesting involvement of H(2)O(2) in UC-induced dysmotility. H(2)O(2) levels were higher in UC than in normal HSCCM, and enzymatically isolated UC muscle cells contained much higher levels of H(2)O(2) than normal cells, which were significantly reduced by catalase. H(2)O(2) treatment of normal cells in CFM reproduced the reduction of NKA-induced Ca(2+) release observed in UC cells. In addition, H(2)O(2) caused a measurable, direct release of Ca(2+) from intracellular stores. We conclude that H(2)O(2) may contribute to reduction of NKA-induced Ca(2+) release from intracellular Ca(2+) stores in UC and contribute to the observed colonic motor dysfunction.

IL-6 induces NF-kappa B activation in the intestinal epithelia

IL-6 is a potent proinflammatory cytokine that has been shown to play an important role in the pathogenesis of inflammatory bowel disease (IBD). It is classically known to activate gene expression via the STAT-3 pathway. Given the crucial role of IL-6 in the pathogenesis of chronic intestinal inflammation, it is not known whether IL-6 activates NF-kappaB, a central mediator of intestinal inflammation. The model intestinal epithelial cell line, Caco2-BBE, was used to study IL-6 signaling and to analyze whether suppressor of cytokine signaling 3 (SOCS-3) proteins play a role in the negative regulation of IL-6 signaling. We show that IL-6 receptors are present in intestinal epithelia in a polarized fashion. Basolateral IL-6 and, to a lesser extent, apical IL-6 induces the activation of the NF-kappaB pathway. Basolateral IL-6 stimulation results in a maximal induction of NF-kappaB activation and NF-kappaB nuclear translocation at 2 h. IL-6 induces polarized expression of ICAM-1, an adhesion molecule shown to be important in the neutrophil-epithelial interactions in IBD. Using various deletion constructs of ICAM-1 promoter, we show that ICAM-1 induction by IL-6 requires the activation of NF-kappaB. We also demonstrate that overexpression of SOCS-3, a protein known to inhibit STAT activation in response to IL-6, down-regulates IL-6-induced NF-kappaB activation and ICAM-1 expression. In summary, we demonstrate the activation of NF-kappaB by IL-6 in intestinal epithelia and the down-regulation of NF-kappaB induction by SOCS-3. These data may have mechanistic and therapeutic implications in diseases such as IBD and rheumatoid arthritis in which IL-6 plays an important role in the pathogenesis.

DNA variants in cytokine and NOD2 genes, exposures to infections and risk for Crohn's disease

The incidence and prevalence of Crohn's disease (CD) among children in developed countries is increasing. Although extensive progress has been made in the elucidation of the pathogenesis of the disease, its mechanism remains unknown. CD is likely to be the result of a complex interplay of both genetic and environmental factors (G x E). However, the specific elements underlying these interactions have not been defined. We propose that the underlying pathology of CD may be related to interactions between infections acquired either during intrauterine life and/or early childhood and DNA variants in the cytokine and the NOD2 genes. DNA variants in the latter could confer susceptibility by altering immune development and response to infectious agents. We present a molecular and epidemiological perspective on possible mechanisms underlying G x E. Investigating these and other pathways will be paramount for the appropriate identification of susceptible populations, so that preventive and/or therapeutic interventions could be adequately targeted.

Connections between psoriasis and Crohn's disease

The prevalence of psoriasis in patients with Crohn's disease (CD) is higher than chance would allow if they were mutually exclusive diseases. A close examination reveals genetic and pathologic connections between these diseases. An appreciation for the role of tumor necrosis factor-alpha in both diseases has proven very important. Increased levels of this inflammatory cytokine have been measured in CD lesions, and in 1997 a clinical trial demonstrated the response of this disease to infliximab, a monoclonal antibody specific for tumor necrosis factor-alpha. A subsequent clinical trial evaluated infliximab in a patient with CD and psoriasis, another disease in which increased levels of tumor necrosis factor-alpha are seen in lesions. Scientists noticed the marked skin improvement of this patient and later demonstrated the efficacy of infliximab for psoriasis in a randomized, double-blind, placebo-controlled trial. Thus, an appreciation for connections between psoriasis and CD can suggest novel therapeutic strategies with ensuing benefits to patients. This article reviews epidemiologic, genetic, and pathologic connections between psoriasis and CD and discusses pharmaceuticals targeting inflammatory mediators common to each disease. (J Am Acad Dermatol 2003;48:805-21.)

LEARNING OBJECTIVE

At the completion of this learning activity, participants should understand how psoriasis and Crohn's disease are related at epidemiologic, genetic, and pathological levels and should appreciate how to use this knowledge to treat these diseases.

Interferon-gamma induces C/EBP beta expression and activity through MEK/ERK and p38 in T84 colon epithelial cells

We investigated the role of IFN-gamma and MAPKs on the expression and activity of the transcription factor CCAAT/enhancer-binding protein-beta (C/EBP beta) in the T84 colon epithelial cell line. IFN-gamma induced the expression and activity of C/EBP beta and subsequently increased the secretion of IL-6 from these cells. Treatment with the p38 inhibitor SB-203580, the MEK1 and MEK2 inhibitor U-0126, or the translational inhibitor cycloheximide inhibited the induction of C/EBP beta and IL-6 by IFN-gamma, whereas the MEK1 inhibitor PD-98059 or the tyrosine kinase inhibitor genistein had no effect. These results suggest a role for MEK2 and p38 in IFN-gamma-mediated signal transduction and induction of C/EBP beta expression and activity associated with interleukin-6 (IL-6) secretion in colon epithelial cells.

Increased expression of HIP/PAP and regenerating gene III in human inflammatory bowel disease and a murine bacterial reconstitution model

Although microorganisms play a role in gut inflammation, it remains uncertain which epithelial genes are expressed in response to luminal flora and whether these molecules are also involved in pathologic mucosal inflammation. Germ-free mice were orally challenged with a bacterial suspension prepared from conventionally housed mice (bacterial reconstitution). Thereafter, the differential gene expression in gut epithelial cells was identified by differential display. The expression of the identified genes was also examined in dextran sulfate sodium (DSS)-induced colitis and human inflammatory bowel disease (IBD) epithelial cells. Regenerating gene III (Reg III) was strongly induced in gut epithelial cells following bacterial reconstitution, as well as in the colitis initiated by DSS. The mRNA expression of hepatocarcinoma-intestine-pancreas/pancreatic associated protein (HIP/PAP), a human counterpart of Reg III, was enhanced in colonic epithelial cells of patients with IBD. Reg III mRNA expression was localized in the epithelial cells including goblet cells and columnar cells in mice; on the other hand, HIP/PAP-expressing cells were correlated with Paneth cell metaplasia in human colon. Epithelial expression of Reg III or HIP/PAP was induced under mucosal inflammation initiated by exposure to commensal bacteria or DSS as well as inflamed IBD colon.

Human intestinal epithelial and smooth muscle cells are potent producers of IL-6

BACKGROUND

Interleukin-6 (IL-6), a pluripotent cytokine, has traditionally been considered the product of proinflammatory cells. However, many other cell types have been shown to produce IL-6. Since intestinal inflammation is commonly associated with a vigorous systemic inflammatory response, we hypothesized that intestinal epithelial and smooth muscle cells might contribute to that response by producing IL-6. We therefore studied the capacity of differentiated human intestinal epithelial and smooth muscle cell lines to produce IL-6 in response to various proinflammatory stimuli.

MATERIALS AND METHODS

CCL-241, a human intestinal epithelial cell line, and HISM, a human intestinal muscle cell line, were grown to confluency and then treated for 24 h with various concentrations of lipopolysaccharide, Clostridium difficile culture extract containing both toxin A and toxin B, recombinant human tumor necrosis factor-alpha (TNF-alpha), or recombinant human interleukin-1 beta (IL-1beta). Supernatants were then collected for IL-6 determination using an enzyme-linked immunosorbent assay. Cell numbers were determined using a Coulter counter. For comparison, parallel studies were performed using phorbol ester-primed U-937 and THP-1 human macrophage cell lines.

RESULTS

Both human intestinal epithelial and smooth muscle cells produced IL-6 under basal conditions. In HISM cells, but not in CCL-241 cells, IL-6 release was increased slightly by treatment with C. difficile culture extract containing both toxin A and toxin B and with lipopolysaccharide. In both cell lines, IL-6 production was profoundly stimulated by treatment with IL-1beta and less so with TNF-alpha. Combinations of high-dose TNF-alpha and IL-1beta may have a slightly additive, but not synergistic, effect on IL-6 release. The amount of IL-6 produced by IL-1-stimulated intestinal cell lines was 70-fold higher than that produced by stimulated macrophage cell lines. CONCLUSIONS; Both intestinal epithelial and smooth muscle cells demonstrate the ability to release significant amounts of IL-6. The profound response to IL-1beta and TNF-alpha stimulation by both cell lines suggests that human intestinal parenchymal cells, influenced by paracrine mediators liberated from proinflammatory cells, might significantly contribute to the overall systemic inflammatory response by producing IL-6.

Possible involvement of neutrophil elastase in impaired mucosal repair in patients with ulcerative colitis

BACKGROUND

Little information is available on the relative contribution of peptide growth factors and leukocyte-derived proteinases to the repair processes in inflammatory bowel disease (IBD). We investigated their possible roles in epithelial cell restitution and proliferation in patients with IBD.

METHODS

The expression of hepatocyte growth factor (HGF), keratinocyte growth factor (KGF), transforming growth factor-beta (TGF-beta), and neutrophil elastase (NE) was examined in colonic mucosal tissues. The effects of organ culture supernatants of mucosal tissues on epithelial cell restitution and proliferation were analyzed in vitro using an intestinal cell line, IEC-6 cells.

RESULTS

Most organ cultures detected the presence of measurable levels of HGF, with a relative paucity of KGF and TGF-beta activity. Greater levels of HGF were obtained in the mucosa involved with IBD, especially in patients with ulcerative colitis (UC). The mucosa involved with UC also showed higher amounts of NE. The supernatants from the mucosa involved with UC possessed a prominent stimulatory effect on the restitution of IEC-6 cells. By contrast, significant suppression beyond baseline levels was observed for the proliferation of IEC-6 cells when they were incubated with recombinant HGF plus the supernatants from the mucosa involved with UC. This suppression was diminished considerably by preincubation of the supernatants with the anti-NE antibody.

CONCLUSIONS

HGF produced in the intestinal mucosa may be an important stimulator acting on epithelial cell restitution in patients with IBD. However, NE released in situ may impair mucosal repair through inhibiting epithelial cell proliferation in patients with UC.

Cytokine profile in colonic mucosa of ulcerative colitis correlates with disease activity and response to granulocytapheresis

OBJECTIVE

The aim of this study was to clarify the correlation between cytokine profile in colonic mucosa with disease activity and response to granulocytapheresis (GCAP) in patients with ulcerative colitis (UC), using a reliable, reproducible quantitative method.

METHODS

Colonoscopic biopsies of inflamed colonic mucosa (16 patients, 21 cases) and uninflamed colonic mucosa (25 patients, 33 cases) were obtained from UC patients. Messenger (m)RNA was extracted and subjected to realtime polymerase chain reaction for quantitative measurement of interleukin (IL)-12, interferon-gamma, tumor necrosis factor-alpha, IL-4, IL-8, and IL-18 mRNAs. In seven patients with high disease activity despite prednisolone (PSL) treatment (> or = 20 mg/day), one course of GCAP was conducted, and pre- and post-GCAP cytokine profiles were determined.

RESULTS

In inflamed colonic mucosa of UC patients, three cytokine profiles were observed: 1) high expression of interferon-gamma, tumor necrosis factor-alpha, and IL-4 mRNAs but low expression of IL-8 mRNA; 2) high expression of IL-8 mRNA and low expression of others; and 3) low expression of all cytokines examined. Inflamed colonic mucosa of patients with high disease activity showed the second pattern. Inflamed colonic mucosa of patients who were not treated with PSL and who had low disease activity showed the first pattern, whereas those on high-dose PSL exhibited the second pattern. IL-8 mRNA was significantly higher in inflamed UC samples than in uninflamed samples. GCAP was effective in five of seven PSL-resistant patients (71.4%). IL-8 was the only cytokine that correlated with effectiveness of GCAP. Compared with GCAP nonresponders, responders had significantly higher IL-8 mRNA before GCAP and showed marked reduction of IL-8 mRNA after GCAP.

CONCLUSIONS

IL-8 mRNA was significantly increased in inflamed mucosa of UC. Patients with high IL-8 mRNA expression in colonic mucosa despite PSL treatment were responsive to GCAP. Therefore, quantitative measurement of mucosal IL-8 mRNA may be useful in predicting the response to GCAP.

Lamina propria and circulating interleukin-6 in newly diagnosed pediatric inflammatory bowel disease patients

OBJECTIVES

Understanding cytokine production patterns in early mucosal lesions of pediatric patients newly diagnosed with inflammatory bowel disease (IBD) may be critical to understanding IBD pathogenesis. Interleukin-6 (IL-6) has a central role in a multitude of immune system reactions; however, inconsistent lamina propria and serum IL-6 has been reported in IBD patients. Newly diagnosed pediatric IBD patients have not previously been evaluated for lamina propria or serum IL-6.

METHODS

Serum and intestinal lamina propria biopsy whole organ culture supernatants were evaluated by ELISA for IL-6 obtained from newly diagnosed IBD patients, before initiation of immunomodulatory therapies.

RESULTS

Levels of lamina propria IL-6 demonstrated significant correlation with graded severity of histological inflammation (p < 0.001). Log-transformed serum and organ culture IL-6 levels demonstrated significant correlation (p < 0.0001, R2 = 0.6226). Assigning a demarcation level of >400 pg/ml, serum IL-6 concentrations were a superior marker for the presence of microscopic intestinal inflammation than erythrocyte sedimentation rate (ESR), with a sensitivity of 82%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 82%. When evaluating subtypes of IBD, serum IL-6 levels were correlated more significantly with active disease in ulcerative colitis patients (p = 0.01, R2 = 0.74) than in Crohn's disease patients (p = 0.21, R2 = 0.33).

CONCLUSIONS

This study outlines graded production of IL-6 in intestinal lamina propria and serum of newly diagnosed pediatric IBD patients, confirming the presence of IL-6 in early IBD patients. In addition, serum IL-6 may be a good predictor of IBD in pediatric patients with suspected or newly diagnosed IBD.

Suppressive effects of cyclosporine A on neutrophils and T cells may be related to therapeutic benefits in patients with steroid-resistant ulcerative colitis

An intravenous infusion of cyclosporine A (CsA) shows clinical benefits in patients with steroid-resistant ulcerative colitis (UC). To clarify its mechanisms, we investigated the ability of CsA to inhibit the functions of neutrophils and T cells. The cytotoxic activity by mucosal T cells was analyzed by anti-CD3-triggered cytotoxicity after lamina propria mononuclear cells were cultured with recombinant interleukin (IL)-2. The chemotactic response, the generation of superoxide, and the production of chemokines, IL-8, and macrophage inflammatory protein-1alpha by neutrophils were examined using a multiple-well chamber assay, a chemiluminescence method, and an enzyme-linked immunosorbent assay (ELISA), respectively. Mucosal chemokine activity was determined by an ELISA using the organ culture supernatant of mucosal biopsy tissues. Pretreatment with CsA caused consistent inhibitions of cytotoxic activity by mucosal T cells and chemotactic migration, superoxide generation, and chemokine production by neutrophils mostly in a dose-dependent manner. In patients who received an intravenous infusion of CsA, mucosal chemokine activity decreased after therapy in parallel with decreases in the numbers of neutrophils and mononuclear cells in the biopsy tissues. These results suggest that suppressive effects of CsA on neutrophils and T cells may be related to therapeutic benefits in patients with steroid-resistant UC.

Expression of interleukin-6, leukemia inhibitory factor and their receptors by colonic epithelium and pericryptal fibroblasts

BACKGROUND AND AIM

The cellular configuration of the human colon suggests a predetermined organization that creates specific microenvironments. The role of pericryptal fibroblasts in this microenvironment has been the subject of considerable speculation. This study examined the expression of growth factors and their receptors by colonic crypt epithelium and pericryptal fibroblasts.

METHODS AND RESULTS

Pericryptal fibroblast cells were isolated and cultured from decrypted human colonic mucosa. The pericryptal fibroblast cells expressed messenger RNA (mRNA) for interleukin-6 (IL-6), leukemia inhibitory factor (LIF), LIF receptor alpha, and the common coreceptor glycoprotein 130 (GP130), but not the IL-6 receptor alpha. Interleukin-6 protein expression was confirmed by the analysis of conditioned medium and immunohistochemistry. In comparison, normal colonic epithelial cells express mRNA for LIF but not IL-6 as well as the receptors for GP-130, IL-6 receptor alpha but not LIF receptor alpha. As cultures of normal human colonic epithelial cells were not available, the conditioned medium was assayed from established colon carcinoma cell lines and demonstrated a secretion of LIF but not IL-6 protein.

CONCLUSION

The expression of reciprocal cytokine and receptor expression suggest that there is a paracrine relationship between pericryptal fibroblasts and colonic epithelium.

Interleukin-6 expression and regulation in rat enteric glial cells

As yet, little is known about the function of the glia of the enteric nervous system (ENS), particularly in an immune-stimulated environment. This prompted us to study the potential of cultured enteroglial cells for cytokine synthesis and secretion. Jejunal myenteric plexus preparations from adult rats were enzymatically dissociated, and enteroglial cells were purified by complement-mediated cytolysis and grown in tissue culture. Cultured cells were stimulated with recombinant rat interleukin (IL)-1beta, IL-6, and tumor necrosis factor (TNF)-alpha, and IL-6 mRNA expression and secretion were assessed using RT-PCR and a bioassay, respectively. Stimulation with TNF-alpha did not affect IL-6 mRNA expression, whereas IL-1beta stimulated IL-6 mRNA and protein synthesis in a time- and concentration-dependent fashion. In contrast, IL-6 significantly and dose-dependently suppressed IL-6 mRNA expression. In summary, we have presented evidence that enteric glial cells are a potential source of IL-6 in the myenteric plexus and that cytokine production by enteric glial cells can be regulated by cytokines. These findings strongly support the contention that enteric glial cells act as immunomodulatory cells in the enteric nervous system.

Colonic production and expression of IL-4, IL-6, and IL-10 in neonatal suckling rats after LPS challenge

It has been demonstrated that the neonatal suckling rat is more susceptible to endotoxin [lipopolysaccharide (LPS)]-induced colonic damage compared with weaned littermates. There is evidence to suggest that differences in the production of certain cytokines, including interleukin (IL)-4, IL-6, and IL-10, are associated with intestinal inflammation in children. We have examined the production, localization, and mRNA detection of these cytokines in suckling and weaned rat colons after bacterial LPS challenge. Suckling (10 day old) and weaned (25 day old) rats were injected with LPS (3 mg/kg ip). Colon samples were taken up to 4 h after treatment, and cytokines were measured by ELISA. LPS-induced cytokine levels were significantly different in suckling rats compared with weaned rats. Cytokine localization to the colonic mucosa was evident in suckling rats up to 4 h after LPS administration but was not consistently seen in weaned rats. The mRNA for cytokines examined were detected by RT-PCR in suckling but not in weaned rat colons after LPS treatment. Induction of neutropenia via anti-neutrophil serum (ANS) administration did not affect cytokine mRNA detection in neonates after LPS treatment. Weaned animals displayed positive detection of all cytokines examined after ANS. Therefore, we have shown that the suckling rat displays a different production and expression of colonic IL-4, IL-6, and IL-10 compared with weaned littermates after LPS challenge. Furthermore, neutrophils may be implicated in colonic cytokine expression after LPS challenge in rats.

Neutrophil-epithelial crosstalk at the intestinal lumenal surface mediated by reciprocal secretion of adenosine and IL-6

Adenosine is formed in the intestinal lumen during active inflammation from neutrophil-derived 5' AMP. Using intestinal epithelial cell line T84, we studied the effect of adenosine on the secretion of IL-6, a proinflammatory cytokine involved in neutrophil degranulation and lymphocyte differentiation. Stimulation of T84 monolayers with either apical or basolateral adenosine induces A2b receptor-mediated increase in IL-6 secretion, which is polarized to the apical (luminal) compartment. In addition, Salmonella typhimurium, TNF-alpha, and forskolin, known inducers of IL-6 secretion in intestinal epithelial cells, also stimulate IL-6 secretion into the apical compartment. We show that IL6 promoter induction by adenosine occurs through cAMP-mediated activation of nuclear cAMP-responsive element-binding protein (CREB). We also show that IL-6 released in the luminal (apical) compartment achieves a sufficient concentration to activate neutrophils (from which the adenosine signal originates), since such IL-6 is found to induce an intracellular [Ca(++)] flux in neutrophils. We conclude that adenosine released in the intestinal lumen during active inflammation may induce IL-6 secretion, which is mediated by cAMP/CREB activation and occurs in an apically polarized fashion. This would allow sequential activation of neutrophil degranulation in the lumen -- a flow of events that would, in an epithelium-dependent fashion, enhance microbicidal activity of neutrophils as they arrive in the intestinal lumen.

Influence of glutamine on cytokine production by human gut in vitro

BACKGROUND

glutamine modulates cytokine production by immune cells in vitro and protects the gut from experimental enterocolitis, but data on the effect of glutamine on cytokine production in human gut are lacking.

AIM

to assess the effect of glutamine pre-treatment in vivo and in vitro on cytokine production by intestinal mucosa.

METHODS

nine fasted volunteers received either enteral glutamine or saline over 6 h in a cross-over design. Duodenal biopsies were cultured for 24 h with or without glutamine. Cytokine content of culture media was analysed by ELISA, and the expression of cytokine mRNA in biopsies was assessed by semi-quantitative RT-PCR.

RESULTS

glutamine given in vivo and in vitro significantly decreased IL-6 [1.4 (0.8-8.5) vs 8.9 (1.0-43.9)] and IL-8 production [5.8 (0-51.4) vs. 53.0 (2.5-114.6), pg/mg wet tissue], median (range), both P< or =0.01, in comparison to no glutamine experiments. Glutamine did not influence IL-4 production. IL-1beta, IL-10 and TNF-alpha were not detectable in culture media. The expression of any cytokine mRNA was not influenced by glutamine.

CONCLUSIONS

glutamine reduces pro-inflammatory cytokine production by human intestinal mucosa, probably by a post-transcriptional pathway. Glutamine could be useful to modulate inflammatory conditions with imbalanced cytokine production.

Beneficial intervention of experimental colitis by passive cigarette smoking through the modulation of cytokines in rats

BACKGROUND

Epidemiologic observations have indicated that cigarette smoking decreases the risk of ulcerative colitis, but the modes of action remain anonymous. The present study aimed to investigate the beneficial effects of passive cigarette smoking using an animal colitis model. We hypothesized that the underlying mechanisms may involve immunoregulation of cytokines.

METHODS

Experimental colitis was induced in rats by enema administration of 2,4-dinitrobenzene sulfonic acid (DNBS). Passive cigarette smoking by rats was performed for 1 hour once daily, from 3 days before DNBS enema until they were sacrificed on day 8. Other groups of DNBS-treated rats received therapeutic treatment of cyclosporin A or pentoxifylline, a tumor necrosis factor (TNF)-alpha inhibitor. Macroscopic and histologic damage were graded, and the colonic levels of different cytokines and the levels/activities of parameters related to neutrophil activation were also measured.

RESULTS

DNBS-induced colonic damage was improved in passive-cigarette-smoking rats. This was accompanied by attenuation of the elevated colonic myeloperoxidase and inducible nitric oxide synthase activities and leukotriene B4 level. Likewise, the augmentation in colonic levels of TNF-alpha, interleukin (IL)-1 beta, and IL-6 in colitis rats was also alleviated by passive cigarette smoking. In contrast, the deprivation of colonic IL-10 during colitis was preserved in cigarette-smoking rats. These effects were similarly accomplished by pentoxifylline and, to some degree, by cyclosporin A.

CONCLUSIONS

The results support the idea that the beneficial effects of passive cigarette smoking in experimental colitis involved immunoregulation of cytokines in colonic tissues.

Necrotizing enterocolitis and hematopoietic cytokines

The names of the hematopoietic cytokines are misleading because in addition to their effects on bone marrow and bone marrow-derived cells, they have many diverse effects, including effects on the gastrointestinal tract. These effects may be directly mediated by interaction with specific receptors on gastrointestinal epithelial cells, or they may result from their effects on circulating or bowel wall leukocytes and the cytokines these cells produce. As might be expected of factors largely defined by their effects on inflammatory cells, the hematopoietic cytokines are intimately involved in the processes of bowel injury. Further investigations are needed to define the role of hematopoietic cytokines in the human neonate's balance between local gastrointestinal host defense and bowel wall injury. This could lead to effective strategies for the treatment and prevention of NEC.

Anti-CagA immunoglobulin G responses correlate with interleukin-8 induction in human gastric mucosal biopsy culture

Helicobacter pylori persists in the human stomach despite eliciting both cellular and humoral immune responses and inducing proinflammatory cytokines. To determine whether local humoral and cytokine responses are related to each other and to histologic responses, we studied 66 Japanese patients who underwent gastroscopy. Using specific enzyme-linked immunosorbent assays, we examined gastric antral mucosal-organ biopsy culture supernatants to assess interleukin-6 (IL-6) and interleukin-8 (IL-8) levels and antibody responses to H. pylori whole-cell antigens CagA, HspA, and HspB. Of the patients studied, 11 were H. pylori negative and 55 were H. pylori positive; by PCR, all strains were cagA(+). As expected, compared to H. pylori-negative patients, H. pylori-positive patients had significantly higher humoral responses to all H. pylori antigens and had higher IL-8 (47.8+/-3.5 versus 10.1+/-4.3 ng/mg of biopsy protein; P<0.001) and IL-6 levels (2.8+/-0.3 versus 0.26+/-0.2 ng/mg of protein; P<0.001). Among the H. pylori-positive patients, supernatant anti-CagA immunoglobulin G (IgG) levels were significantly associated with H. pylori density (P<0.005) and neutrophil infiltration (P<0.005) scores. Anti-CagA immunoglobulin A levels were correlated with intestinal metaplasia (P<0.05). Mononuclear cell infiltration scores were significantly associated with supernatant IL-6 levels (P<0.005) and with IgG responses to whole-cell antigens (P<0.05). Supernatant IL-8 levels were significantly associated with anti-CagA IgG (r = 0.75, P<0.001). Anti-CagA responses correlated with neutrophil infiltration, intestinal metaplasia, H. pylori density, and IL-8 levels, suggesting that the absolute levels of these antibodies may be markers for gastric inflammation and premalignant changes in individual hosts.

Comparison between in vivo and in vitro chemokine production in Helicobacter pylori infection

BACKGROUND

Enhanced gastric mucosal chemokine activity has been demonstrated in patients with Helicobacter pylori infection. However, little is known about the mechanisms involved in this phenomenon.

AIM

To examine whether in vivo chemokine activity is similar to in vitro response of gastric epithelial cells infected by H. pylori.

PATIENTS AND METHODS

Antral biopsy specimens were obtained from patients with H. pylori infection for organ culture, isolation of H. pylori and histological examination.

RESULTS

In organ cultures of mucosal tissues, the levels of interleukin-8 and growth-related gene product a were elevated in patients with peptic ulcer disease compared with those with erosive gastritis or endoscopically normal mucosa. However, there were no significant differences in in vitro cultures of MKN45 or KATO III cells that were infected with H. pylori isolated from these same patients. These in vivo and in vitro alpha-chemokine levels showed no significant association with the presence of cagA gene and CagA protein, ureB genotype, or binding capacity to MKN45 or KATO III cells in individual H. pylori isolates. In contrast, in vivo mucosal alpha-chemokine activity correlated with H. pylori colonization density.

CONCLUSION

Mucosal chemokine profiles and inflammatory responses in H. pylori infection may be associated more closely with host factors, including those determining bacterial adhesiveness, than with differences in H. pylori strains.

Established and emerging biological activity markers of inflammatory bowel disease

Assessment of disease activity in inflammatory bowel disease (IBD), i.e., ulcerative colitis (UC) and Crohn's disease (CD), is done using clinical parameters and various biological disease markers. Ideally, a disease marker must: be able to identify individuals at risk of a given disorder, be disease specific, mirror the disease activity and, finally, be easily applicable for routine clinical purposes. However, no such disease markers have yet been identified for IBD. In this article, classical disease markers including erythrocyte sedimentation rate, acute phase proteins (especially orosomucoid and CRP), leukocyte and platelet counts, albumin, neopterin, and beta2-microglobulin will be reviewed together with emerging disease markers such as antibodies of the ANCA/ASCA type, cytokines (e.g., IL-1, IL-2Ralpha, IL-6, IL-8, TNF-alpha, and TNF-alpha receptors) and with various adhesion molecules. It is concluded that none of the pertinent laboratory surrogate markers of disease activity in IBD are specific or sensitive enough to replace basic clinical observation such as the number of daily bowel movements, general well-being, and other parameters in parallel. Further studies are highly warranted to identify and assess the clinical importance and applicability of new laboratory markers for the diagnosis or the disease activity of IBD.

Study of the mechanisms of acupuncture and moxibustion treatment for ulcerative colitis rats in view of the gene expression of cytokines

AIM: To observe the effect of acupuncture and moxibustion on the expression of IL-1β and IL-6 mRNA in ulcerative colitis rats.

METHODS: The SD rat ulcerative colitis model was created by immunological method associated with local stimulation. Colonic mucosa was prepared from human fresh surgical colonic specimens, homogenized by adding appropriate amount of normal saline and centrifuged at 3000 r/min. The supernatant was collected for measurement of protein conentration and then mixed with Freund adjuvant. This antigen fluid was first injected into the plantae of the model group rats, and then into their plantae, dorsa, inguina and abdominal cavities (no Freund adjuvant for the last injection) again on the 10th, 17th, 24th and 31st day. When a certain titer of serum anti-colonic anti body was reached, 2% formalin and antigen fluid ( no Freund adjuvant ) were administered separately by enema. The ulcerative colitis rat model was thus set up. The animals were randomly divided into four groups: model control group ( MC, n = 8 ), electro-acupuncture group (EA, n = 8), herbs-partition moxibustion group (HPM 8), normal control group ( NC, n = 8 ). HPM: Moxa cones made of refined mugwort floss were placed on the medicinal pad (medicinal pad dispensing: Radix Aconiti praeparata, cortex Cinnamomi, etc) for Qihai (RN 6) and Tianshu (S T 25, bilateral) and ignited. Two moxa cones were used for each acupoint once a day and 14 times in all. EA: Tianshu (bilateral) and Qihai were stimulated by the intermittent pulse with 2 Hz frequency, 4mA intensity for 20 min once a day and 14 times in all. After treatment, rats of all four groups were killed simultaneously. The spleen was separated and the distal colon was dissected. Total tissue RNA was isolated by the guanidinium thiocyanate phenol-chloroform extraction method. RT-PCR technique was used to study the expression of IL-1β and IL-6 mRNA.

RESULTS: IL-1β and IL-6 mRNAs were not detected in the spleen and colonic mucosa of the NC rats, whereas they were significantly expressed in that of the MC rats. IL-1β and IL-6 mRNAs we re markedly lower in the EA and HPM rats than that in MC rats. There was no significant difference between the levels of IL-1β and IL-6 mRNAs in the EA and HPM rats. The expressions of IL-1β and IL-6 mRNAs were nearly the same in the spleen and colon of all groups.

CONCLUSION: Acupuncture and moxibustion greatly inhibited the expression of IL-1β and IL-6 mRNA in the experimental ulcerative colitis rats.

Interleukin-6 and soluble interleukin-6 receptor in the colonic mucosa of inflammatory bowel disease

BACKGROUND

Interleukin-6 (IL-6) has multiple immunological effects on a wide variety of cells and tissues. The expression of IL-6 and IL-6 receptor (IL-6R) may be important to the pathogenesis of inflammatory bowel disease (IBD).

METHODS

In the present study, we examined whether mucosal IL-6 and soluble IL-6R were associated with the pathophysiology of IBD using the colonic mucosal specimens obtained from patients with IBD. Enzyme-linked immunosorbent assay was used to measure the levels of IL-6 and sIL-6R in organ cultures of mucosal tissues and in cell cultures of fractionated mucosal cells as well as in the serum. Expression of IL-6 and IL-6R was analysed by reverse transcription-polymerase chain reaction analysis using freshly isolated lamina propria mononuclear cells (LPMC).

RESULTS

The levels of IL-6 and sIL-6R in organ cultures were substantially elevated in patients with IBD, especially in those with histologically active inflammation. In contrast, considerably higher levels of sIL-6R were detected in patients with other types of colonic inflammation who were included as inflammatory controls, but elevation of IL-6 was less prominent in such patients. The positivity for expression of IL-6 and IL-6R mRNA in LPMC was in parallel with the results obtained in organ cultures. In cell cultures, mucosal macrophages were the main cell type producing both IL-6 and sIL-6R on a per cell basis and other cell fractions including colonic epithelial cells and lymphocytes produced substantially lower amounts of these molecules. The levels of IL-6 and sIL-6R in organ cultures, but not those in the serum, showed a significantly positive correlation with the degree of clinical disease activity in patients with IBD.

CONCLUSIONS

Enhanced IL-6/sIL-6R-mediated immune and inflammatory responses may be implicated, at least partly, in the continuation of intestinal inflammation in patients with IBD.

Cytokines and inflammatory bowel disease: a review

The etiology and pathogenesis of inflammatory bowel disease (IBD) remains an area under intense investigation. Cytokine secretion, which is important in the regulation of normal gastrointestinal immune responses, appears to be dysregulated in IBD. In Crohn's disease, there appears to be an excessive T(H)1 T-cell response to an antigenic stimulus, leading to increased levels of proinflammatory cytokines, such as interferon-gamma (IFN-gamma), interleukin (IL)-12, IL-1, IL-6, and tumor necrosis factor-alpha (TNF-alpha). In ulcerative colitis, a T(H)2 T-cell response appears to be the pathological process responsible for the inflammatory disease. New and innovative therapeutic strategies targeting cytokines, such as TNF-alpha, are producing some promising results in animal and human studies. As more is learned about the complex cytokine interactions in IBD, more effective treatments will undoubtedly ensue.

Clinical relevance of serum interleukin-6 in Crohn's disease: single point measurements, therapy monitoring, and prediction of clinical relapse

OBJECTIVE

To investigate the clinical relevance of interleukin-6 (IL-6) serum levels in patients with Crohn's disease (CD), single point IL-6 measurements in sera from consecutive CD patients and healthy donors (HD), as well as longitudinal measurements during the course of steroid therapy for active CD were performed. Patients with steroid-induced remission were followed until clinical relapse.

METHODS

One hundred thirty-six CD patients without steroid or other immunosuppressive treatment within 2 months and surgical procedures within 3 months before study entry were investigated; 63 patients with active CD were enrolled into the follow-up program. Clinical activity was evaluated by the Crohn's disease activity index (CDAI) and serum IL-6 levels measured by enzyme-linked immunosorbent assay.

RESULTS

IL-6 serum levels were significantly elevated in CD patients compared to HD (p < 0.001). In individual patients serum IL-6 levels correlated with corresponding CDAI scores in a subgroup referred to as primarily inflammatory patients presenting without bowel stenosis, previous intestinal resection, or concomitant inflammatory disorders (r = 0.72, p < 0.001). Primarily inflammatory patients displayed higher serum IL-6 levels (median: 6.0 pg/ml; range: 1.3-25) than CD patients with bowel stenosis (median: 2.0; range: 1.3-4.9; p < 0.01) or extensive intestinal resection (median: 1.5; range: 1.3-13.7; p < 0.001). Longitudinally measured serum IL-6 levels reflected the clinical response during steroid therapy and predicted clinical relapse after steroid-induced remission at week 9 of the treatment protocol.

CONCLUSIONS

Serum IL-6 is a clinically relevant parameter for CD that correlates with inflammatory activity and implies a prognostic value after steroid-induced remission.

Interferon-gamma (IFN-gamma)- and tumour necrosis factor (TNF)-induced nitric oxide as toxic effector molecule in chronic dextran sulphate sodium (DSS)-induced colitis in mice

Excess nitric oxide formation caused by the activity of the inducible nitric oxide synthase has been implicated as a toxic effector molecule in the pathogenesis of experimental colitis and inflammatory bowel disease. It was therefore investigated whether inhibition of this synthase or the cytokines TNF and IFN-gamma, inducers of nitric oxide synthase, had effects on chronic colitis in mice. Chronic colitis was induced in mice by repeated feeding of DSS. Cytokines were neutralized by treatment with MoAbs and nitric oxide synthase was inhibited by aminoguanidine. The degree of colonic inflammation was assessed by a histological score and colon length. Aminoguanidine treatment reduced nitric oxide activity by 60% (P = 0. 0004), the histological score by 31% (P = 0.005) and increased colon length by 1.4 cm (P = 0.002). Neutralization of TNF and IFN-gamma resulted in increased colon length (0.7 cm, P = 0.07 and 0.8 cm, P = 0.03), improved histological score (19%, P = 0.045 and 25%, P = 0. 013), and reduced nitric oxide activity (31%, P = 0.07 and 54%, P = 0.004) compared with controls. The combination of anti-cytokine treatments had additive effects. TNF and IFN-gamma are involved in perpetuation of chronic DSS-induced colitis, and induction of excessive nitric oxide activity could be their common effector mechanism.

Lipopolysaccharide- and proinflammatory cytokine-induced energy production in intestinal and colonic epithelial cell lines

BACKGROUND

Although epithelial cells in ulcerative colitis may be metabolically deficient, it remains unknown whether epithelial cells modulate energy metabolism in inflamed mucosa. The purpose of the present study is to investigate whether inflammatory mediators such as lipopolysaccharide (LPS), interleukin-1beta (IL-1beta), IL-6, and tumor necrosis factor-alpha (TNF-alpha) alter energy metabolism in epithelial cells.

METHODS

Adenosine 5'-triphosphate (ATP) levels in HT29 cells cultured with LPS, IL-1beta, IL-6, or TNF-alpha were measured with high-performance liquid chromatography, using a reversed-phase chromatography column. Cellular and mitochondrial (antimycin A-sensitive) respiration rates were determined polarographically, using a Clark-type oxygen electrode.

RESULTS

When the cells were cultured with LPS, IL-6, and TNF-alpha but not IL-1beta, ATP levels increased significantly at 6 h, followed by a decrease at 24 h. Enhancement of oxygen consumption, which was completely blocked by antimycin A, was also shown at 3 h by the exposure to these substrates.

CONCLUSION

LPS and proinflammatory cytokines induced cellular ATP generated by mitochondrial phosphorylation. An active energy production in epithelial cells on the exposure to inflammatory mediators may be critical for escape from chronic mucosal inflammation.

Mucosal macrophage inflammatory protein-1alpha levels are increased in Helicobacter pylori infection

We examined the relationship between the levels of macrophage inflammatory protein 1alpha (MIP-1alpha) and interleukin-8 (IL-8) in organ cultures of antral mucosal tissues, background gastroduodenal diseases, and grades of histologic gastritis. Significantly higher levels of MIP-1alpha and IL-8 were detected in patients with H. pylori infection than in those without infection. In H. pylori-positive patients, mucosal specimens from patients with peptic ulcer disease showed higher levels of MIP-1alpha and IL-8 than the specimens obtained from patients with erosive gastritis or those from endoscopically normal mucosa, and this was particularly pronounced in patients with duodenal ulcer. There were positive correlations between MIP-1alpha and IL-8 levels and histologic grades of activity, inflammation, and H. pylori density as defined by the Sydney system. However, the degree of association with the inflammatory cell count was different between these two chemokines. MIP-1alpha levels had a stronger association with mononuclear cells than with neutrophils, whereas IL-8 levels showed an association with neutrophils and mononuclear cells to an almost equal degree. These results suggest that MIP-1alpha and IL-8 may play important roles as inflammatory mediators in the pathogenesis of histologically proven H. pylori-associated gastritis.

Mucosal macrophage inflammatory protein-1alpha activity in Helicobacter pylori infection

Mucosal chemokines are considered to be important in the pathogenesis of Helicobacter pylori-associated gastritis. The aims of this study are to examine the levels of macrophage inflammatory protein-1alpha (MIP-1alpha) in organ cultures, the expression of MIP-1alpha mRNA and the cellular source of MIP-1alpha, using the antral mucosal specimens obtained from H. pylori-positive and -negative patients. Enzyme-linked immunosorbent assay was used to measure the levels of MIP-1alpha in organ cultures of mucosal tissues and cell cultures of fractionated mucosal cells. The expression of MIP-1alpha mRNA and protein was analysed in fresh biopsy tissues with reverse transcriptase-polymerase chain reaction (RT-PCR) and double immunofluorescence microscopy, respectively. The mucosal specimens obtained from H. pylori-positive patients exhibited significantly higher values of MIP-1alpha activity in organ cultures with increased numbers of CD68+ macrophages, myeloperoxidase+ neutrophils and mononuclear cells in the lamina propria compared with those from H. pylori-negative patients. The RT-PCR analysis detected MIP-1alpha mRNA in more than 50% of the specimens with H. pylori infection, but not in those without infection. In cell cultures, the macrophage fraction contained substantially higher amounts of MIP-1alpha on a per cell basis than the lymphocyte fraction and MIP-1alpha activity was not detected in cultures of gastric epithelial cells. This observation was also confirmed by a double immunofluorescence microscopic study in which most (>90%) MIP-1alpha-positive infiltrating cells were CD68+ macrophages. This study indicates that synthesis and secretion of MIP-1alpha are increased in H. pylori-infected antral mucosa and that mucosal macrophages are the main cell type responsible for this phenomenon.

Increased mucosal production of granulocyte colony-stimulating factor is related to a delay in neutrophil apoptosis in Inflammatory Bowel disease

Tissue accumulation of polymorphonuclear neutrophils (PMN) in Inflammatory Bowel disease (IBD) might be, in part, due to a delay in apoptotic processes associated with the effects of their specific growth factors and inflammatory cytokines. We addressed this hypothesis by examining the activity of granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage CSF (GM-CSF) in the organ culture supernatants of colonic mucosal specimens and their regulatory effects on PMN apoptosis in patients with IBD. The contents of G-CSF and GM-CSF in the supernatants were measured by the enzyme-linked immunosorbent assays and PMN apoptosis was evaluated by acridine orange/ethidium bromide staining, respectively. Mucosal specimens obtained from patients with active IBD exhibited higher levels of G-CSF and GM-CSF activity than controls. Notably, the levels of G-CSF activity were approximately 1000-fold higher than those of GM-CSF activity. Freshly isolated PMN showed a time-related increase in the proportion of cells with characteristic features of apoptosis when they were incubated with the culture medium alone and exposure of PMN to recombinant G-CSF and GM-CSF caused a concentration-dependent inhibition of apoptosis. Incubation of PMN with the supernatants from patients with active IBD induced an inhibitory effect on PMN apoptosis; this effect was abrogated to a significant degree by pre-incubation of the supernatants with anti-G-CSF serum. This study suggests that PMN apoptosis may be delayed under the influence of soluble mediators, especially G-CSF, in the microenvironment of IBD-affected mucosa, thus providing possible mechanisms for tissue accumulation of PMN in IBD.

Differential normalization of mucosal interleukin-8 and interleukin-6 activity after Helicobacter pylori eradication

There is differential resolution of mucosal infiltration with neutrophils and mononuclear cells following successful Helicobacter pylori eradication. We investigated the effects of H. pylori eradication on mucosal interleukin-8 (IL-8) and IL-6 activity in relation to the resolution of H. pylori-associated gastritis. Eighty-one duodenal ulcer patients with H. pylori infection received dual- or triple-treatment eradication therapy, and mucosal biopsy specimens obtained at the initial and follow-up endoscopic examinations were cultured in vitro for 24 h. The levels of IL-8 and IL-6 were measured by enzyme-linked immunosorbent assays. In the 42 patients in whom H. pylori eradication failed, there was little change in the numbers of neutrophils and mononuclear cells infiltrating the mucosa and in IL-8 and IL-6 activity. In the 39 patients in whom H. pylori was eradicated, there was normalization both in the numbers of infiltrating neutrophils and in mucosal IL-8 activity, which was evident within 1 month following therapy. In contrast, there was a gradual resolution of mononuclear cell infiltration over a 6-month period, accompanied by a gradual normalization in IL-6 levels. Addition of H. pylori to cultures of mucosal tissues induced a significant increase in IL-8 activity in both uninfected control subjects and patients from whom H. pylori was eradicated. However, this introduction yielded a significant increase in IL-6 activity only in the latter group. This study indicates a dichotomy in the changes of mucosal IL-8 and IL-6 activity after H. pylori eradication. The rapid normalization of IL-8 after H. pylori eradication and the ability of H. pylori cells to stimulate IL-8 in control tissues indicate that IL-8 induction is a part of the innate (nonimmune) responses to this organism. In contrast, the results of experiments analyzing IL-6 activity in cultured mucosal tissues suggest that the gradual resolution of mucosal IL-6 activity and mononuclear infiltration after successful eradication observed in vivo may reflect gradually diminishing residual immune responses against H. pylori.

Factors affecting Caco-2 intestinal epithelial cell interleukin-6 secretion

Intestinal epithelial cells (IEC) have previously been shown to produce several cytokines including interleukin-6 (IL-6). However, many factors which may regulate IL-6 secretion by human IEC still remain a mystery due in part to the lack of appropriate model cell lines and the difficulty of culturing human IEC over long periods of time. We have determined that the human colonic carcinoma cell line Caco-2 is capable of secreting IL-6 when stimulated by the inflammatory cytokines IL-1beta or tumor necrosis factor-alpha (TNF-alpha), and stimulation of these cells with IL-1beta plus TNF-alpha induced a synergistic enhancement of IL-6 secretion. The inflammatory cytokine-induced enhancement in IL-6 secretion was greatest when the cells were cultured in a 10% CO2 atmosphere as compared to cells grown in 5% CO2, suggesting that environmental CO2 levels may affect IEC cytokine secretion. Finally, long-term culture of the Caco-2 cells to induce cellular differentiation had no effect on the capacity of these cells to produce IL-6, indicating that the regulation of IL-6 secretion was not affected by differentiation. Taken together, these studies provide important information on the factors which regulate IL-6 secretion by human IEC as they may contribute to the cytokine network during a mucosal inflammation. The results also suggest that the Caco-2 cell line is an appropriate model for further studies on the regulation of cytokine secretion by human IEC.

Nuclear factor kappaB is activated in macrophages and epithelial cells of inflamed intestinal mucosa

BACKGROUND & AIMS

Transcription factors of the nuclear factor kappaB (NF-kappaB) family play an important role in the regulation of genes involved in inflammation. In inflammatory bowel diseases, proinflammatory cytokines known to be regulated by NF-kappaB are involved. The aim of this study was to investigate the role of NF-kappaB activation during mucosal inflammation in situ.

METHODS

A monoclonal antibody, alpha-p65mAb, was applied for immunofluorescence and immunohistochemical analysis that recognizes activated NF-kappaB. Electrophoretic mobility shift assay was used to directly demonstrate the presence of active DNA-binding NF-kappaB.

RESULTS

Using the alpha-p65mAb antibody, activated NF-kappaB could be found in biopsy specimens from inflamed mucosa but was almost absent in uninflamed mucosa. The number of cells showing NF-kappaB activation correlated with the degree of mucosal inflammation but was not significantly different between inflamed mucosa from patients with Crohn's disease, ulcerative colitis, and nonspecific colitis or diverticulitis. NF-kappaB activation was localized in macrophages and in epithelial cells as identified by double-labeling techniques. Electrophoretic mobility shift assay with isolated lamina propria mononuclear cells and epithelial cells confirmed these results.

CONCLUSIONS

This study shows for the first time the activation of NF-kappaB during human mucosal inflammation in situ. In addition to macrophages, epithelial cells contained activated NF-kappaB, indicating an involvement in the inflammatory process.